fusion/iterator/iterator_facade.hpp

0001 /*=============================================================================
0002     Copyright (c) 2001-2011 Joel de Guzman
0003
0004     Distributed under the Boost Software License, Version 1.0. (See accompanying
0005     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006 ==============================================================================*/
0007 #if !defined(FUSION_ITERATOR_FACADE_09252006_1011)
0008 #define FUSION_ITERATOR_FACADE_09252006_1011
0009
0010 #include <boost/fusion/support/config.hpp>
0011 #include <boost/fusion/support/iterator_base.hpp>
0012 #include <boost/fusion/iterator/detail/advance.hpp>
0013 #include <boost/fusion/iterator/detail/distance.hpp>
0014 #include <boost/fusion/support/category_of.hpp>
0015 #include <boost/type_traits/is_same.hpp>
0016 #include <boost/mpl/assert.hpp>
0017 #include <boost/mpl/if.hpp>
0018
0019 namespace boost { namespace fusion
0020 {
0021     struct iterator_facade_tag;
0022
0023     template <typename Derived, typename Category>
0024     struct iterator_facade : iterator_base<Derived>
0025     {
0026         typedef iterator_facade_tag fusion_tag;
0027         typedef Derived derived_type;
0028         typedef Category category;
0029
0030         // default implementation
0031         template <typename I1, typename I2>
0032         struct equal_to // default implementation
0033             : is_same<
0034                 typename I1::derived_type
0035               , typename I2::derived_type
0036             >
0037         {};
0038
0039         // default implementation
0040         template <typename Iterator, typename N>
0041         struct advance :
0042             mpl::if_c<
0043                 (N::value > 0)
0044               , advance_detail::forward<Iterator, N::value>
0045               , advance_detail::backward<Iterator, N::value>
0046             >::type
0047         {
0048             BOOST_MPL_ASSERT_NOT((traits::is_random_access<Iterator>));
0049         };
0050
0051         // default implementation
0052         template <typename First, typename Last>
0053         struct distance :
0054             distance_detail::linear_distance<First, Last>
0055         {};
0056     };
0057 }}
0058
0059 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
0060 namespace std
0061 {
0062     template <typename Derived, typename Category>
0063     struct iterator_traits< ::boost::fusion::iterator_facade<Derived, Category> >
0064     { };
0065 }
0066 #endif
0067
0068 #endif