1 // Boost.Range library 2 // 3 // Copyright Neil Groves 2010. Use, modification and 4 // distribution is subject to the Boost Software License, Version 5 // 1.0. (See accompanying file LICENSE_1_0.txt or copy at 6 // http://www.boost.org/LICENSE_1_0.txt) 7 // 8 // For more information, see http://www.boost.org/libs/range/ 9 // 10 // Acknowledgments: 11 // Ticket #8341: Arno Schoedl - improved handling of has_range_iterator upon 12 // use-cases where T was const. 13 #ifndef BOOST_RANGE_HAS_ITERATOR_HPP_INCLUDED 14 #define BOOST_RANGE_HAS_ITERATOR_HPP_INCLUDED 15 16 #include <boost/mpl/bool.hpp> 17 #include <boost/mpl/eval_if.hpp> 18 #include <boost/mpl/has_xxx.hpp> 19 #include <boost/range/iterator.hpp> 20 #include <boost/type_traits/remove_reference.hpp> 21 #include <boost/utility/enable_if.hpp> 22 23 namespace boost 24 { 25 namespace range_detail 26 { 27 BOOST_MPL_HAS_XXX_TRAIT_DEF(type) 28 29 template<class T, class Enabler = void> 30 struct has_range_iterator_impl 31 : boost::mpl::false_ 32 { 33 }; 34 35 template<class T> 36 struct has_range_iterator_impl< 37 T, 38 BOOST_DEDUCED_TYPENAME ::boost::enable_if< 39 BOOST_DEDUCED_TYPENAME mpl::eval_if<is_const<T>, 40 has_type<boost::range_const_iterator< 41 BOOST_DEDUCED_TYPENAME remove_const<T>::type> >, 42 has_type<boost::range_mutable_iterator<T> > 43 >::type 44 >::type 45 > 46 : boost::mpl::true_ 47 { 48 }; 49 50 template<class T, class Enabler = void> 51 struct has_range_const_iterator_impl 52 : boost::mpl::false_ 53 { 54 }; 55 56 template<class T> 57 struct has_range_const_iterator_impl< 58 T, 59 BOOST_DEDUCED_TYPENAME ::boost::enable_if< 60 has_type<boost::range_const_iterator<T> > 61 >::type 62 > 63 : boost::mpl::true_ 64 { 65 }; 66 67 } // namespace range_detail 68 69 template<class T> 70 struct has_range_iterator 71 : range_detail::has_range_iterator_impl< 72 BOOST_DEDUCED_TYPENAME remove_reference<T>::type> 73 {}; 74 75 template<class T> 76 struct has_range_const_iterator 77 : range_detail::has_range_const_iterator_impl< 78 BOOST_DEDUCED_TYPENAME remove_reference<T>::type> 79 {}; 80 } // namespace boost 81 82 #endif // include guard 83 84