| 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 |
| 119 |