ref: fc7d6470a2c308ac8265515703be2b657aac67e0
dir: /utf8.c/
/*
Basic UTF-8 manipulation routines
by Jeff Bezanson
placed in the public domain Fall 2005
This code is designed to provide the utilities you need to manipulate
UTF-8 as an internal string encoding. These functions do not perform the
error checking normally needed when handling UTF-8 data, so if you happen
to be from the Unicode Consortium you will want to flay me alive.
I do this because error checking can be performed at the boundaries (I/O),
with these routines reserved for higher performance on data known to be
valid.
A UTF-8 validation routine is included.
*/
#include "llt.h"
static const uint32_t offsetsFromUTF8[6] = {
0x00000000UL, 0x00003080UL, 0x000E2080UL,
0x03C82080UL, 0xFA082080UL, 0x82082080UL
};
static const char trailingBytesForUTF8[256] = {
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,
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,
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,
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,
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,
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,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 3,3,3,3,3,3,3,3,4,4,4,4,5,5,5,5
};
// straight from musl
int
u8_iswprint(Rune c)
{
if(c < 0xff)
return ((c+1) & 0x7f) >= 0x21;
if(c < 0x2028 || c-0x202a < 0xd800-0x202a || c-0xe000 < 0xfff9-0xe000)
return 1;
return !(c-0xfffc > Runemax-0xfffc || (c&0xfffe) == 0xfffe);
}
/* returns length of next utf-8 sequence */
size_t
u8_seqlen(const char *s)
{
return trailingBytesForUTF8[(unsigned int)(uint8_t)s[0]] + 1;
}
/* byte offset => charnum */
size_t
u8_charnum(const char *s, size_t offset)
{
size_t charnum = 0, i = 0;
while(i < offset){
if((s[i++] & 0x80) != 0 && !isutf(s[++i]) && !isutf(s[++i]))
i++;
charnum++;
}
return charnum;
}
size_t
u8_strwidth(const char *s)
{
size_t i, w;
Rune r;
for(i = w = 0; s[i];){
i += chartorune(&r, s+i);
w += wcwidth(r);
}
return w;
}
/* next character without NUL character terminator */
Rune
u8_nextmemchar(const char *s, size_t *i)
{
Rune ch = 0;
size_t sz = 0;
do{
ch <<= 6;
ch += (uint8_t)s[(*i)++];
sz++;
}while(!isutf(s[*i]));
return ch - offsetsFromUTF8[sz-1];
}
int
octal_digit(char c)
{
return (c >= '0' && c <= '7');
}
int
hex_digit(char c)
{
return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F');
}
char
read_escape_control_char(char c)
{
switch(c){
case 'n': return '\n';
case 't': return '\t';
case 'a': return '\a';
case 'b': return '\b';
case 'e': return 0x1b;
case 'f': return '\f';
case 'r': return '\r';
case 'v': return '\v';
}
return c;
}
static inline int
buf_put2c(char *buf, const char *src)
{
buf[0] = src[0];
buf[1] = src[1];
buf[2] = '\0';
return 2;
}
int
u8_escape_rune(char *buf, size_t sz, Rune ch)
{
assert(sz > 2);
if(ch >= 0x20 && ch < 0x7f){
buf[0] = ch;
buf[1] = '\0';
return 1;
}
if(ch > 0xffff)
return snprintf(buf, sz, "\\U%.8x", ch);
if(ch >= Runeself)
return snprintf(buf, sz, "\\u%04x", ch);
switch(ch){
case '\n': return buf_put2c(buf, "\\n");
case '\t': return buf_put2c(buf, "\\t");
case '\\': return buf_put2c(buf, "\\\\");
