34 lines
1.3 KiB
TypeScript
34 lines
1.3 KiB
TypeScript
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import { Observable } from '../Observable';
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/**
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* Applies an accumulator function over the source Observable where the
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* accumulator function itself returns an Observable, then each intermediate
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* Observable returned is merged into the output Observable.
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*
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* <span class="informal">It's like {@link scan}, but the Observables returned
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* by the accumulator are merged into the outer Observable.</span>
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*
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* @example <caption>Count the number of click events</caption>
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* const click$ = Rx.Observable.fromEvent(document, 'click');
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* const one$ = click$.mapTo(1);
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* const seed = 0;
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* const count$ = one$.mergeScan((acc, one) => Rx.Observable.of(acc + one), seed);
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* count$.subscribe(x => console.log(x));
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*
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* // Results:
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* 1
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* 2
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* 3
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* 4
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* // ...and so on for each click
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*
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* @param {function(acc: R, value: T): Observable<R>} accumulator
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* The accumulator function called on each source value.
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* @param seed The initial accumulation value.
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* @param {number} [concurrent=Number.POSITIVE_INFINITY] Maximum number of
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* input Observables being subscribed to concurrently.
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* @return {Observable<R>} An observable of the accumulated values.
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* @method mergeScan
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* @owner Observable
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*/
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export declare function mergeScan<T, R>(this: Observable<T>, accumulator: (acc: R, value: T) => Observable<R>, seed: R, concurrent?: number): Observable<R>;
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