Update to tengo v2 (#976)

187 files changed, 11390 insertions, 11809 deletions

diff --git a/vendor/github.com/d5/tengo/.travis.yml b/vendor/github.com/d5/tengo/.travis.yml
deleted file mode 100644
index 57986ae9..00000000
--- a/vendor/github.com/d5/tengo/.travis.yml
+++ /dev/null
@@ -1,17 +0,0 @@
-language: go
-
-go:
-  - "1.12"
-
-install:
-  - env GO111MODULE=on go get -u golang.org/x/lint/golint
-
-script:
-  - env GO111MODULE=on make test
-
-deploy:
-  - provider: script
-    skip_cleanup: true
-    script: curl -sL https://git.io/goreleaser | bash
-    on:
-      tags: true
\ No newline at end of file
diff --git a/vendor/github.com/d5/tengo/compiler/ast/array_lit.go b/vendor/github.com/d5/tengo/compiler/ast/array_lit.go
deleted file mode 100644
index 9fb4ed67..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/array_lit.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package ast
-
-import (
-	"strings"
-
-	"github.com/d5/tengo/compiler/source"
-)
-
-// ArrayLit represents an array literal.
-type ArrayLit struct {
-	Elements []Expr
-	LBrack   source.Pos
-	RBrack   source.Pos
-}
-
-func (e *ArrayLit) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *ArrayLit) Pos() source.Pos {
-	return e.LBrack
-}
-
-// End returns the position of first character immediately after the node.
-func (e *ArrayLit) End() source.Pos {
-	return e.RBrack + 1
-}
-
-func (e *ArrayLit) String() string {
-	var elements []string
-	for _, m := range e.Elements {
-		elements = append(elements, m.String())
-	}
-
-	return "[" + strings.Join(elements, ", ") + "]"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/assign_stmt.go b/vendor/github.com/d5/tengo/compiler/ast/assign_stmt.go
deleted file mode 100644
index e129114e..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/assign_stmt.go
+++ /dev/null
@@ -1,40 +0,0 @@
-package ast
-
-import (
-	"strings"
-
-	"github.com/d5/tengo/compiler/source"
-	"github.com/d5/tengo/compiler/token"
-)
-
-// AssignStmt represents an assignment statement.
-type AssignStmt struct {
-	LHS      []Expr
-	RHS      []Expr
-	Token    token.Token
-	TokenPos source.Pos
-}
-
-func (s *AssignStmt) stmtNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (s *AssignStmt) Pos() source.Pos {
-	return s.LHS[0].Pos()
-}
-
-// End returns the position of first character immediately after the node.
-func (s *AssignStmt) End() source.Pos {
-	return s.RHS[len(s.RHS)-1].End()
-}
-
-func (s *AssignStmt) String() string {
-	var lhs, rhs []string
-	for _, e := range s.LHS {
-		lhs = append(lhs, e.String())
-	}
-	for _, e := range s.RHS {
-		rhs = append(rhs, e.String())
-	}
-
-	return strings.Join(lhs, ", ") + " " + s.Token.String() + " " + strings.Join(rhs, ", ")
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/ast.go b/vendor/github.com/d5/tengo/compiler/ast/ast.go
deleted file mode 100644
index 9fd06728..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/ast.go
+++ /dev/null
@@ -1,5 +0,0 @@
-package ast
-
-const (
-	nullRep = "<null>"
-)
diff --git a/vendor/github.com/d5/tengo/compiler/ast/bad_expr.go b/vendor/github.com/d5/tengo/compiler/ast/bad_expr.go
deleted file mode 100644
index 771f26fd..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/bad_expr.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// BadExpr represents a bad expression.
-type BadExpr struct {
-	From source.Pos
-	To   source.Pos
-}
-
-func (e *BadExpr) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *BadExpr) Pos() source.Pos {
-	return e.From
-}
-
-// End returns the position of first character immediately after the node.
-func (e *BadExpr) End() source.Pos {
-	return e.To
-}
-
-func (e *BadExpr) String() string {
-	return "<bad expression>"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/bad_stmt.go b/vendor/github.com/d5/tengo/compiler/ast/bad_stmt.go
deleted file mode 100644
index c2d0ae9a..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/bad_stmt.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// BadStmt represents a bad statement.
-type BadStmt struct {
-	From source.Pos
-	To   source.Pos
-}
-
-func (s *BadStmt) stmtNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (s *BadStmt) Pos() source.Pos {
-	return s.From
-}
-
-// End returns the position of first character immediately after the node.
-func (s *BadStmt) End() source.Pos {
-	return s.To
-}
-
-func (s *BadStmt) String() string {
-	return "<bad statement>"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/binary_expr.go b/vendor/github.com/d5/tengo/compiler/ast/binary_expr.go
deleted file mode 100644
index 0cc5bba8..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/binary_expr.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package ast
-
-import (
-	"github.com/d5/tengo/compiler/source"
-	"github.com/d5/tengo/compiler/token"
-)
-
-// BinaryExpr represents a binary operator expression.
-type BinaryExpr struct {
-	LHS      Expr
-	RHS      Expr
-	Token    token.Token
-	TokenPos source.Pos
-}
-
-func (e *BinaryExpr) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *BinaryExpr) Pos() source.Pos {
-	return e.LHS.Pos()
-}
-
-// End returns the position of first character immediately after the node.
-func (e *BinaryExpr) End() source.Pos {
-	return e.RHS.End()
-}
-
-func (e *BinaryExpr) String() string {
-	return "(" + e.LHS.String() + " " + e.Token.String() + " " + e.RHS.String() + ")"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/block_stmt.go b/vendor/github.com/d5/tengo/compiler/ast/block_stmt.go
deleted file mode 100644
index 9bde9fa3..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/block_stmt.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package ast
-
-import (
-	"strings"
-
-	"github.com/d5/tengo/compiler/source"
-)
-
-// BlockStmt represents a block statement.
-type BlockStmt struct {
-	Stmts  []Stmt
-	LBrace source.Pos
-	RBrace source.Pos
-}
-
-func (s *BlockStmt) stmtNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (s *BlockStmt) Pos() source.Pos {
-	return s.LBrace
-}
-
-// End returns the position of first character immediately after the node.
-func (s *BlockStmt) End() source.Pos {
-	return s.RBrace + 1
-}
-
-func (s *BlockStmt) String() string {
-	var list []string
-	for _, e := range s.Stmts {
-		list = append(list, e.String())
-	}
-
-	return "{" + strings.Join(list, "; ") + "}"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/bool_lit.go b/vendor/github.com/d5/tengo/compiler/ast/bool_lit.go
deleted file mode 100644
index e667a5c8..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/bool_lit.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// BoolLit represents a boolean literal.
-type BoolLit struct {
-	Value    bool
-	ValuePos source.Pos
-	Literal  string
-}
-
-func (e *BoolLit) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *BoolLit) Pos() source.Pos {
-	return e.ValuePos
-}
-
-// End returns the position of first character immediately after the node.
-func (e *BoolLit) End() source.Pos {
-	return source.Pos(int(e.ValuePos) + len(e.Literal))
-}
-
-func (e *BoolLit) String() string {
-	return e.Literal
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/branch_stmt.go b/vendor/github.com/d5/tengo/compiler/ast/branch_stmt.go
deleted file mode 100644
index f6c7fdea..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/branch_stmt.go
+++ /dev/null
@@ -1,38 +0,0 @@
-package ast
-
-import (
-	"github.com/d5/tengo/compiler/source"
-	"github.com/d5/tengo/compiler/token"
-)
-
-// BranchStmt represents a branch statement.
-type BranchStmt struct {
-	Token    token.Token
-	TokenPos source.Pos
-	Label    *Ident
-}
-
-func (s *BranchStmt) stmtNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (s *BranchStmt) Pos() source.Pos {
-	return s.TokenPos
-}
-
-// End returns the position of first character immediately after the node.
-func (s *BranchStmt) End() source.Pos {
-	if s.Label != nil {
-		return s.Label.End()
-	}
-
-	return source.Pos(int(s.TokenPos) + len(s.Token.String()))
-}
-
-func (s *BranchStmt) String() string {
-	var label string
-	if s.Label != nil {
-		label = " " + s.Label.Name
-	}
-
-	return s.Token.String() + label
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/call_expr.go b/vendor/github.com/d5/tengo/compiler/ast/call_expr.go
deleted file mode 100644
index 0219d7c9..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/call_expr.go
+++ /dev/null
@@ -1,36 +0,0 @@
-package ast
-
-import (
-	"strings"
-
-	"github.com/d5/tengo/compiler/source"
-)
-
-// CallExpr represents a function call expression.
-type CallExpr struct {
-	Func   Expr
-	LParen source.Pos
-	Args   []Expr
-	RParen source.Pos
-}
-
-func (e *CallExpr) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *CallExpr) Pos() source.Pos {
-	return e.Func.Pos()
-}
-
-// End returns the position of first character immediately after the node.
-func (e *CallExpr) End() source.Pos {
-	return e.RParen + 1
-}
-
-func (e *CallExpr) String() string {
-	var args []string
-	for _, e := range e.Args {
-		args = append(args, e.String())
-	}
-
-	return e.Func.String() + "(" + strings.Join(args, ", ") + ")"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/char_lit.go b/vendor/github.com/d5/tengo/compiler/ast/char_lit.go
deleted file mode 100644
index 592f8744..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/char_lit.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// CharLit represents a character literal.
-type CharLit struct {
-	Value    rune
-	ValuePos source.Pos
-	Literal  string
-}
-
-func (e *CharLit) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *CharLit) Pos() source.Pos {
-	return e.ValuePos
-}
-
-// End returns the position of first character immediately after the node.
-func (e *CharLit) End() source.Pos {
-	return source.Pos(int(e.ValuePos) + len(e.Literal))
-}
-
-func (e *CharLit) String() string {
-	return e.Literal
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/cond_expr.go b/vendor/github.com/d5/tengo/compiler/ast/cond_expr.go
deleted file mode 100644
index bb1db849..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/cond_expr.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package ast
-
-import (
-	"github.com/d5/tengo/compiler/source"
-)
-
-// CondExpr represents a ternary conditional expression.
-type CondExpr struct {
-	Cond        Expr
-	True        Expr
-	False       Expr
-	QuestionPos source.Pos
-	ColonPos    source.Pos
-}
-
-func (e *CondExpr) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *CondExpr) Pos() source.Pos {
-	return e.Cond.Pos()
-}
-
-// End returns the position of first character immediately after the node.
-func (e *CondExpr) End() source.Pos {
-	return e.False.End()
-}
-
-func (e *CondExpr) String() string {
-	return "(" + e.Cond.String() + " ? " + e.True.String() + " : " + e.False.String() + ")"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/empty_stmt.go b/vendor/github.com/d5/tengo/compiler/ast/empty_stmt.go
deleted file mode 100644
index a2ac6ffe..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/empty_stmt.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// EmptyStmt represents an empty statement.
-type EmptyStmt struct {
-	Semicolon source.Pos
-	Implicit  bool
-}
-
-func (s *EmptyStmt) stmtNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (s *EmptyStmt) Pos() source.Pos {
-	return s.Semicolon
-}
-
-// End returns the position of first character immediately after the node.
-func (s *EmptyStmt) End() source.Pos {
-	if s.Implicit {
-		return s.Semicolon
-	}
-
-	return s.Semicolon + 1
-}
-
-func (s *EmptyStmt) String() string {
-	return ";"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/error_expr.go b/vendor/github.com/d5/tengo/compiler/ast/error_expr.go
deleted file mode 100644
index 7ce5667e..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/error_expr.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package ast
-
-import (
-	"github.com/d5/tengo/compiler/source"
-)
-
-// ErrorExpr represents an error expression
-type ErrorExpr struct {
-	Expr     Expr
-	ErrorPos source.Pos
-	LParen   source.Pos
-	RParen   source.Pos
-}
-
-func (e *ErrorExpr) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *ErrorExpr) Pos() source.Pos {
-	return e.ErrorPos
-}
-
-// End returns the position of first character immediately after the node.
-func (e *ErrorExpr) End() source.Pos {
-	return e.RParen
-}
-
-func (e *ErrorExpr) String() string {
-	return "error(" + e.Expr.String() + ")"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/export_stmt.go b/vendor/github.com/d5/tengo/compiler/ast/export_stmt.go
deleted file mode 100644
index 64eb7606..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/export_stmt.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package ast
-
-import (
-	"github.com/d5/tengo/compiler/source"
-)
-
-// ExportStmt represents an export statement.
-type ExportStmt struct {
-	ExportPos source.Pos
-	Result    Expr
-}
-
-func (s *ExportStmt) stmtNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (s *ExportStmt) Pos() source.Pos {
-	return s.ExportPos
-}
-
-// End returns the position of first character immediately after the node.
-func (s *ExportStmt) End() source.Pos {
-	return s.Result.End()
-}
-
-func (s *ExportStmt) String() string {
-	return "export " + s.Result.String()
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/expr.go b/vendor/github.com/d5/tengo/compiler/ast/expr.go
deleted file mode 100644
index 764bacec..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/expr.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package ast
-
-// Expr represents an expression node in the AST.
-type Expr interface {
-	Node
-	exprNode()
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/expr_stmt.go b/vendor/github.com/d5/tengo/compiler/ast/expr_stmt.go
deleted file mode 100644
index 095a3ad5..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/expr_stmt.go
+++ /dev/null
@@ -1,24 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// ExprStmt represents an expression statement.
-type ExprStmt struct {
-	Expr Expr
-}
-
-func (s *ExprStmt) stmtNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (s *ExprStmt) Pos() source.Pos {
-	return s.Expr.Pos()
-}
-
-// End returns the position of first character immediately after the node.
-func (s *ExprStmt) End() source.Pos {
-	return s.Expr.End()
-}
-
-func (s *ExprStmt) String() string {
-	return s.Expr.String()
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/float_lit.go b/vendor/github.com/d5/tengo/compiler/ast/float_lit.go
deleted file mode 100644
index 670f744b..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/float_lit.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// FloatLit represents a floating point literal.
-type FloatLit struct {
-	Value    float64
-	ValuePos source.Pos
-	Literal  string
-}
-
-func (e *FloatLit) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *FloatLit) Pos() source.Pos {
-	return e.ValuePos
-}
-
-// End returns the position of first character immediately after the node.
-func (e *FloatLit) End() source.Pos {
-	return source.Pos(int(e.ValuePos) + len(e.Literal))
-}
-
-func (e *FloatLit) String() string {
-	return e.Literal
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/for_in_stmt.go b/vendor/github.com/d5/tengo/compiler/ast/for_in_stmt.go
deleted file mode 100644
index 18020b56..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/for_in_stmt.go
+++ /dev/null
@@ -1,32 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// ForInStmt represents a for-in statement.
-type ForInStmt struct {
-	ForPos   source.Pos
-	Key      *Ident
-	Value    *Ident
-	Iterable Expr
-	Body     *BlockStmt
-}
-
-func (s *ForInStmt) stmtNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (s *ForInStmt) Pos() source.Pos {
-	return s.ForPos
-}
-
-// End returns the position of first character immediately after the node.
-func (s *ForInStmt) End() source.Pos {
-	return s.Body.End()
-}
-
-func (s *ForInStmt) String() string {
-	if s.Value != nil {
-		return "for " + s.Key.String() + ", " + s.Value.String() + " in " + s.Iterable.String() + " " + s.Body.String()
-	}
-
-	return "for " + s.Key.String() + " in " + s.Iterable.String() + " " + s.Body.String()
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/for_stmt.go b/vendor/github.com/d5/tengo/compiler/ast/for_stmt.go
deleted file mode 100644
index 4b5a0a17..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/for_stmt.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// ForStmt represents a for statement.
-type ForStmt struct {
-	ForPos source.Pos
-	Init   Stmt
-	Cond   Expr
-	Post   Stmt
-	Body   *BlockStmt
-}
-
-func (s *ForStmt) stmtNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (s *ForStmt) Pos() source.Pos {
-	return s.ForPos
-}
-
-// End returns the position of first character immediately after the node.
-func (s *ForStmt) End() source.Pos {
-	return s.Body.End()
-}
-
-func (s *ForStmt) String() string {
-	var init, cond, post string
-	if s.Init != nil {
-		init = s.Init.String()
-	}
-	if s.Cond != nil {
-		cond = s.Cond.String() + " "
-	}
-	if s.Post != nil {
-		post = s.Post.String()
-	}
-
-	if init != "" || post != "" {
-		return "for " + init + " ; " + cond + " ; " + post + s.Body.String()
-	}
-
-	return "for " + cond + s.Body.String()
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/func_lit.go b/vendor/github.com/d5/tengo/compiler/ast/func_lit.go
deleted file mode 100644
index 2e90ed2b..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/func_lit.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// FuncLit represents a function literal.
-type FuncLit struct {
-	Type *FuncType
-	Body *BlockStmt
-}
-
-func (e *FuncLit) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *FuncLit) Pos() source.Pos {
-	return e.Type.Pos()
-}
-
-// End returns the position of first character immediately after the node.
-func (e *FuncLit) End() source.Pos {
-	return e.Body.End()
-}
-
-func (e *FuncLit) String() string {
-	return "func" + e.Type.Params.String() + " " + e.Body.String()
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/func_type.go b/vendor/github.com/d5/tengo/compiler/ast/func_type.go
deleted file mode 100644
index 2afaabb1..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/func_type.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// FuncType represents a function type definition.
-type FuncType struct {
-	FuncPos source.Pos
-	Params  *IdentList
-}
-
-func (e *FuncType) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *FuncType) Pos() source.Pos {
-	return e.FuncPos
-}
-
-// End returns the position of first character immediately after the node.
-func (e *FuncType) End() source.Pos {
-	return e.Params.End()
-}
-
-func (e *FuncType) String() string {
-	return "func" + e.Params.String()
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/ident.go b/vendor/github.com/d5/tengo/compiler/ast/ident.go
deleted file mode 100644
index 33b7ff76..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/ident.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// Ident represents an identifier.
-type Ident struct {
-	Name    string
-	NamePos source.Pos
-}
-
-func (e *Ident) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *Ident) Pos() source.Pos {
-	return e.NamePos
-}
-
-// End returns the position of first character immediately after the node.
-func (e *Ident) End() source.Pos {
-	return source.Pos(int(e.NamePos) + len(e.Name))
-}
-
-func (e *Ident) String() string {
-	if e != nil {
-		return e.Name
-	}
-
-	return nullRep
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/if_stmt.go b/vendor/github.com/d5/tengo/compiler/ast/if_stmt.go
deleted file mode 100644
index b3d65606..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/if_stmt.go
+++ /dev/null
@@ -1,40 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// IfStmt represents an if statement.
-type IfStmt struct {
-	IfPos source.Pos
-	Init  Stmt
-	Cond  Expr
-	Body  *BlockStmt
-	Else  Stmt // else branch; or nil
-}
-
-func (s *IfStmt) stmtNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (s *IfStmt) Pos() source.Pos {
-	return s.IfPos
-}
-
-// End returns the position of first character immediately after the node.
-func (s *IfStmt) End() source.Pos {
-	if s.Else != nil {
-		return s.Else.End()
-	}
-
-	return s.Body.End()
-}
-
-func (s *IfStmt) String() string {
-	var initStmt, elseStmt string
-	if s.Init != nil {
-		initStmt = s.Init.String() + "; "
-	}
-	if s.Else != nil {
-		elseStmt = " else " + s.Else.String()
-	}
-
-	return "if " + initStmt + s.Cond.String() + " " + s.Body.String() + elseStmt
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/immutable_expr.go b/vendor/github.com/d5/tengo/compiler/ast/immutable_expr.go
deleted file mode 100644
index f9843b50..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/immutable_expr.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package ast
-
-import (
-	"github.com/d5/tengo/compiler/source"
-)
-
-// ImmutableExpr represents an immutable expression
-type ImmutableExpr struct {
-	Expr     Expr
-	ErrorPos source.Pos
-	LParen   source.Pos
-	RParen   source.Pos
-}
-
-func (e *ImmutableExpr) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *ImmutableExpr) Pos() source.Pos {
-	return e.ErrorPos
-}
-
-// End returns the position of first character immediately after the node.
-func (e *ImmutableExpr) End() source.Pos {
-	return e.RParen
-}
-
-func (e *ImmutableExpr) String() string {
-	return "immutable(" + e.Expr.String() + ")"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/import_expr.go b/vendor/github.com/d5/tengo/compiler/ast/import_expr.go
deleted file mode 100644
index 6eff74a9..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/import_expr.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package ast
-
-import (
-	"github.com/d5/tengo/compiler/source"
-	"github.com/d5/tengo/compiler/token"
-)
-
-// ImportExpr represents an import expression
-type ImportExpr struct {
-	ModuleName string
-	Token      token.Token
-	TokenPos   source.Pos
-}
-
-func (e *ImportExpr) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *ImportExpr) Pos() source.Pos {
-	return e.TokenPos
-}
-
-// End returns the position of first character immediately after the node.
-func (e *ImportExpr) End() source.Pos {
-	return source.Pos(int(e.TokenPos) + 10 + len(e.ModuleName)) // import("moduleName")
-}
-
-func (e *ImportExpr) String() string {
-	return `import("` + e.ModuleName + `")"`
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/inc_dec_stmt.go b/vendor/github.com/d5/tengo/compiler/ast/inc_dec_stmt.go
deleted file mode 100644
index e4e7f92c..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/inc_dec_stmt.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package ast
-
-import (
-	"github.com/d5/tengo/compiler/source"
-	"github.com/d5/tengo/compiler/token"
-)
-
-// IncDecStmt represents increment or decrement statement.
-type IncDecStmt struct {
-	Expr     Expr
-	Token    token.Token
-	TokenPos source.Pos
-}
-
-func (s *IncDecStmt) stmtNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (s *IncDecStmt) Pos() source.Pos {
-	return s.Expr.Pos()
-}
-
-// End returns the position of first character immediately after the node.
-func (s *IncDecStmt) End() source.Pos {
-	return source.Pos(int(s.TokenPos) + 2)
-}
-
-func (s *IncDecStmt) String() string {
-	return s.Expr.String() + s.Token.String()
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/index_expr.go b/vendor/github.com/d5/tengo/compiler/ast/index_expr.go
deleted file mode 100644
index bc0992a3..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/index_expr.go
+++ /dev/null
@@ -1,32 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// IndexExpr represents an index expression.
-type IndexExpr struct {
-	Expr   Expr
-	LBrack source.Pos
-	Index  Expr
-	RBrack source.Pos
-}
-
-func (e *IndexExpr) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *IndexExpr) Pos() source.Pos {
-	return e.Expr.Pos()
-}
-
-// End returns the position of first character immediately after the node.
-func (e *IndexExpr) End() source.Pos {
-	return e.RBrack + 1
-}
-
-func (e *IndexExpr) String() string {
-	var index string
-	if e.Index != nil {
-		index = e.Index.String()
-	}
-
-	return e.Expr.String() + "[" + index + "]"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/int_lit.go b/vendor/github.com/d5/tengo/compiler/ast/int_lit.go
deleted file mode 100644
index 3e1fd98b..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/int_lit.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// IntLit represents an integer literal.
-type IntLit struct {
-	Value    int64
-	ValuePos source.Pos
-	Literal  string
-}
-
-func (e *IntLit) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *IntLit) Pos() source.Pos {
-	return e.ValuePos
-}
-
-// End returns the position of first character immediately after the node.
-func (e *IntLit) End() source.Pos {
-	return source.Pos(int(e.ValuePos) + len(e.Literal))
-}
-
-func (e *IntLit) String() string {
-	return e.Literal
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/map_element_lit.go b/vendor/github.com/d5/tengo/compiler/ast/map_element_lit.go
deleted file mode 100644
index 3d7fca9e..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/map_element_lit.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// MapElementLit represents a map element.
-type MapElementLit struct {
-	Key      string
-	KeyPos   source.Pos
-	ColonPos source.Pos
-	Value    Expr
-}
-
-func (e *MapElementLit) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *MapElementLit) Pos() source.Pos {
-	return e.KeyPos
-}
-
-// End returns the position of first character immediately after the node.
-func (e *MapElementLit) End() source.Pos {
-	return e.Value.End()
-}
-
-func (e *MapElementLit) String() string {
-	return e.Key + ": " + e.Value.String()
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/map_lit.go b/vendor/github.com/d5/tengo/compiler/ast/map_lit.go
deleted file mode 100644
index a228224d..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/map_lit.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package ast
-
-import (
-	"strings"
-
-	"github.com/d5/tengo/compiler/source"
-)
-
-// MapLit represents a map literal.
-type MapLit struct {
-	LBrace   source.Pos
-	Elements []*MapElementLit
-	RBrace   source.Pos
-}
-
-func (e *MapLit) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *MapLit) Pos() source.Pos {
-	return e.LBrace
-}
-
-// End returns the position of first character immediately after the node.
-func (e *MapLit) End() source.Pos {
-	return e.RBrace + 1
-}
-
-func (e *MapLit) String() string {
-	var elements []string
-	for _, m := range e.Elements {
-		elements = append(elements, m.String())
-	}
-
-	return "{" + strings.Join(elements, ", ") + "}"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/node.go b/vendor/github.com/d5/tengo/compiler/ast/node.go
deleted file mode 100644
index 44677b47..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/node.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// Node represents a node in the AST.
-type Node interface {
-	// Pos returns the position of first character belonging to the node.
-	Pos() source.Pos
-	// End returns the position of first character immediately after the node.
-	End() source.Pos
-	// String returns a string representation of the node.
-	String() string
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/paren_expr.go b/vendor/github.com/d5/tengo/compiler/ast/paren_expr.go
deleted file mode 100644
index 8db4ac02..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/paren_expr.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// ParenExpr represents a parenthesis wrapped expression.
-type ParenExpr struct {
-	Expr   Expr
-	LParen source.Pos
-	RParen source.Pos
-}
-
-func (e *ParenExpr) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *ParenExpr) Pos() source.Pos {
-	return e.LParen
-}
-
-// End returns the position of first character immediately after the node.
-func (e *ParenExpr) End() source.Pos {
-	return e.RParen + 1
-}
-
-func (e *ParenExpr) String() string {
-	return "(" + e.Expr.String() + ")"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/return_stmt.go b/vendor/github.com/d5/tengo/compiler/ast/return_stmt.go
deleted file mode 100644
index 592d45b8..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/return_stmt.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package ast
-
-import (
-	"github.com/d5/tengo/compiler/source"
-)
-
-// ReturnStmt represents a return statement.
-type ReturnStmt struct {
-	ReturnPos source.Pos
-	Result    Expr
-}
-
-func (s *ReturnStmt) stmtNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (s *ReturnStmt) Pos() source.Pos {
-	return s.ReturnPos
-}
-
-// End returns the position of first character immediately after the node.
-func (s *ReturnStmt) End() source.Pos {
-	if s.Result != nil {
-		return s.Result.End()
-	}
-
-	return s.ReturnPos + 6
-}
-
-func (s *ReturnStmt) String() string {
-	if s.Result != nil {
-		return "return " + s.Result.String()
-	}
-
-	return "return"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/selector_expr.go b/vendor/github.com/d5/tengo/compiler/ast/selector_expr.go
deleted file mode 100644
index 31d2e6d1..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/selector_expr.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// SelectorExpr represents a selector expression.
-type SelectorExpr struct {
-	Expr Expr
-	Sel  Expr
-}
-
-func (e *SelectorExpr) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *SelectorExpr) Pos() source.Pos {
-	return e.Expr.Pos()
-}
-
-// End returns the position of first character immediately after the node.
-func (e *SelectorExpr) End() source.Pos {
-	return e.Sel.End()
-}
-
-func (e *SelectorExpr) String() string {
-	return e.Expr.String() + "." + e.Sel.String()
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/slice_expr.go b/vendor/github.com/d5/tengo/compiler/ast/slice_expr.go
deleted file mode 100644
index e7e2e05b..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/slice_expr.go
+++ /dev/null
@@ -1,36 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// SliceExpr represents a slice expression.
-type SliceExpr struct {
-	Expr   Expr
-	LBrack source.Pos
-	Low    Expr
-	High   Expr
-	RBrack source.Pos
-}
-
-func (e *SliceExpr) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *SliceExpr) Pos() source.Pos {
-	return e.Expr.Pos()
-}
-
-// End returns the position of first character immediately after the node.
-func (e *SliceExpr) End() source.Pos {
-	return e.RBrack + 1
-}
-
-func (e *SliceExpr) String() string {
-	var low, high string
-	if e.Low != nil {
-		low = e.Low.String()
-	}
-	if e.High != nil {
-		high = e.High.String()
-	}
-
-	return e.Expr.String() + "[" + low + ":" + high + "]"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/stmt.go b/vendor/github.com/d5/tengo/compiler/ast/stmt.go
deleted file mode 100644
index 6b26ba88..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/stmt.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package ast
-
-// Stmt represents a statement in the AST.
-type Stmt interface {
-	Node
-	stmtNode()
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/string_lit.go b/vendor/github.com/d5/tengo/compiler/ast/string_lit.go
deleted file mode 100644
index 2119d34b..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/string_lit.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// StringLit represents a string literal.
-type StringLit struct {
-	Value    string
-	ValuePos source.Pos
-	Literal  string
-}
-
-func (e *StringLit) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *StringLit) Pos() source.Pos {
-	return e.ValuePos
-}
-
-// End returns the position of first character immediately after the node.
-func (e *StringLit) End() source.Pos {
-	return source.Pos(int(e.ValuePos) + len(e.Literal))
-}
-
-func (e *StringLit) String() string {
-	return e.Literal
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/unary_expr.go b/vendor/github.com/d5/tengo/compiler/ast/unary_expr.go
deleted file mode 100644
index 53236146..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/unary_expr.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package ast
-
-import (
-	"github.com/d5/tengo/compiler/source"
-	"github.com/d5/tengo/compiler/token"
-)
-
-// UnaryExpr represents an unary operator expression.
-type UnaryExpr struct {
-	Expr     Expr
-	Token    token.Token
-	TokenPos source.Pos
-}
-
-func (e *UnaryExpr) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *UnaryExpr) Pos() source.Pos {
-	return e.Expr.Pos()
-}
-
-// End returns the position of first character immediately after the node.
-func (e *UnaryExpr) End() source.Pos {
-	return e.Expr.End()
-}
-
-func (e *UnaryExpr) String() string {
-	return "(" + e.Token.String() + e.Expr.String() + ")"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/undefined_lit.go b/vendor/github.com/d5/tengo/compiler/ast/undefined_lit.go
deleted file mode 100644
index 8e51b113..00000000
--- a/vendor/github.com/d5/tengo/compiler/ast/undefined_lit.go
+++ /dev/null
@@ -1,24 +0,0 @@
-package ast
-
-import "github.com/d5/tengo/compiler/source"
-
-// UndefinedLit represents an undefined literal.
-type UndefinedLit struct {
-	TokenPos source.Pos
-}
-
-func (e *UndefinedLit) exprNode() {}
-
-// Pos returns the position of first character belonging to the node.
-func (e *UndefinedLit) Pos() source.Pos {
-	return e.TokenPos
-}
-
-// End returns the position of first character immediately after the node.
-func (e *UndefinedLit) End() source.Pos {
-	return e.TokenPos + 9 // len(undefined) == 9
-}
-
-func (e *UndefinedLit) String() string {
-	return "undefined"
-}
diff --git a/vendor/github.com/d5/tengo/compiler/bytecode.go b/vendor/github.com/d5/tengo/compiler/bytecode.go
deleted file mode 100644
index 35f36c0a..00000000
--- a/vendor/github.com/d5/tengo/compiler/bytecode.go
+++ /dev/null
@@ -1,90 +0,0 @@
-package compiler
-
-import (
-	"encoding/gob"
-	"fmt"
-	"io"
-	"reflect"
-
-	"github.com/d5/tengo/compiler/source"
-	"github.com/d5/tengo/objects"
-)
-
-// Bytecode is a compiled instructions and constants.
-type Bytecode struct {
-	FileSet      *source.FileSet
-	MainFunction *objects.CompiledFunction
-	Constants    []objects.Object
-}
-
-// Encode writes Bytecode data to the writer.
-func (b *Bytecode) Encode(w io.Writer) error {
-	enc := gob.NewEncoder(w)
-
-	if err := enc.Encode(b.FileSet); err != nil {
-		return err
-	}
-
-	if err := enc.Encode(b.MainFunction); err != nil {
-		return err
-	}
-
-	// constants
-	return enc.Encode(b.Constants)
-}
-
-// CountObjects returns the number of objects found in Constants.
-func (b *Bytecode) CountObjects() int {
-	n := 0
-
-	for _, c := range b.Constants {
-		n += objects.CountObjects(c)
-	}
-
-	return n
-}
-
-// FormatInstructions returns human readable string representations of
-// compiled instructions.
-func (b *Bytecode) FormatInstructions() []string {
-	return FormatInstructions(b.MainFunction.Instructions, 0)
-}
-
-// FormatConstants returns human readable string representations of
-// compiled constants.
-func (b *Bytecode) FormatConstants() (output []string) {
-	for cidx, cn := range b.Constants {
-		switch cn := cn.(type) {
-		case *objects.CompiledFunction:
-			output = append(output, fmt.Sprintf("[% 3d] (Compiled Function|%p)", cidx, &cn))
-			for _, l := range FormatInstructions(cn.Instructions, 0) {
-				output = append(output, fmt.Sprintf("     %s", l))
-			}
-		default:
-			output = append(output, fmt.Sprintf("[% 3d] %s (%s|%p)", cidx, cn, reflect.TypeOf(cn).Elem().Name(), &cn))
-		}
-	}
-
-	return
-}
-
-func init() {
-	gob.Register(&source.FileSet{})
-	gob.Register(&source.File{})
-	gob.Register(&objects.Array{})
-	gob.Register(&objects.Bool{})
-	gob.Register(&objects.Bytes{})
-	gob.Register(&objects.Char{})
-	gob.Register(&objects.Closure{})
-	gob.Register(&objects.CompiledFunction{})
-	gob.Register(&objects.Error{})
-	gob.Register(&objects.Float{})
-	gob.Register(&objects.ImmutableArray{})
-	gob.Register(&objects.ImmutableMap{})
-	gob.Register(&objects.Int{})
-	gob.Register(&objects.Map{})
-	gob.Register(&objects.String{})
-	gob.Register(&objects.Time{})
-	gob.Register(&objects.Undefined{})
-	gob.Register(&objects.UserFunction{})
-}
diff --git a/vendor/github.com/d5/tengo/compiler/bytecode_decode.go b/vendor/github.com/d5/tengo/compiler/bytecode_decode.go
deleted file mode 100644
index b3b32a64..00000000
--- a/vendor/github.com/d5/tengo/compiler/bytecode_decode.go
+++ /dev/null
@@ -1,97 +0,0 @@
-package compiler
-
-import (
-	"encoding/gob"
-	"fmt"
-	"io"
-
-	"github.com/d5/tengo/objects"
-)
-
-// Decode reads Bytecode data from the reader.
-func (b *Bytecode) Decode(r io.Reader, modules *objects.ModuleMap) error {
-	if modules == nil {
-		modules = objects.NewModuleMap()
-	}
-
-	dec := gob.NewDecoder(r)
-
-	if err := dec.Decode(&b.FileSet); err != nil {
-		return err
-	}
-	// TODO: files in b.FileSet.File does not have their 'set' field properly set to b.FileSet
-	// as it's private field and not serialized by gob encoder/decoder.
-
-	if err := dec.Decode(&b.MainFunction); err != nil {
-		return err
-	}
-
-	if err := dec.Decode(&b.Constants); err != nil {
-		return err
-	}
-	for i, v := range b.Constants {
-		fv, err := fixDecoded(v, modules)
-		if err != nil {
-			return err
-		}
-		b.Constants[i] = fv
-	}
-
-	return nil
-}
-
-func fixDecoded(o objects.Object, modules *objects.ModuleMap) (objects.Object, error) {
-	switch o := o.(type) {
-	case *objects.Bool:
-		if o.IsFalsy() {
-			return objects.FalseValue, nil
-		}
-		return objects.TrueValue, nil
-	case *objects.Undefined:
-		return objects.UndefinedValue, nil
-	case *objects.Array:
-		for i, v := range o.Value {
-			fv, err := fixDecoded(v, modules)
-			if err != nil {
-				return nil, err
-			}
-			o.Value[i] = fv
-		}
-	case *objects.ImmutableArray:
-		for i, v := range o.Value {
-			fv, err := fixDecoded(v, modules)
-			if err != nil {
-				return nil, err
-			}
-			o.Value[i] = fv
-		}
-	case *objects.Map:
-		for k, v := range o.Value {
-			fv, err := fixDecoded(v, modules)
-			if err != nil {
-				return nil, err
-			}
-			o.Value[k] = fv
-		}
-	case *objects.ImmutableMap:
-		modName := moduleName(o)
-		if mod := modules.GetBuiltinModule(modName); mod != nil {
-			return mod.AsImmutableMap(modName), nil
-		}
-
-		for k, v := range o.Value {
-			// encoding of user function not supported
-			if _, isUserFunction := v.(*objects.UserFunction); isUserFunction {
-				return nil, fmt.Errorf("user function not decodable")
-			}
-
-			fv, err := fixDecoded(v, modules)
-			if err != nil {
-				return nil, err
-			}
-			o.Value[k] = fv
-		}
-	}
-
-	return o, nil
-}
diff --git a/vendor/github.com/d5/tengo/compiler/bytecode_optimize.go b/vendor/github.com/d5/tengo/compiler/bytecode_optimize.go
deleted file mode 100644
index 9526de2e..00000000
--- a/vendor/github.com/d5/tengo/compiler/bytecode_optimize.go
+++ /dev/null
@@ -1,129 +0,0 @@
-package compiler
-
-import (
-	"fmt"
-
-	"github.com/d5/tengo/objects"
-)
-
-// RemoveDuplicates finds and remove the duplicate values in Constants.
-// Note this function mutates Bytecode.
-func (b *Bytecode) RemoveDuplicates() {
-	var deduped []objects.Object
-
-	indexMap := make(map[int]int) // mapping from old constant index to new index
-	ints := make(map[int64]int)
-	strings := make(map[string]int)
-	floats := make(map[float64]int)
-	chars := make(map[rune]int)
-	immutableMaps := make(map[string]int) // for modules
-
-	for curIdx, c := range b.Constants {
-		switch c := c.(type) {
-		case *objects.CompiledFunction:
-			// add to deduped list
-			indexMap[curIdx] = len(deduped)
-			deduped = append(deduped, c)
-		case *objects.ImmutableMap:
-			modName := moduleName(c)
-			newIdx, ok := immutableMaps[modName]
-			if modName != "" && ok {
-				indexMap[curIdx] = newIdx
-			} else {
-				newIdx = len(deduped)
-				immutableMaps[modName] = newIdx
-				indexMap[curIdx] = newIdx
-				deduped = append(deduped, c)
-			}
-		case *objects.Int:
-			if newIdx, ok := ints[c.Value]; ok {
-				indexMap[curIdx] = newIdx
-			} else {
-				newIdx = len(deduped)
-				ints[c.Value] = newIdx
-				indexMap[curIdx] = newIdx
-				deduped = append(deduped, c)
-			}
-		case *objects.String:
-			if newIdx, ok := strings[c.Value]; ok {
-				indexMap[curIdx] = newIdx
-			} else {
-				newIdx = len(deduped)
-				strings[c.Value] = newIdx
-				indexMap[curIdx] = newIdx
-				deduped = append(deduped, c)
-			}
-		case *objects.Float:
-			if newIdx, ok := floats[c.Value]; ok {
-				indexMap[curIdx] = newIdx
-			} else {
-				newIdx = len(deduped)
-				floats[c.Value] = newIdx
-				indexMap[curIdx] = newIdx
-				deduped = append(deduped, c)
-			}
-		case *objects.Char:
-			if newIdx, ok := chars[c.Value]; ok {
-				indexMap[curIdx] = newIdx
-			} else {
-				newIdx = len(deduped)
-				chars[c.Value] = newIdx
-				indexMap[curIdx] = newIdx
-				deduped = append(deduped, c)
-			}
-		default:
-			panic(fmt.Errorf("unsupported top-level constant type: %s", c.TypeName()))
-		}
-	}
-
-	// replace with de-duplicated constants
-	b.Constants = deduped
-
-	// update CONST instructions with new indexes
-	// main function
-	updateConstIndexes(b.MainFunction.Instructions, indexMap)
-	// other compiled functions in constants
-	for _, c := range b.Constants {
-		switch c := c.(type) {
-		case *objects.CompiledFunction:
-			updateConstIndexes(c.Instructions, indexMap)
-		}
-	}
-}
-
-func updateConstIndexes(insts []byte, indexMap map[int]int) {
-	i := 0
-	for i < len(insts) {
-		op := insts[i]
-		numOperands := OpcodeOperands[op]
-		_, read := ReadOperands(numOperands, insts[i+1:])
-
-		switch op {
-		case OpConstant:
-			curIdx := int(insts[i+2]) | int(insts[i+1])<<8
-			newIdx, ok := indexMap[curIdx]
-			if !ok {
-				panic(fmt.Errorf("constant index not found: %d", curIdx))
-			}
-			copy(insts[i:], MakeInstruction(op, newIdx))
-		case OpClosure:
-			curIdx := int(insts[i+2]) | int(insts[i+1])<<8
-			numFree := int(insts[i+3])
-			newIdx, ok := indexMap[curIdx]
-			if !ok {
-				panic(fmt.Errorf("constant index not found: %d", curIdx))
-			}
-			copy(insts[i:], MakeInstruction(op, newIdx, numFree))
-		}
-
-		i += 1 + read
-	}
-}
-
-func moduleName(mod *objects.ImmutableMap) string {
-	if modName, ok := mod.Value["__module_name__"].(*objects.String); ok {
-		return modName.Value
-	}
-
-	return ""
-}
diff --git a/vendor/github.com/d5/tengo/compiler/compilation_scope.go b/vendor/github.com/d5/tengo/compiler/compilation_scope.go
deleted file mode 100644
index 41e7876b..00000000
--- a/vendor/github.com/d5/tengo/compiler/compilation_scope.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package compiler
-
-import "github.com/d5/tengo/compiler/source"
-
-// CompilationScope represents a compiled instructions
-// and the last two instructions that were emitted.
-type CompilationScope struct {
-	instructions []byte
-	symbolInit   map[string]bool
-	sourceMap    map[int]source.Pos
-}
diff --git a/vendor/github.com/d5/tengo/compiler/compiler.go b/vendor/github.com/d5/tengo/compiler/compiler.go
deleted file mode 100644
index 8bde5dc9..00000000
--- a/vendor/github.com/d5/tengo/compiler/compiler.go
+++ /dev/null
@@ -1,846 +0,0 @@
-package compiler
-
-import (
-	"fmt"
-	"io"
-	"io/ioutil"
-	"path/filepath"
-	"reflect"
-	"strings"
-
-	"github.com/d5/tengo"
-	"github.com/d5/tengo/compiler/ast"
-	"github.com/d5/tengo/compiler/source"
-	"github.com/d5/tengo/compiler/token"
-	"github.com/d5/tengo/objects"
-)
-
-// Compiler compiles the AST into a bytecode.
-type Compiler struct {
-	file            *source.File
-	parent          *Compiler
-	modulePath      string
-	constants       []objects.Object
-	symbolTable     *SymbolTable
-	scopes          []CompilationScope
-	scopeIndex      int
-	modules         *objects.ModuleMap
-	compiledModules map[string]*objects.CompiledFunction
-	allowFileImport bool
-	loops           []*Loop
-	loopIndex       int
-	trace           io.Writer
-	indent          int
-}
-
-// NewCompiler creates a Compiler.
-func NewCompiler(file *source.File, symbolTable *SymbolTable, constants []objects.Object, modules *objects.ModuleMap, trace io.Writer) *Compiler {
-	mainScope := CompilationScope{
-		symbolInit: make(map[string]bool),
-		sourceMap:  make(map[int]source.Pos),
-	}
-
-	// symbol table
-	if symbolTable == nil {
-		symbolTable = NewSymbolTable()
-	}
-
-	// add builtin functions to the symbol table
-	for idx, fn := range objects.Builtins {
-		symbolTable.DefineBuiltin(idx, fn.Name)
-	}
-
-	// builtin modules
-	if modules == nil {
-		modules = objects.NewModuleMap()
-	}
-
-	return &Compiler{
-		file:            file,
-		symbolTable:     symbolTable,
-		constants:       constants,
-		scopes:          []CompilationScope{mainScope},
-		scopeIndex:      0,
-		loopIndex:       -1,
-		trace:           trace,
-		modules:         modules,
-		compiledModules: make(map[string]*objects.CompiledFunction),
-	}
-}
-
-// Compile compiles the AST node.
-func (c *Compiler) Compile(node ast.Node) error {
-	if c.trace != nil {
-		if node != nil {
-			defer un(trace(c, fmt.Sprintf("%s (%s)", node.String(), reflect.TypeOf(node).Elem().Name())))
-		} else {
-			defer un(trace(c, "<nil>"))
-		}
-	}
-
-	switch node := node.(type) {
-	case *ast.File:
-		for _, stmt := range node.Stmts {
-			if err := c.Compile(stmt); err != nil {
-				return err
-			}
-		}
-
-	case *ast.ExprStmt:
-		if err := c.Compile(node.Expr); err != nil {
-			return err
-		}
-		c.emit(node, OpPop)
-
-	case *ast.IncDecStmt:
-		op := token.AddAssign
-		if node.Token == token.Dec {
-			op = token.SubAssign
-		}
-
-		return c.compileAssign(node, []ast.Expr{node.Expr}, []ast.Expr{&ast.IntLit{Value: 1}}, op)
-
-	case *ast.ParenExpr:
-		if err := c.Compile(node.Expr); err != nil {
-			return err
-		}
-
-	case *ast.BinaryExpr:
-		if node.Token == token.LAnd || node.Token == token.LOr {
-			return c.compileLogical(node)
-		}
-
-		if node.Token == token.Less {
-			if err := c.Compile(node.RHS); err != nil {
-				return err
-			}
-
-			if err := c.Compile(node.LHS); err != nil {
-				return err
-			}
-
-			c.emit(node, OpBinaryOp, int(token.Greater))
-
-			return nil
-		} else if node.Token == token.LessEq {
-			if err := c.Compile(node.RHS); err != nil {
-				return err
-			}
-			if err := c.Compile(node.LHS); err != nil {
-				return err
-			}
-
-			c.emit(node, OpBinaryOp, int(token.GreaterEq))
-
-			return nil
-		}
-
-		if err := c.Compile(node.LHS); err != nil {
-			return err
-		}
-		if err := c.Compile(node.RHS); err != nil {
-			return err
-		}
-
-		switch node.Token {
-		case token.Add:
-			c.emit(node, OpBinaryOp, int(token.Add))
-		case token.Sub:
-			c.emit(node, OpBinaryOp, int(token.Sub))
-		case token.Mul:
-			c.emit(node, OpBinaryOp, int(token.Mul))
-		case token.Quo:
-			c.emit(node, OpBinaryOp, int(token.Quo))
-		case token.Rem:
-			c.emit(node, OpBinaryOp, int(token.Rem))
-		case token.Greater:
-			c.emit(node, OpBinaryOp, int(token.Greater))
-		case token.GreaterEq:
-			c.emit(node, OpBinaryOp, int(token.GreaterEq))
-		case token.Equal:
-			c.emit(node, OpEqual)
-		case token.NotEqual:
-			c.emit(node, OpNotEqual)
-		case token.And:
-			c.emit(node, OpBinaryOp, int(token.And))
-		case token.Or:
-			c.emit(node, OpBinaryOp, int(token.Or))
-		case token.Xor:
-			c.emit(node, OpBinaryOp, int(token.Xor))
-		case token.AndNot:
-			c.emit(node, OpBinaryOp, int(token.AndNot))
-		case token.Shl:
-			c.emit(node, OpBinaryOp, int(token.Shl))
-		case token.Shr:
-			c.emit(node, OpBinaryOp, int(token.Shr))
-		default:
-			return c.errorf(node, "invalid binary operator: %s", node.Token.String())
-		}
-
-	case *ast.IntLit:
-		c.emit(node, OpConstant, c.addConstant(&objects.Int{Value: node.Value}))
-
-	case *ast.FloatLit:
-		c.emit(node, OpConstant, c.addConstant(&objects.Float{Value: node.Value}))
-
-	case *ast.BoolLit:
-		if node.Value {
-			c.emit(node, OpTrue)
-		} else {
-			c.emit(node, OpFalse)
-		}
-
-	case *ast.StringLit:
-		if len(node.Value) > tengo.MaxStringLen {
-			return c.error(node, objects.ErrStringLimit)
-		}
-
-		c.emit(node, OpConstant, c.addConstant(&objects.String{Value: node.Value}))
-
-	case *ast.CharLit:
-		c.emit(node, OpConstant, c.addConstant(&objects.Char{Value: node.Value}))
-
-	case *ast.UndefinedLit:
-		c.emit(node, OpNull)
-
-	case *ast.UnaryExpr:
-		if err := c.Compile(node.Expr); err != nil {
-			return err
-		}
-
-		switch node.Token {
-		case token.Not:
-			c.emit(node, OpLNot)
-		case token.Sub:
-			c.emit(node, OpMinus)
-		case token.Xor:
-			c.emit(node, OpBComplement)
-		case token.Add:
-			// do nothing?
-		default:
-			return c.errorf(node, "invalid unary operator: %s", node.Token.String())
-		}
-
-	case *ast.IfStmt:
-		// open new symbol table for the statement
-		c.symbolTable = c.symbolTable.Fork(true)
-		defer func() {
-			c.symbolTable = c.symbolTable.Parent(false)
-		}()
-
-		if node.Init != nil {
-			if err := c.Compile(node.Init); err != nil {
-				return err
-			}
-		}
-
-		if err := c.Compile(node.Cond); err != nil {
-			return err
-		}
-
-		// first jump placeholder
-		jumpPos1 := c.emit(node, OpJumpFalsy, 0)
-
-		if err := c.Compile(node.Body); err != nil {
-			return err
-		}
-
-		if node.Else != nil {
-			// second jump placeholder
-			jumpPos2 := c.emit(node, OpJump, 0)
-
-			// update first jump offset
-			curPos := len(c.currentInstructions())
-			c.changeOperand(jumpPos1, curPos)
-
-			if err := c.Compile(node.Else); err != nil {
-				return err
-			}
-
-			// update second jump offset
-			curPos = len(c.currentInstructions())
-			c.changeOperand(jumpPos2, curPos)
-		} else {
-			// update first jump offset
-			curPos := len(c.currentInstructions())
-			c.changeOperand(jumpPos1, curPos)
-		}
-
-	case *ast.ForStmt:
-		return c.compileForStmt(node)
-
-	case *ast.ForInStmt:
-		return c.compileForInStmt(node)
-
-	case *ast.BranchStmt:
-		if node.Token == token.Break {
-			curLoop := c.currentLoop()
-			if curLoop == nil {
-				return c.errorf(node, "break not allowed outside loop")
-			}
-			pos := c.emit(node, OpJump, 0)
-			curLoop.Breaks = append(curLoop.Breaks, pos)
-		} else if node.Token == token.Continue {
-			curLoop := c.currentLoop()
-			if curLoop == nil {
-				return c.errorf(node, "continue not allowed outside loop")
-			}
-			pos := c.emit(node, OpJump, 0)
-			curLoop.Continues = append(curLoop.Continues, pos)
-		} else {
-			panic(fmt.Errorf("invalid branch statement: %s", node.Token.String()))
-		}
-
-	case *ast.BlockStmt:
-		if len(node.Stmts) == 0 {
-			return nil
-		}
-
-		c.symbolTable = c.symbolTable.Fork(true)
-		defer func() {
-			c.symbolTable = c.symbolTable.Parent(false)
-		}()
-
-		for _, stmt := range node.Stmts {
-			if err := c.Compile(stmt); err != nil {
-				return err
-			}
-		}
-
-	case *ast.AssignStmt:
-		if err := c.compileAssign(node, node.LHS, node.RHS, node.Token); err != nil {
-			return err
-		}
-
-	case *ast.Ident:
-		symbol, _, ok := c.symbolTable.Resolve(node.Name)
-		if !ok {
-			return c.errorf(node, "unresolved reference '%s'", node.Name)
-		}
-
-		switch symbol.Scope {
-		case ScopeGlobal:
-			c.emit(node, OpGetGlobal, symbol.Index)
-		case ScopeLocal:
-			c.emit(node, OpGetLocal, symbol.Index)
-		case ScopeBuiltin:
-			c.emit(node, OpGetBuiltin, symbol.Index)
-		case ScopeFree:
-			c.emit(node, OpGetFree, symbol.Index)
-		}
-
-	case *ast.ArrayLit:
-		for _, elem := range node.Elements {
-			if err := c.Compile(elem); err != nil {
-				return err
-			}
-		}
-
-		c.emit(node, OpArray, len(node.Elements))
-
-	case *ast.MapLit:
-		for _, elt := range node.Elements {
-			// key
-			if len(elt.Key) > tengo.MaxStringLen {
-				return c.error(node, objects.ErrStringLimit)
-			}
-			c.emit(node, OpConstant, c.addConstant(&objects.String{Value: elt.Key}))
-
-			// value
-			if err := c.Compile(elt.Value); err != nil {
-				return err
-			}
-		}
-
-		c.emit(node, OpMap, len(node.Elements)*2)
-
-	case *ast.SelectorExpr: // selector on RHS side
-		if err := c.Compile(node.Expr); err != nil {
-			return err
-		}
-
-		if err := c.Compile(node.Sel); err != nil {
-			return err
-		}
-
-		c.emit(node, OpIndex)
-
-	case *ast.IndexExpr:
-		if err := c.Compile(node.Expr); err != nil {
-			return err
-		}
-
-		if err := c.Compile(node.Index); err != nil {
-			return err
-		}
-
-		c.emit(node, OpIndex)
-
-	case *ast.SliceExpr:
-		if err := c.Compile(node.Expr); err != nil {
-			return err
-		}
-
-		if node.Low != nil {
-			if err := c.Compile(node.Low); err != nil {
-				return err
-			}
-		} else {
-			c.emit(node, OpNull)
-		}
-
-		if node.High != nil {
-			if err := c.Compile(node.High); err != nil {
-				return err
-			}
-		} else {
-			c.emit(node, OpNull)
-		}
-
-		c.emit(node, OpSliceIndex)
-
-	case *ast.FuncLit:
-		c.enterScope()
-
-		for _, p := range node.Type.Params.List {
-			s := c.symbolTable.Define(p.Name)
-
-			// function arguments is not assigned directly.
-			s.LocalAssigned = true
-		}
-
-		if err := c.Compile(node.Body); err != nil {
-			return err
-		}
-
-		// code optimization
-		c.optimizeFunc(node)
-
-		freeSymbols := c.symbolTable.FreeSymbols()
-		numLocals := c.symbolTable.MaxSymbols()
-		instructions, sourceMap := c.leaveScope()
-
-		for _, s := range freeSymbols {
-			switch s.Scope {
-			case ScopeLocal:
-				if !s.LocalAssigned {
-					// Here, the closure is capturing a local variable that's not yet assigned its value.
-					// One example is a local recursive function:
-					//
-					//   func() {
-					//     foo := func(x) {
-					//       // ..
-					//       return foo(x-1)
-					//     }
-					//   }
-					//
-					// which translate into
-					//
-					//   0000 GETL    0
-					//   0002 CLOSURE ?     1
-					//   0006 DEFL    0
-					//
-					// . So the local variable (0) is being captured before it's assigned the value.
-					//
-					// Solution is to transform the code into something like this:
-					//
-					//   func() {
-					//     foo := undefined
-					//     foo = func(x) {
-					//       // ..
-					//       return foo(x-1)
-					//     }
-					//   }
-					//
-					// that is equivalent to
-					//
-					//   0000 NULL
-					//   0001 DEFL    0
-					//   0003 GETL    0
-					//   0005 CLOSURE ?     1
-					//   0009 SETL    0
-					//
-
-					c.emit(node, OpNull)
-					c.emit(node, OpDefineLocal, s.Index)
-
-					s.LocalAssigned = true
-				}
-
-				c.emit(node, OpGetLocalPtr, s.Index)
-			case ScopeFree:
-				c.emit(node, OpGetFreePtr, s.Index)
-			}
-		}
-
-		compiledFunction := &objects.CompiledFunction{
-			Instructions:  instructions,
-			NumLocals:     numLocals,
-			NumParameters: len(node.Type.Params.List),
-			VarArgs:       node.Type.Params.VarArgs,
-			SourceMap:     sourceMap,
-		}
-
-		if len(freeSymbols) > 0 {
-			c.emit(node, OpClosure, c.addConstant(compiledFunction), len(freeSymbols))
-		} else {
-			c.emit(node, OpConstant, c.addConstant(compiledFunction))
-		}
-
-	case *ast.ReturnStmt:
-		if c.symbolTable.Parent(true) == nil {
-			// outside the function
-			return c.errorf(node, "return not allowed outside function")
-		}
-
-		if node.Result == nil {
-			c.emit(node, OpReturn, 0)
-		} else {
-			if err := c.Compile(node.Result); err != nil {
-				return err
-			}
-
-			c.emit(node, OpReturn, 1)
-		}
-
-	case *ast.CallExpr:
-		if err := c.Compile(node.Func); err != nil {
-			return err
-		}
-
-		for _, arg := range node.Args {
-			if err := c.Compile(arg); err != nil {
-				return err
-			}
-		}
-
-		c.emit(node, OpCall, len(node.Args))
-
-	case *ast.ImportExpr:
-		if node.ModuleName == "" {
-			return c.errorf(node, "empty module name")
-		}
-
-		if mod := c.modules.Get(node.ModuleName); mod != nil {
-			v, err := mod.Import(node.ModuleName)
-			if err != nil {
-				return err
-			}
-
-			switch v := v.(type) {
-			case []byte: // module written in Tengo
-				compiled, err := c.compileModule(node, node.ModuleName, node.ModuleName, v)
-				if err != nil {
-					return err
-				}
-				c.emit(node, OpConstant, c.addConstant(compiled))
-				c.emit(node, OpCall, 0)
-			case objects.Object: // builtin module
-				c.emit(node, OpConstant, c.addConstant(v))
-			default:
-				panic(fmt.Errorf("invalid import value type: %T", v))
-			}
-		} else if c.allowFileImport {
-			moduleName := node.ModuleName
-			if !strings.HasSuffix(moduleName, ".tengo") {
-				moduleName += ".tengo"
-			}
-
-			modulePath, err := filepath.Abs(moduleName)
-			if err != nil {
-				return c.errorf(node, "module file path error: %s", err.Error())
-			}
-
-			if err := c.checkCyclicImports(node, modulePath); err != nil {
-				return err
-			}
-
-			moduleSrc, err := ioutil.ReadFile(moduleName)
-			if err != nil {
-				return c.errorf(node, "module file read error: %s", err.Error())
-			}
-
-			compiled, err := c.compileModule(node, moduleName, modulePath, moduleSrc)
-			if err != nil {
-				return err
-			}
-			c.emit(node, OpConstant, c.addConstant(compiled))
-			c.emit(node, OpCall, 0)
-		} else {
-			return c.errorf(node, "module '%s' not found", node.ModuleName)
-		}
-
-	case *ast.ExportStmt:
-		// export statement must be in top-level scope
-		if c.scopeIndex != 0 {
-			return c.errorf(node, "export not allowed inside function")
-		}
-
-		// export statement is simply ignore when compiling non-module code
-		if c.parent == nil {
-			break
-		}
-
-		if err := c.Compile(node.Result); err != nil {
-			return err
-		}
-
-		c.emit(node, OpImmutable)
-		c.emit(node, OpReturn, 1)
-
-	case *ast.ErrorExpr:
-		if err := c.Compile(node.Expr); err != nil {
-			return err
-		}
-
-		c.emit(node, OpError)
-
-	case *ast.ImmutableExpr:
-		if err := c.Compile(node.Expr); err != nil {
-			return err
-		}
-
-		c.emit(node, OpImmutable)
-
-	case *ast.CondExpr:
-		if err := c.Compile(node.Cond); err != nil {
-			return err
-		}
-
-		// first jump placeholder
-		jumpPos1 := c.emit(node, OpJumpFalsy, 0)
-
-		if err := c.Compile(node.True); err != nil {
-			return err
-		}
-
-		// second jump placeholder
-		jumpPos2 := c.emit(node, OpJump, 0)
-
-		// update first jump offset
-		curPos := len(c.currentInstructions())
-		c.changeOperand(jumpPos1, curPos)
-
-		if err := c.Compile(node.False); err != nil {
-			return err
-		}
-
-		// update second jump offset
-		curPos = len(c.currentInstructions())
-		c.changeOperand(jumpPos2, curPos)
-	}
-
-	return nil
-}
-
-// Bytecode returns a compiled bytecode.
-func (c *Compiler) Bytecode() *Bytecode {
-	return &Bytecode{
-		FileSet: c.file.Set(),
-		MainFunction: &objects.CompiledFunction{
-			Instructions: c.currentInstructions(),
-			SourceMap:    c.currentSourceMap(),
-		},
-		Constants: c.constants,
-	}
-}
-
-// EnableFileImport enables or disables module loading from local files.
-// Local file modules are disabled by default.
-func (c *Compiler) EnableFileImport(enable bool) {
-	c.allowFileImport = enable
-}
-
-func (c *Compiler) fork(file *source.File, modulePath string, symbolTable *SymbolTable) *Compiler {
-	child := NewCompiler(file, symbolTable, nil, c.modules, c.trace)
-	child.modulePath = modulePath // module file path
-	child.parent = c              // parent to set to current compiler
-
-	return child
-}
-
-func (c *Compiler) error(node ast.Node, err error) error {
-	return &Error{
-		fileSet: c.file.Set(),
-		node:    node,
-		error:   err,
-	}
-}
-
-func (c *Compiler) errorf(node ast.Node, format string, args ...interface{}) error {
-	return &Error{
-		fileSet: c.file.Set(),
-		node:    node,
-		error:   fmt.Errorf(format, args...),
-	}
-}
-
-func (c *Compiler) addConstant(o objects.Object) int {
-	if c.parent != nil {
-		// module compilers will use their parent's constants array
-		return c.parent.addConstant(o)
-	}
-
-	c.constants = append(c.constants, o)
-
-	if c.trace != nil {
-		c.printTrace(fmt.Sprintf("CONST %04d %s", len(c.constants)-1, o))
-	}
-
-	return len(c.constants) - 1
-}
-
-func (c *Compiler) addInstruction(b []byte) int {
-	posNewIns := len(c.currentInstructions())
-
-	c.scopes[c.scopeIndex].instructions = append(c.currentInstructions(), b...)
-
-	return posNewIns
-}
-
-func (c *Compiler) replaceInstruction(pos int, inst []byte) {
-	copy(c.currentInstructions()[pos:], inst)
-
-	if c.trace != nil {
-		c.printTrace(fmt.Sprintf("REPLC %s",
-			FormatInstructions(c.scopes[c.scopeIndex].instructions[pos:], pos)[0]))
-	}
-}
-
-func (c *Compiler) changeOperand(opPos int, operand ...int) {
-	op := Opcode(c.currentInstructions()[opPos])
-	inst := MakeInstruction(op, operand...)
-
-	c.replaceInstruction(opPos, inst)
-}
-
-// optimizeFunc performs some code-level optimization for the current function instructions
-// it removes unreachable (dead code) instructions and adds "returns" instruction if needed.
-func (c *Compiler) optimizeFunc(node ast.Node) {
-	// any instructions between RETURN and the function end
-	// or instructions between RETURN and jump target position
-	// are considered as unreachable.
-
-	// pass 1. identify all jump destinations
-	dsts := make(map[int]bool)
-	iterateInstructions(c.scopes[c.scopeIndex].instructions, func(pos int, opcode Opcode, operands []int) bool {
-		switch opcode {
-		case OpJump, OpJumpFalsy, OpAndJump, OpOrJump:
-			dsts[operands[0]] = true
-		}
-
-		return true
-	})
-
-	var newInsts []byte
-
-	// pass 2. eliminate dead code
-	posMap := make(map[int]int) // old position to new position
-	var dstIdx int
-	var deadCode bool
-	iterateInstructions(c.scopes[c.scopeIndex].instructions, func(pos int, opcode Opcode, operands []int) bool {
-		switch {
-		case opcode == OpReturn:
-			if deadCode {
-				return true
-			}
-			deadCode = true
-		case dsts[pos]:
-			dstIdx++
-			deadCode = false
-		case deadCode:
-			return true
-		}
-
-		posMap[pos] = len(newInsts)
-		newInsts = append(newInsts, MakeInstruction(opcode, operands...)...)
-		return true
-	})
-
-	// pass 3. update jump positions
-	var lastOp Opcode
-	var appendReturn bool
-	endPos := len(c.scopes[c.scopeIndex].instructions)
-	iterateInstructions(newInsts, func(pos int, opcode Opcode, operands []int) bool {
-		switch opcode {
-		case OpJump, OpJumpFalsy, OpAndJump, OpOrJump:
-			newDst, ok := posMap[operands[0]]
-			if ok {
-				copy(newInsts[pos:], MakeInstruction(opcode, newDst))
-			} else if endPos == operands[0] {
-				// there's a jump instruction that jumps to the end of function
-				// compiler should append "return".
-				appendReturn = true
-			} else {
-				panic(fmt.Errorf("invalid jump position: %d", newDst))
-			}
-		}
-		lastOp = opcode
-		return true
-	})
-	if lastOp != OpReturn {
-		appendReturn = true
-	}
-
-	// pass 4. update source map
-	newSourceMap := make(map[int]source.Pos)
-	for pos, srcPos := range c.scopes[c.scopeIndex].sourceMap {
-		newPos, ok := posMap[pos]
-		if ok {
-			newSourceMap[newPos] = srcPos
-		}
-	}
-
-	c.scopes[c.scopeIndex].instructions = newInsts
-	c.scopes[c.scopeIndex].sourceMap = newSourceMap
-
-	// append "return"
-	if appendReturn {
-		c.emit(node, OpReturn, 0)
-	}
-}
-
-func (c *Compiler) emit(node ast.Node, opcode Opcode, operands ...int) int {
-	filePos := source.NoPos
-	if node != nil {
-		filePos = node.Pos()
-	}
-
-	inst := MakeInstruction(opcode, operands...)
-	pos := c.addInstruction(inst)
-	c.scopes[c.scopeIndex].sourceMap[pos] = filePos
-
-	if c.trace != nil {
-		c.printTrace(fmt.Sprintf("EMIT  %s",
-			FormatInstructions(c.scopes[c.scopeIndex].instructions[pos:], pos)[0]))
-	}
-
-	return pos
-}
-
-func (c *Compiler) printTrace(a ...interface{}) {
-	const (
-		dots = ". . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . "
-		n    = len(dots)
-	)
-
-	i := 2 * c.indent
-	for i > n {
-		_, _ = fmt.Fprint(c.trace, dots)
-		i -= n
-	}
-	_, _ = fmt.Fprint(c.trace, dots[0:i])
-	_, _ = fmt.Fprintln(c.trace, a...)
-}
-
-func trace(c *Compiler, msg string) *Compiler {
-	c.printTrace(msg, "{")
-	c.indent++
-
-	return c
-}
-
-func un(c *Compiler) {
-	c.indent--
-	c.printTrace("}")
-}
diff --git a/vendor/github.com/d5/tengo/compiler/compiler_assign.go b/vendor/github.com/d5/tengo/compiler/compiler_assign.go
deleted file mode 100644
index 59296f6f..00000000
--- a/vendor/github.com/d5/tengo/compiler/compiler_assign.go
+++ /dev/null
@@ -1,133 +0,0 @@
-package compiler
-
-import (
-	"fmt"
-
-	"github.com/d5/tengo/compiler/ast"
-	"github.com/d5/tengo/compiler/token"
-)
-
-func (c *Compiler) compileAssign(node ast.Node, lhs, rhs []ast.Expr, op token.Token) error {
-	numLHS, numRHS := len(lhs), len(rhs)
-	if numLHS > 1 || numRHS > 1 {
-		return c.errorf(node, "tuple assignment not allowed")
-	}
-
-	// resolve and compile left-hand side
-	ident, selectors := resolveAssignLHS(lhs[0])
-	numSel := len(selectors)
-
-	if op == token.Define && numSel > 0 {
-		// using selector on new variable does not make sense
-		return c.errorf(node, "operator ':=' not allowed with selector")
-	}
-
-	symbol, depth, exists := c.symbolTable.Resolve(ident)
-	if op == token.Define {
-		if depth == 0 && exists {
-			return c.errorf(node, "'%s' redeclared in this block", ident)
-		}
-
-		symbol = c.symbolTable.Define(ident)
-	} else {
-		if !exists {
-			return c.errorf(node, "unresolved reference '%s'", ident)
-		}
-	}
-
-	// +=, -=, *=, /=
-	if op != token.Assign && op != token.Define {
-		if err := c.Compile(lhs[0]); err != nil {
-			return err
-		}
-	}
-
-	// compile RHSs
-	for _, expr := range rhs {
-		if err := c.Compile(expr); err != nil {
-			return err
-		}
-	}
-
-	switch op {
-	case token.AddAssign:
-		c.emit(node, OpBinaryOp, int(token.Add))
-	case token.SubAssign:
-		c.emit(node, OpBinaryOp, int(token.Sub))
-	case token.MulAssign:
-		c.emit(node, OpBinaryOp, int(token.Mul))
-	case token.QuoAssign:
-		c.emit(node, OpBinaryOp, int(token.Quo))
-	case token.RemAssign:
-		c.emit(node, OpBinaryOp, int(token.Rem))
-	case token.AndAssign:
-		c.emit(node, OpBinaryOp, int(token.And))
-	case token.OrAssign:
-		c.emit(node, OpBinaryOp, int(token.Or))
-	case token.AndNotAssign:
-		c.emit(node, OpBinaryOp, int(token.AndNot))
-	case token.XorAssign:
-		c.emit(node, OpBinaryOp, int(token.Xor))
-	case token.ShlAssign:
-		c.emit(node, OpBinaryOp, int(token.Shl))
-	case token.ShrAssign:
-		c.emit(node, OpBinaryOp, int(token.Shr))
-	}
-
-	// compile selector expressions (right to left)
-	for i := numSel - 1; i >= 0; i-- {
-		if err := c.Compile(selectors[i]); err != nil {
-			return err
-		}
-	}
-
-	switch symbol.Scope {
-	case ScopeGlobal:
-		if numSel > 0 {
-			c.emit(node, OpSetSelGlobal, symbol.Index, numSel)
-		} else {
-			c.emit(node, OpSetGlobal, symbol.Index)
-		}
-	case ScopeLocal:
-		if numSel > 0 {
-			c.emit(node, OpSetSelLocal, symbol.Index, numSel)
-		} else {
-			if op == token.Define && !symbol.LocalAssigned {
-				c.emit(node, OpDefineLocal, symbol.Index)
-			} else {
-				c.emit(node, OpSetLocal, symbol.Index)
-			}
-		}
-
-		// mark the symbol as local-assigned
-		symbol.LocalAssigned = true
-	case ScopeFree:
-		if numSel > 0 {
-			c.emit(node, OpSetSelFree, symbol.Index, numSel)
-		} else {
-			c.emit(node, OpSetFree, symbol.Index)
-		}
-	default:
-		panic(fmt.Errorf("invalid assignment variable scope: %s", symbol.Scope))
-	}
-
-	return nil
-}
-
-func resolveAssignLHS(expr ast.Expr) (name string, selectors []ast.Expr) {
-	switch term := expr.(type) {
-	case *ast.SelectorExpr:
-		name, selectors = resolveAssignLHS(term.Expr)
-		selectors = append(selectors, term.Sel)
-		return
-
-	case *ast.IndexExpr:
-		name, selectors = resolveAssignLHS(term.Expr)
-		selectors = append(selectors, term.Index)
-
-	case *ast.Ident:
-		name = term.Name
-	}
-
-	return
-}
diff --git a/vendor/github.com/d5/tengo/compiler/compiler_for.go b/vendor/github.com/d5/tengo/compiler/compiler_for.go
deleted file mode 100644
index e7b7b5f1..00000000
--- a/vendor/github.com/d5/tengo/compiler/compiler_for.go
+++ /dev/null
@@ -1,181 +0,0 @@
-package compiler
-
-import (
-	"github.com/d5/tengo/compiler/ast"
-)
-
-func (c *Compiler) compileForStmt(stmt *ast.ForStmt) error {
-	c.symbolTable = c.symbolTable.Fork(true)
-	defer func() {
-		c.symbolTable = c.symbolTable.Parent(false)
-	}()
-
-	// init statement
-	if stmt.Init != nil {
-		if err := c.Compile(stmt.Init); err != nil {
-			return err
-		}
-	}
-
-	// pre-condition position
-	preCondPos := len(c.currentInstructions())
-
-	// condition expression
-	postCondPos := -1
-	if stmt.Cond != nil {
-		if err := c.Compile(stmt.Cond); err != nil {
-			return err
-		}
-		// condition jump position
-		postCondPos = c.emit(stmt, OpJumpFalsy, 0)
-	}
-
-	// enter loop
-	loop := c.enterLoop()
-
-	// body statement
-	if err := c.Compile(stmt.Body); err != nil {
-		c.leaveLoop()
-		return err
-	}
-
-	c.leaveLoop()
-
-	// post-body position
-	postBodyPos := len(c.currentInstructions())
-
-	// post statement
-	if stmt.Post != nil {
-		if err := c.Compile(stmt.Post); err != nil {
-			return err
-		}
-	}
-
-	// back to condition
-	c.emit(stmt, OpJump, preCondPos)
-
-	// post-statement position
-	postStmtPos := len(c.currentInstructions())
-	if postCondPos >= 0 {
-		c.changeOperand(postCondPos, postStmtPos)
-	}
-
-	// update all break/continue jump positions
-	for _, pos := range loop.Breaks {
-		c.changeOperand(pos, postStmtPos)
-	}
-	for _, pos := range loop.Continues {
-		c.changeOperand(pos, postBodyPos)
-	}
-
-	return nil
-}
-
-func (c *Compiler) compileForInStmt(stmt *ast.ForInStmt) error {
-	c.symbolTable = c.symbolTable.Fork(true)
-	defer func() {
-		c.symbolTable = c.symbolTable.Parent(false)
-	}()
-
-	// for-in statement is compiled like following:
-	//
-	//   for :it := iterator(iterable); :it.next();  {
-	//     k, v := :it.get()  // DEFINE operator
-	//
-	//     ... body ...
-	//   }
-	//
-	// ":it" is a local variable but will be conflict with other user variables
-	// because character ":" is not allowed.
-
-	// init
-	//   :it = iterator(iterable)
-	itSymbol := c.symbolTable.Define(":it")
-	if err := c.Compile(stmt.Iterable); err != nil {
-		return err
-	}
-	c.emit(stmt, OpIteratorInit)
-	if itSymbol.Scope == ScopeGlobal {
-		c.emit(stmt, OpSetGlobal, itSymbol.Index)
-	} else {
-		c.emit(stmt, OpDefineLocal, itSymbol.Index)
-	}
-
-	// pre-condition position
-	preCondPos := len(c.currentInstructions())
-
-	// condition
-	//  :it.HasMore()
-	if itSymbol.Scope == ScopeGlobal {
-		c.emit(stmt, OpGetGlobal, itSymbol.Index)
-	} else {
-		c.emit(stmt, OpGetLocal, itSymbol.Index)
-	}
-	c.emit(stmt, OpIteratorNext)
-
-	// condition jump position
-	postCondPos := c.emit(stmt, OpJumpFalsy, 0)
-
-	// enter loop
-	loop := c.enterLoop()
-
-	// assign key variable
-	if stmt.Key.Name != "_" {
-		keySymbol := c.symbolTable.Define(stmt.Key.Name)
-		if itSymbol.Scope == ScopeGlobal {
-			c.emit(stmt, OpGetGlobal, itSymbol.Index)
-		} else {
-			c.emit(stmt, OpGetLocal, itSymbol.Index)
-		}
-		c.emit(stmt, OpIteratorKey)
-		if keySymbol.Scope == ScopeGlobal {
-			c.emit(stmt, OpSetGlobal, keySymbol.Index)
-		} else {
-			c.emit(stmt, OpDefineLocal, keySymbol.Index)
-		}
-	}
-
-	// assign value variable
-	if stmt.Value.Name != "_" {
-		valueSymbol := c.symbolTable.Define(stmt.Value.Name)
-		if itSymbol.Scope == ScopeGlobal {
-			c.emit(stmt, OpGetGlobal, itSymbol.Index)
-		} else {
-			c.emit(stmt, OpGetLocal, itSymbol.Index)
-		}
-		c.emit(stmt, OpIteratorValue)
-		if valueSymbol.Scope == ScopeGlobal {
-			c.emit(stmt, OpSetGlobal, valueSymbol.Index)
-		} else {
-			c.emit(stmt, OpDefineLocal, valueSymbol.Index)
-		}
-	}
-
-	// body statement
-	if err := c.Compile(stmt.Body); err != nil {
-		c.leaveLoop()
-		return err
-	}
-
-	c.leaveLoop()
-
-	// post-body position
-	postBodyPos := len(c.currentInstructions())
-
-	// back to condition
-	c.emit(stmt, OpJump, preCondPos)
-
-	// post-statement position
-	postStmtPos := len(c.currentInstructions())
-	c.changeOperand(postCondPos, postStmtPos)
-
-	// update all break/continue jump positions
-	for _, pos := range loop.Breaks {
-		c.changeOperand(pos, postStmtPos)
-	}
-	for _, pos := range loop.Continues {
-		c.changeOperand(pos, postBodyPos)
-	}
-
-	return nil
-}
diff --git a/vendor/github.com/d5/tengo/compiler/compiler_logical.go b/vendor/github.com/d5/tengo/compiler/compiler_logical.go
deleted file mode 100644
index 68c96759..00000000
--- a/vendor/github.com/d5/tengo/compiler/compiler_logical.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package compiler
-
-import (
-	"github.com/d5/tengo/compiler/ast"
-	"github.com/d5/tengo/compiler/token"
-)
-
-func (c *Compiler) compileLogical(node *ast.BinaryExpr) error {
-	// left side term
-	if err := c.Compile(node.LHS); err != nil {
-		return err
-	}
-
-	// jump position
-	var jumpPos int
-	if node.Token == token.LAnd {
-		jumpPos = c.emit(node, OpAndJump, 0)
-	} else {
-		jumpPos = c.emit(node, OpOrJump, 0)
-	}
-
-	// right side term
-	if err := c.Compile(node.RHS); err != nil {
-		return err
-	}
-
-	c.changeOperand(jumpPos, len(c.currentInstructions()))
-
-	return nil
-}
diff --git a/vendor/github.com/d5/tengo/compiler/compiler_loops.go b/vendor/github.com/d5/tengo/compiler/compiler_loops.go
deleted file mode 100644
index 0659ce73..00000000
--- a/vendor/github.com/d5/tengo/compiler/compiler_loops.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package compiler
-
-func (c *Compiler) enterLoop() *Loop {
-	loop := &Loop{}
-
-	c.loops = append(c.loops, loop)
-	c.loopIndex++
-
-	if c.trace != nil {
-		c.printTrace("LOOPE", c.loopIndex)
-	}
-
-	return loop
-}
-
-func (c *Compiler) leaveLoop() {
-	if c.trace != nil {
-		c.printTrace("LOOPL", c.loopIndex)
-	}
-
-	c.loops = c.loops[:len(c.loops)-1]
-	c.loopIndex--
-}
-
-func (c *Compiler) currentLoop() *Loop {
-	if c.loopIndex >= 0 {
-		return c.loops[c.loopIndex]
-	}
-
-	return nil
-}
diff --git a/vendor/github.com/d5/tengo/compiler/compiler_module.go b/vendor/github.com/d5/tengo/compiler/compiler_module.go
deleted file mode 100644
index 8a3671ce..00000000
--- a/vendor/github.com/d5/tengo/compiler/compiler_module.go
+++ /dev/null
@@ -1,79 +0,0 @@
-package compiler
-
-import (
-	"github.com/d5/tengo/compiler/ast"
-	"github.com/d5/tengo/compiler/parser"
-	"github.com/d5/tengo/objects"
-)
-
-func (c *Compiler) checkCyclicImports(node ast.Node, modulePath string) error {
-	if c.modulePath == modulePath {
-		return c.errorf(node, "cyclic module import: %s", modulePath)
-	} else if c.parent != nil {
-		return c.parent.checkCyclicImports(node, modulePath)
-	}
-
-	return nil
-}
-
-func (c *Compiler) compileModule(node ast.Node, moduleName, modulePath string, src []byte) (*objects.CompiledFunction, error) {
-	if err := c.checkCyclicImports(node, modulePath); err != nil {
-		return nil, err
-	}
-
-	compiledModule, exists := c.loadCompiledModule(modulePath)
-	if exists {
-		return compiledModule, nil
-	}
-
-	modFile := c.file.Set().AddFile(moduleName, -1, len(src))
-	p := parser.NewParser(modFile, src, nil)
-	file, err := p.ParseFile()
-	if err != nil {
-		return nil, err
-	}
-
-	symbolTable := NewSymbolTable()
-
-	// inherit builtin functions
-	for _, sym := range c.symbolTable.BuiltinSymbols() {
-		symbolTable.DefineBuiltin(sym.Index, sym.Name)
-	}
-
-	// no global scope for the module
-	symbolTable = symbolTable.Fork(false)
-
-	// compile module
-	moduleCompiler := c.fork(modFile, modulePath, symbolTable)
-	if err := moduleCompiler.Compile(file); err != nil {
-		return nil, err
-	}
-
-	// code optimization
-	moduleCompiler.optimizeFunc(node)
-
-	compiledFunc := moduleCompiler.Bytecode().MainFunction
-	compiledFunc.NumLocals = symbolTable.MaxSymbols()
-
-	c.storeCompiledModule(modulePath, compiledFunc)
-
-	return compiledFunc, nil
-}
-
-func (c *Compiler) loadCompiledModule(modulePath string) (mod *objects.CompiledFunction, ok bool) {
-	if c.parent != nil {
-		return c.parent.loadCompiledModule(modulePath)
-	}
-
-	mod, ok = c.compiledModules[modulePath]
-
-	return
-}
-
-func (c *Compiler) storeCompiledModule(modulePath string, module *objects.CompiledFunction) {
-	if c.parent != nil {
-		c.parent.storeCompiledModule(modulePath, module)
-	}
-
-	c.compiledModules[modulePath] = module
-}
diff --git a/vendor/github.com/d5/tengo/compiler/compiler_scopes.go b/vendor/github.com/d5/tengo/compiler/compiler_scopes.go
deleted file mode 100644
index b63f915a..00000000
--- a/vendor/github.com/d5/tengo/compiler/compiler_scopes.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package compiler
-
-import "github.com/d5/tengo/compiler/source"
-
-func (c *Compiler) currentInstructions() []byte {
-	return c.scopes[c.scopeIndex].instructions
-}
-
-func (c *Compiler) currentSourceMap() map[int]source.Pos {
-	return c.scopes[c.scopeIndex].sourceMap
-}
-
-func (c *Compiler) enterScope() {
-	scope := CompilationScope{
-		symbolInit: make(map[string]bool),
-		sourceMap:  make(map[int]source.Pos),
-	}
-
-	c.scopes = append(c.scopes, scope)
-	c.scopeIndex++
-
-	c.symbolTable = c.symbolTable.Fork(false)
-
-	if c.trace != nil {
-		c.printTrace("SCOPE", c.scopeIndex)
-	}
-}
-
-func (c *Compiler) leaveScope() (instructions []byte, sourceMap map[int]source.Pos) {
-	instructions = c.currentInstructions()
-	sourceMap = c.currentSourceMap()
-
-	c.scopes = c.scopes[:len(c.scopes)-1]
-	c.scopeIndex--
-
-	c.symbolTable = c.symbolTable.Parent(true)
-
-	if c.trace != nil {
-		c.printTrace("SCOPL", c.scopeIndex)
-	}
-
-	return
-}
diff --git a/vendor/github.com/d5/tengo/compiler/emitted_instruction.go b/vendor/github.com/d5/tengo/compiler/emitted_instruction.go
deleted file mode 100644
index 8572fb0a..00000000
--- a/vendor/github.com/d5/tengo/compiler/emitted_instruction.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package compiler
-
-// EmittedInstruction represents an opcode
-// with its emitted position.
-type EmittedInstruction struct {
-	Opcode   Opcode
-	Position int
-}
diff --git a/vendor/github.com/d5/tengo/compiler/error.go b/vendor/github.com/d5/tengo/compiler/error.go
deleted file mode 100644
index 6ac33d42..00000000
--- a/vendor/github.com/d5/tengo/compiler/error.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package compiler
-
-import (
-	"fmt"
-
-	"github.com/d5/tengo/compiler/ast"
-	"github.com/d5/tengo/compiler/source"
-)
-
-// Error represents a compiler error.
-type Error struct {
-	fileSet *source.FileSet
-	node    ast.Node
-	error   error
-}
-
-func (e *Error) Error() string {
-	filePos := e.fileSet.Position(e.node.Pos())
-	return fmt.Sprintf("Compile Error: %s\n\tat %s", e.error.Error(), filePos)
-}
diff --git a/vendor/github.com/d5/tengo/compiler/instructions.go b/vendor/github.com/d5/tengo/compiler/instructions.go
deleted file mode 100644
index 14dde1d8..00000000
--- a/vendor/github.com/d5/tengo/compiler/instructions.go
+++ /dev/null
@@ -1,72 +0,0 @@
-package compiler
-
-import (
-	"fmt"
-)
-
-// MakeInstruction returns a bytecode for an opcode and the operands.
-func MakeInstruction(opcode Opcode, operands ...int) []byte {
-	numOperands := OpcodeOperands[opcode]
-
-	totalLen := 1
-	for _, w := range numOperands {
-		totalLen += w
-	}
-
-	instruction := make([]byte, totalLen)
-	instruction[0] = byte(opcode)
-
-	offset := 1
-	for i, o := range operands {
-		width := numOperands[i]
-		switch width {
-		case 1:
-			instruction[offset] = byte(o)
-		case 2:
-			n := uint16(o)
-			instruction[offset] = byte(n >> 8)
-			instruction[offset+1] = byte(n)
-		}
-		offset += width
-	}
-
-	return instruction
-}
-
-// FormatInstructions returns string representation of
-// bytecode instructions.
-func FormatInstructions(b []byte, posOffset int) []string {
-	var out []string
-
-	i := 0
-	for i < len(b) {
-		numOperands := OpcodeOperands[Opcode(b[i])]
-		operands, read := ReadOperands(numOperands, b[i+1:])
-
-		switch len(numOperands) {
-		case 0:
-			out = append(out, fmt.Sprintf("%04d %-7s", posOffset+i, OpcodeNames[Opcode(b[i])]))
-		case 1:
-			out = append(out, fmt.Sprintf("%04d %-7s %-5d", posOffset+i, OpcodeNames[Opcode(b[i])], operands[0]))
-		case 2:
-			out = append(out, fmt.Sprintf("%04d %-7s %-5d %-5d", posOffset+i, OpcodeNames[Opcode(b[i])], operands[0], operands[1]))
-		}
-
-		i += 1 + read
-	}
-
-	return out
-}
-
-func iterateInstructions(b []byte, fn func(pos int, opcode Opcode, operands []int) bool) {
-	for i := 0; i < len(b); i++ {
-		numOperands := OpcodeOperands[Opcode(b[i])]
-		operands, read := ReadOperands(numOperands, b[i+1:])
-
-		if !fn(i, b[i], operands) {
-			break
-		}
-
-		i += read
-	}
-}
diff --git a/vendor/github.com/d5/tengo/compiler/loop.go b/vendor/github.com/d5/tengo/compiler/loop.go
deleted file mode 100644
index e27cb096..00000000
--- a/vendor/github.com/d5/tengo/compiler/loop.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package compiler
-
-// Loop represents a loop construct that
-// the compiler uses to track the current loop.
-type Loop struct {
-	Continues []int
-	Breaks    []int
-}
diff --git a/vendor/github.com/d5/tengo/compiler/module_loader.go b/vendor/github.com/d5/tengo/compiler/module_loader.go
deleted file mode 100644
index b050474d..00000000
--- a/vendor/github.com/d5/tengo/compiler/module_loader.go
+++ /dev/null
@@ -1,4 +0,0 @@
-package compiler
-
-// ModuleLoader should take a module name and return the module data.
-type ModuleLoader func(moduleName string) ([]byte, error)
diff --git a/vendor/github.com/d5/tengo/compiler/parser/error.go b/vendor/github.com/d5/tengo/compiler/parser/error.go
deleted file mode 100644
index 80544fbd..00000000
--- a/vendor/github.com/d5/tengo/compiler/parser/error.go
+++ /dev/null
@@ -1,21 +0,0 @@
-package parser
-
-import (
-	"fmt"
-
-	"github.com/d5/tengo/compiler/source"
-)
-
-// Error represents a parser error.
-type Error struct {
-	Pos source.FilePos
-	Msg string
-}
-
-func (e Error) Error() string {
-	if e.Pos.Filename != "" || e.Pos.IsValid() {
-		return fmt.Sprintf("Parse Error: %s\n\tat %s", e.Msg, e.Pos)
-	}
-
-	return fmt.Sprintf("Parse Error: %s", e.Msg)
-}
diff --git a/vendor/github.com/d5/tengo/compiler/parser/error_list.go b/vendor/github.com/d5/tengo/compiler/parser/error_list.go
deleted file mode 100644
index 599eaf7d..00000000
--- a/vendor/github.com/d5/tengo/compiler/parser/error_list.go
+++ /dev/null
@@ -1,68 +0,0 @@
-package parser
-
-import (
-	"fmt"
-	"sort"
-
-	"github.com/d5/tengo/compiler/source"
-)
-
-// ErrorList is a collection of parser errors.
-type ErrorList []*Error
-
-// Add adds a new parser error to the collection.
-func (p *ErrorList) Add(pos source.FilePos, msg string) {
-	*p = append(*p, &Error{pos, msg})
-}
-
-// Len returns the number of elements in the collection.
-func (p ErrorList) Len() int {
-	return len(p)
-}
-
-func (p ErrorList) Swap(i, j int) {
-	p[i], p[j] = p[j], p[i]
-}
-
-func (p ErrorList) Less(i, j int) bool {
-	e := &p[i].Pos
-	f := &p[j].Pos
-
-	if e.Filename != f.Filename {
-		return e.Filename < f.Filename
-	}
-
-	if e.Line != f.Line {
-		return e.Line < f.Line
-	}
-
-	if e.Column != f.Column {
-		return e.Column < f.Column
-	}
-
-	return p[i].Msg < p[j].Msg
-}
-
-// Sort sorts the collection.
-func (p ErrorList) Sort() {
-	sort.Sort(p)
-}
-
-func (p ErrorList) Error() string {
-	switch len(p) {
-	case 0:
-		return "no errors"
-	case 1:
-		return p[0].Error()
-	}
-	return fmt.Sprintf("%s (and %d more errors)", p[0], len(p)-1)
-}
-
-// Err returns an error.
-func (p ErrorList) Err() error {
-	if len(p) == 0 {
-		return nil
-	}
-
-	return p
-}
diff --git a/vendor/github.com/d5/tengo/compiler/parser/parse_source.go b/vendor/github.com/d5/tengo/compiler/parser/parse_source.go
deleted file mode 100644
index 5c71436d..00000000
--- a/vendor/github.com/d5/tengo/compiler/parser/parse_source.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package parser
-
-import (
-	"io"
-
-	"github.com/d5/tengo/compiler/ast"
-	"github.com/d5/tengo/compiler/source"
-)
-
-// ParseSource parses source code 'src' and builds an AST.
-func ParseSource(filename string, src []byte, trace io.Writer) (res *ast.File, err error) {
-	fileSet := source.NewFileSet()
-	file := fileSet.AddFile(filename, -1, len(src))
-
-	p := NewParser(file, src, trace)
-	return p.ParseFile()
-}
diff --git a/vendor/github.com/d5/tengo/compiler/parser/sync.go b/vendor/github.com/d5/tengo/compiler/parser/sync.go
deleted file mode 100644
index e68d623a..00000000
--- a/vendor/github.com/d5/tengo/compiler/parser/sync.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package parser
-
-import "github.com/d5/tengo/compiler/token"
-
-var stmtStart = map[token.Token]bool{
-	token.Break:    true,
-	token.Continue: true,
-	token.For:      true,
-	token.If:       true,
-	token.Return:   true,
-	token.Export:   true,
-}
diff --git a/vendor/github.com/d5/tengo/compiler/scanner/error_handler.go b/vendor/github.com/d5/tengo/compiler/scanner/error_handler.go
deleted file mode 100644
index 379f0196..00000000
--- a/vendor/github.com/d5/tengo/compiler/scanner/error_handler.go
+++ /dev/null
@@ -1,6 +0,0 @@
-package scanner
-
-import "github.com/d5/tengo/compiler/source"
-
-// ErrorHandler is an error handler for the scanner.
-type ErrorHandler func(pos source.FilePos, msg string)
diff --git a/vendor/github.com/d5/tengo/compiler/scanner/mode.go b/vendor/github.com/d5/tengo/compiler/scanner/mode.go
deleted file mode 100644
index f67ceaf8..00000000
--- a/vendor/github.com/d5/tengo/compiler/scanner/mode.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package scanner
-
-// Mode represents a scanner mode.
-type Mode int
-
-// List of scanner modes.
-const (
-	ScanComments Mode = 1 << iota
-	DontInsertSemis
-)
diff --git a/vendor/github.com/d5/tengo/compiler/source/file.go b/vendor/github.com/d5/tengo/compiler/source/file.go
deleted file mode 100644
index 9e51c9a4..00000000
--- a/vendor/github.com/d5/tengo/compiler/source/file.go
+++ /dev/null
@@ -1,110 +0,0 @@
-package source
-
-// File represents a source file.
-type File struct {
-	// File set for the file
-	set *FileSet
-	// File name as provided to AddFile
-	Name string
-	// Pos value range for this file is [base...base+size]
-	Base int
-	// File size as provided to AddFile
-	Size int
-	// Lines contains the offset of the first character for each line (the first entry is always 0)
-	Lines []int
-}
-
-// Set returns FileSet.
-func (f *File) Set() *FileSet {
-	return f.set
-}
-
-// LineCount returns the current number of lines.
-func (f *File) LineCount() int {
-	return len(f.Lines)
-}
-
-// AddLine adds a new line.
-func (f *File) AddLine(offset int) {
-	if i := len(f.Lines); (i == 0 || f.Lines[i-1] < offset) && offset < f.Size {
-		f.Lines = append(f.Lines, offset)
-	}
-}
-
-// LineStart returns the position of the first character in the line.
-func (f *File) LineStart(line int) Pos {
-	if line < 1 {
-		panic("illegal line number (line numbering starts at 1)")
-	}
-
-	if line > len(f.Lines) {
-		panic("illegal line number")
-	}
-
-	return Pos(f.Base + f.Lines[line-1])
-}
-
-// FileSetPos returns the position in the file set.
-func (f *File) FileSetPos(offset int) Pos {
-	if offset > f.Size {
-		panic("illegal file offset")
-	}
-
-	return Pos(f.Base + offset)
-}
-
-// Offset translates the file set position into the file offset.
-func (f *File) Offset(p Pos) int {
-	if int(p) < f.Base || int(p) > f.Base+f.Size {
-		panic("illegal Pos value")
-	}
-
-	return int(p) - f.Base
-}
-
-// Position translates the file set position into the file position.
-func (f *File) Position(p Pos) (pos FilePos) {
-	if p != NoPos {
-		if int(p) < f.Base || int(p) > f.Base+f.Size {
-			panic("illegal Pos value")
-		}
-
-		pos = f.position(p)
-	}
-
-	return
-}
-
-func (f *File) position(p Pos) (pos FilePos) {
-	offset := int(p) - f.Base
-	pos.Offset = offset
-	pos.Filename, pos.Line, pos.Column = f.unpack(offset)
-
-	return
-}
-
-func (f *File) unpack(offset int) (filename string, line, column int) {
-	filename = f.Name
-	if i := searchInts(f.Lines, offset); i >= 0 {
-		line, column = i+1, offset-f.Lines[i]+1
-	}
-
-	return
-}
-
-func searchInts(a []int, x int) int {
-	// This function body is a manually inlined version of:
-	//   return sort.Search(len(a), func(i int) bool { return a[i] > x }) - 1
-	i, j := 0, len(a)
-	for i < j {
-		h := i + (j-i)/2 // avoid overflow when computing h
-		// i ≤ h < j
-		if a[h] <= x {
-			i = h + 1
-		} else {
-			j = h
-		}
-	}
-
-	return i - 1
-}
diff --git a/vendor/github.com/d5/tengo/compiler/source/file_pos.go b/vendor/github.com/d5/tengo/compiler/source/file_pos.go
deleted file mode 100644
index 4055fe6d..00000000
--- a/vendor/github.com/d5/tengo/compiler/source/file_pos.go
+++ /dev/null
@@ -1,47 +0,0 @@
-package source
-
-import "fmt"
-
-// FilePos represents a position information in the file.
-type FilePos struct {
-	Filename string // filename, if any
-	Offset   int    // offset, starting at 0
-	Line     int    // line number, starting at 1
-	Column   int    // column number, starting at 1 (byte count)
-}
-
-// IsValid returns true if the position is valid.
-func (p FilePos) IsValid() bool {
-	return p.Line > 0
-}
-
-// String returns a string in one of several forms:
-//
-//	file:line:column    valid position with file name
-//	file:line           valid position with file name but no column (column == 0)
-//	line:column         valid position without file name
-//	line                valid position without file name and no column (column == 0)
-//	file                invalid position with file name
-//	-                   invalid position without file name
-//
-func (p FilePos) String() string {
-	s := p.Filename
-
-	if p.IsValid() {
-		if s != "" {
-			s += ":"
-		}
-
-		s += fmt.Sprintf("%d", p.Line)
-
-		if p.Column != 0 {
-			s += fmt.Sprintf(":%d", p.Column)
-		}
-	}
-
-	if s == "" {
-		s = "-"
-	}
-
-	return s
-}
diff --git a/vendor/github.com/d5/tengo/compiler/source/file_set.go b/vendor/github.com/d5/tengo/compiler/source/file_set.go
deleted file mode 100644
index da342364..00000000
--- a/vendor/github.com/d5/tengo/compiler/source/file_set.go
+++ /dev/null
@@ -1,96 +0,0 @@
-package source
-
-import (
-	"sort"
-)
-
-// FileSet represents a set of source files.
