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Made pop_back not use prior.

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[SVN r73643]
This commit is contained in:
Joel de Guzman
2011-08-10 22:03:09 +00:00
parent 21c17fda63
commit 00b2cfc52e
1 changed files with 116 additions and 11 deletions
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123
include/boost/fusion/algorithm/transformation/pop_back.hpp
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@ -10,22 +10,120 @@
#include <boost/fusion/view/iterator_range/iterator_range.hpp>
#include <boost/fusion/sequence/intrinsic/begin.hpp>
#include <boost/fusion/sequence/intrinsic/end.hpp>
#include <boost/fusion/iterator/prior.hpp>
#include <boost/fusion/iterator/iterator_facade.hpp>
#include <boost/fusion/iterator/next.hpp>
#include <boost/mpl/minus.hpp>
#include <boost/mpl/int.hpp>
namespace boost { namespace fusion
{
template <typename Iterator_>
struct pop_back_iterator
: iterator_facade<
pop_back_iterator<Iterator_>
, typename Iterator_::category>
{
typedef Iterator_ base_type;
base_type base;
pop_back_iterator(base_type const& base)
: base(base) {}
template <typename I1, typename I2>
struct equal_to
: is_same<
typename result_of::next<
typename I1::base_type>::type
, typename I2::base_type
>
{};
template <typename Iterator, typename N>
struct advance
: pop_back_iterator<
typename result_of::advance<
typename Iterator::base_type, N>::type
>
{
};
template <typename First, typename Last>
struct distance
: mpl::minus<
typename result_of::distance<
typename First::base_type
, typename Last::base_type
>::type
, mpl::int_<1>
>::type
{};
template <typename Iterator>
struct value_of
: result_of::value_of<typename Iterator::base_type> {};
template <typename Iterator>
struct deref
{
typedef typename
result_of::deref<typename Iterator::base_type>::type
type;
static type
call(Iterator const& it)
{
return fusion::deref(it.base);
}
};
template <typename Iterator>
struct next
{
typedef pop_back_iterator<
typename result_of::next<
typename Iterator::base_type
>::type>
type;
static type
call(Iterator const& i)
{
return fusion::next(i.base);
}
};
template <typename Iterator>
struct prior
{
typedef pop_back_iterator<
typename result_of::prior<
typename Iterator::base_type
>::type>
type;
static type
call(Iterator const& i)
{
return fusion::prior(i.base);
}
};
};
namespace result_of
{
template <typename Sequence>
struct pop_back
{
typedef pop_back_iterator<
typename begin<Sequence>::type>
begin_type;
typedef pop_back_iterator<
typename end<Sequence>::type>
end_type;
typedef
iterator_range<
typename begin<Sequence>::type
, typename prior<
typename end<Sequence>::type
>::type
>
iterator_range<begin_type, end_type>
type;
};
}
@ -34,8 +132,15 @@ namespace boost { namespace fusion
inline typename result_of::pop_back<Sequence const>::type
pop_back(Sequence const& seq)
{
typedef typename result_of::pop_back<Sequence const>::type result;
return result(fusion::begin(seq), fusion::prior(fusion::end(seq)));
typedef result_of::pop_back<Sequence const> comp;
typedef typename comp::begin_type begin_type;
typedef typename comp::end_type end_type;
typedef typename comp::type result;
return result(
begin_type(fusion::begin(seq))
, end_type(fusion::end(seq))
);
}
}}