1 files changed, 122 insertions, 0 deletions
diff --git a/src/mailman/chains/base.py b/src/mailman/chains/base.py
new file mode 100644
index 000000000..bcd946b40
--- /dev/null
+++ b/src/mailman/chains/base.py
@@ -0,0 +1,122 @@
+# Copyright (C) 2008-2009 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/>.
+
+"""Base class for terminal chains."""
+
+from __future__ import absolute_import, unicode_literals
+
+__metaclass__ = type
+__all__ = [
+    'Chain',
+    'Link',
+    'TerminalChainBase',
+    ]
+
+
+from zope.interface import implements
+
+from mailman.config import config
+from mailman.interfaces.chain 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: {0}'.format(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()