/*
 * 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 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;
	}
}