Change the creation/deletion of tangibles so that the tangible database is never really deleted.

luprex/cpp/core/luastack.cpp

@@ -376,6 +376,54 @@ void LuaStack::makeclass(LuaSlot tab, std::string_view name) const {
     lua_pop(L_, 1);
 }
 
+void LuaStack::maketan(LuaSlot tab, int64_t id) const {
+    LuaVar tangibles, metatab;
+    LuaStack LS(L_, tangibles, metatab);
+    
+    // Try to get the existing tangible.
+    LS.rawget(tangibles, LuaRegistry, "tangibles");
+    LS.rawget(tab, tangibles, id);
+
+    // If we succeeded, return it.
+    if (LS.istable(tab)) {
+        LS.result();
+        return;
+    }
+
+    // Create the tangible's database and metatable.
+    LS.set(tab, LuaNewTable);
+    LS.set(metatab, LuaNewTable);
+    LS.setmetatable(tab, metatab);
+
+    // Mark the tangible using the tabletype field.
+    LS.settabletype(tab, LUA_TT_TANGIBLE);
+    LS.settabletype(metatab, LUA_TT_TANGIBLEMETA);
+
+    // Store the tangible ID and lock the metatable.
+    LS.rawset(metatab, "id", id);
+    LS.rawset(metatab, "__metatable", false);
+
+    // Store the database into the tangibles table.
+    LS.rawset(tangibles, id, tab);
+
+    LS.result();
+}
+
+
+bool LuaStack::tanblank(LuaSlot tab) const {
+    bool result = true;
+    if (istable(tab) && gettabletype(tab) == LUA_TT_TANGIBLE) {
+        if (lua_getmetatable(L_, tab.index())) {
+            lua_pushstring(L_, "threads");
+            lua_rawget(L_, -2);
+            if (lua_type(L_, -1) == LUA_TTABLE) {
+                result = false;
+            }
+            lua_pop(L_, 2);
+        }
+    }
+    return result;
+}
 
 int64_t LuaStack::tanid(LuaSlot tab) const {
     int64_t result = 0;