boost/boost/type_traits/is_reference.hpp

   1
   2 //  (C) Copyright David Abrahams Steve Cleary, Beman Dawes, Howard
   3 //  Hinnant & John Maddock 2000-2002.  Permission to copy, use,
   4 //  modify, sell and distribute this software is granted provided this
   5 //  copyright notice appears in all copies. This software is provided
   6 //  "as is" without express or implied warranty, and with no claim as
   7 //  to its suitability for any purpose.
   8 //
   9 //  See http://www.boost.org for most recent version including documentation.
  10
  11 #ifndef BOOST_TT_IS_REFERENCE_HPP_INCLUDED
  12 #define BOOST_TT_IS_REFERENCE_HPP_INCLUDED
  13
  14 #include "boost/type_traits/config.hpp"
  15
  16 #ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  17 #   include "boost/type_traits/detail/yes_no_type.hpp"
  18 #   include "boost/type_traits/detail/wrap.hpp"
  19 #endif
  20
  21 #if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) && defined(BOOST_MSVC)
  22 #   include "boost/type_traits/detail/is_function_type_tester.hpp"
  23 #   include "boost/type_traits/detail/false_result.hpp"
  24 #endif
  25
  26 // should be the last #include
  27 #include "boost/type_traits/detail/bool_trait_def.hpp"
  28
  29 namespace boost {
  30
  31 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  32
  33 BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_reference,T,false)
  34 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_reference,T&,true)
  35
  36 #if defined(__BORLANDC__) && !defined(__COMO__)
  37 // these are illegal specialisations; cv-qualifies applied to
  38 // references have no effect according to [8.3.2p1],
  39 // C++ Builder requires them though as it treats cv-qualified
  40 // references as distinct types...
  41 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_reference,T& const,true)
  42 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_reference,T& volatile,true)
  43 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_reference,T& const volatile,true)
  44 #endif
  45
  46 #if defined(__GNUC__) && (__GNUC__ < 3)
  47 // these allow us to work around illegally cv-qualified reference
  48 // types.
  49 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_reference,T const ,::boost::is_reference<T>::value)
  50 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_reference,T volatile ,::boost::is_reference<T>::value)
  51 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_reference,T const volatile ,::boost::is_reference<T>::value)
  52 // However, the above specializations confuse gcc 2.96 unless we also
  53 // supply these specializations for array types
  54 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_2(typename T,unsigned long N,is_reference,T[N],false)
  55 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_2(typename T,unsigned long N,is_reference,const T[N],false)
  56 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_2(typename T,unsigned long N,is_reference,volatile T[N],false)
  57 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_2(typename T,unsigned long N,is_reference,const volatile T[N],false)
  58 #endif
  59
  60 #else
  61
  62 #ifdef BOOST_MSVC
  63 #   pragma warning(push)
  64 #   pragma warning(disable: 4181)
  65 #endif
  66
  67 namespace detail {
  68
  69 using ::boost::type_traits::yes_type;
  70 using ::boost::type_traits::no_type;
  71 using ::boost::type_traits::wrap;
  72
  73 template <class T> T&(* is_reference_helper1(wrap<T>) )(wrap<T>);
  74 char is_reference_helper1(...);
  75
  76 template <class T> no_type is_reference_helper2(T&(*)(wrap<T>));
  77 yes_type is_reference_helper2(...);
  78
  79 template <typename T>
  80 struct is_reference_impl
  81 {
  82     BOOST_STATIC_CONSTANT(
  83         bool, value = sizeof(
  84             ::boost::detail::is_reference_helper2(
  85                 ::boost::detail::is_reference_helper1(::boost::type_traits::wrap<T>()))) == 1
  86         );
  87 };
  88
  89 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_reference,void,false)
  90 #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS
  91 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_reference,void const,false)
  92 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_reference,void volatile,false)
  93 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_reference,void const volatile,false)
  94 #endif
  95
  96 } // namespace detail
  97
  98 BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_reference,T,::boost::detail::is_reference_impl<T>::value)
  99
 100 #ifdef BOOST_MSVC
 101 #   pragma warning(pop)
 102 #endif
 103
 104 #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
 105
 106 } // namespace boost
 107
 108 #include "boost/type_traits/detail/bool_trait_undef.hpp"
 109
 110 #endif // BOOST_TT_IS_REFERENCE_HPP_INCLUDED
 111