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fast to_string() implementation

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This commit is contained in:
Marius Bancila 2021-12-23 00:33:04 +02:00
parent c6ad65304b
commit 8e9d0f87f5
1 changed files with 29 additions and 3 deletions
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32
include/uuid.h
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@ -270,6 +270,18 @@ namespace uuids
size_t m_blockByteIndex;
size_t m_byteCount;
};
template <typename CharT>
constexpr CharT empty_guid[] = "00000000-0000-0000-0000-000000000000";
template <>
constexpr wchar_t empty_guid<wchar_t>[] = L"00000000-0000-0000-0000-000000000000";
template <typename CharT>
constexpr CharT guid_encoder[] = "0123456789abcdef";
template <>
constexpr wchar_t guid_encoder<wchar_t>[] = L"0123456789abcdef";
}
// --------------------------------------------------------------------------------------------------------------------------
@ -511,6 +523,9 @@ namespace uuids
template <class Elem, class Traits>
friend std::basic_ostream<Elem, Traits> & operator<<(std::basic_ostream<Elem, Traits> &s, uuid const & id);
template<class CharT, class Traits, class Allocator>
friend std::basic_string<CharT, Traits, Allocator> to_string(uuid const& id);
};
// --------------------------------------------------------------------------------------------------------------------------
@ -572,9 +587,20 @@ namespace uuids
class Allocator = std::allocator<CharT>>
inline std::basic_string<CharT, Traits, Allocator> to_string(uuid const & id)
{
std::basic_stringstream<CharT, Traits, Allocator> sstr;
sstr << id;
return sstr.str();
std::basic_string<CharT, Traits, Allocator> uustr{detail::empty_guid<CharT>};
for (size_t i = 0, index = 0; i < 36; ++i)
{
if (i == 8 || i == 13 || i == 18 || i == 23)
{
continue;
}
uustr[i] = detail::guid_encoder<CharT>[id.data[index] >> 4 & 0x0f];
uustr[++i] = detail::guid_encoder<CharT>[id.data[index] & 0x0f];
index++;
}
return uustr;
}
inline void swap(uuids::uuid & lhs, uuids::uuid & rhs) noexcept