code:
/**
 * @fileoverview `CascadingConfigArrayFactory` class.
 *
 * `CascadingConfigArrayFactory` class has a responsibility:
 *
 * 1. Handles cascading of config files.
 *
 * It provides two methods:
 *
 * - `getConfigArrayForFile(filePath)`
 *     Get the corresponded configuration of a given file. This method doesn't
 *     throw even if the given file didn't exist.
 * - `clearCache()`
 *     Clear the internal cache. You have to call this method when
 *     `additionalPluginPool` was updated if `baseConfig` or `cliConfig` depends
 *     on the additional plugins. (`CLIEngine#addPlugin()` method calls this.)
 *
 * @author Toru Nagashima <https://github.com/mysticatea>
 */

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

import debugOrig from "debug";
import os from "os";
import path from "path";

import { ConfigArrayFactory } from "./config-array-factory.js";
import {
    ConfigArray,
    ConfigDependency,
    IgnorePattern
} from "./config-array/index.js";
import ConfigValidator from "./shared/config-validator.js";
import { emitDeprecationWarning } from "./shared/deprecation-warnings.js";

const debug = debugOrig("eslintrc:cascading-config-array-factory");

//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------

// Define types for VSCode IntelliSense.
/** @typedef {import("./shared/types").ConfigData} ConfigData */
/** @typedef {import("./shared/types").Parser} Parser */
/** @typedef {import("./shared/types").Plugin} Plugin */
/** @typedef {import("./shared/types").Rule} Rule */
/** @typedef {ReturnType<ConfigArrayFactory["create"]>} ConfigArray */

/**
 * @typedef {Object} CascadingConfigArrayFactoryOptions
 * @property {Map<string,Plugin>} [additionalPluginPool] The map for additional plugins.
 * @property {ConfigData} [baseConfig] The config by `baseConfig` option.
 * @property {ConfigData} [cliConfig] The config by CLI options (`--env`, `--global`, `--ignore-pattern`, `--parser`, `--parser-options`, `--plugin`, and `--rule`). CLI options overwrite the setting in config files.
 * @property {string} [cwd] The base directory to start lookup.
 * @property {string} [ignorePath] The path to the alternative file of `.eslintignore`.
 * @property {string[]} [rulePaths] The value of `--rulesdir` option.
 * @property {string} [specificConfigPath] The value of `--config` option.
 * @property {boolean} [useEslintrc] if `false` then it doesn't load config files.
 * @property {Function} loadRules The function to use to load rules.
 * @property {Map<string,Rule>} builtInRules The rules that are built in to ESLint.
 * @property {Object} [resolver=ModuleResolver] The module resolver object.
 * @property {string} eslintAllPath The path to the definitions for eslint:all.
 * @property {Function} getEslintAllConfig Returns the config data for eslint:all.
 * @property {string} eslintRecommendedPath The path to the definitions for eslint:recommended.
 * @property {Function} getEslintRecommendedConfig Returns the config data for eslint:recommended.
 */

/**
 * @typedef {Object} CascadingConfigArrayFactoryInternalSlots
 * @property {ConfigArray} baseConfigArray The config array of `baseConfig` option.
 * @property {ConfigData} baseConfigData The config data of `baseConfig` option. This is used to reset `baseConfigArray`.
 * @property {ConfigArray} cliConfigArray The config array of CLI options.
 * @property {ConfigData} cliConfigData The config data of CLI options. This is used to reset `cliConfigArray`.
 * @property {ConfigArrayFactory} configArrayFactory The factory for config arrays.
 * @property {Map<string, ConfigArray>} configCache The cache from directory paths to config arrays.
 * @property {string} cwd The base directory to start lookup.
 * @property {WeakMap<ConfigArray, ConfigArray>} finalizeCache The cache from config arrays to finalized config arrays.
 * @property {string} [ignorePath] The path to the alternative file of `.eslintignore`.
 * @property {string[]|null} rulePaths The value of `--rulesdir` option. This is used to reset `baseConfigArray`.
 * @property {string|null} specificConfigPath The value of `--config` option. This is used to reset `cliConfigArray`.
 * @property {boolean} useEslintrc if `false` then it doesn't load config files.
 * @property {Function} loadRules The function to use to load rules.
 * @property {Map<string,Rule>} builtInRules The rules that are built in to ESLint.
 * @property {Object} [resolver=ModuleResolver] The module resolver object.
 * @property {string} eslintAllPath The path to the definitions for eslint:all.
 * @property {Function} getEslintAllConfig Returns the config data for eslint:all.
 * @property {string} eslintRecommendedPath The path to the definitions for eslint:recommended.
 * @property {Function} getEslintRecommendedConfig Returns the config data for eslint:recommended.
 */

/** @type {WeakMap<CascadingConfigArrayFactory, CascadingConfigArrayFactoryInternalSlots>} */
const internalSlotsMap = new WeakMap();

/**
 * Create the config array from `baseConfig` and `rulePaths`.
 * @param {CascadingConfigArrayFactoryInternalSlots} slots The slots.
 * @returns {ConfigArray} The config array of the base configs.
 */
function createBaseConfigArray({
    configArrayFactory,
    baseConfigData,
    rulePaths,
    cwd,
    loadRules
}) {
    const baseConfigArray = configArrayFactory.create(
        baseConfigData,
        { name: "BaseConfig" }
    );

    /*
     * Create the config array element for the default ignore patterns.
     * This element has `ignorePattern` property that ignores the default
     * patterns in the current working directory.
     */
    baseConfigArray.unshift(configArrayFactory.create(
        { ignorePatterns: IgnorePattern.DefaultPatterns },
        { name: "DefaultIgnorePattern" }
    )[0]);

    /*
     * Load rules `--rulesdir` option as a pseudo plugin.
     * Use a pseudo plugin to define rules of `--rulesdir`, so we can validate
     * the rule's options with only information in the config array.
     */
    if (rulePaths && rulePaths.length > 0) {
        baseConfigArray.push({
            type: "config",
            name: "--rulesdir",
            filePath: "",
            plugins: {
                "": new ConfigDependency({
                    definition: {
                        rules: rulePaths.reduce(
                            (map, rulesPath) => Object.assign(
                                map,
                                loadRules(rulesPath, cwd)
                            ),
                            {}
                        )
                    },
                    filePath: "",
                    id: "",
                    importerName: "--rulesdir",
                    importerPath: ""
                })
            }
        });
    }

    return baseConfigArray;
}

/**
 * Create the config array from CLI options.
 * @param {CascadingConfigArrayFactoryInternalSlots} slots The slots.
 * @returns {ConfigArray} The config array of the base configs.
 */
function createCLIConfigArray({
    cliConfigData,
    configArrayFactory,
    cwd,
    ignorePath,
    specificConfigPath
}) {
    const cliConfigArray = configArrayFactory.create(
        cliConfigData,
        { name: "CLIOptions" }
    );

    cliConfigArray.unshift(
        ...(ignorePath
            ? configArrayFactory.loadESLintIgnore(ignorePath)
            : configArrayFactory.loadDefaultESLintIgnore())
    );

    if (specificConfigPath) {
        cliConfigArray.unshift(
            ...configArrayFactory.loadFile(
                specificConfigPath,
                { name: "--config", basePath: cwd }
            )
        );
    }

    return cliConfigArray;
}

/**
 * The error type when there are files matched by a glob, but all of them have been ignored.
 */
class ConfigurationNotFoundError extends Error {

    // eslint-disable-next-line jsdoc/require-description
    /**
     * @param {string} directoryPath The directory path.
     */
    constructor(directoryPath) {
        super(`No ESLint configuration found in ${directoryPath}.`);
        this.messageTemplate = "no-config-found";
        this.messageData = { directoryPath };
    }
}

/**
 * This class provides the functionality that enumerates every file which is
 * matched by given glob patterns and that configuration.
 */
class CascadingConfigArrayFactory {

    /**
     * Initialize this enumerator.
     * @param {CascadingConfigArrayFactoryOptions} options The options.
     */
    constructor({
        additionalPluginPool = new Map(),
        baseConfig: baseConfigData = null,
        cliConfig: cliConfigData = null,
        cwd = process.cwd(),
        ignorePath,
        resolvePluginsRelativeTo,
        rulePaths = [],
        specificConfigPath = null,
        useEslintrc = true,
        builtInRules = new Map(),
        loadRules,
        resolver,
        eslintRecommendedPath,
        getEslintRecommendedConfig,
        eslintAllPath,
        getEslintAllConfig
    } = {}) {
        const configArrayFactory = new ConfigArrayFactory({
            additionalPluginPool,
            cwd,
            resolvePluginsRelativeTo,
            builtInRules,
            resolver,
            eslintRecommendedPath,
            getEslintRecommendedConfig,
            eslintAllPath,
            getEslintAllConfig
        });

        internalSlotsMap.set(this, {
            baseConfigArray: createBaseConfigArray({
                baseConfigData,
                configArrayFactory,
                cwd,
                rulePaths,
                loadRules
            }),
            baseConfigData,
            cliConfigArray: createCLIConfigArray({
                cliConfigData,
                configArrayFactory,
                cwd,
                ignorePath,
                specificConfigPath
            }),
            cliConfigData,
            configArrayFactory,
            configCache: new Map(),
            cwd,
            finalizeCache: new WeakMap(),
            ignorePath,
            rulePaths,
            specificConfigPath,
            useEslintrc,
            builtInRules,
            loadRules
        });
    }

    /**
     * The path to the current working directory.
     * This is used by tests.
     * @type {string}
     */
    get cwd() {
        const { cwd } = internalSlotsMap.get(this);

        return cwd;
    }

    /**
     * Get the config array of a given file.
     * If `filePath` was not given, it returns the config which contains only
     * `baseConfigData` and `cliConfigData`.
     * @param {string} [filePath] The file path to a file.
     * @param {Object} [options] The options.
     * @param {boolean} [options.ignoreNotFoundError] If `true` then it doesn't throw `ConfigurationNotFoundError`.
     * @returns {ConfigArray} The config array of the file.
     */
    getConfigArrayForFile(filePath, { ignoreNotFoundError = false } = {}) {
        const {
            baseConfigArray,
            cliConfigArray,
            cwd
        } = internalSlotsMap.get(this);

        if (!filePath) {
            return new ConfigArray(...baseConfigArray, ...cliConfigArray);
        }

        const directoryPath = path.dirname(path.resolve(cwd, filePath));

        debug(`Load config files for ${directoryPath}.`);

        return this._finalizeConfigArray(
            this._loadConfigInAncestors(directoryPath),
            directoryPath,
            ignoreNotFoundError
        );
    }

