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feat(windowCount): add higher-order lettable version of windowCount
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,134 @@ | ||
| import { Operator } from '../Operator'; | ||
| import { Subscriber } from '../Subscriber'; | ||
| import { Observable } from '../Observable'; | ||
| import { Subject } from '../Subject'; | ||
| import { OperatorFunction } from '../interfaces'; | ||
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| /** | ||
| * Branch out the source Observable values as a nested Observable with each | ||
| * nested Observable emitting at most `windowSize` values. | ||
| * | ||
| * <span class="informal">It's like {@link bufferCount}, but emits a nested | ||
| * Observable instead of an array.</span> | ||
| * | ||
| * <img src="./img/windowCount.png" width="100%"> | ||
| * | ||
| * Returns an Observable that emits windows of items it collects from the source | ||
| * Observable. The output Observable emits windows every `startWindowEvery` | ||
| * items, each containing no more than `windowSize` items. When the source | ||
| * Observable completes or encounters an error, the output Observable emits | ||
| * the current window and propagates the notification from the source | ||
| * Observable. If `startWindowEvery` is not provided, then new windows are | ||
| * started immediately at the start of the source and when each window completes | ||
| * with size `windowSize`. | ||
| * | ||
| * @example <caption>Ignore every 3rd click event, starting from the first one</caption> | ||
| * var clicks = Rx.Observable.fromEvent(document, 'click'); | ||
| * var result = clicks.windowCount(3) | ||
| * .map(win => win.skip(1)) // skip first of every 3 clicks | ||
| * .mergeAll(); // flatten the Observable-of-Observables | ||
| * result.subscribe(x => console.log(x)); | ||
| * | ||
| * @example <caption>Ignore every 3rd click event, starting from the third one</caption> | ||
| * var clicks = Rx.Observable.fromEvent(document, 'click'); | ||
| * var result = clicks.windowCount(2, 3) | ||
| * .mergeAll(); // flatten the Observable-of-Observables | ||
| * result.subscribe(x => console.log(x)); | ||
| * | ||
| * @see {@link window} | ||
| * @see {@link windowTime} | ||
| * @see {@link windowToggle} | ||
| * @see {@link windowWhen} | ||
| * @see {@link bufferCount} | ||
| * | ||
| * @param {number} windowSize The maximum number of values emitted by each | ||
| * window. | ||
| * @param {number} [startWindowEvery] Interval at which to start a new window. | ||
| * For example if `startWindowEvery` is `2`, then a new window will be started | ||
| * on every other value from the source. A new window is started at the | ||
| * beginning of the source by default. | ||
| * @return {Observable<Observable<T>>} An Observable of windows, which in turn | ||
| * are Observable of values. | ||
| * @method windowCount | ||
| * @owner Observable | ||
| */ | ||
| export function windowCount<T>(windowSize: number, | ||
| startWindowEvery: number = 0): OperatorFunction<T, Observable<T>> { | ||
| return function windowCountOperatorFunction(source: Observable<T>) { | ||
| return source.lift(new WindowCountOperator<T>(windowSize, startWindowEvery)); | ||
| }; | ||
| } | ||
|
|
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| class WindowCountOperator<T> implements Operator<T, Observable<T>> { | ||
|
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| constructor(private windowSize: number, | ||
| private startWindowEvery: number) { | ||
| } | ||
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| call(subscriber: Subscriber<Observable<T>>, source: any): any { | ||
| return source.subscribe(new WindowCountSubscriber(subscriber, this.windowSize, this.startWindowEvery)); | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * We need this JSDoc comment for affecting ESDoc. | ||
| * @ignore | ||
| * @extends {Ignored} | ||
| */ | ||
| class WindowCountSubscriber<T> extends Subscriber<T> { | ||
| private windows: Subject<T>[] = [ new Subject<T>() ]; | ||
| private count: number = 0; | ||
|
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| constructor(protected destination: Subscriber<Observable<T>>, | ||
| private windowSize: number, | ||
| private startWindowEvery: number) { | ||
| super(destination); | ||
| destination.next(this.windows[0]); | ||
| } | ||
|
|
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| protected _next(value: T) { | ||
| const startWindowEvery = (this.startWindowEvery > 0) ? this.startWindowEvery : this.windowSize; | ||
| const destination = this.destination; | ||
| const windowSize = this.windowSize; | ||
| const windows = this.windows; | ||
| const len = windows.length; | ||
|
|
||
| for (let i = 0; i < len && !this.closed; i++) { | ||
| windows[i].next(value); | ||
| } | ||
| const c = this.count - windowSize + 1; | ||
| if (c >= 0 && c % startWindowEvery === 0 && !this.closed) { | ||
| windows.shift().complete(); | ||
| } | ||
| if (++this.count % startWindowEvery === 0 && !this.closed) { | ||
| const window = new Subject<T>(); | ||
| windows.push(window); | ||
| destination.next(window); | ||
| } | ||
| } | ||
|
|
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| protected _error(err: any) { | ||
| const windows = this.windows; | ||
| if (windows) { | ||
| while (windows.length > 0 && !this.closed) { | ||
| windows.shift().error(err); | ||
| } | ||
| } | ||
| this.destination.error(err); | ||
| } | ||
|
|
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| protected _complete() { | ||
| const windows = this.windows; | ||
| if (windows) { | ||
| while (windows.length > 0 && !this.closed) { | ||
| windows.shift().complete(); | ||
| } | ||
| } | ||
| this.destination.complete(); | ||
| } | ||
|
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| protected _unsubscribe() { | ||
| this.count = 0; | ||
| this.windows = null; | ||
| } | ||
| } |