boost/fusion/iterator/advance.hpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2006 Joel de Guzman
   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(FUSION_ADVANCE_09172005_1146)
   8 #define FUSION_ADVANCE_09172005_1146
   9
  10 #include <boost/fusion/iterator/detail/advance.hpp>
  11 #include <boost/fusion/support/category_of.hpp>
  12
  13 #include <boost/mpl/int.hpp>
  14 #include <boost/mpl/assert.hpp>
  15 #include <boost/type_traits/is_same.hpp>
  16 #include <boost/fusion/support/tag_of.hpp>
  17
  18 namespace boost { namespace fusion
  19 {
  20     struct random_access_traversal_tag;
  21
  22     // Special tags:
  23     struct iterator_facade_tag; // iterator facade tag
  24     struct array_iterator_tag; // boost::array iterator tag
  25     struct mpl_iterator_tag; // mpl sequence iterator tag
  26     struct std_pair_iterator_tag; // std::pair iterator tag
  27
  28     namespace extension
  29     {
  30         template <typename Tag>
  31         struct advance_impl
  32         {
  33             // default implementation
  34             template <typename Iterator, typename N>
  35             struct apply :
  36                 mpl::if_c<
  37                     (N::value > 0)
  38                   , advance_detail::forward<Iterator, N::value>
  39                   , advance_detail::backward<Iterator, N::value>
  40                 >::type
  41             {
  42                 BOOST_MPL_ASSERT_NOT((traits::is_random_access<Iterator>));
  43             };
  44         };
  45
  46         template <>
  47         struct advance_impl<iterator_facade_tag>
  48         {
  49             template <typename Iterator, typename N>
  50             struct apply : Iterator::template advance<Iterator, N> {};
  51         };
  52
  53         template <>
  54         struct advance_impl<array_iterator_tag>;
  55
  56         template <>
  57         struct advance_impl<mpl_iterator_tag>;
  58
  59         template <>
  60         struct advance_impl<std_pair_iterator_tag>;
  61     }
  62
  63     namespace result_of
  64     {
  65         template <typename Iterator, int N>
  66         struct advance_c
  67             : extension::advance_impl<typename detail::tag_of<Iterator>::type>::template apply<Iterator, mpl::int_<N> >
  68         {};
  69
  70         template <typename Iterator, typename N>
  71         struct advance
  72             : extension::advance_impl<typename detail::tag_of<Iterator>::type>::template apply<Iterator, N>
  73         {};
  74     }
  75
  76     template <int N, typename Iterator>
  77     inline typename result_of::advance_c<Iterator, N>::type const
  78     advance_c(Iterator const& i)
  79     {
  80         return result_of::advance_c<Iterator, N>::call(i);
  81     }
  82
  83     template<typename N, typename Iterator>
  84     inline typename result_of::advance<Iterator, N>::type const
  85     advance(Iterator const& i)
  86     {
  87         return result_of::advance<Iterator, N>::call(i);
  88     }
  89
  90 }} // namespace boost::fusion
  91
  92 #endif