    /**
     * Set the config data to override all configs.
     * Require to call `clearCache()` method after this method is called.
     * @param {ConfigData} configData The config data to override all configs.
     * @returns {void}
     */
    setOverrideConfig(configData) {
        const slots = internalSlotsMap.get(this);

        slots.cliConfigData = configData;
    }

    /**
     * Clear config cache.
     * @returns {void}
     */
    clearCache() {
        const slots = internalSlotsMap.get(this);

        slots.baseConfigArray = createBaseConfigArray(slots);
        slots.cliConfigArray = createCLIConfigArray(slots);
        slots.configCache.clear();
    }

    /**
     * Load and normalize config files from the ancestor directories.
     * @param {string} directoryPath The path to a leaf directory.
     * @param {boolean} configsExistInSubdirs `true` if configurations exist in subdirectories.
     * @returns {ConfigArray} The loaded config.
     * @private
     */
    _loadConfigInAncestors(directoryPath, configsExistInSubdirs = false) {
        const {
            baseConfigArray,
            configArrayFactory,
            configCache,
            cwd,
            useEslintrc
        } = internalSlotsMap.get(this);

        if (!useEslintrc) {
            return baseConfigArray;
        }

        let configArray = configCache.get(directoryPath);

        // Hit cache.
        if (configArray) {
            debug(`Cache hit: ${directoryPath}.`);
            return configArray;
        }
        debug(`No cache found: ${directoryPath}.`);

        const homePath = os.homedir();

        // Consider this is root.
        if (directoryPath === homePath && cwd !== homePath) {
            debug("Stop traversing because of considered root.");
            if (configsExistInSubdirs) {
                const filePath = ConfigArrayFactory.getPathToConfigFileInDirectory(directoryPath);

                if (filePath) {
                    emitDeprecationWarning(
                        filePath,
                        "ESLINT_PERSONAL_CONFIG_SUPPRESS"
                    );
                }
            }
            return this._cacheConfig(directoryPath, baseConfigArray);
        }

        // Load the config on this directory.
        try {
            configArray = configArrayFactory.loadInDirectory(directoryPath);
        } catch (error) {
            /* istanbul ignore next */
            if (error.code === "EACCES") {
                debug("Stop traversing because of 'EACCES' error.");
                return this._cacheConfig(directoryPath, baseConfigArray);
            }
            throw error;
        }

        if (configArray.length > 0 && configArray.isRoot()) {
            debug("Stop traversing because of 'root:true'.");
            configArray.unshift(...baseConfigArray);
            return this._cacheConfig(directoryPath, configArray);
        }

        // Load from the ancestors and merge it.
        const parentPath = path.dirname(directoryPath);
        const parentConfigArray = parentPath && parentPath !== directoryPath
            ? this._loadConfigInAncestors(
                parentPath,
                configsExistInSubdirs || configArray.length > 0
            )
            : baseConfigArray;

        if (configArray.length > 0) {
            configArray.unshift(...parentConfigArray);
        } else {
            configArray = parentConfigArray;
        }

        // Cache and return.
        return this._cacheConfig(directoryPath, configArray);
    }

    /**
     * Freeze and cache a given config.
     * @param {string} directoryPath The path to a directory as a cache key.
     * @param {ConfigArray} configArray The config array as a cache value.
     * @returns {ConfigArray} The `configArray` (frozen).
     */
    _cacheConfig(directoryPath, configArray) {
        const { configCache } = internalSlotsMap.get(this);

        Object.freeze(configArray);
        configCache.set(directoryPath, configArray);

        return configArray;
    }

    /**
     * Finalize a given config array.
     * Concatenate `--config` and other CLI options.
     * @param {ConfigArray} configArray The parent config array.
     * @param {string} directoryPath The path to the leaf directory to find config files.
     * @param {boolean} ignoreNotFoundError If `true` then it doesn't throw `ConfigurationNotFoundError`.
     * @returns {ConfigArray} The loaded config.
     * @private
     */
    _finalizeConfigArray(configArray, directoryPath, ignoreNotFoundError) {
        const {
            cliConfigArray,
            configArrayFactory,
            finalizeCache,
            useEslintrc,
            builtInRules
        } = internalSlotsMap.get(this);

        let finalConfigArray = finalizeCache.get(configArray);

        if (!finalConfigArray) {
            finalConfigArray = configArray;

            // Load the personal config if there are no regular config files.
            if (
                useEslintrc &&
                configArray.every(c => !c.filePath) &&
                cliConfigArray.every(c => !c.filePath) // `--config` option can be a file.
            ) {
                const homePath = os.homedir();

                debug("Loading the config file of the home directory:", homePath);

                const personalConfigArray = configArrayFactory.loadInDirectory(
                    homePath,
                    { name: "PersonalConfig" }
                );

                if (
                    personalConfigArray.length > 0 &&
                    !directoryPath.startsWith(homePath)
                ) {
                    const lastElement =
                        personalConfigArray[personalConfigArray.length - 1];

                    emitDeprecationWarning(
                        lastElement.filePath,
                        "ESLINT_PERSONAL_CONFIG_LOAD"
                    );
                }

                finalConfigArray = finalConfigArray.concat(personalConfigArray);
            }

            // Apply CLI options.
            if (cliConfigArray.length > 0) {
                finalConfigArray = finalConfigArray.concat(cliConfigArray);
            }

            // Validate rule settings and environments.
            const validator = new ConfigValidator({
                builtInRules
            });

            validator.validateConfigArray(finalConfigArray);

            // Cache it.
            Object.freeze(finalConfigArray);
            finalizeCache.set(configArray, finalConfigArray);

            debug(
                "Configuration was determined: %o on %s",
                finalConfigArray,
                directoryPath
            );
        }

        // At least one element (the default ignore patterns) exists.
        if (!ignoreNotFoundError && useEslintrc && finalConfigArray.length <= 1) {
            throw new ConfigurationNotFoundError(directoryPath);
        }

        return finalConfigArray;
    }
}

//------------------------------------------------------------------------------
// Public Interface
//------------------------------------------------------------------------------

export { CascadingConfigArrayFactory };

license: mit


code:
/**
 * @fileoverview The factory of `ConfigArray` objects.
 *
 * This class provides methods to create `ConfigArray` instance.
 *
 * - `create(configData, options)`
 *     Create a `ConfigArray` instance from a config data. This is to handle CLI
 *     options except `--config`.
 * - `loadFile(filePath, options)`
 *     Create a `ConfigArray` instance from a config file. This is to handle
 *     `--config` option. If the file was not found, throws the following error:
 *      - If the filename was `*.js`, a `MODULE_NOT_FOUND` error.
 *      - If the filename was `package.json`, an IO error or an
 *        `ESLINT_CONFIG_FIELD_NOT_FOUND` error.
 *      - Otherwise, an IO error such as `ENOENT`.
 * - `loadInDirectory(directoryPath, options)`
 *     Create a `ConfigArray` instance from a config file which is on a given
 *     directory. This tries to load `.eslintrc.*` or `package.json`. If not
 *     found, returns an empty `ConfigArray`.
 * - `loadESLintIgnore(filePath)`
 *     Create a `ConfigArray` instance from a config file that is `.eslintignore`
 *     format. This is to handle `--ignore-path` option.
 * - `loadDefaultESLintIgnore()`
 *     Create a `ConfigArray` instance from `.eslintignore` or `package.json` in
 *     the current working directory.
 *
 * `ConfigArrayFactory` class has the responsibility that loads configuration
 * files, including loading `extends`, `parser`, and `plugins`. The created
 * `ConfigArray` instance has the loaded `extends`, `parser`, and `plugins`.
 *
 * But this class doesn't handle cascading. `CascadingConfigArrayFactory` class
 * handles cascading and hierarchy.
 *
 * @author Toru Nagashima <https://github.com/mysticatea>
 */

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

import debugOrig from "debug";
import fs from "fs";
import importFresh from "import-fresh";
import { createRequire } from "module";
import path from "path";
import stripComments from "strip-json-comments";

import {
    ConfigArray,
    ConfigDependency,
    IgnorePattern,
    OverrideTester
} from "./config-array/index.js";
import ConfigValidator from "./shared/config-validator.js";
import * as naming from "./shared/naming.js";
import * as ModuleResolver from "./shared/relative-module-resolver.js";

const require = createRequire(import.meta.url);

const debug = debugOrig("eslintrc:config-array-factory");

//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------

const configFilenames = [
    ".eslintrc.js",
    ".eslintrc.cjs",
    ".eslintrc.yaml",
    ".eslintrc.yml",
    ".eslintrc.json",
    ".eslintrc",
    "package.json"
];

// Define types for VSCode IntelliSense.
/** @typedef {import("./shared/types").ConfigData} ConfigData */
/** @typedef {import("./shared/types").OverrideConfigData} OverrideConfigData */
/** @typedef {import("./shared/types").Parser} Parser */
/** @typedef {import("./shared/types").Plugin} Plugin */
/** @typedef {import("./shared/types").Rule} Rule */
/** @typedef {import("./config-array/config-dependency").DependentParser} DependentParser */
/** @typedef {import("./config-array/config-dependency").DependentPlugin} DependentPlugin */
/** @typedef {ConfigArray[0]} ConfigArrayElement */

/**
 * @typedef {Object} ConfigArrayFactoryOptions
 * @property {Map<string,Plugin>} [additionalPluginPool] The map for additional plugins.
 * @property {string} [cwd] The path to the current working directory.
 * @property {string} [resolvePluginsRelativeTo] A path to the directory that plugins should be resolved from. Defaults to `cwd`.
 * @property {Map<string,Rule>} builtInRules The rules that are built in to ESLint.
 * @property {Object} [resolver=ModuleResolver] The module resolver object.
 * @property {string} eslintAllPath The path to the definitions for eslint:all.
 * @property {Function} getEslintAllConfig Returns the config data for eslint:all.
 * @property {string} eslintRecommendedPath The path to the definitions for eslint:recommended.
 * @property {Function} getEslintRecommendedConfig Returns the config data for eslint:recommended.
 */

