如何使用遍历双链表并跳过空节点的Iterator

Question

由于双链表有两个虚拟节点，一个是头，另一个是尾。我可以通过self.__current == None: raise StopIteration跳过假尾节点，但我不知道如何通过假头节点并继续遍历下面的节点。

class LinkedListDLL:
    def __init__(self):
        self.__head = NodeDLL(None)
        self.__head.set_next(self.__head)
        self.__head.set_prev(self.__head)
        self.__count = 0
    def size(self):
        return self.__count;
    def is_empty(self):
        return self.__count == 0
    def add_before(self, item, curr):
        new_node = NodeDLL(item)
        new_node.set_next(curr)
        new_node.set_prev(curr.get_prev())
        curr.set_prev(new_node)
        new_node.get_prev().set_next(new_node)
        self.__count += 1
    def add_to_head(self, item):
        self.add_before(item, self.__head.get_next())
    def add_to_tail(self, item):
        self.add_before(item, self.__head)
    def remove_from_head(self):
        self.remove(self.__head.get_next())
    def remove_from_tail(self):
        self.remove(self.__head.get_prev())
    def remove(self, curr):
        curr.get_prev().set_next(curr.get_next())
        curr.get_next().set_prev(curr.get_prev())
        self.__count -= 1
    def __iter__(self):
        return LinkedListIterator(self.__head)
class LinkedListIterator:
    def __init__(self, head):
        self.__current = head
    def __next__(self):
        if self.__current == None :
            raise StopIteration
        else:
            item = self.__current.set_data.get_next()
            self.__current = self.__current.get_next()
            return item

Answer 1

您应该重构代码，记住NodeDLL(None)可能与None不同。完成后:

def __next__(self):
    if not self.__current.get_next():
        raise StopIteration
    #Skips first value in list, i.e. head
    self.__current = self.__current.get_next()
    return self.__current