#链表结构实现  私有属性_pro_item是指向下个节点的指针，_item为此节点的值

class ChainDemo():

    def __init__(self,item = None,pos_item=None):

        self._item = item

        self._pos_item = pos_item

if __name__ == '__main__':

    chain = ChainDemo('A',(ChainDemo('B',ChainDemo('C',ChainDemo('D')))))

    while True:

        print(chain._item)

        if chain._pos_item != None:

            chain = chain._pos_item

        else:

            break

#链表节点结构实现  私有属性_pro_item是指向下个节点的指针，_item为此节点的值

class Node():

    def __init__(self,item = None,pos_item=None):

        self._item = item

        self._next = pos_item

    def __repr__(self):

        '''

        用来定义Node的字符输出，

        print为输出item

        '''

        return str(self._item)

#单链表实现

class Chain():

    def __init__(self):

        self._head = None

        self.length = 0

    #判空

    def isEmpty(self):

        return self.length == 0

    #链表结尾插入

    def append(self,item):

        if isinstance(item,Node):

            node = item

        else:

            node = Node(item)

        if self._head == None:

            self._head = node

        else:

            be_node = self._head

            while be_node._next:

                be_node = be_node._next

            be_node._next = node

        self.length += 1

    #插入数据

    def insert(self,index,item):

        if self.isEmpty():

            print('this chain table is empty')

            return

        if index<0 or index >= self.length:

            print("error: out of index")

            return

        in_node = Node(item)

        node  = self._head

        count = 1

        while True:

            node = node._next

            count += 1

            if count == index:

                next_node = node._next

                node._next = in_node

                in_node._next = next_node

                self.length += 1

                return

            # node = s

    #删除数据

    def delete(self,index):

        if self.isEmpty():

            print('this chain table is empty')

            return

        if index<0 or index >= self.length:

            print("error: out of index")

            return

        # if index == 0

        #     self._head = None

        else:

            node = self._head

            count = 0

            while True:

                count += 1

                if index == count:

                    node._next = node._next._next

                    break

                node = node._next

        self.length -= 1

    def __repr__(self):

        if self.isEmpty():

            print("the chain table is empty")

            return

        nlist = ""

        node = self._head

        while node:

            nlist += node._item +''

            node = node._next

        return nlist

if __name__ == '__main__':

    chain = Chain()

    chain.append('A')

    chain.append('B')

    chain.append('C')

    chain.append('D')

    chain.append('E')

    chain.append('F')

    chain.append('G')

    chain.insert(4,'p')

    chain.delete(3)

    print(chain,chain._head._item,chain.length)