/**
 * @typedef {Object} ConfigArrayFactoryInternalSlots
 * @property {Map<string,Plugin>} additionalPluginPool The map for additional plugins.
 * @property {string} cwd The path to the current working directory.
 * @property {string | undefined} resolvePluginsRelativeTo An absolute path the the directory that plugins should be resolved from.
 * @property {Map<string,Rule>} builtInRules The rules that are built in to ESLint.
 * @property {Object} [resolver=ModuleResolver] The module resolver object.
 * @property {string} eslintAllPath The path to the definitions for eslint:all.
 * @property {Function} getEslintAllConfig Returns the config data for eslint:all.
 * @property {string} eslintRecommendedPath The path to the definitions for eslint:recommended.
 * @property {Function} getEslintRecommendedConfig Returns the config data for eslint:recommended.
 */

/**
 * @typedef {Object} ConfigArrayFactoryLoadingContext
 * @property {string} filePath The path to the current configuration.
 * @property {string} matchBasePath The base path to resolve relative paths in `overrides[].files`, `overrides[].excludedFiles`, and `ignorePatterns`.
 * @property {string} name The name of the current configuration.
 * @property {string} pluginBasePath The base path to resolve plugins.
 * @property {"config" | "ignore" | "implicit-processor"} type The type of the current configuration. This is `"config"` in normal. This is `"ignore"` if it came from `.eslintignore`. This is `"implicit-processor"` if it came from legacy file-extension processors.
 */

/**
 * @typedef {Object} ConfigArrayFactoryLoadingContext
 * @property {string} filePath The path to the current configuration.
 * @property {string} matchBasePath The base path to resolve relative paths in `overrides[].files`, `overrides[].excludedFiles`, and `ignorePatterns`.
 * @property {string} name The name of the current configuration.
 * @property {"config" | "ignore" | "implicit-processor"} type The type of the current configuration. This is `"config"` in normal. This is `"ignore"` if it came from `.eslintignore`. This is `"implicit-processor"` if it came from legacy file-extension processors.
 */

/** @type {WeakMap<ConfigArrayFactory, ConfigArrayFactoryInternalSlots>} */
const internalSlotsMap = new WeakMap();

/** @type {WeakMap<object, Plugin>} */
const normalizedPlugins = new WeakMap();

/**
 * Check if a given string is a file path.
 * @param {string} nameOrPath A module name or file path.
 * @returns {boolean} `true` if the `nameOrPath` is a file path.
 */
function isFilePath(nameOrPath) {
    return (
        /^\.{1,2}[/\\]/u.test(nameOrPath) ||
        path.isAbsolute(nameOrPath)
    );
}

/**
 * Convenience wrapper for synchronously reading file contents.
 * @param {string} filePath The filename to read.
 * @returns {string} The file contents, with the BOM removed.
 * @private
 */
function readFile(filePath) {
    return fs.readFileSync(filePath, "utf8").replace(/^\ufeff/u, "");
}

/**
 * Loads a YAML configuration from a file.
 * @param {string} filePath The filename to load.
 * @returns {ConfigData} The configuration object from the file.
 * @throws {Error} If the file cannot be read.
 * @private
 */
function loadYAMLConfigFile(filePath) {
    debug(`Loading YAML config file: ${filePath}`);

    // lazy load YAML to improve performance when not used
    const yaml = require("js-yaml");

    try {

        // empty YAML file can be null, so always use
        return yaml.load(readFile(filePath)) || {};
    } catch (e) {
        debug(`Error reading YAML file: ${filePath}`);
        e.message = `Cannot read config file: ${filePath}\nError: ${e.message}`;
        throw e;
    }
}

/**
 * Loads a JSON configuration from a file.
 * @param {string} filePath The filename to load.
 * @returns {ConfigData} The configuration object from the file.
 * @throws {Error} If the file cannot be read.
 * @private
 */
function loadJSONConfigFile(filePath) {
    debug(`Loading JSON config file: ${filePath}`);

    try {
        return JSON.parse(stripComments(readFile(filePath)));
    } catch (e) {
        debug(`Error reading JSON file: ${filePath}`);
        e.message = `Cannot read config file: ${filePath}\nError: ${e.message}`;
        e.messageTemplate = "failed-to-read-json";
        e.messageData = {
            path: filePath,
            message: e.message
        };
        throw e;
    }
}

/**
 * Loads a legacy (.eslintrc) configuration from a file.
 * @param {string} filePath The filename to load.
 * @returns {ConfigData} The configuration object from the file.
 * @throws {Error} If the file cannot be read.
 * @private
 */
function loadLegacyConfigFile(filePath) {
    debug(`Loading legacy config file: ${filePath}`);

    // lazy load YAML to improve performance when not used
    const yaml = require("js-yaml");

    try {
        return yaml.load(stripComments(readFile(filePath))) || /* istanbul ignore next */ {};
    } catch (e) {
        debug("Error reading YAML file: %s\n%o", filePath, e);
        e.message = `Cannot read config file: ${filePath}\nError: ${e.message}`;
        throw e;
    }
}

/**
 * Loads a JavaScript configuration from a file.
 * @param {string} filePath The filename to load.
 * @returns {ConfigData} The configuration object from the file.
 * @throws {Error} If the file cannot be read.
 * @private
 */
function loadJSConfigFile(filePath) {
    debug(`Loading JS config file: ${filePath}`);
    try {
        return importFresh(filePath);
    } catch (e) {
        debug(`Error reading JavaScript file: ${filePath}`);
        e.message = `Cannot read config file: ${filePath}\nError: ${e.message}`;
        throw e;
    }
}

/**
 * Loads a configuration from a package.json file.
 * @param {string} filePath The filename to load.
 * @returns {ConfigData} The configuration object from the file.
 * @throws {Error} If the file cannot be read.
 * @private
 */
function loadPackageJSONConfigFile(filePath) {
    debug(`Loading package.json config file: ${filePath}`);
    try {
        const packageData = loadJSONConfigFile(filePath);

        if (!Object.hasOwnProperty.call(packageData, "eslintConfig")) {
            throw Object.assign(
                new Error("package.json file doesn't have 'eslintConfig' field."),
                { code: "ESLINT_CONFIG_FIELD_NOT_FOUND" }
            );
        }

        return packageData.eslintConfig;
    } catch (e) {
        debug(`Error reading package.json file: ${filePath}`);
        e.message = `Cannot read config file: ${filePath}\nError: ${e.message}`;
        throw e;
    }
}

/**
 * Loads a `.eslintignore` from a file.
 * @param {string} filePath The filename to load.
 * @returns {string[]} The ignore patterns from the file.
 * @private
 */
function loadESLintIgnoreFile(filePath) {
    debug(`Loading .eslintignore file: ${filePath}`);

    try {
        return readFile(filePath)
            .split(/\r?\n/gu)
            .filter(line => line.trim() !== "" && !line.startsWith("#"));
    } catch (e) {
        debug(`Error reading .eslintignore file: ${filePath}`);
        e.message = `Cannot read .eslintignore file: ${filePath}\nError: ${e.message}`;
        throw e;
    }
}

/**
 * Creates an error to notify about a missing config to extend from.
 * @param {string} configName The name of the missing config.
 * @param {string} importerName The name of the config that imported the missing config
 * @param {string} messageTemplate The text template to source error strings from.
 * @returns {Error} The error object to throw
 * @private
 */
function configInvalidError(configName, importerName, messageTemplate) {
    return Object.assign(
        new Error(`Failed to load config "${configName}" to extend from.`),
        {
            messageTemplate,
            messageData: { configName, importerName }
        }
    );
}

/**
 * Loads a configuration file regardless of the source. Inspects the file path
 * to determine the correctly way to load the config file.
 * @param {string} filePath The path to the configuration.
 * @returns {ConfigData|null} The configuration information.
 * @private
 */
function loadConfigFile(filePath) {
    switch (path.extname(filePath)) {
        case ".js":
        case ".cjs":
            return loadJSConfigFile(filePath);

        case ".json":
            if (path.basename(filePath) === "package.json") {
                return loadPackageJSONConfigFile(filePath);
            }
            return loadJSONConfigFile(filePath);

        case ".yaml":
        case ".yml":
            return loadYAMLConfigFile(filePath);

        default:
            return loadLegacyConfigFile(filePath);
    }
}

/**
 * Write debug log.
 * @param {string} request The requested module name.
 * @param {string} relativeTo The file path to resolve the request relative to.
 * @param {string} filePath The resolved file path.
 * @returns {void}
 */
function writeDebugLogForLoading(request, relativeTo, filePath) {
    /* istanbul ignore next */
    if (debug.enabled) {
        let nameAndVersion = null;

        try {
            const packageJsonPath = ModuleResolver.resolve(
                `${request}/package.json`,
                relativeTo
            );
            const { version = "unknown" } = require(packageJsonPath);

            nameAndVersion = `${request}@${version}`;
        } catch (error) {
            debug("package.json was not found:", error.message);
            nameAndVersion = request;
        }

        debug("Loaded: %s (%s)", nameAndVersion, filePath);
    }
}

/**
 * Create a new context with default values.
 * @param {ConfigArrayFactoryInternalSlots} slots The internal slots.
 * @param {"config" | "ignore" | "implicit-processor" | undefined} providedType The type of the current configuration. Default is `"config"`.
 * @param {string | undefined} providedName The name of the current configuration. Default is the relative path from `cwd` to `filePath`.
 * @param {string | undefined} providedFilePath The path to the current configuration. Default is empty string.
 * @param {string | undefined} providedMatchBasePath The type of the current configuration. Default is the directory of `filePath` or `cwd`.
 * @returns {ConfigArrayFactoryLoadingContext} The created context.
 */
function createContext(
    { cwd, resolvePluginsRelativeTo },
    providedType,
    providedName,
    providedFilePath,
    providedMatchBasePath
) {
    const filePath = providedFilePath
        ? path.resolve(cwd, providedFilePath)
        : "";
    const matchBasePath =
        (providedMatchBasePath && path.resolve(cwd, providedMatchBasePath)) ||
        (filePath && path.dirname(filePath)) ||
        cwd;
    const name =
        providedName ||
        (filePath && path.relative(cwd, filePath)) ||
        "";
    const pluginBasePath =
        resolvePluginsRelativeTo ||
        (filePath && path.dirname(filePath)) ||
        cwd;
    const type = providedType || "config";

    return { filePath, matchBasePath, name, pluginBasePath, type };
}

/**
 * Normalize a given plugin.
 * - Ensure the object to have four properties: configs, environments, processors, and rules.
 * - Ensure the object to not have other properties.
 * @param {Plugin} plugin The plugin to normalize.
 * @returns {Plugin} The normalized plugin.
 */
function normalizePlugin(plugin) {

