//============================================================================
//  Copyright (c) Kitware, Inc.
//  All rights reserved.
//  See LICENSE.txt for details.
//  This software is distributed WITHOUT ANY WARRANTY; without even
//  the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
//  PURPOSE.  See the above copyright notice for more information.
//
//  Copyright 2015 Sandia Corporation.
//  Copyright 2015 UT-Battelle, LLC.
//  Copyright 2015 Los Alamos National Security.
//
//  Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
//  the U.S. Government retains certain rights in this software.
//
//  Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
//  Laboratory (LANL), the U.S. Government retains certain rights in
//  this software.
//============================================================================
#ifndef vtk_m_TopologyElementTag_h
#define vtk_m_TopologyElementTag_h

#include <vtkm/Types.h>

namespace vtkm {

/// \brief A tag used to identify the cell elements in a topology.
///
/// A topology element refers to some type of substructure of a topology. For
/// example, a 3D mesh has points, edges, faces, and cells. Each of these is an
/// example of a topology element and has its own tag.
///
struct TopologyElementTagCell {  };

/// \brief A tag used to identify the point elements in a topology.
///
/// A topology element refers to some type of substructure of a topology. For
/// example, a 3D mesh has points, edges, faces, and cells. Each of these is an
/// example of a topology element and has its own tag.
///
struct TopologyElementTagPoint {  };

/// \brief A tag used to identify the edge elements in a topology.
///
/// A topology element refers to some type of substructure of a topology. For
/// example, a 3D mesh has points, edges, faces, and cells. Each of these is an
/// example of a topology element and has its own tag.
///
struct TopologyElementTagEdge {  };

/// \brief A tag used to identify the face elements in a topology.
///
/// A topology element refers to some type of substructure of a topology. For
/// example, a 3D mesh has points, edges, faces, and cells. Each of these is an
/// example of a topology element and has its own tag.
///
struct TopologyElementTagFace {  };


namespace internal {

/// Checks to see if the given object is a topology element tag.This check is
/// compatible with C++11 type_traits.
/// It contains a typedef named \c type that is either std::true_type or
/// std::false_type. Both of these have a typedef named value with the
/// respective boolean value.
///
template<typename T>
struct TopologyElementTagCheck : std::false_type
{
};

template<>
struct TopologyElementTagCheck<vtkm::TopologyElementTagCell> : std::true_type
{
};

template<>
struct TopologyElementTagCheck<vtkm::TopologyElementTagPoint> : std::true_type
{
};

template<>
struct TopologyElementTagCheck<vtkm::TopologyElementTagEdge> : std::true_type
{
};

template<>
struct TopologyElementTagCheck<vtkm::TopologyElementTagFace> : std::true_type
{
};


#define VTKM_IS_TOPOLOGY_ELEMENT_TAG(type) \
  static_assert( ::vtkm::internal::TopologyElementTagCheck<type>::value, \
                  "Invalid Topology Element Tag being used")

} // namespace internal

} // namespace vtkm

#endif //vtk_m_TopologyElementTag_h