-type FileSet struct {
-	Base     int     // base offset for the next file
-	Files    []*File // list of files in the order added to the set
-	LastFile *File   // cache of last file looked up
-}
-
-// NewFileSet creates a new file set.
-func NewFileSet() *FileSet {
-	return &FileSet{
-		Base: 1, // 0 == NoPos
-	}
-}
-
-// AddFile adds a new file in the file set.
-func (s *FileSet) AddFile(filename string, base, size int) *File {
-	if base < 0 {
-		base = s.Base
-	}
-	if base < s.Base || size < 0 {
-		panic("illegal base or size")
-	}
-
-	f := &File{
-		set:   s,
-		Name:  filename,
-		Base:  base,
-		Size:  size,
-		Lines: []int{0},
-	}
-
-	base += size + 1 // +1 because EOF also has a position
-	if base < 0 {
-		panic("offset overflow (> 2G of source code in file set)")
-	}
-
-	// add the file to the file set
-	s.Base = base
-	s.Files = append(s.Files, f)
-	s.LastFile = f
-
-	return f
-}
-
-// File returns the file that contains the position p.
-// If no such file is found (for instance for p == NoPos),
-// the result is nil.
-//
-func (s *FileSet) File(p Pos) (f *File) {
-	if p != NoPos {
-		f = s.file(p)
-	}
-
-	return
-}
-
-// Position converts a Pos p in the fileset into a FilePos value.
-func (s *FileSet) Position(p Pos) (pos FilePos) {
-	if p != NoPos {
-		if f := s.file(p); f != nil {
-			return f.position(p)
-		}
-	}
-
-	return
-}
-
-func (s *FileSet) file(p Pos) *File {
-	// common case: p is in last file
-	if f := s.LastFile; f != nil && f.Base <= int(p) && int(p) <= f.Base+f.Size {
-		return f
-	}
-
-	// p is not in last file - search all files
-	if i := searchFiles(s.Files, int(p)); i >= 0 {
-		f := s.Files[i]
-
-		// f.base <= int(p) by definition of searchFiles
-		if int(p) <= f.Base+f.Size {
-			s.LastFile = f // race is ok - s.last is only a cache
-			return f
-		}
-	}
-
-	return nil
-}
-
-func searchFiles(a []*File, x int) int {
-	return sort.Search(len(a), func(i int) bool { return a[i].Base > x }) - 1
-}
diff --git a/vendor/github.com/d5/tengo/compiler/symbol.go b/vendor/github.com/d5/tengo/compiler/symbol.go
deleted file mode 100644
index bcd53234..00000000
--- a/vendor/github.com/d5/tengo/compiler/symbol.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package compiler
-
-// Symbol represents a symbol in the symbol table.
-type Symbol struct {
-	Name          string
-	Scope         SymbolScope
-	Index         int
-	LocalAssigned bool // if the local symbol is assigned at least once
-}
diff --git a/vendor/github.com/d5/tengo/compiler/symbol_scopes.go b/vendor/github.com/d5/tengo/compiler/symbol_scopes.go
deleted file mode 100644
index e0c0d94b..00000000
--- a/vendor/github.com/d5/tengo/compiler/symbol_scopes.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package compiler
-
-// SymbolScope represents a symbol scope.
-type SymbolScope string
-
-// List of symbol scopes
-const (
-	ScopeGlobal  SymbolScope = "GLOBAL"
-	ScopeLocal   SymbolScope = "LOCAL"
-	ScopeBuiltin SymbolScope = "BUILTIN"
-	ScopeFree    SymbolScope = "FREE"
-)
diff --git a/vendor/github.com/d5/tengo/compiler/token/keywords.go b/vendor/github.com/d5/tengo/compiler/token/keywords.go
deleted file mode 100644
index fd6e9d0b..00000000
--- a/vendor/github.com/d5/tengo/compiler/token/keywords.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package token
-
-var keywords map[string]Token
-
-func init() {
-	keywords = make(map[string]Token)
-	for i := _keywordBeg + 1; i < _keywordEnd; i++ {
-		keywords[tokens[i]] = i
-	}
-}
-
-// Lookup returns corresponding keyword if ident is a keyword.
-func Lookup(ident string) Token {
-	if tok, isKeyword := keywords[ident]; isKeyword {
-		return tok
-	}
-
-	return Ident
-}
diff --git a/vendor/github.com/d5/tengo/go.mod b/vendor/github.com/d5/tengo/go.mod
deleted file mode 100644
index 8421e273..00000000
--- a/vendor/github.com/d5/tengo/go.mod
+++ /dev/null
@@ -1,3 +0,0 @@
-module github.com/d5/tengo
-
-go 1.12
diff --git a/vendor/github.com/d5/tengo/objects/array.go b/vendor/github.com/d5/tengo/objects/array.go
deleted file mode 100644
index 1e917c59..00000000
--- a/vendor/github.com/d5/tengo/objects/array.go
+++ /dev/null
@@ -1,130 +0,0 @@
-package objects
-
-import (
-	"fmt"
-	"strings"
-
-	"github.com/d5/tengo/compiler/token"
-)
-
-// Array represents an array of objects.
-type Array struct {
-	Value []Object
-}
-
-// TypeName returns the name of the type.
-func (o *Array) TypeName() string {
-	return "array"
-}
-
-func (o *Array) String() string {
-	var elements []string
-	for _, e := range o.Value {
-		elements = append(elements, e.String())
-	}
-
-	return fmt.Sprintf("[%s]", strings.Join(elements, ", "))
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *Array) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	if rhs, ok := rhs.(*Array); ok {
-		switch op {
-		case token.Add:
-			if len(rhs.Value) == 0 {
-				return o, nil
-			}
-			return &Array{Value: append(o.Value, rhs.Value...)}, nil
-		}
-	}
-
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *Array) Copy() Object {
-	var c []Object
-	for _, elem := range o.Value {
-		c = append(c, elem.Copy())
-	}
-
-	return &Array{Value: c}
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *Array) IsFalsy() bool {
-	return len(o.Value) == 0
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *Array) Equals(x Object) bool {
-	var xVal []Object
-	switch x := x.(type) {
-	case *Array:
-		xVal = x.Value
-	case *ImmutableArray:
-		xVal = x.Value
-	default:
-		return false
-	}
-
-	if len(o.Value) != len(xVal) {
-		return false
-	}
-
-	for i, e := range o.Value {
-		if !e.Equals(xVal[i]) {
-			return false
-		}
-	}
-
-	return true
-}
-
-// IndexGet returns an element at a given index.
-func (o *Array) IndexGet(index Object) (res Object, err error) {
-	intIdx, ok := index.(*Int)
-	if !ok {
-		err = ErrInvalidIndexType
-		return
-	}
-
-	idxVal := int(intIdx.Value)
-
-	if idxVal < 0 || idxVal >= len(o.Value) {
-		res = UndefinedValue
-		return
-	}
-
-	res = o.Value[idxVal]
-
-	return
-}
-
-// IndexSet sets an element at a given index.
-func (o *Array) IndexSet(index, value Object) (err error) {
-	intIdx, ok := ToInt(index)
-	if !ok {
-		err = ErrInvalidIndexType
-		return
-	}
-
-	if intIdx < 0 || intIdx >= len(o.Value) {
-		err = ErrIndexOutOfBounds
-		return
-	}
-
-	o.Value[intIdx] = value
-
-	return nil
-}
-
-// Iterate creates an array iterator.
-func (o *Array) Iterate() Iterator {
-	return &ArrayIterator{
-		v: o.Value,
-		l: len(o.Value),
-	}
-}
diff --git a/vendor/github.com/d5/tengo/objects/array_iterator.go b/vendor/github.com/d5/tengo/objects/array_iterator.go
deleted file mode 100644
index 204faa41..00000000
--- a/vendor/github.com/d5/tengo/objects/array_iterator.go
+++ /dev/null
@@ -1,57 +0,0 @@
-package objects
-
-import "github.com/d5/tengo/compiler/token"
-
-// ArrayIterator is an iterator for an array.
-type ArrayIterator struct {
-	v []Object
-	i int
-	l int
-}
-
-// TypeName returns the name of the type.
-func (i *ArrayIterator) TypeName() string {
-	return "array-iterator"
-}
-
-func (i *ArrayIterator) String() string {
-	return "<array-iterator>"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (i *ArrayIterator) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	return nil, ErrInvalidOperator
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (i *ArrayIterator) IsFalsy() bool {
-	return true
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (i *ArrayIterator) Equals(Object) bool {
-	return false
-}
-
-// Copy returns a copy of the type.
-func (i *ArrayIterator) Copy() Object {
-	return &ArrayIterator{v: i.v, i: i.i, l: i.l}
-}
-
-// Next returns true if there are more elements to iterate.
-func (i *ArrayIterator) Next() bool {
-	i.i++
-	return i.i <= i.l
-}
-
-// Key returns the key or index value of the current element.
-func (i *ArrayIterator) Key() Object {
-	return &Int{Value: int64(i.i - 1)}
-}
-
-// Value returns the value of the current element.
-func (i *ArrayIterator) Value() Object {
-	return i.v[i.i-1]
-}
diff --git a/vendor/github.com/d5/tengo/objects/bool.go b/vendor/github.com/d5/tengo/objects/bool.go
deleted file mode 100644
index ac9949e4..00000000
--- a/vendor/github.com/d5/tengo/objects/bool.go
+++ /dev/null
@@ -1,64 +0,0 @@
-package objects
-
-import (
-	"github.com/d5/tengo/compiler/token"
-)
-
-// Bool represents a boolean value.
-type Bool struct {
-	// this is intentionally non-public to force using objects.TrueValue and FalseValue always
-	value bool
-}
-
-func (o *Bool) String() string {
-	if o.value {
-		return "true"
-	}
-
-	return "false"
-}
-
-// TypeName returns the name of the type.
-func (o *Bool) TypeName() string {
-	return "bool"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *Bool) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *Bool) Copy() Object {
-	return o
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *Bool) IsFalsy() bool {
-	return !o.value
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *Bool) Equals(x Object) bool {
-	return o == x
-}
-
-// GobDecode decodes bool value from input bytes.
-func (o *Bool) GobDecode(b []byte) (err error) {
-	o.value = b[0] == 1
-
-	return
-}
-
-// GobEncode encodes bool values into bytes.
-func (o *Bool) GobEncode() (b []byte, err error) {
-	if o.value {
-		b = []byte{1}
-	} else {
-		b = []byte{0}
-	}
-
-	return
-}
diff --git a/vendor/github.com/d5/tengo/objects/builtin_append.go b/vendor/github.com/d5/tengo/objects/builtin_append.go
deleted file mode 100644
index 9fb14b82..00000000
--- a/vendor/github.com/d5/tengo/objects/builtin_append.go
+++ /dev/null
@@ -1,21 +0,0 @@
-package objects
-
-// append(arr, items...)
-func builtinAppend(args ...Object) (Object, error) {
-	if len(args) < 2 {
-		return nil, ErrWrongNumArguments
-	}
-
-	switch arg := args[0].(type) {
-	case *Array:
-		return &Array{Value: append(arg.Value, args[1:]...)}, nil
-	case *ImmutableArray:
-		return &Array{Value: append(arg.Value, args[1:]...)}, nil
-	default:
-		return nil, ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "array",
-			Found:    arg.TypeName(),
-		}
-	}
-}
diff --git a/vendor/github.com/d5/tengo/objects/builtin_convert.go b/vendor/github.com/d5/tengo/objects/builtin_convert.go
deleted file mode 100644
index b5f2d05d..00000000
--- a/vendor/github.com/d5/tengo/objects/builtin_convert.go
+++ /dev/null
@@ -1,169 +0,0 @@
-package objects
-
-import "github.com/d5/tengo"
-
-func builtinString(args ...Object) (Object, error) {
-	argsLen := len(args)
-	if !(argsLen == 1 || argsLen == 2) {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*String); ok {
-		return args[0], nil
-	}
-
-	v, ok := ToString(args[0])
-	if ok {
-		if len(v) > tengo.MaxStringLen {
-			return nil, ErrStringLimit
-		}
-
-		return &String{Value: v}, nil
-	}
-
-	if argsLen == 2 {
-		return args[1], nil
-	}
-
-	return UndefinedValue, nil
-}
-
-func builtinInt(args ...Object) (Object, error) {
-	argsLen := len(args)
-	if !(argsLen == 1 || argsLen == 2) {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*Int); ok {
-		return args[0], nil
-	}
-
-	v, ok := ToInt64(args[0])
-	if ok {
-		return &Int{Value: v}, nil
-	}
-
-	if argsLen == 2 {
-		return args[1], nil
-	}
-
-	return UndefinedValue, nil
-}
-
-func builtinFloat(args ...Object) (Object, error) {
-	argsLen := len(args)
-	if !(argsLen == 1 || argsLen == 2) {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*Float); ok {
-		return args[0], nil
-	}
-
-	v, ok := ToFloat64(args[0])
-	if ok {
-		return &Float{Value: v}, nil
-	}
-
-	if argsLen == 2 {
-		return args[1], nil
-	}
-
-	return UndefinedValue, nil
-}
-
-func builtinBool(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*Bool); ok {
-		return args[0], nil
-	}
-
-	v, ok := ToBool(args[0])
-	if ok {
-		if v {
-			return TrueValue, nil
-		}
-
-		return FalseValue, nil
-	}
-
-	return UndefinedValue, nil
-}
-
-func builtinChar(args ...Object) (Object, error) {
-	argsLen := len(args)
-	if !(argsLen == 1 || argsLen == 2) {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*Char); ok {
-		return args[0], nil
-	}
-
-	v, ok := ToRune(args[0])
-	if ok {
-		return &Char{Value: v}, nil
-	}
-
-	if argsLen == 2 {
-		return args[1], nil
-	}
-
-	return UndefinedValue, nil
-}
-
-func builtinBytes(args ...Object) (Object, error) {
-	argsLen := len(args)
-	if !(argsLen == 1 || argsLen == 2) {
-		return nil, ErrWrongNumArguments
-	}
-
-	// bytes(N) => create a new bytes with given size N
-	if n, ok := args[0].(*Int); ok {
-		if n.Value > int64(tengo.MaxBytesLen) {
-			return nil, ErrBytesLimit
-		}
-
-		return &Bytes{Value: make([]byte, int(n.Value))}, nil
-	}
-
-	v, ok := ToByteSlice(args[0])
-	if ok {
-		if len(v) > tengo.MaxBytesLen {
-			return nil, ErrBytesLimit
-		}
-
-		return &Bytes{Value: v}, nil
-	}
-
-	if argsLen == 2 {
-		return args[1], nil
-	}
-
-	return UndefinedValue, nil
-}
-
-func builtinTime(args ...Object) (Object, error) {
-	argsLen := len(args)
-	if !(argsLen == 1 || argsLen == 2) {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*Time); ok {
-		return args[0], nil
-	}
-
-	v, ok := ToTime(args[0])
-	if ok {
-		return &Time{Value: v}, nil
-	}
-
-	if argsLen == 2 {
-		return args[1], nil
-	}
-
-	return UndefinedValue, nil
-}
diff --git a/vendor/github.com/d5/tengo/objects/builtin_copy.go b/vendor/github.com/d5/tengo/objects/builtin_copy.go
deleted file mode 100644
index 4b254b2b..00000000
--- a/vendor/github.com/d5/tengo/objects/builtin_copy.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package objects
-
-func builtinCopy(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	return args[0].Copy(), nil
-}
diff --git a/vendor/github.com/d5/tengo/objects/builtin_format.go b/vendor/github.com/d5/tengo/objects/builtin_format.go
deleted file mode 100644
index 1f0e75ed..00000000
--- a/vendor/github.com/d5/tengo/objects/builtin_format.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package objects
-
-func builtinFormat(args ...Object) (Object, error) {
-	numArgs := len(args)
-	if numArgs == 0 {
-		return nil, ErrWrongNumArguments
-	}
-
-	format, ok := args[0].(*String)
-	if !ok {
-		return nil, ErrInvalidArgumentType{
-			Name:     "format",
-			Expected: "string",
-			Found:    args[0].TypeName(),
-		}
-	}
-	if numArgs == 1 {
-		return format, nil // okay to return 'format' directly as String is immutable
-	}
-
-	s, err := Format(format.Value, args[1:]...)
-	if err != nil {
-		return nil, err
-	}
-
-	return &String{Value: s}, nil
-}
diff --git a/vendor/github.com/d5/tengo/objects/builtin_function.go b/vendor/github.com/d5/tengo/objects/builtin_function.go
deleted file mode 100644
index 1d021617..00000000
--- a/vendor/github.com/d5/tengo/objects/builtin_function.go
+++ /dev/null
@@ -1,47 +0,0 @@
-package objects
-
-import (
-	"github.com/d5/tengo/compiler/token"
-)
-
-// BuiltinFunction represents a builtin function.
-type BuiltinFunction struct {
-	Name  string
-	Value CallableFunc
-}
-
-// TypeName returns the name of the type.
-func (o *BuiltinFunction) TypeName() string {
-	return "builtin-function:" + o.Name
-}
-
-func (o *BuiltinFunction) String() string {
-	return "<builtin-function>"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *BuiltinFunction) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *BuiltinFunction) Copy() Object {
-	return &BuiltinFunction{Value: o.Value}
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *BuiltinFunction) IsFalsy() bool {
-	return false
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *BuiltinFunction) Equals(x Object) bool {
-	return false
-}
-
-// Call executes a builtin function.
-func (o *BuiltinFunction) Call(args ...Object) (Object, error) {
-	return o.Value(args...)
-}
diff --git a/vendor/github.com/d5/tengo/objects/builtin_len.go b/vendor/github.com/d5/tengo/objects/builtin_len.go
deleted file mode 100644
index 39fbedd8..00000000
--- a/vendor/github.com/d5/tengo/objects/builtin_len.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package objects
-
-// len(obj object) => int
-func builtinLen(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	switch arg := args[0].(type) {
-	case *Array:
-		return &Int{Value: int64(len(arg.Value))}, nil
-	case *ImmutableArray:
-		return &Int{Value: int64(len(arg.Value))}, nil
-	case *String:
-		return &Int{Value: int64(len(arg.Value))}, nil
-	case *Bytes:
-		return &Int{Value: int64(len(arg.Value))}, nil
-	case *Map:
-		return &Int{Value: int64(len(arg.Value))}, nil
-	case *ImmutableMap:
-		return &Int{Value: int64(len(arg.Value))}, nil
-	default:
-		return nil, ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "array/string/bytes/map",
-			Found:    arg.TypeName(),
-		}
-	}
-}
diff --git a/vendor/github.com/d5/tengo/objects/builtin_module.go b/vendor/github.com/d5/tengo/objects/builtin_module.go
deleted file mode 100644
index 0ad1d99d..00000000
--- a/vendor/github.com/d5/tengo/objects/builtin_module.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package objects
-
-// BuiltinModule is an importable module that's written in Go.
-type BuiltinModule struct {
-	Attrs map[string]Object
-}
-
-// Import returns an immutable map for the module.
-func (m *BuiltinModule) Import(moduleName string) (interface{}, error) {
-	return m.AsImmutableMap(moduleName), nil
-}
-
-// AsImmutableMap converts builtin module into an immutable map.
-func (m *BuiltinModule) AsImmutableMap(moduleName string) *ImmutableMap {
-	attrs := make(map[string]Object, len(m.Attrs))
-	for k, v := range m.Attrs {
-		attrs[k] = v.Copy()
-	}
-
-	attrs["__module_name__"] = &String{Value: moduleName}
-
-	return &ImmutableMap{Value: attrs}
-}
diff --git a/vendor/github.com/d5/tengo/objects/builtin_type.go b/vendor/github.com/d5/tengo/objects/builtin_type.go
deleted file mode 100644
index 376c26bb..00000000
--- a/vendor/github.com/d5/tengo/objects/builtin_type.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package objects
-
-func builtinTypeName(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	return &String{Value: args[0].TypeName()}, nil
-}
diff --git a/vendor/github.com/d5/tengo/objects/builtin_type_checks.go b/vendor/github.com/d5/tengo/objects/builtin_type_checks.go
deleted file mode 100644
index d1e8471d..00000000
--- a/vendor/github.com/d5/tengo/objects/builtin_type_checks.go
+++ /dev/null
@@ -1,195 +0,0 @@
-package objects
-
-func builtinIsString(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*String); ok {
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsInt(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*Int); ok {
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsFloat(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*Float); ok {
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsBool(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*Bool); ok {
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsChar(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*Char); ok {
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsBytes(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*Bytes); ok {
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsArray(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*Array); ok {
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsImmutableArray(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*ImmutableArray); ok {
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsMap(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*Map); ok {
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsImmutableMap(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*ImmutableMap); ok {
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsTime(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*Time); ok {
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsError(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(*Error); ok {
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsUndefined(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if args[0] == UndefinedValue {
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsFunction(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	switch args[0].(type) {
-	case *CompiledFunction, *Closure:
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsCallable(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	switch args[0].(type) {
-	case *CompiledFunction, *Closure, Callable: // BuiltinFunction is Callable
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
-
-func builtinIsIterable(args ...Object) (Object, error) {
-	if len(args) != 1 {
-		return nil, ErrWrongNumArguments
-	}
-
-	if _, ok := args[0].(Iterable); ok {
-		return TrueValue, nil
-	}
-
-	return FalseValue, nil
-}
diff --git a/vendor/github.com/d5/tengo/objects/builtins.go b/vendor/github.com/d5/tengo/objects/builtins.go
deleted file mode 100644
index 773636ec..00000000
--- a/vendor/github.com/d5/tengo/objects/builtins.go
+++ /dev/null
@@ -1,118 +0,0 @@
-package objects
-
-// Builtins contains all default builtin functions.
-// Use GetBuiltinFunctions instead of accessing Builtins directly.
-var Builtins = []*BuiltinFunction{
-	{
-		Name:  "len",
-		Value: builtinLen,
-	},
-	{
-		Name:  "copy",
-		Value: builtinCopy,
-	},
-	{
-		Name:  "append",
-		Value: builtinAppend,
-	},
-	{
-		Name:  "string",
-		Value: builtinString,
-	},
-	{
-		Name:  "int",
-		Value: builtinInt,
-	},
-	{
-		Name:  "bool",
-		Value: builtinBool,
-	},
-	{
-		Name:  "float",
-		Value: builtinFloat,
-	},
-	{
-		Name:  "char",
-		Value: builtinChar,
-	},
-	{
-		Name:  "bytes",
-		Value: builtinBytes,
-	},
-	{
-		Name:  "time",
-		Value: builtinTime,
-	},
-	{
-		Name:  "is_int",
-		Value: builtinIsInt,
-	},
-	{
-		Name:  "is_float",
-		Value: builtinIsFloat,
-	},
-	{
-		Name:  "is_string",
-		Value: builtinIsString,
-	},
-	{
-		Name:  "is_bool",
-		Value: builtinIsBool,
-	},
-	{
-		Name:  "is_char",
-		Value: builtinIsChar,
-	},
-	{
-		Name:  "is_bytes",
-		Value: builtinIsBytes,
-	},
-	{
-		Name:  "is_array",
-		Value: builtinIsArray,
-	},
-	{
-		Name:  "is_immutable_array",
-		Value: builtinIsImmutableArray,
-	},
-	{
-		Name:  "is_map",
-		Value: builtinIsMap,
-	},
-	{
-		Name:  "is_immutable_map",
-		Value: builtinIsImmutableMap,
-	},
-	{
-		Name:  "is_iterable",
-		Value: builtinIsIterable,
-	},
-	{
-		Name:  "is_time",
-		Value: builtinIsTime,
-	},
-	{
-		Name:  "is_error",
-		Value: builtinIsError,
-	},
-	{
-		Name:  "is_undefined",
-		Value: builtinIsUndefined,
-	},
-	{
-		Name:  "is_function",
-		Value: builtinIsFunction,
-	},
-	{
-		Name:  "is_callable",
-		Value: builtinIsCallable,
-	},
-	{
-		Name:  "type_name",
-		Value: builtinTypeName,
-	},
-	{
-		Name:  "format",
-		Value: builtinFormat,
-	},
-}
diff --git a/vendor/github.com/d5/tengo/objects/bytes.go b/vendor/github.com/d5/tengo/objects/bytes.go
deleted file mode 100644
index 5159c22f..00000000
--- a/vendor/github.com/d5/tengo/objects/bytes.go
+++ /dev/null
@@ -1,89 +0,0 @@
-package objects
-
-import (
-	"bytes"
-
-	"github.com/d5/tengo"
-	"github.com/d5/tengo/compiler/token"
-)
-
-// Bytes represents a byte array.
-type Bytes struct {
-	Value []byte
-}
-
-func (o *Bytes) String() string {
-	return string(o.Value)
-}
-
-// TypeName returns the name of the type.
-func (o *Bytes) TypeName() string {
-	return "bytes"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *Bytes) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	switch op {
-	case token.Add:
-		switch rhs := rhs.(type) {
-		case *Bytes:
-			if len(o.Value)+len(rhs.Value) > tengo.MaxBytesLen {
-				return nil, ErrBytesLimit
-			}
-
-			return &Bytes{Value: append(o.Value, rhs.Value...)}, nil
-		}
-	}
-
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *Bytes) Copy() Object {
-	return &Bytes{Value: append([]byte{}, o.Value...)}
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *Bytes) IsFalsy() bool {
-	return len(o.Value) == 0
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *Bytes) Equals(x Object) bool {
-	t, ok := x.(*Bytes)
-	if !ok {
-		return false
-	}
-
-	return bytes.Equal(o.Value, t.Value)
-}
-
-// IndexGet returns an element (as Int) at a given index.
-func (o *Bytes) IndexGet(index Object) (res Object, err error) {
-	intIdx, ok := index.(*Int)
-	if !ok {
-		err = ErrInvalidIndexType
-		return
-	}
-
-	idxVal := int(intIdx.Value)
-
-	if idxVal < 0 || idxVal >= len(o.Value) {
-		res = UndefinedValue
-		return
-	}
-
-	res = &Int{Value: int64(o.Value[idxVal])}
-
-	return
-}
-
-// Iterate creates a bytes iterator.
-func (o *Bytes) Iterate() Iterator {
-	return &BytesIterator{
-		v: o.Value,
-		l: len(o.Value),
-	}
-}
diff --git a/vendor/github.com/d5/tengo/objects/bytes_iterator.go b/vendor/github.com/d5/tengo/objects/bytes_iterator.go
deleted file mode 100644
index 18a36e17..00000000
--- a/vendor/github.com/d5/tengo/objects/bytes_iterator.go
+++ /dev/null
@@ -1,57 +0,0 @@
-package objects
-
-import "github.com/d5/tengo/compiler/token"
-
-// BytesIterator represents an iterator for a string.
-type BytesIterator struct {
-	v []byte
-	i int
-	l int
-}
-
-// TypeName returns the name of the type.
-func (i *BytesIterator) TypeName() string {
-	return "bytes-iterator"
-}
-
-func (i *BytesIterator) String() string {
-	return "<bytes-iterator>"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (i *BytesIterator) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	return nil, ErrInvalidOperator
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (i *BytesIterator) IsFalsy() bool {
-	return true
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (i *BytesIterator) Equals(Object) bool {
-	return false
-}
-
-// Copy returns a copy of the type.
-func (i *BytesIterator) Copy() Object {
-	return &BytesIterator{v: i.v, i: i.i, l: i.l}
-}
-
-// Next returns true if there are more elements to iterate.
-func (i *BytesIterator) Next() bool {
-	i.i++
-	return i.i <= i.l
-}
-
-// Key returns the key or index value of the current element.
-func (i *BytesIterator) Key() Object {
-	return &Int{Value: int64(i.i - 1)}
-}
-
-// Value returns the value of the current element.
-func (i *BytesIterator) Value() Object {
-	return &Int{Value: int64(i.v[i.i-1])}
-}
diff --git a/vendor/github.com/d5/tengo/objects/callable.go b/vendor/github.com/d5/tengo/objects/callable.go
deleted file mode 100644
index a066e1b9..00000000
--- a/vendor/github.com/d5/tengo/objects/callable.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package objects
-
-// Callable represents an object that can be called like a function.
-type Callable interface {
-	// Call should take an arbitrary number of arguments
-	// and returns a return value and/or an error,
-	// which the VM will consider as a run-time error.
-	Call(args ...Object) (ret Object, err error)
-}
diff --git a/vendor/github.com/d5/tengo/objects/callable_func.go b/vendor/github.com/d5/tengo/objects/callable_func.go
deleted file mode 100644
index ad25e65d..00000000
--- a/vendor/github.com/d5/tengo/objects/callable_func.go
+++ /dev/null
@@ -1,4 +0,0 @@
-package objects
-
-// CallableFunc is a function signature for the callable functions.
-type CallableFunc = func(args ...Object) (ret Object, err error)
diff --git a/vendor/github.com/d5/tengo/objects/char.go b/vendor/github.com/d5/tengo/objects/char.go
deleted file mode 100644
index 4458bd12..00000000
--- a/vendor/github.com/d5/tengo/objects/char.go
+++ /dev/null
@@ -1,119 +0,0 @@
-package objects
-
-import (
-	"github.com/d5/tengo/compiler/token"
-)
-
-// Char represents a character value.
-type Char struct {
-	Value rune
-}
-
-func (o *Char) String() string {
-	return string(o.Value)
-}
-
-// TypeName returns the name of the type.
-func (o *Char) TypeName() string {
-	return "char"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *Char) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	switch rhs := rhs.(type) {
-	case *Char:
-		switch op {
-		case token.Add:
-			r := o.Value + rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Char{Value: r}, nil
-		case token.Sub:
-			r := o.Value - rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Char{Value: r}, nil
-		case token.Less:
-			if o.Value < rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.Greater:
-			if o.Value > rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.LessEq:
-			if o.Value <= rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.GreaterEq:
-			if o.Value >= rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		}
-	case *Int:
-		switch op {
-		case token.Add:
-			r := o.Value + rune(rhs.Value)
-			if r == o.Value {
-				return o, nil
-			}
-			return &Char{Value: r}, nil
-		case token.Sub:
-			r := o.Value - rune(rhs.Value)
-			if r == o.Value {
-				return o, nil
-			}
-			return &Char{Value: r}, nil
-		case token.Less:
-			if int64(o.Value) < rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.Greater:
-			if int64(o.Value) > rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.LessEq:
-			if int64(o.Value) <= rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.GreaterEq:
-			if int64(o.Value) >= rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		}
-	}
-
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *Char) Copy() Object {
-	return &Char{Value: o.Value}
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *Char) IsFalsy() bool {
-	return o.Value == 0
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *Char) Equals(x Object) bool {
-	t, ok := x.(*Char)
-	if !ok {
-		return false
-	}
-
-	return o.Value == t.Value
-}
diff --git a/vendor/github.com/d5/tengo/objects/closure.go b/vendor/github.com/d5/tengo/objects/closure.go
deleted file mode 100644
index 06058b23..00000000
--- a/vendor/github.com/d5/tengo/objects/closure.go
+++ /dev/null
@@ -1,45 +0,0 @@
-package objects
-
-import (
-	"github.com/d5/tengo/compiler/token"
-)
-
-// Closure represents a function closure.
-type Closure struct {
-	Fn   *CompiledFunction
-	Free []*ObjectPtr
-}
-
-// TypeName returns the name of the type.
-func (o *Closure) TypeName() string {
-	return "closure"
-}
-
-func (o *Closure) String() string {
-	return "<closure>"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *Closure) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *Closure) Copy() Object {
-	return &Closure{
-		Fn:   o.Fn.Copy().(*CompiledFunction),
-		Free: append([]*ObjectPtr{}, o.Free...), // DO NOT Copy() of elements; these are variable pointers
-	}
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *Closure) IsFalsy() bool {
-	return false
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *Closure) Equals(x Object) bool {
-	return false
-}
diff --git a/vendor/github.com/d5/tengo/objects/compiled_function.go b/vendor/github.com/d5/tengo/objects/compiled_function.go
deleted file mode 100644
index d42e69ec..00000000
--- a/vendor/github.com/d5/tengo/objects/compiled_function.go
+++ /dev/null
@@ -1,62 +0,0 @@
-package objects
-
-import (
-	"github.com/d5/tengo/compiler/source"
-	"github.com/d5/tengo/compiler/token"
-)
-
-// CompiledFunction represents a compiled function.
-type CompiledFunction struct {
-	Instructions  []byte
-	NumLocals     int // number of local variables (including function parameters)
-	NumParameters int
-	VarArgs       bool
-	SourceMap     map[int]source.Pos
-}
-
-// TypeName returns the name of the type.
-func (o *CompiledFunction) TypeName() string {
-	return "compiled-function"
-}
-
-func (o *CompiledFunction) String() string {
-	return "<compiled-function>"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *CompiledFunction) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *CompiledFunction) Copy() Object {
-	return &CompiledFunction{
-		Instructions:  append([]byte{}, o.Instructions...),
-		NumLocals:     o.NumLocals,
-		NumParameters: o.NumParameters,
-		VarArgs:       o.VarArgs,
-	}
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *CompiledFunction) IsFalsy() bool {
-	return false
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *CompiledFunction) Equals(x Object) bool {
-	return false
-}
-
-// SourcePos returns the source position of the instruction at ip.
-func (o *CompiledFunction) SourcePos(ip int) source.Pos {
-	for ip >= 0 {
-		if p, ok := o.SourceMap[ip]; ok {
-			return p
-		}
-		ip--
-	}
-	return source.NoPos
-}
diff --git a/vendor/github.com/d5/tengo/objects/count_objects.go b/vendor/github.com/d5/tengo/objects/count_objects.go
deleted file mode 100644
index 8c482eb3..00000000
--- a/vendor/github.com/d5/tengo/objects/count_objects.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package objects
-
-// CountObjects returns the number of objects that a given object o contains.
-// For scalar value types, it will always be 1. For compound value types,
-// this will include its elements and all of their elements recursively.
-func CountObjects(o Object) (c int) {
-	c = 1
-
-	switch o := o.(type) {
-	case *Array:
-		for _, v := range o.Value {
-			c += CountObjects(v)
-		}
-	case *ImmutableArray:
-		for _, v := range o.Value {
-			c += CountObjects(v)
-		}
-	case *Map:
-		for _, v := range o.Value {
-			c += CountObjects(v)
-		}
-	case *ImmutableMap:
-		for _, v := range o.Value {
-			c += CountObjects(v)
-		}
-	case *Error:
-		c += CountObjects(o.Value)
-	}
-
-	return
-}
diff --git a/vendor/github.com/d5/tengo/objects/error.go b/vendor/github.com/d5/tengo/objects/error.go
deleted file mode 100644
index be21de03..00000000
--- a/vendor/github.com/d5/tengo/objects/error.go
+++ /dev/null
@@ -1,47 +0,0 @@
-package objects
-
-import (
-	"fmt"
-
-	"github.com/d5/tengo/compiler/token"
-)
-
-// Error represents a string value.
-type Error struct {
-	Value Object
-}
-
-// TypeName returns the name of the type.
-func (o *Error) TypeName() string {
-	return "error"
-}
-
-func (o *Error) String() string {
-	if o.Value != nil {
-		return fmt.Sprintf("error: %s", o.Value.String())
-	}
-
-	return "error"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *Error) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	return nil, ErrInvalidOperator
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *Error) IsFalsy() bool {
-	return true // error is always false.
-}
-
-// Copy returns a copy of the type.
-func (o *Error) Copy() Object {
-	return &Error{Value: o.Value.Copy()}
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *Error) Equals(x Object) bool {
-	return o == x // pointer equality
-}
diff --git a/vendor/github.com/d5/tengo/objects/errors.go b/vendor/github.com/d5/tengo/objects/errors.go
deleted file mode 100644
index bcd480a1..00000000
--- a/vendor/github.com/d5/tengo/objects/errors.go
+++ /dev/null
@@ -1,38 +0,0 @@
-package objects
-
-import (
-	"errors"
-	"fmt"
-)
-
-// ErrIndexOutOfBounds is an error where a given index is out of the bounds.
-var ErrIndexOutOfBounds = errors.New("index out of bounds")
-
-// ErrInvalidIndexType represents an invalid index type.
-var ErrInvalidIndexType = errors.New("invalid index type")
-
-// ErrInvalidIndexValueType represents an invalid index value type.
-var ErrInvalidIndexValueType = errors.New("invalid index value type")
-
-// ErrInvalidOperator represents an error for invalid operator usage.
-var ErrInvalidOperator = errors.New("invalid operator")
-
-// ErrWrongNumArguments represents a wrong number of arguments error.
-var ErrWrongNumArguments = errors.New("wrong number of arguments")
-
-// ErrBytesLimit represents an error where the size of bytes value exceeds the limit.
-var ErrBytesLimit = errors.New("exceeding bytes size limit")
-
-// ErrStringLimit represents an error where the size of string value exceeds the limit.
-var ErrStringLimit = errors.New("exceeding string size limit")
-
-// ErrInvalidArgumentType represents an invalid argument value type error.
-type ErrInvalidArgumentType struct {
-	Name     string
-	Expected string
-	Found    string
-}
-
-func (e ErrInvalidArgumentType) Error() string {
-	return fmt.Sprintf("invalid type for argument '%s': expected %s, found %s", e.Name, e.Expected, e.Found)
-}
diff --git a/vendor/github.com/d5/tengo/objects/float.go b/vendor/github.com/d5/tengo/objects/float.go
deleted file mode 100644
index 65997303..00000000
--- a/vendor/github.com/d5/tengo/objects/float.go
+++ /dev/null
@@ -1,146 +0,0 @@
-package objects
-
-import (
-	"math"
-	"strconv"
-
-	"github.com/d5/tengo/compiler/token"
-)
-
-// Float represents a floating point number value.
-type Float struct {
-	Value float64
-}
-
-func (o *Float) String() string {
-	return strconv.FormatFloat(o.Value, 'f', -1, 64)
-}
-
-// TypeName returns the name of the type.
-func (o *Float) TypeName() string {
-	return "float"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *Float) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	switch rhs := rhs.(type) {
-	case *Float:
-		switch op {
-		case token.Add:
-			r := o.Value + rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Float{Value: r}, nil
-		case token.Sub:
-			r := o.Value - rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Float{Value: r}, nil
-		case token.Mul:
-			r := o.Value * rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Float{Value: r}, nil
-		case token.Quo:
-			r := o.Value / rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Float{Value: r}, nil
-		case token.Less:
-			if o.Value < rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.Greater:
-			if o.Value > rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.LessEq:
-			if o.Value <= rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.GreaterEq:
-			if o.Value >= rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		}
-	case *Int:
-		switch op {
-		case token.Add:
-			r := o.Value + float64(rhs.Value)
-			if r == o.Value {
-				return o, nil
-			}
-			return &Float{Value: r}, nil
-		case token.Sub:
-			r := o.Value - float64(rhs.Value)
-			if r == o.Value {
-				return o, nil
-			}
-			return &Float{Value: r}, nil
-		case token.Mul:
-			r := o.Value * float64(rhs.Value)
-			if r == o.Value {
-				return o, nil
-			}
-			return &Float{Value: r}, nil
-		case token.Quo:
-			r := o.Value / float64(rhs.Value)
-			if r == o.Value {
-				return o, nil
-			}
-			return &Float{Value: r}, nil
-		case token.Less:
-			if o.Value < float64(rhs.Value) {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.Greater:
-			if o.Value > float64(rhs.Value) {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.LessEq:
-			if o.Value <= float64(rhs.Value) {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.GreaterEq:
-			if o.Value >= float64(rhs.Value) {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		}
-	}
-
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *Float) Copy() Object {
-	return &Float{Value: o.Value}
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *Float) IsFalsy() bool {
-	return math.IsNaN(o.Value)
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *Float) Equals(x Object) bool {
-	t, ok := x.(*Float)
-	if !ok {
-		return false
-	}
-
-	return o.Value == t.Value
-}
diff --git a/vendor/github.com/d5/tengo/objects/immutable_array.go b/vendor/github.com/d5/tengo/objects/immutable_array.go
deleted file mode 100644
index f3621e29..00000000
--- a/vendor/github.com/d5/tengo/objects/immutable_array.go
+++ /dev/null
@@ -1,109 +0,0 @@
-package objects
-
-import (
-	"fmt"
-	"strings"
-
-	"github.com/d5/tengo/compiler/token"
-)
-
-// ImmutableArray represents an immutable array of objects.
-type ImmutableArray struct {
-	Value []Object
-}
-
-// TypeName returns the name of the type.
-func (o *ImmutableArray) TypeName() string {
-	return "immutable-array"
-}
-
-func (o *ImmutableArray) String() string {
-	var elements []string
-	for _, e := range o.Value {
-		elements = append(elements, e.String())
-	}
-
-	return fmt.Sprintf("[%s]", strings.Join(elements, ", "))
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *ImmutableArray) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	if rhs, ok := rhs.(*ImmutableArray); ok {
-		switch op {
-		case token.Add:
-			return &Array{Value: append(o.Value, rhs.Value...)}, nil
-		}
-	}
-
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *ImmutableArray) Copy() Object {
-	var c []Object
-	for _, elem := range o.Value {
-		c = append(c, elem.Copy())
-	}
-
-	return &Array{Value: c}
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *ImmutableArray) IsFalsy() bool {
-	return len(o.Value) == 0
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *ImmutableArray) Equals(x Object) bool {
-	var xVal []Object
-	switch x := x.(type) {
-	case *Array:
-		xVal = x.Value
-	case *ImmutableArray:
-		xVal = x.Value
-	default:
-		return false
-	}
-
-	if len(o.Value) != len(xVal) {
-		return false
-	}
-
-	for i, e := range o.Value {
-		if !e.Equals(xVal[i]) {
-			return false
-		}
-	}
-
-	return true
-}
-
-// IndexGet returns an element at a given index.
-func (o *ImmutableArray) IndexGet(index Object) (res Object, err error) {
-	intIdx, ok := index.(*Int)
-	if !ok {
-		err = ErrInvalidIndexType
-		return
-	}
-
-	idxVal := int(intIdx.Value)
-
-	if idxVal < 0 || idxVal >= len(o.Value) {
-		res = UndefinedValue
-		return
-	}
-
-	res = o.Value[idxVal]
-
-	return
-}
-
-// Iterate creates an array iterator.
-func (o *ImmutableArray) Iterate() Iterator {
-	return &ArrayIterator{
-		v: o.Value,
-		l: len(o.Value),
-	}
-}
diff --git a/vendor/github.com/d5/tengo/objects/immutable_map.go b/vendor/github.com/d5/tengo/objects/immutable_map.go
deleted file mode 100644
index 8f58701b..00000000
--- a/vendor/github.com/d5/tengo/objects/immutable_map.go
+++ /dev/null
@@ -1,105 +0,0 @@
-package objects
-
-import (
-	"fmt"
-	"strings"
-
-	"github.com/d5/tengo/compiler/token"
-)
-
-// ImmutableMap represents an immutable map object.
-type ImmutableMap struct {
-	Value map[string]Object
-}
-
-// TypeName returns the name of the type.
-func (o *ImmutableMap) TypeName() string {
-	return "immutable-map"
-}
-
-func (o *ImmutableMap) String() string {
-	var pairs []string
-	for k, v := range o.Value {
-		pairs = append(pairs, fmt.Sprintf("%s: %s", k, v.String()))
-	}
-
-	return fmt.Sprintf("{%s}", strings.Join(pairs, ", "))
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *ImmutableMap) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *ImmutableMap) Copy() Object {
-	c := make(map[string]Object)
-	for k, v := range o.Value {
-		c[k] = v.Copy()
-	}
-
-	return &Map{Value: c}
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *ImmutableMap) IsFalsy() bool {
-	return len(o.Value) == 0
-}
-
-// IndexGet returns the value for the given key.
-func (o *ImmutableMap) IndexGet(index Object) (res Object, err error) {
-	strIdx, ok := ToString(index)
-	if !ok {
-		err = ErrInvalidIndexType
-		return
-	}
-
-	val, ok := o.Value[strIdx]
-	if !ok {
-		val = UndefinedValue
-	}
-
-	return val, nil
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *ImmutableMap) Equals(x Object) bool {
-	var xVal map[string]Object
-	switch x := x.(type) {
-	case *Map:
-		xVal = x.Value
-	case *ImmutableMap:
-		xVal = x.Value
-	default:
-		return false
-	}
-
-	if len(o.Value) != len(xVal) {
-		return false
-	}
-
-	for k, v := range o.Value {
-		tv := xVal[k]
-		if !v.Equals(tv) {
-			return false
-		}
-	}
-
-	return true
-}
-
-// Iterate creates an immutable map iterator.
-func (o *ImmutableMap) Iterate() Iterator {
-	var keys []string
-	for k := range o.Value {
-		keys = append(keys, k)
-	}
-
-	return &MapIterator{
-		v: o.Value,
-		k: keys,
-		l: len(keys),
-	}
-}
diff --git a/vendor/github.com/d5/tengo/objects/importable.go b/vendor/github.com/d5/tengo/objects/importable.go
deleted file mode 100644
index 9fd86ae8..00000000
--- a/vendor/github.com/d5/tengo/objects/importable.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package objects
-
-// Importable interface represents importable module instance.
-type Importable interface {
-	// Import should return either an Object or module source code ([]byte).
-	Import(moduleName string) (interface{}, error)
-}
diff --git a/vendor/github.com/d5/tengo/objects/index_assignable.go b/vendor/github.com/d5/tengo/objects/index_assignable.go
deleted file mode 100644
index a1c6cbff..00000000
--- a/vendor/github.com/d5/tengo/objects/index_assignable.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package objects
-
-// IndexAssignable is an object that can take an index and a value
-// on the left-hand side of the assignment statement.
-type IndexAssignable interface {
-	// IndexSet should take an index Object and a value Object.
-	// If an error is returned, it will be treated as a run-time error.
-	IndexSet(index, value Object) error
-}
diff --git a/vendor/github.com/d5/tengo/objects/indexable.go b/vendor/github.com/d5/tengo/objects/indexable.go
deleted file mode 100644
index bbc81633..00000000
--- a/vendor/github.com/d5/tengo/objects/indexable.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package objects
-
-// Indexable is an object that can take an index and return an object.
-type Indexable interface {
-	// IndexGet should take an index Object and return a result Object or an error.
-	// If error is returned, the runtime will treat it as a run-time error and ignore returned value.
-	// If nil is returned as value, it will be converted to Undefined value by the runtime.
-	IndexGet(index Object) (value Object, err error)
-}
diff --git a/vendor/github.com/d5/tengo/objects/int.go b/vendor/github.com/d5/tengo/objects/int.go
deleted file mode 100644
index e902c93a..00000000
--- a/vendor/github.com/d5/tengo/objects/int.go
+++ /dev/null
@@ -1,198 +0,0 @@
-package objects
-
-import (
-	"strconv"
-
-	"github.com/d5/tengo/compiler/token"
-)
-
-// Int represents an integer value.
-type Int struct {
-	Value int64
-}
-
-func (o *Int) String() string {
-	return strconv.FormatInt(o.Value, 10)
-}
-
-// TypeName returns the name of the type.
-func (o *Int) TypeName() string {
-	return "int"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *Int) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	switch rhs := rhs.(type) {
-	case *Int:
-		switch op {
-		case token.Add:
-			r := o.Value + rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Int{Value: r}, nil
-		case token.Sub:
-			r := o.Value - rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Int{Value: r}, nil
-		case token.Mul:
-			r := o.Value * rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Int{Value: r}, nil
-		case token.Quo:
-			r := o.Value / rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Int{Value: r}, nil
-		case token.Rem:
-			r := o.Value % rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Int{Value: r}, nil
-		case token.And:
-			r := o.Value & rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Int{Value: r}, nil
-		case token.Or:
-			r := o.Value | rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Int{Value: r}, nil
-		case token.Xor:
-			r := o.Value ^ rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Int{Value: r}, nil
-		case token.AndNot:
-			r := o.Value &^ rhs.Value
-			if r == o.Value {
-				return o, nil
-			}
-			return &Int{Value: r}, nil
-		case token.Shl:
-			r := o.Value << uint64(rhs.Value)
-			if r == o.Value {
-				return o, nil
-			}
-			return &Int{Value: r}, nil
-		case token.Shr:
-			r := o.Value >> uint64(rhs.Value)
-			if r == o.Value {
-				return o, nil
-			}
-			return &Int{Value: r}, nil
-		case token.Less:
-			if o.Value < rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.Greater:
-			if o.Value > rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.LessEq:
-			if o.Value <= rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.GreaterEq:
-			if o.Value >= rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		}
-	case *Float:
-		switch op {
-		case token.Add:
-			return &Float{float64(o.Value) + rhs.Value}, nil
-		case token.Sub:
-			return &Float{float64(o.Value) - rhs.Value}, nil
-		case token.Mul:
-			return &Float{float64(o.Value) * rhs.Value}, nil
-		case token.Quo:
-			return &Float{float64(o.Value) / rhs.Value}, nil
-		case token.Less:
-			if float64(o.Value) < rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.Greater:
-			if float64(o.Value) > rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.LessEq:
-			if float64(o.Value) <= rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.GreaterEq:
-			if float64(o.Value) >= rhs.Value {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		}
-	case *Char:
-		switch op {
-		case token.Add:
-			return &Char{rune(o.Value) + rhs.Value}, nil
-		case token.Sub:
-			return &Char{rune(o.Value) - rhs.Value}, nil
-		case token.Less:
-			if o.Value < int64(rhs.Value) {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.Greater:
-			if o.Value > int64(rhs.Value) {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.LessEq:
-			if o.Value <= int64(rhs.Value) {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.GreaterEq:
-			if o.Value >= int64(rhs.Value) {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		}
-	}
-
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *Int) Copy() Object {
-	return &Int{Value: o.Value}
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *Int) IsFalsy() bool {
-	return o.Value == 0
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *Int) Equals(x Object) bool {
-	t, ok := x.(*Int)
-	if !ok {
-		return false
-	}
-
-	return o.Value == t.Value
-}
diff --git a/vendor/github.com/d5/tengo/objects/iterable.go b/vendor/github.com/d5/tengo/objects/iterable.go
deleted file mode 100644
index e431d3d7..00000000
--- a/vendor/github.com/d5/tengo/objects/iterable.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package objects
-
-// Iterable represents an object that has iterator.
-type Iterable interface {
-	// Iterate should return an Iterator for the type.
-	Iterate() Iterator
-}
diff --git a/vendor/github.com/d5/tengo/objects/iterator.go b/vendor/github.com/d5/tengo/objects/iterator.go
deleted file mode 100644
index 01522ba5..00000000
--- a/vendor/github.com/d5/tengo/objects/iterator.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package objects
-
-// Iterator represents an iterator for underlying data type.
-type Iterator interface {
-	Object
-
-	// Next returns true if there are more elements to iterate.
-	Next() bool
-
-	// Key returns the key or index value of the current element.
-	Key() Object
-
-	// Value returns the value of the current element.
-	Value() Object
-}
diff --git a/vendor/github.com/d5/tengo/objects/map.go b/vendor/github.com/d5/tengo/objects/map.go
deleted file mode 100644
index 9208872c..00000000
--- a/vendor/github.com/d5/tengo/objects/map.go
+++ /dev/null
@@ -1,118 +0,0 @@
-package objects
-
-import (
-	"fmt"
-	"strings"
-
-	"github.com/d5/tengo/compiler/token"
-)
-
-// Map represents a map of objects.
-type Map struct {
-	Value map[string]Object
-}
-
-// TypeName returns the name of the type.
-func (o *Map) TypeName() string {
-	return "map"
-}
-
-func (o *Map) String() string {
-	var pairs []string
-	for k, v := range o.Value {
-		pairs = append(pairs, fmt.Sprintf("%s: %s", k, v.String()))
-	}
-
-	return fmt.Sprintf("{%s}", strings.Join(pairs, ", "))
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *Map) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *Map) Copy() Object {
-	c := make(map[string]Object)
-	for k, v := range o.Value {
-		c[k] = v.Copy()
-	}
-
-	return &Map{Value: c}
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *Map) IsFalsy() bool {
-	return len(o.Value) == 0
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *Map) Equals(x Object) bool {
-	var xVal map[string]Object
-	switch x := x.(type) {
-	case *Map:
-		xVal = x.Value
-	case *ImmutableMap:
-		xVal = x.Value
-	default:
-		return false
-	}
-
-	if len(o.Value) != len(xVal) {
-		return false
-	}
-
-	for k, v := range o.Value {
-		tv := xVal[k]
-		if !v.Equals(tv) {
-			return false
-		}
-	}
-
-	return true
-}
-
-// IndexGet returns the value for the given key.
-func (o *Map) IndexGet(index Object) (res Object, err error) {
-	strIdx, ok := ToString(index)
-	if !ok {
-		err = ErrInvalidIndexType
-		return
-	}
-
-	val, ok := o.Value[strIdx]
-	if !ok {
-		val = UndefinedValue
-	}
-
-	return val, nil
-}
-
-// IndexSet sets the value for the given key.
-func (o *Map) IndexSet(index, value Object) (err error) {
-	strIdx, ok := ToString(index)
-	if !ok {
-		err = ErrInvalidIndexType
-		return
-	}
-
-	o.Value[strIdx] = value
-
-	return nil
-}
-
-// Iterate creates a map iterator.
-func (o *Map) Iterate() Iterator {
-	var keys []string
-	for k := range o.Value {
-		keys = append(keys, k)
-	}
-
-	return &MapIterator{
-		v: o.Value,
-		k: keys,
-		l: len(keys),
-	}
-}
diff --git a/vendor/github.com/d5/tengo/objects/map_iterator.go b/vendor/github.com/d5/tengo/objects/map_iterator.go
deleted file mode 100644
index d60dd0e1..00000000
--- a/vendor/github.com/d5/tengo/objects/map_iterator.go
+++ /dev/null
@@ -1,62 +0,0 @@
-package objects
-
-import "github.com/d5/tengo/compiler/token"
-
-// MapIterator represents an iterator for the map.
-type MapIterator struct {
-	v map[string]Object
-	k []string
-	i int
-	l int
-}
-
-// TypeName returns the name of the type.
-func (i *MapIterator) TypeName() string {
-	return "map-iterator"
-}
-
-func (i *MapIterator) String() string {
-	return "<map-iterator>"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (i *MapIterator) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	return nil, ErrInvalidOperator
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (i *MapIterator) IsFalsy() bool {
-	return true
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (i *MapIterator) Equals(Object) bool {
-	return false
-}
-
-// Copy returns a copy of the type.
-func (i *MapIterator) Copy() Object {
-	return &MapIterator{v: i.v, k: i.k, i: i.i, l: i.l}
-}
-
-// Next returns true if there are more elements to iterate.
-func (i *MapIterator) Next() bool {
-	i.i++
-	return i.i <= i.l
-}
-
-// Key returns the key or index value of the current element.
-func (i *MapIterator) Key() Object {
-	k := i.k[i.i-1]
-
-	return &String{Value: k}
-}
-
-// Value returns the value of the current element.
-func (i *MapIterator) Value() Object {
-	k := i.k[i.i-1]
-
-	return i.v[k]
-}
diff --git a/vendor/github.com/d5/tengo/objects/object.go b/vendor/github.com/d5/tengo/objects/object.go
deleted file mode 100644
index 4c5aa7ae..00000000
--- a/vendor/github.com/d5/tengo/objects/object.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package objects
-
-import "github.com/d5/tengo/compiler/token"
-
-// Object represents an object in the VM.
-type Object interface {
-	// TypeName should return the name of the type.
-	TypeName() string
-
-	// String should return a string representation of the type's value.
-	String() string
-
-	// BinaryOp should return another object that is the result of
-	// a given binary operator and a right-hand side object.
-	// If BinaryOp returns an error, the VM will treat it as a run-time error.
-	BinaryOp(op token.Token, rhs Object) (Object, error)
-
-	// IsFalsy should return true if the value of the type
-	// should be considered as falsy.
-	IsFalsy() bool
-
-	// Equals should return true if the value of the type
-	// should be considered as equal to the value of another object.
-	Equals(another Object) bool
-
-	// Copy should return a copy of the type (and its value).
-	// Copy function will be used for copy() builtin function
-	// which is expected to deep-copy the values generally.
-	Copy() Object
-}
diff --git a/vendor/github.com/d5/tengo/objects/object_ptr.go b/vendor/github.com/d5/tengo/objects/object_ptr.go
deleted file mode 100644
index 2c87c561..00000000
--- a/vendor/github.com/d5/tengo/objects/object_ptr.go
+++ /dev/null
@@ -1,41 +0,0 @@
-package objects
-
-import (
-	"github.com/d5/tengo/compiler/token"
-)
-
-// ObjectPtr represents a free variable.
-type ObjectPtr struct {
-	Value *Object
-}
-
-func (o *ObjectPtr) String() string {
-	return "free-var"
-}
-
-// TypeName returns the name of the type.
-func (o *ObjectPtr) TypeName() string {
-	return "<free-var>"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *ObjectPtr) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *ObjectPtr) Copy() Object {
-	return o
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *ObjectPtr) IsFalsy() bool {
-	return o.Value == nil
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *ObjectPtr) Equals(x Object) bool {
-	return o == x
-}
diff --git a/vendor/github.com/d5/tengo/objects/objects.go b/vendor/github.com/d5/tengo/objects/objects.go
deleted file mode 100644
index f3878b11..00000000
--- a/vendor/github.com/d5/tengo/objects/objects.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package objects
-
-var (
-	// TrueValue represents a true value.
-	TrueValue Object = &Bool{value: true}
-
-	// FalseValue represents a false value.
-	FalseValue Object = &Bool{value: false}
-
-	// UndefinedValue represents an undefined value.
-	UndefinedValue Object = &Undefined{}
-)
diff --git a/vendor/github.com/d5/tengo/objects/source_module.go b/vendor/github.com/d5/tengo/objects/source_module.go
deleted file mode 100644
index 577fddf2..00000000
--- a/vendor/github.com/d5/tengo/objects/source_module.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package objects
-
-// SourceModule is an importable module that's written in Tengo.
-type SourceModule struct {
-	Src []byte
-}
-
-// Import returns a module source code.
-func (m *SourceModule) Import(_ string) (interface{}, error) {
-	return m.Src, nil
-}
diff --git a/vendor/github.com/d5/tengo/objects/string.go b/vendor/github.com/d5/tengo/objects/string.go
deleted file mode 100644
index c25b0502..00000000
--- a/vendor/github.com/d5/tengo/objects/string.go
+++ /dev/null
@@ -1,103 +0,0 @@
-package objects
-
-import (
-	"strconv"
-
-	"github.com/d5/tengo"
-	"github.com/d5/tengo/compiler/token"
-)
-
-// String represents a string value.
-type String struct {
-	Value   string
-	runeStr []rune
-}
-
-// TypeName returns the name of the type.
-func (o *String) TypeName() string {
-	return "string"
-}
-
-func (o *String) String() string {
-	return strconv.Quote(o.Value)
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *String) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	switch op {
-	case token.Add:
-		switch rhs := rhs.(type) {
-		case *String:
-			if len(o.Value)+len(rhs.Value) > tengo.MaxStringLen {
-				return nil, ErrStringLimit
-			}
-			return &String{Value: o.Value + rhs.Value}, nil
-		default:
-			rhsStr := rhs.String()
-			if len(o.Value)+len(rhsStr) > tengo.MaxStringLen {
-				return nil, ErrStringLimit
-			}
-			return &String{Value: o.Value + rhsStr}, nil
-		}
-	}
-
-	return nil, ErrInvalidOperator
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *String) IsFalsy() bool {
-	return len(o.Value) == 0
-}
-
-// Copy returns a copy of the type.
-func (o *String) Copy() Object {
-	return &String{Value: o.Value}
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *String) Equals(x Object) bool {
-	t, ok := x.(*String)
-	if !ok {
-		return false
-	}
-
-	return o.Value == t.Value
-}
-
-// IndexGet returns a character at a given index.
-func (o *String) IndexGet(index Object) (res Object, err error) {
-	intIdx, ok := index.(*Int)
-	if !ok {
-		err = ErrInvalidIndexType
-		return
-	}
-
-	idxVal := int(intIdx.Value)
-
-	if o.runeStr == nil {
-		o.runeStr = []rune(o.Value)
-	}
-
-	if idxVal < 0 || idxVal >= len(o.runeStr) {
-		res = UndefinedValue
-		return
-	}
-
-	res = &Char{Value: o.runeStr[idxVal]}
-
-	return
-}
-
-// Iterate creates a string iterator.
-func (o *String) Iterate() Iterator {
-	if o.runeStr == nil {
-		o.runeStr = []rune(o.Value)
-	}
-
-	return &StringIterator{
-		v: o.runeStr,
-		l: len(o.runeStr),
-	}
-}
diff --git a/vendor/github.com/d5/tengo/objects/string_iterator.go b/vendor/github.com/d5/tengo/objects/string_iterator.go
deleted file mode 100644
index 8bc95eb5..00000000
--- a/vendor/github.com/d5/tengo/objects/string_iterator.go
+++ /dev/null
@@ -1,57 +0,0 @@
-package objects
-
-import "github.com/d5/tengo/compiler/token"
-
-// StringIterator represents an iterator for a string.
-type StringIterator struct {
-	v []rune
-	i int
-	l int
-}
-
-// TypeName returns the name of the type.
-func (i *StringIterator) TypeName() string {
-	return "string-iterator"
-}
-
-func (i *StringIterator) String() string {
-	return "<string-iterator>"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (i *StringIterator) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	return nil, ErrInvalidOperator
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (i *StringIterator) IsFalsy() bool {
-	return true
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (i *StringIterator) Equals(Object) bool {
-	return false
-}
-
-// Copy returns a copy of the type.
-func (i *StringIterator) Copy() Object {
-	return &StringIterator{v: i.v, i: i.i, l: i.l}
-}
-
-// Next returns true if there are more elements to iterate.
-func (i *StringIterator) Next() bool {
-	i.i++
-	return i.i <= i.l
-}
-
-// Key returns the key or index value of the current element.
-func (i *StringIterator) Key() Object {
-	return &Int{Value: int64(i.i - 1)}
-}
-
-// Value returns the value of the current element.
-func (i *StringIterator) Value() Object {
-	return &Char{Value: i.v[i.i-1]}
-}
diff --git a/vendor/github.com/d5/tengo/objects/time.go b/vendor/github.com/d5/tengo/objects/time.go
deleted file mode 100644
index 4e783cc8..00000000
--- a/vendor/github.com/d5/tengo/objects/time.go
+++ /dev/null
@@ -1,89 +0,0 @@
-package objects
-
-import (
-	"time"
-
-	"github.com/d5/tengo/compiler/token"
-)
-
-// Time represents a time value.
-type Time struct {
-	Value time.Time
-}
-
-func (o *Time) String() string {
-	return o.Value.String()
-}
-
-// TypeName returns the name of the type.
-func (o *Time) TypeName() string {
-	return "time"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *Time) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	switch rhs := rhs.(type) {
-	case *Int:
-		switch op {
-		case token.Add: // time + int => time
-			if rhs.Value == 0 {
-				return o, nil
-			}
-			return &Time{Value: o.Value.Add(time.Duration(rhs.Value))}, nil
-		case token.Sub: // time - int => time
-			if rhs.Value == 0 {
-				return o, nil
-			}
-			return &Time{Value: o.Value.Add(time.Duration(-rhs.Value))}, nil
-		}
-	case *Time:
-		switch op {
-		case token.Sub: // time - time => int (duration)
-			return &Int{Value: int64(o.Value.Sub(rhs.Value))}, nil
-		case token.Less: // time < time => bool
-			if o.Value.Before(rhs.Value) {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.Greater:
-			if o.Value.After(rhs.Value) {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.LessEq:
-			if o.Value.Equal(rhs.Value) || o.Value.Before(rhs.Value) {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		case token.GreaterEq:
-			if o.Value.Equal(rhs.Value) || o.Value.After(rhs.Value) {
-				return TrueValue, nil
-			}
-			return FalseValue, nil
-		}
-	}
-
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *Time) Copy() Object {
-	return &Time{Value: o.Value}
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *Time) IsFalsy() bool {
-	return o.Value.IsZero()
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *Time) Equals(x Object) bool {
-	t, ok := x.(*Time)
-	if !ok {
-		return false
-	}
-
-	return o.Value.Equal(t.Value)
-}
diff --git a/vendor/github.com/d5/tengo/objects/undefined.go b/vendor/github.com/d5/tengo/objects/undefined.go
deleted file mode 100644
index 0fdbc084..00000000
--- a/vendor/github.com/d5/tengo/objects/undefined.go
+++ /dev/null
@@ -1,62 +0,0 @@
-package objects
-
-import "github.com/d5/tengo/compiler/token"
-
-// Undefined represents an undefined value.
-type Undefined struct{}
-
-// TypeName returns the name of the type.
-func (o *Undefined) TypeName() string {
-	return "undefined"
-}
-
-func (o *Undefined) String() string {
-	return "<undefined>"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *Undefined) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *Undefined) Copy() Object {
-	return o
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *Undefined) IsFalsy() bool {
-	return true
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *Undefined) Equals(x Object) bool {
-	return o == x
-}
-
-// IndexGet returns an element at a given index.
-func (o *Undefined) IndexGet(index Object) (Object, error) {
-	return UndefinedValue, nil
-}
-
-// Iterate creates a map iterator.
-func (o *Undefined) Iterate() Iterator {
-	return o
-}
-
-// Next returns true if there are more elements to iterate.
-func (o *Undefined) Next() bool {
-	return false
-}
-
-// Key returns the key or index value of the current element.
-func (o *Undefined) Key() Object {
-	return o
-}
-
-// Value returns the value of the current element.
-func (o *Undefined) Value() Object {
-	return o
-}
diff --git a/vendor/github.com/d5/tengo/objects/user_function.go b/vendor/github.com/d5/tengo/objects/user_function.go
deleted file mode 100644
index a896788b..00000000
--- a/vendor/github.com/d5/tengo/objects/user_function.go
+++ /dev/null
@@ -1,48 +0,0 @@
-package objects
-
-import (
-	"github.com/d5/tengo/compiler/token"
-)
-
-// UserFunction represents a user function.
-type UserFunction struct {
-	Name       string
-	Value      CallableFunc
-	EncodingID string
-}
-
-// TypeName returns the name of the type.
-func (o *UserFunction) TypeName() string {
-	return "user-function:" + o.Name
-}
-
-func (o *UserFunction) String() string {
-	return "<user-function>"
-}
-
-// BinaryOp returns another object that is the result of
-// a given binary operator and a right-hand side object.
-func (o *UserFunction) BinaryOp(op token.Token, rhs Object) (Object, error) {
-	return nil, ErrInvalidOperator
-}
-
-// Copy returns a copy of the type.
-func (o *UserFunction) Copy() Object {
-	return &UserFunction{Value: o.Value}
-}
-
-// IsFalsy returns true if the value of the type is falsy.
-func (o *UserFunction) IsFalsy() bool {
-	return false
-}
-
-// Equals returns true if the value of the type
-// is equal to the value of another object.
-func (o *UserFunction) Equals(x Object) bool {
-	return false
-}
-
-// Call invokes a user function.
-func (o *UserFunction) Call(args ...Object) (Object, error) {
-	return o.Value(args...)
-}
diff --git a/vendor/github.com/d5/tengo/runtime/errors.go b/vendor/github.com/d5/tengo/runtime/errors.go
deleted file mode 100644
index fc7ca0e9..00000000
--- a/vendor/github.com/d5/tengo/runtime/errors.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package runtime
-
-import (
-	"errors"
-)
-
-// ErrStackOverflow is a stack overflow error.
-var ErrStackOverflow = errors.New("stack overflow")
-
-// ErrObjectAllocLimit is an objects allocation limit error.
-var ErrObjectAllocLimit = errors.New("object allocation limit exceeded")
diff --git a/vendor/github.com/d5/tengo/runtime/frame.go b/vendor/github.com/d5/tengo/runtime/frame.go
deleted file mode 100644
index cbaadbdb..00000000
--- a/vendor/github.com/d5/tengo/runtime/frame.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package runtime
-
-import (
-	"github.com/d5/tengo/objects"
-)
-
-// Frame represents a function call frame.
-type Frame struct {
-	fn          *objects.CompiledFunction
-	freeVars    []*objects.ObjectPtr
-	ip          int
-	basePointer int
-}
diff --git a/vendor/github.com/d5/tengo/script/compiled.go b/vendor/github.com/d5/tengo/script/compiled.go
deleted file mode 100644
index ce50f498..00000000
--- a/vendor/github.com/d5/tengo/script/compiled.go
+++ /dev/null
@@ -1,159 +0,0 @@
-package script
-
-import (
-	"context"
-	"fmt"
-	"sync"
-
-	"github.com/d5/tengo/compiler"
-	"github.com/d5/tengo/objects"
-	"github.com/d5/tengo/runtime"
-)
-
-// Compiled is a compiled instance of the user script.
-// Use Script.Compile() to create Compiled object.
-type Compiled struct {
-	globalIndexes map[string]int // global symbol name to index
-	bytecode      *compiler.Bytecode
-	globals       []objects.Object
-	maxAllocs     int64
-	lock          sync.RWMutex
-}
-
-// Run executes the compiled script in the virtual machine.
-func (c *Compiled) Run() error {
-	c.lock.Lock()
-	defer c.lock.Unlock()
-
-	v := runtime.NewVM(c.bytecode, c.globals, c.maxAllocs)
-
-	return v.Run()
-}
-
-// RunContext is like Run but includes a context.
-func (c *Compiled) RunContext(ctx context.Context) (err error) {
-	c.lock.Lock()
-	defer c.lock.Unlock()
-
-	v := runtime.NewVM(c.bytecode, c.globals, c.maxAllocs)
-
-	ch := make(chan error, 1)
-
-	go func() {
-		ch <- v.Run()
-	}()
-
-	select {
-	case <-ctx.Done():
-		v.Abort()
-		<-ch
-		err = ctx.Err()
-	case err = <-ch:
-	}
-
-	return
-}
-
-// Clone creates a new copy of Compiled.
-// Cloned copies are safe for concurrent use by multiple goroutines.
-func (c *Compiled) Clone() *Compiled {
-	c.lock.Lock()
-	defer c.lock.Unlock()
-
-	clone := &Compiled{
-		globalIndexes: c.globalIndexes,
-		bytecode:      c.bytecode,
-		globals:       make([]objects.Object, len(c.globals)),
-		maxAllocs:     c.maxAllocs,
-	}
-
-	// copy global objects
-	for idx, g := range c.globals {
-		if g != nil {
-			clone.globals[idx] = g
-		}
-	}
-
-	return clone
-}
-
-// IsDefined returns true if the variable name is defined (has value) before or after the execution.
-func (c *Compiled) IsDefined(name string) bool {
-	c.lock.RLock()
-	defer c.lock.RUnlock()
-
-	idx, ok := c.globalIndexes[name]
-	if !ok {
-		return false
-	}
-
-	v := c.globals[idx]
-	if v == nil {
-		return false
-	}
-
-	return v != objects.UndefinedValue
-}
-
-// Get returns a variable identified by the name.
-func (c *Compiled) Get(name string) *Variable {
-	c.lock.RLock()
-	defer c.lock.RUnlock()
-
-	value := objects.UndefinedValue
-
-	if idx, ok := c.globalIndexes[name]; ok {
-		value = c.globals[idx]
-		if value == nil {
-			value = objects.UndefinedValue
-		}
-	}
-
-	return &Variable{
-		name:  name,
-		value: value,
-	}
-}
-
-// GetAll returns all the variables that are defined by the compiled script.
-func (c *Compiled) GetAll() []*Variable {
-	c.lock.RLock()
-	defer c.lock.RUnlock()
-
-	var vars []*Variable
-
-	for name, idx := range c.globalIndexes {
-		value := c.globals[idx]
-		if value == nil {
-			value = objects.UndefinedValue
-		}
-
-		vars = append(vars, &Variable{
-			name:  name,
-			value: value,
-		})
-	}
-
-	return vars
-}
-
-// Set replaces the value of a global variable identified by the name.
-// An error will be returned if the name was not defined during compilation.
-func (c *Compiled) Set(name string, value interface{}) error {
-	c.lock.Lock()
-	defer c.lock.Unlock()
-
-	obj, err := objects.FromInterface(value)
-	if err != nil {
-		return err
-	}
-
-	idx, ok := c.globalIndexes[name]
-	if !ok {
-		return fmt.Errorf("'%s' is not defined", name)
-	}
-
-	c.globals[idx] = obj
-
-	return nil
-}
diff --git a/vendor/github.com/d5/tengo/script/script.go b/vendor/github.com/d5/tengo/script/script.go
deleted file mode 100644
index 2ee67b61..00000000
--- a/vendor/github.com/d5/tengo/script/script.go
+++ /dev/null
@@ -1,185 +0,0 @@
-package script
-
-import (
-	"context"
-	"fmt"
-
-	"github.com/d5/tengo/compiler"
-	"github.com/d5/tengo/compiler/parser"
-	"github.com/d5/tengo/compiler/source"
-	"github.com/d5/tengo/objects"
-	"github.com/d5/tengo/runtime"
-)
-
-// Script can simplify compilation and execution of embedded scripts.
-type Script struct {
-	variables        map[string]*Variable
-	modules          *objects.ModuleMap
-	input            []byte
-	maxAllocs        int64
-	maxConstObjects  int
-	enableFileImport bool
-}
-
-// New creates a Script instance with an input script.
-func New(input []byte) *Script {
-	return &Script{
-		variables:       make(map[string]*Variable),
-		input:           input,
-		maxAllocs:       -1,
-		maxConstObjects: -1,
-	}
-}
-
-// Add adds a new variable or updates an existing variable to the script.
-func (s *Script) Add(name string, value interface{}) error {
-	obj, err := objects.FromInterface(value)
-	if err != nil {
-		return err
-	}
-
-	s.variables[name] = &Variable{
-		name:  name,
-		value: obj,
-	}
-
-	return nil
-}
-
-// Remove removes (undefines) an existing variable for the script.
-// It returns false if the variable name is not defined.
-func (s *Script) Remove(name string) bool {
-	if _, ok := s.variables[name]; !ok {
-		return false
-	}
-
-	delete(s.variables, name)
-
-	return true
-}
-
-// SetImports sets import modules.
-func (s *Script) SetImports(modules *objects.ModuleMap) {
-	s.modules = modules
-}
-
-// SetMaxAllocs sets the maximum number of objects allocations during the run time.
-// Compiled script will return runtime.ErrObjectAllocLimit error if it exceeds this limit.
-func (s *Script) SetMaxAllocs(n int64) {
-	s.maxAllocs = n
-}
-
-// SetMaxConstObjects sets the maximum number of objects in the compiled constants.
-func (s *Script) SetMaxConstObjects(n int) {
-	s.maxConstObjects = n
-}
-
-// EnableFileImport enables or disables module loading from local files.
-// Local file modules are disabled by default.
-func (s *Script) EnableFileImport(enable bool) {
-	s.enableFileImport = enable
-}
-
-// Compile compiles the script with all the defined variables, and, returns Compiled object.
-func (s *Script) Compile() (*Compiled, error) {
-	symbolTable, globals, err := s.prepCompile()
-	if err != nil {
-		return nil, err
-	}
-
-	fileSet := source.NewFileSet()
-	srcFile := fileSet.AddFile("(main)", -1, len(s.input))
-
-	p := parser.NewParser(srcFile, s.input, nil)
-	file, err := p.ParseFile()
-	if err != nil {
-		return nil, err
-	}
-
-	c := compiler.NewCompiler(srcFile, symbolTable, nil, s.modules, nil)
-	c.EnableFileImport(s.enableFileImport)
-	if err := c.Compile(file); err != nil {
-		return nil, err
-	}
-
-	// reduce globals size
-	globals = globals[:symbolTable.MaxSymbols()+1]
-
-	// global symbol names to indexes
-	globalIndexes := make(map[string]int, len(globals))
-	for _, name := range symbolTable.Names() {
-		symbol, _, _ := symbolTable.Resolve(name)
-		if symbol.Scope == compiler.ScopeGlobal {
-			globalIndexes[name] = symbol.Index
-		}
-	}
-
-	// remove duplicates from constants
-	bytecode := c.Bytecode()
-	bytecode.RemoveDuplicates()
-
-	// check the constant objects limit
-	if s.maxConstObjects >= 0 {
-		cnt := bytecode.CountObjects()
-		if cnt > s.maxConstObjects {
-			return nil, fmt.Errorf("exceeding constant objects limit: %d", cnt)
-		}
-	}
-
-	return &Compiled{
-		globalIndexes: globalIndexes,
-		bytecode:      bytecode,
-		globals:       globals,
-		maxAllocs:     s.maxAllocs,
-	}, nil
-}
-
-// Run compiles and runs the scripts.
-// Use returned compiled object to access global variables.
-func (s *Script) Run() (compiled *Compiled, err error) {
-	compiled, err = s.Compile()
-	if err != nil {
-		return
-	}
-
-	err = compiled.Run()
-
-	return
-}
-
-// RunContext is like Run but includes a context.
-func (s *Script) RunContext(ctx context.Context) (compiled *Compiled, err error) {
-	compiled, err = s.Compile()
-	if err != nil {
-		return
-	}
-
-	err = compiled.RunContext(ctx)
-
-	return
-}
-
-func (s *Script) prepCompile() (symbolTable *compiler.SymbolTable, globals []objects.Object, err error) {
-	var names []string
-	for name := range s.variables {
-		names = append(names, name)
-	}
-
-	symbolTable = compiler.NewSymbolTable()
-	for idx, fn := range objects.Builtins {
-		symbolTable.DefineBuiltin(idx, fn.Name)
-	}
-
-	globals = make([]objects.Object, runtime.GlobalsSize)
-
-	for idx, name := range names {
-		symbol := symbolTable.Define(name)
-		if symbol.Index != idx {
-			panic(fmt.Errorf("wrong symbol index: %d != %d", idx, symbol.Index))
-		}
-
-		globals[symbol.Index] = s.variables[name].value
-	}
-
-	return
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/base64.go b/vendor/github.com/d5/tengo/stdlib/base64.go
deleted file mode 100644
index 40a746ce..00000000
--- a/vendor/github.com/d5/tengo/stdlib/base64.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package stdlib
-
-import (
-	"encoding/base64"
-	"github.com/d5/tengo/objects"
-)
-
-var base64Module = map[string]objects.Object{
-	"encode": &objects.UserFunction{Value: FuncAYRS(base64.StdEncoding.EncodeToString)},
-	"decode": &objects.UserFunction{Value: FuncASRYE(base64.StdEncoding.DecodeString)},
-
-	"raw_encode": &objects.UserFunction{Value: FuncAYRS(base64.RawStdEncoding.EncodeToString)},
-	"raw_decode": &objects.UserFunction{Value: FuncASRYE(base64.RawStdEncoding.DecodeString)},
-
-	"url_encode": &objects.UserFunction{Value: FuncAYRS(base64.URLEncoding.EncodeToString)},
-	"url_decode": &objects.UserFunction{Value: FuncASRYE(base64.URLEncoding.DecodeString)},
-
-	"raw_url_encode": &objects.UserFunction{Value: FuncAYRS(base64.RawURLEncoding.EncodeToString)},
-	"raw_url_decode": &objects.UserFunction{Value: FuncASRYE(base64.RawURLEncoding.DecodeString)},
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/builtin_modules.go b/vendor/github.com/d5/tengo/stdlib/builtin_modules.go
deleted file mode 100644
index 722461b2..00000000
--- a/vendor/github.com/d5/tengo/stdlib/builtin_modules.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package stdlib
-
-import "github.com/d5/tengo/objects"
-
-// BuiltinModules are builtin type standard library modules.
-var BuiltinModules = map[string]map[string]objects.Object{
-	"math":  mathModule,
-	"os":    osModule,
-	"text":  textModule,
-	"times": timesModule,
-	"rand":  randModule,
-	"fmt":   fmtModule,
-	"json":  jsonModule,
-	"base64": base64Module,
-	"hex":  hexModule,
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/errors.go b/vendor/github.com/d5/tengo/stdlib/errors.go
deleted file mode 100644
index a2942bb0..00000000
--- a/vendor/github.com/d5/tengo/stdlib/errors.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package stdlib
-
-import "github.com/d5/tengo/objects"
-
-func wrapError(err error) objects.Object {
-	if err == nil {
-		return objects.TrueValue
-	}
-
-	return &objects.Error{Value: &objects.String{Value: err.Error()}}
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/fmt.go b/vendor/github.com/d5/tengo/stdlib/fmt.go
deleted file mode 100644
index b8f64278..00000000
--- a/vendor/github.com/d5/tengo/stdlib/fmt.go
+++ /dev/null
@@ -1,110 +0,0 @@
-package stdlib
-
-import (
-	"fmt"
-
-	"github.com/d5/tengo"
-	"github.com/d5/tengo/objects"
-)
-
-var fmtModule = map[string]objects.Object{
-	"print":   &objects.UserFunction{Name: "print", Value: fmtPrint},
-	"printf":  &objects.UserFunction{Name: "printf", Value: fmtPrintf},
-	"println": &objects.UserFunction{Name: "println", Value: fmtPrintln},
-	"sprintf": &objects.UserFunction{Name: "sprintf", Value: fmtSprintf},
-}
-
-func fmtPrint(args ...objects.Object) (ret objects.Object, err error) {
-	printArgs, err := getPrintArgs(args...)
-	if err != nil {
-		return nil, err
-	}
-
-	_, _ = fmt.Print(printArgs...)
-
-	return nil, nil
-}
-
-func fmtPrintf(args ...objects.Object) (ret objects.Object, err error) {
-	numArgs := len(args)
-	if numArgs == 0 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	format, ok := args[0].(*objects.String)
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "format",
-			Expected: "string",
-			Found:    args[0].TypeName(),
-		}
-	}
-	if numArgs == 1 {
-		fmt.Print(format)
-		return nil, nil
-	}
-
-	s, err := objects.Format(format.Value, args[1:]...)
-	if err != nil {
-		return nil, err
-	}
-
-	fmt.Print(s)
-
-	return nil, nil
-}
-
-func fmtPrintln(args ...objects.Object) (ret objects.Object, err error) {
-	printArgs, err := getPrintArgs(args...)
-	if err != nil {
-		return nil, err
-	}
-
-	printArgs = append(printArgs, "\n")
-	_, _ = fmt.Print(printArgs...)
-
-	return nil, nil
-}
-
-func fmtSprintf(args ...objects.Object) (ret objects.Object, err error) {
-	numArgs := len(args)
-	if numArgs == 0 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	format, ok := args[0].(*objects.String)
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "format",
-			Expected: "string",
-			Found:    args[0].TypeName(),
-		}
-	}
-	if numArgs == 1 {
-		return format, nil // okay to return 'format' directly as String is immutable
-	}
-
-	s, err := objects.Format(format.Value, args[1:]...)
-	if err != nil {
-		return nil, err
-	}
-
-	return &objects.String{Value: s}, nil
-}
-
-func getPrintArgs(args ...objects.Object) ([]interface{}, error) {
-	var printArgs []interface{}
-	l := 0
-	for _, arg := range args {
-		s, _ := objects.ToString(arg)
-		slen := len(s)
-		if l+slen > tengo.MaxStringLen { // make sure length does not exceed the limit
-			return nil, objects.ErrStringLimit
-		}
-		l += slen
-
-		printArgs = append(printArgs, s)
-	}
-
-	return printArgs, nil
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/func_typedefs.go b/vendor/github.com/d5/tengo/stdlib/func_typedefs.go
deleted file mode 100644
index c7bd11fa..00000000
--- a/vendor/github.com/d5/tengo/stdlib/func_typedefs.go
+++ /dev/null
@@ -1,1178 +0,0 @@
-package stdlib
-
-import (
-	"fmt"
-
-	"github.com/d5/tengo"
-	"github.com/d5/tengo/objects"
-)
-
-// FuncAR transform a function of 'func()' signature
-// into CallableFunc type.
-func FuncAR(fn func()) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 0 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		fn()
-
-		return objects.UndefinedValue, nil
-	}
-}
-
-// FuncARI transform a function of 'func() int' signature
-// into CallableFunc type.
-func FuncARI(fn func() int) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 0 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		return &objects.Int{Value: int64(fn())}, nil
-	}
-}
-
-// FuncARI64 transform a function of 'func() int64' signature
-// into CallableFunc type.
-func FuncARI64(fn func() int64) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 0 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		return &objects.Int{Value: fn()}, nil
-	}
-}
-
-// FuncAI64RI64 transform a function of 'func(int64) int64' signature
-// into CallableFunc type.
-func FuncAI64RI64(fn func(int64) int64) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		i1, ok := objects.ToInt64(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "int(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		return &objects.Int{Value: fn(i1)}, nil
-	}
-}
-
-// FuncAI64R transform a function of 'func(int64)' signature
-// into CallableFunc type.
-func FuncAI64R(fn func(int64)) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		i1, ok := objects.ToInt64(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "int(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		fn(i1)
-
-		return objects.UndefinedValue, nil
-	}
-}
-
-// FuncARB transform a function of 'func() bool' signature
-// into CallableFunc type.
-func FuncARB(fn func() bool) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 0 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		if fn() {
-			return objects.TrueValue, nil
-		}
-
-		return objects.FalseValue, nil
-	}
-}
-
-// FuncARE transform a function of 'func() error' signature
-// into CallableFunc type.
-func FuncARE(fn func() error) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 0 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		return wrapError(fn()), nil
-	}
-}
-
-// FuncARS transform a function of 'func() string' signature
-// into CallableFunc type.
-func FuncARS(fn func() string) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 0 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s := fn()
-
-		if len(s) > tengo.MaxStringLen {
-			return nil, objects.ErrStringLimit
-		}
-
-		return &objects.String{Value: s}, nil
-	}
-}
-
-// FuncARSE transform a function of 'func() (string, error)' signature
-// into CallableFunc type.
-func FuncARSE(fn func() (string, error)) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 0 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		res, err := fn()
-		if err != nil {
-			return wrapError(err), nil
-		}
-
-		if len(res) > tengo.MaxStringLen {
-			return nil, objects.ErrStringLimit
-		}
-
-		return &objects.String{Value: res}, nil
-	}
-}
-
-// FuncARYE transform a function of 'func() ([]byte, error)' signature
-// into CallableFunc type.
-func FuncARYE(fn func() ([]byte, error)) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 0 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		res, err := fn()
-		if err != nil {
-			return wrapError(err), nil
-		}
-
-		if len(res) > tengo.MaxBytesLen {
-			return nil, objects.ErrBytesLimit
-		}
-
-		return &objects.Bytes{Value: res}, nil
-	}
-}
-
-// FuncARF transform a function of 'func() float64' signature
-// into CallableFunc type.
-func FuncARF(fn func() float64) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 0 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		return &objects.Float{Value: fn()}, nil
-	}
-}
-
-// FuncARSs transform a function of 'func() []string' signature
-// into CallableFunc type.
-func FuncARSs(fn func() []string) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 0 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		arr := &objects.Array{}
-		for _, elem := range fn() {
-			if len(elem) > tengo.MaxStringLen {
-				return nil, objects.ErrStringLimit
-			}
-
-			arr.Value = append(arr.Value, &objects.String{Value: elem})
-		}
-
-		return arr, nil
-	}
-}
-
-// FuncARIsE transform a function of 'func() ([]int, error)' signature
-// into CallableFunc type.
-func FuncARIsE(fn func() ([]int, error)) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 0 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		res, err := fn()
-		if err != nil {
-			return wrapError(err), nil
-		}
-
-		arr := &objects.Array{}
-		for _, v := range res {
-			arr.Value = append(arr.Value, &objects.Int{Value: int64(v)})
-		}
-
-		return arr, nil
-	}
-}
-
-// FuncAIRIs transform a function of 'func(int) []int' signature
-// into CallableFunc type.
-func FuncAIRIs(fn func(int) []int) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		i1, ok := objects.ToInt(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "int(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		res := fn(i1)
-
-		arr := &objects.Array{}
-		for _, v := range res {
-			arr.Value = append(arr.Value, &objects.Int{Value: int64(v)})
-		}
-
-		return arr, nil
-	}
-}
-
-// FuncAFRF transform a function of 'func(float64) float64' signature
-// into CallableFunc type.
-func FuncAFRF(fn func(float64) float64) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		f1, ok := objects.ToFloat64(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "float(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		return &objects.Float{Value: fn(f1)}, nil
-	}
-}
-
-// FuncAIR transform a function of 'func(int)' signature
-// into CallableFunc type.
-func FuncAIR(fn func(int)) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		i1, ok := objects.ToInt(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "int(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		fn(i1)
-
-		return objects.UndefinedValue, nil
-	}
-}
-
-// FuncAIRF transform a function of 'func(int) float64' signature
-// into CallableFunc type.
-func FuncAIRF(fn func(int) float64) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		i1, ok := objects.ToInt(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "int(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		return &objects.Float{Value: fn(i1)}, nil
-	}
-}
-
-// FuncAFRI transform a function of 'func(float64) int' signature
-// into CallableFunc type.
-func FuncAFRI(fn func(float64) int) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		f1, ok := objects.ToFloat64(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "float(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		return &objects.Int{Value: int64(fn(f1))}, nil
-	}
-}
-
-// FuncAFFRF transform a function of 'func(float64, float64) float64' signature
-// into CallableFunc type.
-func FuncAFFRF(fn func(float64, float64) float64) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 2 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		f1, ok := objects.ToFloat64(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "float(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		f2, ok := objects.ToFloat64(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "second",
-				Expected: "float(compatible)",
-				Found:    args[1].TypeName(),
-			}
-		}
-
-		return &objects.Float{Value: fn(f1, f2)}, nil
-	}
-}
-
-// FuncAIFRF transform a function of 'func(int, float64) float64' signature
-// into CallableFunc type.
-func FuncAIFRF(fn func(int, float64) float64) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 2 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		i1, ok := objects.ToInt(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "int(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		f2, ok := objects.ToFloat64(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "second",
-				Expected: "float(compatible)",
-				Found:    args[1].TypeName(),
-			}
-		}
-
-		return &objects.Float{Value: fn(i1, f2)}, nil
-	}
-}
-
-// FuncAFIRF transform a function of 'func(float64, int) float64' signature
-// into CallableFunc type.
-func FuncAFIRF(fn func(float64, int) float64) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 2 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		f1, ok := objects.ToFloat64(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "float(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		i2, ok := objects.ToInt(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "second",
-				Expected: "int(compatible)",
-				Found:    args[1].TypeName(),
-			}
-		}
-
-		return &objects.Float{Value: fn(f1, i2)}, nil
-	}
-}
-
-// FuncAFIRB transform a function of 'func(float64, int) bool' signature
-// into CallableFunc type.
-func FuncAFIRB(fn func(float64, int) bool) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 2 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		f1, ok := objects.ToFloat64(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "float(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		i2, ok := objects.ToInt(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "second",
