// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.

;(function (undefined) {

  var objectTypes = {
    'boolean': false,
    'function': true,
    'object': true,
    'number': false,
    'string': false,
    'undefined': false
  };

  var root = (objectTypes[typeof window] && window) || this,
    freeExports = objectTypes[typeof exports] && exports && !exports.nodeType && exports,
    freeModule = objectTypes[typeof module] && module && !module.nodeType && module,
    moduleExports = freeModule && freeModule.exports === freeExports && freeExports,
    freeGlobal = objectTypes[typeof global] && global;

  if (freeGlobal && (freeGlobal.global === freeGlobal || freeGlobal.window === freeGlobal)) {
    root = freeGlobal;
  }

  var Rx = {
      internals: {},
      config: {
        Promise: root.Promise
      },
      helpers: { }
  };

  // Defaults
  var noop = Rx.helpers.noop = function () { },
    notDefined = Rx.helpers.notDefined = function (x) { return typeof x === 'undefined'; },
    identity = Rx.helpers.identity = function (x) { return x; },
    pluck = Rx.helpers.pluck = function (property) { return function (x) { return x[property]; }; },
    just = Rx.helpers.just = function (value) { return function () { return value; }; },
    defaultNow = Rx.helpers.defaultNow = Date.now,
    defaultComparer = Rx.helpers.defaultComparer = function (x, y) { return isEqual(x, y); },
    defaultSubComparer = Rx.helpers.defaultSubComparer = function (x, y) { return x > y ? 1 : (x < y ? -1 : 0); },
    defaultKeySerializer = Rx.helpers.defaultKeySerializer = function (x) { return x.toString(); },
    defaultError = Rx.helpers.defaultError = function (err) { throw err; },
    isPromise = Rx.helpers.isPromise = function (p) { return !!p && typeof p.then === 'function'; },
    asArray = Rx.helpers.asArray = function () { return Array.prototype.slice.call(arguments); },
    not = Rx.helpers.not = function (a) { return !a; },
    isFunction = Rx.helpers.isFunction = (function () {

      var isFn = function (value) {
        return typeof value == 'function' || false;
      }

      // fallback for older versions of Chrome and Safari
      if (isFn(/x/)) {
        isFn = function(value) {
          return typeof value == 'function' && toString.call(value) == '[object Function]';
        };
      }

      return isFn;
    }());

  function cloneArray(arr) { for(var a = [], i = 0, len = arr.length; i < len; i++) { a.push(arr[i]); } return a;}

  Rx.config.longStackSupport = false;
  var hasStacks = false;
  try {
    throw new Error();
  } catch (e) {
    hasStacks = !!e.stack;
  }

  // All code after this point will be filtered from stack traces reported by RxJS
  var rStartingLine = captureLine(), rFileName;

  var STACK_JUMP_SEPARATOR = "From previous event:";

  function makeStackTraceLong(error, observable) {
      // If possible, transform the error stack trace by removing Node and RxJS
      // cruft, then concatenating with the stack trace of `observable`.
      if (hasStacks &&
          observable.stack &&
          typeof error === "object" &&
          error !== null &&
          error.stack &&
          error.stack.indexOf(STACK_JUMP_SEPARATOR) === -1
      ) {
        var stacks = [];
        for (var o = observable; !!o; o = o.source) {
          if (o.stack) {
            stacks.unshift(o.stack);
          }
        }
        stacks.unshift(error.stack);

        var concatedStacks = stacks.join("\n" + STACK_JUMP_SEPARATOR + "\n");
        error.stack = filterStackString(concatedStacks);
    }
  }

  function filterStackString(stackString) {
    var lines = stackString.split("\n"),
        desiredLines = [];
    for (var i = 0, len = lines.length; i < len; i++) {
      var line = lines[i];

      if (!isInternalFrame(line) && !isNodeFrame(line) && line) {
        desiredLines.push(line);
      }
    }
    return desiredLines.join("\n");
  }

  function isInternalFrame(stackLine) {
    var fileNameAndLineNumber = getFileNameAndLineNumber(stackLine);
    if (!fileNameAndLineNumber) {
      return false;
    }
    var fileName = fileNameAndLineNumber[0], lineNumber = fileNameAndLineNumber[1];

    return fileName === rFileName &&
      lineNumber >= rStartingLine &&
      lineNumber <= rEndingLine;
  }

  function isNodeFrame(stackLine) {
    return stackLine.indexOf("(module.js:") !== -1 ||
      stackLine.indexOf("(node.js:") !== -1;
  }

  function captureLine() {
    if (!hasStacks) { return; }

    try {
      throw new Error();
    } catch (e) {
      var lines = e.stack.split("\n");
      var firstLine = lines[0].indexOf("@") > 0 ? lines[1] : lines[2];
      var fileNameAndLineNumber = getFileNameAndLineNumber(firstLine);
      if (!fileNameAndLineNumber) { return; }

      rFileName = fileNameAndLineNumber[0];
      return fileNameAndLineNumber[1];
    }
  }

  function getFileNameAndLineNumber(stackLine) {
    // Named functions: "at functionName (filename:lineNumber:columnNumber)"
    var attempt1 = /at .+ \((.+):(\d+):(?:\d+)\)$/.exec(stackLine);
    if (attempt1) { return [attempt1[1], Number(attempt1[2])]; }

    // Anonymous functions: "at filename:lineNumber:columnNumber"
    var attempt2 = /at ([^ ]+):(\d+):(?:\d+)$/.exec(stackLine);
    if (attempt2) { return [attempt2[1], Number(attempt2[2])]; }

    // Firefox style: "function@filename:lineNumber or @filename:lineNumber"
    var attempt3 = /.*@(.+):(\d+)$/.exec(stackLine);
    if (attempt3) { return [attempt3[1], Number(attempt3[2])]; }
  }

  var EmptyError = Rx.EmptyError = function() {
    this.message = 'Sequence contains no elements.';
    Error.call(this);
  };
  EmptyError.prototype = Error.prototype;

  var ObjectDisposedError = Rx.ObjectDisposedError = function() {
    this.message = 'Object has been disposed';
    Error.call(this);
  };
  ObjectDisposedError.prototype = Error.prototype;

  var ArgumentOutOfRangeError = Rx.ArgumentOutOfRangeError = function () {
    this.message = 'Argument out of range';
    Error.call(this);
  };
  ArgumentOutOfRangeError.prototype = Error.prototype;

  var NotSupportedError = Rx.NotSupportedError = function (message) {
    this.message = message || 'This operation is not supported';
    Error.call(this);
  };
  NotSupportedError.prototype = Error.prototype;

  var NotImplementedError = Rx.NotImplementedError = function (message) {
    this.message = message || 'This operation is not implemented';
    Error.call(this);
  };
  NotImplementedError.prototype = Error.prototype;

  var notImplemented = Rx.helpers.notImplemented = function () {
    throw new NotImplementedError();
  };

  var notSupported = Rx.helpers.notSupported = function () {
    throw new NotSupportedError();
  };

  // Shim in iterator support
  var $iterator$ = (typeof Symbol === 'function' && Symbol.iterator) ||
    '_es6shim_iterator_';
  // Bug for mozilla version
  if (root.Set && typeof new root.Set()['@@iterator'] === 'function') {
    $iterator$ = '@@iterator';
  }

  var doneEnumerator = Rx.doneEnumerator = { done: true, value: undefined };

  var isIterable = Rx.helpers.isIterable = function (o) {
    return o[$iterator$] !== undefined;
  }

  var isArrayLike = Rx.helpers.isArrayLike = function (o) {
    return o && o.length !== undefined;
  }

  Rx.helpers.iterator = $iterator$;

  var bindCallback = Rx.internals.bindCallback = function (func, thisArg, argCount) {
    if (typeof thisArg === 'undefined') { return func; }
    switch(argCount) {
      case 0:
        return function() {
          return func.call(thisArg)
        };
      case 1:
        return function(arg) {
          return func.call(thisArg, arg);
        }
      case 2:
        return function(value, index) {
          return func.call(thisArg, value, index);
        };
      case 3:
        return function(value, index, collection) {
          return func.call(thisArg, value, index, collection);
        };
    }

    return function() {
      return func.apply(thisArg, arguments);
    };
  };

  /** Used to determine if values are of the language type Object */
  var dontEnums = ['toString',
    'toLocaleString',
    'valueOf',
    'hasOwnProperty',
    'isPrototypeOf',
    'propertyIsEnumerable',
    'constructor'],
  dontEnumsLength = dontEnums.length;

  /** `Object#toString` result shortcuts */
  var argsClass = '[object Arguments]',
    arrayClass = '[object Array]',
    boolClass = '[object Boolean]',
    dateClass = '[object Date]',
    errorClass = '[object Error]',
    funcClass = '[object Function]',
    numberClass = '[object Number]',
    objectClass = '[object Object]',
    regexpClass = '[object RegExp]',
    stringClass = '[object String]';

  var toString = Object.prototype.toString,
    hasOwnProperty = Object.prototype.hasOwnProperty,
    supportsArgsClass = toString.call(arguments) == argsClass, // For less <IE9 && FF<4
    supportNodeClass,
    errorProto = Error.prototype,
    objectProto = Object.prototype,
    stringProto = String.prototype,
    propertyIsEnumerable = objectProto.propertyIsEnumerable;

  try {
    supportNodeClass = !(toString.call(document) == objectClass && !({ 'toString': 0 } + ''));
  } catch (e) {
    supportNodeClass = true;
  }

  var nonEnumProps = {};
  nonEnumProps[arrayClass] = nonEnumProps[dateClass] = nonEnumProps[numberClass] = { 'constructor': true, 'toLocaleString': true, 'toString': true, 'valueOf': true };
  nonEnumProps[boolClass] = nonEnumProps[stringClass] = { 'constructor': true, 'toString': true, 'valueOf': true };
  nonEnumProps[errorClass] = nonEnumProps[funcClass] = nonEnumProps[regexpClass] = { 'constructor': true, 'toString': true };
  nonEnumProps[objectClass] = { 'constructor': true };

  var support = {};
  (function () {
    var ctor = function() { this.x = 1; },
      props = [];

    ctor.prototype = { 'valueOf': 1, 'y': 1 };
    for (var key in new ctor) { props.push(key); }
    for (key in arguments) { }

    // Detect if `name` or `message` properties of `Error.prototype` are enumerable by default.
    support.enumErrorProps = propertyIsEnumerable.call(errorProto, 'message') || propertyIsEnumerable.call(errorProto, 'name');

    // Detect if `prototype` properties are enumerable by default.
    support.enumPrototypes = propertyIsEnumerable.call(ctor, 'prototype');

    // Detect if `arguments` object indexes are non-enumerable
    support.nonEnumArgs = key != 0;

    // Detect if properties shadowing those on `Object.prototype` are non-enumerable.
    support.nonEnumShadows = !/valueOf/.test(props);
  }(1));

  var isObject = Rx.internals.isObject = function(value) {
    var type = typeof value;
    return value && (type == 'function' || type == 'object') || false;
  };

  function keysIn(object) {
    var result = [];
    if (!isObject(object)) {
      return result;
    }
    if (support.nonEnumArgs && object.length && isArguments(object)) {
      object = slice.call(object);
    }
    var skipProto = support.enumPrototypes && typeof object == 'function',
        skipErrorProps = support.enumErrorProps && (object === errorProto || object instanceof Error);

    for (var key in object) {
      if (!(skipProto && key == 'prototype') &&
          !(skipErrorProps && (key == 'message' || key == 'name'))) {
        result.push(key);
      }
    }

    if (support.nonEnumShadows && object !== objectProto) {
      var ctor = object.constructor,
          index = -1,
          length = dontEnumsLength;

      if (object === (ctor && ctor.prototype)) {
        var className = object === stringProto ? stringClass : object === errorProto ? errorClass : toString.call(object),
            nonEnum = nonEnumProps[className];
      }
      while (++index < length) {
        key = dontEnums[index];
        if (!(nonEnum && nonEnum[key]) && hasOwnProperty.call(object, key)) {
          result.push(key);
        }
      }
    }
    return result;
  }

  function internalFor(object, callback, keysFunc) {
    var index = -1,
      props = keysFunc(object),
      length = props.length;

    while (++index < length) {
      var key = props[index];
      if (callback(object[key], key, object) === false) {
        break;
      }
    }
    return object;
  }

  function internalForIn(object, callback) {
    return internalFor(object, callback, keysIn);
  }

  function isNode(value) {
    // IE < 9 presents DOM nodes as `Object` objects except they have `toString`
    // methods that are `typeof` "string" and still can coerce nodes to strings
    return typeof value.toString != 'function' && typeof (value + '') == 'string';
  }

  var isArguments = function(value) {
    return (value && typeof value == 'object') ? toString.call(value) == argsClass : false;
  }

  // fallback for browsers that can't detect `arguments` objects by [[Class]]
  if (!supportsArgsClass) {
    isArguments = function(value) {
      return (value && typeof value == 'object') ? hasOwnProperty.call(value, 'callee') : false;
    };
  }

  var isEqual = Rx.internals.isEqual = function (x, y) {
    return deepEquals(x, y, [], []);
  };

  /** @private
   * Used for deep comparison
   **/
  function deepEquals(a, b, stackA, stackB) {
    // exit early for identical values
    if (a === b) {
      // treat `+0` vs. `-0` as not equal
      return a !== 0 || (1 / a == 1 / b);
    }

    var type = typeof a,
        otherType = typeof b;

    // exit early for unlike primitive values
    if (a === a && (a == null || b == null ||
        (type != 'function' && type != 'object' && otherType != 'function' && otherType != 'object'))) {
      return false;
    }

    // compare [[Class]] names
    var className = toString.call(a),
        otherClass = toString.call(b);

    if (className == argsClass) {
      className = objectClass;
    }
    if (otherClass == argsClass) {
      otherClass = objectClass;
    }
    if (className != otherClass) {
      return false;
    }
    switch (className) {
      case boolClass:
      case dateClass:
        // coerce dates and booleans to numbers, dates to milliseconds and booleans
        // to `1` or `0` treating invalid dates coerced to `NaN` as not equal
        return +a == +b;

      case numberClass:
        // treat `NaN` vs. `NaN` as equal
        return (a != +a) ?
          b != +b :
          // but treat `-0` vs. `+0` as not equal
          (a == 0 ? (1 / a == 1 / b) : a == +b);

      case regexpClass:
      case stringClass:
        // coerce regexes to strings (http://es5.github.io/#x15.10.6.4)
        // treat string primitives and their corresponding object instances as equal
        return a == String(b);
    }
    var isArr = className == arrayClass;
    if (!isArr) {

      // exit for functions and DOM nodes
      if (className != objectClass || (!support.nodeClass && (isNode(a) || isNode(b)))) {
        return false;
      }
      // in older versions of Opera, `arguments` objects have `Array` constructors
      var ctorA = !support.argsObject && isArguments(a) ? Object : a.constructor,
          ctorB = !support.argsObject && isArguments(b) ? Object : b.constructor;

      // non `Object` object instances with different constructors are not equal
      if (ctorA != ctorB &&
            !(hasOwnProperty.call(a, 'constructor') && hasOwnProperty.call(b, 'constructor')) &&
            !(isFunction(ctorA) && ctorA instanceof ctorA && isFunction(ctorB) && ctorB instanceof ctorB) &&
            ('constructor' in a && 'constructor' in b)
          ) {
        return false;
      }
    }
    // assume cyclic structures are equal
    // the algorithm for detecting cyclic structures is adapted from ES 5.1
    // section 15.12.3, abstract operation `JO` (http://es5.github.io/#x15.12.3)
    var initedStack = !stackA;
    stackA || (stackA = []);
    stackB || (stackB = []);

    var length = stackA.length;
    while (length--) {
      if (stackA[length] == a) {
        return stackB[length] == b;
      }
    }
    var size = 0;
    var result = true;

    // add `a` and `b` to the stack of traversed objects
    stackA.push(a);
    stackB.push(b);

    // recursively compare objects and arrays (susceptible to call stack limits)
    if (isArr) {
      // compare lengths to determine if a deep comparison is necessary
      length = a.length;
      size = b.length;
      result = size == length;

      if (result) {
        // deep compare the contents, ignoring non-numeric properties
        while (size--) {
          var index = length,
              value = b[size];

          if (!(result = deepEquals(a[size], value, stackA, stackB))) {
            break;
          }
        }
      }
    }
    else {
      // deep compare objects using `forIn`, instead of `forOwn`, to avoid `Object.keys`
      // which, in this case, is more costly
      internalForIn(b, function(value, key, b) {
        if (hasOwnProperty.call(b, key)) {
          // count the number of properties.
          size++;
          // deep compare each property value.
          return (result = hasOwnProperty.call(a, key) && deepEquals(a[key], value, stackA, stackB));
        }
      });

      if (result) {
        // ensure both objects have the same number of properties
        internalForIn(a, function(value, key, a) {
          if (hasOwnProperty.call(a, key)) {
            // `size` will be `-1` if `a` has more properties than `b`
            return (result = --size > -1);
          }
        });
      }
    }
    stackA.pop();
    stackB.pop();

    return result;
  }

  var hasProp = {}.hasOwnProperty,
      slice = Array.prototype.slice;

  var inherits = this.inherits = Rx.internals.inherits = function (child, parent) {
    function __() { this.constructor = child; }
    __.prototype = parent.prototype;
    child.prototype = new __();
  };

  var addProperties = Rx.internals.addProperties = function (obj) {
    for(var sources = [], i = 1, len = arguments.length; i < len; i++) { sources.push(arguments[i]); }
    for (var idx = 0, ln = sources.length; idx < ln; idx++) {
      var source = sources[idx];
      for (var prop in source) {
        obj[prop] = source[prop];
      }
    }
  };

  // Rx Utils
  var addRef = Rx.internals.addRef = function (xs, r) {
    return new AnonymousObservable(function (observer) {
      return new CompositeDisposable(r.getDisposable(), xs.subscribe(observer));
    });
  };

  function arrayInitialize(count, factory) {
    var a = new Array(count);
    for (var i = 0; i < count; i++) {
      a[i] = factory();
    }
    return a;
  }

  var errorObj = {e: {}};
  var tryCatchTarget;
  function tryCatcher() {
    try {
      return tryCatchTarget.apply(this, arguments);
    } catch (e) {
      errorObj.e = e;
      return errorObj;
    }
  }
  function tryCatch(fn) {
    if (!isFunction(fn)) { throw new TypeError('fn must be a function'); }
    tryCatchTarget = fn;
    return tryCatcher;
  }
  function thrower(e) {
    throw e;
  }

  // Collections
  function IndexedItem(id, value) {
    this.id = id;
    this.value = value;
  }

  IndexedItem.prototype.compareTo = function (other) {
    var c = this.value.compareTo(other.value);
    c === 0 && (c = this.id - other.id);
    return c;
  };

  // Priority Queue for Scheduling
  var PriorityQueue = Rx.internals.PriorityQueue = function (capacity) {
    this.items = new Array(capacity);
    this.length = 0;
  };

  var priorityProto = PriorityQueue.prototype;
  priorityProto.isHigherPriority = function (left, right) {
    return this.items[left].compareTo(this.items[right]) < 0;
  };

  priorityProto.percolate = function (index) {
    if (index >= this.length || index < 0) { return; }
    var parent = index - 1 >> 1;
    if (parent < 0 || parent === index) { return; }
    if (this.isHigherPriority(index, parent)) {
      var temp = this.items[index];
      this.items[index] = this.items[parent];
      this.items[parent] = temp;
      this.percolate(parent);
    }
  };

  priorityProto.heapify = function (index) {
    +index || (index = 0);
    if (index >= this.length || index < 0) { return; }
    var left = 2 * index + 1,
        right = 2 * index + 2,
        first = index;
    if (left < this.length && this.isHigherPriority(left, first)) {
      first = left;
    }
    if (right < this.length && this.isHigherPriority(right, first)) {
      first = right;
    }
    if (first !== index) {
      var temp = this.items[index];
      this.items[index] = this.items[first];
      this.items[first] = temp;
      this.heapify(first);
    }
  };

  priorityProto.peek = function () { return this.items[0].value; };

  priorityProto.removeAt = function (index) {
    this.items[index] = this.items[--this.length];
    this.items[this.length] = undefined;
    this.heapify();
  };

  priorityProto.dequeue = function () {
    var result = this.peek();
    this.removeAt(0);
    return result;
  };

  priorityProto.enqueue = function (item) {
    var index = this.length++;
    this.items[index] = new IndexedItem(PriorityQueue.count++, item);
    this.percolate(index);
  };

  priorityProto.remove = function (item) {
    for (var i = 0; i < this.length; i++) {
      if (this.items[i].value === item) {
        this.removeAt(i);
        return true;
      }
    }
    return false;
  };
  PriorityQueue.count = 0;

  /**
   * 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();
      }
    }
  };

  /**
   * Provides a set of static methods for creating Disposables.
   * @param {Function} dispose Action to run during the first call to dispose. The action is guaranteed to be run at most once.
   */
  var Disposable = Rx.Disposable = function (action) {
    this.isDisposed = false;
    this.action = action || noop;
  };

  /** Performs the task of cleaning up resources. */
  Disposable.prototype.dispose = function () {
    if (!this.isDisposed) {
      this.action();
      this.isDisposed = true;
    }
  };

