Update tengo vendor and load the stdlib. Fixes #789 (#792)

21 files changed, 5588 insertions, 0 deletions

diff --git a/vendor/github.com/d5/tengo/stdlib/builtin_modules.go b/vendor/github.com/d5/tengo/stdlib/builtin_modules.go
new file mode 100644
index 00000000..cc2796f9
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/builtin_modules.go
@@ -0,0 +1,14 @@
+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,
+}
diff --git a/vendor/github.com/d5/tengo/stdlib/errors.go b/vendor/github.com/d5/tengo/stdlib/errors.go
new file mode 100644
index 00000000..a2942bb0
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/errors.go
@@ -0,0 +1,11 @@
+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
new file mode 100644
index 00000000..9c75fc33
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/fmt.go
@@ -0,0 +1,116 @@
+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
+	}
+
+	formatArgs := make([]interface{}, numArgs-1, numArgs-1)
+	for idx, arg := range args[1:] {
+		formatArgs[idx] = objects.ToInterface(arg)
+	}
+
+	fmt.Printf(format.Value, formatArgs...)
+
+	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
+	}
+
+	formatArgs := make([]interface{}, numArgs-1, numArgs-1)
+	for idx, arg := range args[1:] {
+		formatArgs[idx] = objects.ToInterface(arg)
+	}
+
+	s := fmt.Sprintf(format.Value, formatArgs...)
+
+	if len(s) > tengo.MaxStringLen {
+		return nil, objects.ErrStringLimit
+	}
+
+	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
new file mode 100644
index 00000000..26c7ddd9
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/func_typedefs.go
@@ -0,0 +1,1125 @@
+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
+	}
+}
+
+// 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
+	}
+}
+
+// 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/gensrcmods.go b/vendor/github.com/d5/tengo/stdlib/gensrcmods.go
new file mode 100644
index 00000000..fada66bd
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/gensrcmods.go
@@ -0,0 +1,53 @@
+// +build ignore
+
+package main
+
+import (
+	"bytes"
+	"io/ioutil"
+	"log"
+	"regexp"
+	"strconv"
+)
+
+var tengoModFileRE = regexp.MustCompile(`^srcmod_(\w+).tengo$`)
+
+func main() {
+	modules := make(map[string]string)
+
+	// enumerate all Tengo module files
+	files, err := ioutil.ReadDir(".")
+	if err != nil {
+		log.Fatal(err)
+	}
+	for _, file := range files {
+		m := tengoModFileRE.FindStringSubmatch(file.Name())
+		if m != nil {
+			modName := m[1]
+
+			src, err := ioutil.ReadFile(file.Name())
+			if err != nil {
+				log.Fatalf("file '%s' read error: %s", file.Name(), err.Error())
+			}
+
+			modules[modName] = string(src)
+		}
+	}
+
+	var out bytes.Buffer
+	out.WriteString(`// Code generated using gensrcmods.go; DO NOT EDIT.
+
+package stdlib
+
+// SourceModules are source type standard library modules.
+var SourceModules = map[string]string{` + "\n")
+	for modName, modSrc := range modules {
+		out.WriteString("\t\"" + modName + "\": " + strconv.Quote(modSrc) + ",\n")
+	}
+	out.WriteString("}\n")
+
+	const target = "source_modules.go"
+	if err := ioutil.WriteFile(target, out.Bytes(), 0644); err != nil {
+		log.Fatal(err)
+	}
+}
diff --git a/vendor/github.com/d5/tengo/stdlib/json.go b/vendor/github.com/d5/tengo/stdlib/json.go
new file mode 100644
index 00000000..f913dc48
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/json.go
@@ -0,0 +1,126 @@
+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/json/decode.go b/vendor/github.com/d5/tengo/stdlib/json/decode.go
new file mode 100644
index 00000000..5a3fe6c7
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/json/decode.go
@@ -0,0 +1,374 @@
+// A modified version of Go's JSON implementation.
+
+// Copyright 2010 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 json
+
+import (
+	"strconv"
+	"unicode"
+	"unicode/utf16"
+	"unicode/utf8"
+
+	"github.com/d5/tengo/objects"
+)
+
+// Decode parses the JSON-encoded data and returns the result object.
+func Decode(data []byte) (objects.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()
+}
+
+// decodeState represents the state while decoding a JSON value.
+type decodeState struct {
+	data   []byte
+	off    int // next read offset in data
+	opcode int // last read result
+	scan   scanner
+}
+
+// readIndex returns the position of the last byte read.
+func (d *decodeState) readIndex() int {
+	return d.off - 1
+}
+
+const phasePanicMsg = "JSON decoder out of sync - data changing underfoot?"
+
+func (d *decodeState) init(data []byte) *decodeState {
+	d.data = data
+	d.off = 0
+	return d
+}
+
+// scanNext processes the byte at d.data[d.off].
+func (d *decodeState) scanNext() {
+	if d.off < len(d.data) {
+		d.opcode = d.scan.step(&d.scan, d.data[d.off])
+		d.off++
+	} else {
+		d.opcode = d.scan.eof()
+		d.off = len(d.data) + 1 // mark processed EOF with len+1
+	}
+}
+
+// scanWhile processes bytes in d.data[d.off:] until it
+// receives a scan code not equal to op.
+func (d *decodeState) scanWhile(op int) {
+	s, data, i := &d.scan, d.data, d.off
+	for i < len(data) {
+		newOp := s.step(s, data[i])
+		i++
+		if newOp != op {
+			d.opcode = newOp
+			d.off = i
+			return
+		}
+	}
+
+	d.off = len(data) + 1 // mark processed EOF with len+1
+	d.opcode = d.scan.eof()
+}
+
+func (d *decodeState) value() (objects.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
+	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
+		}
+		arr = append(arr, o)
+
+		// Next token must be , or ].
