nil.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_NIL_HH
# define MLN_ACCU_NIL_HH


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


namespace mln
{

  namespace accu
  {

    template <typename T>
    struct nil : public mln::accu::internal::base< util::ignore , nil<T> >
    {
      typedef util::eat    argument;

      nil();

      void init();
      void take_as_init_(const argument&);
      void take(const argument&);
      void take(const nil<T>&);

      util::ignore to_result() const;

      bool is_valid() const;
    };


    namespace meta
    {


      struct nil : public Meta_Accumulator< nil >
      {
        template <typename V>
        struct with
        {
          typedef accu::nil<V> ret;
        };
      };

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


# ifndef MLN_INCLUDE_ONLY

    template <typename T>
    inline
    nil<T>::nil()
    {
    }

    template <typename T>
    inline
    void
    nil<T>::init()
    {
    }

    template <typename T>
    inline
    void
    nil<T>::take(const argument&)
    {
    }

    template <typename T>
    inline
    void
    nil<T>::take_as_init_(const argument&)
    {
    }

    template <typename T>
    inline
    void
    nil<T>::take(const nil<T>&)
    {
    }

    template <typename T>
    inline
    util::ignore
    nil<T>::to_result() const
    {
      return util::ignore();
    }

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


# endif // ! MLN_INCLUDE_ONLY

  } // end of namespace mln::accu

} // end of namespace mln


#endif // ! MLN_ACCU_NIL_HH