sparsitybuild.h

// Copyright (C) 2007-2026 Garth N. Wells
//
// This file is part of DOLFINx (https://www.fenicsproject.org)
//
// SPDX-License-Identifier:    LGPL-3.0-or-later
 
#pragma once
 
#include "DofMap.h"
#include <array>
#include <cstdint>
#include <dolfinx/la/SparsityPattern.h>
#include <functional>
#include <ranges>
#include <span>
 
namespace dolfinx::fem
{
class DofMap;

namespace sparsitybuild
{
template <std::ranges::input_range R0, std::ranges::input_range R1>
void cells(la::SparsityPattern& pattern, const std::pair<R0, R1>& cells,
           std::array<std::reference_wrapper<const DofMap>, 2> dofmaps)
{
  assert(cells.first.size() == cells.second.size());
  const DofMap& map0 = dofmaps[0].get();
  const DofMap& map1 = dofmaps[1].get();
 
  // Reserve entries for all cell-wise outer products.
  if constexpr (std::ranges::sized_range<R0> and std::ranges::sized_range<R1>)
  {
    if (std::size_t num_cells = std::ranges::size(cells.first); num_cells > 0)
    {
      std::size_t n0 = map0.cell_dofs(*cells.first.begin()).size();
      std::size_t n1 = map1.cell_dofs(*cells.second.begin()).size();
      pattern.reserve_blocks(num_cells, num_cells * n0, num_cells * n1);
    }
  }
 
  for (auto cell0 = cells.first.begin(), cell1 = cells.second.begin();
       cell0 != cells.first.end() and cell1 != cells.second.end();
       ++cell0, ++cell1)
  {
    pattern.insert(map0.cell_dofs(*cell0), map1.cell_dofs(*cell1));
  }
}

void interior_facets(
    la::SparsityPattern& pattern,
    std::array<std::span<const std::int32_t>, 2> cells,
    std::array<std::reference_wrapper<const DofMap>, 2> dofmaps);
 
} // namespace sparsitybuild
} // namespace dolfinx::fem