From b3df337b8fc13ed2c5cc51a5a928766adfc9fd59 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sun, 17 Dec 2023 12:41:17 +0300
Subject: [PATCH] Add ecs::system_set

---
 libs/ecs/include/psemek/ecs/system_set.hpp | 92 ++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 libs/ecs/include/psemek/ecs/system_set.hpp

diff --git a/libs/ecs/include/psemek/ecs/system_set.hpp b/libs/ecs/include/psemek/ecs/system_set.hpp
new file mode 100644
index 00000000..41376039
--- /dev/null
+++ b/libs/ecs/include/psemek/ecs/system_set.hpp
@@ -0,0 +1,92 @@
+#pragma once
+
+#include <psemek/ecs/container.hpp>
+
+#include <psemek/util/function.hpp>
+
+#include <vector>
+
+namespace psemek::ecs
+{
+
+	struct system_set
+	{
+		/** Add a function to this system set.
+		 *
+		 *  When `system_set::apply()` is called, this function is applied to
+		 *    the container by calling `container.apply<Components...>(function)`.
+		 *
+		 *  The system set automatically manages the query cache for this function.
+		 *
+		 *  @tparam Components The component types, as in `container::apply`
+		 *  @param function The function to be applied to a container
+		 */
+		template <typename ... Components, typename Function>
+		void add(Function && function);
+
+		/** Add a batch function to this system set.
+		 *
+		 *  When `system_set::apply()` is called, this function is applied to
+		 *    the container by calling `container.batch_apply<Components...>(function)`.
+		 *
+		 *  The system set automatically manages the query cache for this function.
+		 *
+		 *  @tparam Components The component types, as in `container::apply`
+		 *  @param function The function to be applied to a container
+		 */
+		template <typename ... Components, typename Function>
+		void add_batch(Function && function);
+
+		/** Apply this system set to a container.
+		 *
+		 *  The functions added to the set via `add` or `add_batch` are applied
+		 *    to the container in the order in which they were added.
+		 *
+		 *  @param container The container to apply the system set to
+		 */
+		void apply(container & container);
+
+		/** Clear this system set, removing all previously added functions.
+		 */
+		void clear();
+
+	private:
+
+		struct system_data
+		{
+			util::function<query_cache(container &, query_cache)> apply;
+			query_cache cache = nullptr;
+		};
+
+		std::vector<system_data> systems_;
+	};
+
+	template <typename ... Components, typename Function>
+	void system_set::add(Function && function)
+	{
+		systems_.push_back({[function = std::move(function)](container & container, query_cache cache) -> query_cache {
+			return container.apply<Components...>(function, cache);
+		}});
+	}
+
+	template <typename ... Components, typename Function>
+	void system_set::add_batch(Function && function)
+	{
+		systems_.push_back({[function = std::move(function)](container & container, query_cache cache) -> query_cache {
+			return container.batch_apply<Components...>(function, cache);
+		}});
+	}
+
+	inline void system_set::apply(container & container)
+	{
+		for (auto & system : systems_)
+			system.cache = system.apply(container, system.cache);
+	}
+
+	inline void system_set::clear()
+	{
+		systems_.clear();
+	}
+
+
+}