| import { Operator } from '../Operator'; |
| import { Observable } from '../Observable'; |
| import { Subscriber } from '../Subscriber'; |
| |
| import { OuterSubscriber } from '../OuterSubscriber'; |
| import { InnerSubscriber } from '../InnerSubscriber'; |
| import { subscribeToResult } from '../util/subscribeToResult'; |
| |
| import { MonoTypeOperatorFunction, TeardownLogic } from '../types'; |
| |
| /** |
| * Emits the values emitted by the source Observable until a `notifier` |
| * Observable emits a value. |
| * |
| * <span class="informal">Lets values pass until a second Observable, |
| * `notifier`, emits a value. Then, it completes.</span> |
| * |
| * ![](takeUntil.png) |
| * |
| * `takeUntil` subscribes and begins mirroring the source Observable. It also |
| * monitors a second Observable, `notifier` that you provide. If the `notifier` |
| * emits a value, the output Observable stops mirroring the source Observable |
| * and completes. If the `notifier` doesn't emit any value and completes |
| * then `takeUntil` will pass all values. |
| * |
| * ## Example |
| * Tick every second until the first click happens |
| * ```ts |
| * import { fromEvent, interval } from 'rxjs'; |
| * import { takeUntil } from 'rxjs/operators'; |
| * |
| * const source = interval(1000); |
| * const clicks = fromEvent(document, 'click'); |
| * const result = source.pipe(takeUntil(clicks)); |
| * result.subscribe(x => console.log(x)); |
| * ``` |
| * |
| * @see {@link take} |
| * @see {@link takeLast} |
| * @see {@link takeWhile} |
| * @see {@link skip} |
| * |
| * @param {Observable} notifier The Observable whose first emitted value will |
| * cause the output Observable of `takeUntil` to stop emitting values from the |
| * source Observable. |
| * @return {Observable<T>} An Observable that emits the values from the source |
| * Observable until such time as `notifier` emits its first value. |
| * @method takeUntil |
| * @owner Observable |
| */ |
| export function takeUntil<T>(notifier: Observable<any>): MonoTypeOperatorFunction<T> { |
| return (source: Observable<T>) => source.lift(new TakeUntilOperator(notifier)); |
| } |
| |
| class TakeUntilOperator<T> implements Operator<T, T> { |
| constructor(private notifier: Observable<any>) { |
| } |
| |
| call(subscriber: Subscriber<T>, source: any): TeardownLogic { |
| const takeUntilSubscriber = new TakeUntilSubscriber(subscriber); |
| const notifierSubscription = subscribeToResult(takeUntilSubscriber, this.notifier); |
| if (notifierSubscription && !takeUntilSubscriber.seenValue) { |
| takeUntilSubscriber.add(notifierSubscription); |
| return source.subscribe(takeUntilSubscriber); |
| } |
| return takeUntilSubscriber; |
| } |
| } |
| |
| /** |
| * We need this JSDoc comment for affecting ESDoc. |
| * @ignore |
| * @extends {Ignored} |
| */ |
| class TakeUntilSubscriber<T, R> extends OuterSubscriber<T, R> { |
| seenValue = false; |
| |
| constructor(destination: Subscriber<any>, ) { |
| super(destination); |
| } |
| |
| notifyNext(outerValue: T, innerValue: R, |
| outerIndex: number, innerIndex: number, |
| innerSub: InnerSubscriber<T, R>): void { |
| this.seenValue = true; |
| this.complete(); |
| } |
| |
| notifyComplete(): void { |
| // noop |
| } |
| } |