计算器（正则练习详细步骤）

s='1-2*((60-30+(-40/5)*(9-2*5/3+7/3*99/4*2998+10*568/14))-(-4*3)/(16-3*2))'
def cacular(s):
    import re
    def division(a, b):
        return float(a) / float(b)
    def multiplication(a, b):
        return float(a) * float(b)
    def subtraction(a, b):
        return float(a) - float(b)
    def addition(a, b):
        return float(a) + float(b)
    dic = {"*": multiplication, "/": division, "-": subtraction, "+": addition}
    s = s.replace('++', '+')
    s = s.replace('+-', '-')
    s = s.replace('-+', '-')
    s = s.replace("--", '+')
    while re.search('[(][^(]*?[)]',s):
        brackets=re.search('[(][^(]*?[)]',s).group()
        print(f'当前括号内容{brackets}')
        re.search('[(][^(]*?[)]',brackets)
        brackets_inner = re.search('[(]([^(]*?)[)]', brackets).group(1)
        print(f"当前表达式：{brackets_inner}")
        while re.search('d+.?d*[/*]-?d+.?d*',brackets_inner):
            first_MAD = re.search("(?P<firstnumber>d+.?d*)(?P<sign>[*/])(?P<secondnumber>-?d+.?d*)", brackets_inner)
            value=dic[first_MAD.group('sign')](first_MAD.group('firstnumber'),first_MAD.group('secondnumber'))
            brackets_inner=brackets_inner.replace(first_MAD.group(),str(value))
            print(brackets_inner)
        print('当前乘除法结束')
        while re.search('-?d+.?d*[+-]-?d+.?d*',brackets_inner):
            first_ADS = re.search("(?P<firstnumber>-?d+.?d*)(?P<sign>[+-])(?P<secondnumber>-?d+.?d*)", brackets_inner)
            value=dic[first_ADS.group('sign')](first_ADS.group('firstnumber'),first_ADS.group('secondnumber'))
            brackets_inner=brackets_inner.replace(first_ADS.group(),str(value))
            print(brackets_inner)
        print('当前加减法结束')
        print(brackets_inner,brackets)
        s=s.replace(brackets,brackets_inner)
        s = s.replace('++', '+')
        s = s.replace('+-', '-')
        s = s.replace('-+', '-')
        s = s.replace("--", '+')
    print('当前括号内容执行完毕')
    print(s)
    while re.search('d+.?d*[/*]-?d+.?d*', s):
        first_MAD = re.search("(?P<firstnumber>d+.?d*)(?P<sign>[*/])(?P<secondnumber>-?d+.?d*)", s)
        value = dic[first_MAD.group('sign')](first_MAD.group('firstnumber'), first_MAD.group('secondnumber'))
        s = s.replace(first_MAD.group(), str(value))
        print(s)
    print('当前乘除法结束')
    while re.search('-?d+.?d*[+-]-?d+.?d*', s):
        first_MAD = re.search("(?P<firstnumber>-?d+.?d*)(?P<sign>[+-])(?P<secondnumber>-?d+.?d*)", s)
        value = dic[first_MAD.group('sign')](first_MAD.group('firstnumber'), first_MAD.group('secondnumber'))
        s = s.replace(first_MAD.group(), str(value))
        print(s)
    print('当前加减法结束')
    return float(s)
cacular(s)

print(eval(s))