+		if d.opcode == scanSkipSpace {
+			d.scanWhile(scanSkipSpace)
+		}
+		if d.opcode == scanEndArray {
+			break
+		}
+		if d.opcode != scanArrayValue {
+			panic(phasePanicMsg)
+		}
+	}
+
+	return &objects.Array{Value: arr}, nil
+}
+
+func (d *decodeState) object() (objects.Object, error) {
+	m := make(map[string]objects.Object)
+	for {
+		// Read opening " of string key or closing }.
+		d.scanWhile(scanSkipSpace)
+		if d.opcode == scanEndObject {
+			// closing } - can only happen on first iteration.
+			break
+		}
+		if d.opcode != scanBeginLiteral {
+			panic(phasePanicMsg)
+		}
+
+		// Read string key.
+		start := d.readIndex()
+		d.scanWhile(scanContinue)
+		item := d.data[start:d.readIndex()]
+		key, ok := unquote(item)
+		if !ok {
+			panic(phasePanicMsg)
+		}
+
+		// Read : before value.
+		if d.opcode == scanSkipSpace {
+			d.scanWhile(scanSkipSpace)
+		}
+		if d.opcode != scanObjectKey {
+			panic(phasePanicMsg)
+		}
+		d.scanWhile(scanSkipSpace)
+
+		// Read value.
+		o, err := d.value()
+		if err != nil {
+			return nil, err
+		}
+
+		m[key] = o
+
+		// Next token must be , or }.
+		if d.opcode == scanSkipSpace {
+			d.scanWhile(scanSkipSpace)
+		}
+		if d.opcode == scanEndObject {
+			break
+		}
+		if d.opcode != scanObjectValue {
+			panic(phasePanicMsg)
+		}
+	}
+
+	return &objects.Map{Value: m}, nil
+}
+
+func (d *decodeState) literal() (objects.Object, error) {
+	// All bytes inside literal return scanContinue op code.
+	start := d.readIndex()
+	d.scanWhile(scanContinue)
+
+	item := d.data[start:d.readIndex()]
+
+	switch c := item[0]; c {
+	case 'n': // null
+		return objects.UndefinedValue, nil
+
+	case 't', 'f': // true, false
+		if c == 't' {
+			return objects.TrueValue, nil
+		}
+		return objects.FalseValue, nil
+
+	case '"': // string
+		s, ok := unquote(item)
+		if !ok {
+			panic(phasePanicMsg)
+		}
+		return &objects.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
+	}
+}
+
+// getu4 decodes \uXXXX from the beginning of s, returning the hex value,
+// or it returns -1.
+func getu4(s []byte) rune {
+	if len(s) < 6 || s[0] != '\\' || s[1] != 'u' {
+		return -1
+	}
+	var r rune
+	for _, c := range s[2:6] {
+		switch {
+		case '0' <= c && c <= '9':
+			c = c - '0'
+		case 'a' <= c && c <= 'f':
+			c = c - 'a' + 10
+		case 'A' <= c && c <= 'F':
+			c = c - 'A' + 10
+		default:
+			return -1
+		}
+		r = r*16 + rune(c)
+	}
+	return r
+}
+
+// unquote converts a quoted JSON string literal s into an actual string t.
+// The rules are different than for Go, so cannot use strconv.Unquote.
+func unquote(s []byte) (t string, ok bool) {
+	s, ok = unquoteBytes(s)
+	t = string(s)
+	return
+}
+
+func unquoteBytes(s []byte) (t []byte, ok bool) {
+	if len(s) < 2 || s[0] != '"' || s[len(s)-1] != '"' {
+		return
+	}
+	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.
+	r := 0
+	for r < len(s) {
+		c := s[r]
+		if c == '\\' || c == '"' || c < ' ' {
+			break
+		}
+		if c < utf8.RuneSelf {
+			r++
+			continue
+		}
+		rr, size := utf8.DecodeRune(s[r:])
+		if rr == utf8.RuneError && size == 1 {
+			break
+		}
+		r += size
+	}
+	if r == len(s) {
+		return s, true
+	}
+
+	b := make([]byte, len(s)+2*utf8.UTFMax)
+	w := copy(b, s[0:r])
+	for r < len(s) {
+		// Out of room? Can only happen if s is full of
+		// malformed UTF-8 and we're replacing each
+		// byte with RuneError.
+		if w >= len(b)-2*utf8.UTFMax {
+			nb := make([]byte, (len(b)+utf8.UTFMax)*2)
+			copy(nb, b[0:w])
+			b = nb
+		}
+		switch c := s[r]; {
+		case c == '\\':
+			r++
+			if r >= len(s) {
+				return
+			}
+			switch s[r] {
+			default:
+				return
+			case '"', '\\', '/', '\'':
+				b[w] = s[r]
+				r++
+				w++
+			case 'b':
+				b[w] = '\b'
+				r++
+				w++
+			case 'f':
+				b[w] = '\f'
+				r++
+				w++
+			case 'n':
+				b[w] = '\n'
+				r++
+				w++
+			case 'r':
+				b[w] = '\r'
+				r++
+				w++
+			case 't':
+				b[w] = '\t'
+				r++
+				w++
+			case 'u':
+				r--
+				rr := getu4(s[r:])
+				if rr < 0 {
+					return
+				}
+				r += 6
+				if utf16.IsSurrogate(rr) {
+					rr1 := getu4(s[r:])
+					if dec := utf16.DecodeRune(rr, rr1); dec != unicode.ReplacementChar {
+						// A valid pair; consume.
+						r += 6
+						w += utf8.EncodeRune(b[w:], dec)
+						break
+					}
+					// Invalid surrogate; fall back to replacement rune.
