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matterbridge/vendor/github.com/d5/tengo/script/script.go

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package script
import (
"context"
"fmt"
"github.com/d5/tengo/compiler"
"github.com/d5/tengo/compiler/parser"
"github.com/d5/tengo/compiler/source"
"github.com/d5/tengo/objects"
"github.com/d5/tengo/runtime"
)
// Script can simplify compilation and execution of embedded scripts.
type Script struct {
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variables map[string]*Variable
modules *objects.ModuleMap
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input []byte
maxAllocs int64
maxConstObjects int
enableFileImport bool
}
// New creates a Script instance with an input script.
func New(input []byte) *Script {
return &Script{
variables: make(map[string]*Variable),
input: input,
maxAllocs: -1,
maxConstObjects: -1,
}
}
// Add adds a new variable or updates an existing variable to the script.
func (s *Script) Add(name string, value interface{}) error {
obj, err := objects.FromInterface(value)
if err != nil {
return err
}
s.variables[name] = &Variable{
name: name,
value: obj,
}
return nil
}
// Remove removes (undefines) an existing variable for the script.
// It returns false if the variable name is not defined.
func (s *Script) Remove(name string) bool {
if _, ok := s.variables[name]; !ok {
return false
}
delete(s.variables, name)
return true
}
// SetImports sets import modules.
func (s *Script) SetImports(modules *objects.ModuleMap) {
s.modules = modules
}
// SetMaxAllocs sets the maximum number of objects allocations during the run time.
// Compiled script will return runtime.ErrObjectAllocLimit error if it exceeds this limit.
func (s *Script) SetMaxAllocs(n int64) {
s.maxAllocs = n
}
// SetMaxConstObjects sets the maximum number of objects in the compiled constants.
func (s *Script) SetMaxConstObjects(n int) {
s.maxConstObjects = n
}
// EnableFileImport enables or disables module loading from local files.
// Local file modules are disabled by default.
func (s *Script) EnableFileImport(enable bool) {
s.enableFileImport = enable
}
// Compile compiles the script with all the defined variables, and, returns Compiled object.
func (s *Script) Compile() (*Compiled, error) {
symbolTable, globals, err := s.prepCompile()
if err != nil {
return nil, err
}
fileSet := source.NewFileSet()
srcFile := fileSet.AddFile("(main)", -1, len(s.input))
p := parser.NewParser(srcFile, s.input, nil)
file, err := p.ParseFile()
if err != nil {
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return nil, err
}
c := compiler.NewCompiler(srcFile, symbolTable, nil, s.modules, nil)
c.EnableFileImport(s.enableFileImport)
if err := c.Compile(file); err != nil {
return nil, err
}
// reduce globals size
globals = globals[:symbolTable.MaxSymbols()+1]
// global symbol names to indexes
globalIndexes := make(map[string]int, len(globals))
for _, name := range symbolTable.Names() {
symbol, _, _ := symbolTable.Resolve(name)
if symbol.Scope == compiler.ScopeGlobal {
globalIndexes[name] = symbol.Index
}
}
// remove duplicates from constants
bytecode := c.Bytecode()
bytecode.RemoveDuplicates()
// check the constant objects limit
if s.maxConstObjects >= 0 {
cnt := bytecode.CountObjects()
if cnt > s.maxConstObjects {
return nil, fmt.Errorf("exceeding constant objects limit: %d", cnt)
}
}
return &Compiled{
globalIndexes: globalIndexes,
bytecode: bytecode,
globals: globals,
maxAllocs: s.maxAllocs,
}, nil
}
// Run compiles and runs the scripts.
// Use returned compiled object to access global variables.
func (s *Script) Run() (compiled *Compiled, err error) {
compiled, err = s.Compile()
if err != nil {
return
}
err = compiled.Run()
return
}
// RunContext is like Run but includes a context.
func (s *Script) RunContext(ctx context.Context) (compiled *Compiled, err error) {
compiled, err = s.Compile()
if err != nil {
return
}
err = compiled.RunContext(ctx)
return
}
func (s *Script) prepCompile() (symbolTable *compiler.SymbolTable, globals []objects.Object, err error) {
var names []string
for name := range s.variables {
names = append(names, name)
}
symbolTable = compiler.NewSymbolTable()
for idx, fn := range objects.Builtins {
symbolTable.DefineBuiltin(idx, fn.Name)
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}
globals = make([]objects.Object, runtime.GlobalsSize)
for idx, name := range names {
symbol := symbolTable.Define(name)
if symbol.Index != idx {
panic(fmt.Errorf("wrong symbol index: %d != %d", idx, symbol.Index))
}
globals[symbol.Index] = s.variables[name].value
}
return
}