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