class Queue(object):
@staticmethod
def from_list(l):
_q = Queue()
for item in l:
_q.insert(item)
return _q
def __init__(self, max_size=None):
self._ll = None
self._head_of_queue = None
self.max_size = max_size
def push(self, item):
if self._head_of_queue is None:
self._ll = LinkedList(item)
self._head_of_queue = self._ll
else:
self._head_of_queue.insert(item)
self._head_of_queue = self._head_of_queue.next_l
def to_list(self):
return self._ll.to_list() if self._ll is not None else []
def pop(self):
if len(self) == 0:
raise ValueError("Can't pop from an empty queue")
ans = self._ll.item
self._ll = self._ll.next_l
if self._ll is None:
self._head_of_queue = None
return ans
def __len__(self):
return 0 if self._ll is None else len(self._ll)
def __eq__(self, other):
return self._ll == other._ll
def __ne__(self, other):
return not self.__eq__(other)
def __iter__(self):
return iter(self.to_list())
def __str__(self):
return '->'.join(map(str, self.to_list()[::-1]))
