source: trip-planner-front/node_modules/rxjs/src/internal/operators/skipUntil.ts

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1import { Operator } from '../Operator';
2import { Subscriber } from '../Subscriber';
3import { Observable } from '../Observable';
4import { MonoTypeOperatorFunction, TeardownLogic, ObservableInput } from '../types';
5import { Subscription } from '../Subscription';
6import { SimpleOuterSubscriber, SimpleInnerSubscriber, innerSubscribe } from '../innerSubscribe';
7
8/**
9 * Returns an Observable that skips items emitted by the source Observable until a second Observable emits an item.
10 *
11 * The `skipUntil` operator causes the observable stream to skip the emission of values ​​until the passed in observable emits the first value.
12 * This can be particularly useful in combination with user interactions, responses of http requests or waiting for specific times to pass by.
13 *
14 * ![](skipUntil.png)
15 *
16 * Internally the `skipUntil` operator subscribes to the passed in observable (in the following called *notifier*) in order to recognize the emission
17 * of its first value. When this happens, the operator unsubscribes from the *notifier* and starts emitting the values of the *source*
18 * observable. It will never let the *source* observable emit any values if the *notifier* completes or throws an error without emitting
19 * a value before.
20 *
21 * ## Example
22 *
23 * In the following example, all emitted values ​​of the interval observable are skipped until the user clicks anywhere within the page.
24 *
25 * ```ts
26 * import { interval, fromEvent } from 'rxjs';
27 * import { skipUntil } from 'rxjs/operators';
28 *
29 * const intervalObservable = interval(1000);
30 * const click = fromEvent(document, 'click');
31 *
32 * const emitAfterClick = intervalObservable.pipe(
33 * skipUntil(click)
34 * );
35 * // clicked at 4.6s. output: 5...6...7...8........ or
36 * // clicked at 7.3s. output: 8...9...10..11.......
37 * const subscribe = emitAfterClick.subscribe(value => console.log(value));
38 * ```
39 *
40 * @param {Observable} notifier - The second Observable that has to emit an item before the source Observable's elements begin to
41 * be mirrored by the resulting Observable.
42 * @return {Observable<T>} An Observable that skips items from the source Observable until the second Observable emits
43 * an item, then emits the remaining items.
44 * @method skipUntil
45 * @owner Observable
46 */
47export function skipUntil<T>(notifier: Observable<any>): MonoTypeOperatorFunction<T> {
48 return (source: Observable<T>) => source.lift(new SkipUntilOperator(notifier));
49}
50
51class SkipUntilOperator<T> implements Operator<T, T> {
52 constructor(private notifier: Observable<any>) {
53 }
54
55 call(destination: Subscriber<T>, source: any): TeardownLogic {
56 return source.subscribe(new SkipUntilSubscriber(destination, this.notifier));
57 }
58}
59
60/**
61 * We need this JSDoc comment for affecting ESDoc.
62 * @ignore
63 * @extends {Ignored}
64 */
65class SkipUntilSubscriber<T, R> extends SimpleOuterSubscriber<T, R> {
66
67 private hasValue: boolean = false;
68 private innerSubscription?: Subscription;
69
70 constructor(destination: Subscriber<R>, notifier: ObservableInput<any>) {
71 super(destination);
72 const innerSubscriber = new SimpleInnerSubscriber(this);
73 this.add(innerSubscriber);
74 this.innerSubscription = innerSubscriber;
75 const innerSubscription = innerSubscribe(notifier, innerSubscriber);
76 // The returned subscription will usually be the subscriber that was
77 // passed. However, interop subscribers will be wrapped and for
78 // unsubscriptions to chain correctly, the wrapper needs to be added, too.
79 if (innerSubscription !== innerSubscriber) {
80 this.add(innerSubscription);
81 this.innerSubscription = innerSubscription;
82 }
83 }
84
85 protected _next(value: T) {
86 if (this.hasValue) {
87 super._next(value);
88 }
89 }
90
91 notifyNext(): void {
92 this.hasValue = true;
93 if (this.innerSubscription) {
94 this.innerSubscription.unsubscribe();
95 }
96 }
97
98 notifyComplete() {
99 /* do nothing */
100 }
101}
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