  /**
   * Creates a disposable object that invokes the specified action when disposed.
   * @param {Function} dispose Action to run during the first call to dispose. The action is guaranteed to be run at most once.
   * @return {Disposable} The disposable object that runs the given action upon disposal.
   */
  var disposableCreate = Disposable.create = function (action) { return new Disposable(action); };

  /**
   * Gets the disposable that does nothing when disposed.
   */
  var disposableEmpty = Disposable.empty = { dispose: noop };

  /**
   * Validates whether the given object is a disposable
   * @param {Object} Object to test whether it has a dispose method
   * @returns {Boolean} true if a disposable object, else false.
   */
  var isDisposable = Disposable.isDisposable = function (d) {
    return d && isFunction(d.dispose);
  };

  var checkDisposed = Disposable.checkDisposed = function (disposable) {
    if (disposable.isDisposed) { throw new ObjectDisposedError(); }
  };

  // Single assignment
  var SingleAssignmentDisposable = Rx.SingleAssignmentDisposable = function () {
    this.isDisposed = false;
    this.current = null;
  };
  SingleAssignmentDisposable.prototype.getDisposable = function () {
    return this.current;
  };
  SingleAssignmentDisposable.prototype.setDisposable = function (value) {
    if (this.current) { throw new Error('Disposable has already been assigned'); }
    var shouldDispose = this.isDisposed;
    !shouldDispose && (this.current = value);
    shouldDispose && value && value.dispose();
  };
  SingleAssignmentDisposable.prototype.dispose = function () {
    if (!this.isDisposed) {
      this.isDisposed = true;
      var old = this.current;
      this.current = null;
    }
    old && old.dispose();
  };

  // Multiple assignment disposable
  var SerialDisposable = Rx.SerialDisposable = function () {
    this.isDisposed = false;
    this.current = null;
  };
  SerialDisposable.prototype.getDisposable = function () {
    return this.current;
  };
  SerialDisposable.prototype.setDisposable = function (value) {
    var shouldDispose = this.isDisposed;
    if (!shouldDispose) {
      var old = this.current;
      this.current = value;
    }
    old && old.dispose();
    shouldDispose && value && value.dispose();
  };
  SerialDisposable.prototype.dispose = function () {
    if (!this.isDisposed) {
      this.isDisposed = true;
      var old = this.current;
      this.current = null;
    }
    old && old.dispose();
  };

  /**
   * Represents a disposable resource that only disposes its underlying disposable resource when all dependent disposable objects have been disposed.
   */
  var RefCountDisposable = Rx.RefCountDisposable = (function () {

    function InnerDisposable(disposable) {
      this.disposable = disposable;
      this.disposable.count++;
      this.isInnerDisposed = false;
    }

    InnerDisposable.prototype.dispose = function () {
      if (!this.disposable.isDisposed && !this.isInnerDisposed) {
        this.isInnerDisposed = true;
        this.disposable.count--;
        if (this.disposable.count === 0 && this.disposable.isPrimaryDisposed) {
          this.disposable.isDisposed = true;
          this.disposable.underlyingDisposable.dispose();
        }
      }
    };

    /**
     * Initializes a new instance of the RefCountDisposable with the specified disposable.
     * @constructor
     * @param {Disposable} disposable Underlying disposable.
      */
    function RefCountDisposable(disposable) {
      this.underlyingDisposable = disposable;
      this.isDisposed = false;
      this.isPrimaryDisposed = false;
      this.count = 0;
    }

    /**
     * Disposes the underlying disposable only when all dependent disposables have been disposed
     */
    RefCountDisposable.prototype.dispose = function () {
      if (!this.isDisposed && !this.isPrimaryDisposed) {
        this.isPrimaryDisposed = true;
        if (this.count === 0) {
          this.isDisposed = true;
          this.underlyingDisposable.dispose();
        }
      }
    };

    /**
     * Returns a dependent disposable that when disposed decreases the refcount on the underlying disposable.
     * @returns {Disposable} A dependent disposable contributing to the reference count that manages the underlying disposable's lifetime.
     */
    RefCountDisposable.prototype.getDisposable = function () {
      return this.isDisposed ? disposableEmpty : new InnerDisposable(this);
    };

    return RefCountDisposable;
  })();

  function ScheduledDisposable(scheduler, disposable) {
    this.scheduler = scheduler;
    this.disposable = disposable;
    this.isDisposed = false;
  }

  function scheduleItem(s, self) {
    if (!self.isDisposed) {
      self.isDisposed = true;
      self.disposable.dispose();
    }
  }

  ScheduledDisposable.prototype.dispose = function () {
    this.scheduler.scheduleWithState(this, scheduleItem);
  };

  var ScheduledItem = Rx.internals.ScheduledItem = function (scheduler, state, action, dueTime, comparer) {
    this.scheduler = scheduler;
    this.state = state;
    this.action = action;
    this.dueTime = dueTime;
    this.comparer = comparer || defaultSubComparer;
    this.disposable = new SingleAssignmentDisposable();
  }

  ScheduledItem.prototype.invoke = function () {
    this.disposable.setDisposable(this.invokeCore());
  };

  ScheduledItem.prototype.compareTo = function (other) {
    return this.comparer(this.dueTime, other.dueTime);
  };

  ScheduledItem.prototype.isCancelled = function () {
    return this.disposable.isDisposed;
  };

  ScheduledItem.prototype.invokeCore = function () {
    return this.action(this.scheduler, this.state);
  };

  /** Provides a set of static properties to access commonly used schedulers. */
  var Scheduler = Rx.Scheduler = (function () {

    function Scheduler(now, schedule, scheduleRelative, scheduleAbsolute) {
      this.now = now;
      this._schedule = schedule;
      this._scheduleRelative = scheduleRelative;
      this._scheduleAbsolute = scheduleAbsolute;
    }

    /** Determines whether the given object is a scheduler */
    Scheduler.isScheduler = function (s) {
      return s instanceof Scheduler;
    }

    function invokeAction(scheduler, action) {
      action();
      return disposableEmpty;
    }

    var schedulerProto = Scheduler.prototype;

    /**
     * Schedules an action to be executed.
     * @param {Function} action Action to execute.
     * @returns {Disposable} The disposable object used to cancel the scheduled action (best effort).
     */
    schedulerProto.schedule = function (action) {
      return this._schedule(action, invokeAction);
    };

    /**
     * Schedules an action to be executed.
     * @param state State passed to the action to be executed.
     * @param {Function} action Action to be executed.
     * @returns {Disposable} The disposable object used to cancel the scheduled action (best effort).
     */
    schedulerProto.scheduleWithState = function (state, action) {
      return this._schedule(state, action);
    };

    /**
     * Schedules an action to be executed after the specified relative due time.
     * @param {Function} action Action to execute.
     * @param {Number} dueTime Relative time after which to execute the action.
     * @returns {Disposable} The disposable object used to cancel the scheduled action (best effort).
     */
    schedulerProto.scheduleWithRelative = function (dueTime, action) {
      return this._scheduleRelative(action, dueTime, invokeAction);
    };

    /**
     * Schedules an action to be executed after dueTime.
     * @param state State passed to the action to be executed.
     * @param {Function} action Action to be executed.
     * @param {Number} dueTime Relative time after which to execute the action.
     * @returns {Disposable} The disposable object used to cancel the scheduled action (best effort).
     */
    schedulerProto.scheduleWithRelativeAndState = function (state, dueTime, action) {
      return this._scheduleRelative(state, dueTime, action);
    };

    /**
     * Schedules an action to be executed at the specified absolute due time.
     * @param {Function} action Action to execute.
     * @param {Number} dueTime Absolute time at which to execute the action.
     * @returns {Disposable} The disposable object used to cancel the scheduled action (best effort).
      */
    schedulerProto.scheduleWithAbsolute = function (dueTime, action) {
      return this._scheduleAbsolute(action, dueTime, invokeAction);
    };

    /**
     * Schedules an action to be executed at dueTime.
     * @param {Mixed} state State passed to the action to be executed.
     * @param {Function} action Action to be executed.
     * @param {Number}dueTime Absolute time at which to execute the action.
     * @returns {Disposable} The disposable object used to cancel the scheduled action (best effort).
     */
    schedulerProto.scheduleWithAbsoluteAndState = function (state, dueTime, action) {
      return this._scheduleAbsolute(state, dueTime, action);
    };

    /** Gets the current time according to the local machine's system clock. */
    Scheduler.now = defaultNow;

    /**
     * Normalizes the specified TimeSpan value to a positive value.
     * @param {Number} timeSpan The time span value to normalize.
     * @returns {Number} The specified TimeSpan value if it is zero or positive; otherwise, 0
     */
    Scheduler.normalize = function (timeSpan) {
      timeSpan < 0 && (timeSpan = 0);
      return timeSpan;
    };

    return Scheduler;
  }());

  var normalizeTime = Scheduler.normalize, isScheduler = Scheduler.isScheduler;

  (function (schedulerProto) {

    function invokeRecImmediate(scheduler, pair) {
      var state = pair[0], action = pair[1], group = new CompositeDisposable();

      function recursiveAction(state1) {
        action(state1, function (state2) {
          var isAdded = false, isDone = false,
          d = scheduler.scheduleWithState(state2, function (scheduler1, state3) {
            if (isAdded) {
              group.remove(d);
            } else {
              isDone = true;
            }
            recursiveAction(state3);
            return disposableEmpty;
          });
          if (!isDone) {
            group.add(d);
            isAdded = true;
          }
        });
      }

      recursiveAction(state);
      return group;
    }

    function invokeRecDate(scheduler, pair, method) {
      var state = pair[0], action = pair[1], group = new CompositeDisposable();
      function recursiveAction(state1) {
        action(state1, function (state2, dueTime1) {
          var isAdded = false, isDone = false,
          d = scheduler[method](state2, dueTime1, function (scheduler1, state3) {
            if (isAdded) {
              group.remove(d);
            } else {
              isDone = true;
            }
            recursiveAction(state3);
            return disposableEmpty;
          });
          if (!isDone) {
            group.add(d);
            isAdded = true;
          }
        });
      };
      recursiveAction(state);
      return group;
    }

    function scheduleInnerRecursive(action, self) {
      action(function(dt) { self(action, dt); });
    }

    /**
     * Schedules an action to be executed recursively.
     * @param {Function} action Action to execute recursively. The parameter passed to the action is used to trigger recursive scheduling of the action.
     * @returns {Disposable} The disposable object used to cancel the scheduled action (best effort).
     */
    schedulerProto.scheduleRecursive = function (action) {
      return this.scheduleRecursiveWithState(action, function (_action, self) {
        _action(function () { self(_action); }); });
    };

    /**
     * Schedules an action to be executed recursively.
     * @param {Mixed} state State passed to the action to be executed.
     * @param {Function} action Action to execute recursively. The last parameter passed to the action is used to trigger recursive scheduling of the action, passing in recursive invocation state.
     * @returns {Disposable} The disposable object used to cancel the scheduled action (best effort).
     */
    schedulerProto.scheduleRecursiveWithState = function (state, action) {
      return this.scheduleWithState([state, action], invokeRecImmediate);
    };

    /**
     * Schedules an action to be executed recursively after a specified relative due time.
     * @param {Function} action Action to execute recursively. The parameter passed to the action is used to trigger recursive scheduling of the action at the specified relative time.
     * @param {Number}dueTime Relative time after which to execute the action for the first time.
     * @returns {Disposable} The disposable object used to cancel the scheduled action (best effort).
     */
    schedulerProto.scheduleRecursiveWithRelative = function (dueTime, action) {
      return this.scheduleRecursiveWithRelativeAndState(action, dueTime, scheduleInnerRecursive);
    };

    /**
     * Schedules an action to be executed recursively after a specified relative due time.
     * @param {Mixed} state State passed to the action to be executed.
     * @param {Function} action Action to execute recursively. The last parameter passed to the action is used to trigger recursive scheduling of the action, passing in the recursive due time and invocation state.
     * @param {Number}dueTime Relative time after which to execute the action for the first time.
     * @returns {Disposable} The disposable object used to cancel the scheduled action (best effort).
     */
    schedulerProto.scheduleRecursiveWithRelativeAndState = function (state, dueTime, action) {
      return this._scheduleRelative([state, action], dueTime, function (s, p) {
        return invokeRecDate(s, p, 'scheduleWithRelativeAndState');
      });
    };

    /**
     * Schedules an action to be executed recursively at a specified absolute due time.
     * @param {Function} action Action to execute recursively. The parameter passed to the action is used to trigger recursive scheduling of the action at the specified absolute time.
     * @param {Number}dueTime Absolute time at which to execute the action for the first time.
     * @returns {Disposable} The disposable object used to cancel the scheduled action (best effort).
     */
    schedulerProto.scheduleRecursiveWithAbsolute = function (dueTime, action) {
      return this.scheduleRecursiveWithAbsoluteAndState(action, dueTime, scheduleInnerRecursive);
    };

    /**
     * Schedules an action to be executed recursively at a specified absolute due time.
     * @param {Mixed} state State passed to the action to be executed.
     * @param {Function} action Action to execute recursively. The last parameter passed to the action is used to trigger recursive scheduling of the action, passing in the recursive due time and invocation state.
     * @param {Number}dueTime Absolute time at which to execute the action for the first time.
     * @returns {Disposable} The disposable object used to cancel the scheduled action (best effort).
     */
    schedulerProto.scheduleRecursiveWithAbsoluteAndState = function (state, dueTime, action) {
      return this._scheduleAbsolute([state, action], dueTime, function (s, p) {
        return invokeRecDate(s, p, 'scheduleWithAbsoluteAndState');
      });
    };
  }(Scheduler.prototype));

  (function (schedulerProto) {

    /**
     * Schedules a periodic piece of work by dynamically discovering the scheduler's capabilities. The periodic task will be scheduled using window.setInterval for the base implementation.
     * @param {Number} period Period for running the work periodically.
     * @param {Function} action Action to be executed.
     * @returns {Disposable} The disposable object used to cancel the scheduled recurring action (best effort).
     */
    Scheduler.prototype.schedulePeriodic = function (period, action) {
      return this.schedulePeriodicWithState(null, period, action);
    };

    /**
     * Schedules a periodic piece of work by dynamically discovering the scheduler's capabilities. The periodic task will be scheduled using window.setInterval for the base implementation.
     * @param {Mixed} state Initial state passed to the action upon the first iteration.
     * @param {Number} period Period for running the work periodically.
     * @param {Function} action Action to be executed, potentially updating the state.
     * @returns {Disposable} The disposable object used to cancel the scheduled recurring action (best effort).
     */
    Scheduler.prototype.schedulePeriodicWithState = function(state, period, action) {
      if (typeof root.setInterval === 'undefined') { throw new NotSupportedError(); }
      period = normalizeTime(period);
      var s = state, id = root.setInterval(function () { s = action(s); }, period);
      return disposableCreate(function () { root.clearInterval(id); });
    };

  }(Scheduler.prototype));

  (function (schedulerProto) {
    /**
     * Returns a scheduler that wraps the original scheduler, adding exception handling for scheduled actions.
     * @param {Function} handler Handler that's run if an exception is caught. The exception will be rethrown if the handler returns false.
     * @returns {Scheduler} Wrapper around the original scheduler, enforcing exception handling.
     */
    schedulerProto.catchError = schedulerProto['catch'] = function (handler) {
      return new CatchScheduler(this, handler);
    };
  }(Scheduler.prototype));

  var SchedulePeriodicRecursive = Rx.internals.SchedulePeriodicRecursive = (function () {
    function tick(command, recurse) {
      recurse(0, this._period);
      try {
        this._state = this._action(this._state);
      } catch (e) {
        this._cancel.dispose();
        throw e;
      }
    }

    function SchedulePeriodicRecursive(scheduler, state, period, action) {
      this._scheduler = scheduler;
      this._state = state;
      this._period = period;
      this._action = action;
    }

    SchedulePeriodicRecursive.prototype.start = function () {
      var d = new SingleAssignmentDisposable();
      this._cancel = d;
      d.setDisposable(this._scheduler.scheduleRecursiveWithRelativeAndState(0, this._period, tick.bind(this)));

      return d;
    };

    return SchedulePeriodicRecursive;
  }());

  /** Gets a scheduler that schedules work immediately on the current thread. */
  var immediateScheduler = Scheduler.immediate = (function () {
    function scheduleNow(state, action) { return action(this, state); }
    return new Scheduler(defaultNow, scheduleNow, notSupported, notSupported);
  }());

  /**
   * Gets a scheduler that schedules work as soon as possible on the current thread.
   */
  var currentThreadScheduler = Scheduler.currentThread = (function () {
    var queue;

    function runTrampoline () {
      while (queue.length > 0) {
        var item = queue.dequeue();
        !item.isCancelled() && item.invoke();
      }
    }

    function scheduleNow(state, action) {
      var si = new ScheduledItem(this, state, action, this.now());

      if (!queue) {
        queue = new PriorityQueue(4);
        queue.enqueue(si);

        var result = tryCatch(runTrampoline)();
        queue = null;
        if (result === errorObj) { return thrower(result.e); }
      } else {
        queue.enqueue(si);
      }
      return si.disposable;
    }

    var currentScheduler = new Scheduler(defaultNow, scheduleNow, notSupported, notSupported);
    currentScheduler.scheduleRequired = function () { return !queue; };

    return currentScheduler;
  }());

  var scheduleMethod, clearMethod;

  var localTimer = (function () {
    var localSetTimeout, localClearTimeout = noop;
    if (!!root.setTimeout) {
      localSetTimeout = root.setTimeout;
      localClearTimeout = root.clearTimeout;
    } else if (!!root.WScript) {
      localSetTimeout = function (fn, time) {
        root.WScript.Sleep(time);
        fn();
      };
    } else {
      throw new NotSupportedError();
    }

    return {
      setTimeout: localSetTimeout,
      clearTimeout: localClearTimeout
    };
  }());
  var localSetTimeout = localTimer.setTimeout,
    localClearTimeout = localTimer.clearTimeout;

  (function () {

    var nextHandle = 1, tasksByHandle = {}, currentlyRunning = false;

    clearMethod = function (handle) {
      delete tasksByHandle[handle];
    };

    function runTask(handle) {
      if (currentlyRunning) {
        localSetTimeout(function () { runTask(handle) }, 0);
      } else {
        var task = tasksByHandle[handle];
        if (task) {
          currentlyRunning = true;
          var result = tryCatch(task)();
          clearMethod(handle);
          currentlyRunning = false;
          if (result === errorObj) { return thrower(result.e); }
        }
      }
    }

    var reNative = RegExp('^' +
      String(toString)
        .replace(/[.*+?^${}()|[\]\\]/g, '\\$&')
        .replace(/toString| for [^\]]+/g, '.*?') + '$'
    );

    var setImmediate = typeof (setImmediate = freeGlobal && moduleExports && freeGlobal.setImmediate) == 'function' &&
      !reNative.test(setImmediate) && setImmediate;

    function postMessageSupported () {
      // Ensure not in a worker
      if (!root.postMessage || root.importScripts) { return false; }
      var isAsync = false, oldHandler = root.onmessage;
      // Test for async
      root.onmessage = function () { isAsync = true; };
      root.postMessage('', '*');
      root.onmessage = oldHandler;

      return isAsync;
    }

    // Use in order, setImmediate, nextTick, postMessage, MessageChannel, script readystatechanged, setTimeout
    if (isFunction(setImmediate)) {
      scheduleMethod = function (action) {
        var id = nextHandle++;
        tasksByHandle[id] = action;
        setImmediate(function () { runTask(id); });

        return id;
      };
    } else if (typeof process !== 'undefined' && {}.toString.call(process) === '[object process]') {
      scheduleMethod = function (action) {
        var id = nextHandle++;
        tasksByHandle[id] = action;
        process.nextTick(function () { runTask(id); });

        return id;
      };
    } else if (postMessageSupported()) {
      var MSG_PREFIX = 'ms.rx.schedule' + Math.random();

      function onGlobalPostMessage(event) {
        // Only if we're a match to avoid any other global events
        if (typeof event.data === 'string' && event.data.substring(0, MSG_PREFIX.length) === MSG_PREFIX) {
          runTask(event.data.substring(MSG_PREFIX.length));
        }
      }

      if (root.addEventListener) {
        root.addEventListener('message', onGlobalPostMessage, false);
      } else if (root.attachEvent) {
        root.attachEvent('onmessage', onGlobalPostMessage);
      } else {
        root.onmessage = onGlobalPostMessage;
      }

      scheduleMethod = function (action) {
        var id = nextHandle++;
        tasksByHandle[id] = action;
        root.postMessage(MSG_PREFIX + currentId, '*');
        return id;
      };
    } else if (!!root.MessageChannel) {
      var channel = new root.MessageChannel();

      channel.port1.onmessage = function (e) { runTask(e.data); };

      scheduleMethod = function (action) {
        var id = nextHandle++;
        tasksByHandle[id] = action;
        channel.port2.postMessage(id);
        return id;
      };
    } else if ('document' in root && 'onreadystatechange' in root.document.createElement('script')) {

      scheduleMethod = function (action) {
        var scriptElement = root.document.createElement('script');
        var id = nextHandle++;
        tasksByHandle[id] = action;

        scriptElement.onreadystatechange = function () {
          runTask(id);
          scriptElement.onreadystatechange = null;
          scriptElement.parentNode.removeChild(scriptElement);
          scriptElement = null;
        };
        root.document.documentElement.appendChild(scriptElement);
        return id;
      };

