1""" Python 'zlib_codec' Codec - zlib 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    Written by Marc-Andre Lemburg (mal@lemburg.com).
7
8"""
9import codecs
10import zlib # this codec needs the optional zlib module !
11
12### Codec APIs
13
14def zlib_encode(input,errors='strict'):
15
16    """ Encodes the object input and returns a tuple (output
17        object, length consumed).
18
19        errors defines the error handling to apply. It defaults to
20        'strict' handling which is the only currently supported
21        error handling for this codec.
22
23    """
24    assert errors == 'strict'
25    output = zlib.compress(input)
26    return (output, len(input))
27
28def zlib_decode(input,errors='strict'):
29
30    """ Decodes the object input and returns a tuple (output
31        object, length consumed).
32
33        input must be an object which provides the bf_getreadbuf
34        buffer slot. Python strings, buffer objects and memory
35        mapped files are examples of objects providing this slot.
36
37        errors defines the error handling to apply. It defaults to
38        'strict' handling which is the only currently supported
39        error handling for this codec.
40
41    """
42    assert errors == 'strict'
43    output = zlib.decompress(input)
44    return (output, len(input))
45
46class Codec(codecs.Codec):
47
48    def encode(self, input, errors='strict'):
49        return zlib_encode(input, errors)
50    def decode(self, input, errors='strict'):
51        return zlib_decode(input, errors)
52
53class IncrementalEncoder(codecs.IncrementalEncoder):
54    def __init__(self, errors='strict'):
55        assert errors == 'strict'
56        self.errors = errors
57        self.compressobj = zlib.compressobj()
58
59    def encode(self, input, final=False):
60        if final:
61            c = self.compressobj.compress(input)
62            return c + self.compressobj.flush()
63        else:
64            return self.compressobj.compress(input)
65
66    def reset(self):
67        self.compressobj = zlib.compressobj()
68
69class IncrementalDecoder(codecs.IncrementalDecoder):
70    def __init__(self, errors='strict'):
71        assert errors == 'strict'
72        self.errors = errors
73        self.decompressobj = zlib.decompressobj()
74
75    def decode(self, input, final=False):
76        if final:
77            c = self.decompressobj.decompress(input)
78            return c + self.decompressobj.flush()
79        else:
80            return self.decompressobj.decompress(input)
81
82    def reset(self):
83        self.decompressobj = zlib.decompressobj()
84
85class StreamWriter(Codec,codecs.StreamWriter):
86    pass
87
88class StreamReader(Codec,codecs.StreamReader):
89    pass
90
91### encodings module API
92
93def getregentry():
94    return codecs.CodecInfo(
95        name='zlib',
96        encode=zlib_encode,
97        decode=zlib_decode,
98        incrementalencoder=IncrementalEncoder,
99        incrementaldecoder=IncrementalDecoder,
100        streamreader=StreamReader,
101        streamwriter=StreamWriter,
102    )
103