Sprout/sprout/cstring/strlen.hpp

107 lines
3.1 KiB
C++
Raw Normal View History

2013-08-08 09:54:33 +00:00
/*=============================================================================
2016-02-25 09:48:28 +00:00
Copyright (c) 2011-2016 Bolero MURAKAMI
2013-08-08 09:54:33 +00:00
https://github.com/bolero-MURAKAMI/Sprout
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
2012-04-01 13:15:09 +00:00
#ifndef SPROUT_CSTRING_STRLEN_HPP
#define SPROUT_CSTRING_STRLEN_HPP
2013-01-12 16:16:48 +00:00
#include <iterator>
#include <type_traits>
2012-04-01 13:15:09 +00:00
#include <sprout/config.hpp>
#include <sprout/workaround/std/cstddef.hpp>
#include <sprout/iterator/operation.hpp>
2013-01-12 16:16:48 +00:00
#include <sprout/iterator/ptr_index_iterator.hpp>
2013-02-07 14:12:57 +00:00
#include <sprout/utility/pair/pair.hpp>
2013-01-12 16:16:48 +00:00
#include <sprout/type_traits/is_char_type.hpp>
2013-01-11 19:08:44 +00:00
#include <sprout/algorithm/find.hpp>
2012-04-01 13:15:09 +00:00
namespace sprout {
2013-01-12 16:16:48 +00:00
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
)
{
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
2013-03-22 05:24:19 +00:00
// 7.21.6.3 strlen <20>֐<EFBFBD>
2013-01-12 16:16:48 +00:00
//
// recursion depth:
// O(log N)
//
2012-10-05 15:58:56 +00:00
inline SPROUT_CONSTEXPR std::size_t
strlen(char const* s) {
2013-01-12 16:16:48 +00:00
return sprout::detail::strlen(s);
2012-04-01 13:15:09 +00:00
}
2012-12-21 16:02:49 +00:00
inline SPROUT_CONSTEXPR std::size_t
strlen(char const* s, std::size_t n) {
return sprout::distance(
2013-02-26 08:03:30 +00:00
sprout::ptr_index(s),
sprout::find(sprout::ptr_index(s), sprout::ptr_index(s, n), '\0')
2012-12-21 16:02:49 +00:00
);
}
2013-01-12 16:16:48 +00:00
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(
2013-02-26 08:03:30 +00:00
sprout::ptr_index(s),
sprout::find(sprout::ptr_index(s), sprout::ptr_index(s, n), type())
2013-01-12 16:16:48 +00:00
);
}
2012-04-01 13:15:09 +00:00
} // namespace sprout
#endif // #ifndef SPROUT_CSTRING_STRLEN_HPP