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import { Observable } from '../Observable';
import { innerFrom } from '../observable/innerFrom';
import { Subject } from '../Subject';
import { Subscription } from '../Subscription';
import { MonoTypeOperatorFunction, ObservableInput } from '../types';
import { operate } from '../util/lift';
import { createOperatorSubscriber } from './OperatorSubscriber';
/**
* Returns an Observable that mirrors the source Observable with the exception of a `complete`. If the source
* Observable calls `complete`, this method will emit to the Observable returned from `notifier`. If that Observable
* calls `complete` or `error`, then this method will call `complete` or `error` on the child subscription. Otherwise
* this method will resubscribe to the source Observable.
*
* 
*
* ## Example
*
* Repeat a message stream on click
*
* ```ts
* import { of, fromEvent, repeatWhen } from 'rxjs';
*
* const source = of('Repeat message');
* const documentClick$ = fromEvent(document, 'click');
*
* const result = source.pipe(repeatWhen(() => documentClick$));
*
* result.subscribe(data => console.log(data))
* ```
*
* @see {@link repeat}
* @see {@link retry}
* @see {@link retryWhen}
*
* @param notifier Function that receives an Observable of notifications with
* which a user can `complete` or `error`, aborting the repetition.
* @return A function that returns an `ObservableInput` that mirrors the source
* Observable with the exception of a `complete`.
* @deprecated Will be removed in v9 or v10. Use {@link repeat}'s {@link RepeatConfig#delay delay} option instead.
* Instead of `repeatWhen(() => notify$)`, use: `repeat({ delay: () => notify$ })`.
*/
export function repeatWhen<T>(notifier: (notifications: Observable<void>) => ObservableInput<any>): MonoTypeOperatorFunction<T> {
return operate((source, subscriber) => {
let innerSub: Subscription | null;
let syncResub = false;
let completions$: Subject<void>;
let isNotifierComplete = false;
let isMainComplete = false;
/**
* Checks to see if we can complete the result, completes it, and returns `true` if it was completed.
*/
const checkComplete = () => isMainComplete && isNotifierComplete && (subscriber.complete(), true);
/**
* Gets the subject to send errors through. If it doesn't exist,
* we know we need to setup the notifier.
*/
const getCompletionSubject = () => {
if (!completions$) {
completions$ = new Subject();
// If the call to `notifier` throws, it will be caught by the OperatorSubscriber
// In the main subscription -- in `subscribeForRepeatWhen`.
innerFrom(notifier(completions$)).subscribe(
createOperatorSubscriber(
subscriber,
() => {
if (innerSub) {
subscribeForRepeatWhen();
} else {
// If we don't have an innerSub yet, that's because the inner subscription
// call hasn't even returned yet. We've arrived here synchronously.
// So we flag that we want to resub, such that we can ensure finalization
// happens before we resubscribe.
syncResub = true;
}
},
() => {
isNotifierComplete = true;
checkComplete();
}
)
);
}
return completions$;
};
const subscribeForRepeatWhen = () => {
isMainComplete = false;
innerSub = source.subscribe(
createOperatorSubscriber(subscriber, undefined, () => {
isMainComplete = true;
// Check to see if we are complete, and complete if so.
// If we are not complete. Get the subject. This calls the `notifier` function.
// If that function fails, it will throw and `.next()` will not be reached on this
// line. The thrown error is caught by the _complete handler in this
// `OperatorSubscriber` and handled appropriately.
!checkComplete() && getCompletionSubject().next();
})
);
if (syncResub) {
// Ensure that the inner subscription is torn down before
// moving on to the next subscription in the synchronous case.
// If we don't do this here, all inner subscriptions will not be
// torn down until the entire observable is done.
innerSub.unsubscribe();
// It is important to null this out. Not only to free up memory, but
// to make sure code above knows we are in a subscribing state to
// handle synchronous resubscription.
innerSub = null;
// We may need to do this multiple times, so reset the flags.
syncResub = false;
// Resubscribe
subscribeForRepeatWhen();
}
};
// Start the subscription
subscribeForRepeatWhen();
});
}