/*============================================================================= | |
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 |