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 class Codec(codecs.Codec):
  14
  15     # Note: Binding these as C functions will result in the class not
  16     # converting them to methods. This is intended.
  17     encode = codecs.utf_16_encode
  18     decode = codecs.utf_16_decode
  19
  20 class StreamWriter(Codec,codecs.StreamWriter):
  21     def __init__(self, stream, errors='strict'):
  22         self.bom_written = 0
  23         codecs.StreamWriter.__init__(self, stream, errors)
  24
  25     def write(self, data):
  26         result = codecs.StreamWriter.write(self, data)
  27         if not self.bom_written:
  28             self.bom_written = 1
  29             if sys.byteorder == 'little':
  30                 self.encode = codecs.utf_16_le_encode
  31             else:
  32                 self.encode = codecs.utf_16_be_encode
  33         return result
  34
  35 class StreamReader(Codec,codecs.StreamReader):
  36     def __init__(self, stream, errors='strict'):
  37         self.bom_read = 0
  38         codecs.StreamReader.__init__(self, stream, errors)
  39
  40     def read(self, size=-1):
  41         if not self.bom_read:
  42             signature = self.stream.read(2)
  43             if signature == codecs.BOM_BE:
  44                 self.decode = codecs.utf_16_be_decode
  45             elif signature == codecs.BOM_LE:
  46                 self.decode = codecs.utf_16_le_decode
  47             else:
  48                 raise UnicodeError,"UTF-16 stream does not start with BOM"
  49             if size > 2:
  50                 size -= 2
  51             elif size >= 0:
  52                 size = 0
  53             self.bom_read = 1
  54         return codecs.StreamReader.read(self, size)
  55
  56 ### encodings module API
  57
  58 def getregentry():
  59
  60     return (Codec.encode,Codec.decode,StreamReader,StreamWriter)
  61