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# Copyright (C) 2008 by the Free Software Foundation, Inc.
#
# This program 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 2
# of the License, or (at your option) any later version.
#
# This program 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 this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
# USA.
"""Base class for terminal chains."""
__all__ = [
'Chain',
'Link',
'TerminalChainBase',
]
__metaclass__ = type
from zope.interface import implements
from Mailman.configuration import config
from Mailman.interfaces import (
IChain, IChainIterator, IChainLink, IMutableChain, LinkAction)
class Link:
"""A chain link."""
implements(IChainLink)
def __init__(self, rule, action=None, chain=None, function=None):
self.rule = rule
self.action = (LinkAction.defer if action is None else action)
self.chain = chain
self.function = function
class TerminalChainBase:
"""A base chain that always matches and executes a method.
The method is called 'process' and must be provided by the subclass.
"""
implements(IChain, IChainIterator)
def _process(self, mlist, msg, msgdata):
"""Process the message for the given mailing list.
This must be overridden by subclasses.
"""
raise NotImplementedError
def get_links(self, mlist, msg, msgdata):
"""See `IChain`."""
return iter(self)
def __iter__(self):
"""See `IChainIterator`."""
truth = config.rules['truth']
# First, yield a link that always runs the process method.
yield Link(truth, LinkAction.run, function=self._process)
# Now yield a rule that stops all processing.
yield Link(truth, LinkAction.stop)
class Chain:
"""Generic chain base class."""
implements(IMutableChain)
def __init__(self, name, description):
assert name not in config.chains, 'Duplicate chain name: %s' % name
self.name = name
self.description = description
self._links = []
# Register the chain.
config.chains[name] = self
def append_link(self, link):
"""See `IMutableChain`."""
self._links.append(link)
def flush(self):
"""See `IMutableChain`."""
self._links = []
def get_links(self, mlist, msg, msgdata):
"""See `IChain`."""
return iter(ChainIterator(self))
def get_iterator(self):
"""Return an iterator over the links."""
# We do it this way in order to preserve a separation of interfaces,
# and allows .get_links() to be overridden.
for link in self._links:
yield link
class ChainIterator:
"""Generic chain iterator."""
implements(IChainIterator)
def __init__(self, chain):
self._chain = chain
def __iter__(self):
"""See `IChainIterator`."""
return self._chain.get_iterator()
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