permute_axes.h

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/* Copyright (c) 2008-2022 the MRtrix3 contributors.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Covered Software is provided under this License on an "as is"
 * basis, without warranty of any kind, either expressed, implied, or
 * statutory, including, without limitation, warranties that the
 * Covered Software is free of defects, merchantable, fit for a
 * particular purpose or non-infringing.
 * See the Mozilla Public License v. 2.0 for more details.
 *
 * For more details, see http://www.mrtrix.org/.
 */
 
#ifndef __adapter_permute_axes_h__
#define __adapter_permute_axes_h__
 
#include "adapter/base.h"
 
namespace MR
{
  namespace Adapter
  {
 
    template <class ImageType>
      class PermuteAxes :
        public Base<PermuteAxes<ImageType>,ImageType>
    { MEMALIGN (PermuteAxes<ImageType>)
        public:
 
        using base_type = Base<PermuteAxes<ImageType>, ImageType>;
        using value_type = typename ImageType::value_type;
 
        using base_type::size;
        using base_type::parent;
 
        PermuteAxes (const ImageType& original, const vector<int>& axes) :
          base_type (original),
            axes_ (axes) {
              for (int i = 0; i < static_cast<int> (parent().ndim()); ++i) {
                for (size_t a = 0; a < axes_.size(); ++a) {
                  if (axes_[a] >= int (parent().ndim()))
                    throw Exception ("axis " + str(axes_[a]) + " exceeds image dimensionality");
                  if (axes_[a] == i)
                    goto next_axis;
                }
                if (parent().size (i) != 1)
                  throw Exception ("omitted axis \"" + str (i) + "\" has dimension greater than 1");
next_axis:
                continue;
              }
 
              int non_existent_index = -1;
              for (auto& a : axes_) {
                if (a < 0) {
                  a = non_existent_index--;
                  non_existent_axes.push_back (0);
                }
              }
            }
 
          size_t ndim () const {
            return axes_.size();
          }
          ssize_t size (size_t axis) const {
            return axes_[axis] < 0 ? 1 : parent().size (axes_[axis]);
          }
          default_type spacing (size_t axis) const {
            return axes_[axis] < 0 ? std::numeric_limits<default_type>::quiet_NaN() : parent().spacing (axes_[axis]);
          }
          ssize_t stride (size_t axis) const {
            return axes_[axis] < 0 ? 0 : parent().stride (axes_[axis]);
          }
 
          void reset () { parent().reset(); }
 
          ssize_t get_index (size_t axis) const { const auto a = axes_[axis]; return a < 0 ? non_existent_axes[-1-a] : parent().index (a); }
          void move_index (size_t axis, ssize_t increment) {
            const auto a = axes_[axis];
            if (a < 0) non_existent_axes[-1-a] += increment;
            else parent().index (a) += increment;
          }
 
        private:
          vector<int> axes_;
          vector<size_t> non_existent_axes;
 
      };
 
  }
}
 
#endif