Elep

'use strict';
const pTry = require('p-try');

const pLimit = concurrency => {
	if (!((Number.isInteger(concurrency) || concurrency === Infinity) && concurrency > 0)) {
		return Promise.reject(new TypeError('Expected `concurrency` to be a number from 1 and up'));
	}

const queue = [];
	let activeCount = 0;

const next = () => {
		activeCount--;

if (queue.length > 0) {
			queue.shift()();
		}
	};

const run = (fn, resolve, ...args) => {
		activeCount++;

const result = pTry(fn, ...args);

resolve(result);

result.then(next, next);
	};

const enqueue = (fn, resolve, ...args) => {
		if (activeCount < concurrency) {
			run(fn, resolve, ...args);
		} else {
			queue.push(run.bind(null, fn, resolve, ...args));
		}
	};

return generator;
};

module.exports = pLimit;
module.exports.default = pLimit;