| import { Operator } from '../Operator'; |
| import { Subscriber } from '../Subscriber'; |
| import { Observable } from '../Observable'; |
| import { Subject } from '../Subject'; |
| import { OperatorFunction } from '../types'; |
| |
| /** |
| * 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> |
| * |
| * ![](windowCount.png) |
| * |
| * 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`. |
| * |
| * ## Examples |
| * Ignore every 3rd click event, starting from the first one |
| * ```ts |
| * import { fromEvent } from 'rxjs'; |
| * import { windowCount, map, mergeAll, skip } from 'rxjs/operators'; |
| * |
| * const clicks = fromEvent(document, 'click'); |
| * const result = clicks.pipe( |
| * windowCount(3), |
| * map(win => win.pipe(skip(1))), // skip first of every 3 clicks |
| * mergeAll() // flatten the Observable-of-Observables |
| * ); |
| * result.subscribe(x => console.log(x)); |
| * ``` |
| * |
| * Ignore every 3rd click event, starting from the third one |
| * ```ts |
| * import { fromEvent } from 'rxjs'; |
| * import { windowCount, mergeAll } from 'rxjs/operators'; |
| * |
| * const clicks = fromEvent(document, 'click'); |
| * const result = clicks.pipe( |
| * 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)); |
| }; |
| } |
| |
| class WindowCountOperator<T> implements Operator<T, Observable<T>> { |
| |
| constructor(private windowSize: number, |
| private startWindowEvery: number) { |
| } |
| |
| 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; |
| |
| constructor(protected destination: Subscriber<Observable<T>>, |
| private windowSize: number, |
| private startWindowEvery: number) { |
| super(destination); |
| destination.next(this.windows[0]); |
| } |
| |
| 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); |
| } |
| } |
| |
| protected _error(err: any) { |
| const windows = this.windows; |
| if (windows) { |
| while (windows.length > 0 && !this.closed) { |
| windows.shift().error(err); |
| } |
| } |
| this.destination.error(err); |
| } |
| |
| protected _complete() { |
| const windows = this.windows; |
| if (windows) { |
| while (windows.length > 0 && !this.closed) { |
| windows.shift().complete(); |
| } |
| } |
| this.destination.complete(); |
| } |
| |
| protected _unsubscribe() { |
| this.count = 0; |
| this.windows = null; |
| } |
| } |