Source Code for Module Peach.Transformers.compress

  1   
  2  ''' 
  3  Some default compression transforms (gzip, compress, etc). 
  4   
  5  @author: Michael Eddington 
  6  @version: $Id: Peach.Transformers.compress-pysrc.html 1138 2008-08-16 19:39:03Z meddingt $ 
  7  ''' 
  8   
  9  # 
 10  # Copyright (c) 2005-2008 Michael Eddington 
 11  # Copyright (c) 2004-2005 IOActive Inc. 
 12  # 
 13  # Permission is hereby granted, free of charge, to any person obtaining a copy  
 14  # of this software and associated documentation files (the "Software"), to deal 
 15  # in the Software without restriction, including without limitation the rights  
 16  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell  
 17  # copies of the Software, and to permit persons to whom the Software is  
 18  # furnished to do so, subject to the following conditions: 
 19  # 
 20  # The above copyright notice and this permission notice shall be included in     
 21  # all copies or substantial portions of the Software. 
 22  # 
 23  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  
 24  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  
 25  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE  
 26  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER  
 27  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
 28  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 
 29  # SOFTWARE. 
 30  # 
 31   
 32  # Authors: 
 33  #   Michael Eddington (mike@phed.org) 
 34   
 35  # $Id: Peach.Transformers.compress-pysrc.html 1138 2008-08-16 19:39:03Z meddingt $ 
 36   
 37  import zlib, bz2 
 38  from Peach.transformer import Transformer 
 39   
 40 -class GzipCompress(Transformer): 
 41          ''' 
 42          Gzip compression transform.  Also allows for compression level  
 43          selection (default is 6). 
 44          ''' 
 45           
 46 -        def __init__(self, level = 6): 
 47                  ''' 
 48                  @type   level: number 
 49                  @param  level: level is an integer from 1 to 9 controlling the level 
 50                  of compression; 1 is fastest and produces the least compression, 9 
 51                  is slowest and produces the most. The default value is 6. 
 52                  ''' 
 53                  Transformer.__init__(self) 
 54                  self._level = level 
 55                  self._wbits = 15 
 56           
 57 -        def realEncode(self, data): 
 58                  return zlib.compress(data, self._level) 
 59           
 60 -        def realDecode(self, data): 
 61                  return zlib.decompress(data, self._wbits) 
 62           
 63   
 64 -class GzipDecompress(Transformer): 
 65          ''' 
 66          Gzip decompression transform. 
 67          ''' 
 68           
 69 -        def __init__(self, wbits = 15): 
 70                  ''' 
 71                  @type   wbits: number 
 72                  @param  wbits: The absolute value of wbits is the base two logarithm 
 73                  of the size of the history buffer (the ``window size'') used when 
 74                  compressing data. Its absolute value should be between 8 and 15 for 
 75                  the most recent versions of the zlib library, larger values resulting 
 76                  in better compression at the expense of greater memory usage. The 
 77                  default value is 15. When wbits is negative, the standard gzip 
 78                  header is suppressed; this is an undocumented feature of the zlib 
 79                  library, used for compatibility with unzip's compression file format. 
 80                  ''' 
 81                  Transformer.__init__(self) 
 82                  self._wbits = wbits 
 83                  self._level = 6 
 84           
 85 -        def realEncode(self, data): 
 86                  return zlib.decompress(data, self._wbits) 
 87   
 88 -        def realDecode(self, data): 
 89                  return zlib.compress(data, self._level) 
 90   
 91   
 92 -class Bz2Compress(Transformer): 
 93          ''' 
 94          bzip2 compression transform.  Also allows for compression level  
 95          selection (default is 9). 
 96          ''' 
 97           
 98 -        def __init__(self, level = 9): 
 99                  ''' 
100                  @type   level: number 
101                  @param  level: The compresslevel parameter, if given, must be a number 
102                  between 1 and 9; the default is 9. 
103                  ''' 
104                  Transformer.__init__(self) 
105                  self._level = level 
106           
107 -        def realEncode(self, data): 
108                  return bz2.compress(data, self._level) 
109           
110 -        def realDecode(self, data): 
111                  return bz2.decompress(data) 
112   
113   
114 -class Bz2Decompress(Transformer): 
115          ''' 
116          bzip2 decompression transform. 
117          ''' 
118           
119 -        def realEncode(self, data): 
120                  return bz2.decompress(data) 
121           
122 -        def realDecode(self, data): 
123                  return bz2.compress(data, 6) 
124   
125   
126  # end 
127