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     )