1 import sys
   2 import re
   3 
   4 # Variables
   5 arq = None
   6 top = 30000
   7 ptr = 0
   8 cou = 0
   9 src = ''
  10 
  11 segment = [0 for i in range(top)]
  12 loops = []
  13 
  14 # Opening the file
  15 if len(sys.argv) < 2:
  16         print "Usage: mybf.py myscript.bf"
  17         sys.exit(1)
  18 else:
  19         try:
  20                 arq = open(sys.argv[1], 'r')
  21                 src = ''.join(arq.readlines())
  22                 arq.close()
  23                 del arq
  24         except Exception, e:
  25                 print "Can't read the specifyed script."
  26                 sys.exit(1)
  27                 
  28 # Eliminating non-bf characters
  29 src = re.sub('[^\+\-\.\[\],<>]', '', src);
  30 
  31 # Verifyig the brackets equivalency
  32 (lbrackets, rbrackets) = (src.count('['), src.count(']'))
  33 if lbrackets != rbrackets:
  34         print "Missing brackets -> ([: %d | ]: %d)" % (lbrackets, rbrackets)
  35         sys.exit(1)
  36         
  37 # Execution loop
  38 while cou < len(src):
  39         ch = src[cou]
  40         cou += 1
  41         
  42         if ch == '+':
  43                 segment[ptr] += 1
  44                 if segment[ptr] > 256: segment[ptr] = 0
  45         
  46         if ch == '-':
  47                 segment[ptr] -= 1
  48                 if segment[ptr] < 0: segment[ptr] = 256
  49         
  50         if ch == '>':
  51                 ptr += 1
  52                 if ptr == top: ptr = 0
  53         
  54         if ch == '<':
  55                 ptr -= 1
  56                 if ptr < 0: ptr = top-1
  57         
  58         if ch == ',':
  59                 tmp = raw_input()
  60                 if tmp: segment[ptr] = ord(tmp[0])
  61         
  62         if ch == '.':
  63                 print chr(segment[ptr]),
  64         
  65         if ch == '[':
  66                 loops.append(cou)
  67         
  68         if ch == ']':
  69                 if segment[ptr] != 0:
  70                         cou = loops[len(loops) - 1]
  71                 else:
  72                         loops.pop()