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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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85
sprout/cstring/strcmp.hpp
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@ -1,20 +1,91 @@
#ifndef SPROUT_CSTRING_STRCMP_HPP
#define SPROUT_CSTRING_STRCMP_HPP
#include <iterator>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/iterator/operation.hpp>
#include <sprout/utility/pair.hpp>
#include <sprout/tuple/tuple.hpp>
#include <sprout/type_traits/is_char_type.hpp>
namespace sprout {
// Copyright (C) 2011 RiSK (sscrisk)
namespace detail {
template<typename InputIterator1, typename InputIterator2>
inline SPROUT_CONSTEXPR int
strcmp_impl_check(sprout::tuples::tuple<InputIterator1, InputIterator2, int> const& found) {
return !*sprout::tuples::get<1>(found) ? (!*sprout::tuples::get<0>(found) ? 0 : 1)
: !*sprout::tuples::get<0>(found) ? -1
: sprout::tuples::get<2>(found)
;
}
template<typename InputIterator1, typename InputIterator2>
inline SPROUT_CONSTEXPR sprout::tuples::tuple<InputIterator1, InputIterator2, int>
strcmp_impl_1(
sprout::tuples::tuple<InputIterator1, InputIterator2, int> const& current,
typename std::iterator_traits<InputIterator1>::difference_type n
)
{
typedef sprout::tuples::tuple<InputIterator1, InputIterator2, int> type;
return sprout::tuples::get<2>(current) || !*sprout::tuples::get<1>(current) || !*sprout::tuples::get<0>(current) ? current
: n == 1 ? (*sprout::tuples::get<0>(current)) < (*sprout::tuples::get<1>(current)) ? type(sprout::tuples::get<0>(current), sprout::tuples::get<1>(current), -1)
: (*sprout::tuples::get<1>(current)) < (*sprout::tuples::get<0>(current)) ? type(sprout::tuples::get<0>(current), sprout::tuples::get<1>(current), 1)
: type(sprout::next(sprout::tuples::get<0>(current)), sprout::next(sprout::tuples::get<1>(current)), 0)
: sprout::detail::strcmp_impl_1(
sprout::detail::strcmp_impl_1(
current,
n / 2
),
n - n / 2
)
;
}
template<typename InputIterator1, typename InputIterator2>
inline SPROUT_CONSTEXPR sprout::tuples::tuple<InputIterator1, InputIterator2, int>
strcmp_impl(
sprout::tuples::tuple<InputIterator1, InputIterator2, int> const& current,
typename std::iterator_traits<InputIterator1>::difference_type n
)
{
typedef sprout::tuples::tuple<InputIterator1, InputIterator2, int> type;
return sprout::tuples::get<2>(current) || !*sprout::tuples::get<1>(current) || !*sprout::tuples::get<0>(current) ? current
: sprout::detail::strcmp_impl(
sprout::detail::strcmp_impl_1(
current,
n
),
n * 2
)
;
}
template<typename InputIterator1, typename InputIterator2>
inline SPROUT_CONSTEXPR int
strcmp(InputIterator1 first1, InputIterator2 first2)
{
typedef sprout::tuples::tuple<InputIterator1, InputIterator2, int> type;
return sprout::detail::strcmp_impl_check(
sprout::detail::strcmp_impl(type(first1, first2, 0), 1)
);
}
} // namespace detail
// 7.21.4.2 strcmp ŠÖ<C5A0>”
//
// recursion depth:
// O(log(N1+N2))
//
inline SPROUT_CONSTEXPR int
strcmp(char const* s1, char const* s2) {
return !*s1 && !*s2 ? 0
: !*s1 ? -1
: !*s2 ? 1
: *s1 == *s2 ? sprout::strcmp(s1 + 1, s2 + 1)
: static_cast<unsigned char>(*s1) - static_cast<unsigned char>(*s2)
;
return sprout::detail::strcmp(s1, s2);
}
template<typename Elem>
inline SPROUT_CONSTEXPR typename std::enable_if<
sprout::is_char_type<Elem>::value,
int
>::type
strcmp(Elem* s1, Elem* s2) {
return sprout::detail::strcmp(s1, s2);
}
} // namespace sprout