ceph/src/boost/boost/iterator/is_readable_iterator.hpp

   1 // Copyright David Abrahams 2003. Use, modification and distribution is
   2 // subject to the Boost Software License, Version 1.0. (See accompanying
   3 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   4 #ifndef IS_READABLE_ITERATOR_DWA2003112_HPP
   5 # define IS_READABLE_ITERATOR_DWA2003112_HPP
   6
   7 #include <boost/mpl/bool.hpp>
   8 #include <boost/mpl/aux_/lambda_support.hpp>
   9 #include <boost/type_traits/add_lvalue_reference.hpp>
  10
  11 #include <boost/iterator/detail/any_conversion_eater.hpp>
  12
  13 #include <iterator>
  14
  15 // should be the last #include
  16 #include <boost/type_traits/integral_constant.hpp>
  17 #include <boost/iterator/detail/config_def.hpp>
  18
  19 #ifndef BOOST_NO_IS_CONVERTIBLE
  20
  21 namespace boost {
  22
  23 namespace iterators {
  24
  25 namespace detail
  26 {
  27   // Guts of is_readable_iterator.  Value is the iterator's value_type
  28   // and the result is computed in the nested rebind template.
  29   template <class Value>
  30   struct is_readable_iterator_impl
  31   {
  32       static char tester(typename add_lvalue_reference<Value>::type, int);
  33       static char (& tester(any_conversion_eater, ...) )[2];
  34
  35       template <class It>
  36       struct rebind
  37       {
  38           static It& x;
  39
  40           BOOST_STATIC_CONSTANT(
  41               bool
  42             , value = (
  43                 sizeof(
  44                     is_readable_iterator_impl<Value>::tester(*x, 1)
  45                 ) == 1
  46             )
  47           );
  48       };
  49   };
  50
  51 #undef BOOST_READABLE_PRESERVER
  52
  53   //
  54   // void specializations to handle std input and output iterators
  55   //
  56   template <>
  57   struct is_readable_iterator_impl<void>
  58   {
  59       template <class It>
  60       struct rebind : boost::mpl::false_
  61       {};
  62   };
  63
  64 #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS
  65   template <>
  66   struct is_readable_iterator_impl<const void>
  67   {
  68       template <class It>
  69       struct rebind : boost::mpl::false_
  70       {};
  71   };
  72
  73   template <>
  74   struct is_readable_iterator_impl<volatile void>
  75   {
  76       template <class It>
  77       struct rebind : boost::mpl::false_
  78       {};
  79   };
  80
  81   template <>
  82   struct is_readable_iterator_impl<const volatile void>
  83   {
  84       template <class It>
  85       struct rebind : boost::mpl::false_
  86       {};
  87   };
  88 #endif
  89
  90   //
  91   // This level of dispatching is required for Borland.  We might save
  92   // an instantiation by removing it for others.
  93   //
  94   template <class It>
  95   struct is_readable_iterator_impl2
  96     : is_readable_iterator_impl<
  97           BOOST_DEDUCED_TYPENAME std::iterator_traits<It>::value_type const
  98       >::template rebind<It>
  99   {};
 100 } // namespace detail
 101
 102 template< typename T > struct is_readable_iterator
 103 : public ::boost::integral_constant<bool,::boost::iterators::detail::is_readable_iterator_impl2<T>::value>
 104 {
 105 public:
 106     BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_readable_iterator,(T))
 107 };
 108
 109 } // namespace iterators
 110
 111 using iterators::is_readable_iterator;
 112
 113 } // namespace boost
 114
 115 #endif
 116
 117 #include <boost/iterator/detail/config_undef.hpp>
 118
 119 #endif // IS_READABLE_ITERATOR_DWA2003112_HPP