class StackAsLinkedList(Stack):
__slots__ = ['__list']
def __init__(self):
super(StackAsLinkedList, self).__init__()
self.__list = LinkedList()
def purge(self):
self.__list.purge()
def getTop(self):
if self.__list.getIsEmpty():
raise IndexError("Empty")
else:
return self.__list.getHead().getData()
def push(self, obj):
self.__list.prepend(obj)
# el append de linkedlist ya hace las comprobaciones pertinentes
def pop(self):
item = self.__list.getFirst()
self.__list.extract(self.__list.getFirst())
return item
# el extract de linkedlist ya hace las comprobaciones de lista vacia
def accept(self, visitor):
assert isinstance(visitor, Visitor)
ptr = self.__list.head
while ptr is not None:
visitor.visit(ptr.data)
if visitor.isDone:
return
ptr = ptr.next
def getIsEmpty(self):
return self.__list.getIsEmpty()
class Iterator(Iterator):
__slots__ = ['__position']
def __init__(self, queue):
super(StackAsLinkedList.Iterator,self).__init__(stack)
self.__position = None
def next(self):
if self.__position is None:
self.__position = self.container._StackAsLinkedList__list.head
else:
self.__position = self.__position.next
if self.__position is None:
raise StopIteration
return self.__position.data
def __iter__(self):
return self.Iterator(self)
def _compareTo(self, obj):
assert isinstance(self, obj.__class__)
raise NotImplementedError
