import { mergeAll } from './mergeAll';
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import { OperatorFunction, ObservableInput, ObservedValueOf } from '../types';
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/**
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* Converts a higher-order Observable into a first-order Observable by
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* concatenating the inner Observables in order.
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*
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* <span class="informal">Flattens an Observable-of-Observables by putting one
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* inner Observable after the other.</span>
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*
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* 
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*
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* Joins every Observable emitted by the source (a higher-order Observable), in
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* a serial fashion. It subscribes to each inner Observable only after the
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* previous inner Observable has completed, and merges all of their values into
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* the returned observable.
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*
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* __Warning:__ If the source Observable emits Observables quickly and
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* endlessly, and the inner Observables it emits generally complete slower than
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* the source emits, you can run into memory issues as the incoming Observables
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* collect in an unbounded buffer.
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*
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* Note: `concatAll` is equivalent to `mergeAll` with concurrency parameter set
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* to `1`.
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*
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* ## Example
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*
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* For each click event, tick every second from 0 to 3, with no concurrency
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*
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* ```ts
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* import { fromEvent, map, interval, take, concatAll } from 'rxjs';
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*
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* const clicks = fromEvent(document, 'click');
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* const higherOrder = clicks.pipe(
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* map(() => interval(1000).pipe(take(4)))
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* );
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* const firstOrder = higherOrder.pipe(concatAll());
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* firstOrder.subscribe(x => console.log(x));
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*
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* // Results in the following:
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* // (results are not concurrent)
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* // For every click on the "document" it will emit values 0 to 3 spaced
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* // on a 1000ms interval
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* // one click = 1000ms-> 0 -1000ms-> 1 -1000ms-> 2 -1000ms-> 3
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* ```
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*
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* @see {@link combineLatestAll}
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* @see {@link concat}
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* @see {@link concatMap}
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* @see {@link concatMapTo}
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* @see {@link exhaustAll}
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* @see {@link mergeAll}
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* @see {@link switchAll}
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* @see {@link switchMap}
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* @see {@link zipAll}
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*
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* @return A function that returns an Observable emitting values from all the
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* inner Observables concatenated.
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*/
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export function concatAll<O extends ObservableInput<any>>(): OperatorFunction<O, ObservedValueOf<O>> {
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return mergeAll(1);
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}
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