matrix_iterator.h

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// -----------------------------------------------------------------------------
//
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception OR LGPL-2.1-or-later
// Copyright (C) 2006 - 2025 by the deal.II authors
//
// This file is part of the deal.II library.
//
// Detailed license information governing the source code and contributions
// can be found in LICENSE.md and CONTRIBUTING.md at the top level directory.
//
// -----------------------------------------------------------------------------
 
#ifndef dealii_matrix_iterator_h
#define dealii_matrix_iterator_h
 
 
#include <deal.II/base/config.h>
 
#include <deal.II/base/exceptions.h>
#include <deal.II/base/types.h>
 
DEAL_II_NAMESPACE_OPEN

template <typename AccessorType>
class MatrixIterator
{
public:
  using size_type = types::global_dof_index;

  using MatrixType = typename AccessorType::MatrixType;

  MatrixIterator(MatrixType     *matrix,
                 const size_type row   = 0,
                 const size_type index = 0);

  template <class OtherAccessorType>
  MatrixIterator(const MatrixIterator<OtherAccessorType> &other);

  MatrixIterator &
  operator++();

  MatrixIterator
  operator++(int);

  const AccessorType &
  operator*() const;

  const AccessorType *
  operator->() const;

  template <class OtherAccessorType>
  bool
  operator==(const MatrixIterator<OtherAccessorType> &) const;

  template <class OtherAccessorType>
  bool
  operator!=(const MatrixIterator<OtherAccessorType> &) const;

  bool
  operator<(const MatrixIterator &) const;

  bool
  operator>(const MatrixIterator &) const;
 
private:
  AccessorType accessor;
 
  // Allow other iterators access to private data.
  template <class OtherAccessorType>
  friend class MatrixIterator;
};
 
 
//----------------------------------------------------------------------//
 
template <typename AccessorType>
inline MatrixIterator<AccessorType>::MatrixIterator(MatrixType     *matrix,
                                                    const size_type r,
                                                    const size_type i)
  : accessor(matrix, r, i)
{}
 
 
template <typename AccessorType>
template <class OtherAccessorType>
inline MatrixIterator<AccessorType>::MatrixIterator(
  const MatrixIterator<OtherAccessorType> &other)
  : accessor(other.accessor)
{}
 
 
template <typename AccessorType>
inline MatrixIterator<AccessorType> &
MatrixIterator<AccessorType>::operator++()
{
  accessor.advance();
  return *this;
}
 
 
template <typename AccessorType>
inline MatrixIterator<AccessorType>
MatrixIterator<AccessorType>::operator++(int)
{
  const MatrixIterator iter = *this;
  accessor.advance();
  return iter;
}
 
 
template <typename AccessorType>
inline const AccessorType &
MatrixIterator<AccessorType>::operator*() const
{
  return accessor;
}
 
 
template <typename AccessorType>
inline const AccessorType *
MatrixIterator<AccessorType>::operator->() const
{
  return &accessor;
}
 
 
template <typename AccessorType>
template <class OtherAccessorType>
inline bool
MatrixIterator<AccessorType>::operator==(
  const MatrixIterator<OtherAccessorType> &other) const
{
  return (accessor == other.accessor);
}
 
 
template <typename AccessorType>
template <class OtherAccessorType>
inline bool
MatrixIterator<AccessorType>::operator!=(
  const MatrixIterator<OtherAccessorType> &other) const
{
  return !(*this == other);
}
 
 
template <typename AccessorType>
inline bool
MatrixIterator<AccessorType>::operator<(const MatrixIterator &other) const
{
  Assert(&accessor.get_matrix() == &other.accessor.get_matrix(),
         ExcInternalError());
 
  return (accessor < other.accessor);
}
 
 
template <typename AccessorType>
inline bool
MatrixIterator<AccessorType>::operator>(const MatrixIterator &other) const
{
  return (other < *this);
}
 
DEAL_II_NAMESPACE_CLOSE
 
#endif