--- /dev/null
+/**
+ * @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>
+ */
+"use strict";
+
+const util = require("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 {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,
+ error = null,
+ filePath = null,
+ id,
+ importerName,
+ importerPath
+ }) {
+
+ /**
+ * The loaded dependency if the loading succeeded.
+ * @type {T|null}
+ */
+ this.definition = definition;
+
+ /**
+ * 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: _ignore, // eslint-disable-line no-unused-vars
+ ...obj
+ } = this;
+
+ return obj;
+ }
+}
+
+/** @typedef {ConfigDependency<import("../../shared/types").Parser>} DependentParser */
+/** @typedef {ConfigDependency<import("../../shared/types").Plugin>} DependentPlugin */
+
+module.exports = { ConfigDependency };