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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>
*
* 
*
* 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
* ```javascript
* import { fromEvent, interval } from 'rxjs';
* import { windowWhen, map, mergeAll } 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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