exhaust.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');
/**
* Converts a higher-order Observable into a first-order Observable by dropping
* inner Observables while the previous inner Observable has not yet completed.
*
* <span class="informal">Flattens an Observable-of-Observables by dropping the
* next inner Observables while the current inner is still executing.</span>
*
* <img src="./img/exhaust.png" width="100%">
*
* `exhaust` subscribes to an Observable that emits Observables, also known as a
* higher-order Observable. Each time it observes one of these emitted inner
* Observables, the output Observable begins emitting the items emitted by that
* inner Observable. So far, it behaves like {@link mergeAll}. However,
* `exhaust` ignores every new inner Observable if the previous Observable has
* not yet completed. Once that one completes, it will accept and flatten the
* next inner Observable and repeat this process.
*
* @example <caption>Run a finite timer for each click, only if there is no currently active timer</caption>
* var clicks = Rx.Observable.fromEvent(document, 'click');
* var higherOrder = clicks.map((ev) => Rx.Observable.interval(1000));
* var result = higherOrder.exhaust();
* result.subscribe(x => console.log(x));
*
* @see {@link combineAll}
* @see {@link concatAll}
* @see {@link switch}
* @see {@link mergeAll}
* @see {@link exhaustMap}
* @see {@link zipAll}
*
* @return {Observable} Returns an Observable that takes a source of Observables
* and propagates the first observable exclusively until it completes before
* subscribing to the next.
* @method exhaust
* @owner Observable
*/
function exhaust() {
return this.lift(new SwitchFirstOperator());
}
exports.exhaust = exhaust;
var SwitchFirstOperator = (function () {
function SwitchFirstOperator() {
}
SwitchFirstOperator.prototype.call = function (subscriber, source) {
return source.subscribe(new SwitchFirstSubscriber(subscriber));
};
return SwitchFirstOperator;
}());
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
var SwitchFirstSubscriber = (function (_super) {
__extends(SwitchFirstSubscriber, _super);
function SwitchFirstSubscriber(destination) {
_super.call(this, destination);
this.hasCompleted = false;
this.hasSubscription = false;
}
SwitchFirstSubscriber.prototype._next = function (value) {
if (!this.hasSubscription) {
this.hasSubscription = true;
this.add(subscribeToResult_1.subscribeToResult(this, value));
}
};
SwitchFirstSubscriber.prototype._complete = function () {
this.hasCompleted = true;
if (!this.hasSubscription) {
this.destination.complete();
}
};
SwitchFirstSubscriber.prototype.notifyComplete = function (innerSub) {
this.remove(innerSub);
this.hasSubscription = false;
if (this.hasCompleted) {
this.destination.complete();
}
};
return SwitchFirstSubscriber;
}(OuterSubscriber_1.OuterSubscriber));
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