1 /*============================================================================= 2 Copyright (c) 2001-2006 Joel de Guzman 3 4 Distributed under the Boost Software License, Version 1.0. (See accompanying 5 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 6 ==============================================================================*/ 7 #if !defined(FUSION_PRIOR_05042005_1144) 8 #define FUSION_PRIOR_05042005_1144 9 10 #include <boost/fusion/support/tag_of.hpp> 11 12 namespace boost { namespace fusion 13 { 14 // Special tags: 15 struct iterator_facade_tag; // iterator facade tag 16 struct boost_array_iterator_tag; // boost::array iterator tag 17 struct mpl_iterator_tag; // mpl sequence iterator tag 18 struct std_pair_iterator_tag; // std::pair iterator tag 19 20 namespace extension 21 { 22 template <typename Tag> 23 struct prior_impl 24 { 25 template <typename Iterator> 26 struct apply {}; 27 }; 28 29 template <> 30 struct prior_impl<iterator_facade_tag> 31 { 32 template <typename Iterator> 33 struct apply : Iterator::template prior<Iterator> {}; 34 }; 35 36 template <> 37 struct prior_impl<boost_array_iterator_tag>; 38 39 template <> 40 struct prior_impl<mpl_iterator_tag>; 41 42 template <> 43 struct prior_impl<std_pair_iterator_tag>; 44 } 45 46 namespace result_of 47 { 48 template <typename Iterator> 49 struct prior 50 : extension::prior_impl<typename detail::tag_of<Iterator>::type>:: 51 template apply<Iterator> 52 {}; 53 } 54 55 template <typename Iterator> 56 typename result_of::prior<Iterator>::type const prior(Iterator const & i)57 prior(Iterator const& i) 58 { 59 return result_of::prior<Iterator>::call(i); 60 } 61 }} 62 63 #endif 64