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New parser. Next up, making the current parser use this parser
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Anthony Baxter
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1 changed files with 362 additions and 0 deletions
362
Lib/email/FeedParser.py
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362
Lib/email/FeedParser.py
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# A new Feed-style Parser
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from email import Errors, Message
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import re
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NLCRE = re.compile('\r\n|\r|\n')
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EMPTYSTRING = ''
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NL = '\n'
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NeedMoreData = object()
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class FeedableLumpOfText:
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"A file-like object that can have new data loaded into it"
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def __init__(self):
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self._partial = ''
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self._done = False
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# _pending is a list of lines, in reverse order
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self._pending = []
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def readline(self):
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""" Return a line of data.
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If data has been pushed back with unreadline(), the most recently
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returned unreadline()d data will be returned.
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"""
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if not self._pending:
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if self._done:
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return ''
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return NeedMoreData
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return self._pending.pop()
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def unreadline(self, line):
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""" Push a line back into the object.
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"""
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self._pending.append(line)
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def peekline(self):
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""" Non-destructively look at the next line """
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if not self._pending:
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if self._done:
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return ''
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return NeedMoreData
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return self._pending[-1]
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# for r in self._input.readuntil(regexp):
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# if r is NeedMoreData:
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# yield NeedMoreData
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# preamble, matchobj = r
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def readuntil(self, matchre, afterblank=False, includematch=False):
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""" Read a line at a time until we get the specified RE.
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Returns the text up to (and including, if includematch is true) the
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matched text, and the RE match object. If afterblank is true,
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there must be a blank line before the matched text. Moves current
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filepointer to the line following the matched line. If we reach
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end-of-file, return what we've got so far, and return None as the
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RE match object.
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"""
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prematch = []
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blankseen = 0
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while 1:
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if not self._pending:
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if self._done:
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# end of file
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yield EMPTYSTRING.join(prematch), None
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else:
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yield NeedMoreData
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continue
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line = self._pending.pop()
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if afterblank:
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if NLCRE.match(line):
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blankseen = 1
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continue
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else:
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blankseen = 0
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m = matchre.match(line)
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if (m and not afterblank) or (m and afterblank and blankseen):
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if includematch:
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prematch.append(line)
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yield EMPTYSTRING.join(prematch), m
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prematch.append(line)
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NLatend = re.compile('(\r\n|\r|\n)$').match
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NLCRE_crack = re.compile('(\r\n|\r|\n)')
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def push(self, data):
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""" Push some new data into this object """
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# Handle any previous leftovers
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data, self._partial = self._partial+data, ''
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# Crack into lines, but leave the newlines on the end of each
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lines = self.NLCRE_crack.split(data)
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# The *ahem* interesting behaviour of re.split when supplied
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# groups means that the last element is the data after the
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# final RE. In the case of a NL/CR terminated string, this is
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# the empty string.
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self._partial = lines.pop()
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o = []
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for i in range(len(lines) / 2):
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o.append(EMPTYSTRING.join([lines[i*2], lines[i*2+1]]))
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self.pushlines(o)
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def pushlines(self, lines):
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""" Push a list of new lines into the object """
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# Reverse and insert at the front of _pending
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self._pending[:0] = lines[::-1]
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def end(self):
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""" There is no more data """
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self._done = True
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def is_done(self):
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return self._done
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def __iter__(self):
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return self
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def next(self):
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l = self.readline()
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if l == '':
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raise StopIteration
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return l
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class FeedParser:
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"A feed-style parser of email. copy docstring here"
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def __init__(self, _class=Message.Message):
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"fnord fnord fnord"
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self._class = _class
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self._input = FeedableLumpOfText()
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self._root = None
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self._objectstack = []
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self._parse = self._parsegen().next
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def end(self):
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self._input.end()
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self._call_parse()
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return self._root
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def feed(self, data):
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self._input.push(data)
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self._call_parse()
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def _call_parse(self):
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try:
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self._parse()
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except StopIteration:
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pass
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headerRE = re.compile(r'^(From |[-\w]{2,}:|[\t ])')
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def _parse_headers(self,headerlist):
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# Passed a list of strings that are the headers for the
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# current object
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lastheader = ''
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lastvalue = []
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for lineno, line in enumerate(headerlist):
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# Check for continuation
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if line[0] in ' \t':
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if not lastheader:
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raise Errors.HeaderParseError('First line must not be a continuation')
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lastvalue.append(line)
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continue
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if lastheader:
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# XXX reconsider the joining of folded lines
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self._cur[lastheader] = EMPTYSTRING.join(lastvalue).rstrip()
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lastheader, lastvalue = '', []
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# Check for Unix-From
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if line.startswith('From '):
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if lineno == 0:
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self._cur.set_unixfrom(line)
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continue
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elif lineno == len(headerlist) - 1:
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# Something looking like a unix-from at the end - it's
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# probably the first line of the body
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self._input.unreadline(line)
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return
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else:
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# Weirdly placed unix-from line. Ignore it.
