01: /* Copyright (C) 2004 - 2007 db4objects Inc. http://www.db4o.com
02:
03: This file is part of the db4o open source object database.
04:
05: db4o is free software; you can redistribute it and/or modify it under
06: the terms of version 2 of the GNU General Public License as published
07: by the Free Software Foundation and as clarified by db4objects' GPL
08: interpretation policy, available at
09: http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
10: Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
11: Suite 350, San Mateo, CA 94403, USA.
12:
13: db4o is distributed in the hope that it will be useful, but WITHOUT ANY
14: WARRANTY; without even the implied warranty of MERCHANTABILITY or
15: FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16: for more details.
17:
18: You should have received a copy of the GNU General Public License along
19: with this program; if not, write to the Free Software Foundation, Inc.,
20: 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21: package com.db4o.events;
22:
23: import com.db4o.ObjectContainer;
24: import com.db4o.foundation.ArgumentNullException;
25: import com.db4o.internal.*;
26: import com.db4o.internal.callbacks.*;
27: import com.db4o.internal.events.*;
28:
29: /**
30: * Provides an interface for getting an {@link EventRegistry} from an {@link ObjectContainer}.
31: */
32: public class EventRegistryFactory {
33:
34: /**
35: * Returns an {@link EventRegistry} for registering events with the specified container.
36: */
37: public static EventRegistry forObjectContainer(
38: ObjectContainer objectContainer) {
39: if (null == objectContainer) {
40: throw new ArgumentNullException();
41: }
42:
43: InternalObjectContainer container = ((InternalObjectContainer) objectContainer);
44: Callbacks callbacks = container.callbacks();
45: if (callbacks instanceof EventRegistry) {
46: return (EventRegistry) callbacks;
47: }
48: if (callbacks instanceof NullCallbacks) {
49: EventRegistryImpl impl = new EventRegistryImpl(container);
50: container.callbacks(impl);
51: return impl;
52: }
53:
54: // TODO: create a MulticastingCallbacks and register both
55: // the current one and the new one
56: throw new IllegalArgumentException();
57: }
58: }
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