content: // 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:collection' show ListMixin;
  import 'dart:nativewrappers';
  
  JsObject _cachedContext;
  
  JsObject get _context native "Js_context_Callback";
  
  JsObject get context {
    if (_cachedContext == null) {
      _cachedContext = _context;
    }
    return _cachedContext;
  }
  
  /**
   * 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 extends NativeFieldWrapperClass2 {
    JsObject.internal();
  
    /**
     * Constructs a new JavaScript object from [constructor] and returns a proxy
     * to it.
     */
    factory JsObject(JsFunction constructor, [List arguments]) => _create(constructor, arguments);
  
    static JsObject _create(JsFunction constructor, arguments) native "JsObject_constructorCallback";
  
    /**
     * 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 _fromBrowserObject(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 _jsify(object);
    }
  
    static JsObject _jsify(object) native "JsObject_jsify";
  
    static JsObject _fromBrowserObject(object) native "JsObject_fromBrowserObject";
  
    /**
     * Returns the value associated with [property] from the proxied JavaScript
     * object.
     *
     * The type of [property] must be either [String] or [num].
     */
    operator[](property) native "JsObject_[]";
  
    /**
     * Sets the value associated with [property] on the proxied JavaScript
     * object.
     *
     * The type of [property] must be either [String] or [num].
     */
    operator[]=(property, value) native "JsObject_[]=";
  
    int get hashCode native "JsObject_hashCode";
  
    operator==(other) => other is JsObject && _identityEquality(this, other);
  
    static bool _identityEquality(JsObject a, JsObject b) native "JsObject_identityEquality";
  
    /**
     * 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(String property) native "JsObject_hasProperty";
  
    /**
     * Removes [property] from the JavaScript object.
     *
     * This is the equivalent of the `delete` operator in JavaScript.
     */
    void deleteProperty(String property) native "JsObject_deleteProperty";
  
    /**
     * 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) native "JsObject_instanceof";
  
    /**
     * Returns the result of the JavaScript objects `toString` method.
     */
    String toString() {
      try {
        return _toString();
      } catch(e) {
        return super.toString();
      }
    }
  
    String _toString() native "JsObject_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].
     */
    callMethod(String method, [List args]) {
      try {
        return _callMethod(method, args);
      } catch(e) {
        if (hasProperty(method)) {
          rethrow;
        } else {
          throw new NoSuchMethodError(this, new Symbol(method), args, null);
        }
      }
    }
  
    _callMethod(String name, List args) native "JsObject_callMethod";
  }
  
  /**
   * Proxies a JavaScript Function object.
   */
  class JsFunction extends JsObject {
    JsFunction.internal();
  
    /**
     * 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) => _withThis(f);
  
    /**
     * 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}) native "JsFunction_apply";
  
    /**
     * Internal only version of apply which uses debugger proxies of Dart objects
     * rather than opaque handles. This method is private because it cannot be
     * efficiently implemented in Dart2Js so should only be used by internal
     * tools.
     */
    _applyDebuggerOnly(List args, {thisArg}) native "JsFunction_applyDebuggerOnly";
  
    static JsFunction _withThis(Function f) native "JsFunction_withThis";
  }
  
  /**
   * A [List] proxying a JavaScript Array.
   */
  class JsArray<E> extends JsObject with ListMixin<E> {
  
    factory JsArray() => _newJsArray();
  
    static JsArray _newJsArray() native "JsArray_newJsArray";
  
    factory JsArray.from(Iterable<E> other) => _newJsArrayFromSafeList(new List.from(other));
  
    static JsArray _newJsArrayFromSafeList(List list) native "JsArray_newJsArrayFromSafeList";
  
    _checkIndex(int index, {bool insert: false}) {
      int length = insert ? this.length + 1 : this.length;
      if (index is int && (index < 0 || index >= length)) {
        throw new RangeError.range(index, 0, length);
      }
    }
  
    _checkRange(int start, int end) {
      int cachedLength = this.length;
      if (start < 0 || start > cachedLength) {
        throw new RangeError.range(start, 0, cachedLength);
      }
      if (end < start || end > cachedLength) {
        throw new RangeError.range(end, start, cachedLength);
      }
    }
  
    // Methods required by ListMixin
  
    E operator [](index) {
      if (index is int) {
        _checkIndex(index);
      }
      return super[index];
    }
  
    void operator []=(index, E value) {
      if(index is int) {
        _checkIndex(index);
      }
      super[index] = value;
    }
  
    int get length native "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) {
      // TODO(jacobr): this can be optimized slightly.
      callMethod('push', new List.from(iterable));
    }
  
    void insert(int index, E element) {
      _checkIndex(index, insert:true);
      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);
      callMethod('splice', [start, end - start]);
    }
  
    void setRange(int start, int end, Iterable<E> iterable, [int skipCount = 0]) {
      _checkRange(start, end);
      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)]) {
      callMethod('sort', [compare]);
    }
  }
  
  /**
   * Placeholder object for cases where we need to determine exactly how many
   * args were passed to a function.
   */
  const _UNDEFINED = const Object();
  
  // FIXME(jacobr): this method is a hack to work around the lack of proper dart
  // support for varargs methods.
  List _stripUndefinedArgs(List args) =>
      args.takeWhile((i) => i != _UNDEFINED).toList();
  
  /**
   * Returns a method that can be called with an arbitrary number (for n less
   * than 11) of arguments without violating Dart type checks.
   */
  Function _wrapAsDebuggerVarArgsFunction(JsFunction jsFunction) =>
    ([a1=_UNDEFINED, a2=_UNDEFINED, a3=_UNDEFINED, a4=_UNDEFINED,
      a5=_UNDEFINED, a6=_UNDEFINED, a7=_UNDEFINED, a8=_UNDEFINED,
      a9=_UNDEFINED, a10=_UNDEFINED]) =>
      jsFunction._applyDebuggerOnly(_stripUndefinedArgs(
          [a1,a2,a3,a4,a5,a6,a7,a8,a9,a10]));
  