-				Expected: "int(compatible)",
-				Found:    args[1].TypeName(),
-			}
-		}
-
-		if fn(f1, i2) {
-			return objects.TrueValue, nil
-		}
-
-		return objects.FalseValue, nil
-	}
-}
-
-// FuncAFRB transform a function of 'func(float64) bool' signature
-// into CallableFunc type.
-func FuncAFRB(fn func(float64) bool) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		f1, ok := objects.ToFloat64(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "float(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		if fn(f1) {
-			return objects.TrueValue, nil
-		}
-
-		return objects.FalseValue, nil
-	}
-}
-
-// FuncASRS transform a function of 'func(string) string' signature into CallableFunc type.
-// User function will return 'true' if underlying native function returns nil.
-func FuncASRS(fn func(string) string) objects.CallableFunc {
-	return func(args ...objects.Object) (objects.Object, error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		s := fn(s1)
-
-		if len(s) > tengo.MaxStringLen {
-			return nil, objects.ErrStringLimit
-		}
-
-		return &objects.String{Value: s}, nil
-	}
-}
-
-// FuncASRSs transform a function of 'func(string) []string' signature into CallableFunc type.
-func FuncASRSs(fn func(string) []string) objects.CallableFunc {
-	return func(args ...objects.Object) (objects.Object, error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		res := fn(s1)
-
-		arr := &objects.Array{}
-		for _, elem := range res {
-			if len(elem) > tengo.MaxStringLen {
-				return nil, objects.ErrStringLimit
-			}
-
-			arr.Value = append(arr.Value, &objects.String{Value: elem})
-		}
-
-		return arr, nil
-	}
-}
-
-// FuncASRSE transform a function of 'func(string) (string, error)' signature into CallableFunc type.
-// User function will return 'true' if underlying native function returns nil.
-func FuncASRSE(fn func(string) (string, error)) objects.CallableFunc {
-	return func(args ...objects.Object) (objects.Object, error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		res, err := fn(s1)
-		if err != nil {
-			return wrapError(err), nil
-		}
-
-		if len(res) > tengo.MaxStringLen {
-			return nil, objects.ErrStringLimit
-		}
-
-		return &objects.String{Value: res}, nil
-	}
-}
-
-// FuncASRE transform a function of 'func(string) error' signature into CallableFunc type.
-// User function will return 'true' if underlying native function returns nil.
-func FuncASRE(fn func(string) error) objects.CallableFunc {
-	return func(args ...objects.Object) (objects.Object, error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		return wrapError(fn(s1)), nil
-	}
-}
-
-// FuncASSRE transform a function of 'func(string, string) error' signature into CallableFunc type.
-// User function will return 'true' if underlying native function returns nil.
-func FuncASSRE(fn func(string, string) error) objects.CallableFunc {
-	return func(args ...objects.Object) (objects.Object, error) {
-		if len(args) != 2 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		s2, ok := objects.ToString(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "second",
-				Expected: "string(compatible)",
-				Found:    args[1].TypeName(),
-			}
-		}
-
-		return wrapError(fn(s1, s2)), nil
-	}
-}
-
-// FuncASSRSs transform a function of 'func(string, string) []string' signature into CallableFunc type.
-func FuncASSRSs(fn func(string, string) []string) objects.CallableFunc {
-	return func(args ...objects.Object) (objects.Object, error) {
-		if len(args) != 2 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		s2, ok := objects.ToString(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[1].TypeName(),
-			}
-		}
-
-		arr := &objects.Array{}
-		for _, res := range fn(s1, s2) {
-			if len(res) > tengo.MaxStringLen {
-				return nil, objects.ErrStringLimit
-			}
-
-			arr.Value = append(arr.Value, &objects.String{Value: res})
-		}
-
-		return arr, nil
-	}
-}
-
-// FuncASSIRSs transform a function of 'func(string, string, int) []string' signature into CallableFunc type.
-func FuncASSIRSs(fn func(string, string, int) []string) objects.CallableFunc {
-	return func(args ...objects.Object) (objects.Object, error) {
-		if len(args) != 3 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		s2, ok := objects.ToString(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "second",
-				Expected: "string(compatible)",
-				Found:    args[1].TypeName(),
-			}
-		}
-
-		i3, ok := objects.ToInt(args[2])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "third",
-				Expected: "int(compatible)",
-				Found:    args[2].TypeName(),
-			}
-		}
-
-		arr := &objects.Array{}
-		for _, res := range fn(s1, s2, i3) {
-			if len(res) > tengo.MaxStringLen {
-				return nil, objects.ErrStringLimit
-			}
-
-			arr.Value = append(arr.Value, &objects.String{Value: res})
-		}
-
-		return arr, nil
-	}
-}
-
-// FuncASSRI transform a function of 'func(string, string) int' signature into CallableFunc type.
-func FuncASSRI(fn func(string, string) int) objects.CallableFunc {
-	return func(args ...objects.Object) (objects.Object, error) {
-		if len(args) != 2 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		s2, ok := objects.ToString(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "second",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		return &objects.Int{Value: int64(fn(s1, s2))}, nil
-	}
-}
-
-// FuncASSRS transform a function of 'func(string, string) string' signature into CallableFunc type.
-func FuncASSRS(fn func(string, string) string) objects.CallableFunc {
-	return func(args ...objects.Object) (objects.Object, error) {
-		if len(args) != 2 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		s2, ok := objects.ToString(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "second",
-				Expected: "string(compatible)",
-				Found:    args[1].TypeName(),
-			}
-		}
-
-		s := fn(s1, s2)
-
-		if len(s) > tengo.MaxStringLen {
-			return nil, objects.ErrStringLimit
-		}
-
-		return &objects.String{Value: s}, nil
-	}
-}
-
-// FuncASSRB transform a function of 'func(string, string) bool' signature into CallableFunc type.
-func FuncASSRB(fn func(string, string) bool) objects.CallableFunc {
-	return func(args ...objects.Object) (objects.Object, error) {
-		if len(args) != 2 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		s2, ok := objects.ToString(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "second",
-				Expected: "string(compatible)",
-				Found:    args[1].TypeName(),
-			}
-		}
-
-		if fn(s1, s2) {
-			return objects.TrueValue, nil
-		}
-
-		return objects.FalseValue, nil
-	}
-}
-
-// FuncASsSRS transform a function of 'func([]string, string) string' signature into CallableFunc type.
-func FuncASsSRS(fn func([]string, string) string) objects.CallableFunc {
-	return func(args ...objects.Object) (objects.Object, error) {
-		if len(args) != 2 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		var ss1 []string
-		switch arg0 := args[0].(type) {
-		case *objects.Array:
-			for idx, a := range arg0.Value {
-				as, ok := objects.ToString(a)
-				if !ok {
-					return nil, objects.ErrInvalidArgumentType{
-						Name:     fmt.Sprintf("first[%d]", idx),
-						Expected: "string(compatible)",
-						Found:    a.TypeName(),
-					}
-				}
-				ss1 = append(ss1, as)
-			}
-		case *objects.ImmutableArray:
-			for idx, a := range arg0.Value {
-				as, ok := objects.ToString(a)
-				if !ok {
-					return nil, objects.ErrInvalidArgumentType{
-						Name:     fmt.Sprintf("first[%d]", idx),
-						Expected: "string(compatible)",
-						Found:    a.TypeName(),
-					}
-				}
-				ss1 = append(ss1, as)
-			}
-		default:
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "array",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		s2, ok := objects.ToString(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "second",
-				Expected: "string(compatible)",
-				Found:    args[1].TypeName(),
-			}
-		}
-
-		s := fn(ss1, s2)
-		if len(s) > tengo.MaxStringLen {
-			return nil, objects.ErrStringLimit
-		}
-
-		return &objects.String{Value: s}, nil
-	}
-}
-
-// FuncASI64RE transform a function of 'func(string, int64) error' signature
-// into CallableFunc type.
-func FuncASI64RE(fn func(string, int64) error) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 2 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		i2, ok := objects.ToInt64(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "second",
-				Expected: "int(compatible)",
-				Found:    args[1].TypeName(),
-			}
-		}
-
-		return wrapError(fn(s1, i2)), nil
-	}
-}
-
-// FuncAIIRE transform a function of 'func(int, int) error' signature
-// into CallableFunc type.
-func FuncAIIRE(fn func(int, int) error) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 2 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		i1, ok := objects.ToInt(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "int(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		i2, ok := objects.ToInt(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "second",
-				Expected: "int(compatible)",
-				Found:    args[1].TypeName(),
-			}
-		}
-
-		return wrapError(fn(i1, i2)), nil
-	}
-}
-
-// FuncASIRS transform a function of 'func(string, int) string' signature
-// into CallableFunc type.
-func FuncASIRS(fn func(string, int) string) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 2 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		i2, ok := objects.ToInt(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "second",
-				Expected: "int(compatible)",
-				Found:    args[1].TypeName(),
-			}
-		}
-
-		s := fn(s1, i2)
-
-		if len(s) > tengo.MaxStringLen {
-			return nil, objects.ErrStringLimit
-		}
-
-		return &objects.String{Value: s}, nil
-	}
-}
-
-// FuncASIIRE transform a function of 'func(string, int, int) error' signature
-// into CallableFunc type.
-func FuncASIIRE(fn func(string, int, int) error) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 3 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		i2, ok := objects.ToInt(args[1])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "second",
-				Expected: "int(compatible)",
-				Found:    args[1].TypeName(),
-			}
-		}
-
-		i3, ok := objects.ToInt(args[2])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "third",
-				Expected: "int(compatible)",
-				Found:    args[2].TypeName(),
-			}
-		}
-
-		return wrapError(fn(s1, i2, i3)), nil
-	}
-}
-
-// FuncAYRIE transform a function of 'func([]byte) (int, error)' signature
-// into CallableFunc type.
-func FuncAYRIE(fn func([]byte) (int, error)) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		y1, ok := objects.ToByteSlice(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "bytes(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		res, err := fn(y1)
-		if err != nil {
-			return wrapError(err), nil
-		}
-
-		return &objects.Int{Value: int64(res)}, nil
-	}
-}
-
-// FuncAYRS transform a function of 'func([]byte) string' signature
-// into CallableFunc type.
-func FuncAYRS(fn func([]byte) string) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		y1, ok := objects.ToByteSlice(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "bytes(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		res := fn(y1)
-
-		return &objects.String{Value: res}, nil
-	}
-}
-
-// FuncASRIE transform a function of 'func(string) (int, error)' signature
-// into CallableFunc type.
-func FuncASRIE(fn func(string) (int, error)) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		res, err := fn(s1)
-		if err != nil {
-			return wrapError(err), nil
-		}
-
-		return &objects.Int{Value: int64(res)}, nil
-	}
-}
-
-// FuncASRYE transform a function of 'func(string) ([]byte, error)' signature
-// into CallableFunc type.
-func FuncASRYE(fn func(string) ([]byte, error)) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		s1, ok := objects.ToString(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "string(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		res, err := fn(s1)
-		if err != nil {
-			return wrapError(err), nil
-		}
-
-		if len(res) > tengo.MaxBytesLen {
-			return nil, objects.ErrBytesLimit
-		}
-
-		return &objects.Bytes{Value: res}, nil
-	}
-}
-
-// FuncAIRSsE transform a function of 'func(int) ([]string, error)' signature
-// into CallableFunc type.
-func FuncAIRSsE(fn func(int) ([]string, error)) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		i1, ok := objects.ToInt(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "int(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		res, err := fn(i1)
-		if err != nil {
-			return wrapError(err), nil
-		}
-
-		arr := &objects.Array{}
-		for _, r := range res {
-			if len(r) > tengo.MaxStringLen {
-				return nil, objects.ErrStringLimit
-			}
-
-			arr.Value = append(arr.Value, &objects.String{Value: r})
-		}
-
-		return arr, nil
-	}
-}
-
-// FuncAIRS transform a function of 'func(int) string' signature
-// into CallableFunc type.
-func FuncAIRS(fn func(int) string) objects.CallableFunc {
-	return func(args ...objects.Object) (ret objects.Object, err error) {
-		if len(args) != 1 {
-			return nil, objects.ErrWrongNumArguments
-		}
-
-		i1, ok := objects.ToInt(args[0])
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     "first",
-				Expected: "int(compatible)",
-				Found:    args[0].TypeName(),
-			}
-		}
-
-		s := fn(i1)
-
-		if len(s) > tengo.MaxStringLen {
-			return nil, objects.ErrStringLimit
-		}
-
-		return &objects.String{Value: s}, nil
-	}
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/hex.go b/vendor/github.com/d5/tengo/stdlib/hex.go
deleted file mode 100644
index acc29e6a..00000000
--- a/vendor/github.com/d5/tengo/stdlib/hex.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package stdlib
-
-import (
-	"encoding/hex"
-	"github.com/d5/tengo/objects"
-)
-
-var hexModule = map[string]objects.Object{
-	"encode": &objects.UserFunction{Value: FuncAYRS(hex.EncodeToString)},
-	"decode": &objects.UserFunction{Value: FuncASRYE(hex.DecodeString)},
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/json.go b/vendor/github.com/d5/tengo/stdlib/json.go
deleted file mode 100644
index f913dc48..00000000
--- a/vendor/github.com/d5/tengo/stdlib/json.go
+++ /dev/null
@@ -1,126 +0,0 @@
-package stdlib
-
-import (
-	"bytes"
-	gojson "encoding/json"
-
-	"github.com/d5/tengo/objects"
-	"github.com/d5/tengo/stdlib/json"
-)
-
-var jsonModule = map[string]objects.Object{
-	"decode":      &objects.UserFunction{Name: "decode", Value: jsonDecode},
-	"encode":      &objects.UserFunction{Name: "encode", Value: jsonEncode},
-	"indent":      &objects.UserFunction{Name: "encode", Value: jsonIndent},
-	"html_escape": &objects.UserFunction{Name: "html_escape", Value: jsonHTMLEscape},
-}
-
-func jsonDecode(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	switch o := args[0].(type) {
-	case *objects.Bytes:
-		v, err := json.Decode(o.Value)
-		if err != nil {
-			return &objects.Error{Value: &objects.String{Value: err.Error()}}, nil
-		}
-		return v, nil
-	case *objects.String:
-		v, err := json.Decode([]byte(o.Value))
-		if err != nil {
-			return &objects.Error{Value: &objects.String{Value: err.Error()}}, nil
-		}
-		return v, nil
-	default:
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "bytes/string",
-			Found:    args[0].TypeName(),
-		}
-	}
-}
-
-func jsonEncode(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	b, err := json.Encode(args[0])
-	if err != nil {
-		return &objects.Error{Value: &objects.String{Value: err.Error()}}, nil
-	}
-
-	return &objects.Bytes{Value: b}, nil
-}
-
-func jsonIndent(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 3 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	prefix, ok := objects.ToString(args[1])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "prefix",
-			Expected: "string(compatible)",
-			Found:    args[1].TypeName(),
-		}
-	}
-
-	indent, ok := objects.ToString(args[2])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "indent",
-			Expected: "string(compatible)",
-			Found:    args[2].TypeName(),
-		}
-	}
-
-	switch o := args[0].(type) {
-	case *objects.Bytes:
-		var dst bytes.Buffer
-		err := gojson.Indent(&dst, o.Value, prefix, indent)
-		if err != nil {
-			return &objects.Error{Value: &objects.String{Value: err.Error()}}, nil
-		}
-		return &objects.Bytes{Value: dst.Bytes()}, nil
-	case *objects.String:
-		var dst bytes.Buffer
-		err := gojson.Indent(&dst, []byte(o.Value), prefix, indent)
-		if err != nil {
-			return &objects.Error{Value: &objects.String{Value: err.Error()}}, nil
-		}
-		return &objects.Bytes{Value: dst.Bytes()}, nil
-	default:
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "bytes/string",
-			Found:    args[0].TypeName(),
-		}
-	}
-}
-
-func jsonHTMLEscape(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	switch o := args[0].(type) {
-	case *objects.Bytes:
-		var dst bytes.Buffer
-		gojson.HTMLEscape(&dst, o.Value)
-		return &objects.Bytes{Value: dst.Bytes()}, nil
-	case *objects.String:
-		var dst bytes.Buffer
-		gojson.HTMLEscape(&dst, []byte(o.Value))
-		return &objects.Bytes{Value: dst.Bytes()}, nil
-	default:
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "bytes/string",
-			Found:    args[0].TypeName(),
-		}
-	}
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/math.go b/vendor/github.com/d5/tengo/stdlib/math.go
deleted file mode 100644
index 08d82bdf..00000000
--- a/vendor/github.com/d5/tengo/stdlib/math.go
+++ /dev/null
@@ -1,74 +0,0 @@
-package stdlib
-
-import (
-	"math"
-
-	"github.com/d5/tengo/objects"
-)
-
-var mathModule = map[string]objects.Object{
-	"e":         &objects.Float{Value: math.E},
-	"pi":        &objects.Float{Value: math.Pi},
-	"phi":       &objects.Float{Value: math.Phi},
-	"sqrt2":     &objects.Float{Value: math.Sqrt2},
-	"sqrtE":     &objects.Float{Value: math.SqrtE},
-	"sqrtPi":    &objects.Float{Value: math.SqrtPi},
-	"sqrtPhi":   &objects.Float{Value: math.SqrtPhi},
-	"ln2":       &objects.Float{Value: math.Ln2},
-	"log2E":     &objects.Float{Value: math.Log2E},
-	"ln10":      &objects.Float{Value: math.Ln10},
-	"log10E":    &objects.Float{Value: math.Log10E},
-	"abs":       &objects.UserFunction{Name: "abs", Value: FuncAFRF(math.Abs)},
-	"acos":      &objects.UserFunction{Name: "acos", Value: FuncAFRF(math.Acos)},
-	"acosh":     &objects.UserFunction{Name: "acosh", Value: FuncAFRF(math.Acosh)},
-	"asin":      &objects.UserFunction{Name: "asin", Value: FuncAFRF(math.Asin)},
-	"asinh":     &objects.UserFunction{Name: "asinh", Value: FuncAFRF(math.Asinh)},
-	"atan":      &objects.UserFunction{Name: "atan", Value: FuncAFRF(math.Atan)},
-	"atan2":     &objects.UserFunction{Name: "atan2", Value: FuncAFFRF(math.Atan2)},
-	"atanh":     &objects.UserFunction{Name: "atanh", Value: FuncAFRF(math.Atanh)},
-	"cbrt":      &objects.UserFunction{Name: "cbrt", Value: FuncAFRF(math.Cbrt)},
-	"ceil":      &objects.UserFunction{Name: "ceil", Value: FuncAFRF(math.Ceil)},
-	"copysign":  &objects.UserFunction{Name: "copysign", Value: FuncAFFRF(math.Copysign)},
-	"cos":       &objects.UserFunction{Name: "cos", Value: FuncAFRF(math.Cos)},
-	"cosh":      &objects.UserFunction{Name: "cosh", Value: FuncAFRF(math.Cosh)},
-	"dim":       &objects.UserFunction{Name: "dim", Value: FuncAFFRF(math.Dim)},
-	"erf":       &objects.UserFunction{Name: "erf", Value: FuncAFRF(math.Erf)},
-	"erfc":      &objects.UserFunction{Name: "erfc", Value: FuncAFRF(math.Erfc)},
-	"exp":       &objects.UserFunction{Name: "exp", Value: FuncAFRF(math.Exp)},
-	"exp2":      &objects.UserFunction{Name: "exp2", Value: FuncAFRF(math.Exp2)},
-	"expm1":     &objects.UserFunction{Name: "expm1", Value: FuncAFRF(math.Expm1)},
-	"floor":     &objects.UserFunction{Name: "floor", Value: FuncAFRF(math.Floor)},
-	"gamma":     &objects.UserFunction{Name: "gamma", Value: FuncAFRF(math.Gamma)},
-	"hypot":     &objects.UserFunction{Name: "hypot", Value: FuncAFFRF(math.Hypot)},
-	"ilogb":     &objects.UserFunction{Name: "ilogb", Value: FuncAFRI(math.Ilogb)},
-	"inf":       &objects.UserFunction{Name: "inf", Value: FuncAIRF(math.Inf)},
-	"is_inf":    &objects.UserFunction{Name: "is_inf", Value: FuncAFIRB(math.IsInf)},
-	"is_nan":    &objects.UserFunction{Name: "is_nan", Value: FuncAFRB(math.IsNaN)},
-	"j0":        &objects.UserFunction{Name: "j0", Value: FuncAFRF(math.J0)},
-	"j1":        &objects.UserFunction{Name: "j1", Value: FuncAFRF(math.J1)},
-	"jn":        &objects.UserFunction{Name: "jn", Value: FuncAIFRF(math.Jn)},
-	"ldexp":     &objects.UserFunction{Name: "ldexp", Value: FuncAFIRF(math.Ldexp)},
-	"log":       &objects.UserFunction{Name: "log", Value: FuncAFRF(math.Log)},
-	"log10":     &objects.UserFunction{Name: "log10", Value: FuncAFRF(math.Log10)},
-	"log1p":     &objects.UserFunction{Name: "log1p", Value: FuncAFRF(math.Log1p)},
-	"log2":      &objects.UserFunction{Name: "log2", Value: FuncAFRF(math.Log2)},
-	"logb":      &objects.UserFunction{Name: "logb", Value: FuncAFRF(math.Logb)},
-	"max":       &objects.UserFunction{Name: "max", Value: FuncAFFRF(math.Max)},
-	"min":       &objects.UserFunction{Name: "min", Value: FuncAFFRF(math.Min)},
-	"mod":       &objects.UserFunction{Name: "mod", Value: FuncAFFRF(math.Mod)},
-	"nan":       &objects.UserFunction{Name: "nan", Value: FuncARF(math.NaN)},
-	"nextafter": &objects.UserFunction{Name: "nextafter", Value: FuncAFFRF(math.Nextafter)},
-	"pow":       &objects.UserFunction{Name: "pow", Value: FuncAFFRF(math.Pow)},
-	"pow10":     &objects.UserFunction{Name: "pow10", Value: FuncAIRF(math.Pow10)},
-	"remainder": &objects.UserFunction{Name: "remainder", Value: FuncAFFRF(math.Remainder)},
-	"signbit":   &objects.UserFunction{Name: "signbit", Value: FuncAFRB(math.Signbit)},
-	"sin":       &objects.UserFunction{Name: "sin", Value: FuncAFRF(math.Sin)},
-	"sinh":      &objects.UserFunction{Name: "sinh", Value: FuncAFRF(math.Sinh)},
-	"sqrt":      &objects.UserFunction{Name: "sqrt", Value: FuncAFRF(math.Sqrt)},
-	"tan":       &objects.UserFunction{Name: "tan", Value: FuncAFRF(math.Tan)},
-	"tanh":      &objects.UserFunction{Name: "tanh", Value: FuncAFRF(math.Tanh)},
-	"trunc":     &objects.UserFunction{Name: "trunc", Value: FuncAFRF(math.Trunc)},
-	"y0":        &objects.UserFunction{Name: "y0", Value: FuncAFRF(math.Y0)},
-	"y1":        &objects.UserFunction{Name: "y1", Value: FuncAFRF(math.Y1)},
-	"yn":        &objects.UserFunction{Name: "yn", Value: FuncAIFRF(math.Yn)},
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/os.go b/vendor/github.com/d5/tengo/stdlib/os.go
deleted file mode 100644
index a7890cc1..00000000
--- a/vendor/github.com/d5/tengo/stdlib/os.go
+++ /dev/null
@@ -1,492 +0,0 @@
-package stdlib
-
-import (
-	"fmt"
-	"io"
-	"io/ioutil"
-	"os"
-	"os/exec"
-
-	"github.com/d5/tengo"
-	"github.com/d5/tengo/objects"
-)
-
-var osModule = map[string]objects.Object{
-	"o_rdonly":            &objects.Int{Value: int64(os.O_RDONLY)},
-	"o_wronly":            &objects.Int{Value: int64(os.O_WRONLY)},
-	"o_rdwr":              &objects.Int{Value: int64(os.O_RDWR)},
-	"o_append":            &objects.Int{Value: int64(os.O_APPEND)},
-	"o_create":            &objects.Int{Value: int64(os.O_CREATE)},
-	"o_excl":              &objects.Int{Value: int64(os.O_EXCL)},
-	"o_sync":              &objects.Int{Value: int64(os.O_SYNC)},
-	"o_trunc":             &objects.Int{Value: int64(os.O_TRUNC)},
-	"mode_dir":            &objects.Int{Value: int64(os.ModeDir)},
-	"mode_append":         &objects.Int{Value: int64(os.ModeAppend)},
-	"mode_exclusive":      &objects.Int{Value: int64(os.ModeExclusive)},
-	"mode_temporary":      &objects.Int{Value: int64(os.ModeTemporary)},
-	"mode_symlink":        &objects.Int{Value: int64(os.ModeSymlink)},
-	"mode_device":         &objects.Int{Value: int64(os.ModeDevice)},
-	"mode_named_pipe":     &objects.Int{Value: int64(os.ModeNamedPipe)},
-	"mode_socket":         &objects.Int{Value: int64(os.ModeSocket)},
-	"mode_setuid":         &objects.Int{Value: int64(os.ModeSetuid)},
-	"mode_setgui":         &objects.Int{Value: int64(os.ModeSetgid)},
-	"mode_char_device":    &objects.Int{Value: int64(os.ModeCharDevice)},
-	"mode_sticky":         &objects.Int{Value: int64(os.ModeSticky)},
-	"mode_type":           &objects.Int{Value: int64(os.ModeType)},
-	"mode_perm":           &objects.Int{Value: int64(os.ModePerm)},
-	"path_separator":      &objects.Char{Value: os.PathSeparator},
-	"path_list_separator": &objects.Char{Value: os.PathListSeparator},
-	"dev_null":            &objects.String{Value: os.DevNull},
-	"seek_set":            &objects.Int{Value: int64(io.SeekStart)},
-	"seek_cur":            &objects.Int{Value: int64(io.SeekCurrent)},
-	"seek_end":            &objects.Int{Value: int64(io.SeekEnd)},
-	"args":                &objects.UserFunction{Name: "args", Value: osArgs},                             // args() => array(string)
-	"chdir":               &objects.UserFunction{Name: "chdir", Value: FuncASRE(os.Chdir)},                // chdir(dir string) => error
-	"chmod":               osFuncASFmRE("chmod", os.Chmod),                                                // chmod(name string, mode int) => error
-	"chown":               &objects.UserFunction{Name: "chown", Value: FuncASIIRE(os.Chown)},              // chown(name string, uid int, gid int) => error
-	"clearenv":            &objects.UserFunction{Name: "clearenv", Value: FuncAR(os.Clearenv)},            // clearenv()
-	"environ":             &objects.UserFunction{Name: "environ", Value: FuncARSs(os.Environ)},            // environ() => array(string)
-	"exit":                &objects.UserFunction{Name: "exit", Value: FuncAIR(os.Exit)},                   // exit(code int)
-	"expand_env":          &objects.UserFunction{Name: "expand_env", Value: osExpandEnv},                  // expand_env(s string) => string
-	"getegid":             &objects.UserFunction{Name: "getegid", Value: FuncARI(os.Getegid)},             // getegid() => int
-	"getenv":              &objects.UserFunction{Name: "getenv", Value: FuncASRS(os.Getenv)},              // getenv(s string) => string
-	"geteuid":             &objects.UserFunction{Name: "geteuid", Value: FuncARI(os.Geteuid)},             // geteuid() => int
-	"getgid":              &objects.UserFunction{Name: "getgid", Value: FuncARI(os.Getgid)},               // getgid() => int
-	"getgroups":           &objects.UserFunction{Name: "getgroups", Value: FuncARIsE(os.Getgroups)},       // getgroups() => array(string)/error
-	"getpagesize":         &objects.UserFunction{Name: "getpagesize", Value: FuncARI(os.Getpagesize)},     // getpagesize() => int
-	"getpid":              &objects.UserFunction{Name: "getpid", Value: FuncARI(os.Getpid)},               // getpid() => int
-	"getppid":             &objects.UserFunction{Name: "getppid", Value: FuncARI(os.Getppid)},             // getppid() => int
-	"getuid":              &objects.UserFunction{Name: "getuid", Value: FuncARI(os.Getuid)},               // getuid() => int
-	"getwd":               &objects.UserFunction{Name: "getwd", Value: FuncARSE(os.Getwd)},                // getwd() => string/error
-	"hostname":            &objects.UserFunction{Name: "hostname", Value: FuncARSE(os.Hostname)},          // hostname() => string/error
-	"lchown":              &objects.UserFunction{Name: "lchown", Value: FuncASIIRE(os.Lchown)},            // lchown(name string, uid int, gid int) => error
-	"link":                &objects.UserFunction{Name: "link", Value: FuncASSRE(os.Link)},                 // link(oldname string, newname string) => error
-	"lookup_env":          &objects.UserFunction{Name: "lookup_env", Value: osLookupEnv},                  // lookup_env(key string) => string/false
-	"mkdir":               osFuncASFmRE("mkdir", os.Mkdir),                                                // mkdir(name string, perm int) => error
-	"mkdir_all":           osFuncASFmRE("mkdir_all", os.MkdirAll),                                         // mkdir_all(name string, perm int) => error
-	"readlink":            &objects.UserFunction{Name: "readlink", Value: FuncASRSE(os.Readlink)},         // readlink(name string) => string/error
-	"remove":              &objects.UserFunction{Name: "remove", Value: FuncASRE(os.Remove)},              // remove(name string) => error
-	"remove_all":          &objects.UserFunction{Name: "remove_all", Value: FuncASRE(os.RemoveAll)},       // remove_all(name string) => error
-	"rename":              &objects.UserFunction{Name: "rename", Value: FuncASSRE(os.Rename)},             // rename(oldpath string, newpath string) => error
-	"setenv":              &objects.UserFunction{Name: "setenv", Value: FuncASSRE(os.Setenv)},             // setenv(key string, value string) => error
-	"symlink":             &objects.UserFunction{Name: "symlink", Value: FuncASSRE(os.Symlink)},           // symlink(oldname string newname string) => error
-	"temp_dir":            &objects.UserFunction{Name: "temp_dir", Value: FuncARS(os.TempDir)},            // temp_dir() => string
-	"truncate":            &objects.UserFunction{Name: "truncate", Value: FuncASI64RE(os.Truncate)},       // truncate(name string, size int) => error
-	"unsetenv":            &objects.UserFunction{Name: "unsetenv", Value: FuncASRE(os.Unsetenv)},          // unsetenv(key string) => error
-	"create":              &objects.UserFunction{Name: "create", Value: osCreate},                         // create(name string) => imap(file)/error
-	"open":                &objects.UserFunction{Name: "open", Value: osOpen},                             // open(name string) => imap(file)/error
-	"open_file":           &objects.UserFunction{Name: "open_file", Value: osOpenFile},                    // open_file(name string, flag int, perm int) => imap(file)/error
-	"find_process":        &objects.UserFunction{Name: "find_process", Value: osFindProcess},              // find_process(pid int) => imap(process)/error
-	"start_process":       &objects.UserFunction{Name: "start_process", Value: osStartProcess},            // start_process(name string, argv array(string), dir string, env array(string)) => imap(process)/error
-	"exec_look_path":      &objects.UserFunction{Name: "exec_look_path", Value: FuncASRSE(exec.LookPath)}, // exec_look_path(file) => string/error
-	"exec":                &objects.UserFunction{Name: "exec", Value: osExec},                             // exec(name, args...) => command
-	"stat":                &objects.UserFunction{Name: "stat", Value: osStat},                             // stat(name) => imap(fileinfo)/error
-	"read_file":           &objects.UserFunction{Name: "read_file", Value: osReadFile},                    // readfile(name) => array(byte)/error
-}
-
-func osReadFile(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	fname, ok := objects.ToString(args[0])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-	}
-
-	bytes, err := ioutil.ReadFile(fname)
-	if err != nil {
-		return wrapError(err), nil
-	}
-
-	if len(bytes) > tengo.MaxBytesLen {
-		return nil, objects.ErrBytesLimit
-	}
-
-	return &objects.Bytes{Value: bytes}, nil
-}
-
-func osStat(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	fname, ok := objects.ToString(args[0])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-	}
-
-	stat, err := os.Stat(fname)
-	if err != nil {
-		return wrapError(err), nil
-	}
-
-	fstat := &objects.ImmutableMap{
-		Value: map[string]objects.Object{
-			"name":  &objects.String{Value: stat.Name()},
-			"mtime": &objects.Time{Value: stat.ModTime()},
-			"size":  &objects.Int{Value: stat.Size()},
-			"mode":  &objects.Int{Value: int64(stat.Mode())},
-		},
-	}
-
-	if stat.IsDir() {
-		fstat.Value["directory"] = objects.TrueValue
-	} else {
-		fstat.Value["directory"] = objects.FalseValue
-	}
-
-	return fstat, nil
-}
-
-func osCreate(args ...objects.Object) (objects.Object, error) {
-	if len(args) != 1 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-	}
-
-	res, err := os.Create(s1)
-	if err != nil {
-		return wrapError(err), nil
-	}
-
-	return makeOSFile(res), nil
-}
-
-func osOpen(args ...objects.Object) (objects.Object, error) {
-	if len(args) != 1 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-	}
-
-	res, err := os.Open(s1)
-	if err != nil {
-		return wrapError(err), nil
-	}
-
-	return makeOSFile(res), nil
-}
-
-func osOpenFile(args ...objects.Object) (objects.Object, error) {
-	if len(args) != 3 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-	}
-
-	i2, ok := objects.ToInt(args[1])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "int(compatible)",
-			Found:    args[1].TypeName(),
-		}
-	}
-
-	i3, ok := objects.ToInt(args[2])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "third",
-			Expected: "int(compatible)",
-			Found:    args[2].TypeName(),
-		}
-	}
-
-	res, err := os.OpenFile(s1, i2, os.FileMode(i3))
-	if err != nil {
-		return wrapError(err), nil
-	}
-
-	return makeOSFile(res), nil
-}
-
-func osArgs(args ...objects.Object) (objects.Object, error) {
-	if len(args) != 0 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	arr := &objects.Array{}
-	for _, osArg := range os.Args {
-		if len(osArg) > tengo.MaxStringLen {
-			return nil, objects.ErrStringLimit
-		}
-
-		arr.Value = append(arr.Value, &objects.String{Value: osArg})
-	}
-
-	return arr, nil
-}
-
-func osFuncASFmRE(name string, fn func(string, os.FileMode) error) *objects.UserFunction {
-	return &objects.UserFunction{
-		Name: name,
-		Value: func(args ...objects.Object) (objects.Object, error) {
-			if len(args) != 2 {
-				return nil, objects.ErrWrongNumArguments
-			}
-
-			s1, ok := objects.ToString(args[0])
-			if !ok {
-				return nil, objects.ErrInvalidArgumentType{
-					Name:     "first",
-					Expected: "string(compatible)",
-					Found:    args[0].TypeName(),
-				}
-			}
-			i2, ok := objects.ToInt64(args[1])
-			if !ok {
-				return nil, objects.ErrInvalidArgumentType{
-					Name:     "second",
-					Expected: "int(compatible)",
-					Found:    args[1].TypeName(),
-				}
-			}
-
-			return wrapError(fn(s1, os.FileMode(i2))), nil
-		},
-	}
-}
-
-func osLookupEnv(args ...objects.Object) (objects.Object, error) {
-	if len(args) != 1 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-	}
-
-	res, ok := os.LookupEnv(s1)
-	if !ok {
-		return objects.FalseValue, nil
-	}
-
-	if len(res) > tengo.MaxStringLen {
-		return nil, objects.ErrStringLimit
-	}
-
-	return &objects.String{Value: res}, nil
-}
-
-func osExpandEnv(args ...objects.Object) (objects.Object, error) {
-	if len(args) != 1 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-	}
-
-	var vlen int
-	var failed bool
-	s := os.Expand(s1, func(k string) string {
-		if failed {
-			return ""
-		}
-
-		v := os.Getenv(k)
-
-		// this does not count the other texts that are not being replaced
-		// but the code checks the final length at the end
-		vlen += len(v)
-		if vlen > tengo.MaxStringLen {
-			failed = true
-			return ""
-		}
-
-		return v
-	})
-
-	if failed || len(s) > tengo.MaxStringLen {
-		return nil, objects.ErrStringLimit
-	}
-
-	return &objects.String{Value: s}, nil
-}
-
-func osExec(args ...objects.Object) (objects.Object, error) {
-	if len(args) == 0 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	name, ok := objects.ToString(args[0])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-	}
-
-	var execArgs []string
-	for idx, arg := range args[1:] {
-		execArg, ok := objects.ToString(arg)
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     fmt.Sprintf("args[%d]", idx),
-				Expected: "string(compatible)",
-				Found:    args[1+idx].TypeName(),
-			}
-		}
-
-		execArgs = append(execArgs, execArg)
-	}
-
-	return makeOSExecCommand(exec.Command(name, execArgs...)), nil
-}
-
-func osFindProcess(args ...objects.Object) (objects.Object, error) {
-	if len(args) != 1 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	i1, ok := objects.ToInt(args[0])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "int(compatible)",
-			Found:    args[0].TypeName(),
-		}
-	}
-
-	proc, err := os.FindProcess(i1)
-	if err != nil {
-		return wrapError(err), nil
-	}
-
-	return makeOSProcess(proc), nil
-}
-
-func osStartProcess(args ...objects.Object) (objects.Object, error) {
-	if len(args) != 4 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	name, ok := objects.ToString(args[0])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-	}
-
-	var argv []string
-	var err error
-	switch arg1 := args[1].(type) {
-	case *objects.Array:
-		argv, err = stringArray(arg1.Value, "second")
-		if err != nil {
-			return nil, err
-		}
-	case *objects.ImmutableArray:
-		argv, err = stringArray(arg1.Value, "second")
-		if err != nil {
-			return nil, err
-		}
-	default:
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "array",
-			Found:    arg1.TypeName(),
-		}
-	}
-
-	dir, ok := objects.ToString(args[2])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "third",
-			Expected: "string(compatible)",
-			Found:    args[2].TypeName(),
-		}
-	}
-
-	var env []string
-	switch arg3 := args[3].(type) {
-	case *objects.Array:
-		env, err = stringArray(arg3.Value, "fourth")
-		if err != nil {
-			return nil, err
-		}
-	case *objects.ImmutableArray:
-		env, err = stringArray(arg3.Value, "fourth")
-		if err != nil {
-			return nil, err
-		}
-	default:
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "fourth",
-			Expected: "array",
-			Found:    arg3.TypeName(),
-		}
-	}
-
-	proc, err := os.StartProcess(name, argv, &os.ProcAttr{
-		Dir: dir,
-		Env: env,
-	})
-	if err != nil {
-		return wrapError(err), nil
-	}
-
-	return makeOSProcess(proc), nil
-}
-
-func stringArray(arr []objects.Object, argName string) ([]string, error) {
-	var sarr []string
-	for idx, elem := range arr {
-		str, ok := elem.(*objects.String)
-		if !ok {
-			return nil, objects.ErrInvalidArgumentType{
-				Name:     fmt.Sprintf("%s[%d]", argName, idx),
-				Expected: "string",
-				Found:    elem.TypeName(),
-			}
-		}
-
-		sarr = append(sarr, str.Value)
-	}
-
-	return sarr, nil
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/os_exec.go b/vendor/github.com/d5/tengo/stdlib/os_exec.go
deleted file mode 100644
index 5274c36a..00000000
--- a/vendor/github.com/d5/tengo/stdlib/os_exec.go
+++ /dev/null
@@ -1,113 +0,0 @@
-package stdlib
-
-import (
-	"os/exec"
-
-	"github.com/d5/tengo/objects"
-)
-
-func makeOSExecCommand(cmd *exec.Cmd) *objects.ImmutableMap {
-	return &objects.ImmutableMap{
-		Value: map[string]objects.Object{
-			// combined_output() => bytes/error
-			"combined_output": &objects.UserFunction{Name: "combined_output", Value: FuncARYE(cmd.CombinedOutput)}, //
-			// output() => bytes/error
-			"output": &objects.UserFunction{Name: "output", Value: FuncARYE(cmd.Output)}, //
-			// run() => error
-			"run": &objects.UserFunction{Name: "run", Value: FuncARE(cmd.Run)}, //
-			// start() => error
-			"start": &objects.UserFunction{Name: "start", Value: FuncARE(cmd.Start)}, //
-			// wait() => error
-			"wait": &objects.UserFunction{Name: "wait", Value: FuncARE(cmd.Wait)}, //
-			// set_path(path string)
-			"set_path": &objects.UserFunction{
-				Name: "set_path",
-				Value: func(args ...objects.Object) (ret objects.Object, err error) {
-					if len(args) != 1 {
-						return nil, objects.ErrWrongNumArguments
-					}
-
-					s1, ok := objects.ToString(args[0])
-					if !ok {
-						return nil, objects.ErrInvalidArgumentType{
-							Name:     "first",
-							Expected: "string(compatible)",
-							Found:    args[0].TypeName(),
-						}
-					}
-
-					cmd.Path = s1
-
-					return objects.UndefinedValue, nil
-				},
-			},
-			// set_dir(dir string)
-			"set_dir": &objects.UserFunction{
-				Name: "set_dir",
-				Value: func(args ...objects.Object) (ret objects.Object, err error) {
-					if len(args) != 1 {
-						return nil, objects.ErrWrongNumArguments
-					}
-
-					s1, ok := objects.ToString(args[0])
-					if !ok {
-						return nil, objects.ErrInvalidArgumentType{
-							Name:     "first",
-							Expected: "string(compatible)",
-							Found:    args[0].TypeName(),
-						}
-					}
-
-					cmd.Dir = s1
-
-					return objects.UndefinedValue, nil
-				},
-			},
-			// set_env(env array(string))
-			"set_env": &objects.UserFunction{
-				Name: "set_env",
-				Value: func(args ...objects.Object) (objects.Object, error) {
-					if len(args) != 1 {
-						return nil, objects.ErrWrongNumArguments
-					}
-
-					var env []string
-					var err error
-					switch arg0 := args[0].(type) {
-					case *objects.Array:
-						env, err = stringArray(arg0.Value, "first")
-						if err != nil {
-							return nil, err
-						}
-					case *objects.ImmutableArray:
-						env, err = stringArray(arg0.Value, "first")
-						if err != nil {
-							return nil, err
-						}
-					default:
-						return nil, objects.ErrInvalidArgumentType{
-							Name:     "first",
-							Expected: "array",
-							Found:    arg0.TypeName(),
-						}
-					}
-
-					cmd.Env = env
-
-					return objects.UndefinedValue, nil
-				},
-			},
-			// process() => imap(process)
-			"process": &objects.UserFunction{
-				Name: "process",
-				Value: func(args ...objects.Object) (ret objects.Object, err error) {
-					if len(args) != 0 {
-						return nil, objects.ErrWrongNumArguments
-					}
-
-					return makeOSProcess(cmd.Process), nil
-				},
-			},
-		},
-	}
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/os_file.go b/vendor/github.com/d5/tengo/stdlib/os_file.go
deleted file mode 100644
index ee9f625a..00000000
--- a/vendor/github.com/d5/tengo/stdlib/os_file.go
+++ /dev/null
@@ -1,96 +0,0 @@
-package stdlib
-
-import (
-	"os"
-
-	"github.com/d5/tengo/objects"
-)
-
-func makeOSFile(file *os.File) *objects.ImmutableMap {
-	return &objects.ImmutableMap{
-		Value: map[string]objects.Object{
-			// chdir() => true/error
-			"chdir": &objects.UserFunction{Name: "chdir", Value: FuncARE(file.Chdir)}, //
-			// chown(uid int, gid int) => true/error
-			"chown": &objects.UserFunction{Name: "chown", Value: FuncAIIRE(file.Chown)}, //
-			// close() => error
-			"close": &objects.UserFunction{Name: "close", Value: FuncARE(file.Close)}, //
-			// name() => string
-			"name": &objects.UserFunction{Name: "name", Value: FuncARS(file.Name)}, //
-			// readdirnames(n int) => array(string)/error
-			"readdirnames": &objects.UserFunction{Name: "readdirnames", Value: FuncAIRSsE(file.Readdirnames)}, //
-			// sync() => error
-			"sync": &objects.UserFunction{Name: "sync", Value: FuncARE(file.Sync)}, //
-			// write(bytes) => int/error
-			"write": &objects.UserFunction{Name: "write", Value: FuncAYRIE(file.Write)}, //
-			// write(string) => int/error
-			"write_string": &objects.UserFunction{Name: "write_string", Value: FuncASRIE(file.WriteString)}, //
-			// read(bytes) => int/error
-			"read": &objects.UserFunction{Name: "read", Value: FuncAYRIE(file.Read)}, //
-			// chmod(mode int) => error
-			"chmod": &objects.UserFunction{
-				Name: "chmod",
-				Value: func(args ...objects.Object) (ret objects.Object, err error) {
-					if len(args) != 1 {
-						return nil, objects.ErrWrongNumArguments
-					}
-
-					i1, ok := objects.ToInt64(args[0])
-					if !ok {
-						return nil, objects.ErrInvalidArgumentType{
-							Name:     "first",
-							Expected: "int(compatible)",
-							Found:    args[0].TypeName(),
-						}
-					}
-
-					return wrapError(file.Chmod(os.FileMode(i1))), nil
-				},
-			},
-			// seek(offset int, whence int) => int/error
-			"seek": &objects.UserFunction{
-				Name: "seek",
-				Value: func(args ...objects.Object) (ret objects.Object, err error) {
-					if len(args) != 2 {
-						return nil, objects.ErrWrongNumArguments
-					}
-
-					i1, ok := objects.ToInt64(args[0])
-					if !ok {
-						return nil, objects.ErrInvalidArgumentType{
-							Name:     "first",
-							Expected: "int(compatible)",
-							Found:    args[0].TypeName(),
-						}
-					}
-					i2, ok := objects.ToInt(args[1])
-					if !ok {
-						return nil, objects.ErrInvalidArgumentType{
-							Name:     "second",
-							Expected: "int(compatible)",
-							Found:    args[1].TypeName(),
-						}
-					}
-
-					res, err := file.Seek(i1, i2)
-					if err != nil {
-						return wrapError(err), nil
-					}
-
-					return &objects.Int{Value: res}, nil
-				},
-			},
-			// stat() => imap(fileinfo)/error
-			"stat": &objects.UserFunction{
-				Name: "start",
-				Value: func(args ...objects.Object) (ret objects.Object, err error) {
-					if len(args) != 0 {
-						return nil, objects.ErrWrongNumArguments
-					}
-
-					return osStat(&objects.String{Value: file.Name()})
-				},
-			},
-		},
-	}
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/os_process.go b/vendor/github.com/d5/tengo/stdlib/os_process.go
deleted file mode 100644
index 801ccdef..00000000
--- a/vendor/github.com/d5/tengo/stdlib/os_process.go
+++ /dev/null
@@ -1,62 +0,0 @@
-package stdlib
-
-import (
-	"os"
-	"syscall"
-
-	"github.com/d5/tengo/objects"
-)
-
-func makeOSProcessState(state *os.ProcessState) *objects.ImmutableMap {
-	return &objects.ImmutableMap{
-		Value: map[string]objects.Object{
-			"exited":  &objects.UserFunction{Name: "exited", Value: FuncARB(state.Exited)},   //
-			"pid":     &objects.UserFunction{Name: "pid", Value: FuncARI(state.Pid)},         //
-			"string":  &objects.UserFunction{Name: "string", Value: FuncARS(state.String)},   //
-			"success": &objects.UserFunction{Name: "success", Value: FuncARB(state.Success)}, //
-		},
-	}
-}
-
-func makeOSProcess(proc *os.Process) *objects.ImmutableMap {
-	return &objects.ImmutableMap{
-		Value: map[string]objects.Object{
-			"kill":    &objects.UserFunction{Name: "kill", Value: FuncARE(proc.Kill)},       //
-			"release": &objects.UserFunction{Name: "release", Value: FuncARE(proc.Release)}, //
-			"signal": &objects.UserFunction{
-				Name: "signal",
-				Value: func(args ...objects.Object) (ret objects.Object, err error) {
-					if len(args) != 1 {
-						return nil, objects.ErrWrongNumArguments
-					}
-
-					i1, ok := objects.ToInt64(args[0])
-					if !ok {
-						return nil, objects.ErrInvalidArgumentType{
-							Name:     "first",
-							Expected: "int(compatible)",
-							Found:    args[0].TypeName(),
-						}
-					}
-
-					return wrapError(proc.Signal(syscall.Signal(i1))), nil
-				},
-			},
-			"wait": &objects.UserFunction{
-				Name: "wait",
-				Value: func(args ...objects.Object) (ret objects.Object, err error) {
-					if len(args) != 0 {
-						return nil, objects.ErrWrongNumArguments
-					}
-
-					state, err := proc.Wait()
-					if err != nil {
-						return wrapError(err), nil
-					}
-
-					return makeOSProcessState(state), nil
-				},
-			},
-		},
-	}
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/rand.go b/vendor/github.com/d5/tengo/stdlib/rand.go
deleted file mode 100644
index 6efe1de8..00000000
--- a/vendor/github.com/d5/tengo/stdlib/rand.go
+++ /dev/null
@@ -1,102 +0,0 @@
-package stdlib
-
-import (
-	"math/rand"
-
-	"github.com/d5/tengo/objects"
-)
-
-var randModule = map[string]objects.Object{
-	"int":        &objects.UserFunction{Name: "int", Value: FuncARI64(rand.Int63)},
-	"float":      &objects.UserFunction{Name: "float", Value: FuncARF(rand.Float64)},
-	"intn":       &objects.UserFunction{Name: "intn", Value: FuncAI64RI64(rand.Int63n)},
-	"exp_float":  &objects.UserFunction{Name: "exp_float", Value: FuncARF(rand.ExpFloat64)},
-	"norm_float": &objects.UserFunction{Name: "norm_float", Value: FuncARF(rand.NormFloat64)},
-	"perm":       &objects.UserFunction{Name: "perm", Value: FuncAIRIs(rand.Perm)},
-	"seed":       &objects.UserFunction{Name: "seed", Value: FuncAI64R(rand.Seed)},
-	"read": &objects.UserFunction{
-		Name: "read",
-		Value: func(args ...objects.Object) (ret objects.Object, err error) {
-			if len(args) != 1 {
-				return nil, objects.ErrWrongNumArguments
-			}
-
-			y1, ok := args[0].(*objects.Bytes)
-			if !ok {
-				return nil, objects.ErrInvalidArgumentType{
-					Name:     "first",
-					Expected: "bytes",
-					Found:    args[0].TypeName(),
-				}
-			}
-
-			res, err := rand.Read(y1.Value)
-			if err != nil {
-				ret = wrapError(err)
-				return
-			}
-
-			return &objects.Int{Value: int64(res)}, nil
-		},
-	},
-	"rand": &objects.UserFunction{
-		Name: "rand",
-		Value: func(args ...objects.Object) (ret objects.Object, err error) {
-			if len(args) != 1 {
-				return nil, objects.ErrWrongNumArguments
-			}
-
-			i1, ok := objects.ToInt64(args[0])
-			if !ok {
-				return nil, objects.ErrInvalidArgumentType{
-					Name:     "first",
-					Expected: "int(compatible)",
-					Found:    args[0].TypeName(),
-				}
-			}
-
-			src := rand.NewSource(i1)
-
-			return randRand(rand.New(src)), nil
-		},
-	},
-}
-
-func randRand(r *rand.Rand) *objects.ImmutableMap {
-	return &objects.ImmutableMap{
-		Value: map[string]objects.Object{
-			"int":        &objects.UserFunction{Name: "int", Value: FuncARI64(r.Int63)},
-			"float":      &objects.UserFunction{Name: "float", Value: FuncARF(r.Float64)},
-			"intn":       &objects.UserFunction{Name: "intn", Value: FuncAI64RI64(r.Int63n)},
-			"exp_float":  &objects.UserFunction{Name: "exp_float", Value: FuncARF(r.ExpFloat64)},
-			"norm_float": &objects.UserFunction{Name: "norm_float", Value: FuncARF(r.NormFloat64)},
-			"perm":       &objects.UserFunction{Name: "perm", Value: FuncAIRIs(r.Perm)},
-			"seed":       &objects.UserFunction{Name: "seed", Value: FuncAI64R(r.Seed)},
-			"read": &objects.UserFunction{
-				Name: "read",
-				Value: func(args ...objects.Object) (ret objects.Object, err error) {
-					if len(args) != 1 {
-						return nil, objects.ErrWrongNumArguments
-					}
-
-					y1, ok := args[0].(*objects.Bytes)
-					if !ok {
-						return nil, objects.ErrInvalidArgumentType{
-							Name:     "first",
-							Expected: "bytes",
-							Found:    args[0].TypeName(),
-						}
-					}
-
-					res, err := r.Read(y1.Value)
-					if err != nil {
-						ret = wrapError(err)
-						return
-					}
-
-					return &objects.Int{Value: int64(res)}, nil
-				},
-			},
-		},
-	}
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/text.go b/vendor/github.com/d5/tengo/stdlib/text.go
deleted file mode 100644
index 4b5729ec..00000000
--- a/vendor/github.com/d5/tengo/stdlib/text.go
+++ /dev/null
@@ -1,930 +0,0 @@
-package stdlib
-
-import (
-	"fmt"
-	"regexp"
-	"strconv"
-	"strings"
-	"unicode/utf8"
-
-	"github.com/d5/tengo"
-	"github.com/d5/tengo/objects"
-)
-
-var textModule = map[string]objects.Object{
-	"re_match":       &objects.UserFunction{Name: "re_match", Value: textREMatch},                           // re_match(pattern, text) => bool/error
-	"re_find":        &objects.UserFunction{Name: "re_find", Value: textREFind},                             // re_find(pattern, text, count) => [[{text:,begin:,end:}]]/undefined
-	"re_replace":     &objects.UserFunction{Name: "re_replace", Value: textREReplace},                       // re_replace(pattern, text, repl) => string/error
-	"re_split":       &objects.UserFunction{Name: "re_split", Value: textRESplit},                           // re_split(pattern, text, count) => [string]/error
-	"re_compile":     &objects.UserFunction{Name: "re_compile", Value: textRECompile},                       // re_compile(pattern) => Regexp/error
-	"compare":        &objects.UserFunction{Name: "compare", Value: FuncASSRI(strings.Compare)},             // compare(a, b) => int
-	"contains":       &objects.UserFunction{Name: "contains", Value: FuncASSRB(strings.Contains)},           // contains(s, substr) => bool
-	"contains_any":   &objects.UserFunction{Name: "contains_any", Value: FuncASSRB(strings.ContainsAny)},    // contains_any(s, chars) => bool
-	"count":          &objects.UserFunction{Name: "count", Value: FuncASSRI(strings.Count)},                 // count(s, substr) => int
-	"equal_fold":     &objects.UserFunction{Name: "equal_fold", Value: FuncASSRB(strings.EqualFold)},        // "equal_fold(s, t) => bool
-	"fields":         &objects.UserFunction{Name: "fields", Value: FuncASRSs(strings.Fields)},               // fields(s) => [string]
-	"has_prefix":     &objects.UserFunction{Name: "has_prefix", Value: FuncASSRB(strings.HasPrefix)},        // has_prefix(s, prefix) => bool
-	"has_suffix":     &objects.UserFunction{Name: "has_suffix", Value: FuncASSRB(strings.HasSuffix)},        // has_suffix(s, suffix) => bool
-	"index":          &objects.UserFunction{Name: "index", Value: FuncASSRI(strings.Index)},                 // index(s, substr) => int
-	"index_any":      &objects.UserFunction{Name: "index_any", Value: FuncASSRI(strings.IndexAny)},          // index_any(s, chars) => int
-	"join":           &objects.UserFunction{Name: "join", Value: textJoin},                                  // join(arr, sep) => string
-	"last_index":     &objects.UserFunction{Name: "last_index", Value: FuncASSRI(strings.LastIndex)},        // last_index(s, substr) => int
-	"last_index_any": &objects.UserFunction{Name: "last_index_any", Value: FuncASSRI(strings.LastIndexAny)}, // last_index_any(s, chars) => int
-	"repeat":         &objects.UserFunction{Name: "repeat", Value: textRepeat},                              // repeat(s, count) => string
-	"replace":        &objects.UserFunction{Name: "replace", Value: textReplace},                            // replace(s, old, new, n) => string
-	"substr":         &objects.UserFunction{Name: "substr", Value: textSubstring},                           // substr(s, lower, upper) => string
-	"split":          &objects.UserFunction{Name: "split", Value: FuncASSRSs(strings.Split)},                // split(s, sep) => [string]
-	"split_after":    &objects.UserFunction{Name: "split_after", Value: FuncASSRSs(strings.SplitAfter)},     // split_after(s, sep) => [string]
-	"split_after_n":  &objects.UserFunction{Name: "split_after_n", Value: FuncASSIRSs(strings.SplitAfterN)}, // split_after_n(s, sep, n) => [string]
-	"split_n":        &objects.UserFunction{Name: "split_n", Value: FuncASSIRSs(strings.SplitN)},            // split_n(s, sep, n) => [string]
-	"title":          &objects.UserFunction{Name: "title", Value: FuncASRS(strings.Title)},                  // title(s) => string
-	"to_lower":       &objects.UserFunction{Name: "to_lower", Value: FuncASRS(strings.ToLower)},             // to_lower(s) => string
-	"to_title":       &objects.UserFunction{Name: "to_title", Value: FuncASRS(strings.ToTitle)},             // to_title(s) => string
-	"to_upper":       &objects.UserFunction{Name: "to_upper", Value: FuncASRS(strings.ToUpper)},             // to_upper(s) => string
-	"pad_left":       &objects.UserFunction{Name: "pad_left", Value: textPadLeft},                           // pad_left(s, pad_len, pad_with) => string
-	"pad_right":      &objects.UserFunction{Name: "pad_right", Value: textPadRight},                         // pad_right(s, pad_len, pad_with) => string
-	"trim":           &objects.UserFunction{Name: "trim", Value: FuncASSRS(strings.Trim)},                   // trim(s, cutset) => string
-	"trim_left":      &objects.UserFunction{Name: "trim_left", Value: FuncASSRS(strings.TrimLeft)},          // trim_left(s, cutset) => string
-	"trim_prefix":    &objects.UserFunction{Name: "trim_prefix", Value: FuncASSRS(strings.TrimPrefix)},      // trim_prefix(s, prefix) => string
-	"trim_right":     &objects.UserFunction{Name: "trim_right", Value: FuncASSRS(strings.TrimRight)},        // trim_right(s, cutset) => string
-	"trim_space":     &objects.UserFunction{Name: "trim_space", Value: FuncASRS(strings.TrimSpace)},         // trim_space(s) => string
-	"trim_suffix":    &objects.UserFunction{Name: "trim_suffix", Value: FuncASSRS(strings.TrimSuffix)},      // trim_suffix(s, suffix) => string
-	"atoi":           &objects.UserFunction{Name: "atoi", Value: FuncASRIE(strconv.Atoi)},                   // atoi(str) => int/error
-	"format_bool":    &objects.UserFunction{Name: "format_bool", Value: textFormatBool},                     // format_bool(b) => string
-	"format_float":   &objects.UserFunction{Name: "format_float", Value: textFormatFloat},                   // format_float(f, fmt, prec, bits) => string
-	"format_int":     &objects.UserFunction{Name: "format_int", Value: textFormatInt},                       // format_int(i, base) => string
-	"itoa":           &objects.UserFunction{Name: "itoa", Value: FuncAIRS(strconv.Itoa)},                    // itoa(i) => string
-	"parse_bool":     &objects.UserFunction{Name: "parse_bool", Value: textParseBool},                       // parse_bool(str) => bool/error
-	"parse_float":    &objects.UserFunction{Name: "parse_float", Value: textParseFloat},                     // parse_float(str, bits) => float/error
-	"parse_int":      &objects.UserFunction{Name: "parse_int", Value: textParseInt},                         // parse_int(str, base, bits) => int/error
-	"quote":          &objects.UserFunction{Name: "quote", Value: FuncASRS(strconv.Quote)},                  // quote(str) => string
-	"unquote":        &objects.UserFunction{Name: "unquote", Value: FuncASRSE(strconv.Unquote)},             // unquote(str) => string/error
-}
-
-func textREMatch(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 2 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	s2, ok := objects.ToString(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "string(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	matched, err := regexp.MatchString(s1, s2)
-	if err != nil {
-		ret = wrapError(err)
-		return
-	}
-
-	if matched {
-		ret = objects.TrueValue
-	} else {
-		ret = objects.FalseValue
-	}
-
-	return
-}
-
-func textREFind(args ...objects.Object) (ret objects.Object, err error) {
-	numArgs := len(args)
-	if numArgs != 2 && numArgs != 3 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	re, err := regexp.Compile(s1)
-	if err != nil {
-		ret = wrapError(err)
-		return
-	}
-
-	s2, ok := objects.ToString(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "string(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	if numArgs < 3 {
-		m := re.FindStringSubmatchIndex(s2)
-		if m == nil {
-			ret = objects.UndefinedValue
-			return
-		}
-
-		arr := &objects.Array{}
-		for i := 0; i < len(m); i += 2 {
-			arr.Value = append(arr.Value, &objects.ImmutableMap{Value: map[string]objects.Object{
-				"text":  &objects.String{Value: s2[m[i]:m[i+1]]},
-				"begin": &objects.Int{Value: int64(m[i])},
-				"end":   &objects.Int{Value: int64(m[i+1])},
-			}})
-		}
-
-		ret = &objects.Array{Value: []objects.Object{arr}}
-
-		return
-	}
-
-	i3, ok := objects.ToInt(args[2])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "third",
-			Expected: "int(compatible)",
-			Found:    args[2].TypeName(),
-		}
-		return
-	}
-	m := re.FindAllStringSubmatchIndex(s2, i3)
-	if m == nil {
-		ret = objects.UndefinedValue
-		return
-	}
-
-	arr := &objects.Array{}
-	for _, m := range m {
-		subMatch := &objects.Array{}
-		for i := 0; i < len(m); i += 2 {
-			subMatch.Value = append(subMatch.Value, &objects.ImmutableMap{Value: map[string]objects.Object{
-				"text":  &objects.String{Value: s2[m[i]:m[i+1]]},
-				"begin": &objects.Int{Value: int64(m[i])},
-				"end":   &objects.Int{Value: int64(m[i+1])},
-			}})
-		}
-
-		arr.Value = append(arr.Value, subMatch)
-	}
-
-	ret = arr
-
-	return
-}
-
-func textREReplace(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 3 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	s2, ok := objects.ToString(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "string(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	s3, ok := objects.ToString(args[2])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "third",
-			Expected: "string(compatible)",
-			Found:    args[2].TypeName(),
-		}
-		return
-	}
-
-	re, err := regexp.Compile(s1)
-	if err != nil {
-		ret = wrapError(err)
-	} else {
-		s, ok := doTextRegexpReplace(re, s2, s3)
-		if !ok {
-			return nil, objects.ErrStringLimit
-		}
-
-		ret = &objects.String{Value: s}
-	}
-
-	return
-}
-
-func textRESplit(args ...objects.Object) (ret objects.Object, err error) {
-	numArgs := len(args)
-	if numArgs != 2 && numArgs != 3 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	s2, ok := objects.ToString(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "string(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	var i3 = -1
-	if numArgs > 2 {
-		i3, ok = objects.ToInt(args[2])
-		if !ok {
-			err = objects.ErrInvalidArgumentType{
-				Name:     "third",
-				Expected: "int(compatible)",
-				Found:    args[2].TypeName(),
-			}
-			return
-		}
-	}
-
-	re, err := regexp.Compile(s1)
-	if err != nil {
-		ret = wrapError(err)
-		return
-	}
-
-	arr := &objects.Array{}
-	for _, s := range re.Split(s2, i3) {
-		arr.Value = append(arr.Value, &objects.String{Value: s})
-	}
-
-	ret = arr
-
-	return
-}
-
-func textRECompile(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	re, err := regexp.Compile(s1)
-	if err != nil {
-		ret = wrapError(err)
-	} else {
-		ret = makeTextRegexp(re)
-	}
-
-	return
-}
-
-func textReplace(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 4 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	s2, ok := objects.ToString(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "string(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	s3, ok := objects.ToString(args[2])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "third",
-			Expected: "string(compatible)",
-			Found:    args[2].TypeName(),
-		}
-		return
-	}
-
-	i4, ok := objects.ToInt(args[3])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "fourth",
-			Expected: "int(compatible)",
-			Found:    args[3].TypeName(),
-		}
-		return
-	}
-
-	s, ok := doTextReplace(s1, s2, s3, i4)
-	if !ok {
-		err = objects.ErrStringLimit
-		return
-	}
-
-	ret = &objects.String{Value: s}
-
-	return
-}
-
-func textSubstring(args ...objects.Object) (ret objects.Object, err error) {
-	argslen := len(args)
-	if argslen != 2 && argslen != 3 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	i2, ok := objects.ToInt(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "int(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	strlen := len(s1)
-	i3 := strlen
-	if argslen == 3 {
-		i3, ok = objects.ToInt(args[2])
-		if !ok {
-			err = objects.ErrInvalidArgumentType{
-				Name:     "third",
-				Expected: "int(compatible)",
-				Found:    args[2].TypeName(),
-			}
-			return
-		}
-	}
-
-	if i2 > i3 {
-		err = objects.ErrInvalidIndexType
-		return
-	}
-
-	if i2 < 0 {
-		i2 = 0
-	} else if i2 > strlen {
-		i2 = strlen
-	}
-
-	if i3 < 0 {
-		i3 = 0
-	} else if i3 > strlen {
-		i3 = strlen
-	}
-
-	ret = &objects.String{Value: s1[i2:i3]}
-
-	return
-}
-
-func textPadLeft(args ...objects.Object) (ret objects.Object, err error) {
-	argslen := len(args)
-	if argslen != 2 && argslen != 3 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	i2, ok := objects.ToInt(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "int(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	if i2 > tengo.MaxStringLen {
-		return nil, objects.ErrStringLimit
-	}
-
-	sLen := len(s1)
-	if sLen >= i2 {
-		ret = &objects.String{Value: s1}
-		return
-	}
-
-	s3 := " "
-	if argslen == 3 {
-		s3, ok = objects.ToString(args[2])
-		if !ok {
-			err = objects.ErrInvalidArgumentType{
-				Name:     "third",
-				Expected: "string(compatible)",
-				Found:    args[2].TypeName(),
-			}
-			return
-		}
-	}
-
-	padStrLen := len(s3)
-	if padStrLen == 0 {
-		ret = &objects.String{Value: s1}
-		return
-	}
-
-	padCount := ((i2 - padStrLen) / padStrLen) + 1
-	retStr := strings.Repeat(s3, int(padCount)) + s1
-	ret = &objects.String{Value: retStr[len(retStr)-i2:]}
-
-	return
-}
-
-func textPadRight(args ...objects.Object) (ret objects.Object, err error) {
-	argslen := len(args)
-	if argslen != 2 && argslen != 3 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	i2, ok := objects.ToInt(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "int(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	if i2 > tengo.MaxStringLen {
-		return nil, objects.ErrStringLimit
-	}
-
-	sLen := len(s1)
-	if sLen >= i2 {
-		ret = &objects.String{Value: s1}
-		return
-	}
-
-	s3 := " "
-	if argslen == 3 {
-		s3, ok = objects.ToString(args[2])
-		if !ok {
-			err = objects.ErrInvalidArgumentType{
-				Name:     "third",
-				Expected: "string(compatible)",
-				Found:    args[2].TypeName(),
-			}
-			return
-		}
-	}
-
-	padStrLen := len(s3)
-	if padStrLen == 0 {
-		ret = &objects.String{Value: s1}
-		return
-	}
-
-	padCount := ((i2 - padStrLen) / padStrLen) + 1
-	retStr := s1 + strings.Repeat(s3, int(padCount))
-	ret = &objects.String{Value: retStr[:i2]}
-
-	return
-}
-
-func textRepeat(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 2 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-	}
-
-	i2, ok := objects.ToInt(args[1])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "int(compatible)",
-			Found:    args[1].TypeName(),
-		}
-	}
-
-	if len(s1)*i2 > tengo.MaxStringLen {
-		return nil, objects.ErrStringLimit
-	}
-
-	return &objects.String{Value: strings.Repeat(s1, i2)}, nil
-}
-
-func textJoin(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 2 {
-		return nil, objects.ErrWrongNumArguments
-	}
-
-	var slen int
-	var ss1 []string
-	switch arg0 := args[0].(type) {
-	case *objects.Array:
-		for idx, a := range arg0.Value {
-			as, ok := objects.ToString(a)
-			if !ok {
-				return nil, objects.ErrInvalidArgumentType{
-					Name:     fmt.Sprintf("first[%d]", idx),
-					Expected: "string(compatible)",
-					Found:    a.TypeName(),
-				}
-			}
-			slen += len(as)
-			ss1 = append(ss1, as)
-		}
-	case *objects.ImmutableArray:
-		for idx, a := range arg0.Value {
-			as, ok := objects.ToString(a)
-			if !ok {
-				return nil, objects.ErrInvalidArgumentType{
-					Name:     fmt.Sprintf("first[%d]", idx),
-					Expected: "string(compatible)",
-					Found:    a.TypeName(),
-				}
-			}
-			slen += len(as)
-			ss1 = append(ss1, as)
-		}
-	default:
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "array",
-			Found:    args[0].TypeName(),
-		}
-	}
-
-	s2, ok := objects.ToString(args[1])
-	if !ok {
-		return nil, objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "string(compatible)",
-			Found:    args[1].TypeName(),
-		}
-	}
-
-	// make sure output length does not exceed the limit
-	if slen+len(s2)*(len(ss1)-1) > tengo.MaxStringLen {
-		return nil, objects.ErrStringLimit
-	}
-
-	return &objects.String{Value: strings.Join(ss1, s2)}, nil
-}
-
-func textFormatBool(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	b1, ok := args[0].(*objects.Bool)
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "bool",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	if b1 == objects.TrueValue {
-		ret = &objects.String{Value: "true"}
-	} else {
-		ret = &objects.String{Value: "false"}
-	}
-
-	return
-}
-
-func textFormatFloat(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 4 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	f1, ok := args[0].(*objects.Float)
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "float",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	s2, ok := objects.ToString(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "string(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	i3, ok := objects.ToInt(args[2])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "third",
-			Expected: "int(compatible)",
-			Found:    args[2].TypeName(),
-		}
-		return
-	}
-
-	i4, ok := objects.ToInt(args[3])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "fourth",
-			Expected: "int(compatible)",
-			Found:    args[3].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.String{Value: strconv.FormatFloat(f1.Value, s2[0], i3, i4)}
-
-	return
-}
-
-func textFormatInt(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 2 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	i1, ok := args[0].(*objects.Int)
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "int",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	i2, ok := objects.ToInt(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "int(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.String{Value: strconv.FormatInt(i1.Value, i2)}
-
-	return
-}
-
-func textParseBool(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	s1, ok := args[0].(*objects.String)
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	parsed, err := strconv.ParseBool(s1.Value)
-	if err != nil {
-		ret = wrapError(err)
-		return
-	}
-
-	if parsed {
-		ret = objects.TrueValue
-	} else {
-		ret = objects.FalseValue
-	}
-
-	return
-}
-
-func textParseFloat(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 2 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	s1, ok := args[0].(*objects.String)
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	i2, ok := objects.ToInt(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "int(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	parsed, err := strconv.ParseFloat(s1.Value, i2)
-	if err != nil {
-		ret = wrapError(err)
-		return
-	}
-
-	ret = &objects.Float{Value: parsed}
-
-	return
-}
-
-func textParseInt(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 3 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	s1, ok := args[0].(*objects.String)
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	i2, ok := objects.ToInt(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "int(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	i3, ok := objects.ToInt(args[2])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "third",
-			Expected: "int(compatible)",
-			Found:    args[2].TypeName(),
-		}
-		return
-	}
-
-	parsed, err := strconv.ParseInt(s1.Value, i2, i3)
-	if err != nil {
-		ret = wrapError(err)
-		return
-	}
-
-	ret = &objects.Int{Value: parsed}
-
-	return
-}
-
-// Modified implementation of strings.Replace
-// to limit the maximum length of output string.
-func doTextReplace(s, old, new string, n int) (string, bool) {
-	if old == new || n == 0 {
-		return s, true // avoid allocation
-	}
-
-	// Compute number of replacements.
-	if m := strings.Count(s, old); m == 0 {
-		return s, true // avoid allocation
-	} else if n < 0 || m < n {
-		n = m
-	}
-
-	// Apply replacements to buffer.
-	t := make([]byte, len(s)+n*(len(new)-len(old)))
-	w := 0
-	start := 0
-	for i := 0; i < n; i++ {
-		j := start
-		if len(old) == 0 {
-			if i > 0 {
-				_, wid := utf8.DecodeRuneInString(s[start:])
-				j += wid
-			}
-		} else {
-			j += strings.Index(s[start:], old)
-		}
-
-		ssj := s[start:j]
-		if w+len(ssj)+len(new) > tengo.MaxStringLen {
-			return "", false
-		}
-
-		w += copy(t[w:], ssj)
-		w += copy(t[w:], new)
-		start = j + len(old)
-	}
-
-	ss := s[start:]
-	if w+len(ss) > tengo.MaxStringLen {
-		return "", false
-	}
-
-	w += copy(t[w:], ss)
-
-	return string(t[0:w]), true
-}
diff --git a/vendor/github.com/d5/tengo/stdlib/times.go b/vendor/github.com/d5/tengo/stdlib/times.go
deleted file mode 100644
index 111c877a..00000000
--- a/vendor/github.com/d5/tengo/stdlib/times.go
+++ /dev/null
@@ -1,989 +0,0 @@
-package stdlib
-
-import (
-	"time"
-
-	"github.com/d5/tengo"
-	"github.com/d5/tengo/objects"
-)
-
-var timesModule = map[string]objects.Object{
-	"format_ansic":         &objects.String{Value: time.ANSIC},
-	"format_unix_date":     &objects.String{Value: time.UnixDate},
-	"format_ruby_date":     &objects.String{Value: time.RubyDate},
-	"format_rfc822":        &objects.String{Value: time.RFC822},
-	"format_rfc822z":       &objects.String{Value: time.RFC822Z},
-	"format_rfc850":        &objects.String{Value: time.RFC850},
-	"format_rfc1123":       &objects.String{Value: time.RFC1123},
-	"format_rfc1123z":      &objects.String{Value: time.RFC1123Z},
-	"format_rfc3339":       &objects.String{Value: time.RFC3339},
-	"format_rfc3339_nano":  &objects.String{Value: time.RFC3339Nano},
-	"format_kitchen":       &objects.String{Value: time.Kitchen},
-	"format_stamp":         &objects.String{Value: time.Stamp},
-	"format_stamp_milli":   &objects.String{Value: time.StampMilli},
-	"format_stamp_micro":   &objects.String{Value: time.StampMicro},
-	"format_stamp_nano":    &objects.String{Value: time.StampNano},
-	"nanosecond":           &objects.Int{Value: int64(time.Nanosecond)},
-	"microsecond":          &objects.Int{Value: int64(time.Microsecond)},
-	"millisecond":          &objects.Int{Value: int64(time.Millisecond)},
-	"second":               &objects.Int{Value: int64(time.Second)},
-	"minute":               &objects.Int{Value: int64(time.Minute)},
-	"hour":                 &objects.Int{Value: int64(time.Hour)},
-	"january":              &objects.Int{Value: int64(time.January)},
-	"february":             &objects.Int{Value: int64(time.February)},
-	"march":                &objects.Int{Value: int64(time.March)},
-	"april":                &objects.Int{Value: int64(time.April)},
-	"may":                  &objects.Int{Value: int64(time.May)},
-	"june":                 &objects.Int{Value: int64(time.June)},
-	"july":                 &objects.Int{Value: int64(time.July)},
-	"august":               &objects.Int{Value: int64(time.August)},
-	"september":            &objects.Int{Value: int64(time.September)},
-	"october":              &objects.Int{Value: int64(time.October)},
-	"november":             &objects.Int{Value: int64(time.November)},
-	"december":             &objects.Int{Value: int64(time.December)},
-	"sleep":                &objects.UserFunction{Name: "sleep", Value: timesSleep},                              // sleep(int)
-	"parse_duration":       &objects.UserFunction{Name: "parse_duration", Value: timesParseDuration},             // parse_duration(str) => int
-	"since":                &objects.UserFunction{Name: "since", Value: timesSince},                              // since(time) => int
-	"until":                &objects.UserFunction{Name: "until", Value: timesUntil},                              // until(time) => int
-	"duration_hours":       &objects.UserFunction{Name: "duration_hours", Value: timesDurationHours},             // duration_hours(int) => float
-	"duration_minutes":     &objects.UserFunction{Name: "duration_minutes", Value: timesDurationMinutes},         // duration_minutes(int) => float
-	"duration_nanoseconds": &objects.UserFunction{Name: "duration_nanoseconds", Value: timesDurationNanoseconds}, // duration_nanoseconds(int) => int
-	"duration_seconds":     &objects.UserFunction{Name: "duration_seconds", Value: timesDurationSeconds},         // duration_seconds(int) => float
-	"duration_string":      &objects.UserFunction{Name: "duration_string", Value: timesDurationString},           // duration_string(int) => string
-	"month_string":         &objects.UserFunction{Name: "month_string", Value: timesMonthString},                 // month_string(int) => string
-	"date":                 &objects.UserFunction{Name: "date", Value: timesDate},                                // date(year, month, day, hour, min, sec, nsec) => time
-	"now":                  &objects.UserFunction{Name: "now", Value: timesNow},                                  // now() => time
-	"parse":                &objects.UserFunction{Name: "parse", Value: timesParse},                              // parse(format, str) => time
-	"unix":                 &objects.UserFunction{Name: "unix", Value: timesUnix},                                // unix(sec, nsec) => time
-	"add":                  &objects.UserFunction{Name: "add", Value: timesAdd},                                  // add(time, int) => time
-	"add_date":             &objects.UserFunction{Name: "add_date", Value: timesAddDate},                         // add_date(time, years, months, days) => time
-	"sub":                  &objects.UserFunction{Name: "sub", Value: timesSub},                                  // sub(t time, u time) => int
-	"after":                &objects.UserFunction{Name: "after", Value: timesAfter},                              // after(t time, u time) => bool
-	"before":               &objects.UserFunction{Name: "before", Value: timesBefore},                            // before(t time, u time) => bool
-	"time_year":            &objects.UserFunction{Name: "time_year", Value: timesTimeYear},                       // time_year(time) => int
-	"time_month":           &objects.UserFunction{Name: "time_month", Value: timesTimeMonth},                     // time_month(time) => int
-	"time_day":             &objects.UserFunction{Name: "time_day", Value: timesTimeDay},                         // time_day(time) => int
-	"time_weekday":         &objects.UserFunction{Name: "time_weekday", Value: timesTimeWeekday},                 // time_weekday(time) => int
-	"time_hour":            &objects.UserFunction{Name: "time_hour", Value: timesTimeHour},                       // time_hour(time) => int
-	"time_minute":          &objects.UserFunction{Name: "time_minute", Value: timesTimeMinute},                   // time_minute(time) => int
-	"time_second":          &objects.UserFunction{Name: "time_second", Value: timesTimeSecond},                   // time_second(time) => int
-	"time_nanosecond":      &objects.UserFunction{Name: "time_nanosecond", Value: timesTimeNanosecond},           // time_nanosecond(time) => int
-	"time_unix":            &objects.UserFunction{Name: "time_unix", Value: timesTimeUnix},                       // time_unix(time) => int
-	"time_unix_nano":       &objects.UserFunction{Name: "time_unix_nano", Value: timesTimeUnixNano},              // time_unix_nano(time) => int
-	"time_format":          &objects.UserFunction{Name: "time_format", Value: timesTimeFormat},                   // time_format(time, format) => string
-	"time_location":        &objects.UserFunction{Name: "time_location", Value: timesTimeLocation},               // time_location(time) => string
-	"time_string":          &objects.UserFunction{Name: "time_string", Value: timesTimeString},                   // time_string(time) => string
-	"is_zero":              &objects.UserFunction{Name: "is_zero", Value: timesIsZero},                           // is_zero(time) => bool
-	"to_local":             &objects.UserFunction{Name: "to_local", Value: timesToLocal},                         // to_local(time) => time
-	"to_utc":               &objects.UserFunction{Name: "to_utc", Value: timesToUTC},                             // to_utc(time) => time
-}
-
-func timesSleep(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	i1, ok := objects.ToInt64(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "int(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	time.Sleep(time.Duration(i1))
-	ret = objects.UndefinedValue
-
-	return
-}
-
-func timesParseDuration(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	dur, err := time.ParseDuration(s1)
-	if err != nil {
-		ret = wrapError(err)
-		return
-	}
-
-	ret = &objects.Int{Value: int64(dur)}
-
-	return
-}
-
-func timesSince(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Int{Value: int64(time.Since(t1))}
-
-	return
-}
-
-func timesUntil(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Int{Value: int64(time.Until(t1))}
-
-	return
-}
-
-func timesDurationHours(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	i1, ok := objects.ToInt64(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "int(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Float{Value: time.Duration(i1).Hours()}
-
-	return
-}
-
-func timesDurationMinutes(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	i1, ok := objects.ToInt64(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "int(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Float{Value: time.Duration(i1).Minutes()}
-
-	return
-}
-
-func timesDurationNanoseconds(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	i1, ok := objects.ToInt64(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "int(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Int{Value: time.Duration(i1).Nanoseconds()}
-
-	return
-}
-
-func timesDurationSeconds(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	i1, ok := objects.ToInt64(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "int(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Float{Value: time.Duration(i1).Seconds()}
-
-	return
-}
-
-func timesDurationString(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	i1, ok := objects.ToInt64(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "int(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.String{Value: time.Duration(i1).String()}
-
-	return
-}
-
-func timesMonthString(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	i1, ok := objects.ToInt64(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "int(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.String{Value: time.Month(i1).String()}
-
-	return
-}
-
-func timesDate(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 7 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	i1, ok := objects.ToInt(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "int(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-	i2, ok := objects.ToInt(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "int(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-	i3, ok := objects.ToInt(args[2])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "third",
-			Expected: "int(compatible)",
-			Found:    args[2].TypeName(),
-		}
-		return
-	}
-	i4, ok := objects.ToInt(args[3])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "fourth",
-			Expected: "int(compatible)",
-			Found:    args[3].TypeName(),
-		}
-		return
-	}
-	i5, ok := objects.ToInt(args[4])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "fifth",
-			Expected: "int(compatible)",
-			Found:    args[4].TypeName(),
-		}
-		return
-	}
-	i6, ok := objects.ToInt(args[5])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "sixth",
-			Expected: "int(compatible)",
-			Found:    args[5].TypeName(),
-		}
-		return
-	}
-	i7, ok := objects.ToInt(args[6])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "seventh",
-			Expected: "int(compatible)",
-			Found:    args[6].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Time{Value: time.Date(i1, time.Month(i2), i3, i4, i5, i6, i7, time.Now().Location())}
-
-	return
-}
-
-func timesNow(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 0 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	ret = &objects.Time{Value: time.Now()}
-
-	return
-}
-
-func timesParse(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 2 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	s1, ok := objects.ToString(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "string(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	s2, ok := objects.ToString(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "string(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	parsed, err := time.Parse(s1, s2)
-	if err != nil {
-		ret = wrapError(err)
-		return
-	}
-
-	ret = &objects.Time{Value: parsed}
-
-	return
-}
-
-func timesUnix(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 2 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	i1, ok := objects.ToInt64(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "int(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	i2, ok := objects.ToInt64(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "int(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Time{Value: time.Unix(i1, i2)}
-
-	return
-}
-
-func timesAdd(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 2 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	i2, ok := objects.ToInt64(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "int(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Time{Value: t1.Add(time.Duration(i2))}
-
-	return
-}
-
-func timesSub(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 2 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	t2, ok := objects.ToTime(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "time(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Int{Value: int64(t1.Sub(t2))}
-
-	return
-}
-
-func timesAddDate(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 4 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	i2, ok := objects.ToInt(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "int(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	i3, ok := objects.ToInt(args[2])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "third",
-			Expected: "int(compatible)",
-			Found:    args[2].TypeName(),
-		}
-		return
-	}
-
-	i4, ok := objects.ToInt(args[3])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "fourth",
-			Expected: "int(compatible)",
-			Found:    args[3].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Time{Value: t1.AddDate(i2, i3, i4)}
-
-	return
-}
-
-func timesAfter(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 2 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	t2, ok := objects.ToTime(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "time(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	if t1.After(t2) {
-		ret = objects.TrueValue
-	} else {
-		ret = objects.FalseValue
-	}
-
-	return
-}
-
-func timesBefore(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 2 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	t2, ok := objects.ToTime(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	if t1.Before(t2) {
-		ret = objects.TrueValue
-	} else {
-		ret = objects.FalseValue
-	}
-
-	return
-}
-
-func timesTimeYear(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Int{Value: int64(t1.Year())}
-
-	return
-}
-
-func timesTimeMonth(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Int{Value: int64(t1.Month())}
-
-	return
-}
-
-func timesTimeDay(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Int{Value: int64(t1.Day())}
-
-	return
-}
-
-func timesTimeWeekday(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Int{Value: int64(t1.Weekday())}
-
-	return
-}
-
-func timesTimeHour(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Int{Value: int64(t1.Hour())}
-
-	return
-}
-
-func timesTimeMinute(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Int{Value: int64(t1.Minute())}
-
-	return
-}
-
-func timesTimeSecond(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Int{Value: int64(t1.Second())}
-
-	return
-}
-
-func timesTimeNanosecond(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Int{Value: int64(t1.Nanosecond())}
-
-	return
-}
-
-func timesTimeUnix(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Int{Value: int64(t1.Unix())}
-
-	return
-}
-
-func timesTimeUnixNano(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Int{Value: int64(t1.UnixNano())}
-
-	return
-}
-
-func timesTimeFormat(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 2 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	s2, ok := objects.ToString(args[1])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "second",
-			Expected: "string(compatible)",
-			Found:    args[1].TypeName(),
-		}
-		return
-	}
-
-	s := t1.Format(s2)
-	if len(s) > tengo.MaxStringLen {
-
-		return nil, objects.ErrStringLimit
-	}
-
-	ret = &objects.String{Value: s}
-
-	return
-}
-
-func timesIsZero(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	if t1.IsZero() {
-		ret = objects.TrueValue
-	} else {
-		ret = objects.FalseValue
-	}
-
-	return
-}
-
-func timesToLocal(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Time{Value: t1.Local()}
-
-	return
-}
-
-func timesToUTC(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.Time{Value: t1.UTC()}
-
-	return
-}
-
-func timesTimeLocation(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.String{Value: t1.Location().String()}
-
-	return
-}
-
-func timesTimeString(args ...objects.Object) (ret objects.Object, err error) {
-	if len(args) != 1 {
-		err = objects.ErrWrongNumArguments
-		return
-	}
-
-	t1, ok := objects.ToTime(args[0])
-	if !ok {
-		err = objects.ErrInvalidArgumentType{
-			Name:     "first",
-			Expected: "time(compatible)",
-			Found:    args[0].TypeName(),
-		}
-		return
-	}
-
-	ret = &objects.String{Value: t1.String()}
-
-	return
-}
diff --git a/vendor/github.com/d5/tengo/tengo.go b/vendor/github.com/d5/tengo/tengo.go
deleted file mode 100644
index a883bbd7..00000000
--- a/vendor/github.com/d5/tengo/tengo.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package tengo
-
-var (
-	// MaxStringLen is the maximum byte-length for string value.
-	// Note this limit applies to all compiler/VM instances in the process.
-	MaxStringLen = 2147483647
-
-	// MaxBytesLen is the maximum length for bytes value.
-	// Note this limit applies to all compiler/VM instances in the process.
-	MaxBytesLen = 2147483647
-)
diff --git a/vendor/github.com/d5/tengo/.gitignore b/vendor/github.com/d5/tengo/v2/.gitignore
index 77738287..77738287 100644
--- a/vendor/github.com/d5/tengo/.gitignore
+++ b/vendor/github.com/d5/tengo/v2/.gitignore
diff --git a/vendor/github.com/d5/tengo/.goreleaser.yml b/vendor/github.com/d5/tengo/v2/.goreleaser.yml
index 9b1dffec..1bd14324 100644
--- a/vendor/github.com/d5/tengo/.goreleaser.yml
+++ b/vendor/github.com/d5/tengo/v2/.goreleaser.yml
@@ -11,15 +11,6 @@ builds:
       - darwin
       - linux
       - windows
-  - env:
-      - CGO_ENABLED=0
-    main: ./cmd/tengomin/main.go
-    id: tengomin
-    binary: tengomin
-    goos:
-      - darwin
-      - linux
-      - windows
 archive:
   files:
     - none*
diff --git a/vendor/github.com/d5/tengo/LICENSE b/vendor/github.com/d5/tengo/v2/LICENSE
index 2516341a..2516341a 100644
--- a/vendor/github.com/d5/tengo/LICENSE
+++ b/vendor/github.com/d5/tengo/v2/LICENSE
diff --git a/vendor/github.com/d5/tengo/Makefile b/vendor/github.com/d5/tengo/v2/Makefile
index 99daafd1..793bc129 100644
--- a/vendor/github.com/d5/tengo/Makefile
+++ b/vendor/github.com/d5/tengo/v2/Makefile
@@ -1,13 +1,10 @@
-vet:
-	go vet ./...
-
 generate:
 	go generate ./...
 