    // first check the cache
    let normalizedPlugin = normalizedPlugins.get(plugin);

    if (normalizedPlugin) {
        return normalizedPlugin;
    }

    normalizedPlugin = {
        configs: plugin.configs || {},
        environments: plugin.environments || {},
        processors: plugin.processors || {},
        rules: plugin.rules || {}
    };

    // save the reference for later
    normalizedPlugins.set(plugin, normalizedPlugin);

    return normalizedPlugin;
}

//------------------------------------------------------------------------------
// Public Interface
//------------------------------------------------------------------------------

/**
 * The factory of `ConfigArray` objects.
 */
class ConfigArrayFactory {

    /**
     * Initialize this instance.
     * @param {ConfigArrayFactoryOptions} [options] The map for additional plugins.
     */
    constructor({
        additionalPluginPool = new Map(),
        cwd = process.cwd(),
        resolvePluginsRelativeTo,
        builtInRules,
        resolver = ModuleResolver,
        eslintAllPath,
        getEslintAllConfig,
        eslintRecommendedPath,
        getEslintRecommendedConfig
    } = {}) {
        internalSlotsMap.set(this, {
            additionalPluginPool,
            cwd,
            resolvePluginsRelativeTo:
                resolvePluginsRelativeTo &&
                path.resolve(cwd, resolvePluginsRelativeTo),
            builtInRules,
            resolver,
            eslintAllPath,
            getEslintAllConfig,
            eslintRecommendedPath,
            getEslintRecommendedConfig
        });
    }

    /**
     * Create `ConfigArray` instance from a config data.
     * @param {ConfigData|null} configData The config data to create.
     * @param {Object} [options] The options.
     * @param {string} [options.basePath] The base path to resolve relative paths in `overrides[].files`, `overrides[].excludedFiles`, and `ignorePatterns`.
     * @param {string} [options.filePath] The path to this config data.
     * @param {string} [options.name] The config name.
     * @returns {ConfigArray} Loaded config.
     */
    create(configData, { basePath, filePath, name } = {}) {
        if (!configData) {
            return new ConfigArray();
        }

        const slots = internalSlotsMap.get(this);
        const ctx = createContext(slots, "config", name, filePath, basePath);
        const elements = this._normalizeConfigData(configData, ctx);

        return new ConfigArray(...elements);
    }

    /**
     * Load a config file.
     * @param {string} filePath The path to a config file.
     * @param {Object} [options] The options.
     * @param {string} [options.basePath] The base path to resolve relative paths in `overrides[].files`, `overrides[].excludedFiles`, and `ignorePatterns`.
     * @param {string} [options.name] The config name.
     * @returns {ConfigArray} Loaded config.
     */
    loadFile(filePath, { basePath, name } = {}) {
        const slots = internalSlotsMap.get(this);
        const ctx = createContext(slots, "config", name, filePath, basePath);

        return new ConfigArray(...this._loadConfigData(ctx));
    }

    /**
     * Load the config file on a given directory if exists.
     * @param {string} directoryPath The path to a directory.
     * @param {Object} [options] The options.
     * @param {string} [options.basePath] The base path to resolve relative paths in `overrides[].files`, `overrides[].excludedFiles`, and `ignorePatterns`.
     * @param {string} [options.name] The config name.
     * @returns {ConfigArray} Loaded config. An empty `ConfigArray` if any config doesn't exist.
     */
    loadInDirectory(directoryPath, { basePath, name } = {}) {
        const slots = internalSlotsMap.get(this);

        for (const filename of configFilenames) {
            const ctx = createContext(
                slots,
                "config",
                name,
                path.join(directoryPath, filename),
                basePath
            );

            if (fs.existsSync(ctx.filePath) && fs.statSync(ctx.filePath).isFile()) {
                let configData;

                try {
                    configData = loadConfigFile(ctx.filePath);
                } catch (error) {
                    if (!error || error.code !== "ESLINT_CONFIG_FIELD_NOT_FOUND") {
                        throw error;
                    }
                }

                if (configData) {
                    debug(`Config file found: ${ctx.filePath}`);
                    return new ConfigArray(
                        ...this._normalizeConfigData(configData, ctx)
                    );
                }
            }
        }

        debug(`Config file not found on ${directoryPath}`);
        return new ConfigArray();
    }

    /**
     * Check if a config file on a given directory exists or not.
     * @param {string} directoryPath The path to a directory.
     * @returns {string | null} The path to the found config file. If not found then null.
     */
    static getPathToConfigFileInDirectory(directoryPath) {
        for (const filename of configFilenames) {
            const filePath = path.join(directoryPath, filename);

            if (fs.existsSync(filePath)) {
                if (filename === "package.json") {
                    try {
                        loadPackageJSONConfigFile(filePath);
                        return filePath;
                    } catch { /* ignore */ }
                } else {
                    return filePath;
                }
            }
        }
        return null;
    }

    /**
     * Load `.eslintignore` file.
     * @param {string} filePath The path to a `.eslintignore` file to load.
     * @returns {ConfigArray} Loaded config. An empty `ConfigArray` if any config doesn't exist.
     */
    loadESLintIgnore(filePath) {
        const slots = internalSlotsMap.get(this);
        const ctx = createContext(
            slots,
            "ignore",
            void 0,
            filePath,
            slots.cwd
        );
        const ignorePatterns = loadESLintIgnoreFile(ctx.filePath);

        return new ConfigArray(
            ...this._normalizeESLintIgnoreData(ignorePatterns, ctx)
        );
    }

    /**
     * Load `.eslintignore` file in the current working directory.
     * @returns {ConfigArray} Loaded config. An empty `ConfigArray` if any config doesn't exist.
     */
    loadDefaultESLintIgnore() {
        const slots = internalSlotsMap.get(this);
        const eslintIgnorePath = path.resolve(slots.cwd, ".eslintignore");
        const packageJsonPath = path.resolve(slots.cwd, "package.json");

        if (fs.existsSync(eslintIgnorePath)) {
            return this.loadESLintIgnore(eslintIgnorePath);
        }
        if (fs.existsSync(packageJsonPath)) {
            const data = loadJSONConfigFile(packageJsonPath);

            if (Object.hasOwnProperty.call(data, "eslintIgnore")) {
                if (!Array.isArray(data.eslintIgnore)) {
                    throw new Error("Package.json eslintIgnore property requires an array of paths");
                }
                const ctx = createContext(
                    slots,
                    "ignore",
                    "eslintIgnore in package.json",
                    packageJsonPath,
                    slots.cwd
                );

                return new ConfigArray(
                    ...this._normalizeESLintIgnoreData(data.eslintIgnore, ctx)
                );
            }
        }

        return new ConfigArray();
    }

    /**
     * Load a given config file.
     * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
     * @returns {IterableIterator<ConfigArrayElement>} Loaded config.
     * @private
     */
    _loadConfigData(ctx) {
        return this._normalizeConfigData(loadConfigFile(ctx.filePath), ctx);
    }

    /**
     * Normalize a given `.eslintignore` data to config array elements.
     * @param {string[]} ignorePatterns The patterns to ignore files.
     * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
     * @returns {IterableIterator<ConfigArrayElement>} The normalized config.
     * @private
     */
    *_normalizeESLintIgnoreData(ignorePatterns, ctx) {
        const elements = this._normalizeObjectConfigData(
            { ignorePatterns },
            ctx
        );

        // Set `ignorePattern.loose` flag for backward compatibility.
        for (const element of elements) {
            if (element.ignorePattern) {
                element.ignorePattern.loose = true;
            }
            yield element;
        }
    }

    /**
     * Normalize a given config to an array.
     * @param {ConfigData} configData The config data to normalize.
     * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
     * @returns {IterableIterator<ConfigArrayElement>} The normalized config.
     * @private
     */
    _normalizeConfigData(configData, ctx) {
        const validator = new ConfigValidator();

        validator.validateConfigSchema(configData, ctx.name || ctx.filePath);
        return this._normalizeObjectConfigData(configData, ctx);
    }

    /**
     * Normalize a given config to an array.
     * @param {ConfigData|OverrideConfigData} configData The config data to normalize.
     * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
     * @returns {IterableIterator<ConfigArrayElement>} The normalized config.
     * @private
     */
    *_normalizeObjectConfigData(configData, ctx) {
        const { files, excludedFiles, ...configBody } = configData;
        const criteria = OverrideTester.create(
            files,
            excludedFiles,
            ctx.matchBasePath
        );
        const elements = this._normalizeObjectConfigDataBody(configBody, ctx);

        // Apply the criteria to every element.
        for (const element of elements) {

            /*
             * Merge the criteria.
             * This is for the `overrides` entries that came from the
             * configurations of `overrides[].extends`.
             */
            element.criteria = OverrideTester.and(criteria, element.criteria);

            /*
             * Remove `root` property to ignore `root` settings which came from
             * `extends` in `overrides`.
             */
            if (element.criteria) {
                element.root = void 0;
            }

            yield element;
        }
    }

    /**
     * Normalize a given config to an array.
     * @param {ConfigData} configData The config data to normalize.
     * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
     * @returns {IterableIterator<ConfigArrayElement>} The normalized config.
     * @private
     */
    *_normalizeObjectConfigDataBody(
        {
            env,
            extends: extend,
            globals,
            ignorePatterns,
            noInlineConfig,
            parser: parserName,
            parserOptions,
            plugins: pluginList,
            processor,
            reportUnusedDisableDirectives,
            root,
            rules,
            settings,
            overrides: overrideList = []
        },
        ctx
    ) {
        const extendList = Array.isArray(extend) ? extend : [extend];
        const ignorePattern = ignorePatterns && new IgnorePattern(
            Array.isArray(ignorePatterns) ? ignorePatterns : [ignorePatterns],
            ctx.matchBasePath
        );

        // Flatten `extends`.
        for (const extendName of extendList.filter(Boolean)) {
            yield* this._loadExtends(extendName, ctx);
        }

        // Load parser & plugins.
        const parser = parserName && this._loadParser(parserName, ctx);
        const plugins = pluginList && this._loadPlugins(pluginList, ctx);

        // Yield pseudo config data for file extension processors.
        if (plugins) {
            yield* this._takeFileExtensionProcessors(plugins, ctx);
        }