+					rr = unicode.ReplacementChar
+				}
+				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:])
+			r += size
+			w += utf8.EncodeRune(b[w:], rr)
+		}
+	}
+	return b[0:w], true
+}
diff --git a/vendor/github.com/d5/tengo/stdlib/json/encode.go b/vendor/github.com/d5/tengo/stdlib/json/encode.go
new file mode 100644
index 00000000..2b8b17eb
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/json/encode.go
@@ -0,0 +1,147 @@
+// A modified version of Go's JSON implementation.
+
+// Copyright 2010 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 json
+
+import (
+	"encoding/base64"
+	"errors"
+	"math"
+	"strconv"
+
+	"github.com/d5/tengo/objects"
+)
+
+// Encode returns the JSON encoding of the object.
+func Encode(o objects.Object) ([]byte, error) {
+	var b []byte
+
+	switch o := o.(type) {
+	case *objects.Array:
+		b = append(b, '[')
+		len1 := len(o.Value) - 1
+		for idx, elem := range o.Value {
+			eb, err := Encode(elem)
+			if err != nil {
+				return nil, err
+			}
+			b = append(b, eb...)
+			if idx < len1 {
+				b = append(b, ',')
+			}
+		}
+		b = append(b, ']')
+	case *objects.ImmutableArray:
+		b = append(b, '[')
+		len1 := len(o.Value) - 1
+		for idx, elem := range o.Value {
+			eb, err := Encode(elem)
+			if err != nil {
+				return nil, err
+			}
+			b = append(b, eb...)
+			if idx < len1 {
+				b = append(b, ',')
+			}
+		}
+		b = append(b, ']')
+	case *objects.Map:
+		b = append(b, '{')
+		len1 := len(o.Value) - 1
+		idx := 0
+		for key, value := range o.Value {
+			b = strconv.AppendQuote(b, key)
+			b = append(b, ':')
+			eb, err := Encode(value)
+			if err != nil {
+				return nil, err
+			}
+			b = append(b, eb...)
+			if idx < len1 {
+				b = append(b, ',')
+			}
+			idx++
+		}
+		b = append(b, '}')
+	case *objects.ImmutableMap:
+		b = append(b, '{')
+		len1 := len(o.Value) - 1
+		idx := 0
+		for key, value := range o.Value {
+			b = strconv.AppendQuote(b, key)
+			b = append(b, ':')
+			eb, err := Encode(value)
+			if err != nil {
+				return nil, err
+			}
+			b = append(b, eb...)
+			if idx < len1 {
+				b = append(b, ',')
+			}
+			idx++
+		}
+		b = append(b, '}')
+	case *objects.Bool:
+		if o.IsFalsy() {
+			b = strconv.AppendBool(b, false)
+		} else {
+			b = strconv.AppendBool(b, true)
+		}
+	case *objects.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:
+		b = strconv.AppendInt(b, int64(o.Value), 10)
+	case *objects.Float:
+		var y []byte
+
+		f := o.Value
+		if math.IsInf(f, 0) || math.IsNaN(f) {
+			return nil, errors.New("unsupported float value")
+		}
+
+		// Convert as if by ES6 number to string conversion.
+		// This matches most other JSON generators.
+		abs := math.Abs(f)
+		fmt := byte('f')
+		if abs != 0 {
+			if abs < 1e-6 || abs >= 1e21 {
+				fmt = 'e'
+			}
+		}
+		y = strconv.AppendFloat(y, f, fmt, -1, 64)
+		if fmt == 'e' {
+			// clean up e-09 to e-9
+			n := len(y)
+			if n >= 4 && y[n-4] == 'e' && y[n-3] == '-' && y[n-2] == '0' {
+				y[n-2] = y[n-1]
+				y = y[:n-1]
+			}
+		}
+
+		b = append(b, y...)
+	case *objects.Int:
+		b = strconv.AppendInt(b, o.Value, 10)
+	case *objects.String:
+		b = strconv.AppendQuote(b, o.Value)
+	case *objects.Time:
+		y, err := o.Value.MarshalJSON()
+		if err != nil {
+			return nil, err
+		}
+		b = append(b, y...)
+	case *objects.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/stdlib/json/scanner.go
new file mode 100644
index 00000000..8fc6776d
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/json/scanner.go
@@ -0,0 +1,559 @@
+// A modified version of Go's JSON implementation.
+
+// Copyright 2010 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 json
+
+import "strconv"
+
+func checkValid(data []byte, scan *scanner) error {
+	scan.reset()
+	for _, c := range data {
+		scan.bytes++
+		if scan.step(scan, c) == scanError {
+			return scan.err
+		}
+	}
+	if scan.eof() == scanError {
+		return scan.err
+	}
+	return nil
+}
+
+// A SyntaxError is a description of a JSON syntax error.
+type SyntaxError struct {
+	msg    string // description of error
+	Offset int64  // error occurred after reading Offset bytes
+}
+
+func (e *SyntaxError) Error() string { return e.msg }
+
+// A scanner is a JSON scanning state machine.
+// Callers call scan.reset() and then pass bytes in one at a time
+// by calling scan.step(&scan, c) for each byte.
+// The return value, referred to as an opcode, tells the
+// caller about significant parsing events like beginning
+// and ending literals, objects, and arrays, so that the
+// caller can follow along if it wishes.
+// The return value scanEnd indicates that a single top-level
+// JSON value has been completed, *before* the byte that
+// just got passed in.  (The indication must be delayed in order
+// to recognize the end of numbers: is 123 a whole value or
+// the beginning of 12345e+6?).
+type scanner struct {
+	// The step is a func to be called to execute the next transition.
+	// Also tried using an integer constant and a single func
+	// with a switch, but using the func directly was 10% faster
+	// on a 64-bit Mac Mini, and it's nicer to read.
+	step func(*scanner, byte) int
+
+	// Reached end of top-level value.
+	endTop bool
+
+	// Stack of what we're in the middle of - array values, object keys, object values.
+	parseState []int
+
+	// Error that happened, if any.
