@reactivex/rxjs/dist/es6/operator/race.js

Reactive Extensions for modern JavaScript

import { isArray } from '../util/isArray';
import { ArrayObservable } from '../observable/ArrayObservable';
import { OuterSubscriber } from '../OuterSubscriber';
import { subscribeToResult } from '../util/subscribeToResult';
/**
 * Returns an Observable that mirrors the first source Observable to emit an item
 * from the combination of this Observable and supplied Observables
 * @param {...Observables} ...observables sources used to race for which Observable emits first.
 * @return {Observable} an Observable that mirrors the output of the first Observable to emit an item.
 * @method race
 * @owner Observable
 */
export function race(...observables) {
    // if the only argument is an array, it was most likely called with
    // `pair([obs1, obs2, ...])`
    if (observables.length === 1 && isArray(observables[0])) {
        observables = observables[0];
    }
    observables.unshift(this);
    return raceStatic.apply(this, observables);
}
export function raceStatic(...observables) {
    // if the only argument is an array, it was most likely called with
    // `pair([obs1, obs2, ...])`
    if (observables.length === 1) {
        if (isArray(observables[0])) {
            observables = observables[0];
        }
        else {
            return observables[0];
        }
    }
    return new ArrayObservable(observables).lift(new RaceOperator());
}
export class RaceOperator {
    call(subscriber, source) {
        return source._subscribe(new RaceSubscriber(subscriber));
    }
}
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @ignore
 * @extends {Ignored}
 */
export class RaceSubscriber extends OuterSubscriber {
    constructor(destination) {
        super(destination);
        this.hasFirst = false;
        this.observables = [];
        this.subscriptions = [];
    }
    _next(observable) {
        this.observables.push(observable);
    }
    _complete() {
        const observables = this.observables;
        const len = observables.length;
        if (len === 0) {
            this.destination.complete();
        }
        else {
            for (let i = 0; i < len; i++) {
                let observable = observables[i];
                let subscription = subscribeToResult(this, observable, observable, i);
                this.subscriptions.push(subscription);
                this.add(subscription);
            }
            this.observables = null;
        }
    }
    notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) {
        if (!this.hasFirst) {
            this.hasFirst = true;
            for (let i = 0; i < this.subscriptions.length; i++) {
                if (i !== outerIndex) {
                    let subscription = this.subscriptions[i];
                    subscription.unsubscribe();
                    this.remove(subscription);
                }
            }
            this.subscriptions = null;
        }
        this.destination.next(innerValue);
    }
}
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