sort_psites.hh

// Copyright (C) 2007, 2008, 2009 EPITA Research and Development Laboratory (LRDE)
//
// This file is part of Olena.
//
// Olena 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, version 2 of the License.
//
// Olena 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 Olena.  If not, see <http://www.gnu.org/licenses/>.
//
// As a special exception, you may use this file as part of a free
// software project without restriction.  Specifically, if other files
// instantiate templates or use macros or inline functions from this
// file, or you compile this file and link it with other files to produce
// an executable, this file does not by itself cause the resulting
// executable to be covered by the GNU General Public License.  This
// exception does not however invalidate any other reasons why the
// executable file might be covered by the GNU General Public License.

#ifndef MLN_DATA_SORT_PSITES_HH
# define MLN_DATA_SORT_PSITES_HH


# include <algorithm>

# include <mln/core/concept/image.hh>
# include <mln/convert/to_p_array.hh>
# include <mln/histo/compute.hh>
# include <mln/util/ord.hh>
# include <mln/geom/nsites.hh>


namespace mln
{

  namespace data
  {

    template <typename I>
    p_array<mln_psite(I)> sort_psites_increasing(const Image<I>& input);

    template <typename I>
    p_array<mln_psite(I)> sort_psites_decreasing(const Image<I>& input);


# ifndef MLN_INCLUDE_ONLY

    namespace impl
    {

      // utility

      template <typename I>
      struct value_psite_less_
      {
        const I& ima_;

        inline
        value_psite_less_(const I& ima)
          : ima_(ima)
        {
        }

        inline
        bool operator()(const mln_psite(I)& lhs,
                        const mln_psite(I)& rhs) const
        {
          return util::ord_strict(ima_(lhs), ima_(rhs))
            || (ima_(lhs) == ima_(rhs)
                &&
                util::ord_strict(lhs, rhs));
        }
      };

      template <typename I>
      struct value_psite_greater_
      {
        const I& ima_;

        inline
        value_psite_greater_(const I& ima)
          : ima_(ima)
        {
        }

        inline
        bool operator()(const mln_psite(I)& lhs,
                        const mln_psite(I)& rhs) const
        {
          return util::ord_strict(ima_(rhs), ima_(lhs))
            || (ima_(lhs) == ima_(rhs)
                &&
                util::ord_strict(rhs, lhs));
        }
      };


      // increasing

      template <typename I>
      inline
      p_array<mln_psite(I)>
      sort_psites_increasing_(trait::image::quant::any, // general case
                              const I& input)
      {
        p_array<mln_psite(I)> v = mln::convert::to_p_array(input.domain());
        std::sort(v.hook_std_vector_().begin(), v.hook_std_vector_().end(),
                  value_psite_less_<I>(input));
        return v;
      }

      template <typename I>
      inline
      p_array<mln_psite(I)>
      sort_psites_increasing_(trait::image::quant::low, // low quantization
                              const I& input)
      {
        typedef mln_vset(I) S;
        const S& vset = input.values_eligible();
        const unsigned n = vset.nvalues();

        // h
        histo::array<mln_value(I)> h = histo::compute(input);

        // preparing output data
        std::vector<unsigned> loc(vset.nvalues());
        loc[0] = 0;
        for (unsigned i = 1; i != n; ++i)
          loc[i] = loc[i-1] + h[i-1];

        // computing output data
        std::vector<mln_psite(I)> vec(geom::nsites(input));
        mln_fwd_piter(I) p(input.domain());
        for_all(p)
          vec[loc[vset.index_of(input(p))]++] = p;

        p_array<mln_psite(I)> v(vec);
        return v;
      }


      // decreasing

      template <typename I>
      inline
      p_array<mln_psite(I)>
      sort_psites_decreasing_(trait::image::quant::any, // general case
                              const I& input)
      {
        p_array<mln_psite(I)> v = mln::convert::to_p_array(input.domain());
        std::sort(v.hook_std_vector_().begin(), v.hook_std_vector_().end(),
                  value_psite_greater_<I>(input));
        return v;
      }

      template <typename I>
      inline
      p_array<mln_psite(I)>
      sort_psites_decreasing_(trait::image::quant::low, // low quantization
                              const I& input)
      {
        typedef mln_vset(I) S;
        const S& vset = input.values_eligible();
        const unsigned n = vset.nvalues();

        // h
        histo::array<mln_value(I)> h = histo::compute(input);

        // preparing output data
        std::vector<unsigned> loc(vset.nvalues());
        loc[n-1] = 0;
        for (int i = n - 2; i >= 0; --i)
          loc[i] = loc[i+1] + h[i+1];

        // computing output data
        std::vector<mln_psite(I)> vec(geom::nsites(input));
        mln_fwd_piter(I) p(input.domain());
        for_all(p)
          vec[loc[vset.index_of(input(p))]++] = p;

        p_array<mln_psite(I)> v(vec);
        return v;
      }


    } // end of namespace mln::data::impl


    // Facades.

    template <typename I>
    inline
    p_array<mln_psite(I)>
    sort_psites_increasing(const Image<I>& input)
    {
      mln_precondition(exact(input).is_valid());
      return impl::sort_psites_increasing_(mln_trait_image_quant(I)(),
                                           exact(input));
    }

    template <typename I>
    inline
    p_array<mln_psite(I)>
    sort_psites_decreasing(const Image<I>& input)
    {
      mln_precondition(exact(input).is_valid());
      return impl::sort_psites_decreasing_(mln_trait_image_quant(I)(),
                                           exact(input));
    }

# endif // ! MLN_INCLUDE_ONLY

  } // end of namespace mln::data

} // end of namespace mln


#endif // ! MLN_DATA_SORT_PSITES_HH