 lint:
 	golint -set_exit_status ./...
 
-test: generate vet lint
+test: generate lint
 	go test -race -cover ./...
 
 fmt:
diff --git a/vendor/github.com/d5/tengo/README.md b/vendor/github.com/d5/tengo/v2/README.md
index 6a35cfd1..92277cfe 100644
--- a/vendor/github.com/d5/tengo/README.md
+++ b/vendor/github.com/d5/tengo/v2/README.md
@@ -1,21 +1,21 @@
 <p align="center">
-  <img src="https://raw.githubusercontent.com/d5/tengolang.com/master/logo_400.png" width="200" height="200">
+  <img src="https://raw.githubusercontent.com/d5/tengolang-share/master/logo_400.png" width="200" height="200">
 </p>
 
 # The Tengo Language
 
-[![GoDoc](https://godoc.org/github.com/d5/tengo?status.svg)](https://godoc.org/github.com/d5/tengo/script)
+[![GoDoc](https://godoc.org/github.com/d5/tengo?status.svg)](https://godoc.org/github.com/d5/tengo)
 [![Go Report Card](https://goreportcard.com/badge/github.com/d5/tengo)](https://goreportcard.com/report/github.com/d5/tengo)
-[![Build Status](https://travis-ci.org/d5/tengo.svg?branch=master)](https://travis-ci.org/d5/tengo)
+[![CircleCI](https://circleci.com/gh/d5/tengo.svg?style=svg)](https://circleci.com/gh/d5/tengo)
 [![Sourcegraph](https://sourcegraph.com/github.com/d5/tengo/-/badge.svg)](https://sourcegraph.com/github.com/d5/tengo?badge)
 
 **Tengo is a small, dynamic, fast, secure script language for Go.** 
 
-Tengo is **[fast](#benchmark)** and secure because it's compiled/executed as bytecode on stack-based VM that's written in native Go.
+Tengo is **[fast](#benchmark)** and secure because it's compiled/executed as
+bytecode on stack-based VM that's written in native Go.
 
 ```golang
 /* The Tengo Language */
-
 fmt := import("fmt")
 
 each := func(seq, fn) {
@@ -31,19 +31,24 @@ fmt.println(sum(0, [1, 2, 3]))   // "6"
 fmt.println(sum("", [1, 2, 3]))  // "123"
 ```
 
-> Run this code in the [Playground](https://tengolang.com/?s=0c8d5d0d88f2795a7093d7f35ae12c3afa17bea3)
+> Test this Tengo code in the
+> [Tengo Playground](https://tengolang.com/?s=0c8d5d0d88f2795a7093d7f35ae12c3afa17bea3)
 
 ## Features
 
-- Simple and highly readable [Syntax](https://github.com/d5/tengo/blob/master/docs/tutorial.md)
+- Simple and highly readable
+  [Syntax](https://github.com/d5/tengo/blob/master/docs/tutorial.md)
   - Dynamic typing with type coercion
   - Higher-order functions and closures
   - Immutable values
-  - Garbage collection
-- [Securely Embeddable](https://github.com/d5/tengo/blob/master/docs/interoperability.md) and [Extensible](https://github.com/d5/tengo/blob/master/docs/objects.md)
+- [Securely Embeddable](https://github.com/d5/tengo/blob/master/docs/interoperability.md)
+  and [Extensible](https://github.com/d5/tengo/blob/master/docs/objects.md)
 - Compiler/runtime written in native Go _(no external deps or cgo)_
-- Executable as a [standalone](https://github.com/d5/tengo/blob/master/docs/tengo-cli.md) language / REPL
-- Use cases: rules engine, [state machine](https://github.com/d5/go-fsm), [gaming](https://github.com/d5/pbr), data pipeline, [transpiler](https://github.com/d5/tengo2lua)
+- Executable as a
+  [standalone](https://github.com/d5/tengo/blob/master/docs/tengo-cli.md)
+  language / REPL
+- Use cases: rules engine, [state machine](https://github.com/d5/go-fsm),
+  data pipeline, [transpiler](https://github.com/d5/tengo2lua)
 
 ## Benchmark
 
@@ -61,16 +66,69 @@ fmt.println(sum("", [1, 2, 3]))  // "123"
 | [otto](https://github.com/robertkrimen/otto) | `68,377ms` | `11ms` | JS Interpreter on Go |
 | [Anko](https://github.com/mattn/anko) | `92,579ms` | `18ms` | Interpreter on Go |
 
-_* [fib(35)](https://github.com/d5/tengobench/blob/master/code/fib.tengo): Fibonacci(35)_  
-_* [fibt(35)](https://github.com/d5/tengobench/blob/master/code/fibtc.tengo): [tail-call](https://en.wikipedia.org/wiki/Tail_call) version of Fibonacci(35)_  
+_* [fib(35)](https://github.com/d5/tengobench/blob/master/code/fib.tengo):
+Fibonacci(35)_  
+_* [fibt(35)](https://github.com/d5/tengobench/blob/master/code/fibtc.tengo):
+[tail-call](https://en.wikipedia.org/wiki/Tail_call) version of Fibonacci(35)_  
 _* **Go** does not read the source code from file, while all other cases do_  
 _* See [here](https://github.com/d5/tengobench) for commands/codes used_
 
+## Quick Start
+
+A simple Go example code that compiles/runs Tengo script code with some input/output values:
+
+```golang
+package main
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/d5/tengo/v2"
+)
+
+func main() {
+	// Tengo script code
+	src := `
+each := func(seq, fn) {
+    for x in seq { fn(x) }
+}
+
+sum := 0
+mul := 1
+each([a, b, c, d], func(x) {
+	sum += x
+	mul *= x
+})`
+
+	// create a new Script instance
+	script := tengo.NewScript([]byte(src))
+
+	// set values
+	_ = script.Add("a", 1)
+	_ = script.Add("b", 9)
+	_ = script.Add("c", 8)
+	_ = script.Add("d", 4)
+
+	// run the script
+	compiled, err := script.RunContext(context.Background())
+	if err != nil {
+		panic(err)
+	}
+
+	// retrieve values
+	sum := compiled.Get("sum")
+	mul := compiled.Get("mul")
+	fmt.Println(sum, mul) // "22 288"
+}
+```
+
 ## References
 
 - [Language Syntax](https://github.com/d5/tengo/blob/master/docs/tutorial.md)
 - [Object Types](https://github.com/d5/tengo/blob/master/docs/objects.md)
-- [Runtime Types](https://github.com/d5/tengo/blob/master/docs/runtime-types.md) and [Operators](https://github.com/d5/tengo/blob/master/docs/operators.md)
+- [Runtime Types](https://github.com/d5/tengo/blob/master/docs/runtime-types.md)
+  and [Operators](https://github.com/d5/tengo/blob/master/docs/operators.md)
 - [Builtin Functions](https://github.com/d5/tengo/blob/master/docs/builtins.md)
 - [Interoperability](https://github.com/d5/tengo/blob/master/docs/interoperability.md)
 - [Tengo CLI](https://github.com/d5/tengo/blob/master/docs/tengo-cli.md)
diff --git a/vendor/github.com/d5/tengo/v2/builtins.go b/vendor/github.com/d5/tengo/v2/builtins.go
new file mode 100644
index 00000000..87f7fc3d
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/builtins.go
@@ -0,0 +1,502 @@
+package tengo
+
+var builtinFuncs = []*BuiltinFunction{
+	{
+		Name:  "len",
+		Value: builtinLen,
+	},
+	{
+		Name:  "copy",
+		Value: builtinCopy,
+	},
+	{
+		Name:  "append",
+		Value: builtinAppend,
+	},
+	{
+		Name:  "string",
+		Value: builtinString,
+	},
+	{
+		Name:  "int",
+		Value: builtinInt,
+	},
+	{
+		Name:  "bool",
+		Value: builtinBool,
+	},
+	{
+		Name:  "float",
+		Value: builtinFloat,
+	},
+	{
+		Name:  "char",
+		Value: builtinChar,
+	},
+	{
+		Name:  "bytes",
+		Value: builtinBytes,
+	},
+	{
+		Name:  "time",
+		Value: builtinTime,
+	},
+	{
+		Name:  "is_int",
+		Value: builtinIsInt,
+	},
+	{
+		Name:  "is_float",
+		Value: builtinIsFloat,
+	},
+	{
+		Name:  "is_string",
+		Value: builtinIsString,
+	},
+	{
+		Name:  "is_bool",
+		Value: builtinIsBool,
+	},
+	{
+		Name:  "is_char",
+		Value: builtinIsChar,
+	},
+	{
+		Name:  "is_bytes",
+		Value: builtinIsBytes,
+	},
+	{
+		Name:  "is_array",
+		Value: builtinIsArray,
+	},
+	{
+		Name:  "is_immutable_array",
+		Value: builtinIsImmutableArray,
+	},
+	{
+		Name:  "is_map",
+		Value: builtinIsMap,
+	},
+	{
+		Name:  "is_immutable_map",
+		Value: builtinIsImmutableMap,
+	},
+	{
+		Name:  "is_iterable",
+		Value: builtinIsIterable,
+	},
+	{
+		Name:  "is_time",
+		Value: builtinIsTime,
+	},
+	{
+		Name:  "is_error",
+		Value: builtinIsError,
+	},
+	{
+		Name:  "is_undefined",
+		Value: builtinIsUndefined,
+	},
+	{
+		Name:  "is_function",
+		Value: builtinIsFunction,
+	},
+	{
+		Name:  "is_callable",
+		Value: builtinIsCallable,
+	},
+	{
+		Name:  "type_name",
+		Value: builtinTypeName,
+	},
+	{
+		Name:  "format",
+		Value: builtinFormat,
+	},
+}
+
+// GetAllBuiltinFunctions returns all builtin function objects.
+func GetAllBuiltinFunctions() []*BuiltinFunction {
+	return append([]*BuiltinFunction{}, builtinFuncs...)
+}
+
+func builtinTypeName(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	return &String{Value: args[0].TypeName()}, nil
+}
+
+func builtinIsString(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*String); ok {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsInt(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*Int); ok {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsFloat(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*Float); ok {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsBool(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*Bool); ok {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsChar(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*Char); ok {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsBytes(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*Bytes); ok {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsArray(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*Array); ok {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsImmutableArray(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*ImmutableArray); ok {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsMap(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*Map); ok {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsImmutableMap(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*ImmutableMap); ok {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsTime(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*Time); ok {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsError(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*Error); ok {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsUndefined(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if args[0] == UndefinedValue {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsFunction(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	switch args[0].(type) {
+	case *CompiledFunction:
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsCallable(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if args[0].CanCall() {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+func builtinIsIterable(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if args[0].CanIterate() {
+		return TrueValue, nil
+	}
+	return FalseValue, nil
+}
+
+// len(obj object) => int
+func builtinLen(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	switch arg := args[0].(type) {
+	case *Array:
+		return &Int{Value: int64(len(arg.Value))}, nil
+	case *ImmutableArray:
+		return &Int{Value: int64(len(arg.Value))}, nil
+	case *String:
+		return &Int{Value: int64(len(arg.Value))}, nil
+	case *Bytes:
+		return &Int{Value: int64(len(arg.Value))}, nil
+	case *Map:
+		return &Int{Value: int64(len(arg.Value))}, nil
+	case *ImmutableMap:
+		return &Int{Value: int64(len(arg.Value))}, nil
+	default:
+		return nil, ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "array/string/bytes/map",
+			Found:    arg.TypeName(),
+		}
+	}
+}
+
+func builtinFormat(args ...Object) (Object, error) {
+	numArgs := len(args)
+	if numArgs == 0 {
+		return nil, ErrWrongNumArguments
+	}
+	format, ok := args[0].(*String)
+	if !ok {
+		return nil, ErrInvalidArgumentType{
+			Name:     "format",
+			Expected: "string",
+			Found:    args[0].TypeName(),
+		}
+	}
+	if numArgs == 1 {
+		// okay to return 'format' directly as String is immutable
+		return format, nil
+	}
+	s, err := Format(format.Value, args[1:]...)
+	if err != nil {
+		return nil, err
+	}
+	return &String{Value: s}, nil
+}
+
+func builtinCopy(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	return args[0].Copy(), nil
+}
+
+func builtinString(args ...Object) (Object, error) {
+	argsLen := len(args)
+	if !(argsLen == 1 || argsLen == 2) {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*String); ok {
+		return args[0], nil
+	}
+	v, ok := ToString(args[0])
+	if ok {
+		if len(v) > MaxStringLen {
+			return nil, ErrStringLimit
+		}
+		return &String{Value: v}, nil
+	}
+	if argsLen == 2 {
+		return args[1], nil
+	}
+	return UndefinedValue, nil
+}
+
+func builtinInt(args ...Object) (Object, error) {
+	argsLen := len(args)
+	if !(argsLen == 1 || argsLen == 2) {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*Int); ok {
+		return args[0], nil
+	}
+	v, ok := ToInt64(args[0])
+	if ok {
+		return &Int{Value: v}, nil
+	}
+	if argsLen == 2 {
+		return args[1], nil
+	}
+	return UndefinedValue, nil
+}
+
+func builtinFloat(args ...Object) (Object, error) {
+	argsLen := len(args)
+	if !(argsLen == 1 || argsLen == 2) {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*Float); ok {
+		return args[0], nil
+	}
+	v, ok := ToFloat64(args[0])
+	if ok {
+		return &Float{Value: v}, nil
+	}
+	if argsLen == 2 {
+		return args[1], nil
+	}
+	return UndefinedValue, nil
+}
+
+func builtinBool(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*Bool); ok {
+		return args[0], nil
+	}
+	v, ok := ToBool(args[0])
+	if ok {
+		if v {
+			return TrueValue, nil
+		}
+		return FalseValue, nil
+	}
+	return UndefinedValue, nil
+}
+
+func builtinChar(args ...Object) (Object, error) {
+	argsLen := len(args)
+	if !(argsLen == 1 || argsLen == 2) {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*Char); ok {
+		return args[0], nil
+	}
+	v, ok := ToRune(args[0])
+	if ok {
+		return &Char{Value: v}, nil
+	}
+	if argsLen == 2 {
+		return args[1], nil
+	}
+	return UndefinedValue, nil
+}
+
+func builtinBytes(args ...Object) (Object, error) {
+	argsLen := len(args)
+	if !(argsLen == 1 || argsLen == 2) {
+		return nil, ErrWrongNumArguments
+	}
+
+	// bytes(N) => create a new bytes with given size N
+	if n, ok := args[0].(*Int); ok {
+		if n.Value > int64(MaxBytesLen) {
+			return nil, ErrBytesLimit
+		}
+		return &Bytes{Value: make([]byte, int(n.Value))}, nil
+	}
+	v, ok := ToByteSlice(args[0])
+	if ok {
+		if len(v) > MaxBytesLen {
+			return nil, ErrBytesLimit
+		}
+		return &Bytes{Value: v}, nil
+	}
+	if argsLen == 2 {
+		return args[1], nil
+	}
+	return UndefinedValue, nil
+}
+
+func builtinTime(args ...Object) (Object, error) {
+	argsLen := len(args)
+	if !(argsLen == 1 || argsLen == 2) {
+		return nil, ErrWrongNumArguments
+	}
+	if _, ok := args[0].(*Time); ok {
+		return args[0], nil
+	}
+	v, ok := ToTime(args[0])
+	if ok {
+		return &Time{Value: v}, nil
+	}
+	if argsLen == 2 {
+		return args[1], nil
+	}
+	return UndefinedValue, nil
+}
+
+// append(arr, items...)
+func builtinAppend(args ...Object) (Object, error) {
+	if len(args) < 2 {
+		return nil, ErrWrongNumArguments
+	}
+	switch arg := args[0].(type) {
+	case *Array:
+		return &Array{Value: append(arg.Value, args[1:]...)}, nil
+	case *ImmutableArray:
+		return &Array{Value: append(arg.Value, args[1:]...)}, nil
+	default:
+		return nil, ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "array",
+			Found:    arg.TypeName(),
+		}
+	}
+}
diff --git a/vendor/github.com/d5/tengo/v2/bytecode.go b/vendor/github.com/d5/tengo/v2/bytecode.go
new file mode 100644
index 00000000..cfd0d0b5
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/bytecode.go
@@ -0,0 +1,292 @@
+package tengo
+
+import (
+	"encoding/gob"
+	"fmt"
+	"io"
+	"reflect"
+
+	"github.com/d5/tengo/v2/parser"
+)
+
+// Bytecode is a compiled instructions and constants.
+type Bytecode struct {
+	FileSet      *parser.SourceFileSet
+	MainFunction *CompiledFunction
+	Constants    []Object
+}
+
+// Encode writes Bytecode data to the writer.
+func (b *Bytecode) Encode(w io.Writer) error {
+	enc := gob.NewEncoder(w)
+	if err := enc.Encode(b.FileSet); err != nil {
+		return err
+	}
+	if err := enc.Encode(b.MainFunction); err != nil {
+		return err
+	}
+	return enc.Encode(b.Constants)
+}
+
+// CountObjects returns the number of objects found in Constants.
+func (b *Bytecode) CountObjects() int {
+	n := 0
+	for _, c := range b.Constants {
+		n += CountObjects(c)
+	}
+	return n
+}
+
+// FormatInstructions returns human readable string representations of
+// compiled instructions.
+func (b *Bytecode) FormatInstructions() []string {
+	return FormatInstructions(b.MainFunction.Instructions, 0)
+}
+
+// FormatConstants returns human readable string representations of
+// compiled constants.
+func (b *Bytecode) FormatConstants() (output []string) {
+	for cidx, cn := range b.Constants {
+		switch cn := cn.(type) {
+		case *CompiledFunction:
+			output = append(output, fmt.Sprintf(
+				"[% 3d] (Compiled Function|%p)", cidx, &cn))
+			for _, l := range FormatInstructions(cn.Instructions, 0) {
+				output = append(output, fmt.Sprintf("     %s", l))
+			}
+		default:
+			output = append(output, fmt.Sprintf("[% 3d] %s (%s|%p)",
+				cidx, cn, reflect.TypeOf(cn).Elem().Name(), &cn))
+		}
+	}
+	return
+}
+
+// Decode reads Bytecode data from the reader.
+func (b *Bytecode) Decode(r io.Reader, modules *ModuleMap) error {
+	if modules == nil {
+		modules = NewModuleMap()
+	}
+
+	dec := gob.NewDecoder(r)
+	if err := dec.Decode(&b.FileSet); err != nil {
+		return err
+	}
+	// TODO: files in b.FileSet.File does not have their 'set' field properly
+	//  set to b.FileSet as it's private field and not serialized by gob
+	//  encoder/decoder.
+	if err := dec.Decode(&b.MainFunction); err != nil {
+		return err
+	}
+	if err := dec.Decode(&b.Constants); err != nil {
+		return err
+	}
+	for i, v := range b.Constants {
+		fv, err := fixDecodedObject(v, modules)
+		if err != nil {
+			return err
+		}
+		b.Constants[i] = fv
+	}
+	return nil
+}
+
+// RemoveDuplicates finds and remove the duplicate values in Constants.
+// Note this function mutates Bytecode.
+func (b *Bytecode) RemoveDuplicates() {
+	var deduped []Object
+
+	indexMap := make(map[int]int) // mapping from old constant index to new index
+	ints := make(map[int64]int)
+	strings := make(map[string]int)
+	floats := make(map[float64]int)
+	chars := make(map[rune]int)
+	immutableMaps := make(map[string]int) // for modules
+
+	for curIdx, c := range b.Constants {
+		switch c := c.(type) {
+		case *CompiledFunction:
+			// add to deduped list
+			indexMap[curIdx] = len(deduped)
+			deduped = append(deduped, c)
+		case *ImmutableMap:
+			modName := inferModuleName(c)
+			newIdx, ok := immutableMaps[modName]
+			if modName != "" && ok {
+				indexMap[curIdx] = newIdx
+			} else {
+				newIdx = len(deduped)
+				immutableMaps[modName] = newIdx
+				indexMap[curIdx] = newIdx
+				deduped = append(deduped, c)
+			}
+		case *Int:
+			if newIdx, ok := ints[c.Value]; ok {
+				indexMap[curIdx] = newIdx
+			} else {
+				newIdx = len(deduped)
+				ints[c.Value] = newIdx
+				indexMap[curIdx] = newIdx
+				deduped = append(deduped, c)
+			}
+		case *String:
+			if newIdx, ok := strings[c.Value]; ok {
+				indexMap[curIdx] = newIdx
+			} else {
+				newIdx = len(deduped)
+				strings[c.Value] = newIdx
+				indexMap[curIdx] = newIdx
+				deduped = append(deduped, c)
+			}
+		case *Float:
+			if newIdx, ok := floats[c.Value]; ok {
+				indexMap[curIdx] = newIdx
+			} else {
+				newIdx = len(deduped)
+				floats[c.Value] = newIdx
+				indexMap[curIdx] = newIdx
+				deduped = append(deduped, c)
+			}
+		case *Char:
+			if newIdx, ok := chars[c.Value]; ok {
+				indexMap[curIdx] = newIdx
+			} else {
+				newIdx = len(deduped)
+				chars[c.Value] = newIdx
+				indexMap[curIdx] = newIdx
+				deduped = append(deduped, c)
+			}
+		default:
+			panic(fmt.Errorf("unsupported top-level constant type: %s",
+				c.TypeName()))
+		}
+	}
+
+	// replace with de-duplicated constants
+	b.Constants = deduped
+
+	// update CONST instructions with new indexes
+	// main function
+	updateConstIndexes(b.MainFunction.Instructions, indexMap)
+	// other compiled functions in constants
+	for _, c := range b.Constants {
+		switch c := c.(type) {
+		case *CompiledFunction:
+			updateConstIndexes(c.Instructions, indexMap)
+		}
+	}
+}
+
+func fixDecodedObject(
+	o Object,
+	modules *ModuleMap,
+) (Object, error) {
+	switch o := o.(type) {
+	case *Bool:
+		if o.IsFalsy() {
+			return FalseValue, nil
+		}
+		return TrueValue, nil
+	case *Undefined:
+		return UndefinedValue, nil
+	case *Array:
+		for i, v := range o.Value {
+			fv, err := fixDecodedObject(v, modules)
+			if err != nil {
+				return nil, err
+			}
+			o.Value[i] = fv
+		}
+	case *ImmutableArray:
+		for i, v := range o.Value {
+			fv, err := fixDecodedObject(v, modules)
+			if err != nil {
+				return nil, err
+			}
+			o.Value[i] = fv
+		}
+	case *Map:
+		for k, v := range o.Value {
+			fv, err := fixDecodedObject(v, modules)
+			if err != nil {
+				return nil, err
+			}
+			o.Value[k] = fv
+		}
+	case *ImmutableMap:
+		modName := inferModuleName(o)
+		if mod := modules.GetBuiltinModule(modName); mod != nil {
+			return mod.AsImmutableMap(modName), nil
+		}
+
+		for k, v := range o.Value {
+			// encoding of user function not supported
+			if _, isUserFunction := v.(*UserFunction); isUserFunction {
+				return nil, fmt.Errorf("user function not decodable")
+			}
+
+			fv, err := fixDecodedObject(v, modules)
+			if err != nil {
+				return nil, err
+			}
+			o.Value[k] = fv
+		}
+	}
+	return o, nil
+}
+
+func updateConstIndexes(insts []byte, indexMap map[int]int) {
+	i := 0
+	for i < len(insts) {
+		op := insts[i]
+		numOperands := parser.OpcodeOperands[op]
+		_, read := parser.ReadOperands(numOperands, insts[i+1:])
+
+		switch op {
+		case parser.OpConstant:
+			curIdx := int(insts[i+2]) | int(insts[i+1])<<8
+			newIdx, ok := indexMap[curIdx]
+			if !ok {
+				panic(fmt.Errorf("constant index not found: %d", curIdx))
+			}
+			copy(insts[i:], MakeInstruction(op, newIdx))
+		case parser.OpClosure:
+			curIdx := int(insts[i+2]) | int(insts[i+1])<<8
+			numFree := int(insts[i+3])
+			newIdx, ok := indexMap[curIdx]
+			if !ok {
+				panic(fmt.Errorf("constant index not found: %d", curIdx))
+			}
+			copy(insts[i:], MakeInstruction(op, newIdx, numFree))
+		}
+
+		i += 1 + read
+	}
+}
+
+func inferModuleName(mod *ImmutableMap) string {
+	if modName, ok := mod.Value["__module_name__"].(*String); ok {
+		return modName.Value
+	}
+	return ""
+}
+
+func init() {
+	gob.Register(&parser.SourceFileSet{})
+	gob.Register(&parser.SourceFile{})
+	gob.Register(&Array{})
+	gob.Register(&Bool{})
+	gob.Register(&Bytes{})
+	gob.Register(&Char{})
+	gob.Register(&CompiledFunction{})
+	gob.Register(&Error{})
+	gob.Register(&Float{})
+	gob.Register(&ImmutableArray{})
+	gob.Register(&ImmutableMap{})
+	gob.Register(&Int{})
+	gob.Register(&Map{})
+	gob.Register(&String{})
+	gob.Register(&Time{})
+	gob.Register(&Undefined{})
+	gob.Register(&UserFunction{})
+}
diff --git a/vendor/github.com/d5/tengo/v2/compiler.go b/vendor/github.com/d5/tengo/v2/compiler.go
new file mode 100644
index 00000000..eb686ed6
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/compiler.go
@@ -0,0 +1,1312 @@
+package tengo
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"path/filepath"
+	"reflect"
+	"strings"
+
+	"github.com/d5/tengo/v2/parser"
+	"github.com/d5/tengo/v2/token"
+)
+
+// compilationScope represents a compiled instructions and the last two
+// instructions that were emitted.
+type compilationScope struct {
+	Instructions []byte
+	SymbolInit   map[string]bool
+	SourceMap    map[int]parser.Pos
+}
+
+// loop represents a loop construct that the compiler uses to track the current
+// loop.
+type loop struct {
+	Continues []int
+	Breaks    []int
+}
+
+// CompilerError represents a compiler error.
+type CompilerError struct {
+	FileSet *parser.SourceFileSet
+	Node    parser.Node
+	Err     error
+}
+
+func (e *CompilerError) Error() string {
+	filePos := e.FileSet.Position(e.Node.Pos())
+	return fmt.Sprintf("Compile Error: %s\n\tat %s", e.Err.Error(), filePos)
+}
+
+// Compiler compiles the AST into a bytecode.
+type Compiler struct {
+	file            *parser.SourceFile
+	parent          *Compiler
+	modulePath      string
+	constants       []Object
+	symbolTable     *SymbolTable
+	scopes          []compilationScope
+	scopeIndex      int
+	modules         *ModuleMap
+	compiledModules map[string]*CompiledFunction
+	allowFileImport bool
+	loops           []*loop
+	loopIndex       int
+	trace           io.Writer
+	indent          int
+}
+
+// NewCompiler creates a Compiler.
+func NewCompiler(
+	file *parser.SourceFile,
+	symbolTable *SymbolTable,
+	constants []Object,
+	modules *ModuleMap,
+	trace io.Writer,
+) *Compiler {
+	mainScope := compilationScope{
+		SymbolInit: make(map[string]bool),
+		SourceMap:  make(map[int]parser.Pos),
+	}
+
+	// symbol table
+	if symbolTable == nil {
+		symbolTable = NewSymbolTable()
+	}
+
+	// add builtin functions to the symbol table
+	for idx, fn := range builtinFuncs {
+		symbolTable.DefineBuiltin(idx, fn.Name)
+	}
+
+	// builtin modules
+	if modules == nil {
+		modules = NewModuleMap()
+	}
+
+	return &Compiler{
+		file:            file,
+		symbolTable:     symbolTable,
+		constants:       constants,
+		scopes:          []compilationScope{mainScope},
+		scopeIndex:      0,
+		loopIndex:       -1,
+		trace:           trace,
+		modules:         modules,
+		compiledModules: make(map[string]*CompiledFunction),
+	}
+}
+
+// Compile compiles the AST node.
+func (c *Compiler) Compile(node parser.Node) error {
+	if c.trace != nil {
+		if node != nil {
+			defer untracec(tracec(c, fmt.Sprintf("%s (%s)",
+				node.String(), reflect.TypeOf(node).Elem().Name())))
+		} else {
+			defer untracec(tracec(c, "<nil>"))
+		}
+	}
+
+	switch node := node.(type) {
+	case *parser.File:
+		for _, stmt := range node.Stmts {
+			if err := c.Compile(stmt); err != nil {
+				return err
+			}
+		}
+	case *parser.ExprStmt:
+		if err := c.Compile(node.Expr); err != nil {
+			return err
+		}
+		c.emit(node, parser.OpPop)
+	case *parser.IncDecStmt:
+		op := token.AddAssign
+		if node.Token == token.Dec {
+			op = token.SubAssign
+		}
+		return c.compileAssign(node, []parser.Expr{node.Expr},
+			[]parser.Expr{&parser.IntLit{Value: 1}}, op)
+	case *parser.ParenExpr:
+		if err := c.Compile(node.Expr); err != nil {
+			return err
+		}
+	case *parser.BinaryExpr:
+		if node.Token == token.LAnd || node.Token == token.LOr {
+			return c.compileLogical(node)
+		}
+		if node.Token == token.Less {
+			if err := c.Compile(node.RHS); err != nil {
+				return err
+			}
+			if err := c.Compile(node.LHS); err != nil {
+				return err
+			}
+			c.emit(node, parser.OpBinaryOp, int(token.Greater))
+			return nil
+		} else if node.Token == token.LessEq {
+			if err := c.Compile(node.RHS); err != nil {
+				return err
+			}
+			if err := c.Compile(node.LHS); err != nil {
+				return err
+			}
+			c.emit(node, parser.OpBinaryOp, int(token.GreaterEq))
+			return nil
+		}
+		if err := c.Compile(node.LHS); err != nil {
+			return err
+		}
+		if err := c.Compile(node.RHS); err != nil {
+			return err
+		}
+
+		switch node.Token {
+		case token.Add:
+			c.emit(node, parser.OpBinaryOp, int(token.Add))
+		case token.Sub:
+			c.emit(node, parser.OpBinaryOp, int(token.Sub))
+		case token.Mul:
+			c.emit(node, parser.OpBinaryOp, int(token.Mul))
+		case token.Quo:
+			c.emit(node, parser.OpBinaryOp, int(token.Quo))
+		case token.Rem:
+			c.emit(node, parser.OpBinaryOp, int(token.Rem))
+		case token.Greater:
+			c.emit(node, parser.OpBinaryOp, int(token.Greater))
+		case token.GreaterEq:
+			c.emit(node, parser.OpBinaryOp, int(token.GreaterEq))
+		case token.Equal:
+			c.emit(node, parser.OpEqual)
+		case token.NotEqual:
+			c.emit(node, parser.OpNotEqual)
+		case token.And:
+			c.emit(node, parser.OpBinaryOp, int(token.And))
+		case token.Or:
+			c.emit(node, parser.OpBinaryOp, int(token.Or))
+		case token.Xor:
+			c.emit(node, parser.OpBinaryOp, int(token.Xor))
+		case token.AndNot:
+			c.emit(node, parser.OpBinaryOp, int(token.AndNot))
+		case token.Shl:
+			c.emit(node, parser.OpBinaryOp, int(token.Shl))
+		case token.Shr:
+			c.emit(node, parser.OpBinaryOp, int(token.Shr))
+		default:
+			return c.errorf(node, "invalid binary operator: %s",
+				node.Token.String())
+		}
+	case *parser.IntLit:
+		c.emit(node, parser.OpConstant,
+			c.addConstant(&Int{Value: node.Value}))
+	case *parser.FloatLit:
+		c.emit(node, parser.OpConstant,
+			c.addConstant(&Float{Value: node.Value}))
+	case *parser.BoolLit:
+		if node.Value {
+			c.emit(node, parser.OpTrue)
+		} else {
+			c.emit(node, parser.OpFalse)
+		}
+	case *parser.StringLit:
+		if len(node.Value) > MaxStringLen {
+			return c.error(node, ErrStringLimit)
+		}
+		c.emit(node, parser.OpConstant,
+			c.addConstant(&String{Value: node.Value}))
+	case *parser.CharLit:
+		c.emit(node, parser.OpConstant,
+			c.addConstant(&Char{Value: node.Value}))
+	case *parser.UndefinedLit:
+		c.emit(node, parser.OpNull)
+	case *parser.UnaryExpr:
+		if err := c.Compile(node.Expr); err != nil {
+			return err
+		}
+
+		switch node.Token {
+		case token.Not:
+			c.emit(node, parser.OpLNot)
+		case token.Sub:
+			c.emit(node, parser.OpMinus)
+		case token.Xor:
+			c.emit(node, parser.OpBComplement)
+		case token.Add:
+			// do nothing?
+		default:
+			return c.errorf(node,
+				"invalid unary operator: %s", node.Token.String())
+		}
+	case *parser.IfStmt:
+		// open new symbol table for the statement
+		c.symbolTable = c.symbolTable.Fork(true)
+		defer func() {
+			c.symbolTable = c.symbolTable.Parent(false)
+		}()
+
+		if node.Init != nil {
+			if err := c.Compile(node.Init); err != nil {
+				return err
+			}
+		}
+		if err := c.Compile(node.Cond); err != nil {
+			return err
+		}
+
+		// first jump placeholder
+		jumpPos1 := c.emit(node, parser.OpJumpFalsy, 0)
+		if err := c.Compile(node.Body); err != nil {
+			return err
+		}
+		if node.Else != nil {
+			// second jump placeholder
+			jumpPos2 := c.emit(node, parser.OpJump, 0)
+
+			// update first jump offset
+			curPos := len(c.currentInstructions())
+			c.changeOperand(jumpPos1, curPos)
+			if err := c.Compile(node.Else); err != nil {
+				return err
+			}
+
+			// update second jump offset
+			curPos = len(c.currentInstructions())
+			c.changeOperand(jumpPos2, curPos)
+		} else {
+			// update first jump offset
+			curPos := len(c.currentInstructions())
+			c.changeOperand(jumpPos1, curPos)
+		}
+	case *parser.ForStmt:
+		return c.compileForStmt(node)
+	case *parser.ForInStmt:
+		return c.compileForInStmt(node)
+	case *parser.BranchStmt:
+		if node.Token == token.Break {
+			curLoop := c.currentLoop()
+			if curLoop == nil {
+				return c.errorf(node, "break not allowed outside loop")
+			}
+			pos := c.emit(node, parser.OpJump, 0)
+			curLoop.Breaks = append(curLoop.Breaks, pos)
+		} else if node.Token == token.Continue {
+			curLoop := c.currentLoop()
+			if curLoop == nil {
+				return c.errorf(node, "continue not allowed outside loop")
+			}
+			pos := c.emit(node, parser.OpJump, 0)
+			curLoop.Continues = append(curLoop.Continues, pos)
+		} else {
+			panic(fmt.Errorf("invalid branch statement: %s",
+				node.Token.String()))
+		}
+	case *parser.BlockStmt:
+		if len(node.Stmts) == 0 {
+			return nil
+		}
+
+		c.symbolTable = c.symbolTable.Fork(true)
+		defer func() {
+			c.symbolTable = c.symbolTable.Parent(false)
+		}()
+
+		for _, stmt := range node.Stmts {
+			if err := c.Compile(stmt); err != nil {
+				return err
+			}
+		}
+	case *parser.AssignStmt:
+		err := c.compileAssign(node, node.LHS, node.RHS, node.Token)
+		if err != nil {
+			return err
+		}
+	case *parser.Ident:
+		symbol, _, ok := c.symbolTable.Resolve(node.Name)
+		if !ok {
+			return c.errorf(node, "unresolved reference '%s'", node.Name)
+		}
+
+		switch symbol.Scope {
+		case ScopeGlobal:
+			c.emit(node, parser.OpGetGlobal, symbol.Index)
+		case ScopeLocal:
+			c.emit(node, parser.OpGetLocal, symbol.Index)
+		case ScopeBuiltin:
+			c.emit(node, parser.OpGetBuiltin, symbol.Index)
+		case ScopeFree:
+			c.emit(node, parser.OpGetFree, symbol.Index)
+		}
+	case *parser.ArrayLit:
+		for _, elem := range node.Elements {
+			if err := c.Compile(elem); err != nil {
+				return err
+			}
+		}
+		c.emit(node, parser.OpArray, len(node.Elements))
+	case *parser.MapLit:
+		for _, elt := range node.Elements {
+			// key
+			if len(elt.Key) > MaxStringLen {
+				return c.error(node, ErrStringLimit)
+			}
+			c.emit(node, parser.OpConstant,
+				c.addConstant(&String{Value: elt.Key}))
+
+			// value
+			if err := c.Compile(elt.Value); err != nil {
+				return err
+			}
+		}
+		c.emit(node, parser.OpMap, len(node.Elements)*2)
+
+	case *parser.SelectorExpr: // selector on RHS side
+		if err := c.Compile(node.Expr); err != nil {
+			return err
+		}
+		if err := c.Compile(node.Sel); err != nil {
+			return err
+		}
+		c.emit(node, parser.OpIndex)
+	case *parser.IndexExpr:
+		if err := c.Compile(node.Expr); err != nil {
+			return err
+		}
+		if err := c.Compile(node.Index); err != nil {
+			return err
+		}
+		c.emit(node, parser.OpIndex)
+	case *parser.SliceExpr:
+		if err := c.Compile(node.Expr); err != nil {
+			return err
+		}
+		if node.Low != nil {
+			if err := c.Compile(node.Low); err != nil {
+				return err
+			}
+		} else {
+			c.emit(node, parser.OpNull)
+		}
+		if node.High != nil {
+			if err := c.Compile(node.High); err != nil {
+				return err
+			}
+		} else {
+			c.emit(node, parser.OpNull)
+		}
+		c.emit(node, parser.OpSliceIndex)
+	case *parser.FuncLit:
+		c.enterScope()
+
+		for _, p := range node.Type.Params.List {
+			s := c.symbolTable.Define(p.Name)
+
+			// function arguments is not assigned directly.
+			s.LocalAssigned = true
+		}
+
+		if err := c.Compile(node.Body); err != nil {
+			return err
+		}
+
+		// code optimization
+		c.optimizeFunc(node)
+
+		freeSymbols := c.symbolTable.FreeSymbols()
+		numLocals := c.symbolTable.MaxSymbols()
+		instructions, sourceMap := c.leaveScope()
+
+		for _, s := range freeSymbols {
+			switch s.Scope {
+			case ScopeLocal:
+				if !s.LocalAssigned {
+					// Here, the closure is capturing a local variable that's
+					// not yet assigned its value. One example is a local
+					// recursive function:
+					//
+					//   func() {
+					//     foo := func(x) {
+					//       // ..
+					//       return foo(x-1)
+					//     }
+					//   }
+					//
+					// which translate into
+					//
+					//   0000 GETL    0
+					//   0002 CLOSURE ?     1
+					//   0006 DEFL    0
+					//
+					// . So the local variable (0) is being captured before
+					// it's assigned the value.
+					//
+					// Solution is to transform the code into something like
+					// this:
+					//
+					//   func() {
+					//     foo := undefined
+					//     foo = func(x) {
+					//       // ..
+					//       return foo(x-1)
+					//     }
+					//   }
+					//
+					// that is equivalent to
+					//
+					//   0000 NULL
+					//   0001 DEFL    0
+					//   0003 GETL    0
+					//   0005 CLOSURE ?     1
+					//   0009 SETL    0
+					//
+					c.emit(node, parser.OpNull)
+					c.emit(node, parser.OpDefineLocal, s.Index)
+					s.LocalAssigned = true
+				}
+				c.emit(node, parser.OpGetLocalPtr, s.Index)
+			case ScopeFree:
+				c.emit(node, parser.OpGetFreePtr, s.Index)
+			}
+		}
+
+		compiledFunction := &CompiledFunction{
+			Instructions:  instructions,
+			NumLocals:     numLocals,
+			NumParameters: len(node.Type.Params.List),
+			VarArgs:       node.Type.Params.VarArgs,
+			SourceMap:     sourceMap,
+		}
+		if len(freeSymbols) > 0 {
+			c.emit(node, parser.OpClosure,
+				c.addConstant(compiledFunction), len(freeSymbols))
+		} else {
+			c.emit(node, parser.OpConstant, c.addConstant(compiledFunction))
+		}
+	case *parser.ReturnStmt:
+		if c.symbolTable.Parent(true) == nil {
+			// outside the function
+			return c.errorf(node, "return not allowed outside function")
+		}
+
+		if node.Result == nil {
+			c.emit(node, parser.OpReturn, 0)
+		} else {
+			if err := c.Compile(node.Result); err != nil {
+				return err
+			}
+			c.emit(node, parser.OpReturn, 1)
+		}
+	case *parser.CallExpr:
+		if err := c.Compile(node.Func); err != nil {
+			return err
+		}
+		for _, arg := range node.Args {
+			if err := c.Compile(arg); err != nil {
+				return err
+			}
+		}
+		c.emit(node, parser.OpCall, len(node.Args))
+	case *parser.ImportExpr:
+		if node.ModuleName == "" {
+			return c.errorf(node, "empty module name")
+		}
+
+		if mod := c.modules.Get(node.ModuleName); mod != nil {
+			v, err := mod.Import(node.ModuleName)
+			if err != nil {
+				return err
+			}
+
+			switch v := v.(type) {
+			case []byte: // module written in Tengo
+				compiled, err := c.compileModule(node,
+					node.ModuleName, node.ModuleName, v)
+				if err != nil {
+					return err
+				}
+				c.emit(node, parser.OpConstant, c.addConstant(compiled))
+				c.emit(node, parser.OpCall, 0)
+			case Object: // builtin module
+				c.emit(node, parser.OpConstant, c.addConstant(v))
+			default:
+				panic(fmt.Errorf("invalid import value type: %T", v))
+			}
+		} else if c.allowFileImport {
+			moduleName := node.ModuleName
+			if !strings.HasSuffix(moduleName, ".tengo") {
+				moduleName += ".tengo"
+			}
+
+			modulePath, err := filepath.Abs(moduleName)
+			if err != nil {
+				return c.errorf(node, "module file path error: %s",
+					err.Error())
+			}
+
+			if err := c.checkCyclicImports(node, modulePath); err != nil {
+				return err
+			}
+
+			moduleSrc, err := ioutil.ReadFile(moduleName)
+			if err != nil {
+				return c.errorf(node, "module file read error: %s",
+					err.Error())
+			}
+
+			compiled, err := c.compileModule(node,
+				moduleName, modulePath, moduleSrc)
+			if err != nil {
+				return err
+			}
+			c.emit(node, parser.OpConstant, c.addConstant(compiled))
+			c.emit(node, parser.OpCall, 0)
+		} else {
+			return c.errorf(node, "module '%s' not found", node.ModuleName)
+		}
+	case *parser.ExportStmt:
+		// export statement must be in top-level scope
+		if c.scopeIndex != 0 {
+			return c.errorf(node, "export not allowed inside function")
+		}
+
+		// export statement is simply ignore when compiling non-module code
+		if c.parent == nil {
+			break
+		}
+		if err := c.Compile(node.Result); err != nil {
+			return err
+		}
+		c.emit(node, parser.OpImmutable)
+		c.emit(node, parser.OpReturn, 1)
+	case *parser.ErrorExpr:
+		if err := c.Compile(node.Expr); err != nil {
+			return err
+		}
+		c.emit(node, parser.OpError)
+	case *parser.ImmutableExpr:
+		if err := c.Compile(node.Expr); err != nil {
+			return err
+		}
+		c.emit(node, parser.OpImmutable)
+	case *parser.CondExpr:
+		if err := c.Compile(node.Cond); err != nil {
+			return err
+		}
+
+		// first jump placeholder
+		jumpPos1 := c.emit(node, parser.OpJumpFalsy, 0)
+		if err := c.Compile(node.True); err != nil {
+			return err
+		}
+
+		// second jump placeholder
+		jumpPos2 := c.emit(node, parser.OpJump, 0)
+
+		// update first jump offset
+		curPos := len(c.currentInstructions())
+		c.changeOperand(jumpPos1, curPos)
+		if err := c.Compile(node.False); err != nil {
+			return err
+		}
+
+		// update second jump offset
+		curPos = len(c.currentInstructions())
+		c.changeOperand(jumpPos2, curPos)
+	}
+	return nil
+}
+
+// Bytecode returns a compiled bytecode.
+func (c *Compiler) Bytecode() *Bytecode {
+	return &Bytecode{
+		FileSet: c.file.Set(),
+		MainFunction: &CompiledFunction{
+			Instructions: append(c.currentInstructions(), parser.OpSuspend),
+			SourceMap:    c.currentSourceMap(),
+		},
+		Constants: c.constants,
+	}
+}
+
+// EnableFileImport enables or disables module loading from local files.
+// Local file modules are disabled by default.
+func (c *Compiler) EnableFileImport(enable bool) {
+	c.allowFileImport = enable
+}
+
+func (c *Compiler) compileAssign(
+	node parser.Node,
+	lhs, rhs []parser.Expr,
+	op token.Token,
+) error {
+	numLHS, numRHS := len(lhs), len(rhs)
+	if numLHS > 1 || numRHS > 1 {
+		return c.errorf(node, "tuple assignment not allowed")
+	}
+
+	// resolve and compile left-hand side
+	ident, selectors := resolveAssignLHS(lhs[0])
+	numSel := len(selectors)
+
+	if op == token.Define && numSel > 0 {
+		// using selector on new variable does not make sense
+		return c.errorf(node, "operator ':=' not allowed with selector")
+	}
+
+	symbol, depth, exists := c.symbolTable.Resolve(ident)
+	if op == token.Define {
+		if depth == 0 && exists {
+			return c.errorf(node, "'%s' redeclared in this block", ident)
+		}
+		symbol = c.symbolTable.Define(ident)
+	} else {
+		if !exists {
+			return c.errorf(node, "unresolved reference '%s'", ident)
+		}
+	}
+
+	// +=, -=, *=, /=
+	if op != token.Assign && op != token.Define {
+		if err := c.Compile(lhs[0]); err != nil {
+			return err
+		}
+	}
+
+	// compile RHSs
+	for _, expr := range rhs {
+		if err := c.Compile(expr); err != nil {
+			return err
+		}
+	}
+
+	switch op {
+	case token.AddAssign:
+		c.emit(node, parser.OpBinaryOp, int(token.Add))
+	case token.SubAssign:
+		c.emit(node, parser.OpBinaryOp, int(token.Sub))
+	case token.MulAssign:
+		c.emit(node, parser.OpBinaryOp, int(token.Mul))
+	case token.QuoAssign:
+		c.emit(node, parser.OpBinaryOp, int(token.Quo))
+	case token.RemAssign:
+		c.emit(node, parser.OpBinaryOp, int(token.Rem))
+	case token.AndAssign:
+		c.emit(node, parser.OpBinaryOp, int(token.And))
+	case token.OrAssign:
+		c.emit(node, parser.OpBinaryOp, int(token.Or))
+	case token.AndNotAssign:
+		c.emit(node, parser.OpBinaryOp, int(token.AndNot))
+	case token.XorAssign:
+		c.emit(node, parser.OpBinaryOp, int(token.Xor))
+	case token.ShlAssign:
+		c.emit(node, parser.OpBinaryOp, int(token.Shl))
+	case token.ShrAssign:
+		c.emit(node, parser.OpBinaryOp, int(token.Shr))
+	}
+
+	// compile selector expressions (right to left)
+	for i := numSel - 1; i >= 0; i-- {
+		if err := c.Compile(selectors[i]); err != nil {
+			return err
+		}
+	}
+
+	switch symbol.Scope {
+	case ScopeGlobal:
+		if numSel > 0 {
+			c.emit(node, parser.OpSetSelGlobal, symbol.Index, numSel)
+		} else {
+			c.emit(node, parser.OpSetGlobal, symbol.Index)
+		}
+	case ScopeLocal:
+		if numSel > 0 {
+			c.emit(node, parser.OpSetSelLocal, symbol.Index, numSel)
+		} else {
+			if op == token.Define && !symbol.LocalAssigned {
+				c.emit(node, parser.OpDefineLocal, symbol.Index)
+			} else {
+				c.emit(node, parser.OpSetLocal, symbol.Index)
+			}
+		}
+
+		// mark the symbol as local-assigned
+		symbol.LocalAssigned = true
+	case ScopeFree:
+		if numSel > 0 {
+			c.emit(node, parser.OpSetSelFree, symbol.Index, numSel)
+		} else {
+			c.emit(node, parser.OpSetFree, symbol.Index)
+		}
+	default:
+		panic(fmt.Errorf("invalid assignment variable scope: %s",
+			symbol.Scope))
+	}
+	return nil
+}
+
+func (c *Compiler) compileLogical(node *parser.BinaryExpr) error {
+	// left side term
+	if err := c.Compile(node.LHS); err != nil {
+		return err
+	}
+
+	// jump position
+	var jumpPos int
+	if node.Token == token.LAnd {
+		jumpPos = c.emit(node, parser.OpAndJump, 0)
+	} else {
+		jumpPos = c.emit(node, parser.OpOrJump, 0)
+	}
+
+	// right side term
+	if err := c.Compile(node.RHS); err != nil {
+		return err
+	}
+
+	c.changeOperand(jumpPos, len(c.currentInstructions()))
+	return nil
+}
+
+func (c *Compiler) compileForStmt(stmt *parser.ForStmt) error {
+	c.symbolTable = c.symbolTable.Fork(true)
+	defer func() {
+		c.symbolTable = c.symbolTable.Parent(false)
+	}()
+
+	// init statement
+	if stmt.Init != nil {
+		if err := c.Compile(stmt.Init); err != nil {
+			return err
+		}
+	}
+
+	// pre-condition position
+	preCondPos := len(c.currentInstructions())
+
+	// condition expression
+	postCondPos := -1
+	if stmt.Cond != nil {
+		if err := c.Compile(stmt.Cond); err != nil {
+			return err
+		}
+		// condition jump position
+		postCondPos = c.emit(stmt, parser.OpJumpFalsy, 0)
+	}
+
+	// enter loop
+	loop := c.enterLoop()
+
+	// body statement
+	if err := c.Compile(stmt.Body); err != nil {
+		c.leaveLoop()
+		return err
+	}
+
+	c.leaveLoop()
+
+	// post-body position
+	postBodyPos := len(c.currentInstructions())
+
+	// post statement
+	if stmt.Post != nil {
+		if err := c.Compile(stmt.Post); err != nil {
+			return err
+		}
+	}
+
+	// back to condition
+	c.emit(stmt, parser.OpJump, preCondPos)
+
+	// post-statement position
+	postStmtPos := len(c.currentInstructions())
+	if postCondPos >= 0 {
+		c.changeOperand(postCondPos, postStmtPos)
+	}
+
+	// update all break/continue jump positions
+	for _, pos := range loop.Breaks {
+		c.changeOperand(pos, postStmtPos)
+	}
+	for _, pos := range loop.Continues {
+		c.changeOperand(pos, postBodyPos)
+	}
+	return nil
+}
+
+func (c *Compiler) compileForInStmt(stmt *parser.ForInStmt) error {
+	c.symbolTable = c.symbolTable.Fork(true)
+	defer func() {
+		c.symbolTable = c.symbolTable.Parent(false)
+	}()
+
+	// for-in statement is compiled like following:
+	//
+	//   for :it := iterator(iterable); :it.next();  {
+	//     k, v := :it.get()  // DEFINE operator
+	//
+	//     ... body ...
+	//   }
+	//
+	// ":it" is a local variable but will be conflict with other user variables
+	// because character ":" is not allowed.
+
+	// init
+	//   :it = iterator(iterable)
+	itSymbol := c.symbolTable.Define(":it")
+	if err := c.Compile(stmt.Iterable); err != nil {
+		return err
+	}
+	c.emit(stmt, parser.OpIteratorInit)
+	if itSymbol.Scope == ScopeGlobal {
+		c.emit(stmt, parser.OpSetGlobal, itSymbol.Index)
+	} else {
+		c.emit(stmt, parser.OpDefineLocal, itSymbol.Index)
+	}
+
+	// pre-condition position
+	preCondPos := len(c.currentInstructions())
+
+	// condition
+	//  :it.HasMore()
+	if itSymbol.Scope == ScopeGlobal {
+		c.emit(stmt, parser.OpGetGlobal, itSymbol.Index)
+	} else {
+		c.emit(stmt, parser.OpGetLocal, itSymbol.Index)
+	}
+	c.emit(stmt, parser.OpIteratorNext)
+
+	// condition jump position
+	postCondPos := c.emit(stmt, parser.OpJumpFalsy, 0)
+
+	// enter loop
+	loop := c.enterLoop()
+
+	// assign key variable
+	if stmt.Key.Name != "_" {
+		keySymbol := c.symbolTable.Define(stmt.Key.Name)
+		if itSymbol.Scope == ScopeGlobal {
+			c.emit(stmt, parser.OpGetGlobal, itSymbol.Index)
+		} else {
+			c.emit(stmt, parser.OpGetLocal, itSymbol.Index)
+		}
+		c.emit(stmt, parser.OpIteratorKey)
+		if keySymbol.Scope == ScopeGlobal {
+			c.emit(stmt, parser.OpSetGlobal, keySymbol.Index)
+		} else {
+			c.emit(stmt, parser.OpDefineLocal, keySymbol.Index)
+		}
+	}
+
+	// assign value variable
+	if stmt.Value.Name != "_" {
+		valueSymbol := c.symbolTable.Define(stmt.Value.Name)
+		if itSymbol.Scope == ScopeGlobal {
+			c.emit(stmt, parser.OpGetGlobal, itSymbol.Index)
+		} else {
+			c.emit(stmt, parser.OpGetLocal, itSymbol.Index)
+		}
+		c.emit(stmt, parser.OpIteratorValue)
+		if valueSymbol.Scope == ScopeGlobal {
+			c.emit(stmt, parser.OpSetGlobal, valueSymbol.Index)
+		} else {
+			c.emit(stmt, parser.OpDefineLocal, valueSymbol.Index)
+		}
+	}
+
+	// body statement
+	if err := c.Compile(stmt.Body); err != nil {
+		c.leaveLoop()
+		return err
+	}
+
+	c.leaveLoop()
+
+	// post-body position
+	postBodyPos := len(c.currentInstructions())
+
+	// back to condition
+	c.emit(stmt, parser.OpJump, preCondPos)
+
+	// post-statement position
+	postStmtPos := len(c.currentInstructions())
+	c.changeOperand(postCondPos, postStmtPos)
+
+	// update all break/continue jump positions
+	for _, pos := range loop.Breaks {
+		c.changeOperand(pos, postStmtPos)
+	}
+	for _, pos := range loop.Continues {
+		c.changeOperand(pos, postBodyPos)
+	}
+	return nil
+}
+
+func (c *Compiler) checkCyclicImports(
+	node parser.Node,
+	modulePath string,
+) error {
+	if c.modulePath == modulePath {
+		return c.errorf(node, "cyclic module import: %s", modulePath)
+	} else if c.parent != nil {
+		return c.parent.checkCyclicImports(node, modulePath)
+	}
+	return nil
+}
+
+func (c *Compiler) compileModule(
+	node parser.Node,
+	moduleName, modulePath string,
+	src []byte,
+) (*CompiledFunction, error) {
+	if err := c.checkCyclicImports(node, modulePath); err != nil {
+		return nil, err
+	}
+
+	compiledModule, exists := c.loadCompiledModule(modulePath)
+	if exists {
+		return compiledModule, nil
+	}
+
+	modFile := c.file.Set().AddFile(moduleName, -1, len(src))
+	p := parser.NewParser(modFile, src, nil)
+	file, err := p.ParseFile()
+	if err != nil {
+		return nil, err
+	}
+
+	// inherit builtin functions
+	symbolTable := NewSymbolTable()
+	for _, sym := range c.symbolTable.BuiltinSymbols() {
+		symbolTable.DefineBuiltin(sym.Index, sym.Name)
+	}
+
+	// no global scope for the module
+	symbolTable = symbolTable.Fork(false)
+
+	// compile module
+	moduleCompiler := c.fork(modFile, modulePath, symbolTable)
+	if err := moduleCompiler.Compile(file); err != nil {
+		return nil, err
+	}
+
+	// code optimization
+	moduleCompiler.optimizeFunc(node)
+	compiledFunc := moduleCompiler.Bytecode().MainFunction
+	compiledFunc.NumLocals = symbolTable.MaxSymbols()
+	c.storeCompiledModule(modulePath, compiledFunc)
+	return compiledFunc, nil
+}
+
+func (c *Compiler) loadCompiledModule(
+	modulePath string,
+) (mod *CompiledFunction, ok bool) {
+	if c.parent != nil {
+		return c.parent.loadCompiledModule(modulePath)
+	}
+	mod, ok = c.compiledModules[modulePath]
+	return
+}
+
+func (c *Compiler) storeCompiledModule(
+	modulePath string,
+	module *CompiledFunction,
+) {
+	if c.parent != nil {
+		c.parent.storeCompiledModule(modulePath, module)
+	}
+	c.compiledModules[modulePath] = module
+}
+
+func (c *Compiler) enterLoop() *loop {
+	loop := &loop{}
+	c.loops = append(c.loops, loop)
+	c.loopIndex++
+	if c.trace != nil {
+		c.printTrace("LOOPE", c.loopIndex)
+	}
+	return loop
+}
+
+func (c *Compiler) leaveLoop() {
+	if c.trace != nil {
+		c.printTrace("LOOPL", c.loopIndex)
+	}
+	c.loops = c.loops[:len(c.loops)-1]
+	c.loopIndex--
+}
+
+func (c *Compiler) currentLoop() *loop {
+	if c.loopIndex >= 0 {
+		return c.loops[c.loopIndex]
+	}
+	return nil
+}
+
+func (c *Compiler) currentInstructions() []byte {
+	return c.scopes[c.scopeIndex].Instructions
+}
+
+func (c *Compiler) currentSourceMap() map[int]parser.Pos {
+	return c.scopes[c.scopeIndex].SourceMap
+}
+
+func (c *Compiler) enterScope() {
+	scope := compilationScope{
+		SymbolInit: make(map[string]bool),
+		SourceMap:  make(map[int]parser.Pos),
+	}
+	c.scopes = append(c.scopes, scope)
+	c.scopeIndex++
+	c.symbolTable = c.symbolTable.Fork(false)
+	if c.trace != nil {
+		c.printTrace("SCOPE", c.scopeIndex)
+	}
+}
+
+func (c *Compiler) leaveScope() (
+	instructions []byte,
+	sourceMap map[int]parser.Pos,
+) {
+	instructions = c.currentInstructions()
+	sourceMap = c.currentSourceMap()
+	c.scopes = c.scopes[:len(c.scopes)-1]
+	c.scopeIndex--
+	c.symbolTable = c.symbolTable.Parent(true)
+	if c.trace != nil {
+		c.printTrace("SCOPL", c.scopeIndex)
+	}
+	return
+}
+
+func (c *Compiler) fork(
+	file *parser.SourceFile,
+	modulePath string,
+	symbolTable *SymbolTable,
+) *Compiler {
+	child := NewCompiler(file, symbolTable, nil, c.modules, c.trace)
+	child.modulePath = modulePath // module file path
+	child.parent = c              // parent to set to current compiler
+	return child
+}
+
+func (c *Compiler) error(node parser.Node, err error) error {
+	return &CompilerError{
+		FileSet: c.file.Set(),
+		Node:    node,
+		Err:     err,
+	}
+}
+
+func (c *Compiler) errorf(
+	node parser.Node,
+	format string,
+	args ...interface{},
+) error {
+	return &CompilerError{
+		FileSet: c.file.Set(),
+		Node:    node,
+		Err:     fmt.Errorf(format, args...),
+	}
+}
+
+func (c *Compiler) addConstant(o Object) int {
+	if c.parent != nil {
+		// module compilers will use their parent's constants array
+		return c.parent.addConstant(o)
+	}
+	c.constants = append(c.constants, o)
+	if c.trace != nil {
+		c.printTrace(fmt.Sprintf("CONST %04d %s", len(c.constants)-1, o))
+	}
+	return len(c.constants) - 1
+}
+
+func (c *Compiler) addInstruction(b []byte) int {
+	posNewIns := len(c.currentInstructions())
+	c.scopes[c.scopeIndex].Instructions = append(
+		c.currentInstructions(), b...)
+	return posNewIns
+}
+
+func (c *Compiler) replaceInstruction(pos int, inst []byte) {
+	copy(c.currentInstructions()[pos:], inst)
+	if c.trace != nil {
+		c.printTrace(fmt.Sprintf("REPLC %s",
+			FormatInstructions(
+				c.scopes[c.scopeIndex].Instructions[pos:], pos)[0]))
+	}
+}
+
+func (c *Compiler) changeOperand(opPos int, operand ...int) {
+	op := c.currentInstructions()[opPos]
+	inst := MakeInstruction(op, operand...)
+	c.replaceInstruction(opPos, inst)
+}
+
+// optimizeFunc performs some code-level optimization for the current function
+// instructions. It also removes unreachable (dead code) instructions and adds
+// "returns" instruction if needed.
+func (c *Compiler) optimizeFunc(node parser.Node) {
+	// any instructions between RETURN and the function end
+	// or instructions between RETURN and jump target position
+	// are considered as unreachable.
+
+	// pass 1. identify all jump destinations
+	dsts := make(map[int]bool)
+	iterateInstructions(c.scopes[c.scopeIndex].Instructions,
+		func(pos int, opcode parser.Opcode, operands []int) bool {
+			switch opcode {
+			case parser.OpJump, parser.OpJumpFalsy,
+				parser.OpAndJump, parser.OpOrJump:
+				dsts[operands[0]] = true
+			}
+			return true
+		})
+
+	// pass 2. eliminate dead code
+	var newInsts []byte
+	posMap := make(map[int]int) // old position to new position
+	var dstIdx int
+	var deadCode bool
+	iterateInstructions(c.scopes[c.scopeIndex].Instructions,
+		func(pos int, opcode parser.Opcode, operands []int) bool {
+			switch {
+			case opcode == parser.OpReturn:
+				if deadCode {
+					return true
+				}
+				deadCode = true
+			case dsts[pos]:
+				dstIdx++
+				deadCode = false
+			case deadCode:
+				return true
+			}
+			posMap[pos] = len(newInsts)
+			newInsts = append(newInsts,
+				MakeInstruction(opcode, operands...)...)
+			return true
+		})
+
+	// pass 3. update jump positions
+	var lastOp parser.Opcode
+	var appendReturn bool
+	endPos := len(c.scopes[c.scopeIndex].Instructions)
+	iterateInstructions(newInsts,
+		func(pos int, opcode parser.Opcode, operands []int) bool {
+			switch opcode {
+			case parser.OpJump, parser.OpJumpFalsy, parser.OpAndJump,
+				parser.OpOrJump:
+				newDst, ok := posMap[operands[0]]
+				if ok {
+					copy(newInsts[pos:],
+						MakeInstruction(opcode, newDst))
+				} else if endPos == operands[0] {
+					// there's a jump instruction that jumps to the end of
+					// function compiler should append "return".
+					appendReturn = true
+				} else {
+					panic(fmt.Errorf("invalid jump position: %d", newDst))
+				}
+			}
+			lastOp = opcode
+			return true
+		})
+	if lastOp != parser.OpReturn {
+		appendReturn = true
+	}
+
+	// pass 4. update source map
+	newSourceMap := make(map[int]parser.Pos)
+	for pos, srcPos := range c.scopes[c.scopeIndex].SourceMap {
+		newPos, ok := posMap[pos]
+		if ok {
+			newSourceMap[newPos] = srcPos
+		}
+	}
+	c.scopes[c.scopeIndex].Instructions = newInsts
+	c.scopes[c.scopeIndex].SourceMap = newSourceMap
+
+	// append "return"
+	if appendReturn {
+		c.emit(node, parser.OpReturn, 0)
+	}
+}
+
+func (c *Compiler) emit(
+	node parser.Node,
+	opcode parser.Opcode,
+	operands ...int,
+) int {
+	filePos := parser.NoPos
+	if node != nil {
+		filePos = node.Pos()
+	}
+
+	inst := MakeInstruction(opcode, operands...)
+	pos := c.addInstruction(inst)
+	c.scopes[c.scopeIndex].SourceMap[pos] = filePos
+	if c.trace != nil {
+		c.printTrace(fmt.Sprintf("EMIT  %s",
+			FormatInstructions(
+				c.scopes[c.scopeIndex].Instructions[pos:], pos)[0]))
+	}
+	return pos
+}
+
+func (c *Compiler) printTrace(a ...interface{}) {
+	const (
+		dots = ". . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . "
+		n    = len(dots)
+	)
+
+	i := 2 * c.indent
+	for i > n {
+		_, _ = fmt.Fprint(c.trace, dots)
+		i -= n
+	}
+	_, _ = fmt.Fprint(c.trace, dots[0:i])
+	_, _ = fmt.Fprintln(c.trace, a...)
+}
+
+func resolveAssignLHS(
+	expr parser.Expr,
+) (name string, selectors []parser.Expr) {
+	switch term := expr.(type) {
+	case *parser.SelectorExpr:
+		name, selectors = resolveAssignLHS(term.Expr)
+		selectors = append(selectors, term.Sel)
+		return
+	case *parser.IndexExpr:
+		name, selectors = resolveAssignLHS(term.Expr)
+		selectors = append(selectors, term.Index)
+	case *parser.Ident:
+		name = term.Name
+	}
+	return
+}
+
+func iterateInstructions(
+	b []byte,
+	fn func(pos int, opcode parser.Opcode, operands []int) bool,
+) {
+	for i := 0; i < len(b); i++ {
+		numOperands := parser.OpcodeOperands[b[i]]
+		operands, read := parser.ReadOperands(numOperands, b[i+1:])
+		if !fn(i, b[i], operands) {
+			break
+		}
+		i += read
+	}
+}
+
+func tracec(c *Compiler, msg string) *Compiler {
+	c.printTrace(msg, "{")
+	c.indent++
+	return c
+}
+
+func untracec(c *Compiler) {
+	c.indent--
+	c.printTrace("}")
+}
diff --git a/vendor/github.com/d5/tengo/v2/doc.go b/vendor/github.com/d5/tengo/v2/doc.go
new file mode 100644
index 00000000..05b47de1
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/doc.go
@@ -0,0 +1,3 @@
+// tengo is a small, dynamic, fast, secure script language for Go.
+
+package tengo
diff --git a/vendor/github.com/d5/tengo/v2/errors.go b/vendor/github.com/d5/tengo/v2/errors.go
new file mode 100644
index 00000000..a3fd1f3b
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/errors.go
@@ -0,0 +1,64 @@
+package tengo
+
+import (
+	"errors"
+	"fmt"
+)
+
+var (
+	// ErrStackOverflow is a stack overflow error.
+	ErrStackOverflow = errors.New("stack overflow")
+
+	// ErrObjectAllocLimit is an objects allocation limit error.
+	ErrObjectAllocLimit = errors.New("object allocation limit exceeded")
+
+	// ErrIndexOutOfBounds is an error where a given index is out of the
+	// bounds.
+	ErrIndexOutOfBounds = errors.New("index out of bounds")
+
+	// ErrInvalidIndexType represents an invalid index type.
+	ErrInvalidIndexType = errors.New("invalid index type")
+
+	// ErrInvalidIndexValueType represents an invalid index value type.
+	ErrInvalidIndexValueType = errors.New("invalid index value type")
+
+	// ErrInvalidIndexOnError represents an invalid index on error.
+	ErrInvalidIndexOnError = errors.New("invalid index on error")
+
+	// ErrInvalidOperator represents an error for invalid operator usage.
+	ErrInvalidOperator = errors.New("invalid operator")
+
+	// ErrWrongNumArguments represents a wrong number of arguments error.
+	ErrWrongNumArguments = errors.New("wrong number of arguments")
+
+	// ErrBytesLimit represents an error where the size of bytes value exceeds
+	// the limit.
+	ErrBytesLimit = errors.New("exceeding bytes size limit")
+
+	// ErrStringLimit represents an error where the size of string value
+	// exceeds the limit.
+	ErrStringLimit = errors.New("exceeding string size limit")
+
+	// ErrNotIndexable is an error where an Object is not indexable.
+	ErrNotIndexable = errors.New("not indexable")
+
+	// ErrNotIndexAssignable is an error where an Object is not index
+	// assignable.
+	ErrNotIndexAssignable = errors.New("not index-assignable")
+
+	// ErrNotImplemented is an error where an Object has not implemented a
+	// required method.
+	ErrNotImplemented = errors.New("not implemented")
+)
+
+// ErrInvalidArgumentType represents an invalid argument value type error.
+type ErrInvalidArgumentType struct {
+	Name     string
+	Expected string
+	Found    string
+}
+
+func (e ErrInvalidArgumentType) Error() string {
+	return fmt.Sprintf("invalid type for argument '%s': expected %s, found %s",
+		e.Name, e.Expected, e.Found)
+}
diff --git a/vendor/github.com/d5/tengo/objects/formatter.go b/vendor/github.com/d5/tengo/v2/formatter.go
index 95d7f6b1..0dbf71c6 100644
--- a/vendor/github.com/d5/tengo/objects/formatter.go
+++ b/vendor/github.com/d5/tengo/v2/formatter.go
@@ -1,15 +1,13 @@
-package objects
+package tengo
 
 import (
 	"strconv"
 	"sync"
 	"unicode/utf8"
-
-	"github.com/d5/tengo"
 )
 
