linear_index_iterator.h

// ---------------------------------------------------------------------
//
// Copyright (C) 2018 by the deal.II authors
//
// This file is part of the deal.II library.
//
// The deal.II library is free software; you can use it, 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.
// The full text of the license can be found in the file LICENSE.md at
// the top level directory of deal.II.
//
// ---------------------------------------------------------------------

#ifndef dealii_linear_index_iterator_h
#define dealii_linear_index_iterator_h

#include <deal.II/base/config.h>

#include <deal.II/base/exceptions.h>


DEAL_II_NAMESPACE_OPEN
template <class DerivedIterator, class AccessorType>
class LinearIndexIterator
{
public:
  using iterator_category = std::random_access_iterator_tag;

  using value_type = AccessorType;

  using difference_type = std::ptrdiff_t;

  using reference = const value_type &;

  using pointer = const value_type *;

  using size_type = typename value_type::size_type;

  DerivedIterator &
  operator=(const DerivedIterator &it);

  DerivedIterator &
  operator++();

  DerivedIterator
  operator++(int);

  DerivedIterator &
  operator--();

  DerivedIterator
  operator--(int);

  DerivedIterator
  operator+(const difference_type n) const;

  DerivedIterator
  operator-(const difference_type n) const;

  DerivedIterator &
  operator+=(const difference_type n);

  DerivedIterator &
  operator-=(const difference_type n);

  difference_type
  operator-(const DerivedIterator &p) const;

  reference operator*() const;

  pointer operator->() const;

  bool
  operator==(const DerivedIterator &) const;

  bool
  operator!=(const DerivedIterator &) const;

  bool
  operator<=(const DerivedIterator &) const;

  bool
  operator>=(const DerivedIterator &) const;

  bool
  operator<(const DerivedIterator &) const;

  bool
  operator>(const DerivedIterator &) const;

protected:
  LinearIndexIterator() = default;

  LinearIndexIterator(const AccessorType accessor);

protected:
  AccessorType accessor;
};



template <class DerivedIterator, class AccessorType>
inline DerivedIterator &
LinearIndexIterator<DerivedIterator, AccessorType>::
operator=(const DerivedIterator &it)
{
  accessor.container    = it.container;
  accessor.linear_index = it.linear_index;
  return static_cast<DerivedIterator &>(*this);
}



template <class DerivedIterator, class AccessorType>
inline DerivedIterator &
LinearIndexIterator<DerivedIterator, AccessorType>::operator++()
{
  return operator+=(1);
}



template <class DerivedIterator, class AccessorType>
inline DerivedIterator
LinearIndexIterator<DerivedIterator, AccessorType>::operator++(int)
{
  const DerivedIterator copy(this->accessor);
                        operator+=(1);
  return copy;
}



template <class DerivedIterator, class AccessorType>
inline DerivedIterator &
LinearIndexIterator<DerivedIterator, AccessorType>::operator--()
{
  return operator+=(-1);
}



template <class DerivedIterator, class AccessorType>
inline DerivedIterator
LinearIndexIterator<DerivedIterator, AccessorType>::operator--(int)
{
  const DerivedIterator copy(this->accessor);
                        operator+=(-1);
  return copy;
}



template <class DerivedIterator, class AccessorType>
inline DerivedIterator
LinearIndexIterator<DerivedIterator, AccessorType>::
operator+(const difference_type n) const
{
  DerivedIterator copy(this->accessor);
  copy += n;
  return copy;
}



template <class DerivedIterator, class AccessorType>
inline DerivedIterator
LinearIndexIterator<DerivedIterator, AccessorType>::
operator-(const difference_type n) const
{
  DerivedIterator copy(this->accessor);
  copy += -n;
  return copy;
}



template <class DerivedIterator, class AccessorType>
inline DerivedIterator &
LinearIndexIterator<DerivedIterator, AccessorType>::
operator+=(const difference_type n)
{
  accessor.linear_index += n;
  return static_cast<DerivedIterator &>(*this);
}



template <class DerivedIterator, class AccessorType>
inline DerivedIterator &
LinearIndexIterator<DerivedIterator, AccessorType>::
operator-=(const difference_type n)
{
  return operator+=(-n);
}



template <class DerivedIterator, class AccessorType>
inline
  typename LinearIndexIterator<DerivedIterator, AccessorType>::difference_type
  LinearIndexIterator<DerivedIterator, AccessorType>::
  operator-(const DerivedIterator &other) const
{
  Assert(this->accessor.container == other.accessor.container,
         ExcMessage(
           "Only iterators pointing to the same container can be compared."));
  return this->accessor.linear_index - other.accessor.linear_index;
}



template <class DerivedIterator, class AccessorType>
inline typename LinearIndexIterator<DerivedIterator, AccessorType>::reference
  LinearIndexIterator<DerivedIterator, AccessorType>::operator*() const
{
  return accessor;
}



template <class DerivedIterator, class AccessorType>
inline typename LinearIndexIterator<DerivedIterator, AccessorType>::pointer
  LinearIndexIterator<DerivedIterator, AccessorType>::operator->() const
{
  return &accessor;
}



template <class DerivedIterator, class AccessorType>
inline bool
LinearIndexIterator<DerivedIterator, AccessorType>::
operator==(const DerivedIterator &other) const
{
  const auto &other_2 = static_cast<decltype(*this) &>(other);
  return accessor.container == other_2.accessor.container &&
         accessor.linear_index == other_2.accessor.linear_index;
}



template <class DerivedIterator, class AccessorType>
inline bool
LinearIndexIterator<DerivedIterator, AccessorType>::
operator!=(const DerivedIterator &other) const
{
  return !(*this == other);
}



template <class DerivedIterator, class AccessorType>
inline bool
LinearIndexIterator<DerivedIterator, AccessorType>::
operator<=(const DerivedIterator &other) const
{
  return (*this == other) || (*this < other);
}



template <class DerivedIterator, class AccessorType>
inline bool
LinearIndexIterator<DerivedIterator, AccessorType>::
operator>=(const DerivedIterator &other) const
{
  return !(*this < other);
}



template <class DerivedIterator, class AccessorType>
inline bool
LinearIndexIterator<DerivedIterator, AccessorType>::
operator<(const DerivedIterator &other) const
{
  Assert(this->accessor.container == other.accessor.container,
         ExcMessage(
           "Only iterators pointing to the same container can be compared."));
  return this->accessor.linear_index < other.accessor.linear_index;
}



template <class DerivedIterator, class AccessorType>
inline bool
LinearIndexIterator<DerivedIterator, AccessorType>::
operator>(const DerivedIterator &other) const
{
  return other < *this;
}



template <class DerivedIterator, class AccessorType>
inline LinearIndexIterator<DerivedIterator, AccessorType>::LinearIndexIterator(
  const AccessorType accessor)
  : accessor(accessor)
{}


DEAL_II_NAMESPACE_CLOSE

#endif