first step for #168, adds dart:js impl to the build

tool/input_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.
+
+/**
+ * Support for interoperating with JavaScript.
+ *
+ * This library provides access to JavaScript objects from Dart, allowing
+ * Dart code to get and set properties, and call methods of JavaScript objects
+ * and invoke JavaScript functions. The library takes care of converting
+ * between Dart and JavaScript objects where possible, or providing proxies if
+ * conversion isn't possible.
+ *
+ * This library does not yet make Dart objects usable from JavaScript, their
+ * methods and proeprties are not accessible, though it does allow Dart
+ * functions to be passed into and called from JavaScript.
+ *
+ * [JsObject] is the core type and represents a proxy of a JavaScript object.
+ * JsObject gives access to the underlying JavaScript objects properties and
+ * methods. `JsObject`s can be acquired by calls to JavaScript, or they can be
+ * created from proxies to JavaScript constructors.
+ *
+ * The top-level getter [context] provides a [JsObject] that represents the
+ * global object in JavaScript, usually `window`.
+ *
+ * The following example shows an alert dialog via a JavaScript call to the
+ * global function `alert()`:
+ *
+ *     import 'dart:js';
+ *
+ *     main() => context.callMethod('alert', ['Hello from Dart!']);
+ *
+ * This example shows how to create a [JsObject] from a JavaScript constructor
+ * and access its properties:
+ *
+ *     import 'dart:js';
+ *
+ *     main() {
+ *       var object = new JsObject(context['Object']);
+ *       object['greeting'] = 'Hello';
+ *       object['greet'] = (name) => "${object['greeting']} $name";
+ *       var message = object.callMethod('greet', ['JavaScript']);
+ *       context['console'].callMethod('log', [message]);
+ *     }
+ *
+ * ## Proxying and automatic conversion
+ *
+ * When setting properties on a JsObject or passing arguments to a Javascript
+ * method or function, Dart objects are automatically converted or proxied to
+ * JavaScript objects. When accessing JavaScript properties, or when a Dart
+ * closure is invoked from JavaScript, the JavaScript objects are also
+ * converted to Dart.
+ *
+ * Functions and closures are proxied in such a way that they are callable. A
+ * Dart closure assigned to a JavaScript property is proxied by a function in
+ * JavaScript. A JavaScript function accessed from Dart is proxied by a
+ * [JsFunction], which has a [apply] method to invoke it.
+ *
+ * The following types are transferred directly and not proxied:
+ *
+ * * "Basic" types: `null`, `bool`, `num`, `String`, `DateTime`
+ * * `Blob`
+ * * `Event`
+ * * `HtmlCollection`
+ * * `ImageData`
+ * * `KeyRange`
+ * * `Node`
+ * * `NodeList`
+ * * `TypedData`, including its subclasses like `Int32List`, but _not_
+ *   `ByteBuffer`
+ * * `Window`
+ *
+ * ## Converting collections with JsObject.jsify()
+ *
+ * To create a JavaScript collection from a Dart collection use the
+ * [JsObject.jsify] constructor, which converts Dart [Map]s and [Iterable]s
+ * into JavaScript Objects and Arrays.
+ *
+ * The following expression creats a new JavaScript object with the properties
+ * `a` and `b` defined:
+ *
+ *     var jsMap = new JsObject.jsify({'a': 1, 'b': 2});
+ *
+ * This expression creates a JavaScript array:
+ *
+ *     var jsArray = new JsObject.jsify([1, 2, 3]);
+ */
+library dart.js;
+
+import 'dart:html' show Blob, Event, ImageData, Node, Window;
+import 'dart:collection' show HashMap, ListMixin;
+import 'dart:indexed_db' show KeyRange;
+import 'dart:typed_data' show TypedData;
+
+import 'dart:_foreign_helper' show JS, DART_CLOSURE_TO_JS;
+import 'dart:_interceptors' show JavaScriptObject, UnknownJavaScriptObject;
+import 'dart:_js_helper' show Primitives, convertDartClosureToJS,
+    getIsolateAffinityTag;
+
+final JsObject context = _wrapToDart(JS('', 'self'));
+
+_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 = new List.from(arguments.map(_convertToDart));
+  return _convertToJS(Function.apply(callback, dartArgs));
+}
+
+/**
+ * Proxies a JavaScript object to Dart.
+ *
+ * The properties of the JavaScript object are accessible via the `[]` and
+ * `[]=` operators. Methods are callable via [callMethod].
+ */
+class JsObject {
+  // The wrapped JS object.
+  final dynamic _jsObject;
+
+  // This shoud only be called from _wrapToDart
+  JsObject._fromJs(this._jsObject) {
+    assert(_jsObject != null);
+  }
+
+  /**
+   * Constructs a new JavaScript object from [constructor] and returns a proxy
+   * to it.
