| /*============================================================================= |
| Copyright (c) 2001-2006 Joel de Guzman |
| Copyright (c) 2006 Dan Marsden |
| |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| ==============================================================================*/ |
| #if !defined(FUSION_DISTANCE_IMPL_20060124_2033) |
| #define FUSION_DISTANCE_IMPL_20060124_2033 |
| |
| #include <boost/mpl/eval_if.hpp> |
| #include <boost/mpl/placeholders.hpp> |
| #include <boost/mpl/assert.hpp> |
| #include <boost/fusion/iterator/distance.hpp> |
| #include <boost/fusion/support/category_of.hpp> |
| #include <boost/fusion/algorithm/query/find_if.hpp> |
| #include <boost/fusion/sequence/intrinsic/end.hpp> |
| #include <boost/fusion/sequence/intrinsic/value_at.hpp> |
| #include <boost/type_traits/is_same.hpp> |
| |
| namespace boost { namespace fusion { |
| |
| struct zip_view_iterator_tag; |
| |
| struct random_access_iterator_tag; |
| |
| namespace detail |
| { |
| template<typename FoundIt, typename SearchIt> |
| struct best_distance |
| { |
| typedef typename result_of::find_if< |
| typename SearchIt::iterators, is_same<traits::category_of<mpl::_>, random_access_iterator_tag> > finder; |
| |
| BOOST_MPL_ASSERT_NOT((is_same<typename finder::type, result_of::end<typename SearchIt::iterators> >)); |
| |
| typedef typename result_of::distance<FoundIt, typename finder::type>::type type; |
| }; |
| |
| template<typename It1, typename It2> |
| struct default_distance |
| : result_of::distance< |
| typename result_of::value_at_c<typename It1::iterators, 0>::type, |
| typename result_of::value_at_c<typename It2::iterators, 0>::type> |
| {}; |
| |
| template<typename It1, typename It2> |
| struct zip_view_iterator_distance |
| { |
| typedef typename result_of::find_if< |
| typename It1::iterators, is_same<traits::category_of<mpl::_>, random_access_iterator_tag> > finder; |
| |
| typedef typename mpl::eval_if< |
| is_same<typename finder::type, typename result_of::end<typename It1::iterators>::type>, |
| detail::default_distance<It1, It2> , |
| detail::best_distance<typename finder::type, It2> >::type type; |
| }; |
| } |
| |
| namespace extension |
| { |
| template<typename Tag> |
| struct distance_impl; |
| |
| template<> |
| struct distance_impl<zip_view_iterator_tag> |
| { |
| template<typename It1, typename It2> |
| struct apply |
| : detail::zip_view_iterator_distance<It1, It2>::type |
| { |
| static typename detail::zip_view_iterator_distance<It1, It2>::type |
| call(It1 const& /*it1*/, It2 const& /*it2*/) |
| { |
| return typename detail::zip_view_iterator_distance<It1, It2>::type(); |
| } |
| }; |
| }; |
| } |
| }} |
| |
| #endif |