feedc0de/boost_fusion
1
0
Fork 0
forked from boostorg/fusion
Code Pull Requests Activity

Make fusion::at<vector<...>,N> O(1).

Browse Source
This commit is contained in:
Kohei Takahashi
2015-10-20 20:12:14 +09:00
parent c537da605b
commit 1ad2e59e07
3 changed files with 30 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
include/boost/fusion/container/vector/detail/config.hpp
View File

@@ -13,7 +13,8 @@
#if (defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) \
|| defined(BOOST_NO_CXX11_RVALUE_REFERENCES) \
|| defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)) \
|| defined(BOOST_NO_CXX11_TEMPLATE_ALIASES) \
|| defined(BOOST_NO_CXX11_DECLTYPE)) \
|| (defined(__WAVE__) && defined(BOOST_FUSION_CREATE_PREPROCESSED_FILES))
# if defined(BOOST_FUSION_HAS_VARIADIC_VECTOR)
# undef BOOST_FUSION_HAS_VARIADIC_VECTOR

24
include/boost/fusion/container/vector/detail/value_at_impl.hpp
View File

@@ -21,8 +21,9 @@
///////////////////////////////////////////////////////////////////////////////
// C++11 interface
///////////////////////////////////////////////////////////////////////////////
#include <cstddef>
#include <boost/fusion/container/vector/vector_fwd.hpp>
#include <boost/type_traits/declval.hpp>
#include <boost/type_traits/remove_cv.hpp>
namespace boost { namespace fusion
{
@@ -42,23 +43,12 @@ namespace boost { namespace fusion
template <>
struct value_at_impl<vector_tag>
{
template <typename V, std::size_t N>
struct apply_impl;
template <typename H, typename ...T>
struct apply_impl<vector<H, T...>, 0>
{
typedef H type;
};
template <typename H, typename ...T, std::size_t N>
struct apply_impl<vector<H, T...>, N>
: apply_impl<vector<T...>, N - 1>
{};
template <typename Sequence, typename N>
struct apply : apply_impl<typename Sequence::type_sequence, N::value>
{};
struct apply
{
typedef typename boost::remove_cv<Sequence>::type seq;
typedef decltype(seq::template value_at_impl<N::value>(boost::declval<seq*>())) type;
};
};
}
}}