| import { Observable } from '../Observable'; |
| import { Operator } from '../Operator'; |
| import { Subscriber } from '../Subscriber'; |
| import { Subscription } from '../Subscription'; |
| import { subscribeToResult } from '../util/subscribeToResult'; |
| import { OuterSubscriber } from '../OuterSubscriber'; |
| import { InnerSubscriber } from '../InnerSubscriber'; |
| import { ObservableInput, OperatorFunction, ObservedValueOf } from '../types'; |
| import { map } from './map'; |
| import { from } from '../observable/from'; |
| |
| /* tslint:disable:max-line-length */ |
| export function mergeMap<T, O extends ObservableInput<any>>(project: (value: T, index: number) => O, concurrent?: number): OperatorFunction<T, ObservedValueOf<O>>; |
| /** @deprecated resultSelector no longer supported, use inner map instead */ |
| export function mergeMap<T, O extends ObservableInput<any>>(project: (value: T, index: number) => O, resultSelector: undefined, concurrent?: number): OperatorFunction<T, ObservedValueOf<O>>; |
| /** @deprecated resultSelector no longer supported, use inner map instead */ |
| export function mergeMap<T, R, O extends ObservableInput<any>>(project: (value: T, index: number) => O, resultSelector: (outerValue: T, innerValue: ObservedValueOf<O>, outerIndex: number, innerIndex: number) => R, concurrent?: number): OperatorFunction<T, R>; |
| /* tslint:enable:max-line-length */ |
| |
| /** |
| * Projects each source value to an Observable which is merged in the output |
| * Observable. |
| * |
| * <span class="informal">Maps each value to an Observable, then flattens all of |
| * these inner Observables using {@link mergeAll}.</span> |
| * |
| * ![](mergeMap.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 Observable, and then merging those resulting Observables and |
| * emitting the results of this merger. |
| * |
| * ## Example |
| * Map and flatten each letter to an Observable ticking every 1 second |
| * ```ts |
| * import { of, interval } from 'rxjs'; |
| * import { mergeMap, map } from 'rxjs/operators'; |
| * |
| * const letters = of('a', 'b', 'c'); |
| * const result = letters.pipe( |
| * mergeMap(x => interval(1000).pipe(map(i => x+i))), |
| * ); |
| * result.subscribe(x => console.log(x)); |
| * |
| * // Results in the following: |
| * // a0 |
| * // b0 |
| * // c0 |
| * // a1 |
| * // b1 |
| * // c1 |
| * // continues to list a,b,c with respective ascending integers |
| * ``` |
| * |
| * @see {@link concatMap} |
| * @see {@link exhaustMap} |
| * @see {@link merge} |
| * @see {@link mergeAll} |
| * @see {@link mergeMapTo} |
| * @see {@link mergeScan} |
| * @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. |
| * @param {number} [concurrent=Number.POSITIVE_INFINITY] Maximum number of input |
| * Observables being subscribed to concurrently. |
| * @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 merging the results of the Observables |
| * obtained from this transformation. |
| * @method mergeMap |
| * @owner Observable |
| */ |
| export function mergeMap<T, R, O extends ObservableInput<any>>( |
| project: (value: T, index: number) => O, |
| resultSelector?: ((outerValue: T, innerValue: ObservedValueOf<O>, outerIndex: number, innerIndex: number) => R) | number, |
| concurrent: number = Number.POSITIVE_INFINITY |
| ): OperatorFunction<T, ObservedValueOf<O>|R> { |
| if (typeof resultSelector === 'function') { |
| // DEPRECATED PATH |
| return (source: Observable<T>) => source.pipe( |
| mergeMap((a, i) => from(project(a, i)).pipe( |
| map((b: any, ii: number) => resultSelector(a, b, i, ii)), |
| ), concurrent) |
| ); |
| } else if (typeof resultSelector === 'number') { |
| concurrent = resultSelector; |
| } |
| return (source: Observable<T>) => source.lift(new MergeMapOperator(project, concurrent)); |
| } |
| |
| export class MergeMapOperator<T, R> implements Operator<T, R> { |
| constructor(private project: (value: T, index: number) => ObservableInput<R>, |
| private concurrent: number = Number.POSITIVE_INFINITY) { |
| } |
| |
| call(observer: Subscriber<R>, source: any): any { |
| return source.subscribe(new MergeMapSubscriber( |
| observer, this.project, this.concurrent |
| )); |
| } |
| } |
| |
| /** |
| * We need this JSDoc comment for affecting ESDoc. |
| * @ignore |
| * @extends {Ignored} |
| */ |
| export class MergeMapSubscriber<T, R> extends OuterSubscriber<T, R> { |
| private hasCompleted: boolean = false; |
| private buffer: T[] = []; |
| private active: number = 0; |
| protected index: number = 0; |
| |
| constructor(destination: Subscriber<R>, |
| private project: (value: T, index: number) => ObservableInput<R>, |
| private concurrent: number = Number.POSITIVE_INFINITY) { |
| super(destination); |
| } |
| |
| protected _next(value: T): void { |
| if (this.active < this.concurrent) { |
| this._tryNext(value); |
| } else { |
| this.buffer.push(value); |
| } |
| } |
| |
| protected _tryNext(value: T) { |
| let result: ObservableInput<R>; |
| const index = this.index++; |
| try { |
| result = this.project(value, index); |
| } catch (err) { |
| this.destination.error(err); |
| return; |
| } |
| this.active++; |
| this._innerSub(result, value, index); |
| } |
| |
| private _innerSub(ish: 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, ish, value, index, innerSubscriber); |
| } |
| |
| protected _complete(): void { |
| this.hasCompleted = true; |
| if (this.active === 0 && this.buffer.length === 0) { |
| this.destination.complete(); |
| } |
| this.unsubscribe(); |
| } |
| |
| notifyNext(outerValue: T, innerValue: R, |
| outerIndex: number, innerIndex: number, |
| innerSub: InnerSubscriber<T, R>): void { |
| this.destination.next(innerValue); |
| } |
| |
| notifyComplete(innerSub: Subscription): void { |
| const buffer = this.buffer; |
| this.remove(innerSub); |
| this.active--; |
| if (buffer.length > 0) { |
| this._next(buffer.shift()); |
| } else if (this.active === 0 && this.hasCompleted) { |
| this.destination.complete(); |
| } |
| } |
| } |