descriptorTag.h

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/*  This file is part of the OpenLB library
 *
 *  Copyright (C) 2019 Adrian Kummerlaender
 *  E-mail contact: info@openlb.net
 *  The most recent release of OpenLB can be downloaded at
 *  <http://www.openlb.net/>
 *
 *  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 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public
 *  License along with this program; if not, write to the Free
 *  Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA  02110-1301, USA.
*/
 
#ifndef DESCRIPTOR_TAG_H
#define DESCRIPTOR_TAG_H
 
#include "core/meta.h"
 
namespace olb {
 
namespace descriptors {
 
// *INDENT-OFF*
 
 
 
struct DESCRIPTOR_TAG {
  template <unsigned, unsigned>
  static constexpr unsigned size()
  {
    return 0; // a tag doesn't have a size
  }
 
  template <typename T>
  using value_type = void;
};
 
template <typename FIELD>
using is_tag_field = std::is_base_of<DESCRIPTOR_TAG, FIELD>;
 
namespace tag {
 
 
struct CATEGORY { };
 
struct DEFAULT : public CATEGORY, public DESCRIPTOR_TAG { };
 
 
template <typename BASE, typename FALLBACK, typename... FIELDS>
using field_with_base = typename std::conditional<
  std::is_void<typename meta::first_type_with_base<BASE, FIELDS...>::type>::value,
  FALLBACK,
  typename meta::first_type_with_base<BASE, FIELDS...>::type
>::type;
 
}
 
 
}
 
}
 
#endif