synchronous_iterator.h

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// ------------------------------------------------------------------------
//
// SPDX-License-Identifier: LGPL-2.1-or-later
// Copyright (C) 2009 - 2021 by the deal.II authors
//
// This file is part of the deal.II library.
//
// Part of the source code is dual licensed under Apache-2.0 WITH
// LLVM-exception OR LGPL-2.1-or-later. Detailed license information
// governing the source code and code contributions can be found in
// LICENSE.md and CONTRIBUTING.md at the top level directory of deal.II.
//
// ------------------------------------------------------------------------
 
#ifndef dealii_synchronous_iterator_h
#define dealii_synchronous_iterator_h
 
 
#include <deal.II/base/config.h>
 
#include <deal.II/base/exceptions.h>
 
#include <iterator>
#include <tuple>
 
DEAL_II_NAMESPACE_OPEN
 
template <typename Iterators>
struct SynchronousIterators
{
  SynchronousIterators(const Iterators &i);
 
  const Iterators &
  operator*() const;
 
  Iterators &
  operator*();
 
  using difference_type   = std::size_t;
  using iterator_category = std::bidirectional_iterator_tag;
  using value_type        = Iterators;
  using pointer           = Iterators *;
  using reference         = Iterators &;
 
private:
  Iterators iterators;
};
 
 
 
template <typename Iterators>
inline SynchronousIterators<Iterators>::SynchronousIterators(const Iterators &i)
  : iterators(i)
{}
 
 
 
template <typename Iterators>
inline const Iterators &
SynchronousIterators<Iterators>::operator*() const
{
  return iterators;
}
 
 
 
template <typename Iterators>
inline Iterators &
SynchronousIterators<Iterators>::operator*()
{
  return iterators;
}
 
 
 
template <typename Iterators>
inline bool
operator<(const SynchronousIterators<Iterators> &a,
          const SynchronousIterators<Iterators> &b)
{
  return std::get<0>(*a) < std::get<0>(*b);
}
 
 
 
template <typename Iterators>
inline std::size_t
operator-(const SynchronousIterators<Iterators> &a,
          const SynchronousIterators<Iterators> &b)
{
  Assert(std::distance(std::get<0>(*b), std::get<0>(*a)) >= 0,
         ExcInternalError());
  return std::distance(std::get<0>(*b), std::get<0>(*a));
}
 
 
template <typename I1, typename I2>
inline void
advance(std::tuple<I1, I2> &t, const unsigned int n)
{
  std::advance(std::get<0>(t), n);
  std::advance(std::get<1>(t), n);
}
 
template <typename I1, typename I2, typename I3>
inline void
advance(std::tuple<I1, I2, I3> &t, const unsigned int n)
{
  std::advance(std::get<0>(t), n);
  std::advance(std::get<1>(t), n);
  std::advance(std::get<2>(t), n);
}
 
template <typename I1, typename I2, typename I3, typename I4>
inline void
advance(std::tuple<I1, I2, I3, I4> &t, const unsigned int n)
{
  std::advance(std::get<0>(t), n);
  std::advance(std::get<1>(t), n);
  std::advance(std::get<2>(t), n);
  std::advance(std::get<3>(t), n);
}
 
template <typename I1, typename I2>
inline void
prev(std::tuple<I1, I2> &t)
{
  --std::get<0>(t);
  --std::get<1>(t);
}
 
template <typename I1, typename I2, typename I3>
inline void
prev(std::tuple<I1, I2, I3> &t)
{
  --std::get<0>(t);
  --std::get<1>(t);
  --std::get<2>(t);
}
 
template <typename I1, typename I2, typename I3, typename I4>
inline void
prev(std::tuple<I1, I2, I3, I4> &t)
{
  --std::get<0>(t);
  --std::get<1>(t);
  --std::get<2>(t);
  --std::get<3>(t);
}
 
template <typename I1, typename I2>
inline void
advance_by_one(std::tuple<I1, I2> &t)
{
  ++std::get<0>(t);
  ++std::get<1>(t);
}
 
template <typename I1, typename I2, typename I3>
inline void
advance_by_one(std::tuple<I1, I2, I3> &t)
{
  ++std::get<0>(t);
  ++std::get<1>(t);
  ++std::get<2>(t);
}
 
template <typename I1, typename I2, typename I3, typename I4>
inline void
advance_by_one(std::tuple<I1, I2, I3, I4> &t)
{
  ++std::get<0>(t);
  ++std::get<1>(t);
  ++std::get<2>(t);
  ++std::get<3>(t);
}
 
template <typename Iterators>
inline SynchronousIterators<Iterators>
operator+(const SynchronousIterators<Iterators> &a, const std::size_t n)
{
  SynchronousIterators<Iterators> x(a);
  ::advance(*x, n);
  return x;
}
 
template <typename Iterators>
inline SynchronousIterators<Iterators> &
operator++(SynchronousIterators<Iterators> &a)
{
  ::advance_by_one(*a);
  return a;
}
 
template <typename Iterators>
inline SynchronousIterators<Iterators> &
operator--(SynchronousIterators<Iterators> &a)
{
  ::prev(*a);
  return a;
}
 
template <typename Iterators>
inline SynchronousIterators<Iterators>
operator++(SynchronousIterators<Iterators> &a, int)
{
  SynchronousIterators<Iterators> b = a;
  ::advance_by_one(*a);
  return b;
}
 
template <typename Iterators>
inline bool
operator!=(const SynchronousIterators<Iterators> &a,
           const SynchronousIterators<Iterators> &b)
{
  return (std::get<0>(*a) != std::get<0>(*b));
}
 
DEAL_II_NAMESPACE_CLOSE
 
#endif