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Viewing changes to boost/boost/fusion/view/zip_view/detail/distance_impl.hpp

  • Committer: bigmuscle
  • Date: 2010-05-08 08:47:15 UTC
  • Revision ID: svn-v4:5fb55d53-692c-0410-a46a-e90ab66e00ee:trunk:497
removed old boost version

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boost/boost/fusion/view/zip_view/detail/distance_impl.hpp
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/*=============================================================================
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    Copyright (c) 2001-2006 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/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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                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