1 files changed, 113 insertions, 0 deletions
diff --git a/Lib/encodings/rot_13.py b/Lib/encodings/rot_13.py
new file mode 100755
index 00000000000..3140c1432dc
--- /dev/null
+++ b/Lib/encodings/rot_13.py
@@ -0,0 +1,113 @@
+#!/usr/bin/env python
+""" Python Character Mapping Codec for ROT13.
+
+This codec de/encodes from str to str and is therefore usable with
+str.transform() and str.untransform().
+
+Written by Marc-Andre Lemburg (mal@lemburg.com).
+"""
+
+import codecs
+
+### Codec APIs
+
+class Codec(codecs.Codec):
+    def encode(self, input, errors='strict'):
+        return (input.translate(rot13_map), len(input))
+
+    def decode(self, input, errors='strict'):
+        return (input.translate(rot13_map), len(input))
+
+class IncrementalEncoder(codecs.IncrementalEncoder):
+    def encode(self, input, final=False):
+        return input.translate(rot13_map)
+
+class IncrementalDecoder(codecs.IncrementalDecoder):
+    def decode(self, input, final=False):
+        return input.translate(rot13_map)
+
+class StreamWriter(Codec,codecs.StreamWriter):
+    pass
+
+class StreamReader(Codec,codecs.StreamReader):
+    pass
+
+### encodings module API
+
+def getregentry():
+    return codecs.CodecInfo(
+        name='rot-13',
+        encode=Codec().encode,
+        decode=Codec().decode,
+        incrementalencoder=IncrementalEncoder,
+        incrementaldecoder=IncrementalDecoder,
+        streamwriter=StreamWriter,
+        streamreader=StreamReader,
+    )
+
+### Map
+
+rot13_map = codecs.make_identity_dict(range(256))
+rot13_map.update({
+   0x0041: 0x004e,
+   0x0042: 0x004f,
+   0x0043: 0x0050,
+   0x0044: 0x0051,
+   0x0045: 0x0052,
+   0x0046: 0x0053,
+   0x0047: 0x0054,
+   0x0048: 0x0055,
+   0x0049: 0x0056,
+   0x004a: 0x0057,
+   0x004b: 0x0058,
+   0x004c: 0x0059,
+   0x004d: 0x005a,
+   0x004e: 0x0041,
+   0x004f: 0x0042,
+   0x0050: 0x0043,
+   0x0051: 0x0044,
+   0x0052: 0x0045,
+   0x0053: 0x0046,
+   0x0054: 0x0047,
+   0x0055: 0x0048,
+   0x0056: 0x0049,
+   0x0057: 0x004a,
+   0x0058: 0x004b,
+   0x0059: 0x004c,
+   0x005a: 0x004d,
+   0x0061: 0x006e,
+   0x0062: 0x006f,
+   0x0063: 0x0070,
+   0x0064: 0x0071,
+   0x0065: 0x0072,
+   0x0066: 0x0073,
+   0x0067: 0x0074,
+   0x0068: 0x0075,
+   0x0069: 0x0076,
+   0x006a: 0x0077,
+   0x006b: 0x0078,
+   0x006c: 0x0079,
+   0x006d: 0x007a,
+   0x006e: 0x0061,
+   0x006f: 0x0062,
+   0x0070: 0x0063,
+   0x0071: 0x0064,
+   0x0072: 0x0065,
+   0x0073: 0x0066,
+   0x0074: 0x0067,
+   0x0075: 0x0068,
+   0x0076: 0x0069,
+   0x0077: 0x006a,
+   0x0078: 0x006b,
+   0x0079: 0x006c,
+   0x007a: 0x006d,
+})
+
+### Filter API
+
+def rot13(infile, outfile):
+    outfile.write(infile.read().encode('rot-13'))
+
+if __name__ == '__main__':
+    import sys
+    rot13(sys.stdin, sys.stdout)