boost/fusion/sequence/intrinsic/segments.hpp

   1 /*=============================================================================
   2     Copyright (c) 2006 Eric Niebler
   3
   4     Distributed under the Boost Software License, Version 1.0. (See accompanying
   5     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 ==============================================================================*/
   7 #if !defined(BOOST_FUSION_SEGMENTS_04052005_1141)
   8 #define BOOST_FUSION_SEGMENTS_04052005_1141
   9
  10 #include <boost/type_traits/is_const.hpp>
  11 #include <boost/utility/enable_if.hpp>
  12 #include <boost/fusion/sequence/intrinsic_fwd.hpp>
  13 #include <boost/fusion/support/tag_of.hpp>
  14
  15 namespace boost { namespace fusion
  16 {
  17     // Special tags:
  18     struct sequence_facade_tag;
  19     struct iterator_range_tag;
  20
  21     // segments: returns a sequence of sequences
  22     namespace extension
  23     {
  24         template <typename Tag>
  25         struct segments_impl
  26         {
  27             template <typename Sequence>
  28             struct apply {};
  29         };
  30
  31         template <>
  32         struct segments_impl<sequence_facade_tag>
  33         {
  34             template <typename Sequence>
  35             struct apply : Sequence::template segments<Sequence> {};
  36         };
  37
  38         template <>
  39         struct segments_impl<iterator_range_tag>;
  40     }
  41
  42     namespace result_of
  43     {
  44         template <typename Sequence>
  45         struct segments
  46         {
  47             typedef typename traits::tag_of<Sequence>::type tag_type;
  48
  49             typedef typename
  50                 extension::segments_impl<tag_type>::template apply<Sequence>::type
  51             type;
  52         };
  53     }
  54
  55     template <typename Sequence>
  56     inline typename
  57         lazy_disable_if<
  58             is_const<Sequence>
  59           , result_of::segments<Sequence>
  60         >::type
  61     segments(Sequence& seq)
  62     {
  63         typedef typename traits::tag_of<Sequence>::type tag_type;
  64         return extension::segments_impl<tag_type>::template apply<Sequence>::call(seq);
  65     }
  66
  67     template <typename Sequence>
  68     inline typename result_of::segments<Sequence const>::type
  69     segments(Sequence const& seq)
  70     {
  71         typedef typename traits::tag_of<Sequence const>::type tag_type;
  72         return extension::segments_impl<tag_type>::template apply<Sequence const>::call(seq);
  73     }
  74 }}
  75
  76 #endif