"use strict";
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/** @typedef {import("webpack").Compilation["inputFileSystem"] } InputFileSystem */
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/** @typedef {import("fs").Stats } Stats */
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/**
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* @param {InputFileSystem} inputFileSystem
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* @param {string} path
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* @return {Promise<undefined | Stats>}
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*/
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function stat(inputFileSystem, path) {
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return new Promise((resolve, reject) => {
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inputFileSystem.stat(path,
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/**
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* @param {null | undefined | NodeJS.ErrnoException} err
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* @param {undefined | Stats} stats
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*/
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// @ts-ignore
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(err, stats) => {
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if (err) {
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reject(err);
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return;
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}
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resolve(stats);
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});
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});
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}
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/**
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* @param {InputFileSystem} inputFileSystem
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* @param {string} path
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* @return {Promise<string | Buffer>}
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*/
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function readFile(inputFileSystem, path) {
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return new Promise((resolve, reject) => {
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inputFileSystem.readFile(path,
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/**
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* @param {null | undefined | NodeJS.ErrnoException} err
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* @param {undefined | string | Buffer} data
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*/
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(err, data) => {
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if (err) {
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reject(err);
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return;
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}
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resolve(/** @type {string | Buffer} */data);
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});
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});
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}
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const notSettled = Symbol(`not-settled`);
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/**
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* @template T
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* @typedef {() => Promise<T>} Task
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*/
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/**
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* Run tasks with limited concurrency.
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* @template T
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* @param {number} limit - Limit of tasks that run at once.
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* @param {Task<T>[]} tasks - List of tasks to run.
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* @returns {Promise<T[]>} A promise that fulfills to an array of the results
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*/
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function throttleAll(limit, tasks) {
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if (!Number.isInteger(limit) || limit < 1) {
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throw new TypeError(`Expected \`limit\` to be a finite number > 0, got \`${limit}\` (${typeof limit})`);
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}
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if (!Array.isArray(tasks) || !tasks.every(task => typeof task === `function`)) {
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throw new TypeError(`Expected \`tasks\` to be a list of functions returning a promise`);
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}
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return new Promise((resolve, reject) => {
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const result = Array(tasks.length).fill(notSettled);
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const entries = tasks.entries();
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const next = () => {
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const {
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done,
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value
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} = entries.next();
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if (done) {
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const isLast = !result.includes(notSettled);
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if (isLast) {
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resolve(/** @type{T[]} **/result);
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}
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return;
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}
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const [index, task] = value;
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/**
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* @param {T} x
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*/
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const onFulfilled = x => {
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result[index] = x;
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next();
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};
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task().then(onFulfilled, reject);
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};
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Array(limit).fill(0).forEach(next);
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});
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}
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/**
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* @template T
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* @param fn {(function(): any) | undefined}
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* @returns {function(): T}
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*/
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function memoize(fn) {
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let cache = false;
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/** @type {T} */
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let result;
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return () => {
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if (cache) {
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return result;
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}
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result = /** @type {function(): any} */fn();
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cache = true;
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// Allow to clean up memory for fn
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// and all dependent resources
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// eslint-disable-next-line no-undefined, no-param-reassign
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fn = undefined;
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return result;
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};
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}
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module.exports = {
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stat,
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readFile,
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throttleAll,
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memoize
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};
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