package jsre
import (
"fmt"
"github.com/obscuren/otto"
"io/ioutil"
"github.com/ethereum/go-ethereum/common"
)
/*
JSRE is a generic JS runtime environment embedding the otto JS interpreter.
It provides some helper functions to
- load code from files
- run code snippets
- require libraries
- bind native go objects
*/
type JSRE struct {
assetPath string
vm *otto.Otto
}
func New(assetPath string) *JSRE {
re := &JSRE{
assetPath,
otto.New(),
}
// load prettyprint func definition
re.vm.Run(pp_js)
re.vm.Set("loadScript", re.loadScript)
return re
}
// Exec(file) loads and runs the contents of a file
// if a relative path is given, the jsre's assetPath is used
func (self *JSRE) Exec(file string) error {
return self.exec(common.AbsolutePath(self.assetPath, file))
}
func (self *JSRE) exec(path string) error {
code, err := ioutil.ReadFile(path)
if err != nil {
return err
}
_, err = self.vm.Run(code)
return err
}
func (self *JSRE) Bind(name string, v interface{}) (err error) {
self.vm.Set(name, v)
return
}
func (self *JSRE) Run(code string) (otto.Value, error) {
return self.vm.Run(code)
}
func (self *JSRE) Get(ns string) (otto.Value, error) {
return self.vm.Get(ns)
}
func (self *JSRE) Set(ns string, v interface{}) error {
return self.vm.Set(ns, v)
}
func (self *JSRE) loadScript(call otto.FunctionCall) otto.Value {
file, err := call.Argument(0).ToString()
if err != nil {
return otto.FalseValue()
}
if err := self.Exec(file); err != nil {
fmt.Println("err:", err)
return otto.FalseValue()
}
return otto.TrueValue()
}
func (self *JSRE) PrettyPrint(v interface{}) (val otto.Value, err error) {
var method otto.Value
v, err = self.vm.ToValue(v)
if err != nil {
return
}
method, err = self.vm.Get("prettyPrint")
if err != nil {
return
}
return method.Call(method, v)
}
func (self *JSRE) ToVal(v interface{}) otto.Value {
result, err := self.vm.ToValue(v)
if err != nil {
fmt.Println("Value unknown:", err)
return otto.UndefinedValue()
}
return result
}
func (self *JSRE) Eval(code string) (s string, err error) {
var val otto.Value
val, err = self.Run(code)
if err != nil {
return
}
val, err = self.PrettyPrint(val)
if err != nil {
return
}
return fmt.Sprintf("%v", val), nil
}
