178 lines
6.3 KiB
JavaScript
178 lines
6.3 KiB
JavaScript
import { Subscriber } from '../Subscriber';
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import { Observable } from '../Observable';
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import { OuterSubscriber } from '../OuterSubscriber';
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import { subscribeToResult } from '../util/subscribeToResult';
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/**
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* Delays the emission of items from the source Observable by a given time span
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* determined by the emissions of another Observable.
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*
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* <span class="informal">It's like {@link delay}, but the time span of the
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* delay duration is determined by a second Observable.</span>
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*
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* <img src="./img/delayWhen.png" width="100%">
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*
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* `delayWhen` time shifts each emitted value from the source Observable by a
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* time span determined by another Observable. When the source emits a value,
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* the `delayDurationSelector` function is called with the source value as
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* argument, and should return an Observable, called the "duration" Observable.
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* The source value is emitted on the output Observable only when the duration
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* Observable emits a value or completes.
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*
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* Optionally, `delayWhen` takes a second argument, `subscriptionDelay`, which
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* is an Observable. When `subscriptionDelay` emits its first value or
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* completes, the source Observable is subscribed to and starts behaving like
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* described in the previous paragraph. If `subscriptionDelay` is not provided,
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* `delayWhen` will subscribe to the source Observable as soon as the output
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* Observable is subscribed.
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*
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* @example <caption>Delay each click by a random amount of time, between 0 and 5 seconds</caption>
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* var clicks = Rx.Observable.fromEvent(document, 'click');
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* var delayedClicks = clicks.delayWhen(event =>
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* Rx.Observable.interval(Math.random() * 5000)
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* );
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* delayedClicks.subscribe(x => console.log(x));
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*
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* @see {@link debounce}
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* @see {@link delay}
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*
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* @param {function(value: T): Observable} delayDurationSelector A function that
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* returns an Observable for each value emitted by the source Observable, which
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* is then used to delay the emission of that item on the output Observable
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* until the Observable returned from this function emits a value.
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* @param {Observable} subscriptionDelay An Observable that triggers the
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* subscription to the source Observable once it emits any value.
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* @return {Observable} An Observable that delays the emissions of the source
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* Observable by an amount of time specified by the Observable returned by
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* `delayDurationSelector`.
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* @method delayWhen
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* @owner Observable
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*/
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export function delayWhen(delayDurationSelector, subscriptionDelay) {
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if (subscriptionDelay) {
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return (source) => new SubscriptionDelayObservable(source, subscriptionDelay)
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.lift(new DelayWhenOperator(delayDurationSelector));
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}
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return (source) => source.lift(new DelayWhenOperator(delayDurationSelector));
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}
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class DelayWhenOperator {
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constructor(delayDurationSelector) {
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this.delayDurationSelector = delayDurationSelector;
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}
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call(subscriber, source) {
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return source.subscribe(new DelayWhenSubscriber(subscriber, this.delayDurationSelector));
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}
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}
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/**
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* We need this JSDoc comment for affecting ESDoc.
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* @ignore
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* @extends {Ignored}
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*/
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class DelayWhenSubscriber extends OuterSubscriber {
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constructor(destination, delayDurationSelector) {
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super(destination);
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this.delayDurationSelector = delayDurationSelector;
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this.completed = false;
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this.delayNotifierSubscriptions = [];
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this.values = [];
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}
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notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) {
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this.destination.next(outerValue);
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this.removeSubscription(innerSub);
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this.tryComplete();
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}
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notifyError(error, innerSub) {
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this._error(error);
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}
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notifyComplete(innerSub) {
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const value = this.removeSubscription(innerSub);
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if (value) {
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this.destination.next(value);
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}
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this.tryComplete();
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}
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_next(value) {
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try {
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const delayNotifier = this.delayDurationSelector(value);
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if (delayNotifier) {
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this.tryDelay(delayNotifier, value);
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}
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}
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catch (err) {
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this.destination.error(err);
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}
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}
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_complete() {
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this.completed = true;
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this.tryComplete();
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}
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removeSubscription(subscription) {
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subscription.unsubscribe();
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const subscriptionIdx = this.delayNotifierSubscriptions.indexOf(subscription);
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let value = null;
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if (subscriptionIdx !== -1) {
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value = this.values[subscriptionIdx];
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this.delayNotifierSubscriptions.splice(subscriptionIdx, 1);
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this.values.splice(subscriptionIdx, 1);
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}
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return value;
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}
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tryDelay(delayNotifier, value) {
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const notifierSubscription = subscribeToResult(this, delayNotifier, value);
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if (notifierSubscription && !notifierSubscription.closed) {
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this.add(notifierSubscription);
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this.delayNotifierSubscriptions.push(notifierSubscription);
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}
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this.values.push(value);
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}
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tryComplete() {
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if (this.completed && this.delayNotifierSubscriptions.length === 0) {
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this.destination.complete();
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}
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}
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}
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/**
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* We need this JSDoc comment for affecting ESDoc.
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* @ignore
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* @extends {Ignored}
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*/
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class SubscriptionDelayObservable extends Observable {
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constructor(/** @deprecated internal use only */ source, subscriptionDelay) {
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super();
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this.source = source;
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this.subscriptionDelay = subscriptionDelay;
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}
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/** @deprecated internal use only */ _subscribe(subscriber) {
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this.subscriptionDelay.subscribe(new SubscriptionDelaySubscriber(subscriber, this.source));
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}
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}
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/**
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* We need this JSDoc comment for affecting ESDoc.
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* @ignore
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* @extends {Ignored}
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*/
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class SubscriptionDelaySubscriber extends Subscriber {
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constructor(parent, source) {
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super();
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this.parent = parent;
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this.source = source;
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this.sourceSubscribed = false;
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}
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_next(unused) {
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this.subscribeToSource();
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}
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_error(err) {
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this.unsubscribe();
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this.parent.error(err);
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}
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_complete() {
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this.subscribeToSource();
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}
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subscribeToSource() {
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if (!this.sourceSubscribed) {
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this.sourceSubscribed = true;
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this.unsubscribe();
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this.source.subscribe(this.parent);
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}
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}
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}
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//# sourceMappingURL=delayWhen.js.map
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