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- import { Subscription } from '../Subscription';
- import { OperatorFunction, ObservableInput } from '../types';
- import { operate } from '../util/lift';
- import { innerFrom } from '../observable/innerFrom';
- import { createOperatorSubscriber } from './OperatorSubscriber';
- import { noop } from '../util/noop';
- import { arrRemove } from '../util/arrRemove';
- /**
- * Buffers the source Observable values starting from an emission from
- * `openings` and ending when the output of `closingSelector` emits.
- *
- * <span class="informal">Collects values from the past as an array. Starts
- * collecting only when `opening` emits, and calls the `closingSelector`
- * function to get an Observable that tells when to close the buffer.</span>
- *
- * 
- *
- * Buffers values from the source by opening the buffer via signals from an
- * Observable provided to `openings`, and closing and sending the buffers when
- * a Subscribable or Promise returned by the `closingSelector` function emits.
- *
- * ## Example
- *
- * Every other second, emit the click events from the next 500ms
- *
- * ```ts
- * import { fromEvent, interval, bufferToggle, EMPTY } from 'rxjs';
- *
- * const clicks = fromEvent(document, 'click');
- * const openings = interval(1000);
- * const buffered = clicks.pipe(bufferToggle(openings, i =>
- * i % 2 ? interval(500) : EMPTY
- * ));
- * buffered.subscribe(x => console.log(x));
- * ```
- *
- * @see {@link buffer}
- * @see {@link bufferCount}
- * @see {@link bufferTime}
- * @see {@link bufferWhen}
- * @see {@link windowToggle}
- *
- * @param openings A Subscribable or Promise of notifications to start new
- * buffers.
- * @param closingSelector A function that takes
- * the value emitted by the `openings` observable and returns a Subscribable or Promise,
- * which, when it emits, signals that the associated buffer should be emitted
- * and cleared.
- * @return A function that returns an Observable of arrays of buffered values.
- */
- export function bufferToggle<T, O>(
- openings: ObservableInput<O>,
- closingSelector: (value: O) => ObservableInput<any>
- ): OperatorFunction<T, T[]> {
- return operate((source, subscriber) => {
- const buffers: T[][] = [];
- // Subscribe to the openings notifier first
- innerFrom(openings).subscribe(
- createOperatorSubscriber(
- subscriber,
- (openValue) => {
- const buffer: T[] = [];
- buffers.push(buffer);
- // We use this composite subscription, so that
- // when the closing notifier emits, we can tear it down.
- const closingSubscription = new Subscription();
- const emitBuffer = () => {
- arrRemove(buffers, buffer);
- subscriber.next(buffer);
- closingSubscription.unsubscribe();
- };
- // The line below will add the subscription to the parent subscriber *and* the closing subscription.
- closingSubscription.add(innerFrom(closingSelector(openValue)).subscribe(createOperatorSubscriber(subscriber, emitBuffer, noop)));
- },
- noop
- )
- );
- source.subscribe(
- createOperatorSubscriber(
- subscriber,
- (value) => {
- // Value from our source. Add it to all pending buffers.
- for (const buffer of buffers) {
- buffer.push(value);
- }
- },
- () => {
- // Source complete. Emit all pending buffers.
- while (buffers.length > 0) {
- subscriber.next(buffers.shift()!);
- }
- subscriber.complete();
- }
- )
- );
- });
- }
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