Nodes: add owner_tree method to nodes

source/blender/blenkernel/BKE_node_runtime.hh

@@ -361,6 +361,12 @@ inline const bNodeSocket &bNode::output_by_identifier(blender::StringRef identif
   return *this->runtime->outputs_by_identifier.lookup_as(identifier);
 }
 
+inline const bNodeTree &bNode::owner_tree() const
+{
+  BLI_assert(blender::bke::node_tree_runtime::topology_cache_is_available(*this));
+  return *this->runtime->owner_tree;
+}
+
 inline blender::StringRefNull bNode::label_or_name() const
 {
   if (this->label[0] == '\0') {

source/blender/makesdna/DNA_node_types.h

@@ -410,6 +410,8 @@ typedef struct bNode {
   /** Lookup socket of this node by its identifier. */
   const bNodeSocket &input_by_identifier(blender::StringRef identifier) const;
   const bNodeSocket &output_by_identifier(blender::StringRef identifier) const;
+  /** Node tree this node belongs to. */
+  const bNodeTree &owner_tree() const;
 #endif
 } bNode;