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feat(mergeMapTo): add higher-order lettable version of mergeMapTo
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,168 @@ | ||
| import { Observable, ObservableInput } from '../Observable'; | ||
| import { Operator } from '../Operator'; | ||
| import { PartialObserver } from '../Observer'; | ||
| import { Subscriber } from '../Subscriber'; | ||
| import { Subscription } from '../Subscription'; | ||
| import { OuterSubscriber } from '../OuterSubscriber'; | ||
| import { InnerSubscriber } from '../InnerSubscriber'; | ||
| import { subscribeToResult } from '../util/subscribeToResult'; | ||
| import { OperatorFunction } from '../interfaces'; | ||
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| /* tslint:disable:max-line-length */ | ||
| export function mergeMapTo<T, R>(observable: ObservableInput<R>, concurrent?: number): OperatorFunction<T, R>; | ||
| export function mergeMapTo<T, I, R>(observable: ObservableInput<I>, resultSelector: (outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R, concurrent?: number): OperatorFunction<T, R>; | ||
| /* tslint:enable:max-line-length */ | ||
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| /** | ||
| * Projects each source value to the same Observable which is merged multiple | ||
| * times in the output Observable. | ||
| * | ||
| * <span class="informal">It's like {@link mergeMap}, but maps each value always | ||
| * to the same inner Observable.</span> | ||
| * | ||
| * <img src="./img/mergeMapTo.png" width="100%"> | ||
| * | ||
| * Maps each source value to the given Observable `innerObservable` regardless | ||
| * of the source value, and then merges those resulting Observables into one | ||
| * single Observable, which is the output Observable. | ||
| * | ||
| * @example <caption>For each click event, start an interval Observable ticking every 1 second</caption> | ||
| * var clicks = Rx.Observable.fromEvent(document, 'click'); | ||
| * var result = clicks.mergeMapTo(Rx.Observable.interval(1000)); | ||
| * result.subscribe(x => console.log(x)); | ||
| * | ||
| * @see {@link concatMapTo} | ||
| * @see {@link merge} | ||
| * @see {@link mergeAll} | ||
| * @see {@link mergeMap} | ||
| * @see {@link mergeScan} | ||
| * @see {@link switchMapTo} | ||
| * | ||
| * @param {ObservableInput} innerObservable An Observable to replace each value from | ||
| * the source Observable. | ||
| * @param {function(outerValue: T, innerValue: I, outerIndex: number, innerIndex: number): any} [resultSelector] | ||
| * A function to produce the value on the output Observable based on the values | ||
| * and the indices of the source (outer) emission and the inner Observable | ||
| * emission. The arguments passed to this function are: | ||
| * - `outerValue`: the value that came from the source | ||
| * - `innerValue`: the value that came from the projected Observable | ||
| * - `outerIndex`: the "index" of the value that came from the source | ||
| * - `innerIndex`: the "index" of the value from the projected Observable | ||
| * @param {number} [concurrent=Number.POSITIVE_INFINITY] Maximum number of input | ||
| * Observables being subscribed to concurrently. | ||
| * @return {Observable} An Observable that emits items from the given | ||
| * `innerObservable` (and optionally transformed through `resultSelector`) every | ||
| * time a value is emitted on the source Observable. | ||
| * @method mergeMapTo | ||
| * @owner Observable | ||
| */ | ||
| export function mergeMapTo<T, I, R>(innerObservable: Observable<I>, | ||
| resultSelector?: ((outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R) | number, | ||
| concurrent: number = Number.POSITIVE_INFINITY): OperatorFunction<T, R> { | ||
| if (typeof resultSelector === 'number') { | ||
| concurrent = <number>resultSelector; | ||
| resultSelector = null; | ||
| } | ||
| return (source: Observable<T>) => source.lift(new MergeMapToOperator(innerObservable, <any>resultSelector, concurrent)); | ||
| } | ||
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| // TODO: Figure out correct signature here: an Operator<Observable<T>, R> | ||
| // needs to implement call(observer: Subscriber<R>): Subscriber<Observable<T>> | ||
| export class MergeMapToOperator<T, I, R> implements Operator<Observable<T>, R> { | ||
| constructor(private ish: ObservableInput<I>, | ||
| private resultSelector?: (outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R, | ||
| private concurrent: number = Number.POSITIVE_INFINITY) { | ||
| } | ||
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| call(observer: Subscriber<R>, source: any): any { | ||
| return source.subscribe(new MergeMapToSubscriber(observer, this.ish, this.resultSelector, this.concurrent)); | ||
| } | ||
| } | ||
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| /** | ||
| * We need this JSDoc comment for affecting ESDoc. | ||
| * @ignore | ||
| * @extends {Ignored} | ||
| */ | ||
| export class MergeMapToSubscriber<T, I, R> extends OuterSubscriber<T, I> { | ||
| private hasCompleted: boolean = false; | ||
| private buffer: T[] = []; | ||
| private active: number = 0; | ||
| protected index: number = 0; | ||
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| constructor(destination: Subscriber<R>, | ||
| private ish: ObservableInput<I>, | ||
| private resultSelector?: (outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R, | ||
| private concurrent: number = Number.POSITIVE_INFINITY) { | ||
| super(destination); | ||
| } | ||
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| protected _next(value: T): void { | ||
| if (this.active < this.concurrent) { | ||
| const resultSelector = this.resultSelector; | ||
| const index = this.index++; | ||
| const ish = this.ish; | ||
| const destination = this.destination; | ||
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| this.active++; | ||
| this._innerSub(ish, destination, resultSelector, value, index); | ||
| } else { | ||
| this.buffer.push(value); | ||
| } | ||
| } | ||
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| private _innerSub(ish: ObservableInput<I>, | ||
| destination: PartialObserver<I>, | ||
| resultSelector: (outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R, | ||
| value: T, | ||
| index: number): void { | ||
| this.add(subscribeToResult<T, I>(this, ish, value, index)); | ||
| } | ||
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| protected _complete(): void { | ||
| this.hasCompleted = true; | ||
| if (this.active === 0 && this.buffer.length === 0) { | ||
| this.destination.complete(); | ||
| } | ||
| } | ||
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| notifyNext(outerValue: T, innerValue: I, | ||
| outerIndex: number, innerIndex: number, | ||
| innerSub: InnerSubscriber<T, I>): void { | ||
| const { resultSelector, destination } = this; | ||
| if (resultSelector) { | ||
| this.trySelectResult(outerValue, innerValue, outerIndex, innerIndex); | ||
| } else { | ||
| destination.next(innerValue); | ||
| } | ||
| } | ||
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| private trySelectResult(outerValue: T, innerValue: I, | ||
| outerIndex: number, innerIndex: number): void { | ||
| const { resultSelector, destination } = this; | ||
| let result: R; | ||
| try { | ||
| result = resultSelector(outerValue, innerValue, outerIndex, innerIndex); | ||
| } catch (err) { | ||
| destination.error(err); | ||
| return; | ||
| } | ||
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| destination.next(result); | ||
| } | ||
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| notifyError(err: any): void { | ||
| this.destination.error(err); | ||
| } | ||
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| 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(); | ||
| } | ||
| } | ||
| } |