lib/tree_graph.rb in tree_graph-0.2.2 vs lib/tree_graph.rb in tree_graph-0.2.3

@@ -12,10 +12,22 @@
 
   def tree_graph_bottom_up_in_same_order
     BottomUpInSameOrder.new(self).tree_graph
   end
 
+  EMPTY_ARRAY = []
+
+  class ::Object
+    def label_for_tree_graph
+      to_s
+    end
+
+    def children_for_tree_graph
+      EMPTY_ARRAY
+    end
+  end
+
   module Node
 
     attr_accessor :is_last
     attr_reader :raw_node, :parent
 
@@ -42,10 +54,10 @@
     def levels
       [level] + children_nodes.map(&:tree_graph)
     end
 
     def ancestors
-      return [] unless parent
+      return EMPTY_ARRAY unless parent
       parent.ancestors + [parent]
     end
 
     def indent
       ancestors.map do |a|