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new implementation for 'utf8.len'

This commit is contained in:
Roberto Ierusalimschy 2014-04-02 14:01:22 -03:00
parent 7d514af0bc
commit 3a044de5a1
1 changed files with 18 additions and 13 deletions
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31
lutf8lib.c
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@ -1,5 +1,5 @@
/* /*
** $Id: lutf8lib.c,v 1.4 2014/03/20 19:36:02 roberto Exp roberto $ ** $Id: lutf8lib.c,v 1.5 2014/04/01 14:39:55 roberto Exp roberto $
** Standard library for UTF-8 manipulation ** Standard library for UTF-8 manipulation
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@ -61,25 +61,30 @@ static const char *utf8_decode (const char *o, int *val) {
/* /*
** utf8len(s, [i]) --> number of codepoints in 's' after 'i'; ** utf8len(s [, i [, j]]) --> number of codepoints in 's' between 'i';
** nil if 's' not well formed ** nil + current position if 's' not well formed
*/ */
static int utflen (lua_State *L) { static int utflen (lua_State *L) {
int n = 0; int n = 0;
const char *ends;
size_t len; size_t len;
const char *s = luaL_checklstring(L, 1, &len); const char *s = luaL_checklstring(L, 1, &len);
lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), 1); lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
luaL_argcheck(L, 1 <= posi && posi <= (lua_Integer)len, 1, lua_Integer posj = u_posrelat(luaL_optinteger(L, 3, -1), len);
luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 2,
"initial position out of string"); "initial position out of string");
ends = s + len; luaL_argcheck(L, --posj < (lua_Integer)len, 3,
s += posi - 1; "final position out of string");
while (s < ends && (s = utf8_decode(s, NULL)) != NULL) while (posi <= posj) {
const char *s1 = utf8_decode(s + posi, NULL);
if (s1 == NULL) { /* conversion error? */
lua_pushnil(L); /* return nil ... */
lua_pushinteger(L, posi + 1); /* ... and current position */
return 2;
}
posi = s1 - s;
n++; n++;
if (s == ends) }
lua_pushinteger(L, n); lua_pushinteger(L, n);
else
lua_pushnil(L);
return 1; return 1;
} }