#
# This file contains the Python code from Program 6.18 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/pgm06_18.txt
#
class DequeAsArray(QueueAsArray, Deque):

    def __init__(self, size = 0):
        super(DequeAsArray, self).__init__(size)

    def enqueueHead(self, obj):
        if self._count == len(self._array):
            raise ContainerFull
        if self._head == 0:
            self._head = len(self._array) - 1
        else:
            self._head = self._head - 1
        self._array[self._head] = obj;
        self._count += 1

    # ...