        // Yield the config data except `extends` and `overrides`.
        yield {

            // Debug information.
            type: ctx.type,
            name: ctx.name,
            filePath: ctx.filePath,

            // Config data.
            criteria: null,
            env,
            globals,
            ignorePattern,
            noInlineConfig,
            parser,
            parserOptions,
            plugins,
            processor,
            reportUnusedDisableDirectives,
            root,
            rules,
            settings
        };

        // Flatten `overries`.
        for (let i = 0; i < overrideList.length; ++i) {
            yield* this._normalizeObjectConfigData(
                overrideList[i],
                { ...ctx, name: `${ctx.name}#overrides[${i}]` }
            );
        }
    }

    /**
     * Load configs of an element in `extends`.
     * @param {string} extendName The name of a base config.
     * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
     * @returns {IterableIterator<ConfigArrayElement>} The normalized config.
     * @private
     */
    _loadExtends(extendName, ctx) {
        debug("Loading {extends:%j} relative to %s", extendName, ctx.filePath);
        try {
            if (extendName.startsWith("eslint:")) {
                return this._loadExtendedBuiltInConfig(extendName, ctx);
            }
            if (extendName.startsWith("plugin:")) {
                return this._loadExtendedPluginConfig(extendName, ctx);
            }
            return this._loadExtendedShareableConfig(extendName, ctx);
        } catch (error) {
            error.message += `\nReferenced from: ${ctx.filePath || ctx.name}`;
            throw error;
        }
    }

    /**
     * Load configs of an element in `extends`.
     * @param {string} extendName The name of a base config.
     * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
     * @returns {IterableIterator<ConfigArrayElement>} The normalized config.
     * @private
     */
    _loadExtendedBuiltInConfig(extendName, ctx) {
        const {
            eslintAllPath,
            getEslintAllConfig,
            eslintRecommendedPath,
            getEslintRecommendedConfig
        } = internalSlotsMap.get(this);

        if (extendName === "eslint:recommended") {
            const name = `${ctx.name} » ${extendName}`;

            if (getEslintRecommendedConfig) {
                if (typeof getEslintRecommendedConfig !== "function") {
                    throw new Error(`getEslintRecommendedConfig must be a function instead of '${getEslintRecommendedConfig}'`);
                }
                return this._normalizeConfigData(getEslintRecommendedConfig(), { ...ctx, name, filePath: "" });
            }
            return this._loadConfigData({
                ...ctx,
                name,
                filePath: eslintRecommendedPath
            });
        }
        if (extendName === "eslint:all") {
            const name = `${ctx.name} » ${extendName}`;

            if (getEslintAllConfig) {
                if (typeof getEslintAllConfig !== "function") {
                    throw new Error(`getEslintAllConfig must be a function instead of '${getEslintAllConfig}'`);
                }
                return this._normalizeConfigData(getEslintAllConfig(), { ...ctx, name, filePath: "" });
            }
            return this._loadConfigData({
                ...ctx,
                name,
                filePath: eslintAllPath
            });
        }

        throw configInvalidError(extendName, ctx.name, "extend-config-missing");
    }

    /**
     * Load configs of an element in `extends`.
     * @param {string} extendName The name of a base config.
     * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
     * @returns {IterableIterator<ConfigArrayElement>} The normalized config.
     * @private
     */
    _loadExtendedPluginConfig(extendName, ctx) {
        const slashIndex = extendName.lastIndexOf("/");

        if (slashIndex === -1) {
            throw configInvalidError(extendName, ctx.filePath, "plugin-invalid");
        }

        const pluginName = extendName.slice("plugin:".length, slashIndex);
        const configName = extendName.slice(slashIndex + 1);

        if (isFilePath(pluginName)) {
            throw new Error("'extends' cannot use a file path for plugins.");
        }

        const plugin = this._loadPlugin(pluginName, ctx);
        const configData =
            plugin.definition &&
            plugin.definition.configs[configName];

        if (configData) {
            return this._normalizeConfigData(configData, {
                ...ctx,
                filePath: plugin.filePath || ctx.filePath,
                name: `${ctx.name} » plugin:${plugin.id}/${configName}`
            });
        }

        throw plugin.error || configInvalidError(extendName, ctx.filePath, "extend-config-missing");
    }

    /**
     * Load configs of an element in `extends`.
     * @param {string} extendName The name of a base config.
     * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
     * @returns {IterableIterator<ConfigArrayElement>} The normalized config.
     * @private
     */
    _loadExtendedShareableConfig(extendName, ctx) {
        const { cwd, resolver } = internalSlotsMap.get(this);
        const relativeTo = ctx.filePath || path.join(cwd, "__placeholder__.js");
        let request;

        if (isFilePath(extendName)) {
            request = extendName;
        } else if (extendName.startsWith(".")) {
            request = `./${extendName}`; // For backward compatibility. A ton of tests depended on this behavior.
        } else {
            request = naming.normalizePackageName(
                extendName,
                "eslint-config"
            );
        }

        let filePath;

        try {
            filePath = resolver.resolve(request, relativeTo);
        } catch (error) {
            /* istanbul ignore else */
            if (error && error.code === "MODULE_NOT_FOUND") {
                throw configInvalidError(extendName, ctx.filePath, "extend-config-missing");
            }
            throw error;
        }

        writeDebugLogForLoading(request, relativeTo, filePath);
        return this._loadConfigData({
            ...ctx,
            filePath,
            name: `${ctx.name} » ${request}`
        });
    }

    /**
     * Load given plugins.
     * @param {string[]} names The plugin names to load.
     * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
     * @returns {Record<string,DependentPlugin>} The loaded parser.
     * @private
     */
    _loadPlugins(names, ctx) {
        return names.reduce((map, name) => {
            if (isFilePath(name)) {
                throw new Error("Plugins array cannot includes file paths.");
            }
            const plugin = this._loadPlugin(name, ctx);

            map[plugin.id] = plugin;

            return map;
        }, {});
    }

    /**
     * Load a given parser.
     * @param {string} nameOrPath The package name or the path to a parser file.
     * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
     * @returns {DependentParser} The loaded parser.
     */
    _loadParser(nameOrPath, ctx) {
        debug("Loading parser %j from %s", nameOrPath, ctx.filePath);

        const { cwd, resolver } = internalSlotsMap.get(this);
        const relativeTo = ctx.filePath || path.join(cwd, "__placeholder__.js");

        try {
            const filePath = resolver.resolve(nameOrPath, relativeTo);

            writeDebugLogForLoading(nameOrPath, relativeTo, filePath);

            return new ConfigDependency({
                definition: require(filePath),
                filePath,
                id: nameOrPath,
                importerName: ctx.name,
                importerPath: ctx.filePath
            });
        } catch (error) {

            // If the parser name is "espree", load the espree of ESLint.
            if (nameOrPath === "espree") {
                debug("Fallback espree.");
                return new ConfigDependency({
                    definition: require("espree"),
                    filePath: require.resolve("espree"),
                    id: nameOrPath,
                    importerName: ctx.name,
                    importerPath: ctx.filePath
                });
            }

            debug("Failed to load parser '%s' declared in '%s'.", nameOrPath, ctx.name);
            error.message = `Failed to load parser '${nameOrPath}' declared in '${ctx.name}': ${error.message}`;

            return new ConfigDependency({
                error,
                id: nameOrPath,
                importerName: ctx.name,
                importerPath: ctx.filePath
            });
        }
    }

    /**
     * Load a given plugin.
     * @param {string} name The plugin name to load.
     * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
     * @returns {DependentPlugin} The loaded plugin.
     * @private
     */
    _loadPlugin(name, ctx) {
        debug("Loading plugin %j from %s", name, ctx.filePath);

        const { additionalPluginPool, resolver } = internalSlotsMap.get(this);
        const request = naming.normalizePackageName(name, "eslint-plugin");
        const id = naming.getShorthandName(request, "eslint-plugin");
        const relativeTo = path.join(ctx.pluginBasePath, "__placeholder__.js");

        if (name.match(/\s+/u)) {
            const error = Object.assign(
                new Error(`Whitespace found in plugin name '${name}'`),
                {
                    messageTemplate: "whitespace-found",
                    messageData: { pluginName: request }
                }
            );

            return new ConfigDependency({
                error,
                id,
                importerName: ctx.name,
                importerPath: ctx.filePath
            });
        }

        // Check for additional pool.
        const plugin =
            additionalPluginPool.get(request) ||
            additionalPluginPool.get(id);

        if (plugin) {
            return new ConfigDependency({
                definition: normalizePlugin(plugin),
                original: plugin,
                filePath: "", // It's unknown where the plugin came from.
                id,
                importerName: ctx.name,
                importerPath: ctx.filePath
            });
        }

        let filePath;
        let error;

        try {
            filePath = resolver.resolve(request, relativeTo);
        } catch (resolveError) {
            error = resolveError;
            /* istanbul ignore else */
            if (error && error.code === "MODULE_NOT_FOUND") {
                error.messageTemplate = "plugin-missing";
                error.messageData = {
                    pluginName: request,
                    resolvePluginsRelativeTo: ctx.pluginBasePath,
                    importerName: ctx.name
                };
            }
        }

        if (filePath) {
            try {
                writeDebugLogForLoading(request, relativeTo, filePath);

                const startTime = Date.now();
                const pluginDefinition = require(filePath);

                debug(`Plugin ${filePath} loaded in: ${Date.now() - startTime}ms`);

                return new ConfigDependency({
                    definition: normalizePlugin(pluginDefinition),
                    original: pluginDefinition,
                    filePath,
                    id,
                    importerName: ctx.name,
                    importerPath: ctx.filePath
                });
            } catch (loadError) {
                error = loadError;
            }
        }

        debug("Failed to load plugin '%s' declared in '%s'.", name, ctx.name);
        error.message = `Failed to load plugin '${name}' declared in '${ctx.name}': ${error.message}`;
        return new ConfigDependency({
            error,
            id,
            importerName: ctx.name,
            importerPath: ctx.filePath
        });
    }

