es6/Observable.js

import { root } from './util/root';
import { toSubscriber } from './util/toSubscriber';
import { $$observable } from './symbol/observable';
/**
 * A representation of any set of values over any amount of time. This the most basic building block
 * of RxJS.
 *
 * @class Observable<T>
 */
export var Observable = (function () {
    /**
     * @constructor
     * @param {Function} subscribe the function that is  called when the Observable is
     * initially subscribed to. This function is given a Subscriber, to which new values
     * can be `next`ed, or an `error` method can be called to raise an error, or
     * `complete` can be called to notify of a successful completion.
     */
    function Observable(subscribe) {
        this._isScalar = false;
        if (subscribe) {
            this._subscribe = subscribe;
        }
    }
    /**
     * Creates a new Observable, with this Observable as the source, and the passed
     * operator defined as the new observable's operator.
     * @method lift
     * @param {Operator} operator the operator defining the operation to take on the observable
     * @return {Observable} a new observable with the Operator applied
     */
    Observable.prototype.lift = function (operator) {
        var observable = new Observable();
        observable.source = this;
        observable.operator = operator;
        return observable;
    };
    Observable.prototype.subscribe = function (observerOrNext, error, complete) {
        var operator = this.operator;
        var sink = toSubscriber(observerOrNext, error, complete);
        if (operator) {
            operator.call(sink, this);
        }
        else {
            sink.add(this._subscribe(sink));
        }
        if (sink.syncErrorThrowable) {
            sink.syncErrorThrowable = false;
            if (sink.syncErrorThrown) {
                throw sink.syncErrorValue;
            }
        }
        return sink;
    };
    /**
     * @method forEach
     * @param {Function} next a handler for each value emitted by the observable
     * @param {PromiseConstructor} [PromiseCtor] a constructor function used to instantiate the Promise
     * @return {Promise} a promise that either resolves on observable completion or
     *  rejects with the handled error
     */
    Observable.prototype.forEach = function (next, PromiseCtor) {
        var _this = this;
        if (!PromiseCtor) {
            if (root.Rx && root.Rx.config && root.Rx.config.Promise) {
                PromiseCtor = root.Rx.config.Promise;
            }
            else if (root.Promise) {
                PromiseCtor = root.Promise;
            }
        }
        if (!PromiseCtor) {
            throw new Error('no Promise impl found');
        }
        return new PromiseCtor(function (resolve, reject) {
            var subscription = _this.subscribe(function (value) {
                if (subscription) {
                    // if there is a subscription, then we can surmise
                    // the next handling is asynchronous. Any errors thrown
                    // need to be rejected explicitly and unsubscribe must be
                    // called manually
                    try {
                        next(value);
                    }
                    catch (err) {
                        reject(err);
                        subscription.unsubscribe();
                    }
                }
                else {
                    // if there is NO subscription, then we're getting a nexted
                    // value synchronously during subscription. We can just call it.
                    // If it errors, Observable's `subscribe` will ensure the
                    // unsubscription logic is called, then synchronously rethrow the error.
                    // After that, Promise will trap the error and send it
                    // down the rejection path.
                    next(value);
                }
            }, reject, resolve);
        });
    };
    Observable.prototype._subscribe = function (subscriber) {
        return this.source.subscribe(subscriber);
    };
    /**
     * An interop point defined by the es7-observable spec https://github.com/zenparsing/es-observable
     * @method Symbol.observable
     * @return {Observable} this instance of the observable
     */
    Observable.prototype[$$observable] = function () {
        return this;
    };
    // HACK: Since TypeScript inherits static properties too, we have to
    // fight against TypeScript here so Subject can have a different static create signature
    /**
     * Creates a new cold Observable by calling the Observable constructor
     * @static true
     * @owner Observable
     * @method create
     * @param {Function} subscribe? the subscriber function to be passed to the Observable constructor
     * @return {Observable} a new cold observable
     */
    Observable.create = function (subscribe) {
        return new Observable(subscribe);
    };
    return Observable;
}());
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