mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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99 lines
2.7 KiB
C++
99 lines
2.7 KiB
C++
#ifndef SPROUT_CSTRING_STRLEN_HPP
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#define SPROUT_CSTRING_STRLEN_HPP
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#include <cstddef>
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#include <iterator>
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/iterator/operation.hpp>
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#include <sprout/iterator/ptr_index_iterator.hpp>
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#include <sprout/utility/pair/pair.hpp>
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#include <sprout/type_traits/is_char_type.hpp>
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#include <sprout/algorithm/find.hpp>
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namespace sprout {
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namespace detail {
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template<typename InputIterator>
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inline SPROUT_CONSTEXPR sprout::pair<InputIterator, std::size_t>
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strlen_impl_1(
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sprout::pair<InputIterator, std::size_t> const& current,
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typename std::iterator_traits<InputIterator>::difference_type n
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)
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{
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typedef sprout::pair<InputIterator, std::size_t> type;
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return !*current.first ? current
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: n == 1 ? type(sprout::next(current.first), current.second + 1)
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: sprout::detail::strlen_impl_1(
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sprout::detail::strlen_impl_1(
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current,
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n / 2
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),
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n - n / 2
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)
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;
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}
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template<typename InputIterator>
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inline SPROUT_CONSTEXPR sprout::pair<InputIterator, std::size_t>
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strlen_impl(
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sprout::pair<InputIterator, std::size_t> const& current,
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typename std::iterator_traits<InputIterator>::difference_type n
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)
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{
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return !*current.first ? current
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: sprout::detail::strlen_impl(
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sprout::detail::strlen_impl_1(
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current,
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n
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),
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n * 2
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)
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;
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}
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template<typename InputIterator>
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inline SPROUT_CONSTEXPR std::size_t
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strlen(InputIterator first) {
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typedef sprout::pair<InputIterator, std::size_t> type;
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return sprout::detail::strlen_impl(type(first, 0), 1).second;
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}
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} // namespace detail
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// 7.21.6.3 strlen ŠÖ<C5A0>”
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//
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// recursion depth:
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// O(log N)
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//
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inline SPROUT_CONSTEXPR std::size_t
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strlen(char const* s) {
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return sprout::detail::strlen(s);
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}
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inline SPROUT_CONSTEXPR std::size_t
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strlen(char const* s, std::size_t n) {
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return sprout::distance(
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sprout::ptr_index(s),
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sprout::find(sprout::ptr_index(s), sprout::ptr_index(s, n), '\0')
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);
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}
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template<typename Elem>
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inline SPROUT_CONSTEXPR typename std::enable_if<
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sprout::is_char_type<Elem>::value,
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std::size_t
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>::type
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strlen(Elem* s) {
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return sprout::detail::strlen(s);
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}
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template<typename Elem>
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inline SPROUT_CONSTEXPR typename std::enable_if<
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sprout::is_char_type<Elem>::value,
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std::size_t
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>::type
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strlen(Elem* s, std::size_t n) {
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typedef typename std::decay<Elem>::type type;
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return sprout::distance(
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sprout::ptr_index(s),
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sprout::find(sprout::ptr_index(s), sprout::ptr_index(s, n), type())
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);
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_CSTRING_STRLEN_HPP
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