    /**
     * Take file expression processors as config array elements.
     * @param {Record<string,DependentPlugin>} plugins The plugin definitions.
     * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
     * @returns {IterableIterator<ConfigArrayElement>} The config array elements of file expression processors.
     * @private
     */
    *_takeFileExtensionProcessors(plugins, ctx) {
        for (const pluginId of Object.keys(plugins)) {
            const processors =
                plugins[pluginId] &&
                plugins[pluginId].definition &&
                plugins[pluginId].definition.processors;

            if (!processors) {
                continue;
            }

            for (const processorId of Object.keys(processors)) {
                if (processorId.startsWith(".")) {
                    yield* this._normalizeObjectConfigData(
                        {
                            files: [`*${processorId}`],
                            processor: `${pluginId}/${processorId}`
                        },
                        {
                            ...ctx,
                            type: "implicit-processor",
                            name: `${ctx.name}#processors["${pluginId}/${processorId}"]`
                        }
                    );
                }
            }
        }
    }
}

export { ConfigArrayFactory, createContext };


code:
/**
 * @fileoverview `ConfigArray` class.
 *
 * `ConfigArray` class expresses the full of a configuration. It has the entry
 * config file, base config files that were extended, loaded parsers, and loaded
 * plugins.
 *
 * `ConfigArray` class provides three properties and two methods.
 *
 * - `pluginEnvironments`
 * - `pluginProcessors`
 * - `pluginRules`
 *      The `Map` objects that contain the members of all plugins that this
 *      config array contains. Those map objects don't have mutation methods.
 *      Those keys are the member ID such as `pluginId/memberName`.
 * - `isRoot()`
 *      If `true` then this configuration has `root:true` property.
 * - `extractConfig(filePath)`
 *      Extract the final configuration for a given file. This means merging
 *      every config array element which that `criteria` property matched. The
 *      `filePath` argument must be an absolute path.
 *
 * `ConfigArrayFactory` provides the loading logic of config files.
 *
 * @author Toru Nagashima <https://github.com/mysticatea>
 */

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

import { ExtractedConfig } from "./extracted-config.js";
import { IgnorePattern } from "./ignore-pattern.js";

//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------

// Define types for VSCode IntelliSense.
/** @typedef {import("../../shared/types").Environment} Environment */
/** @typedef {import("../../shared/types").GlobalConf} GlobalConf */
/** @typedef {import("../../shared/types").RuleConf} RuleConf */
/** @typedef {import("../../shared/types").Rule} Rule */
/** @typedef {import("../../shared/types").Plugin} Plugin */
/** @typedef {import("../../shared/types").Processor} Processor */
/** @typedef {import("./config-dependency").DependentParser} DependentParser */
/** @typedef {import("./config-dependency").DependentPlugin} DependentPlugin */
/** @typedef {import("./override-tester")["OverrideTester"]} OverrideTester */

/**
 * @typedef {Object} ConfigArrayElement
 * @property {string} name The name of this config element.
 * @property {string} filePath The path to the source file of this config element.
 * @property {InstanceType<OverrideTester>|null} criteria The tester for the `files` and `excludedFiles` of this config element.
 * @property {Record<string, boolean>|undefined} env The environment settings.
 * @property {Record<string, GlobalConf>|undefined} globals The global variable settings.
 * @property {IgnorePattern|undefined} ignorePattern The ignore patterns.
 * @property {boolean|undefined} noInlineConfig The flag that disables directive comments.
 * @property {DependentParser|undefined} parser The parser loader.
 * @property {Object|undefined} parserOptions The parser options.
 * @property {Record<string, DependentPlugin>|undefined} plugins The plugin loaders.
 * @property {string|undefined} processor The processor name to refer plugin's processor.
 * @property {boolean|undefined} reportUnusedDisableDirectives The flag to report unused `eslint-disable` comments.
 * @property {boolean|undefined} root The flag to express root.
 * @property {Record<string, RuleConf>|undefined} rules The rule settings
 * @property {Object|undefined} settings The shared settings.
 * @property {"config" | "ignore" | "implicit-processor"} type The element type.
 */

/**
 * @typedef {Object} ConfigArrayInternalSlots
 * @property {Map<string, ExtractedConfig>} cache The cache to extract configs.
 * @property {ReadonlyMap<string, Environment>|null} envMap The map from environment ID to environment definition.
 * @property {ReadonlyMap<string, Processor>|null} processorMap The map from processor ID to environment definition.
 * @property {ReadonlyMap<string, Rule>|null} ruleMap The map from rule ID to rule definition.
 */

/** @type {WeakMap<ConfigArray, ConfigArrayInternalSlots>} */
const internalSlotsMap = new class extends WeakMap {
    get(key) {
        let value = super.get(key);

        if (!value) {
            value = {
                cache: new Map(),
                envMap: null,
                processorMap: null,
                ruleMap: null
            };
            super.set(key, value);
        }

        return value;
    }
}();

/**
 * Get the indices which are matched to a given file.
 * @param {ConfigArrayElement[]} elements The elements.
 * @param {string} filePath The path to a target file.
 * @returns {number[]} The indices.
 */
function getMatchedIndices(elements, filePath) {
    const indices = [];

    for (let i = elements.length - 1; i >= 0; --i) {
        const element = elements[i];

        if (!element.criteria || (filePath && element.criteria.test(filePath))) {
            indices.push(i);
        }
    }

    return indices;
}

/**
 * Check if a value is a non-null object.
 * @param {any} x The value to check.
 * @returns {boolean} `true` if the value is a non-null object.
 */
function isNonNullObject(x) {
    return typeof x === "object" && x !== null;
}

/**
 * Merge two objects.
 *
 * Assign every property values of `y` to `x` if `x` doesn't have the property.
 * If `x`'s property value is an object, it does recursive.
 * @param {Object} target The destination to merge
 * @param {Object|undefined} source The source to merge.
 * @returns {void}
 */
function mergeWithoutOverwrite(target, source) {
    if (!isNonNullObject(source)) {
        return;
    }

    for (const key of Object.keys(source)) {
        if (key === "__proto__") {
            continue;
        }

        if (isNonNullObject(target[key])) {
            mergeWithoutOverwrite(target[key], source[key]);
        } else if (target[key] === void 0) {
            if (isNonNullObject(source[key])) {
                target[key] = Array.isArray(source[key]) ? [] : {};
                mergeWithoutOverwrite(target[key], source[key]);
            } else if (source[key] !== void 0) {
                target[key] = source[key];
            }
        }
    }
}

/**
 * The error for plugin conflicts.
 */
class PluginConflictError extends Error {

    /**
     * Initialize this error object.
     * @param {string} pluginId The plugin ID.
     * @param {{filePath:string, importerName:string}[]} plugins The resolved plugins.
     */
    constructor(pluginId, plugins) {
        super(`Plugin "${pluginId}" was conflicted between ${plugins.map(p => `"${p.importerName}"`).join(" and ")}.`);
        this.messageTemplate = "plugin-conflict";
        this.messageData = { pluginId, plugins };
    }
}

/**
 * Merge plugins.
 * `target`'s definition is prior to `source`'s.
 * @param {Record<string, DependentPlugin>} target The destination to merge
 * @param {Record<string, DependentPlugin>|undefined} source The source to merge.
 * @returns {void}
 */
function mergePlugins(target, source) {
    if (!isNonNullObject(source)) {
        return;
    }

    for (const key of Object.keys(source)) {
        if (key === "__proto__") {
            continue;
        }
        const targetValue = target[key];
        const sourceValue = source[key];

        // Adopt the plugin which was found at first.
        if (targetValue === void 0) {
            if (sourceValue.error) {
                throw sourceValue.error;
            }
            target[key] = sourceValue;
        } else if (sourceValue.filePath !== targetValue.filePath) {
            throw new PluginConflictError(key, [
                {
                    filePath: targetValue.filePath,
                    importerName: targetValue.importerName
                },
                {
                    filePath: sourceValue.filePath,
                    importerName: sourceValue.importerName
                }
            ]);
        }
    }
}

/**
 * Merge rule configs.
 * `target`'s definition is prior to `source`'s.
 * @param {Record<string, Array>} target The destination to merge
 * @param {Record<string, RuleConf>|undefined} source The source to merge.
 * @returns {void}
 */
function mergeRuleConfigs(target, source) {
    if (!isNonNullObject(source)) {
        return;
    }

    for (const key of Object.keys(source)) {
        if (key === "__proto__") {
            continue;
        }
        const targetDef = target[key];
        const sourceDef = source[key];

        // Adopt the rule config which was found at first.
        if (targetDef === void 0) {
            if (Array.isArray(sourceDef)) {
                target[key] = [...sourceDef];
            } else {
                target[key] = [sourceDef];
            }

        /*
         * If the first found rule config is severity only and the current rule
         * config has options, merge the severity and the options.
         */
        } else if (
            targetDef.length === 1 &&
            Array.isArray(sourceDef) &&
            sourceDef.length >= 2
        ) {
            targetDef.push(...sourceDef.slice(1));
        }
    }
}

/**
 * Create the extracted config.
 * @param {ConfigArray} instance The config elements.
 * @param {number[]} indices The indices to use.
 * @returns {ExtractedConfig} The extracted config.
 */
function createConfig(instance, indices) {
    const config = new ExtractedConfig();
    const ignorePatterns = [];

    // Merge elements.
    for (const index of indices) {
        const element = instance[index];

        // Adopt the parser which was found at first.
        if (!config.parser && element.parser) {
            if (element.parser.error) {
                throw element.parser.error;
            }
            config.parser = element.parser;
        }

        // Adopt the processor which was found at first.
        if (!config.processor && element.processor) {
            config.processor = element.processor;
        }

        // Adopt the noInlineConfig which was found at first.
        if (config.noInlineConfig === void 0 && element.noInlineConfig !== void 0) {
            config.noInlineConfig = element.noInlineConfig;
            config.configNameOfNoInlineConfig = element.name;
        }

        // Adopt the reportUnusedDisableDirectives which was found at first.
        if (config.reportUnusedDisableDirectives === void 0 && element.reportUnusedDisableDirectives !== void 0) {
            config.reportUnusedDisableDirectives = element.reportUnusedDisableDirectives;
        }

        // Collect ignorePatterns
        if (element.ignorePattern) {
            ignorePatterns.push(element.ignorePattern);
        }

        // Merge others.
        mergeWithoutOverwrite(config.env, element.env);
        mergeWithoutOverwrite(config.globals, element.globals);
        mergeWithoutOverwrite(config.parserOptions, element.parserOptions);
        mergeWithoutOverwrite(config.settings, element.settings);
        mergePlugins(config.plugins, element.plugins);
        mergeRuleConfigs(config.rules, element.rules);
    }

