/*******************************************************************************
 * Copyright (c) 2006, 2013 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation
 *
 ******************************************************************************/
package org.eclipse.persistence.jpa.jpql.parser;

/**
 * The query BNF for a result variable expression.
 *
 * @version 2.5.1
 * @since 2.3
 * @author Pascal Filion
 */
public final class ResultVariableBNF extends JPQLQueryBNF {

	/**
	 * The unique identifier of this BNF rule, which is the same as {@link InternalSelectExpressionBNF#ID}
	 * in order to override it.
	 */
	public static final String ID = InternalSelectExpressionBNF.ID;

	/**
	 * Creates a new <code>ResultVariableBNF</code>.
	 */
	public ResultVariableBNF() {
		super(ID);
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected void initialize() {

		super.initialize();

		setFallbackBNFId(ID);
		setFallbackExpressionFactoryId(ResultVariableFactory.ID);
		registerChild(SelectExpressionBNF.ID);

		// The ResultVariable's BNF is this one so it needs to be registered as a child of itself.
		// This is required for validation to work properly. Basically, when checking if the select
		// expression is valid, it checks its BNF with the non-compound children of this one
		registerChild(ResultVariableBNF.ID);
	}
}