    } else {
      scheduleMethod = function (action) {
        var id = nextHandle++;
        tasksByHandle[id] = action;
        localSetTimeout(function () {
          runTask(id);
        }, 0);

        return id;
      };
    }
  }());

  /**
   * Gets a scheduler that schedules work via a timed callback based upon platform.
   */
  var timeoutScheduler = Scheduler.timeout = Scheduler['default'] = (function () {

    function scheduleNow(state, action) {
      var scheduler = this, disposable = new SingleAssignmentDisposable();
      var id = scheduleMethod(function () {
        !disposable.isDisposed && disposable.setDisposable(action(scheduler, state));
      });
      return new CompositeDisposable(disposable, disposableCreate(function () {
        clearMethod(id);
      }));
    }

    function scheduleRelative(state, dueTime, action) {
      var scheduler = this, dt = Scheduler.normalize(dueTime), disposable = new SingleAssignmentDisposable();
      if (dt === 0) { return scheduler.scheduleWithState(state, action); }
      var id = localSetTimeout(function () {
        !disposable.isDisposed && disposable.setDisposable(action(scheduler, state));
      }, dt);
      return new CompositeDisposable(disposable, disposableCreate(function () {
        localClearTimeout(id);
      }));
    }

    function scheduleAbsolute(state, dueTime, action) {
      return this.scheduleWithRelativeAndState(state, dueTime - this.now(), action);
    }

    return new Scheduler(defaultNow, scheduleNow, scheduleRelative, scheduleAbsolute);
  })();

  var CatchScheduler = (function (__super__) {

    function scheduleNow(state, action) {
      return this._scheduler.scheduleWithState(state, this._wrap(action));
    }

    function scheduleRelative(state, dueTime, action) {
      return this._scheduler.scheduleWithRelativeAndState(state, dueTime, this._wrap(action));
    }

    function scheduleAbsolute(state, dueTime, action) {
      return this._scheduler.scheduleWithAbsoluteAndState(state, dueTime, this._wrap(action));
    }

    inherits(CatchScheduler, __super__);

    function CatchScheduler(scheduler, handler) {
      this._scheduler = scheduler;
      this._handler = handler;
      this._recursiveOriginal = null;
      this._recursiveWrapper = null;
      __super__.call(this, this._scheduler.now.bind(this._scheduler), scheduleNow, scheduleRelative, scheduleAbsolute);
    }

    CatchScheduler.prototype._clone = function (scheduler) {
        return new CatchScheduler(scheduler, this._handler);
    };

    CatchScheduler.prototype._wrap = function (action) {
      var parent = this;
      return function (self, state) {
        try {
          return action(parent._getRecursiveWrapper(self), state);
        } catch (e) {
          if (!parent._handler(e)) { throw e; }
          return disposableEmpty;
        }
      };
    };

    CatchScheduler.prototype._getRecursiveWrapper = function (scheduler) {
      if (this._recursiveOriginal !== scheduler) {
        this._recursiveOriginal = scheduler;
        var wrapper = this._clone(scheduler);
        wrapper._recursiveOriginal = scheduler;
        wrapper._recursiveWrapper = wrapper;
        this._recursiveWrapper = wrapper;
      }
      return this._recursiveWrapper;
    };

    CatchScheduler.prototype.schedulePeriodicWithState = function (state, period, action) {
      var self = this, failed = false, d = new SingleAssignmentDisposable();

      d.setDisposable(this._scheduler.schedulePeriodicWithState(state, period, function (state1) {
        if (failed) { return null; }
        try {
          return action(state1);
        } catch (e) {
          failed = true;
          if (!self._handler(e)) { throw e; }
          d.dispose();
          return null;
        }
      }));

      return d;
    };

    return CatchScheduler;
  }(Scheduler));

  /**
   *  Represents a notification to an observer.
   */
  var Notification = Rx.Notification = (function () {
    function Notification(kind, value, exception, accept, acceptObservable, toString) {
      this.kind = kind;
      this.value = value;
      this.exception = exception;
      this._accept = accept;
      this._acceptObservable = acceptObservable;
      this.toString = toString;
    }

    /**
     * Invokes the delegate corresponding to the notification or the observer's method corresponding to the notification and returns the produced result.
     *
     * @memberOf Notification
     * @param {Any} observerOrOnNext Delegate to invoke for an OnNext notification or Observer to invoke the notification on..
     * @param {Function} onError Delegate to invoke for an OnError notification.
     * @param {Function} onCompleted Delegate to invoke for an OnCompleted notification.
     * @returns {Any} Result produced by the observation.
     */
    Notification.prototype.accept = function (observerOrOnNext, onError, onCompleted) {
      return observerOrOnNext && typeof observerOrOnNext === 'object' ?
        this._acceptObservable(observerOrOnNext) :
        this._accept(observerOrOnNext, onError, onCompleted);
    };

    /**
     * Returns an observable sequence with a single notification.
     *
     * @memberOf Notifications
     * @param {Scheduler} [scheduler] Scheduler to send out the notification calls on.
     * @returns {Observable} The observable sequence that surfaces the behavior of the notification upon subscription.
     */
    Notification.prototype.toObservable = function (scheduler) {
      var self = this;
      isScheduler(scheduler) || (scheduler = immediateScheduler);
      return new AnonymousObservable(function (observer) {
        return scheduler.scheduleWithState(self, function (_, notification) {
          notification._acceptObservable(observer);
          notification.kind === 'N' && observer.onCompleted();
        });
      });
    };

    return Notification;
  })();

  /**
   * Creates an object that represents an OnNext notification to an observer.
   * @param {Any} value The value contained in the notification.
   * @returns {Notification} The OnNext notification containing the value.
   */
  var notificationCreateOnNext = Notification.createOnNext = (function () {
      function _accept(onNext) { return onNext(this.value); }
      function _acceptObservable(observer) { return observer.onNext(this.value); }
      function toString() { return 'OnNext(' + this.value + ')'; }

      return function (value) {
        return new Notification('N', value, null, _accept, _acceptObservable, toString);
      };
  }());

  /**
   * Creates an object that represents an OnError notification to an observer.
   * @param {Any} error The exception contained in the notification.
   * @returns {Notification} The OnError notification containing the exception.
   */
  var notificationCreateOnError = Notification.createOnError = (function () {
    function _accept (onNext, onError) { return onError(this.exception); }
    function _acceptObservable(observer) { return observer.onError(this.exception); }
    function toString () { return 'OnError(' + this.exception + ')'; }

    return function (e) {
      return new Notification('E', null, e, _accept, _acceptObservable, toString);
    };
  }());

  /**
   * Creates an object that represents an OnCompleted notification to an observer.
   * @returns {Notification} The OnCompleted notification.
   */
  var notificationCreateOnCompleted = Notification.createOnCompleted = (function () {
    function _accept (onNext, onError, onCompleted) { return onCompleted(); }
    function _acceptObservable(observer) { return observer.onCompleted(); }
    function toString () { return 'OnCompleted()'; }

    return function () {
      return new Notification('C', null, null, _accept, _acceptObservable, toString);
    };
  }());

  var Enumerator = Rx.internals.Enumerator = function (next) {
    this._next = next;
  };

  Enumerator.prototype.next = function () {
    return this._next();
  };

  Enumerator.prototype[$iterator$] = function () { return this; }

  var Enumerable = Rx.internals.Enumerable = function (iterator) {
    this._iterator = iterator;
  };

  Enumerable.prototype[$iterator$] = function () {
    return this._iterator();
  };

  Enumerable.prototype.concat = function () {
    var sources = this;
    return new AnonymousObservable(function (o) {
      var e = sources[$iterator$]();

      var isDisposed, subscription = new SerialDisposable();
      var cancelable = immediateScheduler.scheduleRecursive(function (self) {
        if (isDisposed) { return; }
        try {
          var currentItem = e.next();
        } catch (ex) {
          return o.onError(ex);
        }

        if (currentItem.done) {
          return o.onCompleted();
        }

        // Check if promise
        var currentValue = currentItem.value;
        isPromise(currentValue) && (currentValue = observableFromPromise(currentValue));

        var d = new SingleAssignmentDisposable();
        subscription.setDisposable(d);
        d.setDisposable(currentValue.subscribe(
          function(x) { o.onNext(x); },
          function(err) { o.onError(err); },
          self)
        );
      });

      return new CompositeDisposable(subscription, cancelable, disposableCreate(function () {
        isDisposed = true;
      }));
    });
  };

  Enumerable.prototype.catchError = function () {
    var sources = this;
    return new AnonymousObservable(function (o) {
      var e = sources[$iterator$]();

      var isDisposed, subscription = new SerialDisposable();
      var cancelable = immediateScheduler.scheduleRecursiveWithState(null, function (lastException, self) {
        if (isDisposed) { return; }

        try {
          var currentItem = e.next();
        } catch (ex) {
          return observer.onError(ex);
        }

        if (currentItem.done) {
          if (lastException !== null) {
            o.onError(lastException);
          } else {
            o.onCompleted();
          }
          return;
        }

        // Check if promise
        var currentValue = currentItem.value;
        isPromise(currentValue) && (currentValue = observableFromPromise(currentValue));

        var d = new SingleAssignmentDisposable();
        subscription.setDisposable(d);
        d.setDisposable(currentValue.subscribe(
          function(x) { o.onNext(x); },
          self,
          function() { o.onCompleted(); }));
      });
      return new CompositeDisposable(subscription, cancelable, disposableCreate(function () {
        isDisposed = true;
      }));
    });
  };


  Enumerable.prototype.catchErrorWhen = function (notificationHandler) {
    var sources = this;
    return new AnonymousObservable(function (o) {
      var exceptions = new Subject(),
        notifier = new Subject(),
        handled = notificationHandler(exceptions),
        notificationDisposable = handled.subscribe(notifier);

      var e = sources[$iterator$]();

      var isDisposed,
        lastException,
        subscription = new SerialDisposable();
      var cancelable = immediateScheduler.scheduleRecursive(function (self) {
        if (isDisposed) { return; }

        try {
          var currentItem = e.next();
        } catch (ex) {
          return o.onError(ex);
        }

        if (currentItem.done) {
          if (lastException) {
            o.onError(lastException);
          } else {
            o.onCompleted();
          }
          return;
        }

        // Check if promise
        var currentValue = currentItem.value;
        isPromise(currentValue) && (currentValue = observableFromPromise(currentValue));

        var outer = new SingleAssignmentDisposable();
        var inner = new SingleAssignmentDisposable();
        subscription.setDisposable(new CompositeDisposable(inner, outer));
        outer.setDisposable(currentValue.subscribe(
          function(x) { o.onNext(x); },
          function (exn) {
            inner.setDisposable(notifier.subscribe(self, function(ex) {
              o.onError(ex);
            }, function() {
              o.onCompleted();
            }));

            exceptions.onNext(exn);
          },
          function() { o.onCompleted(); }));
      });

      return new CompositeDisposable(notificationDisposable, subscription, cancelable, disposableCreate(function () {
        isDisposed = true;
      }));
    });
  };

  var enumerableRepeat = Enumerable.repeat = function (value, repeatCount) {
    if (repeatCount == null) { repeatCount = -1; }
    return new Enumerable(function () {
      var left = repeatCount;
      return new Enumerator(function () {
        if (left === 0) { return doneEnumerator; }
        if (left > 0) { left--; }
        return { done: false, value: value };
      });
    });
  };

  var enumerableOf = Enumerable.of = function (source, selector, thisArg) {
    if (selector) {
      var selectorFn = bindCallback(selector, thisArg, 3);
    }
    return new Enumerable(function () {
      var index = -1;
      return new Enumerator(
        function () {
          return ++index < source.length ?
            { done: false, value: !selector ? source[index] : selectorFn(source[index], index, source) } :
            doneEnumerator;
        });
    });
  };

  /**
   * Supports push-style iteration over an observable sequence.
   */
  var Observer = Rx.Observer = function () { };

  /**
   *  Creates a notification callback from an observer.
   * @returns The action that forwards its input notification to the underlying observer.
   */
  Observer.prototype.toNotifier = function () {
    var observer = this;
    return function (n) { return n.accept(observer); };
  };

  /**
   *  Hides the identity of an observer.
   * @returns An observer that hides the identity of the specified observer.
   */
  Observer.prototype.asObserver = function () {
    return new AnonymousObserver(this.onNext.bind(this), this.onError.bind(this), this.onCompleted.bind(this));
  };

  /**
   *  Checks access to the observer for grammar violations. This includes checking for multiple OnError or OnCompleted calls, as well as reentrancy in any of the observer methods.
   *  If a violation is detected, an Error is thrown from the offending observer method call.
   * @returns An observer that checks callbacks invocations against the observer grammar and, if the checks pass, forwards those to the specified observer.
   */
  Observer.prototype.checked = function () { return new CheckedObserver(this); };

  /**
   *  Creates an observer from the specified OnNext, along with optional OnError, and OnCompleted actions.
   * @param {Function} [onNext] Observer's OnNext action implementation.
   * @param {Function} [onError] Observer's OnError action implementation.
   * @param {Function} [onCompleted] Observer's OnCompleted action implementation.
   * @returns {Observer} The observer object implemented using the given actions.
   */
  var observerCreate = Observer.create = function (onNext, onError, onCompleted) {
    onNext || (onNext = noop);
    onError || (onError = defaultError);
    onCompleted || (onCompleted = noop);
    return new AnonymousObserver(onNext, onError, onCompleted);
  };

  /**
   *  Creates an observer from a notification callback.
   *
   * @static
   * @memberOf Observer
   * @param {Function} handler Action that handles a notification.
   * @returns The observer object that invokes the specified handler using a notification corresponding to each message it receives.
   */
  Observer.fromNotifier = function (handler, thisArg) {
    return new AnonymousObserver(function (x) {
      return handler.call(thisArg, notificationCreateOnNext(x));
    }, function (e) {
      return handler.call(thisArg, notificationCreateOnError(e));
    }, function () {
      return handler.call(thisArg, notificationCreateOnCompleted());
    });
  };

  /**
   * Schedules the invocation of observer methods on the given scheduler.
   * @param {Scheduler} scheduler Scheduler to schedule observer messages on.
   * @returns {Observer} Observer whose messages are scheduled on the given scheduler.
   */
  Observer.prototype.notifyOn = function (scheduler) {
    return new ObserveOnObserver(scheduler, this);
  };

  Observer.prototype.makeSafe = function(disposable) {
    return new AnonymousSafeObserver(this._onNext, this._onError, this._onCompleted, disposable);
  };

  /**
   * Abstract base class for implementations of the Observer class.
   * This base class enforces the grammar of observers where OnError and OnCompleted are terminal messages.
   */
  var AbstractObserver = Rx.internals.AbstractObserver = (function (__super__) {
    inherits(AbstractObserver, __super__);

    /**
     * Creates a new observer in a non-stopped state.
     */
    function AbstractObserver() {
      this.isStopped = false;
      __super__.call(this);
    }

    // Must be implemented by other observers
    AbstractObserver.prototype.next = notImplemented;
    AbstractObserver.prototype.error = notImplemented;
    AbstractObserver.prototype.completed = notImplemented;

    /**
     * Notifies the observer of a new element in the sequence.
     * @param {Any} value Next element in the sequence.
     */
    AbstractObserver.prototype.onNext = function (value) {
      if (!this.isStopped) { this.next(value); }
    };

    /**
     * Notifies the observer that an exception has occurred.
     * @param {Any} error The error that has occurred.
     */
    AbstractObserver.prototype.onError = function (error) {
      if (!this.isStopped) {
        this.isStopped = true;
        this.error(error);
      }
    };

    /**
     * Notifies the observer of the end of the sequence.
     */
    AbstractObserver.prototype.onCompleted = function () {
      if (!this.isStopped) {
        this.isStopped = true;
        this.completed();
      }
    };

    /**
     * Disposes the observer, causing it to transition to the stopped state.
     */
    AbstractObserver.prototype.dispose = function () {
      this.isStopped = true;
    };

    AbstractObserver.prototype.fail = function (e) {
      if (!this.isStopped) {
        this.isStopped = true;
        this.error(e);
        return true;
      }

      return false;
    };

    return AbstractObserver;
  }(Observer));

  /**
   * Class to create an Observer instance from delegate-based implementations of the on* methods.
   */
  var AnonymousObserver = Rx.AnonymousObserver = (function (__super__) {
    inherits(AnonymousObserver, __super__);

    /**
     * Creates an observer from the specified OnNext, OnError, and OnCompleted actions.
     * @param {Any} onNext Observer's OnNext action implementation.
     * @param {Any} onError Observer's OnError action implementation.
     * @param {Any} onCompleted Observer's OnCompleted action implementation.
     */
    function AnonymousObserver(onNext, onError, onCompleted) {
      __super__.call(this);
      this._onNext = onNext;
      this._onError = onError;
      this._onCompleted = onCompleted;
    }

    /**
     * Calls the onNext action.
     * @param {Any} value Next element in the sequence.
     */
    AnonymousObserver.prototype.next = function (value) {
      this._onNext(value);
    };

    /**
     * Calls the onError action.
     * @param {Any} error The error that has occurred.
     */
    AnonymousObserver.prototype.error = function (error) {
      this._onError(error);
    };

    /**
     *  Calls the onCompleted action.
     */
    AnonymousObserver.prototype.completed = function () {
      this._onCompleted();
    };

    return AnonymousObserver;
  }(AbstractObserver));

  var CheckedObserver = (function (__super__) {
    inherits(CheckedObserver, __super__);

    function CheckedObserver(observer) {
      __super__.call(this);
      this._observer = observer;
      this._state = 0; // 0 - idle, 1 - busy, 2 - done
    }

    var CheckedObserverPrototype = CheckedObserver.prototype;

    CheckedObserverPrototype.onNext = function (value) {
      this.checkAccess();
      var res = tryCatch(this._observer.onNext).call(this._observer, value);
      this._state = 0;
      res === errorObj && thrower(res.e);
    };

    CheckedObserverPrototype.onError = function (err) {
      this.checkAccess();
      var res = tryCatch(this._observer.onError).call(this._observer, err);
      this._state = 2;
      res === errorObj && thrower(res.e);
    };

    CheckedObserverPrototype.onCompleted = function () {
      this.checkAccess();
      var res = tryCatch(this._observer.onCompleted).call(this._observer);
      this._state = 2;
      res === errorObj && thrower(res.e);
    };

    CheckedObserverPrototype.checkAccess = function () {
      if (this._state === 1) { throw new Error('Re-entrancy detected'); }
      if (this._state === 2) { throw new Error('Observer completed'); }
      if (this._state === 0) { this._state = 1; }
    };

    return CheckedObserver;
  }(Observer));

  var ScheduledObserver = Rx.internals.ScheduledObserver = (function (__super__) {
    inherits(ScheduledObserver, __super__);

    function ScheduledObserver(scheduler, observer) {
      __super__.call(this);
      this.scheduler = scheduler;
      this.observer = observer;
      this.isAcquired = false;
      this.hasFaulted = false;
      this.queue = [];
      this.disposable = new SerialDisposable();
    }

    ScheduledObserver.prototype.next = function (value) {
      var self = this;
      this.queue.push(function () { self.observer.onNext(value); });
    };

    ScheduledObserver.prototype.error = function (e) {
      var self = this;
      this.queue.push(function () { self.observer.onError(e); });
    };

    ScheduledObserver.prototype.completed = function () {
      var self = this;
      this.queue.push(function () { self.observer.onCompleted(); });
    };

    ScheduledObserver.prototype.ensureActive = function () {
      var isOwner = false, parent = this;
      if (!this.hasFaulted && this.queue.length > 0) {
        isOwner = !this.isAcquired;
        this.isAcquired = true;
      }
      if (isOwner) {
        this.disposable.setDisposable(this.scheduler.scheduleRecursive(function (self) {
          var work;
          if (parent.queue.length > 0) {
            work = parent.queue.shift();
          } else {
            parent.isAcquired = false;
            return;
          }
          try {
            work();
          } catch (ex) {
            parent.queue = [];
            parent.hasFaulted = true;
            throw ex;
          }
          self();
        }));
      }
    };

    ScheduledObserver.prototype.dispose = function () {
      __super__.prototype.dispose.call(this);
      this.disposable.dispose();
    };

    return ScheduledObserver;
  }(AbstractObserver));

  var ObserveOnObserver = (function (__super__) {
    inherits(ObserveOnObserver, __super__);

    function ObserveOnObserver(scheduler, observer, cancel) {
      __super__.call(this, scheduler, observer);
      this._cancel = cancel;
    }

    ObserveOnObserver.prototype.next = function (value) {
      __super__.prototype.next.call(this, value);
      this.ensureActive();
    };

    ObserveOnObserver.prototype.error = function (e) {
      __super__.prototype.error.call(this, e);
      this.ensureActive();
    };

    ObserveOnObserver.prototype.completed = function () {
      __super__.prototype.completed.call(this);
      this.ensureActive();
    };

