class PriorityQueue:
def __init__(self):
self._list = DoublyLinkedList()
def __len__(self) -> int:
return len(self._list)
def __iter__(self) -> Generator[T]:
yield from self._list
def enqueue(self, data: T) -> None:
if len(self) == 0:
self._list.add_last(data)
else:
current = self._list.head
while current and current.data > data:
current = current.next_
if current is None:
self._list.add_last(data)
else:
self._list.add_before(current, data)
def peek(self) -> T:
if len(self) == 0:
raise IndexError("peek from empty priority queue")
return self._list.head.data
def dequeue(self) -> T:
if len(self) == 0:
raise IndexError("dequeue from empty priority queue")
data = self.peek()
self._list.remove_first()
return data
def test_container():
linked_list = DoublyLinkedList()
linked_list.add_last(1)
linked_list.add_last(2)
assert 1 in linked_list
assert 2 in linked_list
assert 3 not in linked_list
def test_reversed():
linked_list = DoublyLinkedList()
linked_list.add_last(1)
linked_list.add_last(2)
linked_list.add_last(3)
values_list = [item for item in reversed(linked_list)]
assert values_list == [3, 2, 1]
def test_iteration():
linked_list = DoublyLinkedList()
linked_list.add_last(1)
linked_list.add_last(2)
linked_list.add_last(3)
values_list = [item for item in linked_list]
assert values_list == [1, 2, 3]
def test_remove_added_last(method_name, size, head, tail):
dll = DoublyLinkedList()
for n in range(size):
dll.add_last(n)
method = getattr(dll, method_name)
method()
assert len(dll) == (size - 1)
assert dll.head == head
assert dll.tail == tail
def test_add_before_tail():
linked_list = DoublyLinkedList()
linked_list.add_last(1)
linked_list.add_last(3)
linked_list.add_before(linked_list.tail, 2)
head = linked_list.head
middle = head.next_
tail = linked_list.tail
assert head == 1
assert head.previous is None
assert head.next_ == middle
assert middle == 2
assert middle.previous == head
assert middle.next_ == tail
assert tail == 3
assert tail.previous == middle
assert tail.next_ is None