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fix recursion depth: cstring algorithm

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This commit is contained in:
bolero-MURAKAMI 2013-01-13 01:16:48 +09:00
parent f26032dce8
commit b51b14efa9
25 changed files with 792 additions and 142 deletions
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82
sprout/cstring/strlen.hpp
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@ -2,20 +2,71 @@
#define SPROUT_CSTRING_STRLEN_HPP
#include <cstddef>
#include <iterator>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/iterator/ptr_index_iterator.hpp>
#include <sprout/iterator/operation.hpp>
#include <sprout/iterator/ptr_index_iterator.hpp>
#include <sprout/utility/pair.hpp>
#include <sprout/type_traits/is_char_type.hpp>
#include <sprout/algorithm/find.hpp>
namespace sprout {
namespace detail {
template<typename InputIterator>
inline SPROUT_CONSTEXPR sprout::pair<InputIterator, std::size_t>
strlen_impl_1(
sprout::pair<InputIterator, std::size_t> const& current,
typename std::iterator_traits<InputIterator>::difference_type n
)
{
typedef sprout::pair<InputIterator, std::size_t> type;
return !*current.first ? current
: n == 1 ? type(sprout::next(current.first), current.second + 1)
: sprout::detail::strlen_impl_1(
sprout::detail::strlen_impl_1(
current,
n / 2
),
n - n / 2
)
;
}
template<typename InputIterator>
inline SPROUT_CONSTEXPR sprout::pair<InputIterator, std::size_t>
strlen_impl(
sprout::pair<InputIterator, std::size_t> const& current,
typename std::iterator_traits<InputIterator>::difference_type n
)
{
typedef sprout::pair<InputIterator, std::size_t> type;
return !*current.first ? current
: sprout::detail::strlen_impl(
sprout::detail::strlen_impl_1(
current,
n
),
n * 2
)
;
}
template<typename InputIterator>
inline SPROUT_CONSTEXPR std::size_t
strlen(InputIterator first) {
typedef sprout::pair<InputIterator, std::size_t> type;
return sprout::detail::strlen_impl(type(first, 0), 1).second;
}
} // namespace detail
// 7.21.6.3 strlen ŠÖ<C5A0>”
//
// recursion depth:
// O(log N)
//
inline SPROUT_CONSTEXPR std::size_t
strlen(char const* s) {
return !*s ? 0
: 1 + sprout::strlen(s + 1)
;
return sprout::detail::strlen(s);
}
inline SPROUT_CONSTEXPR std::size_t
strlen(char const* s, std::size_t n) {
return sprout::distance(
@ -23,6 +74,27 @@ namespace sprout {
sprout::find(sprout::as_iterator(s), sprout::as_iterator(s, n), '\0')
);
}
template<typename Elem>
inline SPROUT_CONSTEXPR typename std::enable_if<
sprout::is_char_type<Elem>::value,
std::size_t
>::type
strlen(Elem* s) {
return sprout::detail::strlen(s);
}
template<typename Elem>
inline SPROUT_CONSTEXPR typename std::enable_if<
sprout::is_char_type<Elem>::value,
std::size_t
>::type
strlen(Elem* s, std::size_t n) {
typedef typename std::decay<Elem>::type type;
return sprout::distance(
sprout::as_iterator(s),
sprout::find(sprout::as_iterator(s), sprout::as_iterator(s, n), type())
);
}
} // namespace sprout
#endif // #ifndef SPROUT_CSTRING_STRLEN_HPP