import { MonoTypeOperatorFunction } from '../types';
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import { operate } from '../util/lift';
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/**
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* Returns an Observable that mirrors the source Observable, but will call a specified function when
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* the source terminates on complete or error.
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* The specified function will also be called when the subscriber explicitly unsubscribes.
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*
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* ## Examples
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*
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* Execute callback function when the observable completes
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*
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* ```ts
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* import { interval, take, finalize } from 'rxjs';
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*
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* // emit value in sequence every 1 second
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* const source = interval(1000);
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* const example = source.pipe(
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* take(5), //take only the first 5 values
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* finalize(() => console.log('Sequence complete')) // Execute when the observable completes
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* );
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* const subscribe = example.subscribe(val => console.log(val));
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*
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* // results:
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* // 0
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* // 1
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* // 2
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* // 3
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* // 4
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* // 'Sequence complete'
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* ```
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*
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* Execute callback function when the subscriber explicitly unsubscribes
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*
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* ```ts
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* import { interval, finalize, tap, noop, timer } from 'rxjs';
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*
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* const source = interval(100).pipe(
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* finalize(() => console.log('[finalize] Called')),
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* tap({
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* next: () => console.log('[next] Called'),
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* error: () => console.log('[error] Not called'),
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* complete: () => console.log('[tap complete] Not called')
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* })
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* );
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*
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* const sub = source.subscribe({
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* next: x => console.log(x),
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* error: noop,
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* complete: () => console.log('[complete] Not called')
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* });
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*
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* timer(150).subscribe(() => sub.unsubscribe());
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*
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* // results:
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* // '[next] Called'
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* // 0
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* // '[finalize] Called'
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* ```
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*
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* @param {function} callback Function to be called when source terminates.
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* @return A function that returns an Observable that mirrors the source, but
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* will call the specified function on termination.
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*/
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export function finalize<T>(callback: () => void): MonoTypeOperatorFunction<T> {
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return operate((source, subscriber) => {
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// TODO: This try/finally was only added for `useDeprecatedSynchronousErrorHandling`.
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// REMOVE THIS WHEN THAT HOT GARBAGE IS REMOVED IN V8.
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try {
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source.subscribe(subscriber);
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} finally {
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subscriber.add(callback);
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}
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});
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}
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