Erweiterungen

lib/tools/message_service.dart

@@ -1,11 +1,15 @@
 typedef EventHandler<T> = void Function(T args);
 
-/// The Custom Events Service that can publish data
-/// from one module/component to another.
-class MessageService {
-  static final MessageService _singleton = new MessageService._internal();
+class _MapEntry {
+  late dynamic owner;
 
-  Map<String, dynamic> _callbackMaps = Map<String, dynamic>();
+  late dynamic handler;
+}
+
+class MessageService {
+  static final MessageService _singleton = MessageService._internal();
+
+  final Map<String, Set<_MapEntry>> _callbackMaps = <String, Set<_MapEntry>>{};
 
   factory MessageService() {
     return _singleton;
@@ -13,80 +17,39 @@ class MessageService {
 
   MessageService._internal();
 
-  /// Subscribe to an event topic. Events that
-  /// get posted to that topic will trigger
-  /// the provided handler
-  /// * [topic] The topic to subscribe to
-  /// * [handler] The event handler
-  subscribe<T>(String topic, EventHandler<T>? handler) {
-    List<EventHandler<T>>? handlers = _callbackMaps[topic];
-    if (handler == null) {
-      _callbackMaps.remove(topic);
-      return;
-    }
-    if (handlers == null) {
-      handlers = [];
-      _callbackMaps[topic] = handlers;
-    }
-    handlers.add(handler);
-  }
+  subscribe<T>(String topic, dynamic owner, EventHandler<T>? handler) {
+    var entry = _MapEntry();
+    entry.owner = owner;
+    entry.handler = handler;
 
-  /// Unsubscribe from the given topic. Your handler
-  /// will no longer recieve events published to this
-  /// topic
-  /// * [topic] The topic to unsubscribe from
-  /// * [handler] The event handler
-  unsubscribe<T>(String topic, {EventHandler<T>? handler}) {
-    if (handler == null) {
-      _callbackMaps.remove(topic);
-      return;
-    }
-
-    final handlers = _callbackMaps[topic];
-    if (handlers == null) {
-      return;
-    }
-
-    // We now need to remove specific handler
-    final handlerIndex = handlers.indexOf(handler);
-
-    if (handlerIndex >= 0) {
-      handlers.removeAt(handlerIndex);
-      if (handlers.length == 0) {
-        _callbackMaps.remove(topic);
-      }
+    if (_callbackMaps.containsKey(topic)) {
+      _callbackMaps[topic]!.remove(entry);
+      _callbackMaps[topic]!.add(entry);
+    } else {
+      _callbackMaps[topic] = <_MapEntry>{};
+      _callbackMaps[topic]!.add(entry);
     }
   }
 
-  /// Publish an Event to given topic.
-  /// * [topic] The topic to publish to
-  /// * [arguments] The arguments to pass to
-  /// the handlers. It's better if custom
-  /// Structure is used.
-  publish<T>(String topic, {T? arguments}) {
-    List<EventHandler<T>>? handlers;
-    try {
-      handlers = _callbackMaps[topic];
-    } catch (_) {
-      throw FormatException(
-          'Type mismatch between Publisher Arguments and what Subscriber Expects');
-    }
+  unsubscribe<T>(String topic, dynamic owner) {
+    if (_callbackMaps.containsKey(topic)) {
+      for (var entry in _callbackMaps[topic]!) {
+        if (entry.owner == owner) {
+          _callbackMaps[topic]!.remove(entry);
 
-    if (handlers == null || handlers.isEmpty) {
-      return;
-    }
-
-    handlers.forEach((EventHandler<T> handler) {
-      try {
-        if (arguments != null) {
-          handler(arguments);
-        } else {
-          throw 'arguments null';
+          break;
         }
-      } catch (_) {
-        print('Error Occured while executing handler for topic $topic');
-        print(_);
       }
-    });
+    }
+  }
+
+  publish<T>(String topic, {T? arguments}) {
+    var entries = _callbackMaps[topic];
+
+    if (entries != null) {
+      for (var entry in entries) {
+        entry.handler(arguments);
+      }
+    }
   }
 }