text: #
  # This file contains the Python code from Program 9.4 of
  # "Data Structures and Algorithms
  # with Object-Oriented Design Patterns in Python"
  # by Bruno R. Preiss.
  #
  # Copyright (c) 2003 by Bruno R. Preiss, P.Eng.  All rights reserved.
  #
  # http://www.brpreiss.com/books/opus7/programs/pgm09_04.txt
  #
  class PreOrder(PrePostVisitor):
  
      def __init__(self, visitor):
          super(PreOrder, self).__init__()
          self._visitor = visitor
  
      def preVisit(self, obj):
          self._visitor.visit(obj)
      
      def getIsDone(self):
          return self._visitor.isDone
  