mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-18 12:22:12 +00:00
55 lines
1.1 KiB
C++
55 lines
1.1 KiB
C++
#pragma once
|
|
|
|
#include <DB/Core/Types.h>
|
|
#include <x86intrin.h>
|
|
|
|
|
|
namespace DB
|
|
{
|
|
|
|
|
|
namespace UTF8
|
|
{
|
|
|
|
|
|
static const UInt8 CONTINUATION_OCTET_MASK = 0b11000000u;
|
|
static const UInt8 CONTINUATION_OCTET = 0b10000000u;
|
|
|
|
/// return true if `octet` binary repr starts with 10 (octet is a UTF-8 sequence continuation)
|
|
inline bool isContinuationOctet(const UInt8 octet)
|
|
{
|
|
return (octet & CONTINUATION_OCTET_MASK) == CONTINUATION_OCTET;
|
|
}
|
|
|
|
/// moves `s` backward until either first non-continuation octet
|
|
inline void syncBackward(const UInt8 * & s)
|
|
{
|
|
while (isContinuationOctet(*s))
|
|
--s;
|
|
}
|
|
|
|
/// moves `s` forward until either first non-continuation octet or string end is met
|
|
inline void syncForward(const UInt8 * & s, const UInt8 * const end)
|
|
{
|
|
while (s < end && isContinuationOctet(*s))
|
|
++s;
|
|
}
|
|
|
|
/// returns UTF-8 code point sequence length judging by it's first octet
|
|
inline std::size_t seqLength(const UInt8 first_octet)
|
|
{
|
|
if (first_octet < 0x80u)
|
|
return 1;
|
|
|
|
const std::size_t bits = 8;
|
|
const auto first_zero = _bit_scan_reverse(static_cast<UInt8>(~first_octet));
|
|
|
|
return bits - 1 - first_zero;
|
|
}
|
|
|
|
|
|
}
|
|
|
|
|
|
}
|