class Queue:
__slots__ = 'ring_buffer', 'max_capacity'
"""constructor with intial max capacity of 10"""
def __init__(self, capacity=10):
self.ring_buffer = RingBuffer(capacity)
self.max_capacity = capacity
"""to string function uses the internal to string of ring buffer but
points to the end"""
def __str__(self):
return str(self.ring_buffer) + '<-- end '
""" enqueue function which inserts values in the queue """
def enqueue(self, value):
if value is None:
raise Exception('cannot enqueue None element in the queue')
else:
self.ring_buffer.insert_keep_old(value)
""" dequeue function which removes values from the queue using FIFO
method
raises an exception if dequeue is done on the empty queue"""
def dequeue(self):
if self.ring_buffer.size() is 0:
raise Exception('dequeue from a empty queue is not allowed')
else:
return self.ring_buffer.remove_oldest()
""" returns the current size of the stack"""
def size(self):
return self.ring_buffer.size()
""" :return the max capacity of the stack """
def capacity(self):
return self.ring_buffer.capacity()
""" only returns the value of the first element in the queue does not
removed the element from the queue
"""
def peek(self):
if self.size() < 1:
raise Exception('peek into a empty queue is not allowed')
else:
return self.ring_buffer.start_element()
def test_init(self):
rb = RingBuffer(4)
rs = RingStack(4)
rq = RingQueue(4)
ls = ListStack(4)
lq = ListQueue(4)
self.assertIsNotNone(rb.head)
self.assertEqual(rb.size(), 0)
self.assertEqual(rs.top, -1)
self.assertEqual(rs.size, 0)
self.assertEqual(ls.top, -1)
self.assertEqual(ls.size, 0)
self.assertEqual(rq.front, -1)
self.assertEqual(rq.back, -1)
self.assertEqual(rq.size, 0)
self.assertEqual(lq.front, -1)
self.assertEqual(lq.back, -1)
self.assertEqual(lq.size, 0)
list1.enqueue(5)
print("Printing Queue")
list1.__str__()
print("Adding 6 but it should not be added as Queue is full")
list1.enqueue(6)
print("Now doing dqueue and printing the queue")
list1.dequeue()
list1.__str__()
print("Adding 6 now")
list1.enqueue(6)
print("Printing Queue")
list1.__str__()
print("Checking Queue's size")
print(list1.size())
print("Checking Queue's capacity")
print(list1.capacity1)
print("Peek on Queue returns")
print(list1.peek())
print("Reseting the Queue with size 0")
list1 = Queue(0)
print("Now trying to add 1")
list1.enqueue(1)
print("Now trying to print Queue")
list1.__str__()
print("Now trying to dequeqe")
list1.dequeue()
