/*
 * 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 <http://www.gnu.org/licenses/lgpl-2.1.html>.
 */
package org.hibernate.transform;

import org.hibernate.internal.util.collections.ArrayHelper;

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 instance. 
Author:
Gavin King, Steve Ebersole/**
 * {@link ResultTransformer} implementation which limits the result tuple
 * to only the "root entity".
 * <p/>
 * 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.
/**
	 * Disallow instantiation of RootEntityResultTransformer.
	 */
	private RootEntityResultTransformer() {
	}

	
Return just the root entity from the row tuple.
/**
	 * 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.
Returns:
The singleton instance : INSTANCE/**
	 * Serialization hook for ensuring singleton uniqueing.
	 *
	 * @return The singleton instance : {@link #INSTANCE}
	 */
	private Object readResolve() {
		return INSTANCE;
	}
}