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- import { Operator } from '../Operator';
- import { Observable } from '../Observable';
- import { Subscriber } from '../Subscriber';
- import { Subscription } from '../Subscription';
- import { OuterSubscriber } from '../OuterSubscriber';
- import { InnerSubscriber } from '../InnerSubscriber';
- import { subscribeToResult } from '../util/subscribeToResult';
- import { ObservableInput, OperatorFunction, ObservedValueOf } from '../types';
- import { map } from './map';
- import { from } from '../observable/from';
-
- /* tslint:disable:max-line-length */
- export function exhaustMap<T, O extends ObservableInput<any>>(project: (value: T, index: number) => O): OperatorFunction<T, ObservedValueOf<O>>;
- /** @deprecated resultSelector is no longer supported. Use inner map instead. */
- export function exhaustMap<T, O extends ObservableInput<any>>(project: (value: T, index: number) => O, resultSelector: undefined): OperatorFunction<T, ObservedValueOf<O>>;
- /** @deprecated resultSelector is no longer supported. Use inner map instead. */
- export function exhaustMap<T, I, R>(project: (value: T, index: number) => ObservableInput<I>, resultSelector: (outerValue: T, innerValue: I, 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 only if the previous projected Observable has completed.
- *
- * <span class="informal">Maps each value to an Observable, then flattens all of
- * these inner Observables using {@link exhaust}.</span>
- *
- * ![](exhaustMap.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. When it projects a source value to
- * an Observable, the output Observable begins emitting the items emitted by
- * that projected Observable. However, `exhaustMap` ignores every new projected
- * Observable if the previous projected Observable has not yet completed. Once
- * that one completes, it will accept and flatten the next projected Observable
- * and repeat this process.
- *
- * ## Example
- * Run a finite timer for each click, only if there is no currently active timer
- * ```ts
- * import { fromEvent, interval } from 'rxjs';
- * import { exhaustMap, take } from 'rxjs/operators';
- *
- * const clicks = fromEvent(document, 'click');
- * const result = clicks.pipe(
- * exhaustMap(ev => interval(1000).pipe(take(5)))
- * );
- * result.subscribe(x => console.log(x));
- * ```
- *
- * @see {@link concatMap}
- * @see {@link exhaust}
- * @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 containing projected Observables
- * of each item of the source, ignoring projected Observables that start before
- * their preceding Observable has completed.
- * @method exhaustMap
- * @owner Observable
- */
- export function exhaustMap<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> {
- if (resultSelector) {
- // DEPRECATED PATH
- return (source: Observable<T>) => source.pipe(
- exhaustMap((a, i) => from(project(a, i)).pipe(
- map((b: any, ii: any) => resultSelector(a, b, i, ii)),
- )),
- );
- }
- return (source: Observable<T>) =>
- source.lift(new ExhaustMapOperator(project));
- }
-
- class ExhaustMapOperator<T, R> implements Operator<T, R> {
- constructor(private project: (value: T, index: number) => ObservableInput<R>) {
- }
-
- call(subscriber: Subscriber<R>, source: any): any {
- return source.subscribe(new ExhaustMapSubscriber(subscriber, this.project));
- }
- }
-
- /**
- * We need this JSDoc comment for affecting ESDoc.
- * @ignore
- * @extends {Ignored}
- */
- class ExhaustMapSubscriber<T, R> extends OuterSubscriber<T, R> {
- private hasSubscription = false;
- private hasCompleted = false;
- private index = 0;
-
- constructor(destination: Subscriber<R>,
- private project: (value: T, index: number) => ObservableInput<R>) {
- super(destination);
- }
-
- protected _next(value: T): void {
- if (!this.hasSubscription) {
- this.tryNext(value);
- }
- }
-
- private tryNext(value: T): void {
- let result: ObservableInput<R>;
- const index = this.index++;
- try {
- result = this.project(value, index);
- } catch (err) {
- this.destination.error(err);
- return;
- }
- this.hasSubscription = true;
- this._innerSub(result, value, index);
- }
-
- private _innerSub(result: ObservableInput<R>, value: T, index: number): void {
- const innerSubscriber = new InnerSubscriber(this, undefined, undefined);
- const destination = this.destination as Subscription;
- destination.add(innerSubscriber);
- subscribeToResult<T, R>(this, result, value, index, innerSubscriber);
- }
-
- protected _complete(): void {
- this.hasCompleted = true;
- if (!this.hasSubscription) {
- this.destination.complete();
- }
- this.unsubscribe();
- }
-
- notifyNext(outerValue: T, innerValue: R,
- outerIndex: number, innerIndex: number,
- innerSub: InnerSubscriber<T, R>): void {
- this.destination.next(innerValue);
- }
-
- notifyError(err: any): void {
- this.destination.error(err);
- }
-
- notifyComplete(innerSub: Subscription): void {
- const destination = this.destination as Subscription;
- destination.remove(innerSub);
-
- this.hasSubscription = false;
- if (this.hasCompleted) {
- this.destination.complete();
- }
- }
- }
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