| import { mergeMap } from './mergeMap'; |
| import { ObservableInput, OperatorFunction, ObservedValueOf } from '../types'; |
| |
| /* tslint:disable:max-line-length */ |
| export function concatMap<T, O extends ObservableInput<any>>(project: (value: T, index: number) => O): OperatorFunction<T, ObservedValueOf<O>>; |
| /** @deprecated resultSelector no longer supported, use inner map instead */ |
| export function concatMap<T, O extends ObservableInput<any>>(project: (value: T, index: number) => O, resultSelector: undefined): OperatorFunction<T, ObservedValueOf<O>>; |
| /** @deprecated resultSelector no longer supported, use inner map instead */ |
| 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> |
| * |
| * ![](concatMap.png) |
| * |
| * 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, interval } from 'rxjs'; |
| * import { concatMap, take } from 'rxjs/operators'; |
| * |
| * 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 {function(value: T, ?index: number): ObservableInput} project A function |
| * that, when applied to an item emitted by the source Observable, returns an |
| * Observable. |
| * @return {Observable} 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. |
| * @method concatMap |
| * @owner Observable |
| */ |
| 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 mergeMap(project, resultSelector, 1); |
| } |