es6/operators/windowWhen.js

import { Subject } from '../Subject';
import { tryCatch } from '../util/tryCatch';
import { errorObject } from '../util/errorObject';
import { OuterSubscriber } from '../OuterSubscriber';
import { subscribeToResult } from '../util/subscribeToResult';
/**
 * 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>
 *
 * <img src="./img/windowWhen.png" width="100%">
 *
 * 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 <caption>Emit only the first two clicks events in every window of [1-5] random seconds</caption>
 * var clicks = Rx.Observable.fromEvent(document, 'click');
 * var result = clicks
 *   .windowWhen(() => Rx.Observable.interval(1000 + Math.random() * 4000))
 *   .map(win => win.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(closingSelector) {
    return function windowWhenOperatorFunction(source) {
        return source.lift(new WindowOperator(closingSelector));
    };
}
class WindowOperator {
    constructor(closingSelector) {
        this.closingSelector = closingSelector;
    }
    call(subscriber, source) {
        return source.subscribe(new WindowSubscriber(subscriber, this.closingSelector));
    }
}
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @ignore
 * @extends {Ignored}
 */
class WindowSubscriber extends OuterSubscriber {
    constructor(destination, closingSelector) {
        super(destination);
        this.destination = destination;
        this.closingSelector = closingSelector;
        this.openWindow();
    }
    notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) {
        this.openWindow(innerSub);
    }
    notifyError(error, innerSub) {
        this._error(error);
    }
    notifyComplete(innerSub) {
        this.openWindow(innerSub);
    }
    _next(value) {
        this.window.next(value);
    }
    _error(err) {
        this.window.error(err);
        this.destination.error(err);
        this.unsubscribeClosingNotification();
    }
    _complete() {
        this.window.complete();
        this.destination.complete();
        this.unsubscribeClosingNotification();
    }
    unsubscribeClosingNotification() {
        if (this.closingNotification) {
            this.closingNotification.unsubscribe();
        }
    }
    openWindow(innerSub = null) {
        if (innerSub) {
            this.remove(innerSub);
            innerSub.unsubscribe();
        }
        const prevWindow = this.window;
        if (prevWindow) {
            prevWindow.complete();
        }
        const window = this.window = new Subject();
        this.destination.next(window);
        const closingNotifier = tryCatch(this.closingSelector)();
        if (closingNotifier === errorObject) {
            const err = errorObject.e;
            this.destination.error(err);
            this.window.error(err);
        }
        else {
            this.add(this.closingNotification = subscribeToResult(this, closingNotifier));
        }
    }
}
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