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Sub: Update xorlist 

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==== End ====
This commit is contained in:
Shockwave 2022-11-26 10:28:32 +08:00
parent c1b3b9a9d6
commit 42aeecf17a
1 changed files with 13 additions and 7 deletions
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20
snippet/python/xorlist.py
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@ -34,15 +34,18 @@ class XorList:
def insert(self, data): def insert(self, data):
node = Node(data) node = Node(data)
node_id = id(node) node_id = id(node)
# New node npx is XOR of current head and NULL # New node npx is XOR of current head and id(None)
node.npx = id(self.head)
# node.npx = self.xor(node_id, id(self.head)) # node.npx = self.xor(node_id, id(self.head))
node.npx = id(self.head)
if self.head is not None: if self.head is None:
# list is empty, set tail to the first node.
self.tail = node
else: # list is not empty, update npx of old head
old_head_npx = self.head.npx old_head_npx = self.head.npx
self.head.npx = self.xor(node_id, old_head_npx) self.head.npx = self.xor(node_id, old_head_npx)
else: # old_head_id = id(self.head)
self.tail = node # node.npx = self.xor(old_head_id, id(None))
self.__nodes.append(node) self.__nodes.append(node)
self.head = node self.head = node
@ -67,7 +70,7 @@ class XorList:
def backward(self): def backward(self):
print("backward visit list") print("backward visit list")
rear_id = NULL rear_id = id(None)
curr_node = self.tail curr_node = self.tail
if curr_node is None: if curr_node is None:
@ -85,7 +88,10 @@ class XorList:
""" """
Returns a new instance of type points to the same memory Returns a new instance of type points to the same memory
""" """
return ctypes.cast(obj_id, ctypes.py_object).value py_obj = ctypes.cast(obj_id, ctypes.py_object)
if not py_obj:
return None
return py_obj.value
if __name__ == '__main__': if __name__ == '__main__':