feat(Core/Utilities): add event emitter class (#12632)

src/common/Utilities/EventEmitter.h

@@ -0,0 +1,44 @@
+/*
+ * This file is part of the AzerothCore Project. See AUTHORS file for Copyright information
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Affero General Public License as published by the
+ * Free Software Foundation; either version 3 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __EVENT_EMITTER_H
+#define __EVENT_EMITTER_H
+
+template<class Signature>
+class EventEmitter
+{
+public:
+    template<typename Functor>
+    void operator+=(Functor&& f)
+    {
+        functions.emplace_back(std::forward<Functor>(f));
+    }
+
+    template<class... Args>
+    void operator()(Args&&... args) const
+    {
+        for (auto& f : functions)
+        {
+            f(args...);
+        }
+    }
+
+private:
+    std::vector<std::function<Signature>> functions;
+};
+
+#endif