mine/node_modules/eslint-webpack-plugin/dist/getESLint.js

"use strict";

const {
  cpus
} = require('os');

const {
  Worker: JestWorker
} = require('jest-worker');

const {
  getESLintOptions
} = require('./options');

const {
  jsonStringifyReplacerSortKeys
} = require('./utils');
/** @type {{[key: string]: any}} */


const cache = {};
/** @typedef {import('eslint').ESLint} ESLint */

/** @typedef {import('eslint').ESLint.LintResult} LintResult */

/** @typedef {import('./options').Options} Options */

/** @typedef {() => Promise<void>} AsyncTask */

/** @typedef {(files: string|string[]) => Promise<LintResult[]>} LintTask */

/** @typedef {{threads: number, ESLint: ESLint, eslint: ESLint, lintFiles: LintTask, cleanup: AsyncTask}} Linter */

/** @typedef {JestWorker & {lintFiles: LintTask}} Worker */

/**
 * @param {Options} options
 * @returns {Linter}
 */

function loadESLint(options) {
  const {
    eslintPath
  } = options;

  const {
    ESLint
  } = require(eslintPath || 'eslint'); // Filter out loader options before passing the options to ESLint.


  const eslint = new ESLint(getESLintOptions(options));
  return {
    threads: 1,
    ESLint,
    eslint,
    lintFiles: async files => {
      const results = await eslint.lintFiles(files); // istanbul ignore else

      if (options.fix) {
        await ESLint.outputFixes(results);
      }

      return results;
    },
    // no-op for non-threaded
    cleanup: async () => {}
  };
}
/**
 * @param {string|undefined} key
 * @param {number} poolSize
 * @param {Options} options
 * @returns {Linter}
 */


function loadESLintThreaded(key, poolSize, options) {
  const cacheKey = getCacheKey(key, options);
  const {
    eslintPath = 'eslint'
  } = options;

  const source = require.resolve('./worker');

  const workerOptions = {
    enableWorkerThreads: true,
    numWorkers: poolSize,
    setupArgs: [{
      eslintPath,
      eslintOptions: getESLintOptions(options)
    }]
  };
  const local = loadESLint(options);
  let worker =
  /** @type {Worker?} */
  new JestWorker(source, workerOptions);
  /** @type {Linter} */

  const context = { ...local,
    threads: poolSize,
    lintFiles: async files => worker && (await worker.lintFiles(files)) ||
    /* istanbul ignore next */
    [],
    cleanup: async () => {
      cache[cacheKey] = local;

      context.lintFiles = files => local.lintFiles(files);

      if (worker) {
        worker.end();
        worker = null;
      }
    }
  };
  return context;
}
/**
 * @param {string|undefined} key
 * @param {Options} options
 * @returns {Linter}
 */


function getESLint(key, {
  threads,
  ...options
}) {
  const max = typeof threads !== 'number' ? threads ? cpus().length - 1 : 1 :
  /* istanbul ignore next */
  threads;
  const cacheKey = getCacheKey(key, {
    threads,
    ...options
  });

  if (!cache[cacheKey]) {
    cache[cacheKey] = max > 1 ? loadESLintThreaded(key, max, options) : loadESLint(options);
  }

  return cache[cacheKey];
}
/**
 * @param {string|undefined} key
 * @param {Options} options
 * @returns {string}
 */


function getCacheKey(key, options) {
  return JSON.stringify({
    key,
    options
  }, jsonStringifyReplacerSortKeys);
}

module.exports = {
  loadESLint,
  loadESLintThreaded,
  getESLint
};