axax/esnext/combineLatest.js

A library of async iterator extensions for JavaScript including ```map```, ```reduce```, ```filter```, ```flatMap```, ```pipe``` and [more](https://github.com/jamiemccrindle/axax/blob/master/docs/API.md#functions).

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const subject_1 = require("./subject");
const toCallbacks_1 = require("./toCallbacks");
/**
 * Combines iterables
 *
 * @param sources the iterables to combine
 */
function combineLatest(...sources) {
    const results = new Array(sources.length);
    const resultsAvailable = new Array(sources.length).fill(false);
    const subject = new subject_1.Subject();
    let done = false;
    subject.finally(() => {
        done = true;
    });
    let doneCount = 0;
    sources.map((source, index) => {
        return toCallbacks_1.toCallbacks(result => {
            if (result.done) {
                doneCount += 1;
                if (doneCount >= sources.length) {
                    done = true;
                    return subject.callback({ done: true, value: [] });
                }
            }
            if (done) {
                throw new toCallbacks_1.StopError();
            }
            else if (!result.done) {
                results[index] = result.value;
                resultsAvailable[index] = true;
                if (resultsAvailable.every(value => value)) {
                    return subject.callback({ done: false, value: Array.from(results) });
                }
                else {
                    return Promise.resolve();
                }
            }
            else {
                return Promise.resolve();
            }
        })(source);
    });
    return subject.iterator;
}
exports.combineLatest = combineLatest;