Grid3d.hpp

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 *
 * SUPPORT OPEN SCIENCE!  If you use OpenMD or its source code in your
 * research, please cite the following paper when you publish your work:
 *
 * [1] Drisko et al., J. Open Source Softw. 9, 7004 (2024).
 *
 * Good starting points for code and simulation methodology are:
 *
 * [2] Meineke, et al., J. Comp. Chem. 26, 252-271 (2005).
 * [3] Fennell & Gezelter, J. Chem. Phys. 124, 234104 (2006).
 * [4] Sun, Lin & Gezelter, J. Chem. Phys. 128, 234107 (2008).
 * [5] Vardeman, Stocker & Gezelter, J. Chem. Theory Comput. 7, 834 (2011).
 * [6] Kuang & Gezelter, Mol. Phys., 110, 691-701 (2012).
 * [7] Lamichhane, Gezelter & Newman, J. Chem. Phys. 141, 134109 (2014).
 * [8] Bhattarai, Newman & Gezelter, Phys. Rev. B 99, 094106 (2019).
 * [9] Drisko & Gezelter, J. Chem. Theory Comput. 20, 4986-4997 (2024).
 */
 
#ifndef UTILS_GRID3D_HPP
#define UTILS_GRID3D_HPP
 
#include <cassert>
#include <vector>
 
namespace OpenMD {
 
  /**
   * @class Grid3d
   * A generic 3d grid class
   */
  template<class Elem>
  class Grid3D {
  public:
    Grid3D(unsigned int dim1, unsigned int dim2, unsigned int dim3) :
        dim1_(dim1), dim2_(dim2), dim3_(dim3) {
      data_.resize(dim1_ * dim2_ * dim3_);
    }
 
    Elem& operator()(unsigned int i, unsigned int j, unsigned int k) {
      int index = isValidGrid(i, j, k);
      assert(index != -1);
      return data_[index];
    }
 
    const Elem& operator()(unsigned int i, unsigned int j,
                           unsigned int k) const {
      int index = isValidGrid(i, j, k);
      assert(index != -1);
      return data_[index];
    }
 
    std::vector<Elem> getAllNeighbors(unsigned int i, unsigned int j,
                                      unsigned int k) {
      std::vector<Elem> result;
      int index;
      index = isValidGrid(i - 1, j, k);
      if (index != -1) result.push_back(data_[index]);
 
      index = isValidGrid(i + 1, j, k);
      if (index != -1) result.push_back(data_[index]);
 
      index = isValidGrid(i, j - 1, k);
      if (index != -1) result.push_back(data_[index]);
 
      index = isValidGrid(i, j + 1, k);
      if (index != -1) result.push_back(data_[index]);
 
      index = isValidGrid(i, j, k - 1);
      if (index != -1) result.push_back(data_[index]);
 
      index = isValidGrid(i, j, k + 1);
      if (index != -1) result.push_back(data_[index]);
 
      return result;
    }
 
  private:
    int isValidGrid(unsigned int i, unsigned int j, unsigned int k) const {
      unsigned int index = i * dim2_ * dim3_ + j * dim3_ + k;
      return index < data_.size() ? int(index) : -1;
    };
 
    unsigned int dim1_;
    unsigned int dim2_;
    unsigned int dim3_;
    std::vector<Elem> data_;
  };
}  // namespace OpenMD
 
#endif