Pythonは逆ポーランド計算機を実現

Pythonは逆ポーランド計算機を実現

#-----------------------------      --------------------------------
class Stack():#     
    def __init__(self,):
        self.stack = []
    def push(self,data):#  
        self.stack.append(data)
    def pop(self):#  
        return self.stack.pop()
    def is_empty(self):#    
        return not len(self.stack)
    def top(self):#    
        if self.is_empty():
            return None
        return self.stack[-1]




class InversPolishCalculator(object):#      

    def deal(self,exspression):#   ,       ,    
        list_expression = self.get_list_expression(exspression)
        stack = Stack()  #     
        for ele in list_expression:  #         
            if ele.replace('.','').isdigit():  #       
                stack.push(ele)
            else:  #         ,     ,     
                ret = self.operation(ele, float(stack.pop()), float(stack.pop()))
                stack.push(ret)
        return '%.2f'% stack.pop()#    

    def operation(self,sign, num2, num1):  #     
        if sign == '*':
            return num1 * num2
        if sign == '/':

            return num1/num2
        if sign == '+':
            return num1 + num2
        if sign == '-':
            return num1 - num2

    def deal_str(self,exspression):#          ,          
        status = 0
        res = ''
        exspression = exspression.strip().replace(' ','')
        for ele in exspression:
            if ele.isdigit() or ele =='.':
                if status == 1:
                    res =res.strip(' ')
                    res = res + ele + ' '
                else:
                    status = 1
                    res= res+ele+' '
            else:
                status = 0
                res = res + ele + ' '
        return res.strip().split(' ')

    def get_list_expression(self,exspression):#             
        lst = self.deal_str(exspression)
        s1 = Stack()
        s2 = Stack()
        for ele in lst:
            if ele.replace('.','').isdigit():
                s2.push(ele)
            else:
                self.deal_symbol(ele,s1,s2)
        while not s1.is_empty():
            s2.push(s1.pop())
        res = []
        while not s2.is_empty():
            res.append(s2.pop())
        return res[::-1]

    def deal_symbol(self,ele,s1,s2):#          
        if s1.is_empty() or s1.top() == '(' or ele == '(':
            s1.push(ele)
        elif ele == ')':
            while s1.top() != '(':
                s2.push(s1.pop())
            s1.pop()
        elif self.get_priority(ele) > self.get_priority(s1.top()):
            s1.push(ele)
        else:
            s2.push(s1.pop())
            self.deal_symbol(ele,s1,s2)

    def get_priority(self,sign):#       
        if sign=='*' or sign=='/':
            return 2
        elif sign=='+' or sign=='-':
            return 1



if __name__ == '__main__':
    exspression = input('       :')
    Calculator = InversPolishCalculator()
    ret = Calculator.deal(exspression)
    print('    :',ret)
    input()