/*============================================================================= | |
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 |