comb.hxx

Go to the documentation of this file.

/*===========================================================================================================
 *
 * HUC - Hurna Core
 *
 * Copyright (c) Michael Jeulin-Lagarrigue
 *
 *  Licensed under the MIT License, you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         https://github.com/Hurna/Hurna-Core/blob/master/LICENSE
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is
 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and limitations under the License.
 *
 * The above copyright notice and this permission notice shall be included in all copies or
 * substantial portions of the Software.
 *
 *=========================================================================================================*/
#ifndef MODULE_SORT_COMB_HXX
#define MODULE_SORT_COMB_HXX

// STD includes
#include <iterator>

namespace huc
{
  namespace sort
  {
    template <typename IT, typename Compare = std::less<typename std::iterator_traits<IT>::value_type>>
    void Comb(const IT& begin, const IT& end)
    {
      const auto distance = static_cast<const int>(std::distance(begin, end));
      if (distance < 2)
        return;

      auto gap = distance;
      double shrink = 1.3;
      bool hasSwapped = true;
      while (hasSwapped)
      {
        hasSwapped = false;

        gap /= shrink;
        if (gap > 1)
          hasSwapped = true;
        else
          gap = 1;

        for (auto it = begin; it + gap < end; ++it)
          if (Compare()(*(it + gap), *it))
          {
            std::swap(*it, *(it + gap));
            hasSwapped = true;
          }
      }
    }
  }
}

#endif // MODULE_SORT_COMB_HXX