text: /*=============================================================================
      Copyright (c) 2001-2011 Joel de Guzman
      Copyright (c) 2006 Dan Marsden
  
      Distributed under the Boost Software License, Version 1.0. (See accompanying 
      file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  ==============================================================================*/
  #if !defined(FUSION_ADVANCE_IMPL_20061024_2021)
  #define FUSION_ADVANCE_IMPL_20061024_2021
  
  #include <boost/fusion/support/config.hpp>
  #include <boost/fusion/view/zip_view/zip_view_iterator_fwd.hpp>
  #include <boost/fusion/iterator/advance.hpp>
  #include <boost/fusion/algorithm/transformation/transform.hpp>
  #include <boost/type_traits/remove_reference.hpp>
  
  namespace boost { namespace fusion {
  
      struct zip_view_iterator_tag;
  
      namespace detail
      {
          template<typename N>
          struct poly_advance
          {
              template<typename Sig>
              struct result;
  
              template<typename N1, typename It>
              struct result<poly_advance<N1>(It)>
              {
                  typedef typename remove_reference<It>::type it;
                  typedef typename result_of::advance<it,N>::type type;
              };
  
              template<typename It>
              BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
              typename result<poly_advance(It)>::type
              operator()(const It& it) const
              {
                  return fusion::advance<N>(it);
              }
          };
      }
  
      namespace extension
      {
          template<typename Tag>
          struct advance_impl;
  
          template<>
          struct advance_impl<zip_view_iterator_tag>
          {
              template<typename It, typename N>
              struct apply
              {
                  typedef zip_view_iterator<
                      typename result_of::transform<typename It::iterators, detail::poly_advance<N> >::type> type;
  
                  BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
                  static type
                  call(It const& it)
                  {
                      return type(
                          fusion::transform(it.iterators_, detail::poly_advance<N>()));
                  }
              };
          };
      }
  }}
  
  #endif
  