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      1 """Python 'zlib_codec' Codec - zlib compression encoding.
      2 
      3 This codec de/encodes from bytes to bytes.
      4 
      5 Written by Marc-Andre Lemburg (mal (at] lemburg.com).
      6 """
      7 
      8 import codecs
      9 import zlib # this codec needs the optional zlib module !
     10 
     11 ### Codec APIs
     12 
     13 def zlib_encode(input, errors='strict'):
     14     assert errors == 'strict'
     15     return (zlib.compress(input), len(input))
     16 
     17 def zlib_decode(input, errors='strict'):
     18     assert errors == 'strict'
     19     return (zlib.decompress(input), len(input))
     20 
     21 class Codec(codecs.Codec):
     22     def encode(self, input, errors='strict'):
     23         return zlib_encode(input, errors)
     24     def decode(self, input, errors='strict'):
     25         return zlib_decode(input, errors)
     26 
     27 class IncrementalEncoder(codecs.IncrementalEncoder):
     28     def __init__(self, errors='strict'):
     29         assert errors == 'strict'
     30         self.errors = errors
     31         self.compressobj = zlib.compressobj()
     32 
     33     def encode(self, input, final=False):
     34         if final:
     35             c = self.compressobj.compress(input)
     36             return c + self.compressobj.flush()
     37         else:
     38             return self.compressobj.compress(input)
     39 
     40     def reset(self):
     41         self.compressobj = zlib.compressobj()
     42 
     43 class IncrementalDecoder(codecs.IncrementalDecoder):
     44     def __init__(self, errors='strict'):
     45         assert errors == 'strict'
     46         self.errors = errors
     47         self.decompressobj = zlib.decompressobj()
     48 
     49     def decode(self, input, final=False):
     50         if final:
     51             c = self.decompressobj.decompress(input)
     52             return c + self.decompressobj.flush()
     53         else:
     54             return self.decompressobj.decompress(input)
     55 
     56     def reset(self):
     57         self.decompressobj = zlib.decompressobj()
     58 
     59 class StreamWriter(Codec, codecs.StreamWriter):
     60     charbuffertype = bytes
     61 
     62 class StreamReader(Codec, codecs.StreamReader):
     63     charbuffertype = bytes
     64 
     65 ### encodings module API
     66 
     67 def getregentry():
     68     return codecs.CodecInfo(
     69         name='zlib',
     70         encode=zlib_encode,
     71         decode=zlib_decode,
     72         incrementalencoder=IncrementalEncoder,
     73         incrementaldecoder=IncrementalDecoder,
     74         streamreader=StreamReader,
     75         streamwriter=StreamWriter,
     76         _is_text_encoding=False,
     77     )
     78