es6/operators/bufferWhen.js

import { Subscription } from '../Subscription';
import { tryCatch } from '../util/tryCatch';
import { errorObject } from '../util/errorObject';
import { OuterSubscriber } from '../OuterSubscriber';
import { subscribeToResult } from '../util/subscribeToResult';
/**
 * Buffers the source Observable values, using a factory function of closing
 * Observables to determine when to close, emit, and reset the buffer.
 *
 * <span class="informal">Collects values from the past as an array. When it
 * starts collecting values, it calls a function that returns an Observable that
 * tells when to close the buffer and restart collecting.</span>
 *
 * <img src="./img/bufferWhen.png" width="100%">
 *
 * Opens a buffer immediately, then closes the buffer when the observable
 * returned by calling `closingSelector` function emits a value. When it closes
 * the buffer, it immediately opens a new buffer and repeats the process.
 *
 * @example <caption>Emit an array of the last clicks every [1-5] random seconds</caption>
 * var clicks = Rx.Observable.fromEvent(document, 'click');
 * var buffered = clicks.bufferWhen(() =>
 *   Rx.Observable.interval(1000 + Math.random() * 4000)
 * );
 * buffered.subscribe(x => console.log(x));
 *
 * @see {@link buffer}
 * @see {@link bufferCount}
 * @see {@link bufferTime}
 * @see {@link bufferToggle}
 * @see {@link windowWhen}
 *
 * @param {function(): Observable} closingSelector A function that takes no
 * arguments and returns an Observable that signals buffer closure.
 * @return {Observable<T[]>} An observable of arrays of buffered values.
 * @method bufferWhen
 * @owner Observable
 */
export function bufferWhen(closingSelector) {
    return function (source) {
        return source.lift(new BufferWhenOperator(closingSelector));
    };
}
class BufferWhenOperator {
    constructor(closingSelector) {
        this.closingSelector = closingSelector;
    }
    call(subscriber, source) {
        return source.subscribe(new BufferWhenSubscriber(subscriber, this.closingSelector));
    }
}
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @ignore
 * @extends {Ignored}
 */
class BufferWhenSubscriber extends OuterSubscriber {
    constructor(destination, closingSelector) {
        super(destination);
        this.closingSelector = closingSelector;
        this.subscribing = false;
        this.openBuffer();
    }
    _next(value) {
        this.buffer.push(value);
    }
    _complete() {
        const buffer = this.buffer;
        if (buffer) {
            this.destination.next(buffer);
        }
        super._complete();
    }
    _unsubscribe() {
        this.buffer = null;
        this.subscribing = false;
    }
    notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) {
        this.openBuffer();
    }
    notifyComplete() {
        if (this.subscribing) {
            this.complete();
        }
        else {
            this.openBuffer();
        }
    }
    openBuffer() {
        let { closingSubscription } = this;
        if (closingSubscription) {
            this.remove(closingSubscription);
            closingSubscription.unsubscribe();
        }
        const buffer = this.buffer;
        if (this.buffer) {
            this.destination.next(buffer);
        }
        this.buffer = [];
        const closingNotifier = tryCatch(this.closingSelector)();
        if (closingNotifier === errorObject) {
            this.error(errorObject.e);
        }
        else {
            closingSubscription = new Subscription();
            this.closingSubscription = closingSubscription;
            this.add(closingSubscription);
            this.subscribing = true;
            closingSubscription.add(subscribeToResult(this, closingNotifier));
            this.subscribing = false;
        }
    }
}
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