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 }