    ObserveOnObserver.prototype.dispose = function () {
      __super__.prototype.dispose.call(this);
      this._cancel && this._cancel.dispose();
      this._cancel = null;
    };

    return ObserveOnObserver;
  })(ScheduledObserver);

  var observableProto;

  /**
   * Represents a push-style collection.
   */
  var Observable = Rx.Observable = (function () {

    function Observable(subscribe) {
      if (Rx.config.longStackSupport && hasStacks) {
        try {
          throw new Error();
        } catch (e) {
          this.stack = e.stack.substring(e.stack.indexOf("\n") + 1);
        }

        var self = this;
        this._subscribe = function (observer) {
          var oldOnError = observer.onError.bind(observer);

          observer.onError = function (err) {
            makeStackTraceLong(err, self);
            oldOnError(err);
          };

          return subscribe.call(self, observer);
        };
      } else {
        this._subscribe = subscribe;
      }
    }

    observableProto = Observable.prototype;

    /**
     *  Subscribes an observer to the observable sequence.
     *  @param {Mixed} [observerOrOnNext] The object that is to receive notifications or an action to invoke for each element in the observable sequence.
     *  @param {Function} [onError] Action to invoke upon exceptional termination of the observable sequence.
     *  @param {Function} [onCompleted] Action to invoke upon graceful termination of the observable sequence.
     *  @returns {Diposable} A disposable handling the subscriptions and unsubscriptions.
     */
    observableProto.subscribe = observableProto.forEach = function (observerOrOnNext, onError, onCompleted) {
      return this._subscribe(typeof observerOrOnNext === 'object' ?
        observerOrOnNext :
        observerCreate(observerOrOnNext, onError, onCompleted));
    };

    /**
     * Subscribes to the next value in the sequence with an optional "this" argument.
     * @param {Function} onNext The function to invoke on each element in the observable sequence.
     * @param {Any} [thisArg] Object to use as this when executing callback.
     * @returns {Disposable} A disposable handling the subscriptions and unsubscriptions.
     */
    observableProto.subscribeOnNext = function (onNext, thisArg) {
      return this._subscribe(observerCreate(typeof thisArg !== 'undefined' ? function(x) { onNext.call(thisArg, x); } : onNext));
    };

    /**
     * Subscribes to an exceptional condition in the sequence with an optional "this" argument.
     * @param {Function} onError The function to invoke upon exceptional termination of the observable sequence.
     * @param {Any} [thisArg] Object to use as this when executing callback.
     * @returns {Disposable} A disposable handling the subscriptions and unsubscriptions.
     */
    observableProto.subscribeOnError = function (onError, thisArg) {
      return this._subscribe(observerCreate(null, typeof thisArg !== 'undefined' ? function(e) { onError.call(thisArg, e); } : onError));
    };

    /**
     * Subscribes to the next value in the sequence with an optional "this" argument.
     * @param {Function} onCompleted The function to invoke upon graceful termination of the observable sequence.
     * @param {Any} [thisArg] Object to use as this when executing callback.
     * @returns {Disposable} A disposable handling the subscriptions and unsubscriptions.
     */
    observableProto.subscribeOnCompleted = function (onCompleted, thisArg) {
      return this._subscribe(observerCreate(null, null, typeof thisArg !== 'undefined' ? function() { onCompleted.call(thisArg); } : onCompleted));
    };

    return Observable;
  })();

  var ObservableBase = Rx.ObservableBase = (function (__super__) {
    inherits(ObservableBase, __super__);

    function fixSubscriber(subscriber) {
      return subscriber && isFunction(subscriber.dispose) ? subscriber :
        isFunction(subscriber) ? disposableCreate(subscriber) : disposableEmpty;
    }

    function setDisposable(s, state) {
      var ado = state[0], self = state[1];
      var sub = tryCatch(self.subscribeCore).call(self, ado);

      if (sub === errorObj) {
        if(!ado.fail(errorObj.e)) { return thrower(errorObj.e); }
      }
      ado.setDisposable(fixSubscriber(sub));
    }

    function subscribe(observer) {
      var ado = new AutoDetachObserver(observer), state = [ado, this];

      if (currentThreadScheduler.scheduleRequired()) {
        currentThreadScheduler.scheduleWithState(state, setDisposable);
      } else {
        setDisposable(null, state);
      }
      return ado;
    }

    function ObservableBase() {
      __super__.call(this, subscribe);
    }

    ObservableBase.prototype.subscribeCore = notImplemented;

    return ObservableBase;
  }(Observable));

   /**
   *  Wraps the source sequence in order to run its observer callbacks on the specified scheduler.
   *
   *  This only invokes observer callbacks on a scheduler. In case the subscription and/or unsubscription actions have side-effects
   *  that require to be run on a scheduler, use subscribeOn.
   *
   *  @param {Scheduler} scheduler Scheduler to notify observers on.
   *  @returns {Observable} The source sequence whose observations happen on the specified scheduler.
   */
  observableProto.observeOn = function (scheduler) {
    var source = this;
    return new AnonymousObservable(function (observer) {
      return source.subscribe(new ObserveOnObserver(scheduler, observer));
    }, source);
  };

   /**
   *  Wraps the source sequence in order to run its subscription and unsubscription logic on the specified scheduler. This operation is not commonly used;
   *  see the remarks section for more information on the distinction between subscribeOn and observeOn.

   *  This only performs the side-effects of subscription and unsubscription on the specified scheduler. In order to invoke observer
   *  callbacks on a scheduler, use observeOn.

   *  @param {Scheduler} scheduler Scheduler to perform subscription and unsubscription actions on.
   *  @returns {Observable} The source sequence whose subscriptions and unsubscriptions happen on the specified scheduler.
   */
  observableProto.subscribeOn = function (scheduler) {
    var source = this;
    return new AnonymousObservable(function (observer) {
      var m = new SingleAssignmentDisposable(), d = new SerialDisposable();
      d.setDisposable(m);
      m.setDisposable(scheduler.schedule(function () {
        d.setDisposable(new ScheduledDisposable(scheduler, source.subscribe(observer)));
      }));
      return d;
    }, source);
  };

  /**
   * Converts a Promise to an Observable sequence
   * @param {Promise} An ES6 Compliant promise.
   * @returns {Observable} An Observable sequence which wraps the existing promise success and failure.
   */
  var observableFromPromise = Observable.fromPromise = function (promise) {
    return observableDefer(function () {
      var subject = new Rx.AsyncSubject();

      promise.then(
        function (value) {
          subject.onNext(value);
          subject.onCompleted();
        },
        subject.onError.bind(subject));

      return subject;
    });
  };

  /*
   * Converts an existing observable sequence to an ES6 Compatible Promise
   * @example
   * var promise = Rx.Observable.return(42).toPromise(RSVP.Promise);
   *
   * // With config
   * Rx.config.Promise = RSVP.Promise;
   * var promise = Rx.Observable.return(42).toPromise();
   * @param {Function} [promiseCtor] The constructor of the promise. If not provided, it looks for it in Rx.config.Promise.
   * @returns {Promise} An ES6 compatible promise with the last value from the observable sequence.
   */
  observableProto.toPromise = function (promiseCtor) {
    promiseCtor || (promiseCtor = Rx.config.Promise);
    if (!promiseCtor) { throw new NotSupportedError('Promise type not provided nor in Rx.config.Promise'); }
    var source = this;
    return new promiseCtor(function (resolve, reject) {
      // No cancellation can be done
      var value, hasValue = false;
      source.subscribe(function (v) {
        value = v;
        hasValue = true;
      }, reject, function () {
        hasValue && resolve(value);
      });
    });
  };

  var ToArrayObservable = (function(__super__) {
    inherits(ToArrayObservable, __super__);
    function ToArrayObservable(source) {
      this.source = source;
      __super__.call(this);
    }

    ToArrayObservable.prototype.subscribeCore = function(observer) {
      return this.source.subscribe(new ToArrayObserver(observer));
    };

    return ToArrayObservable;
  }(ObservableBase));

  function ToArrayObserver(observer) {
    this.observer = observer;
    this.a = [];
    this.isStopped = false;
  }
  ToArrayObserver.prototype.onNext = function (x) { if(!this.isStopped) { this.a.push(x); } };
  ToArrayObserver.prototype.onError = function (e) {
    if (!this.isStopped) {
      this.isStopped = true;
      this.observer.onError(e);
    }
  };
  ToArrayObserver.prototype.onCompleted = function () {
    if (!this.isStopped) {
      this.isStopped = true;
      this.observer.onNext(this.a);
      this.observer.onCompleted();
    }
  };
  ToArrayObserver.prototype.dispose = function () { this.isStopped = true; }
  ToArrayObserver.prototype.fail = function (e) {
    if (!this.isStopped) {
      this.isStopped = true;
      this.observer.onError(e);
      return true;
    }

    return false;
  };

  /**
  * Creates an array from an observable sequence.
  * @returns {Observable} An observable sequence containing a single element with a list containing all the elements of the source sequence.
  */
  observableProto.toArray = function () {
    return new ToArrayObservable(this);
  };

  /**
   *  Creates an observable sequence from a specified subscribe method implementation.
   * @example
   *  var res = Rx.Observable.create(function (observer) { return function () { } );
   *  var res = Rx.Observable.create(function (observer) { return Rx.Disposable.empty; } );
   *  var res = Rx.Observable.create(function (observer) { } );
   * @param {Function} subscribe Implementation of the resulting observable sequence's subscribe method, returning a function that will be wrapped in a Disposable.
   * @returns {Observable} The observable sequence with the specified implementation for the Subscribe method.
   */
  Observable.create = Observable.createWithDisposable = function (subscribe, parent) {
    return new AnonymousObservable(subscribe, parent);
  };

  /**
   *  Returns an observable sequence that invokes the specified factory function whenever a new observer subscribes.
   *
   * @example
   *  var res = Rx.Observable.defer(function () { return Rx.Observable.fromArray([1,2,3]); });
   * @param {Function} observableFactory Observable factory function to invoke for each observer that subscribes to the resulting sequence or Promise.
   * @returns {Observable} An observable sequence whose observers trigger an invocation of the given observable factory function.
   */
  var observableDefer = Observable.defer = function (observableFactory) {
    return new AnonymousObservable(function (observer) {
      var result;
      try {
        result = observableFactory();
      } catch (e) {
        return observableThrow(e).subscribe(observer);
      }
      isPromise(result) && (result = observableFromPromise(result));
      return result.subscribe(observer);
    });
  };

  var EmptyObservable = (function(__super__) {
    inherits(EmptyObservable, __super__);
    function EmptyObservable(scheduler) {
      this.scheduler = scheduler;
      __super__.call(this);
    }

    EmptyObservable.prototype.subscribeCore = function (observer) {
      var sink = new EmptySink(observer, this);
      return sink.run();
    };

    function EmptySink(observer, parent) {
      this.observer = observer;
      this.parent = parent;
    }

    function scheduleItem(s, state) {
      state.onCompleted();
    }

    EmptySink.prototype.run = function () {
      return this.parent.scheduler.scheduleWithState(this.observer, scheduleItem);
    };

    return EmptyObservable;
  }(ObservableBase));

  /**
   *  Returns an empty observable sequence, using the specified scheduler to send out the single OnCompleted message.
   *
   * @example
   *  var res = Rx.Observable.empty();
   *  var res = Rx.Observable.empty(Rx.Scheduler.timeout);
   * @param {Scheduler} [scheduler] Scheduler to send the termination call on.
   * @returns {Observable} An observable sequence with no elements.
   */
  var observableEmpty = Observable.empty = function (scheduler) {
    isScheduler(scheduler) || (scheduler = immediateScheduler);
    return new EmptyObservable(scheduler);
  };

  var FromObservable = (function(__super__) {
    inherits(FromObservable, __super__);
    function FromObservable(iterable, mapper, scheduler) {
      this.iterable = iterable;
      this.mapper = mapper;
      this.scheduler = scheduler;
      __super__.call(this);
    }

    FromObservable.prototype.subscribeCore = function (observer) {
      var sink = new FromSink(observer, this);
      return sink.run();
    };

    return FromObservable;
  }(ObservableBase));

  var FromSink = (function () {
    function FromSink(observer, parent) {
      this.observer = observer;
      this.parent = parent;
    }

    FromSink.prototype.run = function () {
      var list = Object(this.parent.iterable),
          it = getIterable(list),
          observer = this.observer,
          mapper = this.parent.mapper;

      function loopRecursive(i, recurse) {
        try {
          var next = it.next();
        } catch (e) {
          return observer.onError(e);
        }
        if (next.done) {
          return observer.onCompleted();
        }

        var result = next.value;

        if (mapper) {
          try {
            result = mapper(result, i);
          } catch (e) {
            return observer.onError(e);
          }
        }

        observer.onNext(result);
        recurse(i + 1);
      }

      return this.parent.scheduler.scheduleRecursiveWithState(0, loopRecursive);
    };

    return FromSink;
  }());

  var maxSafeInteger = Math.pow(2, 53) - 1;

  function StringIterable(str) {
    this._s = s;
  }

  StringIterable.prototype[$iterator$] = function () {
    return new StringIterator(this._s);
  };

  function StringIterator(str) {
    this._s = s;
    this._l = s.length;
    this._i = 0;
  }

  StringIterator.prototype[$iterator$] = function () {
    return this;
  };

  StringIterator.prototype.next = function () {
    return this._i < this._l ? { done: false, value: this._s.charAt(this._i++) } : doneEnumerator;
  };

  function ArrayIterable(a) {
    this._a = a;
  }

  ArrayIterable.prototype[$iterator$] = function () {
    return new ArrayIterator(this._a);
  };

  function ArrayIterator(a) {
    this._a = a;
    this._l = toLength(a);
    this._i = 0;
  }

  ArrayIterator.prototype[$iterator$] = function () {
    return this;
  };

  ArrayIterator.prototype.next = function () {
    return this._i < this._l ? { done: false, value: this._a[this._i++] } : doneEnumerator;
  };

  function numberIsFinite(value) {
    return typeof value === 'number' && root.isFinite(value);
  }

  function isNan(n) {
    return n !== n;
  }

  function getIterable(o) {
    var i = o[$iterator$], it;
    if (!i && typeof o === 'string') {
      it = new StringIterable(o);
      return it[$iterator$]();
    }
    if (!i && o.length !== undefined) {
      it = new ArrayIterable(o);
      return it[$iterator$]();
    }
    if (!i) { throw new TypeError('Object is not iterable'); }
    return o[$iterator$]();
  }

  function sign(value) {
    var number = +value;
    if (number === 0) { return number; }
    if (isNaN(number)) { return number; }
    return number < 0 ? -1 : 1;
  }

  function toLength(o) {
    var len = +o.length;
    if (isNaN(len)) { return 0; }
    if (len === 0 || !numberIsFinite(len)) { return len; }
    len = sign(len) * Math.floor(Math.abs(len));
    if (len <= 0) { return 0; }
    if (len > maxSafeInteger) { return maxSafeInteger; }
    return len;
  }

  /**
  * This method creates a new Observable sequence from an array-like or iterable object.
  * @param {Any} arrayLike An array-like or iterable object to convert to an Observable sequence.
  * @param {Function} [mapFn] Map function to call on every element of the array.
  * @param {Any} [thisArg] The context to use calling the mapFn if provided.
  * @param {Scheduler} [scheduler] Optional scheduler to use for scheduling.  If not provided, defaults to Scheduler.currentThread.
  */
  var observableFrom = Observable.from = function (iterable, mapFn, thisArg, scheduler) {
    if (iterable == null) {
      throw new Error('iterable cannot be null.')
    }
    if (mapFn && !isFunction(mapFn)) {
      throw new Error('mapFn when provided must be a function');
    }
    if (mapFn) {
      var mapper = bindCallback(mapFn, thisArg, 2);
    }
    isScheduler(scheduler) || (scheduler = currentThreadScheduler);
    return new FromObservable(iterable, mapper, scheduler);
  }

  var FromArrayObservable = (function(__super__) {
    inherits(FromArrayObservable, __super__);
    function FromArrayObservable(args, scheduler) {
      this.args = args;
      this.scheduler = scheduler;
      __super__.call(this);
    }

    FromArrayObservable.prototype.subscribeCore = function (observer) {
      var sink = new FromArraySink(observer, this);
      return sink.run();
    };

    return FromArrayObservable;
  }(ObservableBase));

  function FromArraySink(observer, parent) {
    this.observer = observer;
    this.parent = parent;
  }

  FromArraySink.prototype.run = function () {
    var observer = this.observer, args = this.parent.args, len = args.length;
    function loopRecursive(i, recurse) {
      if (i < len) {
        observer.onNext(args[i]);
        recurse(i + 1);
      } else {
        observer.onCompleted();
      }
    }

    return this.parent.scheduler.scheduleRecursiveWithState(0, loopRecursive);
  };

  /**
  *  Converts an array to an observable sequence, using an optional scheduler to enumerate the array.
  * @deprecated use Observable.from or Observable.of
  * @param {Scheduler} [scheduler] Scheduler to run the enumeration of the input sequence on.
  * @returns {Observable} The observable sequence whose elements are pulled from the given enumerable sequence.
  */
  var observableFromArray = Observable.fromArray = function (array, scheduler) {
    isScheduler(scheduler) || (scheduler = currentThreadScheduler);
    return new FromArrayObservable(array, scheduler)
  };

  /**
   *  Generates an observable sequence by running a state-driven loop producing the sequence's elements, using the specified scheduler to send out observer messages.
   *
   * @example
   *  var res = Rx.Observable.generate(0, function (x) { return x < 10; }, function (x) { return x + 1; }, function (x) { return x; });
   *  var res = Rx.Observable.generate(0, function (x) { return x < 10; }, function (x) { return x + 1; }, function (x) { return x; }, Rx.Scheduler.timeout);
   * @param {Mixed} initialState Initial state.
   * @param {Function} condition Condition to terminate generation (upon returning false).
   * @param {Function} iterate Iteration step function.
   * @param {Function} resultSelector Selector function for results produced in the sequence.
   * @param {Scheduler} [scheduler] Scheduler on which to run the generator loop. If not provided, defaults to Scheduler.currentThread.
   * @returns {Observable} The generated sequence.
   */
  Observable.generate = function (initialState, condition, iterate, resultSelector, scheduler) {
    isScheduler(scheduler) || (scheduler = currentThreadScheduler);
    return new AnonymousObservable(function (o) {
      var first = true;
      return scheduler.scheduleRecursiveWithState(initialState, function (state, self) {
        var hasResult, result;
        try {
          if (first) {
            first = false;
          } else {
            state = iterate(state);
          }
          hasResult = condition(state);
          hasResult && (result = resultSelector(state));
        } catch (e) {
          return o.onError(e);
        }
        if (hasResult) {
          o.onNext(result);
          self(state);
        } else {
          o.onCompleted();
        }
      });
    });
  };

  var NeverObservable = (function(__super__) {
    inherits(NeverObservable, __super__);
    function NeverObservable() {
      __super__.call(this);
    }

    NeverObservable.prototype.subscribeCore = function (observer) {
      return disposableEmpty;
    };

    return NeverObservable;
  }(ObservableBase));

  /**
   * Returns a non-terminating observable sequence, which can be used to denote an infinite duration (e.g. when using reactive joins).
   * @returns {Observable} An observable sequence whose observers will never get called.
   */
  var observableNever = Observable.never = function () {
    return new NeverObservable();
  };

  function observableOf (scheduler, array) {
    isScheduler(scheduler) || (scheduler = currentThreadScheduler);
    return new FromArrayObservable(array, scheduler);
  }

  /**
  *  This method creates a new Observable instance with a variable number of arguments, regardless of number or type of the arguments.
  * @returns {Observable} The observable sequence whose elements are pulled from the given arguments.
  */
  Observable.of = function () {
    var len = arguments.length, args = new Array(len);
    for(var i = 0; i < len; i++) { args[i] = arguments[i]; }
    return new FromArrayObservable(args, currentThreadScheduler);
  };

  /**
  *  This method creates a new Observable instance with a variable number of arguments, regardless of number or type of the arguments.
  * @param {Scheduler} scheduler A scheduler to use for scheduling the arguments.
  * @returns {Observable} The observable sequence whose elements are pulled from the given arguments.
  */
  Observable.ofWithScheduler = function (scheduler) {
    var len = arguments.length, args = new Array(len - 1);
    for(var i = 1; i < len; i++) { args[i - 1] = arguments[i]; }
    return new FromArrayObservable(args, scheduler);
  };

  var PairsObservable = (function(__super__) {
    inherits(PairsObservable, __super__);
    function PairsObservable(obj, scheduler) {
      this.obj = obj;
      this.keys = Object.keys(obj);
      this.scheduler = scheduler;
      __super__.call(this);
    }

    PairsObservable.prototype.subscribeCore = function (observer) {
      var sink = new PairsSink(observer, this);
      return sink.run();
    };

    return PairsObservable;
  }(ObservableBase));

  function PairsSink(observer, parent) {
    this.observer = observer;
    this.parent = parent;
  }

  PairsSink.prototype.run = function () {
    var observer = this.observer, obj = this.parent.obj, keys = this.parent.keys, len = keys.length;
    function loopRecursive(i, recurse) {
      if (i < len) {
        var key = keys[i];
        observer.onNext([key, obj[key]]);
        recurse(i + 1);
      } else {
        observer.onCompleted();
      }
    }

    return this.parent.scheduler.scheduleRecursiveWithState(0, loopRecursive);
  };

