Added luasnap checkpointing mechanism

luprex/cpp/luastack.cpp

@@ -38,17 +38,20 @@ int LuaStack::collect_tagged_pointer(lua_State *L) {
 }
 
 void LuaStack::register_all_userdata(lua_State *L) {
-    LuaVar tab, lud;
-    LuaStack LS(L, tab, lud);
+    LuaVar tab, lud, classtab, classname;
+    LuaStack LS(L, tab, lud, classtab, classname);
     auto regs = LuaFunctionReg::all();
     for (const LuaFunctionReg *r : regs) {
         const std::string &name = util::tolower(r->get_name());
         lua_CFunction tag = r->get_func();
         std::string mode = r->get_mode();
+        LS.set(classname, name);
         if (mode.find('t') != std::string::npos) { // Register type
             LS.newtable(tab);
             LS.setfield(tab, "type", name);
             LS.setfield(tab, "__gc", collect_tagged_pointer);
+            LS.makeclass(classtab, classname);
+            LS.setfield(tab, "__index", classtab);
             LS.setlightuserdata(lud, (void *)tag);
             LS.rawset(LuaRegistry, lud, tab);
         }
@@ -202,6 +205,37 @@ void LuaStack::newtable(LuaSlot target) const {
     lua_replace(L_, target);
 }
 
+void LuaStack::makeclass(LuaSlot classtab, LuaSlot classname) const {
+    int top = lua_gettop(L_);
+    checkstring(classname);
+
+    // Special case: if the classname is _G, return global env.
+    lua_pushstring(L_, "_G");
+    int eqlg = lua_equal(L_, -1, classname.index());
+    lua_settop(L_, top);
+    if (eqlg) {
+        set(classtab, LuaGlobals);
+        return;
+    }
+    
+    // Get the classtab from the global environment.
+    // Create it if it doesn't exist.
+    rawget(classtab, LuaGlobals, classname);
+    if (isnil(classtab)) {
+        newtable(classtab);
+        rawset(LuaGlobals, classname, classtab);
+    }
+
+    // If the name isn't bound to a table, abort.
+    if (!istable(classtab)) {
+        luaL_error(L_, "%s is not a class", ckstring(classname).c_str());
+    }
+
+    // Repair the special fields.
+    setfield(classtab, "__index", classtab);
+    setfield(classtab, "__class", classname);
+}
+
 void LuaStack::setlightuserdata(LuaSlot target, void *p) const {
     lua_pushlightuserdata(L_, p);
     lua_replace(L_, target);