implementation of lua_ref (previously in module `lmem').

1 files changed, 78 insertions, 0 deletions

diff --git a/lref.c b/lref.c
new file mode 100644
index 00000000..2479141c
--- /dev/null
+++ b/lref.c
@@ -0,0 +1,78 @@
+/*
+** $Id: $
+** REF mechanism
+** See Copyright Notice in lua.h
+*/
+
+
+#include "lmem.h"
+#include "lref.h"
+#include "lstate.h"
+#include "lua.h"
+
+
+int luaR_ref (const TObject *o, int lock) {
+  int ref;
+  if (ttype(o) == LUA_T_NIL)
+    ref = LUA_REFNIL;
+  else {
+    for (ref=0; ref<L->refSize; ref++)
+      if (L->refArray[ref].status == FREE)
+        break;
+    if (ref == L->refSize) {  /* no more empty spaces? */
+      luaM_growvector(L->refArray, L->refSize, 1, struct ref, refEM, MAX_INT);
+      L->refSize++;
+    }
+    L->refArray[ref].o = *o;
+    L->refArray[ref].status = lock ? LOCK : HOLD;
+  }
+  return ref;
+}
+
+
+void lua_unref (int ref) {
+  if (ref >= 0 && ref < L->refSize)
+    L->refArray[ref].status = FREE;
+}
+
+
+const TObject *luaR_getref (int ref) {
+  if (ref == LUA_REFNIL)
+    return &luaO_nilobject;
+  if (ref >= 0 && ref < L->refSize &&
+      (L->refArray[ref].status == LOCK || L->refArray[ref].status == HOLD))
+    return &L->refArray[ref].o;
+  else
+    return NULL;
+}
+
+
+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_CLOSURE:
+      return o->value.cl->marked;
+    case LUA_T_PROTO:
+      return o->value.tf->marked;
+#ifdef DEBUG
+    case LUA_T_LINE: case LUA_T_CLMARK:
+    case LUA_T_CMARK: case LUA_T_PMARK:
+      LUA_INTERNALERROR("invalid type");
+#endif
+    default:  /* nil, number or cproto */
+      return 1;
+  }
+}
+
+
+void luaR_invalidaterefs (void) {
+  int i;
+  for (i=0; i<L->refSize; i++)
+    if (L->refArray[i].status == HOLD && !ismarked(&L->refArray[i].o))
+      L->refArray[i].status = COLLECTED;
+}
+