  /**
   * Represents a group of disposable resources that are disposed together.
   * @constructor
   */
  var CompositeDisposable = Rx.CompositeDisposable = function () {
    var args = [], i, len;
    if (Array.isArray(arguments[0])) {
      args = arguments[0];
      len = args.length;
    } else {
      len = arguments.length;
      args = new Array(len);
      for(i = 0; i < len; i++) { args[i] = arguments[i]; }
    }
    for(i = 0; i < len; i++) {
      if (!isDisposable(args[i])) { throw new TypeError('Not a disposable'); }
    }
    this.disposables = args;
    this.isDisposed = false;
    this.length = args.length;
  };

  var CompositeDisposablePrototype = CompositeDisposable.prototype;

  /**
   * Adds a disposable to the CompositeDisposable or disposes the disposable if the CompositeDisposable is disposed.
   * @param {Mixed} item Disposable to add.
   */
  CompositeDisposablePrototype.add = function (item) {
    if (this.isDisposed) {
      item.dispose();
    } else {
      this.disposables.push(item);
      this.length++;
    }
  };

  /**
   * Removes and disposes the first occurrence of a disposable from the CompositeDisposable.
   * @param {Mixed} item Disposable to remove.
   * @returns {Boolean} true if found; false otherwise.
   */
  CompositeDisposablePrototype.remove = function (item) {
    var shouldDispose = false;
    if (!this.isDisposed) {
      var idx = this.disposables.indexOf(item);
      if (idx !== -1) {
        shouldDispose = true;
        this.disposables.splice(idx, 1);
        this.length--;
        item.dispose();
      }
    }
    return shouldDispose;
  };

  /**
   *  Disposes all disposables in the group and removes them from the group.
   */
  CompositeDisposablePrototype.dispose = function () {
    if (!this.isDisposed) {
      this.isDisposed = true;
      var len = this.disposables.length, currentDisposables = new Array(len);
      for(var i = 0; i < len; i++) { currentDisposables[i] = this.disposables[i]; }
      this.disposables = [];
      this.length = 0;

      for (i = 0; i < len; i++) {
        currentDisposables[i].dispose();
      }
    }
  };
