rx.lite.async.js

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

;(function (factory) {
  var objectTypes = {
    'function': true,
    'object': true
  };

  function checkGlobal(value) {
    return (value && value.Object === Object) ? value : null;
  }

  var freeExports = (objectTypes[typeof exports] && exports && !exports.nodeType) ? exports : null;
  var freeModule = (objectTypes[typeof module] && module && !module.nodeType) ? module : null;
  var freeGlobal = checkGlobal(freeExports && freeModule && typeof global === 'object' && global);
  var freeSelf = checkGlobal(objectTypes[typeof self] && self);
  var freeWindow = checkGlobal(objectTypes[typeof window] && window);
  var moduleExports = (freeModule && freeModule.exports === freeExports) ? freeExports : null;
  var thisGlobal = checkGlobal(objectTypes[typeof this] && this);
  var root = freeGlobal || ((freeWindow !== (thisGlobal && thisGlobal.window)) && freeWindow) || freeSelf || thisGlobal || Function('return this')();

  // Because of build optimizers
  if (typeof define === 'function' && define.amd) {
    define(['./rx.lite'], function (Rx, exports) {
      return factory(root, exports, Rx);
    });
  } else if (typeof module === 'object' && module && module.exports === freeExports) {
    module.exports = factory(root, module.exports, require('rx-lite'));
  } else {
    root.Rx = factory(root, {}, root.Rx);
  }
}.call(this, function (root, exp, Rx, undefined) {

  // Aliases
  var Observable = Rx.Observable,
    observableFromPromise = Observable.fromPromise,
    observableThrow = Observable.throwError,
    AnonymousObservable = Rx.AnonymousObservable,
    ObservableBase = Rx.ObservableBase,
    AsyncSubject = Rx.AsyncSubject,
    disposableCreate = Rx.Disposable.create,
    CompositeDisposable = Rx.CompositeDisposable,
    immediateScheduler = Rx.Scheduler.immediate,
    defaultScheduler = Rx.Scheduler['default'],
    inherits = Rx.internals.inherits,
    isScheduler = Rx.Scheduler.isScheduler,
    isPromise = Rx.helpers.isPromise,
    isFunction = Rx.helpers.isFunction,
    isIterable = Rx.helpers.isIterable,
    isArrayLike = Rx.helpers.isArrayLike;

  Observable.wrap = function (fn) {
    function createObservable() {
      return Observable.spawn.call(this, fn.apply(this, arguments));
    }

    createObservable.__generatorFunction__ = fn;
    return createObservable;
  };

  var spawn = Observable.spawn = function () {
    var gen = arguments[0], self = this, args = [];
    for (var i = 1, len = arguments.length; i < len; i++) { args.push(arguments[i]); }

    return new AnonymousObservable(function (o) {
      var g = new CompositeDisposable();

      if (isFunction(gen)) { gen = gen.apply(self, args); }
      if (!gen || !isFunction(gen.next)) {
        o.onNext(gen);
        return o.onCompleted();
      }

      function processGenerator(res) {
        var ret = tryCatch(gen.next).call(gen, res);
        if (ret === errorObj) { return o.onError(ret.e); }
        next(ret);
      }

      processGenerator();

      function onError(err) {
        var ret = tryCatch(gen.next).call(gen, err);
        if (ret === errorObj) { return o.onError(ret.e); }
        next(ret);
      }

      function next(ret) {
        if (ret.done) {
          o.onNext(ret.value);
          o.onCompleted();
          return;
        }
        var obs = toObservable.call(self, ret.value);
        var value = null;
        var hasValue = false;
        if (Observable.isObservable(obs)) {
          g.add(obs.subscribe(function(val) {
            hasValue = true;
            value = val;
          }, onError, function() {
            hasValue && processGenerator(value);
          }));
        } else {
          onError(new TypeError('type not supported'));
        }
      }

      return g;
    });
  };

