/* This file is part of the db4o object database http://www.db4o.com
Copyright (C) 2004 - 2011 Versant Corporation http://www.versant.com
db4o is free software; you can redistribute it and/or modify it under
the terms of version 3 of the GNU General Public License as published
by the Free Software Foundation.
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, see http://www.gnu.org/licenses/. */
package com.db4o.cs.internal.objectexchange;
import com.db4o.foundation.*;
import com.db4o.internal.*;
import com.db4o.internal.marshall.*;
public class StandardReferenceCollector implements ReferenceCollector {
private Transaction _transaction;
public StandardReferenceCollector(Transaction transaction) {
_transaction = transaction;
}
public Iterator4<Integer> referencesFrom(int id) {
final CollectIdContext context = CollectIdContext.forID(_transaction, id);
final ClassMetadata classMetadata = context.classMetadata();
if (null == classMetadata) {
// most probably ClassMetadata reading
return Iterators.EMPTY_ITERATOR;
}
if (!classMetadata.hasIdentity()) {
throw new IllegalStateException(classMetadata.toString());
}
if (!Handlers4.isCascading(classMetadata.typeHandler())) {
return Iterators.EMPTY_ITERATOR;
}
classMetadata.collectIDs(context);
return new TreeKeyIterator(context.ids());
}
}