Core: Add StateMachine

Backported from legacy Nazara

include/Nazara/Core/StateMachine.hpp

@@ -0,0 +1,62 @@
+// Copyright (C) 2023 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_STATEMACHINE_HPP
+#define NAZARA_CORE_STATEMACHINE_HPP
+
+#include <NazaraUtils/Prerequisites.hpp>
+#include <Nazara/Core/State.hpp>
+#include <Nazara/Core/Time.hpp>
+#include <memory>
+#include <vector>
+
+namespace Nz
+{
+	class StateMachine
+	{
+		public:
+			inline StateMachine(std::shared_ptr<State> originalState);
+			StateMachine(const StateMachine&) = delete;
+			inline StateMachine(StateMachine&& fsm) = default;
+			inline ~StateMachine();
+
+			inline void ChangeState(std::shared_ptr<State> state);
+
+			inline bool IsTopState(const State* state) const;
+
+			inline void PopState();
+			inline void PopStatesUntil(std::shared_ptr<State> state);
+			inline void PushState(std::shared_ptr<State> state);
+
+			inline void ResetState(std::shared_ptr<State> state);
+
+			inline bool Update(Time elapsedTime);
+
+			inline StateMachine& operator=(StateMachine&& fsm) = default;
+			StateMachine& operator=(const StateMachine&) = delete;
+
+		private:
+			enum class TransitionType
+			{
+				Pop,
+				PopUntil,
+				Push,
+			};
+
+			struct StateTransition
+			{
+				TransitionType type;
+				std::shared_ptr<State> state;
+			};
+
+			std::vector<std::shared_ptr<State>> m_states;
+			std::vector<StateTransition> m_transitions;
+	};
+}
+
+#include <Nazara/Core/StateMachine.inl>
+
+#endif // NAZARA_CORE_STATEMACHINE_HPP