cpython/Lib/quopri.py

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#! /usr/bin/env python
"""Conversions to/from quoted-printable transport encoding as per RFC-1521."""
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# (Dec 1991 version).
ESCAPE = '='
MAXLINESIZE = 76
HEX = '0123456789ABCDEF'
def needsquoting(c, quotetabs):
"""Decide whether a particular character needs to be quoted.
The 'quotetabs' flag indicates whether tabs should be quoted."""
if c == '\t':
return not quotetabs
return c == ESCAPE or not(' ' <= c <= '~')
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def quote(c):
"""Quote a single character."""
i = ord(c)
return ESCAPE + HEX[i/16] + HEX[i%16]
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def encode(input, output, quotetabs):
"""Read 'input', apply quoted-printable encoding, and write to 'output'.
'input' and 'output' are files with readline() and write() methods.
The 'quotetabs' flag indicates whether tabs should be quoted.
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"""
while 1:
line = input.readline()
if not line:
break
new = ''
last = line[-1:]
if last == '\n':
line = line[:-1]
else:
last = ''
prev = ''
for c in line:
if needsquoting(c, quotetabs):
c = quote(c)
if len(new) + len(c) >= MAXLINESIZE:
output.write(new + ESCAPE + '\n')
new = ''
new = new + c
prev = c
if prev in (' ', '\t'):
output.write(new + ESCAPE + '\n\n')
else:
output.write(new + '\n')
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def decode(input, output):
"""Read 'input', apply quoted-printable decoding, and write to 'output'.
'input' and 'output' are files with readline() and write() methods."""
new = ''
while 1:
line = input.readline()
if not line: break
i, n = 0, len(line)
if n > 0 and line[n-1] == '\n':
partial = 0; n = n-1
# Strip trailing whitespace
while n > 0 and line[n-1] in (' ', '\t'):
n = n-1
else:
partial = 1
while i < n:
c = line[i]
if c != ESCAPE:
new = new + c; i = i+1
elif i+1 == n and not partial:
partial = 1; break
elif i+1 < n and line[i+1] == ESCAPE:
new = new + ESCAPE; i = i+2
elif i+2 < n and ishex(line[i+1]) and ishex(line[i+2]):
new = new + chr(unhex(line[i+1:i+3])); i = i+3
else: # Bad escape sequence -- leave it in
new = new + c; i = i+1
if not partial:
output.write(new + '\n')
new = ''
if new:
output.write(new)
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def ishex(c):
"""Return true if the character 'c' is a hexadecimal digit."""
return '0' <= c <= '9' or 'a' <= c <= 'f' or 'A' <= c <= 'F'
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def unhex(s):
"""Get the integer value of a hexadecimal number."""
bits = 0
for c in s:
if '0' <= c <= '9':
i = ord('0')
elif 'a' <= c <= 'f':
i = ord('a')-10
elif 'A' <= c <= 'F':
i = ord('A')-10
else:
break
bits = bits*16 + (ord(c) - i)
return bits
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def test():
import sys
import getopt
try:
opts, args = getopt.getopt(sys.argv[1:], 'td')
except getopt.error, msg:
sys.stdout = sys.stderr
print msg
print "usage: quopri [-t | -d] [file] ..."
print "-t: quote tabs"
print "-d: decode; default encode"
sys.exit(2)
deco = 0
tabs = 0
for o, a in opts:
if o == '-t': tabs = 1
if o == '-d': deco = 1
if tabs and deco:
sys.stdout = sys.stderr
print "-t and -d are mutually exclusive"
sys.exit(2)
if not args: args = ['-']
sts = 0
for file in args:
if file == '-':
fp = sys.stdin
else:
try:
fp = open(file)
except IOError, msg:
sys.stderr.write("%s: can't open (%s)\n" % (file, msg))
sts = 1
continue
if deco:
decode(fp, sys.stdout)
else:
encode(fp, sys.stdout, tabs)
if fp is not sys.stdin:
fp.close()
if sts:
sys.exit(sts)
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if __name__ == '__main__':
test()