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Clear interface between references and predefines

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The reference system has a defined way to add initial values to the
table where it operates.
This commit is contained in:
Roberto Ierusalimschy
2024-01-15 11:31:49 -03:00
parent 8eb0abc9db
commit 17e0c29d9b
7 changed files with 92 additions and 43 deletions
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28
lauxlib.c
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@@ -672,13 +672,10 @@ LUALIB_API char *luaL_buffinitsize (lua_State *L, luaL_Buffer *B, size_t sz) {
** =======================================================
*/
/* index of free-list header (after the predefined values) */
#define freelist (LUA_RIDX_LAST + 1)
/*
** The previously freed references form a linked list:
** t[freelist] is the index of a first free index, or zero if list is
** empty; t[t[freelist]] is the index of the second element; etc.
** The previously freed references form a linked list: t[1] is the index
** of a first free index, t[t[1]] is the index of the second element,
** etc. A zero signals the end of the list.
*/
LUALIB_API int luaL_ref (lua_State *L, int t) {
int ref;
@@ -687,19 +684,18 @@ LUALIB_API int luaL_ref (lua_State *L, int t) {
return LUA_REFNIL; /* 'nil' has a unique fixed reference */
}
t = lua_absindex(L, t);
if (lua_rawgeti(L, t, freelist) == LUA_TNIL) { /* first access? */
if (lua_rawgeti(L, t, 1) == LUA_TNUMBER) /* already initialized? */
ref = (int)lua_tointeger(L, -1); /* ref = t[1] */
else { /* first access */
lua_assert(!lua_toboolean(L, -1)); /* must be nil or false */
ref = 0; /* list is empty */
lua_pushinteger(L, 0); /* initialize as an empty list */
lua_rawseti(L, t, freelist); /* ref = t[freelist] = 0 */
}
else { /* already initialized */
lua_assert(lua_isinteger(L, -1));
ref = (int)lua_tointeger(L, -1); /* ref = t[freelist] */
lua_rawseti(L, t, 1); /* ref = t[1] = 0 */
}
lua_pop(L, 1); /* remove element from stack */
if (ref != 0) { /* any free element? */
lua_rawgeti(L, t, ref); /* remove it from list */
lua_rawseti(L, t, freelist); /* (t[freelist] = t[ref]) */
lua_rawseti(L, t, 1); /* (t[1] = t[ref]) */
}
else /* no free elements */
ref = (int)lua_rawlen(L, t) + 1; /* get a new reference */
@@ -711,11 +707,11 @@ LUALIB_API int luaL_ref (lua_State *L, int t) {
LUALIB_API void luaL_unref (lua_State *L, int t, int ref) {
if (ref >= 0) {
t = lua_absindex(L, t);
lua_rawgeti(L, t, freelist);
lua_rawgeti(L, t, 1);
lua_assert(lua_isinteger(L, -1));
lua_rawseti(L, t, ref); /* t[ref] = t[freelist] */
lua_rawseti(L, t, ref); /* t[ref] = t[1] */
lua_pushinteger(L, ref);
lua_rawseti(L, t, freelist); /* t[freelist] = ref */
lua_rawseti(L, t, 1); /* t[1] = ref */
}
}