value_like.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
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#ifndef MLN_VALUE_INTERNAL_VALUE_LIKE_HH
# define MLN_VALUE_INTERNAL_VALUE_LIKE_HH


# include <mln/core/concept/value.hh>
# include <mln/core/internal/force_exact.hh>


namespace mln
{

  namespace value
  {

    namespace internal
    {

      template < typename V, // Equivalent.
                 typename C, // Encoding.
                 typename N, // Interoperation.
                 typename E >
      struct value_like_ // FIXME :Remove -> : public Value<E>
      {
        typedef V equiv;

        typedef C enc;

        typedef N interop;

        V to_equiv() const;

        const C& to_enc() const;

        N to_interop() const;


        // Handle to encoding value.
        C& handle_() { return v_; }

      protected:
        enc v_; 
      };


      template <typename V, typename C, typename N, typename E>
      bool operator==(const value_like_<V,C,N,E>& lhs, const value_like_<V,C,N,E>& rhs);


      template <typename V, typename C, typename N, typename E>
      bool operator<(const value_like_<V,C,N,E>& lhs, const value_like_<V,C,N,E>& rhs);


# ifndef MLN_INCLUDE_ONLY

      template <typename V, typename C, typename N, typename E>
      inline
      V
      value_like_<V,C,N,E>::to_equiv() const
      {
        return v_;
      }

      template <typename V, typename C, typename N, typename E>
      inline
      const C&
      value_like_<V,C,N,E>::to_enc() const
      {
        return v_;
      }

      template <typename V, typename C, typename N, typename E>
      inline
      N
      value_like_<V,C,N,E>::to_interop() const
      {
        return static_cast<N>(mln::internal::force_exact<E>(*this));
      }

      template <typename V, typename C, typename N, typename E>
      inline
      bool operator==(const value_like_<V,C,N,E>& lhs,
                      const value_like_<V,C,N,E>& rhs)
      {
        return lhs.to_enc() == rhs.to_enc();
      }

      template <typename V, typename C, typename N, typename E>
      inline
      bool operator<(const value_like_<V,C,N,E>& lhs,
                     const value_like_<V,C,N,E>& rhs)
      {
        return lhs.to_interop() < rhs.to_interop(); // FIXME HERE: Why interop?
      }

# endif // ! MLN_INCLUDE_ONLY

    } // end of namespace mln::value::internal

  } // end of namespace mln::value

} // end of namespace mln


#endif // ! MLN_VALUE_INTERNAL_VALUE_LIKE_HH