combineLatest.js 2.82 KB
import { isScheduler } from '../util/isScheduler';
import { isArray } from '../util/isArray';
import { OuterSubscriber } from '../OuterSubscriber';
import { subscribeToResult } from '../util/subscribeToResult';
import { fromArray } from './fromArray';
const NONE = {};
export function combineLatest(...observables) {
    let resultSelector = undefined;
    let scheduler = undefined;
    if (isScheduler(observables[observables.length - 1])) {
        scheduler = observables.pop();
    }
    if (typeof observables[observables.length - 1] === 'function') {
        resultSelector = observables.pop();
    }
    if (observables.length === 1 && isArray(observables[0])) {
        observables = observables[0];
    }
    return fromArray(observables, scheduler).lift(new CombineLatestOperator(resultSelector));
}
export class CombineLatestOperator {
    constructor(resultSelector) {
        this.resultSelector = resultSelector;
    }
    call(subscriber, source) {
        return source.subscribe(new CombineLatestSubscriber(subscriber, this.resultSelector));
    }
}
export class CombineLatestSubscriber extends OuterSubscriber {
    constructor(destination, resultSelector) {
        super(destination);
        this.resultSelector = resultSelector;
        this.active = 0;
        this.values = [];
        this.observables = [];
    }
    _next(observable) {
        this.values.push(NONE);
        this.observables.push(observable);
    }
    _complete() {
        const observables = this.observables;
        const len = observables.length;
        if (len === 0) {
            this.destination.complete();
        }
        else {
            this.active = len;
            this.toRespond = len;
            for (let i = 0; i < len; i++) {
                const observable = observables[i];
                this.add(subscribeToResult(this, observable, undefined, i));
            }
        }
    }
    notifyComplete(unused) {
        if ((this.active -= 1) === 0) {
            this.destination.complete();
        }
    }
    notifyNext(_outerValue, innerValue, outerIndex) {
        const values = this.values;
        const oldVal = values[outerIndex];
        const toRespond = !this.toRespond
            ? 0
            : oldVal === NONE ? --this.toRespond : this.toRespond;
        values[outerIndex] = innerValue;
        if (toRespond === 0) {
            if (this.resultSelector) {
                this._tryResultSelector(values);
            }
            else {
                this.destination.next(values.slice());
            }
        }
    }
    _tryResultSelector(values) {
        let result;
        try {
            result = this.resultSelector.apply(this, values);
        }
        catch (err) {
            this.destination.error(err);
            return;
        }
        this.destination.next(result);
    }
}
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