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# Copyright (C) 2007-2017 by the Free Software Foundation, Inc.
#
# This file is part of GNU Mailman.
#
# GNU Mailman is free software: you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option)
# any later version.
#
# GNU Mailman is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
# more details.
#
# You should have received a copy of the GNU General Public License along with
# GNU Mailman. If not, see <http://www.gnu.org/licenses/>.
"""Application support for chain processing."""
from mailman.chains.base import Chain, TerminalChainBase
from mailman.config import config
from mailman.interfaces.chain import IChain, LinkAction
from mailman.utilities.modules import find_components
from public import public
from zope.interface.verify import verifyObject
@public
def process(mlist, msg, msgdata, start_chain='default-posting-chain'):
"""Process the message through a chain.
:param mlist: the IMailingList for this message.
:param msg: The Message object.
:param msgdata: The message metadata dictionary.
:param start_chain: The name of the chain to start the processing with.
"""
# Set up some bookkeeping.
chain_stack = []
msgdata['rule_hits'] = hits = []
msgdata['rule_misses'] = misses = []
# Find the starting chain and begin iterating through its links.
chain = config.chains[start_chain]
chain_iter = chain.get_links(mlist, msg, msgdata)
# Loop until we've reached the end of all processing chains.
while chain:
# Iterate over all links in the chain. Do this outside a for-loop so
# we can capture a chain's link iterator in mid-flight. This supports
# the 'detour' link action.
try:
link = next(chain_iter)
except StopIteration:
# This chain is exhausted. Pop the last chain on the stack and
# continue iterating through it. If there's nothing left on the
# chain stack then we're completely finished processing.
if len(chain_stack) == 0:
return
chain, chain_iter = chain_stack.pop()
continue
if link.rule.check(mlist, msg, msgdata):
if link.rule.record:
hits.append(link.rule.name)
# The rule matched so run its action.
if link.action is LinkAction.jump:
chain = link.chain
chain_iter = chain.get_links(mlist, msg, msgdata)
continue
elif link.action is LinkAction.detour:
# Push the current chain so that we can return to it when
# the next chain is finished.
chain_stack.append((chain, chain_iter))
chain = link.chain
chain_iter = chain.get_links(mlist, msg, msgdata)
continue
elif link.action is LinkAction.stop:
# Stop all processing.
return
elif link.action is LinkAction.defer:
# Just process the next link in the chain.
pass
elif link.action is LinkAction.run:
link.function(mlist, msg, msgdata)
else:
raise AssertionError(
'Bad link action: {}'.format(link.action))
else:
# The rule did not match; keep going.
if link.rule.record:
misses.append(link.rule.name)
@public
def initialize():
"""Set up chains, both built-in and from the database."""
for chain_class in find_components('mailman.chains', IChain):
# FIXME 2010-12-28 barry: We need a generic way to disable automatic
# instantiation of discovered classes. This is useful not just for
# chains, but also for rules, handlers, etc. Ideally it should be
# part of find_components(). For now, hard code the ones we do not
# want to instantiate.
if chain_class in (Chain, TerminalChainBase):
continue
chain = chain_class()
verifyObject(IChain, chain)
assert chain.name not in config.chains, (
'Duplicate chain "{}" found in {} (previously: {}'.format(
chain.name, chain_class, config.chains[chain.name]))
config.chains[chain.name] = chain
# XXX Read chains from the database and initialize them.
pass
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