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      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 (at] 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     )
    103