  /**
   * Convert an object into an observable sequence of [key, value] pairs.
   * @param {Object} obj The object to inspect.
   * @param {Scheduler} [scheduler] Scheduler to run the enumeration of the input sequence on.
   * @returns {Observable} An observable sequence of [key, value] pairs from the object.
   */
  Observable.pairs = function (obj, scheduler) {
    scheduler || (scheduler = currentThreadScheduler);
    return new PairsObservable(obj, scheduler);
  };

    var RangeObservable = (function(__super__) {
    inherits(RangeObservable, __super__);
    function RangeObservable(start, count, scheduler) {
      this.start = start;
      this.count = count;
      this.scheduler = scheduler;
      __super__.call(this);
    }

    RangeObservable.prototype.subscribeCore = function (observer) {
      var sink = new RangeSink(observer, this);
      return sink.run();
    };

    return RangeObservable;
  }(ObservableBase));

  var RangeSink = (function () {
    function RangeSink(observer, parent) {
      this.observer = observer;
      this.parent = parent;
    }

    RangeSink.prototype.run = function () {
      var start = this.parent.start, count = this.parent.count, observer = this.observer;
      function loopRecursive(i, recurse) {
        if (i < count) {
          observer.onNext(start + i);
          recurse(i + 1);
        } else {
          observer.onCompleted();
        }
      }

      return this.parent.scheduler.scheduleRecursiveWithState(0, loopRecursive);
    };

    return RangeSink;
  }());

  /**
  *  Generates an observable sequence of integral numbers within a specified range, using the specified scheduler to send out observer messages.
  * @param {Number} start The value of the first integer in the sequence.
  * @param {Number} count The number of sequential integers to generate.
  * @param {Scheduler} [scheduler] Scheduler to run the generator loop on. If not specified, defaults to Scheduler.currentThread.
  * @returns {Observable} An observable sequence that contains a range of sequential integral numbers.
  */
  Observable.range = function (start, count, scheduler) {
    isScheduler(scheduler) || (scheduler = currentThreadScheduler);
    return new RangeObservable(start, count, scheduler);
  };

  var RepeatObservable = (function(__super__) {
    inherits(RepeatObservable, __super__);
    function RepeatObservable(value, repeatCount, scheduler) {
      this.value = value;
      this.repeatCount = repeatCount == null ? -1 : repeatCount;
      this.scheduler = scheduler;
      __super__.call(this);
    }

    RepeatObservable.prototype.subscribeCore = function (observer) {
      var sink = new RepeatSink(observer, this);
      return sink.run();
    };

    return RepeatObservable;
  }(ObservableBase));

  function RepeatSink(observer, parent) {
    this.observer = observer;
    this.parent = parent;
  }

  RepeatSink.prototype.run = function () {
    var observer = this.observer, value = this.parent.value;
    function loopRecursive(i, recurse) {
      if (i === -1 || i > 0) {
        observer.onNext(value);
        i > 0 && i--;
      }
      if (i === 0) { return observer.onCompleted(); }
      recurse(i);
    }

    return this.parent.scheduler.scheduleRecursiveWithState(this.parent.repeatCount, loopRecursive);
  };

  /**
   *  Generates an observable sequence that repeats the given element the specified number of times, using the specified scheduler to send out observer messages.
   * @param {Mixed} value Element to repeat.
   * @param {Number} repeatCount [Optiona] Number of times to repeat the element. If not specified, repeats indefinitely.
   * @param {Scheduler} scheduler Scheduler to run the producer loop on. If not specified, defaults to Scheduler.immediate.
   * @returns {Observable} An observable sequence that repeats the given element the specified number of times.
   */
  Observable.repeat = function (value, repeatCount, scheduler) {
    isScheduler(scheduler) || (scheduler = currentThreadScheduler);
    return new RepeatObservable(value, repeatCount, scheduler);
  };

  var JustObservable = (function(__super__) {
    inherits(JustObservable, __super__);
    function JustObservable(value, scheduler) {
      this.value = value;
      this.scheduler = scheduler;
      __super__.call(this);
    }

    JustObservable.prototype.subscribeCore = function (observer) {
      var sink = new JustSink(observer, this);
      return sink.run();
    };

    function JustSink(observer, parent) {
      this.observer = observer;
      this.parent = parent;
    }

    function scheduleItem(s, state) {
      var value = state[0], observer = state[1];
      observer.onNext(value);
      observer.onCompleted();
    }

    JustSink.prototype.run = function () {
      return this.parent.scheduler.scheduleWithState([this.parent.value, this.observer], scheduleItem);
    };

    return JustObservable;
  }(ObservableBase));

  /**
   *  Returns an observable sequence that contains a single element, using the specified scheduler to send out observer messages.
   *  There is an alias called 'just' or browsers <IE9.
   * @param {Mixed} value Single element in the resulting observable sequence.
   * @param {Scheduler} scheduler Scheduler to send the single element on. If not specified, defaults to Scheduler.immediate.
   * @returns {Observable} An observable sequence containing the single specified element.
   */
  var observableReturn = Observable['return'] = Observable.just = Observable.returnValue = function (value, scheduler) {
    isScheduler(scheduler) || (scheduler = immediateScheduler);
    return new JustObservable(value, scheduler);
  };

  var ThrowObservable = (function(__super__) {
    inherits(ThrowObservable, __super__);
    function ThrowObservable(error, scheduler) {
      this.error = error;
      this.scheduler = scheduler;
      __super__.call(this);
    }

    ThrowObservable.prototype.subscribeCore = function (observer) {
      var sink = new ThrowSink(observer, this);
      return sink.run();
    };

    function ThrowSink(observer, parent) {
      this.observer = observer;
      this.parent = parent;
    }

    function scheduleItem(s, state) {
      var error = state[0], observer = state[1];
      observer.onError(error);
    }

    ThrowSink.prototype.run = function () {
      return this.parent.scheduler.scheduleWithState([this.parent.error, this.observer], scheduleItem);
    };

    return ThrowObservable;
  }(ObservableBase));

  /**
   *  Returns an observable sequence that terminates with an exception, using the specified scheduler to send out the single onError message.
   *  There is an alias to this method called 'throwError' for browsers <IE9.
   * @param {Mixed} error An object used for the sequence's termination.
   * @param {Scheduler} scheduler Scheduler to send the exceptional termination call on. If not specified, defaults to Scheduler.immediate.
   * @returns {Observable} The observable sequence that terminates exceptionally with the specified exception object.
   */
  var observableThrow = Observable['throw'] = Observable.throwError = Observable.throwException = function (error, scheduler) {
    isScheduler(scheduler) || (scheduler = immediateScheduler);
    return new ThrowObservable(error, scheduler);
  };

  /**
   * Constructs an observable sequence that depends on a resource object, whose lifetime is tied to the resulting observable sequence's lifetime.
   * @param {Function} resourceFactory Factory function to obtain a resource object.
   * @param {Function} observableFactory Factory function to obtain an observable sequence that depends on the obtained resource.
   * @returns {Observable} An observable sequence whose lifetime controls the lifetime of the dependent resource object.
   */
  Observable.using = function (resourceFactory, observableFactory) {
    return new AnonymousObservable(function (observer) {
      var disposable = disposableEmpty, resource, source;
      try {
        resource = resourceFactory();
        resource && (disposable = resource);
        source = observableFactory(resource);
      } catch (exception) {
        return new CompositeDisposable(observableThrow(exception).subscribe(observer), disposable);
      }
      return new CompositeDisposable(source.subscribe(observer), disposable);
    });
  };

  /**
   * Propagates the observable sequence or Promise that reacts first.
   * @param {Observable} rightSource Second observable sequence or Promise.
   * @returns {Observable} {Observable} An observable sequence that surfaces either of the given sequences, whichever reacted first.
   */
  observableProto.amb = function (rightSource) {
    var leftSource = this;
    return new AnonymousObservable(function (observer) {
      var choice,
        leftChoice = 'L', rightChoice = 'R',
        leftSubscription = new SingleAssignmentDisposable(),
        rightSubscription = new SingleAssignmentDisposable();

      isPromise(rightSource) && (rightSource = observableFromPromise(rightSource));

      function choiceL() {
        if (!choice) {
          choice = leftChoice;
          rightSubscription.dispose();
        }
      }

      function choiceR() {
        if (!choice) {
          choice = rightChoice;
          leftSubscription.dispose();
        }
      }

      leftSubscription.setDisposable(leftSource.subscribe(function (left) {
        choiceL();
        if (choice === leftChoice) {
          observer.onNext(left);
        }
      }, function (err) {
        choiceL();
        if (choice === leftChoice) {
          observer.onError(err);
        }
      }, function () {
        choiceL();
        if (choice === leftChoice) {
          observer.onCompleted();
        }
      }));

      rightSubscription.setDisposable(rightSource.subscribe(function (right) {
        choiceR();
        if (choice === rightChoice) {
          observer.onNext(right);
        }
      }, function (err) {
        choiceR();
        if (choice === rightChoice) {
          observer.onError(err);
        }
      }, function () {
        choiceR();
        if (choice === rightChoice) {
          observer.onCompleted();
        }
      }));

      return new CompositeDisposable(leftSubscription, rightSubscription);
    });
  };

  /**
   * Propagates the observable sequence or Promise that reacts first.
   *
   * @example
   * var = Rx.Observable.amb(xs, ys, zs);
   * @returns {Observable} An observable sequence that surfaces any of the given sequences, whichever reacted first.
   */
  Observable.amb = function () {
    var acc = observableNever(), items = [];
    if (Array.isArray(arguments[0])) {
      items = arguments[0];
    } else {
      for(var i = 0, len = arguments.length; i < len; i++) { items.push(arguments[i]); }
    }

    function func(previous, current) {
      return previous.amb(current);
    }
    for (var i = 0, len = items.length; i < len; i++) {
      acc = func(acc, items[i]);
    }
    return acc;
  };

  function observableCatchHandler(source, handler) {
    return new AnonymousObservable(function (o) {
      var d1 = new SingleAssignmentDisposable(), subscription = new SerialDisposable();
      subscription.setDisposable(d1);
      d1.setDisposable(source.subscribe(function (x) { o.onNext(x); }, function (e) {
        try {
          var result = handler(e);
        } catch (ex) {
          return o.onError(ex);
        }
        isPromise(result) && (result = observableFromPromise(result));

        var d = new SingleAssignmentDisposable();
        subscription.setDisposable(d);
        d.setDisposable(result.subscribe(o));
      }, function (x) { o.onCompleted(x); }));

      return subscription;
    }, source);
  }

  /**
   * Continues an observable sequence that is terminated by an exception with the next observable sequence.
   * @example
   * 1 - xs.catchException(ys)
   * 2 - xs.catchException(function (ex) { return ys(ex); })
   * @param {Mixed} handlerOrSecond Exception handler function that returns an observable sequence given the error that occurred in the first sequence, or a second observable sequence used to produce results when an error occurred in the first sequence.
   * @returns {Observable} An observable sequence containing the first sequence's elements, followed by the elements of the handler sequence in case an exception occurred.
   */
  observableProto['catch'] = observableProto.catchError = observableProto.catchException = function (handlerOrSecond) {
    return typeof handlerOrSecond === 'function' ?
      observableCatchHandler(this, handlerOrSecond) :
      observableCatch([this, handlerOrSecond]);
  };

  /**
   * Continues an observable sequence that is terminated by an exception with the next observable sequence.
   * @param {Array | Arguments} args Arguments or an array to use as the next sequence if an error occurs.
   * @returns {Observable} An observable sequence containing elements from consecutive source sequences until a source sequence terminates successfully.
   */
  var observableCatch = Observable.catchError = Observable['catch'] = Observable.catchException = function () {
    var items = [];
    if (Array.isArray(arguments[0])) {
      items = arguments[0];
    } else {
      for(var i = 0, len = arguments.length; i < len; i++) { items.push(arguments[i]); }
    }
    return enumerableOf(items).catchError();
  };

  /**
   * Merges the specified observable sequences into one observable sequence by using the selector function whenever any of the observable sequences or Promises produces an element.
   * This can be in the form of an argument list of observables or an array.
   *
   * @example
   * 1 - obs = observable.combineLatest(obs1, obs2, obs3, function (o1, o2, o3) { return o1 + o2 + o3; });
   * 2 - obs = observable.combineLatest([obs1, obs2, obs3], function (o1, o2, o3) { return o1 + o2 + o3; });
   * @returns {Observable} An observable sequence containing the result of combining elements of the sources using the specified result selector function.
   */
  observableProto.combineLatest = function () {
    var len = arguments.length, args = new Array(len);
    for(var i = 0; i < len; i++) { args[i] = arguments[i]; }
    if (Array.isArray(args[0])) {
      args[0].unshift(this);
    } else {
      args.unshift(this);
    }
    return combineLatest.apply(this, args);
  };

  /**
   * Merges the specified observable sequences into one observable sequence by using the selector function whenever any of the observable sequences or Promises produces an element.
   *
   * @example
   * 1 - obs = Rx.Observable.combineLatest(obs1, obs2, obs3, function (o1, o2, o3) { return o1 + o2 + o3; });
   * 2 - obs = Rx.Observable.combineLatest([obs1, obs2, obs3], function (o1, o2, o3) { return o1 + o2 + o3; });
   * @returns {Observable} An observable sequence containing the result of combining elements of the sources using the specified result selector function.
   */
  var combineLatest = Observable.combineLatest = function () {
    var len = arguments.length, args = new Array(len);
    for(var i = 0; i < len; i++) { args[i] = arguments[i]; }
    var resultSelector = args.pop();
    Array.isArray(args[0]) && (args = args[0]);

    return new AnonymousObservable(function (o) {
      var n = args.length,
        falseFactory = function () { return false; },
        hasValue = arrayInitialize(n, falseFactory),
        hasValueAll = false,
        isDone = arrayInitialize(n, falseFactory),
        values = new Array(n);

      function next(i) {
        hasValue[i] = true;
        if (hasValueAll || (hasValueAll = hasValue.every(identity))) {
          try {
            var res = resultSelector.apply(null, values);
          } catch (e) {
            return o.onError(e);
          }
          o.onNext(res);
        } else if (isDone.filter(function (x, j) { return j !== i; }).every(identity)) {
          o.onCompleted();
        }
      }

      function done (i) {
        isDone[i] = true;
        isDone.every(identity) && o.onCompleted();
      }

      var subscriptions = new Array(n);
      for (var idx = 0; idx < n; idx++) {
        (function (i) {
          var source = args[i], sad = new SingleAssignmentDisposable();
          isPromise(source) && (source = observableFromPromise(source));
          sad.setDisposable(source.subscribe(function (x) {
              values[i] = x;
              next(i);
            },
            function(e) { o.onError(e); },
            function () { done(i); }
          ));
          subscriptions[i] = sad;
        }(idx));
      }

      return new CompositeDisposable(subscriptions);
    }, this);
  };

  /**
   * Concatenates all the observable sequences.  This takes in either an array or variable arguments to concatenate.
   * @returns {Observable} An observable sequence that contains the elements of each given sequence, in sequential order.
   */
  observableProto.concat = function () {
    for(var args = [], i = 0, len = arguments.length; i < len; i++) { args.push(arguments[i]); }
    args.unshift(this);
    return observableConcat.apply(null, args);
  };

  /**
   * Concatenates all the observable sequences.
   * @param {Array | Arguments} args Arguments or an array to concat to the observable sequence.
   * @returns {Observable} An observable sequence that contains the elements of each given sequence, in sequential order.
   */
  var observableConcat = Observable.concat = function () {
    var args;
    if (Array.isArray(arguments[0])) {
      args = arguments[0];
    } else {
      args = new Array(arguments.length);
      for(var i = 0, len = arguments.length; i < len; i++) { args[i] = arguments[i]; }
    }
    return enumerableOf(args).concat();
  };

  /**
   * Concatenates an observable sequence of observable sequences.
   * @returns {Observable} An observable sequence that contains the elements of each observed inner sequence, in sequential order.
   */
  observableProto.concatAll = observableProto.concatObservable = function () {
    return this.merge(1);
  };

  var MergeObservable = (function (__super__) {
    inherits(MergeObservable, __super__);

    function MergeObservable(source, maxConcurrent) {
      this.source = source;
      this.maxConcurrent = maxConcurrent;
      __super__.call(this);
    }

    MergeObservable.prototype.subscribeCore = function(observer) {
      var g = new CompositeDisposable();
      g.add(this.source.subscribe(new MergeObserver(observer, this.maxConcurrent, g)));
      return g;
    };

    return MergeObservable;

  }(ObservableBase));

  var MergeObserver = (function () {
    function MergeObserver(o, max, g) {
      this.o = o;
      this.max = max;
      this.g = g;
      this.done = false;
      this.q = [];
      this.activeCount = 0;
      this.isStopped = false;
    }
    MergeObserver.prototype.handleSubscribe = function (xs) {
      var sad = new SingleAssignmentDisposable();
      this.g.add(sad);
      isPromise(xs) && (xs = observableFromPromise(xs));
      sad.setDisposable(xs.subscribe(new InnerObserver(this, sad)));
    };
    MergeObserver.prototype.onNext = function (innerSource) {
      if (this.isStopped) { return; }
        if(this.activeCount < this.max) {
          this.activeCount++;
          this.handleSubscribe(innerSource);
        } else {
          this.q.push(innerSource);
        }
      };
      MergeObserver.prototype.onError = function (e) {
        if (!this.isStopped) {
          this.isStopped = true;
          this.o.onError(e);
        }
      };
      MergeObserver.prototype.onCompleted = function () {
        if (!this.isStopped) {
          this.isStopped = true;
          this.done = true;
          this.activeCount === 0 && this.o.onCompleted();
        }
      };
      MergeObserver.prototype.dispose = function() { this.isStopped = true; };
      MergeObserver.prototype.fail = function (e) {
        if (!this.isStopped) {
          this.isStopped = true;
          this.o.onError(e);
          return true;
        }

        return false;
      };

      function InnerObserver(parent, sad) {
        this.parent = parent;
        this.sad = sad;
        this.isStopped = false;
      }
      InnerObserver.prototype.onNext = function (x) { if(!this.isStopped) { this.parent.o.onNext(x); } };
      InnerObserver.prototype.onError = function (e) {
        if (!this.isStopped) {
          this.isStopped = true;
          this.parent.o.onError(e);
        }
      };
      InnerObserver.prototype.onCompleted = function () {
        if(!this.isStopped) {
          this.isStopped = true;
          var parent = this.parent;
          parent.g.remove(this.sad);
          if (parent.q.length > 0) {
            parent.handleSubscribe(parent.q.shift());
          } else {
            parent.activeCount--;
            parent.done && parent.activeCount === 0 && parent.o.onCompleted();
          }
        }
      };
      InnerObserver.prototype.dispose = function() { this.isStopped = true; };
      InnerObserver.prototype.fail = function (e) {
        if (!this.isStopped) {
          this.isStopped = true;
          this.parent.o.onError(e);
          return true;
        }

        return false;
      };

      return MergeObserver;
  }());





  /**
  * Merges an observable sequence of observable sequences into an observable sequence, limiting the number of concurrent subscriptions to inner sequences.
  * Or merges two observable sequences into a single observable sequence.
  *
  * @example
  * 1 - merged = sources.merge(1);
  * 2 - merged = source.merge(otherSource);
  * @param {Mixed} [maxConcurrentOrOther] Maximum number of inner observable sequences being subscribed to concurrently or the second observable sequence.
  * @returns {Observable} The observable sequence that merges the elements of the inner sequences.
  */
  observableProto.merge = function (maxConcurrentOrOther) {
    return typeof maxConcurrentOrOther !== 'number' ?
      observableMerge(this, maxConcurrentOrOther) :
      new MergeObservable(this, maxConcurrentOrOther);
  };

  /**
   * Merges all the observable sequences into a single observable sequence.
   * The scheduler is optional and if not specified, the immediate scheduler is used.
   * @returns {Observable} The observable sequence that merges the elements of the observable sequences.
   */
  var observableMerge = Observable.merge = function () {
    var scheduler, sources = [], i, len = arguments.length;
    if (!arguments[0]) {
      scheduler = immediateScheduler;
      for(i = 1; i < len; i++) { sources.push(arguments[i]); }
    } else if (isScheduler(arguments[0])) {
      scheduler = arguments[0];
      for(i = 1; i < len; i++) { sources.push(arguments[i]); }
    } else {
      scheduler = immediateScheduler;
      for(i = 0; i < len; i++) { sources.push(arguments[i]); }
    }
    if (Array.isArray(sources[0])) {
      sources = sources[0];
    }
    return observableOf(scheduler, sources).mergeAll();
  };

  var CompositeError = Rx.CompositeError = function(errors) {
    this.name = "NotImplementedError";
    this.innerErrors = errors;
    this.message = 'This contains multiple errors. Check the innerErrors';
    Error.call(this);
  }
  CompositeError.prototype = Error.prototype;

