that should cover linked lists (and their derivates Stacks and Queues)

tools/lists.py

@@ -9,41 +9,6 @@ class Node:
     prev: 'Node' = None
 
 
-class Stack:
-    _tail: Node = None
-    size: int = 0
-
-    def push(self, obj: Any):
-        self._tail = Node(obj, self._tail)
-        self.size += 1
-
-    def pop(self) -> Any:
-        if self._tail is None:
-            raise ValueError('No more objects on stack')
-
-        res = self._tail.value
-        self._tail = self._tail.next
-        self.size -= 1
-        return res
-
-    def peek(self) -> Any:
-        if self._tail is None:
-            raise ValueError('No more objects on stack')
-
-        return self._tail.value
-
-    def __contains__(self, obj: Any) -> bool:
-        x = self._tail
-        while x.value != obj and x.next is not None:
-            x = x.next
-
-        return x.value == obj
-
-
-class Queue:
-    pass
-
-
 class LinkedList:
     _head: Union[Node, None] = None
     _tail: Union[Node, None] = None
@@ -69,19 +34,16 @@ class LinkedList:
 
         i_node.prev, i_node.next = node.prev, node
         node.prev = i_node
-        if node.prev is not None:
+        if i_node.prev is not None:
-            node.prev.next = i_node
+            i_node.prev.next = i_node
 
         if index == 0:
             self._head = i_node
 
-        if index == self.size - 1:
-            self._tail = i_node
-
         self.size += 1
 
     def _get_node(self, index: int) -> Node:
-        if abs(index) >= self.size:
+        if index >= self.size or index < -self.size:
             raise IndexError("index out of bounds")
 
         if index < 0:
@@ -110,36 +72,22 @@ class LinkedList:
             raise IndexError("pop from empty list")
 
         if index is None:  # pop from the tail
-            node = self._tail
+            index = -1
-            if self.size > 1:
-                self._tail = self._tail.prev
-                self._tail.next = None
-            else:
-                self._head = None
-                self._tail = None
 
-            ret = node.value
-        elif index == 0:  # pop from the head
-            node = self._head
-            if self.size > 1:
-                self._head = self._head.next
-                self._head.prev = None
-            else:
-                self._head = None
-                self._tail = None
-
-            ret = node.value
-        else:
         node = self._get_node(index)
         if node.prev is not None:
             node.prev.next = node.next
+        else:
+            self._head = node.next
         if node.next is not None:
             node.next.prev = node.prev
-            node.prev = None
+        else:
-            node.next = None
+            self._tail = node.prev
-            ret = node.value
 
+        ret = node.value
+        del node
         self.size -= 1
+
         return ret
 
     def append(self, obj: Any):
@@ -154,14 +102,64 @@ class LinkedList:
     def pop(self, index: int = None) -> Any:
         return self._pop(index)
 
-    def debug(self):
+    def __contains__(self, obj: Any) -> bool:
-        print("head:", self._head)
+        x = self._head
-        print("tail:", self._tail)
+        while x.value != obj and x.next is not None:
-        if self.size > 0:
+            x = x.next
-            x = 0
+
-            o = self._head
+        return x.value == obj
-            print(x, o.value)
+
-            while o.next is not None:
+    def __add__(self, other: 'LinkedList') -> 'LinkedList':
-                x += 1
+        self._tail.next = other._head
-                o = o.next
+        other._head.prev = self._tail
-                print(x, o.value)
+        self._tail = other._tail
+        self.size += other.size
+        return self
+
+    def __getitem__(self, index: int):
+        return self._get(index)
+
+    def __setitem__(self, index: int, obj: Any):
+        self._get_node(index).value = obj
+
+    def __len__(self):
+        return self.size
+
+    def __repr__(self):
+        x = self._head
+        if x is None:
+            v = ""
+        else:
+            v = str(x.value)
+            while x.next is not None:
+                x = x.next
+                v += ", " + str(x.value)
+        return "%s(%s)" % (self.__class__.__name__, v)
+
+    def __str__(self):
+        return self.__repr__()
+
+
+class Stack(LinkedList):
+    def push(self, obj: Any):
+        self._append(obj)
+
+    def pop(self) -> Any:
+        return self._pop()
+
+    def peek(self) -> Any:
+        return self._tail.value
+
+
+class Queue(LinkedList):
+    def enqueue(self, obj: Any):
+        self._append(obj)
+
+    def dequeue(self) -> Any:
+        return self._pop(0)
+
+    def peek(self) -> Any:
+        return self._head.value
+
+    push = enqueue
+    pop = dequeue