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- import { Operator } from '../Operator';
- import { Subscriber } from '../Subscriber';
- import { Observable } from '../Observable';
- import { Subject } from '../Subject';
- import { Subscription } from '../Subscription';
- import { OuterSubscriber } from '../OuterSubscriber';
- import { InnerSubscriber } from '../InnerSubscriber';
- import { subscribeToResult } from '../util/subscribeToResult';
- import { OperatorFunction } from '../types';
-
- /**
- * Branch out the source Observable values as a nested Observable using a
- * factory function of closing Observables to determine when to start a new
- * window.
- *
- * <span class="informal">It's like {@link bufferWhen}, but emits a nested
- * Observable instead of an array.</span>
- *
- * ![](windowWhen.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
- * produced by the specified `closingSelector` function emits an item. The first
- * window is opened immediately when subscribing to the output Observable.
- *
- * ## Example
- * Emit only the first two clicks events in every window of [1-5] random seconds
- * ```ts
- * import { fromEvent, interval } from 'rxjs';
- * import { windowWhen, map, mergeAll, take } from 'rxjs/operators';
- *
- * const clicks = fromEvent(document, 'click');
- * const result = clicks.pipe(
- * windowWhen(() => interval(1000 + Math.random() * 4000)),
- * 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 window}
- * @see {@link windowCount}
- * @see {@link windowTime}
- * @see {@link windowToggle}
- * @see {@link bufferWhen}
- *
- * @param {function(): Observable} closingSelector A function that takes no
- * arguments and returns an Observable that signals (on either `next` or
- * `complete`) when to close the previous window and start a new one.
- * @return {Observable<Observable<T>>} An observable of windows, which in turn
- * are Observables.
- * @method windowWhen
- * @owner Observable
- */
- export function windowWhen<T>(closingSelector: () => Observable<any>): OperatorFunction<T, Observable<T>> {
- return function windowWhenOperatorFunction(source: Observable<T>) {
- return source.lift(new WindowOperator<T>(closingSelector));
- };
- }
-
- class WindowOperator<T> implements Operator<T, Observable<T>> {
- constructor(private closingSelector: () => Observable<any>) {
- }
-
- call(subscriber: Subscriber<Observable<T>>, source: any): any {
- return source.subscribe(new WindowSubscriber(subscriber, this.closingSelector));
- }
- }
-
- /**
- * We need this JSDoc comment for affecting ESDoc.
- * @ignore
- * @extends {Ignored}
- */
- class WindowSubscriber<T> extends OuterSubscriber<T, any> {
- private window: Subject<T>;
- private closingNotification: Subscription;
-
- constructor(protected destination: Subscriber<Observable<T>>,
- private closingSelector: () => Observable<any>) {
- super(destination);
- this.openWindow();
- }
-
- notifyNext(outerValue: T, innerValue: any,
- outerIndex: number, innerIndex: number,
- innerSub: InnerSubscriber<T, any>): void {
- this.openWindow(innerSub);
- }
-
- notifyError(error: any, innerSub: InnerSubscriber<T, any>): void {
- this._error(error);
- }
-
- notifyComplete(innerSub: InnerSubscriber<T, any>): void {
- this.openWindow(innerSub);
- }
-
- protected _next(value: T): void {
- this.window.next(value);
- }
-
- protected _error(err: any): void {
- this.window.error(err);
- this.destination.error(err);
- this.unsubscribeClosingNotification();
- }
-
- protected _complete(): void {
- this.window.complete();
- this.destination.complete();
- this.unsubscribeClosingNotification();
- }
-
- private unsubscribeClosingNotification(): void {
- if (this.closingNotification) {
- this.closingNotification.unsubscribe();
- }
- }
-
- private openWindow(innerSub: InnerSubscriber<T, any> = null): void {
- if (innerSub) {
- this.remove(innerSub);
- innerSub.unsubscribe();
- }
-
- const prevWindow = this.window;
- if (prevWindow) {
- prevWindow.complete();
- }
-
- const window = this.window = new Subject<T>();
- this.destination.next(window);
-
- let closingNotifier;
- try {
- const { closingSelector } = this;
- closingNotifier = closingSelector();
- } catch (e) {
- this.destination.error(e);
- this.window.error(e);
- return;
- }
- this.add(this.closingNotification = subscribeToResult(this, closingNotifier));
- }
- }
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