Python实现解析Bit Torrent种子文件内容的方法

import re
def tokenize(text, match=re.compile("([idel])|(/d+):|(-?/d+)").match):
 i = 0
 while i < len(text):
  m = match(text, i)
  s = m.group(m.lastindex)
  i = m.end()
  if m.lastindex == 2:
   yield "s"
   yield text[i:i+int(s)]
   i = i + int(s)
  else:
   yield s
def decode_item(next, token):
 if token == "i":
  # integer: "i" value "e"
  data = int(next())
  if next() != "e":
   raise ValueError
 elif token == "s":
  # string: "s" value (virtual tokens)
  data = next()
 elif token == "l" or token == "d":
  # Container: "l" (or "d") values "e"
  data = []
  tok = next()
  while tok != "e":
   data.append(decode_item(next, tok))
   tok = next()
  if token == "d":
   data = dict(zip(data[0::2], data[1::2]))
 else:
  raise ValueError
 return data
def decode(text):
 try:
  src = tokenize(text)
  data = decode_item(src.next, src.next())
  for token in src: # look for more tokens
   raise SyntaxError("trailing junk")
 except (AttributeError, ValueError, StopIteration):
  raise SyntaxError("syntax error")
 return data
if __name__ == "__main__":
#需要读取的文件名称放到这里
 data = open("The_Shawshank_Redemption.torrent", "rb").read()
 torrent = decode(data)
 myfile = file("testit.txt", 'w')
 a = u'文件名称'.encode('gbk')
 b = u'文件大小'.encode('gbk')
 print "%s /t %s /n" % (a,b)
 for file in torrent["info"]["files"]:
  print "%s /t %d Mb " % ("/".join(file["path"]), file["length"]/1024/1024)
  print "-----------------------------------------------------------------"