[6a3a178] | 1 | import { mergeMap } from './mergeMap';
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| 2 | import { ObservableInput, OperatorFunction, ObservedValueOf } from '../types';
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| 3 |
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| 4 | /* tslint:disable:max-line-length */
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| 5 | export function concatMap<T, O extends ObservableInput<any>>(project: (value: T, index: number) => O): OperatorFunction<T, ObservedValueOf<O>>;
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| 6 | /** @deprecated resultSelector no longer supported, use inner map instead */
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| 7 | export function concatMap<T, O extends ObservableInput<any>>(project: (value: T, index: number) => O, resultSelector: undefined): OperatorFunction<T, ObservedValueOf<O>>;
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| 8 | /** @deprecated resultSelector no longer supported, use inner map instead */
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| 9 | 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>;
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| 10 | /* tslint:enable:max-line-length */
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| 11 |
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| 12 | /**
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| 13 | * Projects each source value to an Observable which is merged in the output
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| 14 | * Observable, in a serialized fashion waiting for each one to complete before
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| 15 | * merging the next.
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| 16 | *
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| 17 | * <span class="informal">Maps each value to an Observable, then flattens all of
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| 18 | * these inner Observables using {@link concatAll}.</span>
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| 19 | *
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| 20 | * ![](concatMap.png)
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| 21 | *
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| 22 | * Returns an Observable that emits items based on applying a function that you
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| 23 | * supply to each item emitted by the source Observable, where that function
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| 24 | * returns an (so-called "inner") Observable. Each new inner Observable is
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| 25 | * concatenated with the previous inner Observable.
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| 26 | *
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| 27 | * __Warning:__ if source values arrive endlessly and faster than their
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| 28 | * corresponding inner Observables can complete, it will result in memory issues
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| 29 | * as inner Observables amass in an unbounded buffer waiting for their turn to
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| 30 | * be subscribed to.
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| 31 | *
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| 32 | * Note: `concatMap` is equivalent to `mergeMap` with concurrency parameter set
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| 33 | * to `1`.
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| 34 | *
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| 35 | * ## Example
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| 36 | * For each click event, tick every second from 0 to 3, with no concurrency
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| 37 | *
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| 38 | * ```ts
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| 39 | * import { fromEvent, interval } from 'rxjs';
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| 40 | * import { concatMap, take } from 'rxjs/operators';
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| 41 | *
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| 42 | * const clicks = fromEvent(document, 'click');
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| 43 | * const result = clicks.pipe(
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| 44 | * concatMap(ev => interval(1000).pipe(take(4)))
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| 45 | * );
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| 46 | * result.subscribe(x => console.log(x));
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| 47 | *
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| 48 | * // Results in the following:
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| 49 | * // (results are not concurrent)
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| 50 | * // For every click on the "document" it will emit values 0 to 3 spaced
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| 51 | * // on a 1000ms interval
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| 52 | * // one click = 1000ms-> 0 -1000ms-> 1 -1000ms-> 2 -1000ms-> 3
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| 53 | * ```
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| 54 | *
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| 55 | * @see {@link concat}
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| 56 | * @see {@link concatAll}
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| 57 | * @see {@link concatMapTo}
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| 58 | * @see {@link exhaustMap}
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| 59 | * @see {@link mergeMap}
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| 60 | * @see {@link switchMap}
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| 61 | *
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| 62 | * @param {function(value: T, ?index: number): ObservableInput} project A function
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| 63 | * that, when applied to an item emitted by the source Observable, returns an
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| 64 | * Observable.
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| 65 | * @return {Observable} An Observable that emits the result of applying the
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| 66 | * projection function (and the optional deprecated `resultSelector`) to each item emitted
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| 67 | * by the source Observable and taking values from each projected inner
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| 68 | * Observable sequentially.
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| 69 | * @method concatMap
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| 70 | * @owner Observable
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| 71 | */
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| 72 | export function concatMap<T, R, O extends ObservableInput<any>>(
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| 73 | project: (value: T, index: number) => O,
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| 74 | resultSelector?: (outerValue: T, innerValue: ObservedValueOf<O>, outerIndex: number, innerIndex: number) => R
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| 75 | ): OperatorFunction<T, ObservedValueOf<O>|R> {
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| 76 | return mergeMap(project, resultSelector, 1);
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| 77 | }
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