Add system graph (wip)

include/Nazara/Core/Systems.hpp

@@ -30,5 +30,6 @@
 #define NAZARA_CORE_SYSTEMS_HPP
 
 #include <Nazara/Core/Systems/LifetimeSystem.hpp>
+#include <Nazara/Core/Systems/SystemGraph.hpp>
 
 #endif // NAZARA_CORE_SYSTEMS_HPP

include/Nazara/Core/Systems/SystemGraph.hpp

@@ -0,0 +1,70 @@
+// Copyright (C) 2022 Jérôme "Lynix" Leclercq (lynix680@gmail.com)
+// This file is part of the "Nazara Engine - Core module"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#pragma once
+
+#ifndef NAZARA_CORE_SYSTEMS_SYSTEMGRAPH_HPP
+#define NAZARA_CORE_SYSTEMS_SYSTEMGRAPH_HPP
+
+#include <Nazara/Prerequisites.hpp>
+#include <Nazara/Core/Clock.hpp>
+#include <Nazara/Core/Config.hpp>
+#include <Nazara/Utils/MovablePtr.hpp>
+#include <entt/entt.hpp>
+#include <functional>
+#include <unordered_map>
+#include <vector>
+
+namespace Nz
+{
+	class NAZARA_CORE_API SystemGraph
+	{
+		public:
+			inline SystemGraph(entt::registry& registry);
+			SystemGraph(const SystemGraph&) = delete;
+			SystemGraph(SystemGraph&&) = delete;
+			~SystemGraph() = default;
+
+			template<typename T, typename... Args> T& AddSystem(Args&&... args);
+
+			template<typename T> T& GetSystem() const;
+
+			void Update();
+			void Update(float elapsedTime);
+
+			SystemGraph& operator=(const SystemGraph&) = delete;
+			SystemGraph& operator=(SystemGraph&&) = delete;
+
+		private:
+			struct NAZARA_CORE_API NodeBase
+			{
+				virtual ~NodeBase();
+
+				virtual void Update(float elapsedTime) = 0;
+
+				Int64 executionOrder;
+			};
+
+			template<typename T>
+			struct Node : NodeBase
+			{
+				template<typename... Args> Node(Args&&... args);
+
+				void Update(float elapsedTime) override;
+
+				T system;
+			};
+
+			std::unordered_map<entt::id_type, std::size_t /*nodeIndex*/> m_systemToNodes;
+			std::vector<NodeBase*> m_orderedNodes;
+			std::vector<std::unique_ptr<NodeBase>> m_nodes;
+			entt::registry& m_registry;
+			Nz::Clock m_clock;
+			bool m_systemOrderUpdated;
+	};
+}
+
+#include <Nazara/Core/Systems/SystemGraph.inl>
+
+#endif // NAZARA_CORE_SYSTEMS_SYSTEMGRAPH_HPP

include/Nazara/Core/Systems/SystemGraph.inl

@@ -0,0 +1,74 @@
+// Copyright (C) 2022 Jérôme "Lynix" Leclercq (lynix680@gmail.com)
+// This file is part of the "Nazara Engine - Core module"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#include <Nazara/Core/Systems/SystemGraph.hpp>
+#include <Nazara/Core/Error.hpp>
+#include <stdexcept>
+#include <Nazara/Core/Debug.hpp>
+
+namespace Nz
+{
+	namespace Detail
+	{
+		template<typename, typename = void>
+		struct SystemGraphAllowConcurrent : std::bool_constant<true> {};
+
+		template<typename T>
+		struct SystemGraphAllowConcurrent<T, std::void_t<decltype(T::AllowConcurrent)>> : std::bool_constant<T::AllowConcurrent> {};
+
+		template<typename, typename = void>
+		struct SystemGraphExecutionOrder : std::integral_constant<Int64, 0> {};
+
+		template<typename T>
+		struct SystemGraphExecutionOrder<T, std::void_t<decltype(T::ExecutionOrder)>> : std::integral_constant<Int64, T::ExecutionOrder> {};
+	}
+
+	template<typename T>
+	template<typename... Args>
+	SystemGraph::Node<T>::Node(Args&&... args) :
+	system(std::forward<Args>(args)...)
+	{
+	}
+
+	template<typename T>
+	void SystemGraph::Node<T>::Update(float elapsedTime)
+	{
+		system.Update(elapsedTime);
+	}
+
+	inline SystemGraph::SystemGraph(entt::registry& registry) :
+	m_registry(registry),
+	m_systemOrderUpdated(true)
+	{
+	}
+
+	template<typename T, typename... Args>
+	T& SystemGraph::AddSystem(Args&&... args)
+	{
+		NazaraAssert(m_systemToNodes.find(entt::type_hash<T>()) == m_systemToNodes.end(), "this system already exists");
+
+		auto nodePtr = std::make_unique<Node<T>>(m_registry, std::forward<Args>(args)...);
+		nodePtr->executionOrder = Detail::SystemGraphExecutionOrder<T>();
+
+		T& system = nodePtr->system;
+
+		m_nodes.emplace_back(std::move(nodePtr));
+		m_systemOrderUpdated = false;
+
+		return system;
+	}
+
+	template<typename T>
+	T& SystemGraph::GetSystem() const
+	{
+		auto it = m_systemToNodes.find(entt::type_hash<T>());
+		if (it == m_systemToNodes.end())
+			throw std::runtime_error("this system is not part of the graph");
+
+		auto& node = static_cast<Node<T>&>(*m_nodes[it->second]);
+		return node.system;
+	}
+}
+
+#include <Nazara/Core/DebugOff.hpp>