exp_tree.py 文件源码

def evaluate(t): # Evaluate a expression tree
    oper = {'+':operator.add, '-':operator.sub, '*':operator.mul, '/':operator.truediv}
    left = t.get_left()
    right = t.get_right()
    if left and right:
        return oper[t.get_root()](evaluate(left),evaluate(right))
    else:
        return t.get_root()