+	err error
+
+	// total bytes consumed, updated by decoder.Decode
+	bytes int64
+}
+
+// These values are returned by the state transition functions
+// assigned to scanner.state and the method scanner.eof.
+// They give details about the current state of the scan that
+// callers might be interested to know about.
+// It is okay to ignore the return value of any particular
+// call to scanner.state: if one call returns scanError,
+// every subsequent call will return scanError too.
+const (
+	// Continue.
+	scanContinue     = iota // uninteresting byte
+	scanBeginLiteral        // end implied by next result != scanContinue
+	scanBeginObject         // begin object
+	scanObjectKey           // just finished object key (string)
+	scanObjectValue         // just finished non-last object value
+	scanEndObject           // end object (implies scanObjectValue if possible)
+	scanBeginArray          // begin array
+	scanArrayValue          // just finished array value
+	scanEndArray            // end array (implies scanArrayValue if possible)
+	scanSkipSpace           // space byte; can skip; known to be last "continue" result
+
+	// Stop.
+	scanEnd   // top-level value ended *before* this byte; known to be first "stop" result
+	scanError // hit an error, scanner.err.
+)
+
+// These values are stored in the parseState stack.
+// They give the current state of a composite value
+// being scanned. If the parser is inside a nested value
+// the parseState describes the nested state, outermost at entry 0.
+const (
+	parseObjectKey   = iota // parsing object key (before colon)
+	parseObjectValue        // parsing object value (after colon)
+	parseArrayValue         // parsing array value
+)
+
+// reset prepares the scanner for use.
+// It must be called before calling s.step.
+func (s *scanner) reset() {
+	s.step = stateBeginValue
+	s.parseState = s.parseState[0:0]
+	s.err = nil
+	s.endTop = false
+}
+
+// eof tells the scanner that the end of input has been reached.
+// It returns a scan status just as s.step does.
+func (s *scanner) eof() int {
+	if s.err != nil {
+		return scanError
+	}
+	if s.endTop {
+		return scanEnd
+	}
+	s.step(s, ' ')
+	if s.endTop {
+		return scanEnd
+	}
+	if s.err == nil {
+		s.err = &SyntaxError{"unexpected end of JSON input", s.bytes}
+	}
+	return scanError
+}
+
+// pushParseState pushes a new parse state p onto the parse stack.
+func (s *scanner) pushParseState(p int) {
+	s.parseState = append(s.parseState, p)
+}
+
+// popParseState pops a parse state (already obtained) off the stack
+// and updates s.step accordingly.
+func (s *scanner) popParseState() {
+	n := len(s.parseState) - 1
+	s.parseState = s.parseState[0:n]
+	if n == 0 {
+		s.step = stateEndTop
+		s.endTop = true
+	} else {
+		s.step = stateEndValue
+	}
+}
+
+func isSpace(c byte) bool {
+	return c == ' ' || c == '\t' || c == '\r' || c == '\n'
+}
+
+// stateBeginValueOrEmpty is the state after reading `[`.
+func stateBeginValueOrEmpty(s *scanner, c byte) int {
+	if c <= ' ' && isSpace(c) {
+		return scanSkipSpace
+	}
+	if c == ']' {
+		return stateEndValue(s, c)
+	}
+	return stateBeginValue(s, c)
+}
+
+// stateBeginValue is the state at the beginning of the input.
+func stateBeginValue(s *scanner, c byte) int {
+	if c <= ' ' && isSpace(c) {
+		return scanSkipSpace
+	}
+	switch c {
+	case '{':
+		s.step = stateBeginStringOrEmpty
+		s.pushParseState(parseObjectKey)
+		return scanBeginObject
+	case '[':
+		s.step = stateBeginValueOrEmpty
+		s.pushParseState(parseArrayValue)
+		return scanBeginArray
+	case '"':
+		s.step = stateInString
+		return scanBeginLiteral
+	case '-':
+		s.step = stateNeg
+		return scanBeginLiteral
+	case '0': // beginning of 0.123
+		s.step = state0
+		return scanBeginLiteral
+	case 't': // beginning of true
+		s.step = stateT
+		return scanBeginLiteral
+	case 'f': // beginning of false
+		s.step = stateF
+		return scanBeginLiteral
+	case 'n': // beginning of null
+		s.step = stateN
+		return scanBeginLiteral
+	}
+	if '1' <= c && c <= '9' { // beginning of 1234.5
+		s.step = state1
+		return scanBeginLiteral
+	}
+	return s.error(c, "looking for beginning of value")
+}
+
+// stateBeginStringOrEmpty is the state after reading `{`.
+func stateBeginStringOrEmpty(s *scanner, c byte) int {
+	if c <= ' ' && isSpace(c) {
+		return scanSkipSpace
+	}
+	if c == '}' {
+		n := len(s.parseState)
+		s.parseState[n-1] = parseObjectValue
+		return stateEndValue(s, c)
+	}
+	return stateBeginString(s, c)
+}
+
+// stateBeginString is the state after reading `{"key": value,`.
+func stateBeginString(s *scanner, c byte) int {
+	if c <= ' ' && isSpace(c) {
+		return scanSkipSpace
+	}
+	if c == '"' {
+		s.step = stateInString
+		return scanBeginLiteral
+	}
+	return s.error(c, "looking for beginning of object key string")
+}
+
+// stateEndValue is the state after completing a value,
+// such as after reading `{}` or `true` or `["x"`.
+func stateEndValue(s *scanner, c byte) int {
+	n := len(s.parseState)
+	if n == 0 {
+		// Completed top-level before the current byte.
