Reimplement broadcast (un)subscribe events

src/client/voice/VoiceBroadcast.js

@@ -1,5 +1,6 @@
 const EventEmitter = require('events');
 const BroadcastAudioPlayer = require('./player/BroadcastAudioPlayer');
+const DispatcherSet = require('./util/DispatcherSet');
 
 /**
  * A voice broadcast can be played across multiple voice connections for improved shared-stream efficiency.
@@ -23,7 +24,7 @@ class VoiceBroadcast extends EventEmitter {
      * @type {Client}
      */
     this.client = client;
-    this.dispatchers = new Set();
+    this.dispatchers = new DispatcherSet(this);
     this.player = new BroadcastAudioPlayer(this);
   }
 

src/client/voice/util/DispatcherSet.js

@@ -0,0 +1,40 @@
+const { Events } = require('../../../util/Constants');
+
+/**
+ * A "store" for handling broadcast dispatcher (un)subscription
+ * @private
+ */
+class DispatcherSet extends Set {
+  constructor(broadcast) {
+    super();
+    /**
+     * The broadcast that this set belongs to
+     * @type {VoiceBroadcast}
+     */
+    this.broadcast = broadcast;
+  }
+
+  add(dispatcher) {
+    super.add(dispatcher);
+    /**
+     * Emitted whenever a stream dispatcher subscribes to the broadcast.
+     * @event VoiceBroadcast#subscribe
+     * @param {StreamDispatcher} dispatcher The subscribed dispatcher
+     */
+    this.broadcast.emit(Events.VOICE_BROADCAST_SUBSCRIBE, dispatcher);
+    return this;
+  }
+
+  delete(dispatcher) {
+    const ret = super.delete(dispatcher);
+    /**
+     * Emitted whenever a stream dispatcher unsubscribes to the broadcast.
+     * @event VoiceBroadcast#unsubscribe
+     * @param {StreamDispatcher} dispatcher The unsubscribed dispatcher
+     */
+    if (ret) this.broadcast.emit(Events.VOICE_BROADCAST_UNSUBSCRIBE, dispatcher);
+    return ret;
+  }
+}
+
+module.exports = DispatcherSet;

src/util/Constants.js

@@ -234,6 +234,8 @@ exports.Events = {
   USER_GUILD_SETTINGS_UPDATE: 'clientUserGuildSettingsUpdate',
   PRESENCE_UPDATE: 'presenceUpdate',
   VOICE_STATE_UPDATE: 'voiceStateUpdate',
+  VOICE_BROADCAST_SUBSCRIBE: 'subscribe',
+  VOICE_BROADCAST_UNSUBSCRIBE: 'unsubscribe',
   TYPING_START: 'typingStart',
   TYPING_STOP: 'typingStop',
   DISCONNECT: 'disconnect',