/*============================================================================= Copyright (c) 2001-2011 Joel de Guzman 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_09172005_1149) #define FUSION_ADVANCE_09172005_1149 #include <boost/fusion/support/config.hpp> #include <boost/mpl/int.hpp> #include <boost/mpl/if.hpp> #include <boost/mpl/eval_if.hpp> #include <boost/mpl/identity.hpp> #include <boost/fusion/iterator/next.hpp> #include <boost/fusion/iterator/prior.hpp> namespace boost { namespace fusion { namespace advance_detail { // Default advance implementation, perform next(i) // or prior(i) N times. template <typename Iterator, int N> struct forward; template <typename Iterator, int N> struct next_forward { typedef typename forward< typename result_of::next<Iterator>::type , N-1 >::type type; }; template <typename Iterator, int N> struct forward { typedef typename mpl::eval_if_c< (N == 0) , mpl::identity<Iterator> , next_forward<Iterator, N> >::type type; BOOST_FUSION_GPU_ENABLED static type const& call(type const& i) { return i; } template <typename I> BOOST_FUSION_GPU_ENABLED static type call(I const& i) { return call(fusion::next(i)); } }; template <typename Iterator, int N> struct backward; template <typename Iterator, int N> struct next_backward { typedef typename backward< typename result_of::prior<Iterator>::type , N+1 >::type type; }; template <typename Iterator, int N> struct backward { typedef typename mpl::eval_if_c< (N == 0) , mpl::identity<Iterator> , next_backward<Iterator, N> >::type type; BOOST_FUSION_GPU_ENABLED static type const& call(type const& i) { return i; } template <typename I> BOOST_FUSION_GPU_ENABLED static type call(I const& i) { return call(fusion::prior(i)); } }; }}} #endif