// Copyright (c) 2014 GeometryFactory Sarl (France)
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 3 of the License,
// or (at your option) any later version.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL: https://github.com/CGAL/cgal/blob/releases/CGAL-4.14.3/STL_Extension/include/CGAL/Has_timestamp.h $
// $Id: Has_timestamp.h 8cdfad0 2017-11-15T22:58:57+01:00 Sébastien Loriot
// SPDX-License-Identifier: LGPL-3.0+
//
// Author(s)     : Jane Tournois

#ifndef CGAL_HAS_TIMESTAMP_H
#define CGAL_HAS_TIMESTAMP_H

#include <boost/mpl/has_xxx.hpp>
#include <CGAL/tags.h>

namespace CGAL {

namespace internal {

  BOOST_MPL_HAS_XXX_TRAIT_DEF(Has_timestamp)

  // Used by Compact container to make the comparison of iterator
  // depending on the insertion order rather than the object address
  // when the object class defines a Has_timestamp tag
  // This is for example used in to make Mesh_3 deterministic, see
  // classes implementing concepts MeshCellBase_3 and MeshVertexBase_3
  template <typename T, bool has_ts = has_Has_timestamp<T>::value>
  struct Has_timestamp : public T::Has_timestamp
    // when T has a Has_timestamp tag
  {};

  template <typename T>
  struct Has_timestamp<T, false> : public Tag_false
    // when T does not have a Has_timestamp tag
  {};

} // end namespace internal
} // end namespace CGAL

#endif // CGAL_HAS_TIMESTAMP_H
