first implementation for weak tables

lapi.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lapi.c,v 1.136 2001/03/07 18:09:25 roberto Exp roberto $
+** $Id: lapi.c,v 1.137 2001/03/26 14:31:49 roberto Exp roberto $
 ** Lua API
 ** See Copyright Notice in lua.h
 */
@@ -681,18 +681,19 @@ LUA_API int lua_next (lua_State *L, int index) {
 
 
 LUA_API int lua_getn (lua_State *L, int index) {
-  Hash *h;
+  StkId t;
   const TObject *value;
   int n;
   lua_lock(L);
-  h = hvalue(luaA_index(L, index));
-  value = luaH_getstr(h, luaS_newliteral(L, l_s("n")));  /* = h.n */
+  t = luaA_index(L, index);
+  api_check(L, ttype(t) == LUA_TTABLE);
+  value = luaH_getstr(hvalue(t), luaS_newliteral(L, l_s("n")));  /* = t.n */
   if (ttype(value) == LUA_TNUMBER)
     n = (int)nvalue(value);
   else {
     lua_Number max = 0;
-    int i = h->size;
-    Node *nd = h->node;
+    int i = hvalue(t)->size;
+    Node *nd = hvalue(t)->node;
     while (i--) {
       if (ttype_key(nd) == LUA_TNUMBER &&
           ttype(val(nd)) != LUA_TNIL &&
@@ -737,3 +738,23 @@ LUA_API void *lua_newuserdata (lua_State *L, size_t size) {
   return p;
 }
 
+
+LUA_API int lua_getweakmode (lua_State *L, int index) {
+  StkId t;
+  int mode;
+  lua_lock(L);
+  t = luaA_index(L, index);
+  api_check(L, ttype(t) == LUA_TTABLE);
+  mode = hvalue(t)->weakmode;
+  lua_unlock(L);
+  return mode;
+}
+
+
+LUA_API void  lua_setweakmode (lua_State *L, int mode) {
+  lua_lock(L);
+  api_check(L, ttype(L->top-1) == LUA_TTABLE);
+  hvalue(L->top-1)->weakmode = mode;
+  lua_unlock(L);
+}
+

lbaselib.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lbaselib.c,v 1.31 2001/03/26 14:31:49 roberto Exp roberto $
+** $Id: lbaselib.c,v 1.32 2001/04/06 18:25:00 roberto Exp roberto $
 ** Basic library
 ** See Copyright Notice in lua.h
 */
@@ -169,6 +169,29 @@ static int luaB_settag (lua_State *L) {
   return 1;  /* return table */
 }
 
+static int luaB_weakmode (lua_State *L) {
+  const char *mode = luaL_opt_string(L, 2, NULL);
+  luaL_checktype(L, 1, LUA_TTABLE);
+  if (mode == NULL) {
+    char buff[3];
+    char *s = buff;
+    int imode = lua_getweakmode(L, 1);
+    if (imode & LUA_WEAK_KEY) *s++ = 'k';
+    if (imode & LUA_WEAK_VALUE) *s++ = 'v';
+    *s = '\0';
+    lua_pushstring(L, buff);
+    return 1;
+  }
+  else {
+    int imode = 0;
+    lua_pushvalue(L, 1);  /* push table */
+    if (strchr(mode, l_c('k'))) imode |= LUA_WEAK_KEY;
+    if (strchr(mode, l_c('v'))) imode |= LUA_WEAK_VALUE;
+    lua_setweakmode(L, imode);
+    return 1;
+  }
+}
+
 static int luaB_newtype (lua_State *L) {
   const l_char *name = luaL_opt_string(L, 1, NULL);
   lua_pushnumber(L, lua_newtype(L, name, LUA_TTABLE));
@@ -753,6 +776,7 @@ static const luaL_reg base_funcs[] = {
   {l_s("tremove"), luaB_tremove},
   {l_s("unwrap"), luaB_unwrap},
   {l_s("xtype"), luaB_xtype},
+  {l_s("weakmode"), luaB_weakmode}
 };
 
