work.suroh.tk/node_modules/rxjs/operators/switchMapTo.js

"use strict";
var __extends = (this && this.__extends) || function (d, b) {
    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
    function __() { this.constructor = d; }
    d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
var OuterSubscriber_1 = require('../OuterSubscriber');
var subscribeToResult_1 = require('../util/subscribeToResult');
/* tslint:enable:max-line-length */
/**
 * Projects each source value to the same Observable which is flattened multiple
 * times with {@link switch} in the output Observable.
 *
 * <span class="informal">It's like {@link switchMap}, but maps each value
 * always to the same inner Observable.</span>
 *
 * <img src="./img/switchMapTo.png" width="100%">
 *
 * Maps each source value to the given Observable `innerObservable` regardless
 * of the source value, and then flattens those resulting Observables into one
 * single Observable, which is the output Observable. The output Observables
 * emits values only from the most recently emitted instance of
 * `innerObservable`.
 *
 * @example <caption>Rerun an interval Observable on every click event</caption>
 * var clicks = Rx.Observable.fromEvent(document, 'click');
 * var result = clicks.switchMapTo(Rx.Observable.interval(1000));
 * result.subscribe(x => console.log(x));
 *
 * @see {@link concatMapTo}
 * @see {@link switch}
 * @see {@link switchMap}
 * @see {@link mergeMapTo}
 *
 * @param {ObservableInput} innerObservable An Observable to replace each value from
 * the source Observable.
 * @param {function(outerValue: T, innerValue: I, outerIndex: number, innerIndex: number): any} [resultSelector]
 * A function to produce the value on the output Observable based on the values
 * and the indices of the source (outer) emission and the inner Observable
 * emission. The arguments passed to this function are:
 * - `outerValue`: the value that came from the source
 * - `innerValue`: the value that came from the projected Observable
 * - `outerIndex`: the "index" of the value that came from the source
 * - `innerIndex`: the "index" of the value from the projected Observable
 * @return {Observable} An Observable that emits items from the given
 * `innerObservable` (and optionally transformed through `resultSelector`) every
 * time a value is emitted on the source Observable, and taking only the values
 * from the most recently projected inner Observable.
 * @method switchMapTo
 * @owner Observable
 */
function switchMapTo(innerObservable, resultSelector) {
    return function (source) { return source.lift(new SwitchMapToOperator(innerObservable, resultSelector)); };
}
exports.switchMapTo = switchMapTo;
var SwitchMapToOperator = (function () {
    function SwitchMapToOperator(observable, resultSelector) {
        this.observable = observable;
        this.resultSelector = resultSelector;
    }
    SwitchMapToOperator.prototype.call = function (subscriber, source) {
        return source.subscribe(new SwitchMapToSubscriber(subscriber, this.observable, this.resultSelector));
    };
    return SwitchMapToOperator;
}());
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @ignore
 * @extends {Ignored}
 */
var SwitchMapToSubscriber = (function (_super) {
    __extends(SwitchMapToSubscriber, _super);
    function SwitchMapToSubscriber(destination, inner, resultSelector) {
        _super.call(this, destination);
        this.inner = inner;
        this.resultSelector = resultSelector;
        this.index = 0;
    }
    SwitchMapToSubscriber.prototype._next = function (value) {
        var innerSubscription = this.innerSubscription;
        if (innerSubscription) {
            innerSubscription.unsubscribe();
        }
        this.add(this.innerSubscription = subscribeToResult_1.subscribeToResult(this, this.inner, value, this.index++));
    };
    SwitchMapToSubscriber.prototype._complete = function () {
        var innerSubscription = this.innerSubscription;
        if (!innerSubscription || innerSubscription.closed) {
            _super.prototype._complete.call(this);
        }
    };
    /** @deprecated internal use only */ SwitchMapToSubscriber.prototype._unsubscribe = function () {
        this.innerSubscription = null;
    };
    SwitchMapToSubscriber.prototype.notifyComplete = function (innerSub) {
        this.remove(innerSub);
        this.innerSubscription = null;
        if (this.isStopped) {
            _super.prototype._complete.call(this);
        }
    };
    SwitchMapToSubscriber.prototype.notifyNext = function (outerValue, innerValue, outerIndex, innerIndex, innerSub) {
        var _a = this, resultSelector = _a.resultSelector, destination = _a.destination;
        if (resultSelector) {
            this.tryResultSelector(outerValue, innerValue, outerIndex, innerIndex);
        }
        else {
            destination.next(innerValue);
        }
    };
    SwitchMapToSubscriber.prototype.tryResultSelector = function (outerValue, innerValue, outerIndex, innerIndex) {
        var _a = this, resultSelector = _a.resultSelector, destination = _a.destination;
        var result;
        try {
            result = resultSelector(outerValue, innerValue, outerIndex, innerIndex);
        }
        catch (err) {
            destination.error(err);
            return;
        }
        destination.next(result);
    };
    return SwitchMapToSubscriber;
}(OuterSubscriber_1.OuterSubscriber));
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