boost/type_traits/add_reference.hpp

   1
   2 //  (C) Copyright Steve Cleary, Beman Dawes, Howard Hinnant & John Maddock 2000.
   3 //  Use, modification and distribution are subject to the Boost Software License,
   4 //  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   5 //  http://www.boost.org/LICENSE_1_0.txt).
   6 //
   7 //  See http://www.boost.org/libs/type_traits for most recent version including documentation.
   8
   9 #ifndef BOOST_TT_ADD_REFERENCE_HPP_INCLUDED
  10 #define BOOST_TT_ADD_REFERENCE_HPP_INCLUDED
  11
  12 #include <boost/type_traits/is_reference.hpp>
  13 #include <boost/detail/workaround.hpp>
  14 #include <boost/config.hpp>
  15
  16 // should be the last #include
  17 #include <boost/type_traits/detail/type_trait_def.hpp>
  18
  19 namespace boost {
  20
  21 namespace detail {
  22
  23 #if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) && defined(BOOST_MSVC6_MEMBER_TEMPLATES)
  24
  25 template <bool x>
  26 struct reference_adder
  27 {
  28     template <typename T> struct result_
  29     {
  30         typedef T& type;
  31     };
  32 };
  33
  34 template <>
  35 struct reference_adder<true>
  36 {
  37     template <typename T> struct result_
  38     {
  39         typedef T type;
  40     };
  41 };
  42
  43 template <typename T>
  44 struct add_reference_impl
  45 {
  46     typedef typename reference_adder<
  47           ::boost::is_reference<T>::value
  48         >::template result_<T> result;
  49
  50     typedef typename result::type type;
  51 };
  52
  53 #else
  54 //
  55 // We can't filter out rvalue_references at the same level as
  56 // references or we get ambiguities from msvc:
  57 //
  58
  59 template <typename T>
  60 struct add_reference_rvalue_layer
  61 {
  62     typedef T& type;
  63 };
  64
  65 #ifndef BOOST_NO_RVALUE_REFERENCES
  66 template <typename T>
  67 struct add_reference_rvalue_layer<T&&>
  68 {
  69     typedef T&& type;
  70 };
  71 #endif
  72
  73 template <typename T>
  74 struct add_reference_impl
  75 {
  76     typedef typename add_reference_rvalue_layer<T>::type type;
  77 };
  78
  79 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  80 BOOST_TT_AUX_TYPE_TRAIT_IMPL_PARTIAL_SPEC1_1(typename T,add_reference,T&,T&)
  81 #endif
  82
  83 #endif
  84
  85 // these full specialisations are always required:
  86 BOOST_TT_AUX_TYPE_TRAIT_IMPL_SPEC1(add_reference,void,void)
  87 #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS
  88 BOOST_TT_AUX_TYPE_TRAIT_IMPL_SPEC1(add_reference,void const,void const)
  89 BOOST_TT_AUX_TYPE_TRAIT_IMPL_SPEC1(add_reference,void volatile,void volatile)
  90 BOOST_TT_AUX_TYPE_TRAIT_IMPL_SPEC1(add_reference,void const volatile,void const volatile)
  91 #endif
  92
  93 } // namespace detail
  94
  95 BOOST_TT_AUX_TYPE_TRAIT_DEF1(add_reference,T,typename boost::detail::add_reference_impl<T>::type)
  96
  97 // agurt, 07/mar/03: workaround Borland's ill-formed sensitivity to an additional
  98 // level of indirection, here
  99 #if BOOST_WORKAROUND(__BORLANDC__, < 0x600)
 100 BOOST_TT_AUX_TYPE_TRAIT_PARTIAL_SPEC1_1(typename T,add_reference,T&,T&)
 101 #endif
 102
 103 } // namespace boost
 104
 105 #include <boost/type_traits/detail/type_trait_undef.hpp>
 106
 107 #endif // BOOST_TT_ADD_REFERENCE_HPP_INCLUDED