# Copyright (C) 2004-2006 Python Software Foundation
# Authors: Baxter, Wouters and Warsaw
# Contact: email-sig@python.org
"""FeedParser - An email feed parser.
The feed parser implements an interface for incrementally parsing an email
message, line by line. This has advantages for certain applications, such as
those reading email messages off a socket.
FeedParser.feed() is the primary interface for pushing new data into the
parser. It returns when there's nothing more it can do with the available
data. When you have no more data to push into the parser, call .close().
This completes the parsing and returns the root message object.
The other advantage of this parser is that it will never raise a parsing
exception. Instead, when it finds something unexpected, it adds a 'defect' to
the current message. Defects are just instances that live on the message
object's .defects attribute.
from email import message
NLCRE = re.compile('\r\n|\r|\n')
NLCRE_bol = re.compile('(\r\n|\r|\n)')
NLCRE_eol = re.compile('(\r\n|\r|\n)\Z')
NLCRE_crack = re.compile('(\r\n|\r|\n)')
# RFC 2822 $3.6.8 Optional fields. ftext is %d33-57 / %d59-126, Any character
# except controls, SP, and ":".
headerRE = re.compile(r'^(From |[\041-\071\073-\176]{1,}:|[\t ])')
class BufferedSubFile(object):
"""A file-ish object that can have new data loaded into it.
You can also push and pop line-matching predicates onto a stack. When the
current predicate matches the current line, a false EOF response
(i.e. empty string) is returned instead. This lets the parser adhere to a
simple abstraction -- it parses until EOF closes the current message.
# Chunks of the last partial line pushed into this object.
# The list of full, pushed lines, in reverse order
# The stack of false-EOF checking predicates.
# A flag indicating whether the file has been closed or not.
def push_eof_matcher(self, pred):
self._eofstack.append(pred)
def pop_eof_matcher(self):
return self._eofstack.pop()
# Don't forget any trailing partial line.
self.pushlines(''.join(self._partial).splitlines(True))
# Pop the line off the stack and see if it matches the current
# RFC 2046, section 5.1.2 requires us to recognize outer level
# boundaries at any level of inner nesting. Do this, but be sure it's
# in the order of most to least nested.
for ateof in self._eofstack[::-1]:
# We're at the false EOF. But push the last line back first.
def unreadline(self, line):
# Let the consumer push a line back into the buffer.
assert line is not NeedMoreData
"""Push some new data into this object."""
# Crack into lines, but preserve the linesep characters on the end of each
parts = data.splitlines(True)
if not parts or not parts[0].endswith(('\n', '\r')):
# No new complete lines, so just accumulate partials
# If there are previous leftovers, complete them now
self._partial.append(parts[0])
parts[0:1] = ''.join(self._partial).splitlines(True)
# If the last element of the list does not end in a newline, then treat
# it as a partial line. We only check for '\n' here because a line
# ending with '\r' might be a line that was split in the middle of a
# '\r\n' sequence (see bugs 1555570 and 1721862).
if not parts[-1].endswith('\n'):
self._partial = [parts.pop()]
def pushlines(self, lines):
# Reverse and insert at the front of the lines.
self._lines[:0] = lines[::-1]
"""A feed-style parser of email."""
def __init__(self, _factory=message.Message):
"""_factory is called with no arguments to create a new message obj"""
self._input = BufferedSubFile()
self._parse = self._parsegen().next
self._headersonly = False
# Non-public interface for supporting Parser's headersonly flag
def _set_headersonly(self):
"""Push more data into the parser."""
"""Parse all remaining data and return the root message object."""
root = self._pop_message()
assert not self._msgstack
# Look for final set of defects
if root.get_content_maintype() == 'multipart' \
and not root.is_multipart():
root.defects.append(errors.MultipartInvariantViolationDefect())
if self._cur and self._cur.get_content_type() == 'multipart/digest':
msg.set_default_type('message/rfc822')
self._msgstack[-1].attach(msg)
self._msgstack.append(msg)
retval = self._msgstack.pop()
self._cur = self._msgstack[-1]
# Create a new message and start by parsing headers.
# Collect the headers, searching for a line that doesn't match the RFC
# 2822 header or continuation pattern (including an empty line).
if not headerRE.match(line):
# If we saw the RFC defined header/body separator
# (i.e. newline), just throw it away. Otherwise the line is
# part of the body so push it back.
if not NLCRE.match(line):
self._input.unreadline(line)
# Done with the headers, so parse them and figure out what we're
# supposed to see in the body of the message.
self._parse_headers(headers)
# Headers-only parsing is a backwards compatibility hack, which was
# necessary in the older parser, which could raise errors. All
# remaining lines in the input are thrown into the message body.
line = self._input.readline()
self._cur.set_payload(EMPTYSTRING.join(lines))
if self._cur.get_content_type() == 'message/delivery-status':
# message/delivery-status contains blocks of headers separated by
# a blank line. We'll represent each header block as a separate
# nested message object, but the processing is a bit different
# than standard message/* types because there is no body for the
# nested messages. A blank line separates the subparts.
self._input.push_eof_matcher(NLCRE.match)
for retval in self._parsegen():
if retval is NeedMoreData:
msg = self._pop_message()
# We need to pop the EOF matcher in order to tell if we're at
# the end of the current file, not the end of the last block
self._input.pop_eof_matcher()