-// Strings for use with buffer.WriteString.
-// This is less overhead than using buffer.Write with byte arrays.
+// Strings for use with fmtbuf.WriteString. This is less overhead than using
+// fmtbuf.Write with byte arrays.
 const (
 	commaSpaceString  = ", "
 	nilParenString    = "(nil)"
@@ -55,9 +53,9 @@ type fmtFlags struct {
 }
 
 // A formatter is the raw formatter used by Printf etc.
-// It prints into a buffer that must be set up separately.
+// It prints into a fmtbuf that must be set up separately.
 type formatter struct {
-	buf *buffer
+	buf *fmtbuf
 
 	fmtFlags
 
@@ -69,13 +67,13 @@ type formatter struct {
 	intbuf [68]byte
 }
 
-func (f *formatter) clearflags() {
+func (f *formatter) clearFlags() {
 	f.fmtFlags = fmtFlags{}
 }
 
-func (f *formatter) init(buf *buffer) {
+func (f *formatter) init(buf *fmtbuf) {
 	f.buf = buf
-	f.clearflags()
+	f.clearFlags()
 }
 
 // writePadding generates n bytes of padding.
@@ -87,13 +85,13 @@ func (f *formatter) writePadding(n int) {
 	oldLen := len(buf)
 	newLen := oldLen + n
 
-	if newLen > tengo.MaxStringLen {
+	if newLen > MaxStringLen {
 		panic(ErrStringLimit)
 	}
 
 	// Make enough room for padding.
 	if newLen > cap(buf) {
-		buf = make(buffer, cap(buf)*2+n)
+		buf = make(fmtbuf, cap(buf)*2+n)
 		copy(buf, *f.buf)
 	}
 	// Decide which byte the padding should be filled with.
@@ -171,10 +169,12 @@ func (f *formatter) fmtUnicode(u uint64) {
 		}
 	}
 
-	// Format into buf, ending at buf[i]. Formatting numbers is easier right-to-left.
+	// Format into buf, ending at buf[i]. Formatting numbers is easier
+	// right-to-left.
 	i := len(buf)
 
-	// For %#U we want to add a space and a quoted character at the end of the buffer.
+	// For %#U we want to add a space and a quoted character at the end of
+	// the fmtbuf.
 	if f.sharp && u <= utf8.MaxRune && strconv.IsPrint(rune(u)) {
 		i--
 		buf[i] = '\''
@@ -214,7 +214,13 @@ func (f *formatter) fmtUnicode(u uint64) {
 }
 
 // fmtInteger formats signed and unsigned integers.
-func (f *formatter) fmtInteger(u uint64, base int, isSigned bool, verb rune, digits string) {
+func (f *formatter) fmtInteger(
+	u uint64,
+	base int,
+	isSigned bool,
+	verb rune,
+	digits string,
+) {
 	negative := isSigned && int64(u) < 0
 	if negative {
 		u = -u
@@ -253,9 +259,10 @@ func (f *formatter) fmtInteger(u uint64, base int, isSigned bool, verb rune, dig
 		}
 	}
 
-	// Because printing is easier right-to-left: format u into buf, ending at buf[i].
-	// We could make things marginally faster by splitting the 32-bit case out
-	// into a separate block but it's not worth the duplication, so u has 64 bits.
+	// Because printing is easier right-to-left: format u into buf, ending at
+	// buf[i]. We could make things marginally faster by splitting the 32-bit
+	// case out into a separate block but it's not worth the duplication, so
+	// u has 64 bits.
 	i := len(buf)
 	// Use constants for the division and modulo for more efficient code.
 	// Switch cases ordered by popularity.
@@ -357,7 +364,8 @@ func (f *formatter) truncateString(s string) string {
 	return s
 }
 
-// truncate truncates the byte slice b as a string of the specified precision, if present.
+// truncate truncates the byte slice b as a string of the specified precision,
+// if present.
 func (f *formatter) truncate(b []byte) []byte {
 	if f.precPresent {
 		n := f.prec
@@ -399,11 +407,13 @@ func (f *formatter) fmtSbx(s string, b []byte, digits string) {
 	if f.precPresent && f.prec < length {
 		length = f.prec
 	}
-	// Compute width of the encoding taking into account the f.sharp and f.space flag.
+	// Compute width of the encoding taking into account the f.sharp and
+	// f.space flag.
 	width := 2 * length
 	if width > 0 {
 		if f.space {
-			// Each element encoded by two hexadecimals will get a leading 0x or 0X.
+			// Each element encoded by two hexadecimals will get a leading
+			// 0x or 0X.
 			if f.sharp {
 				width *= 2
 			}
@@ -423,7 +433,7 @@ func (f *formatter) fmtSbx(s string, b []byte, digits string) {
 	if f.widPresent && f.wid > width && !f.minus {
 		f.writePadding(f.wid - width)
 	}
-	// Write the encoding directly into the output buffer.
+	// Write the encoding directly into the output fmtbuf.
 	buf := *f.buf
 	if f.sharp {
 		// Add leading 0x or 0X.
@@ -589,8 +599,9 @@ func (f *formatter) fmtFloat(v float64, size int, verb rune, prec int) {
 	}
 	// We want a sign if asked for and if the sign is not positive.
 	if f.plus || num[0] != '+' {
-		// If we're zero padding to the left we want the sign before the leading zeros.
-		// Achieve this by writing the sign out and then padding the unsigned number.
+		// If we're zero padding to the left we want the sign before the
+		// leading zeros. Achieve this by writing the sign out and then padding
+		// the unsigned number.
 		if f.zero && f.widPresent && f.wid > len(num) {
 			f.buf.WriteSingleByte(num[0])
 			f.writePadding(f.wid - len(num))
@@ -600,39 +611,40 @@ func (f *formatter) fmtFloat(v float64, size int, verb rune, prec int) {
 		f.pad(num)
 		return
 	}
-	// No sign to show and the number is positive; just print the unsigned number.
+	// No sign to show and the number is positive; just print the unsigned
+	// number.
 	f.pad(num[1:])
 }
 
 // Use simple []byte instead of bytes.Buffer to avoid large dependency.
-type buffer []byte
+type fmtbuf []byte
 
-func (b *buffer) Write(p []byte) {
-	if len(*b)+len(p) > tengo.MaxStringLen {
+func (b *fmtbuf) Write(p []byte) {
+	if len(*b)+len(p) > MaxStringLen {
 		panic(ErrStringLimit)
 	}
 
 	*b = append(*b, p...)
 }
 
-func (b *buffer) WriteString(s string) {
-	if len(*b)+len(s) > tengo.MaxStringLen {
+func (b *fmtbuf) WriteString(s string) {
+	if len(*b)+len(s) > MaxStringLen {
 		panic(ErrStringLimit)
 	}
 
 	*b = append(*b, s...)
 }
 
-func (b *buffer) WriteSingleByte(c byte) {
-	if len(*b) >= tengo.MaxStringLen {
+func (b *fmtbuf) WriteSingleByte(c byte) {
+	if len(*b) >= MaxStringLen {
 		panic(ErrStringLimit)
 	}
 
 	*b = append(*b, c)
 }
 
-func (b *buffer) WriteRune(r rune) {
-	if len(*b)+utf8.RuneLen(r) > tengo.MaxStringLen {
+func (b *fmtbuf) WriteRune(r rune) {
+	if len(*b)+utf8.RuneLen(r) > MaxStringLen {
 		panic(ErrStringLimit)
 	}
 
@@ -650,9 +662,10 @@ func (b *buffer) WriteRune(r rune) {
 	*b = b2[:n+w]
 }
 
-// pp is used to store a printer's state and is reused with sync.Pool to avoid allocations.
+// pp is used to store a printer's state and is reused with sync.Pool to avoid
+// allocations.
 type pp struct {
-	buf buffer
+	buf fmtbuf
 
 	// arg holds the current item.
 	arg Object
@@ -663,10 +676,12 @@ type pp struct {
 	// reordered records whether the format string used argument reordering.
 	reordered bool
 
-	// goodArgNum records whether the most recent reordering directive was valid.
+	// goodArgNum records whether the most recent reordering directive was
+	// valid.
 	goodArgNum bool
 
-	// erroring is set when printing an error string to guard against calling handleMethods.
+	// erroring is set when printing an error string to guard against calling
+	// handleMethods.
 	erroring bool
 }
 
@@ -686,8 +701,8 @@ func newPrinter() *pp {
 func (p *pp) free() {
 	// Proper usage of a sync.Pool requires each entry to have approximately
 	// the same memory cost. To obtain this property when the stored type
-	// contains a variably-sized buffer, we add a hard limit on the maximum buffer
-	// to place back in the pool.
+	// contains a variably-sized fmtbuf, we add a hard limit on the maximum
+	// fmtbuf to place back in the pool.
 	//
 	// See https://golang.org/issue/23199
 	if cap(p.buf) > 64<<10 {
@@ -699,9 +714,13 @@ func (p *pp) free() {
 	ppFree.Put(p)
 }
 
-func (p *pp) Width() (wid int, ok bool) { return p.fmt.wid, p.fmt.widPresent }
+func (p *pp) Width() (wid int, ok bool) {
+	return p.fmt.wid, p.fmt.widPresent
+}
 
-func (p *pp) Precision() (prec int, ok bool) { return p.fmt.prec, p.fmt.precPresent }
+func (p *pp) Precision() (prec int, ok bool) {
+	return p.fmt.prec, p.fmt.precPresent
+}
 
 func (p *pp) Flag(b int) bool {
 	switch b {
@@ -750,7 +769,8 @@ func tooLarge(x int) bool {
 	return x > max || x < -max
 }
 
-// parsenum converts ASCII to integer.  num is 0 (and isnum is false) if no number present.
+// parsenum converts ASCII to integer.  num is 0 (and isnum is false) if no
+// number present.
 func parsenum(s string, start, end int) (num int, isnum bool, newi int) {
 	if start >= end {
 		return 0, false, end
@@ -918,7 +938,8 @@ func (p *pp) printArg(arg Object, verb rune) {
 	}
 
 	// Special processing considerations.
-	// %T (the value's type) and %p (its address) are special; we always do them first.
+	// %T (the value's type) and %p (its address) are special; we always do
+	// them first.
 	switch verb {
 	case 'T':
 		p.fmt.fmtS(arg.TypeName())
@@ -945,7 +966,8 @@ func (p *pp) printArg(arg Object, verb rune) {
 	}
 }
 
-// intFromArg gets the argNumth element of a. On return, isInt reports whether the argument has integer type.
+// intFromArg gets the argNumth element of a. On return, isInt reports whether
+// the argument has integer type.
 func intFromArg(a []Object, argNum int) (num int, isInt bool, newArgNum int) {
 	newArgNum = argNum
 	if argNum < len(a) {
@@ -980,16 +1002,23 @@ func parseArgNumber(format string) (index int, wid int, ok bool) {
 			if !ok || newi != i {
 				return 0, i + 1, false
 			}
-			return width - 1, i + 1, true // arg numbers are one-indexed and skip paren.
+			// arg numbers are one-indexed andskip paren.
+			return width - 1, i + 1, true
 		}
 	}
 	return 0, 1, false
 }
 
-// argNumber returns the next argument to evaluate, which is either the value of the passed-in
-// argNum or the value of the bracketed integer that begins format[i:]. It also returns
-// the new value of i, that is, the index of the next byte of the format to process.
-func (p *pp) argNumber(argNum int, format string, i int, numArgs int) (newArgNum, newi int, found bool) {
+// argNumber returns the next argument to evaluate, which is either the value
+// of the passed-in argNum or the value of the bracketed integer that begins
+// format[i:]. It also returns the new value of i, that is, the index of the
+// next byte of the format to process.
+func (p *pp) argNumber(
+	argNum int,
+	format string,
+	i int,
+	numArgs int,
+) (newArgNum, newi int, found bool) {
 	if len(format) <= i || format[i] != '[' {
 		return argNum, i, false
 	}
@@ -1048,7 +1077,7 @@ formatLoop:
 		i++
 
 		// Do we have flags?
-		p.fmt.clearflags()
+		p.fmt.clearFlags()
 	simpleFormat:
 		for ; i < end; i++ {
 			c := format[i]
@@ -1056,7 +1085,8 @@ formatLoop:
 			case '#':
 				p.fmt.sharp = true
 			case '0':
-				p.fmt.zero = !p.fmt.minus // Only allow zero padding to the left.
+				// Only allow zero padding to the left.
+				p.fmt.zero = !p.fmt.minus
 			case '+':
 				p.fmt.plus = true
 			case '-':
@@ -1081,7 +1111,8 @@ formatLoop:
 					i++
 					continue formatLoop
 				}
-				// Format is more complex than simple flags and a verb or is malformed.
+				// Format is more complex than simple flags and a verb or is
+				// malformed.
 				break simpleFormat
 			}
 		}
@@ -1157,11 +1188,13 @@ formatLoop:
 		i += size
 
 		switch {
-		case verb == '%': // Percent does not absorb operands and ignores f.wid and f.prec.
+		case verb == '%':
+			// Percent does not absorb operands and ignores f.wid and f.prec.
 			_, _ = p.WriteSingleByte('%')
 		case !p.goodArgNum:
 			p.badArgNum(verb)
-		case argNum >= len(a): // No argument left over to print for the current verb.
+		case argNum >= len(a):
+			// No argument left over to print for the current verb.
 			p.missingArg(verb)
 		case verb == 'v':
 			// Go syntax
@@ -1181,7 +1214,7 @@ formatLoop:
 	// out of order, in which case it's too expensive to detect if they've all
 	// been used and arguably OK if they're not.
 	if !p.reordered && argNum < len(a) {
-		p.fmt.clearflags()
+		p.fmt.clearFlags()
 		_, _ = p.WriteString(extraString)
 		for i, arg := range a[argNum:] {
 			if i > 0 {
@@ -1201,7 +1234,7 @@ formatLoop:
 	return nil
 }
 
-// Format formats according to a format specifier and returns the resulting string.
+// Format is like fmt.Sprintf but using Objects.
 func Format(format string, a ...Object) (string, error) {
 	p := newPrinter()
 	err := p.doFormat(format, a)
diff --git a/vendor/github.com/d5/tengo/v2/go.mod b/vendor/github.com/d5/tengo/v2/go.mod
new file mode 100644
index 00000000..732ff142
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/go.mod
@@ -0,0 +1,3 @@
+module github.com/d5/tengo/v2
+
+go 1.13
diff --git a/vendor/github.com/d5/tengo/go.sum b/vendor/github.com/d5/tengo/v2/go.sum
index e69de29b..e69de29b 100644
--- a/vendor/github.com/d5/tengo/go.sum
+++ b/vendor/github.com/d5/tengo/v2/go.sum
diff --git a/vendor/github.com/d5/tengo/v2/instructions.go b/vendor/github.com/d5/tengo/v2/instructions.go
new file mode 100644
index 00000000..eb1fbf27
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/instructions.go
@@ -0,0 +1,61 @@
+package tengo
+
+import (
+	"fmt"
+
+	"github.com/d5/tengo/v2/parser"
+)
+
+// MakeInstruction returns a bytecode for an opcode and the operands.
+func MakeInstruction(opcode parser.Opcode, operands ...int) []byte {
+	numOperands := parser.OpcodeOperands[opcode]
+
+	totalLen := 1
+	for _, w := range numOperands {
+		totalLen += w
+	}
+
+	instruction := make([]byte, totalLen)
+	instruction[0] = opcode
+
+	offset := 1
+	for i, o := range operands {
+		width := numOperands[i]
+		switch width {
+		case 1:
+			instruction[offset] = byte(o)
+		case 2:
+			n := uint16(o)
+			instruction[offset] = byte(n >> 8)
+			instruction[offset+1] = byte(n)
+		}
+		offset += width
+	}
+	return instruction
+}
+
+// FormatInstructions returns string representation of bytecode instructions.
+func FormatInstructions(b []byte, posOffset int) []string {
+	var out []string
+
+	i := 0
+	for i < len(b) {
+		numOperands := parser.OpcodeOperands[b[i]]
+		operands, read := parser.ReadOperands(numOperands, b[i+1:])
+
+		switch len(numOperands) {
+		case 0:
+			out = append(out, fmt.Sprintf("%04d %-7s",
+				posOffset+i, parser.OpcodeNames[b[i]]))
+		case 1:
+			out = append(out, fmt.Sprintf("%04d %-7s %-5d",
+				posOffset+i, parser.OpcodeNames[b[i]], operands[0]))
+		case 2:
+			out = append(out, fmt.Sprintf("%04d %-7s %-5d %-5d",
+				posOffset+i, parser.OpcodeNames[b[i]],
+				operands[0], operands[1]))
+		}
+		i += 1 + read
+	}
+	return out
+}
diff --git a/vendor/github.com/d5/tengo/v2/iterator.go b/vendor/github.com/d5/tengo/v2/iterator.go
new file mode 100644
index 00000000..13adbbab
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/iterator.go
@@ -0,0 +1,209 @@
+package tengo
+
+// Iterator represents an iterator for underlying data type.
+type Iterator interface {
+	Object
+
+	// Next returns true if there are more elements to iterate.
+	Next() bool
+
+	// Key returns the key or index value of the current element.
+	Key() Object
+
+	// Value returns the value of the current element.
+	Value() Object
+}
+
+// ArrayIterator is an iterator for an array.
+type ArrayIterator struct {
+	ObjectImpl
+	v []Object
+	i int
+	l int
+}
+
+// TypeName returns the name of the type.
+func (i *ArrayIterator) TypeName() string {
+	return "array-iterator"
+}
+
+func (i *ArrayIterator) String() string {
+	return "<array-iterator>"
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (i *ArrayIterator) IsFalsy() bool {
+	return true
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (i *ArrayIterator) Equals(Object) bool {
+	return false
+}
+
+// Copy returns a copy of the type.
+func (i *ArrayIterator) Copy() Object {
+	return &ArrayIterator{v: i.v, i: i.i, l: i.l}
+}
+
+// Next returns true if there are more elements to iterate.
+func (i *ArrayIterator) Next() bool {
+	i.i++
+	return i.i <= i.l
+}
+
+// Key returns the key or index value of the current element.
+func (i *ArrayIterator) Key() Object {
+	return &Int{Value: int64(i.i - 1)}
+}
+
+// Value returns the value of the current element.
+func (i *ArrayIterator) Value() Object {
+	return i.v[i.i-1]
+}
+
+// BytesIterator represents an iterator for a string.
+type BytesIterator struct {
+	ObjectImpl
+	v []byte
+	i int
+	l int
+}
+
+// TypeName returns the name of the type.
+func (i *BytesIterator) TypeName() string {
+	return "bytes-iterator"
+}
+
+func (i *BytesIterator) String() string {
+	return "<bytes-iterator>"
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (i *BytesIterator) Equals(Object) bool {
+	return false
+}
+
+// Copy returns a copy of the type.
+func (i *BytesIterator) Copy() Object {
+	return &BytesIterator{v: i.v, i: i.i, l: i.l}
+}
+
+// Next returns true if there are more elements to iterate.
+func (i *BytesIterator) Next() bool {
+	i.i++
+	return i.i <= i.l
+}
+
+// Key returns the key or index value of the current element.
+func (i *BytesIterator) Key() Object {
+	return &Int{Value: int64(i.i - 1)}
+}
+
+// Value returns the value of the current element.
+func (i *BytesIterator) Value() Object {
+	return &Int{Value: int64(i.v[i.i-1])}
+}
+
+// MapIterator represents an iterator for the map.
+type MapIterator struct {
+	ObjectImpl
+	v map[string]Object
+	k []string
+	i int
+	l int
+}
+
+// TypeName returns the name of the type.
+func (i *MapIterator) TypeName() string {
+	return "map-iterator"
+}
+
+func (i *MapIterator) String() string {
+	return "<map-iterator>"
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (i *MapIterator) IsFalsy() bool {
+	return true
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (i *MapIterator) Equals(Object) bool {
+	return false
+}
+
+// Copy returns a copy of the type.
+func (i *MapIterator) Copy() Object {
+	return &MapIterator{v: i.v, k: i.k, i: i.i, l: i.l}
+}
+
+// Next returns true if there are more elements to iterate.
+func (i *MapIterator) Next() bool {
+	i.i++
+	return i.i <= i.l
+}
+
+// Key returns the key or index value of the current element.
+func (i *MapIterator) Key() Object {
+	k := i.k[i.i-1]
+	return &String{Value: k}
+}
+
+// Value returns the value of the current element.
+func (i *MapIterator) Value() Object {
+	k := i.k[i.i-1]
+	return i.v[k]
+}
+
+// StringIterator represents an iterator for a string.
+type StringIterator struct {
+	ObjectImpl
+	v []rune
+	i int
+	l int
+}
+
+// TypeName returns the name of the type.
+func (i *StringIterator) TypeName() string {
+	return "string-iterator"
+}
+
+func (i *StringIterator) String() string {
+	return "<string-iterator>"
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (i *StringIterator) IsFalsy() bool {
+	return true
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (i *StringIterator) Equals(Object) bool {
+	return false
+}
+
+// Copy returns a copy of the type.
+func (i *StringIterator) Copy() Object {
+	return &StringIterator{v: i.v, i: i.i, l: i.l}
+}
+
+// Next returns true if there are more elements to iterate.
+func (i *StringIterator) Next() bool {
+	i.i++
+	return i.i <= i.l
+}
+
+// Key returns the key or index value of the current element.
+func (i *StringIterator) Key() Object {
+	return &Int{Value: int64(i.i - 1)}
+}
+
+// Value returns the value of the current element.
+func (i *StringIterator) Value() Object {
+	return &Char{Value: i.v[i.i-1]}
+}
diff --git a/vendor/github.com/d5/tengo/objects/module_map.go b/vendor/github.com/d5/tengo/v2/modules.go
index 874b8a2b..c8fcde7f 100644
--- a/vendor/github.com/d5/tengo/objects/module_map.go
+++ b/vendor/github.com/d5/tengo/v2/modules.go
@@ -1,7 +1,13 @@
-package objects
+package tengo
 
-// ModuleMap represents a set of named modules.
-// Use NewModuleMap to create a new module map.
+// Importable interface represents importable module instance.
+type Importable interface {
+	// Import should return either an Object or module source code ([]byte).
+	Import(moduleName string) (interface{}, error)
+}
+
+// ModuleMap represents a set of named modules. Use NewModuleMap to create a
+// new module map.
 type ModuleMap struct {
 	m map[string]Importable
 }
@@ -33,21 +39,21 @@ func (m *ModuleMap) Remove(name string) {
 	delete(m.m, name)
 }
 
-// Get returns an import module identified by name.
-// It returns if the name is not found.
+// Get returns an import module identified by name. It returns if the name is
+// not found.
 func (m *ModuleMap) Get(name string) Importable {
 	return m.m[name]
 }
 
-// GetBuiltinModule returns a builtin module identified by name.
-// It returns if the name is not found or the module is not a builtin module.
+// GetBuiltinModule returns a builtin module identified by name. It returns
+// if the name is not found or the module is not a builtin module.
 func (m *ModuleMap) GetBuiltinModule(name string) *BuiltinModule {
 	mod, _ := m.m[name].(*BuiltinModule)
 	return mod
 }
 
-// GetSourceModule returns a source module identified by name.
-// It returns if the name is not found or the module is not a source module.
+// GetSourceModule returns a source module identified by name. It returns if
+// the name is not found or the module is not a source module.
 func (m *ModuleMap) GetSourceModule(name string) *SourceModule {
 	mod, _ := m.m[name].(*SourceModule)
 	return mod
@@ -75,3 +81,13 @@ func (m *ModuleMap) AddMap(o *ModuleMap) {
 		m.m[name] = mod
 	}
 }
+
+// SourceModule is an importable module that's written in Tengo.
+type SourceModule struct {
+	Src []byte
+}
+
+// Import returns a module source code.
+func (m *SourceModule) Import(_ string) (interface{}, error) {
+	return m.Src, nil
+}
diff --git a/vendor/github.com/d5/tengo/v2/objects.go b/vendor/github.com/d5/tengo/v2/objects.go
new file mode 100644
index 00000000..27c1d493
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/objects.go
@@ -0,0 +1,1581 @@
+package tengo
+
+import (
+	"bytes"
+	"fmt"
+	"math"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/d5/tengo/v2/parser"
+	"github.com/d5/tengo/v2/token"
+)
+
+var (
+	// TrueValue represents a true value.
+	TrueValue Object = &Bool{value: true}
+
+	// FalseValue represents a false value.
+	FalseValue Object = &Bool{value: false}
+
+	// UndefinedValue represents an undefined value.
+	UndefinedValue Object = &Undefined{}
+)
+
+// Object represents an object in the VM.
+type Object interface {
+	// TypeName should return the name of the type.
+	TypeName() string
+
+	// String should return a string representation of the type's value.
+	String() string
+
+	// BinaryOp should return another object that is the result of a given
+	// binary operator and a right-hand side object. If BinaryOp returns an
+	// error, the VM will treat it as a run-time error.
+	BinaryOp(op token.Token, rhs Object) (Object, error)
+
+	// IsFalsy should return true if the value of the type should be considered
+	// as falsy.
+	IsFalsy() bool
+
+	// Equals should return true if the value of the type should be considered
+	// as equal to the value of another object.
+	Equals(another Object) bool
+
+	// Copy should return a copy of the type (and its value). Copy function
+	// will be used for copy() builtin function which is expected to deep-copy
+	// the values generally.
+	Copy() Object
+
+	// IndexGet should take an index Object and return a result Object or an
+	// error for indexable objects. Indexable is an object that can take an
+	// index and return an object. If error is returned, the runtime will treat
+	// it as a run-time error and ignore returned value. If Object is not
+	// indexable, ErrNotIndexable should be returned as error. If nil is
+	// returned as value, it will be converted to UndefinedToken value by the
+	// runtime.
+	IndexGet(index Object) (value Object, err error)
+
+	// IndexSet should take an index Object and a value Object for index
+	// assignable objects. Index assignable is an object that can take an index
+	// and a value on the left-hand side of the assignment statement. If Object
+	// is not index assignable, ErrNotIndexAssignable should be returned as
+	// error. If an error is returned, it will be treated as a run-time error.
+	IndexSet(index, value Object) error
+
+	// Iterate should return an Iterator for the type.
+	Iterate() Iterator
+
+	// CanIterate should return whether the Object can be Iterated.
+	CanIterate() bool
+
+	// Call should take an arbitrary number of arguments and returns a return
+	// value and/or an error, which the VM will consider as a run-time error.
+	Call(args ...Object) (ret Object, err error)
+
+	// CanCall should return whether the Object can be Called.
+	CanCall() bool
+}
+
+// ObjectImpl represents a default Object Implementation. To defined a new
+// value type, one can embed ObjectImpl in their type declarations to avoid
+// implementing all non-significant methods. TypeName() and String() methods
+// still need to be implemented.
+type ObjectImpl struct {
+}
+
+// TypeName returns the name of the type.
+func (o *ObjectImpl) TypeName() string {
+	panic(ErrNotImplemented)
+}
+
+func (o *ObjectImpl) String() string {
+	panic(ErrNotImplemented)
+}
+
+// BinaryOp returns another object that is the result of a given binary
+// operator and a right-hand side object.
+func (o *ObjectImpl) BinaryOp(_ token.Token, _ Object) (Object, error) {
+	return nil, ErrInvalidOperator
+}
+
+// Copy returns a copy of the type.
+func (o *ObjectImpl) Copy() Object {
+	return nil
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *ObjectImpl) IsFalsy() bool {
+	return false
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *ObjectImpl) Equals(x Object) bool {
+	return o == x
+}
+
+// IndexGet returns an element at a given index.
+func (o *ObjectImpl) IndexGet(_ Object) (res Object, err error) {
+	return nil, ErrNotIndexable
+}
+
+// IndexSet sets an element at a given index.
+func (o *ObjectImpl) IndexSet(_, _ Object) (err error) {
+	return ErrNotIndexAssignable
+}
+
+// Iterate returns an iterator.
+func (o *ObjectImpl) Iterate() Iterator {
+	return nil
+}
+
+// CanIterate returns whether the Object can be Iterated.
+func (o *ObjectImpl) CanIterate() bool {
+	return false
+}
+
+// Call takes an arbitrary number of arguments and returns a return value
+// and/or an error.
+func (o *ObjectImpl) Call(_ ...Object) (ret Object, err error) {
+	return nil, nil
+}
+
+// CanCall returns whether the Object can be Called.
+func (o *ObjectImpl) CanCall() bool {
+	return false
+}
+
+// Array represents an array of objects.
+type Array struct {
+	ObjectImpl
+	Value []Object
+}
+
+// TypeName returns the name of the type.
+func (o *Array) TypeName() string {
+	return "array"
+}
+
+func (o *Array) String() string {
+	var elements []string
+	for _, e := range o.Value {
+		elements = append(elements, e.String())
+	}
+	return fmt.Sprintf("[%s]", strings.Join(elements, ", "))
+}
+
+// BinaryOp returns another object that is the result of a given binary
+// operator and a right-hand side object.
+func (o *Array) BinaryOp(op token.Token, rhs Object) (Object, error) {
+	if rhs, ok := rhs.(*Array); ok {
+		switch op {
+		case token.Add:
+			if len(rhs.Value) == 0 {
+				return o, nil
+			}
+			return &Array{Value: append(o.Value, rhs.Value...)}, nil
+		}
+	}
+	return nil, ErrInvalidOperator
+}
+
+// Copy returns a copy of the type.
+func (o *Array) Copy() Object {
+	var c []Object
+	for _, elem := range o.Value {
+		c = append(c, elem.Copy())
+	}
+	return &Array{Value: c}
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *Array) IsFalsy() bool {
+	return len(o.Value) == 0
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *Array) Equals(x Object) bool {
+	var xVal []Object
+	switch x := x.(type) {
+	case *Array:
+		xVal = x.Value
+	case *ImmutableArray:
+		xVal = x.Value
+	default:
+		return false
+	}
+	if len(o.Value) != len(xVal) {
+		return false
+	}
+	for i, e := range o.Value {
+		if !e.Equals(xVal[i]) {
+			return false
+		}
+	}
+	return true
+}
+
+// IndexGet returns an element at a given index.
+func (o *Array) IndexGet(index Object) (res Object, err error) {
+	intIdx, ok := index.(*Int)
+	if !ok {
+		err = ErrInvalidIndexType
+		return
+	}
+	idxVal := int(intIdx.Value)
+	if idxVal < 0 || idxVal >= len(o.Value) {
+		res = UndefinedValue
+		return
+	}
+	res = o.Value[idxVal]
+	return
+}
+
+// IndexSet sets an element at a given index.
+func (o *Array) IndexSet(index, value Object) (err error) {
+	intIdx, ok := ToInt(index)
+	if !ok {
+		err = ErrInvalidIndexType
+		return
+	}
+	if intIdx < 0 || intIdx >= len(o.Value) {
+		err = ErrIndexOutOfBounds
+		return
+	}
+	o.Value[intIdx] = value
+	return nil
+}
+
+// Iterate creates an array iterator.
+func (o *Array) Iterate() Iterator {
+	return &ArrayIterator{
+		v: o.Value,
+		l: len(o.Value),
+	}
+}
+
+// CanIterate returns whether the Object can be Iterated.
+func (o *Array) CanIterate() bool {
+	return true
+}
+
+// Bool represents a boolean value.
+type Bool struct {
+	ObjectImpl
+
+	// this is intentionally non-public to force using objects.TrueValue and
+	// FalseValue always
+	value bool
+}
+
+func (o *Bool) String() string {
+	if o.value {
+		return "true"
+	}
+
+	return "false"
+}
+
+// TypeName returns the name of the type.
+func (o *Bool) TypeName() string {
+	return "bool"
+}
+
+// Copy returns a copy of the type.
+func (o *Bool) Copy() Object {
+	return o
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *Bool) IsFalsy() bool {
+	return !o.value
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *Bool) Equals(x Object) bool {
+	return o == x
+}
+
+// GobDecode decodes bool value from input bytes.
+func (o *Bool) GobDecode(b []byte) (err error) {
+	o.value = b[0] == 1
+	return
+}
+
+// GobEncode encodes bool values into bytes.
+func (o *Bool) GobEncode() (b []byte, err error) {
+	if o.value {
+		b = []byte{1}
+	} else {
+		b = []byte{0}
+	}
+	return
+}
+
+// BuiltinFunction represents a builtin function.
+type BuiltinFunction struct {
+	ObjectImpl
+	Name  string
+	Value CallableFunc
+}
+
+// TypeName returns the name of the type.
+func (o *BuiltinFunction) TypeName() string {
+	return "builtin-function:" + o.Name
+}
+
+func (o *BuiltinFunction) String() string {
+	return "<builtin-function>"
+}
+
+// Copy returns a copy of the type.
+func (o *BuiltinFunction) Copy() Object {
+	return &BuiltinFunction{Value: o.Value}
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *BuiltinFunction) Equals(_ Object) bool {
+	return false
+}
+
+// Call executes a builtin function.
+func (o *BuiltinFunction) Call(args ...Object) (Object, error) {
+	return o.Value(args...)
+}
+
+// CanCall returns whether the Object can be Called.
+func (o *BuiltinFunction) CanCall() bool {
+	return true
+}
+
+// BuiltinModule is an importable module that's written in Go.
+type BuiltinModule struct {
+	Attrs map[string]Object
+}
+
+// Import returns an immutable map for the module.
+func (m *BuiltinModule) Import(moduleName string) (interface{}, error) {
+	return m.AsImmutableMap(moduleName), nil
+}
+
+// AsImmutableMap converts builtin module into an immutable map.
+func (m *BuiltinModule) AsImmutableMap(moduleName string) *ImmutableMap {
+	attrs := make(map[string]Object, len(m.Attrs))
+	for k, v := range m.Attrs {
+		attrs[k] = v.Copy()
+	}
+	attrs["__module_name__"] = &String{Value: moduleName}
+	return &ImmutableMap{Value: attrs}
+}
+
+// Bytes represents a byte array.
+type Bytes struct {
+	ObjectImpl
+	Value []byte
+}
+
+func (o *Bytes) String() string {
+	return string(o.Value)
+}
+
+// TypeName returns the name of the type.
+func (o *Bytes) TypeName() string {
+	return "bytes"
+}
+
+// BinaryOp returns another object that is the result of a given binary
+// operator and a right-hand side object.
+func (o *Bytes) BinaryOp(op token.Token, rhs Object) (Object, error) {
+	switch op {
+	case token.Add:
+		switch rhs := rhs.(type) {
+		case *Bytes:
+			if len(o.Value)+len(rhs.Value) > MaxBytesLen {
+				return nil, ErrBytesLimit
+			}
+			return &Bytes{Value: append(o.Value, rhs.Value...)}, nil
+		}
+	}
+	return nil, ErrInvalidOperator
+}
+
+// Copy returns a copy of the type.
+func (o *Bytes) Copy() Object {
+	return &Bytes{Value: append([]byte{}, o.Value...)}
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *Bytes) IsFalsy() bool {
+	return len(o.Value) == 0
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *Bytes) Equals(x Object) bool {
+	t, ok := x.(*Bytes)
+	if !ok {
+		return false
+	}
+	return bytes.Equal(o.Value, t.Value)
+}
+
+// IndexGet returns an element (as Int) at a given index.
+func (o *Bytes) IndexGet(index Object) (res Object, err error) {
+	intIdx, ok := index.(*Int)
+	if !ok {
+		err = ErrInvalidIndexType
+		return
+	}
+	idxVal := int(intIdx.Value)
+	if idxVal < 0 || idxVal >= len(o.Value) {
+		res = UndefinedValue
+		return
+	}
+	res = &Int{Value: int64(o.Value[idxVal])}
+	return
+}
+
+// Iterate creates a bytes iterator.
+func (o *Bytes) Iterate() Iterator {
+	return &BytesIterator{
+		v: o.Value,
+		l: len(o.Value),
+	}
+}
+
+// CanIterate returns whether the Object can be Iterated.
+func (o *Bytes) CanIterate() bool {
+	return true
+}
+
+// Char represents a character value.
+type Char struct {
+	ObjectImpl
+	Value rune
+}
+
+func (o *Char) String() string {
+	return string(o.Value)
+}
+
+// TypeName returns the name of the type.
+func (o *Char) TypeName() string {
+	return "char"
+}
+
+// BinaryOp returns another object that is the result of a given binary
+// operator and a right-hand side object.
+func (o *Char) BinaryOp(op token.Token, rhs Object) (Object, error) {
+	switch rhs := rhs.(type) {
+	case *Char:
+		switch op {
+		case token.Add:
+			r := o.Value + rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Char{Value: r}, nil
+		case token.Sub:
+			r := o.Value - rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Char{Value: r}, nil
+		case token.Less:
+			if o.Value < rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.Greater:
+			if o.Value > rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.LessEq:
+			if o.Value <= rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.GreaterEq:
+			if o.Value >= rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		}
+	case *Int:
+		switch op {
+		case token.Add:
+			r := o.Value + rune(rhs.Value)
+			if r == o.Value {
+				return o, nil
+			}
+			return &Char{Value: r}, nil
+		case token.Sub:
+			r := o.Value - rune(rhs.Value)
+			if r == o.Value {
+				return o, nil
+			}
+			return &Char{Value: r}, nil
+		case token.Less:
+			if int64(o.Value) < rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.Greater:
+			if int64(o.Value) > rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.LessEq:
+			if int64(o.Value) <= rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.GreaterEq:
+			if int64(o.Value) >= rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		}
+	}
+	return nil, ErrInvalidOperator
+}
+
+// Copy returns a copy of the type.
+func (o *Char) Copy() Object {
+	return &Char{Value: o.Value}
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *Char) IsFalsy() bool {
+	return o.Value == 0
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *Char) Equals(x Object) bool {
+	t, ok := x.(*Char)
+	if !ok {
+		return false
+	}
+	return o.Value == t.Value
+}
+
+// CompiledFunction represents a compiled function.
+type CompiledFunction struct {
+	ObjectImpl
+	Instructions  []byte
+	NumLocals     int // number of local variables (including function parameters)
+	NumParameters int
+	VarArgs       bool
+	SourceMap     map[int]parser.Pos
+	Free          []*ObjectPtr
+}
+
+// TypeName returns the name of the type.
+func (o *CompiledFunction) TypeName() string {
+	return "compiled-function"
+}
+
+func (o *CompiledFunction) String() string {
+	return "<compiled-function>"
+}
+
+// Copy returns a copy of the type.
+func (o *CompiledFunction) Copy() Object {
+	return &CompiledFunction{
+		Instructions:  append([]byte{}, o.Instructions...),
+		NumLocals:     o.NumLocals,
+		NumParameters: o.NumParameters,
+		VarArgs:       o.VarArgs,
+		Free:          append([]*ObjectPtr{}, o.Free...), // DO NOT Copy() of elements; these are variable pointers
+	}
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *CompiledFunction) Equals(_ Object) bool {
+	return false
+}
+
+// SourcePos returns the source position of the instruction at ip.
+func (o *CompiledFunction) SourcePos(ip int) parser.Pos {
+	for ip >= 0 {
+		if p, ok := o.SourceMap[ip]; ok {
+			return p
+		}
+		ip--
+	}
+	return parser.NoPos
+}
+
+// CanCall returns whether the Object can be Called.
+func (o *CompiledFunction) CanCall() bool {
+	return true
+}
+
+// Error represents an error value.
+type Error struct {
+	ObjectImpl
+	Value Object
+}
+
+// TypeName returns the name of the type.
+func (o *Error) TypeName() string {
+	return "error"
+}
+
+func (o *Error) String() string {
+	if o.Value != nil {
+		return fmt.Sprintf("error: %s", o.Value.String())
+	}
+	return "error"
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *Error) IsFalsy() bool {
+	return true // error is always false.
+}
+
+// Copy returns a copy of the type.
+func (o *Error) Copy() Object {
+	return &Error{Value: o.Value.Copy()}
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *Error) Equals(x Object) bool {
+	return o == x // pointer equality
+}
+
+// IndexGet returns an element at a given index.
+func (o *Error) IndexGet(index Object) (res Object, err error) {
+	if strIdx, _ := ToString(index); strIdx != "value" {
+		err = ErrInvalidIndexOnError
+		return
+	}
+	res = o.Value
+	return
+}
+
+// Float represents a floating point number value.
+type Float struct {
+	ObjectImpl
+	Value float64
+}
+
+func (o *Float) String() string {
+	return strconv.FormatFloat(o.Value, 'f', -1, 64)
+}
+
+// TypeName returns the name of the type.
+func (o *Float) TypeName() string {
+	return "float"
+}
+
+// BinaryOp returns another object that is the result of a given binary
+// operator and a right-hand side object.
+func (o *Float) BinaryOp(op token.Token, rhs Object) (Object, error) {
+	switch rhs := rhs.(type) {
+	case *Float:
+		switch op {
+		case token.Add:
+			r := o.Value + rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Float{Value: r}, nil
+		case token.Sub:
+			r := o.Value - rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Float{Value: r}, nil
+		case token.Mul:
+			r := o.Value * rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Float{Value: r}, nil
+		case token.Quo:
+			r := o.Value / rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Float{Value: r}, nil
+		case token.Less:
+			if o.Value < rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.Greater:
+			if o.Value > rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.LessEq:
+			if o.Value <= rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.GreaterEq:
+			if o.Value >= rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		}
+	case *Int:
+		switch op {
+		case token.Add:
+			r := o.Value + float64(rhs.Value)
+			if r == o.Value {
+				return o, nil
+			}
+			return &Float{Value: r}, nil
+		case token.Sub:
+			r := o.Value - float64(rhs.Value)
+			if r == o.Value {
+				return o, nil
+			}
+			return &Float{Value: r}, nil
+		case token.Mul:
+			r := o.Value * float64(rhs.Value)
+			if r == o.Value {
+				return o, nil
+			}
+			return &Float{Value: r}, nil
+		case token.Quo:
+			r := o.Value / float64(rhs.Value)
+			if r == o.Value {
+				return o, nil
+			}
+			return &Float{Value: r}, nil
+		case token.Less:
+			if o.Value < float64(rhs.Value) {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.Greater:
+			if o.Value > float64(rhs.Value) {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.LessEq:
+			if o.Value <= float64(rhs.Value) {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.GreaterEq:
+			if o.Value >= float64(rhs.Value) {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		}
+	}
+	return nil, ErrInvalidOperator
+}
+
+// Copy returns a copy of the type.
+func (o *Float) Copy() Object {
+	return &Float{Value: o.Value}
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *Float) IsFalsy() bool {
+	return math.IsNaN(o.Value)
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *Float) Equals(x Object) bool {
+	t, ok := x.(*Float)
+	if !ok {
+		return false
+	}
+	return o.Value == t.Value
+}
+
+// ImmutableArray represents an immutable array of objects.
+type ImmutableArray struct {
+	ObjectImpl
+	Value []Object
+}
+
+// TypeName returns the name of the type.
+func (o *ImmutableArray) TypeName() string {
+	return "immutable-array"
+}
+
+func (o *ImmutableArray) String() string {
+	var elements []string
+	for _, e := range o.Value {
+		elements = append(elements, e.String())
+	}
+	return fmt.Sprintf("[%s]", strings.Join(elements, ", "))
+}
+
+// BinaryOp returns another object that is the result of a given binary
+// operator and a right-hand side object.
+func (o *ImmutableArray) BinaryOp(op token.Token, rhs Object) (Object, error) {
+	if rhs, ok := rhs.(*ImmutableArray); ok {
+		switch op {
+		case token.Add:
+			return &Array{Value: append(o.Value, rhs.Value...)}, nil
+		}
+	}
+	return nil, ErrInvalidOperator
+}
+
+// Copy returns a copy of the type.
+func (o *ImmutableArray) Copy() Object {
+	var c []Object
+	for _, elem := range o.Value {
+		c = append(c, elem.Copy())
+	}
+	return &Array{Value: c}
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *ImmutableArray) IsFalsy() bool {
+	return len(o.Value) == 0
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *ImmutableArray) Equals(x Object) bool {
+	var xVal []Object
+	switch x := x.(type) {
+	case *Array:
+		xVal = x.Value
+	case *ImmutableArray:
+		xVal = x.Value
+	default:
+		return false
+	}
+	if len(o.Value) != len(xVal) {
+		return false
+	}
+	for i, e := range o.Value {
+		if !e.Equals(xVal[i]) {
+			return false
+		}
+	}
+	return true
+}
+
+// IndexGet returns an element at a given index.
+func (o *ImmutableArray) IndexGet(index Object) (res Object, err error) {
+	intIdx, ok := index.(*Int)
+	if !ok {
+		err = ErrInvalidIndexType
+		return
+	}
+	idxVal := int(intIdx.Value)
+	if idxVal < 0 || idxVal >= len(o.Value) {
+		res = UndefinedValue
+		return
+	}
+	res = o.Value[idxVal]
+	return
+}
+
+// Iterate creates an array iterator.
+func (o *ImmutableArray) Iterate() Iterator {
+	return &ArrayIterator{
+		v: o.Value,
+		l: len(o.Value),
+	}
+}
+
+// CanIterate returns whether the Object can be Iterated.
+func (o *ImmutableArray) CanIterate() bool {
+	return true
+}
+
+// ImmutableMap represents an immutable map object.
+type ImmutableMap struct {
+	ObjectImpl
+	Value map[string]Object
+}
+
+// TypeName returns the name of the type.
+func (o *ImmutableMap) TypeName() string {
+	return "immutable-map"
+}
+
+func (o *ImmutableMap) String() string {
+	var pairs []string
+	for k, v := range o.Value {
+		pairs = append(pairs, fmt.Sprintf("%s: %s", k, v.String()))
+	}
+	return fmt.Sprintf("{%s}", strings.Join(pairs, ", "))
+}
+
+// Copy returns a copy of the type.
+func (o *ImmutableMap) Copy() Object {
+	c := make(map[string]Object)
+	for k, v := range o.Value {
+		c[k] = v.Copy()
+	}
+	return &Map{Value: c}
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *ImmutableMap) IsFalsy() bool {
+	return len(o.Value) == 0
+}
+
+// IndexGet returns the value for the given key.
+func (o *ImmutableMap) IndexGet(index Object) (res Object, err error) {
+	strIdx, ok := ToString(index)
+	if !ok {
+		err = ErrInvalidIndexType
+		return
+	}
+	res, ok = o.Value[strIdx]
+	if !ok {
+		res = UndefinedValue
+	}
+	return
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *ImmutableMap) Equals(x Object) bool {
+	var xVal map[string]Object
+	switch x := x.(type) {
+	case *Map:
+		xVal = x.Value
+	case *ImmutableMap:
+		xVal = x.Value
+	default:
+		return false
+	}
+	if len(o.Value) != len(xVal) {
+		return false
+	}
+	for k, v := range o.Value {
+		tv := xVal[k]
+		if !v.Equals(tv) {
+			return false
+		}
+	}
+	return true
+}
+
+// Iterate creates an immutable map iterator.
+func (o *ImmutableMap) Iterate() Iterator {
+	var keys []string
+	for k := range o.Value {
+		keys = append(keys, k)
+	}
+	return &MapIterator{
+		v: o.Value,
+		k: keys,
+		l: len(keys),
+	}
+}
+
+// CanIterate returns whether the Object can be Iterated.
+func (o *ImmutableMap) CanIterate() bool {
+	return true
+}
+
+// Int represents an integer value.
+type Int struct {
+	ObjectImpl
+	Value int64
+}
+
+func (o *Int) String() string {
+	return strconv.FormatInt(o.Value, 10)
+}
+
+// TypeName returns the name of the type.
+func (o *Int) TypeName() string {
+	return "int"
+}
+
+// BinaryOp returns another object that is the result of a given binary
+// operator and a right-hand side object.
+func (o *Int) BinaryOp(op token.Token, rhs Object) (Object, error) {
+	switch rhs := rhs.(type) {
+	case *Int:
+		switch op {
+		case token.Add:
+			r := o.Value + rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Int{Value: r}, nil
+		case token.Sub:
+			r := o.Value - rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Int{Value: r}, nil
+		case token.Mul:
+			r := o.Value * rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Int{Value: r}, nil
+		case token.Quo:
+			r := o.Value / rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Int{Value: r}, nil
+		case token.Rem:
+			r := o.Value % rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Int{Value: r}, nil
+		case token.And:
+			r := o.Value & rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Int{Value: r}, nil
+		case token.Or:
+			r := o.Value | rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Int{Value: r}, nil
+		case token.Xor:
+			r := o.Value ^ rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Int{Value: r}, nil
+		case token.AndNot:
+			r := o.Value &^ rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Int{Value: r}, nil
+		case token.Shl:
+			r := o.Value << uint64(rhs.Value)
+			if r == o.Value {
+				return o, nil
+			}
+			return &Int{Value: r}, nil
+		case token.Shr:
+			r := o.Value >> uint64(rhs.Value)
+			if r == o.Value {
+				return o, nil
+			}
+			return &Int{Value: r}, nil
+		case token.Less:
+			if o.Value < rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.Greater:
+			if o.Value > rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.LessEq:
+			if o.Value <= rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.GreaterEq:
+			if o.Value >= rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		}
+	case *Float:
+		switch op {
+		case token.Add:
+			return &Float{Value: float64(o.Value) + rhs.Value}, nil
+		case token.Sub:
+			return &Float{Value: float64(o.Value) - rhs.Value}, nil
+		case token.Mul:
+			return &Float{Value: float64(o.Value) * rhs.Value}, nil
+		case token.Quo:
+			return &Float{Value: float64(o.Value) / rhs.Value}, nil
+		case token.Less:
+			if float64(o.Value) < rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.Greater:
+			if float64(o.Value) > rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.LessEq:
+			if float64(o.Value) <= rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.GreaterEq:
+			if float64(o.Value) >= rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		}
+	case *Char:
+		switch op {
+		case token.Add:
+			return &Char{Value: rune(o.Value) + rhs.Value}, nil
+		case token.Sub:
+			return &Char{Value: rune(o.Value) - rhs.Value}, nil
+		case token.Less:
+			if o.Value < int64(rhs.Value) {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.Greater:
+			if o.Value > int64(rhs.Value) {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.LessEq:
+			if o.Value <= int64(rhs.Value) {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.GreaterEq:
+			if o.Value >= int64(rhs.Value) {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		}
+	}
+	return nil, ErrInvalidOperator
+}
+
+// Copy returns a copy of the type.
+func (o *Int) Copy() Object {
+	return &Int{Value: o.Value}
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *Int) IsFalsy() bool {
+	return o.Value == 0
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *Int) Equals(x Object) bool {
+	t, ok := x.(*Int)
+	if !ok {
+		return false
+	}
+	return o.Value == t.Value
+}
+
+// Map represents a map of objects.
+type Map struct {
+	ObjectImpl
+	Value map[string]Object
+}
+
+// TypeName returns the name of the type.
+func (o *Map) TypeName() string {
+	return "map"
+}
+
+func (o *Map) String() string {
+	var pairs []string
+	for k, v := range o.Value {
+		pairs = append(pairs, fmt.Sprintf("%s: %s", k, v.String()))
+	}
+	return fmt.Sprintf("{%s}", strings.Join(pairs, ", "))
+}
+
+// Copy returns a copy of the type.
+func (o *Map) Copy() Object {
+	c := make(map[string]Object)
+	for k, v := range o.Value {
+		c[k] = v.Copy()
+	}
+	return &Map{Value: c}
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *Map) IsFalsy() bool {
+	return len(o.Value) == 0
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *Map) Equals(x Object) bool {
+	var xVal map[string]Object
+	switch x := x.(type) {
+	case *Map:
+		xVal = x.Value
+	case *ImmutableMap:
+		xVal = x.Value
+	default:
+		return false
+	}
+	if len(o.Value) != len(xVal) {
+		return false
+	}
+	for k, v := range o.Value {
+		tv := xVal[k]
+		if !v.Equals(tv) {
+			return false
+		}
+	}
+	return true
+}
+
+// IndexGet returns the value for the given key.
+func (o *Map) IndexGet(index Object) (res Object, err error) {
+	strIdx, ok := ToString(index)
+	if !ok {
+		err = ErrInvalidIndexType
+		return
+	}
+	res, ok = o.Value[strIdx]
+	if !ok {
+		res = UndefinedValue
+	}
+	return
+}
+
+// IndexSet sets the value for the given key.
+func (o *Map) IndexSet(index, value Object) (err error) {
+	strIdx, ok := ToString(index)
+	if !ok {
+		err = ErrInvalidIndexType
+		return
+	}
+	o.Value[strIdx] = value
+	return nil
+}
+
+// Iterate creates a map iterator.
+func (o *Map) Iterate() Iterator {
+	var keys []string
+	for k := range o.Value {
+		keys = append(keys, k)
+	}
+	return &MapIterator{
+		v: o.Value,
+		k: keys,
+		l: len(keys),
+	}
+}
+
+// CanIterate returns whether the Object can be Iterated.
+func (o *Map) CanIterate() bool {
+	return true
+}
+
+// ObjectPtr represents a free variable.
+type ObjectPtr struct {
+	ObjectImpl
+	Value *Object
+}
+
+func (o *ObjectPtr) String() string {
+	return "free-var"
+}
+
+// TypeName returns the name of the type.
+func (o *ObjectPtr) TypeName() string {
+	return "<free-var>"
+}
+
+// Copy returns a copy of the type.
+func (o *ObjectPtr) Copy() Object {
+	return o
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *ObjectPtr) IsFalsy() bool {
+	return o.Value == nil
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *ObjectPtr) Equals(x Object) bool {
+	return o == x
+}
+
+// String represents a string value.
+type String struct {
+	ObjectImpl
+	Value   string
+	runeStr []rune
+}
+
+// TypeName returns the name of the type.
+func (o *String) TypeName() string {
+	return "string"
+}
+
+func (o *String) String() string {
+	return strconv.Quote(o.Value)
+}
+
+// BinaryOp returns another object that is the result of a given binary
+// operator and a right-hand side object.
+func (o *String) BinaryOp(op token.Token, rhs Object) (Object, error) {
+	switch op {
+	case token.Add:
+		switch rhs := rhs.(type) {
+		case *String:
+			if len(o.Value)+len(rhs.Value) > MaxStringLen {
+				return nil, ErrStringLimit
+			}
+			return &String{Value: o.Value + rhs.Value}, nil
+		default:
+			rhsStr := rhs.String()
+			if len(o.Value)+len(rhsStr) > MaxStringLen {
+				return nil, ErrStringLimit
+			}
+			return &String{Value: o.Value + rhsStr}, nil
+		}
+	}
+	return nil, ErrInvalidOperator
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *String) IsFalsy() bool {
+	return len(o.Value) == 0
+}
+
+// Copy returns a copy of the type.
+func (o *String) Copy() Object {
+	return &String{Value: o.Value}
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *String) Equals(x Object) bool {
+	t, ok := x.(*String)
+	if !ok {
+		return false
+	}
+	return o.Value == t.Value
+}
+
+// IndexGet returns a character at a given index.
+func (o *String) IndexGet(index Object) (res Object, err error) {
+	intIdx, ok := index.(*Int)
+	if !ok {
+		err = ErrInvalidIndexType
+		return
+	}
+	idxVal := int(intIdx.Value)
+	if o.runeStr == nil {
+		o.runeStr = []rune(o.Value)
+	}
+	if idxVal < 0 || idxVal >= len(o.runeStr) {
+		res = UndefinedValue
+		return
+	}
+	res = &Char{Value: o.runeStr[idxVal]}
+	return
+}
+
+// Iterate creates a string iterator.
+func (o *String) Iterate() Iterator {
+	if o.runeStr == nil {
+		o.runeStr = []rune(o.Value)
+	}
+	return &StringIterator{
+		v: o.runeStr,
+		l: len(o.runeStr),
+	}
+}
+
+// CanIterate returns whether the Object can be Iterated.
+func (o *String) CanIterate() bool {
+	return true
+}
+
+// Time represents a time value.
+type Time struct {
+	ObjectImpl
+	Value time.Time
+}
+
+func (o *Time) String() string {
+	return o.Value.String()
+}
+
+// TypeName returns the name of the type.
+func (o *Time) TypeName() string {
+	return "time"
+}
+
+// BinaryOp returns another object that is the result of a given binary
+// operator and a right-hand side object.
+func (o *Time) BinaryOp(op token.Token, rhs Object) (Object, error) {
+	switch rhs := rhs.(type) {
+	case *Int:
+		switch op {
+		case token.Add: // time + int => time
+			if rhs.Value == 0 {
+				return o, nil
+			}
+			return &Time{Value: o.Value.Add(time.Duration(rhs.Value))}, nil
+		case token.Sub: // time - int => time
+			if rhs.Value == 0 {
+				return o, nil
+			}
+			return &Time{Value: o.Value.Add(time.Duration(-rhs.Value))}, nil
+		}
+	case *Time:
+		switch op {
+		case token.Sub: // time - time => int (duration)
+			return &Int{Value: int64(o.Value.Sub(rhs.Value))}, nil
+		case token.Less: // time < time => bool
+			if o.Value.Before(rhs.Value) {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.Greater:
+			if o.Value.After(rhs.Value) {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.LessEq:
+			if o.Value.Equal(rhs.Value) || o.Value.Before(rhs.Value) {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.GreaterEq:
+			if o.Value.Equal(rhs.Value) || o.Value.After(rhs.Value) {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		}
+	}
+	return nil, ErrInvalidOperator
+}
+
+// Copy returns a copy of the type.
+func (o *Time) Copy() Object {
+	return &Time{Value: o.Value}
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *Time) IsFalsy() bool {
+	return o.Value.IsZero()
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *Time) Equals(x Object) bool {
+	t, ok := x.(*Time)
+	if !ok {
+		return false
+	}
+	return o.Value.Equal(t.Value)
+}
+
+// Undefined represents an undefined value.
+type Undefined struct {
+	ObjectImpl
+}
+
+// TypeName returns the name of the type.
+func (o *Undefined) TypeName() string {
+	return "undefined"
+}
+
+func (o *Undefined) String() string {
+	return "<undefined>"
+}
+
+// Copy returns a copy of the type.
+func (o *Undefined) Copy() Object {
+	return o
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *Undefined) IsFalsy() bool {
+	return true
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *Undefined) Equals(x Object) bool {
+	return o == x
+}
+
+// IndexGet returns an element at a given index.
+func (o *Undefined) IndexGet(_ Object) (Object, error) {
+	return UndefinedValue, nil
+}
+
+// Iterate creates a map iterator.
+func (o *Undefined) Iterate() Iterator {
+	return o
+}
+
+// CanIterate returns whether the Object can be Iterated.
+func (o *Undefined) CanIterate() bool {
+	return true
+}
+
+// Next returns true if there are more elements to iterate.
+func (o *Undefined) Next() bool {
+	return false
+}
+
+// Key returns the key or index value of the current element.
+func (o *Undefined) Key() Object {
+	return o
+}
+
+// Value returns the value of the current element.
+func (o *Undefined) Value() Object {
+	return o
+}
+
+// UserFunction represents a user function.
+type UserFunction struct {
+	ObjectImpl
+	Name       string
+	Value      CallableFunc
+	EncodingID string
+}
+
+// TypeName returns the name of the type.
+func (o *UserFunction) TypeName() string {
+	return "user-function:" + o.Name
+}
+
+func (o *UserFunction) String() string {
+	return "<user-function>"
+}
+
+// Copy returns a copy of the type.
+func (o *UserFunction) Copy() Object {
+	return &UserFunction{Value: o.Value}
+}
+
+// Equals returns true if the value of the type is equal to the value of
+// another object.
+func (o *UserFunction) Equals(_ Object) bool {
+	return false
+}
+
+// Call invokes a user function.
+func (o *UserFunction) Call(args ...Object) (Object, error) {
+	return o.Value(args...)
+}
+
+// CanCall returns whether the Object can be Called.
+func (o *UserFunction) CanCall() bool {
+	return true
+}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/ident_list.go b/vendor/github.com/d5/tengo/v2/parser/ast.go
index 8dd6d307..8c2f7c07 100644
--- a/vendor/github.com/d5/tengo/compiler/ast/ident_list.go
+++ b/vendor/github.com/d5/tengo/v2/parser/ast.go
@@ -1,43 +1,51 @@
-package ast
+package parser
 
 import (
 	"strings"
+)
 
-	"github.com/d5/tengo/compiler/source"
+const (
+	nullRep = "<null>"
 )
 
+// Node represents a node in the AST.
+type Node interface {
+	// Pos returns the position of first character belonging to the node.
+	Pos() Pos
+	// End returns the position of first character immediately after the node.
+	End() Pos
+	// String returns a string representation of the node.
+	String() string
+}
+
 // IdentList represents a list of identifiers.
 type IdentList struct {
-	LParen  source.Pos
+	LParen  Pos
 	VarArgs bool
 	List    []*Ident
-	RParen  source.Pos
+	RParen  Pos
 }
 
 // Pos returns the position of first character belonging to the node.
-func (n *IdentList) Pos() source.Pos {
+func (n *IdentList) Pos() Pos {
 	if n.LParen.IsValid() {
 		return n.LParen
 	}
-
 	if len(n.List) > 0 {
 		return n.List[0].Pos()
 	}
-
-	return source.NoPos
+	return NoPos
 }
 
 // End returns the position of first character immediately after the node.
-func (n *IdentList) End() source.Pos {
+func (n *IdentList) End() Pos {
 	if n.RParen.IsValid() {
 		return n.RParen + 1
 	}
-
 	if l := len(n.List); l > 0 {
 		return n.List[l-1].End()
 	}
-
-	return source.NoPos
+	return NoPos
 }
 
 // NumFields returns the number of fields.
@@ -45,7 +53,6 @@ func (n *IdentList) NumFields() int {
 	if n == nil {
 		return 0
 	}
-
 	return len(n.List)
 }
 
@@ -58,6 +65,5 @@ func (n *IdentList) String() string {
 			list = append(list, e.String())
 		}
 	}
-
 	return "(" + strings.Join(list, ", ") + ")"
 }
diff --git a/vendor/github.com/d5/tengo/v2/parser/expr.go b/vendor/github.com/d5/tengo/v2/parser/expr.go
new file mode 100644
index 00000000..71e5155b
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/parser/expr.go
@@ -0,0 +1,597 @@
+package parser
+
+import (
+	"strings"
+
+	"github.com/d5/tengo/v2/token"
+)
+
+// Expr represents an expression node in the AST.
+type Expr interface {
+	Node
+	exprNode()
+}
+
+// ArrayLit represents an array literal.
+type ArrayLit struct {
+	Elements []Expr
+	LBrack   Pos
+	RBrack   Pos
+}
+
+func (e *ArrayLit) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *ArrayLit) Pos() Pos {
+	return e.LBrack
+}
+
+// End returns the position of first character immediately after the node.
+func (e *ArrayLit) End() Pos {
+	return e.RBrack + 1
+}
+
+func (e *ArrayLit) String() string {
+	var elements []string
+	for _, m := range e.Elements {
+		elements = append(elements, m.String())
+	}
+	return "[" + strings.Join(elements, ", ") + "]"
+}
+
+// BadExpr represents a bad expression.
+type BadExpr struct {
+	From Pos
+	To   Pos
+}
+
+func (e *BadExpr) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *BadExpr) Pos() Pos {
+	return e.From
+}
+
+// End returns the position of first character immediately after the node.
+func (e *BadExpr) End() Pos {
+	return e.To
+}
+
+func (e *BadExpr) String() string {
+	return "<bad expression>"
+}
+
+// BinaryExpr represents a binary operator expression.
+type BinaryExpr struct {
+	LHS      Expr
+	RHS      Expr
+	Token    token.Token
+	TokenPos Pos
+}
+
+func (e *BinaryExpr) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *BinaryExpr) Pos() Pos {
+	return e.LHS.Pos()
+}
+
+// End returns the position of first character immediately after the node.
+func (e *BinaryExpr) End() Pos {
+	return e.RHS.End()
+}
+
+func (e *BinaryExpr) String() string {
+	return "(" + e.LHS.String() + " " + e.Token.String() +
+		" " + e.RHS.String() + ")"
+}
+
+// BoolLit represents a boolean literal.
+type BoolLit struct {
+	Value    bool
+	ValuePos Pos
+	Literal  string
+}
+
+func (e *BoolLit) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *BoolLit) Pos() Pos {
+	return e.ValuePos
+}
+
+// End returns the position of first character immediately after the node.
+func (e *BoolLit) End() Pos {
+	return Pos(int(e.ValuePos) + len(e.Literal))
+}
+
+func (e *BoolLit) String() string {
+	return e.Literal
+}
+
+// CallExpr represents a function call expression.
+type CallExpr struct {
+	Func   Expr
+	LParen Pos
+	Args   []Expr
+	RParen Pos
+}
+
+func (e *CallExpr) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *CallExpr) Pos() Pos {
+	return e.Func.Pos()
+}
+
+// End returns the position of first character immediately after the node.
+func (e *CallExpr) End() Pos {
+	return e.RParen + 1
+}
+
+func (e *CallExpr) String() string {
+	var args []string
+	for _, e := range e.Args {
+		args = append(args, e.String())
+	}
+	return e.Func.String() + "(" + strings.Join(args, ", ") + ")"
+}
+
+// CharLit represents a character literal.
+type CharLit struct {
+	Value    rune
+	ValuePos Pos
+	Literal  string
+}
+
+func (e *CharLit) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *CharLit) Pos() Pos {
+	return e.ValuePos
+}
+
+// End returns the position of first character immediately after the node.
+func (e *CharLit) End() Pos {
+	return Pos(int(e.ValuePos) + len(e.Literal))
+}
+
+func (e *CharLit) String() string {
+	return e.Literal
+}
+
+// CondExpr represents a ternary conditional expression.
+type CondExpr struct {
+	Cond        Expr
+	True        Expr
+	False       Expr
+	QuestionPos Pos
+	ColonPos    Pos
+}
+
+func (e *CondExpr) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *CondExpr) Pos() Pos {
+	return e.Cond.Pos()
+}
+
+// End returns the position of first character immediately after the node.
+func (e *CondExpr) End() Pos {
+	return e.False.End()
+}
+
+func (e *CondExpr) String() string {
+	return "(" + e.Cond.String() + " ? " + e.True.String() +
+		" : " + e.False.String() + ")"
+}
+
+// ErrorExpr represents an error expression
+type ErrorExpr struct {
+	Expr     Expr
+	ErrorPos Pos
+	LParen   Pos
+	RParen   Pos
+}
+
+func (e *ErrorExpr) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *ErrorExpr) Pos() Pos {
+	return e.ErrorPos
+}
+
+// End returns the position of first character immediately after the node.
+func (e *ErrorExpr) End() Pos {
+	return e.RParen
+}
+
+func (e *ErrorExpr) String() string {
+	return "error(" + e.Expr.String() + ")"
+}
+
+// FloatLit represents a floating point literal.
+type FloatLit struct {
+	Value    float64
+	ValuePos Pos
+	Literal  string
+}
+
+func (e *FloatLit) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *FloatLit) Pos() Pos {
+	return e.ValuePos
+}
+
+// End returns the position of first character immediately after the node.
+func (e *FloatLit) End() Pos {
+	return Pos(int(e.ValuePos) + len(e.Literal))
+}
+
+func (e *FloatLit) String() string {
+	return e.Literal
+}
+
+// FuncLit represents a function literal.
+type FuncLit struct {
+	Type *FuncType
+	Body *BlockStmt
+}
+
+func (e *FuncLit) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *FuncLit) Pos() Pos {
+	return e.Type.Pos()
+}
+
+// End returns the position of first character immediately after the node.
+func (e *FuncLit) End() Pos {
+	return e.Body.End()
+}
+
+func (e *FuncLit) String() string {
+	return "func" + e.Type.Params.String() + " " + e.Body.String()
+}
+
+// FuncType represents a function type definition.
+type FuncType struct {
+	FuncPos Pos
+	Params  *IdentList
+}
+
+func (e *FuncType) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *FuncType) Pos() Pos {
+	return e.FuncPos
+}
+
+// End returns the position of first character immediately after the node.
+func (e *FuncType) End() Pos {
+	return e.Params.End()
+}
+
+func (e *FuncType) String() string {
+	return "func" + e.Params.String()
+}
+
+// Ident represents an identifier.
+type Ident struct {
+	Name    string
+	NamePos Pos
+}
+
+func (e *Ident) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *Ident) Pos() Pos {
+	return e.NamePos
+}
+
+// End returns the position of first character immediately after the node.
+func (e *Ident) End() Pos {
+	return Pos(int(e.NamePos) + len(e.Name))
+}
+
+func (e *Ident) String() string {
+	if e != nil {
+		return e.Name
+	}
+	return nullRep
+}
+
+// ImmutableExpr represents an immutable expression
+type ImmutableExpr struct {
+	Expr     Expr
+	ErrorPos Pos
+	LParen   Pos
+	RParen   Pos
+}
+
+func (e *ImmutableExpr) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *ImmutableExpr) Pos() Pos {
+	return e.ErrorPos
+}
+
+// End returns the position of first character immediately after the node.
+func (e *ImmutableExpr) End() Pos {
+	return e.RParen
+}
+
+func (e *ImmutableExpr) String() string {
+	return "immutable(" + e.Expr.String() + ")"
+}
+
+// ImportExpr represents an import expression
+type ImportExpr struct {
+	ModuleName string
+	Token      token.Token
+	TokenPos   Pos
+}
+
+func (e *ImportExpr) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *ImportExpr) Pos() Pos {
+	return e.TokenPos
+}
+
+// End returns the position of first character immediately after the node.
+func (e *ImportExpr) End() Pos {
+	// import("moduleName")
+	return Pos(int(e.TokenPos) + 10 + len(e.ModuleName))
+}
+
+func (e *ImportExpr) String() string {
+	return `import("` + e.ModuleName + `")"`
+}
+
+// IndexExpr represents an index expression.
+type IndexExpr struct {
+	Expr   Expr
+	LBrack Pos
+	Index  Expr
+	RBrack Pos
+}
+
+func (e *IndexExpr) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *IndexExpr) Pos() Pos {
+	return e.Expr.Pos()
+}
+
+// End returns the position of first character immediately after the node.
+func (e *IndexExpr) End() Pos {
+	return e.RBrack + 1
+}
+
+func (e *IndexExpr) String() string {
+	var index string
+	if e.Index != nil {
+		index = e.Index.String()
+	}
+	return e.Expr.String() + "[" + index + "]"
+}
+
+// IntLit represents an integer literal.
+type IntLit struct {
+	Value    int64
+	ValuePos Pos
+	Literal  string
+}
+
+func (e *IntLit) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *IntLit) Pos() Pos {
+	return e.ValuePos
+}
+
+// End returns the position of first character immediately after the node.
+func (e *IntLit) End() Pos {
+	return Pos(int(e.ValuePos) + len(e.Literal))
+}
+
+func (e *IntLit) String() string {
+	return e.Literal
+}
+
+// MapElementLit represents a map element.
+type MapElementLit struct {
+	Key      string
+	KeyPos   Pos
+	ColonPos Pos
+	Value    Expr
+}
+
+func (e *MapElementLit) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *MapElementLit) Pos() Pos {
+	return e.KeyPos
+}
+
+// End returns the position of first character immediately after the node.
+func (e *MapElementLit) End() Pos {
+	return e.Value.End()
+}
+
+func (e *MapElementLit) String() string {
+	return e.Key + ": " + e.Value.String()
+}
+
+// MapLit represents a map literal.
+type MapLit struct {
+	LBrace   Pos
+	Elements []*MapElementLit
+	RBrace   Pos
+}
+
+func (e *MapLit) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *MapLit) Pos() Pos {
+	return e.LBrace
+}
+
+// End returns the position of first character immediately after the node.
+func (e *MapLit) End() Pos {
+	return e.RBrace + 1
+}
+
+func (e *MapLit) String() string {
+	var elements []string
+	for _, m := range e.Elements {
+		elements = append(elements, m.String())
+	}
+	return "{" + strings.Join(elements, ", ") + "}"
+}
+
+// ParenExpr represents a parenthesis wrapped expression.
+type ParenExpr struct {
+	Expr   Expr
+	LParen Pos
+	RParen Pos
+}
+
+func (e *ParenExpr) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *ParenExpr) Pos() Pos {
+	return e.LParen
+}
+
+// End returns the position of first character immediately after the node.
+func (e *ParenExpr) End() Pos {
+	return e.RParen + 1
+}
+
+func (e *ParenExpr) String() string {
+	return "(" + e.Expr.String() + ")"
+}
+
+// SelectorExpr represents a selector expression.
+type SelectorExpr struct {
+	Expr Expr
+	Sel  Expr
+}
+
+func (e *SelectorExpr) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *SelectorExpr) Pos() Pos {
+	return e.Expr.Pos()
+}
+
+// End returns the position of first character immediately after the node.
+func (e *SelectorExpr) End() Pos {
+	return e.Sel.End()
+}
+
+func (e *SelectorExpr) String() string {
+	return e.Expr.String() + "." + e.Sel.String()
+}
+
+// SliceExpr represents a slice expression.
+type SliceExpr struct {
+	Expr   Expr
+	LBrack Pos
+	Low    Expr
+	High   Expr
+	RBrack Pos
+}
+
+func (e *SliceExpr) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *SliceExpr) Pos() Pos {
+	return e.Expr.Pos()
+}
+
+// End returns the position of first character immediately after the node.
+func (e *SliceExpr) End() Pos {
+	return e.RBrack + 1
+}
+
+func (e *SliceExpr) String() string {
+	var low, high string
+	if e.Low != nil {
+		low = e.Low.String()
+	}
+	if e.High != nil {
+		high = e.High.String()
+	}
+	return e.Expr.String() + "[" + low + ":" + high + "]"
+}
+
+// StringLit represents a string literal.
+type StringLit struct {
+	Value    string
+	ValuePos Pos
+	Literal  string
+}
+
+func (e *StringLit) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *StringLit) Pos() Pos {
+	return e.ValuePos
+}
+
+// End returns the position of first character immediately after the node.
+func (e *StringLit) End() Pos {
+	return Pos(int(e.ValuePos) + len(e.Literal))
+}
+
+func (e *StringLit) String() string {
+	return e.Literal
+}
+
+// UnaryExpr represents an unary operator expression.
+type UnaryExpr struct {
+	Expr     Expr
+	Token    token.Token
+	TokenPos Pos
+}
+
+func (e *UnaryExpr) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *UnaryExpr) Pos() Pos {
+	return e.Expr.Pos()
+}
+
+// End returns the position of first character immediately after the node.
+func (e *UnaryExpr) End() Pos {
+	return e.Expr.End()
+}
+
+func (e *UnaryExpr) String() string {
+	return "(" + e.Token.String() + e.Expr.String() + ")"
+}
+
+// UndefinedLit represents an undefined literal.
+type UndefinedLit struct {
+	TokenPos Pos
+}
+
+func (e *UndefinedLit) exprNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (e *UndefinedLit) Pos() Pos {
+	return e.TokenPos
+}
+
+// End returns the position of first character immediately after the node.
+func (e *UndefinedLit) End() Pos {
+	return e.TokenPos + 9 // len(undefined) == 9
+}
+
+func (e *UndefinedLit) String() string {
+	return "undefined"
+}
diff --git a/vendor/github.com/d5/tengo/compiler/ast/file.go b/vendor/github.com/d5/tengo/v2/parser/file.go
index fc18b2d7..7cf50fea 100644
--- a/vendor/github.com/d5/tengo/compiler/ast/file.go
+++ b/vendor/github.com/d5/tengo/v2/parser/file.go
@@ -1,25 +1,23 @@
-package ast
+package parser
 
 import (
 	"strings"
-
-	"github.com/d5/tengo/compiler/source"
 )
 
 // File represents a file unit.
 type File struct {
-	InputFile *source.File
+	InputFile *SourceFile
 	Stmts     []Stmt
 }
 
 // Pos returns the position of first character belonging to the node.
-func (n *File) Pos() source.Pos {
-	return source.Pos(n.InputFile.Base)
+func (n *File) Pos() Pos {
+	return Pos(n.InputFile.Base)
 }
 
 // End returns the position of first character immediately after the node.
-func (n *File) End() source.Pos {
-	return source.Pos(n.InputFile.Base + n.InputFile.Size)
+func (n *File) End() Pos {
+	return Pos(n.InputFile.Base + n.InputFile.Size)
 }
 
 func (n *File) String() string {
@@ -27,6 +25,5 @@ func (n *File) String() string {
 	for _, e := range n.Stmts {
 		stmts = append(stmts, e.String())
 	}
-
 	return strings.Join(stmts, "; ")
 }
diff --git a/vendor/github.com/d5/tengo/compiler/opcodes.go b/vendor/github.com/d5/tengo/v2/parser/opcodes.go
index d832ee17..a4fbfbaf 100644
--- a/vendor/github.com/d5/tengo/compiler/opcodes.go
+++ b/vendor/github.com/d5/tengo/v2/parser/opcodes.go
@@ -1,4 +1,4 @@
-package compiler
+package parser
 
 // Opcode represents a single byte operation code.
 type Opcode = byte
@@ -45,10 +45,11 @@ const (
 	OpIteratorNext                // Iterator next
 	OpIteratorKey                 // Iterator key
 	OpIteratorValue               // Iterator value
-	OpBinaryOp                    // Binary Operation
+	OpBinaryOp                    // Binary operation
+	OpSuspend                     // Suspend VM
 )
 
-// OpcodeNames is opcode names.
+// OpcodeNames are string representation of opcodes.
 var OpcodeNames = [...]string{
 	OpConstant:      "CONST",
 	OpPop:           "POP",
@@ -91,6 +92,7 @@ var OpcodeNames = [...]string{
 	OpIteratorKey:   "ITKEY",
 	OpIteratorValue: "ITVAL",
 	OpBinaryOp:      "BINARYOP",
+	OpSuspend:       "SUSPEND",
 }
 
 // OpcodeOperands is the number of operands.
@@ -136,6 +138,7 @@ var OpcodeOperands = [...][]int{
 	OpIteratorKey:   {},
 	OpIteratorValue: {},
 	OpBinaryOp:      {1},
+	OpSuspend:       {},
 }
 
 // ReadOperands reads operands from the bytecode.
@@ -147,9 +150,7 @@ func ReadOperands(numOperands []int, ins []byte) (operands []int, offset int) {
 		case 2:
 			operands = append(operands, int(ins[offset+1])|int(ins[offset])<<8)
 		}
-
 		offset += width
 	}
-
 	return
 }
diff --git a/vendor/github.com/d5/tengo/compiler/parser/parser.go b/vendor/github.com/d5/tengo/v2/parser/parser.go
index 27dd48f0..501a9106 100644
--- a/vendor/github.com/d5/tengo/compiler/parser/parser.go
+++ b/vendor/github.com/d5/tengo/v2/parser/parser.go
@@ -1,63 +1,128 @@
-/*
-	Parser parses the Tengo source files.
-
-	Parser is a modified version of Go's parser implementation.
-
-	Copyright 2009 The Go Authors. All rights reserved.
-	Use of this source code is governed by a BSD-style
-	license that can be found in the LICENSE file.
-*/
-
 package parser
 
 import (
 	"fmt"
 	"io"
+	"sort"
 	"strconv"
 
-	"github.com/d5/tengo/compiler/ast"
-	"github.com/d5/tengo/compiler/scanner"
-	"github.com/d5/tengo/compiler/source"
-	"github.com/d5/tengo/compiler/token"
+	"github.com/d5/tengo/v2/token"
 )
 
 type bailout struct{}
 
-// Parser parses the Tengo source files.
+var stmtStart = map[token.Token]bool{
+	token.Break:    true,
+	token.Continue: true,
+	token.For:      true,
+	token.If:       true,
+	token.Return:   true,
+	token.Export:   true,
+}
+
+// Error represents a parser error.
+type Error struct {
+	Pos SourceFilePos
+	Msg string
+}
+
+func (e Error) Error() string {
+	if e.Pos.Filename != "" || e.Pos.IsValid() {
+		return fmt.Sprintf("Parse Error: %s\n\tat %s", e.Msg, e.Pos)
+	}
+	return fmt.Sprintf("Parse Error: %s", e.Msg)
+}
+
+// ErrorList is a collection of parser errors.
+type ErrorList []*Error
+
+// Add adds a new parser error to the collection.
+func (p *ErrorList) Add(pos SourceFilePos, msg string) {
+	*p = append(*p, &Error{pos, msg})
+}
+
+// Len returns the number of elements in the collection.
+func (p ErrorList) Len() int {
+	return len(p)
+}
+
+func (p ErrorList) Swap(i, j int) {
+	p[i], p[j] = p[j], p[i]
+}
+
+func (p ErrorList) Less(i, j int) bool {
+	e := &p[i].Pos
+	f := &p[j].Pos
+
+	if e.Filename != f.Filename {
+		return e.Filename < f.Filename
+	}
+	if e.Line != f.Line {
+		return e.Line < f.Line
+	}
+	if e.Column != f.Column {
+		return e.Column < f.Column
+	}
+	return p[i].Msg < p[j].Msg
+}
+
+// Sort sorts the collection.
+func (p ErrorList) Sort() {
+	sort.Sort(p)
+}
+
+func (p ErrorList) Error() string {
+	switch len(p) {
+	case 0:
+		return "no errors"
+	case 1:
+		return p[0].Error()
+	}
+	return fmt.Sprintf("%s (and %d more errors)", p[0], len(p)-1)
+}
+
+// Err returns an error.
+func (p ErrorList) Err() error {
+	if len(p) == 0 {
+		return nil
+	}
+	return p
+}
+
+// Parser parses the Tengo source files. It's based on Go's parser
+// implementation.
 type Parser struct {
-	file      *source.File
+	file      *SourceFile
 	errors    ErrorList
-	scanner   *scanner.Scanner
-	pos       source.Pos
+	scanner   *Scanner
+	pos       Pos
 	token     token.Token
 	tokenLit  string
-	exprLevel int        // < 0: in control clause, >= 0: in expression
-	syncPos   source.Pos // last sync position
-	syncCount int        // number of advance calls without progress
+	exprLevel int // < 0: in control clause, >= 0: in expression
+	syncPos   Pos // last sync position
+	syncCount int // number of advance calls without progress
 	trace     bool
 	indent    int
 	traceOut  io.Writer
 }
 
 // NewParser creates a Parser.
-func NewParser(file *source.File, src []byte, trace io.Writer) *Parser {
+func NewParser(file *SourceFile, src []byte, trace io.Writer) *Parser {
 	p := &Parser{
 		file:     file,
 		trace:    trace != nil,
 		traceOut: trace,
 	}
-
-	p.scanner = scanner.NewScanner(p.file, src, func(pos source.FilePos, msg string) {
-		p.errors.Add(pos, msg)
-	}, 0)
-
+	p.scanner = NewScanner(p.file, src,
+		func(pos SourceFilePos, msg string) {
+			p.errors.Add(pos, msg)
+		}, 0)
 	p.next()
-
 	return p
 }
 
