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import {OperatorFunction, ObservableInput} from '../types';
import { switchMap } from './switchMap';
import { identity } from '../util/identity';
export function switchAll<T>(): OperatorFunction<ObservableInput<T>, T>;
export function switchAll<R>(): OperatorFunction<any, R>;
/**
* Converts a higher-order Observable into a first-order Observable
* producing values only from the most recent observable sequence
*
* <span class="informal">Flattens an Observable-of-Observables.</span>
*
* 
*
* `switchAll` subscribes to a source that is an observable of observables, also known as a
* "higher-order observable" (or `Observable<Observable<T>>`). It subscribes to the most recently
* provided "inner observable" emitted by the source, unsubscribing from any previously subscribed
* to inner observable, such that only the most recent inner observable may be subscribed to at
* any point in time. The resulting observable returned by `switchAll` will only complete if the
* source observable completes, *and* any currently subscribed to inner observable also has completed,
* if there are any.
*
* ## Examples
* Spawn a new interval observable for each click event, but for every new
* click, cancel the previous interval and subscribe to the new one.
*
* ```ts
* import { fromEvent, interval } from 'rxjs';
* import { switchAll, map } from 'rxjs/operators';
*
* const clicks = fromEvent(document, 'click').pipe(tap(() => console.log('click')));
* const source = clicks.pipe(map((ev) => interval(1000)));
*
* source.pipe(
* switchAll()
* ).subscribe(x => console.log(x));
*
/* Output
* click
* 1
* 2
* 3
* 4
* ...
* click
* 1
* 2
* 3
* ...
* click
* ...
* ```
*
* @see {@link combineAll}
* @see {@link concatAll}
* @see {@link exhaust}
* @see {@link switchMap}
* @see {@link switchMapTo}
* @see {@link mergeAll}
*/
export function switchAll<T>(): OperatorFunction<ObservableInput<T>, T> {
return switchMap(identity);
}
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