cleaner way to remark open upvalues

lfunc.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lfunc.c,v 2.4 2004/04/30 20:13:38 roberto Exp roberto $
+** $Id: lfunc.c,v 2.5 2004/11/24 19:20:21 roberto Exp $
 ** Auxiliary functions to manipulate prototypes and closures
 ** See Copyright Notice in lua.h
 */
@@ -43,42 +43,66 @@ Closure *luaF_newLclosure (lua_State *L, int nelems, TValue *e) {
 UpVal *luaF_newupval (lua_State *L) {
   UpVal *uv = luaM_new(L, UpVal);
   luaC_link(L, obj2gco(uv), LUA_TUPVAL);
-  uv->v = &uv->value;
+  uv->v = &uv->u.value;
   setnilvalue(uv->v);
   return uv;
 }
 
 
 UpVal *luaF_findupval (lua_State *L, StkId level) {
+  global_State *g = G(L);
   GCObject **pp = &L->openupval;
   UpVal *p;
   UpVal *uv;
   while ((p = ngcotouv(*pp)) != NULL && p->v >= level) {
+    lua_assert(p->v != &p->u.value);
     if (p->v == level) return p;
     pp = &p->next;
   }
   uv = luaM_new(L, UpVal);  /* not found: create a new one */
   uv->tt = LUA_TUPVAL;
-  uv->marked = luaC_white(G(L));
+  uv->marked = luaC_white(g);
   uv->v = level;  /* current value lives in the stack */
   uv->next = *pp;  /* chain it in the proper position */
   *pp = obj2gco(uv);
+  lua_assert(g->uvhead.u.l.next->u.l.prev == &g->uvhead &&
+             g->uvhead.u.l.prev->u.l.next == &g->uvhead);
+  uv->u.l.prev = &g->uvhead;  /* double link it in `uvhead' list */
+  uv->u.l.next = g->uvhead.u.l.next;
+  uv->u.l.next->u.l.prev = uv;
+  g->uvhead.u.l.next = uv;
+  lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
   return uv;
 }
 
 
+static void unlinkupval (UpVal *uv) {
+  lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
+  uv->u.l.next->u.l.prev = uv->u.l.prev;  /* remove from `uvhead' list */
+  uv->u.l.prev->u.l.next = uv->u.l.next;
+}
+
+
+void luaF_freeupval (lua_State *L, UpVal *uv) {
+  if (uv->v != &uv->u.value)  /* is it open? */
+    unlinkupval(uv);  /* remove from open list */
+  luaM_free(L, uv);  /* free upvalue */
+}
+
+
 void luaF_close (lua_State *L, StkId level) {
   UpVal *uv;
   global_State *g = G(L);
   while ((uv = ngcotouv(L->openupval)) != NULL && uv->v >= level) {
     GCObject *o = obj2gco(uv);
-    lua_assert(!isblack(o));
+    lua_assert(!isblack(o) && uv->v != &uv->u.value);
     L->openupval = uv->next;  /* remove from `open' list */
     if (isdead(g, o))
-      luaM_free(L, uv);  /* free upvalue */
+      luaF_freeupval(L, uv);  /* free upvalue */
     else {
-      setobj(L, &uv->value, uv->v);
-      uv->v = &uv->value;  /* now current value lives here */
+      unlinkupval(uv);
+      setobj(L, &uv->u.value, uv->v);
+      uv->v = &uv->u.value;  /* now current value lives here */
       luaC_linkupval(L, uv);  /* link upvalue into `gcroot' list */
     }
   }