preceding_node_of

# File lib/rexml/xpath_parser.rb, line 546
    def preceding_node_of( node )
      psn = node.previous_sibling_node
      if psn.nil?
        if node.parent.nil? or node.parent.class == Document
          return nil
        end
        return node.parent
        #psn = preceding_node_of( node.parent )
      end
      while psn and psn.kind_of? Element and psn.children.size > 0
        psn = psn.children[-1]
      end
      psn
    end