RFC: introduce dart:js

sdk/lib/js/dart2js/js_dart2js.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library dart.js;
+
+import 'dart:_foreign_helper' show JS;
+import 'dart:_js_helper' show convertDartClosureToJS;
+
+JsObject get context {
+  return new JsObject._fromJs(JS('=Object', 'window'));
+}
+
+JsObject jsify(dynamic data) => data == null ? null : new JsObject._json(data);
+
+class Callback implements Serializable<JsFunction> {
+  final Function _f; // here to allow capture in closure
+  final bool _withThis; // here to allow capture in closure
+  dynamic _jsFunction;
+
+  Callback._(this._f, this._withThis) {
+    _jsFunction = JS('=Object', r'''
+(function(){
+  var f = #;
+  return function(){
+    return f(this, Array.prototype.slice.apply(arguments));
+  };
+}).apply(this)''', convertDartClosureToJS(_call, 2));
+  }
+
+  factory Callback(Function f) => new Callback._(f, false);
+  factory Callback.withThis(Function f) => new Callback._(f, true);
+
+  _call(thisArg, List args) {
+    final arguments = new List.from(args);
+    if (_withThis) arguments.insert(0, thisArg);
+    final dartArgs = arguments.map(_convertToDart).toList();
+    return _convertToJS(Function.apply(_f, dartArgs));
+  }
+
+  JsFunction toJs() => new JsFunction._fromJs(_jsFunction);
+}
+
+class JsObject implements Serializable<JsObject> {
+  final dynamic _jsObject;
+
+  JsObject._fromJs(this._jsObject);
+
+  factory JsObject(Serializable<JsFunction> constructor, [List arguments]) {
+    final constr = _convertToJS(constructor);
+    if (arguments == null) {
+      return new JsObject._fromJs(JS('=Object', 'new #()', constr));
+    }
+    final args = arguments.map(_convertToJS).toList();
+    switch (args.length) {
+      case 0:
+        return new JsObject._fromJs(JS('=Object', 'new #()', constr));
+      case 1:
+        return new JsObject._fromJs(JS('=Object', 'new #(#)', constr, args[0]));
+      case 2:
+        return new JsObject._fromJs(JS('=Object', 'new #(#,#)', constr, args[0],
+            args[1]));
+      case 3:
+        return new JsObject._fromJs(JS('=Object', 'new #(#,#,#)', constr,
+            args[0], args[1], args[2]));
+      case 4:
+        return new JsObject._fromJs(JS('=Object', 'new #(#,#,#,#)', constr,
+            args[0], args[1], args[2], args[3]));
+      case 5:
+        return new JsObject._fromJs(JS('=Object', 'new #(#,#,#,#,#)', constr,
+            args[0], args[1], args[2], args[3], args[4]));
+      case 6:
+        return new JsObject._fromJs(JS('=Object', 'new #(#,#,#,#,#,#)', constr,
+            args[0], args[1], args[2], args[3], args[4], args[5]));
+      case 7:
+        return new JsObject._fromJs(JS('=Object', 'new #(#,#,#,#,#,#,#)',
+            constr, args[0], args[1], args[2], args[3], args[4], args[5],
+            args[6]));
+      case 8:
+        return new JsObject._fromJs(JS('=Object', 'new #(#,#,#,#,#,#,#,#)',
+            constr, args[0], args[1], args[2], args[3], args[4], args[5],
+            args[6], args[7]));
+      case 9:
+        return new JsObject._fromJs(JS('=Object', 'new #(#,#,#,#,#,#,#,#,#)',
+            constr, args[0], args[1], args[2], args[3], args[4], args[5],
+            args[6], args[7], args[8]));
+      case 10:
+        return new JsObject._fromJs(JS('=Object', 'new #(#,#,#,#,#,#,#,#,#,#)',
+            constr, args[0], args[1], args[2], args[3], args[4], args[5],
+            args[6], args[7], args[8], args[9]));
+    }
+    return new JsObject._fromJs(JS('=Object', r'''(function(){
+var Type = function(){};
+Type.prototype = #.prototype;
+var instance = new Type();
+ret = #.apply(instance, #);
+ret = Object(ret) === ret ? ret : instance;
+return ret;
+})()''', constr, constr, args));
+  }
+
+  factory JsObject._json(data) => new JsObject._fromJs(_convertDataTree(data));
+
+  static _convertDataTree(data) {
+    if (data is Map) {
+      final convertedData = JS('=Object', '{}');
+      for (var key in data.keys) {
+        JS('=Object', '#[#]=#', convertedData, key,
+            _convertDataTree(data[key]));
+      }
+      return convertedData;
+    } else if (data is Iterable) {
+      return data.map(_convertDataTree).toList();
+    } else {
+      return _convertToJS(data);
+    }
+  }
+
+  JsObject toJs() => this;
+
+  operator[](key) =>
+      _convertToDart(JS('=Object', '#[#]', _convertToJS(this), key));
+  operator[]=(key, value) => JS('void', '#[#]=#', _convertToJS(this), key,
+      _convertToJS(value));
+
+  int get hashCode => 0;

[vsm, 2013/07/11 19:49:26]

Would it make sense to invoke toString on the underlying JS object and hash
that?

