material-motion/dist/observables/IndefiniteSubject.js

Makes it easy to add rich, interactive motion to your application.

/** @license
 *  Copyright 2016 - present The Material Motion Authors. All Rights Reserved.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may not
 *  use this file except in compliance with the License. You may obtain a copy
 *  of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 *  License for the specific language governing permissions and limitations
 *  under the License.
 */
import { isObserver, } from '../typeGuards';
import { MemorylessIndefiniteSubject, } from './MemorylessIndefiniteSubject';
/**
 * An `IndefiniteSubject` is both an `Observer` and an `Observable`.  Whenever
 * it receives a value on `next`, it forwards that value to any subscribed
 * observers.
 *
 * `IndefiniteSubject` also remembers the most recent emission and passes it to
 * any new subscriber.
 */
export class IndefiniteSubject extends MemorylessIndefiniteSubject {
    constructor() {
        super(...arguments);
        this._hasStarted = false;
    }
    /**
     * Passes the supplied value to any currently-subscribed observers.  If an
     * observer `subscribe`s before `next` is called again, it will immediately
     * receive `value`.
     */
    next(value) {
        this._hasStarted = true;
        this._lastEmission = value;
        super.next(value);
    }
    /**
     * `subscribe` accepts either a function or an object with a next method.
     * `subject.next` will forward any value it receives to the function or method
     * provided here.
     *
     * Call the returned `unsubscribe` method to stop receiving values on this
     * particular observer.
     */
    subscribe(observerOrNext) {
        const subscription = super.subscribe(observerOrNext);
        if (this._hasStarted) {
            isObserver(observerOrNext)
                ? observerOrNext.next(this._lastEmission)
                : observerOrNext(this._lastEmission);
        }
        return subscription;
    }
}
export default IndefiniteSubject;
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