fetch_particles.hpp

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/*
 * Copyright (C) 2010-2022 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/>.
 */
 
#ifndef FETCH_PARTICLES_HPP
#define FETCH_PARTICLES_HPP
 
#include "PidObservable.hpp"
#include "cell_system/CellStructure.hpp"
#include "system/System.hpp"
 
#include <algorithm>
#include <iterator>
#include <set>
#include <vector>
 
/** Fetch a group of particles.
 *
 *  @param ids particle identifiers
 *  @return array of particle copies, with positions in the current box.
 */
inline auto fetch_particles(std::vector<int> const &ids) {
  auto const &system = System::get_system();
  auto const ids_set = std::set<int>{ids.begin(), ids.end()};
  auto const local_particles = system.cell_structure->local_particles();
  Observables::ParticleReferenceRange local_particle_refs;
  std::copy_if(local_particles.begin(), local_particles.end(),
               std::back_inserter(local_particle_refs),
               [&ids_set](Particle &p) { return ids_set.count(p.id()) != 0; });
  return local_particle_refs;
}
#endif