grid.h

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/*
 *
 *    Copyright (c) 2014-2019
 *      SMASH Team
 *
 *    GNU General Public License (GPLv3 or later)
 *
 */

#ifndef SRC_INCLUDE_GRID_H_
#define SRC_INCLUDE_GRID_H_

#include <array>
#include <cmath>
#include <functional>
#include <utility>
#include <vector>

#include "forwarddeclarations.h"
#include "particles.h"

namespace smash {

enum class GridOptions : char {
  Normal = 0,
  PeriodicBoundaries = 1
};

enum class CellSizeStrategy : char {
  Optimal,

  Largest
};

class GridBase {
 public:
  typedef int SizeType;

 protected:
  static std::pair<std::array<double, 3>, std::array<double, 3>>
  find_min_and_length(const Particles &particles);
};

template <GridOptions Options = GridOptions::Normal>
class Grid : public GridBase {
 public:
  Grid(const Particles &particles, double min_cell_length,
       double timestep_duration,
       CellSizeStrategy strategy = CellSizeStrategy::Optimal)
      : Grid{find_min_and_length(particles), std::move(particles),
             min_cell_length, timestep_duration, strategy} {}

  Grid(const std::pair<std::array<double, 3>, std::array<double, 3>>
           &min_and_length,
       const Particles &particles, double min_cell_length,
       double timestep_duration,
       CellSizeStrategy strategy = CellSizeStrategy::Optimal);

  void iterate_cells(
      const std::function<void(const ParticleList &)> &search_cell_callback,
      const std::function<void(const ParticleList &, const ParticleList &)>
          &neighbor_cell_callback) const;

 private:
  SizeType make_index(SizeType x, SizeType y, SizeType z) const;

  SizeType make_index(std::array<SizeType, 3> idx) const {
    return make_index(idx[0], idx[1], idx[2]);
  }

  const std::array<double, 3> length_;

  std::array<int, 3> number_of_cells_;

  std::vector<ParticleList> cells_;
};

}  // namespace smash

#endif  // SRC_INCLUDE_GRID_H_