/* Copyright (C) 2004 - 2006 db4objects Inc. http://www.db4o.com
This file is part of the db4o open source object database.
db4o is free software; you can redistribute it and/or modify it under
the terms of version 2 of the GNU General Public License as published
by the Free Software Foundation and as clarified by db4objects' GPL
interpretation policy, available at
http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
Suite 350, San Mateo, CA 94403, USA.
db4o 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.,
59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
package com.db4o.events;
import com.db4o.ObjectContainer;
import com.db4o.foundation.ArgumentNullException;
import com.db4o.internal.*;
import com.db4o.internal.callbacks.*;
import com.db4o.internal.events.*;
/**
* Provides an interface for getting an {@link EventRegistry} from an {@link ObjectContainer}.
*/
public class EventRegistryFactory {
/**
* Returns an {@link EventRegistry} for registering events with the specified container.
*/
public static EventRegistry forObjectContainer(ObjectContainer container) {
if (null == container) {
throw new ArgumentNullException("container");
}
ObjectContainerBase stream = ((ObjectContainerBase)container);
Callbacks callbacks = stream.callbacks();
if (callbacks instanceof EventRegistry) {
return (EventRegistry)callbacks;
}
if (callbacks instanceof NullCallbacks) {
EventRegistryImpl impl = new EventRegistryImpl();
stream.callbacks(impl);
return impl;
}
// TODO: create a MulticastingCallbacks and register both
// the current one and the new one
throw new IllegalArgumentException("container callbacks already in use");
}
}