Chris@16: /*=============================================================================
Chris@16:     Copyright (c) 2001-2011 Joel de Guzman
Chris@16: 
Chris@16:     Distributed under the Boost Software License, Version 1.0. (See accompanying 
Chris@16:     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: ==============================================================================*/
Chris@16: #if !defined(FUSION_ADVANCE_09172005_1149)
Chris@16: #define FUSION_ADVANCE_09172005_1149
Chris@16: 
Chris@101: #include <boost/fusion/support/config.hpp>
Chris@16: #include <boost/mpl/int.hpp>
Chris@16: #include <boost/mpl/if.hpp>
Chris@16: #include <boost/mpl/eval_if.hpp>
Chris@16: #include <boost/mpl/identity.hpp>
Chris@16: #include <boost/fusion/iterator/next.hpp>
Chris@16: #include <boost/fusion/iterator/prior.hpp>
Chris@16: 
Chris@16: namespace boost { namespace fusion { namespace advance_detail
Chris@16: {
Chris@16:     // Default advance implementation, perform next(i)
Chris@16:     // or prior(i) N times.
Chris@16: 
Chris@16:     template <typename Iterator, int N>
Chris@16:     struct forward;
Chris@16: 
Chris@16:     template <typename Iterator, int N>
Chris@16:     struct next_forward
Chris@16:     {
Chris@16:         typedef typename
Chris@16:             forward<
Chris@16:                 typename result_of::next<Iterator>::type
Chris@16:               , N-1
Chris@16:             >::type
Chris@16:         type;
Chris@16:     };
Chris@16: 
Chris@16:     template <typename Iterator, int N>
Chris@16:     struct forward
Chris@16:     {
Chris@16:         typedef typename
Chris@16:             mpl::eval_if_c<
Chris@16:                 (N == 0)
Chris@16:               , mpl::identity<Iterator>
Chris@16:               , next_forward<Iterator, N>
Chris@16:             >::type
Chris@16:         type;
Chris@16: 
Chris@101:         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
Chris@16:         static type const&
Chris@16:         call(type const& i)
Chris@16:         {
Chris@16:             return i;
Chris@16:         }
Chris@16: 
Chris@16:         template <typename I>
Chris@101:         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
Chris@16:         static type
Chris@16:         call(I const& i)
Chris@16:         {
Chris@16:             return call(fusion::next(i));
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     template <typename Iterator, int N>
Chris@16:     struct backward;
Chris@16: 
Chris@16:     template <typename Iterator, int N>
Chris@16:     struct next_backward
Chris@16:     {
Chris@16:         typedef typename
Chris@16:             backward<
Chris@16:                 typename result_of::prior<Iterator>::type
Chris@16:               , N+1
Chris@16:             >::type
Chris@16:         type;
Chris@16:     };
Chris@16: 
Chris@16:     template <typename Iterator, int N>
Chris@16:     struct backward
Chris@16:     {
Chris@16:         typedef typename
Chris@16:             mpl::eval_if_c<
Chris@16:                 (N == 0)
Chris@16:               , mpl::identity<Iterator>
Chris@16:               , next_backward<Iterator, N>
Chris@16:             >::type
Chris@16:         type;
Chris@16: 
Chris@101:         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
Chris@16:         static type const&
Chris@16:         call(type const& i)
Chris@16:         {
Chris@16:             return i;
Chris@16:         }
Chris@16: 
Chris@16:         template <typename I>
Chris@101:         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
Chris@16:         static type
Chris@16:         call(I const& i)
Chris@16:         {
Chris@16:             return call(fusion::prior(i));
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16: }}}
Chris@16: 
Chris@16: #endif