// Copyright (c) 2016-2020 Kiwano - 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

namespace kiwano
{

template <typename _Ty>
struct Singleton
{
protected:
    Singleton()                 = default;
    Singleton(const Singleton&) = delete;
    Singleton& operator=(const Singleton&) = delete;

private:
    struct ObjectCreator
    {
        ObjectCreator()
        {
            (void)Singleton<_Ty>::GetInstance();
        }

        inline void Dummy() const {}
    };
    static ObjectCreator creator_;

public:
    using object_type = _Ty;

    static inline object_type& GetInstance()
    {
        static object_type instance;
        creator_.Dummy();
        return instance;
    }
};

template <typename _Ty>
typename Singleton<_Ty>::ObjectCreator Singleton<_Ty>::creator_;

}  // namespace kiwano
