first_enabled.hpp

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/*=============================================================================
  Copyright (C) 2015-2017 DxLibEx project
  https://github.com/Nagarei/DxLibEx/

  Distributed under the Boost Software License, Version 1.0.
  (See http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#ifndef DXLE_INC_TYPE_TRAITS_FIRST_ENABLED_HPP_
#define DXLE_INC_TYPE_TRAITS_FIRST_ENABLED_HPP_
#include <type_traits>
namespace dxle {
namespace type_traits {

    template<typename ...Args>
    struct first_enabled {};

    template<typename T, typename ...Args>
    struct first_enabled<std::enable_if<true, T>, Args...> { using type = T; };
    template<typename T, typename ...Args>
    struct first_enabled<std::enable_if<false, T>, Args...> : first_enabled<Args...> {};
    template<typename T, typename ...Args>
    struct first_enabled<T, Args...> { using type = T; };

    template<typename ...Args>
    using first_enabled_t = typename first_enabled<Args...>::type;

}//namespace
using namespace type_traits;
}
#endif //DXLE_INC_TYPE_TRAITS_FIRST_ENABLED_HPP_