 // ParseFile parses the source and returns an AST file unit.
-func (p *Parser) ParseFile() (file *ast.File, err error) {
+func (p *Parser) ParseFile() (file *File, err error) {
 	defer func() {
 		if e := recover(); e != nil {
 			if _, ok := e.(bailout); !ok {
@@ -70,7 +135,7 @@ func (p *Parser) ParseFile() (file *ast.File, err error) {
 	}()
 
 	if p.trace {
-		defer un(trace(p, "File"))
+		defer untracep(tracep(p, "File"))
 	}
 
 	if p.errors.Len() > 0 {
@@ -82,17 +147,16 @@ func (p *Parser) ParseFile() (file *ast.File, err error) {
 		return nil, p.errors.Err()
 	}
 
-	file = &ast.File{
+	file = &File{
 		InputFile: p.file,
 		Stmts:     stmts,
 	}
-
 	return
 }
 
-func (p *Parser) parseExpr() ast.Expr {
+func (p *Parser) parseExpr() Expr {
 	if p.trace {
-		defer un(trace(p, "Expression"))
+		defer untracep(tracep(p, "Expression"))
 	}
 
 	expr := p.parseBinaryExpr(token.LowestPrec + 1)
@@ -101,13 +165,12 @@ func (p *Parser) parseExpr() ast.Expr {
 	if p.token == token.Question {
 		return p.parseCondExpr(expr)
 	}
-
 	return expr
 }
 
-func (p *Parser) parseBinaryExpr(prec1 int) ast.Expr {
+func (p *Parser) parseBinaryExpr(prec1 int) Expr {
 	if p.trace {
-		defer un(trace(p, "BinaryExpression"))
+		defer untracep(tracep(p, "BinaryExpression"))
 	}
 
 	x := p.parseUnaryExpr()
@@ -122,7 +185,7 @@ func (p *Parser) parseBinaryExpr(prec1 int) ast.Expr {
 
 		y := p.parseBinaryExpr(prec + 1)
 
-		x = &ast.BinaryExpr{
+		x = &BinaryExpr{
 			LHS:      x,
 			RHS:      y,
 			Token:    op,
@@ -131,16 +194,13 @@ func (p *Parser) parseBinaryExpr(prec1 int) ast.Expr {
 	}
 }
 
-func (p *Parser) parseCondExpr(cond ast.Expr) ast.Expr {
+func (p *Parser) parseCondExpr(cond Expr) Expr {
 	questionPos := p.expect(token.Question)
-
 	trueExpr := p.parseExpr()
-
 	colonPos := p.expect(token.Colon)
-
 	falseExpr := p.parseExpr()
 
-	return &ast.CondExpr{
+	return &CondExpr{
 		Cond:        cond,
 		True:        trueExpr,
 		False:       falseExpr,
@@ -149,9 +209,9 @@ func (p *Parser) parseCondExpr(cond ast.Expr) ast.Expr {
 	}
 }
 
-func (p *Parser) parseUnaryExpr() ast.Expr {
+func (p *Parser) parseUnaryExpr() Expr {
 	if p.trace {
-		defer un(trace(p, "UnaryExpression"))
+		defer untracep(tracep(p, "UnaryExpression"))
 	}
 
 	switch p.token {
@@ -159,19 +219,18 @@ func (p *Parser) parseUnaryExpr() ast.Expr {
 		pos, op := p.pos, p.token
 		p.next()
 		x := p.parseUnaryExpr()
-		return &ast.UnaryExpr{
+		return &UnaryExpr{
 			Token:    op,
 			TokenPos: pos,
 			Expr:     x,
 		}
 	}
-
 	return p.parsePrimaryExpr()
 }
 
-func (p *Parser) parsePrimaryExpr() ast.Expr {
+func (p *Parser) parsePrimaryExpr() Expr {
 	if p.trace {
-		defer un(trace(p, "PrimaryExpression"))
+		defer untracep(tracep(p, "PrimaryExpression"))
 	}
 
 	x := p.parseOperand()
@@ -189,7 +248,7 @@ L:
 				pos := p.pos
 				p.errorExpected(pos, "selector")
 				p.advance(stmtStart)
-				return &ast.BadExpr{From: pos, To: p.pos}
+				return &BadExpr{From: pos, To: p.pos}
 			}
 		case token.LBrack:
 			x = p.parseIndexOrSlice(x)
@@ -199,19 +258,18 @@ L:
 			break L
 		}
 	}
-
 	return x
 }
 
-func (p *Parser) parseCall(x ast.Expr) *ast.CallExpr {
+func (p *Parser) parseCall(x Expr) *CallExpr {
 	if p.trace {
-		defer un(trace(p, "Call"))
+		defer untracep(tracep(p, "Call"))
 	}
 
 	lparen := p.expect(token.LParen)
 	p.exprLevel++
 
-	var list []ast.Expr
+	var list []Expr
 	for p.token != token.RParen && p.token != token.EOF {
 		list = append(list, p.parseExpr())
 
@@ -222,8 +280,7 @@ func (p *Parser) parseCall(x ast.Expr) *ast.CallExpr {
 
 	p.exprLevel--
 	rparen := p.expect(token.RParen)
-
-	return &ast.CallExpr{
+	return &CallExpr{
 		Func:   x,
 		LParen: lparen,
 		RParen: rparen,
@@ -239,26 +296,24 @@ func (p *Parser) expectComma(closing token.Token, want string) bool {
 			p.errorExpected(p.pos, want)
 			return false
 		}
-
 		return true
 	}
 
 	if p.token == token.Semicolon && p.tokenLit == "\n" {
 		p.next()
 	}
-
 	return false
 }
 
-func (p *Parser) parseIndexOrSlice(x ast.Expr) ast.Expr {
+func (p *Parser) parseIndexOrSlice(x Expr) Expr {
 	if p.trace {
-		defer un(trace(p, "IndexOrSlice"))
+		defer untracep(tracep(p, "IndexOrSlice"))
 	}
 
 	lbrack := p.expect(token.LBrack)
 	p.exprLevel++
 
-	var index [2]ast.Expr
+	var index [2]Expr
 	if p.token != token.Colon {
 		index[0] = p.parseExpr()
 	}
@@ -277,7 +332,7 @@ func (p *Parser) parseIndexOrSlice(x ast.Expr) ast.Expr {
 
 	if numColons > 0 {
 		// slice expression
-		return &ast.SliceExpr{
+		return &SliceExpr{
 			Expr:   x,
 			LBrack: lbrack,
 			RBrack: rbrack,
@@ -285,8 +340,7 @@ func (p *Parser) parseIndexOrSlice(x ast.Expr) ast.Expr {
 			High:   index[1],
 		}
 	}
-
-	return &ast.IndexExpr{
+	return &IndexExpr{
 		Expr:   x,
 		LBrack: lbrack,
 		RBrack: rbrack,
@@ -294,88 +348,78 @@ func (p *Parser) parseIndexOrSlice(x ast.Expr) ast.Expr {
 	}
 }
 
-func (p *Parser) parseSelector(x ast.Expr) ast.Expr {
+func (p *Parser) parseSelector(x Expr) Expr {
 	if p.trace {
-		defer un(trace(p, "Selector"))
+		defer untracep(tracep(p, "Selector"))
 	}
 
 	sel := p.parseIdent()
-
-	return &ast.SelectorExpr{Expr: x, Sel: &ast.StringLit{
+	return &SelectorExpr{Expr: x, Sel: &StringLit{
 		Value:    sel.Name,
 		ValuePos: sel.NamePos,
 		Literal:  sel.Name,
 	}}
 }
 
-func (p *Parser) parseOperand() ast.Expr {
+func (p *Parser) parseOperand() Expr {
 	if p.trace {
-		defer un(trace(p, "Operand"))
+		defer untracep(tracep(p, "Operand"))
 	}
 
 	switch p.token {
 	case token.Ident:
 		return p.parseIdent()
-
 	case token.Int:
 		v, _ := strconv.ParseInt(p.tokenLit, 10, 64)
-		x := &ast.IntLit{
+		x := &IntLit{
 			Value:    v,
 			ValuePos: p.pos,
 			Literal:  p.tokenLit,
 		}
 		p.next()
 		return x
-
 	case token.Float:
 		v, _ := strconv.ParseFloat(p.tokenLit, 64)
-		x := &ast.FloatLit{
+		x := &FloatLit{
 			Value:    v,
 			ValuePos: p.pos,
 			Literal:  p.tokenLit,
 		}
 		p.next()
 		return x
-
 	case token.Char:
 		return p.parseCharLit()
-
 	case token.String:
 		v, _ := strconv.Unquote(p.tokenLit)
-		x := &ast.StringLit{
+		x := &StringLit{
 			Value:    v,
 			ValuePos: p.pos,
 			Literal:  p.tokenLit,
 		}
 		p.next()
 		return x
-
 	case token.True:
-		x := &ast.BoolLit{
+		x := &BoolLit{
 			Value:    true,
 			ValuePos: p.pos,
 			Literal:  p.tokenLit,
 		}
 		p.next()
 		return x
-
 	case token.False:
-		x := &ast.BoolLit{
+		x := &BoolLit{
 			Value:    false,
 			ValuePos: p.pos,
 			Literal:  p.tokenLit,
 		}
 		p.next()
 		return x
-
 	case token.Undefined:
-		x := &ast.UndefinedLit{TokenPos: p.pos}
+		x := &UndefinedLit{TokenPos: p.pos}
 		p.next()
 		return x
-
 	case token.Import:
 		return p.parseImportExpr()
-
 	case token.LParen:
 		lparen := p.pos
 		p.next()
@@ -383,24 +427,19 @@ func (p *Parser) parseOperand() ast.Expr {
 		x := p.parseExpr()
 		p.exprLevel--
 		rparen := p.expect(token.RParen)
-		return &ast.ParenExpr{
+		return &ParenExpr{
 			LParen: lparen,
 			Expr:   x,
 			RParen: rparen,
 		}
-
 	case token.LBrack: // array literal
 		return p.parseArrayLit()
-
 	case token.LBrace: // map literal
 		return p.parseMapLit()
-
 	case token.Func: // function literal
 		return p.parseFuncLit()
-
 	case token.Error: // error expression
 		return p.parseErrorExpr()
-
 	case token.Immutable: // immutable expression
 		return p.parseImmutableExpr()
 	}
@@ -408,43 +447,38 @@ func (p *Parser) parseOperand() ast.Expr {
 	pos := p.pos
 	p.errorExpected(pos, "operand")
 	p.advance(stmtStart)
-	return &ast.BadExpr{From: pos, To: p.pos}
+	return &BadExpr{From: pos, To: p.pos}
 }
 
-func (p *Parser) parseImportExpr() ast.Expr {
+func (p *Parser) parseImportExpr() Expr {
 	pos := p.pos
-
 	p.next()
-
 	p.expect(token.LParen)
-
 	if p.token != token.String {
 		p.errorExpected(p.pos, "module name")
 		p.advance(stmtStart)
-		return &ast.BadExpr{From: pos, To: p.pos}
+		return &BadExpr{From: pos, To: p.pos}
 	}
 
 	// module name
 	moduleName, _ := strconv.Unquote(p.tokenLit)
-
-	expr := &ast.ImportExpr{
+	expr := &ImportExpr{
 		ModuleName: moduleName,
 		Token:      token.Import,
 		TokenPos:   pos,
 	}
 
 	p.next()
-
 	p.expect(token.RParen)
-
 	return expr
 }
 
-func (p *Parser) parseCharLit() ast.Expr {
+func (p *Parser) parseCharLit() Expr {
 	if n := len(p.tokenLit); n >= 3 {
-		if code, _, _, err := strconv.UnquoteChar(p.tokenLit[1:n-1], '\''); err == nil {
-			x := &ast.CharLit{
-				Value:    rune(code),
+		code, _, _, err := strconv.UnquoteChar(p.tokenLit[1:n-1], '\'')
+		if err == nil {
+			x := &CharLit{
+				Value:    code,
 				ValuePos: p.pos,
 				Literal:  p.tokenLit,
 			}
@@ -456,38 +490,36 @@ func (p *Parser) parseCharLit() ast.Expr {
 	pos := p.pos
 	p.error(pos, "illegal char literal")
 	p.next()
-	return &ast.BadExpr{
+	return &BadExpr{
 		From: pos,
 		To:   p.pos,
 	}
 }
 
-func (p *Parser) parseFuncLit() ast.Expr {
+func (p *Parser) parseFuncLit() Expr {
 	if p.trace {
-		defer un(trace(p, "FuncLit"))
+		defer untracep(tracep(p, "FuncLit"))
 	}
 
 	typ := p.parseFuncType()
-
 	p.exprLevel++
 	body := p.parseBody()
 	p.exprLevel--
-
-	return &ast.FuncLit{
+	return &FuncLit{
 		Type: typ,
 		Body: body,
 	}
 }
 
-func (p *Parser) parseArrayLit() ast.Expr {
+func (p *Parser) parseArrayLit() Expr {
 	if p.trace {
-		defer un(trace(p, "ArrayLit"))
+		defer untracep(tracep(p, "ArrayLit"))
 	}
 
 	lbrack := p.expect(token.LBrack)
 	p.exprLevel++
 
-	var elements []ast.Expr
+	var elements []Expr
 	for p.token != token.RBrack && p.token != token.EOF {
 		elements = append(elements, p.parseExpr())
 
@@ -498,95 +530,83 @@ func (p *Parser) parseArrayLit() ast.Expr {
 
 	p.exprLevel--
 	rbrack := p.expect(token.RBrack)
-
-	return &ast.ArrayLit{
+	return &ArrayLit{
 		Elements: elements,
 		LBrack:   lbrack,
 		RBrack:   rbrack,
 	}
 }
 
-func (p *Parser) parseErrorExpr() ast.Expr {
+func (p *Parser) parseErrorExpr() Expr {
 	pos := p.pos
 
 	p.next()
-
 	lparen := p.expect(token.LParen)
 	value := p.parseExpr()
 	rparen := p.expect(token.RParen)
-
-	expr := &ast.ErrorExpr{
+	return &ErrorExpr{
 		ErrorPos: pos,
 		Expr:     value,
 		LParen:   lparen,
 		RParen:   rparen,
 	}
-
-	return expr
 }
 
-func (p *Parser) parseImmutableExpr() ast.Expr {
+func (p *Parser) parseImmutableExpr() Expr {
 	pos := p.pos
 
 	p.next()
-
 	lparen := p.expect(token.LParen)
 	value := p.parseExpr()
 	rparen := p.expect(token.RParen)
-
-	expr := &ast.ImmutableExpr{
+	return &ImmutableExpr{
 		ErrorPos: pos,
 		Expr:     value,
 		LParen:   lparen,
 		RParen:   rparen,
 	}
-
-	return expr
 }
 
-func (p *Parser) parseFuncType() *ast.FuncType {
+func (p *Parser) parseFuncType() *FuncType {
 	if p.trace {
-		defer un(trace(p, "FuncType"))
+		defer untracep(tracep(p, "FuncType"))
 	}
 
 	pos := p.expect(token.Func)
 	params := p.parseIdentList()
-
-	return &ast.FuncType{
+	return &FuncType{
 		FuncPos: pos,
 		Params:  params,
 	}
 }
 
-func (p *Parser) parseBody() *ast.BlockStmt {
+func (p *Parser) parseBody() *BlockStmt {
 	if p.trace {
-		defer un(trace(p, "Body"))
+		defer untracep(tracep(p, "Body"))
 	}
 
 	lbrace := p.expect(token.LBrace)
 	list := p.parseStmtList()
 	rbrace := p.expect(token.RBrace)
-
-	return &ast.BlockStmt{
+	return &BlockStmt{
 		LBrace: lbrace,
 		RBrace: rbrace,
 		Stmts:  list,
 	}
 }
 
-func (p *Parser) parseStmtList() (list []ast.Stmt) {
+func (p *Parser) parseStmtList() (list []Stmt) {
 	if p.trace {
-		defer un(trace(p, "StatementList"))
+		defer untracep(tracep(p, "StatementList"))
 	}
 
 	for p.token != token.RBrace && p.token != token.EOF {
 		list = append(list, p.parseStmt())
 	}
-
 	return
 }
 
-func (p *Parser) parseIdent() *ast.Ident {
+func (p *Parser) parseIdent() *Ident {
 	pos := p.pos
 	name := "_"
 
@@ -596,19 +616,18 @@ func (p *Parser) parseIdent() *ast.Ident {
 	} else {
 		p.expect(token.Ident)
 	}
-
-	return &ast.Ident{
+	return &Ident{
 		NamePos: pos,
 		Name:    name,
 	}
 }
 
-func (p *Parser) parseIdentList() *ast.IdentList {
+func (p *Parser) parseIdentList() *IdentList {
 	if p.trace {
-		defer un(trace(p, "IdentList"))
+		defer untracep(tracep(p, "IdentList"))
 	}
 
-	var params []*ast.Ident
+	var params []*Ident
 	lparen := p.expect(token.LParen)
 	isVarArgs := false
 	if p.token != token.RParen {
@@ -629,8 +648,7 @@ func (p *Parser) parseIdentList() *ast.IdentList {
 	}
 
 	rparen := p.expect(token.RParen)
-
-	return &ast.IdentList{
+	return &IdentList{
 		LParen:  lparen,
 		RParen:  rparen,
 		VarArgs: isVarArgs,
@@ -638,16 +656,18 @@ func (p *Parser) parseIdentList() *ast.IdentList {
 	}
 }
 
-func (p *Parser) parseStmt() (stmt ast.Stmt) {
+func (p *Parser) parseStmt() (stmt Stmt) {
 	if p.trace {
-		defer un(trace(p, "Statement"))
+		defer untracep(tracep(p, "Statement"))
 	}
 
 	switch p.token {
 	case // simple statements
-		token.Func, token.Error, token.Immutable, token.Ident, token.Int, token.Float, token.Char, token.String, token.True, token.False,
-		token.Undefined, token.Import, token.LParen, token.LBrace, token.LBrack,
-		token.Add, token.Sub, token.Mul, token.And, token.Xor, token.Not:
+		token.Func, token.Error, token.Immutable, token.Ident, token.Int,
+		token.Float, token.Char, token.String, token.True, token.False,
+		token.Undefined, token.Import, token.LParen, token.LBrace,
+		token.LBrack, token.Add, token.Sub, token.Mul, token.And, token.Xor,
+		token.Not:
 		s := p.parseSimpleStmt(false)
 		p.expectSemi()
 		return s
@@ -662,23 +682,23 @@ func (p *Parser) parseStmt() (stmt ast.Stmt) {
 	case token.Break, token.Continue:
 		return p.parseBranchStmt(p.token)
 	case token.Semicolon:
-		s := &ast.EmptyStmt{Semicolon: p.pos, Implicit: p.tokenLit == "\n"}
+		s := &EmptyStmt{Semicolon: p.pos, Implicit: p.tokenLit == "\n"}
 		p.next()
 		return s
 	case token.RBrace:
 		// semicolon may be omitted before a closing "}"
-		return &ast.EmptyStmt{Semicolon: p.pos, Implicit: true}
+		return &EmptyStmt{Semicolon: p.pos, Implicit: true}
 	default:
 		pos := p.pos
 		p.errorExpected(pos, "statement")
 		p.advance(stmtStart)
-		return &ast.BadStmt{From: pos, To: p.pos}
+		return &BadStmt{From: pos, To: p.pos}
 	}
 }
 
-func (p *Parser) parseForStmt() ast.Stmt {
+func (p *Parser) parseForStmt() Stmt {
 	if p.trace {
-		defer un(trace(p, "ForStmt"))
+		defer untracep(tracep(p, "ForStmt"))
 	}
 
 	pos := p.expect(token.For)
@@ -688,7 +708,7 @@ func (p *Parser) parseForStmt() ast.Stmt {
 		body := p.parseBlockStmt()
 		p.expectSemi()
 
-		return &ast.ForStmt{
+		return &ForStmt{
 			ForPos: pos,
 			Body:   body,
 		}
@@ -697,7 +717,7 @@ func (p *Parser) parseForStmt() ast.Stmt {
 	prevLevel := p.exprLevel
 	p.exprLevel = -1
 
-	var s1 ast.Stmt
+	var s1 Stmt
 	if p.token != token.Semicolon { // skipping init
 		s1 = p.parseSimpleStmt(true)
 	}
@@ -705,7 +725,7 @@ func (p *Parser) parseForStmt() ast.Stmt {
 	// for _ in seq {}            or
 	// for value in seq {}        or
 	// for key, value in seq {}
-	if forInStmt, isForIn := s1.(*ast.ForInStmt); isForIn {
+	if forInStmt, isForIn := s1.(*ForInStmt); isForIn {
 		forInStmt.ForPos = pos
 		p.exprLevel = prevLevel
 		forInStmt.Body = p.parseBlockStmt()
@@ -714,7 +734,7 @@ func (p *Parser) parseForStmt() ast.Stmt {
 	}
 
 	// for init; cond; post {}
-	var s2, s3 ast.Stmt
+	var s2, s3 Stmt
 	if p.token == token.Semicolon {
 		p.next()
 		if p.token != token.Semicolon {
@@ -734,50 +754,45 @@ func (p *Parser) parseForStmt() ast.Stmt {
 	p.exprLevel = prevLevel
 	body := p.parseBlockStmt()
 	p.expectSemi()
-
 	cond := p.makeExpr(s2, "condition expression")
-
-	return &ast.ForStmt{
+	return &ForStmt{
 		ForPos: pos,
 		Init:   s1,
 		Cond:   cond,
 		Post:   s3,
 		Body:   body,
 	}
-
 }
 
-func (p *Parser) parseBranchStmt(tok token.Token) ast.Stmt {
+func (p *Parser) parseBranchStmt(tok token.Token) Stmt {
 	if p.trace {
-		defer un(trace(p, "BranchStmt"))
+		defer untracep(tracep(p, "BranchStmt"))
 	}
 
 	pos := p.expect(tok)
 
-	var label *ast.Ident
+	var label *Ident
 	if p.token == token.Ident {
 		label = p.parseIdent()
 	}
 	p.expectSemi()
-
-	return &ast.BranchStmt{
+	return &BranchStmt{
 		Token:    tok,
 		TokenPos: pos,
 		Label:    label,
 	}
 }
 
-func (p *Parser) parseIfStmt() ast.Stmt {
+func (p *Parser) parseIfStmt() Stmt {
 	if p.trace {
-		defer un(trace(p, "IfStmt"))
+		defer untracep(tracep(p, "IfStmt"))
 	}
 
 	pos := p.expect(token.If)
-
 	init, cond := p.parseIfHeader()
 	body := p.parseBlockStmt()
 
-	var elseStmt ast.Stmt
+	var elseStmt Stmt
 	if p.token == token.Else {
 		p.next()
 
@@ -789,13 +804,12 @@ func (p *Parser) parseIfStmt() ast.Stmt {
 			p.expectSemi()
 		default:
 			p.errorExpected(p.pos, "if or {")
-			elseStmt = &ast.BadStmt{From: p.pos, To: p.pos}
+			elseStmt = &BadStmt{From: p.pos, To: p.pos}
 		}
 	} else {
 		p.expectSemi()
 	}
-
-	return &ast.IfStmt{
+	return &IfStmt{
 		IfPos: pos,
 		Init:  init,
 		Cond:  cond,
@@ -804,40 +818,37 @@ func (p *Parser) parseIfStmt() ast.Stmt {
 	}
 }
 
-func (p *Parser) parseBlockStmt() *ast.BlockStmt {
+func (p *Parser) parseBlockStmt() *BlockStmt {
 	if p.trace {
-		defer un(trace(p, "BlockStmt"))
+		defer untracep(tracep(p, "BlockStmt"))
 	}
 
 	lbrace := p.expect(token.LBrace)
 	list := p.parseStmtList()
 	rbrace := p.expect(token.RBrace)
-
-	return &ast.BlockStmt{
+	return &BlockStmt{
 		LBrace: lbrace,
 		RBrace: rbrace,
 		Stmts:  list,
 	}
 }
 
-func (p *Parser) parseIfHeader() (init ast.Stmt, cond ast.Expr) {
+func (p *Parser) parseIfHeader() (init Stmt, cond Expr) {
 	if p.token == token.LBrace {
 		p.error(p.pos, "missing condition in if statement")
-		cond = &ast.BadExpr{From: p.pos, To: p.pos}
+		cond = &BadExpr{From: p.pos, To: p.pos}
 		return
 	}
 
 	outer := p.exprLevel
 	p.exprLevel = -1
-
 	if p.token == token.Semicolon {
 		p.error(p.pos, "missing init in if statement")
 		return
 	}
-
 	init = p.parseSimpleStmt(false)
 
-	var condStmt ast.Stmt
+	var condStmt Stmt
 	if p.token == token.LBrace {
 		condStmt = init
 		init = nil
@@ -852,75 +863,67 @@ func (p *Parser) parseIfHeader() (init ast.Stmt, cond ast.Expr) {
 	if condStmt != nil {
 		cond = p.makeExpr(condStmt, "boolean expression")
 	}
-
 	if cond == nil {
-		cond = &ast.BadExpr{From: p.pos, To: p.pos}
+		cond = &BadExpr{From: p.pos, To: p.pos}
 	}
-
 	p.exprLevel = outer
-
 	return
 }
 
-func (p *Parser) makeExpr(s ast.Stmt, want string) ast.Expr {
+func (p *Parser) makeExpr(s Stmt, want string) Expr {
 	if s == nil {
 		return nil
 	}
 
-	if es, isExpr := s.(*ast.ExprStmt); isExpr {
+	if es, isExpr := s.(*ExprStmt); isExpr {
 		return es.Expr
 	}
 
 	found := "simple statement"
-	if _, isAss := s.(*ast.AssignStmt); isAss {
+	if _, isAss := s.(*AssignStmt); isAss {
 		found = "assignment"
 	}
-
 	p.error(s.Pos(), fmt.Sprintf("expected %s, found %s", want, found))
-
-	return &ast.BadExpr{From: s.Pos(), To: p.safePos(s.End())}
+	return &BadExpr{From: s.Pos(), To: p.safePos(s.End())}
 }
 
-func (p *Parser) parseReturnStmt() ast.Stmt {
+func (p *Parser) parseReturnStmt() Stmt {
 	if p.trace {
-		defer un(trace(p, "ReturnStmt"))
+		defer untracep(tracep(p, "ReturnStmt"))
 	}
 
 	pos := p.pos
 	p.expect(token.Return)
 
-	var x ast.Expr
+	var x Expr
 	if p.token != token.Semicolon && p.token != token.RBrace {
 		x = p.parseExpr()
 	}
 	p.expectSemi()
-
-	return &ast.ReturnStmt{
+	return &ReturnStmt{
 		ReturnPos: pos,
 		Result:    x,
 	}
 }
 
-func (p *Parser) parseExportStmt() ast.Stmt {
+func (p *Parser) parseExportStmt() Stmt {
 	if p.trace {
-		defer un(trace(p, "ExportStmt"))
+		defer untracep(tracep(p, "ExportStmt"))
 	}
 
 	pos := p.pos
 	p.expect(token.Export)
-
 	x := p.parseExpr()
 	p.expectSemi()
-
-	return &ast.ExportStmt{
+	return &ExportStmt{
 		ExportPos: pos,
 		Result:    x,
 	}
 }
 
-func (p *Parser) parseSimpleStmt(forIn bool) ast.Stmt {
+func (p *Parser) parseSimpleStmt(forIn bool) Stmt {
 	if p.trace {
-		defer un(trace(p, "SimpleStmt"))
+		defer untracep(tracep(p, "SimpleStmt"))
 	}
 
 	x := p.parseExprList()
@@ -929,10 +932,8 @@ func (p *Parser) parseSimpleStmt(forIn bool) ast.Stmt {
 	case token.Assign, token.Define: // assignment statement
 		pos, tok := p.pos, p.token
 		p.next()
-
 		y := p.parseExprList()
-
-		return &ast.AssignStmt{
+		return &AssignStmt{
 			LHS:      x,
 			RHS:      y,
 			Token:    tok,
@@ -941,35 +942,32 @@ func (p *Parser) parseSimpleStmt(forIn bool) ast.Stmt {
 	case token.In:
 		if forIn {
 			p.next()
-
 			y := p.parseExpr()
 
-			var key, value *ast.Ident
+			var key, value *Ident
 			var ok bool
-
 			switch len(x) {
 			case 1:
-				key = &ast.Ident{Name: "_", NamePos: x[0].Pos()}
+				key = &Ident{Name: "_", NamePos: x[0].Pos()}
 
-				value, ok = x[0].(*ast.Ident)
+				value, ok = x[0].(*Ident)
 				if !ok {
 					p.errorExpected(x[0].Pos(), "identifier")
-					value = &ast.Ident{Name: "_", NamePos: x[0].Pos()}
+					value = &Ident{Name: "_", NamePos: x[0].Pos()}
 				}
 			case 2:
-				key, ok = x[0].(*ast.Ident)
+				key, ok = x[0].(*Ident)
 				if !ok {
 					p.errorExpected(x[0].Pos(), "identifier")
-					key = &ast.Ident{Name: "_", NamePos: x[0].Pos()}
+					key = &Ident{Name: "_", NamePos: x[0].Pos()}
 				}
-				value, ok = x[1].(*ast.Ident)
+				value, ok = x[1].(*Ident)
 				if !ok {
 					p.errorExpected(x[1].Pos(), "identifier")
-					value = &ast.Ident{Name: "_", NamePos: x[1].Pos()}
+					value = &Ident{Name: "_", NamePos: x[1].Pos()}
 				}
 			}
-
-			return &ast.ForInStmt{
+			return &ForInStmt{
 				Key:      key,
 				Value:    value,
 				Iterable: y,
@@ -984,33 +982,30 @@ func (p *Parser) parseSimpleStmt(forIn bool) ast.Stmt {
 
 	switch p.token {
 	case token.Define,
-		token.AddAssign, token.SubAssign, token.MulAssign, token.QuoAssign, token.RemAssign,
-		token.AndAssign, token.OrAssign, token.XorAssign, token.ShlAssign, token.ShrAssign, token.AndNotAssign:
+		token.AddAssign, token.SubAssign, token.MulAssign, token.QuoAssign,
+		token.RemAssign, token.AndAssign, token.OrAssign, token.XorAssign,
+		token.ShlAssign, token.ShrAssign, token.AndNotAssign:
 		pos, tok := p.pos, p.token
 		p.next()
-
 		y := p.parseExpr()
-
-		return &ast.AssignStmt{
-			LHS:      []ast.Expr{x[0]},
-			RHS:      []ast.Expr{y},
+		return &AssignStmt{
+			LHS:      []Expr{x[0]},
+			RHS:      []Expr{y},
 			Token:    tok,
 			TokenPos: pos,
 		}
 	case token.Inc, token.Dec:
 		// increment or decrement statement
-		s := &ast.IncDecStmt{Expr: x[0], Token: p.token, TokenPos: p.pos}
+		s := &IncDecStmt{Expr: x[0], Token: p.token, TokenPos: p.pos}
 		p.next()
 		return s
 	}
-
-	// expression statement
-	return &ast.ExprStmt{Expr: x[0]}
+	return &ExprStmt{Expr: x[0]}
 }
 
-func (p *Parser) parseExprList() (list []ast.Expr) {
+func (p *Parser) parseExprList() (list []Expr) {
 	if p.trace {
-		defer un(trace(p, "ExpressionList"))
+		defer untracep(tracep(p, "ExpressionList"))
 	}
 
 	list = append(list, p.parseExpr())
@@ -1018,18 +1013,16 @@ func (p *Parser) parseExprList() (list []ast.Expr) {
 		p.next()
 		list = append(list, p.parseExpr())
 	}
-
 	return
 }
 
-func (p *Parser) parseMapElementLit() *ast.MapElementLit {
+func (p *Parser) parseMapElementLit() *MapElementLit {
 	if p.trace {
-		defer un(trace(p, "MapElementLit"))
+		defer untracep(tracep(p, "MapElementLit"))
 	}
 
 	pos := p.pos
 	name := "_"
-
 	if p.token == token.Ident {
 		name = p.tokenLit
 	} else if p.token == token.String {
@@ -1038,13 +1031,10 @@ func (p *Parser) parseMapElementLit() *ast.MapElementLit {
 	} else {
 		p.errorExpected(pos, "map key")
 	}
-
 	p.next()
-
 	colonPos := p.expect(token.Colon)
 	valueExpr := p.parseExpr()
-
-	return &ast.MapElementLit{
+	return &MapElementLit{
 		Key:      name,
 		KeyPos:   pos,
 		ColonPos: colonPos,
@@ -1052,15 +1042,15 @@ func (p *Parser) parseMapElementLit() *ast.MapElementLit {
 	}
 }
 
-func (p *Parser) parseMapLit() *ast.MapLit {
+func (p *Parser) parseMapLit() *MapLit {
 	if p.trace {
-		defer un(trace(p, "MapLit"))
+		defer untracep(tracep(p, "MapLit"))
 	}
 
 	lbrace := p.expect(token.LBrace)
 	p.exprLevel++
 
-	var elements []*ast.MapElementLit
+	var elements []*MapElementLit
 	for p.token != token.RBrace && p.token != token.EOF {
 		elements = append(elements, p.parseMapElementLit())
 
@@ -1071,22 +1061,20 @@ func (p *Parser) parseMapLit() *ast.MapLit {
 
 	p.exprLevel--
 	rbrace := p.expect(token.RBrace)
-
-	return &ast.MapLit{
+	return &MapLit{
 		LBrace:   lbrace,
 		RBrace:   rbrace,
 		Elements: elements,
 	}
 }
 
-func (p *Parser) expect(token token.Token) source.Pos {
+func (p *Parser) expect(token token.Token) Pos {
 	pos := p.pos
 
 	if p.token != token {
 		p.errorExpected(pos, "'"+token.String()+"'")
 	}
 	p.next()
-
 	return pos
 }
 
@@ -1104,7 +1092,6 @@ func (p *Parser) expectSemi() {
 		p.errorExpected(p.pos, "';'")
 		p.advance(stmtStart)
 	}
-
 }
 
 func (p *Parser) advance(to map[token.Token]bool) {
@@ -1114,7 +1101,6 @@ func (p *Parser) advance(to map[token.Token]bool) {
 				p.syncCount++
 				return
 			}
-
 			if p.pos > p.syncPos {
 				p.syncPos = p.pos
 				p.syncCount = 0
@@ -1124,7 +1110,7 @@ func (p *Parser) advance(to map[token.Token]bool) {
 	}
 }
 
-func (p *Parser) error(pos source.Pos, msg string) {
+func (p *Parser) error(pos Pos, msg string) {
 	filePos := p.file.Position(pos)
 
 	n := len(p.errors)
@@ -1132,16 +1118,14 @@ func (p *Parser) error(pos source.Pos, msg string) {
 		// discard errors reported on the same line
 		return
 	}
-
 	if n > 10 {
 		// too many errors; terminate early
 		panic(bailout{})
 	}
-
 	p.errors.Add(filePos, msg)
 }
 
-func (p *Parser) errorExpected(pos source.Pos, msg string) {
+func (p *Parser) errorExpected(pos Pos, msg string) {
 	msg = "expected " + msg
 	if pos == p.pos {
 		// error happened at the current position: provide more specific
@@ -1154,7 +1138,6 @@ func (p *Parser) errorExpected(pos source.Pos, msg string) {
 			msg += ", found '" + p.token.String() + "'"
 		}
 	}
-
 	p.error(pos, msg)
 }
 
@@ -1170,19 +1153,18 @@ func (p *Parser) next() {
 			p.printTrace(s)
 		}
 	}
-
 	p.token, p.tokenLit, p.pos = p.scanner.Scan()
 }
 
 func (p *Parser) printTrace(a ...interface{}) {
 	const (
-		dots = ". . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . "
+		dots = ". . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . "
 		n    = len(dots)
 	)
 
 	filePos := p.file.Position(p.pos)
-	_, _ = fmt.Fprintf(p.traceOut, "%5d: %5d:%3d: ", p.pos, filePos.Line, filePos.Column)
-
+	_, _ = fmt.Fprintf(p.traceOut, "%5d: %5d:%3d: ", p.pos, filePos.Line,
+		filePos.Column)
 	i := 2 * p.indent
 	for i > n {
 		_, _ = fmt.Fprint(p.traceOut, dots)
@@ -1192,25 +1174,23 @@ func (p *Parser) printTrace(a ...interface{}) {
 	_, _ = fmt.Fprintln(p.traceOut, a...)
 }
 
-func (p *Parser) safePos(pos source.Pos) source.Pos {
+func (p *Parser) safePos(pos Pos) Pos {
 	fileBase := p.file.Base
 	fileSize := p.file.Size
 
 	if int(pos) < fileBase || int(pos) > fileBase+fileSize {
-		return source.Pos(fileBase + fileSize)
+		return Pos(fileBase + fileSize)
 	}
-
 	return pos
 }
 
-func trace(p *Parser, msg string) *Parser {
+func tracep(p *Parser, msg string) *Parser {
 	p.printTrace(msg, "(")
 	p.indent++
-
 	return p
 }
 
-func un(p *Parser) {
+func untracep(p *Parser) {
 	p.indent--
 	p.printTrace(")")
 }
diff --git a/vendor/github.com/d5/tengo/compiler/source/pos.go b/vendor/github.com/d5/tengo/v2/parser/pos.go
index 72128b13..f8d3898c 100644
--- a/vendor/github.com/d5/tengo/compiler/source/pos.go
+++ b/vendor/github.com/d5/tengo/v2/parser/pos.go
@@ -1,4 +1,4 @@
-package source
+package parser
 
 // Pos represents a position in the file set.
 type Pos int
diff --git a/vendor/github.com/d5/tengo/compiler/scanner/scanner.go b/vendor/github.com/d5/tengo/v2/parser/scanner.go
index 387cd8ee..f1d820a4 100644
--- a/vendor/github.com/d5/tengo/compiler/scanner/scanner.go
+++ b/vendor/github.com/d5/tengo/v2/parser/scanner.go
@@ -1,45 +1,53 @@
-/*
-	Scanner reads the Tengo source text and tokenize them.
-
-	Scanner is a modified version of Go's scanner implementation.
-
-	Copyright 2009 The Go Authors. All rights reserved.
-	Use of this source code is governed by a BSD-style
-	license that can be found in the LICENSE file.
-*/
-
-package scanner
+package parser
 
 import (
 	"fmt"
 	"unicode"
 	"unicode/utf8"
 
-	"github.com/d5/tengo/compiler/source"
-	"github.com/d5/tengo/compiler/token"
+	"github.com/d5/tengo/v2/token"
 )
 
 // byte order mark
 const bom = 0xFEFF
 
-// Scanner reads the Tengo source text.
+// ScanMode represents a scanner mode.
+type ScanMode int
+
+// List of scanner modes.
+const (
+	ScanComments ScanMode = 1 << iota
+	DontInsertSemis
+)
+
+// ScannerErrorHandler is an error handler for the scanner.
+type ScannerErrorHandler func(pos SourceFilePos, msg string)
+
+// Scanner reads the Tengo source text. It's based on Go's scanner
+// implementation.
 type Scanner struct {
-	file         *source.File // source file handle
-	src          []byte       // source
-	ch           rune         // current character
-	offset       int          // character offset
-	readOffset   int          // reading offset (position after current character)
-	lineOffset   int          // current line offset
-	insertSemi   bool         // insert a semicolon before next newline
-	errorHandler ErrorHandler // error reporting; or nil
-	errorCount   int          // number of errors encountered
-	mode         Mode
+	file         *SourceFile         // source file handle
+	src          []byte              // source
+	ch           rune                // current character
+	offset       int                 // character offset
+	readOffset   int                 // reading offset (position after current character)
+	lineOffset   int                 // current line offset
+	insertSemi   bool                // insert a semicolon before next newline
+	errorHandler ScannerErrorHandler // error reporting; or nil
+	errorCount   int                 // number of errors encountered
+	mode         ScanMode
 }
 
 // NewScanner creates a Scanner.
-func NewScanner(file *source.File, src []byte, errorHandler ErrorHandler, mode Mode) *Scanner {
+func NewScanner(
+	file *SourceFile,
+	src []byte,
+	errorHandler ScannerErrorHandler,
+	mode ScanMode,
+) *Scanner {
 	if file.Size != len(src) {
-		panic(fmt.Sprintf("file size (%d) does not match src len (%d)", file.Size, len(src)))
+		panic(fmt.Sprintf("file size (%d) does not match src len (%d)",
+			file.Size, len(src)))
 	}
 
 	s := &Scanner{
@@ -64,7 +72,11 @@ func (s *Scanner) ErrorCount() int {
 }
 
 // Scan returns a token, token literal and its position.
-func (s *Scanner) Scan() (tok token.Token, literal string, pos source.Pos) {
+func (s *Scanner) Scan() (
+	tok token.Token,
+	literal string,
+	pos Pos,
+) {
 	s.skipWhitespace()
 
 	pos = s.file.FileSetPos(s.offset)
@@ -77,7 +89,8 @@ func (s *Scanner) Scan() (tok token.Token, literal string, pos source.Pos) {
 		literal = s.scanIdentifier()
 		tok = token.Lookup(literal)
 		switch tok {
-		case token.Ident, token.Break, token.Continue, token.Return, token.Export, token.True, token.False, token.Undefined:
+		case token.Ident, token.Break, token.Continue, token.Return,
+			token.Export, token.True, token.False, token.Undefined:
 			insertSemi = true
 		}
 	case '0' <= ch && ch <= '9':
@@ -184,9 +197,11 @@ func (s *Scanner) Scan() (tok token.Token, literal string, pos source.Pos) {
 		case '^':
 			tok = s.switch2(token.Xor, token.XorAssign)
 		case '<':
-			tok = s.switch4(token.Less, token.LessEq, '<', token.Shl, token.ShlAssign)
+			tok = s.switch4(token.Less, token.LessEq, '<',
+				token.Shl, token.ShlAssign)
 		case '>':
-			tok = s.switch4(token.Greater, token.GreaterEq, '>', token.Shr, token.ShrAssign)
+			tok = s.switch4(token.Greater, token.GreaterEq, '>',
+				token.Shr, token.ShrAssign)
 		case '=':
 			tok = s.switch2(token.Assign, token.Equal)
 		case '!':
@@ -203,18 +218,17 @@ func (s *Scanner) Scan() (tok token.Token, literal string, pos source.Pos) {
 		default:
 			// next reports unexpected BOMs - don't repeat
 			if ch != bom {
-				s.error(s.file.Offset(pos), fmt.Sprintf("illegal character %#U", ch))
+				s.error(s.file.Offset(pos),
+					fmt.Sprintf("illegal character %#U", ch))
 			}
 			insertSemi = s.insertSemi // preserve insertSemi info
 			tok = token.Illegal
 			literal = string(ch)
 		}
 	}
-
 	if s.mode&DontInsertSemis == 0 {
 		s.insertSemi = insertSemi
 	}
-
 	return
 }
 
@@ -254,7 +268,6 @@ func (s *Scanner) peek() byte {
 	if s.readOffset < len(s.src) {
 		return s.src[s.readOffset]
 	}
-
 	return 0
 }
 
@@ -262,7 +275,6 @@ func (s *Scanner) error(offset int, msg string) {
 	if s.errorHandler != nil {
 		s.errorHandler(s.file.Position(s.file.FileSetPos(offset)), msg)
 	}
-
 	s.errorCount++
 }
 
@@ -310,11 +322,9 @@ exit:
 		lit = lit[:len(lit)-1]
 		numCR--
 	}
-
 	if numCR > 0 {
 		lit = StripCR(lit, lit[1] == '*')
 	}
-
 	return string(lit)
 }
 
@@ -358,7 +368,6 @@ func (s *Scanner) findLineEnd() bool {
 		}
 		s.next() // consume '/'
 	}
-
 	return false
 }
 
@@ -367,7 +376,6 @@ func (s *Scanner) scanIdentifier() string {
 	for isLetter(s.ch) || isDigit(s.ch) {
 		s.next()
 	}
-
 	return string(s.src[offs:s.offset])
 }
 
@@ -377,7 +385,9 @@ func (s *Scanner) scanMantissa(base int) {
 	}
 }
 
-func (s *Scanner) scanNumber(seenDecimalPoint bool) (tok token.Token, lit string) {
+func (s *Scanner) scanNumber(
+	seenDecimalPoint bool,
+) (tok token.Token, lit string) {
 	// digitVal(s.ch) < 10
 	offs := s.offset
 	tok = token.Int
@@ -422,7 +432,6 @@ func (s *Scanner) scanNumber(seenDecimalPoint bool) (tok token.Token, lit string
 				s.error(offs, "illegal octal number")
 			}
 		}
-
 		return
 	}
 
@@ -449,7 +458,6 @@ exponent:
 			s.error(offs, "illegal floating-point exponent")
 		}
 	}
-
 	return
 }
 
@@ -486,7 +494,8 @@ func (s *Scanner) scanEscape(quote rune) bool {
 	for n > 0 {
 		d := uint32(digitVal(s.ch))
 		if d >= base {
-			msg := fmt.Sprintf("illegal character %#U in escape sequence", s.ch)
+			msg := fmt.Sprintf(
+				"illegal character %#U in escape sequence", s.ch)
 			if s.ch < 0 {
 				msg = "escape sequence not terminated"
 			}
@@ -502,7 +511,6 @@ func (s *Scanner) scanEscape(quote rune) bool {
 		s.error(offs, "escape sequence is invalid Unicode code point")
 		return false
 	}
-
 	return true
 }
 
@@ -537,7 +545,6 @@ func (s *Scanner) scanRune() string {
 	if valid && n != 1 {
 		s.error(offs, "illegal rune literal")
 	}
-
 	return string(s.src[offs:s.offset])
 }
 
@@ -558,7 +565,6 @@ func (s *Scanner) scanString() string {
 			s.scanEscape('"')
 		}
 	}
-
 	return string(s.src[offs:s.offset])
 }
 
@@ -588,30 +594,30 @@ func (s *Scanner) scanRawString() string {
 	if hasCR {
 		lit = StripCR(lit, false)
 	}
-
 	return string(lit)
 }
 
 // StripCR removes carriage return characters.
 func StripCR(b []byte, comment bool) []byte {
 	c := make([]byte, len(b))
-
 	i := 0
 	for j, ch := range b {
-		// In a /*-style comment, don't strip \r from *\r/ (incl. sequences of \r from *\r\r...\r/)
-		// since the resulting  */ would terminate the comment too early unless the \r is immediately
-		// following the opening /* in which case it's ok because /*/ is not closed yet.
-		if ch != '\r' || comment && i > len("/*") && c[i-1] == '*' && j+1 < len(b) && b[j+1] == '/' {
+		// In a /*-style comment, don't strip \r from *\r/ (incl. sequences of
+		// \r from *\r\r...\r/) since the resulting  */ would terminate the
+		// comment too early unless the \r is immediately following the opening
+		// /* in which case it's ok because /*/ is not closed yet.
+		if ch != '\r' || comment && i > len("/*") && c[i-1] == '*' &&
+			j+1 < len(b) && b[j+1] == '/' {
 			c[i] = ch
 			i++
 		}
 	}
-
 	return c[:i]
 }
 
 func (s *Scanner) skipWhitespace() {
-	for s.ch == ' ' || s.ch == '\t' || s.ch == '\n' && !s.insertSemi || s.ch == '\r' {
+	for s.ch == ' ' || s.ch == '\t' || s.ch == '\n' && !s.insertSemi ||
+		s.ch == '\r' {
 		s.next()
 	}
 }
@@ -621,49 +627,53 @@ func (s *Scanner) switch2(tok0, tok1 token.Token) token.Token {
 		s.next()
 		return tok1
 	}
-
 	return tok0
 }
 
-func (s *Scanner) switch3(tok0, tok1 token.Token, ch2 rune, tok2 token.Token) token.Token {
+func (s *Scanner) switch3(
+	tok0, tok1 token.Token,
+	ch2 rune,
+	tok2 token.Token,
+) token.Token {
 	if s.ch == '=' {
 		s.next()
 		return tok1
 	}
-
 	if s.ch == ch2 {
 		s.next()
 		return tok2
 	}
-
 	return tok0
 }
 
-func (s *Scanner) switch4(tok0, tok1 token.Token, ch2 rune, tok2, tok3 token.Token) token.Token {
+func (s *Scanner) switch4(
+	tok0, tok1 token.Token,
+	ch2 rune,
+	tok2, tok3 token.Token,
+) token.Token {
 	if s.ch == '=' {
 		s.next()
 		return tok1
 	}
-
 	if s.ch == ch2 {
 		s.next()
 		if s.ch == '=' {
 			s.next()
 			return tok3
 		}
-
 		return tok2
 	}
-
 	return tok0
 }
 
 func isLetter(ch rune) bool {
-	return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || ch >= utf8.RuneSelf && unicode.IsLetter(ch)
+	return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' ||
+		ch >= utf8.RuneSelf && unicode.IsLetter(ch)
 }
 
 func isDigit(ch rune) bool {
-	return '0' <= ch && ch <= '9' || ch >= utf8.RuneSelf && unicode.IsDigit(ch)
+	return '0' <= ch && ch <= '9' ||
+		ch >= utf8.RuneSelf && unicode.IsDigit(ch)
 }
 
 func digitVal(ch rune) int {
@@ -675,6 +685,5 @@ func digitVal(ch rune) int {
 	case 'A' <= ch && ch <= 'F':
 		return int(ch - 'A' + 10)
 	}
-
 	return 16 // larger than any legal digit val
 }
diff --git a/vendor/github.com/d5/tengo/v2/parser/source_file.go b/vendor/github.com/d5/tengo/v2/parser/source_file.go
new file mode 100644
index 00000000..e9f4b0f5
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/parser/source_file.go
@@ -0,0 +1,231 @@
+package parser
+
+import (
+	"fmt"
+	"sort"
+)
+
+// SourceFilePos represents a position information in the file.
+type SourceFilePos struct {
+	Filename string // filename, if any
+	Offset   int    // offset, starting at 0
+	Line     int    // line number, starting at 1
+	Column   int    // column number, starting at 1 (byte count)
+}
+
+// IsValid returns true if the position is valid.
+func (p SourceFilePos) IsValid() bool {
+	return p.Line > 0
+}
+
+// String returns a string in one of several forms:
+//
+//	file:line:column    valid position with file name
+//	file:line           valid position with file name but no column (column == 0)
+//	line:column         valid position without file name
+//	line                valid position without file name and no column (column == 0)
+//	file                invalid position with file name
+//	-                   invalid position without file name
+//
+func (p SourceFilePos) String() string {
+	s := p.Filename
+	if p.IsValid() {
+		if s != "" {
+			s += ":"
+		}
+		s += fmt.Sprintf("%d", p.Line)
+		if p.Column != 0 {
+			s += fmt.Sprintf(":%d", p.Column)
+		}
+	}
+	if s == "" {
+		s = "-"
+	}
+	return s
+}
+
+// SourceFileSet represents a set of source files.
+type SourceFileSet struct {
+	Base     int           // base offset for the next file
+	Files    []*SourceFile // list of files in the order added to the set
+	LastFile *SourceFile   // cache of last file looked up
+}
+
+// NewFileSet creates a new file set.
+func NewFileSet() *SourceFileSet {
+	return &SourceFileSet{
+		Base: 1, // 0 == NoPos
+	}
+}
+
+// AddFile adds a new file in the file set.
+func (s *SourceFileSet) AddFile(filename string, base, size int) *SourceFile {
+	if base < 0 {
+		base = s.Base
+	}
+	if base < s.Base || size < 0 {
+		panic("illegal base or size")
+	}
+	f := &SourceFile{
+		set:   s,
+		Name:  filename,
+		Base:  base,
+		Size:  size,
+		Lines: []int{0},
+	}
+	base += size + 1 // +1 because EOF also has a position
+	if base < 0 {
+		panic("offset overflow (> 2G of source code in file set)")
+	}
+
+	// add the file to the file set
+	s.Base = base
+	s.Files = append(s.Files, f)
+	s.LastFile = f
+	return f
+}
+
+// File returns the file that contains the position p. If no such file is
+// found (for instance for p == NoPos), the result is nil.
+func (s *SourceFileSet) File(p Pos) (f *SourceFile) {
+	if p != NoPos {
+		f = s.file(p)
+	}
+	return
+}
+
+// Position converts a SourcePos p in the fileset into a SourceFilePos value.
+func (s *SourceFileSet) Position(p Pos) (pos SourceFilePos) {
+	if p != NoPos {
+		if f := s.file(p); f != nil {
+			return f.position(p)
+		}
+	}
+	return
+}
+
+func (s *SourceFileSet) file(p Pos) *SourceFile {
+	// common case: p is in last file
+	f := s.LastFile
+	if f != nil && f.Base <= int(p) && int(p) <= f.Base+f.Size {
+		return f
+	}
+
+	// p is not in last file - search all files
+	if i := searchFiles(s.Files, int(p)); i >= 0 {
+		f := s.Files[i]
+
+		// f.base <= int(p) by definition of searchFiles
+		if int(p) <= f.Base+f.Size {
+			s.LastFile = f // race is ok - s.last is only a cache
+			return f
+		}
+	}
+	return nil
+}
+
+func searchFiles(a []*SourceFile, x int) int {
+	return sort.Search(len(a), func(i int) bool { return a[i].Base > x }) - 1
+}
+
+// SourceFile represents a source file.
+type SourceFile struct {
+	// SourceFile set for the file
+	set *SourceFileSet
+	// SourceFile name as provided to AddFile
+	Name string
+	// SourcePos value range for this file is [base...base+size]
+	Base int
+	// SourceFile size as provided to AddFile
+	Size int
+	// Lines contains the offset of the first character for each line
+	// (the first entry is always 0)
+	Lines []int
+}
+
+// Set returns SourceFileSet.
+func (f *SourceFile) Set() *SourceFileSet {
+	return f.set
+}
+
+// LineCount returns the current number of lines.
+func (f *SourceFile) LineCount() int {
+	return len(f.Lines)
+}
+
+// AddLine adds a new line.
+func (f *SourceFile) AddLine(offset int) {
+	i := len(f.Lines)
+	if (i == 0 || f.Lines[i-1] < offset) && offset < f.Size {
+		f.Lines = append(f.Lines, offset)
+	}
+}
+
+// LineStart returns the position of the first character in the line.
+func (f *SourceFile) LineStart(line int) Pos {
+	if line < 1 {
+		panic("illegal line number (line numbering starts at 1)")
+	}
+	if line > len(f.Lines) {
+		panic("illegal line number")
+	}
+	return Pos(f.Base + f.Lines[line-1])
+}
+
+// FileSetPos returns the position in the file set.
+func (f *SourceFile) FileSetPos(offset int) Pos {
+	if offset > f.Size {
+		panic("illegal file offset")
+	}
+	return Pos(f.Base + offset)
+}
+
+// Offset translates the file set position into the file offset.
+func (f *SourceFile) Offset(p Pos) int {
+	if int(p) < f.Base || int(p) > f.Base+f.Size {
+		panic("illegal SourcePos value")
+	}
+	return int(p) - f.Base
+}
+
+// Position translates the file set position into the file position.
+func (f *SourceFile) Position(p Pos) (pos SourceFilePos) {
+	if p != NoPos {
+		if int(p) < f.Base || int(p) > f.Base+f.Size {
+			panic("illegal SourcePos value")
+		}
+		pos = f.position(p)
+	}
+	return
+}
+
+func (f *SourceFile) position(p Pos) (pos SourceFilePos) {
+	offset := int(p) - f.Base
+	pos.Offset = offset
+	pos.Filename, pos.Line, pos.Column = f.unpack(offset)
+	return
+}
+
+func (f *SourceFile) unpack(offset int) (filename string, line, column int) {
+	filename = f.Name
+	if i := searchInts(f.Lines, offset); i >= 0 {
+		line, column = i+1, offset-f.Lines[i]+1
+	}
+	return
+}
+
+func searchInts(a []int, x int) int {
+	// This function body is a manually inlined version of:
+	//   return sort.Search(len(a), func(i int) bool { return a[i] > x }) - 1
+	i, j := 0, len(a)
+	for i < j {
+		h := i + (j-i)/2 // avoid overflow when computing h
+		// i ≤ h < j
+		if a[h] <= x {
+			i = h + 1
+		} else {
+			j = h
+		}
+	}
+	return i - 1
+}
diff --git a/vendor/github.com/d5/tengo/v2/parser/stmt.go b/vendor/github.com/d5/tengo/v2/parser/stmt.go
new file mode 100644
index 00000000..c0848c48
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/parser/stmt.go
@@ -0,0 +1,349 @@
+package parser
+
+import (
+	"strings"
+
+	"github.com/d5/tengo/v2/token"
+)
+
+// Stmt represents a statement in the AST.
+type Stmt interface {
+	Node
+	stmtNode()
+}
+
+// AssignStmt represents an assignment statement.
+type AssignStmt struct {
+	LHS      []Expr
+	RHS      []Expr
+	Token    token.Token
+	TokenPos Pos
+}
+
+func (s *AssignStmt) stmtNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (s *AssignStmt) Pos() Pos {
+	return s.LHS[0].Pos()
+}
+
+// End returns the position of first character immediately after the node.
+func (s *AssignStmt) End() Pos {
+	return s.RHS[len(s.RHS)-1].End()
+}
+
+func (s *AssignStmt) String() string {
+	var lhs, rhs []string
+	for _, e := range s.LHS {
+		lhs = append(lhs, e.String())
+	}
+	for _, e := range s.RHS {
+		rhs = append(rhs, e.String())
+	}
+	return strings.Join(lhs, ", ") + " " + s.Token.String() +
+		" " + strings.Join(rhs, ", ")
+}
+
+// BadStmt represents a bad statement.
+type BadStmt struct {
+	From Pos
+	To   Pos
+}
+
+func (s *BadStmt) stmtNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (s *BadStmt) Pos() Pos {
+	return s.From
+}
+
+// End returns the position of first character immediately after the node.
+func (s *BadStmt) End() Pos {
+	return s.To
+}
+
+func (s *BadStmt) String() string {
+	return "<bad statement>"
+}
+
+// BlockStmt represents a block statement.
+type BlockStmt struct {
+	Stmts  []Stmt
+	LBrace Pos
+	RBrace Pos
+}
+
+func (s *BlockStmt) stmtNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (s *BlockStmt) Pos() Pos {
+	return s.LBrace
+}
+
+// End returns the position of first character immediately after the node.
+func (s *BlockStmt) End() Pos {
+	return s.RBrace + 1
+}
+
+func (s *BlockStmt) String() string {
+	var list []string
+	for _, e := range s.Stmts {
+		list = append(list, e.String())
+	}
+	return "{" + strings.Join(list, "; ") + "}"
+}
+
+// BranchStmt represents a branch statement.
+type BranchStmt struct {
+	Token    token.Token
+	TokenPos Pos
+	Label    *Ident
+}
+
+func (s *BranchStmt) stmtNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (s *BranchStmt) Pos() Pos {
+	return s.TokenPos
+}
+
+// End returns the position of first character immediately after the node.
+func (s *BranchStmt) End() Pos {
+	if s.Label != nil {
+		return s.Label.End()
+	}
+
+	return Pos(int(s.TokenPos) + len(s.Token.String()))
+}
+
+func (s *BranchStmt) String() string {
+	var label string
+	if s.Label != nil {
+		label = " " + s.Label.Name
+	}
+	return s.Token.String() + label
+}
+
+// EmptyStmt represents an empty statement.
+type EmptyStmt struct {
+	Semicolon Pos
+	Implicit  bool
+}
+
+func (s *EmptyStmt) stmtNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (s *EmptyStmt) Pos() Pos {
+	return s.Semicolon
+}
+
+// End returns the position of first character immediately after the node.
+func (s *EmptyStmt) End() Pos {
+	if s.Implicit {
+		return s.Semicolon
+	}
+	return s.Semicolon + 1
+}
+
+func (s *EmptyStmt) String() string {
+	return ";"
+}
+
+// ExportStmt represents an export statement.
+type ExportStmt struct {
+	ExportPos Pos
+	Result    Expr
+}
+
+func (s *ExportStmt) stmtNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (s *ExportStmt) Pos() Pos {
+	return s.ExportPos
+}
+
+// End returns the position of first character immediately after the node.
+func (s *ExportStmt) End() Pos {
+	return s.Result.End()
+}
+
+func (s *ExportStmt) String() string {
+	return "export " + s.Result.String()
+}
+
+// ExprStmt represents an expression statement.
+type ExprStmt struct {
+	Expr Expr
+}
+
+func (s *ExprStmt) stmtNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (s *ExprStmt) Pos() Pos {
+	return s.Expr.Pos()
+}
+
+// End returns the position of first character immediately after the node.
+func (s *ExprStmt) End() Pos {
+	return s.Expr.End()
+}
+
+func (s *ExprStmt) String() string {
+	return s.Expr.String()
+}
+
+// ForInStmt represents a for-in statement.
+type ForInStmt struct {
+	ForPos   Pos
+	Key      *Ident
+	Value    *Ident
+	Iterable Expr
+	Body     *BlockStmt
+}
+
+func (s *ForInStmt) stmtNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (s *ForInStmt) Pos() Pos {
+	return s.ForPos
+}
+
+// End returns the position of first character immediately after the node.
+func (s *ForInStmt) End() Pos {
+	return s.Body.End()
+}
+
+func (s *ForInStmt) String() string {
+	if s.Value != nil {
+		return "for " + s.Key.String() + ", " + s.Value.String() +
+			" in " + s.Iterable.String() + " " + s.Body.String()
+	}
+	return "for " + s.Key.String() + " in " + s.Iterable.String() +
+		" " + s.Body.String()
+}
+
+// ForStmt represents a for statement.
+type ForStmt struct {
+	ForPos Pos
+	Init   Stmt
+	Cond   Expr
+	Post   Stmt
+	Body   *BlockStmt
+}
+
+func (s *ForStmt) stmtNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (s *ForStmt) Pos() Pos {
+	return s.ForPos
+}
+
+// End returns the position of first character immediately after the node.
+func (s *ForStmt) End() Pos {
+	return s.Body.End()
+}
+
+func (s *ForStmt) String() string {
+	var init, cond, post string
+	if s.Init != nil {
+		init = s.Init.String()
+	}
+	if s.Cond != nil {
+		cond = s.Cond.String() + " "
+	}
+	if s.Post != nil {
+		post = s.Post.String()
+	}
+
+	if init != "" || post != "" {
+		return "for " + init + " ; " + cond + " ; " + post + s.Body.String()
+	}
+	return "for " + cond + s.Body.String()
+}
+
+// IfStmt represents an if statement.
+type IfStmt struct {
+	IfPos Pos
+	Init  Stmt
+	Cond  Expr
+	Body  *BlockStmt
+	Else  Stmt // else branch; or nil
+}
+
+func (s *IfStmt) stmtNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (s *IfStmt) Pos() Pos {
+	return s.IfPos
+}
+
+// End returns the position of first character immediately after the node.
+func (s *IfStmt) End() Pos {
+	if s.Else != nil {
+		return s.Else.End()
+	}
+	return s.Body.End()
+}
+
+func (s *IfStmt) String() string {
+	var initStmt, elseStmt string
+	if s.Init != nil {
+		initStmt = s.Init.String() + "; "
+	}
+	if s.Else != nil {
+		elseStmt = " else " + s.Else.String()
+	}
+	return "if " + initStmt + s.Cond.String() + " " +
+		s.Body.String() + elseStmt
+}
+
+// IncDecStmt represents increment or decrement statement.
+type IncDecStmt struct {
+	Expr     Expr
+	Token    token.Token
+	TokenPos Pos
+}
+
+func (s *IncDecStmt) stmtNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (s *IncDecStmt) Pos() Pos {
+	return s.Expr.Pos()
+}
+
+// End returns the position of first character immediately after the node.
+func (s *IncDecStmt) End() Pos {
+	return Pos(int(s.TokenPos) + 2)
+}
+
+func (s *IncDecStmt) String() string {
+	return s.Expr.String() + s.Token.String()
+}
+
+// ReturnStmt represents a return statement.
+type ReturnStmt struct {
+	ReturnPos Pos
+	Result    Expr
+}
+
+func (s *ReturnStmt) stmtNode() {}
+
+// Pos returns the position of first character belonging to the node.
+func (s *ReturnStmt) Pos() Pos {
+	return s.ReturnPos
+}
+
+// End returns the position of first character immediately after the node.
+func (s *ReturnStmt) End() Pos {
+	if s.Result != nil {
+		return s.Result.End()
+	}
+	return s.ReturnPos + 6
+}
+
+func (s *ReturnStmt) String() string {
+	if s.Result != nil {
+		return "return " + s.Result.String()
+	}
+	return "return"
+}
diff --git a/vendor/github.com/d5/tengo/v2/script.go b/vendor/github.com/d5/tengo/v2/script.go
new file mode 100644
index 00000000..906771d9
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/script.go
@@ -0,0 +1,313 @@
+package tengo
+
+import (
+	"context"
+	"fmt"
+	"sync"
+
+	"github.com/d5/tengo/v2/parser"
+)
+
+// Script can simplify compilation and execution of embedded scripts.
+type Script struct {
+	variables        map[string]*Variable
+	modules          *ModuleMap
+	input            []byte
+	maxAllocs        int64
+	maxConstObjects  int
+	enableFileImport bool
+}
+
+// NewScript creates a Script instance with an input script.
+func NewScript(input []byte) *Script {
+	return &Script{
+		variables:       make(map[string]*Variable),
+		input:           input,
+		maxAllocs:       -1,
+		maxConstObjects: -1,
+	}
+}
+
+// Add adds a new variable or updates an existing variable to the script.
+func (s *Script) Add(name string, value interface{}) error {
+	obj, err := FromInterface(value)
+	if err != nil {
+		return err
+	}
+	s.variables[name] = &Variable{
+		name:  name,
+		value: obj,
+	}
+	return nil
+}
+
+// Remove removes (undefines) an existing variable for the script. It returns
+// false if the variable name is not defined.
+func (s *Script) Remove(name string) bool {
+	if _, ok := s.variables[name]; !ok {
+		return false
+	}
+	delete(s.variables, name)
+	return true
+}
+
+// SetImports sets import modules.
+func (s *Script) SetImports(modules *ModuleMap) {
+	s.modules = modules
+}
+
+// SetMaxAllocs sets the maximum number of objects allocations during the run
+// time. Compiled script will return ErrObjectAllocLimit error if it
+// exceeds this limit.
+func (s *Script) SetMaxAllocs(n int64) {
+	s.maxAllocs = n
+}
+
+// SetMaxConstObjects sets the maximum number of objects in the compiled
+// constants.
+func (s *Script) SetMaxConstObjects(n int) {
+	s.maxConstObjects = n
+}
+
+// EnableFileImport enables or disables module loading from local files. Local
+// file modules are disabled by default.
+func (s *Script) EnableFileImport(enable bool) {
+	s.enableFileImport = enable
+}
+
+// Compile compiles the script with all the defined variables, and, returns
+// Compiled object.
+func (s *Script) Compile() (*Compiled, error) {
+	symbolTable, globals, err := s.prepCompile()
+	if err != nil {
+		return nil, err
+	}
+
+	fileSet := parser.NewFileSet()
+	srcFile := fileSet.AddFile("(main)", -1, len(s.input))
+	p := parser.NewParser(srcFile, s.input, nil)
+	file, err := p.ParseFile()
+	if err != nil {
+		return nil, err
+	}
+
+	c := NewCompiler(srcFile, symbolTable, nil, s.modules, nil)
+	c.EnableFileImport(s.enableFileImport)
+	if err := c.Compile(file); err != nil {
+		return nil, err
+	}
+
+	// reduce globals size
+	globals = globals[:symbolTable.MaxSymbols()+1]
+
+	// global symbol names to indexes
+	globalIndexes := make(map[string]int, len(globals))
+	for _, name := range symbolTable.Names() {
+		symbol, _, _ := symbolTable.Resolve(name)
+		if symbol.Scope == ScopeGlobal {
+			globalIndexes[name] = symbol.Index
+		}
+	}
+
+	// remove duplicates from constants
+	bytecode := c.Bytecode()
+	bytecode.RemoveDuplicates()
+
+	// check the constant objects limit
+	if s.maxConstObjects >= 0 {
+		cnt := bytecode.CountObjects()
+		if cnt > s.maxConstObjects {
+			return nil, fmt.Errorf("exceeding constant objects limit: %d", cnt)
+		}
+	}
+	return &Compiled{
+		globalIndexes: globalIndexes,
+		bytecode:      bytecode,
+		globals:       globals,
+		maxAllocs:     s.maxAllocs,
+	}, nil
+}
+
+// Run compiles and runs the scripts. Use returned compiled object to access
+// global variables.
+func (s *Script) Run() (compiled *Compiled, err error) {
+	compiled, err = s.Compile()
+	if err != nil {
+		return
+	}
+	err = compiled.Run()
+	return
+}
+
+// RunContext is like Run but includes a context.
+func (s *Script) RunContext(
+	ctx context.Context,
+) (compiled *Compiled, err error) {
+	compiled, err = s.Compile()
+	if err != nil {
+		return
+	}
+	err = compiled.RunContext(ctx)
+	return
+}
+
+func (s *Script) prepCompile() (
+	symbolTable *SymbolTable,
+	globals []Object,
+	err error,
+) {
+	var names []string
+	for name := range s.variables {
+		names = append(names, name)
+	}
+
+	symbolTable = NewSymbolTable()
+	for idx, fn := range builtinFuncs {
+		symbolTable.DefineBuiltin(idx, fn.Name)
+	}
+
+	globals = make([]Object, GlobalsSize)
+
+	for idx, name := range names {
+		symbol := symbolTable.Define(name)
+		if symbol.Index != idx {
+			panic(fmt.Errorf("wrong symbol index: %d != %d",
+				idx, symbol.Index))
+		}
+		globals[symbol.Index] = s.variables[name].value
+	}
+	return
+}
+
+// Compiled is a compiled instance of the user script. Use Script.Compile() to
+// create Compiled object.
+type Compiled struct {
+	globalIndexes map[string]int // global symbol name to index
+	bytecode      *Bytecode
+	globals       []Object
+	maxAllocs     int64
+	lock          sync.RWMutex
+}
+
+// Run executes the compiled script in the virtual machine.
+func (c *Compiled) Run() error {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	v := NewVM(c.bytecode, c.globals, c.maxAllocs)
+	return v.Run()
+}
+
+// RunContext is like Run but includes a context.
+func (c *Compiled) RunContext(ctx context.Context) (err error) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	v := NewVM(c.bytecode, c.globals, c.maxAllocs)
+	ch := make(chan error, 1)
+	go func() {
+		ch <- v.Run()
+	}()
+
+	select {
+	case <-ctx.Done():
+		v.Abort()
+		<-ch
+		err = ctx.Err()
+	case err = <-ch:
+	}
+	return
+}
+
+// Clone creates a new copy of Compiled. Cloned copies are safe for concurrent
+// use by multiple goroutines.
+func (c *Compiled) Clone() *Compiled {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	clone := &Compiled{
+		globalIndexes: c.globalIndexes,
+		bytecode:      c.bytecode,
+		globals:       make([]Object, len(c.globals)),
+		maxAllocs:     c.maxAllocs,
+	}
+	// copy global objects
+	for idx, g := range c.globals {
+		if g != nil {
+			clone.globals[idx] = g
+		}
+	}
+	return clone
+}
+
+// IsDefined returns true if the variable name is defined (has value) before or
+// after the execution.
+func (c *Compiled) IsDefined(name string) bool {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+
+	idx, ok := c.globalIndexes[name]
+	if !ok {
+		return false
+	}
+	v := c.globals[idx]
+	if v == nil {
+		return false
+	}
+	return v != UndefinedValue
+}
+
+// Get returns a variable identified by the name.
+func (c *Compiled) Get(name string) *Variable {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+
+	value := UndefinedValue
+	if idx, ok := c.globalIndexes[name]; ok {
+		value = c.globals[idx]
+		if value == nil {
+			value = UndefinedValue
+		}
+	}
+	return &Variable{
+		name:  name,
+		value: value,
+	}
+}
+
+// GetAll returns all the variables that are defined by the compiled script.
+func (c *Compiled) GetAll() []*Variable {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+
+	var vars []*Variable
+	for name, idx := range c.globalIndexes {
+		value := c.globals[idx]
+		if value == nil {
+			value = UndefinedValue
+		}
+		vars = append(vars, &Variable{
+			name:  name,
+			value: value,
+		})
+	}
+	return vars
+}
+
+// Set replaces the value of a global variable identified by the name. An error
+// will be returned if the name was not defined during compilation.
+func (c *Compiled) Set(name string, value interface{}) error {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	obj, err := FromInterface(value)
+	if err != nil {
+		return err
+	}
+	idx, ok := c.globalIndexes[name]
+	if !ok {
+		return fmt.Errorf("'%s' is not defined", name)
+	}
+	c.globals[idx] = obj
+	return nil
+}
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/base64.go b/vendor/github.com/d5/tengo/v2/stdlib/base64.go
new file mode 100644
index 00000000..b4c5b56e
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/base64.go
@@ -0,0 +1,34 @@
+package stdlib
+
+import (
+	"encoding/base64"
+
+	"github.com/d5/tengo/v2"
+)
+
+var base64Module = map[string]tengo.Object{
+	"encode": &tengo.UserFunction{
+		Value: FuncAYRS(base64.StdEncoding.EncodeToString),
+	},
+	"decode": &tengo.UserFunction{
+		Value: FuncASRYE(base64.StdEncoding.DecodeString),
+	},
+	"raw_encode": &tengo.UserFunction{
+		Value: FuncAYRS(base64.RawStdEncoding.EncodeToString),
+	},
+	"raw_decode": &tengo.UserFunction{
+		Value: FuncASRYE(base64.RawStdEncoding.DecodeString),
+	},
+	"url_encode": &tengo.UserFunction{
+		Value: FuncAYRS(base64.URLEncoding.EncodeToString),
+	},
+	"url_decode": &tengo.UserFunction{
+		Value: FuncASRYE(base64.URLEncoding.DecodeString),
+	},
+	"raw_url_encode": &tengo.UserFunction{
+		Value: FuncAYRS(base64.RawURLEncoding.EncodeToString),
+	},
+	"raw_url_decode": &tengo.UserFunction{
+		Value: FuncASRYE(base64.RawURLEncoding.DecodeString),
+	},
+}
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/builtin_modules.go b/vendor/github.com/d5/tengo/v2/stdlib/builtin_modules.go
new file mode 100644
index 00000000..cf0e9621
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/builtin_modules.go
@@ -0,0 +1,18 @@
+package stdlib
+
+import (
+	"github.com/d5/tengo/v2"
+)
+
+// BuiltinModules are builtin type standard library modules.
+var BuiltinModules = map[string]map[string]tengo.Object{
+	"math":   mathModule,
+	"os":     osModule,
+	"text":   textModule,
+	"times":  timesModule,
+	"rand":   randModule,
+	"fmt":    fmtModule,
+	"json":   jsonModule,
+	"base64": base64Module,
+	"hex":    hexModule,
+}
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/errors.go b/vendor/github.com/d5/tengo/v2/stdlib/errors.go
new file mode 100644
index 00000000..ad83c6f8
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/errors.go
@@ -0,0 +1,12 @@
+package stdlib
+
+import (
+	"github.com/d5/tengo/v2"
+)
+
+func wrapError(err error) tengo.Object {
+	if err == nil {
+		return tengo.TrueValue
+	}
+	return &tengo.Error{Value: &tengo.String{Value: err.Error()}}
+}
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/fmt.go b/vendor/github.com/d5/tengo/v2/stdlib/fmt.go
new file mode 100644
index 00000000..9945277f
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/fmt.go
@@ -0,0 +1,101 @@
+package stdlib
+
+import (
+	"fmt"
+
+	"github.com/d5/tengo/v2"
+)
+
+var fmtModule = map[string]tengo.Object{
+	"print":   &tengo.UserFunction{Name: "print", Value: fmtPrint},
+	"printf":  &tengo.UserFunction{Name: "printf", Value: fmtPrintf},
+	"println": &tengo.UserFunction{Name: "println", Value: fmtPrintln},
+	"sprintf": &tengo.UserFunction{Name: "sprintf", Value: fmtSprintf},
+}
+
+func fmtPrint(args ...tengo.Object) (ret tengo.Object, err error) {
+	printArgs, err := getPrintArgs(args...)
+	if err != nil {
+		return nil, err
+	}
+	_, _ = fmt.Print(printArgs...)
+	return nil, nil
+}
+
+func fmtPrintf(args ...tengo.Object) (ret tengo.Object, err error) {
+	numArgs := len(args)
+	if numArgs == 0 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+
+	format, ok := args[0].(*tengo.String)
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "format",
+			Expected: "string",
+			Found:    args[0].TypeName(),
+		}
+	}
+	if numArgs == 1 {
+		fmt.Print(format)
+		return nil, nil
+	}
+
+	s, err := tengo.Format(format.Value, args[1:]...)
+	if err != nil {
+		return nil, err
+	}
+	fmt.Print(s)
+	return nil, nil
+}
+
+func fmtPrintln(args ...tengo.Object) (ret tengo.Object, err error) {
+	printArgs, err := getPrintArgs(args...)
+	if err != nil {
+		return nil, err
+	}
+	printArgs = append(printArgs, "\n")
+	_, _ = fmt.Print(printArgs...)
+	return nil, nil
+}
+
+func fmtSprintf(args ...tengo.Object) (ret tengo.Object, err error) {
+	numArgs := len(args)
+	if numArgs == 0 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+
+	format, ok := args[0].(*tengo.String)
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "format",
+			Expected: "string",
+			Found:    args[0].TypeName(),
+		}
+	}
+	if numArgs == 1 {
+		// okay to return 'format' directly as String is immutable
+		return format, nil
+	}
+	s, err := tengo.Format(format.Value, args[1:]...)
+	if err != nil {
+		return nil, err
+	}
+	return &tengo.String{Value: s}, nil
+}
+
+func getPrintArgs(args ...tengo.Object) ([]interface{}, error) {
+	var printArgs []interface{}
+	l := 0
+	for _, arg := range args {
+		s, _ := tengo.ToString(arg)
+		slen := len(s)
+		// make sure length does not exceed the limit
+		if l+slen > tengo.MaxStringLen {
+			return nil, tengo.ErrStringLimit
+		}
+		l += slen
+		printArgs = append(printArgs, s)
+	}
+	return printArgs, nil
+}
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/func_typedefs.go b/vendor/github.com/d5/tengo/v2/stdlib/func_typedefs.go
new file mode 100644
index 00000000..fdac933c
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/func_typedefs.go
@@ -0,0 +1,1049 @@
+package stdlib
+
+import (
+	"fmt"
+
+	"github.com/d5/tengo/v2"
+)
+
+// FuncAR transform a function of 'func()' signature into CallableFunc type.
+func FuncAR(fn func()) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 0 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		fn()
+		return tengo.UndefinedValue, nil
+	}
+}
+
+// FuncARI transform a function of 'func() int' signature into CallableFunc
+// type.
+func FuncARI(fn func() int) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 0 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		return &tengo.Int{Value: int64(fn())}, nil
+	}
+}
+
+// FuncARI64 transform a function of 'func() int64' signature into CallableFunc
+// type.
+func FuncARI64(fn func() int64) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 0 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		return &tengo.Int{Value: fn()}, nil
+	}
+}
+
+// FuncAI64RI64 transform a function of 'func(int64) int64' signature into
+// CallableFunc type.
+func FuncAI64RI64(fn func(int64) int64) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+
+		i1, ok := tengo.ToInt64(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "int(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		return &tengo.Int{Value: fn(i1)}, nil
+	}
+}
+
+// FuncAI64R transform a function of 'func(int64)' signature into CallableFunc
+// type.
+func FuncAI64R(fn func(int64)) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+
+		i1, ok := tengo.ToInt64(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "int(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		fn(i1)
+		return tengo.UndefinedValue, nil
+	}
+}
+
+// FuncARB transform a function of 'func() bool' signature into CallableFunc
+// type.
+func FuncARB(fn func() bool) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 0 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		if fn() {
+			return tengo.TrueValue, nil
+		}
+		return tengo.FalseValue, nil
+	}
+}
+
+// FuncARE transform a function of 'func() error' signature into CallableFunc
+// type.
+func FuncARE(fn func() error) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 0 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		return wrapError(fn()), nil
+	}
+}
+
+// FuncARS transform a function of 'func() string' signature into CallableFunc
+// type.
+func FuncARS(fn func() string) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 0 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s := fn()
+		if len(s) > tengo.MaxStringLen {
+			return nil, tengo.ErrStringLimit
+		}
+		return &tengo.String{Value: s}, nil
+	}
+}
+
+// FuncARSE transform a function of 'func() (string, error)' signature into
+// CallableFunc type.
+func FuncARSE(fn func() (string, error)) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 0 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		res, err := fn()
+		if err != nil {
+			return wrapError(err), nil
+		}
+		if len(res) > tengo.MaxStringLen {
+			return nil, tengo.ErrStringLimit
+		}
+		return &tengo.String{Value: res}, nil
+	}
+}
+
+// FuncARYE transform a function of 'func() ([]byte, error)' signature into
+// CallableFunc type.
+func FuncARYE(fn func() ([]byte, error)) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 0 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		res, err := fn()
+		if err != nil {
+			return wrapError(err), nil
+		}
+		if len(res) > tengo.MaxBytesLen {
+			return nil, tengo.ErrBytesLimit
+		}
+		return &tengo.Bytes{Value: res}, nil
+	}
+}
+
+// FuncARF transform a function of 'func() float64' signature into CallableFunc
+// type.
+func FuncARF(fn func() float64) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 0 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		return &tengo.Float{Value: fn()}, nil
+	}
+}
+
+// FuncARSs transform a function of 'func() []string' signature into
+// CallableFunc type.
+func FuncARSs(fn func() []string) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 0 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		arr := &tengo.Array{}
+		for _, elem := range fn() {
+			if len(elem) > tengo.MaxStringLen {
+				return nil, tengo.ErrStringLimit
+			}
+			arr.Value = append(arr.Value, &tengo.String{Value: elem})
+		}
+		return arr, nil
+	}
+}
+
+// FuncARIsE transform a function of 'func() ([]int, error)' signature into
+// CallableFunc type.
+func FuncARIsE(fn func() ([]int, error)) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 0 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		res, err := fn()
+		if err != nil {
+			return wrapError(err), nil
+		}
+		arr := &tengo.Array{}
+		for _, v := range res {
+			arr.Value = append(arr.Value, &tengo.Int{Value: int64(v)})
+		}
+		return arr, nil
+	}
+}
+
+// FuncAIRIs transform a function of 'func(int) []int' signature into
+// CallableFunc type.
+func FuncAIRIs(fn func(int) []int) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		i1, ok := tengo.ToInt(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "int(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		res := fn(i1)
+		arr := &tengo.Array{}
+		for _, v := range res {
+			arr.Value = append(arr.Value, &tengo.Int{Value: int64(v)})
+		}
+		return arr, nil
+	}
+}
+
+// FuncAFRF transform a function of 'func(float64) float64' signature into
+// CallableFunc type.
+func FuncAFRF(fn func(float64) float64) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		f1, ok := tengo.ToFloat64(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "float(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		return &tengo.Float{Value: fn(f1)}, nil
+	}
+}
+
+// FuncAIR transform a function of 'func(int)' signature into CallableFunc type.
+func FuncAIR(fn func(int)) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		i1, ok := tengo.ToInt(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "int(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		fn(i1)
+		return tengo.UndefinedValue, nil
+	}
+}
+
+// FuncAIRF transform a function of 'func(int) float64' signature into
+// CallableFunc type.
+func FuncAIRF(fn func(int) float64) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		i1, ok := tengo.ToInt(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "int(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		return &tengo.Float{Value: fn(i1)}, nil
+	}
+}
+
+// FuncAFRI transform a function of 'func(float64) int' signature into
+// CallableFunc type.
+func FuncAFRI(fn func(float64) int) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		f1, ok := tengo.ToFloat64(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "float(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		return &tengo.Int{Value: int64(fn(f1))}, nil
+	}
+}
+
+// FuncAFFRF transform a function of 'func(float64, float64) float64' signature
+// into CallableFunc type.
+func FuncAFFRF(fn func(float64, float64) float64) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 2 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		f1, ok := tengo.ToFloat64(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "float(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		f2, ok := tengo.ToFloat64(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "second",
+				Expected: "float(compatible)",
+				Found:    args[1].TypeName(),
+			}
+		}
+		return &tengo.Float{Value: fn(f1, f2)}, nil
+	}
+}
+
+// FuncAIFRF transform a function of 'func(int, float64) float64' signature
+// into CallableFunc type.
+func FuncAIFRF(fn func(int, float64) float64) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 2 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		i1, ok := tengo.ToInt(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "int(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		f2, ok := tengo.ToFloat64(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "second",
+				Expected: "float(compatible)",
+				Found:    args[1].TypeName(),
+			}
+		}
+		return &tengo.Float{Value: fn(i1, f2)}, nil
+	}
+}
+
+// FuncAFIRF transform a function of 'func(float64, int) float64' signature
+// into CallableFunc type.
+func FuncAFIRF(fn func(float64, int) float64) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 2 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		f1, ok := tengo.ToFloat64(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "float(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		i2, ok := tengo.ToInt(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "second",
+				Expected: "int(compatible)",
+				Found:    args[1].TypeName(),
+			}
+		}
+		return &tengo.Float{Value: fn(f1, i2)}, nil
+	}
+}
+
+// FuncAFIRB transform a function of 'func(float64, int) bool' signature
+// into CallableFunc type.
+func FuncAFIRB(fn func(float64, int) bool) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 2 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		f1, ok := tengo.ToFloat64(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "float(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		i2, ok := tengo.ToInt(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "second",
+				Expected: "int(compatible)",
+				Found:    args[1].TypeName(),
+			}
+		}
+		if fn(f1, i2) {
+			return tengo.TrueValue, nil
+		}
+		return tengo.FalseValue, nil
+	}
+}
+
+// FuncAFRB transform a function of 'func(float64) bool' signature
+// into CallableFunc type.
+func FuncAFRB(fn func(float64) bool) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		f1, ok := tengo.ToFloat64(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "float(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		if fn(f1) {
+			return tengo.TrueValue, nil
+		}
+		return tengo.FalseValue, nil
+	}
+}
+
+// FuncASRS transform a function of 'func(string) string' signature into
+// CallableFunc type. User function will return 'true' if underlying native
+// function returns nil.
+func FuncASRS(fn func(string) string) tengo.CallableFunc {
+	return func(args ...tengo.Object) (tengo.Object, error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		s := fn(s1)
+		if len(s) > tengo.MaxStringLen {
+			return nil, tengo.ErrStringLimit
+		}
+		return &tengo.String{Value: s}, nil
+	}
+}
+
+// FuncASRSs transform a function of 'func(string) []string' signature into
+// CallableFunc type.
+func FuncASRSs(fn func(string) []string) tengo.CallableFunc {
+	return func(args ...tengo.Object) (tengo.Object, error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		res := fn(s1)
+		arr := &tengo.Array{}
+		for _, elem := range res {
+			if len(elem) > tengo.MaxStringLen {
+				return nil, tengo.ErrStringLimit
+			}
+			arr.Value = append(arr.Value, &tengo.String{Value: elem})
+		}
+		return arr, nil
+	}
+}
+
+// FuncASRSE transform a function of 'func(string) (string, error)' signature
+// into CallableFunc type. User function will return 'true' if underlying
+// native function returns nil.
+func FuncASRSE(fn func(string) (string, error)) tengo.CallableFunc {
+	return func(args ...tengo.Object) (tengo.Object, error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		res, err := fn(s1)
+		if err != nil {
+			return wrapError(err), nil
+		}
+		if len(res) > tengo.MaxStringLen {
+			return nil, tengo.ErrStringLimit
+		}
+		return &tengo.String{Value: res}, nil
+	}
+}
+
+// FuncASRE transform a function of 'func(string) error' signature into
+// CallableFunc type. User function will return 'true' if underlying native
+// function returns nil.
+func FuncASRE(fn func(string) error) tengo.CallableFunc {
+	return func(args ...tengo.Object) (tengo.Object, error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		return wrapError(fn(s1)), nil
+	}
+}
+
+// FuncASSRE transform a function of 'func(string, string) error' signature
+// into CallableFunc type. User function will return 'true' if underlying
+// native function returns nil.
+func FuncASSRE(fn func(string, string) error) tengo.CallableFunc {
+	return func(args ...tengo.Object) (tengo.Object, error) {
+		if len(args) != 2 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		s2, ok := tengo.ToString(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "second",
+				Expected: "string(compatible)",
+				Found:    args[1].TypeName(),
+			}
+		}
+		return wrapError(fn(s1, s2)), nil
+	}
+}
+
+// FuncASSRSs transform a function of 'func(string, string) []string'
+// signature into CallableFunc type.
+func FuncASSRSs(fn func(string, string) []string) tengo.CallableFunc {
+	return func(args ...tengo.Object) (tengo.Object, error) {
+		if len(args) != 2 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		s2, ok := tengo.ToString(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[1].TypeName(),
+			}
+		}
+		arr := &tengo.Array{}
+		for _, res := range fn(s1, s2) {
+			if len(res) > tengo.MaxStringLen {
+				return nil, tengo.ErrStringLimit
+			}
+			arr.Value = append(arr.Value, &tengo.String{Value: res})
+		}
+		return arr, nil
+	}
+}
+
+// FuncASSIRSs transform a function of 'func(string, string, int) []string'
+// signature into CallableFunc type.
+func FuncASSIRSs(fn func(string, string, int) []string) tengo.CallableFunc {
+	return func(args ...tengo.Object) (tengo.Object, error) {
+		if len(args) != 3 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		s2, ok := tengo.ToString(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "second",
+				Expected: "string(compatible)",
+				Found:    args[1].TypeName(),
+			}
+		}
+		i3, ok := tengo.ToInt(args[2])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "third",
+				Expected: "int(compatible)",
+				Found:    args[2].TypeName(),
+			}
+		}
+		arr := &tengo.Array{}
+		for _, res := range fn(s1, s2, i3) {
+			if len(res) > tengo.MaxStringLen {
+				return nil, tengo.ErrStringLimit
+			}
+			arr.Value = append(arr.Value, &tengo.String{Value: res})
+		}
+		return arr, nil
+	}
+}
+
+// FuncASSRI transform a function of 'func(string, string) int' signature into
+// CallableFunc type.
+func FuncASSRI(fn func(string, string) int) tengo.CallableFunc {
+	return func(args ...tengo.Object) (tengo.Object, error) {
+		if len(args) != 2 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		s2, ok := tengo.ToString(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "second",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		return &tengo.Int{Value: int64(fn(s1, s2))}, nil
+	}
+}
+
+// FuncASSRS transform a function of 'func(string, string) string' signature
+// into CallableFunc type.
+func FuncASSRS(fn func(string, string) string) tengo.CallableFunc {
+	return func(args ...tengo.Object) (tengo.Object, error) {
+		if len(args) != 2 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		s2, ok := tengo.ToString(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "second",
+				Expected: "string(compatible)",
+				Found:    args[1].TypeName(),
+			}
+		}
+		s := fn(s1, s2)
+		if len(s) > tengo.MaxStringLen {
+			return nil, tengo.ErrStringLimit
+		}
+		return &tengo.String{Value: s}, nil
+	}
+}
+
+// FuncASSRB transform a function of 'func(string, string) bool' signature
+// into CallableFunc type.
+func FuncASSRB(fn func(string, string) bool) tengo.CallableFunc {
+	return func(args ...tengo.Object) (tengo.Object, error) {
+		if len(args) != 2 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		s2, ok := tengo.ToString(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "second",
+				Expected: "string(compatible)",
+				Found:    args[1].TypeName(),
+			}
+		}
+		if fn(s1, s2) {
+			return tengo.TrueValue, nil
+		}
+		return tengo.FalseValue, nil
+	}
+}
+
+// FuncASsSRS transform a function of 'func([]string, string) string' signature
+// into CallableFunc type.
+func FuncASsSRS(fn func([]string, string) string) tengo.CallableFunc {
+	return func(args ...tengo.Object) (tengo.Object, error) {
+		if len(args) != 2 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		var ss1 []string
+		switch arg0 := args[0].(type) {
+		case *tengo.Array:
+			for idx, a := range arg0.Value {
+				as, ok := tengo.ToString(a)
+				if !ok {
+					return nil, tengo.ErrInvalidArgumentType{
+						Name:     fmt.Sprintf("first[%d]", idx),
+						Expected: "string(compatible)",
+						Found:    a.TypeName(),
+					}
+				}
+				ss1 = append(ss1, as)
+			}
+		case *tengo.ImmutableArray:
+			for idx, a := range arg0.Value {
+				as, ok := tengo.ToString(a)
+				if !ok {
+					return nil, tengo.ErrInvalidArgumentType{
+						Name:     fmt.Sprintf("first[%d]", idx),
+						Expected: "string(compatible)",
+						Found:    a.TypeName(),
+					}
+				}
+				ss1 = append(ss1, as)
+			}
+		default:
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "array",
+				Found:    args[0].TypeName(),
+			}
+		}
+		s2, ok := tengo.ToString(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "second",
+				Expected: "string(compatible)",
+				Found:    args[1].TypeName(),
+			}
+		}
+		s := fn(ss1, s2)
+		if len(s) > tengo.MaxStringLen {
+			return nil, tengo.ErrStringLimit
+		}
+		return &tengo.String{Value: s}, nil
+	}
+}
+
+// FuncASI64RE transform a function of 'func(string, int64) error' signature
+// into CallableFunc type.
+func FuncASI64RE(fn func(string, int64) error) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 2 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		i2, ok := tengo.ToInt64(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "second",
+				Expected: "int(compatible)",
+				Found:    args[1].TypeName(),
+			}
+		}
+		return wrapError(fn(s1, i2)), nil
+	}
+}
+
+// FuncAIIRE transform a function of 'func(int, int) error' signature
+// into CallableFunc type.
+func FuncAIIRE(fn func(int, int) error) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 2 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		i1, ok := tengo.ToInt(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "int(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		i2, ok := tengo.ToInt(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "second",
+				Expected: "int(compatible)",
+				Found:    args[1].TypeName(),
+			}
+		}
+		return wrapError(fn(i1, i2)), nil
+	}
+}
+
+// FuncASIRS transform a function of 'func(string, int) string' signature
+// into CallableFunc type.
+func FuncASIRS(fn func(string, int) string) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 2 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		i2, ok := tengo.ToInt(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "second",
+				Expected: "int(compatible)",
+				Found:    args[1].TypeName(),
+			}
+		}
+		s := fn(s1, i2)
+		if len(s) > tengo.MaxStringLen {
+			return nil, tengo.ErrStringLimit
+		}
+		return &tengo.String{Value: s}, nil
+	}
+}
+
+// FuncASIIRE transform a function of 'func(string, int, int) error' signature
+// into CallableFunc type.
+func FuncASIIRE(fn func(string, int, int) error) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 3 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		i2, ok := tengo.ToInt(args[1])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "second",
+				Expected: "int(compatible)",
+				Found:    args[1].TypeName(),
+			}
+		}
+		i3, ok := tengo.ToInt(args[2])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "third",
+				Expected: "int(compatible)",
+				Found:    args[2].TypeName(),
+			}
+		}
+		return wrapError(fn(s1, i2, i3)), nil
+	}
+}
+
+// FuncAYRIE transform a function of 'func([]byte) (int, error)' signature
+// into CallableFunc type.
+func FuncAYRIE(fn func([]byte) (int, error)) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		y1, ok := tengo.ToByteSlice(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "bytes(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		res, err := fn(y1)
+		if err != nil {
+			return wrapError(err), nil
+		}
+		return &tengo.Int{Value: int64(res)}, nil
+	}
+}
+
+// FuncAYRS transform a function of 'func([]byte) string' signature into
+// CallableFunc type.
+func FuncAYRS(fn func([]byte) string) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		y1, ok := tengo.ToByteSlice(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "bytes(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		res := fn(y1)
+		return &tengo.String{Value: res}, nil
+	}
+}
+
+// FuncASRIE transform a function of 'func(string) (int, error)' signature
+// into CallableFunc type.
+func FuncASRIE(fn func(string) (int, error)) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		res, err := fn(s1)
+		if err != nil {
+			return wrapError(err), nil
+		}
+		return &tengo.Int{Value: int64(res)}, nil
+	}
+}
+
+// FuncASRYE transform a function of 'func(string) ([]byte, error)' signature
+// into CallableFunc type.
+func FuncASRYE(fn func(string) ([]byte, error)) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		s1, ok := tengo.ToString(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "string(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		res, err := fn(s1)
+		if err != nil {
+			return wrapError(err), nil
+		}
+		if len(res) > tengo.MaxBytesLen {
+			return nil, tengo.ErrBytesLimit
+		}
+		return &tengo.Bytes{Value: res}, nil
+	}
+}
+
+// FuncAIRSsE transform a function of 'func(int) ([]string, error)' signature
+// into CallableFunc type.
+func FuncAIRSsE(fn func(int) ([]string, error)) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		i1, ok := tengo.ToInt(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "int(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		res, err := fn(i1)
+		if err != nil {
+			return wrapError(err), nil
+		}
+		arr := &tengo.Array{}
+		for _, r := range res {
+			if len(r) > tengo.MaxStringLen {
+				return nil, tengo.ErrStringLimit
+			}
+			arr.Value = append(arr.Value, &tengo.String{Value: r})
+		}
+		return arr, nil
+	}
+}
+
+// FuncAIRS transform a function of 'func(int) string' signature into
+// CallableFunc type.
+func FuncAIRS(fn func(int) string) tengo.CallableFunc {
+	return func(args ...tengo.Object) (ret tengo.Object, err error) {
+		if len(args) != 1 {
+			return nil, tengo.ErrWrongNumArguments
+		}
+		i1, ok := tengo.ToInt(args[0])
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     "first",
+				Expected: "int(compatible)",
+				Found:    args[0].TypeName(),
+			}
+		}
+		s := fn(i1)
+		if len(s) > tengo.MaxStringLen {
+			return nil, tengo.ErrStringLimit
+		}
+		return &tengo.String{Value: s}, nil
+	}
+}
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/hex.go b/vendor/github.com/d5/tengo/v2/stdlib/hex.go
new file mode 100644
index 00000000..981da696
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/hex.go
@@ -0,0 +1,12 @@
+package stdlib
+
+import (
+	"encoding/hex"
+
+	"github.com/d5/tengo/v2"
+)
+
+var hexModule = map[string]tengo.Object{
+	"encode": &tengo.UserFunction{Value: FuncAYRS(hex.EncodeToString)},
+	"decode": &tengo.UserFunction{Value: FuncASRYE(hex.DecodeString)},
+}
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/json.go b/vendor/github.com/d5/tengo/v2/stdlib/json.go
new file mode 100644
index 00000000..be2185db
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/json.go
@@ -0,0 +1,146 @@
+package stdlib
+
+import (
+	"bytes"
+	gojson "encoding/json"
+
+	"github.com/d5/tengo/v2"
+	"github.com/d5/tengo/v2/stdlib/json"
+)
+
+var jsonModule = map[string]tengo.Object{
+	"decode": &tengo.UserFunction{
+		Name:  "decode",
+		Value: jsonDecode,
+	},
+	"encode": &tengo.UserFunction{
+		Name:  "encode",
+		Value: jsonEncode,
+	},
+	"indent": &tengo.UserFunction{
+		Name:  "encode",
+		Value: jsonIndent,
+	},
+	"html_escape": &tengo.UserFunction{
+		Name:  "html_escape",
+		Value: jsonHTMLEscape,
+	},
+}
+
+func jsonDecode(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+
+	switch o := args[0].(type) {
+	case *tengo.Bytes:
+		v, err := json.Decode(o.Value)
+		if err != nil {
+			return &tengo.Error{
+				Value: &tengo.String{Value: err.Error()},
+			}, nil
+		}
+		return v, nil
+	case *tengo.String:
+		v, err := json.Decode([]byte(o.Value))
+		if err != nil {
+			return &tengo.Error{
+				Value: &tengo.String{Value: err.Error()},
+			}, nil
+		}
+		return v, nil
+	default:
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "bytes/string",
+			Found:    args[0].TypeName(),
+		}
+	}
+}
+
+func jsonEncode(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+
+	b, err := json.Encode(args[0])
+	if err != nil {
+		return &tengo.Error{Value: &tengo.String{Value: err.Error()}}, nil
+	}
+
+	return &tengo.Bytes{Value: b}, nil
+}
+
+func jsonIndent(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 3 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+
+	prefix, ok := tengo.ToString(args[1])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "prefix",
+			Expected: "string(compatible)",
+			Found:    args[1].TypeName(),
+		}
+	}
+
+	indent, ok := tengo.ToString(args[2])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "indent",
+			Expected: "string(compatible)",
+			Found:    args[2].TypeName(),
+		}
+	}
+
+	switch o := args[0].(type) {
+	case *tengo.Bytes:
+		var dst bytes.Buffer
+		err := gojson.Indent(&dst, o.Value, prefix, indent)
+		if err != nil {
+			return &tengo.Error{
+				Value: &tengo.String{Value: err.Error()},
+			}, nil
+		}
+		return &tengo.Bytes{Value: dst.Bytes()}, nil
+	case *tengo.String:
+		var dst bytes.Buffer
+		err := gojson.Indent(&dst, []byte(o.Value), prefix, indent)
+		if err != nil {
+			return &tengo.Error{
+				Value: &tengo.String{Value: err.Error()},
+			}, nil
+		}
+		return &tengo.Bytes{Value: dst.Bytes()}, nil
+	default:
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "bytes/string",
+			Found:    args[0].TypeName(),
+		}
+	}
+}
+
+func jsonHTMLEscape(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+
+	switch o := args[0].(type) {
+	case *tengo.Bytes:
+		var dst bytes.Buffer
+		gojson.HTMLEscape(&dst, o.Value)
+		return &tengo.Bytes{Value: dst.Bytes()}, nil
+	case *tengo.String:
+		var dst bytes.Buffer
+		gojson.HTMLEscape(&dst, []byte(o.Value))
+		return &tengo.Bytes{Value: dst.Bytes()}, nil
+	default:
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "bytes/string",
+			Found:    args[0].TypeName(),
+		}
+	}
+}
diff --git a/vendor/github.com/d5/tengo/stdlib/json/decode.go b/vendor/github.com/d5/tengo/v2/stdlib/json/decode.go
index 5a3fe6c7..6d468ef0 100644
--- a/vendor/github.com/d5/tengo/stdlib/json/decode.go
+++ b/vendor/github.com/d5/tengo/v2/stdlib/json/decode.go
@@ -12,21 +12,19 @@ import (
 	"unicode/utf16"
 	"unicode/utf8"
 
