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68 lines
2.2 KiB
68 lines
2.2 KiB
/*============================================================================= |
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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_STRICTEST_TRAVERSAL_20060123_2101) |
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#define FUSION_STRICTEST_TRAVERSAL_20060123_2101 |
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#include <boost/mpl/or.hpp> |
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#include <boost/mpl/if.hpp> |
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#include <boost/fusion/support/category_of.hpp> |
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#include <boost/fusion/mpl.hpp> |
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#include <boost/fusion/algorithm/iteration/fold.hpp> |
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#include <boost/type_traits/remove_reference.hpp> |
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#include <boost/type_traits/is_convertible.hpp> |
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namespace boost { namespace fusion |
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{ |
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struct forward_traversal_tag; |
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struct bidirectional_traversal_tag; |
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struct random_access_traversal_tag; |
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namespace detail |
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{ |
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template<typename Tag1, typename Tag2, |
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bool Tag1Stricter = boost::is_convertible<Tag2,Tag1>::value> |
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struct stricter_traversal |
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{ |
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typedef Tag1 type; |
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}; |
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template<typename Tag1, typename Tag2> |
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struct stricter_traversal<Tag1,Tag2,false> |
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{ |
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typedef Tag2 type; |
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}; |
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struct strictest_traversal_impl |
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{ |
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template<typename Sig> |
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struct result; |
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template<typename StrictestSoFar, typename Next> |
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struct result<strictest_traversal_impl(StrictestSoFar, Next)> |
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{ |
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typedef typename remove_reference<Next>::type next_value; |
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typedef typename remove_reference<StrictestSoFar>::type strictest_so_far; |
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typedef strictest_so_far tag1; |
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typedef typename traits::category_of<next_value>::type tag2; |
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typedef typename stricter_traversal<tag1,tag2>::type type; |
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}; |
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}; |
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template<typename Sequence> |
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struct strictest_traversal |
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: result_of::fold< |
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Sequence, fusion::random_access_traversal_tag, |
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strictest_traversal_impl> |
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{}; |
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} |
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}} |
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#endif
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