value.hh

// Copyright (C) 2001, 2002, 2003  EPITA Research and Development Laboratory
//
// This file is part of the Olena Library.  This library is free
// software; you can redistribute it and/or modify it under the terms
// of the GNU General Public License version 2 as published by the
// Free Software Foundation.
//
// This library 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 this library; see the file COPYING.  If not, write to
// the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
// MA 02111-1307, USA.
//
// As a special exception, you may use this file as part of a free
// software library 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 NTG_CORE_VALUE_HH
# define NTG_CORE_VALUE_HH

# include <ntg/core/macros.hh>
# include <ntg/core/type.hh>
# include <ntg/core/type_traits.hh>

namespace ntg {

  namespace internal {

    /*---------.
    | any_ntg_ |
    `---------*/

    // FIXME: it is not possible to inherit from mlc::any, because it
    // gives all subtypes an implicit access to the mlc
    // namespace. This is problematic since min or max for example are
    // defined in mlc and ntg::internal namespaces, and it creates
    // conflicts with g++ (3.2, 3.3, 3.4).


    template <class E>
    class any_ntg_ : public ntg::any<E>
    {};

  } // end of internal.

  /*--------.
  | any_ntg |
  `--------*/


  template <class E>
  class any_ntg : public internal::any_ntg_<E>
  {};

  /*------.
  | value |
  `------*/


  template <class E>
  class value : public any_ntg<E>
  {
    // note: here it is not possible to use ntg::type_traits,
    // because of recursive instanciation problems.
    typedef typename internal::typetraits<E>::storage_type storage_type;

  public:
    // Hooks
    storage_type& val() { return val_; }
    const storage_type& val() const { return val_; }

  protected:
    storage_type val_;
  };

  namespace internal {
    
    template <class E>
    struct typetraits<value<E> >
    {
      typedef E unsafe_type;
    };

    template <class E>
    struct optraits<value<E> >
    {};

  }

} // end of ntg.

#endif // !NTG_CORE_VALUE_HH

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