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import { async } from '../scheduler/async';
import { isDate } from '../util/isDate';
import { Operator } from '../Operator';
import { Subscriber } from '../Subscriber';
import { Subscription } from '../Subscription';
import { Notification } from '../Notification';
import { Observable } from '../Observable';
import { MonoTypeOperatorFunction, PartialObserver, SchedulerAction, SchedulerLike, TeardownLogic } from '../types';
/**
* Delays the emission of items from the source Observable by a given timeout or
* until a given Date.
*
* <span class="informal">Time shifts each item by some specified amount of
* milliseconds.</span>
*
* 
*
* If the delay argument is a Number, this operator time shifts the source
* Observable by that amount of time expressed in milliseconds. The relative
* time intervals between the values are preserved.
*
* If the delay argument is a Date, this operator time shifts the start of the
* Observable execution until the given date occurs.
*
* ## Examples
* Delay each click by one second
* ```ts
* import { fromEvent } from 'rxjs';
* import { delay } from 'rxjs/operators';
*
* const clicks = fromEvent(document, 'click');
* const delayedClicks = clicks.pipe(delay(1000)); // each click emitted after 1 second
* delayedClicks.subscribe(x => console.log(x));
* ```
*
* Delay all clicks until a future date happens
* ```ts
* import { fromEvent } from 'rxjs';
* import { delay } from 'rxjs/operators';
*
* const clicks = fromEvent(document, 'click');
* const date = new Date('March 15, 2050 12:00:00'); // in the future
* const delayedClicks = clicks.pipe(delay(date)); // click emitted only after that date
* delayedClicks.subscribe(x => console.log(x));
* ```
*
* @see {@link debounceTime}
* @see {@link delayWhen}
*
* @param {number|Date} delay The delay duration in milliseconds (a `number`) or
* a `Date` until which the emission of the source items is delayed.
* @param {SchedulerLike} [scheduler=async] The {@link SchedulerLike} to use for
* managing the timers that handle the time-shift for each item.
* @return {Observable} An Observable that delays the emissions of the source
* Observable by the specified timeout or Date.
* @method delay
* @owner Observable
*/
export function delay<T>(delay: number|Date,
scheduler: SchedulerLike = async): MonoTypeOperatorFunction<T> {
const absoluteDelay = isDate(delay);
const delayFor = absoluteDelay ? (+delay - scheduler.now()) : Math.abs(<number>delay);
return (source: Observable<T>) => source.lift(new DelayOperator(delayFor, scheduler));
}
class DelayOperator<T> implements Operator<T, T> {
constructor(private delay: number,
private scheduler: SchedulerLike) {
}
call(subscriber: Subscriber<T>, source: any): TeardownLogic {
return source.subscribe(new DelaySubscriber(subscriber, this.delay, this.scheduler));
}
}
interface DelayState<T> {
source: DelaySubscriber<T>;
destination: PartialObserver<T>;
scheduler: SchedulerLike;
}
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
class DelaySubscriber<T> extends Subscriber<T> {
private queue: Array<DelayMessage<T>> = [];
private active: boolean = false;
private errored: boolean = false;
private static dispatch<T>(this: SchedulerAction<DelayState<T>>, state: DelayState<T>): void {
const source = state.source;
const queue = source.queue;
const scheduler = state.scheduler;
const destination = state.destination;
while (queue.length > 0 && (queue[0].time - scheduler.now()) <= 0) {
queue.shift().notification.observe(destination);
}
if (queue.length > 0) {
const delay = Math.max(0, queue[0].time - scheduler.now());
this.schedule(state, delay);
} else {
this.unsubscribe();
source.active = false;
}
}
constructor(destination: Subscriber<T>,
private delay: number,
private scheduler: SchedulerLike) {
super(destination);
}
private _schedule(scheduler: SchedulerLike): void {
this.active = true;
const destination = this.destination as Subscription;
destination.add(scheduler.schedule<DelayState<T>>(DelaySubscriber.dispatch, this.delay, {
source: this, destination: this.destination, scheduler: scheduler
}));
}
private scheduleNotification(notification: Notification<T>): void {
if (this.errored === true) {
return;
}
const scheduler = this.scheduler;
const message = new DelayMessage(scheduler.now() + this.delay, notification);
this.queue.push(message);
if (this.active === false) {
this._schedule(scheduler);
}
}
protected _next(value: T) {
this.scheduleNotification(Notification.createNext(value));
}
protected _error(err: any) {
this.errored = true;
this.queue = [];
this.destination.error(err);
this.unsubscribe();
}
protected _complete() {
this.scheduleNotification(Notification.createComplete());
this.unsubscribe();
}
}
class DelayMessage<T> {
constructor(public readonly time: number,
public readonly notification: Notification<T>) {
}
}
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