bugfix: http://study.163.com/forum/detail/1004978058.htm

Author: PegasusWang

docs/03_链表/linked_list.py

@@ -43,6 +43,8 @@ def append(self, value):    # O(1)
         self.length += 1
 
     def appendleft(self, value):
+        if self.maxsize is not None and len(self) > self.maxsize:
+            raise Exception('LinkedList is Full')
         headnode = self.root.next
         node = Node(value)
         self.root.next = node
@@ -100,6 +102,9 @@ def popleft(self):    # O(1)
         self.root.next = headnode.next
         self.length -= 1
         value = headnode.value
+
+        if self.tailnode is headnode:   # 勘误：增加单节点删除 tailnode 处理
+            self.tailnode = None
         del headnode
         return value
 
@@ -138,6 +143,12 @@ def test_linked_list():
     assert len(ll) == 2
     assert list(ll) == [1, 3]
 
+    assert ll.popleft() == 1
+    assert list(ll) == [3]
+    ll.popleft()
+    assert len(ll) == 0
+    assert ll.tailnode is None
+
     ll.clear()
     assert len(ll) == 0