import { Operator } from '../Operator';
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import { Subscriber } from '../Subscriber';
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import { Observable } from '../Observable';
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import { Subject } from '../Subject';
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import { Subscription } from '../Subscription';
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import { OuterSubscriber } from '../OuterSubscriber';
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import { InnerSubscriber } from '../InnerSubscriber';
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import { subscribeToResult } from '../util/subscribeToResult';
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import { OperatorFunction } from '../types';
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/**
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* Branch out the source Observable values as a nested Observable using a
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* factory function of closing Observables to determine when to start a new
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* window.
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*
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* <span class="informal">It's like {@link bufferWhen}, but emits a nested
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* Observable instead of an array.</span>
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*
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* 
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*
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* Returns an Observable that emits windows of items it collects from the source
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* Observable. The output Observable emits connected, non-overlapping windows.
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* It emits the current window and opens a new one whenever the Observable
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* produced by the specified `closingSelector` function emits an item. The first
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* window is opened immediately when subscribing to the output Observable.
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*
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* ## Example
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* Emit only the first two clicks events in every window of [1-5] random seconds
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* ```ts
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* import { fromEvent, interval } from 'rxjs';
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* import { windowWhen, map, mergeAll, take } from 'rxjs/operators';
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*
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* const clicks = fromEvent(document, 'click');
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* const result = clicks.pipe(
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* windowWhen(() => interval(1000 + Math.random() * 4000)),
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* map(win => win.pipe(take(2))), // each window has at most 2 emissions
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* mergeAll() // flatten the Observable-of-Observables
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* );
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* result.subscribe(x => console.log(x));
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* ```
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*
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* @see {@link window}
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* @see {@link windowCount}
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* @see {@link windowTime}
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* @see {@link windowToggle}
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* @see {@link bufferWhen}
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*
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* @param {function(): Observable} closingSelector A function that takes no
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* arguments and returns an Observable that signals (on either `next` or
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* `complete`) when to close the previous window and start a new one.
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* @return {Observable<Observable<T>>} An observable of windows, which in turn
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* are Observables.
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* @method windowWhen
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* @owner Observable
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*/
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export function windowWhen<T>(closingSelector: () => Observable<any>): OperatorFunction<T, Observable<T>> {
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return function windowWhenOperatorFunction(source: Observable<T>) {
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return source.lift(new WindowOperator<T>(closingSelector));
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};
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}
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class WindowOperator<T> implements Operator<T, Observable<T>> {
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constructor(private closingSelector: () => Observable<any>) {
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}
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call(subscriber: Subscriber<Observable<T>>, source: any): any {
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return source.subscribe(new WindowSubscriber(subscriber, this.closingSelector));
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}
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}
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/**
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* We need this JSDoc comment for affecting ESDoc.
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* @ignore
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* @extends {Ignored}
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*/
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class WindowSubscriber<T> extends OuterSubscriber<T, any> {
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private window: Subject<T>;
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private closingNotification: Subscription;
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constructor(protected destination: Subscriber<Observable<T>>,
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private closingSelector: () => Observable<any>) {
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super(destination);
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this.openWindow();
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}
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notifyNext(outerValue: T, innerValue: any,
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outerIndex: number, innerIndex: number,
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innerSub: InnerSubscriber<T, any>): void {
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this.openWindow(innerSub);
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}
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notifyError(error: any, innerSub: InnerSubscriber<T, any>): void {
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this._error(error);
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}
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notifyComplete(innerSub: InnerSubscriber<T, any>): void {
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this.openWindow(innerSub);
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}
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protected _next(value: T): void {
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this.window.next(value);
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}
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protected _error(err: any): void {
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this.window.error(err);
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this.destination.error(err);
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this.unsubscribeClosingNotification();
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}
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protected _complete(): void {
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this.window.complete();
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this.destination.complete();
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this.unsubscribeClosingNotification();
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}
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private unsubscribeClosingNotification(): void {
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if (this.closingNotification) {
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this.closingNotification.unsubscribe();
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}
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}
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private openWindow(innerSub: InnerSubscriber<T, any> = null): void {
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if (innerSub) {
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this.remove(innerSub);
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innerSub.unsubscribe();
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}
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const prevWindow = this.window;
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if (prevWindow) {
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prevWindow.complete();
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}
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const window = this.window = new Subject<T>();
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this.destination.next(window);
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let closingNotifier;
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try {
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const { closingSelector } = this;
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closingNotifier = closingSelector();
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} catch (e) {
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this.destination.error(e);
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this.window.error(e);
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return;
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}
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this.add(this.closingNotification = subscribeToResult(this, closingNotifier));
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}
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}
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