| 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> |
| * |
| * ![](delay.png) |
| * |
| * 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>) { |
| } |
| } |