Add listener structure directly to component caches.

packages/ecs/include/ecs/entityecs/ECSExt.h

@@ -182,17 +182,62 @@ namespace l::ecs {
 		}
 
 		virtual void receive(World*, const Events::OnComponentAssigned2& event) {
-			tryAdd(event.entity);
+			if (tryAdd(event.entity)) {
+				for (auto& listener : mEventListenersAssign) {
+					listener.second(event);
+				}
+			}
 		}
 
 		virtual void receive(World*, const Events::OnComponentRemoved2& event) {
-			tryRemove(event.entity);
+			if (tryRemove(event.entity)) {
+				for (auto& listener : mEventListenersRemove) {
+					listener.second(event);
+				}
+			}
+		}
+
+		template<class T>
+		int32_t registerListener(std::function<void(const T&)> listener) {
+			if constexpr (std::is_same<T, Events::OnComponentAssigned2>){
+				mEventListenersAssign.push_back({ mIdEnumerator, listener });
+			}
+			else if constexpr (std::is_same<T, Events::OnComponentRemoved2>){
+				mEventListenersRemove.push_back({ mIdEnumerator, listener });
+			}
+			else {
+				return -1;
+			}
+			return mIdEnumerator++;
 		}
 
+		template<class T>
+		void unregisterListener(int32_t id) {
+			if constexpr (std::is_same<T, Events::OnComponentAssigned2>){
+				std::erase_if(mEventListenersAssign, [cid = id](auto& listener) {
+					if (listener.first == cid) {
+						return true;
+					}
+					return false;
+					});
+			}
+			else if constexpr (std::is_same<T, Events::OnComponentRemoved2>){
+				std::erase_if(mEventListenersRemove, [cid = id](auto& listener) {
+					if (listener.first == cid) {
+						return true;
+					}
+					return false;
+					});
+			}
+		}
 	protected:
 
 		std::vector<std::tuple<Entity*, ComponentHandle<Types>...>> mComponents;
 		std::map<Entity*, std::tuple<ComponentHandle<Types>...>> mComponentMap;
+
+		int32_t mIdEnumerator = 0;
+		std::vector<std::pair<int32_t, std::function<void(const Events::OnComponentAssigned2&)>>> mEventListenersAssign;
+		std::vector<std::pair<int32_t, std::function<void(const Events::OnComponentRemoved2&)>>> mEventListenersRemove;
 	};
 
 	class EntitySystem2 : public l::ecs::EntitySystem