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- import { Observable } from '../Observable';
- import { Subscriber } from '../Subscriber';
- import { ObservableInput, OperatorFunction, ObservedValueOf } from '../types';
- import { map } from './map';
- import { innerFrom } from '../observable/innerFrom';
- import { operate } from '../util/lift';
- import { createOperatorSubscriber } from './OperatorSubscriber';
- /* tslint:disable:max-line-length */
- export function exhaustMap<T, O extends ObservableInput<any>>(
- project: (value: T, index: number) => O
- ): OperatorFunction<T, ObservedValueOf<O>>;
- /** @deprecated The `resultSelector` parameter will be removed in v8. Use an inner `map` instead. Details: https://rxjs.dev/deprecations/resultSelector */
- export function exhaustMap<T, O extends ObservableInput<any>>(
- project: (value: T, index: number) => O,
- resultSelector: undefined
- ): OperatorFunction<T, ObservedValueOf<O>>;
- /** @deprecated The `resultSelector` parameter will be removed in v8. Use an inner `map` instead. Details: https://rxjs.dev/deprecations/resultSelector */
- export function exhaustMap<T, I, R>(
- project: (value: T, index: number) => ObservableInput<I>,
- resultSelector: (outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R
- ): OperatorFunction<T, R>;
- /* tslint:enable:max-line-length */
- /**
- * Projects each source value to an Observable which is merged in the output
- * Observable only if the previous projected Observable has completed.
- *
- * <span class="informal">Maps each value to an Observable, then flattens all of
- * these inner Observables using {@link exhaustAll}.</span>
- *
- * 
- *
- * Returns an Observable that emits items based on applying a function that you
- * supply to each item emitted by the source Observable, where that function
- * returns an (so-called "inner") Observable. When it projects a source value to
- * an Observable, the output Observable begins emitting the items emitted by
- * that projected Observable. However, `exhaustMap` ignores every new projected
- * Observable if the previous projected Observable has not yet completed. Once
- * that one completes, it will accept and flatten the next projected Observable
- * and repeat this process.
- *
- * ## Example
- *
- * Run a finite timer for each click, only if there is no currently active timer
- *
- * ```ts
- * import { fromEvent, exhaustMap, interval, take } from 'rxjs';
- *
- * const clicks = fromEvent(document, 'click');
- * const result = clicks.pipe(
- * exhaustMap(() => interval(1000).pipe(take(5)))
- * );
- * result.subscribe(x => console.log(x));
- * ```
- *
- * @see {@link concatMap}
- * @see {@link exhaust}
- * @see {@link mergeMap}
- * @see {@link switchMap}
- *
- * @param project A function that, when applied to an item emitted by the source
- * Observable, returns an Observable.
- * @return A function that returns an Observable containing projected
- * Observables of each item of the source, ignoring projected Observables that
- * start before their preceding Observable has completed.
- */
- export function exhaustMap<T, R, O extends ObservableInput<any>>(
- project: (value: T, index: number) => O,
- resultSelector?: (outerValue: T, innerValue: ObservedValueOf<O>, outerIndex: number, innerIndex: number) => R
- ): OperatorFunction<T, ObservedValueOf<O> | R> {
- if (resultSelector) {
- // DEPRECATED PATH
- return (source: Observable<T>) =>
- source.pipe(exhaustMap((a, i) => innerFrom(project(a, i)).pipe(map((b: any, ii: any) => resultSelector(a, b, i, ii)))));
- }
- return operate((source, subscriber) => {
- let index = 0;
- let innerSub: Subscriber<T> | null = null;
- let isComplete = false;
- source.subscribe(
- createOperatorSubscriber(
- subscriber,
- (outerValue) => {
- if (!innerSub) {
- innerSub = createOperatorSubscriber(subscriber, undefined, () => {
- innerSub = null;
- isComplete && subscriber.complete();
- });
- innerFrom(project(outerValue, index++)).subscribe(innerSub);
- }
- },
- () => {
- isComplete = true;
- !innerSub && subscriber.complete();
- }
- )
- );
- });
- }
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