From 4fae4bbbe4c4b43d045fbecbe5fa5eb6925480f6 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Tue, 16 Aug 2022 14:36:35 +0300
Subject: [PATCH] Add event-based behavior & processor registration in ECS

---
 libs/util/include/psemek/util/ecs.hpp | 47 +++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/libs/util/include/psemek/util/ecs.hpp b/libs/util/include/psemek/util/ecs.hpp
index 41270b44..ce65fbd3 100644
--- a/libs/util/include/psemek/util/ecs.hpp
+++ b/libs/util/include/psemek/util/ecs.hpp
@@ -2,6 +2,7 @@
 
 #include <psemek/util/to_string.hpp>
 #include <psemek/util/type_name.hpp>
+#include <psemek/util/function.hpp>
 
 #include <cstdint>
 #include <typeindex>
@@ -466,8 +467,22 @@ namespace psemek::util
 		template <typename Behavior, typename ... Args>
 		void apply(Behavior && behavior, species_handle species, Args const & ... args);
 
+		template <typename Event, typename Processor>
+		void register_processor(Processor && processor);
+
+		template <typename Event, typename Behavior>
+		void register_behavior(Behavior && behavior);
+
+		template <typename Event, typename Behavior>
+		void register_behavior(Behavior && behavior, species_handle species);
+
+		template <typename Event>
+		void event(Event const & event);
+
 	private:
 		std::vector<std::unique_ptr<ecs_detail::species_base>> species_;
+
+		std::unordered_map<std::type_index, std::vector<util::function<void(void const *)>>> event_subscribers_;
 	};
 
 	template <typename ... Components>
@@ -573,6 +588,38 @@ namespace psemek::util
 		species_[species.value]->apply(behavior, args...);
 	}
 
+	template <typename Event, typename Processor>
+	void ecs::register_processor(Processor && processor)
+	{
+		event_subscribers_[typeid(Event)].push_back([this, processor = std::move(processor)](void const * event) mutable {
+			processor(*static_cast<Event const *>(event));
+		});
+	}
+
+	template <typename Event, typename Behavior>
+	void ecs::register_behavior(Behavior && behavior)
+	{
+		event_subscribers_[typeid(Event)].push_back([this, behavior = std::move(behavior)](void const * event) mutable {
+			apply(behavior, *static_cast<Event const *>(event));
+		});
+	}
+
+	template <typename Event, typename Behavior>
+	void ecs::register_behavior(Behavior && behavior, species_handle species)
+	{
+		event_subscribers_[typeid(Event)].push_back([this, species, behavior = std::move(behavior)](void const * event) mutable {
+			apply(behavior, species, *static_cast<Event const *>(event));
+		});
+	}
+
+	template <typename Event>
+	void ecs::event(Event const & event)
+	{
+		if (auto it = event_subscribers_.find(typeid(Event)); it != event_subscribers_.end())
+			for (auto const & b : it->second)
+				b(std::addressof(event));
+	}
+
 }
 
 namespace std