org.hibernate.transform.RootEntityResultTransformer Maven / Gradle / Ivy
/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* License: GNU Lesser General Public License (LGPL), version 2.1 or later.
* See the lgpl.txt file in the root directory or .
*/
package org.hibernate.transform;
import org.hibernate.internal.util.collections.ArrayHelper;
/**
* {@link ResultTransformer} implementation which limits the result tuple
* to only the "root entity".
*
* 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 final class RootEntityResultTransformer extends BasicTransformerAdapter implements TupleSubsetResultTransformer {
public static final RootEntityResultTransformer INSTANCE = new RootEntityResultTransformer();
/**
* Disallow instantiation of RootEntityResultTransformer.
*/
private RootEntityResultTransformer() {
}
/**
* Return just the root entity from the row tuple.
*/
@Override
public Object transformTuple(Object[] tuple, String[] aliases) {
return tuple[ tuple.length-1 ];
}
@Override
public boolean isTransformedValueATupleElement(String[] aliases, int tupleLength) {
return true;
}
@Override
public boolean[] includeInTransform(String[] aliases, int tupleLength) {
boolean[] includeInTransform;
if ( tupleLength == 1 ) {
includeInTransform = ArrayHelper.TRUE;
}
else {
includeInTransform = new boolean[tupleLength];
includeInTransform[ tupleLength - 1 ] = true;
}
return includeInTransform;
}
/**
* Serialization hook for ensuring singleton uniqueing.
*
* @return The singleton instance : {@link #INSTANCE}
*/
private Object readResolve() {
return INSTANCE;
}
}