boost/boost/type_traits/is_reference.hpp

   1
   2 //  (C) Copyright Dave Abrahams, Steve Cleary, Beman Dawes,
   3 //      Howard Hinnant and John Maddock 2000.
   4 //  (C) Copyright Mat Marcus, Jesse Jones and Adobe Systems Inc 2001
   5
   6 //  Use, modification and distribution are subject to the Boost Software License,
   7 //  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   8 //  http://www.boost.org/LICENSE_1_0.txt).
   9 //
  10 //  See http://www.boost.org/libs/type_traits for most recent version including documentation.
  11
  12 //    Fixed is_pointer, is_reference, is_const, is_volatile, is_same,
  13 //    is_member_pointer based on the Simulated Partial Specialization work
  14 //    of Mat Marcus and Jesse Jones. See  http://opensource.adobe.com or
  15 //    http://groups.yahoo.com/group/boost/message/5441
  16 //    Some workarounds in here use ideas suggested from "Generic<Programming>:
  17 //    Mappings between Types and Values"
  18 //    by Andrei Alexandrescu (see http://www.cuj.com/experts/1810/alexandr.html).
  19
  20
  21 #ifndef BOOST_TT_IS_REFERENCE_HPP_INCLUDED
  22 #define BOOST_TT_IS_REFERENCE_HPP_INCLUDED
  23
  24 #include "boost/type_traits/config.hpp"
  25
  26 #ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  27 #   include "boost/type_traits/detail/yes_no_type.hpp"
  28 #   include "boost/type_traits/detail/wrap.hpp"
  29 #endif
  30
  31 #if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) && defined(BOOST_MSVC)
  32 #   include "boost/type_traits/detail/is_function_type_tester.hpp"
  33 #   include "boost/type_traits/detail/false_result.hpp"
  34 #endif
  35
  36 // should be the last #include
  37 #include "boost/type_traits/detail/bool_trait_def.hpp"
  38
  39 namespace boost {
  40
  41 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  42
  43 BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_reference,T,false)
  44 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_reference,T&,true)
  45
  46 #if defined(__BORLANDC__) && !defined(__COMO__) && (__BORLANDC__ < 0x600)
  47 // these are illegal specialisations; cv-qualifies applied to
  48 // references have no effect according to [8.3.2p1],
  49 // C++ Builder requires them though as it treats cv-qualified
  50 // references as distinct types...
  51 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_reference,T& const,true)
  52 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_reference,T& volatile,true)
  53 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_reference,T& const volatile,true)
  54 #endif
  55
  56 #if defined(__GNUC__) && (__GNUC__ < 3)
  57 // these allow us to work around illegally cv-qualified reference
  58 // types.
  59 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_reference,T const ,::boost::is_reference<T>::value)
  60 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_reference,T volatile ,::boost::is_reference<T>::value)
  61 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_reference,T const volatile ,::boost::is_reference<T>::value)
  62 // However, the above specializations confuse gcc 2.96 unless we also
  63 // supply these specializations for array types
  64 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_2(typename T,unsigned long N,is_reference,T[N],false)
  65 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_2(typename T,unsigned long N,is_reference,const T[N],false)
  66 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_2(typename T,unsigned long N,is_reference,volatile T[N],false)
  67 BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_2(typename T,unsigned long N,is_reference,const volatile T[N],false)
  68 #endif
  69
  70 #else
  71
  72 #ifdef BOOST_MSVC
  73 #   pragma warning(push)
  74 #   pragma warning(disable: 4181)
  75 #endif
  76
  77 namespace detail {
  78
  79 using ::boost::type_traits::yes_type;
  80 using ::boost::type_traits::no_type;
  81 using ::boost::type_traits::wrap;
  82
  83 template <class T> T&(* is_reference_helper1(wrap<T>) )(wrap<T>);
  84 char is_reference_helper1(...);
  85
  86 template <class T> no_type is_reference_helper2(T&(*)(wrap<T>));
  87 yes_type is_reference_helper2(...);
  88
  89 template <typename T>
  90 struct is_reference_impl
  91 {
  92     BOOST_STATIC_CONSTANT(
  93         bool, value = sizeof(
  94             ::boost::detail::is_reference_helper2(
  95                 ::boost::detail::is_reference_helper1(::boost::type_traits::wrap<T>()))) == 1
  96         );
  97 };
  98
  99 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_reference,void,false)
 100 #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS
 101 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_reference,void const,false)
 102 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_reference,void volatile,false)
 103 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_reference,void const volatile,false)
 104 #endif
 105
 106 } // namespace detail
 107
 108 BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_reference,T,::boost::detail::is_reference_impl<T>::value)
 109
 110 #ifdef BOOST_MSVC
 111 #   pragma warning(pop)
 112 #endif
 113
 114 #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
 115
 116 } // namespace boost
 117
 118 #include "boost/type_traits/detail/bool_trait_undef.hpp"
 119
 120 #endif // BOOST_TT_IS_REFERENCE_HPP_INCLUDED
 121