import { Observable } from '../Observable'; import { OperatorFunction } from '../types'; import { Subject } from '../Subject'; import { Subscriber } from '../Subscriber'; import { Operator } from '../Operator'; import { SimpleOuterSubscriber, innerSubscribe, SimpleInnerSubscriber } from '../innerSubscribe'; /** * Branch out the source Observable values as a nested Observable whenever * `windowBoundaries` emits. * * It's like {@link buffer}, but emits a nested Observable * instead of an array. * * ![](window.png) * * Returns an Observable that emits windows of items it collects from the source * Observable. The output Observable emits connected, non-overlapping * windows. It emits the current window and opens a new one whenever the * Observable `windowBoundaries` emits an item. Because each window is an * Observable, the output is a higher-order Observable. * * ## Example * In every window of 1 second each, emit at most 2 click events * ```ts * import { fromEvent, interval } from 'rxjs'; * import { window, mergeAll, map, take } from 'rxjs/operators'; * * const clicks = fromEvent(document, 'click'); * const sec = interval(1000); * const result = clicks.pipe( * window(sec), * map(win => win.pipe(take(2))), // each window has at most 2 emissions * mergeAll(), // flatten the Observable-of-Observables * ); * result.subscribe(x => console.log(x)); * ``` * @see {@link windowCount} * @see {@link windowTime} * @see {@link windowToggle} * @see {@link windowWhen} * @see {@link buffer} * * @param {Observable} windowBoundaries An Observable that completes the * previous window and starts a new window. * @return {Observable>} An Observable of windows, which are * Observables emitting values of the source Observable. * @method window * @owner Observable */ export function window(windowBoundaries: Observable): OperatorFunction> { return function windowOperatorFunction(source: Observable) { return source.lift(new WindowOperator(windowBoundaries)); }; } class WindowOperator implements Operator> { constructor(private windowBoundaries: Observable) { } call(subscriber: Subscriber>, source: any): any { const windowSubscriber = new WindowSubscriber(subscriber); const sourceSubscription = source.subscribe(windowSubscriber); if (!sourceSubscription.closed) { windowSubscriber.add(innerSubscribe(this.windowBoundaries, new SimpleInnerSubscriber(windowSubscriber))); } return sourceSubscription; } } /** * We need this JSDoc comment for affecting ESDoc. * @ignore * @extends {Ignored} */ class WindowSubscriber extends SimpleOuterSubscriber { private window: Subject = new Subject(); constructor(destination: Subscriber>) { super(destination); destination.next(this.window); } notifyNext(): void { this.openWindow(); } notifyError(error: any): void { this._error(error); } notifyComplete(): void { this._complete(); } protected _next(value: T): void { this.window.next(value); } protected _error(err: any): void { this.window.error(err); this.destination.error!(err); } protected _complete(): void { this.window.complete(); this.destination.complete!(); } /** @deprecated This is an internal implementation detail, do not use. */ _unsubscribe() { this.window = null!; } private openWindow(): void { const prevWindow = this.window; if (prevWindow) { prevWindow.complete(); } const destination = this.destination; const newWindow = this.window = new Subject(); destination.next!(newWindow); } }