count.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_MATH_COUNT_HH
# define MLN_ACCU_MATH_COUNT_HH


# include <mln/accu/internal/base.hh>
# include <mln/core/concept/meta_accumulator.hh>


namespace mln
{

  // Forward declaration.
  namespace accu {
    namespace math {
      template <typename T> struct count;
    }
  }


  // Traits.

  namespace trait
  {

    template <typename T>
    struct accumulator_< accu::math::count<T> >
    {
      typedef accumulator::has_untake::yes    has_untake;
      typedef accumulator::has_set_value::yes has_set_value;
      typedef accumulator::has_stop::no       has_stop;
      typedef accumulator::when_pix::use_none when_pix;
    };

  } // end of namespace mln::trait


  namespace accu
  {

    namespace meta
    {

      namespace math
      {

        struct count : public Meta_Accumulator< count >
        {
          template <typename T>
          struct with
          {
            typedef accu::math::count<T> ret;
          };
        };

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

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


    namespace math
    {

      //
      template <typename T>
      struct count : public mln::accu::internal::base< unsigned , count<T> >
      {
        typedef T argument;

        count();

        void init();
        void take(const argument&);
        void take(const count<T>& other);

        void untake(const argument&);
        void untake(const count<T>& other);

        void set_value(unsigned c);

        unsigned to_result() const;

        bool is_valid() const;

      protected:
        unsigned count_;
      };



# ifndef MLN_INCLUDE_ONLY

      template <typename T>
      inline
      count<T>::count()
      {
        init();
      }

      template <typename T>
      inline
      void
      count<T>::init()
      {
        count_ = 0;
      }

      template <typename T>
      inline
      void
      count<T>::take(const argument&)
      {
        ++count_;
      }

      template <typename T>
      inline
      void
      count<T>::untake(const argument&)
      {
        mln_precondition(count_ > 0);
        --count_;
      }

      template <typename T>
      inline
      void
      count<T>::take(const count<T>& other)
      {
        count_ += other.count_;
      }

      template <typename T>
      inline
      void
      count<T>::untake(const count<T>& other)
      {
        mln_precondition(other.count_ <= count_);
        count_ -= other.count_;
      }

      template <typename T>
      inline
      unsigned
      count<T>::to_result() const
      {
        return count_;
      }

      template <typename T>
      inline
      void
      count<T>::set_value(unsigned c)
      {
        count_ = c;
      }

      template <typename T>
      inline
      bool
      count<T>::is_valid() const
      {
        return true;
      }

# endif // ! MLN_INCLUDE_ONLY

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

  } // end of namespace mln::accu

} // end of namespace mln


#endif // ! MLN_ACCU_MATH_COUNT_HH