boost/fusion/iterator/mpl/fusion_iterator.hpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2011 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_FUSION_ITERATOR_10012005_1551)
   8 #define FUSION_FUSION_ITERATOR_10012005_1551
   9
  10 #include <boost/fusion/support/config.hpp>
  11 #include <boost/fusion/iterator/value_of.hpp>
  12 #include <boost/fusion/iterator/next.hpp>
  13 #include <boost/fusion/iterator/prior.hpp>
  14 #include <boost/fusion/iterator/advance.hpp>
  15 #include <boost/fusion/iterator/distance.hpp>
  16 #include <boost/fusion/support/category_of.hpp>
  17 #include <boost/mpl/next_prior.hpp>
  18 #include <boost/mpl/advance_fwd.hpp>
  19 #include <boost/mpl/distance_fwd.hpp>
  20 #include <boost/mpl/iterator_tags.hpp>
  21 #include <boost/mpl/eval_if.hpp>
  22 #include <boost/type_traits/is_base_of.hpp>
  23
  24 namespace boost { namespace fusion { namespace detail
  25 {
  26
  27 template<class Category>
  28 struct to_mpl_category {
  29     typedef typename mpl::eval_if<
  30         is_base_of<random_access_traversal_tag, Category>,
  31         mpl::random_access_iterator_tag,
  32         mpl::eval_if<
  33             is_base_of<bidirectional_traversal_tag, Category>,
  34             mpl::bidirectional_iterator_tag,
  35             mpl::forward_iterator_tag
  36         >
  37     >::type type;
  38 };
  39
  40 }}}
  41
  42 namespace boost { namespace mpl
  43 {
  44     template <typename Iterator>
  45     struct fusion_iterator
  46     {
  47         typedef typename fusion::result_of::value_of<Iterator>::type type;
  48         typedef typename fusion::traits::category_of<Iterator>::type fusion_category;
  49         typedef typename fusion::detail::to_mpl_category<fusion_category>::type category;
  50         typedef Iterator iterator;
  51     };
  52
  53     template <typename Iterator>
  54     struct next<fusion_iterator<Iterator> >
  55     {
  56         typedef fusion_iterator<typename fusion::result_of::next<Iterator>::type> type;
  57     };
  58
  59     template <typename Iterator>
  60     struct prior<fusion_iterator<Iterator> >
  61     {
  62         typedef fusion_iterator<typename fusion::result_of::prior<Iterator>::type> type;
  63     };
  64
  65     template <typename Iterator, typename N>
  66     struct advance<fusion_iterator<Iterator>, N>
  67     {
  68         typedef fusion_iterator<typename fusion::result_of::advance<Iterator, N>::type> type;
  69     };
  70
  71     template <typename First, typename Last>
  72     struct distance<fusion_iterator<First>, fusion_iterator<Last> >
  73         : fusion::result_of::distance<First, Last>
  74     {};
  75
  76 }}
  77
  78 #endif
  79
  80