constraints.hh

// constraints.hh: this file is part of the Vaucanson project.
//
// Vaucanson, a generic library for finite state machines.
//
// Copyright (C) 2001, 2002, 2003, 2004, 2005 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_CONSTRAINTS_HH
# define VCSN_MISC_CONSTRAINTS_HH


namespace utility
{

  /*---------------------------.
  | Static constraint checking |
  `---------------------------*/

  // this stuff is heavily inspired from the C++ Boost Library.
  // Use it sparingly, it can cause HUGE amounts of template instanciations.

# if defined(__GNUC__)
#  define UnusedConceptVar __attribute__ ((__unused__))
# else
#  define UnusedConceptVar /* unused */
# endif

  namespace concepts
  {
    template <typename Concept_>
    static void function_requires()
    {
      void (Concept_::*ptr)() UnusedConceptVar = &Concept_::constraints;
    }

    // deep wizardry at work here...

# define UTILITY_CLASS_CHECKING_IDX(Lineno, Concept, T) \
  ConceptChecking##Lineno##_##Concept##T
# define UTILITY_CLASS_CHECKING_ID(Lineno, Concept, T) \
  UTILITY_CLASS_CHECKING_IDX(Lineno, Concept, T)
# define UTILITY_CLASS_FPTR_IDX(Lineno, Concept, T) \
  Concept##Lineno##_fptr_##T
# define UTILITY_CLASS_FPTR_ID(Lineno, Concept, T) \
  UTILITY_CLASS_FPTR_IDX(Lineno, Concept, T)

# ifdef VCSN_NDEBUG

#  define UTILITY_CLASS_REQUIRE_CONCEPT(Var, Namespace, Concept) \
    typedef void UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _t)
#  define UTILITY_CLASS_REQUIRE_CONCEPT2(Var1, Var2, Namespace, Concept) \
    typedef void UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _t)
#  define UTILITY_CLASS_REQUIRE_CONCEPT3(Var1, Var2, Var3, Namespace, Concept) \
    typedef void UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _t)
#  define UTILITY_CLASS_REQUIRE_CONCEPT4(Var1, Var2, Var3, Var4, Namespace, Concept) \
    typedef void UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _t)
#  define UTILITY_REQUIRE_CONCEPT(Var, Namespace, Concept) \
    typedef void UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _t)
#  define UTILITY_REQUIRE_CONCEPT2(Var1, Var2, Namespace, Concept) \
    typedef void UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _t)
#  define UTILITY_REQUIRE_CONCEPT3(Var1, Var2, Var3, Namespace, Concept) \
    typedef void UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _t)
#  define UTILITY_REQUIRE_CONCEPT4(Var1, Var2, Var3, Var4, Namespace, Concept) \
    typedef void UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _t)

# else // VCSN_NDEBUG

    // these should be left 120 columns wide for better readability

#  define UTILITY_CLASS_REQUIRE_CONCEPT(Var, Namespace, Concept)                                        \
  typedef void (Namespace::Concept <Var>::* UTILITY_CLASS_FPTR_ID(__LINE__, Concept, t))();             \
  template <UTILITY_CLASS_FPTR_ID(__LINE__, Concept, t) UTILITY_CLASS_FPTR_ID(__LINE__, Concept, arg)>  \
  struct UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _s) {};                                           \
  typedef UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _s)<& Namespace::Concept<Var>::constraints>      \
        UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _t)

#  define UTILITY_CLASS_REQUIRE_CONCEPT2(Var1, Var2, Namespace, Concept)                                \
  typedef void (Namespace::Concept <Var1,Var2>::* UTILITY_CLASS_FPTR_ID(__LINE__, Concept, t))();       \
  template <UTILITY_CLASS_FPTR_ID(__LINE__, Concept, t) UTILITY_CLASS_FPTR_ID(__LINE__, Concept, arg)>  \
  struct UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _s) {};                                           \
  typedef UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _s)<& Namespace::Concept<Var1,Var2>::constraints> \
        UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _t)

#  define UTILITY_CLASS_REQUIRE_CONCEPT3(Var1, Var2, Var3, Namespace, Concept)                          \
  typedef void (Namespace::Concept <Var1,Var2,Var3>::* UTILITY_CLASS_FPTR_ID(__LINE__, Concept, t))();  \
  template <UTILITY_CLASS_FPTR_ID(__LINE__, Concept, t) UTILITY_CLASS_FPTR_ID(__LINE__, Concept, arg)>  \
  struct UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _s) {};                                           \
  typedef UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _s)<& Namespace::Concept<Var1,Var2,Var3>::constraints> \
        UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _t)

#  define UTILITY_CLASS_REQUIRE_CONCEPT4(Var1, Var2, Var3, Var4, Namespace, Concept)                    \
  typedef void (Namespace::Concept <Var1,Var2,Var3,Var4>::* UTILITY_CLASS_FPTR_ID(__LINE__, Concept, t))();\
  template <UTILITY_CLASS_FPTR_ID(__LINE__, Concept, t) UTILITY_CLASS_FPTR_ID(__LINE__, Concept, arg)>  \
  struct UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _s) {};                                           \
  typedef UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _s)<& Namespace::Concept<Var1,Var2,Var3,Var4>::constraints> \
        UTILITY_CLASS_CHECKING_ID(__LINE__, Concept, _t)

#  define UTILITY_REQUIRE_CONCEPT(Var, Namespace, Concept) \
  utility::concepts::function_requires<Namespace::Concept <Var> >()
#  define UTILITY_REQUIRE_CONCEPT2(Var1, Var2, Namespace, Concept) \
  utility::concepts::function_requires<Namespace::Concept <Var1, Var2> >()
#  define UTILITY_REQUIRE_CONCEPT3(Var1, Var2, Var3, Namespace, Concept) \
  utility::concepts::function_requires<Namespace::Concept <Var1, Var2, Var3> >()
#  define UTILITY_REQUIRE_CONCEPT4(Var1, Var2, Var3, Var4, Namespace, Concept) \
  utility::concepts::function_requires<Namespace::Concept <Var1, Var2, Var3, Var4> >()

# endif // ! VCSN_NDEBUG

  } // concepts
} // utility

#endif // ! VCSN_MISC_CONSTRAINTS_HH

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