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