+   */
+  factory JsObject(JsFunction constructor, [List arguments]) {
+    var constr = _convertToJS(constructor);
+    if (arguments == null) {
+      return _wrapToDart(JS('', 'new #()', constr));
+    }
+    // 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);
+    // This could return an UnknownJavaScriptObject, or a native
+    // object for which there is an interceptor
+    var jsObj = JS('JavaScriptObject', 'new #()', factoryFunction);
+
+    return _wrapToDart(jsObj);
+  }
+
+  /**
+   * Constructs a [JsObject] that proxies a native Dart object; _for expert use
+   * only_.
+   *
+   * Use this constructor only if you wish to get access to JavaScript
+   * properties attached to a browser host object, such as a Node or Blob, that
+   * is normally automatically converted into a native Dart object.
+   *
+   * An exception will be thrown if [object] either is `null` or has the type
+   * `bool`, `num`, or `String`.
+   */
+  factory JsObject.fromBrowserObject(object) {
+    if (object is num || object is String || object is bool || object == null) {
+      throw new ArgumentError(
+        "object cannot be a num, string, bool, or null");
+    }
+    return _wrapToDart(_convertToJS(object));
+  }
+
+  /**
+   * Recursively converts a JSON-like collection of Dart objects to a
+   * collection of JavaScript objects and returns a [JsObject] proxy to it.
+   *
+   * [object] must be a [Map] or [Iterable], the contents of which are also
+   * converted. Maps and Iterables are copied to a new JavaScript object.
+   * Primitives and other transferrable values are directly converted to their
+   * JavaScript type, and all other objects are proxied.
+   */
+  factory JsObject.jsify(object) {
+    if ((object is! Map) && (object is! Iterable)) {
+      throw new ArgumentError("object must be a Map or Iterable");
+    }
+    return _wrapToDart(_convertDataTree(object));
+  }
+
+  static _convertDataTree(data) {
+    var _convertedObjects = new HashMap.identity();
+
+    _convert(o) {
+      if (_convertedObjects.containsKey(o)) {
+        return _convertedObjects[o];
+      }
+      if (o is Map) {
+        final convertedMap = JS('=Object', '{}');
+        _convertedObjects[o] = convertedMap;
+        for (var key in o.keys) {
+          JS('=Object', '#[#]=#', convertedMap, key, _convert(o[key]));
+        }
+        return convertedMap;
+      } else if (o is Iterable) {
+        var convertedList = [];
+        _convertedObjects[o] = convertedList;
+        convertedList.addAll(o.map(_convert));
+        return convertedList;
+      } else {
+        return _convertToJS(o);
+      }
+    }
+
+    return _convert(data);
+  }
+
+  /**
+   * Returns the value associated with [property] from the proxied JavaScript
+   * object.
+   *
+   * The type of [property] must be either [String] or [num].
+   */
+  dynamic operator[](property) {
+    if (property is! String && property is! num) {
+      throw new ArgumentError("property is not a String or num");
+    }
+    return _convertToDart(JS('', '#[#]', _jsObject, property));
+  }
+
+  /**
+   * Sets the value associated with [property] on the proxied JavaScript
+   * object.
+   *
+   * The type of [property] must be either [String] or [num].
+   */
+  operator[]=(property, value) {
+    if (property is! String && property is! num) {
+      throw new ArgumentError("property is not a String or num");
+    }
+    JS('', '#[#]=#', _jsObject, property, _convertToJS(value));
+  }
+
+  int get hashCode => 0;
+
+  bool operator==(other) => other is JsObject &&
+      JS('bool', '# === #', _jsObject, other._jsObject);
+
+  /**
+   * Returns `true` if the JavaScript object contains the specified property
+   * either directly or though its prototype chain.
+   *
+   * This is the equivalent of the `in` operator in JavaScript.
+   */
+  bool hasProperty(property) {
+    if (property is! String && property is! num) {
+      throw new ArgumentError("property is not a String or num");
+    }
+    return JS('bool', '# in #', property, _jsObject);
+  }
+
+  /**
+   * Removes [property] from the JavaScript object.
+   *
+   * This is the equivalent of the `delete` operator in JavaScript.
+   */
+  void deleteProperty(property) {
+    if (property is! String && property is! num) {
+      throw new ArgumentError("property is not a String or num");
+    }
+    JS('bool', 'delete #[#]', _jsObject, property);
+  }
+
+  /**
+   * Returns `true` if the JavaScript object has [type] in its prototype chain.
+   *
+   * This is the equivalent of the `instanceof` operator in JavaScript.
+   */
+  bool instanceof(JsFunction type) {
+    return JS('bool', '# instanceof #', _jsObject, _convertToJS(type));
+  }
+
+  /**
+   * Returns the result of the JavaScript objects `toString` method.
