Cleanup JS() expressions. New Constructor for JsObject that preserves the correct prototype. Type c…

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
index 64b4af0b4771972ac4ac9b773480ece956d914b8..6ac611680437afd22b2317074c550c6ec1873749 100644
--- a/sdk/lib/js/dart2js/js_dart2js.dart
+++ b/sdk/lib/js/dart2js/js_dart2js.dart
@@ -4,7 +4,7 @@
 
 library dart.js;
 
-import 'dart:_foreign_helper' show JS;
+import 'dart:_foreign_helper' show JS, DART_CLOSURE_TO_JS;
 import 'dart:_js_helper' show Primitives, convertDartClosureToJS;
 
 final JsObject context = new JsObject._fromJs(Primitives.computeGlobalThis());
@@ -17,7 +17,7 @@ class Callback implements Serializable<JsFunction> {
   dynamic _jsFunction;
 
   Callback._(this._f, this._withThis) {
-    _jsFunction = JS('=Object', r'''
+    _jsFunction = JS('', r'''
 (function(){
   var f = #;
   return function(){
@@ -39,64 +39,62 @@ class Callback implements Serializable<JsFunction> {
   JsFunction toJs() => new JsFunction._fromJs(_jsFunction);
 }
 
+/*
+ * TODO(justinfagnani): add tests and make public when we remove Callback.
+ *
+ * Returns a [JsFunction] that captures its 'this' binding and calls [f]
+ * with the value of this passed as the first argument.
+ */
+JsFunction _captureThis(Function f) => 
+  new JsFunction._fromJs(_convertDartFunction(f, captureThis: true));
+
+_convertDartFunction(Function f, {bool captureThis: false}) {
+  return JS('',
+    'function(_call, f, captureThis) {'
+      'return function() {'
+        'return _call(f, captureThis, this, '
+            'Array.prototype.slice.apply(arguments));'
+      '}'
+    '}(#, #, #)', DART_CLOSURE_TO_JS(_callDartFunction), f, captureThis);
+}
+
+_callDartFunction(callback, bool captureThis, self, List arguments) {
+  if (captureThis) {
+    arguments = [self]..addAll(arguments);
+  }
+  var dartArgs = arguments.map(_convertToDart).toList();
+  return _convertToJS(Function.apply(callback, dartArgs));
+}
+
+
 class JsObject implements Serializable<JsObject> {
+  // The wrapped JS object.
   final dynamic _jsObject;
 
-  JsObject._fromJs(this._jsObject);
+  JsObject._fromJs(this._jsObject) {
+    // Remember this proxy for the JS object
+    _getDartProxy(_jsObject, _DART_OBJECT_PROPERTY_NAME, (o) => this);
+  }
 
   // TODO(vsm): Type constructor as Serializable<JsFunction> when
   // dartbug.com/11854 is fixed.
-  factory JsObject(var constructor, [List arguments]) {
-    final constr = _convertToJS(constructor);
+  factory JsObject(constructor, [List arguments]) {
+    var constr = _convertToJS(constructor);
     if (arguments == null) {
-      return new JsObject._fromJs(JS('=Object', 'new #()', constr));
+      return new JsObject._fromJs(JS('', '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));
+    // The following code solves the problem of invoking a JavaScript
+    // constructor with an unknown number arguments.
+    // First bind the constructor to the argument list using bind.apply().
+    // The first argument to bind() is the binding of 'this', so add 'null' to
+    // the arguments list passed to apply().
+    // After that, use the JavaScript 'new' operator which overrides any binding
+    // of 'this' with the new instance.
+    var args = [null]..addAll(arguments.map(_convertToJS));
+    var factoryFunction = JS('', '#.bind.apply(#, #)', constr, constr, args);
+    // Without this line, calling factoryFunction as a constructor throws
+    JS('String', 'String(#)', factoryFunction);
+    return new JsObject._fromJs(JS('', 'new #()', factoryFunction));
   }
 
   factory JsObject._json(data) => new JsObject._fromJs(_convertDataTree(data));
@@ -118,46 +116,82 @@ return ret;
 
   JsObject toJs() => this;
 
-  operator[](key) =>
-      _convertToDart(JS('=Object', '#[#]', _convertToJS(this), key));
-  operator[]=(key, value) => JS('void', '#[#]=#', _convertToJS(this), key,
-      _convertToJS(value));
+  /**
+   * Returns the value associated with [key] from the proxied JavaScript
+   * object.
+   *
+   * [key] must either be a [String] or [int].
+   */
+  // TODO(justinfagnani): rename key/name to property
+  dynamic operator[](key) {
+    if (key is! String && key is! int) {
+      throw new ArgumentError("key is not a String or int");
+    }
+    return _convertToDart(JS('', '#[#]', _jsObject, key));
+  }
+  
+  /**
+   * Sets the value associated with [key] from the proxied JavaScript
+   * object.
+   *
+   * [key] must either be a [String] or [int].
+   */
+  operator[]=(key, value) {
+    if (key is! String && key is! int) {
+      throw new ArgumentError("key is not a String or int");
+    }
+    JS('', '#[#]=#', _jsObject, key, _convertToJS(value));
+  }
 
   int get hashCode => 0;
 
