Singleton.h

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/*
    ------------------------------------------------------------------------------------
    LICENSE:
    ------------------------------------------------------------------------------------
    This file is part of EVEmu: EVE Online Server Emulator
    Copyright 2006 - 2021 The EVEmu Team
    For the latest information visit https://evemu.dev
    ------------------------------------------------------------------------------------
    This program is free software; you can redistribute it and/or modify it under
    the terms of the GNU Lesser General Public License as published by the Free Software
    Foundation; either version 2 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 Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License along with
    this program; if not, write to the Free Software Foundation, Inc., 59 Temple
    Place - Suite 330, Boston, MA 02111-1307, USA, or go to
    http://www.gnu.org/copyleft/lesser.txt.
    ------------------------------------------------------------------------------------
    Author:        Bloody.Rabbit
*/

#ifndef __UTILS__SINGLETON_H__INCL__
#define __UTILS__SINGLETON_H__INCL__
#include <memory>

template<typename X>
class Singleton
{
public:
    Singleton()
    {
        assert(mInstance.get() == nullptr);
    }

    static X& get()
    {
        if (mInstance.get() == nullptr)
            mInstance.reset( new X );

        return *mInstance;
    }

protected:
    static std::shared_ptr<X> mInstance;
};

template<typename X>
std::shared_ptr<X> Singleton<X>::mInstance( nullptr );

#endif /* !__UTILS__SINGLETON_H__INCL__ */