Singleton.h

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/*
 * i6engine
 * Copyright (2016) Daniel Bonrath, Michael Baer, All rights reserved.
 *
 * This file is part of i6engine; i6engine 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 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

#ifndef __I6ENGINE_UTILS_SINGLETON_H__
#define __I6ENGINE_UTILS_SINGLETON_H__

#include "boost/interprocess/sync/scoped_lock.hpp"
#include "boost/make_shared.hpp"
#include "boost/thread/mutex.hpp"

namespace i6e {
namespace utils {

        template<typename T, typename... Dependencies>
        class Singleton {
        public:
                static inline T * GetSingletonPtr() {
                        return Init().get();
                }

                static inline T & GetSingleton() {
                        return *Init();
                }

        protected:
                Singleton() {
                }

                virtual ~Singleton() {
                }

        private:
                template<typename... B>
                struct InitDependencies {
                        InitDependencies() {
                        }
                        static void Init() {
                        }
                };

                template<typename A, typename... B>
                struct InitDependencies<A, B...> {
                        InitDependencies() {
                                Init();
                        }
                        ~InitDependencies() {
                        }
                        static void Init() {
                                A::GetSingleton();
                                InitDependencies<B...>::Init();
                        }
                };

                static boost::shared_ptr<T> & Init() {
                        static const InitDependencies<Dependencies...> id;
                        static boost::shared_ptr<T> _ptrSingleton = boost::shared_ptr<T>(new T());
                        return _ptrSingleton;
                }

                Singleton(const Singleton &) = delete;

                const Singleton & operator=(const Singleton &) = delete;
        };

} /* namespace utils */
} /* namespace i6e */

#endif /* __I6ENGINE_UTILS_SINGLETON_H__ */