python----------------正则实现计算器功能

# -*- coding: utf-8 -*-# Author:Gogh# @Time:2017/12/4 20:16# @Email:[e-mail] redef operator_update(formula):    # 对formula公式进行 去除空字符，更新运算符处理    formula = formula.replace(" ", "")  # 去除空字符    formula = formula.replace("+-", "-")    formula = formula.replace("--", "+")    return formuladef calc_muldiv(formula_list):    '''    计算公式里面的乘除    :param formula: 列表    :return:    '''    for index, element in enumerate(formula_list):        if "*" in element or "/" in element:            operators = re.findall("[*/]", element)            calc_list = re.split("[*/]", element)            num = None            for i, e in enumerate(calc_list):                if num:                    if operators[i - 1] == "*":                        num *= float(e)                    elif operators[i - 1] == "/":                        num /= float(e)                else:                    num = float(e)            formula_list[index] = num    return formula_listdef calc_plumin(operators, num_list):    '''    计算列表数字的加减    :param operators: 运算符列表    :param num_list: 进行运算的数字列表    :return: 返回计算结果    '''    num = None    for i, e in enumerate(num_list):        if num:            if operators[i - 1] == "+":                num += float(e)            elif operators[i - 1] == "-":                num -= float(e)        else:            num = float(e)    return numdef merge(plus_minus_operator, multiply_divide_list):    '''    把列表中这样的形式'2*' '-3*' '5/3*' '4/2'合并到一块    :param formula_list:    :return:    '''    for index, element in enumerate(multiply_divide_list):        if element.endswith("*") or element.endswith("/"):            multiply_divide_list[index] = element + plus_minus_operator[index] + multiply_divide_list[index + 1]            del multiply_divide_list[index + 1]            del plus_minus_operator[index]            return merge(plus_minus_operator, multiply_divide_list)    return plus_minus_operator, multiply_divide_listdef bracket_calc(formula):    '''    对括号最内层的formula公式进行计算    :param formula:    :return:    '''    formula = re.sub("[()]", "", formula)  # 去除两边的（）    formula = operator_update(formula)    plus_minus_operator = re.findall("[+-]", formula)  # 列表 '+' '-' 运算符    multiply_divide_list = re.split("[+-]", formula)  # 列表 有'*' '/'    if multiply_divide_list[0] == "":  # multiply_divide_list列表第一个字符为空的话，表示一个数字为负号        multiply_divide_list[1] = "-" + multiply_divide_list[1]        del plus_minus_operator[0]        del multiply_divide_list[0]    res = merge(plus_minus_operator, multiply_divide_list)    plus_minus_operator = res[0]  # 列表 '+' '-' 运算符 进行合并处理    multiply_divide_list = res[1]    plus_minus_list = calc_muldiv(multiply_divide_list)  # 生成只进行加减运算的列表    res = calc_plumin(plus_minus_operator, plus_minus_list)    return resdef calculate(formula):    '''计算程序主入口, 主要逻辑是先计算拓号里的值,算出来后再算乘除,再算加减'''    while True:        formula_depth = re.search("\([^()]+\)", formula)        if formula_depth:            formula_depth = formula_depth.group()            res = bracket_calc(formula_depth)            formula = formula.replace(formula_depth, str(res))            print("\33[34;1m%s\33[0m" % (formula))        else:            res = bracket_calc(formula)            print("\33[31;1m结果:%s\33[0m" % (res))            exit()if __name__ == '__main__':    formula = "1 - 2 * ( (60-30 +(-9-2- 5-2*-3-5/3-40*4/2-3/5+6*3) * (-9-2-5-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) -(-4*3)/ (16-3*2) )"    calculate(formula)