// =====================================================================================================================
//  fennec, a free and open source game engine
//  Copyright © 2025 - 2026  Medusa Slockbower
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
// =====================================================================================================================

///
/// \file fennec/rtti/singleton.h
/// \brief
///
///
/// \details
/// \author Medusa Slockbower
///
/// \copyright Copyright © 2025 - 2026 Medusa Slockbower ([GPLv3](https://www.gnu.org/licenses/gpl-3.0.en.html))
///
///

#ifndef FENNEC_RTTI_SINGLETON_H
#define FENNEC_RTTI_SINGLETON_H

#include <fennec/lang/type_traits.h>

namespace fennec
{

///
/// \brief Interface for defining a singleton instance
/// \tparam T The type of the singleton
template<typename T>
struct singleton {

// Instance Acquisition ================================================================================================
public:

	/// \name Instance Acquisition
	/// @{

	///
	/// \brief Acquire the singleton instance.
	/// \returns A reference to the instance.
	static T& instance() requires(is_pointer_v<T>) {
		static T instance = nullptr;
		return instance;
	}

	///
	/// \brief Acquire the singleton instance.
	/// \returns A reference to the instance.
	static T& instance() requires(not is_pointer_v<T>) {
		static T instance;
		return instance;
	}

	/// @}
};

}

#endif // FENNEC_RTTI_SINGLETON_H