import { OperatorFunction, ObservableInput } from '../types';
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import { operate } from '../util/lift';
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import { noop } from '../util/noop';
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import { createOperatorSubscriber } from './OperatorSubscriber';
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import { innerFrom } from '../observable/innerFrom';
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/**
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* Buffers the source Observable values until `closingNotifier` emits.
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*
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* <span class="informal">Collects values from the past as an array, and emits
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* that array only when another Observable emits.</span>
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*
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* 
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*
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* Buffers the incoming Observable values until the given `closingNotifier`
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* `ObservableInput` (that internally gets converted to an Observable)
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* emits a value, at which point it emits the buffer on the output
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* Observable and starts a new buffer internally, awaiting the next time
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* `closingNotifier` emits.
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*
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* ## Example
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*
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* On every click, emit array of most recent interval events
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*
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* ```ts
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* import { fromEvent, interval, buffer } from 'rxjs';
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*
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* const clicks = fromEvent(document, 'click');
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* const intervalEvents = interval(1000);
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* const buffered = intervalEvents.pipe(buffer(clicks));
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* buffered.subscribe(x => console.log(x));
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* ```
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*
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* @see {@link bufferCount}
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* @see {@link bufferTime}
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* @see {@link bufferToggle}
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* @see {@link bufferWhen}
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* @see {@link window}
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*
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* @param closingNotifier An `ObservableInput` that signals the
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* buffer to be emitted on the output Observable.
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* @return A function that returns an Observable of buffers, which are arrays
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* of values.
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*/
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export function buffer<T>(closingNotifier: ObservableInput<any>): OperatorFunction<T, T[]> {
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return operate((source, subscriber) => {
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// The current buffered values.
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let currentBuffer: T[] = [];
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// Subscribe to our source.
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source.subscribe(
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createOperatorSubscriber(
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subscriber,
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(value) => currentBuffer.push(value),
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() => {
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subscriber.next(currentBuffer);
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subscriber.complete();
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}
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)
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);
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// Subscribe to the closing notifier.
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innerFrom(closingNotifier).subscribe(
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createOperatorSubscriber(
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subscriber,
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() => {
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// Start a new buffer and emit the previous one.
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const b = currentBuffer;
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currentBuffer = [];
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subscriber.next(b);
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},
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noop
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)
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);
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return () => {
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// Ensure buffered values are released on finalization.
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currentBuffer = null!;
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};
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});
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}
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