add data argument to container:add(...)

src/logic/scripting/lua/libs/libgui.cpp

@@ -83,8 +83,16 @@ static int l_container_add(lua::State* L) {
     }
     auto xmlsrc = lua::require_string(L, 2);
     try {
+        auto env = docnode.document->getEnvironment();
+        if (lua::istable(L, 3)) {
+            env = create_environment(std::move(env));
+            lua::pushenv(L, *env);
+            lua::pushvalue(L, 3);
+            lua::setfield(L, "DATA");
+            lua::pop(L);
+        }
         auto subnode = guiutil::create(
-            engine->getGUI(), xmlsrc, docnode.document->getEnvironment()
+            engine->getGUI(), xmlsrc, std::move(env)
         );
         node->add(subnode);
         UINode::getIndices(subnode, docnode.document->getMapWriteable());

src/logic/scripting/scripting.cpp

@@ -154,6 +154,22 @@ std::unique_ptr<Process> scripting::start_coroutine(
     });
 }
 
+[[nodiscard]] scriptenv scripting::create_environment(
+    const scriptenv& parent
+) {
+    auto L = lua::get_main_state();
+    int id = lua::create_environment(L, (parent ? *parent : 0));
+    lua::pushenv(L, id);
+    lua::pushvalue(L, -1);
+    lua::setfield(L, "CUR_ENV");
+
+    lua::pop(L);
+    return std::shared_ptr<int>(new int(id), [=](int* id) { //-V508
+        lua::remove_environment(L, *id);
+        delete id;
+    });
+}
+
 [[nodiscard]] scriptenv scripting::create_doc_environment(
     const scriptenv& parent, const std::string& name
 ) {

src/logic/scripting/scripting.hpp

@@ -58,6 +58,7 @@ namespace scripting {
 
     scriptenv get_root_environment();
     scriptenv create_pack_environment(const ContentPack& pack);
+    scriptenv create_environment(const scriptenv& parent);
     scriptenv create_doc_environment(
         const scriptenv& parent, const std::string& name
     );