eris: add general purpose 'flag bits' to lua tables'

luprex/eris-master/src/eris.c

@@ -905,6 +905,9 @@ static void
 p_literaltable(Info *info) {                                       /* ... tbl */
   eris_checkstack(info->L, 3);
 
+  unsigned char bits = lua_getflagbits(info->L, -1);
+  WRITE_VALUE(bits, uint8_t);
+
   /* Persist all key / value pairs. */
   lua_pushnil(info->L);                                        /* ... tbl nil */
   while (lua_next(info->L, -2)) {                              /* ... tbl k v */
@@ -943,6 +946,8 @@ u_literaltable(Info *info) {                                           /* ... */
   eris_checkstack(info->L, 3);
 
   lua_newtable(info->L);                                           /* ... tbl */
+  unsigned char bits = READ_VALUE(uint8_t);
+  lua_setflagbits(info->L, -1, bits);
 
   /* Preregister table for handling of cycles (keys, values or metatable). */
   registerobject(info);

luprex/eris-master/src/lapi.c

@@ -898,6 +898,38 @@ LUA_API void lua_setuservalue (lua_State *L, int idx) {
 }
 
 
+LUA_API void lua_setflagbits (lua_State *L, int idx, unsigned char bits) {
+  TValue *obj;
+  Table *tab;
+  lua_lock(L);
+  obj = index2addr(L, idx);
+  api_check(L, ttistable(obj), "table expected");
+  tab = hvalue(obj);
+  tab->flagbits = bits;
+  lua_unlock(L);
+}
+
+LUA_API void lua_modflagbits (lua_State *L, int idx, unsigned char set, unsigned char clear) {
+  TValue *obj;
+  Table *tab;
+  lua_lock(L);
+  obj = index2addr(L, idx);
+  api_check(L, ttistable(obj), "table expected");
+  tab = hvalue(obj);
+  tab->flagbits |= set;
+  tab->flagbits &= (~clear);
+  lua_unlock(L);
+}
+
+LUA_API unsigned char lua_getflagbits (lua_State *L, int idx) {
+  TValue *obj;
+  Table *tab;
+  obj = index2addr(L, idx);
+  api_check(L, ttistable(obj), "table expected");
+  tab = hvalue(obj);
+  return tab->flagbits;
+}
+
 /*
 ** `load' and `call' functions (run Lua code)
 */

luprex/eris-master/src/lobject.h

@@ -556,6 +556,7 @@ typedef struct Node {
 typedef struct Table {
   CommonHeader;
   lu_byte flags;  /* 1<<p means tagmethod(p) is not present */
+  lu_byte flagbits;  /* flag bits reserved for the user */
   lu_byte lsizenode;  /* log2 of size of `node' array */
   int sizearray;  /* size of `array' array */
   int nnkeys;     /* number of non-nil keys in both array and hash */

luprex/eris-master/src/ltable.c

@@ -509,6 +509,7 @@ Table *luaH_new (lua_State *L) {
   Table *t = &luaC_newobj(L, LUA_TTABLE, sizeof(Table), NULL, 0)->h;
   t->metatable = NULL;
   t->flags = cast_byte(~0);
+  t->flagbits = 0;
   t->array = NULL;
   t->sizearray = 0;
   t->node = cast(Node *, dummynode);

luprex/eris-master/src/lua.h

@@ -245,7 +245,9 @@ LUA_API void  (lua_rawseti) (lua_State *L, int idx, int n);
 LUA_API void          (lua_rawsetp) (lua_State *L, int idx, const void *p);
 LUA_API int           (lua_setmetatable) (lua_State *L, int objindex);
 LUA_API void          (lua_setuservalue) (lua_State *L, int idx);
-
+LUA_API void          (lua_setflagbits) (lua_State *L, int idx, unsigned char bits);
+LUA_API void          (lua_modflagbits) (lua_State *L, int idx, unsigned char set, unsigned char clear);
+LUA_API unsigned char (lua_getflagbits) (lua_State *L, int idx);
 
 /*
 ** 'load' and 'call' functions (load and run Lua code)