Remove empty parent menus when menu item is deleted.

Author: tedwaine

src/ui/model_data/src/model_data_actor.cpp

@@ -69,15 +69,24 @@ utility::JsonTree *find_node_matching_string_field(
 }
 
 bool find_and_delete(
-    utility::JsonTree *data, const std::string &field, const std::string &field_value) {
+    utility::JsonTree *data, const std::string &field, const std::string &field_value, const bool cleanup_empty_nodes=false) {
     if (data->data().contains(field) && data->data()[field].get<std::string>() == field_value) {
 
         data->parent()->erase(std::next(data->parent()->begin(), data->index()));
         return true;
 
     } else {
         for (auto p = data->begin(); p != data->end(); ++p) {
-            if (find_and_delete(&(*p), field, field_value)) {
+            if (find_and_delete(&(*p), field, field_value, cleanup_empty_nodes)) {
+                if (cleanup_empty_nodes &&
+                    data->empty() && data->parent()) {
+                    // after we've done a deletion, does that leave the node's
+                    // parent empty? For menu models, this will leave an empty
+                    // submenu which will generally not be desirable.
+                    // Therefore, remove the empty parent node here.
+                    data->parent()->erase(std::next(data->parent()->begin(), data->index()));
+                }
+
                 return true;
             }
         }
@@ -1404,7 +1413,7 @@ void GlobalUIModelData::remove_node(
 
             std::string uuid_string = to_string(model_item_id);
             std::string field("uuid");
-            if (find_and_delete(menu_model_data, field, uuid_string)) {
+            if (find_and_delete(menu_model_data, field, uuid_string, true)) {
                 broadcast_whole_model_data(mmn->name_);
             }
         }