cpython/Lib/email/Encoders.py

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# Copyright (C) 2001,2002 Python Software Foundation
# Author: barry@zope.com (Barry Warsaw)
"""Module containing encoding functions for Image.Image and Text.Text.
"""
import base64
# Helpers
try:
from quopri import encodestring as _encodestring
def _qencode(s):
enc = _encodestring(s, quotetabs=1)
# Must encode spaces, which quopri.encodestring() doesn't do
return enc.replace(' ', '=20')
except ImportError:
# Python 2.1 doesn't have quopri.encodestring()
from cStringIO import StringIO
import quopri as _quopri
def _qencode(s):
if not s:
return s
hasnewline = (s[-1] == '\n')
infp = StringIO(s)
outfp = StringIO()
_quopri.encode(infp, outfp, quotetabs=1)
# Python 2.x's encode() doesn't encode spaces even when quotetabs==1
value = outfp.getvalue().replace(' ', '=20')
if not hasnewline and value[-1] == '\n':
return value[:-1]
return value
def _bencode(s):
# We can't quite use base64.encodestring() since it tacks on a "courtesy
# newline". Blech!
if not s:
return s
hasnewline = (s[-1] == '\n')
value = base64.encodestring(s)
if not hasnewline and value[-1] == '\n':
return value[:-1]
return value
def encode_base64(msg):
"""Encode the message's payload in Base64.
Also, add an appropriate Content-Transfer-Encoding: header.
"""
orig = msg.get_payload()
encdata = _bencode(orig)
msg.set_payload(encdata)
msg['Content-Transfer-Encoding'] = 'base64'
def encode_quopri(msg):
"""Encode the message's payload in Quoted-Printable.
Also, add an appropriate Content-Transfer-Encoding: header.
"""
orig = msg.get_payload()
encdata = _qencode(orig)
msg.set_payload(encdata)
msg['Content-Transfer-Encoding'] = 'quoted-printable'
def encode_7or8bit(msg):
"""Set the Content-Transfer-Encoding: header to 7bit or 8bit."""
orig = msg.get_payload()
if orig is None:
# There's no payload. For backwards compatibility we use 7bit
msg['Content-Transfer-Encoding'] = '7bit'
return
# We play a trick to make this go fast. If encoding to ASCII succeeds, we
# know the data must be 7bit, otherwise treat it as 8bit.
try:
orig.encode('ascii')
except UnicodeError:
msg['Content-Transfer-Encoding'] = '8bit'
else:
msg['Content-Transfer-Encoding'] = '7bit'
def encode_noop(msg):
"""Do nothing."""