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