case '\a': return buf_put2c(buf, "\\a");
case '\b': return buf_put2c(buf, "\\b");
case 0x1b: return buf_put2c(buf, "\\e");
case '\f': return buf_put2c(buf, "\\f");
case '\r': return buf_put2c(buf, "\\r");
case '\v': return buf_put2c(buf, "\\v");
}
return snprintf(buf, sz, "\\x%02x", ch);
}
size_t
u8_escape(char *buf, size_t sz, const char *src, size_t *pi, size_t end, int escape_quotes, int ascii)
{
size_t i = *pi, i0;
Rune ch;
char *start = buf;
char *blim = start + sz-11;
assert(sz > 11);
while(i < end && buf < blim){
// sz-11: leaves room for longest escape sequence
if(escape_quotes && src[i] == '"'){
buf += buf_put2c(buf, "\\\"");
i++;
}else if(src[i] == '\\'){
buf += buf_put2c(buf, "\\\\");
i++;
}else{
i0 = i;
ch = u8_nextmemchar(src, &i);
if(ascii || !u8_iswprint(ch)){
buf += u8_escape_rune(buf, sz - (buf-start), ch);
}else{
i = i0;
do{
*buf++ = src[i++];
}while(!isutf(src[i]));
}
}
}
*buf++ = '\0';
*pi = i;
return (buf-start);
}
char *
u8_memchr(const char *s, Rune ch, size_t sz, size_t *charn)
{
size_t i = 0, lasti = 0;
Rune c;
int csz;
*charn = 0;
while(i < sz){
c = csz = 0;
do{
c <<= 6;
c += (uint8_t)s[i++];
csz++;
}while(i < sz && !isutf(s[i]));
c -= offsetsFromUTF8[csz-1];
if(c == ch)
return (char*)&s[lasti];
lasti = i;
(*charn)++;
}
return nil;
}
/* based on the valid_utf8 routine from the PCRE library by Philip Hazel
length is in bytes, since without knowing whether the string is valid
it's hard to know how many characters there are! */
int
u8_isvalid(const char *str, int length)
{
const uint8_t *p, *pend = (uint8_t*)str + length;
uint8_t c;
int ab;
for(p = (uint8_t*)str; p < pend; p++){
c = *p;
if(c < 128)
continue;
if((c & 0xc0) != 0xc0)
return 0;
ab = trailingBytesForUTF8[c];
if(length < ab)
return 0;
length -= ab;
p++;
/* Check top bits in the second byte */
if((*p & 0xc0) != 0x80)
return 0;
/* Check for overlong sequences for each different length */
switch(ab){
/* Check for xx00 000x */
case 1:
if((c & 0x3e) == 0)
return 0;
continue; /* We know there aren't any more bytes to check */
/* Check for 1110 0000, xx0x xxxx */
case 2:
if(c == 0xe0 && (*p & 0x20) == 0)
return 0;
break;
/* Check for 1111 0000, xx00 xxxx */
case 3:
if(c == 0xf0 && (*p & 0x30) == 0)
return 0;
break;
/* Check for 1111 1000, xx00 0xxx */
case 4:
if(c == 0xf8 && (*p & 0x38) == 0)
return 0;
break;
/* Check for leading 0xfe or 0xff and then for 1111 1100, xx00 00xx */
case 5:
if(c == 0xfe || c == 0xff || (c == 0xfc && (*p & 0x3c) == 0))
return 0;
break;
}
/* Check for valid bytes after the 2nd, if any; all must start 10 */
while(--ab > 0)
if((*(++p) & 0xc0) != 0x80)
return 0;
}
return 1;
}
int
u8_reverse(char *dest, char *src, size_t len)
{
size_t si, di;
dest[di = len] = '\0';
for(si = 0; si < len;){
switch((uint8_t)src[si]>>4){
case 0xf:
di -= 4;
dest[di+0] = src[si++];
dest[di+1] = src[si++];
dest[di+2] = src[si++];
dest[di+3] = src[si++];
break;
case 0xe:
di -= 3;
dest[di+0] = src[si++];
dest[di+1] = src[si++];
dest[di+2] = src[si++];
break;
case 0xd:
case 0xc:
di -= 2;
dest[di+0] = src[si++];
dest[di+1] = src[si++];
break;
default:
di--;
dest[di+0] = src[si++];
break;
}
}
return 0;
}