localviewpair.hh

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// SPDX-FileCopyrightText: Copyright © DUNE Project contributors, see file AUTHORS.md
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception OR LGPL-3.0-or-later
 
#ifndef DUNE_ASSEMBLER_LOCALVIEWPAIR_HH
#define DUNE_ASSEMBLER_LOCALVIEWPAIR_HH
 
#include <type_traits>
 
#include <dune/assembler/concepts.hh>
#include <dune/common/std/extents.hh>
 
namespace Dune::Assembler {
 
template <Concepts::LocalView RowLocalView, Concepts::LocalView ColLocalView>
class LocalViewPair
{
  using RowBasis = typename RowLocalView::GlobalBasis;
  using ColBasis = typename ColLocalView::GlobalBasis;
 
  using size_type = std::common_type_t<typename RowLocalView::size_type, typename ColLocalView::size_type>;
 
  // create a reference to the first local view of the bases and the local views
  // are identical, otherwise return a reference to the second local view.
  template <class LV1, class LV2>
  static auto& refColLocalView (LV1& first, LV2& second, bool same) noexcept
  {
    if constexpr (std::is_same_v<LV1,LV2>)
      return same ? first : second;
    else
      return second;
  }
 
public:
  LocalViewPair (RowBasis const& rowBasis, ColBasis const& colBasis)
    : rowLocalView_(rowBasis.localView())
    , colLocalViewStorage_(colBasis.localView())
    , colLocalView_(refColLocalView(rowLocalView_, colLocalViewStorage_,
                                    (void*)(&rowBasis) == (void*)(&colBasis)))
  {}
 
  LocalViewPair (const LocalViewPair& other)
    : rowLocalView_(other.rowLocalView_)
    , colLocalViewStorage_(other.colLocalViewStorage_)
    , colLocalView_(refColLocalView(rowLocalView_, colLocalViewStorage_, other.same()))
  {}
 
  LocalViewPair (LocalViewPair&& other)
    : rowLocalView_(std::move(other.rowLocalView_))
    , colLocalViewStorage_(std::move(other.colLocalViewStorage_))
    , colLocalView_(refColLocalView(rowLocalView_, colLocalViewStorage_, other.same()))
  {}
 
  template <class Element>
  void bind (const Element& element)
  {
    rowLocalView_.bind(element);
    if (not same())
      colLocalView_.bind(element);
  }
 
  void unbind ()
  {
    rowLocalView_.unbind();
    if (not same())
      colLocalView_.unbind();
  }
 
  template <std::size_t I>
  friend auto const& get (const LocalViewPair& pair) noexcept
  {
    if constexpr (I == 0)
      return pair.rowLocalView_;
    else
      return pair.colLocalView_;
  }
 
  [[nodiscard]] bool same () const
  {
    return ((void*)(&rowLocalView_) == (void*)(&colLocalView_));
  }
 
protected:
  RowLocalView rowLocalView_;
  ColLocalView colLocalViewStorage_;
  ColLocalView& colLocalView_;
};
 
template <Concepts::GlobalBasis RowBasis, Concepts::GlobalBasis ColBasis>
LocalViewPair(const RowBasis&, const ColBasis&)
-> LocalViewPair<typename RowBasis::LocalView, typename ColBasis::LocalView>;
 
} // end namespace Dune::Assembler
 
#endif // DUNE_ASSEMBLER_LOCALVIEWPAIR_HH