switchMapTo.js
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"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:disable: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 {Observable} 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` every time a value is emitted on the source 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 this.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);
}
};
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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