 

lgc.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lgc.c,v 1.94 2001/03/07 18:09:25 roberto Exp roberto $
+** $Id: lgc.c,v 1.95 2001/03/26 14:31:49 roberto Exp roberto $
 ** Garbage Collector
 ** See Copyright Notice in lua.h
 */
@@ -38,9 +38,6 @@ typedef struct GCState {
 
 
 
-static void markobject (GCState *st, TObject *o);
-
-
 /* mark a string; marks larger than 1 cannot be changed */
 #define strmark(s)    {if ((s)->marked == 0) (s)->marked = 1;}
 
@@ -144,22 +141,30 @@ static void traverseclosure (GCState *st, Closure *f) {
 }
 
 
+static void removekey (Node *n) {
+  if (ttype_key(n) != LUA_TNIL && ttype_key(n) != LUA_TNUMBER)
+    n->key_value.ts = NULL;  /* dead key; remove it */
+}
+
+
 static void traversetable (GCState *st, Hash *h) {
   int i;
+  int mode = h->weakmode;
+  if (mode == (LUA_WEAK_KEY | LUA_WEAK_VALUE))
+    return;  /* avoid traversing if both keys and values are weak */
   for (i=0; i<h->size; i++) {
     Node *n = node(h, i);
-    if (ttype(val(n)) == LUA_TNIL) {
-      if (ttype_key(n) != LUA_TNIL)
-        n->key_value.ts = NULL;  /* dead key; remove it */
-    }
+    if (ttype(val(n)) == LUA_TNIL)
+      removekey(n);
     else {
       lua_assert(ttype_key(n) != LUA_TNIL);
-      if (ttype_key(n) != LUA_TNUMBER) {
-        TObject o;
-        setkey2obj(&o, n);
-        markobject(st, &o);
+      if (ttype_key(n) != LUA_TNUMBER && !(mode & LUA_WEAK_KEY)) {
+        TObject k;
+        setkey2obj(&k, n);
+        markobject(st, &k);
       }
-      markobject(st, &n->val);
+      if (!(mode & LUA_WEAK_VALUE))
+        markobject(st, &n->val);
     }
   }
 }
@@ -190,7 +195,6 @@ static void markall (lua_State *L) {
 
 
 static int hasmark (const TObject *o) {
-  /* valid only for locked objects */
   switch (ttype(o)) {
     case LUA_TSTRING: case LUA_TUSERDATA:
       return tsvalue(o)->marked;
@@ -198,7 +202,7 @@ static int hasmark (const TObject *o) {
       return ismarked(hvalue(o));
     case LUA_TFUNCTION:
       return ismarked(clvalue(o));
-    default:  /* number */
+    default:  /* number, nil */
       return 1;
   }
 }
@@ -224,6 +228,30 @@ static void invalidaterefs (global_State *G) {
 }
 
 
+static void invalidatetable (Hash *h) {
+  int i;
+  for (i=0; i<h->size; i++) {
+    Node *n = node(h, i);
+    TObject k;
+    if (ttype(val(n)) == LUA_TNIL) continue;  /* empty node */
+    setkey2obj(&k, n);
+    if (!hasmark(val(n)) || !hasmark(&k)) {
+      setnilvalue(val(n));  /* remove value */
+      removekey(n);
+    }
+  }
+}
+
+
+static void invalidatetables (global_State *G) {
+  Hash *h;
+  for (h = G->roottable; h; h = h->next) {
+    if (ismarked(h) && h->weakmode)
+      invalidatetable(h);
+  }
+}
+
+
 
 static void collectproto (lua_State *L) {
   Proto **p = &G(L)->rootproto;
@@ -381,6 +409,7 @@ void luaC_collect (lua_State *L, int all) {
 void luaC_collectgarbage (lua_State *L) {
   markall(L);
   invalidaterefs(G(L));  /* check unlocked references */
+  invalidatetables(G(L));
   luaC_collect(L, 0);
   checkMbuffer(L);
   G(L)->GCthreshold = 2*G(L)->nblocks;  /* set new threshold */

lobject.h

@@ -1,5 +1,5 @@
 /*
-** $Id: lobject.h,v 1.100 2001/03/02 17:27:50 roberto Exp roberto $
+** $Id: lobject.h,v 1.101 2001/03/07 18:09:25 roberto Exp roberto $
 ** Type definitions for Lua objects
 ** See Copyright Notice in lua.h
 */
@@ -179,6 +179,7 @@ typedef struct Hash {
   Node *firstfree;  /* this position is free; all positions after it are full */
   struct Hash *next;
   struct Hash *mark;  /* marked tables (point to itself when not marked) */
+  int weakmode;
 } Hash;
 