-  operator==(other) => other is JsObject &&
-      JS('bool', '# === #', _convertToJS(this), _convertToJS(other));
+  bool operator==(other) => other is JsObject &&
+      JS('bool', '# === #', _jsObject, other._jsObject);
 
-  bool hasProperty(String property) => JS('bool', '# in #', property,
-      _convertToJS(this));
+  bool hasProperty(name) {
+    if (name is! String && name is! int) {
+      throw new ArgumentError("name is not a String or int");
+    }
+    return JS('bool', '# in #', name, _jsObject);
+  }
 
-  void deleteProperty(String name) {
-    JS('void', 'delete #[#]', _convertToJS(this), name);
+  void deleteProperty(name) {
+    if (name is! String && name is! int) {
+      throw new ArgumentError("name is not a String or int");
+    }
+    JS('bool', 'delete #[#]', _jsObject, name);
   }
 
   // TODO(vsm): Type type as Serializable<JsFunction> when
   // dartbug.com/11854 is fixed.
-  bool instanceof(var type) =>
-      JS('bool', '# instanceof #', _convertToJS(this), _convertToJS(type));
+  bool instanceof(type) {
+    return JS('bool', '# instanceof #', _jsObject, _convertToJS(type));
+  }
 
   String toString() {
     try {
-      return JS('String', '#.toString()', _convertToJS(this));
+      return JS('String', 'String(#)', _jsObject);
     } 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()));
+  dynamic callMethod(name, [List args]) {
+    if (name is! String && name is! int) {
+      throw new ArgumentError("name is not a String or int");
+    }
+    return _convertToDart(JS('', '#[#].apply(#, #)', _jsObject, name,
+        _jsObject,
+        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),
+      _convertToDart(JS('', '#.apply(#, #)', _jsObject,
           _convertToJS(thisArg),
           args == null ? null : args.map(_convertToJS).toList()));
 }
@@ -166,6 +200,27 @@ abstract class Serializable<T> {
   T toJs();
 }
 
+// property added to a Dart object referencing its JS-side DartObject proxy
+const _DART_OBJECT_PROPERTY_NAME = r'_$dart_dartObject';
+const _DART_CLOSURE_PROPERTY_NAME = r'_$dart_dartClosure';
+
+// property added to a JS object referencing its Dart-side JsObject proxy
+const _JS_OBJECT_PROPERTY_NAME = r'_$dart_jsObject';
+const _JS_FUNCTION_PROPERTY_NAME = r'$dart_jsFunction';
+
+bool _defineProperty(o, String name, value) {
+  if (JS('bool', 'Object.isExtensible(#)', o)) {
+    try {
+      JS('void', 'Object.defineProperty(#, #, { value: #})', o, name, value);
+      return true;
+    } catch(e) {
+      // object is native and lies about being extensible
+      // see https://bugzilla.mozilla.org/show_bug.cgi?id=775185
+    }
+  }
+  return false;
+}
+
 dynamic _convertToJS(dynamic o) {
   if (o == null) {
     return null;
@@ -176,24 +231,51 @@ dynamic _convertToJS(dynamic o) {
   } else if (o is Serializable) {
     return _convertToJS(o.toJs());
   } else if (o is Function) {
-    return _convertToJS(new Callback(o));
+    return _getJsProxy(o, _JS_FUNCTION_PROPERTY_NAME, (o) {
+      var jsFunction = _convertDartFunction(o);
+      // set a property on the JS closure referencing the Dart closure
+      _defineProperty(jsFunction, _DART_CLOSURE_PROPERTY_NAME, o);
+      return jsFunction;
+    });
   } else {
-    return JS('=Object', 'new DartProxy(#)', o);
+    return _getJsProxy(o, _JS_OBJECT_PROPERTY_NAME,
+        (o) => JS('', 'new DartObject(#)', 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)) {
+Object _getJsProxy(o, String propertyName, createProxy(o)) {
+  var jsProxy = JS('', '#[#]', o, propertyName);
+  if (jsProxy == null) {
+    jsProxy = createProxy(o);
+    _defineProperty(o, propertyName, jsProxy);
+  }
+  return jsProxy;
+}
+
+// converts a Dart object to a reference to a native JS object
+// which might be a DartObject JS->Dart proxy
+Object _convertToDart(o) {
+  if (JS('bool', '# == null', o) ||
+      JS('bool', 'typeof # == "string"', o) ||
+      JS('bool', 'typeof # == "number"', o) ||
+      JS('bool', 'typeof # == "boolean"', 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('var', '#.o', o);
+  } else if (JS('bool', 'typeof # == "function"', o)) {
+    return _getDartProxy(o, _DART_CLOSURE_PROPERTY_NAME,
+        (o) => new JsFunction._fromJs(o));
+  } else if (JS('bool', '#.constructor === DartObject', o)) {
+    return JS('', '#.o', o);
   } else {
-    return new JsObject._fromJs(JS('=Object', '#', o));
+    return _getDartProxy(o, _DART_OBJECT_PROPERTY_NAME,
+        (o) => new JsObject._fromJs(o));
   }
-}
+}
+
+Object _getDartProxy(o, String propertyName, createProxy(o)) {
+  var dartProxy = JS('', '#[#]', o, propertyName);
+  if (dartProxy == null) {
+    dartProxy = createProxy(o);
+    _defineProperty(o, propertyName, dartProxy);
+  }
+  return dartProxy;
+}