Merge branch 'custom-structures'

src/util/Structures.js

@@ -0,0 +1,80 @@
+/**
+ * Allows for the extension of built-in Discord.js structures that are instantiated by {@link DataStore DataStores}.
+ */
+class Structures {
+  constructor() {
+    throw new Error(`The ${this.constructor.name} class may not be instantiated.`);
+  }
+
+  /**
+   * Retrieves a structure class.
+   * @param {string} structure Name of the structure to retrieve
+   * @returns {Function}
+   */
+  static get(structure) {
+    if (typeof structure === 'string') return structures[structure];
+    throw new TypeError(`"structure" argument must be a string (received ${typeof structure})`);
+  }
+
+  /**
+   * Extends a structure.
+   * @param {string} structure Name of the structure class to extend
+   * @param {Function} extender Function that takes the base class to extend as its only parameter and returns the
+   * extended class/prototype
+   * @returns {Function} Extended class/prototype returned from the extender
+   * @example
+   * const { Structures } = require('discord.js');
+   *
+   * Structures.extend('Guild', Guild => {
+   *   class CoolGuild extends Guild {
+   *     constructor(client, data) {
+   *       super(client, data);
+   *       this.cool = true;
+   *     }
+   *   }
+   *
+   *   return CoolGuild;
+   * });
+   */
+  static extend(structure, extender) {
+    if (!structures[structure]) throw new RangeError(`"${structure}" is not a valid extensible structure.`);
+    if (typeof extender !== 'function') {
+      const received = `(received ${typeof extender})`;
+      throw new TypeError(
+        `"extender" argument must be a function that returns the extended structure class/prototype ${received}`
+      );
+    }
+
+    const extended = extender(structures[structure]);
+    if (typeof extended !== 'function') {
+      throw new TypeError('The extender function must return the extended structure class/prototype.');
+    }
+    if (Object.getPrototypeOf(extended) !== structures[structure]) {
+      throw new Error(
+        'The class/prototype returned from the extender function must extend the existing structure class/prototype.'
+      );
+    }
+
+    structures[structure] = extended;
+    return extended;
+  }
+}
+
+const structures = {
+  Emoji: require('../structures/Emoji'),
+  DMChannel: require('../structures/DMChannel'),
+  GroupDMChannel: require('../structures/GroupDMChannel'),
+  TextChannel: require('../structures/TextChannel'),
+  VoiceChannel: require('../structures/VoiceChannel'),
+  CategoryChannel: require('../structures/CategoryChannel'),
+  GuildChannel: require('../structures/GuildChannel'),
+  GuildMember: require('../structures/GuildMember'),
+  Guild: require('../structures/Guild'),
+  Message: require('../structures/Message'),
+  MessageReaction: require('../structures/MessageReaction'),
+  Presence: require('../structures/Presence').Presence,
+  Role: require('../structures/Role'),
+  User: require('../structures/User'),
+};
+
+module.exports = Structures;