X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=source%2Fgame%2Feventbus.h;fp=source%2Fgame%2Feventbus.h;h=ce9c812e20b1593cbbe6489b537d4ad201f1f52f;hb=6a93721ab67315e916f6c649b1f7bc5447d611a4;hp=0000000000000000000000000000000000000000;hpb=b644c89c81d89f60a0d82fe208fc76ce1c278a4c;p=libs%2Fgame.git

diff --git a/source/game/eventbus.h b/source/game/eventbus.h
new file mode 100644
index 0000000..ce9c812
--- /dev/null
+++ b/source/game/eventbus.h
@@ -0,0 +1,113 @@
+#ifndef MSP_GAME_EVENTBUS_H_
+#define MSP_GAME_EVENTBUS_H_
+
+#include <functional>
+#include <vector>
+
+namespace Msp::Game {
+
+class EventObserver;
+
+template<typename T>
+struct EventDispatcher
+{
+	struct Handler
+	{
+		EventObserver *observer;
+		std::function<void(const T &)> callback;
+	};
+
+	std::vector<Handler> handlers;
+
+	void add_observer(EventObserver *obs, std::function<void(const T &)> &&cb)
+	{ handlers.emplace_back(obs, std::move(cb)); }
+
+	void remove_observer(EventObserver *obs)
+	{ std::erase_if(handlers, [obs](const Handler &h){ return h.observer==obs; }); }
+
+	void dispatch(const T &) const;
+};
+
+
+class EventBus
+{
+private:
+	using DeleteFunc = void(void *);
+	using RemoveFunc = void(void *, EventObserver &);
+
+	struct Dispatcher
+	{
+		void *dispatcher = nullptr;
+		DeleteFunc *deleter = nullptr;
+		RemoveFunc *remover = nullptr;
+	};
+
+	std::vector<Dispatcher> dispatchers;
+
+	static unsigned get_next_id();
+
+public:
+	template<typename T>
+	static unsigned get_event_id();
+
+private:
+	template<typename T>
+	EventDispatcher<T> &get_emitter();
+
+public:
+	template<typename T>
+	void add_observer(EventObserver &obs, std::function<void(const T &)> cb)
+	{ get_emitter<T>().add_observer(obs, std::move(cb)); }
+
+	void replace_observer(EventObserver &, EventObserver &);
+	void remove_observer(EventObserver &);
+
+	template<typename T>
+	void dispatch(const T &) const;
+};
+
+
+template<typename T>
+void EventDispatcher<T>::dispatch(const T &event) const
+{
+	for(const Handler &h: handlers)
+		h.callback(event);
+}
+
+
+template<typename T>
+inline unsigned EventBus::get_event_id()
+{
+	static unsigned id = get_next_id();
+	return id;
+}
+
+template<typename T>
+inline EventDispatcher<T> &EventBus::get_emitter()
+{
+	unsigned id = get_event_id<T>();
+	if(dispatchers.size()<=id)
+		dispatchers.resize(id+1);
+
+	Dispatcher &event = dispatchers[id];
+	if(!event.dispatcher)
+	{
+		event.dispatcher = new EventDispatcher<T>;
+		event.deleter = [](void *p){ delete static_cast<EventDispatcher<T> *>(p); };
+		event.remover = [](void *p, EventObserver &o){ static_cast<EventDispatcher<T> *>(p)->remove_observer(o); };
+	}
+
+	return static_cast<EventDispatcher<T> *>(event.dispatcher);
+}
+
+template<typename T>
+inline void EventBus::dispatch(const T &event) const
+{
+	unsigned id = get_event_id<T>();
+	if(id<dispatchers.size() && dispatchers[id].dispatcher)
+		static_cast<EventDispatcher<T> *>(dispatchers[id].dispatcher)->dispatch(event);
+}
+
+} // namespace Msp::Game
+
+#endif