  /**
  * Flattens an Observable that emits Observables into one Observable, in a way that allows an Observer to
  * receive all successfully emitted items from all of the source Observables without being interrupted by
  * an error notification from one of them.
  *
  * This behaves like Observable.prototype.mergeAll except that if any of the merged Observables notify of an
  * error via the Observer's onError, mergeDelayError will refrain from propagating that
  * error notification until all of the merged Observables have finished emitting items.
  * @param {Array | Arguments} args Arguments or an array to merge.
  * @returns {Observable} an Observable that emits all of the items emitted by the Observables emitted by the Observable
  */
  Observable.mergeDelayError = function() {
    var args;
    if (Array.isArray(arguments[0])) {
      args = arguments[0];
    } else {
      var len = arguments.length;
      args = new Array(len);
      for(var i = 0; i < len; i++) { args[i] = arguments[i]; }
    }
    var source = observableOf(null, args);

    return new AnonymousObservable(function (o) {
      var group = new CompositeDisposable(),
        m = new SingleAssignmentDisposable(),
        isStopped = false,
        errors = [];

      function setCompletion() {
        if (errors.length === 0) {
          o.onCompleted();
        } else if (errors.length === 1) {
          o.onError(errors[0]);
        } else {
          o.onError(new CompositeError(errors));
        }
      }

      group.add(m);

      m.setDisposable(source.subscribe(
        function (innerSource) {
          var innerSubscription = new SingleAssignmentDisposable();
          group.add(innerSubscription);

          // Check for promises support
          isPromise(innerSource) && (innerSource = observableFromPromise(innerSource));

          innerSubscription.setDisposable(innerSource.subscribe(
            function (x) { o.onNext(x); },
            function (e) {
              errors.push(e);
              group.remove(innerSubscription);
              isStopped && group.length === 1 && setCompletion();
            },
            function () {
              group.remove(innerSubscription);
              isStopped && group.length === 1 && setCompletion();
          }));
        },
        function (e) {
          errors.push(e);
          isStopped = true;
          group.length === 1 && setCompletion();
        },
        function () {
          isStopped = true;
          group.length === 1 && setCompletion();
        }));
      return group;
    });
  };

  var MergeAllObservable = (function (__super__) {
    inherits(MergeAllObservable, __super__);

    function MergeAllObservable(source) {
      this.source = source;
      __super__.call(this);
    }

    MergeAllObservable.prototype.subscribeCore = function (observer) {
      var g = new CompositeDisposable(), m = new SingleAssignmentDisposable();
      g.add(m);
      m.setDisposable(this.source.subscribe(new MergeAllObserver(observer, g)));
      return g;
    };

    return MergeAllObservable;
  }(ObservableBase));

  var MergeAllObserver = (function() {

    function MergeAllObserver(o, g) {
      this.o = o;
      this.g = g;
      this.isStopped = false;
      this.done = false;
    }
    MergeAllObserver.prototype.onNext = function(innerSource) {
      if(this.isStopped) { return; }
      var sad = new SingleAssignmentDisposable();
      this.g.add(sad);

      isPromise(innerSource) && (innerSource = observableFromPromise(innerSource));

      sad.setDisposable(innerSource.subscribe(new InnerObserver(this, this.g, sad)));
    };
    MergeAllObserver.prototype.onError = function (e) {
      if(!this.isStopped) {
        this.isStopped = true;
        this.o.onError(e);
      }
    };
    MergeAllObserver.prototype.onCompleted = function () {
      if(!this.isStopped) {
        this.isStopped = true;
        this.done = true;
        this.g.length === 1 && this.o.onCompleted();
      }
    };
    MergeAllObserver.prototype.dispose = function() { this.isStopped = true; };
    MergeAllObserver.prototype.fail = function (e) {
      if (!this.isStopped) {
        this.isStopped = true;
        this.o.onError(e);
        return true;
      }

      return false;
    };

    function InnerObserver(parent, g, sad) {
      this.parent = parent;
      this.g = g;
      this.sad = sad;
      this.isStopped = false;
    }
    InnerObserver.prototype.onNext = function (x) { if (!this.isStopped) { this.parent.o.onNext(x); } };
    InnerObserver.prototype.onError = function (e) {
      if(!this.isStopped) {
        this.isStopped = true;
        this.parent.o.onError(e);
      }
    };
    InnerObserver.prototype.onCompleted = function () {
      if(!this.isStopped) {
        var parent = this.parent;
        this.isStopped = true;
        parent.g.remove(this.sad);
        parent.done && parent.g.length === 1 && parent.o.onCompleted();
      }
    };
    InnerObserver.prototype.dispose = function() { this.isStopped = true; };
    InnerObserver.prototype.fail = function (e) {
      if (!this.isStopped) {
        this.isStopped = true;
        this.parent.o.onError(e);
        return true;
      }

      return false;
    };

    return MergeAllObserver;

  }());

  /**
  * Merges an observable sequence of observable sequences into an observable sequence.
  * @returns {Observable} The observable sequence that merges the elements of the inner sequences.
  */
  observableProto.mergeAll = observableProto.mergeObservable = function () {
    return new MergeAllObservable(this);
  };

  /**
   * Continues an observable sequence that is terminated normally or by an exception with the next observable sequence.
   * @param {Observable} second Second observable sequence used to produce results after the first sequence terminates.
   * @returns {Observable} An observable sequence that concatenates the first and second sequence, even if the first sequence terminates exceptionally.
   */
  observableProto.onErrorResumeNext = function (second) {
    if (!second) { throw new Error('Second observable is required'); }
    return onErrorResumeNext([this, second]);
  };

  /**
   * Continues an observable sequence that is terminated normally or by an exception with the next observable sequence.
   *
   * @example
   * 1 - res = Rx.Observable.onErrorResumeNext(xs, ys, zs);
   * 1 - res = Rx.Observable.onErrorResumeNext([xs, ys, zs]);
   * @returns {Observable} An observable sequence that concatenates the source sequences, even if a sequence terminates exceptionally.
   */
  var onErrorResumeNext = Observable.onErrorResumeNext = function () {
    var sources = [];
    if (Array.isArray(arguments[0])) {
      sources = arguments[0];
    } else {
      for(var i = 0, len = arguments.length; i < len; i++) { sources.push(arguments[i]); }
    }
    return new AnonymousObservable(function (observer) {
      var pos = 0, subscription = new SerialDisposable(),
      cancelable = immediateScheduler.scheduleRecursive(function (self) {
        var current, d;
        if (pos < sources.length) {
          current = sources[pos++];
          isPromise(current) && (current = observableFromPromise(current));
          d = new SingleAssignmentDisposable();
          subscription.setDisposable(d);
          d.setDisposable(current.subscribe(observer.onNext.bind(observer), self, self));
        } else {
          observer.onCompleted();
        }
      });
      return new CompositeDisposable(subscription, cancelable);
    });
  };

  /**
   * Returns the values from the source observable sequence only after the other observable sequence produces a value.
   * @param {Observable | Promise} other The observable sequence or Promise that triggers propagation of elements of the source sequence.
   * @returns {Observable} An observable sequence containing the elements of the source sequence starting from the point the other sequence triggered propagation.
   */
  observableProto.skipUntil = function (other) {
    var source = this;
    return new AnonymousObservable(function (o) {
      var isOpen = false;
      var disposables = new CompositeDisposable(source.subscribe(function (left) {
        isOpen && o.onNext(left);
      }, function (e) { o.onError(e); }, function () {
        isOpen && o.onCompleted();
      }));

      isPromise(other) && (other = observableFromPromise(other));

      var rightSubscription = new SingleAssignmentDisposable();
      disposables.add(rightSubscription);
      rightSubscription.setDisposable(other.subscribe(function () {
        isOpen = true;
        rightSubscription.dispose();
      }, function (e) { o.onError(e); }, function () {
        rightSubscription.dispose();
      }));

      return disposables;
    }, source);
  };

  /**
   * Transforms an observable sequence of observable sequences into an observable sequence producing values only from the most recent observable sequence.
   * @returns {Observable} The observable sequence that at any point in time produces the elements of the most recent inner observable sequence that has been received.
   */
  observableProto['switch'] = observableProto.switchLatest = function () {
    var sources = this;
    return new AnonymousObservable(function (observer) {
      var hasLatest = false,
        innerSubscription = new SerialDisposable(),
        isStopped = false,
        latest = 0,
        subscription = sources.subscribe(
          function (innerSource) {
            var d = new SingleAssignmentDisposable(), id = ++latest;
            hasLatest = true;
            innerSubscription.setDisposable(d);

            // Check if Promise or Observable
            isPromise(innerSource) && (innerSource = observableFromPromise(innerSource));

            d.setDisposable(innerSource.subscribe(
              function (x) { latest === id && observer.onNext(x); },
              function (e) { latest === id && observer.onError(e); },
              function () {
                if (latest === id) {
                  hasLatest = false;
                  isStopped && observer.onCompleted();
                }
              }));
          },
          function (e) { observer.onError(e); },
          function () {
            isStopped = true;
            !hasLatest && observer.onCompleted();
          });
      return new CompositeDisposable(subscription, innerSubscription);
    }, sources);
  };

  /**
   * Returns the values from the source observable sequence until the other observable sequence produces a value.
   * @param {Observable | Promise} other Observable sequence or Promise that terminates propagation of elements of the source sequence.
   * @returns {Observable} An observable sequence containing the elements of the source sequence up to the point the other sequence interrupted further propagation.
   */
  observableProto.takeUntil = function (other) {
    var source = this;
    return new AnonymousObservable(function (o) {
      isPromise(other) && (other = observableFromPromise(other));
      return new CompositeDisposable(
        source.subscribe(o),
        other.subscribe(function () { o.onCompleted(); }, function (e) { o.onError(e); }, noop)
      );
    }, source);
  };

  /**
   * Merges the specified observable sequences into one observable sequence by using the selector function only when the (first) source observable sequence produces an element.
   *
   * @example
   * 1 - obs = obs1.withLatestFrom(obs2, obs3, function (o1, o2, o3) { return o1 + o2 + o3; });
   * 2 - obs = obs1.withLatestFrom([obs2, obs3], function (o1, o2, o3) { return o1 + o2 + o3; });
   * @returns {Observable} An observable sequence containing the result of combining elements of the sources using the specified result selector function.
   */
  observableProto.withLatestFrom = function () {
    var len = arguments.length, args = new Array(len)
    for(var i = 0; i < len; i++) { args[i] = arguments[i]; }
    var resultSelector = args.pop(), source = this;

    if (typeof source === 'undefined') {
      throw new Error('Source observable not found for withLatestFrom().');
    }
    if (typeof resultSelector !== 'function') {
      throw new Error('withLatestFrom() expects a resultSelector function.');
    }
    if (Array.isArray(args[0])) {
      args = args[0];
    }

    return new AnonymousObservable(function (observer) {
      var falseFactory = function () { return false; },
        n = args.length,
        hasValue = arrayInitialize(n, falseFactory),
        hasValueAll = false,
        values = new Array(n);

      var subscriptions = new Array(n + 1);
      for (var idx = 0; idx < n; idx++) {
        (function (i) {
          var other = args[i], sad = new SingleAssignmentDisposable();
          isPromise(other) && (other = observableFromPromise(other));
          sad.setDisposable(other.subscribe(function (x) {
            values[i] = x;
            hasValue[i] = true;
            hasValueAll = hasValue.every(identity);
          }, observer.onError.bind(observer), function () {}));
          subscriptions[i] = sad;
        }(idx));
      }

      var sad = new SingleAssignmentDisposable();
      sad.setDisposable(source.subscribe(function (x) {
        var res;
        var allValues = [x].concat(values);
        if (!hasValueAll) return;
        try {
          res = resultSelector.apply(null, allValues);
        } catch (ex) {
          observer.onError(ex);
          return;
        }
        observer.onNext(res);
      }, observer.onError.bind(observer), function () {
        observer.onCompleted();
      }));
      subscriptions[n] = sad;

      return new CompositeDisposable(subscriptions);
    }, this);
  };

  function zipArray(second, resultSelector) {
    var first = this;
    return new AnonymousObservable(function (observer) {
      var index = 0, len = second.length;
      return first.subscribe(function (left) {
        if (index < len) {
          var right = second[index++], result;
          try {
            result = resultSelector(left, right);
          } catch (e) {
            return observer.onError(e);
          }
          observer.onNext(result);
        } else {
          observer.onCompleted();
        }
      }, function (e) { observer.onError(e); }, function () { observer.onCompleted(); });
    }, first);
  }

  function falseFactory() { return false; }
  function emptyArrayFactory() { return []; }

  /**
   * Merges the specified observable sequences into one observable sequence by using the selector function whenever all of the observable sequences or an array have produced an element at a corresponding index.
   * The last element in the arguments must be a function to invoke for each series of elements at corresponding indexes in the args.
   *
   * @example
   * 1 - res = obs1.zip(obs2, fn);
   * 1 - res = x1.zip([1,2,3], fn);
   * @returns {Observable} An observable sequence containing the result of combining elements of the args using the specified result selector function.
   */
  observableProto.zip = function () {
    if (Array.isArray(arguments[0])) { return zipArray.apply(this, arguments); }
    var len = arguments.length, args = new Array(len);
    for(var i = 0; i < len; i++) { args[i] = arguments[i]; }

    var parent = this, resultSelector = args.pop();
    args.unshift(parent);
    return new AnonymousObservable(function (observer) {
      var n = args.length,
        queues = arrayInitialize(n, emptyArrayFactory),
        isDone = arrayInitialize(n, falseFactory);

      function next(i) {
        var res, queuedValues;
        if (queues.every(function (x) { return x.length > 0; })) {
          try {
            queuedValues = queues.map(function (x) { return x.shift(); });
            res = resultSelector.apply(parent, queuedValues);
          } catch (ex) {
            observer.onError(ex);
            return;
          }
          observer.onNext(res);
        } else if (isDone.filter(function (x, j) { return j !== i; }).every(identity)) {
          observer.onCompleted();
        }
      };

      function done(i) {
        isDone[i] = true;
        if (isDone.every(function (x) { return x; })) {
          observer.onCompleted();
        }
      }

      var subscriptions = new Array(n);
      for (var idx = 0; idx < n; idx++) {
        (function (i) {
          var source = args[i], sad = new SingleAssignmentDisposable();
          isPromise(source) && (source = observableFromPromise(source));
          sad.setDisposable(source.subscribe(function (x) {
            queues[i].push(x);
            next(i);
          }, function (e) { observer.onError(e); }, function () {
            done(i);
          }));
          subscriptions[i] = sad;
        })(idx);
      }

      return new CompositeDisposable(subscriptions);
    }, parent);
  };

  /**
   * Merges the specified observable sequences into one observable sequence by using the selector function whenever all of the observable sequences have produced an element at a corresponding index.
   * @param arguments Observable sources.
   * @param {Function} resultSelector Function to invoke for each series of elements at corresponding indexes in the sources.
   * @returns {Observable} An observable sequence containing the result of combining elements of the sources using the specified result selector function.
   */
  Observable.zip = function () {
    var len = arguments.length, args = new Array(len);
    for(var i = 0; i < len; i++) { args[i] = arguments[i]; }
    var first = args.shift();
    return first.zip.apply(first, args);
  };

  /**
   * Merges the specified observable sequences into one observable sequence by emitting a list with the elements of the observable sequences at corresponding indexes.
   * @param arguments Observable sources.
   * @returns {Observable} An observable sequence containing lists of elements at corresponding indexes.
   */
  Observable.zipArray = function () {
    var sources;
    if (Array.isArray(arguments[0])) {
      sources = arguments[0];
    } else {
      var len = arguments.length;
      sources = new Array(len);
      for(var i = 0; i < len; i++) { sources[i] = arguments[i]; }
    }
    return new AnonymousObservable(function (observer) {
      var n = sources.length,
        queues = arrayInitialize(n, function () { return []; }),
        isDone = arrayInitialize(n, function () { return false; });

      function next(i) {
        if (queues.every(function (x) { return x.length > 0; })) {
          var res = queues.map(function (x) { return x.shift(); });
          observer.onNext(res);
        } else if (isDone.filter(function (x, j) { return j !== i; }).every(identity)) {
          observer.onCompleted();
          return;
        }
      };

      function done(i) {
        isDone[i] = true;
        if (isDone.every(identity)) {
          observer.onCompleted();
          return;
        }
      }

      var subscriptions = new Array(n);
      for (var idx = 0; idx < n; idx++) {
        (function (i) {
          subscriptions[i] = new SingleAssignmentDisposable();
          subscriptions[i].setDisposable(sources[i].subscribe(function (x) {
            queues[i].push(x);
            next(i);
          }, function (e) { observer.onError(e); }, function () {
            done(i);
          }));
        })(idx);
      }

      return new CompositeDisposable(subscriptions);
    });
  };

  /**
   *  Hides the identity of an observable sequence.
   * @returns {Observable} An observable sequence that hides the identity of the source sequence.
   */
  observableProto.asObservable = function () {
    var source = this;
    return new AnonymousObservable(function (o) { return source.subscribe(o); }, this);
  };

  /**
   *  Projects each element of an observable sequence into zero or more buffers which are produced based on element count information.
   *
   * @example
   *  var res = xs.bufferWithCount(10);
   *  var res = xs.bufferWithCount(10, 1);
   * @param {Number} count Length of each buffer.
   * @param {Number} [skip] Number of elements to skip between creation of consecutive buffers. If not provided, defaults to the count.
   * @returns {Observable} An observable sequence of buffers.
   */
  observableProto.bufferWithCount = function (count, skip) {
    if (typeof skip !== 'number') {
      skip = count;
    }
    return this.windowWithCount(count, skip).selectMany(function (x) {
      return x.toArray();
    }).where(function (x) {
      return x.length > 0;
    });
  };

  /**
   * Dematerializes the explicit notification values of an observable sequence as implicit notifications.
   * @returns {Observable} An observable sequence exhibiting the behavior corresponding to the source sequence's notification values.
   */
  observableProto.dematerialize = function () {
    var source = this;
    return new AnonymousObservable(function (o) {
      return source.subscribe(function (x) { return x.accept(o); }, function(e) { o.onError(e); }, function () { o.onCompleted(); });
    }, this);
  };

  /**
   *  Returns an observable sequence that contains only distinct contiguous elements according to the keySelector and the comparer.
   *
   *  var obs = observable.distinctUntilChanged();
   *  var obs = observable.distinctUntilChanged(function (x) { return x.id; });
   *  var obs = observable.distinctUntilChanged(function (x) { return x.id; }, function (x, y) { return x === y; });
   *
   * @param {Function} [keySelector] A function to compute the comparison key for each element. If not provided, it projects the value.
   * @param {Function} [comparer] Equality comparer for computed key values. If not provided, defaults to an equality comparer function.
   * @returns {Observable} An observable sequence only containing the distinct contiguous elements, based on a computed key value, from the source sequence.
   */
  observableProto.distinctUntilChanged = function (keySelector, comparer) {
    var source = this;
    comparer || (comparer = defaultComparer);
    return new AnonymousObservable(function (o) {
      var hasCurrentKey = false, currentKey;
      return source.subscribe(function (value) {
        var key = value;
        if (keySelector) {
          try {
            key = keySelector(value);
          } catch (e) {
            o.onError(e);
            return;
          }
        }
        if (hasCurrentKey) {
          try {
            var comparerEquals = comparer(currentKey, key);
          } catch (e) {
            o.onError(e);
            return;
          }
        }
        if (!hasCurrentKey || !comparerEquals) {
          hasCurrentKey = true;
          currentKey = key;
          o.onNext(value);
        }
      }, function (e) { o.onError(e); }, function () { o.onCompleted(); });
    }, this);
  };

  /**
   *  Invokes an action for each element in the observable sequence and invokes an action upon graceful or exceptional termination of the observable sequence.
   *  This method can be used for debugging, logging, etc. of query behavior by intercepting the message stream to run arbitrary actions for messages on the pipeline.
   * @param {Function | Observer} observerOrOnNext Action to invoke for each element in the observable sequence or an observer.
   * @param {Function} [onError]  Action to invoke upon exceptional termination of the observable sequence. Used if only the observerOrOnNext parameter is also a function.
   * @param {Function} [onCompleted]  Action to invoke upon graceful termination of the observable sequence. Used if only the observerOrOnNext parameter is also a function.
   * @returns {Observable} The source sequence with the side-effecting behavior applied.
   */
  observableProto['do'] = observableProto.tap = observableProto.doAction = function (observerOrOnNext, onError, onCompleted) {
    var source = this;
    return new AnonymousObservable(function (observer) {
      var tapObserver = !observerOrOnNext || isFunction(observerOrOnNext) ?
        observerCreate(observerOrOnNext || noop, onError || noop, onCompleted || noop) :
        observerOrOnNext;

      return source.subscribe(function (x) {
        try {
          tapObserver.onNext(x);
        } catch (e) {
          observer.onError(e);
        }
        observer.onNext(x);
      }, function (err) {
          try {
            tapObserver.onError(err);
          } catch (e) {
            observer.onError(e);
          }
        observer.onError(err);
      }, function () {
        try {
          tapObserver.onCompleted();
        } catch (e) {
          observer.onError(e);
        }
        observer.onCompleted();
      });
    }, this);
  };

