package tengo
import (
"context"
"fmt"
"path/filepath"
"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
importDir string
}
// 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
}
// SetImportDir sets the initial import directory for script files.
func (s *Script) SetImportDir(dir string) error {
dir, err := filepath.Abs(dir)
if err != nil {
return err
}
s.importDir = dir
return nil
}
// 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)
c.SetImportDir(s.importDir)
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, false)
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
}