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Merge pull request #56 from kariya-mitsuru/algorithm.search_n

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[algorithm.search_n] Fix search_n's complexity violation.
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Bolero MURAKAMI 2013-10-26 19:50:46 -07:00
commit 39bc2bfc5d
1 changed files with 112 additions and 10 deletions
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122
sprout/algorithm/search_n.hpp
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@ -11,11 +11,115 @@
#include <iterator>
#include <sprout/config.hpp>
#include <sprout/iterator/operation.hpp>
#include <sprout/iterator/value_iterator.hpp>
#include <sprout/functional/equal_to.hpp>
#include <sprout/algorithm/search.hpp>
#include <sprout/tuple.hpp>
#include <sprout/algorithm/find.hpp>
#include <sprout/algorithm/find_if.hpp>
namespace sprout {
namespace detail {
template<typename RandomAccessIterator, typename Size, typename T, typename BinaryPredicate>
inline SPROUT_CONSTEXPR RandomAccessIterator
search_n_impl_ra(
RandomAccessIterator current, RandomAccessIterator last,
Size count, T const& value, BinaryPredicate pred,
typename std::iterator_traits<RandomAccessIterator>::difference_type len,
RandomAccessIterator searched
)
{
return sprout::distance(searched, current) >= count || searched == last ? searched
: len == 1 ? pred(*current, value) ? searched
: sprout::distance(current, last) > count ? sprout::next(current) : last
: sprout::detail::search_n_impl_ra(
current + len / 2, last, count, value, pred, len - len / 2,
sprout::detail::search_n_impl_ra(
current, last, count, value, pred, len / 2, searched
)
)
;
}
template<typename RandomAccessIterator, typename Size, typename T, typename BinaryPredicate>
inline SPROUT_CONSTEXPR typename std::enable_if<
sprout::is_constant_distance_iterator<RandomAccessIterator>::value,
RandomAccessIterator
>::type
search_n(
RandomAccessIterator first, RandomAccessIterator last, Size count, T const& value, BinaryPredicate pred,
std::random_access_iterator_tag*
)
{
return sprout::distance(first, last) < count
? last
: sprout::detail::search_n_impl_ra(
first, last, count, value, pred, sprout::distance(first, last), first
)
;
}
template<typename ForwardIterator, typename Size>
inline SPROUT_CONSTEXPR ForwardIterator
search_n_impl_check(
sprout::tuple<ForwardIterator, ForwardIterator, Size> current,
ForwardIterator last, Size count
)
{
return sprout::tuples::get<2>(current) == count ? sprout::tuples::get<1>(current) : last;
}
template<typename ForwardIterator, typename Size, typename T, typename BinaryPredicate>
inline SPROUT_CONSTEXPR sprout::tuple<ForwardIterator, ForwardIterator, Size>
search_n_impl_1(
sprout::tuple<ForwardIterator, ForwardIterator, Size> current,
ForwardIterator last, Size count, T const& value, BinaryPredicate pred,
typename std::iterator_traits<ForwardIterator>::difference_type n
)
{
typedef sprout::tuple<ForwardIterator, ForwardIterator, Size> type;
return sprout::tuples::get<2>(current) == count || sprout::tuples::get<0>(current) == last ? current
: n == 1
? pred(*sprout::tuples::get<0>(current), value)
? type(sprout::next(sprout::tuples::get<0>(current)), sprout::tuples::get<1>(current), sprout::tuples::get<2>(current) + 1)
: type(sprout::next(sprout::tuples::get<0>(current)), sprout::next(sprout::tuples::get<0>(current)), 0)
: sprout::detail::search_n_impl_1(
sprout::detail::search_n_impl_1(
current,
last, count, value, pred, n / 2
),
last, count, value, pred, n - n / 2
)
;
}
template<typename ForwardIterator, typename Size, typename T, typename BinaryPredicate>
inline SPROUT_CONSTEXPR sprout::tuple<ForwardIterator, ForwardIterator, Size>
search_n_impl(
sprout::tuple<ForwardIterator, ForwardIterator, Size> current,
ForwardIterator last, Size count, T const& value, BinaryPredicate pred,
typename std::iterator_traits<ForwardIterator>::difference_type n
)
{
return sprout::tuples::get<2>(current) == count || sprout::tuples::get<0>(current) == last ? current
: sprout::detail::search_n_impl(
sprout::detail::search_n_impl_1(
current,
last, count, value, pred, n
),
last, count, value, pred, n * 2
)
;
}
template<typename ForwardIterator, typename Size, typename T, typename BinaryPredicate>
inline SPROUT_CONSTEXPR ForwardIterator
search_n(
ForwardIterator first, ForwardIterator last, Size count, T const& value, BinaryPredicate pred,
std::forward_iterator_tag*
)
{
typedef sprout::tuple<ForwardIterator, ForwardIterator, Size> type;
return sprout::detail::search_n_impl_check(
sprout::detail::search_n_impl(type(first, first, 0), last, count, value, pred, 1),
last, count
)
;
}
}
// 25.2.13 Search
//
// recursion depth:
@ -24,19 +128,17 @@ namespace sprout {
template<typename ForwardIterator, typename Size, typename T, typename BinaryPredicate>
inline SPROUT_CONSTEXPR ForwardIterator
search_n(ForwardIterator first, ForwardIterator last, Size count, T const& value, BinaryPredicate pred) {
typedef sprout::value_iterator<T const&> iterator;
typedef typename std::iterator_traits<iterator>::difference_type difference_type;
return sprout::search(
first, last,
iterator(value, static_cast<difference_type>(count)), iterator(value, 0),
pred
);
typedef typename std::iterator_traits<ForwardIterator>::iterator_category* category;
return count == 0 ? last : count == 1 ? sprout::find_if(first, last, sprout::bind2nd(pred, value))
: sprout::detail::search_n(first, last, count, value, pred, category());
}
template<typename ForwardIterator, typename Size, typename T>
inline SPROUT_CONSTEXPR ForwardIterator
search_n(ForwardIterator first, ForwardIterator last, Size count, T const& value) {
return sprout::search_n(first, last, count, value, sprout::equal_to<>());
typedef typename std::iterator_traits<ForwardIterator>::iterator_category* category;
return count == 0 ? last : count == 1 ? sprout::find(first, last, value)
: sprout::detail::search_n(first, last, count, value, sprout::equal_to<>(), category());
}
} // namespace sprout