Update to tengo v2 (#976)

1 files changed, 313 insertions, 0 deletions

diff --git a/vendor/github.com/d5/tengo/v2/script.go b/vendor/github.com/d5/tengo/v2/script.go
new file mode 100644
index 00000000..906771d9
--- /dev/null
+++ b/vendor/github.com/d5/tengo/v2/script.go
@@ -0,0 +1,313 @@
+package tengo
+
+import (
+	"context"
+	"fmt"
+	"sync"
+
+	"github.com/d5/tengo/v2/parser"
+)
+
+// Script can simplify compilation and execution of embedded scripts.
+type Script struct {
+	variables        map[string]*Variable
+	modules          *ModuleMap
+	input            []byte
+	maxAllocs        int64
+	maxConstObjects  int
+	enableFileImport bool
+}
+
+// NewScript creates a Script instance with an input script.
+func NewScript(input []byte) *Script {
+	return &Script{
+		variables:       make(map[string]*Variable),
+		input:           input,
+		maxAllocs:       -1,
+		maxConstObjects: -1,
+	}
+}
+
+// Add adds a new variable or updates an existing variable to the script.
+func (s *Script) Add(name string, value interface{}) error {
+	obj, err := FromInterface(value)
+	if err != nil {
+		return err
+	}
+	s.variables[name] = &Variable{
+		name:  name,
+		value: obj,
+	}
+	return nil
+}
+
+// Remove removes (undefines) an existing variable for the script. It returns
+// false if the variable name is not defined.
+func (s *Script) Remove(name string) bool {
+	if _, ok := s.variables[name]; !ok {
+		return false
+	}
+	delete(s.variables, name)
+	return true
+}
+
+// SetImports sets import modules.
+func (s *Script) SetImports(modules *ModuleMap) {
+	s.modules = modules
+}
+
+// SetMaxAllocs sets the maximum number of objects allocations during the run
+// time. Compiled script will return ErrObjectAllocLimit error if it
+// exceeds this limit.
+func (s *Script) SetMaxAllocs(n int64) {
+	s.maxAllocs = n
+}
+
+// SetMaxConstObjects sets the maximum number of objects in the compiled
+// constants.
+func (s *Script) SetMaxConstObjects(n int) {
+	s.maxConstObjects = n
+}
+
+// EnableFileImport enables or disables module loading from local files. Local
+// file modules are disabled by default.
+func (s *Script) EnableFileImport(enable bool) {
+	s.enableFileImport = enable
+}
+
+// Compile compiles the script with all the defined variables, and, returns
+// Compiled object.
+func (s *Script) Compile() (*Compiled, error) {
+	symbolTable, globals, err := s.prepCompile()
+	if err != nil {
+		return nil, err
+	}
+
+	fileSet := parser.NewFileSet()
+	srcFile := fileSet.AddFile("(main)", -1, len(s.input))
+	p := parser.NewParser(srcFile, s.input, nil)
+	file, err := p.ParseFile()
+	if err != nil {
+		return nil, err
+	}
+
+	c := NewCompiler(srcFile, symbolTable, nil, s.modules, nil)
+	c.EnableFileImport(s.enableFileImport)
+	if err := c.Compile(file); err != nil {
+		return nil, err
+	}
+
+	// reduce globals size
+	globals = globals[:symbolTable.MaxSymbols()+1]
+
+	// global symbol names to indexes
+	globalIndexes := make(map[string]int, len(globals))
+	for _, name := range symbolTable.Names() {
+		symbol, _, _ := symbolTable.Resolve(name)
+		if symbol.Scope == ScopeGlobal {
+			globalIndexes[name] = symbol.Index
+		}
+	}
+
+	// remove duplicates from constants
+	bytecode := c.Bytecode()
+	bytecode.RemoveDuplicates()
+
+	// check the constant objects limit
+	if s.maxConstObjects >= 0 {
+		cnt := bytecode.CountObjects()
+		if cnt > s.maxConstObjects {
+			return nil, fmt.Errorf("exceeding constant objects limit: %d", cnt)
+		}
+	}
+	return &Compiled{
+		globalIndexes: globalIndexes,
+		bytecode:      bytecode,
+		globals:       globals,
+		maxAllocs:     s.maxAllocs,
+	}, nil
+}
+
+// Run compiles and runs the scripts. Use returned compiled object to access
+// global variables.
