boost/fusion/iterator/iterator_facade.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_ITERATOR_FACADE_09252006_1011)
   8 #define FUSION_ITERATOR_FACADE_09252006_1011
   9
  10 #include <boost/fusion/support/iterator_base.hpp>
  11 #include <boost/fusion/iterator/detail/advance.hpp>
  12 #include <boost/fusion/iterator/detail/distance.hpp>
  13 #include <boost/fusion/support/category_of.hpp>
  14 #include <boost/type_traits/is_same.hpp>
  15 #include <boost/mpl/assert.hpp>
  16
  17 namespace boost { namespace fusion
  18 {
  19     struct iterator_facade_tag;
  20
  21     template <typename Derived, typename Category>
  22     struct iterator_facade : iterator_base<Derived>
  23     {
  24         typedef iterator_facade_tag fusion_tag;
  25         typedef Derived derived_type;
  26         typedef Category category;
  27
  28         // default implementation
  29         template <typename I1, typename I2>
  30         struct equal_to // default implementation
  31             : is_same<
  32                 typename I1::derived_type
  33               , typename I2::derived_type
  34             >
  35         {};
  36
  37         // default implementation
  38         template <typename Iterator, typename N>
  39         struct advance :
  40             mpl::if_c<
  41                 (N::value > 0)
  42               , advance_detail::forward<Iterator, N::value>
  43               , advance_detail::backward<Iterator, N::value>
  44             >::type
  45         {
  46             BOOST_MPL_ASSERT_NOT((traits::is_random_access<Iterator>));
  47         };
  48
  49         // default implementation
  50         template <typename First, typename Last>
  51         struct distance :
  52             distance_detail::linear_distance<First, Last>
  53         {
  54         };
  55     };
  56 }}
  57
  58 #endif