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Merge pull request #41 from Flast/patch-2

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`result_of::at<Seq, N>::type` is't defined when sizeof of sequence is less than N
This commit is contained in:
Joel de Guzman
2014-11-19 06:33:04 +08:00
parent d10f40c489 c9ae4fc886
commit c65000eac8
1 changed files with 16 additions and 2 deletions
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18
include/boost/fusion/sequence/intrinsic/at.hpp
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@ -9,6 +9,9 @@
#include <boost/fusion/support/config.hpp> #include <boost/fusion/support/config.hpp>
#include <boost/mpl/int.hpp> #include <boost/mpl/int.hpp>
#include <boost/mpl/if.hpp>
#include <boost/mpl/less.hpp>
#include <boost/mpl/empty_base.hpp>
#include <boost/type_traits/is_const.hpp> #include <boost/type_traits/is_const.hpp>
#include <boost/fusion/sequence/intrinsic_fwd.hpp> #include <boost/fusion/sequence/intrinsic_fwd.hpp>
#include <boost/fusion/support/tag_of.hpp> #include <boost/fusion/support/tag_of.hpp>
@ -56,12 +59,23 @@ namespace boost { namespace fusion
struct at_impl<std_tuple_tag>; struct at_impl<std_tuple_tag>;
} }
namespace detail
{
template <typename Sequence, typename N, typename Tag>
struct at_impl
: mpl::if_<
mpl::less<N, typename extension::size_impl<Tag>::template apply<Sequence>::type>
, typename extension::at_impl<Tag>::template apply<Sequence, N>
, mpl::empty_base
>::type
{};
}
namespace result_of namespace result_of
{ {
template <typename Sequence, typename N> template <typename Sequence, typename N>
struct at struct at
: extension::at_impl<typename detail::tag_of<Sequence>::type>:: : detail::at_impl<Sequence, N, typename detail::tag_of<Sequence>::type>
template apply<Sequence, N>
{}; {};
template <typename Sequence, int N> template <typename Sequence, int N>