Calculadora de expressao

expcalc.py

#enconding: utf-8
'''
Calculadora de expressao

testes:
2+2 = 4
2-2 = 0
2*2 = 4
2/2 = 1
2^2 = 4

2+2-5 = -1

(2-2)*5 = 0
2-2*5 = -8

6+(10/2-3*(4-1)) = 2 
'''

import unittest

def split(s, op):
	i = s.find(op)
	a = s[0:i]
	b = s[i+1:]
	return a, b

def calc(s):
	import re
	if '(' in s:
		ie = re.match(r'\(([^)]+)', s)
		if ie:
			ie = ie.group().replace('(', '')
			iec = calc(ie)
			s = s.replace('('+ie+')', str(iec)).replace('(', '').replace(')', '')
			print 'iec',iec
			print 's',s
	if '+' in s:
		a, b = split(s, '+')
		return calc(a)+calc(b)
	elif '-' in s:
		a, b = split(s, '-')
		return calc(a)-calc(b)
	elif '/' in s:
		a, b = split(s, '/')
		return calc(a)/calc(b)
	elif '*' in s:
		a, b = split(s, '*')
		return calc(a)*calc(b)
	elif '^' in s:
		a, b = split(s, '^')
		return calc(a)**calc(b)
	return int(s)

class Calculadora(unittest.TestCase):
	def test_2_mais_2_igl_4(self):
		self.assertEquals(calc('2+2'), 4)
	def test_2_menos_2_igl_0(self):
		self.assertEquals(calc('2-2'), 0)
	def test_2_vezes_2_igl_4(self):
		self.assertEquals(calc('2*2'), 4)
	def test_2_dividido_2_igl_4(self):
		self.assertEquals(calc('2/2'), 1)
	def test_2_potenciacao_2_igl_4(self):
		self.assertEquals(calc('2^2'), 4)
	def test_7_mai_2_igl_9(self):
		self.assertEquals(calc('7+2'), 9)
	def test_2_mai_2_men_5_igl_n1(self):
		self.assertEquals(calc('2+2-5'), -1)
	def test_2_vezes_3_men_10_igl_n4(self):
		self.assertEquals(calc('2*3-10'), -4)
	def test_p2_menos_2p_vezes_5_igl_0(self):
		self.assertEquals(calc('(2-2)*5'), 0)
	def test_cabulosa(self):
		self.assertEquals(calc('6+(10-2-3+(4-1))'),14)
		

unittest.main()