-	"github.com/d5/tengo/objects"
+	"github.com/d5/tengo/v2"
 )
 
 // Decode parses the JSON-encoded data and returns the result object.
-func Decode(data []byte) (objects.Object, error) {
+func Decode(data []byte) (tengo.Object, error) {
 	var d decodeState
 	err := checkValid(data, &d.scan)
 	if err != nil {
 		return nil, err
 	}
-
 	d.init(data)
 	d.scan.reset()
 	d.scanWhile(scanSkipSpace)
-
 	return d.value()
 }
 
@@ -80,45 +78,37 @@ func (d *decodeState) scanWhile(op int) {
 	d.opcode = d.scan.eof()
 }
 
-func (d *decodeState) value() (objects.Object, error) {
+func (d *decodeState) value() (tengo.Object, error) {
 	switch d.opcode {
 	default:
 		panic(phasePanicMsg)
-
 	case scanBeginArray:
 		o, err := d.array()
 		if err != nil {
 			return nil, err
 		}
-
 		d.scanNext()
-
 		return o, nil
-
 	case scanBeginObject:
 		o, err := d.object()
 		if err != nil {
 			return nil, err
 		}
-
 		d.scanNext()
-
 		return o, nil
-
 	case scanBeginLiteral:
 		return d.literal()
 	}
 }
 
-func (d *decodeState) array() (objects.Object, error) {
-	var arr []objects.Object
+func (d *decodeState) array() (tengo.Object, error) {
+	var arr []tengo.Object
 	for {
 		// Look ahead for ] - can only happen on first iteration.
 		d.scanWhile(scanSkipSpace)
 		if d.opcode == scanEndArray {
 			break
 		}
-
 		o, err := d.value()
 		if err != nil {
 			return nil, err
@@ -136,12 +126,11 @@ func (d *decodeState) array() (objects.Object, error) {
 			panic(phasePanicMsg)
 		}
 	}
-
-	return &objects.Array{Value: arr}, nil
+	return &tengo.Array{Value: arr}, nil
 }
 
-func (d *decodeState) object() (objects.Object, error) {
-	m := make(map[string]objects.Object)
+func (d *decodeState) object() (tengo.Object, error) {
+	m := make(map[string]tengo.Object)
 	for {
 		// Read opening " of string key or closing }.
 		d.scanWhile(scanSkipSpace)
@@ -190,11 +179,10 @@ func (d *decodeState) object() (objects.Object, error) {
 			panic(phasePanicMsg)
 		}
 	}
-
-	return &objects.Map{Value: m}, nil
+	return &tengo.Map{Value: m}, nil
 }
 
-func (d *decodeState) literal() (objects.Object, error) {
+func (d *decodeState) literal() (tengo.Object, error) {
 	// All bytes inside literal return scanContinue op code.
 	start := d.readIndex()
 	d.scanWhile(scanContinue)
@@ -203,28 +191,27 @@ func (d *decodeState) literal() (objects.Object, error) {
 
 	switch c := item[0]; c {
 	case 'n': // null
-		return objects.UndefinedValue, nil
+		return tengo.UndefinedValue, nil
 
 	case 't', 'f': // true, false
 		if c == 't' {
-			return objects.TrueValue, nil
+			return tengo.TrueValue, nil
 		}
-		return objects.FalseValue, nil
+		return tengo.FalseValue, nil
 
 	case '"': // string
 		s, ok := unquote(item)
 		if !ok {
 			panic(phasePanicMsg)
 		}
-		return &objects.String{Value: s}, nil
+		return &tengo.String{Value: s}, nil
 
 	default: // number
 		if c != '-' && (c < '0' || c > '9') {
 			panic(phasePanicMsg)
 		}
-
 		n, _ := strconv.ParseFloat(string(item), 10)
-		return &objects.Float{Value: n}, nil
+		return &tengo.Float{Value: n}, nil
 	}
 }
 
@@ -265,9 +252,8 @@ func unquoteBytes(s []byte) (t []byte, ok bool) {
 	}
 	s = s[1 : len(s)-1]
 
-	// Check for unusual characters. If there are none,
-	// then no unquoting is needed, so return a slice of the
-	// original bytes.
+	// Check for unusual characters. If there are none, then no unquoting is
+	// needed, so return a slice of the original bytes.
 	r := 0
 	for r < len(s) {
 		c := s[r]
@@ -341,7 +327,8 @@ func unquoteBytes(s []byte) (t []byte, ok bool) {
 				r += 6
 				if utf16.IsSurrogate(rr) {
 					rr1 := getu4(s[r:])
-					if dec := utf16.DecodeRune(rr, rr1); dec != unicode.ReplacementChar {
+					dec := utf16.DecodeRune(rr, rr1)
+					if dec != unicode.ReplacementChar {
 						// A valid pair; consume.
 						r += 6
 						w += utf8.EncodeRune(b[w:], dec)
@@ -352,17 +339,14 @@ func unquoteBytes(s []byte) (t []byte, ok bool) {
 				}
 				w += utf8.EncodeRune(b[w:], rr)
 			}
-
 		// Quote, control characters are invalid.
 		case c == '"', c < ' ':
 			return
-
 		// ASCII
 		case c < utf8.RuneSelf:
 			b[w] = c
 			r++
 			w++
-
 		// Coerce to well-formed UTF-8.
 		default:
 			rr, size := utf8.DecodeRune(s[r:])
diff --git a/vendor/github.com/d5/tengo/stdlib/json/encode.go b/vendor/github.com/d5/tengo/v2/stdlib/json/encode.go
index 2b8b17eb..ab7ca6ff 100644
--- a/vendor/github.com/d5/tengo/stdlib/json/encode.go
+++ b/vendor/github.com/d5/tengo/v2/stdlib/json/encode.go
@@ -12,15 +12,15 @@ import (
 	"math"
 	"strconv"
 
-	"github.com/d5/tengo/objects"
+	"github.com/d5/tengo/v2"
 )
 
 // Encode returns the JSON encoding of the object.
-func Encode(o objects.Object) ([]byte, error) {
+func Encode(o tengo.Object) ([]byte, error) {
 	var b []byte
 
 	switch o := o.(type) {
-	case *objects.Array:
+	case *tengo.Array:
 		b = append(b, '[')
 		len1 := len(o.Value) - 1
 		for idx, elem := range o.Value {
@@ -34,7 +34,7 @@ func Encode(o objects.Object) ([]byte, error) {
 			}
 		}
 		b = append(b, ']')
-	case *objects.ImmutableArray:
+	case *tengo.ImmutableArray:
 		b = append(b, '[')
 		len1 := len(o.Value) - 1
 		for idx, elem := range o.Value {
@@ -48,7 +48,7 @@ func Encode(o objects.Object) ([]byte, error) {
 			}
 		}
 		b = append(b, ']')
-	case *objects.Map:
+	case *tengo.Map:
 		b = append(b, '{')
 		len1 := len(o.Value) - 1
 		idx := 0
@@ -66,7 +66,7 @@ func Encode(o objects.Object) ([]byte, error) {
 			idx++
 		}
 		b = append(b, '}')
-	case *objects.ImmutableMap:
+	case *tengo.ImmutableMap:
 		b = append(b, '{')
 		len1 := len(o.Value) - 1
 		idx := 0
@@ -84,22 +84,22 @@ func Encode(o objects.Object) ([]byte, error) {
 			idx++
 		}
 		b = append(b, '}')
-	case *objects.Bool:
+	case *tengo.Bool:
 		if o.IsFalsy() {
 			b = strconv.AppendBool(b, false)
 		} else {
 			b = strconv.AppendBool(b, true)
 		}
-	case *objects.Bytes:
+	case *tengo.Bytes:
 		b = append(b, '"')
 		encodedLen := base64.StdEncoding.EncodedLen(len(o.Value))
 		dst := make([]byte, encodedLen)
 		base64.StdEncoding.Encode(dst, o.Value)
 		b = append(b, dst...)
 		b = append(b, '"')
-	case *objects.Char:
+	case *tengo.Char:
 		b = strconv.AppendInt(b, int64(o.Value), 10)
-	case *objects.Float:
+	case *tengo.Float:
 		var y []byte
 
 		f := o.Value
@@ -127,21 +127,20 @@ func Encode(o objects.Object) ([]byte, error) {
 		}
 
 		b = append(b, y...)
-	case *objects.Int:
+	case *tengo.Int:
 		b = strconv.AppendInt(b, o.Value, 10)
-	case *objects.String:
+	case *tengo.String:
 		b = strconv.AppendQuote(b, o.Value)
-	case *objects.Time:
+	case *tengo.Time:
 		y, err := o.Value.MarshalJSON()
 		if err != nil {
 			return nil, err
 		}
 		b = append(b, y...)
-	case *objects.Undefined:
+	case *tengo.Undefined:
 		b = append(b, "null"...)
 	default:
 		// unknown type: ignore
 	}
-
 	return b, nil
 }
diff --git a/vendor/github.com/d5/tengo/stdlib/json/scanner.go b/vendor/github.com/d5/tengo/v2/stdlib/json/scanner.go
index 8fc6776d..aed15cf5 100644
--- a/vendor/github.com/d5/tengo/stdlib/json/scanner.go
+++ b/vendor/github.com/d5/tengo/v2/stdlib/json/scanner.go
@@ -532,14 +532,17 @@ func stateNul(s *scanner, c byte) int {
 
 // stateError is the state after reaching a syntax error,
 // such as after reading `[1}` or `5.1.2`.
-func stateError(s *scanner, c byte) int {
+func stateError(_ *scanner, _ byte) int {
 	return scanError
 }
 
 // error records an error and switches to the error state.
 func (s *scanner) error(c byte, context string) int {
 	s.step = stateError
-	s.err = &SyntaxError{"invalid character " + quoteChar(c) + " " + context, s.bytes}
+	s.err = &SyntaxError{
+		msg:    "invalid character " + quoteChar(c) + " " + context,
+		Offset: s.bytes,
+	}
 	return scanError
 }
 
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/math.go b/vendor/github.com/d5/tengo/v2/stdlib/math.go
new file mode 100644
index 00000000..633ea09f
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/math.go
@@ -0,0 +1,233 @@
+package stdlib
+
+import (
+	"math"
+
+	"github.com/d5/tengo/v2"
+)
+
+var mathModule = map[string]tengo.Object{
+	"e":       &tengo.Float{Value: math.E},
+	"pi":      &tengo.Float{Value: math.Pi},
+	"phi":     &tengo.Float{Value: math.Phi},
+	"sqrt2":   &tengo.Float{Value: math.Sqrt2},
+	"sqrtE":   &tengo.Float{Value: math.SqrtE},
+	"sqrtPi":  &tengo.Float{Value: math.SqrtPi},
+	"sqrtPhi": &tengo.Float{Value: math.SqrtPhi},
+	"ln2":     &tengo.Float{Value: math.Ln2},
+	"log2E":   &tengo.Float{Value: math.Log2E},
+	"ln10":    &tengo.Float{Value: math.Ln10},
+	"log10E":  &tengo.Float{Value: math.Log10E},
+	"abs": &tengo.UserFunction{
+		Name:  "abs",
+		Value: FuncAFRF(math.Abs),
+	},
+	"acos": &tengo.UserFunction{
+		Name:  "acos",
+		Value: FuncAFRF(math.Acos),
+	},
+	"acosh": &tengo.UserFunction{
+		Name:  "acosh",
+		Value: FuncAFRF(math.Acosh),
+	},
+	"asin": &tengo.UserFunction{
+		Name:  "asin",
+		Value: FuncAFRF(math.Asin),
+	},
+	"asinh": &tengo.UserFunction{
+		Name:  "asinh",
+		Value: FuncAFRF(math.Asinh),
+	},
+	"atan": &tengo.UserFunction{
+		Name:  "atan",
+		Value: FuncAFRF(math.Atan),
+	},
+	"atan2": &tengo.UserFunction{
+		Name:  "atan2",
+		Value: FuncAFFRF(math.Atan2),
+	},
+	"atanh": &tengo.UserFunction{
+		Name:  "atanh",
+		Value: FuncAFRF(math.Atanh),
+	},
+	"cbrt": &tengo.UserFunction{
+		Name:  "cbrt",
+		Value: FuncAFRF(math.Cbrt),
+	},
+	"ceil": &tengo.UserFunction{
+		Name:  "ceil",
+		Value: FuncAFRF(math.Ceil),
+	},
+	"copysign": &tengo.UserFunction{
+		Name:  "copysign",
+		Value: FuncAFFRF(math.Copysign),
+	},
+	"cos": &tengo.UserFunction{
+		Name:  "cos",
+		Value: FuncAFRF(math.Cos),
+	},
+	"cosh": &tengo.UserFunction{
+		Name:  "cosh",
+		Value: FuncAFRF(math.Cosh),
+	},
+	"dim": &tengo.UserFunction{
+		Name:  "dim",
+		Value: FuncAFFRF(math.Dim),
+	},
+	"erf": &tengo.UserFunction{
+		Name:  "erf",
+		Value: FuncAFRF(math.Erf),
+	},
+	"erfc": &tengo.UserFunction{
+		Name:  "erfc",
+		Value: FuncAFRF(math.Erfc),
+	},
+	"exp": &tengo.UserFunction{
+		Name:  "exp",
+		Value: FuncAFRF(math.Exp),
+	},
+	"exp2": &tengo.UserFunction{
+		Name:  "exp2",
+		Value: FuncAFRF(math.Exp2),
+	},
+	"expm1": &tengo.UserFunction{
+		Name:  "expm1",
+		Value: FuncAFRF(math.Expm1),
+	},
+	"floor": &tengo.UserFunction{
+		Name:  "floor",
+		Value: FuncAFRF(math.Floor),
+	},
+	"gamma": &tengo.UserFunction{
+		Name:  "gamma",
+		Value: FuncAFRF(math.Gamma),
+	},
+	"hypot": &tengo.UserFunction{
+		Name:  "hypot",
+		Value: FuncAFFRF(math.Hypot),
+	},
+	"ilogb": &tengo.UserFunction{
+		Name:  "ilogb",
+		Value: FuncAFRI(math.Ilogb),
+	},
+	"inf": &tengo.UserFunction{
+		Name:  "inf",
+		Value: FuncAIRF(math.Inf),
+	},
+	"is_inf": &tengo.UserFunction{
+		Name:  "is_inf",
+		Value: FuncAFIRB(math.IsInf),
+	},
+	"is_nan": &tengo.UserFunction{
+		Name:  "is_nan",
+		Value: FuncAFRB(math.IsNaN),
+	},
+	"j0": &tengo.UserFunction{
+		Name:  "j0",
+		Value: FuncAFRF(math.J0),
+	},
+	"j1": &tengo.UserFunction{
+		Name:  "j1",
+		Value: FuncAFRF(math.J1),
+	},
+	"jn": &tengo.UserFunction{
+		Name:  "jn",
+		Value: FuncAIFRF(math.Jn),
+	},
+	"ldexp": &tengo.UserFunction{
+		Name:  "ldexp",
+		Value: FuncAFIRF(math.Ldexp),
+	},
+	"log": &tengo.UserFunction{
+		Name:  "log",
+		Value: FuncAFRF(math.Log),
+	},
+	"log10": &tengo.UserFunction{
+		Name:  "log10",
+		Value: FuncAFRF(math.Log10),
+	},
+	"log1p": &tengo.UserFunction{
+		Name:  "log1p",
+		Value: FuncAFRF(math.Log1p),
+	},
+	"log2": &tengo.UserFunction{
+		Name:  "log2",
+		Value: FuncAFRF(math.Log2),
+	},
+	"logb": &tengo.UserFunction{
+		Name:  "logb",
+		Value: FuncAFRF(math.Logb),
+	},
+	"max": &tengo.UserFunction{
+		Name:  "max",
+		Value: FuncAFFRF(math.Max),
+	},
+	"min": &tengo.UserFunction{
+		Name:  "min",
+		Value: FuncAFFRF(math.Min),
+	},
+	"mod": &tengo.UserFunction{
+		Name:  "mod",
+		Value: FuncAFFRF(math.Mod),
+	},
+	"nan": &tengo.UserFunction{
+		Name:  "nan",
+		Value: FuncARF(math.NaN),
+	},
+	"nextafter": &tengo.UserFunction{
+		Name:  "nextafter",
+		Value: FuncAFFRF(math.Nextafter),
+	},
+	"pow": &tengo.UserFunction{
+		Name:  "pow",
+		Value: FuncAFFRF(math.Pow),
+	},
+	"pow10": &tengo.UserFunction{
+		Name:  "pow10",
+		Value: FuncAIRF(math.Pow10),
+	},
+	"remainder": &tengo.UserFunction{
+		Name:  "remainder",
+		Value: FuncAFFRF(math.Remainder),
+	},
+	"signbit": &tengo.UserFunction{
+		Name:  "signbit",
+		Value: FuncAFRB(math.Signbit),
+	},
+	"sin": &tengo.UserFunction{
+		Name:  "sin",
+		Value: FuncAFRF(math.Sin),
+	},
+	"sinh": &tengo.UserFunction{
+		Name:  "sinh",
+		Value: FuncAFRF(math.Sinh),
+	},
+	"sqrt": &tengo.UserFunction{
+		Name:  "sqrt",
+		Value: FuncAFRF(math.Sqrt),
+	},
+	"tan": &tengo.UserFunction{
+		Name:  "tan",
+		Value: FuncAFRF(math.Tan),
+	},
+	"tanh": &tengo.UserFunction{
+		Name:  "tanh",
+		Value: FuncAFRF(math.Tanh),
+	},
+	"trunc": &tengo.UserFunction{
+		Name:  "trunc",
+		Value: FuncAFRF(math.Trunc),
+	},
+	"y0": &tengo.UserFunction{
+		Name:  "y0",
+		Value: FuncAFRF(math.Y0),
+	},
+	"y1": &tengo.UserFunction{
+		Name:  "y1",
+		Value: FuncAFRF(math.Y1),
+	},
+	"yn": &tengo.UserFunction{
+		Name:  "yn",
+		Value: FuncAIFRF(math.Yn),
+	},
+}
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/os.go b/vendor/github.com/d5/tengo/v2/stdlib/os.go
new file mode 100644
index 00000000..576bc94b
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/os.go
@@ -0,0 +1,564 @@
+package stdlib
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"os/exec"
+
+	"github.com/d5/tengo/v2"
+)
+
+var osModule = map[string]tengo.Object{
+	"o_rdonly":            &tengo.Int{Value: int64(os.O_RDONLY)},
+	"o_wronly":            &tengo.Int{Value: int64(os.O_WRONLY)},
+	"o_rdwr":              &tengo.Int{Value: int64(os.O_RDWR)},
+	"o_append":            &tengo.Int{Value: int64(os.O_APPEND)},
+	"o_create":            &tengo.Int{Value: int64(os.O_CREATE)},
+	"o_excl":              &tengo.Int{Value: int64(os.O_EXCL)},
+	"o_sync":              &tengo.Int{Value: int64(os.O_SYNC)},
+	"o_trunc":             &tengo.Int{Value: int64(os.O_TRUNC)},
+	"mode_dir":            &tengo.Int{Value: int64(os.ModeDir)},
+	"mode_append":         &tengo.Int{Value: int64(os.ModeAppend)},
+	"mode_exclusive":      &tengo.Int{Value: int64(os.ModeExclusive)},
+	"mode_temporary":      &tengo.Int{Value: int64(os.ModeTemporary)},
+	"mode_symlink":        &tengo.Int{Value: int64(os.ModeSymlink)},
+	"mode_device":         &tengo.Int{Value: int64(os.ModeDevice)},
+	"mode_named_pipe":     &tengo.Int{Value: int64(os.ModeNamedPipe)},
+	"mode_socket":         &tengo.Int{Value: int64(os.ModeSocket)},
+	"mode_setuid":         &tengo.Int{Value: int64(os.ModeSetuid)},
+	"mode_setgui":         &tengo.Int{Value: int64(os.ModeSetgid)},
+	"mode_char_device":    &tengo.Int{Value: int64(os.ModeCharDevice)},
+	"mode_sticky":         &tengo.Int{Value: int64(os.ModeSticky)},
+	"mode_type":           &tengo.Int{Value: int64(os.ModeType)},
+	"mode_perm":           &tengo.Int{Value: int64(os.ModePerm)},
+	"path_separator":      &tengo.Char{Value: os.PathSeparator},
+	"path_list_separator": &tengo.Char{Value: os.PathListSeparator},
+	"dev_null":            &tengo.String{Value: os.DevNull},
+	"seek_set":            &tengo.Int{Value: int64(io.SeekStart)},
+	"seek_cur":            &tengo.Int{Value: int64(io.SeekCurrent)},
+	"seek_end":            &tengo.Int{Value: int64(io.SeekEnd)},
+	"args": &tengo.UserFunction{
+		Name:  "args",
+		Value: osArgs,
+	}, // args() => array(string)
+	"chdir": &tengo.UserFunction{
+		Name:  "chdir",
+		Value: FuncASRE(os.Chdir),
+	}, // chdir(dir string) => error
+	"chmod": osFuncASFmRE("chmod", os.Chmod), // chmod(name string, mode int) => error
+	"chown": &tengo.UserFunction{
+		Name:  "chown",
+		Value: FuncASIIRE(os.Chown),
+	}, // chown(name string, uid int, gid int) => error
+	"clearenv": &tengo.UserFunction{
+		Name:  "clearenv",
+		Value: FuncAR(os.Clearenv),
+	}, // clearenv()
+	"environ": &tengo.UserFunction{
+		Name:  "environ",
+		Value: FuncARSs(os.Environ),
+	}, // environ() => array(string)
+	"exit": &tengo.UserFunction{
+		Name:  "exit",
+		Value: FuncAIR(os.Exit),
+	}, // exit(code int)
+	"expand_env": &tengo.UserFunction{
+		Name:  "expand_env",
+		Value: osExpandEnv,
+	}, // expand_env(s string) => string
+	"getegid": &tengo.UserFunction{
+		Name:  "getegid",
+		Value: FuncARI(os.Getegid),
+	}, // getegid() => int
+	"getenv": &tengo.UserFunction{
+		Name:  "getenv",
+		Value: FuncASRS(os.Getenv),
+	}, // getenv(s string) => string
+	"geteuid": &tengo.UserFunction{
+		Name:  "geteuid",
+		Value: FuncARI(os.Geteuid),
+	}, // geteuid() => int
+	"getgid": &tengo.UserFunction{
+		Name:  "getgid",
+		Value: FuncARI(os.Getgid),
+	}, // getgid() => int
+	"getgroups": &tengo.UserFunction{
+		Name:  "getgroups",
+		Value: FuncARIsE(os.Getgroups),
+	}, // getgroups() => array(string)/error
+	"getpagesize": &tengo.UserFunction{
+		Name:  "getpagesize",
+		Value: FuncARI(os.Getpagesize),
+	}, // getpagesize() => int
+	"getpid": &tengo.UserFunction{
+		Name:  "getpid",
+		Value: FuncARI(os.Getpid),
+	}, // getpid() => int
+	"getppid": &tengo.UserFunction{
+		Name:  "getppid",
+		Value: FuncARI(os.Getppid),
+	}, // getppid() => int
+	"getuid": &tengo.UserFunction{
+		Name:  "getuid",
+		Value: FuncARI(os.Getuid),
+	}, // getuid() => int
+	"getwd": &tengo.UserFunction{
+		Name:  "getwd",
+		Value: FuncARSE(os.Getwd),
+	}, // getwd() => string/error
+	"hostname": &tengo.UserFunction{
+		Name:  "hostname",
+		Value: FuncARSE(os.Hostname),
+	}, // hostname() => string/error
+	"lchown": &tengo.UserFunction{
+		Name:  "lchown",
+		Value: FuncASIIRE(os.Lchown),
+	}, // lchown(name string, uid int, gid int) => error
+	"link": &tengo.UserFunction{
+		Name:  "link",
+		Value: FuncASSRE(os.Link),
+	}, // link(oldname string, newname string) => error
+	"lookup_env": &tengo.UserFunction{
+		Name:  "lookup_env",
+		Value: osLookupEnv,
+	}, // lookup_env(key string) => string/false
+	"mkdir":     osFuncASFmRE("mkdir", os.Mkdir),        // mkdir(name string, perm int) => error
+	"mkdir_all": osFuncASFmRE("mkdir_all", os.MkdirAll), // mkdir_all(name string, perm int) => error
+	"readlink": &tengo.UserFunction{
+		Name:  "readlink",
+		Value: FuncASRSE(os.Readlink),
+	}, // readlink(name string) => string/error
+	"remove": &tengo.UserFunction{
+		Name:  "remove",
+		Value: FuncASRE(os.Remove),
+	}, // remove(name string) => error
+	"remove_all": &tengo.UserFunction{
+		Name:  "remove_all",
+		Value: FuncASRE(os.RemoveAll),
+	}, // remove_all(name string) => error
+	"rename": &tengo.UserFunction{
+		Name:  "rename",
+		Value: FuncASSRE(os.Rename),
+	}, // rename(oldpath string, newpath string) => error
+	"setenv": &tengo.UserFunction{
+		Name:  "setenv",
+		Value: FuncASSRE(os.Setenv),
+	}, // setenv(key string, value string) => error
+	"symlink": &tengo.UserFunction{
+		Name:  "symlink",
+		Value: FuncASSRE(os.Symlink),
+	}, // symlink(oldname string newname string) => error
+	"temp_dir": &tengo.UserFunction{
+		Name:  "temp_dir",
+		Value: FuncARS(os.TempDir),
+	}, // temp_dir() => string
+	"truncate": &tengo.UserFunction{
+		Name:  "truncate",
+		Value: FuncASI64RE(os.Truncate),
+	}, // truncate(name string, size int) => error
+	"unsetenv": &tengo.UserFunction{
+		Name:  "unsetenv",
+		Value: FuncASRE(os.Unsetenv),
+	}, // unsetenv(key string) => error
+	"create": &tengo.UserFunction{
+		Name:  "create",
+		Value: osCreate,
+	}, // create(name string) => imap(file)/error
+	"open": &tengo.UserFunction{
+		Name:  "open",
+		Value: osOpen,
+	}, // open(name string) => imap(file)/error
+	"open_file": &tengo.UserFunction{
+		Name:  "open_file",
+		Value: osOpenFile,
+	}, // open_file(name string, flag int, perm int) => imap(file)/error
+	"find_process": &tengo.UserFunction{
+		Name:  "find_process",
+		Value: osFindProcess,
+	}, // find_process(pid int) => imap(process)/error
+	"start_process": &tengo.UserFunction{
+		Name:  "start_process",
+		Value: osStartProcess,
+	}, // start_process(name string, argv array(string), dir string, env array(string)) => imap(process)/error
+	"exec_look_path": &tengo.UserFunction{
+		Name:  "exec_look_path",
+		Value: FuncASRSE(exec.LookPath),
+	}, // exec_look_path(file) => string/error
+	"exec": &tengo.UserFunction{
+		Name:  "exec",
+		Value: osExec,
+	}, // exec(name, args...) => command
+	"stat": &tengo.UserFunction{
+		Name:  "stat",
+		Value: osStat,
+	}, // stat(name) => imap(fileinfo)/error
+	"read_file": &tengo.UserFunction{
+		Name:  "read_file",
+		Value: osReadFile,
+	}, // readfile(name) => array(byte)/error
+}
+
+func osReadFile(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+	fname, ok := tengo.ToString(args[0])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+	}
+	bytes, err := ioutil.ReadFile(fname)
+	if err != nil {
+		return wrapError(err), nil
+	}
+	if len(bytes) > tengo.MaxBytesLen {
+		return nil, tengo.ErrBytesLimit
+	}
+	return &tengo.Bytes{Value: bytes}, nil
+}
+
+func osStat(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+	fname, ok := tengo.ToString(args[0])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+	}
+	stat, err := os.Stat(fname)
+	if err != nil {
+		return wrapError(err), nil
+	}
+	fstat := &tengo.ImmutableMap{
+		Value: map[string]tengo.Object{
+			"name":  &tengo.String{Value: stat.Name()},
+			"mtime": &tengo.Time{Value: stat.ModTime()},
+			"size":  &tengo.Int{Value: stat.Size()},
+			"mode":  &tengo.Int{Value: int64(stat.Mode())},
+		},
+	}
+	if stat.IsDir() {
+		fstat.Value["directory"] = tengo.TrueValue
+	} else {
+		fstat.Value["directory"] = tengo.FalseValue
+	}
+	return fstat, nil
+}
+
+func osCreate(args ...tengo.Object) (tengo.Object, error) {
+	if len(args) != 1 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+	}
+	res, err := os.Create(s1)
+	if err != nil {
+		return wrapError(err), nil
+	}
+	return makeOSFile(res), nil
+}
+
+func osOpen(args ...tengo.Object) (tengo.Object, error) {
+	if len(args) != 1 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+	}
+	res, err := os.Open(s1)
+	if err != nil {
+		return wrapError(err), nil
+	}
+	return makeOSFile(res), nil
+}
+
+func osOpenFile(args ...tengo.Object) (tengo.Object, error) {
+	if len(args) != 3 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+	}
+	i2, ok := tengo.ToInt(args[1])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "int(compatible)",
+			Found:    args[1].TypeName(),
+		}
+	}
+	i3, ok := tengo.ToInt(args[2])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "third",
+			Expected: "int(compatible)",
+			Found:    args[2].TypeName(),
+		}
+	}
+	res, err := os.OpenFile(s1, i2, os.FileMode(i3))
+	if err != nil {
+		return wrapError(err), nil
+	}
+	return makeOSFile(res), nil
+}
+
+func osArgs(args ...tengo.Object) (tengo.Object, error) {
+	if len(args) != 0 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+	arr := &tengo.Array{}
+	for _, osArg := range os.Args {
+		if len(osArg) > tengo.MaxStringLen {
+			return nil, tengo.ErrStringLimit
+		}
+		arr.Value = append(arr.Value, &tengo.String{Value: osArg})
+	}
+	return arr, nil
+}
+
+func osFuncASFmRE(
+	name string,
+	fn func(string, os.FileMode) error,
+) *tengo.UserFunction {
+	return &tengo.UserFunction{
+		Name: name,
+		Value: func(args ...tengo.Object) (tengo.Object, error) {
+			if len(args) != 2 {
+				return nil, tengo.ErrWrongNumArguments
+			}
+			s1, ok := tengo.ToString(args[0])
+			if !ok {
+				return nil, tengo.ErrInvalidArgumentType{
+					Name:     "first",
+					Expected: "string(compatible)",
+					Found:    args[0].TypeName(),
+				}
+			}
+			i2, ok := tengo.ToInt64(args[1])
+			if !ok {
+				return nil, tengo.ErrInvalidArgumentType{
+					Name:     "second",
+					Expected: "int(compatible)",
+					Found:    args[1].TypeName(),
+				}
+			}
+			return wrapError(fn(s1, os.FileMode(i2))), nil
+		},
+	}
+}
+
+func osLookupEnv(args ...tengo.Object) (tengo.Object, error) {
+	if len(args) != 1 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+	}
+	res, ok := os.LookupEnv(s1)
+	if !ok {
+		return tengo.FalseValue, nil
+	}
+	if len(res) > tengo.MaxStringLen {
+		return nil, tengo.ErrStringLimit
+	}
+	return &tengo.String{Value: res}, nil
+}
+
+func osExpandEnv(args ...tengo.Object) (tengo.Object, error) {
+	if len(args) != 1 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+	}
+	var vlen int
+	var failed bool
+	s := os.Expand(s1, func(k string) string {
+		if failed {
+			return ""
+		}
+		v := os.Getenv(k)
+
+		// this does not count the other texts that are not being replaced
+		// but the code checks the final length at the end
+		vlen += len(v)
+		if vlen > tengo.MaxStringLen {
+			failed = true
+			return ""
+		}
+		return v
+	})
+	if failed || len(s) > tengo.MaxStringLen {
+		return nil, tengo.ErrStringLimit
+	}
+	return &tengo.String{Value: s}, nil
+}
+
+func osExec(args ...tengo.Object) (tengo.Object, error) {
+	if len(args) == 0 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+	name, ok := tengo.ToString(args[0])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+	}
+	var execArgs []string
+	for idx, arg := range args[1:] {
+		execArg, ok := tengo.ToString(arg)
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     fmt.Sprintf("args[%d]", idx),
+				Expected: "string(compatible)",
+				Found:    args[1+idx].TypeName(),
+			}
+		}
+		execArgs = append(execArgs, execArg)
+	}
+	return makeOSExecCommand(exec.Command(name, execArgs...)), nil
+}
+
+func osFindProcess(args ...tengo.Object) (tengo.Object, error) {
+	if len(args) != 1 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+	i1, ok := tengo.ToInt(args[0])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "int(compatible)",
+			Found:    args[0].TypeName(),
+		}
+	}
+	proc, err := os.FindProcess(i1)
+	if err != nil {
+		return wrapError(err), nil
+	}
+	return makeOSProcess(proc), nil
+}
+
+func osStartProcess(args ...tengo.Object) (tengo.Object, error) {
+	if len(args) != 4 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+	name, ok := tengo.ToString(args[0])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+	}
+	var argv []string
+	var err error
+	switch arg1 := args[1].(type) {
+	case *tengo.Array:
+		argv, err = stringArray(arg1.Value, "second")
+		if err != nil {
+			return nil, err
+		}
+	case *tengo.ImmutableArray:
+		argv, err = stringArray(arg1.Value, "second")
+		if err != nil {
+			return nil, err
+		}
+	default:
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "array",
+			Found:    arg1.TypeName(),
+		}
+	}
+
+	dir, ok := tengo.ToString(args[2])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "third",
+			Expected: "string(compatible)",
+			Found:    args[2].TypeName(),
+		}
+	}
+
+	var env []string
+	switch arg3 := args[3].(type) {
+	case *tengo.Array:
+		env, err = stringArray(arg3.Value, "fourth")
+		if err != nil {
+			return nil, err
+		}
+	case *tengo.ImmutableArray:
+		env, err = stringArray(arg3.Value, "fourth")
+		if err != nil {
+			return nil, err
+		}
+	default:
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "fourth",
+			Expected: "array",
+			Found:    arg3.TypeName(),
+		}
+	}
+
+	proc, err := os.StartProcess(name, argv, &os.ProcAttr{
+		Dir: dir,
+		Env: env,
+	})
+	if err != nil {
+		return wrapError(err), nil
+	}
+	return makeOSProcess(proc), nil
+}
+
+func stringArray(arr []tengo.Object, argName string) ([]string, error) {
+	var sarr []string
+	for idx, elem := range arr {
+		str, ok := elem.(*tengo.String)
+		if !ok {
+			return nil, tengo.ErrInvalidArgumentType{
+				Name:     fmt.Sprintf("%s[%d]", argName, idx),
+				Expected: "string",
+				Found:    elem.TypeName(),
+			}
+		}
+		sarr = append(sarr, str.Value)
+	}
+	return sarr, nil
+}
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/os_exec.go b/vendor/github.com/d5/tengo/v2/stdlib/os_exec.go
new file mode 100644
index 00000000..7ee5c1cd
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/os_exec.go
@@ -0,0 +1,119 @@
+package stdlib
+
+import (
+	"os/exec"
+
+	"github.com/d5/tengo/v2"
+)
+
+func makeOSExecCommand(cmd *exec.Cmd) *tengo.ImmutableMap {
+	return &tengo.ImmutableMap{
+		Value: map[string]tengo.Object{
+			// combined_output() => bytes/error
+			"combined_output": &tengo.UserFunction{
+				Name:  "combined_output",
+				Value: FuncARYE(cmd.CombinedOutput),
+			},
+			// output() => bytes/error
+			"output": &tengo.UserFunction{
+				Name:  "output",
+				Value: FuncARYE(cmd.Output),
+			}, //
+			// run() => error
+			"run": &tengo.UserFunction{
+				Name:  "run",
+				Value: FuncARE(cmd.Run),
+			}, //
+			// start() => error
+			"start": &tengo.UserFunction{
+				Name:  "start",
+				Value: FuncARE(cmd.Start),
+			}, //
+			// wait() => error
+			"wait": &tengo.UserFunction{
+				Name:  "wait",
+				Value: FuncARE(cmd.Wait),
+			}, //
+			// set_path(path string)
+			"set_path": &tengo.UserFunction{
+				Name: "set_path",
+				Value: func(args ...tengo.Object) (tengo.Object, error) {
+					if len(args) != 1 {
+						return nil, tengo.ErrWrongNumArguments
+					}
+					s1, ok := tengo.ToString(args[0])
+					if !ok {
+						return nil, tengo.ErrInvalidArgumentType{
+							Name:     "first",
+							Expected: "string(compatible)",
+							Found:    args[0].TypeName(),
+						}
+					}
+					cmd.Path = s1
+					return tengo.UndefinedValue, nil
+				},
+			},
+			// set_dir(dir string)
+			"set_dir": &tengo.UserFunction{
+				Name: "set_dir",
+				Value: func(args ...tengo.Object) (tengo.Object, error) {
+					if len(args) != 1 {
+						return nil, tengo.ErrWrongNumArguments
+					}
+					s1, ok := tengo.ToString(args[0])
+					if !ok {
+						return nil, tengo.ErrInvalidArgumentType{
+							Name:     "first",
+							Expected: "string(compatible)",
+							Found:    args[0].TypeName(),
+						}
+					}
+					cmd.Dir = s1
+					return tengo.UndefinedValue, nil
+				},
+			},
+			// set_env(env array(string))
+			"set_env": &tengo.UserFunction{
+				Name: "set_env",
+				Value: func(args ...tengo.Object) (tengo.Object, error) {
+					if len(args) != 1 {
+						return nil, tengo.ErrWrongNumArguments
+					}
+
+					var env []string
+					var err error
+					switch arg0 := args[0].(type) {
+					case *tengo.Array:
+						env, err = stringArray(arg0.Value, "first")
+						if err != nil {
+							return nil, err
+						}
+					case *tengo.ImmutableArray:
+						env, err = stringArray(arg0.Value, "first")
+						if err != nil {
+							return nil, err
+						}
+					default:
+						return nil, tengo.ErrInvalidArgumentType{
+							Name:     "first",
+							Expected: "array",
+							Found:    arg0.TypeName(),
+						}
+					}
+					cmd.Env = env
+					return tengo.UndefinedValue, nil
+				},
+			},
+			// process() => imap(process)
+			"process": &tengo.UserFunction{
+				Name: "process",
+				Value: func(args ...tengo.Object) (tengo.Object, error) {
+					if len(args) != 0 {
+						return nil, tengo.ErrWrongNumArguments
+					}
+					return makeOSProcess(cmd.Process), nil
+				},
+			},
+		},
+	}
+}
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/os_file.go b/vendor/github.com/d5/tengo/v2/stdlib/os_file.go
new file mode 100644
index 00000000..4f59b4c4
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/os_file.go
@@ -0,0 +1,117 @@
+package stdlib
+
+import (
+	"os"
+
+	"github.com/d5/tengo/v2"
+)
+
+func makeOSFile(file *os.File) *tengo.ImmutableMap {
+	return &tengo.ImmutableMap{
+		Value: map[string]tengo.Object{
+			// chdir() => true/error
+			"chdir": &tengo.UserFunction{
+				Name:  "chdir",
+				Value: FuncARE(file.Chdir),
+			}, //
+			// chown(uid int, gid int) => true/error
+			"chown": &tengo.UserFunction{
+				Name:  "chown",
+				Value: FuncAIIRE(file.Chown),
+			}, //
+			// close() => error
+			"close": &tengo.UserFunction{
+				Name:  "close",
+				Value: FuncARE(file.Close),
+			}, //
+			// name() => string
+			"name": &tengo.UserFunction{
+				Name:  "name",
+				Value: FuncARS(file.Name),
+			}, //
+			// readdirnames(n int) => array(string)/error
+			"readdirnames": &tengo.UserFunction{
+				Name:  "readdirnames",
+				Value: FuncAIRSsE(file.Readdirnames),
+			}, //
+			// sync() => error
+			"sync": &tengo.UserFunction{
+				Name:  "sync",
+				Value: FuncARE(file.Sync),
+			}, //
+			// write(bytes) => int/error
+			"write": &tengo.UserFunction{
+				Name:  "write",
+				Value: FuncAYRIE(file.Write),
+			}, //
+			// write(string) => int/error
+			"write_string": &tengo.UserFunction{
+				Name:  "write_string",
+				Value: FuncASRIE(file.WriteString),
+			}, //
+			// read(bytes) => int/error
+			"read": &tengo.UserFunction{
+				Name:  "read",
+				Value: FuncAYRIE(file.Read),
+			}, //
+			// chmod(mode int) => error
+			"chmod": &tengo.UserFunction{
+				Name: "chmod",
+				Value: func(args ...tengo.Object) (tengo.Object, error) {
+					if len(args) != 1 {
+						return nil, tengo.ErrWrongNumArguments
+					}
+					i1, ok := tengo.ToInt64(args[0])
+					if !ok {
+						return nil, tengo.ErrInvalidArgumentType{
+							Name:     "first",
+							Expected: "int(compatible)",
+							Found:    args[0].TypeName(),
+						}
+					}
+					return wrapError(file.Chmod(os.FileMode(i1))), nil
+				},
+			},
+			// seek(offset int, whence int) => int/error
+			"seek": &tengo.UserFunction{
+				Name: "seek",
+				Value: func(args ...tengo.Object) (tengo.Object, error) {
+					if len(args) != 2 {
+						return nil, tengo.ErrWrongNumArguments
+					}
+					i1, ok := tengo.ToInt64(args[0])
+					if !ok {
+						return nil, tengo.ErrInvalidArgumentType{
+							Name:     "first",
+							Expected: "int(compatible)",
+							Found:    args[0].TypeName(),
+						}
+					}
+					i2, ok := tengo.ToInt(args[1])
+					if !ok {
+						return nil, tengo.ErrInvalidArgumentType{
+							Name:     "second",
+							Expected: "int(compatible)",
+							Found:    args[1].TypeName(),
+						}
+					}
+					res, err := file.Seek(i1, i2)
+					if err != nil {
+						return wrapError(err), nil
+					}
+					return &tengo.Int{Value: res}, nil
+				},
+			},
+			// stat() => imap(fileinfo)/error
+			"stat": &tengo.UserFunction{
+				Name: "stat",
+				Value: func(args ...tengo.Object) (tengo.Object, error) {
+					if len(args) != 0 {
+						return nil, tengo.ErrWrongNumArguments
+					}
+					return osStat(&tengo.String{Value: file.Name()})
+				},
+			},
+		},
+	}
+}
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/os_process.go b/vendor/github.com/d5/tengo/v2/stdlib/os_process.go
new file mode 100644
index 00000000..7fcf27a4
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/os_process.go
@@ -0,0 +1,76 @@
+package stdlib
+
+import (
+	"os"
+	"syscall"
+
+	"github.com/d5/tengo/v2"
+)
+
+func makeOSProcessState(state *os.ProcessState) *tengo.ImmutableMap {
+	return &tengo.ImmutableMap{
+		Value: map[string]tengo.Object{
+			"exited": &tengo.UserFunction{
+				Name:  "exited",
+				Value: FuncARB(state.Exited),
+			},
+			"pid": &tengo.UserFunction{
+				Name:  "pid",
+				Value: FuncARI(state.Pid),
+			},
+			"string": &tengo.UserFunction{
+				Name:  "string",
+				Value: FuncARS(state.String),
+			},
+			"success": &tengo.UserFunction{
+				Name:  "success",
+				Value: FuncARB(state.Success),
+			},
+		},
+	}
+}
+
+func makeOSProcess(proc *os.Process) *tengo.ImmutableMap {
+	return &tengo.ImmutableMap{
+		Value: map[string]tengo.Object{
+			"kill": &tengo.UserFunction{
+				Name:  "kill",
+				Value: FuncARE(proc.Kill),
+			},
+			"release": &tengo.UserFunction{
+				Name:  "release",
+				Value: FuncARE(proc.Release),
+			},
+			"signal": &tengo.UserFunction{
+				Name: "signal",
+				Value: func(args ...tengo.Object) (tengo.Object, error) {
+					if len(args) != 1 {
+						return nil, tengo.ErrWrongNumArguments
+					}
+					i1, ok := tengo.ToInt64(args[0])
+					if !ok {
+						return nil, tengo.ErrInvalidArgumentType{
+							Name:     "first",
+							Expected: "int(compatible)",
+							Found:    args[0].TypeName(),
+						}
+					}
+					return wrapError(proc.Signal(syscall.Signal(i1))), nil
+				},
+			},
+			"wait": &tengo.UserFunction{
+				Name: "wait",
+				Value: func(args ...tengo.Object) (tengo.Object, error) {
+					if len(args) != 0 {
+						return nil, tengo.ErrWrongNumArguments
+					}
+					state, err := proc.Wait()
+					if err != nil {
+						return wrapError(err), nil
+					}
+					return makeOSProcessState(state), nil
+				},
+			},
+		},
+	}
+}
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/rand.go b/vendor/github.com/d5/tengo/v2/stdlib/rand.go
new file mode 100644
index 00000000..5d21e1df
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/rand.go
@@ -0,0 +1,138 @@
+package stdlib
+
+import (
+	"math/rand"
+
+	"github.com/d5/tengo/v2"
+)
+
+var randModule = map[string]tengo.Object{
+	"int": &tengo.UserFunction{
+		Name:  "int",
+		Value: FuncARI64(rand.Int63),
+	},
+	"float": &tengo.UserFunction{
+		Name:  "float",
+		Value: FuncARF(rand.Float64),
+	},
+	"intn": &tengo.UserFunction{
+		Name:  "intn",
+		Value: FuncAI64RI64(rand.Int63n),
+	},
+	"exp_float": &tengo.UserFunction{
+		Name:  "exp_float",
+		Value: FuncARF(rand.ExpFloat64),
+	},
+	"norm_float": &tengo.UserFunction{
+		Name:  "norm_float",
+		Value: FuncARF(rand.NormFloat64),
+	},
+	"perm": &tengo.UserFunction{
+		Name:  "perm",
+		Value: FuncAIRIs(rand.Perm),
+	},
+	"seed": &tengo.UserFunction{
+		Name:  "seed",
+		Value: FuncAI64R(rand.Seed),
+	},
+	"read": &tengo.UserFunction{
+		Name: "read",
+		Value: func(args ...tengo.Object) (ret tengo.Object, err error) {
+			if len(args) != 1 {
+				return nil, tengo.ErrWrongNumArguments
+			}
+			y1, ok := args[0].(*tengo.Bytes)
+			if !ok {
+				return nil, tengo.ErrInvalidArgumentType{
+					Name:     "first",
+					Expected: "bytes",
+					Found:    args[0].TypeName(),
+				}
+			}
+			res, err := rand.Read(y1.Value)
+			if err != nil {
+				ret = wrapError(err)
+				return
+			}
+			return &tengo.Int{Value: int64(res)}, nil
+		},
+	},
+	"rand": &tengo.UserFunction{
+		Name: "rand",
+		Value: func(args ...tengo.Object) (tengo.Object, error) {
+			if len(args) != 1 {
+				return nil, tengo.ErrWrongNumArguments
+			}
+			i1, ok := tengo.ToInt64(args[0])
+			if !ok {
+				return nil, tengo.ErrInvalidArgumentType{
+					Name:     "first",
+					Expected: "int(compatible)",
+					Found:    args[0].TypeName(),
+				}
+			}
+			src := rand.NewSource(i1)
+			return randRand(rand.New(src)), nil
+		},
+	},
+}
+
+func randRand(r *rand.Rand) *tengo.ImmutableMap {
+	return &tengo.ImmutableMap{
+		Value: map[string]tengo.Object{
+			"int": &tengo.UserFunction{
+				Name:  "int",
+				Value: FuncARI64(r.Int63),
+			},
+			"float": &tengo.UserFunction{
+				Name:  "float",
+				Value: FuncARF(r.Float64),
+			},
+			"intn": &tengo.UserFunction{
+				Name:  "intn",
+				Value: FuncAI64RI64(r.Int63n),
+			},
+			"exp_float": &tengo.UserFunction{
+				Name:  "exp_float",
+				Value: FuncARF(r.ExpFloat64),
+			},
+			"norm_float": &tengo.UserFunction{
+				Name:  "norm_float",
+				Value: FuncARF(r.NormFloat64),
+			},
+			"perm": &tengo.UserFunction{
+				Name:  "perm",
+				Value: FuncAIRIs(r.Perm),
+			},
+			"seed": &tengo.UserFunction{
+				Name:  "seed",
+				Value: FuncAI64R(r.Seed),
+			},
+			"read": &tengo.UserFunction{
+				Name: "read",
+				Value: func(args ...tengo.Object) (
+					ret tengo.Object,
+					err error,
+				) {
+					if len(args) != 1 {
+						return nil, tengo.ErrWrongNumArguments
+					}
+					y1, ok := args[0].(*tengo.Bytes)
+					if !ok {
+						return nil, tengo.ErrInvalidArgumentType{
+							Name:     "first",
+							Expected: "bytes",
+							Found:    args[0].TypeName(),
+						}
+					}
+					res, err := r.Read(y1.Value)
+					if err != nil {
+						ret = wrapError(err)
+						return
+					}
+					return &tengo.Int{Value: int64(res)}, nil
+				},
+			},
+		},
+	}
+}
diff --git a/vendor/github.com/d5/tengo/stdlib/source_modules.go b/vendor/github.com/d5/tengo/v2/stdlib/source_modules.go
index ca69d7d1..ca69d7d1 100644
--- a/vendor/github.com/d5/tengo/stdlib/source_modules.go
+++ b/vendor/github.com/d5/tengo/v2/stdlib/source_modules.go
diff --git a/vendor/github.com/d5/tengo/stdlib/srcmod_enum.tengo b/vendor/github.com/d5/tengo/v2/stdlib/srcmod_enum.tengo
index 7a5ea637..7a5ea637 100644
--- a/vendor/github.com/d5/tengo/stdlib/srcmod_enum.tengo
+++ b/vendor/github.com/d5/tengo/v2/stdlib/srcmod_enum.tengo
diff --git a/vendor/github.com/d5/tengo/stdlib/stdlib.go b/vendor/github.com/d5/tengo/v2/stdlib/stdlib.go
index aad220ee..16c369a0 100644
--- a/vendor/github.com/d5/tengo/stdlib/stdlib.go
+++ b/vendor/github.com/d5/tengo/v2/stdlib/stdlib.go
@@ -2,7 +2,9 @@ package stdlib
 
 //go:generate go run gensrcmods.go
 
-import "github.com/d5/tengo/objects"
+import (
+	"github.com/d5/tengo/v2"
+)
 
 // AllModuleNames returns a list of all default module names.
 func AllModuleNames() []string {
@@ -18,9 +20,8 @@ func AllModuleNames() []string {
 
 // GetModuleMap returns the module map that includes all modules
 // for the given module names.
-func GetModuleMap(names ...string) *objects.ModuleMap {
-	modules := objects.NewModuleMap()
-
+func GetModuleMap(names ...string) *tengo.ModuleMap {
+	modules := tengo.NewModuleMap()
 	for _, name := range names {
 		if mod := BuiltinModules[name]; mod != nil {
 			modules.AddBuiltinModule(name, mod)
@@ -29,6 +30,5 @@ func GetModuleMap(names ...string) *objects.ModuleMap {
 			modules.AddSourceModule(name, []byte(mod))
 		}
 	}
-
 	return modules
 }
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/text.go b/vendor/github.com/d5/tengo/v2/stdlib/text.go
new file mode 100644
index 00000000..d7d5d1da
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/text.go
@@ -0,0 +1,1072 @@
+package stdlib
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+	"strings"
+	"unicode/utf8"
+
+	"github.com/d5/tengo/v2"
+)
+
+var textModule = map[string]tengo.Object{
+	"re_match": &tengo.UserFunction{
+		Name:  "re_match",
+		Value: textREMatch,
+	}, // re_match(pattern, text) => bool/error
+	"re_find": &tengo.UserFunction{
+		Name:  "re_find",
+		Value: textREFind,
+	}, // re_find(pattern, text, count) => [[{text:,begin:,end:}]]/undefined
+	"re_replace": &tengo.UserFunction{
+		Name:  "re_replace",
+		Value: textREReplace,
+	}, // re_replace(pattern, text, repl) => string/error
+	"re_split": &tengo.UserFunction{
+		Name:  "re_split",
+		Value: textRESplit,
+	}, // re_split(pattern, text, count) => [string]/error
+	"re_compile": &tengo.UserFunction{
+		Name:  "re_compile",
+		Value: textRECompile,
+	}, // re_compile(pattern) => Regexp/error
+	"compare": &tengo.UserFunction{
+		Name:  "compare",
+		Value: FuncASSRI(strings.Compare),
+	}, // compare(a, b) => int
+	"contains": &tengo.UserFunction{
+		Name:  "contains",
+		Value: FuncASSRB(strings.Contains),
+	}, // contains(s, substr) => bool
+	"contains_any": &tengo.UserFunction{
+		Name:  "contains_any",
+		Value: FuncASSRB(strings.ContainsAny),
+	}, // contains_any(s, chars) => bool
+	"count": &tengo.UserFunction{
+		Name:  "count",
+		Value: FuncASSRI(strings.Count),
+	}, // count(s, substr) => int
+	"equal_fold": &tengo.UserFunction{
+		Name:  "equal_fold",
+		Value: FuncASSRB(strings.EqualFold),
+	}, // "equal_fold(s, t) => bool
+	"fields": &tengo.UserFunction{
+		Name:  "fields",
+		Value: FuncASRSs(strings.Fields),
+	}, // fields(s) => [string]
+	"has_prefix": &tengo.UserFunction{
+		Name:  "has_prefix",
+		Value: FuncASSRB(strings.HasPrefix),
+	}, // has_prefix(s, prefix) => bool
+	"has_suffix": &tengo.UserFunction{
+		Name:  "has_suffix",
+		Value: FuncASSRB(strings.HasSuffix),
+	}, // has_suffix(s, suffix) => bool
+	"index": &tengo.UserFunction{
+		Name:  "index",
+		Value: FuncASSRI(strings.Index),
+	}, // index(s, substr) => int
+	"index_any": &tengo.UserFunction{
+		Name:  "index_any",
+		Value: FuncASSRI(strings.IndexAny),
+	}, // index_any(s, chars) => int
+	"join": &tengo.UserFunction{
+		Name:  "join",
+		Value: textJoin,
+	}, // join(arr, sep) => string
+	"last_index": &tengo.UserFunction{
+		Name:  "last_index",
+		Value: FuncASSRI(strings.LastIndex),
+	}, // last_index(s, substr) => int
+	"last_index_any": &tengo.UserFunction{
+		Name:  "last_index_any",
+		Value: FuncASSRI(strings.LastIndexAny),
+	}, // last_index_any(s, chars) => int
+	"repeat": &tengo.UserFunction{
+		Name:  "repeat",
+		Value: textRepeat,
+	}, // repeat(s, count) => string
+	"replace": &tengo.UserFunction{
+		Name:  "replace",
+		Value: textReplace,
+	}, // replace(s, old, new, n) => string
+	"substr": &tengo.UserFunction{
+		Name:  "substr",
+		Value: textSubstring,
+	}, // substr(s, lower, upper) => string
+	"split": &tengo.UserFunction{
+		Name:  "split",
+		Value: FuncASSRSs(strings.Split),
+	}, // split(s, sep) => [string]
+	"split_after": &tengo.UserFunction{
+		Name:  "split_after",
+		Value: FuncASSRSs(strings.SplitAfter),
+	}, // split_after(s, sep) => [string]
+	"split_after_n": &tengo.UserFunction{
+		Name:  "split_after_n",
+		Value: FuncASSIRSs(strings.SplitAfterN),
+	}, // split_after_n(s, sep, n) => [string]
+	"split_n": &tengo.UserFunction{
+		Name:  "split_n",
+		Value: FuncASSIRSs(strings.SplitN),
+	}, // split_n(s, sep, n) => [string]
+	"title": &tengo.UserFunction{
+		Name:  "title",
+		Value: FuncASRS(strings.Title),
+	}, // title(s) => string
+	"to_lower": &tengo.UserFunction{
+		Name:  "to_lower",
+		Value: FuncASRS(strings.ToLower),
+	}, // to_lower(s) => string
+	"to_title": &tengo.UserFunction{
+		Name:  "to_title",
+		Value: FuncASRS(strings.ToTitle),
+	}, // to_title(s) => string
+	"to_upper": &tengo.UserFunction{
+		Name:  "to_upper",
+		Value: FuncASRS(strings.ToUpper),
+	}, // to_upper(s) => string
+	"pad_left": &tengo.UserFunction{
+		Name:  "pad_left",
+		Value: textPadLeft,
+	}, // pad_left(s, pad_len, pad_with) => string
+	"pad_right": &tengo.UserFunction{
+		Name:  "pad_right",
+		Value: textPadRight,
+	}, // pad_right(s, pad_len, pad_with) => string
+	"trim": &tengo.UserFunction{
+		Name:  "trim",
+		Value: FuncASSRS(strings.Trim),
+	}, // trim(s, cutset) => string
+	"trim_left": &tengo.UserFunction{
+		Name:  "trim_left",
+		Value: FuncASSRS(strings.TrimLeft),
+	}, // trim_left(s, cutset) => string
+	"trim_prefix": &tengo.UserFunction{
+		Name:  "trim_prefix",
+		Value: FuncASSRS(strings.TrimPrefix),
+	}, // trim_prefix(s, prefix) => string
+	"trim_right": &tengo.UserFunction{
+		Name:  "trim_right",
+		Value: FuncASSRS(strings.TrimRight),
+	}, // trim_right(s, cutset) => string
+	"trim_space": &tengo.UserFunction{
+		Name:  "trim_space",
+		Value: FuncASRS(strings.TrimSpace),
+	}, // trim_space(s) => string
+	"trim_suffix": &tengo.UserFunction{
+		Name:  "trim_suffix",
+		Value: FuncASSRS(strings.TrimSuffix),
+	}, // trim_suffix(s, suffix) => string
+	"atoi": &tengo.UserFunction{
+		Name:  "atoi",
+		Value: FuncASRIE(strconv.Atoi),
+	}, // atoi(str) => int/error
+	"format_bool": &tengo.UserFunction{
+		Name:  "format_bool",
+		Value: textFormatBool,
+	}, // format_bool(b) => string
+	"format_float": &tengo.UserFunction{
+		Name:  "format_float",
+		Value: textFormatFloat,
+	}, // format_float(f, fmt, prec, bits) => string
+	"format_int": &tengo.UserFunction{
+		Name:  "format_int",
+		Value: textFormatInt,
+	}, // format_int(i, base) => string
+	"itoa": &tengo.UserFunction{
+		Name:  "itoa",
+		Value: FuncAIRS(strconv.Itoa),
+	}, // itoa(i) => string
+	"parse_bool": &tengo.UserFunction{
+		Name:  "parse_bool",
+		Value: textParseBool,
+	}, // parse_bool(str) => bool/error
+	"parse_float": &tengo.UserFunction{
+		Name:  "parse_float",
+		Value: textParseFloat,
+	}, // parse_float(str, bits) => float/error
+	"parse_int": &tengo.UserFunction{
+		Name:  "parse_int",
+		Value: textParseInt,
+	}, // parse_int(str, base, bits) => int/error
+	"quote": &tengo.UserFunction{
+		Name:  "quote",
+		Value: FuncASRS(strconv.Quote),
+	}, // quote(str) => string
+	"unquote": &tengo.UserFunction{
+		Name:  "unquote",
+		Value: FuncASRSE(strconv.Unquote),
+	}, // unquote(str) => string/error
+}
+
+func textREMatch(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 2 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	s2, ok := tengo.ToString(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "string(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	matched, err := regexp.MatchString(s1, s2)
+	if err != nil {
+		ret = wrapError(err)
+		return
+	}
+
+	if matched {
+		ret = tengo.TrueValue
+	} else {
+		ret = tengo.FalseValue
+	}
+
+	return
+}
+
+func textREFind(args ...tengo.Object) (ret tengo.Object, err error) {
+	numArgs := len(args)
+	if numArgs != 2 && numArgs != 3 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	re, err := regexp.Compile(s1)
+	if err != nil {
+		ret = wrapError(err)
+		return
+	}
+
+	s2, ok := tengo.ToString(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "string(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	if numArgs < 3 {
+		m := re.FindStringSubmatchIndex(s2)
+		if m == nil {
+			ret = tengo.UndefinedValue
+			return
+		}
+
+		arr := &tengo.Array{}
+		for i := 0; i < len(m); i += 2 {
+			arr.Value = append(arr.Value,
+				&tengo.ImmutableMap{Value: map[string]tengo.Object{
+					"text":  &tengo.String{Value: s2[m[i]:m[i+1]]},
+					"begin": &tengo.Int{Value: int64(m[i])},
+					"end":   &tengo.Int{Value: int64(m[i+1])},
+				}})
+		}
+
+		ret = &tengo.Array{Value: []tengo.Object{arr}}
+
+		return
+	}
+
+	i3, ok := tengo.ToInt(args[2])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "third",
+			Expected: "int(compatible)",
+			Found:    args[2].TypeName(),
+		}
+		return
+	}
+	m := re.FindAllStringSubmatchIndex(s2, i3)
+	if m == nil {
+		ret = tengo.UndefinedValue
+		return
+	}
+
+	arr := &tengo.Array{}
+	for _, m := range m {
+		subMatch := &tengo.Array{}
+		for i := 0; i < len(m); i += 2 {
+			subMatch.Value = append(subMatch.Value,
+				&tengo.ImmutableMap{Value: map[string]tengo.Object{
+					"text":  &tengo.String{Value: s2[m[i]:m[i+1]]},
+					"begin": &tengo.Int{Value: int64(m[i])},
+					"end":   &tengo.Int{Value: int64(m[i+1])},
+				}})
+		}
+
+		arr.Value = append(arr.Value, subMatch)
+	}
+
+	ret = arr
+
+	return
+}
+
+func textREReplace(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 3 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	s2, ok := tengo.ToString(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "string(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	s3, ok := tengo.ToString(args[2])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "third",
+			Expected: "string(compatible)",
+			Found:    args[2].TypeName(),
+		}
+		return
+	}
+
+	re, err := regexp.Compile(s1)
+	if err != nil {
+		ret = wrapError(err)
+	} else {
+		s, ok := doTextRegexpReplace(re, s2, s3)
+		if !ok {
+			return nil, tengo.ErrStringLimit
+		}
+
+		ret = &tengo.String{Value: s}
+	}
+
+	return
+}
+
+func textRESplit(args ...tengo.Object) (ret tengo.Object, err error) {
+	numArgs := len(args)
+	if numArgs != 2 && numArgs != 3 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	s2, ok := tengo.ToString(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "string(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	var i3 = -1
+	if numArgs > 2 {
+		i3, ok = tengo.ToInt(args[2])
+		if !ok {
+			err = tengo.ErrInvalidArgumentType{
+				Name:     "third",
+				Expected: "int(compatible)",
+				Found:    args[2].TypeName(),
+			}
+			return
+		}
+	}
+
+	re, err := regexp.Compile(s1)
+	if err != nil {
+		ret = wrapError(err)
+		return
+	}
+
+	arr := &tengo.Array{}
+	for _, s := range re.Split(s2, i3) {
+		arr.Value = append(arr.Value, &tengo.String{Value: s})
+	}
+
+	ret = arr
+
+	return
+}
+
+func textRECompile(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	re, err := regexp.Compile(s1)
+	if err != nil {
+		ret = wrapError(err)
+	} else {
+		ret = makeTextRegexp(re)
+	}
+
+	return
+}
+
+func textReplace(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 4 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	s2, ok := tengo.ToString(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "string(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	s3, ok := tengo.ToString(args[2])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "third",
+			Expected: "string(compatible)",
+			Found:    args[2].TypeName(),
+		}
+		return
+	}
+
+	i4, ok := tengo.ToInt(args[3])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "fourth",
+			Expected: "int(compatible)",
+			Found:    args[3].TypeName(),
+		}
+		return
+	}
+
+	s, ok := doTextReplace(s1, s2, s3, i4)
+	if !ok {
+		err = tengo.ErrStringLimit
+		return
+	}
+
+	ret = &tengo.String{Value: s}
+
+	return
+}
+
+func textSubstring(args ...tengo.Object) (ret tengo.Object, err error) {
+	argslen := len(args)
+	if argslen != 2 && argslen != 3 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	i2, ok := tengo.ToInt(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "int(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	strlen := len(s1)
+	i3 := strlen
+	if argslen == 3 {
+		i3, ok = tengo.ToInt(args[2])
+		if !ok {
+			err = tengo.ErrInvalidArgumentType{
+				Name:     "third",
+				Expected: "int(compatible)",
+				Found:    args[2].TypeName(),
+			}
+			return
+		}
+	}
+
+	if i2 > i3 {
+		err = tengo.ErrInvalidIndexType
+		return
+	}
+
+	if i2 < 0 {
+		i2 = 0
+	} else if i2 > strlen {
+		i2 = strlen
+	}
+
+	if i3 < 0 {
+		i3 = 0
+	} else if i3 > strlen {
+		i3 = strlen
+	}
+
+	ret = &tengo.String{Value: s1[i2:i3]}
+
+	return
+}
+
+func textPadLeft(args ...tengo.Object) (ret tengo.Object, err error) {
+	argslen := len(args)
+	if argslen != 2 && argslen != 3 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	i2, ok := tengo.ToInt(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "int(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	if i2 > tengo.MaxStringLen {
+		return nil, tengo.ErrStringLimit
+	}
+
+	sLen := len(s1)
+	if sLen >= i2 {
+		ret = &tengo.String{Value: s1}
+		return
+	}
+
+	s3 := " "
+	if argslen == 3 {
+		s3, ok = tengo.ToString(args[2])
+		if !ok {
+			err = tengo.ErrInvalidArgumentType{
+				Name:     "third",
+				Expected: "string(compatible)",
+				Found:    args[2].TypeName(),
+			}
+			return
+		}
+	}
+
+	padStrLen := len(s3)
+	if padStrLen == 0 {
+		ret = &tengo.String{Value: s1}
+		return
+	}
+
+	padCount := ((i2 - padStrLen) / padStrLen) + 1
+	retStr := strings.Repeat(s3, padCount) + s1
+	ret = &tengo.String{Value: retStr[len(retStr)-i2:]}
+
+	return
+}
+
+func textPadRight(args ...tengo.Object) (ret tengo.Object, err error) {
+	argslen := len(args)
+	if argslen != 2 && argslen != 3 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	i2, ok := tengo.ToInt(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "int(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	if i2 > tengo.MaxStringLen {
+		return nil, tengo.ErrStringLimit
+	}
+
+	sLen := len(s1)
+	if sLen >= i2 {
+		ret = &tengo.String{Value: s1}
+		return
+	}
+
+	s3 := " "
+	if argslen == 3 {
+		s3, ok = tengo.ToString(args[2])
+		if !ok {
+			err = tengo.ErrInvalidArgumentType{
+				Name:     "third",
+				Expected: "string(compatible)",
+				Found:    args[2].TypeName(),
+			}
+			return
+		}
+	}
+
+	padStrLen := len(s3)
+	if padStrLen == 0 {
+		ret = &tengo.String{Value: s1}
+		return
+	}
+
+	padCount := ((i2 - padStrLen) / padStrLen) + 1
+	retStr := s1 + strings.Repeat(s3, padCount)
+	ret = &tengo.String{Value: retStr[:i2]}
+
+	return
+}
+
+func textRepeat(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 2 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+	}
+
+	i2, ok := tengo.ToInt(args[1])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "int(compatible)",
+			Found:    args[1].TypeName(),
+		}
+	}
+
+	if len(s1)*i2 > tengo.MaxStringLen {
+		return nil, tengo.ErrStringLimit
+	}
+
+	return &tengo.String{Value: strings.Repeat(s1, i2)}, nil
+}
+
+func textJoin(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 2 {
+		return nil, tengo.ErrWrongNumArguments
+	}
+
+	var slen int
+	var ss1 []string
+	switch arg0 := args[0].(type) {
+	case *tengo.Array:
+		for idx, a := range arg0.Value {
+			as, ok := tengo.ToString(a)
+			if !ok {
+				return nil, tengo.ErrInvalidArgumentType{
+					Name:     fmt.Sprintf("first[%d]", idx),
+					Expected: "string(compatible)",
+					Found:    a.TypeName(),
+				}
+			}
+			slen += len(as)
+			ss1 = append(ss1, as)
+		}
+	case *tengo.ImmutableArray:
+		for idx, a := range arg0.Value {
+			as, ok := tengo.ToString(a)
+			if !ok {
+				return nil, tengo.ErrInvalidArgumentType{
+					Name:     fmt.Sprintf("first[%d]", idx),
+					Expected: "string(compatible)",
+					Found:    a.TypeName(),
+				}
+			}
+			slen += len(as)
+			ss1 = append(ss1, as)
+		}
+	default:
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "array",
+			Found:    args[0].TypeName(),
+		}
+	}
+
+	s2, ok := tengo.ToString(args[1])
+	if !ok {
+		return nil, tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "string(compatible)",
+			Found:    args[1].TypeName(),
+		}
+	}
+
+	// make sure output length does not exceed the limit
+	if slen+len(s2)*(len(ss1)-1) > tengo.MaxStringLen {
+		return nil, tengo.ErrStringLimit
+	}
+
+	return &tengo.String{Value: strings.Join(ss1, s2)}, nil
+}
+
+func textFormatBool(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	b1, ok := args[0].(*tengo.Bool)
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "bool",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	if b1 == tengo.TrueValue {
+		ret = &tengo.String{Value: "true"}
+	} else {
+		ret = &tengo.String{Value: "false"}
+	}
+
+	return
+}
+
+func textFormatFloat(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 4 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	f1, ok := args[0].(*tengo.Float)
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "float",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	s2, ok := tengo.ToString(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "string(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	i3, ok := tengo.ToInt(args[2])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "third",
+			Expected: "int(compatible)",
+			Found:    args[2].TypeName(),
+		}
+		return
+	}
+
+	i4, ok := tengo.ToInt(args[3])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "fourth",
+			Expected: "int(compatible)",
+			Found:    args[3].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.String{Value: strconv.FormatFloat(f1.Value, s2[0], i3, i4)}
+
+	return
+}
+
+func textFormatInt(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 2 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	i1, ok := args[0].(*tengo.Int)
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "int",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	i2, ok := tengo.ToInt(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "int(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.String{Value: strconv.FormatInt(i1.Value, i2)}
+
+	return
+}
+
+func textParseBool(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	s1, ok := args[0].(*tengo.String)
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	parsed, err := strconv.ParseBool(s1.Value)
+	if err != nil {
+		ret = wrapError(err)
+		return
+	}
+
+	if parsed {
+		ret = tengo.TrueValue
+	} else {
+		ret = tengo.FalseValue
+	}
+
+	return
+}
+
+func textParseFloat(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 2 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	s1, ok := args[0].(*tengo.String)
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	i2, ok := tengo.ToInt(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "int(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	parsed, err := strconv.ParseFloat(s1.Value, i2)
+	if err != nil {
+		ret = wrapError(err)
+		return
+	}
+
+	ret = &tengo.Float{Value: parsed}
+
+	return
+}
+
+func textParseInt(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 3 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	s1, ok := args[0].(*tengo.String)
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	i2, ok := tengo.ToInt(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "int(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	i3, ok := tengo.ToInt(args[2])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "third",
+			Expected: "int(compatible)",
+			Found:    args[2].TypeName(),
+		}
+		return
+	}
+
+	parsed, err := strconv.ParseInt(s1.Value, i2, i3)
+	if err != nil {
+		ret = wrapError(err)
+		return
+	}
+
+	ret = &tengo.Int{Value: parsed}
+
+	return
+}
+
+// Modified implementation of strings.Replace
+// to limit the maximum length of output string.
+func doTextReplace(s, old, new string, n int) (string, bool) {
+	if old == new || n == 0 {
+		return s, true // avoid allocation
+	}
+
+	// Compute number of replacements.
+	if m := strings.Count(s, old); m == 0 {
+		return s, true // avoid allocation
+	} else if n < 0 || m < n {
+		n = m
+	}
+
+	// Apply replacements to buffer.
+	t := make([]byte, len(s)+n*(len(new)-len(old)))
+	w := 0
+	start := 0
+	for i := 0; i < n; i++ {
+		j := start
+		if len(old) == 0 {
+			if i > 0 {
+				_, wid := utf8.DecodeRuneInString(s[start:])
+				j += wid
+			}
+		} else {
+			j += strings.Index(s[start:], old)
+		}
+
+		ssj := s[start:j]
+		if w+len(ssj)+len(new) > tengo.MaxStringLen {
+			return "", false
+		}
+
+		w += copy(t[w:], ssj)
+		w += copy(t[w:], new)
+		start = j + len(old)
+	}
+
+	ss := s[start:]
+	if w+len(ss) > tengo.MaxStringLen {
+		return "", false
+	}
+
+	w += copy(t[w:], ss)
+
+	return string(t[0:w]), true
+}
diff --git a/vendor/github.com/d5/tengo/stdlib/text_regexp.go b/vendor/github.com/d5/tengo/v2/stdlib/text_regexp.go
index 16f135bf..1a7ecf07 100644
--- a/vendor/github.com/d5/tengo/stdlib/text_regexp.go
+++ b/vendor/github.com/d5/tengo/v2/stdlib/text_regexp.go
@@ -3,24 +3,26 @@ package stdlib
 import (
 	"regexp"
 
