Lib/encodings/rot_13.py

   1 #!/usr/bin/env python
   2 """ Python Character Mapping Codec for ROT13.
   3
   4     See http://ucsub.colorado.edu/~kominek/rot13/ for details.
   5
   6     Written by Marc-Andre Lemburg (mal@lemburg.com).
   7
   8 """#"
   9
  10 import codecs
  11
  12 ### Codec APIs
  13
  14 class Codec(codecs.Codec):
  15
  16     def encode(self,input,errors='strict'):
  17         return codecs.charmap_encode(input,errors,encoding_map)
  18
  19     def decode(self,input,errors='strict'):
  20         return codecs.charmap_decode(input,errors,decoding_map)
  21
  22 class IncrementalEncoder(codecs.IncrementalEncoder):
  23     def encode(self, input, final=False):
  24         return codecs.charmap_encode(input,self.errors,encoding_map)[0]
  25
  26 class IncrementalDecoder(codecs.IncrementalDecoder):
  27     def decode(self, input, final=False):
  28         return codecs.charmap_decode(input,self.errors,decoding_map)[0]
  29
  30 class StreamWriter(Codec,codecs.StreamWriter):
  31     pass
  32
  33 class StreamReader(Codec,codecs.StreamReader):
  34     pass
  35
  36 ### encodings module API
  37
  38 def getregentry():
  39     return codecs.CodecInfo(
  40         name='rot-13',
  41         encode=Codec().encode,
  42         decode=Codec().decode,
  43         incrementalencoder=IncrementalEncoder,
  44         incrementaldecoder=IncrementalDecoder,
  45         streamwriter=StreamWriter,
  46         streamreader=StreamReader,
  47     )
  48
  49 ### Decoding Map
  50
  51 decoding_map = codecs.make_identity_dict(range(256))
  52 decoding_map.update({
  53    0x0041: 0x004e,
  54    0x0042: 0x004f,
  55    0x0043: 0x0050,
  56    0x0044: 0x0051,
  57    0x0045: 0x0052,
  58    0x0046: 0x0053,
  59    0x0047: 0x0054,
  60    0x0048: 0x0055,
  61    0x0049: 0x0056,
  62    0x004a: 0x0057,
  63    0x004b: 0x0058,
  64    0x004c: 0x0059,
  65    0x004d: 0x005a,
  66    0x004e: 0x0041,
  67    0x004f: 0x0042,
  68    0x0050: 0x0043,
  69    0x0051: 0x0044,
  70    0x0052: 0x0045,
  71    0x0053: 0x0046,
  72    0x0054: 0x0047,
  73    0x0055: 0x0048,
  74    0x0056: 0x0049,
  75    0x0057: 0x004a,
  76    0x0058: 0x004b,
  77    0x0059: 0x004c,
  78    0x005a: 0x004d,
  79    0x0061: 0x006e,
  80    0x0062: 0x006f,
  81    0x0063: 0x0070,
  82    0x0064: 0x0071,
  83    0x0065: 0x0072,
  84    0x0066: 0x0073,
  85    0x0067: 0x0074,
  86    0x0068: 0x0075,
  87    0x0069: 0x0076,
  88    0x006a: 0x0077,
  89    0x006b: 0x0078,
  90    0x006c: 0x0079,
  91    0x006d: 0x007a,
  92    0x006e: 0x0061,
  93    0x006f: 0x0062,
  94    0x0070: 0x0063,
  95    0x0071: 0x0064,
  96    0x0072: 0x0065,
  97    0x0073: 0x0066,
  98    0x0074: 0x0067,
  99    0x0075: 0x0068,
 100    0x0076: 0x0069,
 101    0x0077: 0x006a,
 102    0x0078: 0x006b,
 103    0x0079: 0x006c,
 104    0x007a: 0x006d,
 105 })
 106
 107 ### Encoding Map
 108
 109 encoding_map = codecs.make_encoding_map(decoding_map)
 110
 111 ### Filter API
 112
 113 def rot13(infile, outfile):
 114     outfile.write(infile.read().encode('rot-13'))
 115
 116 if __name__ == '__main__':
 117     import sys
 118     rot13(sys.stdin, sys.stdout)