+		s.step = stateEndTop
+		s.endTop = true
+		return stateEndTop(s, c)
+	}
+	if c <= ' ' && isSpace(c) {
+		s.step = stateEndValue
+		return scanSkipSpace
+	}
+	ps := s.parseState[n-1]
+	switch ps {
+	case parseObjectKey:
+		if c == ':' {
+			s.parseState[n-1] = parseObjectValue
+			s.step = stateBeginValue
+			return scanObjectKey
+		}
+		return s.error(c, "after object key")
+	case parseObjectValue:
+		if c == ',' {
+			s.parseState[n-1] = parseObjectKey
+			s.step = stateBeginString
+			return scanObjectValue
+		}
+		if c == '}' {
+			s.popParseState()
+			return scanEndObject
+		}
+		return s.error(c, "after object key:value pair")
+	case parseArrayValue:
+		if c == ',' {
+			s.step = stateBeginValue
+			return scanArrayValue
+		}
+		if c == ']' {
+			s.popParseState()
+			return scanEndArray
+		}
+		return s.error(c, "after array element")
+	}
+	return s.error(c, "")
+}
+
+// stateEndTop is the state after finishing the top-level value,
+// such as after reading `{}` or `[1,2,3]`.
+// Only space characters should be seen now.
+func stateEndTop(s *scanner, c byte) int {
+	if !isSpace(c) {
+		// Complain about non-space byte on next call.
+		s.error(c, "after top-level value")
+	}
+	return scanEnd
+}
+
+// stateInString is the state after reading `"`.
+func stateInString(s *scanner, c byte) int {
+	if c == '"' {
+		s.step = stateEndValue
+		return scanContinue
+	}
+	if c == '\\' {
+		s.step = stateInStringEsc
+		return scanContinue
+	}
+	if c < 0x20 {
+		return s.error(c, "in string literal")
+	}
+	return scanContinue
+}
+
+// stateInStringEsc is the state after reading `"\` during a quoted string.
+func stateInStringEsc(s *scanner, c byte) int {
+	switch c {
+	case 'b', 'f', 'n', 'r', 't', '\\', '/', '"':
+		s.step = stateInString
+		return scanContinue
+	case 'u':
+		s.step = stateInStringEscU
+		return scanContinue
+	}
+	return s.error(c, "in string escape code")
+}
+
+// stateInStringEscU is the state after reading `"\u` during a quoted string.
+func stateInStringEscU(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
+		s.step = stateInStringEscU1
+		return scanContinue
+	}
+	// numbers
+	return s.error(c, "in \\u hexadecimal character escape")
+}
+
+// stateInStringEscU1 is the state after reading `"\u1` during a quoted string.
+func stateInStringEscU1(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
+		s.step = stateInStringEscU12
+		return scanContinue
+	}
+	// numbers
+	return s.error(c, "in \\u hexadecimal character escape")
+}
+
+// stateInStringEscU12 is the state after reading `"\u12` during a quoted string.
+func stateInStringEscU12(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
+		s.step = stateInStringEscU123
+		return scanContinue
+	}
+	// numbers
+	return s.error(c, "in \\u hexadecimal character escape")
+}
+
+// stateInStringEscU123 is the state after reading `"\u123` during a quoted string.
+func stateInStringEscU123(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
+		s.step = stateInString
+		return scanContinue
+	}
+	// numbers
+	return s.error(c, "in \\u hexadecimal character escape")
+}
+
+// stateNeg is the state after reading `-` during a number.
+func stateNeg(s *scanner, c byte) int {
+	if c == '0' {
+		s.step = state0
+		return scanContinue
+	}
+	if '1' <= c && c <= '9' {
+		s.step = state1
+		return scanContinue
+	}
+	return s.error(c, "in numeric literal")
+}
+
+// state1 is the state after reading a non-zero integer during a number,
+// such as after reading `1` or `100` but not `0`.
+func state1(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' {
+		s.step = state1
+		return scanContinue
+	}
+	return state0(s, c)
+}
+
+// state0 is the state after reading `0` during a number.
+func state0(s *scanner, c byte) int {
+	if c == '.' {
+		s.step = stateDot
+		return scanContinue
+	}
+	if c == 'e' || c == 'E' {
+		s.step = stateE
+		return scanContinue
+	}
+	return stateEndValue(s, c)
+}
+
+// stateDot is the state after reading the integer and decimal point in a number,
+// such as after reading `1.`.
+func stateDot(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' {
+		s.step = stateDot0
+		return scanContinue
+	}
+	return s.error(c, "after decimal point in numeric literal")
+}
+
+// stateDot0 is the state after reading the integer, decimal point, and subsequent
+// digits of a number, such as after reading `3.14`.
+func stateDot0(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' {
+		return scanContinue
+	}
+	if c == 'e' || c == 'E' {
+		s.step = stateE
+		return scanContinue
+	}
+	return stateEndValue(s, c)
+}
+
+// stateE is the state after reading the mantissa and e in a number,
+// such as after reading `314e` or `0.314e`.
+func stateE(s *scanner, c byte) int {
+	if c == '+' || c == '-' {
+		s.step = stateESign
+		return scanContinue
+	}
+	return stateESign(s, c)
+}
+
+// stateESign is the state after reading the mantissa, e, and sign in a number,
+// such as after reading `314e-` or `0.314e+`.
+func stateESign(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' {
+		s.step = stateE0
+		return scanContinue
+	}
+	return s.error(c, "in exponent of numeric literal")
+}
+
+// stateE0 is the state after reading the mantissa, e, optional sign,
+// and at least one digit of the exponent in a number,
+// such as after reading `314e-2` or `0.314e+1` or `3.14e0`.
+func stateE0(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' {
+		return scanContinue
+	}
+	return stateEndValue(s, c)
+}
+
+// stateT is the state after reading `t`.
+func stateT(s *scanner, c byte) int {
+	if c == 'r' {
+		s.step = stateTr
+		return scanContinue
+	}
+	return s.error(c, "in literal true (expecting 'r')")
+}
+
+// stateTr is the state after reading `tr`.
