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- import { mergeMap } from './mergeMap';
- import { ObservableInput, OperatorFunction, ObservedValueOf } from '../types';
- import { isFunction } from '../util/isFunction';
- /* tslint:disable:max-line-length */
- export function concatMap<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 concatMap<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 concatMap<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, R>;
- /* tslint:enable:max-line-length */
- /**
- * Projects each source value to an Observable which is merged in the output
- * Observable, in a serialized fashion waiting for each one to complete before
- * merging the next.
- *
- * <span class="informal">Maps each value to an Observable, then flattens all of
- * these inner Observables using {@link concatAll}.</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. Each new inner Observable is
- * concatenated with the previous inner Observable.
- *
- * __Warning:__ if source values arrive endlessly and faster than their
- * corresponding inner Observables can complete, it will result in memory issues
- * as inner Observables amass in an unbounded buffer waiting for their turn to
- * be subscribed to.
- *
- * Note: `concatMap` is equivalent to `mergeMap` with concurrency parameter set
- * to `1`.
- *
- * ## Example
- *
- * For each click event, tick every second from 0 to 3, with no concurrency
- *
- * ```ts
- * import { fromEvent, concatMap, interval, take } from 'rxjs';
- *
- * const clicks = fromEvent(document, 'click');
- * const result = clicks.pipe(
- * concatMap(ev => interval(1000).pipe(take(4)))
- * );
- * result.subscribe(x => console.log(x));
- *
- * // Results in the following:
- * // (results are not concurrent)
- * // For every click on the "document" it will emit values 0 to 3 spaced
- * // on a 1000ms interval
- * // one click = 1000ms-> 0 -1000ms-> 1 -1000ms-> 2 -1000ms-> 3
- * ```
- *
- * @see {@link concat}
- * @see {@link concatAll}
- * @see {@link concatMapTo}
- * @see {@link exhaustMap}
- * @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 that emits the result of
- * applying the projection function (and the optional deprecated
- * `resultSelector`) to each item emitted by the source Observable and taking
- * values from each projected inner Observable sequentially.
- */
- export function concatMap<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> {
- return isFunction(resultSelector) ? mergeMap(project, resultSelector, 1) : mergeMap(project, 1);
- }
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