Magic_Game/core/base/Singleton.hpp

// Copyright (c) 2016-2018 Easy2D - Nomango
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#pragma once
#include <memory>

namespace easy2d
{
	template <typename T>
	class ISingleton
	{
	public:
		static inline T& Instance();

		static inline void Destroy();

	private:
		ISingleton() {}

		~ISingleton() {}

		ISingleton(const ISingleton&) = delete;

		ISingleton & operator= (const ISingleton &) = delete;

		static std::unique_ptr<T> instance_;
	};

	template<typename T>
	inline T & easy2d::ISingleton<T>::Instance()
	{
		if (!instance_)
			instance_.reset(new (std::nothrow) T);
		return *instance_;
	}

	template<typename T>
	inline void easy2d::ISingleton<T>::Destroy()
	{
		if (instance_)
			instance_.reset();
	}

	template<typename T>
	std::unique_ptr<T> easy2d::ISingleton<T>::instance_;
}

// Class that will implement the singleton mode,
// must use the macro in it's delare file

#ifndef E2D_DECLARE_SINGLETON
#define E2D_DECLARE_SINGLETON( type )			\
	friend class ::std::unique_ptr< type >;		\
	friend struct ::std::default_delete< type >;\
	friend class ::easy2d::ISingleton< type >
#endif

#ifndef E2D_DECLARE_SINGLETON_TYPE
#define E2D_DECLARE_SINGLETON_TYPE( type, singleton_type ) using singleton_type = ::easy2d::ISingleton< type >
#endif