Infix To Postfix + Evaluasi

Infix To Postfix pada Python

from __future__ import print_function

class Stack:

    def __init__(self):

        self.items = []

    def isEmpty(self):

        return self.items==[]

    def push(self,items):

        self.items.append(items)

    def pop(self):

        return self.items.pop()

    def peek(self):

        return self.items[len(self.items)-1]

    def size(self):

        return len(self.items)

def infixToPostfix(infixexpr):

    prec = {}

    prec["*"] = 3

    prec["/"] = 3

    prec["+"] = 2

    prec["-"] = 2

    prec["("] = 1

    opStack = Stack()

    postfixList = []

    tokenList = infixexpr.split()  

    print (tokenList)

    for token in tokenList:

        if token in "ABCDEFGHIJKLMNOPQRSTUVWXYZ" or token in "0123456789":

            postfixList.append(token)

        elif token == '(':

            opStack.push(token)

        elif token == ')':

            topToken = opStack.pop()

            while topToken != '(':

                postfixList.append(topToken)

                topToken = opStack.pop()

        else:

            while (not opStack.isEmpty()) and (prec[opStack.peek()] >= prec[token]) :

                postfixList.append(opStack.pop())

            opStack.push(token)

    while not opStack.isEmpty():

        postfixList.append(opStack.pop())

    return " ".join(postfixList)

def postfixEval(postfixExpr):

    operandStack = Stack()

    tokenList = postfixExpr.split()

    for token in tokenList:

        if token in "0123456789":

            operandStack.push(int(token))

        else:

            operand2 = operandStack.pop()

            operand1 = operandStack.pop()

            result = doMath(token,operand1,operand2)

            operandStack.push(result)

    return operandStack.pop()

def doMath(op, op1, op2):

    if op == "*":

        return op1 * op2

    elif op == "/":

        return op1 / op2

    elif op == "+":

        return op1 + op2

    else:

        return op1 - op2

# Infix To Postfix

data = input("Masukan Infix (Dalam bentuk String dan tambahan spasi): ")

postfix = infixToPostfix(data)

print (postfix)

# Postfix Evaluasi

data2 = input("Masukan Postfix (Dalam bentuk Angka dan tambahan spasi): ")

infix = postfixEval(data2)

print (infix)