+func stateTr(s *scanner, c byte) int {
+	if c == 'u' {
+		s.step = stateTru
+		return scanContinue
+	}
+	return s.error(c, "in literal true (expecting 'u')")
+}
+
+// stateTru is the state after reading `tru`.
+func stateTru(s *scanner, c byte) int {
+	if c == 'e' {
+		s.step = stateEndValue
+		return scanContinue
+	}
+	return s.error(c, "in literal true (expecting 'e')")
+}
+
+// stateF is the state after reading `f`.
+func stateF(s *scanner, c byte) int {
+	if c == 'a' {
+		s.step = stateFa
+		return scanContinue
+	}
+	return s.error(c, "in literal false (expecting 'a')")
+}
+
+// stateFa is the state after reading `fa`.
+func stateFa(s *scanner, c byte) int {
+	if c == 'l' {
+		s.step = stateFal
+		return scanContinue
+	}
+	return s.error(c, "in literal false (expecting 'l')")
+}
+
+// stateFal is the state after reading `fal`.
+func stateFal(s *scanner, c byte) int {
+	if c == 's' {
+		s.step = stateFals
+		return scanContinue
+	}
+	return s.error(c, "in literal false (expecting 's')")
+}
+
+// stateFals is the state after reading `fals`.
+func stateFals(s *scanner, c byte) int {
+	if c == 'e' {
+		s.step = stateEndValue
+		return scanContinue
+	}
+	return s.error(c, "in literal false (expecting 'e')")
+}
+
+// stateN is the state after reading `n`.
+func stateN(s *scanner, c byte) int {
+	if c == 'u' {
+		s.step = stateNu
+		return scanContinue
+	}
+	return s.error(c, "in literal null (expecting 'u')")
+}
+
+// stateNu is the state after reading `nu`.
+func stateNu(s *scanner, c byte) int {
+	if c == 'l' {
+		s.step = stateNul
+		return scanContinue
+	}
+	return s.error(c, "in literal null (expecting 'l')")
+}
+
+// stateNul is the state after reading `nul`.
+func stateNul(s *scanner, c byte) int {
+	if c == 'l' {
+		s.step = stateEndValue
+		return scanContinue
+	}
+	return s.error(c, "in literal null (expecting 'l')")
+}
+
+// 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 {
+	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}
+	return scanError
+}
+
+// quoteChar formats c as a quoted character literal
+func quoteChar(c byte) string {
+	// special cases - different from quoted strings
+	if c == '\'' {
+		return `'\''`
+	}
+	if c == '"' {
+		return `'"'`
+	}
+
+	// use quoted string with different quotation marks
+	s := strconv.Quote(string(c))
+	return "'" + s[1:len(s)-1] + "'"
+}
diff --git a/vendor/github.com/d5/tengo/stdlib/math.go b/vendor/github.com/d5/tengo/stdlib/math.go
new file mode 100644
index 00000000..08d82bdf
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/math.go
@@ -0,0 +1,74 @@
+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
new file mode 100644
index 00000000..a7890cc1
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/os.go
@@ -0,0 +1,492 @@
+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
new file mode 100644
index 00000000..5274c36a
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/os_exec.go
@@ -0,0 +1,113 @@
+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
new file mode 100644
index 00000000..ee9f625a
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/os_file.go
@@ -0,0 +1,96 @@
+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
new file mode 100644
index 00000000..801ccdef
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/os_process.go
@@ -0,0 +1,62 @@
+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
new file mode 100644
index 00000000..6efe1de8
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/rand.go
@@ -0,0 +1,102 @@
+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/source_modules.go b/vendor/github.com/d5/tengo/stdlib/source_modules.go
new file mode 100644
index 00000000..ca69d7d1
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/source_modules.go
@@ -0,0 +1,8 @@
+// Code generated using gensrcmods.go; DO NOT EDIT.
+
+package stdlib
+
+// SourceModules are source type standard library modules.
+var SourceModules = map[string]string{
+	"enum": "is_enumerable := func(x) {\n  return is_array(x) || is_map(x) || is_immutable_array(x) || is_immutable_map(x)\n}\n\nis_array_like := func(x) {\n  return is_array(x) || is_immutable_array(x)\n}\n\nexport {\n  // all returns true if the given function `fn` evaluates to a truthy value on\n  // all of the items in `x`. It returns undefined if `x` is not enumerable.\n  all: func(x, fn) {\n    if !is_enumerable(x) { return undefined }\n\n    for k, v in x {\n      if !fn(k, v) { return false }\n    }\n\n    return true\n  },\n  // any returns true if the given function `fn` evaluates to a truthy value on\n  // any of the items in `x`. It returns undefined if `x` is not enumerable.\n  any: func(x, fn) {\n    if !is_enumerable(x) { return undefined }\n\n    for k, v in x {\n      if fn(k, v) { return true }\n    }\n\n    return false\n  },\n  // chunk returns an array of elements split into groups the length of size.\n  // If `x` can't be split evenly, the final chunk will be the remaining elements.\n  // It returns undefined if `x` is not array.\n  chunk: func(x, size) {\n    if !is_array_like(x) || !size { return undefined }\n\n    numElements := len(x)\n    if !numElements { return [] }\n\n    res := []\n    idx := 0\n    for idx < numElements {\n      res = append(res, x[idx:idx+size])\n      idx += size\n    }\n\n    return res\n  },\n  // at returns an element at the given index (if `x` is array) or\n  // key (if `x` is map). It returns undefined if `x` is not enumerable.