Issue #27959: Adds oem encoding, alias ansi to mbcs, move aliasmbcs to codec lookup

Lib/encodings/oem.py

@@ -0,0 +1,41 @@
+""" Python 'oem' Codec for Windows
+
+"""
+# Import them explicitly to cause an ImportError
+# on non-Windows systems
+from codecs import oem_encode, oem_decode
+# for IncrementalDecoder, IncrementalEncoder, ...
+import codecs
+
+### Codec APIs
+
+encode = oem_encode
+
+def decode(input, errors='strict'):
+    return oem_decode(input, errors, True)
+
+class IncrementalEncoder(codecs.IncrementalEncoder):
+    def encode(self, input, final=False):
+        return oem_encode(input, self.errors)[0]
+
+class IncrementalDecoder(codecs.BufferedIncrementalDecoder):
+    _buffer_decode = oem_decode
+
+class StreamWriter(codecs.StreamWriter):
+    encode = oem_encode
+
+class StreamReader(codecs.StreamReader):
+    decode = oem_decode
+
+### encodings module API
+
+def getregentry():
+    return codecs.CodecInfo(
+        name='oem',
+        encode=encode,
+        decode=decode,
+        incrementalencoder=IncrementalEncoder,
+        incrementaldecoder=IncrementalDecoder,
+        streamreader=StreamReader,
+        streamwriter=StreamWriter,
+    )