| 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(); |
| } |
| } |
| } |