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Very fast UTF-8, using Bjoern Hoehrmann's DFA decoder. Faster branchl… #2

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103 changes: 55 additions & 48 deletions mregexp.c
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
/*
/*
* Copyright (c) 2020 Fabian van Rissenbeck

* Permission is hereby granted, free of charge, to any person obtaining a copy
Expand Down Expand Up @@ -34,65 +34,72 @@
#define __SIZE_MAX__ 4294967296
#endif

static inline unsigned utf8_char_width(uint8_t c)
static inline uint32_t utf8_char_width(uint8_t c)
{
int a1 = !(128 & c) && 1;
int a2 = (128 & c) && (64 & c) && !(32 & c);
int a3 = (128 & c) && (64 & c) && (32 & c) && !(16 & c);
int a4 = (128 & c) && (64 & c) && (32 & c) && (16 & c) && !(8 & c);

return a1 * 1 + a2 * 2 + a3 * 3 + a4 * 4;
// "optimal" branchless implementation...
uint32_t ret = (c < 0x80); // 1
ret |= ((c & 0xE0) == 0xC0) << 1; // 2
ret |= ((c & 0xF0) == 0xE0) * 3; // 3
ret |= ((c & 0xF8) == 0xF0) << 2; // 4
return ret;
}

// utf8 valid is extremly slow
static inline bool utf8_valid(const char *s)
{
const size_t len = strlen(s);

for (size_t i = 0; i < len;) {
const unsigned width = utf8_char_width((uint8_t)s[i]);

if (width == 0) {
return false;
}

if (i + width > len) {
return false;
}
// Copyright (c) 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>
// See http://bjoern.hoehrmann.de/utf-8/decoder/dfa/ for details.

#define UTF8_ACCEPT 0
#define UTF8_REJECT 1

static const uint8_t utf8d[] = {
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 00..1f
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 20..3f
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 40..5f
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 60..7f
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, // 80..9f
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, // a0..bf
8,8,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, // c0..df
0xa,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x4,0x3,0x3, // e0..ef
0xb,0x6,0x6,0x6,0x5,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8, // f0..ff
0x0,0x1,0x2,0x3,0x5,0x8,0x7,0x1,0x1,0x1,0x4,0x6,0x1,0x1,0x1,0x1, // s0..s0
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,1,1,0,1,0,1,1,1,1,1,1, // s1..s2
1,2,1,1,1,1,1,2,1,2,1,1,1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1, // s3..s4
1,2,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,1,1,1,1,3,1,3,1,1,1,1,1,1, // s5..s6
1,3,1,1,1,1,1,3,1,3,1,1,1,1,1,1,1,3,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // s7..s8
};

for (unsigned j = 1; j < width; ++j)
if ((s[i + j] & (128 + 64)) != 128) {
return false;
}
static inline uint32_t utf8_decode(uint32_t *state, uint32_t *codep,
const uint32_t byte)
{
uint32_t type = utf8d[byte];
*codep = (*state != UTF8_ACCEPT) ? (byte & 0x3fu) | (*codep << 6)
: (0xff >> type) & (byte);

i += width;
}
*state = utf8d[256 + (*state << 4) + type];
return *state;
}

return true;
static bool utf8_count_codepoints(size_t *count, const uint8_t *s)
{
uint32_t state = UTF8_ACCEPT, codepoint;
for (*count = 0; *s; ++s)
*count += !utf8_decode(&state, &codepoint, *s);
return state == UTF8_ACCEPT; // NB! valid == true
}

bool mregexp_check_utf8(const char *s)
// End - Copyright (c) 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>

bool mregexp_valid_utf8(const char *s)
{
return utf8_valid(s);
size_t count;
bool valid = utf8_count_codepoints(&count, (const uint8_t *)s);
return valid;
}

static const int utf8_peek_mods[] = {0, 127, 31, 15, 7};
static inline uint32_t utf8_peek(const char *s)
{
if (*s == 0)
return 0;

const unsigned width = utf8_char_width(s[0]);
size_t ret = 0;

ret = s[0] & utf8_peek_mods[width];

for (unsigned i = 1; i < width; ++i) {
ret <<= 6;
ret += s[i] & 63;
}

return ret;
uint32_t state = UTF8_ACCEPT, codepoint;
utf8_decode(&state, &codepoint, (uint8_t)s[0]);
return codepoint;
}

static inline const char *utf8_next(const char *s)
Expand Down Expand Up @@ -853,7 +860,7 @@ MRegexp *mregexp_compile(const char *re)
return NULL;
}

if (!utf8_valid(re)) {
if (!mregexp_valid_utf8(re)) {
CompileException.err = MREGEXP_INVALID_UTF8;
CompileException.s = NULL;
return NULL;
Expand Down