CALCULATRICE LIGNE DE COMMANDE - CALCUL EXACT

from fractions import *
import sys

sys.setrecursionlimit(5000) # profondeur maximal des recusions

def gestion_nb_virgule(chaine):
 chaine_finale = ""
 num = ""
 denum = ""
 for elem in chaine:
  if elem == ".":
   num = denum
   denum = ""
  elif elem in ("+","-","/","*"):
   if num and denum:
    if chaine_finale:
     if chaine_finale[-1] == "/":
      chaine_finale = chaine_finale[:-1]+"*"
      chaine_finale += str(1/Fraction(num+"."+denum))+elem
      denum = num = ""
    else:
     chaine_finale += str(Fraction(num+"."+denum))+elem
     denum = num = ""
   else:
    chaine_finale += denum + elem
    denum = num = ""
  else:
   denum += elem
 if num and denum:
  if chaine_finale:
   if chaine_finale[-1] == "/":
    chaine_finale = chaine_finale[:-1]+"*"
    chaine_finale += str(1/Fraction(num+"."+denum))
    denum = num = ""
   else:
    chaine_finale += str(Fraction(num+"."+denum))
    denum = num = ""
  else:
   chaine_finale += str(Fraction(num+"."+denum))
   denum = num = ""
 else:
  chaine_finale += denum
  denum = num = ""
 return chaine_finale

# Le programme utilise la recursivite pour calculer

def exacalc(chaine):

 if "+" in chaine: # ADDITION OU SOUSTRACTION OU MULTIPLICATIONS OU DIVISIONS
  for rang, operation in enumerate(chaine.split("+")):
   if rang == 0: # 1ER NOMBRE
    if ("-" in operation) and (operation[0]!="-") :
     resultat = exacalc(operation)
    if "*" in operation:
     resultat = exacalc(operation)
    if "/" in operation:
     resultat = exacalc(operation)
    else:
     resultat = operation
   else:
    if "-" in operation:
     operation = exacalc(operation)
    if "*" in operation:
     operation = exacalc(operation)
    if "/" in operation:
     operation = exacalc(operation)

    if "/" not in resultat:
     resultat += "/1"
    if "/" not in operation:
     operation += "/1"
    resultat = resultat.split("/") 
    operation = operation.split("/")
    resultat = str(Fraction(int(resultat[0]),int(resultat[1]))+Fraction(int(operation[0]),int(operation[1])))

 elif ("-" in chaine) and (chaine[0]!="-") : # SOUSTRACTION OU MULTIPLICATIONS OU DIVISIONS
  for rang, operation in enumerate(chaine.split("-")):
   if rang == 0: # 1ER NOMBRE
    if "*" in operation:
     resultat = exacalc(operation)
    if "/" in operation:
     resultat = exacalc(operation)
    else:
     resultat = operation
   else:
    if "*" in operation:
     operation = exacalc(operation)
    if "/" in operation:
     operation = exacalc(operation)

    if "/" not in resultat:
     resultat += "/1"
    if "/" not in operation:
     operation += "/1"
    resultat = resultat.split("/") 
    operation = operation.split("/")
    resultat = str(Fraction(int(resultat[0]),int(resultat[1]))-Fraction(int(operation[0]),int(operation[1])))
    if( resultat[0]=="0") and ("/" in resultat):
     resultat = 0

 elif "*" in chaine: # MULTIPLICATIONS OU DIVISIONS
  for rang, operation in enumerate(chaine.split("*")):
   if rang == 0: # 1ER NOMBRE
    if "/" in operation: # DIVISION
     resultat = exacalc(operation)
    else:
     resultat = operation
   else:
    if "/" not in resultat:
     resultat += "/1"
    if "/" not in operation:
     operation += "/1"
    resultat = resultat.split("/") 
    operation = operation.split("/")
    resultat = str(Fraction(int(resultat[0]),int(resultat[1]))*Fraction(int(operation[0]),int(operation[1])))
	  
 elif "/" in chaine: # QUE DES DIVISIONS
  for rang, operation in enumerate(chaine.split("/")):
   if rang == 0:
    resultat = operation
   elif rang == 1:
    resultat += "/"+operation
   else: # divisions suivantes
    resultat = resultat.split("/")
    resultat = str(Fraction(int(resultat[0]),int(resultat[1]))/Fraction(int(operation),1))

 if "/" in resultat:
  resultat = resultat.split("/")
  return str(Fraction(int(resultat[0]),int(resultat[1])))
 
 else:
  return resultat

while 1:
 saisie = raw_input("\nexacalc : ")
 saisie = saisie.replace(" ","")
 saisie = saisie.replace("++","+")
 saisie = saisie.replace("--","+")
 saisie = saisie.replace("+-","-")
 saisie = saisie.replace("-+","-")
 saisie = saisie.replace("**","*")
 saisie = saisie.replace("\\","/") # attention "\\" correspond a "\"
 saisie = saisie.replace("//","/")
 saisie = saisie.replace(",",".")
 
 # ICI DEBUG
 # if saisie and ("+" in saisie)or("-" in saisie)or("*" in saisie)or("/" in saisie):
  # print " ", exacalc(gestion_nb_virgule(saisie))
 
 # ICI ANTI-ERREUR
 if saisie and ("+" in saisie)or("-" in saisie)or("*" in saisie)or("/" in saisie):
  try:
   saisie = gestion_nb_virgule(saisie)
   resultat = exacalc(saisie)
   print " ", resultat
   if "/" in resultat:
    print " ", float(resultat.split("/")[0])/float(resultat.split("/")[1])
  except:
   print "erreur de syntaxe"