1#!/usr/bin/env python
2""" Python Character Mapping Codec for ROT13.
3
4This codec de/encodes from str to str.
5
6Written by Marc-Andre Lemburg (mal@lemburg.com).
7"""
8
9import codecs
10
11### Codec APIs
12
13class Codec(codecs.Codec):
14    def encode(self, input, errors='strict'):
15        return (str.translate(input, rot13_map), len(input))
16
17    def decode(self, input, errors='strict'):
18        return (str.translate(input, rot13_map), len(input))
19
20class IncrementalEncoder(codecs.IncrementalEncoder):
21    def encode(self, input, final=False):
22        return str.translate(input, rot13_map)
23
24class IncrementalDecoder(codecs.IncrementalDecoder):
25    def decode(self, input, final=False):
26        return str.translate(input, rot13_map)
27
28class StreamWriter(Codec,codecs.StreamWriter):
29    pass
30
31class StreamReader(Codec,codecs.StreamReader):
32    pass
33
34### encodings module API
35
36def getregentry():
37    return codecs.CodecInfo(
38        name='rot-13',
39        encode=Codec().encode,
40        decode=Codec().decode,
41        incrementalencoder=IncrementalEncoder,
42        incrementaldecoder=IncrementalDecoder,
43        streamwriter=StreamWriter,
44        streamreader=StreamReader,
45        _is_text_encoding=False,
46    )
47
48### Map
49
50rot13_map = codecs.make_identity_dict(range(256))
51rot13_map.update({
52   0x0041: 0x004e,
53   0x0042: 0x004f,
54   0x0043: 0x0050,
55   0x0044: 0x0051,
56   0x0045: 0x0052,
57   0x0046: 0x0053,
58   0x0047: 0x0054,
59   0x0048: 0x0055,
60   0x0049: 0x0056,
61   0x004a: 0x0057,
62   0x004b: 0x0058,
63   0x004c: 0x0059,
64   0x004d: 0x005a,
65   0x004e: 0x0041,
66   0x004f: 0x0042,
67   0x0050: 0x0043,
68   0x0051: 0x0044,
69   0x0052: 0x0045,
70   0x0053: 0x0046,
71   0x0054: 0x0047,
72   0x0055: 0x0048,
73   0x0056: 0x0049,
74   0x0057: 0x004a,
75   0x0058: 0x004b,
76   0x0059: 0x004c,
77   0x005a: 0x004d,
78   0x0061: 0x006e,
79   0x0062: 0x006f,
80   0x0063: 0x0070,
81   0x0064: 0x0071,
82   0x0065: 0x0072,
83   0x0066: 0x0073,
84   0x0067: 0x0074,
85   0x0068: 0x0075,
86   0x0069: 0x0076,
87   0x006a: 0x0077,
88   0x006b: 0x0078,
89   0x006c: 0x0079,
90   0x006d: 0x007a,
91   0x006e: 0x0061,
92   0x006f: 0x0062,
93   0x0070: 0x0063,
94   0x0071: 0x0064,
95   0x0072: 0x0065,
96   0x0073: 0x0066,
97   0x0074: 0x0067,
98   0x0075: 0x0068,
99   0x0076: 0x0069,
100   0x0077: 0x006a,
101   0x0078: 0x006b,
102   0x0079: 0x006c,
103   0x007a: 0x006d,
104})
105
106### Filter API
107
108def rot13(infile, outfile):
109    outfile.write(codecs.encode(infile.read(), 'rot-13'))
110
111if __name__ == '__main__':
112    import sys
113    rot13(sys.stdin, sys.stdout)
114