@nx/devkit/src/utils/async-iterable/combine-async-iterables.js

The Nx Devkit is used to customize Nx for different technologies and use cases. It contains many utility functions for reading and writing files, updating configuration, working with Abstract Syntax Trees(ASTs), and more. Learn more about [extending Nx by

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.combineAsyncIterables = combineAsyncIterables;
async function* combineAsyncIterables(..._iterators) {
    // Convert iterables into iterators with next, return, throws methods.
    // If it's already an iterator, keep it.
    const iterators = _iterators.map((it) => {
        if (typeof it['next'] === 'function') {
            return it;
        }
        else {
            return (async function* wrapped() {
                for await (const val of it) {
                    yield val;
                }
            })();
        }
    });
    let [options] = iterators;
    if (typeof options.next === 'function') {
        options = Object.create(null);
    }
    else {
        iterators.shift();
    }
    const getNextAsyncIteratorValue = getNextAsyncIteratorFactory(options);
    const asyncIteratorsValues = new Map(iterators.map((it, idx) => [idx, getNextAsyncIteratorValue(it, idx)]));
    try {
        do {
            const { iterator, index } = await Promise.race(asyncIteratorsValues.values());
            if (iterator.done) {
                asyncIteratorsValues.delete(index);
            }
            else {
                yield iterator.value;
                asyncIteratorsValues.set(index, getNextAsyncIteratorValue(iterators[index], index));
            }
        } while (asyncIteratorsValues.size > 0);
    }
    finally {
        for (const [index, iterator] of asyncIteratorsValues.entries())
            if (iterator?.['return'] !== null)
                iterator['return']?.();
    }
}
function getNextAsyncIteratorFactory(options) {
    return async (asyncIterator, index) => {
        try {
            const iterator = await asyncIterator.next();
            return { index, iterator };
        }
        catch (err) {
            if (options.errorCallback) {
                options.errorCallback(err, index);
            }
            return Promise.reject(err);
        }
    };
}