Lib/quopri.py

   1 # Conversions to/from quoted-printable transport encoding as per RFC-XXXX
   2 # (Dec 1991 version).
   3
   4 ESCAPE = '='
   5 MAXLINESIZE = 76
   6 HEX = '0123456789ABCDEF'
   7
   8 def needsquoting(c, quotetabs):
   9         if c == '\t':
  10                 return not quotetabs
  11         return c == ESCAPE or not(' ' <= c <= '~')
  12
  13 def quote(c):
  14         if c == ESCAPE:
  15                 return ESCAPE * 2
  16         else:
  17                 i = ord(c)
  18                 return ESCAPE + HEX[i/16] + HEX[i%16]
  19
  20 def encode(input, output, quotetabs):
  21         while 1:
  22                 line = input.readline()
  23                 if not line: break
  24                 new = ''
  25                 last = line[-1:]
  26                 if last == '\n': line = line[:-1]
  27                 else: last = ''
  28                 prev = ''
  29                 for c in line:
  30                         if needsquoting(c, quotetabs):
  31                                 c = quote(c)
  32                         if len(new) + len(c) >= MAXLINESIZE:
  33                                 output.write(new + ESCAPE + '\n')
  34                                 new = ''
  35                         new = new + c
  36                         prev = c
  37                 if prev in (' ', '\t'):
  38                         output.write(new + ESCAPE + '\n\n')
  39                 else:
  40                         output.write(new + '\n')
  41
  42 def decode(input, output):
  43         new = ''
  44         while 1:
  45                 line = input.readline()
  46                 if not line: break
  47                 i, n = 0, len(line)
  48                 if n > 0 and line[n-1] == '\n':
  49                         partial = 0; n = n-1
  50                         # Strip trailing whitespace
  51                         while n > 0 and line[n-1] in (' ', '\t'):
  52                                 n = n-1
  53                 else:
  54                         partial = 1
  55                 while i < n:
  56                         c = line[i]
  57                         if c <> ESCAPE:
  58                                 new = new + c; i = i+1
  59                         elif i+1 == n and not partial:
  60                                 partial = 1; break
  61                         elif i+1 < n and line[i+1] == ESCAPE:
  62                                 new = new + ESCAPE; i = i+2
  63                         elif i+2 < n and ishex(line[i+1]) and ishex(line[i+2]):
  64                                 new = new + chr(unhex(line[i+1:i+3])); i = i+3
  65                         else: # Bad escape sequence -- leave it in
  66                                 new = new + c; i = i+1
  67                 if not partial:
  68                         output.write(new + '\n')
  69                         new = ''
  70         if new:
  71                 output.write(new)
  72
  73 def ishex(c):
  74         return '0' <= c <= '9' or 'a' <= c <= 'f' or 'A' <= c <= 'F'
  75
  76 def unhex(s):
  77         bits = 0
  78         for c in s:
  79                 if '0' <= c <= '9':
  80                         i = ord('0')
  81                 elif 'a' <= c <= 'f':
  82                         i = ord('a')-10
  83                 elif 'A' <= c <= 'F':
  84                         i = ord('A')-10
  85                 else:
  86                         break
  87                 bits = bits*16 + (ord(c) - i)
  88         return bits
  89
  90 def test():
  91         import sys
  92         if sys.argv[1:]:
  93                 if sys.argv[1] == '-t': # Quote tabs
  94                         encode(sys.stdin, sys.stdout, 1)
  95                 else:
  96                         decode(sys.stdin, sys.stdout)
  97         else:
  98                 encode(sys.stdin, sys.stdout, 0)
  99
 100 if __name__ == '__main__':
 101         main()