tzzzoz/monkey

SpiderMonkey wrapper for Go

What is

This package is SpiderMonkey wrapper for Go.

You can use this package to embed JavaScript into your Go program.

This package just newborn, use in production enviroment at your own risk!

Why make

You can found "go-v8" or "gomonkey" project on the github.

Thy have same purpose: Embed JavaScript into Golang program, make it more dynamic.

But I found all of existing projects are not powerful enough.

For example "go-v8" use JSON to pass data between Go and JavaScript, each callback has a significant performance cost.

So I make one by myself.

Install

You need install SpiderMonkey first.

Mac OS X:

brew install spidermonkey

Ubuntu:

sudo apt-get install libmozjs185-dev

Or compile by yourself (reference).

And then install Monkey by "go get" command.

go get github.com/realint/monkey

Examples

All the example codes can be found in "examples" folder.

You can run all of the example codes like this:

go run examples/hello_world.go

The "hello_world.go" shows what Monkey can do.

package main

import "fmt"
import js "github.com/realint/monkey"

func main() {
	// Create Script Runtime
	runtime, err1 := js.NewRuntime()
	if err1 != nil {
		panic(err1)
	}

	// Evaluate Script
	if value, err := runtime.Eval("'Hello ' + 'World!'"); err == nil {
		println(value.ToString())
	}

	// Built-in Function
	runtime.Eval("println('Hello Built-in Function!')")

	// Compile Once, Run Many Times
	if script, err := runtime.Compile(
		"println('Hello Compiler!')",
		"<no name>", 0,
	); err == nil {
		script.Execute()
		script.Execute()
		script.Execute()
	}

	// Define Function
	if err := runtime.DefineFunction("add",
		func(argv []js.Value) (js.Value, bool) {
			if len(argv) != 2 {
				return runtime.Null(), false
			}
			return runtime.Int(argv[0].Int() + argv[1].Int()), true
		},
	); err == nil {
		if value, err := runtime.Eval("add(100, 200)"); err == nil {
			println(value.Int())
		}
	}

	// Error Handle
	runtime.SetErrorReporter(func(report *js.ErrorReport) {
		println(fmt.Sprintf(
			"%s:%d: %s",
			report.FileName, report.LineNum, report.Message,
		))
		if report.LineBuf != "" {
			println("\t", report.LineBuf)
		}
	})

	// Trigger An Error
	runtime.Eval("abc()")

	// Say Good Bye
	runtime.Dispose()
}

This code will output:

Hello World!
Hello Built-in Function!
Hello Compiler!
Hello Compiler!
Hello Compiler!
300
Eval():0: ReferenceError: abc is not defined

The "op_value.go" shows how to convert JS value to Go value.

package main

import js "github.com/realint/monkey"

func assert(c bool) bool {
	if !c {
		panic("assert failed")
	}
	return c
}

func main() {
	// Create Script Runtime
	runtime, err1 := js.NewRuntime()
	if err1 != nil {
		panic(err1)
	}

	// String
	if value, err := runtime.Eval("'abc'"); assert(err == nil) {
		assert(value.IsString())
		assert(value.String() == "abc")
	}

	// Int
	if value, err := runtime.Eval("123456789"); assert(err == nil) {
		assert(value.IsInt())
		assert(value.Int() == 123456789)
	}

	// Number
	if value, err := runtime.Eval("12345.6789"); assert(err == nil) {
		assert(value.IsNumber())
		assert(value.Number() == 12345.6789)
	}

	runtime.Dispose()
}

The "op_object.go" shows how to play with JS object.

package main

import js "github.com/realint/monkey"

func assert(c bool) bool {
	if !c {
		panic("assert failed")
	}
	return c
}

func main() {
	// Create Script Runtime
	runtime, err1 := js.NewRuntime()
	if err1 != nil {
		panic(err1)
	}

	// Return Object From JavaScript
	if value, err := runtime.Eval("x={a:123}"); assert(err == nil) {
		// Type Check
		assert(value.IsObject())
		obj := value.Object()

		// Get Property
		value1, ok1 := obj.GetProperty("a")
		assert(ok1)
		assert(value1.IsInt())
		assert(value1.Int() == 123)

		// Set Property
		assert(obj.SetProperty("b", runtime.Int(456)))
		value2, ok2 := obj.GetProperty("b")
		assert(ok2)
		assert(value2.IsInt())
		assert(value2.Int() == 456)
	}

