| import { concatMap } from './concatMap'; |
| import { ObservableInput, OperatorFunction, ObservedValueOf } from '../types'; |
| |
| /* tslint:disable:max-line-length */ |
| export function concatMapTo<T, O extends ObservableInput<any>>(observable: O): OperatorFunction<T, ObservedValueOf<O>>; |
| /** @deprecated */ |
| export function concatMapTo<T, O extends ObservableInput<any>>(observable: O, resultSelector: undefined): OperatorFunction<T, ObservedValueOf<O>>; |
| /** @deprecated */ |
| export function concatMapTo<T, R, O extends ObservableInput<any>>(observable: 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 the same Observable which is merged multiple |
| * times in a serialized fashion on the output Observable. |
| * |
| * <span class="informal">It's like {@link concatMap}, but maps each value |
| * always to the same inner Observable.</span> |
| * |
| * ![](concatMapTo.png) |
| * |
| * Maps each source value to the given Observable `innerObservable` regardless |
| * of the source value, and then flattens those resulting Observables into one |
| * single Observable, which is the output Observable. Each new `innerObservable` |
| * instance emitted on the output Observable is concatenated with the previous |
| * `innerObservable` instance. |
| * |
| * __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: `concatMapTo` is equivalent to `mergeMapTo` 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 { concatMapTo, take } from 'rxjs/operators'; |
| * |
| * const clicks = fromEvent(document, 'click'); |
| * const result = clicks.pipe( |
| * concatMapTo(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 concatMap} |
| * @see {@link mergeMapTo} |
| * @see {@link switchMapTo} |
| * |
| * @param {ObservableInput} innerObservable An Observable to replace each value from |
| * the source Observable. |
| * @return {Observable} An observable of values merged together by joining the |
| * passed observable with itself, one after the other, for each value emitted |
| * from the source. |
| * @method concatMapTo |
| * @owner Observable |
| */ |
| export function concatMapTo<T, R, O extends ObservableInput<any>>( |
| innerObservable: O, |
| resultSelector?: (outerValue: T, innerValue: ObservedValueOf<O>, outerIndex: number, innerIndex: number) => R |
| ): OperatorFunction<T, ObservedValueOf<O>|R> { |
| return concatMap(() => innerObservable, resultSelector); |
| } |