mean.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_ACCU_STAT_MEAN_HH
# define MLN_ACCU_STAT_MEAN_HH


# include <mln/accu/internal/base.hh>
# include <mln/accu/math/count.hh>
# include <mln/accu/math/sum.hh>


namespace mln
{

  namespace accu
  {

    namespace stat
    {

      // Forward declaration.
      template <typename T, typename S, typename M>
      struct mean;

    } // end of namespace mln::accu::stat


    // Meta.

    namespace meta
    {

      namespace stat
      {

        struct mean : public Meta_Accumulator< mean >
        {
          template < typename T,
                     typename S = mln_sum(T),
                     typename M = S >
          struct with
          {
            typedef accu::stat::mean<T,S,M> ret;
          };
        };

      } // end of namespace mln::accu::meta::stat

    } // end of namespace mln::accu::meta

  } // end of namespace mln::accu


  // Traits.

  namespace trait
  {

    template <typename T, typename S, typename M>
    struct accumulator_< accu::stat::mean<T, S, M> >
    {
      typedef accumulator::has_untake::no     has_untake;
      typedef accumulator::has_set_value::no  has_set_value;
      typedef accumulator::has_stop::no       has_stop;
      typedef accumulator::when_pix::use_v      when_pix;
    };

  } // end of namespace mln::trait


  namespace accu
  {

    namespace stat
    {


      template <typename T,
                typename S = mln_sum(T),
                typename M = S>
      struct mean : public mln::accu::internal::base< M , mean<T,S,M> >
      {
        typedef T argument;
        typedef M result;

        mean();

        void init();
        void take(const argument& t);
        void take(const mean<T,S,M>& other);

        M to_result() const;
        operator M () const;

        bool is_valid() const;

      protected:

        accu::math::count<T> count_;
        accu::math::sum<T,S>   sum_;
      };



      template <typename I, typename S, typename M>
      struct mean< util::pix<I>, S,M >;


# ifndef MLN_INCLUDE_ONLY

      template <typename T, typename S, typename M>
      inline
      mean<T,S,M>::mean()
      {
        init();
      }

      template <typename T, typename S, typename M>
      inline
      void
      mean<T,S,M>::init()
      {
        count_.init();
        sum_.init();
      }

      template <typename T, typename S, typename M>
      inline
      void mean<T,S,M>::take(const argument& t)
      {
        count_.take(t);
        sum_.take(t);
      }

      template <typename T, typename S, typename M>
      inline
      void
      mean<T,S,M>::take(const mean<T,S,M>& other)
      {
        count_.take(other.count_);
        sum_.take(other.sum_);
      }

      template <typename T, typename S, typename M>
      inline
      M
      mean<T,S,M>::to_result() const
      {
        unsigned n = count_.to_result();
        if (n == 0u)
          return M(); // Safety.
        return static_cast<M>(sum_.to_result() / n);
      }

      template <typename T, typename S, typename M>
      inline
      mean<T,S,M>::operator M() const
      {
        return to_result();
      }

      template <typename T, typename S, typename M>
      inline
      bool
      mean<T,S,M>::is_valid() const
      {
        return count_.to_result() != 0;
      }

# endif // ! MLN_INCLUDE_ONLY

    } // end of namespace mln::accu::stat

  } // end of namespace mln::accu

} // end of namespace mln

#endif // ! MLN_ACCU_STAT_MEAN_HH