es6/operators/multicast.js

import { connectableObservableDescriptor } from '../observable/ConnectableObservable';
/* tslint:enable:max-line-length */
/**
 * Returns an Observable that emits the results of invoking a specified selector on items
 * emitted by a ConnectableObservable that shares a single subscription to the underlying stream.
 *
 * <img src="./img/multicast.png" width="100%">
 *
 * @param {Function|Subject} subjectOrSubjectFactory - Factory function to create an intermediate subject through
 * which the source sequence's elements will be multicast to the selector function
 * or Subject to push source elements into.
 * @param {Function} [selector] - Optional selector function that can use the multicasted source stream
 * as many times as needed, without causing multiple subscriptions to the source stream.
 * Subscribers to the given source will receive all notifications of the source from the
 * time of the subscription forward.
 * @return {Observable} An Observable that emits the results of invoking the selector
 * on the items emitted by a `ConnectableObservable` that shares a single subscription to
 * the underlying stream.
 * @method multicast
 * @owner Observable
 */
export function multicast(subjectOrSubjectFactory, selector) {
    return function multicastOperatorFunction(source) {
        let subjectFactory;
        if (typeof subjectOrSubjectFactory === 'function') {
            subjectFactory = subjectOrSubjectFactory;
        }
        else {
            subjectFactory = function subjectFactory() {
                return subjectOrSubjectFactory;
            };
        }
        if (typeof selector === 'function') {
            return source.lift(new MulticastOperator(subjectFactory, selector));
        }
        const connectable = Object.create(source, connectableObservableDescriptor);
        connectable.source = source;
        connectable.subjectFactory = subjectFactory;
        return connectable;
    };
}
export class MulticastOperator {
    constructor(subjectFactory, selector) {
        this.subjectFactory = subjectFactory;
        this.selector = selector;
    }
    call(subscriber, source) {
        const { selector } = this;
        const subject = this.subjectFactory();
        const subscription = selector(subject).subscribe(subscriber);
        subscription.add(source.subscribe(subject));
        return subscription;
    }
}
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