| """ Python 'zlib_codec' Codec - zlib compression encoding | |
| Unlike most of the other codecs which target Unicode, this codec | |
| will return Python string objects for both encode and decode. | |
| Written by Marc-Andre Lemburg (mal@lemburg.com). | |
| """ | |
| import codecs | |
| import zlib # this codec needs the optional zlib module ! | |
| ### Codec APIs | |
| def zlib_encode(input,errors='strict'): | |
| """ Encodes the object input and returns a tuple (output | |
| object, length consumed). | |
| errors defines the error handling to apply. It defaults to | |
| 'strict' handling which is the only currently supported | |
| error handling for this codec. | |
| """ | |
| assert errors == 'strict' | |
| output = zlib.compress(input) | |
| return (output, len(input)) | |
| def zlib_decode(input,errors='strict'): | |
| """ Decodes the object input and returns a tuple (output | |
| object, length consumed). | |
| input must be an object which provides the bf_getreadbuf | |
| buffer slot. Python strings, buffer objects and memory | |
| mapped files are examples of objects providing this slot. | |
| errors defines the error handling to apply. It defaults to | |
| 'strict' handling which is the only currently supported | |
| error handling for this codec. | |
| """ | |
| assert errors == 'strict' | |
| output = zlib.decompress(input) | |
| return (output, len(input)) | |
| class Codec(codecs.Codec): | |
| def encode(self, input, errors='strict'): | |
| return zlib_encode(input, errors) | |
| def decode(self, input, errors='strict'): | |
| return zlib_decode(input, errors) | |
| class IncrementalEncoder(codecs.IncrementalEncoder): | |
| def __init__(self, errors='strict'): | |
| assert errors == 'strict' | |
| self.errors = errors | |
| self.compressobj = zlib.compressobj() | |
| def encode(self, input, final=False): | |
| if final: | |
| c = self.compressobj.compress(input) | |
| return c + self.compressobj.flush() | |
| else: | |
| return self.compressobj.compress(input) | |
| def reset(self): | |
| self.compressobj = zlib.compressobj() | |
| class IncrementalDecoder(codecs.IncrementalDecoder): | |
| def __init__(self, errors='strict'): | |
| assert errors == 'strict' | |
| self.errors = errors | |
| self.decompressobj = zlib.decompressobj() | |
| def decode(self, input, final=False): | |
| if final: | |
| c = self.decompressobj.decompress(input) | |
| return c + self.decompressobj.flush() | |
| else: | |
| return self.decompressobj.decompress(input) | |
| def reset(self): | |
| self.decompressobj = zlib.decompressobj() | |
| class StreamWriter(Codec,codecs.StreamWriter): | |
| pass | |
| class StreamReader(Codec,codecs.StreamReader): | |
| pass | |
| ### encodings module API | |
| def getregentry(): | |
| return codecs.CodecInfo( | |
| name='zlib', | |
| encode=zlib_encode, | |
| decode=zlib_decode, | |
| incrementalencoder=IncrementalEncoder, | |
| incrementaldecoder=IncrementalDecoder, | |
| streamreader=StreamReader, | |
| streamwriter=StreamWriter, | |
| ) |