-	"github.com/d5/tengo"
-	"github.com/d5/tengo/objects"
+	"github.com/d5/tengo/v2"
 )
 
-func makeTextRegexp(re *regexp.Regexp) *objects.ImmutableMap {
-	return &objects.ImmutableMap{
-		Value: map[string]objects.Object{
+func makeTextRegexp(re *regexp.Regexp) *tengo.ImmutableMap {
+	return &tengo.ImmutableMap{
+		Value: map[string]tengo.Object{
 			// match(text) => bool
-			"match": &objects.UserFunction{
-				Value: func(args ...objects.Object) (ret objects.Object, err error) {
+			"match": &tengo.UserFunction{
+				Value: func(args ...tengo.Object) (
+					ret tengo.Object,
+					err error,
+				) {
 					if len(args) != 1 {
-						err = objects.ErrWrongNumArguments
+						err = tengo.ErrWrongNumArguments
 						return
 					}
 
-					s1, ok := objects.ToString(args[0])
+					s1, ok := tengo.ToString(args[0])
 					if !ok {
-						err = objects.ErrInvalidArgumentType{
+						err = tengo.ErrInvalidArgumentType{
 							Name:     "first",
 							Expected: "string(compatible)",
 							Found:    args[0].TypeName(),
@@ -29,9 +31,9 @@ func makeTextRegexp(re *regexp.Regexp) *objects.ImmutableMap {
 					}
 
 					if re.MatchString(s1) {
-						ret = objects.TrueValue
+						ret = tengo.TrueValue
 					} else {
-						ret = objects.FalseValue
+						ret = tengo.FalseValue
 					}
 
 					return
@@ -40,17 +42,20 @@ func makeTextRegexp(re *regexp.Regexp) *objects.ImmutableMap {
 
 			// find(text) 			=> array(array({text:,begin:,end:}))/undefined
 			// find(text, maxCount) => array(array({text:,begin:,end:}))/undefined
-			"find": &objects.UserFunction{
-				Value: func(args ...objects.Object) (ret objects.Object, err error) {
+			"find": &tengo.UserFunction{
+				Value: func(args ...tengo.Object) (
+					ret tengo.Object,
+					err error,
+				) {
 					numArgs := len(args)
 					if numArgs != 1 && numArgs != 2 {
-						err = objects.ErrWrongNumArguments
+						err = tengo.ErrWrongNumArguments
 						return
 					}
 
-					s1, ok := objects.ToString(args[0])
+					s1, ok := tengo.ToString(args[0])
 					if !ok {
-						err = objects.ErrInvalidArgumentType{
+						err = tengo.ErrInvalidArgumentType{
 							Name:     "first",
 							Expected: "string(compatible)",
 							Found:    args[0].TypeName(),
@@ -61,27 +66,35 @@ func makeTextRegexp(re *regexp.Regexp) *objects.ImmutableMap {
 					if numArgs == 1 {
 						m := re.FindStringSubmatchIndex(s1)
 						if m == nil {
-							ret = objects.UndefinedValue
+							ret = tengo.UndefinedValue
 							return
 						}
 
-						arr := &objects.Array{}
+						arr := &tengo.Array{}
 						for i := 0; i < len(m); i += 2 {
-							arr.Value = append(arr.Value, &objects.ImmutableMap{Value: map[string]objects.Object{
-								"text":  &objects.String{Value: s1[m[i]:m[i+1]]},
-								"begin": &objects.Int{Value: int64(m[i])},
-								"end":   &objects.Int{Value: int64(m[i+1])},
-							}})
+							arr.Value = append(arr.Value,
+								&tengo.ImmutableMap{
+									Value: map[string]tengo.Object{
+										"text": &tengo.String{
+											Value: s1[m[i]:m[i+1]],
+										},
+										"begin": &tengo.Int{
+											Value: int64(m[i]),
+										},
+										"end": &tengo.Int{
+											Value: int64(m[i+1]),
+										},
+									}})
 						}
 
-						ret = &objects.Array{Value: []objects.Object{arr}}
+						ret = &tengo.Array{Value: []tengo.Object{arr}}
 
 						return
 					}
 
-					i2, ok := objects.ToInt(args[1])
+					i2, ok := tengo.ToInt(args[1])
 					if !ok {
-						err = objects.ErrInvalidArgumentType{
+						err = tengo.ErrInvalidArgumentType{
 							Name:     "second",
 							Expected: "int(compatible)",
 							Found:    args[1].TypeName(),
@@ -90,19 +103,27 @@ func makeTextRegexp(re *regexp.Regexp) *objects.ImmutableMap {
 					}
 					m := re.FindAllStringSubmatchIndex(s1, i2)
 					if m == nil {
-						ret = objects.UndefinedValue
+						ret = tengo.UndefinedValue
 						return
 					}
 
-					arr := &objects.Array{}
+					arr := &tengo.Array{}
 					for _, m := range m {
-						subMatch := &objects.Array{}
+						subMatch := &tengo.Array{}
 						for i := 0; i < len(m); i += 2 {
-							subMatch.Value = append(subMatch.Value, &objects.ImmutableMap{Value: map[string]objects.Object{
-								"text":  &objects.String{Value: s1[m[i]:m[i+1]]},
-								"begin": &objects.Int{Value: int64(m[i])},
-								"end":   &objects.Int{Value: int64(m[i+1])},
-							}})
+							subMatch.Value = append(subMatch.Value,
+								&tengo.ImmutableMap{
+									Value: map[string]tengo.Object{
+										"text": &tengo.String{
+											Value: s1[m[i]:m[i+1]],
+										},
+										"begin": &tengo.Int{
+											Value: int64(m[i]),
+										},
+										"end": &tengo.Int{
+											Value: int64(m[i+1]),
+										},
+									}})
 						}
 
 						arr.Value = append(arr.Value, subMatch)
@@ -115,16 +136,19 @@ func makeTextRegexp(re *regexp.Regexp) *objects.ImmutableMap {
 			},
 
 			// replace(src, repl) => string
-			"replace": &objects.UserFunction{
-				Value: func(args ...objects.Object) (ret objects.Object, err error) {
+			"replace": &tengo.UserFunction{
+				Value: func(args ...tengo.Object) (
+					ret tengo.Object,
+					err error,
+				) {
 					if len(args) != 2 {
-						err = objects.ErrWrongNumArguments
+						err = tengo.ErrWrongNumArguments
 						return
 					}
 
-					s1, ok := objects.ToString(args[0])
+					s1, ok := tengo.ToString(args[0])
 					if !ok {
-						err = objects.ErrInvalidArgumentType{
+						err = tengo.ErrInvalidArgumentType{
 							Name:     "first",
 							Expected: "string(compatible)",
 							Found:    args[0].TypeName(),
@@ -132,9 +156,9 @@ func makeTextRegexp(re *regexp.Regexp) *objects.ImmutableMap {
 						return
 					}
 
-					s2, ok := objects.ToString(args[1])
+					s2, ok := tengo.ToString(args[1])
 					if !ok {
-						err = objects.ErrInvalidArgumentType{
+						err = tengo.ErrInvalidArgumentType{
 							Name:     "second",
 							Expected: "string(compatible)",
 							Found:    args[1].TypeName(),
@@ -144,10 +168,10 @@ func makeTextRegexp(re *regexp.Regexp) *objects.ImmutableMap {
 
 					s, ok := doTextRegexpReplace(re, s1, s2)
 					if !ok {
-						return nil, objects.ErrStringLimit
+						return nil, tengo.ErrStringLimit
 					}
 
-					ret = &objects.String{Value: s}
+					ret = &tengo.String{Value: s}
 
 					return
 				},
@@ -155,17 +179,20 @@ func makeTextRegexp(re *regexp.Regexp) *objects.ImmutableMap {
 
 			// split(text) 			 => array(string)
 			// split(text, maxCount) => array(string)
-			"split": &objects.UserFunction{
-				Value: func(args ...objects.Object) (ret objects.Object, err error) {
+			"split": &tengo.UserFunction{
+				Value: func(args ...tengo.Object) (
+					ret tengo.Object,
+					err error,
+				) {
 					numArgs := len(args)
 					if numArgs != 1 && numArgs != 2 {
-						err = objects.ErrWrongNumArguments
+						err = tengo.ErrWrongNumArguments
 						return
 					}
 
-					s1, ok := objects.ToString(args[0])
+					s1, ok := tengo.ToString(args[0])
 					if !ok {
-						err = objects.ErrInvalidArgumentType{
+						err = tengo.ErrInvalidArgumentType{
 							Name:     "first",
 							Expected: "string(compatible)",
 							Found:    args[0].TypeName(),
@@ -175,9 +202,9 @@ func makeTextRegexp(re *regexp.Regexp) *objects.ImmutableMap {
 
 					var i2 = -1
 					if numArgs > 1 {
-						i2, ok = objects.ToInt(args[1])
+						i2, ok = tengo.ToInt(args[1])
 						if !ok {
-							err = objects.ErrInvalidArgumentType{
+							err = tengo.ErrInvalidArgumentType{
 								Name:     "second",
 								Expected: "int(compatible)",
 								Found:    args[1].TypeName(),
@@ -186,9 +213,10 @@ func makeTextRegexp(re *regexp.Regexp) *objects.ImmutableMap {
 						}
 					}
 
-					arr := &objects.Array{}
+					arr := &tengo.Array{}
 					for _, s := range re.Split(s1, i2) {
-						arr.Value = append(arr.Value, &objects.String{Value: s})
+						arr.Value = append(arr.Value,
+							&tengo.String{Value: s})
 					}
 
 					ret = arr
@@ -204,15 +232,12 @@ func makeTextRegexp(re *regexp.Regexp) *objects.ImmutableMap {
 func doTextRegexpReplace(re *regexp.Regexp, src, repl string) (string, bool) {
 	idx := 0
 	out := ""
-
 	for _, m := range re.FindAllStringSubmatchIndex(src, -1) {
 		var exp []byte
 		exp = re.ExpandString(exp, repl, src, m)
-
 		if len(out)+m[0]-idx+len(exp) > tengo.MaxStringLen {
 			return "", false
 		}
-
 		out += src[idx:m[0]] + string(exp)
 		idx = m[1]
 	}
@@ -220,9 +245,7 @@ func doTextRegexpReplace(re *regexp.Regexp, src, repl string) (string, bool) {
 		if len(out)+len(src)-idx > tengo.MaxStringLen {
 			return "", false
 		}
-
 		out += src[idx:]
 	}
-
-	return string(out), true
+	return out, true
 }
diff --git a/vendor/github.com/d5/tengo/v2/stdlib/times.go b/vendor/github.com/d5/tengo/v2/stdlib/times.go
new file mode 100644
index 00000000..0b6f7bd4
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/stdlib/times.go
@@ -0,0 +1,1135 @@
+package stdlib
+
+import (
+	"time"
+
+	"github.com/d5/tengo/v2"
+)
+
+var timesModule = map[string]tengo.Object{
+	"format_ansic":        &tengo.String{Value: time.ANSIC},
+	"format_unix_date":    &tengo.String{Value: time.UnixDate},
+	"format_ruby_date":    &tengo.String{Value: time.RubyDate},
+	"format_rfc822":       &tengo.String{Value: time.RFC822},
+	"format_rfc822z":      &tengo.String{Value: time.RFC822Z},
+	"format_rfc850":       &tengo.String{Value: time.RFC850},
+	"format_rfc1123":      &tengo.String{Value: time.RFC1123},
+	"format_rfc1123z":     &tengo.String{Value: time.RFC1123Z},
+	"format_rfc3339":      &tengo.String{Value: time.RFC3339},
+	"format_rfc3339_nano": &tengo.String{Value: time.RFC3339Nano},
+	"format_kitchen":      &tengo.String{Value: time.Kitchen},
+	"format_stamp":        &tengo.String{Value: time.Stamp},
+	"format_stamp_milli":  &tengo.String{Value: time.StampMilli},
+	"format_stamp_micro":  &tengo.String{Value: time.StampMicro},
+	"format_stamp_nano":   &tengo.String{Value: time.StampNano},
+	"nanosecond":          &tengo.Int{Value: int64(time.Nanosecond)},
+	"microsecond":         &tengo.Int{Value: int64(time.Microsecond)},
+	"millisecond":         &tengo.Int{Value: int64(time.Millisecond)},
+	"second":              &tengo.Int{Value: int64(time.Second)},
+	"minute":              &tengo.Int{Value: int64(time.Minute)},
+	"hour":                &tengo.Int{Value: int64(time.Hour)},
+	"january":             &tengo.Int{Value: int64(time.January)},
+	"february":            &tengo.Int{Value: int64(time.February)},
+	"march":               &tengo.Int{Value: int64(time.March)},
+	"april":               &tengo.Int{Value: int64(time.April)},
+	"may":                 &tengo.Int{Value: int64(time.May)},
+	"june":                &tengo.Int{Value: int64(time.June)},
+	"july":                &tengo.Int{Value: int64(time.July)},
+	"august":              &tengo.Int{Value: int64(time.August)},
+	"september":           &tengo.Int{Value: int64(time.September)},
+	"october":             &tengo.Int{Value: int64(time.October)},
+	"november":            &tengo.Int{Value: int64(time.November)},
+	"december":            &tengo.Int{Value: int64(time.December)},
+	"sleep": &tengo.UserFunction{
+		Name:  "sleep",
+		Value: timesSleep,
+	}, // sleep(int)
+	"parse_duration": &tengo.UserFunction{
+		Name:  "parse_duration",
+		Value: timesParseDuration,
+	}, // parse_duration(str) => int
+	"since": &tengo.UserFunction{
+		Name:  "since",
+		Value: timesSince,
+	}, // since(time) => int
+	"until": &tengo.UserFunction{
+		Name:  "until",
+		Value: timesUntil,
+	}, // until(time) => int
+	"duration_hours": &tengo.UserFunction{
+		Name:  "duration_hours",
+		Value: timesDurationHours,
+	}, // duration_hours(int) => float
+	"duration_minutes": &tengo.UserFunction{
+		Name:  "duration_minutes",
+		Value: timesDurationMinutes,
+	}, // duration_minutes(int) => float
+	"duration_nanoseconds": &tengo.UserFunction{
+		Name:  "duration_nanoseconds",
+		Value: timesDurationNanoseconds,
+	}, // duration_nanoseconds(int) => int
+	"duration_seconds": &tengo.UserFunction{
+		Name:  "duration_seconds",
+		Value: timesDurationSeconds,
+	}, // duration_seconds(int) => float
+	"duration_string": &tengo.UserFunction{
+		Name:  "duration_string",
+		Value: timesDurationString,
+	}, // duration_string(int) => string
+	"month_string": &tengo.UserFunction{
+		Name:  "month_string",
+		Value: timesMonthString,
+	}, // month_string(int) => string
+	"date": &tengo.UserFunction{
+		Name:  "date",
+		Value: timesDate,
+	}, // date(year, month, day, hour, min, sec, nsec) => time
+	"now": &tengo.UserFunction{
+		Name:  "now",
+		Value: timesNow,
+	}, // now() => time
+	"parse": &tengo.UserFunction{
+		Name:  "parse",
+		Value: timesParse,
+	}, // parse(format, str) => time
+	"unix": &tengo.UserFunction{
+		Name:  "unix",
+		Value: timesUnix,
+	}, // unix(sec, nsec) => time
+	"add": &tengo.UserFunction{
+		Name:  "add",
+		Value: timesAdd,
+	}, // add(time, int) => time
+	"add_date": &tengo.UserFunction{
+		Name:  "add_date",
+		Value: timesAddDate,
+	}, // add_date(time, years, months, days) => time
+	"sub": &tengo.UserFunction{
+		Name:  "sub",
+		Value: timesSub,
+	}, // sub(t time, u time) => int
+	"after": &tengo.UserFunction{
+		Name:  "after",
+		Value: timesAfter,
+	}, // after(t time, u time) => bool
+	"before": &tengo.UserFunction{
+		Name:  "before",
+		Value: timesBefore,
+	}, // before(t time, u time) => bool
+	"time_year": &tengo.UserFunction{
+		Name:  "time_year",
+		Value: timesTimeYear,
+	}, // time_year(time) => int
+	"time_month": &tengo.UserFunction{
+		Name:  "time_month",
+		Value: timesTimeMonth,
+	}, // time_month(time) => int
+	"time_day": &tengo.UserFunction{
+		Name:  "time_day",
+		Value: timesTimeDay,
+	}, // time_day(time) => int
+	"time_weekday": &tengo.UserFunction{
+		Name:  "time_weekday",
+		Value: timesTimeWeekday,
+	}, // time_weekday(time) => int
+	"time_hour": &tengo.UserFunction{
+		Name:  "time_hour",
+		Value: timesTimeHour,
+	}, // time_hour(time) => int
+	"time_minute": &tengo.UserFunction{
+		Name:  "time_minute",
+		Value: timesTimeMinute,
+	}, // time_minute(time) => int
+	"time_second": &tengo.UserFunction{
+		Name:  "time_second",
+		Value: timesTimeSecond,
+	}, // time_second(time) => int
+	"time_nanosecond": &tengo.UserFunction{
+		Name:  "time_nanosecond",
+		Value: timesTimeNanosecond,
+	}, // time_nanosecond(time) => int
+	"time_unix": &tengo.UserFunction{
+		Name:  "time_unix",
+		Value: timesTimeUnix,
+	}, // time_unix(time) => int
+	"time_unix_nano": &tengo.UserFunction{
+		Name:  "time_unix_nano",
+		Value: timesTimeUnixNano,
+	}, // time_unix_nano(time) => int
+	"time_format": &tengo.UserFunction{
+		Name:  "time_format",
+		Value: timesTimeFormat,
+	}, // time_format(time, format) => string
+	"time_location": &tengo.UserFunction{
+		Name:  "time_location",
+		Value: timesTimeLocation,
+	}, // time_location(time) => string
+	"time_string": &tengo.UserFunction{
+		Name:  "time_string",
+		Value: timesTimeString,
+	}, // time_string(time) => string
+	"is_zero": &tengo.UserFunction{
+		Name:  "is_zero",
+		Value: timesIsZero,
+	}, // is_zero(time) => bool
+	"to_local": &tengo.UserFunction{
+		Name:  "to_local",
+		Value: timesToLocal,
+	}, // to_local(time) => time
+	"to_utc": &tengo.UserFunction{
+		Name:  "to_utc",
+		Value: timesToUTC,
+	}, // to_utc(time) => time
+}
+
+func timesSleep(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	i1, ok := tengo.ToInt64(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "int(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	time.Sleep(time.Duration(i1))
+	ret = tengo.UndefinedValue
+
+	return
+}
+
+func timesParseDuration(args ...tengo.Object) (
+	ret tengo.Object,
+	err error,
+) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	dur, err := time.ParseDuration(s1)
+	if err != nil {
+		ret = wrapError(err)
+		return
+	}
+
+	ret = &tengo.Int{Value: int64(dur)}
+
+	return
+}
+
+func timesSince(args ...tengo.Object) (
+	ret tengo.Object,
+	err error,
+) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Int{Value: int64(time.Since(t1))}
+
+	return
+}
+
+func timesUntil(args ...tengo.Object) (
+	ret tengo.Object,
+	err error,
+) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Int{Value: int64(time.Until(t1))}
+
+	return
+}
+
+func timesDurationHours(args ...tengo.Object) (
+	ret tengo.Object,
+	err error,
+) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	i1, ok := tengo.ToInt64(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "int(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Float{Value: time.Duration(i1).Hours()}
+
+	return
+}
+
+func timesDurationMinutes(args ...tengo.Object) (
+	ret tengo.Object,
+	err error,
+) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	i1, ok := tengo.ToInt64(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "int(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Float{Value: time.Duration(i1).Minutes()}
+
+	return
+}
+
+func timesDurationNanoseconds(args ...tengo.Object) (
+	ret tengo.Object,
+	err error,
+) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	i1, ok := tengo.ToInt64(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "int(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Int{Value: time.Duration(i1).Nanoseconds()}
+
+	return
+}
+
+func timesDurationSeconds(args ...tengo.Object) (
+	ret tengo.Object,
+	err error,
+) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	i1, ok := tengo.ToInt64(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "int(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Float{Value: time.Duration(i1).Seconds()}
+
+	return
+}
+
+func timesDurationString(args ...tengo.Object) (
+	ret tengo.Object,
+	err error,
+) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	i1, ok := tengo.ToInt64(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "int(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.String{Value: time.Duration(i1).String()}
+
+	return
+}
+
+func timesMonthString(args ...tengo.Object) (
+	ret tengo.Object,
+	err error,
+) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	i1, ok := tengo.ToInt64(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "int(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.String{Value: time.Month(i1).String()}
+
+	return
+}
+
+func timesDate(args ...tengo.Object) (
+	ret tengo.Object,
+	err error,
+) {
+	if len(args) != 7 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	i1, ok := tengo.ToInt(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "int(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+	i2, ok := tengo.ToInt(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "int(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+	i3, ok := tengo.ToInt(args[2])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "third",
+			Expected: "int(compatible)",
+			Found:    args[2].TypeName(),
+		}
+		return
+	}
+	i4, ok := tengo.ToInt(args[3])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "fourth",
+			Expected: "int(compatible)",
+			Found:    args[3].TypeName(),
+		}
+		return
+	}
+	i5, ok := tengo.ToInt(args[4])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "fifth",
+			Expected: "int(compatible)",
+			Found:    args[4].TypeName(),
+		}
+		return
+	}
+	i6, ok := tengo.ToInt(args[5])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "sixth",
+			Expected: "int(compatible)",
+			Found:    args[5].TypeName(),
+		}
+		return
+	}
+	i7, ok := tengo.ToInt(args[6])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "seventh",
+			Expected: "int(compatible)",
+			Found:    args[6].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Time{
+		Value: time.Date(i1,
+			time.Month(i2), i3, i4, i5, i6, i7, time.Now().Location()),
+	}
+
+	return
+}
+
+func timesNow(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 0 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	ret = &tengo.Time{Value: time.Now()}
+
+	return
+}
+
+func timesParse(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 2 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	s1, ok := tengo.ToString(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "string(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	s2, ok := tengo.ToString(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "string(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	parsed, err := time.Parse(s1, s2)
+	if err != nil {
+		ret = wrapError(err)
+		return
+	}
+
+	ret = &tengo.Time{Value: parsed}
+
+	return
+}
+
+func timesUnix(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 2 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	i1, ok := tengo.ToInt64(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "int(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	i2, ok := tengo.ToInt64(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "int(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Time{Value: time.Unix(i1, i2)}
+
+	return
+}
+
+func timesAdd(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 2 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	i2, ok := tengo.ToInt64(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "int(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Time{Value: t1.Add(time.Duration(i2))}
+
+	return
+}
+
+func timesSub(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 2 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	t2, ok := tengo.ToTime(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "time(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Int{Value: int64(t1.Sub(t2))}
+
+	return
+}
+
+func timesAddDate(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 4 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	i2, ok := tengo.ToInt(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "int(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	i3, ok := tengo.ToInt(args[2])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "third",
+			Expected: "int(compatible)",
+			Found:    args[2].TypeName(),
+		}
+		return
+	}
+
+	i4, ok := tengo.ToInt(args[3])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "fourth",
+			Expected: "int(compatible)",
+			Found:    args[3].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Time{Value: t1.AddDate(i2, i3, i4)}
+
+	return
+}
+
+func timesAfter(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 2 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	t2, ok := tengo.ToTime(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "time(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	if t1.After(t2) {
+		ret = tengo.TrueValue
+	} else {
+		ret = tengo.FalseValue
+	}
+
+	return
+}
+
+func timesBefore(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 2 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	t2, ok := tengo.ToTime(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	if t1.Before(t2) {
+		ret = tengo.TrueValue
+	} else {
+		ret = tengo.FalseValue
+	}
+
+	return
+}
+
+func timesTimeYear(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Int{Value: int64(t1.Year())}
+
+	return
+}
+
+func timesTimeMonth(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Int{Value: int64(t1.Month())}
+
+	return
+}
+
+func timesTimeDay(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Int{Value: int64(t1.Day())}
+
+	return
+}
+
+func timesTimeWeekday(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Int{Value: int64(t1.Weekday())}
+
+	return
+}
+
+func timesTimeHour(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Int{Value: int64(t1.Hour())}
+
+	return
+}
+
+func timesTimeMinute(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Int{Value: int64(t1.Minute())}
+
+	return
+}
+
+func timesTimeSecond(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Int{Value: int64(t1.Second())}
+
+	return
+}
+
+func timesTimeNanosecond(args ...tengo.Object) (
+	ret tengo.Object,
+	err error,
+) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Int{Value: int64(t1.Nanosecond())}
+
+	return
+}
+
+func timesTimeUnix(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Int{Value: t1.Unix()}
+
+	return
+}
+
+func timesTimeUnixNano(args ...tengo.Object) (
+	ret tengo.Object,
+	err error,
+) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Int{Value: t1.UnixNano()}
+
+	return
+}
+
+func timesTimeFormat(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 2 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	s2, ok := tengo.ToString(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "string(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	s := t1.Format(s2)
+	if len(s) > tengo.MaxStringLen {
+
+		return nil, tengo.ErrStringLimit
+	}
+
+	ret = &tengo.String{Value: s}
+
+	return
+}
+
+func timesIsZero(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	if t1.IsZero() {
+		ret = tengo.TrueValue
+	} else {
+		ret = tengo.FalseValue
+	}
+
+	return
+}
+
+func timesToLocal(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Time{Value: t1.Local()}
+
+	return
+}
+
+func timesToUTC(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.Time{Value: t1.UTC()}
+
+	return
+}
+
+func timesTimeLocation(args ...tengo.Object) (
+	ret tengo.Object,
+	err error,
+) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.String{Value: t1.Location().String()}
+
+	return
+}
+
+func timesTimeString(args ...tengo.Object) (ret tengo.Object, err error) {
+	if len(args) != 1 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	ret = &tengo.String{Value: t1.String()}
+
+	return
+}
diff --git a/vendor/github.com/d5/tengo/compiler/symbol_table.go b/vendor/github.com/d5/tengo/v2/symbol_table.go
index 94c868de..6ae5d7d3 100644
--- a/vendor/github.com/d5/tengo/compiler/symbol_table.go
+++ b/vendor/github.com/d5/tengo/v2/symbol_table.go
@@ -1,4 +1,23 @@
-package compiler
+package tengo
+
+// SymbolScope represents a symbol scope.
+type SymbolScope string
+
+// List of symbol scopes
+const (
+	ScopeGlobal  SymbolScope = "GLOBAL"
+	ScopeLocal   SymbolScope = "LOCAL"
+	ScopeBuiltin SymbolScope = "BUILTIN"
+	ScopeFree    SymbolScope = "FREE"
+)
+
+// Symbol represents a symbol in the symbol table.
+type Symbol struct {
+	Name          string
+	Scope         SymbolScope
+	Index         int
+	LocalAssigned bool // if the local symbol is assigned at least once
+}
 
 // SymbolTable represents a symbol table.
 type SymbolTable struct {
@@ -28,11 +47,8 @@ func (t *SymbolTable) Define(name string) *Symbol {
 	} else {
 		symbol.Scope = ScopeLocal
 	}
-
 	t.store[name] = symbol
-
 	t.updateMaxDefs(symbol.Index + 1)
-
 	return symbol
 }
 
@@ -47,34 +63,32 @@ func (t *SymbolTable) DefineBuiltin(index int, name string) *Symbol {
 		Index: index,
 		Scope: ScopeBuiltin,
 	}
-
 	t.store[name] = symbol
-
 	t.builtinSymbols = append(t.builtinSymbols, symbol)
-
 	return symbol
 }
 
 // Resolve resolves a symbol with a given name.
-func (t *SymbolTable) Resolve(name string) (symbol *Symbol, depth int, ok bool) {
+func (t *SymbolTable) Resolve(
+	name string,
+) (symbol *Symbol, depth int, ok bool) {
 	symbol, ok = t.store[name]
 	if !ok && t.parent != nil {
 		symbol, depth, ok = t.parent.Resolve(name)
 		if !ok {
 			return
 		}
-
 		depth++
 
 		// if symbol is defined in parent table and if it's not global/builtin
 		// then it's free variable.
-		if !t.block && depth > 0 && symbol.Scope != ScopeGlobal && symbol.Scope != ScopeBuiltin {
+		if !t.block && depth > 0 &&
+			symbol.Scope != ScopeGlobal &&
+			symbol.Scope != ScopeBuiltin {
 			return t.defineFree(symbol), depth, true
 		}
-
 		return
 	}
-
 	return
 }
 
@@ -92,7 +106,6 @@ func (t *SymbolTable) Parent(skipBlock bool) *SymbolTable {
 	if skipBlock && t.block {
 		return t.parent.Parent(skipBlock)
 	}
-
 	return t.parent
 }
 
@@ -111,7 +124,6 @@ func (t *SymbolTable) BuiltinSymbols() []*Symbol {
 	if t.parent != nil {
 		return t.parent.BuiltinSymbols()
 	}
-
 	return t.builtinSymbols
 }
 
@@ -128,7 +140,6 @@ func (t *SymbolTable) nextIndex() int {
 	if t.block {
 		return t.parent.nextIndex() + t.numDefinition
 	}
-
 	return t.numDefinition
 }
 
@@ -136,7 +147,6 @@ func (t *SymbolTable) updateMaxDefs(numDefs int) {
 	if numDefs > t.maxDefinition {
 		t.maxDefinition = numDefs
 	}
-
 	if t.block {
 		t.parent.updateMaxDefs(numDefs)
 	}
@@ -144,16 +154,12 @@ func (t *SymbolTable) updateMaxDefs(numDefs int) {
 
 func (t *SymbolTable) defineFree(original *Symbol) *Symbol {
 	// TODO: should we check duplicates?
-
 	t.freeSymbols = append(t.freeSymbols, original)
-
 	symbol := &Symbol{
 		Name:  original.Name,
 		Index: len(t.freeSymbols) - 1,
 		Scope: ScopeFree,
 	}
-
 	t.store[original.Name] = symbol
-
 	return symbol
 }
diff --git a/vendor/github.com/d5/tengo/objects/conversion.go b/vendor/github.com/d5/tengo/v2/tengo.go
index 27514132..098a1970 100644
--- a/vendor/github.com/d5/tengo/objects/conversion.go
+++ b/vendor/github.com/d5/tengo/v2/tengo.go
@@ -1,29 +1,75 @@
-package objects
+package tengo
 
 import (
 	"errors"
 	"fmt"
 	"strconv"
 	"time"
+)
+
+var (
+	// MaxStringLen is the maximum byte-length for string value. Note this
+	// limit applies to all compiler/VM instances in the process.
+	MaxStringLen = 2147483647
 
-	"github.com/d5/tengo"
+	// MaxBytesLen is the maximum length for bytes value. Note this limit
+	// applies to all compiler/VM instances in the process.
+	MaxBytesLen = 2147483647
 )
 
+const (
+	// GlobalsSize is the maximum number of global variables for a VM.
+	GlobalsSize = 1024
+
+	// StackSize is the maximum stack size for a VM.
+	StackSize = 2048
+
+	// MaxFrames is the maximum number of function frames for a VM.
+	MaxFrames = 1024
+)
+
+// CallableFunc is a function signature for the callable functions.
+type CallableFunc = func(args ...Object) (ret Object, err error)
+
+// CountObjects returns the number of objects that a given object o contains.
+// For scalar value types, it will always be 1. For compound value types,
+// this will include its elements and all of their elements recursively.
+func CountObjects(o Object) (c int) {
+	c = 1
+	switch o := o.(type) {
+	case *Array:
+		for _, v := range o.Value {
+			c += CountObjects(v)
+		}
+	case *ImmutableArray:
+		for _, v := range o.Value {
+			c += CountObjects(v)
+		}
+	case *Map:
+		for _, v := range o.Value {
+			c += CountObjects(v)
+		}
+	case *ImmutableMap:
+		for _, v := range o.Value {
+			c += CountObjects(v)
+		}
+	case *Error:
+		c += CountObjects(o.Value)
+	}
+	return
+}
+
 // ToString will try to convert object o to string value.
 func ToString(o Object) (v string, ok bool) {
 	if o == UndefinedValue {
-		//ok = false
 		return
 	}
-
 	ok = true
-
 	if str, isStr := o.(*String); isStr {
 		v = str.Value
 	} else {
 		v = o.String()
 	}
-
 	return
 }
 
@@ -51,8 +97,6 @@ func ToInt(o Object) (v int, ok bool) {
 			ok = true
 		}
 	}
-
-	//ok = false
 	return
 }
 
@@ -80,8 +124,6 @@ func ToInt64(o Object) (v int64, ok bool) {
 			ok = true
 		}
 	}
-
-	//ok = false
 	return
 }
 
@@ -101,8 +143,6 @@ func ToFloat64(o Object) (v float64, ok bool) {
 			ok = true
 		}
 	}
-
-	//ok = false
 	return
 }
 
@@ -110,7 +150,6 @@ func ToFloat64(o Object) (v float64, ok bool) {
 func ToBool(o Object) (v bool, ok bool) {
 	ok = true
 	v = !o.IsFalsy()
-
 	return
 }
 
@@ -121,11 +160,9 @@ func ToRune(o Object) (v rune, ok bool) {
 		v = rune(o.Value)
 		ok = true
 	case *Char:
-		v = rune(o.Value)
+		v = o.Value
 		ok = true
 	}
-
-	//ok = false
 	return
 }
 
@@ -139,8 +176,6 @@ func ToByteSlice(o Object) (v []byte, ok bool) {
 		v = []byte(o.Value)
 		ok = true
 	}
-
-	//ok = false
 	return
 }
 
@@ -154,8 +189,6 @@ func ToTime(o Object) (v time.Time, ok bool) {
 		v = time.Unix(o.Value, 0)
 		ok = true
 	}
-
-	//ok = false
 	return
 }
 
@@ -203,7 +236,6 @@ func ToInterface(o Object) (res interface{}) {
 	case Object:
 		return o
 	}
-
 	return
 }
 
@@ -213,7 +245,7 @@ func FromInterface(v interface{}) (Object, error) {
 	case nil:
 		return UndefinedValue, nil
 	case string:
-		if len(v) > tengo.MaxStringLen {
+		if len(v) > MaxStringLen {
 			return nil, ErrStringLimit
 		}
 		return &String{Value: v}, nil
@@ -233,7 +265,7 @@ func FromInterface(v interface{}) (Object, error) {
 	case float64:
 		return &Float{Value: v}, nil
 	case []byte:
-		if len(v) > tengo.MaxBytesLen {
+		if len(v) > MaxBytesLen {
 			return nil, ErrBytesLimit
 		}
 		return &Bytes{Value: v}, nil
@@ -260,7 +292,6 @@ func FromInterface(v interface{}) (Object, error) {
 			if err != nil {
 				return nil, err
 			}
-
 			arr[i] = vo
 		}
 		return &Array{Value: arr}, nil
@@ -271,6 +302,5 @@ func FromInterface(v interface{}) (Object, error) {
 	case CallableFunc:
 		return &UserFunction{Value: v}, nil
 	}
-
 	return nil, fmt.Errorf("cannot convert to object: %T", v)
 }
diff --git a/vendor/github.com/d5/tengo/compiler/token/tokens.go b/vendor/github.com/d5/tengo/v2/token/token.go
index b32d36ee..4e6aa80a 100644
--- a/vendor/github.com/d5/tengo/compiler/token/tokens.go
+++ b/vendor/github.com/d5/tengo/v2/token/token.go
@@ -2,6 +2,8 @@ package token
 
 import "strconv"
 
+var keywords map[string]Token
+
 // Token represents a token.
 type Token int
 
@@ -206,3 +208,18 @@ func (tok Token) IsOperator() bool {
 func (tok Token) IsKeyword() bool {
 	return _keywordBeg < tok && tok < _keywordEnd
 }
+
+// Lookup returns corresponding keyword if ident is a keyword.
+func Lookup(ident string) Token {
+	if tok, isKeyword := keywords[ident]; isKeyword {
+		return tok
+	}
+	return Ident
+}
+
+func init() {
+	keywords = make(map[string]Token)
+	for i := _keywordBeg + 1; i < _keywordEnd; i++ {
+		keywords[tokens[i]] = i
+	}
+}
diff --git a/vendor/github.com/d5/tengo/script/variable.go b/vendor/github.com/d5/tengo/v2/variable.go
index df345115..481b36b8 100644
--- a/vendor/github.com/d5/tengo/script/variable.go
+++ b/vendor/github.com/d5/tengo/v2/variable.go
@@ -1,24 +1,21 @@
-package script
+package tengo
 
 import (
 	"errors"
-
-	"github.com/d5/tengo/objects"
 )
 
 // Variable is a user-defined variable for the script.
 type Variable struct {
 	name  string
-	value objects.Object
+	value Object
 }
 
 // NewVariable creates a Variable.
 func NewVariable(name string, value interface{}) (*Variable, error) {
-	obj, err := objects.FromInterface(value)
+	obj, err := FromInterface(value)
 	if err != nil {
 		return nil, err
 	}
-
 	return &Variable{
 		name:  name,
 		value: obj,
@@ -32,7 +29,7 @@ func (v *Variable) Name() string {
 
 // Value returns an empty interface of the variable value.
 func (v *Variable) Value() interface{} {
-	return objects.ToInterface(v.value)
+	return ToInterface(v.value)
 }
 
 // ValueType returns the name of the value type.
@@ -43,107 +40,97 @@ func (v *Variable) ValueType() string {
 // Int returns int value of the variable value.
 // It returns 0 if the value is not convertible to int.
 func (v *Variable) Int() int {
-	c, _ := objects.ToInt(v.value)
-
+	c, _ := ToInt(v.value)
 	return c
 }
 
-// Int64 returns int64 value of the variable value.
-// It returns 0 if the value is not convertible to int64.
+// Int64 returns int64 value of the variable value. It returns 0 if the value
+// is not convertible to int64.
 func (v *Variable) Int64() int64 {
-	c, _ := objects.ToInt64(v.value)
-
+	c, _ := ToInt64(v.value)
 	return c
 }
 
-// Float returns float64 value of the variable value.
-// It returns 0.0 if the value is not convertible to float64.
+// Float returns float64 value of the variable value. It returns 0.0 if the
+// value is not convertible to float64.
 func (v *Variable) Float() float64 {
-	c, _ := objects.ToFloat64(v.value)
-
+	c, _ := ToFloat64(v.value)
 	return c
 }
 
-// Char returns rune value of the variable value.
-// It returns 0 if the value is not convertible to rune.
+// Char returns rune value of the variable value. It returns 0 if the value is
+// not convertible to rune.
 func (v *Variable) Char() rune {
-	c, _ := objects.ToRune(v.value)
-
+	c, _ := ToRune(v.value)
 	return c
 }
 
-// Bool returns bool value of the variable value.
-// It returns 0 if the value is not convertible to bool.
+// Bool returns bool value of the variable value. It returns 0 if the value is
+// not convertible to bool.
 func (v *Variable) Bool() bool {
-	c, _ := objects.ToBool(v.value)
-
+	c, _ := ToBool(v.value)
 	return c
 }
 
-// Array returns []interface value of the variable value.
-// It returns 0 if the value is not convertible to []interface.
+// Array returns []interface value of the variable value. It returns 0 if the
+// value is not convertible to []interface.
 func (v *Variable) Array() []interface{} {
 	switch val := v.value.(type) {
-	case *objects.Array:
+	case *Array:
 		var arr []interface{}
 		for _, e := range val.Value {
-			arr = append(arr, objects.ToInterface(e))
+			arr = append(arr, ToInterface(e))
 		}
 		return arr
 	}
-
 	return nil
 }
 
-// Map returns map[string]interface{} value of the variable value.
-// It returns 0 if the value is not convertible to map[string]interface{}.
+// Map returns map[string]interface{} value of the variable value. It returns
+// 0 if the value is not convertible to map[string]interface{}.
 func (v *Variable) Map() map[string]interface{} {
 	switch val := v.value.(type) {
-	case *objects.Map:
+	case *Map:
 		kv := make(map[string]interface{})
 		for mk, mv := range val.Value {
-			kv[mk] = objects.ToInterface(mv)
+			kv[mk] = ToInterface(mv)
 		}
 		return kv
 	}
-
 	return nil
 }
 
-// String returns string value of the variable value.
-// It returns 0 if the value is not convertible to string.
+// String returns string value of the variable value. It returns 0 if the value
+// is not convertible to string.
 func (v *Variable) String() string {
-	c, _ := objects.ToString(v.value)
-
+	c, _ := ToString(v.value)
 	return c
 }
 
-// Bytes returns a byte slice of the variable value.
-// It returns nil if the value is not convertible to byte slice.
+// Bytes returns a byte slice of the variable value. It returns nil if the
+// value is not convertible to byte slice.
 func (v *Variable) Bytes() []byte {
-	c, _ := objects.ToByteSlice(v.value)
-
+	c, _ := ToByteSlice(v.value)
 	return c
 }
 
-// Error returns an error if the underlying value is error object.
-// If not, this returns nil.
+// Error returns an error if the underlying value is error object. If not,
+// this returns nil.
 func (v *Variable) Error() error {
-	err, ok := v.value.(*objects.Error)
+	err, ok := v.value.(*Error)
 	if ok {
 		return errors.New(err.String())
 	}
-
 	return nil
 }
 
-// Object returns an underlying Object of the variable value.
-// Note that returned Object is a copy of an actual Object used in the script.
-func (v *Variable) Object() objects.Object {
+// Object returns an underlying Object of the variable value. Note that
+// returned Object is a copy of an actual Object used in the script.
+func (v *Variable) Object() Object {
 	return v.value
 }
 
 // IsUndefined returns true if the underlying value is undefined.
 func (v *Variable) IsUndefined() bool {
-	return v.value == objects.UndefinedValue
+	return v.value == UndefinedValue
 }
diff --git a/vendor/github.com/d5/tengo/runtime/vm.go b/vendor/github.com/d5/tengo/v2/vm.go
index 07f6e530..783a54a9 100644
--- a/vendor/github.com/d5/tengo/runtime/vm.go
+++ b/vendor/github.com/d5/tengo/v2/vm.go
@@ -1,36 +1,31 @@
-package runtime
+package tengo
 
 import (
 	"fmt"
 	"sync/atomic"
 
-	"github.com/d5/tengo/compiler"
-	"github.com/d5/tengo/compiler/source"
-	"github.com/d5/tengo/compiler/token"
-	"github.com/d5/tengo/objects"
+	"github.com/d5/tengo/v2/parser"
+	"github.com/d5/tengo/v2/token"
 )
 
-const (
-	// StackSize is the maximum stack size.
-	StackSize = 2048
-
-	// GlobalsSize is the maximum number of global variables.
-	GlobalsSize = 1024
-
-	// MaxFrames is the maximum number of function frames.
-	MaxFrames = 1024
-)
+// frame represents a function call frame.
+type frame struct {
+	fn          *CompiledFunction
+	freeVars    []*ObjectPtr
+	ip          int
+	basePointer int
+}
 
 // VM is a virtual machine that executes the bytecode compiled by Compiler.
 type VM struct {
-	constants   []objects.Object
-	stack       [StackSize]objects.Object
+	constants   []Object
+	stack       [StackSize]Object
 	sp          int
-	globals     []objects.Object
-	fileSet     *source.FileSet
-	frames      [MaxFrames]Frame
+	globals     []Object
+	fileSet     *parser.SourceFileSet
+	frames      [MaxFrames]frame
 	framesIndex int
-	curFrame    *Frame
+	curFrame    *frame
 	curInsts    []byte
 	ip          int
 	aborting    int64
@@ -40,11 +35,14 @@ type VM struct {
 }
 
 // NewVM creates a VM.
-func NewVM(bytecode *compiler.Bytecode, globals []objects.Object, maxAllocs int64) *VM {
+func NewVM(
+	bytecode *Bytecode,
+	globals []Object,
+	maxAllocs int64,
+) *VM {
 	if globals == nil {
-		globals = make([]objects.Object, GlobalsSize)
+		globals = make([]Object, GlobalsSize)
 	}
-
 	v := &VM{
 		constants:   bytecode.Constants,
 		sp:          0,
@@ -54,12 +52,10 @@ func NewVM(bytecode *compiler.Bytecode, globals []objects.Object, maxAllocs int6
 		ip:          -1,
 		maxAllocs:   maxAllocs,
 	}
-
 	v.frames[0].fn = bytecode.MainFunction
 	v.frames[0].ip = -1
 	v.curFrame = &v.frames[0]
 	v.curInsts = v.curFrame.fn.Instructions
-
 	return v
 }
 
@@ -79,75 +75,52 @@ func (v *VM) Run() (err error) {
 	v.allocs = v.maxAllocs + 1
 
 	v.run()
-
 	atomic.StoreInt64(&v.aborting, 0)
-
 	err = v.err
 	if err != nil {
-		filePos := v.fileSet.Position(v.curFrame.fn.SourcePos(v.ip - 1))
-		err = fmt.Errorf("Runtime Error: %s\n\tat %s", err.Error(), filePos)
+		filePos := v.fileSet.Position(
+			v.curFrame.fn.SourcePos(v.ip - 1))
+		err = fmt.Errorf("Runtime Error: %s\n\tat %s",
+			err.Error(), filePos)
 		for v.framesIndex > 1 {
 			v.framesIndex--
 			v.curFrame = &v.frames[v.framesIndex-1]
-
-			filePos = v.fileSet.Position(v.curFrame.fn.SourcePos(v.curFrame.ip - 1))
+			filePos = v.fileSet.Position(
+				v.curFrame.fn.SourcePos(v.curFrame.ip - 1))
 			err = fmt.Errorf("%s\n\tat %s", err.Error(), filePos)
 		}
 		return err
 	}
-
 	return nil
 }
 
 func (v *VM) run() {
-	defer func() {
-		if r := recover(); r != nil {
-			if v.sp >= StackSize || v.framesIndex >= MaxFrames {
-				v.err = ErrStackOverflow
-				return
-			}
-
-			if v.ip < len(v.curInsts)-1 {
-				if err, ok := r.(error); ok {
-					v.err = err
-				} else {
-					v.err = fmt.Errorf("panic: %v", r)
-				}
-			}
-		}
-	}()
-
 	for atomic.LoadInt64(&v.aborting) == 0 {
 		v.ip++
 
 		switch v.curInsts[v.ip] {
-		case compiler.OpConstant:
+		case parser.OpConstant:
 			v.ip += 2
 			cidx := int(v.curInsts[v.ip]) | int(v.curInsts[v.ip-1])<<8
 
 			v.stack[v.sp] = v.constants[cidx]
 			v.sp++
-
-		case compiler.OpNull:
-			v.stack[v.sp] = objects.UndefinedValue
+		case parser.OpNull:
+			v.stack[v.sp] = UndefinedValue
 			v.sp++
-
-		case compiler.OpBinaryOp:
+		case parser.OpBinaryOp:
 			v.ip++
 			right := v.stack[v.sp-1]
 			left := v.stack[v.sp-2]
-
 			tok := token.Token(v.curInsts[v.ip])
 			res, e := left.BinaryOp(tok, right)
 			if e != nil {
 				v.sp -= 2
-
-				if e == objects.ErrInvalidOperator {
+				if e == ErrInvalidOperator {
 					v.err = fmt.Errorf("invalid operation: %s %s %s",
 						left.TypeName(), tok.String(), right.TypeName())
 					return
 				}
-
 				v.err = e
 				return
 			}
@@ -160,185 +133,155 @@ func (v *VM) run() {
 
 			v.stack[v.sp-2] = res
 			v.sp--
-
-		case compiler.OpEqual:
+		case parser.OpEqual:
 			right := v.stack[v.sp-1]
 			left := v.stack[v.sp-2]
 			v.sp -= 2
-
 			if left.Equals(right) {
-				v.stack[v.sp] = objects.TrueValue
+				v.stack[v.sp] = TrueValue
 			} else {
-				v.stack[v.sp] = objects.FalseValue
+				v.stack[v.sp] = FalseValue
 			}
 			v.sp++
-
-		case compiler.OpNotEqual:
+		case parser.OpNotEqual:
 			right := v.stack[v.sp-1]
 			left := v.stack[v.sp-2]
 			v.sp -= 2
-
 			if left.Equals(right) {
-				v.stack[v.sp] = objects.FalseValue
+				v.stack[v.sp] = FalseValue
 			} else {
-				v.stack[v.sp] = objects.TrueValue
+				v.stack[v.sp] = TrueValue
 			}
 			v.sp++
-
-		case compiler.OpPop:
+		case parser.OpPop:
 			v.sp--
-
-		case compiler.OpTrue:
-			v.stack[v.sp] = objects.TrueValue
+		case parser.OpTrue:
+			v.stack[v.sp] = TrueValue
 			v.sp++
-
-		case compiler.OpFalse:
-			v.stack[v.sp] = objects.FalseValue
+		case parser.OpFalse:
+			v.stack[v.sp] = FalseValue
 			v.sp++
-
-		case compiler.OpLNot:
+		case parser.OpLNot:
 			operand := v.stack[v.sp-1]
 			v.sp--
-
 			if operand.IsFalsy() {
-				v.stack[v.sp] = objects.TrueValue
+				v.stack[v.sp] = TrueValue
 			} else {
-				v.stack[v.sp] = objects.FalseValue
+				v.stack[v.sp] = FalseValue
 			}
 			v.sp++
-
-		case compiler.OpBComplement:
+		case parser.OpBComplement:
 			operand := v.stack[v.sp-1]
 			v.sp--
 
 			switch x := operand.(type) {
-			case *objects.Int:
-				var res objects.Object = &objects.Int{Value: ^x.Value}
-
+			case *Int:
+				var res Object = &Int{Value: ^x.Value}
 				v.allocs--
 				if v.allocs == 0 {
 					v.err = ErrObjectAllocLimit
 					return
 				}
-
 				v.stack[v.sp] = res
 				v.sp++
 			default:
-				v.err = fmt.Errorf("invalid operation: ^%s", operand.TypeName())
+				v.err = fmt.Errorf("invalid operation: ^%s",
+					operand.TypeName())
 				return
 			}
-
-		case compiler.OpMinus:
+		case parser.OpMinus:
 			operand := v.stack[v.sp-1]
 			v.sp--
 
 			switch x := operand.(type) {
-			case *objects.Int:
-				var res objects.Object = &objects.Int{Value: -x.Value}
-
+			case *Int:
+				var res Object = &Int{Value: -x.Value}
 				v.allocs--
 				if v.allocs == 0 {
 					v.err = ErrObjectAllocLimit
 					return
 				}
-
 				v.stack[v.sp] = res
 				v.sp++
-			case *objects.Float:
-				var res objects.Object = &objects.Float{Value: -x.Value}
-
+			case *Float:
+				var res Object = &Float{Value: -x.Value}
 				v.allocs--
 				if v.allocs == 0 {
 					v.err = ErrObjectAllocLimit
 					return
 				}
-
 				v.stack[v.sp] = res
 				v.sp++
 			default:
-				v.err = fmt.Errorf("invalid operation: -%s", operand.TypeName())
+				v.err = fmt.Errorf("invalid operation: -%s",
+					operand.TypeName())
 				return
 			}
-
-		case compiler.OpJumpFalsy:
+		case parser.OpJumpFalsy:
 			v.ip += 2
 			v.sp--
 			if v.stack[v.sp].IsFalsy() {
 				pos := int(v.curInsts[v.ip]) | int(v.curInsts[v.ip-1])<<8
 				v.ip = pos - 1
 			}
-
-		case compiler.OpAndJump:
+		case parser.OpAndJump:
 			v.ip += 2
-
 			if v.stack[v.sp-1].IsFalsy() {
 				pos := int(v.curInsts[v.ip]) | int(v.curInsts[v.ip-1])<<8
 				v.ip = pos - 1
 			} else {
 				v.sp--
 			}
-
-		case compiler.OpOrJump:
+		case parser.OpOrJump:
 			v.ip += 2
-
 			if v.stack[v.sp-1].IsFalsy() {
 				v.sp--
 			} else {
 				pos := int(v.curInsts[v.ip]) | int(v.curInsts[v.ip-1])<<8
 				v.ip = pos - 1
 			}
-
-		case compiler.OpJump:
+		case parser.OpJump:
 			pos := int(v.curInsts[v.ip+2]) | int(v.curInsts[v.ip+1])<<8
 			v.ip = pos - 1
-
-		case compiler.OpSetGlobal:
+		case parser.OpSetGlobal:
 			v.ip += 2
 			v.sp--
-
 			globalIndex := int(v.curInsts[v.ip]) | int(v.curInsts[v.ip-1])<<8
 			v.globals[globalIndex] = v.stack[v.sp]
-
-		case compiler.OpSetSelGlobal:
+		case parser.OpSetSelGlobal:
 			v.ip += 3
 			globalIndex := int(v.curInsts[v.ip-1]) | int(v.curInsts[v.ip-2])<<8
 			numSelectors := int(v.curInsts[v.ip])
 
 			// selectors and RHS value
-			selectors := make([]objects.Object, numSelectors)
+			selectors := make([]Object, numSelectors)
 			for i := 0; i < numSelectors; i++ {
 				selectors[i] = v.stack[v.sp-numSelectors+i]
 			}
-
 			val := v.stack[v.sp-numSelectors-1]
 			v.sp -= numSelectors + 1
-
-			if e := indexAssign(v.globals[globalIndex], val, selectors); e != nil {
+			e := indexAssign(v.globals[globalIndex], val, selectors)
+			if e != nil {
 				v.err = e
 				return
 			}
-
-		case compiler.OpGetGlobal:
+		case parser.OpGetGlobal:
 			v.ip += 2
 			globalIndex := int(v.curInsts[v.ip]) | int(v.curInsts[v.ip-1])<<8
-
 			val := v.globals[globalIndex]
-
 			v.stack[v.sp] = val
 			v.sp++
-
-		case compiler.OpArray:
+		case parser.OpArray:
 			v.ip += 2
 			numElements := int(v.curInsts[v.ip]) | int(v.curInsts[v.ip-1])<<8
 
-			var elements []objects.Object
+			var elements []Object
 			for i := v.sp - numElements; i < v.sp; i++ {
 				elements = append(elements, v.stack[i])
 			}
 			v.sp -= numElements
 
-			var arr objects.Object = &objects.Array{Value: elements}
-
+			var arr Object = &Array{Value: elements}
 			v.allocs--
 			if v.allocs == 0 {
 				v.err = ErrObjectAllocLimit
@@ -347,355 +290,260 @@ func (v *VM) run() {
 
 			v.stack[v.sp] = arr
 			v.sp++
-
-		case compiler.OpMap:
+		case parser.OpMap:
 			v.ip += 2
 			numElements := int(v.curInsts[v.ip]) | int(v.curInsts[v.ip-1])<<8
-
-			kv := make(map[string]objects.Object)
+			kv := make(map[string]Object)
 			for i := v.sp - numElements; i < v.sp; i += 2 {
 				key := v.stack[i]
 				value := v.stack[i+1]
-				kv[key.(*objects.String).Value] = value
+				kv[key.(*String).Value] = value
 			}
 			v.sp -= numElements
 
-			var m objects.Object = &objects.Map{Value: kv}
-
+			var m Object = &Map{Value: kv}
 			v.allocs--
 			if v.allocs == 0 {
 				v.err = ErrObjectAllocLimit
 				return
 			}
-
 			v.stack[v.sp] = m
 			v.sp++
-
-		case compiler.OpError:
+		case parser.OpError:
 			value := v.stack[v.sp-1]
-
-			var e objects.Object = &objects.Error{
+			var e Object = &Error{
 				Value: value,
 			}
-
 			v.allocs--
 			if v.allocs == 0 {
 				v.err = ErrObjectAllocLimit
 				return
 			}
-
 			v.stack[v.sp-1] = e
-
-		case compiler.OpImmutable:
+		case parser.OpImmutable:
 			value := v.stack[v.sp-1]
-
 			switch value := value.(type) {
-			case *objects.Array:
-				var immutableArray objects.Object = &objects.ImmutableArray{
+			case *Array:
+				var immutableArray Object = &ImmutableArray{
 					Value: value.Value,
 				}
-
 				v.allocs--
 				if v.allocs == 0 {
 					v.err = ErrObjectAllocLimit
 					return
 				}
-
 				v.stack[v.sp-1] = immutableArray
-			case *objects.Map:
-				var immutableMap objects.Object = &objects.ImmutableMap{
+			case *Map:
+				var immutableMap Object = &ImmutableMap{
 					Value: value.Value,
 				}
-
 				v.allocs--
 				if v.allocs == 0 {
 					v.err = ErrObjectAllocLimit
 					return
 				}
-
 				v.stack[v.sp-1] = immutableMap
 			}
-
-		case compiler.OpIndex:
+		case parser.OpIndex:
 			index := v.stack[v.sp-1]
 			left := v.stack[v.sp-2]
 			v.sp -= 2
 
-			switch left := left.(type) {
-			case objects.Indexable:
-				val, e := left.IndexGet(index)
-				if e != nil {
-
-					if e == objects.ErrInvalidIndexType {
-						v.err = fmt.Errorf("invalid index type: %s", index.TypeName())
-						return
-					}
-
-					v.err = e
+			val, err := left.IndexGet(index)
+			if err != nil {
+				if err == ErrNotIndexable {
+					v.err = fmt.Errorf("not indexable: %s", index.TypeName())
 					return
 				}
-				if val == nil {
-					val = objects.UndefinedValue
-				}
-
-				v.stack[v.sp] = val
-				v.sp++
-
-			case *objects.Error: // e.value
-				key, ok := index.(*objects.String)
-				if !ok || key.Value != "value" {
-					v.err = fmt.Errorf("invalid index on error")
+				if err == ErrInvalidIndexType {
+					v.err = fmt.Errorf("invalid index type: %s",
+						index.TypeName())
 					return
 				}
-
-				v.stack[v.sp] = left.Value
-				v.sp++
-
-			default:
-				v.err = fmt.Errorf("not indexable: %s", left.TypeName())
+				v.err = err
 				return
 			}
-
-		case compiler.OpSliceIndex:
+			if val == nil {
+				val = UndefinedValue
+			}
+			v.stack[v.sp] = val
+			v.sp++
+		case parser.OpSliceIndex:
 			high := v.stack[v.sp-1]
 			low := v.stack[v.sp-2]
 			left := v.stack[v.sp-3]
 			v.sp -= 3
 
 			var lowIdx int64
-			if low != objects.UndefinedValue {
-				if low, ok := low.(*objects.Int); ok {
+			if low != UndefinedValue {
+				if low, ok := low.(*Int); ok {
 					lowIdx = low.Value
 				} else {
-					v.err = fmt.Errorf("invalid slice index type: %s", low.TypeName())
+					v.err = fmt.Errorf("invalid slice index type: %s",
+						low.TypeName())
 					return
 				}
 			}
 
 			switch left := left.(type) {
-			case *objects.Array:
+			case *Array:
 				numElements := int64(len(left.Value))
 				var highIdx int64
-				if high == objects.UndefinedValue {
+				if high == UndefinedValue {
 					highIdx = numElements
-				} else if high, ok := high.(*objects.Int); ok {
+				} else if high, ok := high.(*Int); ok {
 					highIdx = high.Value
 				} else {
-					v.err = fmt.Errorf("invalid slice index type: %s", high.TypeName())
+					v.err = fmt.Errorf("invalid slice index type: %s",
+						high.TypeName())
 					return
 				}
-
 				if lowIdx > highIdx {
-					v.err = fmt.Errorf("invalid slice index: %d > %d", lowIdx, highIdx)
+					v.err = fmt.Errorf("invalid slice index: %d > %d",
+						lowIdx, highIdx)
 					return
 				}
-
 				if lowIdx < 0 {
 					lowIdx = 0
 				} else if lowIdx > numElements {
 					lowIdx = numElements
 				}
-
 				if highIdx < 0 {
 					highIdx = 0
 				} else if highIdx > numElements {
 					highIdx = numElements
 				}
-
-				var val objects.Object = &objects.Array{Value: left.Value[lowIdx:highIdx]}
-
+				var val Object = &Array{
+					Value: left.Value[lowIdx:highIdx],
+				}
 				v.allocs--
 				if v.allocs == 0 {
 					v.err = ErrObjectAllocLimit
 					return
 				}
-
 				v.stack[v.sp] = val
 				v.sp++
-
-			case *objects.ImmutableArray:
+			case *ImmutableArray:
 				numElements := int64(len(left.Value))
 				var highIdx int64
-				if high == objects.UndefinedValue {
+				if high == UndefinedValue {
 					highIdx = numElements
-				} else if high, ok := high.(*objects.Int); ok {
+				} else if high, ok := high.(*Int); ok {
 					highIdx = high.Value
 				} else {
-					v.err = fmt.Errorf("invalid slice index type: %s", high.TypeName())
+					v.err = fmt.Errorf("invalid slice index type: %s",
+						high.TypeName())
 					return
 				}
-
 				if lowIdx > highIdx {
-					v.err = fmt.Errorf("invalid slice index: %d > %d", lowIdx, highIdx)
+					v.err = fmt.Errorf("invalid slice index: %d > %d",
+						lowIdx, highIdx)
 					return
 				}
-
 				if lowIdx < 0 {
 					lowIdx = 0
 				} else if lowIdx > numElements {
 					lowIdx = numElements
 				}
-
 				if highIdx < 0 {
 					highIdx = 0
 				} else if highIdx > numElements {
 					highIdx = numElements
 				}
-
-				var val objects.Object = &objects.Array{Value: left.Value[lowIdx:highIdx]}
-
+				var val Object = &Array{
+					Value: left.Value[lowIdx:highIdx],
+				}
 				v.allocs--
 				if v.allocs == 0 {
 					v.err = ErrObjectAllocLimit
 					return
 				}
-
 				v.stack[v.sp] = val
 				v.sp++
-
-			case *objects.String:
+			case *String:
 				numElements := int64(len(left.Value))
 				var highIdx int64
-				if high == objects.UndefinedValue {
+				if high == UndefinedValue {
 					highIdx = numElements
-				} else if high, ok := high.(*objects.Int); ok {
+				} else if high, ok := high.(*Int); ok {
 					highIdx = high.Value
 				} else {
-					v.err = fmt.Errorf("invalid slice index type: %s", high.TypeName())
+					v.err = fmt.Errorf("invalid slice index type: %s",
+						high.TypeName())
 					return
 				}
-
 				if lowIdx > highIdx {
-					v.err = fmt.Errorf("invalid slice index: %d > %d", lowIdx, highIdx)
+					v.err = fmt.Errorf("invalid slice index: %d > %d",
+						lowIdx, highIdx)
 					return
 				}
-
 				if lowIdx < 0 {
 					lowIdx = 0
 				} else if lowIdx > numElements {
 					lowIdx = numElements
 				}
-
 				if highIdx < 0 {
 					highIdx = 0
 				} else if highIdx > numElements {
 					highIdx = numElements
 				}
-
-				var val objects.Object = &objects.String{Value: left.Value[lowIdx:highIdx]}
-
+				var val Object = &String{
+					Value: left.Value[lowIdx:highIdx],
+				}
 				v.allocs--
 				if v.allocs == 0 {
 					v.err = ErrObjectAllocLimit
 					return
 				}
-
 				v.stack[v.sp] = val
 				v.sp++
-
-			case *objects.Bytes:
+			case *Bytes:
 				numElements := int64(len(left.Value))
 				var highIdx int64
-				if high == objects.UndefinedValue {
+				if high == UndefinedValue {
 					highIdx = numElements
-				} else if high, ok := high.(*objects.Int); ok {
+				} else if high, ok := high.(*Int); ok {
 					highIdx = high.Value
 				} else {
-					v.err = fmt.Errorf("invalid slice index type: %s", high.TypeName())
+					v.err = fmt.Errorf("invalid slice index type: %s",
+						high.TypeName())
 					return
 				}
-
 				if lowIdx > highIdx {
-					v.err = fmt.Errorf("invalid slice index: %d > %d", lowIdx, highIdx)
+					v.err = fmt.Errorf("invalid slice index: %d > %d",
+						lowIdx, highIdx)
 					return
 				}
-
 				if lowIdx < 0 {
 					lowIdx = 0
 				} else if lowIdx > numElements {
 					lowIdx = numElements
 				}
-
 				if highIdx < 0 {
 					highIdx = 0
 				} else if highIdx > numElements {
 					highIdx = numElements
 				}
-
-				var val objects.Object = &objects.Bytes{Value: left.Value[lowIdx:highIdx]}
-
+				var val Object = &Bytes{
+					Value: left.Value[lowIdx:highIdx],
+				}
 				v.allocs--
 				if v.allocs == 0 {
 					v.err = ErrObjectAllocLimit
 					return
 				}
-
 				v.stack[v.sp] = val
 				v.sp++
 			}
-
-		case compiler.OpCall:
+		case parser.OpCall:
 			numArgs := int(v.curInsts[v.ip+1])
 			v.ip++
-
 			value := v.stack[v.sp-1-numArgs]
-
-			switch callee := value.(type) {
-			case *objects.Closure:
-				if callee.Fn.VarArgs {
-					// if the closure is variadic,
-					// roll up all variadic parameters into an array
-					realArgs := callee.Fn.NumParameters - 1
-					varArgs := numArgs - realArgs
-					if varArgs >= 0 {
-						numArgs = realArgs + 1
-						args := make([]objects.Object, varArgs)
-						spStart := v.sp - varArgs
-						for i := spStart; i < v.sp; i++ {
-							args[i-spStart] = v.stack[i]
-						}
-						v.stack[spStart] = &objects.Array{Value: args}
-						v.sp = spStart + 1
-					}
-				}
-
-				if numArgs != callee.Fn.NumParameters {
-					if callee.Fn.VarArgs {
-						v.err = fmt.Errorf("wrong number of arguments: want>=%d, got=%d",
-							callee.Fn.NumParameters-1, numArgs)
-					} else {
-						v.err = fmt.Errorf("wrong number of arguments: want=%d, got=%d",
-							callee.Fn.NumParameters, numArgs)
-					}
-					return
-				}
-
-				// test if it's tail-call
-				if callee.Fn == v.curFrame.fn { // recursion
-					nextOp := v.curInsts[v.ip+1]
-					if nextOp == compiler.OpReturn ||
-						(nextOp == compiler.OpPop && compiler.OpReturn == v.curInsts[v.ip+2]) {
-						for p := 0; p < numArgs; p++ {
-							v.stack[v.curFrame.basePointer+p] = v.stack[v.sp-numArgs+p]
-						}
-						v.sp -= numArgs + 1
-						v.ip = -1 // reset IP to beginning of the frame
-						continue
-					}
-				}
-
-				// update call frame
-				v.curFrame.ip = v.ip // store current ip before call
-				v.curFrame = &(v.frames[v.framesIndex])
-				v.curFrame.fn = callee.Fn
-				v.curFrame.freeVars = callee.Free
-				v.curFrame.basePointer = v.sp - numArgs
-				v.curInsts = callee.Fn.Instructions
-				v.ip = -1
-				v.framesIndex++
-				v.sp = v.sp - numArgs + callee.Fn.NumLocals
-
-			case *objects.CompiledFunction:
+			if !value.CanCall() {
+				v.err = fmt.Errorf("not callable: %s", value.TypeName())
+				return
+			}
+			if callee, ok := value.(*CompiledFunction); ok {
 				if callee.VarArgs {
 					// if the closure is variadic,
 					// roll up all variadic parameters into an array
@@ -703,22 +551,23 @@ func (v *VM) run() {
 					varArgs := numArgs - realArgs
 					if varArgs >= 0 {
 						numArgs = realArgs + 1
-						args := make([]objects.Object, varArgs)
+						args := make([]Object, varArgs)
 						spStart := v.sp - varArgs
 						for i := spStart; i < v.sp; i++ {
 							args[i-spStart] = v.stack[i]
 						}
-						v.stack[spStart] = &objects.Array{Value: args}
+						v.stack[spStart] = &Array{Value: args}
 						v.sp = spStart + 1
 					}
 				}
-
 				if numArgs != callee.NumParameters {
 					if callee.VarArgs {
-						v.err = fmt.Errorf("wrong number of arguments: want>=%d, got=%d",
+						v.err = fmt.Errorf(
+							"wrong number of arguments: want>=%d, got=%d",
 							callee.NumParameters-1, numArgs)
 					} else {
-						v.err = fmt.Errorf("wrong number of arguments: want=%d, got=%d",
+						v.err = fmt.Errorf(
+							"wrong number of arguments: want=%d, got=%d",
 							callee.NumParameters, numArgs)
 					}
 					return
@@ -727,321 +576,271 @@ func (v *VM) run() {
 				// test if it's tail-call
 				if callee == v.curFrame.fn { // recursion
 					nextOp := v.curInsts[v.ip+1]
-					if nextOp == compiler.OpReturn ||
-						(nextOp == compiler.OpPop && compiler.OpReturn == v.curInsts[v.ip+2]) {
+					if nextOp == parser.OpReturn ||
+						(nextOp == parser.OpPop &&
+							parser.OpReturn == v.curInsts[v.ip+2]) {
 						for p := 0; p < numArgs; p++ {
-							v.stack[v.curFrame.basePointer+p] = v.stack[v.sp-numArgs+p]
+							v.stack[v.curFrame.basePointer+p] =
+								v.stack[v.sp-numArgs+p]
 						}
 						v.sp -= numArgs + 1
 						v.ip = -1 // reset IP to beginning of the frame
 						continue
 					}
 				}
+				if v.framesIndex >= MaxFrames {
+					v.err = ErrStackOverflow
+					return
+				}
 
 				// update call frame
 				v.curFrame.ip = v.ip // store current ip before call
 				v.curFrame = &(v.frames[v.framesIndex])
 				v.curFrame.fn = callee
-				v.curFrame.freeVars = nil
+				v.curFrame.freeVars = callee.Free
 				v.curFrame.basePointer = v.sp - numArgs
 				v.curInsts = callee.Instructions
 				v.ip = -1
 				v.framesIndex++
 				v.sp = v.sp - numArgs + callee.NumLocals
-
-			case objects.Callable:
-				var args []objects.Object
+			} else {
+				var args []Object
 				args = append(args, v.stack[v.sp-numArgs:v.sp]...)
-
-				ret, e := callee.Call(args...)
+				ret, e := value.Call(args...)
 				v.sp -= numArgs + 1
 
 				// runtime error
 				if e != nil {
-					if e == objects.ErrWrongNumArguments {
-						v.err = fmt.Errorf("wrong number of arguments in call to '%s'",
+					if e == ErrWrongNumArguments {
+						v.err = fmt.Errorf(
+							"wrong number of arguments in call to '%s'",
 							value.TypeName())
 						return
 					}
-
-					if e, ok := e.(objects.ErrInvalidArgumentType); ok {
-						v.err = fmt.Errorf("invalid type for argument '%s' in call to '%s': expected %s, found %s",
+					if e, ok := e.(ErrInvalidArgumentType); ok {
+						v.err = fmt.Errorf(
+							"invalid type for argument '%s' in call to '%s': "+
+								"expected %s, found %s",
 							e.Name, value.TypeName(), e.Expected, e.Found)
 						return
 					}
-
 					v.err = e
 					return
 				}
 
 				// nil return -> undefined
 				if ret == nil {
-					ret = objects.UndefinedValue
+					ret = UndefinedValue
 				}
-
 				v.allocs--
 				if v.allocs == 0 {
 					v.err = ErrObjectAllocLimit
 					return
 				}
-
 				v.stack[v.sp] = ret
 				v.sp++
-
-			default:
-				v.err = fmt.Errorf("not callable: %s", callee.TypeName())
-				return
 			}
-
-		case compiler.OpReturn:
+		case parser.OpReturn:
 			v.ip++
-			var retVal objects.Object
+			var retVal Object
 			if int(v.curInsts[v.ip]) == 1 {
 				retVal = v.stack[v.sp-1]
 			} else {
-				retVal = objects.UndefinedValue
+				retVal = UndefinedValue
 			}
 			//v.sp--
-
 			v.framesIndex--
 			v.curFrame = &v.frames[v.framesIndex-1]
 			v.curInsts = v.curFrame.fn.Instructions
 			v.ip = v.curFrame.ip
-
 			//v.sp = lastFrame.basePointer - 1
 			v.sp = v.frames[v.framesIndex].basePointer
-
 			// skip stack overflow check because (newSP) <= (oldSP)
 			v.stack[v.sp-1] = retVal
 			//v.sp++
-
-		case compiler.OpDefineLocal:
+		case parser.OpDefineLocal:
 			v.ip++
 			localIndex := int(v.curInsts[v.ip])
-
 			sp := v.curFrame.basePointer + localIndex
 
 			// local variables can be mutated by other actions
 			// so always store the copy of popped value
 			val := v.stack[v.sp-1]
 			v.sp--
-
 			v.stack[sp] = val
-
-		case compiler.OpSetLocal:
+		case parser.OpSetLocal:
 			localIndex := int(v.curInsts[v.ip+1])
 			v.ip++
-
 			sp := v.curFrame.basePointer + localIndex
 
-			// update pointee of v.stack[sp] instead of replacing the pointer itself.
-			// this is needed because there can be free variables referencing the same local variables.
+			// update pointee of v.stack[sp] instead of replacing the pointer
+			// itself. this is needed because there can be free variables
+			// referencing the same local variables.
 			val := v.stack[v.sp-1]
 			v.sp--
-
-			if obj, ok := v.stack[sp].(*objects.ObjectPtr); ok {
+			if obj, ok := v.stack[sp].(*ObjectPtr); ok {
 				*obj.Value = val
 				val = obj
 			}
 			v.stack[sp] = val // also use a copy of popped value
-
-		case compiler.OpSetSelLocal:
+		case parser.OpSetSelLocal:
 			localIndex := int(v.curInsts[v.ip+1])
 			numSelectors := int(v.curInsts[v.ip+2])
 			v.ip += 2
 
 			// selectors and RHS value
-			selectors := make([]objects.Object, numSelectors)
+			selectors := make([]Object, numSelectors)
 			for i := 0; i < numSelectors; i++ {
 				selectors[i] = v.stack[v.sp-numSelectors+i]
 			}
-
 			val := v.stack[v.sp-numSelectors-1]
 			v.sp -= numSelectors + 1
-
 			dst := v.stack[v.curFrame.basePointer+localIndex]
-			if obj, ok := dst.(*objects.ObjectPtr); ok {
+			if obj, ok := dst.(*ObjectPtr); ok {
 				dst = *obj.Value
 			}
-
 			if e := indexAssign(dst, val, selectors); e != nil {
 				v.err = e
 				return
 			}
-
-		case compiler.OpGetLocal:
+		case parser.OpGetLocal:
 			v.ip++
 			localIndex := int(v.curInsts[v.ip])
-
 			val := v.stack[v.curFrame.basePointer+localIndex]
-
-			if obj, ok := val.(*objects.ObjectPtr); ok {
+			if obj, ok := val.(*ObjectPtr); ok {
 				val = *obj.Value
 			}
-
 			v.stack[v.sp] = val
 			v.sp++
-
-		case compiler.OpGetBuiltin:
+		case parser.OpGetBuiltin:
 			v.ip++
 			builtinIndex := int(v.curInsts[v.ip])
-
-			v.stack[v.sp] = objects.Builtins[builtinIndex]
+			v.stack[v.sp] = builtinFuncs[builtinIndex]
 			v.sp++
-
-		case compiler.OpClosure:
+		case parser.OpClosure:
 			v.ip += 3
 			constIndex := int(v.curInsts[v.ip-1]) | int(v.curInsts[v.ip-2])<<8
 			numFree := int(v.curInsts[v.ip])
-
-			fn, ok := v.constants[constIndex].(*objects.CompiledFunction)
+			fn, ok := v.constants[constIndex].(*CompiledFunction)
 			if !ok {
 				v.err = fmt.Errorf("not function: %s", fn.TypeName())
 				return
 			}
-
-			free := make([]*objects.ObjectPtr, numFree)
+			free := make([]*ObjectPtr, numFree)
 			for i := 0; i < numFree; i++ {
 				switch freeVar := (v.stack[v.sp-numFree+i]).(type) {
-				case *objects.ObjectPtr:
+				case *ObjectPtr:
 					free[i] = freeVar
 				default:
-					free[i] = &objects.ObjectPtr{Value: &v.stack[v.sp-numFree+i]}
+					free[i] = &ObjectPtr{
+						Value: &v.stack[v.sp-numFree+i],
+					}
 				}
 			}
-
 			v.sp -= numFree
-
-			var cl = &objects.Closure{
-				Fn:   fn,
-				Free: free,
+			cl := &CompiledFunction{
+				Instructions:  fn.Instructions,
+				NumLocals:     fn.NumLocals,
+				NumParameters: fn.NumParameters,
+				VarArgs:       fn.VarArgs,
+				Free:          free,
 			}
-
 			v.allocs--
 			if v.allocs == 0 {
 				v.err = ErrObjectAllocLimit
 				return
 			}
-
 			v.stack[v.sp] = cl
 			v.sp++
-
-		case compiler.OpGetFreePtr:
+		case parser.OpGetFreePtr:
 			v.ip++
 			freeIndex := int(v.curInsts[v.ip])
-
 			val := v.curFrame.freeVars[freeIndex]
-
 			v.stack[v.sp] = val
 			v.sp++
-
-		case compiler.OpGetFree:
+		case parser.OpGetFree:
 			v.ip++
 			freeIndex := int(v.curInsts[v.ip])
-
 			val := *v.curFrame.freeVars[freeIndex].Value
-
 			v.stack[v.sp] = val
 			v.sp++
-
-		case compiler.OpSetFree:
+		case parser.OpSetFree:
 			v.ip++
 			freeIndex := int(v.curInsts[v.ip])
-
 			*v.curFrame.freeVars[freeIndex].Value = v.stack[v.sp-1]
-
 			v.sp--
-
-		case compiler.OpGetLocalPtr:
+		case parser.OpGetLocalPtr:
 			v.ip++
 			localIndex := int(v.curInsts[v.ip])
-
 			sp := v.curFrame.basePointer + localIndex
 			val := v.stack[sp]
-
-			var freeVar *objects.ObjectPtr
-			if obj, ok := val.(*objects.ObjectPtr); ok {
+			var freeVar *ObjectPtr
+			if obj, ok := val.(*ObjectPtr); ok {
 				freeVar = obj
 			} else {
-				freeVar = &objects.ObjectPtr{Value: &val}
+				freeVar = &ObjectPtr{Value: &val}
 				v.stack[sp] = freeVar
 			}
-
 			v.stack[v.sp] = freeVar
 			v.sp++
-
-		case compiler.OpSetSelFree:
+		case parser.OpSetSelFree:
 			v.ip += 2
 			freeIndex := int(v.curInsts[v.ip-1])
 			numSelectors := int(v.curInsts[v.ip])
 
 			// selectors and RHS value
-			selectors := make([]objects.Object, numSelectors)
+			selectors := make([]Object, numSelectors)
 			for i := 0; i < numSelectors; i++ {
 				selectors[i] = v.stack[v.sp-numSelectors+i]
 			}
 			val := v.stack[v.sp-numSelectors-1]
 			v.sp -= numSelectors + 1
-
-			if e := indexAssign(*v.curFrame.freeVars[freeIndex].Value, val, selectors); e != nil {
+			e := indexAssign(*v.curFrame.freeVars[freeIndex].Value,
+				val, selectors)
+			if e != nil {
 				v.err = e
 				return
 			}
-
-		case compiler.OpIteratorInit:
-			var iterator objects.Object
-
+		case parser.OpIteratorInit:
+			var iterator Object
 			dst := v.stack[v.sp-1]
 			v.sp--
-
-			iterable, ok := dst.(objects.Iterable)
-			if !ok {
+			if !dst.CanIterate() {
 				v.err = fmt.Errorf("not iterable: %s", dst.TypeName())
 				return
 			}
-
-			iterator = iterable.Iterate()
-
+			iterator = dst.Iterate()
 			v.allocs--
 			if v.allocs == 0 {
 				v.err = ErrObjectAllocLimit
 				return
 			}
-
 			v.stack[v.sp] = iterator
 			v.sp++
-
-		case compiler.OpIteratorNext:
+		case parser.OpIteratorNext:
 			iterator := v.stack[v.sp-1]
 			v.sp--
-
-			hasMore := iterator.(objects.Iterator).Next()
-
+			hasMore := iterator.(Iterator).Next()
 			if hasMore {
-				v.stack[v.sp] = objects.TrueValue
+				v.stack[v.sp] = TrueValue
 			} else {
-				v.stack[v.sp] = objects.FalseValue
+				v.stack[v.sp] = FalseValue
 			}
 			v.sp++
-
-		case compiler.OpIteratorKey:
+		case parser.OpIteratorKey:
 			iterator := v.stack[v.sp-1]
 			v.sp--
-
-			val := iterator.(objects.Iterator).Key()
-
+			val := iterator.(Iterator).Key()
 			v.stack[v.sp] = val
 			v.sp++
-
-		case compiler.OpIteratorValue:
+		case parser.OpIteratorValue:
 			iterator := v.stack[v.sp-1]
 			v.sp--
-
-			val := iterator.(objects.Iterator).Value()
-
+			val := iterator.(Iterator).Value()
 			v.stack[v.sp] = val
 			v.sp++
-
+		case parser.OpSuspend:
+			return
 		default:
 			v.err = fmt.Errorf("unknown opcode: %d", v.curInsts[v.ip])
 			return
@@ -1054,39 +853,31 @@ func (v *VM) IsStackEmpty() bool {
 	return v.sp == 0
 }
 
-func indexAssign(dst, src objects.Object, selectors []objects.Object) error {
+func indexAssign(dst, src Object, selectors []Object) error {
 	numSel := len(selectors)
-
 	for sidx := numSel - 1; sidx > 0; sidx-- {
-		indexable, ok := dst.(objects.Indexable)
-		if !ok {
-			return fmt.Errorf("not indexable: %s", dst.TypeName())
-		}
-
-		next, err := indexable.IndexGet(selectors[sidx])
+		next, err := dst.IndexGet(selectors[sidx])
 		if err != nil {
-			if err == objects.ErrInvalidIndexType {
-				return fmt.Errorf("invalid index type: %s", selectors[sidx].TypeName())
+			if err == ErrNotIndexable {
+				return fmt.Errorf("not indexable: %s", dst.TypeName())
+			}
+			if err == ErrInvalidIndexType {
+				return fmt.Errorf("invalid index type: %s",
+					selectors[sidx].TypeName())
 			}
-
 			return err
 		}
-
 		dst = next
 	}
 
-	indexAssignable, ok := dst.(objects.IndexAssignable)
-	if !ok {
-		return fmt.Errorf("not index-assignable: %s", dst.TypeName())
-	}
-
-	if err := indexAssignable.IndexSet(selectors[0], src); err != nil {
-		if err == objects.ErrInvalidIndexValueType {
+	if err := dst.IndexSet(selectors[0], src); err != nil {
+		if err == ErrNotIndexAssignable {
+			return fmt.Errorf("not index-assignable: %s", dst.TypeName())
+		}
+		if err == ErrInvalidIndexValueType {
 			return fmt.Errorf("invaid index value type: %s", src.TypeName())
 		}
-
 		return err
 	}
-
 	return nil
 }