RFC: introduce dart:js

sdk/lib/js/dart2js/js_dart2js.dart

Index: sdk/lib/js/dart2js/js_dart2js.dart
diff --git a/sdk/lib/js/dart2js/js_dart2js.dart b/sdk/lib/js/dart2js/js_dart2js.dart
new file mode 100644
index 0000000000000000000000000000000000000000..f103b6eef9f25b8627e943bb85916396769c7c3f
--- /dev/null
+++ b/sdk/lib/js/dart2js/js_dart2js.dart
@@ -0,0 +1,199 @@
+// 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));
+
+  operator==(other) => identical(this, 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();
+}
+
+class _DartProxy {

[vsm, 2013/06/20 18:43:58]

This might need to be defined in JS, as a JS type.

[alexandre.ardhuin, 2013/06/27 17:05:36]

Done. I have added a DartProxy javascript object.

+  dynamic o;
+  _DartProxy(this.o);
+}
+
+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 new _DartProxy(o);

[vsm, 2013/06/20 18:43:58]

It feels dangerous to pass out a direct pointer to a Dart instance here.

[alexandre.ardhuin, 2013/06/27 17:05:36]

Done.

+  }
+}
+
+dynamic _convertToDart(dynamic o) {

[vsm, 2013/06/20 18:43:58]

I think we need to always access "o" via JS notation to avoid confusing the
compiler.  E.g., based on the calls to this method, it looks like it only ever
gets passed an "Object".  Given that, dart2js might incorrectly tree-shake the
Dart type tests below.  Using JS - as you are doing for function - should be
safe.

[alexandre.ardhuin, 2013/06/27 17:05:36]

Done.

+  if (o == null) {
+    return null;
+  } else if (o is num || o is String || o is bool) {
+    return o;
+  } else if (JS('bool', '# instanceof Function', o)) {
+    return new JsFunction._fromJs(JS('=Object', '#', o));
+  } else if (o is _DartProxy) {
+    return o.o;
+  } else {
+    return new JsObject._fromJs(JS('=Object', '#', o));
+  }
+}