add CommonJS module example

.gitignore

@@ -6,3 +6,4 @@ v8
 *.swp
 .svn
 v8worker.test
+out/

examples/commonjs/README.md

@@ -0,0 +1,11 @@
+CommonJS
+--------
+
+Rudimentary CommonJS module example:
+
+```
+$ go build -o out/commonjs commonjs.go
+$ out/commonjs
+```
+
+See the actual spec [here](http://www.commonjs.org/specs/modules/1.0/).

examples/commonjs/commonjs.go

@@ -0,0 +1,162 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"path"
+	"regexp"
+
+	"github.com/ry/v8worker"
+)
+
+type module struct {
+	Err      error  `json:"err"`
+	Source   string `json:"source"`
+	Id       string `json:"id"`
+	Filename string `json:"filename"`
+	Dirname  string `json:"dirname"`
+	main     bool
+}
+
+func (m *module) load() {
+	filename := jsExtensionRe.ReplaceAllString(m.Id, "") + ".js"
+	if wd, err := os.Getwd(); err == nil {
+		m.Filename = path.Join(wd, filename)
+	} else {
+		m.Err = err
+		return
+	}
+	file, err := ioutil.ReadFile(filename)
+	if err != nil {
+		m.Err = err
+		return
+	}
+	m.Dirname = path.Dir(m.Filename)
+	var b bytes.Buffer
+	if m.main {
+		b.WriteString(fmt.Sprintf(
+			"var main = new NativeModule({ id: '%s', filename: '%s', dirname: '%s' });\n",
+			m.Id, m.Filename, m.Dirname))
+	}
+	b.WriteString("(function (exports, require, module, __filename, __dirname) { ")
+	if m.main {
+		b.WriteString("\nrequire.main = module;")
+	}
+	b.Write(file)
+	if m.main {
+		b.WriteString("\n}")
+		b.WriteString("(main.exports, NativeModule.require, main, main.filename, main.dirname));")
+		b.WriteString("\n$send('exit');") // exit when main returns
+	} else {
+		b.WriteString("\n});")
+	}
+	m.Source = b.String()
+}
+
+// Adapted from node.js source:
+// see https://github.com/nodejs/node/blob/master/src/node.js#L871
+const nativeModule = `
+	'use strict';
+
+	function NativeModule(rawModule) {
+		this.filename = rawModule.filename;
+		this.dirname = rawModule.dirname;
+		this.id = rawModule.id;
+		this.exports = {};
+		this.loaded = false;
+		this._source = rawModule.source;
+	}
+
+	NativeModule.require = function(id) {
+		var rawModule = JSON.parse($sendSync(id));
+		if (rawModule.err) {
+			throw new RangeError(JSON.stringify(rawModule.err));
+		}
+
+		var nativeModule = new NativeModule(rawModule);
+
+		nativeModule.compile();
+
+		return nativeModule.exports;
+	};
+
+	NativeModule.prototype.compile = function() {
+		var fn = eval(this._source);
+		fn(this.exports, NativeModule.require, this, this.filename, this.dirname);
+		this.loaded = true;
+	};
+	`
+
+var (
+	jsExtensionRe = regexp.MustCompile(`\.js$`)
+	jsFile        = flag.String("f", "module-1.js", "js file to run")
+)
+
+func loadMainModule(w *v8worker.Worker, id string) error {
+	m := module{Id: id, main: true}
+	m.load()
+	if m.Err != nil {
+		return m.Err
+	}
+	return w.Load(m.Filename, m.Source)
+}
+
+func runWorker(done <-chan struct{}, scriptFile string) <-chan string {
+	out := make(chan string)
+
+	go func() {
+		worker := v8worker.New(func(msg string) {
+			out <- msg
+		}, func(msg string) string {
+			m := module{Id: msg, main: false}
+			m.load()
+			bytes, _ := json.Marshal(m)
+			return string(bytes)
+		})
+
+		defer func() {
+			close(out)
+			worker.TerminateExecution()
+		}()
+
+		if err := worker.Load("native-module.js", nativeModule); err != nil {
+			log.Println(err)
+			return
+		}
+		if err := loadMainModule(worker, scriptFile); err != nil {
+			log.Println(err)
+			return
+		}
+
+		for {
+			select {
+			case <-done:
+				log.Println("killing worker...")
+				return
+			default:
+			}
+		}
+	}()
+
+	return out
+}
+
+func main() {
+	flag.Parse()
+	done := make(chan struct{})
+	in := runWorker(done, *jsFile)
+
+	for msg := range in {
+		if msg == "exit" {
+			log.Println("got exit message from js...")
+			close(done)
+		} else {
+			log.Printf("message from js: %q\n", msg)
+		}
+	}
+}

examples/commonjs/module-1.js

@@ -0,0 +1,20 @@
+/*global $send*/
+
+'use strict';
+
+$send('module1 __dirname = ' + __dirname);
+$send('module1 __filename = ' + __filename);
+
+var module2 = require('module-2');
+
+for (var i = 0; i < 10; i++) {
+  $send(module2.saySomething(i));
+}
+
+if (require.main === module) {
+  $send("module1 is main");
+}
+
+module2.longRunning(function(msg) {
+  $send(msg);
+});

examples/commonjs/module-2.js

@@ -0,0 +1,23 @@
+/*global $send*/
+
+'use strict';
+
+$send('module2 __dirname = ' + __dirname);
+$send('module2 __filename = ' + __filename);
+
+var words = ['every', 'good', 'bird', 'does', 'fly',
+  'alligators', 'can', 'eat', 'grape', 'burgers'
+];
+
+exports.saySomething = function(index) {
+  return 'module2 says ' + words[index % 10] + '!';
+};
+
+exports.longRunning = function(callback) {
+  for (var i = 0; i < Number.MAX_SAFE_INTEGER; i++) {
+    if (i === Math.floor(Number.MAX_SAFE_INTEGER / 10000000)) {
+      callback('long running job has finished (' + i + ')');
+      return;
+    }
+  }
+};