add event system and use it to propagate to print traces

src/lib/eventsystem/EventHandler.h

@@ -0,0 +1,80 @@
+#ifndef EVENT_HANDLER_H
+#define EVENT_HANDLER_H
+
+#include <memory>
+
+#include "EventHandlerBase.h"
+#include "EventManager.h"
+
+template <typename T>
+class EventHandler: public EventHandlerBase
+{
+public:
+	void registerForEvent()
+	{
+		EventManager::getInstance()->registerEventHandler(this);
+	}
+
+	void unregisterForEvent()
+	{
+		EventManager::getInstance()->unregisterEventHandler(this);
+	}
+
+	void handleBaseEvent(std::shared_ptr<const Event> event) override
+	{
+		std::shared_ptr<const T> specificEvent = std::dynamic_pointer_cast<const T>(event);
+		if (specificEvent)
+		{
+			handleEvent(specificEvent);
+		}
+	}
+
+private:
+	virtual void handleEvent(std::shared_ptr<const T> event) = 0;
+};
+
+
+template <typename... Ts> class CombinedEventHandlerHelper 
+{
+protected:
+	void registerForEventsHelper() {}
+	void unregisterForEventsHelper() {}
+};
+
+
+template <typename T, typename... Ts>
+class CombinedEventHandlerHelper<T, Ts...>
+    : public EventHandler<T>
+    , public CombinedEventHandlerHelper<Ts...>
+{
+protected:
+	void registerForEventsHelper()
+	{
+		EventHandler<T>::registerForEvent();
+		CombinedEventHandlerHelper<Ts...>::registerForEventsHelper();
+	}
+
+	void unregisterForEventsHelper()
+	{
+		EventHandler<T>::unregisterForEvent();
+		CombinedEventHandlerHelper<Ts...>::unregisterForEventsHelper();
+	}
+};
+
+
+template <typename... Ts>
+class CombinedEventHandler: public CombinedEventHandlerHelper<Ts...>
+{
+protected:
+	void registerForEvents()
+	{
+		CombinedEventHandlerHelper<Ts...>::registerForEventsHelper();
+	}
+
+	void unregisterForEvents()
+	{
+		CombinedEventHandlerHelper<Ts...>::unregisterForEventsHelper();
+	}
+};
+
+#endif   // EVENT_HANDLER_H