+func (s *Script) Run() (compiled *Compiled, err error) {
+	compiled, err = s.Compile()
+	if err != nil {
+		return
+	}
+	err = compiled.Run()
+	return
+}
+
+// RunContext is like Run but includes a context.
+func (s *Script) RunContext(
+	ctx context.Context,
+) (compiled *Compiled, err error) {
+	compiled, err = s.Compile()
+	if err != nil {
+		return
+	}
+	err = compiled.RunContext(ctx)
+	return
+}
+
+func (s *Script) prepCompile() (
+	symbolTable *SymbolTable,
+	globals []Object,
+	err error,
+) {
+	var names []string
+	for name := range s.variables {
+		names = append(names, name)
+	}
+
+	symbolTable = NewSymbolTable()
+	for idx, fn := range builtinFuncs {
+		symbolTable.DefineBuiltin(idx, fn.Name)
+	}
+
+	globals = make([]Object, GlobalsSize)
+
+	for idx, name := range names {
+		symbol := symbolTable.Define(name)
+		if symbol.Index != idx {
+			panic(fmt.Errorf("wrong symbol index: %d != %d",
+				idx, symbol.Index))
+		}
+		globals[symbol.Index] = s.variables[name].value
+	}
+	return
+}
+
+// Compiled is a compiled instance of the user script. Use Script.Compile() to
+// create Compiled object.
+type Compiled struct {
+	globalIndexes map[string]int // global symbol name to index
+	bytecode      *Bytecode
+	globals       []Object
+	maxAllocs     int64
+	lock          sync.RWMutex
+}
+
+// Run executes the compiled script in the virtual machine.
+func (c *Compiled) Run() error {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	v := NewVM(c.bytecode, c.globals, c.maxAllocs)
+	return v.Run()
+}
+
+// RunContext is like Run but includes a context.
+func (c *Compiled) RunContext(ctx context.Context) (err error) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	v := NewVM(c.bytecode, c.globals, c.maxAllocs)
+	ch := make(chan error, 1)
+	go func() {
+		ch <- v.Run()
+	}()
+
+	select {
+	case <-ctx.Done():
+		v.Abort()
+		<-ch
+		err = ctx.Err()
+	case err = <-ch:
+	}
+	return
+}
+
+// Clone creates a new copy of Compiled. Cloned copies are safe for concurrent
+// use by multiple goroutines.
+func (c *Compiled) Clone() *Compiled {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	clone := &Compiled{
+		globalIndexes: c.globalIndexes,
+		bytecode:      c.bytecode,
+		globals:       make([]Object, len(c.globals)),
+		maxAllocs:     c.maxAllocs,
+	}
+	// copy global objects
+	for idx, g := range c.globals {
+		if g != nil {
+			clone.globals[idx] = g
+		}
+	}
+	return clone
+}
+
+// IsDefined returns true if the variable name is defined (has value) before or
+// after the execution.
+func (c *Compiled) IsDefined(name string) bool {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+
+	idx, ok := c.globalIndexes[name]
+	if !ok {
+		return false
+	}
+	v := c.globals[idx]
+	if v == nil {
+		return false
+	}
+	return v != UndefinedValue
+}
+
+// Get returns a variable identified by the name.
+func (c *Compiled) Get(name string) *Variable {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+
+	value := UndefinedValue
+	if idx, ok := c.globalIndexes[name]; ok {
+		value = c.globals[idx]
+		if value == nil {
+			value = UndefinedValue
+		}
+	}
+	return &Variable{
+		name:  name,
+		value: value,
+	}
+}
+
+// GetAll returns all the variables that are defined by the compiled script.
+func (c *Compiled) GetAll() []*Variable {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+
+	var vars []*Variable
+	for name, idx := range c.globalIndexes {
+		value := c.globals[idx]
+		if value == nil {
+			value = UndefinedValue
+		}
+		vars = append(vars, &Variable{
+			name:  name,
+			value: value,
+		})
+	}
+	return vars
+}
+
+// Set replaces the value of a global variable identified by the name. An error
+// will be returned if the name was not defined during compilation.
+func (c *Compiled) Set(name string, value interface{}) error {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	obj, err := FromInterface(value)
+	if err != nil {
+		return err
+	}
+	idx, ok := c.globalIndexes[name]
+	if !ok {
+		return fmt.Errorf("'%s' is not defined", name)
+	}
+	c.globals[idx] = obj
+	return nil
+}