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/*
** $Id: lref.c,v 1.5 1999/12/23 18:19:57 roberto Exp roberto $
** reference mechanism
** See Copyright Notice in lua.h
*/
#define LUA_REENTRANT
#include "lapi.h"
#include "lmem.h"
#include "lref.h"
#include "lstate.h"
#include "lua.h"
int lua_ref (lua_State *L, int lock) {
int ref;
luaA_checkCparams(L, 1);
if (ttype(L->top-1) == LUA_T_NIL)
ref = LUA_REFNIL;
else {
if (L->refFree != NONEXT) { /* is there a free place? */
ref = L->refFree;
L->refFree = L->refArray[ref].st;
}
else { /* no more free places */
luaM_growvector(L, L->refArray, L->refSize, 1, struct ref, refEM, MAX_INT);
ref = L->refSize++;
}
L->refArray[ref].o = *(L->top-1);
L->refArray[ref].st = lock ? LOCK : HOLD;
}
L->top--;
return ref;
}
void lua_unref (lua_State *L, int ref) {
if (ref >= 0) {
if (ref >= L->refSize || L->refArray[ref].st >= 0)
lua_error(L, "API error - invalid parameter for function `lua_unref'");
L->refArray[ref].st = L->refFree;
L->refFree = ref;
}
}
lua_Object lua_getref (lua_State *L, int ref) {
if (ref == LUA_REFNIL)
return luaA_putluaObject(L, &luaO_nilobject);
else if (0 <= ref && ref < L->refSize &&
(L->refArray[ref].st == LOCK || L->refArray[ref].st == HOLD))
return luaA_putluaObject(L, &L->refArray[ref].o);
else
return LUA_NOOBJECT;
}
void lua_beginblock (lua_State *L) {
luaM_growvector(L, L->Cblocks, L->numCblocks, 1, struct C_Lua_Stack,
"too many nested blocks", L->stacksize);
L->Cblocks[L->numCblocks] = L->Cstack;
L->numCblocks++;
}
void lua_endblock (lua_State *L) {
if (L->numCblocks <= 0)
lua_error(L, "API error - no block to end");
--L->numCblocks;
L->Cstack = L->Cblocks[L->numCblocks];
L->top = L->Cstack.base;
}
static int ismarked (const TObject *o) {
/* valid only for locked objects */
switch (o->ttype) {
case LUA_T_STRING: case LUA_T_USERDATA:
return o->value.ts->marked;
case LUA_T_ARRAY:
return o->value.a->marked;
case LUA_T_LCLOSURE: case LUA_T_CCLOSURE:
return o->value.cl->marked;
case LUA_T_LPROTO:
return o->value.tf->marked;
default: /* number or cproto */
return 1;
}
}
/* for internal debugging only; check if a link of free refs is valid */
#define VALIDLINK(L, st,n) (NONEXT <= (st) && (st) < (n))
void luaR_invalidaterefs (lua_State *L) {
int n = L->refSize;
int i;
for (i=0; i<n; i++) {
struct ref *r = &L->refArray[i];
if (r->st == HOLD && !ismarked(&r->o))
r->st = COLLECTED;
LUA_ASSERT(L, (r->st == LOCK && ismarked(&r->o)) ||
r->st == COLLECTED ||
r->st == NONEXT ||
(r->st < n && VALIDLINK(L, L->refArray[r->st].st, n)),
"inconsistent ref table");
}
LUA_ASSERT(L, VALIDLINK(L, L->refFree, n), "inconsistent ref table");
}
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