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/* Copyright (C) 2019 Wildfire Games.
* This file is part of 0 A.D.
*
* 0 A.D. 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 2 of the License, or
* (at your option) any later version.
*
* 0 A.D. 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 0 A.D. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef INCLUDED_SINGLETON
#define INCLUDED_SINGLETON
#include "lib/debug.h"
/**
* Template base class for singletons.
*
* Usage:
* class MyClass : public Singleton<MyClass> {};
* MyClass::GetSingleton().MyMethod();
*
* Modified from http://gamedev.net/reference/articles/article1954.asp
*/
template<typename T>
class Singleton
{
NONCOPYABLE(Singleton);
public:
Singleton()
{
ENSURE(!ms_singleton);
ms_singleton = static_cast<T*>(this);
}
~Singleton()
{
ENSURE(ms_singleton);
ms_singleton = nullptr;
}
static T& GetSingleton()
{
ENSURE(ms_singleton);
return *ms_singleton;
}
static T* GetSingletonPtr()
{
ENSURE(ms_singleton);
return ms_singleton;
}
static bool IsInitialised()
{
return ms_singleton != nullptr;
}
private:
static T* ms_singleton;
};
template <typename T>
T* Singleton<T>::ms_singleton = nullptr;
#endif // INCLUDED_SINGLETON
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