    // Create the predicate function for ignore patterns.
    if (ignorePatterns.length > 0) {
        config.ignores = IgnorePattern.createIgnore(ignorePatterns.reverse());
    }

    return config;
}

/**
 * Collect definitions.
 * @template T, U
 * @param {string} pluginId The plugin ID for prefix.
 * @param {Record<string,T>} defs The definitions to collect.
 * @param {Map<string, U>} map The map to output.
 * @param {function(T): U} [normalize] The normalize function for each value.
 * @returns {void}
 */
function collect(pluginId, defs, map, normalize) {
    if (defs) {
        const prefix = pluginId && `${pluginId}/`;

        for (const [key, value] of Object.entries(defs)) {
            map.set(
                `${prefix}${key}`,
                normalize ? normalize(value) : value
            );
        }
    }
}

/**
 * Normalize a rule definition.
 * @param {Function|Rule} rule The rule definition to normalize.
 * @returns {Rule} The normalized rule definition.
 */
function normalizePluginRule(rule) {
    return typeof rule === "function" ? { create: rule } : rule;
}

/**
 * Delete the mutation methods from a given map.
 * @param {Map<any, any>} map The map object to delete.
 * @returns {void}
 */
function deleteMutationMethods(map) {
    Object.defineProperties(map, {
        clear: { configurable: true, value: void 0 },
        delete: { configurable: true, value: void 0 },
        set: { configurable: true, value: void 0 }
    });
}

/**
 * Create `envMap`, `processorMap`, `ruleMap` with the plugins in the config array.
 * @param {ConfigArrayElement[]} elements The config elements.
 * @param {ConfigArrayInternalSlots} slots The internal slots.
 * @returns {void}
 */
function initPluginMemberMaps(elements, slots) {
    const processed = new Set();

    slots.envMap = new Map();
    slots.processorMap = new Map();
    slots.ruleMap = new Map();

    for (const element of elements) {
        if (!element.plugins) {
            continue;
        }

        for (const [pluginId, value] of Object.entries(element.plugins)) {
            const plugin = value.definition;

            if (!plugin || processed.has(pluginId)) {
                continue;
            }
            processed.add(pluginId);

            collect(pluginId, plugin.environments, slots.envMap);
            collect(pluginId, plugin.processors, slots.processorMap);
            collect(pluginId, plugin.rules, slots.ruleMap, normalizePluginRule);
        }
    }

    deleteMutationMethods(slots.envMap);
    deleteMutationMethods(slots.processorMap);
    deleteMutationMethods(slots.ruleMap);
}

/**
 * Create `envMap`, `processorMap`, `ruleMap` with the plugins in the config array.
 * @param {ConfigArray} instance The config elements.
 * @returns {ConfigArrayInternalSlots} The extracted config.
 */
function ensurePluginMemberMaps(instance) {
    const slots = internalSlotsMap.get(instance);

    if (!slots.ruleMap) {
        initPluginMemberMaps(instance, slots);
    }

    return slots;
}

//------------------------------------------------------------------------------
// Public Interface
//------------------------------------------------------------------------------

/**
 * The Config Array.
 *
 * `ConfigArray` instance contains all settings, parsers, and plugins.
 * You need to call `ConfigArray#extractConfig(filePath)` method in order to
 * extract, merge and get only the config data which is related to an arbitrary
 * file.
 * @extends {Array<ConfigArrayElement>}
 */
class ConfigArray extends Array {

    /**
     * Get the plugin environments.
     * The returned map cannot be mutated.
     * @type {ReadonlyMap<string, Environment>} The plugin environments.
     */
    get pluginEnvironments() {
        return ensurePluginMemberMaps(this).envMap;
    }

    /**
     * Get the plugin processors.
     * The returned map cannot be mutated.
     * @type {ReadonlyMap<string, Processor>} The plugin processors.
     */
    get pluginProcessors() {
        return ensurePluginMemberMaps(this).processorMap;
    }

    /**
     * Get the plugin rules.
     * The returned map cannot be mutated.
     * @returns {ReadonlyMap<string, Rule>} The plugin rules.
     */
    get pluginRules() {
        return ensurePluginMemberMaps(this).ruleMap;
    }

    /**
     * Check if this config has `root` flag.
     * @returns {boolean} `true` if this config array is root.
     */
    isRoot() {
        for (let i = this.length - 1; i >= 0; --i) {
            const root = this[i].root;

            if (typeof root === "boolean") {
                return root;
            }
        }
        return false;
    }

    /**
     * Extract the config data which is related to a given file.
     * @param {string} filePath The absolute path to the target file.
     * @returns {ExtractedConfig} The extracted config data.
     */
    extractConfig(filePath) {
        const { cache } = internalSlotsMap.get(this);
        const indices = getMatchedIndices(this, filePath);
        const cacheKey = indices.join(",");

        if (!cache.has(cacheKey)) {
            cache.set(cacheKey, createConfig(this, indices));
        }

        return cache.get(cacheKey);
    }

    /**
     * Check if a given path is an additional lint target.
     * @param {string} filePath The absolute path to the target file.
     * @returns {boolean} `true` if the file is an additional lint target.
     */
    isAdditionalTargetPath(filePath) {
        for (const { criteria, type } of this) {
            if (
                type === "config" &&
                criteria &&
                !criteria.endsWithWildcard &&
                criteria.test(filePath)
            ) {
                return true;
            }
        }
        return false;
    }
}

/**
 * Get the used extracted configs.
 * CLIEngine will use this method to collect used deprecated rules.
 * @param {ConfigArray} instance The config array object to get.
 * @returns {ExtractedConfig[]} The used extracted configs.
 * @private
 */
function getUsedExtractedConfigs(instance) {
    const { cache } = internalSlotsMap.get(instance);

    return Array.from(cache.values());
}

export {
    ConfigArray,
    getUsedExtractedConfigs
};


code:
/**
 * @fileoverview `ConfigDependency` class.
 *
 * `ConfigDependency` class expresses a loaded parser or plugin.
 *
 * If the parser or plugin was loaded successfully, it has `definition` property
 * and `filePath` property. Otherwise, it has `error` property.
 *
 * When `JSON.stringify()` converted a `ConfigDependency` object to a JSON, it
 * omits `definition` property.
 *
 * `ConfigArrayFactory` creates `ConfigDependency` objects when it loads parsers
 * or plugins.
 *
 * @author Toru Nagashima <https://github.com/mysticatea>
 */

import util from "util";

/**
 * The class is to store parsers or plugins.
 * This class hides the loaded object from `JSON.stringify()` and `console.log`.
 * @template T
 */
class ConfigDependency {

    /**
     * Initialize this instance.
     * @param {Object} data The dependency data.
     * @param {T} [data.definition] The dependency if the loading succeeded.
     * @param {T} [data.original] The original, non-normalized dependency if the loading succeeded.
     * @param {Error} [data.error] The error object if the loading failed.
     * @param {string} [data.filePath] The actual path to the dependency if the loading succeeded.
     * @param {string} data.id The ID of this dependency.
     * @param {string} data.importerName The name of the config file which loads this dependency.
     * @param {string} data.importerPath The path to the config file which loads this dependency.
     */
    constructor({
        definition = null,
        original = null,
        error = null,
        filePath = null,
        id,
        importerName,
        importerPath
    }) {

        /**
         * The loaded dependency if the loading succeeded.
         * @type {T|null}
         */
        this.definition = definition;

        /**
         * The original dependency as loaded directly from disk if the loading succeeded.
         * @type {T|null}
         */
        this.original = original;

        /**
         * The error object if the loading failed.
         * @type {Error|null}
         */
        this.error = error;

        /**
         * The loaded dependency if the loading succeeded.
         * @type {string|null}
         */
        this.filePath = filePath;

        /**
         * The ID of this dependency.
         * @type {string}
         */
        this.id = id;

        /**
         * The name of the config file which loads this dependency.
         * @type {string}
         */
        this.importerName = importerName;

        /**
         * The path to the config file which loads this dependency.
         * @type {string}
         */
        this.importerPath = importerPath;
    }

    // eslint-disable-next-line jsdoc/require-description
    /**
     * @returns {Object} a JSON compatible object.
     */
    toJSON() {
        const obj = this[util.inspect.custom]();

        // Display `error.message` (`Error#message` is unenumerable).
        if (obj.error instanceof Error) {
            obj.error = { ...obj.error, message: obj.error.message };
        }

        return obj;
    }

    // eslint-disable-next-line jsdoc/require-description
    /**
     * @returns {Object} an object to display by `console.log()`.
     */
    [util.inspect.custom]() {
        const {
            definition: _ignore1, // eslint-disable-line no-unused-vars
            original: _ignore2, // eslint-disable-line no-unused-vars
            ...obj
        } = this;

        return obj;
    }
}

/** @typedef {ConfigDependency<import("../../shared/types").Parser>} DependentParser */
/** @typedef {ConfigDependency<import("../../shared/types").Plugin>} DependentPlugin */

export { ConfigDependency };


code:
/**
 * @fileoverview `ExtractedConfig` class.
 *
 * `ExtractedConfig` class expresses a final configuration for a specific file.
 *
 * It provides one method.
 *
 * - `toCompatibleObjectAsConfigFileContent()`
 *      Convert this configuration to the compatible object as the content of
 *      config files. It converts the loaded parser and plugins to strings.
 *      `CLIEngine#getConfigForFile(filePath)` method uses this method.
 *
 * `ConfigArray#extractConfig(filePath)` creates a `ExtractedConfig` instance.
 *
 * @author Toru Nagashima <https://github.com/mysticatea>
 */

import { IgnorePattern } from "./ignore-pattern.js";

// For VSCode intellisense
/** @typedef {import("../../shared/types").ConfigData} ConfigData */
/** @typedef {import("../../shared/types").GlobalConf} GlobalConf */
/** @typedef {import("../../shared/types").SeverityConf} SeverityConf */
/** @typedef {import("./config-dependency").DependentParser} DependentParser */
/** @typedef {import("./config-dependency").DependentPlugin} DependentPlugin */

/**
 * Check if `xs` starts with `ys`.
 * @template T
 * @param {T[]} xs The array to check.
 * @param {T[]} ys The array that may be the first part of `xs`.
 * @returns {boolean} `true` if `xs` starts with `ys`.
 */
function startsWith(xs, ys) {
    return xs.length >= ys.length && ys.every((y, i) => y === xs[i]);
}

