Binary Seach tree 的一段python实现

class BinarySearchTree:
    def __init__(self):
        self.root=None
        self.size=0

    def length(self):
        return self.size

    def __len__(self):
        return self.size

    def __iter__(self):
        return self.root.__iter__()


    def put(self,key,val):
        if self.root:
            self._put(key,val,self.root)
        else:
            self.root=TreeNode(key,val)
        self.size=self.size+1

    def _put(self,key,val,currentNode):
        if key < currentNode.key:
            if currentNode.hasLeftChild():
                self._put(key,val,currentNode.leftChild)
            else:
                currentNode.leftChild=TreeNode(key,val,parent=currentNode)
        else:
            if currentNode.hasRightChild():
                self._put(key,val,current.Node.rigthChild)
            else:
                currentNode.rightChild=TreeNode(key,val,parent=currentNode)


    def __setitem__(self,k,v):
        slf.put(k,v)

    def get(self,key):
        if self.root:
            res=self._get(key,self.root)
            if res:
                return res.payload
            else:
                return None
        else:
            return None

    def _get(self,key,currentNonde):
        if not currentNode:
            return None
        elif currentNode.key==key:
            return currentNode
        elif key < currentNode.key:
            return self._get(key,currentNode.leftChild)
        else:
            return self._get(key,currentNode.rightChild)

    def __getitem__(self,key):
        return self.get(key)

    def __contains__(self,key):
        if self._get(key,self.root):
            return True
        else:
            return False

    def delete(self,key):
        if self.size > 1:
            nodeToRemove=self._get(key,self.root)
            if nodeToRemove:
                self.remove(nodeToRemove)
                self.size=self.size-1
            else:
                raise KeyError('Error,key not in tree')
        elif self.size==1 and self.root.key==key:
            self.root=None
            self.size=self.size-1
        else:
            raise KeyError('Error,key not in tree')

    def __delitem__(self,key):
        self.delete(key)

    def findSuccessor(self):
        succ=None
        if self.hasRightChld():
            succ=self.rightChild.findMind()
        else:
            if self.parent:
                if self.isLeftChild():
                    succ.self.parent
                else:
                    self.parent.rightChild=None
                    succ=self.parent.findSuccessor()
                    self.parent.rightChild=self
        return succ

    def findMin(self):
        current=self
        while current.hasLeftChild():
            current=current.leftChild
        return current

    def spliceOut(self):
        if self.isLeaf():
            if self.isLeftChild():
                self.parent.leftChild=None
            else:
                self.parent.rightChild=None

        elif self.hasAnyChildren():
            if self.hasLeftChild():
                if self.isLeftChild():
                    self.parent.leftChild=self.leftChild
                else:
                    self.parent.rightChild=self.leftChild
                self.leftChild.parent=self.parent
            else:
                if self.isLeftChild():
                    self.parent.leftChild=self.rightChild
                else:
                    self.parent.rigthChild=self.rightChild
                self.rightChild.parent=self.parent

    def __iter__(self):
        if self:
            if self.hasLeftChild():
                for elem in self.leftChild:
                    yield elem
            yield self.key
            if self.hasRightChild():
                for elem in self.rightChild
                    yield elem


class TreeNode:
    def __init__(self,key,val,left=None,right=None,parent=None):
        self.key=key
        self.payload=val
        self.leftChild=left
        self.rightChild=right
        self.parent=parent

    def hasLeftChild(self):
        return self.leftChild

    def hasRightChild(self):
        return self.rightChild

    def isLeftChild(self):
        return self.parent and self.parent.leftChild==self

    def isRightChild(self):
        return self.parent and self.parent.rightChild==self

    def isRoot(self):
        return not self.parent

    def isLeaft(self):
        return not (self.rightChild or self.leftChild)

    def hasAnyChildren(self):
        return self.rightChild or self.leftChild

    def hasBothChildren(self):
        return self.rightChild and self.leftChild

    def replaceNodeData(self,key,value,lc,rc):
        self.key=key
        self.payload=value
        self.leftChild=lc
        self.rightChild=rc
        if self.hasLeftChild():
            self.leftChild.parent=self
        if self.hasRightChild():
            self.rightChild.parent=self