  /**
   *  Invokes an action for each element in the observable sequence.
   *  This method can be used for debugging, logging, etc. of query behavior by intercepting the message stream to run arbitrary actions for messages on the pipeline.
   * @param {Function} onNext Action to invoke for each element in the observable sequence.
   * @param {Any} [thisArg] Object to use as this when executing callback.
   * @returns {Observable} The source sequence with the side-effecting behavior applied.
   */
  observableProto.doOnNext = observableProto.tapOnNext = function (onNext, thisArg) {
    return this.tap(typeof thisArg !== 'undefined' ? function (x) { onNext.call(thisArg, x); } : onNext);
  };

  /**
   *  Invokes an action upon exceptional termination of the observable sequence.
   *  This method can be used for debugging, logging, etc. of query behavior by intercepting the message stream to run arbitrary actions for messages on the pipeline.
   * @param {Function} onError Action to invoke upon exceptional termination of the observable sequence.
   * @param {Any} [thisArg] Object to use as this when executing callback.
   * @returns {Observable} The source sequence with the side-effecting behavior applied.
   */
  observableProto.doOnError = observableProto.tapOnError = function (onError, thisArg) {
    return this.tap(noop, typeof thisArg !== 'undefined' ? function (e) { onError.call(thisArg, e); } : onError);
  };

  /**
   *  Invokes an action upon graceful termination of the observable sequence.
   *  This method can be used for debugging, logging, etc. of query behavior by intercepting the message stream to run arbitrary actions for messages on the pipeline.
   * @param {Function} onCompleted Action to invoke upon graceful termination of the observable sequence.
   * @param {Any} [thisArg] Object to use as this when executing callback.
   * @returns {Observable} The source sequence with the side-effecting behavior applied.
   */
  observableProto.doOnCompleted = observableProto.tapOnCompleted = function (onCompleted, thisArg) {
    return this.tap(noop, null, typeof thisArg !== 'undefined' ? function () { onCompleted.call(thisArg); } : onCompleted);
  };

  /**
   *  Invokes a specified action after the source observable sequence terminates gracefully or exceptionally.
   * @param {Function} finallyAction Action to invoke after the source observable sequence terminates.
   * @returns {Observable} Source sequence with the action-invoking termination behavior applied.
   */
  observableProto['finally'] = observableProto.ensure = function (action) {
    var source = this;
    return new AnonymousObservable(function (observer) {
      var subscription;
      try {
        subscription = source.subscribe(observer);
      } catch (e) {
        action();
        throw e;
      }
      return disposableCreate(function () {
        try {
          subscription.dispose();
        } catch (e) {
          throw e;
        } finally {
          action();
        }
      });
    }, this);
  };

  /**
   * @deprecated use #finally or #ensure instead.
   */
  observableProto.finallyAction = function (action) {
    //deprecate('finallyAction', 'finally or ensure');
    return this.ensure(action);
  };

  /**
   *  Ignores all elements in an observable sequence leaving only the termination messages.
   * @returns {Observable} An empty observable sequence that signals termination, successful or exceptional, of the source sequence.
   */
  observableProto.ignoreElements = function () {
    var source = this;
    return new AnonymousObservable(function (o) {
      return source.subscribe(noop, function (e) { o.onError(e); }, function () { o.onCompleted(); });
    }, source);
  };

  /**
   *  Materializes the implicit notifications of an observable sequence as explicit notification values.
   * @returns {Observable} An observable sequence containing the materialized notification values from the source sequence.
   */
  observableProto.materialize = function () {
    var source = this;
    return new AnonymousObservable(function (observer) {
      return source.subscribe(function (value) {
        observer.onNext(notificationCreateOnNext(value));
      }, function (e) {
        observer.onNext(notificationCreateOnError(e));
        observer.onCompleted();
      }, function () {
        observer.onNext(notificationCreateOnCompleted());
        observer.onCompleted();
      });
    }, source);
  };

  /**
   *  Repeats the observable sequence a specified number of times. If the repeat count is not specified, the sequence repeats indefinitely.
   * @param {Number} [repeatCount]  Number of times to repeat the sequence. If not provided, repeats the sequence indefinitely.
   * @returns {Observable} The observable sequence producing the elements of the given sequence repeatedly.
   */
  observableProto.repeat = function (repeatCount) {
    return enumerableRepeat(this, repeatCount).concat();
  };

  /**
   *  Repeats the source observable sequence the specified number of times or until it successfully terminates. If the retry count is not specified, it retries indefinitely.
   *  Note if you encounter an error and want it to retry once, then you must use .retry(2);
   *
   * @example
   *  var res = retried = retry.repeat();
   *  var res = retried = retry.repeat(2);
   * @param {Number} [retryCount]  Number of times to retry the sequence. If not provided, retry the sequence indefinitely.
   * @returns {Observable} An observable sequence producing the elements of the given sequence repeatedly until it terminates successfully.
   */
  observableProto.retry = function (retryCount) {
    return enumerableRepeat(this, retryCount).catchError();
  };

  /**
   *  Repeats the source observable sequence upon error each time the notifier emits or until it successfully terminates. 
   *  if the notifier completes, the observable sequence completes.
   *
   * @example
   *  var timer = Observable.timer(500);
   *  var source = observable.retryWhen(timer);
   * @param {Observable} [notifier] An observable that triggers the retries or completes the observable with onNext or onCompleted respectively.
   * @returns {Observable} An observable sequence producing the elements of the given sequence repeatedly until it terminates successfully.
   */
  observableProto.retryWhen = function (notifier) {
    return enumerableRepeat(this).catchErrorWhen(notifier);
  };
  /**
   *  Applies an accumulator function over an observable sequence and returns each intermediate result. The optional seed value is used as the initial accumulator value.
   *  For aggregation behavior with no intermediate results, see Observable.aggregate.
   * @example
   *  var res = source.scan(function (acc, x) { return acc + x; });
   *  var res = source.scan(0, function (acc, x) { return acc + x; });
   * @param {Mixed} [seed] The initial accumulator value.
   * @param {Function} accumulator An accumulator function to be invoked on each element.
   * @returns {Observable} An observable sequence containing the accumulated values.
   */
  observableProto.scan = function () {
    var hasSeed = false, seed, accumulator, source = this;
    if (arguments.length === 2) {
      hasSeed = true;
      seed = arguments[0];
      accumulator = arguments[1];
    } else {
      accumulator = arguments[0];
    }
    return new AnonymousObservable(function (o) {
      var hasAccumulation, accumulation, hasValue;
      return source.subscribe (
        function (x) {
          !hasValue && (hasValue = true);
          try {
            if (hasAccumulation) {
              accumulation = accumulator(accumulation, x);
            } else {
              accumulation = hasSeed ? accumulator(seed, x) : x;
              hasAccumulation = true;
            }
          } catch (e) {
            o.onError(e);
            return;
          }

          o.onNext(accumulation);
        },
        function (e) { o.onError(e); },
        function () {
          !hasValue && hasSeed && o.onNext(seed);
          o.onCompleted();
        }
      );
    }, source);
  };

  /**
   *  Bypasses a specified number of elements at the end of an observable sequence.
   * @description
   *  This operator accumulates a queue with a length enough to store the first `count` elements. As more elements are
   *  received, elements are taken from the front of the queue and produced on the result sequence. This causes elements to be delayed.
   * @param count Number of elements to bypass at the end of the source sequence.
   * @returns {Observable} An observable sequence containing the source sequence elements except for the bypassed ones at the end.
   */
  observableProto.skipLast = function (count) {
    if (count < 0) { throw new ArgumentOutOfRangeError(); }
    var source = this;
    return new AnonymousObservable(function (o) {
      var q = [];
      return source.subscribe(function (x) {
        q.push(x);
        q.length > count && o.onNext(q.shift());
      }, function (e) { o.onError(e); }, function () { o.onCompleted(); });
    }, source);
  };

  /**
   *  Prepends a sequence of values to an observable sequence with an optional scheduler and an argument list of values to prepend.
   *  @example
   *  var res = source.startWith(1, 2, 3);
   *  var res = source.startWith(Rx.Scheduler.timeout, 1, 2, 3);
   * @param {Arguments} args The specified values to prepend to the observable sequence
   * @returns {Observable} The source sequence prepended with the specified values.
   */
  observableProto.startWith = function () {
    var values, scheduler, start = 0;
    if (!!arguments.length && isScheduler(arguments[0])) {
      scheduler = arguments[0];
      start = 1;
    } else {
      scheduler = immediateScheduler;
    }
    for(var args = [], i = start, len = arguments.length; i < len; i++) { args.push(arguments[i]); }
    return enumerableOf([observableFromArray(args, scheduler), this]).concat();
  };

  /**
   *  Returns a specified number of contiguous elements from the end of an observable sequence.
   * @description
   *  This operator accumulates a buffer with a length enough to store elements count elements. Upon completion of
   *  the source sequence, this buffer is drained on the result sequence. This causes the elements to be delayed.
   * @param {Number} count Number of elements to take from the end of the source sequence.
   * @returns {Observable} An observable sequence containing the specified number of elements from the end of the source sequence.
   */
  observableProto.takeLast = function (count) {
    if (count < 0) { throw new ArgumentOutOfRangeError(); }
    var source = this;
    return new AnonymousObservable(function (o) {
      var q = [];
      return source.subscribe(function (x) {
        q.push(x);
        q.length > count && q.shift();
      }, function (e) { o.onError(e); }, function () {
        while (q.length > 0) { o.onNext(q.shift()); }
        o.onCompleted();
      });
    }, source);
  };

  /**
   *  Returns an array with the specified number of contiguous elements from the end of an observable sequence.
   *
   * @description
   *  This operator accumulates a buffer with a length enough to store count elements. Upon completion of the
   *  source sequence, this buffer is produced on the result sequence.
   * @param {Number} count Number of elements to take from the end of the source sequence.
   * @returns {Observable} An observable sequence containing a single array with the specified number of elements from the end of the source sequence.
   */
  observableProto.takeLastBuffer = function (count) {
    var source = this;
    return new AnonymousObservable(function (o) {
      var q = [];
      return source.subscribe(function (x) {
        q.push(x);
        q.length > count && q.shift();
      }, function (e) { o.onError(e); }, function () {
        o.onNext(q);
        o.onCompleted();
      });
    }, source);
  };

  /**
   *  Projects each element of an observable sequence into zero or more windows which are produced based on element count information.
   *
   *  var res = xs.windowWithCount(10);
   *  var res = xs.windowWithCount(10, 1);
   * @param {Number} count Length of each window.
   * @param {Number} [skip] Number of elements to skip between creation of consecutive windows. If not specified, defaults to the count.
   * @returns {Observable} An observable sequence of windows.
   */
  observableProto.windowWithCount = function (count, skip) {
    var source = this;
    +count || (count = 0);
    Math.abs(count) === Infinity && (count = 0);
    if (count <= 0) { throw new ArgumentOutOfRangeError(); }
    skip == null && (skip = count);
    +skip || (skip = 0);
    Math.abs(skip) === Infinity && (skip = 0);

    if (skip <= 0) { throw new ArgumentOutOfRangeError(); }
    return new AnonymousObservable(function (observer) {
      var m = new SingleAssignmentDisposable(),
        refCountDisposable = new RefCountDisposable(m),
        n = 0,
        q = [];

      function createWindow () {
        var s = new Subject();
        q.push(s);
        observer.onNext(addRef(s, refCountDisposable));
      }

      createWindow();

      m.setDisposable(source.subscribe(
        function (x) {
          for (var i = 0, len = q.length; i < len; i++) { q[i].onNext(x); }
          var c = n - count + 1;
          c >= 0 && c % skip === 0 && q.shift().onCompleted();
          ++n % skip === 0 && createWindow();
        },
        function (e) {
          while (q.length > 0) { q.shift().onError(e); }
          observer.onError(e);
        },
        function () {
          while (q.length > 0) { q.shift().onCompleted(); }
          observer.onCompleted();
        }
      ));
      return refCountDisposable;
    }, source);
  };

  function concatMap(source, selector, thisArg) {
    var selectorFunc = bindCallback(selector, thisArg, 3);
    return source.map(function (x, i) {
      var result = selectorFunc(x, i, source);
      isPromise(result) && (result = observableFromPromise(result));
      (isArrayLike(result) || isIterable(result)) && (result = observableFrom(result));
      return result;
    }).concatAll();
  }

  /**
   *  One of the Following:
   *  Projects each element of an observable sequence to an observable sequence and merges the resulting observable sequences into one observable sequence.
   *
   * @example
   *  var res = source.concatMap(function (x) { return Rx.Observable.range(0, x); });
   *  Or:
   *  Projects each element of an observable sequence to an observable sequence, invokes the result selector for the source element and each of the corresponding inner sequence's elements, and merges the results into one observable sequence.
   *
   *  var res = source.concatMap(function (x) { return Rx.Observable.range(0, x); }, function (x, y) { return x + y; });
   *  Or:
   *  Projects each element of the source observable sequence to the other observable sequence and merges the resulting observable sequences into one observable sequence.
   *
   *  var res = source.concatMap(Rx.Observable.fromArray([1,2,3]));
   * @param {Function} selector A transform function to apply to each element or an observable sequence to project each element from the
   * source sequence onto which could be either an observable or Promise.
   * @param {Function} [resultSelector]  A transform function to apply to each element of the intermediate sequence.
   * @returns {Observable} An observable sequence whose elements are the result of invoking the one-to-many transform function collectionSelector on each element of the input sequence and then mapping each of those sequence elements and their corresponding source element to a result element.
   */
  observableProto.selectConcat = observableProto.concatMap = function (selector, resultSelector, thisArg) {
    if (isFunction(selector) && isFunction(resultSelector)) {
      return this.concatMap(function (x, i) {
        var selectorResult = selector(x, i);
        isPromise(selectorResult) && (selectorResult = observableFromPromise(selectorResult));
        (isArrayLike(selectorResult) || isIterable(selectorResult)) && (selectorResult = observableFrom(selectorResult));

        return selectorResult.map(function (y, i2) {
          return resultSelector(x, y, i, i2);
        });
      });
    }
    return isFunction(selector) ?
      concatMap(this, selector, thisArg) :
      concatMap(this, function () { return selector; });
  };

  /**
   * Projects each notification of an observable sequence to an observable sequence and concats the resulting observable sequences into one observable sequence.
   * @param {Function} onNext A transform function to apply to each element; the second parameter of the function represents the index of the source element.
   * @param {Function} onError A transform function to apply when an error occurs in the source sequence.
   * @param {Function} onCompleted A transform function to apply when the end of the source sequence is reached.
   * @param {Any} [thisArg] An optional "this" to use to invoke each transform.
   * @returns {Observable} An observable sequence whose elements are the result of invoking the one-to-many transform function corresponding to each notification in the input sequence.
   */
  observableProto.concatMapObserver = observableProto.selectConcatObserver = function(onNext, onError, onCompleted, thisArg) {
    var source = this,
        onNextFunc = bindCallback(onNext, thisArg, 2),
        onErrorFunc = bindCallback(onError, thisArg, 1),
        onCompletedFunc = bindCallback(onCompleted, thisArg, 0);
    return new AnonymousObservable(function (observer) {
      var index = 0;
      return source.subscribe(
        function (x) {
          var result;
          try {
            result = onNextFunc(x, index++);
          } catch (e) {
            observer.onError(e);
            return;
          }
          isPromise(result) && (result = observableFromPromise(result));
          observer.onNext(result);
        },
        function (err) {
          var result;
          try {
            result = onErrorFunc(err);
          } catch (e) {
            observer.onError(e);
            return;
          }
          isPromise(result) && (result = observableFromPromise(result));
          observer.onNext(result);
          observer.onCompleted();
        },
        function () {
          var result;
          try {
            result = onCompletedFunc();
          } catch (e) {
            observer.onError(e);
            return;
          }
          isPromise(result) && (result = observableFromPromise(result));
          observer.onNext(result);
          observer.onCompleted();
        });
    }, this).concatAll();
  };

    /**
     *  Returns the elements of the specified sequence or the specified value in a singleton sequence if the sequence is empty.
     *
     *  var res = obs = xs.defaultIfEmpty();
     *  2 - obs = xs.defaultIfEmpty(false);
     *
     * @memberOf Observable#
     * @param defaultValue The value to return if the sequence is empty. If not provided, this defaults to null.
     * @returns {Observable} An observable sequence that contains the specified default value if the source is empty; otherwise, the elements of the source itself.
     */
    observableProto.defaultIfEmpty = function (defaultValue) {
      var source = this;
      defaultValue === undefined && (defaultValue = null);
      return new AnonymousObservable(function (observer) {
        var found = false;
        return source.subscribe(function (x) {
          found = true;
          observer.onNext(x);
        },
        function (e) { observer.onError(e); }, 
        function () {
          !found && observer.onNext(defaultValue);
          observer.onCompleted();
        });
      }, source);
    };

  // Swap out for Array.findIndex
  function arrayIndexOfComparer(array, item, comparer) {
    for (var i = 0, len = array.length; i < len; i++) {
      if (comparer(array[i], item)) { return i; }
    }
    return -1;
  }

  function HashSet(comparer) {
    this.comparer = comparer;
    this.set = [];
  }
  HashSet.prototype.push = function(value) {
    var retValue = arrayIndexOfComparer(this.set, value, this.comparer) === -1;
    retValue && this.set.push(value);
    return retValue;
  };

  /**
   *  Returns an observable sequence that contains only distinct elements according to the keySelector and the comparer.
   *  Usage of this operator should be considered carefully due to the maintenance of an internal lookup structure which can grow large.
   *
   * @example
   *  var res = obs = xs.distinct();
   *  2 - obs = xs.distinct(function (x) { return x.id; });
   *  2 - obs = xs.distinct(function (x) { return x.id; }, function (a,b) { return a === b; });
   * @param {Function} [keySelector]  A function to compute the comparison key for each element.
   * @param {Function} [comparer]  Used to compare items in the collection.
   * @returns {Observable} An observable sequence only containing the distinct elements, based on a computed key value, from the source sequence.
   */
  observableProto.distinct = function (keySelector, comparer) {
    var source = this;
    comparer || (comparer = defaultComparer);
    return new AnonymousObservable(function (o) {
      var hashSet = new HashSet(comparer);
      return source.subscribe(function (x) {
        var key = x;

        if (keySelector) {
          try {
            key = keySelector(x);
          } catch (e) {
            o.onError(e);
            return;
          }
        }
        hashSet.push(key) && o.onNext(x);
      },
      function (e) { o.onError(e); }, function () { o.onCompleted(); });
    }, this);
  };

  var MapObservable = (function (__super__) {
    inherits(MapObservable, __super__);

    function MapObservable(source, selector, thisArg) {
      this.source = source;
      this.selector = bindCallback(selector, thisArg, 3);
      __super__.call(this);
    }

    MapObservable.prototype.internalMap = function (selector, thisArg) {
      var self = this;
      return new MapObservable(this.source, function (x, i, o) { return selector.call(this, self.selector(x, i, o), i, o); }, thisArg)
    };

    MapObservable.prototype.subscribeCore = function (observer) {
      return this.source.subscribe(new MapObserver(observer, this.selector, this));
    };

    return MapObservable;

  }(ObservableBase));

  function MapObserver(observer, selector, source) {
    this.observer = observer;
    this.selector = selector;
    this.source = source;
    this.i = 0;
    this.isStopped = false;
  }

  MapObserver.prototype.onNext = function(x) {
    if (this.isStopped) { return; }
    var result = tryCatch(this.selector).call(this, x, this.i++, this.source);
    if (result === errorObj) {
      return this.observer.onError(result.e);
    }
    this.observer.onNext(result);
  };
  MapObserver.prototype.onError = function (e) {
    if(!this.isStopped) { this.isStopped = true; this.observer.onError(e); }
  };
  MapObserver.prototype.onCompleted = function () {
    if(!this.isStopped) { this.isStopped = true; this.observer.onCompleted(); }
  };
  MapObserver.prototype.dispose = function() { this.isStopped = true; };
  MapObserver.prototype.fail = function (e) {
    if (!this.isStopped) {
      this.isStopped = true;
      this.observer.onError(e);
      return true;
    }

    return false;
  };

  /**
  * Projects each element of an observable sequence into a new form by incorporating the element's index.
  * @param {Function} selector A transform function to apply to each source element; the second parameter of the function represents the index of the source element.
  * @param {Any} [thisArg] Object to use as this when executing callback.
  * @returns {Observable} An observable sequence whose elements are the result of invoking the transform function on each element of source.
  */
  observableProto.map = observableProto.select = function (selector, thisArg) {
    var selectorFn = typeof selector === 'function' ? selector : function () { return selector; };
    return this instanceof MapObservable ?
      this.internalMap(selectorFn, thisArg) :
      new MapObservable(this, selectorFn, thisArg);
  };

  /**
   * Retrieves the value of a specified nested property from all elements in
   * the Observable sequence.
   * @param {Arguments} arguments The nested properties to pluck.
   * @returns {Observable} Returns a new Observable sequence of property values.
   */
  observableProto.pluck = function () {
    var args = arguments, len = arguments.length;
    if (len === 0) { throw new Error('List of properties cannot be empty.'); }
    return this.map(function (x) {
      var currentProp = x;
      for (var i = 0; i < len; i++) {
        var p = currentProp[args[i]];
        if (typeof p !== 'undefined') {
          currentProp = p;
        } else {
          return undefined;
        }
      }
      return currentProp;
    });
  };

