85 lines
3.2 KiB
Plaintext
85 lines
3.2 KiB
Plaintext
/*=============================================================================
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Copyright (c) 2001-2011 Joel de Guzman
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Copyright (c) 2006 Dan Marsden
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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==============================================================================*/
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#if !defined(FUSION_DISTANCE_IMPL_20060124_2033)
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#define FUSION_DISTANCE_IMPL_20060124_2033
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#include <boost/fusion/support/config.hpp>
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#include <boost/mpl/eval_if.hpp>
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#include <boost/mpl/placeholders.hpp>
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#include <boost/mpl/assert.hpp>
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#include <boost/fusion/iterator/distance.hpp>
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#include <boost/fusion/support/category_of.hpp>
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#include <boost/fusion/algorithm/query/find_if.hpp>
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#include <boost/fusion/sequence/intrinsic/end.hpp>
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#include <boost/fusion/sequence/intrinsic/value_at.hpp>
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#include <boost/type_traits/is_same.hpp>
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namespace boost { namespace fusion {
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struct zip_view_iterator_tag;
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struct random_access_iterator_tag;
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namespace detail
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{
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template<typename FoundIt, typename SearchIt>
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struct best_distance
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{
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typedef typename result_of::find_if<
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typename SearchIt::iterators, is_same<traits::category_of<mpl::_>, random_access_iterator_tag> > finder;
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BOOST_MPL_ASSERT_NOT((is_same<typename finder::type, result_of::end<typename SearchIt::iterators> >));
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typedef typename result_of::distance<FoundIt, typename finder::type>::type type;
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};
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template<typename It1, typename It2>
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struct default_distance
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: result_of::distance<
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typename result_of::value_at_c<typename It1::iterators, 0>::type,
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typename result_of::value_at_c<typename It2::iterators, 0>::type>
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{};
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template<typename It1, typename It2>
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struct zip_view_iterator_distance
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{
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typedef typename result_of::find_if<
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typename It1::iterators, is_same<traits::category_of<mpl::_>, random_access_iterator_tag> > finder;
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typedef typename mpl::eval_if<
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is_same<typename finder::type, typename result_of::end<typename It1::iterators>::type>,
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detail::default_distance<It1, It2> ,
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detail::best_distance<typename finder::type, It2> >::type type;
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};
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}
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namespace extension
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{
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template<typename Tag>
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struct distance_impl;
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template<>
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struct distance_impl<zip_view_iterator_tag>
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{
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template<typename It1, typename It2>
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struct apply
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: detail::zip_view_iterator_distance<It1, It2>::type
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{
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BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
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static typename detail::zip_view_iterator_distance<It1, It2>::type
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call(It1 const& /*it1*/, It2 const& /*it2*/)
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{
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return typename detail::zip_view_iterator_distance<It1, It2>::type();
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}
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};
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};
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}
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}}
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#endif
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