124 lines
4.3 KiB
JavaScript
124 lines
4.3 KiB
JavaScript
import { async } from '../scheduler/async';
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import { isDate } from '../util/isDate';
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import { Subscriber } from '../Subscriber';
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import { Notification } from '../Notification';
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/**
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* Delays the emission of items from the source Observable by a given timeout or
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* until a given Date.
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*
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* <span class="informal">Time shifts each item by some specified amount of
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* milliseconds.</span>
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*
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* <img src="./img/delay.png" width="100%">
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*
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* If the delay argument is a Number, this operator time shifts the source
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* Observable by that amount of time expressed in milliseconds. The relative
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* time intervals between the values are preserved.
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*
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* If the delay argument is a Date, this operator time shifts the start of the
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* Observable execution until the given date occurs.
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*
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* @example <caption>Delay each click by one second</caption>
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* var clicks = Rx.Observable.fromEvent(document, 'click');
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* var delayedClicks = clicks.delay(1000); // each click emitted after 1 second
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* delayedClicks.subscribe(x => console.log(x));
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*
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* @example <caption>Delay all clicks until a future date happens</caption>
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* var clicks = Rx.Observable.fromEvent(document, 'click');
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* var date = new Date('March 15, 2050 12:00:00'); // in the future
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* var delayedClicks = clicks.delay(date); // click emitted only after that date
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* delayedClicks.subscribe(x => console.log(x));
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*
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* @see {@link debounceTime}
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* @see {@link delayWhen}
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*
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* @param {number|Date} delay The delay duration in milliseconds (a `number`) or
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* a `Date` until which the emission of the source items is delayed.
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* @param {Scheduler} [scheduler=async] The IScheduler to use for
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* managing the timers that handle the time-shift for each item.
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* @return {Observable} An Observable that delays the emissions of the source
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* Observable by the specified timeout or Date.
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* @method delay
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* @owner Observable
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*/
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export function delay(delay, scheduler = async) {
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const absoluteDelay = isDate(delay);
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const delayFor = absoluteDelay ? (+delay - scheduler.now()) : Math.abs(delay);
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return (source) => source.lift(new DelayOperator(delayFor, scheduler));
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}
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class DelayOperator {
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constructor(delay, scheduler) {
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this.delay = delay;
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this.scheduler = scheduler;
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}
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call(subscriber, source) {
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return source.subscribe(new DelaySubscriber(subscriber, this.delay, this.scheduler));
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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 DelaySubscriber extends Subscriber {
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constructor(destination, delay, scheduler) {
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super(destination);
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this.delay = delay;
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this.scheduler = scheduler;
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this.queue = [];
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this.active = false;
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this.errored = false;
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}
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static dispatch(state) {
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const source = state.source;
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const queue = source.queue;
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const scheduler = state.scheduler;
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const destination = state.destination;
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while (queue.length > 0 && (queue[0].time - scheduler.now()) <= 0) {
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queue.shift().notification.observe(destination);
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}
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if (queue.length > 0) {
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const delay = Math.max(0, queue[0].time - scheduler.now());
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this.schedule(state, delay);
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}
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else {
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this.unsubscribe();
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source.active = false;
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}
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}
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_schedule(scheduler) {
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this.active = true;
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this.add(scheduler.schedule(DelaySubscriber.dispatch, this.delay, {
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source: this, destination: this.destination, scheduler: scheduler
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}));
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}
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scheduleNotification(notification) {
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if (this.errored === true) {
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return;
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}
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const scheduler = this.scheduler;
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const message = new DelayMessage(scheduler.now() + this.delay, notification);
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this.queue.push(message);
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if (this.active === false) {
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this._schedule(scheduler);
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}
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}
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_next(value) {
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this.scheduleNotification(Notification.createNext(value));
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}
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_error(err) {
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this.errored = true;
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this.queue = [];
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this.destination.error(err);
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}
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_complete() {
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this.scheduleNotification(Notification.createComplete());
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}
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}
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class DelayMessage {
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constructor(time, notification) {
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this.time = time;
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this.notification = notification;
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}
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}
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//# sourceMappingURL=delay.js.map
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