Viewing file:  zlib_codec.py (2.98 KB) -rw-r--r--
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""" Python 'zlib_codec' Codec - zlib compression encoding
Unlike most of the other codecs which target Unicode, this codec
will return Python string objects for both encode and decode.
Written by Marc-Andre Lemburg (mal@lemburg.com).
"""
import codecs
import zlib # this codec needs the optional zlib module !
### Codec APIs
def zlib_encode(input,errors='strict'):
""" Encodes the object input and returns a tuple (output
object, length consumed).
errors defines the error handling to apply. It defaults to
'strict' handling which is the only currently supported
error handling for this codec.
"""
assert errors == 'strict'
output = zlib.compress(input)
return (output, len(input))
def zlib_decode(input,errors='strict'):
""" Decodes the object input and returns a tuple (output
object, length consumed).
input must be an object which provides the bf_getreadbuf
buffer slot. Python strings, buffer objects and memory
mapped files are examples of objects providing this slot.
errors defines the error handling to apply. It defaults to
'strict' handling which is the only currently supported
error handling for this codec.
"""
assert errors == 'strict'
output = zlib.decompress(input)
return (output, len(input))
class Codec(codecs.Codec):
def encode(self, input, errors='strict'):
return zlib_encode(input, errors)
def decode(self, input, errors='strict'):
return zlib_decode(input, errors)
class IncrementalEncoder(codecs.IncrementalEncoder):
def __init__(self, errors='strict'):
assert errors == 'strict'
self.errors = errors
self.compressobj = zlib.compressobj()
def encode(self, input, final=False):
if final:
c = self.compressobj.compress(input)
return c + self.compressobj.flush()
else:
return self.compressobj.compress(input)
def reset(self):
self.compressobj = zlib.compressobj()
class IncrementalDecoder(codecs.IncrementalDecoder):
def __init__(self, errors='strict'):
assert errors == 'strict'
self.errors = errors
self.decompressobj = zlib.decompressobj()
def decode(self, input, final=False):
if final:
c = self.decompressobj.decompress(input)
return c + self.decompressobj.flush()
else:
return self.decompressobj.decompress(input)
def reset(self):
self.decompressobj = zlib.decompressobj()
class StreamWriter(Codec,codecs.StreamWriter):
pass
class StreamReader(Codec,codecs.StreamReader):
pass
### encodings module API
def getregentry():
return codecs.CodecInfo(
name='zlib',
encode=zlib_encode,
decode=zlib_decode,
incrementalencoder=IncrementalEncoder,
incrementaldecoder=IncrementalDecoder,
streamreader=StreamReader,
streamwriter=StreamWriter,
_is_text_encoding=False,
)
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