null_output_iterator.h

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// The libMesh Finite Element Library.
// Copyright (C) 2002-2025 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_NULL_OUTPUT_ITERATOR_H
#define LIBMESH_NULL_OUTPUT_ITERATOR_H

// Local includes

// C++ includes
#include <iterator>

namespace libMesh
{

template <typename T>
struct null_output_iterator
{
  using iterator_category = std::output_iterator_tag;
  using value_type = T;
  using difference_type = std::ptrdiff_t;
  using pointer = T*;
  using reference = T&;

  template <typename T2>
  void operator=(const T2&) {}

  null_output_iterator & operator++()
  {
    return *this;
  }

  null_output_iterator operator++(int)
  {
    return null_output_iterator(*this);
  }

  // We don't return a reference-to-T here because we don't want to
  // construct one or have any of its methods called.
  null_output_iterator & operator*() { return *this; }
};

} // namespace libMesh


#endif // LIBMESH_NULL_OUTPUT_ITERATOR_H