  function toObservable(obj) {
    if (!obj) { return obj; }
    if (Observable.isObservable(obj)) { return obj; }
    if (isPromise(obj)) { return Observable.fromPromise(obj); }
    if (isGeneratorFunction(obj) || isGenerator(obj)) { return spawn.call(this, obj); }
    if (isFunction(obj)) { return thunkToObservable.call(this, obj); }
    if (isArrayLike(obj) || isIterable(obj)) { return arrayToObservable.call(this, obj); }
    if (isObject(obj)) {return objectToObservable.call(this, obj);}
    return obj;
  }

  function arrayToObservable (obj) {
    return Observable.from(obj).concatMap(function(o) {
      if(Observable.isObservable(o) || isObject(o)) {
        return toObservable.call(null, o);
      } else {
        return Rx.Observable.just(o);
      }
    }).toArray();
  }

  function objectToObservable (obj) {
    var results = new obj.constructor(), keys = Object.keys(obj), observables = [];
    for (var i = 0, len = keys.length; i < len; i++) {
      var key = keys[i];
      var observable = toObservable.call(this, obj[key]);

      if(observable && Observable.isObservable(observable)) {
        defer(observable, key);
      } else {
        results[key] = obj[key];
      }
    }

    return Observable.forkJoin.apply(Observable, observables).map(function() {
      return results;
    });


    function defer (observable, key) {
      results[key] = undefined;
      observables.push(observable.map(function (next) {
        results[key] = next;
      }));
    }
  }

  function thunkToObservable(fn) {
    var self = this;
    return new AnonymousObservable(function (o) {
      fn.call(self, function () {
        var err = arguments[0], res = arguments[1];
        if (err) { return o.onError(err); }
        if (arguments.length > 2) {
          var args = [];
          for (var i = 1, len = arguments.length; i < len; i++) { args.push(arguments[i]); }
          res = args;
        }
        o.onNext(res);
        o.onCompleted();
      });
    });
  }

  function isGenerator(obj) {
    return isFunction (obj.next) && isFunction (obj['throw']);
  }

  function isGeneratorFunction(obj) {
    var ctor = obj.constructor;
    if (!ctor) { return false; }
    if (ctor.name === 'GeneratorFunction' || ctor.displayName === 'GeneratorFunction') { return true; }
    return isGenerator(ctor.prototype);
  }

  function isObject(val) {
    return Object == val.constructor;
  }

  /**
   * Invokes the specified function asynchronously on the specified scheduler, surfacing the result through an observable sequence.
   *
   * @example
   * var res = Rx.Observable.start(function () { console.log('hello'); });
   * var res = Rx.Observable.start(function () { console.log('hello'); }, Rx.Scheduler.timeout);
   * var res = Rx.Observable.start(function () { this.log('hello'); }, Rx.Scheduler.timeout, console);
   *
   * @param {Function} func Function to run asynchronously.
   * @param {Scheduler} [scheduler]  Scheduler to run the function on. If not specified, defaults to Scheduler.timeout.
   * @param [context]  The context for the func parameter to be executed.  If not specified, defaults to undefined.
   * @returns {Observable} An observable sequence exposing the function's result value, or an exception.
   *
   * Remarks
   * * The function is called immediately, not during the subscription of the resulting sequence.
   * * Multiple subscriptions to the resulting sequence can observe the function's result.
   */
  Observable.start = function (func, context, scheduler) {
    return observableToAsync(func, context, scheduler)();
  };

  /**
   * Invokes the asynchronous function, surfacing the result through an observable sequence.
   * @param {Function} functionAsync Asynchronous function which returns a Promise to run.
   * @returns {Observable} An observable sequence exposing the function's result value, or an exception.
   */
  Observable.startAsync = function (functionAsync) {
    var promise = tryCatch(functionAsync)();
    if (promise === errorObj) { return observableThrow(promise.e); }
    return observableFromPromise(promise);
  };

  return Rx;
}));