[数据结构与算法]Python 单链表节点遍历的生成器

经过几天的单链表学习，积累了很多单链表节点类的方法和属性，见以下代码。今天对其中的属性 values 做些修改，就能得到对应的生成器方法和属性。特别是当链表很长时，生成器比列表更节省内存空间。

class Node():
    def __init__(self, value=None, Next=None):
        self.val = value
        self.next = Next
        if type(self.next)==Node and self.next.val==None:
            self.next=None
 
    def __repr__(self):
        return f'Node({self.val}->{self.next})'
    
    def __str__(self):
        return f'{self.val}->{self.next}'
 
    def __len__(self):
        if self.val is None:
            return 0
        length,ptr = 0,self
        while ptr is not None:
            length += 1
            ptr = ptr.next
        return length 
 
    def __eq__(self, other):
        ptr1,ptr2 = self,other
        if len(ptr1)!=len(ptr2):
            return False
        while ptr1 is not None:
            if ptr1.val!=ptr2.val:
                return False
            ptr1 = ptr1.next
            ptr2 = ptr2.next
        else:
            return True
 
    def size(self):
        return self.__len__()
 
    @property
    def length(self):
        return self.size()
 
    @property
    def value(self):
        return self.val
 
    @property
    def values(self):
        ret,ptr = [],self
        while ptr is not None:
            ret.append(ptr.val)
            ptr = ptr.next
        return ret
 
    def pprint(self):
        items = [str(i) for i in self.values]
        if items==[]:
            print('None->None')
        elif len(items)==1:
            print(f'{items[0]}->None')
        else:
            print('->'.join(items)+'->None')
 
    def isNode(node):
        return isinstance(node,Node) and isinstance(node.next,(Node,type(None)))
 
    def build(*data, split=True):
        '''把数据转换成节点链表'''
        lst,ret = [],Node()
        for val in data:
            if type(val) is str:
                if not split:
                    lst.append(val)
                    continue
                if str=='':
                    continue
                try:
                    num = int(val)
                    lst.extend([int(_) for _ in val])
                except:
                    lst.extend([_ for _ in val])
            elif hasattr(val,'__iter__'):
                lst.extend([_ for _ in val])
            elif type(val) is Node:
                if not val.isNone:
                    lst.extend(val.values)
            else:
                lst.append(val)
        ret = Node()
        for i in lst[::-1]:
            ret = Node(i, ret)
        return ret
 
    def copy(node):
        ret = Node()
        ptr1,ptr2 = node,ret
        while ptr1 is not None:
            ptr2.next = Node(ptr1.val)
            ptr1,ptr2 = ptr1.next,ptr2.next
        return ret.next

增加链表节点数据域的遍历生成器(方法、属性)：

    def items(self):
        ptr = self
        while ptr is not None:
            yield ptr.val
            ptr = ptr.next
            
    @property
    def generator(self):
        yield from self.values

yield 语法糖： yield form?iterable object? (python 3.3+)

等价于：
for item in iterable:
????????yield?item