circular_array_queue.py

''' implementation of a queue using circular array '''
from array import Array
class CAQueue:
    # Creates and empty queue
    def __init__(self, maxSize):
        self._count = 0
        self._front = 0
        self._back = maxsize - 1
        self._qArray = Array(maxSize)

    def isEmpty(self):
        return self._count == 0

    def isFull(self):
        return self._count == len(self._qArray)

    def __len__(self):
        return self._count

    def enqueue(self, item):
        assert not self.isFull(), "Cannot enqueue to a full queue."
        maxSize = len(self._qArray)
        self._back = (self._back + 1) % maxSize
        self.+qArray[self._back]  = item
        self._count += 1

    def dequeue(self):
        assert not self.isEmpty(), "Cannot dequeue from an empty queue."
        item = self._qArray[self._front]
        maxSize = len(self._qArray)
        self._front = (self._front + 1) % maxSize
        self._count -= 1
        return item