Add support for event subscription (delegates)

code/qcommon/CMakeLists.txt

@@ -13,6 +13,7 @@ set(SOURCES_SHARED_UBER
 	"${CMAKE_SOURCE_DIR}/code/qcommon/class.cpp"
 	"${CMAKE_SOURCE_DIR}/code/qcommon/con_set.cpp"
 	"${CMAKE_SOURCE_DIR}/code/qcommon/con_timer.cpp"
+	"${CMAKE_SOURCE_DIR}/code/qcommon/delegate.cpp"
 	"${CMAKE_SOURCE_DIR}/code/qcommon/lightclass.cpp"
 	"${CMAKE_SOURCE_DIR}/code/qcommon/listener.cpp"
 	"${CMAKE_SOURCE_DIR}/code/qcommon/lz77.cpp"

code/qcommon/delegate.cpp

@@ -0,0 +1,52 @@
+/*
+===========================================================================
+Copyright (C) 2025 the OpenMoHAA team
+
+This file is part of OpenMoHAA source code.
+
+OpenMoHAA source code is free software; you can redistribute it
+and/or modify it under the terms of the GNU General Public License as
+published by the Free Software Foundation; either version 2 of the License,
+or (at your option) any later version.
+
+OpenMoHAA source code 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 General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with OpenMoHAA source code; if not, write to the Free Software
+Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+===========================================================================
+*/
+
+#include "delegate.h"
+
+uint64_t DelegateHandle::currentHandle = 0;
+
+DelegateHandle::DelegateHandle()
+    : handle(GenerateDelegateID())
+{}
+
+bool DelegateHandle::operator==(const DelegateHandle& other) const
+{
+    return handle == other.handle;
+}
+
+bool DelegateHandle::operator!=(const DelegateHandle& other) const
+{
+    return handle != other.handle;
+}
+
+uint64_t DelegateHandle::GenerateDelegateID()
+{
+    uint64_t handle;
+
+    handle = ++currentHandle;
+
+    if (handle == 0) {
+        handle = ++currentHandle;
+    }
+
+    return handle;
+}

code/qcommon/delegate.h

@@ -0,0 +1,125 @@
+/*
+===========================================================================
+Copyright (C) 2025 the OpenMoHAA team
+
+This file is part of OpenMoHAA source code.
+
+OpenMoHAA source code is free software; you can redistribute it
+and/or modify it under the terms of the GNU General Public License as
+published by the Free Software Foundation; either version 2 of the License,
+or (at your option) any later version.
+
+OpenMoHAA source code 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 General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with OpenMoHAA source code; if not, write to the Free Software
+Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+===========================================================================
+*/
+
+#include <functional>
+#include "container.h"
+
+template<typename T>
+using Delegate = std::function<T>;
+
+struct DelegateHandle {
+public:
+    DelegateHandle();
+
+    bool operator==(const DelegateHandle& other) const;
+    bool operator!=(const DelegateHandle& other) const;
+
+private:
+    static uint64_t GenerateDelegateID();
+    static uint64_t currentHandle;
+
+    uint64_t handle;
+};
+
+template<typename T>
+class DelegateMultiElement
+{
+public:
+    DelegateMultiElement(Delegate<T>&& inFunction);
+
+    template<typename... Args>
+    void Execute(Args&&...args) const;
+
+    DelegateHandle GetHandle() const;
+
+private:
+    DelegateHandle handle;
+    Delegate<T>    func;
+};
+
+template<typename T>
+DelegateMultiElement<T>::DelegateMultiElement(Delegate<T>&& inFunction)
+    : func(inFunction)
+{}
+
+template<typename T>
+template<typename... Args>
+void DelegateMultiElement<T>::Execute(Args&&...args) const
+{
+    func(std::move(args)...);
+}
+
+template<typename T>
+DelegateHandle DelegateMultiElement<T>::GetHandle() const
+{
+    return handle;
+}
+
+template<typename T>
+class MulticastDelegate
+{
+public:
+    DelegateHandle Add(Delegate<T>&& function);
+    void           Remove(DelegateHandle handle);
+
+    template<typename... Args>
+    void Execute(Args&&...args);
+
+private:
+    Container<DelegateMultiElement<T>> delegates;
+};
+
+template<typename T>
+DelegateHandle MulticastDelegate<T>::Add(Delegate<T>&& function)
+{
+    int index = delegates.AddObject(DelegateMultiElement<T>(std::move(function)));
+
+    return delegates.ObjectAt(index).GetHandle();
+}
+
+template<typename T>
+void MulticastDelegate<T>::Remove(DelegateHandle handle)
+{
+    size_t i;
+
+    for (i = delegates.NumObjects(); i > 0; i--) {
+        const DelegateMultiElement<T>& elem = delegates.ObjectAt(i);
+
+        if (elem.GetHandle() == handle) {
+            delegates.RemoveObjectAt(i);
+            break;
+        }
+    }
+}
+
+template<typename T>
+template<typename... Args>
+void MulticastDelegate<T>::Execute(Args&&...args)
+{
+    size_t i;
+
+    for (i = 1; i <= delegates.NumObjects(); i++) {
+        const DelegateMultiElement<T>& element = delegates.ObjectAt(i);
+
+        element.Execute(std::move(args)...);
+    }
+}