\n  at: func(x, key) {\n    if !is_enumerable(x) { return undefined }\n\n    if is_array_like(x) {\n        if !is_int(key) { return undefined }\n    } else {\n        if !is_string(key) { return undefined }\n    }\n\n    return x[key]\n  },\n  // each iterates over elements of `x` and invokes `fn` for each element. `fn` is\n  // invoked with two arguments: `key` and `value`. `key` is an int index\n  // if `x` is array. `key` is a string key if `x` is map. It does not iterate\n  // and returns undefined if `x` is not enumerable.\n  each: func(x, fn) {\n    if !is_enumerable(x) { return undefined }\n\n    for k, v in x {\n      fn(k, v)\n    }\n  },\n  // filter iterates over elements of `x`, returning an array of all elements `fn`\n  // returns truthy for. `fn` is invoked with two arguments: `key` and `value`.\n  // `key` is an int index if `x` is array. `key` is a string key if `x` is map.\n  // It returns undefined if `x` is not enumerable.\n  filter: func(x, fn) {\n    if !is_array_like(x) { return undefined }\n\n    dst := []\n    for k, v in x {\n      if fn(k, v) { dst = append(dst, v) }\n    }\n\n    return dst\n  },\n  // find iterates over elements of `x`, returning value of the first element `fn`\n  // returns truthy for. `fn` is invoked with two arguments: `key` and `value`.\n  // `key` is an int index if `x` is array. `key` is a string key if `x` is map.\n  // It returns undefined if `x` is not enumerable.\n  find: func(x, fn) {\n    if !is_enumerable(x) { return undefined }\n\n    for k, v in x {\n      if fn(k, v) { return v }\n    }\n  },\n  // find_key iterates over elements of `x`, returning key or index of the first\n  // element `fn` returns truthy for. `fn` is invoked with two arguments: `key`\n  // and `value`. `key` is an int index if `x` is array. `key` is a string key if\n  // `x` is map. It returns undefined if `x` is not enumerable.\n  find_key: func(x, fn) {\n    if !is_enumerable(x) { return undefined }\n\n    for k, v in x {\n      if fn(k, v) { return k }\n    }\n  },\n  // map creates an array of values by running each element in `x` through `fn`.\n  // `fn` is invoked with two arguments: `key` and `value`. `key` is an int index\n  // if `x` is array. `key` is a string key if `x` is map. It returns undefined\n  // if `x` is not enumerable.\n  map: func(x, fn) {\n    if !is_enumerable(x) { return undefined }\n\n    dst := []\n    for k, v in x {\n      dst = append(dst, fn(k, v))\n    }\n\n    return dst\n  },\n  // key returns the first argument.\n  key: func(k, _) { return k },\n  // value returns the second argument.\n  value: func(_, v) { return v }\n}\n",
+}
diff --git a/vendor/github.com/d5/tengo/stdlib/srcmod_enum.tengo b/vendor/github.com/d5/tengo/stdlib/srcmod_enum.tengo
new file mode 100644
index 00000000..7a5ea637
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/srcmod_enum.tengo
@@ -0,0 +1,128 @@
+is_enumerable := func(x) {
+  return is_array(x) || is_map(x) || is_immutable_array(x) || is_immutable_map(x)
+}
+
+is_array_like := func(x) {
+  return is_array(x) || is_immutable_array(x)
+}
+
+export {
+  // all returns true if the given function `fn` evaluates to a truthy value on
+  // all of the items in `x`. It returns undefined if `x` is not enumerable.
+  all: func(x, fn) {
+    if !is_enumerable(x) { return undefined }
+
+    for k, v in x {
+      if !fn(k, v) { return false }
+    }
+
+    return true
+  },
+  // any returns true if the given function `fn` evaluates to a truthy value on
+  // any of the items in `x`. It returns undefined if `x` is not enumerable.
+  any: func(x, fn) {
+    if !is_enumerable(x) { return undefined }
+
+    for k, v in x {
+      if fn(k, v) { return true }
+    }
+
+    return false
+  },
+  // chunk returns an array of elements split into groups the length of size.
+  // If `x` can't be split evenly, the final chunk will be the remaining elements.
+  // It returns undefined if `x` is not array.
+  chunk: func(x, size) {
+    if !is_array_like(x) || !size { return undefined }
+
+    numElements := len(x)
+    if !numElements { return [] }
+
+    res := []
+    idx := 0
+    for idx < numElements {
+      res = append(res, x[idx:idx+size])
+      idx += size
+    }
+
+    return res
+  },
+  // at returns an element at the given index (if `x` is array) or
+  // key (if `x` is map). It returns undefined if `x` is not enumerable.
+  at: func(x, key) {
+    if !is_enumerable(x) { return undefined }
+
+    if is_array_like(x) {
+        if !is_int(key) { return undefined }
+    } else {
+        if !is_string(key) { return undefined }
+    }
+
+    return x[key]
+  },
+  // each iterates over elements of `x` and invokes `fn` for each element. `fn` is
+  // invoked with two arguments: `key` and `value`. `key` is an int index
+  // if `x` is array. `key` is a string key if `x` is map. It does not iterate
+  // and returns undefined if `x` is not enumerable.
+  each: func(x, fn) {
+    if !is_enumerable(x) { return undefined }
+
+    for k, v in x {
+      fn(k, v)
+    }
+  },
+  // filter iterates over elements of `x`, returning an array of all elements `fn`
+  // returns truthy for. `fn` is invoked with two arguments: `key` and `value`.
+  // `key` is an int index if `x` is array. `key` is a string key if `x` is map.
+  // It returns undefined if `x` is not enumerable.
+  filter: func(x, fn) {
+    if !is_array_like(x) { return undefined }
+
+    dst := []
+    for k, v in x {
+      if fn(k, v) { dst = append(dst, v) }
+    }
+
+    return dst
+  },
+  // find iterates over elements of `x`, returning value of the first element `fn`
+  // returns truthy for. `fn` is invoked with two arguments: `key` and `value`.
+  // `key` is an int index if `x` is array. `key` is a string key if `x` is map.
+  // It returns undefined if `x` is not enumerable.
