| /*============================================================================= |
| Copyright (c) 2001-2006 Joel de Guzman |
| |
| 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_09172005_0721) |
| #define FUSION_DISTANCE_09172005_0721 |
| |
| #include <boost/fusion/iterator/detail/distance.hpp> |
| #include <boost/fusion/support/category_of.hpp> |
| |
| #include <boost/mpl/int.hpp> |
| #include <boost/mpl/assert.hpp> |
| #include <boost/type_traits/is_same.hpp> |
| |
| #include <boost/fusion/support/tag_of.hpp> |
| |
| namespace boost { namespace fusion |
| { |
| struct random_access_traversal_tag; |
| |
| // Special tags: |
| struct iterator_facade_tag; // iterator facade tag |
| struct boost_array_iterator_tag; // boost::array iterator tag |
| struct mpl_iterator_tag; // mpl sequence iterator tag |
| struct std_pair_iterator_tag; // std::pair iterator tag |
| |
| namespace extension |
| { |
| template <typename Tag> |
| struct distance_impl |
| { |
| // default implementation |
| template <typename First, typename Last> |
| struct apply : distance_detail::linear_distance<First, Last> |
| { |
| BOOST_MPL_ASSERT_NOT((traits::is_random_access<First>)); |
| BOOST_MPL_ASSERT_NOT((traits::is_random_access<Last>)); |
| }; |
| }; |
| |
| template <> |
| struct distance_impl<iterator_facade_tag> |
| { |
| template <typename First, typename Last> |
| struct apply : First::template distance<First, Last> {}; |
| }; |
| |
| template <> |
| struct distance_impl<boost_array_iterator_tag>; |
| |
| template <> |
| struct distance_impl<mpl_iterator_tag>; |
| |
| template <> |
| struct distance_impl<std_pair_iterator_tag>; |
| } |
| |
| namespace result_of |
| { |
| template <typename First, typename Last> |
| struct distance |
| : extension::distance_impl<typename detail::tag_of<First>::type>:: |
| template apply<First, Last> |
| { |
| typedef typename extension::distance_impl<typename detail::tag_of<First>::type>:: |
| template apply<First, Last>::type distance_application; |
| BOOST_STATIC_CONSTANT(int, value = distance_application::value); |
| }; |
| } |
| |
| template <typename First, typename Last> |
| inline typename result_of::distance<First, Last>::type |
| distance(First const& a, Last const& b) |
| { |
| return result_of::distance<First, Last>::call(a,b); |
| } |
| }} |
| |
| #endif |