class AnimalShelter():
q = None # Queue
def __init__(self):
# create internal data structs
self.q = Queue()
def enqueue(self, animal: Animal):
# add animal to shelter
self.q.enqueue(animal.serialize())
def dequeue(self, pref: AnimalType = None) -> Animal:
# grab animal that has been in queue the longest, optionally provide parameter
# No Pref First
if pref == None:
b, val = self.q.peek()
if not b:
return None
if self.q.dequeue(val):
return Animal.Factory(val)
else:
stack = Stack()
# Find the Animal we Want (deq, push to stack)
found = False
b, val = self.q.peek()
while b:
animal = Animal.Factory(val)
if animal.animaltype == pref:
found = True
break
stack.push(val)
self.q.dequeue(val)
b, val = self.q.peek()
if found:
# Pop off stack and enqueue back to queue
# record the current count, as we need to cycle the enq (back of line) to the front
c = self.q.count()
b, val = stack.peek()
while b:
val = stack.pop()
self.q.enqueue(val)
b, val = stack.peek()
# cycle the back of the list to the front
diff = self.q.count() - c
for x in range(diff):
val = self.q.peek()
self.q.dequeue(val)
self.q.enqueue(val)
return animal
else:
return None
def test_queue_enqueue():
# enqueue into a queue
q = Queue()
q.enqueue('pao de queijo')
assert q.count() == 1