	// Return Object From Go
	if err := runtime.DefineFunction("get_data",
		func(argv []js.Value) (js.Value, bool) {
			obj := runtime.NewObject()
			obj.SetProperty("abc", runtime.Int(100))
			obj.SetProperty("def", runtime.Int(200))
			return obj.ToValue(), true
		},
	); err == nil {
		if value, err := runtime.Eval("get_data()"); assert(err == nil) {
			// Type Check
			assert(value.IsObject())
			obj := value.Object()

			// Get Property 'abc'
			value1, ok1 := obj.GetProperty("abc")
			assert(ok1)
			assert(value1.IsInt())
			assert(value1.Int() == 100)

			// Get Property 'def'
			value2, ok2 := obj.GetProperty("def")
			assert(ok2)
			assert(value2.IsInt())
			assert(value2.Int() == 200)
		}
	}

	runtime.Dispose()
}

The "op_array.go" shows how to play with JS array.

package main

import js "github.com/realint/monkey"

func assert(c bool) bool {
	if !c {
		panic("assert failed")
	}
	return c
}

func main() {
	// Create Script Runtime
	runtime, err1 := js.NewRuntime()
	if err1 != nil {
		panic(err1)
	}

	// Return Array From JavaScript
	if value, err := runtime.Eval("[123, 456]"); assert(err == nil) {
		// Type Check
		assert(value.IsObject())
		obj := value.Object()
		assert(obj.IsArray())
		assert(obj.GetArrayLength() == 2)

		// Get First Item
		value1, ok1 := obj.GetElement(0)
		assert(ok1)
		assert(value1.IsInt())
		assert(value1.Int() == 123)

		// Get Second Item
		value2, ok2 := obj.GetElement(1)
		assert(ok2)
		assert(value2.IsInt())
		assert(value2.Int() == 456)

		// Set First Item
		assert(obj.SetElement(0, runtime.Int(789)))
		value3, ok3 := obj.GetElement(0)
		assert(ok3)
		assert(value3.IsInt())
		assert(value3.Int() == 789)

		// Grows
		assert(obj.SetArrayLength(3))
		assert(obj.GetArrayLength() == 3)
	}

	// Return Array From Go
	if err := runtime.DefineFunction("get_data",
		func(argv []js.Value) (js.Value, bool) {
			array := runtime.NewArray()
			array.SetElement(0, runtime.Int(100))
			array.SetElement(1, runtime.Int(200))
			return array.ToValue(), true
		},
	); err == nil {
		if value, err := runtime.Eval("get_data()"); assert(err == nil) {
			// Type Check
			assert(value.IsObject())
			obj := value.Object()
			assert(obj.IsArray())
			assert(obj.GetArrayLength() == 2)

			// Get First Item
			value1, ok1 := obj.GetElement(0)
			assert(ok1)
			assert(value1.IsInt())
			assert(value1.Int() == 100)

			// Get Second Item
			value2, ok2 := obj.GetElement(1)
			assert(ok2)
			assert(value2.IsInt())
			assert(value2.Int() == 200)
		}
	}

	runtime.Dispose()
}

The "op_func.go" shows how to play with JS function value.

package main

import js "github.com/realint/monkey"

func assert(c bool) bool {
	if !c {
		panic("assert failed")
	}
	return c
}

func main() {
	// Create Script Runtime
	runtime, err1 := js.NewRuntime()
	if err1 != nil {
		panic(err1)
	}

	// Function
	if value, err := runtime.Eval("function(a,b){ return a+b; }"); assert(err == nil) {
		// Type Check
		assert(value.IsFunction())

		// Call
		value1, ok1 := value.Call([]js.Value{
			runtime.Int(10),
			runtime.Int(20),
		})

		// Result Check
		assert(ok1)
		assert(value1.IsNumber())
		assert(value1.Int() == 30)
	}

	runtime.Dispose()
}

The "many_many.go" shows Monkey is thread safe.

package main

import "sync"
import "runtime"
import js "github.com/realint/monkey"

func main() {
	runtime.GOMAXPROCS(20)

	// Create Script Runtime
	runtime, err1 := js.NewRuntime()
	if err1 != nil {
		panic(err1)
	}

	wg := new(sync.WaitGroup)

	// One Runtime Instance Used By Many Goroutines
	for i := 0; i < 100; i++ {
		wg.Add(1)
		go func() {
			for j := 0; j < 1000; j++ {
				runtime.Eval("println('Hello World!')")
			}
			wg.Done()
		}()
	}

	wg.Wait()

	// Say Good Bye
	runtime.Dispose()
}