Lib/encodings/bz2_codec.py

   1 """ Python 'bz2_codec' Codec - bz2 compression encoding
   2
   3     Unlike most of the other codecs which target Unicode, this codec
   4     will return Python string objects for both encode and decode.
   5
   6     Adapted by Raymond Hettinger from zlib_codec.py which was written
   7     by Marc-Andre Lemburg (mal@lemburg.com).
   8
   9 """
  10 import codecs
  11 import bz2 # this codec needs the optional bz2 module !
  12
  13 ### Codec APIs
  14
  15 def bz2_encode(input,errors='strict'):
  16
  17     """ Encodes the object input and returns a tuple (output
  18         object, length consumed).
  19
  20         errors defines the error handling to apply. It defaults to
  21         'strict' handling which is the only currently supported
  22         error handling for this codec.
  23
  24     """
  25     assert errors == 'strict'
  26     output = bz2.compress(input)
  27     return (output, len(input))
  28
  29 def bz2_decode(input,errors='strict'):
  30
  31     """ Decodes the object input and returns a tuple (output
  32         object, length consumed).
  33
  34         input must be an object which provides the bf_getreadbuf
  35         buffer slot. Python strings, buffer objects and memory
  36         mapped files are examples of objects providing this slot.
  37
  38         errors defines the error handling to apply. It defaults to
  39         'strict' handling which is the only currently supported
  40         error handling for this codec.
  41
  42     """
  43     assert errors == 'strict'
  44     output = bz2.decompress(input)
  45     return (output, len(input))
  46
  47 class Codec(codecs.Codec):
  48
  49     def encode(self, input, errors='strict'):
  50         return bz2_encode(input, errors)
  51     def decode(self, input, errors='strict'):
  52         return bz2_decode(input, errors)
  53
  54 class IncrementalEncoder(codecs.IncrementalEncoder):
  55     def __init__(self, errors='strict'):
  56         assert errors == 'strict'
  57         self.errors = errors
  58         self.compressobj = bz2.BZ2Compressor()
  59
  60     def encode(self, input, final=False):
  61         if final:
  62             c = self.compressobj.compress(input)
  63             return c + self.compressobj.flush()
  64         else:
  65             return self.compressobj.compress(input)
  66
  67     def reset(self):
  68         self.compressobj = bz2.BZ2Compressor()
  69
  70 class IncrementalDecoder(codecs.IncrementalDecoder):
  71     def __init__(self, errors='strict'):
  72         assert errors == 'strict'
  73         self.errors = errors
  74         self.decompressobj = bz2.BZ2Decompressor()
  75
  76     def decode(self, input, final=False):
  77         try:
  78             return self.decompressobj.decompress(input)
  79         except EOFError:
  80             return ''
  81
  82     def reset(self):
  83         self.decompressobj = bz2.BZ2Decompressor()
  84
  85 class StreamWriter(Codec,codecs.StreamWriter):
  86     pass
  87
  88 class StreamReader(Codec,codecs.StreamReader):
  89     pass
  90
  91 ### encodings module API
  92
  93 def getregentry():
  94     return codecs.CodecInfo(
  95         name="bz2",
  96         encode=bz2_encode,
  97         decode=bz2_decode,
  98         incrementalencoder=IncrementalEncoder,
  99         incrementaldecoder=IncrementalDecoder,
 100         streamwriter=StreamWriter,
 101         streamreader=StreamReader,
 102     )