ItemConnectivityContainerView.h

// -*- tab-width: 2; indent-tabs-mode: nil; coding: utf-8-with-signature -*-
//-----------------------------------------------------------------------------
// Copyright 2000-2026 CEA (www.cea.fr) IFPEN (www.ifpenergiesnouvelles.com)
// See the top-level COPYRIGHT file for details.
// SPDX-License-Identifier: Apache-2.0
//-----------------------------------------------------------------------------
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/* ItemConnectivityContainerView.h                             (C) 2000-2026 */
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/* Views of containers holding connectivity.                                 */
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#ifndef ARCANE_CORE_ITEMCONNECTIVITYCONTAINERVIEW_H
#define ARCANE_CORE_ITEMCONNECTIVITYCONTAINERVIEW_H
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#include "arccore/base/Span.h"
 
#include "arcane/core/ItemTypes.h"
#include "arcane/core/ItemLocalId.h"
 
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namespace Arcane::mesh
{
class IncrementalItemConnectivityBase;
}
 
namespace Arcane
{
class ItemInternalConnectivityList;
 
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/*!
 * \internal
 * \brief Views of containers holding connectivity.
 * This class allows the containers used to be opaque outside of Arcane
 * to facilitate their eventual change.
 */
class ARCANE_CORE_EXPORT ItemConnectivityContainerView
{
  // List of classes that have the right to create or directly retrieve
  // instances of this class
  friend ItemInternalConnectivityList;
  friend IndexedItemConnectivityViewBase;
  friend IndexedItemConnectivityViewBase2;
  friend mesh::IncrementalItemConnectivityBase;
  template <typename ItemType1, typename ItemType2>
  friend class IndexedItemConnectivityGenericViewT;
 
 private:
 
  ItemConnectivityContainerView() = default;
  ItemConnectivityContainerView(SmallSpan<Int32> _list,
                                SmallSpan<const Int32> _indexes,
                                SmallSpan<const Int32> _nb_connected_item)
  : m_list_data(_list.data())
  , m_indexes(_indexes.data())
  , m_nb_connected_items(_nb_connected_item.data())
  , m_list_data_size(_list.size())
  , m_nb_item(_nb_connected_item.size())
  {
#ifdef ARCANE_CHECK
    _checkSize(_indexes.size(), _nb_connected_item.size());
#endif
  }
 
 public:
 
  /*!
   * \brief Checks that the two instances \a this and \a rhs have the same values.
   *
   * Throws a FatalErrorException if not.
   */
  void checkSame(ItemConnectivityContainerView rhs) const;
 
 private:
 
  //! List of entities connected to the entity with localId() \a lid
  template <typename ItemType> constexpr ARCCORE_HOST_DEVICE
  ItemLocalIdListViewT<ItemType>
  itemsIds(ItemLocalId lid) const
  {
    ARCANE_CHECK_AT(lid.localId(), m_nb_item);
    Int32 x = m_indexes[lid];
    ARCANE_CHECK_AT(x, m_list_data_size);
    auto* p = &m_list_data[x];
    // TODO: LOCAL_ID_OFFSET
    return { p, m_nb_connected_items[lid], 0 };
  }
 
  //! \a index-th entity connected to the entity with localId() \a lid
  template <typename ItemLocalIdType> constexpr ARCCORE_HOST_DEVICE
  ItemLocalIdType
  itemId(ItemLocalId lid, Int32 index) const
  {
    ARCANE_CHECK_AT(lid.localId(), m_nb_item);
    Int32 x = m_indexes[lid] + index;
    ARCANE_CHECK_AT(x, m_list_data_size);
    return ItemLocalIdType(m_list_data[x]);
  }
 
  //! Array of indices in the connectivity table
  constexpr ARCCORE_HOST_DEVICE SmallSpan<const Int32>
  indexes() const { return { m_indexes, m_nb_item }; }
 
  //! Array of the number of entities connected to another entity.
  constexpr ARCCORE_HOST_DEVICE SmallSpan<const Int32>
  nbConnectedItems() const { return { m_nb_connected_items, m_nb_item }; }
 
  //! Number of entities
  constexpr ARCCORE_HOST_DEVICE Int32 nbItem() const { return m_nb_item; }
 
 private:
 
  Int32* m_list_data = nullptr;
  const Int32* m_indexes = nullptr;
  const Int32* m_nb_connected_items = nullptr;
  Int32 m_list_data_size = 0;
  Int32 m_nb_item = 0;
 
 private:
 
  void _checkSize(Int32 indexes_size, Int32 nb_connected_item_size);
 
 private:
 
  friend class MutableIndexedParticleCellConnectivityView;
  // Only to position the cell a particle belongs to
  ARCCORE_HOST_DEVICE void _setParticleCellId(ItemLocalId particle_lid, CellLocalId cell_lid) const
  {
    ARCANE_CHECK_AT(particle_lid.localId(), m_nb_item);
    m_list_data[m_indexes[particle_lid]] = cell_lid;
  }
};
 
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} // End namespace Arcane
 
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#endif