+   */
+  String toString() {
+    try {
+      return JS('String', 'String(#)', _jsObject);
+    } catch(e) {
+      return super.toString();
+    }
+  }
+
+  /**
+   * Calls [method] on the JavaScript object with the arguments [args] and
+   * returns the result.
+   *
+   * The type of [method] must be either [String] or [num].
+   */
+  dynamic callMethod(method, [List args]) {
+    if (method is! String && method is! num) {
+      throw new ArgumentError("method is not a String or num");
+    }
+    return _convertToDart(JS('', '#[#].apply(#, #)', _jsObject, method,
+        _jsObject,
+        args == null ? null : new List.from(args.map(_convertToJS))));
+  }
+}
+
+/**
+ * Proxies a JavaScript Function object.
+ */
+class JsFunction extends JsObject {
+
+  /**
+   * Returns a [JsFunction] that captures its 'this' binding and calls [f]
+   * with the value of this passed as the first argument.
+   */
+  factory JsFunction.withThis(Function f) {
+    var jsFunc = _convertDartFunction(f, captureThis: true);
+    return new JsFunction._fromJs(jsFunc);
+  }
+
+  JsFunction._fromJs(jsObject) : super._fromJs(jsObject);
+
+  /**
+   * Invokes the JavaScript function with arguments [args]. If [thisArg] is
+   * supplied it is the value of `this` for the invocation.
+   */
+  dynamic apply(List args, { thisArg }) =>
+      _convertToDart(JS('', '#.apply(#, #)', _jsObject,
+          _convertToJS(thisArg),
+          args == null ? null : new List.from(args.map(_convertToJS))));
+}
+
+/**
+ * A [List] that proxies a JavaScript array.
+ */
+class JsArray<E> extends JsObject with ListMixin<E> {
+
+  /**
+   * Creates a new JavaScript array.
+   */
+  JsArray() : super._fromJs([]);
+
+  /**
+   * Creates a new JavaScript array and initializes it to the contents of
+   * [other].
+   */
+  JsArray.from(Iterable<E> other)
+      : super._fromJs([]..addAll(other.map(_convertToJS)));
+
+  JsArray._fromJs(jsObject) : super._fromJs(jsObject);
+
+  _checkIndex(int index) {
+    if (index is int && (index < 0 || index >= length)) {
+      throw new RangeError.range(index, 0, length);
+    }
+  }
+
+  _checkInsertIndex(int index) {
+    if (index is int && (index < 0 || index >= length + 1)) {
+      throw new RangeError.range(index, 0, length);
+    }
+  }
+
+  static _checkRange(int start, int end, int length) {
+    if (start < 0 || start > length) {
+      throw new RangeError.range(start, 0, length);
+    }
+    if (end < start || end > length) {
+      throw new RangeError.range(end, start, length);
+    }
+  }
+
+  // Methods required by ListMixin
+
+  E operator [](index) {
+    // TODO(justinfagnani): fix the semantics for non-ints
+    // dartbug.com/14605
+    if (index is num && index == index.toInt()) {
+      _checkIndex(index);
+    }
+    return super[index];
+  }
+
+  void operator []=(index, E value) {
+    // TODO(justinfagnani): fix the semantics for non-ints
+    // dartbug.com/14605
+    if (index is num && index == index.toInt()) {
+      _checkIndex(index);
+    }
+    super[index] = value;
+  }
+
+  int get length {
+    // Check the length honours the List contract.
+    var len = JS('', '#.length', _jsObject);
+    // JavaScript arrays have lengths which are unsigned 32-bit integers.
+    if (JS('bool', 'typeof # === "number" && (# >>> 0) === #', len, len, len)) {
+      return JS('int', '#', len);
+    }
+    throw new StateError('Bad JsArray length');
+  }
+
+  void set length(int length) { super['length'] = length; }
+
+
+  // Methods overriden for better performance
+
+  void add(E value) {
+    callMethod('push', [value]);
+  }
+
+  void addAll(Iterable<E> iterable) {
+    var list = (JS('bool', '# instanceof Array', iterable))
+        ? iterable
+        : new List.from(iterable);
+    callMethod('push', list);
+  }
+
+  void insert(int index, E element) {
+    _checkInsertIndex(index);
+    callMethod('splice', [index, 0, element]);
+  }
+
+  E removeAt(int index) {
+    _checkIndex(index);
+    return callMethod('splice', [index, 1])[0];
+  }
+
+  E removeLast() {
+    if (length == 0) throw new RangeError(-1);
+    return callMethod('pop');
+  }
+
+  void removeRange(int start, int end) {
+    _checkRange(start, end, length);
+    callMethod('splice', [start, end - start]);
+  }
+
+  void setRange(int start, int end, Iterable<E> iterable, [int skipCount = 0]) {
+    _checkRange(start, end, length);
+    int length = end - start;
+    if (length == 0) return;
+    if (skipCount < 0) throw new ArgumentError(skipCount);
+    var args = [start, length]..addAll(iterable.skip(skipCount).take(length));
+    callMethod('splice', args);
+  }
+
+  void sort([int compare(E a, E b)]) {
+    // Note: arr.sort(null) is a type error in FF
+    callMethod('sort', compare == null ? [] : [compare]);
+  }
+}
+
+// property added to a Dart object referencing its JS-side DartObject proxy
+final String _DART_OBJECT_PROPERTY_NAME =
+    getIsolateAffinityTag(r'_$dart_dartObject');
+final String _DART_CLOSURE_PROPERTY_NAME =
+    getIsolateAffinityTag(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 (_isExtensible(o) &&
+      // TODO(ahe): Calling _hasOwnProperty to work around
+      // https://code.google.com/p/dart/issues/detail?id=21331.
