lib/rgl/traversal.rb in rgl-0.6.3 vs lib/rgl/traversal.rb in rgl-0.6.4

@@ -115,10 +115,12 @@
     # This method uses the +tree_edge_event+ of BFSIterator
     # to record all tree edges of the search tree in the result.
     #
     # @return [DirectedAdjacencyGraph] which represents a BFS search tree starting at _v_.
     def bfs_search_tree_from(v)
-      require 'rgl/adjacency'
+      unless defined?(DirectedAdjacencyGraph)
+        require 'rgl/adjacency'
+      end
       bfs  = bfs_iterator(v)
       tree = DirectedAdjacencyGraph.new
 
       bfs.set_tree_edge_event_handler do |from, to|
         tree.add_edge(from, to)