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
|
* ```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): 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 = 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));
|
}
|
}
|
