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Initial move from Spirit CVS

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[SVN r34896]
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Joel de Guzman
2006-08-16 16:50:52 +00:00
commit 75b9d13a88
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103
include/boost/fusion/iterator/detail/advance.hpp Normal file
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/*=============================================================================
Copyright (c) 2001-2006 Joel de Guzman
Use, modification and distribution is subject to 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