Scaled.hpp

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/*
 * Copyright (C) 2010-2026 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/>.
 */
 
#pragma once
 
#include <unordered_map>
 
namespace FieldCoupling {
namespace Coupling {
class Scaled {
  std::unordered_map<int, double> m_scales;
  double m_default;
 
public:
  static constexpr bool is_linear = true;
 
  template <typename ScalesRef>
  Scaled(ScalesRef &&scales, double default_val)
      : m_scales(std::forward<ScalesRef>(scales)), m_default(default_val) {}
 
  double &default_scale() { return m_default; }
  double const &default_scale() const { return m_default; }
  auto &particle_scales() { return m_scales; }
  auto const &particle_scales() const { return m_scales; }
 
private:
  template <typename Particle> double scale(Particle const &p) const {
    auto const it = m_scales.find(p.id());
    if (it != m_scales.end()) {
      return it->second;
    }
    return m_default;
  }
 
public:
  template <typename T, typename Particle>
  T operator()(Particle const &p, T const &x) const {
    return scale(p) * x;
  }
};
} // namespace Coupling
} // namespace FieldCoupling