# The input stream must be sitting at the newline or at the
# EOF. We want to see if we're at the end of this subpart, so
# first consume the blank line, then test the next line to see
# if we're at this subpart's EOF.
line = self._input.readline()
line = self._input.readline()
# Not at EOF so this is a line we're going to need.
self._input.unreadline(line)
if self._cur.get_content_maintype() == 'message':
# The message claims to be a message/* type, then what follows is
# another RFC 2822 message.
for retval in self._parsegen():
if retval is NeedMoreData:
if self._cur.get_content_maintype() == 'multipart':
boundary = self._cur.get_boundary()
# The message /claims/ to be a multipart but it has not
# defined a boundary. That's a problem which we'll handle by
# reading everything until the EOF and marking the message as
self._cur.defects.append(errors.NoBoundaryInMultipartDefect())
self._cur.set_payload(EMPTYSTRING.join(lines))
# Create a line match predicate which matches the inter-part
# boundary as well as the end-of-multipart boundary. Don't push
# this onto the input stream until we've scanned past the
separator = '--' + boundary
'(?P<sep>' + re.escape(separator) +
r')(?P<end>--)?(?P<ws>[ \t]*)(?P<linesep>\r\n|\r|\n)?$')
capturing_preamble = True
line = self._input.readline()
mo = boundaryre.match(line)
# If we're looking at the end boundary, we're done with
# this multipart. If there was a newline at the end of
# the closing boundary, then we need to initialize the
# epilogue with the empty string (see below).
linesep = mo.group('linesep')
# We saw an inter-part boundary. Were we in the preamble?
# According to RFC 2046, the last newline belongs
eolmo = NLCRE_eol.search(lastline)
preamble[-1] = lastline[:-len(eolmo.group(0))]
self._cur.preamble = EMPTYSTRING.join(preamble)
capturing_preamble = False
self._input.unreadline(line)
# We saw a boundary separating two parts. Consume any
# multiple boundary lines that may be following. Our
# interpretation of RFC 2046 BNF grammar does not produce
# body parts within such double boundaries.
line = self._input.readline()
mo = boundaryre.match(line)
self._input.unreadline(line)
# Recurse to parse this subpart; the input stream points
# at the subpart's first line.
self._input.push_eof_matcher(boundaryre.match)
for retval in self._parsegen():
if retval is NeedMoreData:
# Because of RFC 2046, the newline preceding the boundary
# separator actually belongs to the boundary, not the
# previous subpart's payload (or epilogue if the previous
if self._last.get_content_maintype() == 'multipart':
epilogue = self._last.epilogue
self._last.epilogue = None
elif epilogue is not None:
mo = NLCRE_eol.search(epilogue)
self._last.epilogue = epilogue[:-end]
payload = self._last.get_payload()
if isinstance(payload, basestring):
mo = NLCRE_eol.search(payload)
payload = payload[:-len(mo.group(0))]
self._last.set_payload(payload)
self._input.pop_eof_matcher()
# Set the multipart up for newline cleansing, which will
# happen if we're in a nested multipart.
# I think we must be in the preamble
assert capturing_preamble
# We've seen either the EOF or the end boundary. If we're still
# capturing the preamble, we never saw the start boundary. Note
# that as a defect and store the captured text as the payload.
# Everything from here to the EOF is epilogue.
self._cur.defects.append(errors.StartBoundaryNotFoundDefect())
self._cur.set_payload(EMPTYSTRING.join(preamble))
self._cur.epilogue = EMPTYSTRING.join(epilogue)
# If the end boundary ended in a newline, we'll need to make sure
# the epilogue isn't None
# Any CRLF at the front of the epilogue is not technically part of
# the epilogue. Also, watch out for an empty string epilogue,
# which means a single newline.
bolmo = NLCRE_bol.match(firstline)
epilogue[0] = firstline[len(bolmo.group(0)):]
self._cur.epilogue = EMPTYSTRING.join(epilogue)
# Otherwise, it's some non-multipart type, so the entire rest of the
# file contents becomes the payload.
self._cur.set_payload(EMPTYSTRING.join(lines))
def _parse_headers(self, lines):
# Passed a list of lines that make up the headers for the current msg
for lineno, line in enumerate(lines):
# The first line of the headers was a continuation. This
# is illegal, so let's note the defect, store the illegal
# line, and ignore it for purposes of headers.
defect = errors.FirstHeaderLineIsContinuationDefect(line)
self._cur.defects.append(defect)
# XXX reconsider the joining of folded lines
lhdr = EMPTYSTRING.join(lastvalue)[:-1].rstrip('\r\n')
self._cur[lastheader] = lhdr
lastheader, lastvalue = '', []
# Check for envelope header, i.e. unix-from
if line.startswith('From '):
# Strip off the trailing newline
mo = NLCRE_eol.search(line)
line = line[:-len(mo.group(0))]
self._cur.set_unixfrom(line)
elif lineno == len(lines) - 1:
# Something looking like a unix-from at the end - it's
# probably the first line of the body, so push back the
self._input.unreadline(line)
# Weirdly placed unix-from line. Note this as a defect
defect = errors.MisplacedEnvelopeHeaderDefect(line)
self._cur.defects.append(defect)
# Split the line on the colon separating field name from value.
defect = errors.MalformedHeaderDefect(line)
self._cur.defects.append(defect)
lastvalue = [line[i+1:].lstrip()]
# Done with all the lines, so handle the last header.
# XXX reconsider the joining of folded lines
self._cur[lastheader] = EMPTYSTRING.join(lastvalue).rstrip('\r\n')
It is recommended that you Edit text format, this type of Fix handles quite a lot in one request
