work.suroh.tk/node_modules/rxjs/_esm2015/operators/refCount.js

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2019-12-02 12:22:45 +00:00
import { Subscriber } from '../Subscriber';
export function refCount() {
return function refCountOperatorFunction(source) {
return source.lift(new RefCountOperator(source));
};
}
class RefCountOperator {
constructor(connectable) {
this.connectable = connectable;
}
call(subscriber, source) {
const { connectable } = this;
connectable._refCount++;
const refCounter = new RefCountSubscriber(subscriber, connectable);
const subscription = source.subscribe(refCounter);
if (!refCounter.closed) {
refCounter.connection = connectable.connect();
}
return subscription;
}
}
class RefCountSubscriber extends Subscriber {
constructor(destination, connectable) {
super(destination);
this.connectable = connectable;
}
/** @deprecated internal use only */ _unsubscribe() {
const { connectable } = this;
if (!connectable) {
this.connection = null;
return;
}
this.connectable = null;
const refCount = connectable._refCount;
if (refCount <= 0) {
this.connection = null;
return;
}
connectable._refCount = refCount - 1;
if (refCount > 1) {
this.connection = null;
return;
}
///
// Compare the local RefCountSubscriber's connection Subscription to the
// connection Subscription on the shared ConnectableObservable. In cases
// where the ConnectableObservable source synchronously emits values, and
// the RefCountSubscriber's downstream Observers synchronously unsubscribe,
// execution continues to here before the RefCountOperator has a chance to
// supply the RefCountSubscriber with the shared connection Subscription.
// For example:
// ```
// Observable.range(0, 10)
// .publish()
// .refCount()
// .take(5)
// .subscribe();
// ```
// In order to account for this case, RefCountSubscriber should only dispose
// the ConnectableObservable's shared connection Subscription if the
// connection Subscription exists, *and* either:
// a. RefCountSubscriber doesn't have a reference to the shared connection
// Subscription yet, or,
// b. RefCountSubscriber's connection Subscription reference is identical
// to the shared connection Subscription
///
const { connection } = this;
const sharedConnection = connectable._connection;
this.connection = null;
if (sharedConnection && (!connection || sharedConnection === connection)) {
sharedConnection.unsubscribe();
}
}
}
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