+      !_hasOwnProperty(o, name)) {
+    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;
+}
+
+bool _hasOwnProperty(o, String name) {
+  return JS('bool', 'Object.prototype.hasOwnProperty.call(#, #)', o, name);
+}
+
+bool _isExtensible(o) => JS('bool', 'Object.isExtensible(#)', o);
+
+Object _getOwnProperty(o, String name) {
+  if (_hasOwnProperty(o, name)) {
+    return JS('', '#[#]', o, name);
+  }
+  return null;
+}
+
+bool _isLocalObject(o) => JS('bool', '# instanceof Object', o);
+
+// The shared constructor function for proxies to Dart objects in JavaScript.
+final _dartProxyCtor = JS('', 'function DartObject(o) { this.o = o; }');
+
+dynamic _convertToJS(dynamic o) {
+  // Note: we don't write `if (o == null) return null;` to make sure dart2js
+  // doesn't convert `return null;` into `return;` (which would make `null` be
+  // `undefined` in Javascprit). See dartbug.com/20305 for details.
+  if (o == null || o is String || o is num || o is bool) {
+    return o;
+  } else if (o is Blob || o is Event || o is KeyRange || o is ImageData
+      || o is Node || o is TypedData || o is Window) {
+    return o;
+  } else if (o is DateTime) {
+    return Primitives.lazyAsJsDate(o);
+  } else if (o is JsObject) {
+    return o._jsObject;
+  } else if (o is Function) {
+    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 {
+    var ctor = _dartProxyCtor;
+    return _getJsProxy(o, _JS_OBJECT_PROPERTY_NAME,
+        (o) => JS('', 'new #(#)', ctor, o));
+  }
+}
+
+Object _getJsProxy(o, String propertyName, createProxy(o)) {
+  var jsProxy = _getOwnProperty(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 (_isLocalObject(o)
+      && (o is Blob || o is Event || o is KeyRange || o is ImageData
+      || o is Node || o is TypedData || o is Window)) {
+    // long line: dart2js doesn't allow string concatenation in the JS() form
+    return JS('Blob|Event|KeyRange|ImageData|Node|TypedData|Window', '#', o);
+  } else if (JS('bool', '# instanceof Date', o)) {
+    var ms = JS('num', '#.getTime()', o);
+    return new DateTime.fromMillisecondsSinceEpoch(ms);
+  } else if (JS('bool', '#.constructor === #', o, _dartProxyCtor)) {
+    return JS('', '#.o', o);
+  } else {
+    return _wrapToDart(o);
+  }
+}
+
+JsObject _wrapToDart(o) {
+  if (JS('bool', 'typeof # == "function"', o)) {
+    return _getDartProxy(o, _DART_CLOSURE_PROPERTY_NAME,
+        (o) => new JsFunction._fromJs(o));
+  } else if (JS('bool', '# instanceof Array', o)) {
+    return _getDartProxy(o, _DART_OBJECT_PROPERTY_NAME,
+        (o) => new JsArray._fromJs(o));
+  } else {
+    return _getDartProxy(o, _DART_OBJECT_PROPERTY_NAME,
+        (o) => new JsObject._fromJs(o));
+  }
+}
+
+Object _getDartProxy(o, String propertyName, createProxy(o)) {
+  var dartProxy = _getOwnProperty(o, propertyName);
+  // Temporary fix for dartbug.com/15193
+  // In some cases it's possible to see a JavaScript object that
+  // came from a different context and was previously proxied to
+  // Dart in that context. The JS object will have a cached proxy
+  // but it won't be a valid Dart object in this context.
+  // For now we throw away the cached proxy, but we should be able
+  // to cache proxies from multiple JS contexts and Dart isolates.
+  if (dartProxy == null || !_isLocalObject(o)) {
+    dartProxy = createProxy(o);
+    _defineProperty(o, propertyName, dartProxy);
+  }
+  return dartProxy;
+}