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Short strings can be external, too

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That complicates a little object equality (and therefore table access
for long strings), but the old behavior was somewhat weird. (Short
strings, a concept otherwise absent from the manual, could not be
external.)
This commit is contained in:
Roberto Ierusalimschy
2025-07-15 14:40:27 -03:00
parent c612685d4b
commit 60b6599e83
9 changed files with 168 additions and 120 deletions
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46
lstring.c
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@@ -39,14 +39,14 @@
/*
** equality for long strings
** generic equality for strings
*/
int luaS_eqlngstr (TString *a, TString *b) {
size_t len = a->u.lnglen;
lua_assert(a->tt == LUA_VLNGSTR && b->tt == LUA_VLNGSTR);
return (a == b) || /* same instance or... */
((len == b->u.lnglen) && /* equal length and ... */
(memcmp(getlngstr(a), getlngstr(b), len) == 0)); /* equal contents */
int luaS_eqstr (TString *a, TString *b) {
size_t len1, len2;
const char *s1 = getlstr(a, len1);
const char *s2 = getlstr(b, len2);
return ((len1 == len2) && /* equal length and ... */
(memcmp(s1, s2, len1) == 0)); /* equal contents */
}
@@ -315,28 +315,9 @@ static void f_newext (lua_State *L, void *ud) {
}
static void f_pintern (lua_State *L, void *ud) {
struct NewExt *ne = cast(struct NewExt *, ud);
ne->ts = internshrstr(L, ne->s, ne->len);
}
TString *luaS_newextlstr (lua_State *L,
const char *s, size_t len, lua_Alloc falloc, void *ud) {
struct NewExt ne;
if (len <= LUAI_MAXSHORTLEN) { /* short string? */
ne.s = s; ne.len = len;
if (!falloc)
f_pintern(L, &ne); /* just internalize string */
else {
TStatus status = luaD_rawrunprotected(L, f_pintern, &ne);
(*falloc)(ud, cast_voidp(s), len + 1, 0); /* free external string */
if (status != LUA_OK) /* memory error? */
luaM_error(L); /* re-raise memory error */
}
return ne.ts;
}
/* "normal" case: long strings */
if (!falloc) {
ne.kind = LSTRFIX;
f_newext(L, &ne); /* just create header */
@@ -357,3 +338,16 @@ TString *luaS_newextlstr (lua_State *L,
}
/*
** Normalize an external string: If it is short, internalize it.
*/
TString *luaS_normstr (lua_State *L, TString *ts) {
size_t len = ts->u.lnglen;
if (len > LUAI_MAXSHORTLEN)
return ts; /* long string; keep the original */
else {
const char *str = getlngstr(ts);
return internshrstr(L, str, len);
}
}