static int str_byte (lua_State *L) {
size_t l;
const char *s = luaL_checklstring(L, 1, &l);
ptrdiff_t posi = posrelat(luaL_optint32(L, 2, 1), l);
ptrdiff_t pose = posrelat(luaL_optint32(L, 3, posi), l);
int n, i;
if (posi <= 0) posi = 1;
if ((size_t)pose > l) pose = l;
if (posi > pose) return 0; /* empty interval; return no values */
n = (int)(pose - posi + 1);
if (posi + n <= pose) /* overflow? */
luaL_error(L, "string slice too long");
luaL_checkstack(L, n, "string slice too long");
for (i=0; i<n; i++)
lua_pushinteger(L, uchar(s[posi+i-1]));
return n;
}
static int f_setvbuf (lua_State *L) {
static const int mode[] = {_IONBF, _IOFBF, _IOLBF};
static const char *const modenames[] = {"no", "full", "line", NULL};
FILE *f = tofile(L);
int op = luaL_checkoption(L, 2, NULL, modenames);
size_t sz = luaL_optint32(L, 3, LUAL_BUFFERSIZE);
int res = setvbuf(f, NULL, mode[op], sz);
return pushresult(L, res == 0, NULL);
}
static int str_sub (lua_State *L) {
size_t l;
const char *s = luaL_checklstring(L, 1, &l);
ptrdiff_t start = posrelat(luaL_checkint32(L, 2), l);
ptrdiff_t end = posrelat(luaL_optint32(L, 3, -1), l);
if (start < 1) start = 1;
if (end > (ptrdiff_t)l) end = (ptrdiff_t)l;
if (start <= end)
lua_pushlstring(L, s+start-1, end-start+1);
else lua_pushliteral(L, "");
return 1;
}
static int str_find_aux (lua_State *L, int find) {
size_t l1, l2;
const char *s = luaL_checklstring(L, 1, &l1);
const char *p = luaL_checklstring(L, 2, &l2);
ptrdiff_t init = posrelat(luaL_optint32(L, 3, 1), l1) - 1;
if (init < 0) init = 0;
else if ((size_t)(init) > l1) init = (ptrdiff_t)l1;
if (find && (lua_toboolean(L, 4) || /* explicit request? */
strpbrk(p, SPECIALS) == NULL)) { /* or no special characters? */
/* do a plain search */
const char *s2 = lmemfind(s+init, l1-init, p, l2);
if (s2) {
lua_pushinteger(L, s2-s+1);
lua_pushinteger(L, s2-s+l2);
return 2;
}
}
else {
MatchState ms;
int anchor = (*p == '^') ? (p++, 1) : 0;
const char *s1=s+init;
ms.L = L;
ms.src_init = s;
ms.src_end = s+l1;
do {
const char *res;
ms.level = 0;
if ((res=match(&ms, s1, p)) != NULL) {
if (find) {
lua_pushinteger(L, s1-s+1); /* start */
lua_pushinteger(L, res-s); /* end */
return push_captures(&ms, NULL, 0) + 2;
}
else
return push_captures(&ms, s1, res);
}
} while (s1++ < ms.src_end && !anchor);
}
lua_pushnil(L); /* not found */
return 1;
}