Lib/encodings/utf_16.py

   1 """ Python 'utf-16' Codec
   2
   3
   4 Written by Marc-Andre Lemburg (mal@lemburg.com).
   5
   6 (c) Copyright CNRI, All Rights Reserved. NO WARRANTY.
   7
   8 """
   9 import codecs, sys
  10
  11 ### Codec APIs
  12
  13 encode = codecs.utf_16_encode
  14
  15 def decode(input, errors='strict'):
  16     return codecs.utf_16_decode(input, errors, True)
  17
  18 class IncrementalEncoder(codecs.IncrementalEncoder):
  19     def __init__(self, errors='strict'):
  20         codecs.IncrementalEncoder.__init__(self, errors)
  21         self.encoder = None
  22
  23     def encode(self, input, final=False):
  24         if self.encoder is None:
  25             result = codecs.utf_16_encode(input, self.errors)[0]
  26             if sys.byteorder == 'little':
  27                 self.encoder = codecs.utf_16_le_encode
  28             else:
  29                 self.encoder = codecs.utf_16_be_encode
  30             return result
  31         return self.encoder(input, self.errors)[0]
  32
  33     def reset(self):
  34         codecs.IncrementalEncoder.reset(self)
  35         self.encoder = None
  36
  37 class IncrementalDecoder(codecs.BufferedIncrementalDecoder):
  38     def __init__(self, errors='strict'):
  39         codecs.BufferedIncrementalDecoder.__init__(self, errors)
  40         self.decoder = None
  41
  42     def _buffer_decode(self, input, errors, final):
  43         if self.decoder is None:
  44             (output, consumed, byteorder) = \
  45                 codecs.utf_16_ex_decode(input, errors, 0, final)
  46             if byteorder == -1:
  47                 self.decoder = codecs.utf_16_le_decode
  48             elif byteorder == 1:
  49                 self.decoder = codecs.utf_16_be_decode
  50             elif consumed >= 2:
  51                 raise UnicodeError("UTF-16 stream does not start with BOM")
  52             return (output, consumed)
  53         return self.decoder(input, self.errors, final)
  54
  55     def reset(self):
  56         codecs.BufferedIncrementalDecoder.reset(self)
  57         self.decoder = None
  58
  59 class StreamWriter(codecs.StreamWriter):
  60     def __init__(self, stream, errors='strict'):
  61         self.bom_written = False
  62         codecs.StreamWriter.__init__(self, stream, errors)
  63
  64     def encode(self, input, errors='strict'):
  65         self.bom_written = True
  66         result = codecs.utf_16_encode(input, errors)
  67         if sys.byteorder == 'little':
  68             self.encode = codecs.utf_16_le_encode
  69         else:
  70             self.encode = codecs.utf_16_be_encode
  71         return result
  72
  73 class StreamReader(codecs.StreamReader):
  74
  75     def reset(self):
  76         codecs.StreamReader.reset(self)
  77         try:
  78             del self.decode
  79         except AttributeError:
  80             pass
  81
  82     def decode(self, input, errors='strict'):
  83         (object, consumed, byteorder) = \
  84             codecs.utf_16_ex_decode(input, errors, 0, False)
  85         if byteorder == -1:
  86             self.decode = codecs.utf_16_le_decode
  87         elif byteorder == 1:
  88             self.decode = codecs.utf_16_be_decode
  89         elif consumed>=2:
  90             raise UnicodeError,"UTF-16 stream does not start with BOM"
  91         return (object, consumed)
  92
  93 ### encodings module API
  94
  95 def getregentry():
  96     return codecs.CodecInfo(
  97         name='utf-16',
  98         encode=encode,
  99         decode=decode,
 100         incrementalencoder=IncrementalEncoder,
 101         incrementaldecoder=IncrementalDecoder,
 102         streamreader=StreamReader,
 103         streamwriter=StreamWriter,
 104     )