Python单链表的简单实现方法

class LinkedList(object):    class Element(object):        def __init__(self,list,datum,next):       self._list = list      self._datum = datum       self._next = next    def getDatum(self):       return self._datum    datum = property(      fget = lambda self: self.getDatum())    def getNext(self):      return self._next    next = property(      fget = lambda self: self.getNext())  def __init__(self):    self._head = None    self._tail = None  def getHead(self):    return self._head   head = property(    fget = lambda self: self.getHead())   def prepend(self,item):    tmp = self.Element (self,item,self._head)    if self._head is None:      self._tail = tmp     self._head = tmp   def insert(self, pos, item):    i = 0    p = self._head    while p != None and i < pos -1:      p = p._next      i += 1    if p == None or i > pos-1:      return -1    tmp = self.Element(self, item, p._next)    p._next = tmp    return 1  def getItem(self, pos):    i = 0    p = self._head    while p != None and i < pos -1:      p = p._next      i += 1    if p == None or i > post-1:      return -1    return p._datum  def delete(self, pos):    i = 0    p = self._head    while p != None and i < pos -1:      p = p._next      i += 1    if p == None or i > post-1:      return -1    q = p._next    p._nex = q._next    datum = p._datum    return datum  def setItem(self, pos, item):    i = 0    p = self._head    while p != None and i < pos -1:      p = p._next      i += 1    if p == None or i > post-1:      return -1    p._datum = item    return 1  def find(self, pos, item):    i = 0    p = self._head    while p != None and i < pos -1:      if p._datum == item:        return 1      p = p._next      i += 1    return -1  def empty(self):    if self._head == None:      return 1    return 0  def size(self):    i = 0    p = self._head    while p != None and i < pos -1:      p = p._next      i += 1    return i  def clear(self):    self._head = None    self._tail = Nonetest = LinkedList()test.prepend('test0')print test.insert(1, 'test')print test.head.datumprint test.head.next.datum