defines_type.hpp

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// This file is a part of NiHu, a C++ BEM template library.
//
// Copyright (C) 2012-2014  Peter Fiala <fiala@hit.bme.hu>
// Copyright (C) 2012-2014  Peter Rucz <rucz@hit.bme.hu>
//
// This program 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 3 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
#ifndef DEFINES_TYPE_HPP_INCLUDED
#define DEFINES_TYPE_HPP_INCLUDED
 
#include <type_traits>
 
namespace internal
{
    template <class C>
    struct voidize { typedef void type; };
}
 
#define DEFINES_TYPE(TYPE)                              \
template <class C, class = void>                        \
struct defines_##TYPE : std::false_type {};             \
template <class C>                                      \
                                                        \
struct defines_##TYPE <                                 \
    C,                                                  \
    typename internal::voidize<typename C::TYPE>::type  \
> : std::true_type { };
 
#endif // DEFINES_TYPE_HPP_INCLUDED