# Copyright (C) 2001-2006 Python Software Foundation# Author: Barry Warsaw# Contact: email-sig@python.org """Encodings and related functions.""" __all__ = [    'encode_7or8bit',    'encode_base64',    'encode_noop',    'encode_quopri',    ] import base64 from quopri import encodestring as _encodestring  def _qencode(s):    enc = _encodestring(s, quotetabs=True)    # Must encode spaces, which quopri.encodestring() doesn't do    return enc.replace(' ', '=20')  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:        # iso-2022-* is non-ASCII but still 7-bit        charset = msg.get_charset()        output_cset = charset and charset.output_charset        if output_cset and output_cset.lower().startswith('iso-2202-'):            msg['Content-Transfer-Encoding'] = '7bit'        else:            msg['Content-Transfer-Encoding'] = '8bit'    else:        msg['Content-Transfer-Encoding'] = '7bit'  def encode_noop(msg):    """Do nothing."""