Reorganization.

Create a Mailman.chains package and move a bunch of the Mailman.apps.chains
classes to separate modules under this package.

Also, separate out iteration from chain management.  In other words, IChain
and IChainIterator are separate, and the latter is retrieved from the former
by the .get_links() method.  This latter takes the mailing list, message, and
metadata dictionary so that links can be targetted specifically to the task at
hand.

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()