#
# This file contains the Ruby code from Program 6.18 of
# "Data Structures and Algorithms
# with Object-Oriented Design Patterns in Ruby"
# by Bruno R. Preiss.
#
# Copyright (c) 2004 by Bruno R. Preiss, P.Eng.  All rights reserved.
#
# http://www.brpreiss.com/books/opus8/programs/pgm06_18.txt
#
module DequeMethods

    abstractmethod :enqueueHead

    abstractmethod :dequeueHead

    abstractmethod :head

    abstractmethod :enqueueTail

    abstractmethod :dequeueTail

    abstractmethod :tail

end

class Deque < Queue

    def initialize
	super
    end

    alias_method :queueHead, :head
    include DequeMethods
    alias_method :head, :queueHead

end