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continue
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i = line.find(':')
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if i < 0:
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# The older parser had various special-cases here. We've
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# already handled them
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raise Errors.HeaderParseError(
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"Not a header, not a continuation: ``%s''" % line)
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lastheader = line[:i]
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lastvalue = [line[i+1:].lstrip()]
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if lastheader:
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# XXX reconsider the joining of folded lines
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self._cur[lastheader] = EMPTYSTRING.join(lastvalue).rstrip()
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def _parsegen(self):
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# Parse any currently available text
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self._new_sub_object()
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self._root = self._cur
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completing = False
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last = None
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for line in self._input:
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if line is NeedMoreData:
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yield None # Need More Data
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continue
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self._input.unreadline(line)
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if not completing:
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headers = []
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# Now collect all headers.
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for line in self._input:
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if line is NeedMoreData:
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yield None # Need More Data
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continue
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if not self.headerRE.match(line):
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self._parse_headers(headers)
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# A message/rfc822 has no body and no internal
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# boundary.
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if self._cur.get_content_maintype() == "message":
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self._new_sub_object()
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completing = False
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headers = []
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continue
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if line.strip():
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# No blank line between headers and body.
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# Push this line back, it's the first line of
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# the body.
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self._input.unreadline(line)
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break
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else:
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headers.append(line)
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else:
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# We're done with the data and are still inside the headers
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self._parse_headers(headers)
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# Now we're dealing with the body
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boundary = self._cur.get_boundary()
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isdigest = (self._cur.get_content_type() == 'multipart/digest')
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if boundary and not self._cur._finishing:
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separator = '--' + boundary
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self._cur._boundaryRE = re.compile(
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r'(?P<sep>' + re.escape(separator) +
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r')(?P<end>--)?(?P<ws>[ \t]*)(?P<linesep>\r\n|\r|\n)$')
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for r in self._input.readuntil(self._cur._boundaryRE):
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if r is NeedMoreData:
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yield NeedMoreData
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else:
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preamble, matchobj = r
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break
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if not matchobj:
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# Broken - we hit the end of file. Just set the body
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# to the text.
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if completing:
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self._attach_trailer(last, preamble)
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else:
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self._attach_preamble(self._cur, preamble)
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# XXX move back to the parent container.
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self._pop_container()
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completing = True
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continue
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if preamble:
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if completing:
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preamble = preamble[:-len(matchobj.group('linesep'))]
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self._attach_trailer(last, preamble)
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else:
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self._attach_preamble(self._cur, preamble)
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elif not completing:
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# The module docs specify an empty preamble is None, not ''
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self._cur.preamble = None
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# If we _are_ completing, the last object gets no payload
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if matchobj.group('end'):
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# That was the end boundary tag. Bounce back to the
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# parent container
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last = self._pop_container()
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self._input.unreadline(matchobj.group('linesep'))
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completing = True
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continue
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# A number of MTAs produced by a nameless large company
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# we shall call "SicroMoft" produce repeated boundary
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# lines.
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while True:
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line = self._input.peekline()
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if line is NeedMoreData:
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yield None
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continue
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if self._cur._boundaryRE.match(line):
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self._input.readline()
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else:
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break
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self._new_sub_object()
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completing = False
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if isdigest:
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self._cur.set_default_type('message/rfc822')
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continue
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else:
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# non-multipart or after end-boundary
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if last is not self._root:
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last = self._pop_container()
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if self._cur.get_content_maintype() == "message":
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# We double-pop to leave the RFC822 object
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self._pop_container()
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completing = True
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elif self._cur._boundaryRE and last <> self._root:
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completing = True
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else:
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# Non-multipart top level, or in the trailer of the
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# top level multipart
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while not self._input.is_done():
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yield None
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data = list(self._input)
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body = EMPTYSTRING.join(data)
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self._attach_trailer(last, body)
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def _attach_trailer(self, obj, trailer):
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#import pdb ; pdb.set_trace()
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if obj.get_content_maintype() in ( "multipart", "message" ):
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obj.epilogue = trailer
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else:
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obj.set_payload(trailer)
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def _attach_preamble(self, obj, trailer):
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if obj.get_content_maintype() in ( "multipart", "message" ):
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obj.preamble = trailer
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else:
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obj.set_payload(trailer)
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def _new_sub_object(self):
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new = self._class()
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#print "pushing", self._objectstack, repr(new)
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if self._objectstack:
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self._objectstack[-1].attach(new)
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self._objectstack.append(new)
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new._boundaryRE = None
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new._finishing = False
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self._cur = new
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def _pop_container(self):
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# Move the pointer to the container of the current object.
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# Returns the (old) current object
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#import pdb ; pdb.set_trace()
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#print "popping", self._objectstack
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last = self._objectstack.pop()
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if self._objectstack:
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self._cur = self._objectstack[-1]
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else:
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self._cur._finishing = True
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return last
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