deferrer.hh

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// deferrer.hh: this file is part of the Vaucanson project.
//
// Vaucanson, a generic library for finite state machines.
//
// Copyright (C) 2004, 2005, 2006 The Vaucanson Group.
//
// This program 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; either version 2
// of the License, or (at your option) any later version.
//
// The complete GNU General Public Licence Notice can be found as the
// `COPYING' file in the root directory.
//
// The Vaucanson Group consists of people listed in the `AUTHORS' file.
//
#ifndef VCSN_MISC_DEFERRER_HH
# define VCSN_MISC_DEFERRER_HH
 
namespace vcsn
{
  namespace misc
  {

# ifndef VCSN_NDEBUG
    enum { deferrer_runtime_checks_default = true };
# else // VCSN_NDEBUG
    enum { deferrer_runtime_checks_default = false };
# endif // ! VCSN_NDEBUG


    template <class T, bool B>
    struct DeferrerDebugPart
    {
      protected:
        // Defaults to true.
        DeferrerDebugPart (void* ptr, bool is_valid = false);

        void     set_valid (bool b);
        T&       cast (void*);
        const T& cast (const void*) const;

        bool is_valid_;
    };

    template <class T>
    struct DeferrerDebugPart<T, false>
    {
      protected:
        // False version.
        DeferrerDebugPart (void* ptr, bool is_valid = false);
        void     set_valid (bool b);
        T&       cast (void*);
        const T& cast (const void*) const;
    };
    template <class T, bool rt_checks = deferrer_runtime_checks_default>
    struct Deferrer : DeferrerDebugPart<T, rt_checks>
    {
        typedef T deferred_type;

        Deferrer ();

        Deferrer&
        operator= (const deferred_type&);

        operator T () const;
      protected:
        typedef unsigned char data_t[sizeof (deferred_type)];

        data_t data;
    };

  } // End of namespace misc.
} // End of namespace vcsn.

# if !defined VCSN_USE_INTERFACE_ONLY || defined VCSN_USE_LIB
#  include <vaucanson/misc/deferrer.hxx>
# endif // VCSN_USE_INTERFACE_ONLY

#endif // ! VCSN_MISC_DEFERRER_HH