vector_slice.h

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// ---------------------------------------------------------------------
//
// Copyright (C) 2004 - 2020 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_vector_slice_h
#define dealii_vector_slice_h

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

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

DEAL_II_NAMESPACE_OPEN

template <typename VectorType>
class DEAL_II_DEPRECATED VectorSlice
  : public ArrayView<
      typename std::conditional<std::is_const<VectorType>::value,
                                const typename VectorType::value_type,
                                typename VectorType::value_type>::type>
{
public:
  VectorSlice(VectorType &v);
  VectorSlice(VectorType &v, unsigned int start, unsigned int length);

protected:
  using ArrayViewType =
    ArrayView<typename std::conditional<std::is_const<VectorType>::value,
                                        const typename VectorType::value_type,
                                        typename VectorType::value_type>::type>;
};


template <typename VectorType>
inline const VectorSlice<const VectorType>
make_slice(VectorType &v)
{
  const VectorSlice<const VectorType> r(v);
  return r;
}



template <typename VectorType>
inline const VectorSlice<const VectorType>
make_slice(VectorType &v, const unsigned int start, const unsigned int length)
{
  const VectorSlice<const VectorType> r(v, start, length);
  return r;
}



//---------------------------------------------------------------------------

template <typename VectorType>
inline VectorSlice<VectorType>::VectorSlice(VectorType &v)
  : ArrayViewType(make_array_view(std::begin(v), std::end(v)))
{}



template <typename VectorType>
inline VectorSlice<VectorType>::VectorSlice(VectorType & v,
                                            unsigned int start,
                                            unsigned int length)
  : ArrayViewType(
      make_array_view(std::begin(v) + start, std::begin(v) + start + length))
{
  AssertIndexRange(length, v.size() - start + 1);
}

DEAL_II_NAMESPACE_CLOSE

#endif