计算器加减乘除(去括号待完善)

#!/usr/bin/env python
# -*- coding:utf-8 -*-

import re


def cheng(suanshi):
    try:
        while 1:
            x = re.search(r'-?d+(.d+)?[*/]d+(.d+)?', suanshi)
            a, b, c = re.split(r'([*/])', x.group())
            a = float(a)
            c = float(c)
            if b == '*':
                res = a * c
            elif b == '/':
                res = float(a / c)
            suanshi = suanshi.replace(x.group(), str(res), 1)
    except Exception:
        obj = re.search('([^()]+)', suanshi)
        print(obj)
        if not obj.group():
            return suanshi[1:-1]
        return suanshi


def jia(suanshi):
    try:
        while 1:
            x = re.search(r'-?d+(.d+)?[-+]d+(.d+)?', suanshi)
            lst = re.split(r'([-+])', x.group())
            if len(lst) == 5:
                q, w, a, b, c = lst
                if b == '+':
                    res = - float(a) + float(c)
                elif b == '-':
                    res = -(float(a) + float(c))
            elif len(lst) == 3:
                a, b, c = lst
                if b == '+':
                    res = float(a) + float(c)
                elif b == '-':
                    res = float(a) - float(c)
            suanshi = suanshi.replace(x.group(), str(res), 1)
            print(suanshi)
    except Exception:
        return suanshi


# user = input('请输入算式:')
user = '1-2*((60-30+(-40/5)*(9-2*5/4+7/2+10*14/7))-(-4*3)/(16-3*2))'
while 1:
    lst = re.findall('([^()]+)', user)
    print(lst)
    if not lst:
        res = jia(cheng(user))[1:-1]
        user = user.replace('--', '+')
        user = user.replace('+-', '-')
        continue
    for i in lst:
        user = user.replace(i, cheng(i), 1)
    print(user)
    lst2 = re.findall('([^()]+)', user)
    for j in lst2:
        user = user.replace(j, jia(j), 1)
    print(user)