 

ltable.c

@@ -1,5 +1,5 @@
 /*
-** $Id: ltable.c,v 1.77 2001/02/23 17:17:25 roberto Exp roberto $
+** $Id: ltable.c,v 1.78 2001/03/26 14:31:49 roberto Exp roberto $
 ** Lua tables (hash)
 ** See Copyright Notice in lua.h
 */
@@ -118,6 +118,7 @@ Hash *luaH_new (lua_State *L, int size) {
   G(L)->roottable = t;
   t->mark = t;
   t->size = 0;
+  t->weakmode = 0;
   t->node = NULL;
   setnodevector(L, t, power2(L, size));
   return t;

ltests.c

@@ -1,5 +1,5 @@
 /*
-** $Id: ltests.c,v 1.76 2001/03/09 18:05:05 roberto Exp roberto $
+** $Id: ltests.c,v 1.77 2001/03/26 14:31:49 roberto Exp roberto $
 ** Internal Module for Debugging of the Lua Implementation
 ** See Copyright Notice in lua.h
 */
@@ -337,9 +337,16 @@ static int table_query (lua_State *L) {
     return 2;
   }
   else if (i < t->size) {
-    TObject o;
-    setkey2obj(&o, &t->node[i]);
-    luaA_pushobject(L, &o);
+    if (ttype(val(node(t, i))) != LUA_TNIL ||
+        ttype_key(node(t, i)) == LUA_TNIL ||
+        ttype_key(node(t, i)) == LUA_TNUMBER ||
+        tsvalue_key(node(t, i)) != NULL) {
+      TObject o;
+      setkey2obj(&o, node(t, i));
+      luaA_pushobject(L, &o);
+    }
+    else
+      lua_pushstring(L, "<undef>");
     luaA_pushobject(L, &t->node[i].val);
     if (t->node[i].next) {
       lua_pushnumber(L, t->node[i].next - t->node);

lua.h

@@ -1,5 +1,5 @@
 /*
-** $Id: lua.h,v 1.92 2001/03/26 14:31:49 roberto Exp roberto $
+** $Id: lua.h,v 1.93 2001/04/06 21:17:37 roberto Exp roberto $
 ** Lua - An Extensible Extension Language
 ** TeCGraf: Grupo de Tecnologia em Computacao Grafica, PUC-Rio, Brazil
 ** e-mail: [email protected]
@@ -46,6 +46,11 @@
 #define LUA_ERRMEM	4
 #define LUA_ERRERR	5
 
+/* weak modes */
+#define LUA_WEAK_KEY	1
+#define LUA_WEAK_VALUE	2
+
+
 typedef struct lua_State lua_State;
 
 typedef int (*lua_CFunction) (lua_State *L);
@@ -208,6 +213,9 @@ LUA_API void  lua_concat (lua_State *L, int n);
 
 LUA_API void *lua_newuserdata (lua_State *L, size_t size);
 
+LUA_API void  lua_setweakmode (lua_State *L, int mode);
+LUA_API int  lua_getweakmode (lua_State *L, int index);
+
 
 /* 
 ** ===============================================================
@@ -290,7 +298,7 @@ LUA_API void *lua_newuserdata (lua_State *L, size_t size);
 
 
 /******************************************************************************
-* Copyright (C) 1994-2000 TeCGraf, PUC-Rio.  All rights reserved.
+* Copyright (C) 1994-2001 TeCGraf, PUC-Rio.  All rights reserved.
 * 
 * Permission is hereby granted, without written agreement and without license
 * or royalty fees, to use, copy, modify, and distribute this software and its