boost/fusion/iterator/deref.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_DEREF_05042005_1019)
   8 #define FUSION_DEREF_05042005_1019
   9
  10 #include <boost/fusion/support/iterator_base.hpp>
  11 #include <boost/fusion/support/tag_of.hpp>
  12
  13 namespace boost { namespace fusion
  14 {
  15     // Special tags:
  16     struct iterator_facade_tag; // iterator facade tag
  17     struct array_iterator_tag; // boost::array iterator tag
  18     struct mpl_iterator_tag; // mpl sequence iterator tag
  19     struct std_pair_iterator_tag; // std::pair iterator tag
  20
  21     namespace extension
  22     {
  23         template <typename Tag>
  24         struct deref_impl
  25         {
  26             template <typename Iterator>
  27             struct apply {};
  28         };
  29
  30         template <>
  31         struct deref_impl<iterator_facade_tag>
  32         {
  33             template <typename Iterator>
  34             struct apply : Iterator::template deref<Iterator> {};
  35        };
  36
  37         template <>
  38         struct deref_impl<array_iterator_tag>;
  39
  40         template <>
  41         struct deref_impl<mpl_iterator_tag>;
  42
  43         template <>
  44         struct deref_impl<std_pair_iterator_tag>;
  45     }
  46
  47     namespace result_of
  48     {
  49         template <typename Iterator>
  50         struct deref
  51             : extension::deref_impl<typename detail::tag_of<Iterator>::type>::
  52                 template apply<Iterator>
  53         {};
  54     }
  55
  56     template <typename Iterator>
  57     typename result_of::deref<Iterator>::type
  58     deref(Iterator const& i)
  59     {
  60         typedef result_of::deref<Iterator> deref_meta;
  61         return deref_meta::call(i);
  62     }
  63
  64     template <typename Iterator>
  65     typename result_of::deref<Iterator>::type
  66     operator*(iterator_base<Iterator> const& i)
  67     {
  68         return fusion::deref(i.cast());
  69     }
  70 }}
  71
  72 #endif