1 files changed, 131 insertions, 0 deletions
diff --git a/Mailman/chains/base.py b/Mailman/chains/base.py
new file mode 100644
index 000000000..30b66b1cf
--- /dev/null
+++ b/Mailman/chains/base.py
@@ -0,0 +1,131 @@
+# 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_rule(self, name):
+        """See `IChain`.
+
+        This always returns the globally registered named rule.
+        """
+        return config.rules[name]
+
+    def get_links(self, mlist, msg, msgdata):
+        """See `IChain`."""
+        return iter(self)
+
+    def __iter__(self):
+        """See `IChainIterator`."""
+        # 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_rule(self, name):
+        """See `IChain`.
+
+        This always returns the globally registered named rule.
+        """
+        return config.rules[name]
+
+    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()