If not, can you add a TODO here - I think we'll want to figure out a proper
hash.

[alexandre.ardhuin, 2013/07/12 19:03:41]

I don't think this makes sense to call toString.
For example if JsObject wrap an Array. The result of toString will change if the
content of the Array changes. So it could lead to issues.

hashCode=0 is not very optimized but it works.

A solution could be to define a "__dart_id" on every proxify object and use the
hash of this id. Something like this :

  int _dart_id = 0; // top level

  JsObject._fromJs(this._jsObject) {
    if (JS('bool', '!("__dart_id" in #)', _convertToJS(this))) {
      JS('void', 'Object.defineProperty(#, "__dart_id", {value: #});',
          _convertToJS(this), _dart_id++);
    }
  }

  int get hashCode => JS('int', '#["__dart_id"]', _convertToJS(this)).hashCode;

  operator==(other) => other is JsObject &&
      JS('bool', '# === #', _convertToJS(this), _convertToJS(other));

I have a CL ready with that change.

What do you think ?

+
+  operator==(other) => other is JsObject &&
+      JS('bool', '# === #', _convertToJS(this), _convertToJS(other));
+
+  bool hasProperty(String property) => JS('bool', '# in #', property,
+      _convertToJS(this));
+
+  void deleteProperty(String name) {
+    JS('void', 'delete #[#]', _convertToJS(this), name);
+  }
+
+  bool instanceof(Serializable<JsFunction> type) =>
+      JS('bool', '# instanceof #', _convertToJS(this), _convertToJS(type));
+
+  String toString() {
+    try {
+      return JS('String', '#.toString()', _convertToJS(this));
+    } catch(e) {
+      return super.toString();
+    }
+  }
+
+  callMethod(String name, [List args]) =>
+      _convertToDart(JS('=Object', '#[#].apply(#, #)', _convertToJS(this), name,
+          _convertToJS(this),
+          args == null ? null : args.map(_convertToJS).toList()));
+}
+
+class JsFunction extends JsObject implements Serializable<JsFunction> {
+  JsFunction._fromJs(jsObject) : super._fromJs(jsObject);
+  apply(thisArg, [List args]) =>
+      _convertToDart(JS('=Object', '#.apply(#, #)', _convertToJS(this),
+          _convertToJS(thisArg),
+          args == null ? null : args.map(_convertToJS).toList()));
+}
+
+abstract class Serializable<T> {
+  T toJs();
+}
+
+dynamic _convertToJS(dynamic o) {
+  if (o == null) {
+    return null;
+  } else if (o is String || o is num || o is bool) {
+    return o;
+  } else if (o is JsObject) {
+    return o._jsObject;
+  } else if (o is Serializable) {
+    return _convertToJS(o.toJs());
+  } else if (o is Function) {
+    return _convertToJS(new Callback(o));
+  } else {
+    return JS('=Object', 'new DartProxy(#)', o);
+  }
+}
+
+dynamic _convertToDart(dynamic o) {
+  if (JS('bool', '# == null', o)) {
+    return null;
+  } else if (JS('bool', 'typeof # == "string" || # instanceof String', o, o) ||
+      JS('bool', 'typeof # == "number" || # instanceof Number', o, o) ||
+      JS('bool', 'typeof # == "boolean" || # instanceof Boolean', o, o)) {
+    return o;
+  } else if (JS('bool', '# instanceof Function', o)) {
+    return new JsFunction._fromJs(JS('=Object', '#', o));
+  } else if (JS('bool', '# instanceof DartProxy', o)) {
+    return JS('Object', '#.o', o);

[vsm, 2013/07/15 13:58:45]

sra pointed me to the docs here:
https://code.google.com/p/dart/source/browse/branches/bleeding_edge/dart/sdk/...

We should replace 'Object' with 'var' in the line above.  This should reduce
code size safely:
return JS('var', '#.o', o);

[alexandre.ardhuin, 2013/07/15 14:53:58]

Done.

+  } else {
+    return new JsObject._fromJs(JS('=Object', '#', o));
+  }
+}