boost/boost/type_traits/add_rvalue_reference.hpp

   1 //  add_rvalue_reference.hpp  ---------------------------------------------------------//
   2
   3 //  Copyright 2010 Vicente J. Botet Escriba
   4
   5 //  Distributed under the Boost Software License, Version 1.0.
   6 //  See http://www.boost.org/LICENSE_1_0.txt
   7
   8 #ifndef BOOST_TYPE_TRAITS_EXT_ADD_RVALUE_REFERENCE__HPP
   9 #define BOOST_TYPE_TRAITS_EXT_ADD_RVALUE_REFERENCE__HPP
  10
  11 #include <boost/config.hpp>
  12
  13 //----------------------------------------------------------------------------//
  14
  15 #include <boost/type_traits/is_void.hpp>
  16 #include <boost/type_traits/is_reference.hpp>
  17
  18 // should be the last #include
  19 #include <boost/type_traits/detail/type_trait_def.hpp>
  20
  21 //----------------------------------------------------------------------------//
  22 //                                                                            //
  23 //                           C++03 implementation of                          //
  24 //             20.7.6.2 Reference modifications [meta.trans.ref]              //
  25 //                          Written by Vicente J. Botet Escriba               //
  26 //                                                                            //
  27 // If T names an object or function type then the member typedef type
  28 // shall name T&&; otherwise, type shall name T. [ Note: This rule reflects
  29 // the semantics of reference collapsing. For example, when a type T names
  30 // a type T1&, the type add_rvalue_reference<T>::type is not an rvalue
  31 // reference. -end note ]
  32 //----------------------------------------------------------------------------//
  33
  34 namespace boost {
  35
  36 namespace type_traits_detail {
  37
  38     template <typename T, bool b>
  39     struct add_rvalue_reference_helper
  40     { typedef T   type; };
  41
  42     template <typename T>
  43     struct add_rvalue_reference_helper<T, true>
  44     {
  45 #if !defined(BOOST_NO_RVALUE_REFERENCES)
  46         typedef T&&   type;
  47 #else
  48         typedef T   type;
  49 #endif
  50     };
  51
  52     template <typename T>
  53     struct add_rvalue_reference_imp
  54     {
  55        typedef typename boost::type_traits_detail::add_rvalue_reference_helper
  56                   <T, (!is_void<T>::value && !is_reference<T>::value) >::type type;
  57     };
  58
  59 }
  60
  61 BOOST_TT_AUX_TYPE_TRAIT_DEF1(add_rvalue_reference,T,typename boost::type_traits_detail::add_rvalue_reference_imp<T>::type)
  62
  63 }  // namespace boost
  64
  65 #include <boost/type_traits/detail/type_trait_undef.hpp>
  66
  67 #endif  // BOOST_TYPE_TRAITS_EXT_ADD_RVALUE_REFERENCE__HPP
  68