  /**
   * Projects each notification of an observable sequence to an observable sequence and merges the resulting observable sequences into one observable sequence.
   * @param {Function} onNext A transform function to apply to each element; the second parameter of the function represents the index of the source element.
   * @param {Function} onError A transform function to apply when an error occurs in the source sequence.
   * @param {Function} onCompleted A transform function to apply when the end of the source sequence is reached.
   * @param {Any} [thisArg] An optional "this" to use to invoke each transform.
   * @returns {Observable} An observable sequence whose elements are the result of invoking the one-to-many transform function corresponding to each notification in the input sequence.
   */
  observableProto.flatMapObserver = observableProto.selectManyObserver = function (onNext, onError, onCompleted, thisArg) {
    var source = this;
    return new AnonymousObservable(function (observer) {
      var index = 0;

      return source.subscribe(
        function (x) {
          var result;
          try {
            result = onNext.call(thisArg, x, index++);
          } catch (e) {
            observer.onError(e);
            return;
          }
          isPromise(result) && (result = observableFromPromise(result));
          observer.onNext(result);
        },
        function (err) {
          var result;
          try {
            result = onError.call(thisArg, err);
          } catch (e) {
            observer.onError(e);
            return;
          }
          isPromise(result) && (result = observableFromPromise(result));
          observer.onNext(result);
          observer.onCompleted();
        },
        function () {
          var result;
          try {
            result = onCompleted.call(thisArg);
          } catch (e) {
            observer.onError(e);
            return;
          }
          isPromise(result) && (result = observableFromPromise(result));
          observer.onNext(result);
          observer.onCompleted();
        });
    }, source).mergeAll();
  };

  function flatMap(source, selector, thisArg) {
    var selectorFunc = bindCallback(selector, thisArg, 3);
    return source.map(function (x, i) {
      var result = selectorFunc(x, i, source);
      isPromise(result) && (result = observableFromPromise(result));
      (isArrayLike(result) || isIterable(result)) && (result = observableFrom(result));
      return result;
    }).mergeAll();
  }

  /**
   *  One of the Following:
   *  Projects each element of an observable sequence to an observable sequence and merges the resulting observable sequences into one observable sequence.
   *
   * @example
   *  var res = source.selectMany(function (x) { return Rx.Observable.range(0, x); });
   *  Or:
   *  Projects each element of an observable sequence to an observable sequence, invokes the result selector for the source element and each of the corresponding inner sequence's elements, and merges the results into one observable sequence.
   *
   *  var res = source.selectMany(function (x) { return Rx.Observable.range(0, x); }, function (x, y) { return x + y; });
   *  Or:
   *  Projects each element of the source observable sequence to the other observable sequence and merges the resulting observable sequences into one observable sequence.
   *
   *  var res = source.selectMany(Rx.Observable.fromArray([1,2,3]));
   * @param {Function} selector A transform function to apply to each element or an observable sequence to project each element from the source sequence onto which could be either an observable or Promise.
   * @param {Function} [resultSelector]  A transform function to apply to each element of the intermediate sequence.
   * @param {Any} [thisArg] Object to use as this when executing callback.
   * @returns {Observable} An observable sequence whose elements are the result of invoking the one-to-many transform function collectionSelector on each element of the input sequence and then mapping each of those sequence elements and their corresponding source element to a result element.
   */
  observableProto.selectMany = observableProto.flatMap = function (selector, resultSelector, thisArg) {
    if (isFunction(selector) && isFunction(resultSelector)) {
      return this.flatMap(function (x, i) {
        var selectorResult = selector(x, i);
        isPromise(selectorResult) && (selectorResult = observableFromPromise(selectorResult));
        (isArrayLike(selectorResult) || isIterable(selectorResult)) && (selectorResult = observableFrom(selectorResult));

        return selectorResult.map(function (y, i2) {
          return resultSelector(x, y, i, i2);
        });
      }, thisArg);
    }
    return isFunction(selector) ?
      flatMap(this, selector, thisArg) :
      flatMap(this, function () { return selector; });
  };

  /**
   *  Projects each element of an observable sequence into a new sequence of observable sequences by incorporating the element's index and then
   *  transforms an observable sequence of observable sequences into an observable sequence producing values only from the most recent observable sequence.
   * @param {Function} selector A transform function to apply to each source element; the second parameter of the function represents the index of the source element.
   * @param {Any} [thisArg] Object to use as this when executing callback.
   * @returns {Observable} An observable sequence whose elements are the result of invoking the transform function on each element of source producing an Observable of Observable sequences
   *  and that at any point in time produces the elements of the most recent inner observable sequence that has been received.
   */
  observableProto.selectSwitch = observableProto.flatMapLatest = observableProto.switchMap = function (selector, thisArg) {
    return this.select(selector, thisArg).switchLatest();
  };

  /**
   * Bypasses a specified number of elements in an observable sequence and then returns the remaining elements.
   * @param {Number} count The number of elements to skip before returning the remaining elements.
   * @returns {Observable} An observable sequence that contains the elements that occur after the specified index in the input sequence.
   */
  observableProto.skip = function (count) {
    if (count < 0) { throw new ArgumentOutOfRangeError(); }
    var source = this;
    return new AnonymousObservable(function (o) {
      var remaining = count;
      return source.subscribe(function (x) {
        if (remaining <= 0) {
          o.onNext(x);
        } else {
          remaining--;
        }
      }, function (e) { o.onError(e); }, function () { o.onCompleted(); });
    }, source);
  };

  /**
   *  Bypasses elements in an observable sequence as long as a specified condition is true and then returns the remaining elements.
   *  The element's index is used in the logic of the predicate function.
   *
   *  var res = source.skipWhile(function (value) { return value < 10; });
   *  var res = source.skipWhile(function (value, index) { return value < 10 || index < 10; });
   * @param {Function} predicate A function to test each element for a condition; the second parameter of the function represents the index of the source element.
   * @param {Any} [thisArg] Object to use as this when executing callback.
   * @returns {Observable} An observable sequence that contains the elements from the input sequence starting at the first element in the linear series that does not pass the test specified by predicate.
   */
  observableProto.skipWhile = function (predicate, thisArg) {
    var source = this,
        callback = bindCallback(predicate, thisArg, 3);
    return new AnonymousObservable(function (o) {
      var i = 0, running = false;
      return source.subscribe(function (x) {
        if (!running) {
          try {
            running = !callback(x, i++, source);
          } catch (e) {
            o.onError(e);
            return;
          }
        }
        running && o.onNext(x);
      }, function (e) { o.onError(e); }, function () { o.onCompleted(); });
    }, source);
  };

  /**
   *  Returns a specified number of contiguous elements from the start of an observable sequence, using the specified scheduler for the edge case of take(0).
   *
   *  var res = source.take(5);
   *  var res = source.take(0, Rx.Scheduler.timeout);
   * @param {Number} count The number of elements to return.
   * @param {Scheduler} [scheduler] Scheduler used to produce an OnCompleted message in case <paramref name="count count</paramref> is set to 0.
   * @returns {Observable} An observable sequence that contains the specified number of elements from the start of the input sequence.
   */
  observableProto.take = function (count, scheduler) {
    if (count < 0) { throw new ArgumentOutOfRangeError(); }
    if (count === 0) { return observableEmpty(scheduler); }
    var source = this;
    return new AnonymousObservable(function (o) {
      var remaining = count;
      return source.subscribe(function (x) {
        if (remaining-- > 0) {
          o.onNext(x);
          remaining === 0 && o.onCompleted();
        }
      }, function (e) { o.onError(e); }, function () { o.onCompleted(); });
    }, source);
  };

  /**
   *  Returns elements from an observable sequence as long as a specified condition is true.
   *  The element's index is used in the logic of the predicate function.
   * @param {Function} predicate A function to test each element for a condition; the second parameter of the function represents the index of the source element.
   * @param {Any} [thisArg] Object to use as this when executing callback.
   * @returns {Observable} An observable sequence that contains the elements from the input sequence that occur before the element at which the test no longer passes.
   */
  observableProto.takeWhile = function (predicate, thisArg) {
    var source = this,
        callback = bindCallback(predicate, thisArg, 3);
    return new AnonymousObservable(function (o) {
      var i = 0, running = true;
      return source.subscribe(function (x) {
        if (running) {
          try {
            running = callback(x, i++, source);
          } catch (e) {
            o.onError(e);
            return;
          }
          if (running) {
            o.onNext(x);
          } else {
            o.onCompleted();
          }
        }
      }, function (e) { o.onError(e); }, function () { o.onCompleted(); });
    }, source);
  };

  var FilterObservable = (function (__super__) {
    inherits(FilterObservable, __super__);

    function FilterObservable(source, predicate, thisArg) {
      this.source = source;
      this.predicate = bindCallback(predicate, thisArg, 3);
      __super__.call(this);
    }

    FilterObservable.prototype.subscribeCore = function (observer) {
      return this.source.subscribe(new FilterObserver(observer, this.predicate, this));
    };

    FilterObservable.prototype.internalFilter = function(predicate, thisArg) {
      var self = this;
      return new FilterObservable(this.source, function(x, i, o) { return self.predicate(x, i, o) && predicate.call(this, x, i, o); }, thisArg);
    };

    return FilterObservable;

  }(ObservableBase));

  function FilterObserver(observer, predicate, source) {
    this.observer = observer;
    this.predicate = predicate;
    this.source = source;
    this.i = 0;
    this.isStopped = false;
  }

  FilterObserver.prototype.onNext = function(x) {
    if (this.isStopped) { return; }
    var shouldYield = tryCatch(this.predicate).call(this, x, this.i++, this.source);
    if (shouldYield === errorObj) {
      return this.observer.onError(shouldYield.e);
    }
    shouldYield && this.observer.onNext(x);
  };
  FilterObserver.prototype.onError = function (e) {
    if(!this.isStopped) { this.isStopped = true; this.observer.onError(e); }
  };
  FilterObserver.prototype.onCompleted = function () {
    if(!this.isStopped) { this.isStopped = true; this.observer.onCompleted(); }
  };
  FilterObserver.prototype.dispose = function() { this.isStopped = true; };
  FilterObserver.prototype.fail = function (e) {
    if (!this.isStopped) {
      this.isStopped = true;
      this.observer.onError(e);
      return true;
    }
    return false;
  };

  /**
  *  Filters the elements of an observable sequence based on a predicate by incorporating the element's index.
  * @param {Function} predicate A function to test each source element for a condition; the second parameter of the function represents the index of the source element.
  * @param {Any} [thisArg] Object to use as this when executing callback.
  * @returns {Observable} An observable sequence that contains elements from the input sequence that satisfy the condition.
  */
  observableProto.filter = observableProto.where = function (predicate, thisArg) {
    return this instanceof FilterObservable ? this.internalFilter(predicate, thisArg) :
      new FilterObservable(this, predicate, thisArg);
  };

  /**
   * Executes a transducer to transform the observable sequence
   * @param {Transducer} transducer A transducer to execute
   * @returns {Observable} An Observable sequence containing the results from the transducer.
   */
  observableProto.transduce = function(transducer) {
    var source = this;

    function transformForObserver(o) {
      return {
        '@@transducer/init': function() {
          return o;
        },
        '@@transducer/step': function(obs, input) {
          return obs.onNext(input);
        },
        '@@transducer/result': function(obs) {
          return obs.onCompleted();
        }
      };
    }

    return new AnonymousObservable(function(o) {
      var xform = transducer(transformForObserver(o));
      return source.subscribe(
        function(v) {
          try {
            xform['@@transducer/step'](o, v);
          } catch (e) {
            o.onError(e);
          }
        },
        function (e) { o.onError(e); },
        function() { xform['@@transducer/result'](o); }
      );
    }, source);
  };

  var AnonymousObservable = Rx.AnonymousObservable = (function (__super__) {
    inherits(AnonymousObservable, __super__);

    // Fix subscriber to check for undefined or function returned to decorate as Disposable
    function fixSubscriber(subscriber) {
      return subscriber && isFunction(subscriber.dispose) ? subscriber :
        isFunction(subscriber) ? disposableCreate(subscriber) : disposableEmpty;
    }

    function setDisposable(s, state) {
      var ado = state[0], subscribe = state[1];
      var sub = tryCatch(subscribe)(ado);

      if (sub === errorObj) {
        if(!ado.fail(errorObj.e)) { return thrower(errorObj.e); }
      }
      ado.setDisposable(fixSubscriber(sub));
    }

    function AnonymousObservable(subscribe, parent) {
      this.source = parent;

      function s(observer) {
        var ado = new AutoDetachObserver(observer), state = [ado, subscribe];

        if (currentThreadScheduler.scheduleRequired()) {
          currentThreadScheduler.scheduleWithState(state, setDisposable);
        } else {
          setDisposable(null, state);
        }
        return ado;
      }

      __super__.call(this, s);
    }

    return AnonymousObservable;

  }(Observable));

  var AutoDetachObserver = (function (__super__) {
    inherits(AutoDetachObserver, __super__);

    function AutoDetachObserver(observer) {
      __super__.call(this);
      this.observer = observer;
      this.m = new SingleAssignmentDisposable();
    }

    var AutoDetachObserverPrototype = AutoDetachObserver.prototype;

    AutoDetachObserverPrototype.next = function (value) {
      var result = tryCatch(this.observer.onNext).call(this.observer, value);
      if (result === errorObj) {
        this.dispose();
        thrower(result.e);
      }
    };

    AutoDetachObserverPrototype.error = function (err) {
      var result = tryCatch(this.observer.onError).call(this.observer, err);
      this.dispose();
      result === errorObj && thrower(result.e);
    };

    AutoDetachObserverPrototype.completed = function () {
      var result = tryCatch(this.observer.onCompleted).call(this.observer);
      this.dispose();
      result === errorObj && thrower(result.e);
    };

    AutoDetachObserverPrototype.setDisposable = function (value) { this.m.setDisposable(value); };
    AutoDetachObserverPrototype.getDisposable = function () { return this.m.getDisposable(); };

    AutoDetachObserverPrototype.dispose = function () {
      __super__.prototype.dispose.call(this);
      this.m.dispose();
    };

    return AutoDetachObserver;
  }(AbstractObserver));

  var InnerSubscription = function (subject, observer) {
    this.subject = subject;
    this.observer = observer;
  };

  InnerSubscription.prototype.dispose = function () {
    if (!this.subject.isDisposed && this.observer !== null) {
      var idx = this.subject.observers.indexOf(this.observer);
      this.subject.observers.splice(idx, 1);
      this.observer = null;
    }
  };

  /**
   *  Represents an object that is both an observable sequence as well as an observer.
   *  Each notification is broadcasted to all subscribed observers.
   */
  var Subject = Rx.Subject = (function (__super__) {
    function subscribe(observer) {
      checkDisposed(this);
      if (!this.isStopped) {
        this.observers.push(observer);
        return new InnerSubscription(this, observer);
      }
      if (this.hasError) {
        observer.onError(this.error);
        return disposableEmpty;
      }
      observer.onCompleted();
      return disposableEmpty;
    }

    inherits(Subject, __super__);

    /**
     * Creates a subject.
     */
    function Subject() {
      __super__.call(this, subscribe);
      this.isDisposed = false,
      this.isStopped = false,
      this.observers = [];
      this.hasError = false;
    }

    addProperties(Subject.prototype, Observer.prototype, {
      /**
       * Indicates whether the subject has observers subscribed to it.
       * @returns {Boolean} Indicates whether the subject has observers subscribed to it.
       */
      hasObservers: function () { return this.observers.length > 0; },
      /**
       * Notifies all subscribed observers about the end of the sequence.
       */
      onCompleted: function () {
        checkDisposed(this);
        if (!this.isStopped) {
          this.isStopped = true;
          for (var i = 0, os = cloneArray(this.observers), len = os.length; i < len; i++) {
            os[i].onCompleted();
          }

          this.observers.length = 0;
        }
      },
      /**
       * Notifies all subscribed observers about the exception.
       * @param {Mixed} error The exception to send to all observers.
       */
      onError: function (error) {
        checkDisposed(this);
        if (!this.isStopped) {
          this.isStopped = true;
          this.error = error;
          this.hasError = true;
          for (var i = 0, os = cloneArray(this.observers), len = os.length; i < len; i++) {
            os[i].onError(error);
          }

          this.observers.length = 0;
        }
      },
      /**
       * Notifies all subscribed observers about the arrival of the specified element in the sequence.
       * @param {Mixed} value The value to send to all observers.
       */
      onNext: function (value) {
        checkDisposed(this);
        if (!this.isStopped) {
          for (var i = 0, os = cloneArray(this.observers), len = os.length; i < len; i++) {
            os[i].onNext(value);
          }
        }
      },
      /**
       * Unsubscribe all observers and release resources.
       */
      dispose: function () {
        this.isDisposed = true;
        this.observers = null;
      }
    });

    /**
     * Creates a subject from the specified observer and observable.
     * @param {Observer} observer The observer used to send messages to the subject.
     * @param {Observable} observable The observable used to subscribe to messages sent from the subject.
     * @returns {Subject} Subject implemented using the given observer and observable.
     */
    Subject.create = function (observer, observable) {
      return new AnonymousSubject(observer, observable);
    };

    return Subject;
  }(Observable));

  /**
   *  Represents the result of an asynchronous operation.
   *  The last value before the OnCompleted notification, or the error received through OnError, is sent to all subscribed observers.
   */
  var AsyncSubject = Rx.AsyncSubject = (function (__super__) {

    function subscribe(observer) {
      checkDisposed(this);

      if (!this.isStopped) {
        this.observers.push(observer);
        return new InnerSubscription(this, observer);
      }

      if (this.hasError) {
        observer.onError(this.error);
      } else if (this.hasValue) {
        observer.onNext(this.value);
        observer.onCompleted();
      } else {
        observer.onCompleted();
      }

      return disposableEmpty;
    }

    inherits(AsyncSubject, __super__);

    /**
     * Creates a subject that can only receive one value and that value is cached for all future observations.
     * @constructor
     */
    function AsyncSubject() {
      __super__.call(this, subscribe);

      this.isDisposed = false;
      this.isStopped = false;
      this.hasValue = false;
      this.observers = [];
      this.hasError = false;
    }

    addProperties(AsyncSubject.prototype, Observer, {
      /**
       * Indicates whether the subject has observers subscribed to it.
       * @returns {Boolean} Indicates whether the subject has observers subscribed to it.
       */
      hasObservers: function () {
        checkDisposed(this);
        return this.observers.length > 0;
      },
      /**
       * Notifies all subscribed observers about the end of the sequence, also causing the last received value to be sent out (if any).
       */
      onCompleted: function () {
        var i, len;
        checkDisposed(this);
        if (!this.isStopped) {
          this.isStopped = true;
          var os = cloneArray(this.observers), len = os.length;

          if (this.hasValue) {
            for (i = 0; i < len; i++) {
              var o = os[i];
              o.onNext(this.value);
              o.onCompleted();
            }
          } else {
            for (i = 0; i < len; i++) {
              os[i].onCompleted();
            }
          }

          this.observers.length = 0;
        }
      },
      /**
       * Notifies all subscribed observers about the error.
       * @param {Mixed} error The Error to send to all observers.
       */
      onError: function (error) {
        checkDisposed(this);
        if (!this.isStopped) {
          this.isStopped = true;
          this.hasError = true;
          this.error = error;

          for (var i = 0, os = cloneArray(this.observers), len = os.length; i < len; i++) {
            os[i].onError(error);
          }

          this.observers.length = 0;
        }
      },
      /**
       * Sends a value to the subject. The last value received before successful termination will be sent to all subscribed and future observers.
       * @param {Mixed} value The value to store in the subject.
       */
      onNext: function (value) {
        checkDisposed(this);
        if (this.isStopped) { return; }
        this.value = value;
        this.hasValue = true;
      },
      /**
       * Unsubscribe all observers and release resources.
       */
      dispose: function () {
        this.isDisposed = true;
        this.observers = null;
        this.exception = null;
        this.value = null;
      }
    });

    return AsyncSubject;
  }(Observable));

  var AnonymousSubject = Rx.AnonymousSubject = (function (__super__) {
    inherits(AnonymousSubject, __super__);

    function subscribe(observer) {
      return this.observable.subscribe(observer);
    }

    function AnonymousSubject(observer, observable) {
      this.observer = observer;
      this.observable = observable;
      __super__.call(this, subscribe);
    }

    addProperties(AnonymousSubject.prototype, Observer.prototype, {
      onCompleted: function () {
        this.observer.onCompleted();
      },
      onError: function (error) {
        this.observer.onError(error);
      },
      onNext: function (value) {
        this.observer.onNext(value);
      }
    });

    return AnonymousSubject;
  }(Observable));

  if (typeof define == 'function' && typeof define.amd == 'object' && define.amd) {
    root.Rx = Rx;

    define(function() {
      return Rx;
    });
  } else if (freeExports && freeModule) {
    // in Node.js or RingoJS
    if (moduleExports) {
      (freeModule.exports = Rx).Rx = Rx;
    } else {
      freeExports.Rx = Rx;
    }
  } else {
    // in a browser or Rhino
    root.Rx = Rx;
  }

  // All code before this point will be filtered from stack traces.
  var rEndingLine = captureLine();

}.call(this));