+  find: func(x, fn) {
+    if !is_enumerable(x) { return undefined }
+
+    for k, v in x {
+      if fn(k, v) { return v }
+    }
+  },
+  // find_key iterates over elements of `x`, returning key or index of the first
+  // element `fn` returns truthy for. `fn` is invoked with two arguments: `key`
+  // and `value`. `key` is an int index if `x` is array. `key` is a string key if
+  // `x` is map. It returns undefined if `x` is not enumerable.
+  find_key: func(x, fn) {
+    if !is_enumerable(x) { return undefined }
+
+    for k, v in x {
+      if fn(k, v) { return k }
+    }
+  },
+  // map creates an array of values by running each element in `x` through `fn`.
+  // `fn` is invoked with two arguments: `key` and `value`. `key` is an int index
+  // if `x` is array. `key` is a string key if `x` is map. It returns undefined
+  // if `x` is not enumerable.
+  map: func(x, fn) {
+    if !is_enumerable(x) { return undefined }
+
+    dst := []
+    for k, v in x {
+      dst = append(dst, fn(k, v))
+    }
+
+    return dst
+  },
+  // key returns the first argument.
+  key: func(k, _) { return k },
+  // value returns the second argument.
+  value: func(_, v) { return v }
+}
diff --git a/vendor/github.com/d5/tengo/stdlib/stdlib.go b/vendor/github.com/d5/tengo/stdlib/stdlib.go
new file mode 100644
index 00000000..aad220ee
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/stdlib.go
@@ -0,0 +1,34 @@
+package stdlib
+
+//go:generate go run gensrcmods.go
+
+import "github.com/d5/tengo/objects"
+
+// AllModuleNames returns a list of all default module names.
+func AllModuleNames() []string {
+	var names []string
+	for name := range BuiltinModules {
+		names = append(names, name)
+	}
+	for name := range SourceModules {
+		names = append(names, name)
+	}
+	return names
+}
+
+// GetModuleMap returns the module map that includes all modules
+// for the given module names.
+func GetModuleMap(names ...string) *objects.ModuleMap {
+	modules := objects.NewModuleMap()
+
+	for _, name := range names {
+		if mod := BuiltinModules[name]; mod != nil {
+			modules.AddBuiltinModule(name, mod)
+		}
+		if mod := SourceModules[name]; mod != "" {
+			modules.AddSourceModule(name, []byte(mod))
+		}
+	}
+
+	return modules
+}
diff --git a/vendor/github.com/d5/tengo/stdlib/text.go b/vendor/github.com/d5/tengo/stdlib/text.go
new file mode 100644
index 00000000..9f9770b8
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/text.go
@@ -0,0 +1,737 @@
+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
+	"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
+	"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 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/text_regexp.go b/vendor/github.com/d5/tengo/stdlib/text_regexp.go
new file mode 100644
index 00000000..16f135bf
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/text_regexp.go
@@ -0,0 +1,228 @@
+package stdlib
+
+import (
+	"regexp"
+
+	"github.com/d5/tengo"
+	"github.com/d5/tengo/objects"
+)
+
+func makeTextRegexp(re *regexp.Regexp) *objects.ImmutableMap {
+	return &objects.ImmutableMap{
+		Value: map[string]objects.Object{
+			// match(text) => bool
+			"match": &objects.UserFunction{
+				Value: func(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
+					}
+
+					if re.MatchString(s1) {
+						ret = objects.TrueValue
+					} else {
+						ret = objects.FalseValue
+					}
+
+					return
+				},
+			},
+
+			// 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) {
+					numArgs := len(args)
+					if numArgs != 1 && numArgs != 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
+					}
+
+					if numArgs == 1 {
+						m := re.FindStringSubmatchIndex(s1)
+						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: s1[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
+					}
+
+					i2, ok := objects.ToInt(args[1])
+					if !ok {
+						err = objects.ErrInvalidArgumentType{
+							Name:     "second",
+							Expected: "int(compatible)",
+							Found:    args[1].TypeName(),
+						}
+						return
+					}
+					m := re.FindAllStringSubmatchIndex(s1, i2)
+					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: 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, subMatch)
+					}
+
+					ret = arr
+
+					return
+				},
+			},
+
+			// replace(src, repl) => string
+			"replace": &objects.UserFunction{
+				Value: func(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
+					}
+
+					s, ok := doTextRegexpReplace(re, s1, s2)
+					if !ok {
+						return nil, objects.ErrStringLimit
+					}
+
+					ret = &objects.String{Value: s}
+
+					return
+				},
+			},
+
+			// split(text) 			 => array(string)
+			// split(text, maxCount) => array(string)
+			"split": &objects.UserFunction{
+				Value: func(args ...objects.Object) (ret objects.Object, err error) {
+					numArgs := len(args)
+					if numArgs != 1 && numArgs != 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
+					}
+
+					var i2 = -1
+					if numArgs > 1 {
+						i2, ok = objects.ToInt(args[1])
+						if !ok {
+							err = objects.ErrInvalidArgumentType{
+								Name:     "second",
+								Expected: "int(compatible)",
+								Found:    args[1].TypeName(),
+							}
+							return
+						}
+					}
+
+					arr := &objects.Array{}
+					for _, s := range re.Split(s1, i2) {
+						arr.Value = append(arr.Value, &objects.String{Value: s})
+					}
+
+					ret = arr
+
+					return
+				},
+			},
+		},
+	}
+}
+
+// Size-limit checking implementation of regexp.ReplaceAllString.
+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]
+	}
+	if idx < len(src) {
+		if len(out)+len(src)-idx > tengo.MaxStringLen {
+			return "", false
+		}
+
+		out += src[idx:]
+	}
+
+	return string(out), true
+}
diff --git a/vendor/github.com/d5/tengo/stdlib/times.go b/vendor/github.com/d5/tengo/stdlib/times.go
new file mode 100644
index 00000000..111c877a
--- /dev/null
+++ b/vendor/github.com/d5/tengo/stdlib/times.go
@@ -0,0 +1,989 @@
+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
+}