/**
 * The class for extracted config data.
 */
class ExtractedConfig {
    constructor() {

        /**
         * The config name what `noInlineConfig` setting came from.
         * @type {string}
         */
        this.configNameOfNoInlineConfig = "";

        /**
         * Environments.
         * @type {Record<string, boolean>}
         */
        this.env = {};

        /**
         * Global variables.
         * @type {Record<string, GlobalConf>}
         */
        this.globals = {};

        /**
         * The glob patterns that ignore to lint.
         * @type {(((filePath:string, dot?:boolean) => boolean) & { basePath:string; patterns:string[] }) | undefined}
         */
        this.ignores = void 0;

        /**
         * The flag that disables directive comments.
         * @type {boolean|undefined}
         */
        this.noInlineConfig = void 0;

        /**
         * Parser definition.
         * @type {DependentParser|null}
         */
        this.parser = null;

        /**
         * Options for the parser.
         * @type {Object}
         */
        this.parserOptions = {};

        /**
         * Plugin definitions.
         * @type {Record<string, DependentPlugin>}
         */
        this.plugins = {};

        /**
         * Processor ID.
         * @type {string|null}
         */
        this.processor = null;

        /**
         * The flag that reports unused `eslint-disable` directive comments.
         * @type {boolean|undefined}
         */
        this.reportUnusedDisableDirectives = void 0;

        /**
         * Rule settings.
         * @type {Record<string, [SeverityConf, ...any[]]>}
         */
        this.rules = {};

        /**
         * Shared settings.
         * @type {Object}
         */
        this.settings = {};
    }

    /**
     * Convert this config to the compatible object as a config file content.
     * @returns {ConfigData} The converted object.
     */
    toCompatibleObjectAsConfigFileContent() {
        const {
            /* eslint-disable no-unused-vars */
            configNameOfNoInlineConfig: _ignore1,
            processor: _ignore2,
            /* eslint-enable no-unused-vars */
            ignores,
            ...config
        } = this;

        config.parser = config.parser && config.parser.filePath;
        config.plugins = Object.keys(config.plugins).filter(Boolean).reverse();
        config.ignorePatterns = ignores ? ignores.patterns : [];

        // Strip the default patterns from `ignorePatterns`.
        if (startsWith(config.ignorePatterns, IgnorePattern.DefaultPatterns)) {
            config.ignorePatterns =
                config.ignorePatterns.slice(IgnorePattern.DefaultPatterns.length);
        }

        return config;
    }
}

export { ExtractedConfig };


code:
/**
 * @fileoverview `IgnorePattern` class.
 *
 * `IgnorePattern` class has the set of glob patterns and the base path.
 *
 * It provides two static methods.
 *
 * - `IgnorePattern.createDefaultIgnore(cwd)`
 *      Create the default predicate function.
 * - `IgnorePattern.createIgnore(ignorePatterns)`
 *      Create the predicate function from multiple `IgnorePattern` objects.
 *
 * It provides two properties and a method.
 *
 * - `patterns`
 *      The glob patterns that ignore to lint.
 * - `basePath`
 *      The base path of the glob patterns. If absolute paths existed in the
 *      glob patterns, those are handled as relative paths to the base path.
 * - `getPatternsRelativeTo(basePath)`
 *      Get `patterns` as modified for a given base path. It modifies the
 *      absolute paths in the patterns as prepending the difference of two base
 *      paths.
 *
 * `ConfigArrayFactory` creates `IgnorePattern` objects when it processes
 * `ignorePatterns` properties.
 *
 * @author Toru Nagashima <https://github.com/mysticatea>
 */

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

import assert from "assert";
import path from "path";
import ignore from "ignore";
import debugOrig from "debug";

const debug = debugOrig("eslintrc:ignore-pattern");

/** @typedef {ReturnType<import("ignore").default>} Ignore */

//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------

/**
 * Get the path to the common ancestor directory of given paths.
 * @param {string[]} sourcePaths The paths to calculate the common ancestor.
 * @returns {string} The path to the common ancestor directory.
 */
function getCommonAncestorPath(sourcePaths) {
    let result = sourcePaths[0];

    for (let i = 1; i < sourcePaths.length; ++i) {
        const a = result;
        const b = sourcePaths[i];

        // Set the shorter one (it's the common ancestor if one includes the other).
        result = a.length < b.length ? a : b;

        // Set the common ancestor.
        for (let j = 0, lastSepPos = 0; j < a.length && j < b.length; ++j) {
            if (a[j] !== b[j]) {
                result = a.slice(0, lastSepPos);
                break;
            }
            if (a[j] === path.sep) {
                lastSepPos = j;
            }
        }
    }

    let resolvedResult = result || path.sep;

    // if Windows common ancestor is root of drive must have trailing slash to be absolute.
    if (resolvedResult && resolvedResult.endsWith(":") && process.platform === "win32") {
        resolvedResult += path.sep;
    }
    return resolvedResult;
}

/**
 * Make relative path.
 * @param {string} from The source path to get relative path.
 * @param {string} to The destination path to get relative path.
 * @returns {string} The relative path.
 */
function relative(from, to) {
    const relPath = path.relative(from, to);

    if (path.sep === "/") {
        return relPath;
    }
    return relPath.split(path.sep).join("/");
}

/**
 * Get the trailing slash if existed.
 * @param {string} filePath The path to check.
 * @returns {string} The trailing slash if existed.
 */
function dirSuffix(filePath) {
    const isDir = (
        filePath.endsWith(path.sep) ||
        (process.platform === "win32" && filePath.endsWith("/"))
    );

    return isDir ? "/" : "";
}

const DefaultPatterns = Object.freeze(["/**/node_modules/*"]);
const DotPatterns = Object.freeze([".*", "!.eslintrc.*", "!../"]);

//------------------------------------------------------------------------------
// Public
//------------------------------------------------------------------------------

class IgnorePattern {

    /**
     * The default patterns.
     * @type {string[]}
     */
    static get DefaultPatterns() {
        return DefaultPatterns;
    }

    /**
     * Create the default predicate function.
     * @param {string} cwd The current working directory.
     * @returns {((filePath:string, dot:boolean) => boolean) & {basePath:string; patterns:string[]}}
     * The preficate function.
     * The first argument is an absolute path that is checked.
     * The second argument is the flag to not ignore dotfiles.
     * If the predicate function returned `true`, it means the path should be ignored.
     */
    static createDefaultIgnore(cwd) {
        return this.createIgnore([new IgnorePattern(DefaultPatterns, cwd)]);
    }

    /**
     * Create the predicate function from multiple `IgnorePattern` objects.
     * @param {IgnorePattern[]} ignorePatterns The list of ignore patterns.
     * @returns {((filePath:string, dot?:boolean) => boolean) & {basePath:string; patterns:string[]}}
     * The preficate function.
     * The first argument is an absolute path that is checked.
     * The second argument is the flag to not ignore dotfiles.
     * If the predicate function returned `true`, it means the path should be ignored.
     */
    static createIgnore(ignorePatterns) {
        debug("Create with: %o", ignorePatterns);

        const basePath = getCommonAncestorPath(ignorePatterns.map(p => p.basePath));
        const patterns = [].concat(
            ...ignorePatterns.map(p => p.getPatternsRelativeTo(basePath))
        );
        const ig = ignore({ allowRelativePaths: true }).add([...DotPatterns, ...patterns]);
        const dotIg = ignore({ allowRelativePaths: true }).add(patterns);

        debug("  processed: %o", { basePath, patterns });

        return Object.assign(
            (filePath, dot = false) => {
                assert(path.isAbsolute(filePath), "'filePath' should be an absolute path.");
                const relPathRaw = relative(basePath, filePath);
                const relPath = relPathRaw && (relPathRaw + dirSuffix(filePath));
                const adoptedIg = dot ? dotIg : ig;
                const result = relPath !== "" && adoptedIg.ignores(relPath);

                debug("Check", { filePath, dot, relativePath: relPath, result });
                return result;
            },
            { basePath, patterns }
        );
    }

    /**
     * Initialize a new `IgnorePattern` instance.
     * @param {string[]} patterns The glob patterns that ignore to lint.
     * @param {string} basePath The base path of `patterns`.
     */
    constructor(patterns, basePath) {
        assert(path.isAbsolute(basePath), "'basePath' should be an absolute path.");

        /**
         * The glob patterns that ignore to lint.
         * @type {string[]}
         */
        this.patterns = patterns;

        /**
         * The base path of `patterns`.
         * @type {string}
         */
        this.basePath = basePath;

        /**
         * If `true` then patterns which don't start with `/` will match the paths to the outside of `basePath`. Defaults to `false`.
         *
         * It's set `true` for `.eslintignore`, `package.json`, and `--ignore-path` for backward compatibility.
         * It's `false` as-is for `ignorePatterns` property in config files.
         * @type {boolean}
         */
        this.loose = false;
    }

    /**
     * Get `patterns` as modified for a given base path. It modifies the
     * absolute paths in the patterns as prepending the difference of two base
     * paths.
     * @param {string} newBasePath The base path.
     * @returns {string[]} Modifired patterns.
     */
    getPatternsRelativeTo(newBasePath) {
        assert(path.isAbsolute(newBasePath), "'newBasePath' should be an absolute path.");
        const { basePath, loose, patterns } = this;

        if (newBasePath === basePath) {
            return patterns;
        }
        const prefix = `/${relative(newBasePath, basePath)}`;

        return patterns.map(pattern => {
            const negative = pattern.startsWith("!");
            const head = negative ? "!" : "";
            const body = negative ? pattern.slice(1) : pattern;

            if (body.startsWith("/") || body.startsWith("../")) {
                return `${head}${prefix}${body}`;
            }
            return loose ? pattern : `${head}${prefix}/**/${body}`;
        });
    }
}

export { IgnorePattern };


code:
/**
 * @fileoverview `ConfigArray` class.
 * @author Toru Nagashima <https://github.com/mysticatea>
 */

import { ConfigArray, getUsedExtractedConfigs } from "./config-array.js";
import { ConfigDependency } from "./config-dependency.js";
import { ExtractedConfig } from "./extracted-config.js";
import { IgnorePattern } from "./ignore-pattern.js";
import { OverrideTester } from "./override-tester.js";

export {
    ConfigArray,
    ConfigDependency,
    ExtractedConfig,
    IgnorePattern,
    OverrideTester,
    getUsedExtractedConfigs
};