ClickHouse/dbms/src/Common/UTF8Helpers.h
2019-01-04 15:10:00 +03:00

84 lines
2.2 KiB
C++

#pragma once
#include <Core/Types.h>
#include <Common/BitHelpers.h>
#ifdef __SSE2__
#include <emmintrin.h>
#endif
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 or begin
inline void syncBackward(const UInt8 * & s, const UInt8 * const begin)
{
while (isContinuationOctet(*s) && s > begin)
--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 size_t seqLength(const UInt8 first_octet)
{
if (first_octet < 0x80u)
return 1;
const size_t bits = 8;
const auto first_zero = bitScanReverse(static_cast<UInt8>(~first_octet));
return bits - 1 - first_zero;
}
inline size_t countCodePoints(const UInt8 * data, size_t size)
{
size_t res = 0;
const auto end = data + size;
#ifdef __SSE2__
constexpr auto bytes_sse = sizeof(__m128i);
const auto src_end_sse = data + size / bytes_sse * bytes_sse;
const auto threshold = _mm_set1_epi8(0xBF);
for (; data < src_end_sse; data += bytes_sse)
res += __builtin_popcount(_mm_movemask_epi8(
_mm_cmpgt_epi8(_mm_loadu_si128(reinterpret_cast<const __m128i *>(data)), threshold)));
#endif
for (; data < end; ++data) /// Skip UTF-8 continuation bytes.
res += static_cast<Int8>(*data) > static_cast<Int8>(0xBF);
return res;
}
/// returns UTF-8 wcswidth. Invalid sequence is treated as zero width character.
/// `prefix` is used to compute the `\t` width which extends the string before
/// and include `\t` to the nearest longer length with multiple of eight.
size_t computeWidth(const UInt8 * data, size_t size, size_t prefix = 0) noexcept;
}
}