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