ix/asynciterable/combinelatest.js

The Interactive Extensions for JavaScript

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.combineLatest = exports.CombineLatestAsyncIterable = void 0;
const tslib_1 = require("tslib");
const asynciterablex_js_1 = require("./asynciterablex.js");
const identity_js_1 = require("../util/identity.js");
const withabort_js_1 = require("./operators/withabort.js");
const aborterror_js_1 = require("../aborterror.js");
const safeRace_js_1 = require("../util/safeRace.js");
// eslint-disable-next-line @typescript-eslint/no-empty-function
const NEVER_PROMISE = new Promise(() => { });
function wrapPromiseWithIndex(promise, index) {
    return promise.then((value) => ({ value, index }));
}
/** @ignore */
class CombineLatestAsyncIterable extends asynciterablex_js_1.AsyncIterableX {
    constructor(sources) {
        super();
        this._sources = sources;
    }
    [Symbol.asyncIterator](signal) {
        return tslib_1.__asyncGenerator(this, arguments, function* _a() {
            (0, aborterror_js_1.throwIfAborted)(signal);
            const length = this._sources.length;
            const iterators = new Array(length);
            const nexts = new Array(length);
            let hasValueAll = false;
            const values = new Array(length);
            const hasValues = new Array(length);
            let active = length;
            hasValues.fill(false);
            for (let i = 0; i < length; i++) {
                const iterator = (0, withabort_js_1.wrapWithAbort)(this._sources[i], signal)[Symbol.asyncIterator]();
                iterators[i] = iterator;
                nexts[i] = wrapPromiseWithIndex(iterator.next(), i);
            }
            while (active > 0) {
                const next = (0, safeRace_js_1.safeRace)(nexts);
                const { value: { value: value$, done: done$ }, index, } = yield tslib_1.__await(next);
                if (done$) {
                    nexts[index] = NEVER_PROMISE;
                    active--;
                }
                else {
                    values[index] = value$;
                    hasValues[index] = true;
                    const iterator$ = iterators[index];
                    nexts[index] = wrapPromiseWithIndex(iterator$.next(), index);
                    if (hasValueAll || (hasValueAll = hasValues.every(identity_js_1.identity))) {
                        yield yield tslib_1.__await(values);
                    }
                }
            }
        });
    }
}
exports.CombineLatestAsyncIterable = CombineLatestAsyncIterable;
function combineLatest(...sources) {
    return new CombineLatestAsyncIterable(sources);
}
exports.combineLatest = combineLatest;

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