elem_hash.h

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// The libMesh Finite Element Library.
// Copyright (C) 2002-2026 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner
 
// This library is free software; 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 2.1 of the License, or (at your option) any later version.
 
// This library 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
// Lesser General Public License for more details.
 
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
#ifndef LIBMESH_ELEM_HASH_H
#define LIBMESH_ELEM_HASH_H
 
#include "elem.h"
 
// C++ includes
#include <unordered_set>
 
// This header defines some typedefs that are useful for working with
// "unordered" containers of Elem * that use Elem::key() as a hash
// function.
namespace libMesh
{
 
struct ElemHashUtils
{
public:
  inline
  std::size_t operator()(const Elem * elem) const
  {
    return cast_int<std::size_t>(elem->key());
  }
 
  inline
  bool operator()(const Elem * lhs, const Elem * rhs) const
  {
    return lhs->key() == rhs->key();
  }
};
 
// A convenient type for working with unordered_multiset<Elem *>
typedef std::unordered_multiset<Elem *, ElemHashUtils, ElemHashUtils> unordered_multiset_elem;
 
}
 
#endif