short_range_verlet.cpp

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/*
 * Copyright (C) 2025-2026 The ESPResSo project
 *
 * This file is part of ESPResSo.
 *
 * ESPResSo is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * ESPResSo is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
// Sole instantiation site of the update_cabana_state AoSoA-commit /
// Verlet-list-build template for VerletCriterion<>. forces.cpp, energy.cpp and
// pressure.cpp used to each instantiate this giant (identical each time); they
// now call the non-template wrapper below so the build-lambda instantiations
// exist ONLY here.
 
#include "short_range_verlet.hpp"
 
#include <config/config.hpp>
 
#include "cell_system/CellStructure.hpp"
#include "electrostatics/coulomb.hpp"
#include "integrators/Propagation.hpp"
#include "magnetostatics/dipoles.hpp"
#include "nonbonded_interactions/VerletCriterion.hpp"
#include "system/System.hpp"
 
#include "short_range_cabana.hpp"
 
void update_verlet_state(System::System const &system,
                         double const collision_cut) {
  auto &cell_structure = *system.cell_structure;
  auto const skin = cell_structure.get_verlet_skin();
  auto const coulomb_cut = system.coulomb.cutoff();
  auto const dipolar_cut = system.dipoles.cutoff();
  auto const pair_cutoff = system.get_interaction_range();
  auto const integ_switch = system.propagation->integ_switch;
  // When no electrostatics/dipolar/collision cutoff is active, build the
  // criterion variant that compiles those dead per-candidate branches out of
  // the build loop; otherwise the full one. pair_cutoff is the interaction
  // range, which is also the criterion's maximum cutoff. Both
  // update_cabana_state instantiations live in this single TU. The criterion
  // is handed over as a factory so its O(n_types^2) cutoff table is only
  // built when the Verlet list is actually rebuilt.
  bool const short_range_only = coulomb_cut == inactive_cutoff and
                                dipolar_cut == inactive_cutoff and
                                collision_cut == inactive_cutoff;
  if (short_range_only) {
    auto const make_criterion = [&] {
      return VerletCriterion<GetNonbondedCutoff, true>{
          system, skin, pair_cutoff, coulomb_cut, dipolar_cut, collision_cut};
    };
    update_cabana_state(cell_structure, make_criterion, pair_cutoff,
                        integ_switch);
  } else {
    auto const make_criterion = [&] {
      return VerletCriterion<GetNonbondedCutoff, false>{
          system, skin, pair_cutoff, coulomb_cut, dipolar_cut, collision_cut};
    };
    update_cabana_state(cell_structure, make_criterion, pair_cutoff,
                        integ_switch);
  }
}