| /*============================================================================= |
| Copyright (c) 2001-2006 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/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; |
| |
| static type const& |
| call(type const& i) |
| { |
| return i; |
| } |
| |
| template <typename I> |
| 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; |
| |
| static type const& |
| call(type const& i) |
| { |
| return i; |
| } |
| |
| template <typename I> |
| static type |
| call(I const& i) |
| { |
| return call(fusion::prior(i)); |
| } |
| }; |
| |
| }}} |
| |
| #endif |