Function postordereval

ParseTree.py:58–68

(tree)

# 利用后序遍历实现两个叶结点的运算
def postordereval(tree):
    opers = {'+': operator.add, '-': operator.sub, '*': operator.mul, '/': operator.truediv}
    res1 = None
    res2 = None
    if tree:
        res1 = postordereval(tree.getLeftChild())
        res2 = postordereval(tree.getRightChild())
        if res1 and res2:
            return opers[tree.getRootVal()](res1, res2)
        else:
            return tree.getRootVal()

# 递归实现中序遍历
def inorder(tree):