org.hibernate.transform.DistinctRootEntityResultTransformer Maven / Gradle / Ivy
/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Middleware LLC.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* 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 Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*
*/
package org.hibernate.transform;
import java.util.List;
/**
* Much like {@link RootEntityResultTransformer}, but we also distinct
* the entity in the final result.
*
* Since this transformer is stateless, all instances would be considered equal.
* So for optimization purposes we limit it to a single, singleton {@link #INSTANCE instance}.
*
* @author Gavin King
* @author Steve Ebersole
*/
public class DistinctRootEntityResultTransformer implements TupleSubsetResultTransformer {
public static final DistinctRootEntityResultTransformer INSTANCE = new DistinctRootEntityResultTransformer();
/**
* Disallow instantiation of DistinctRootEntityResultTransformer.
*/
private DistinctRootEntityResultTransformer() {
}
/**
* Simply delegates to {@link RootEntityResultTransformer#transformTuple}.
*
* @param tuple The tuple to transform
* @param aliases The tuple aliases
* @return The transformed tuple row.
*/
@Override
public Object transformTuple(Object[] tuple, String[] aliases) {
return RootEntityResultTransformer.INSTANCE.transformTuple( tuple, aliases );
}
/**
* Simply delegates to {@link DistinctResultTransformer#transformList}.
*
* @param list The list to transform.
* @return The transformed List.
*/
@Override
public List transformList(List list) {
return DistinctResultTransformer.INSTANCE.transformList( list );
}
@Override
public boolean[] includeInTransform(String[] aliases, int tupleLength) {
return RootEntityResultTransformer.INSTANCE.includeInTransform( aliases, tupleLength );
}
@Override
public boolean isTransformedValueATupleElement(String[] aliases, int tupleLength) {
return RootEntityResultTransformer.INSTANCE.isTransformedValueATupleElement( null, tupleLength );
}
/**
* Serialization hook for ensuring singleton uniqueing.
*
* @return The singleton instance : {@link #INSTANCE}
*/
private Object readResolve() {
return INSTANCE;
}
}