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/*
 * Copyright (c) 2012, 2020 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 v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0,
 * or the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

// Contributors:
//     Oracle - initial API and implementation
//
package org.eclipse.persistence.jpa.jpql.parser;

/**
 * In a hierarchical query, if the rows of siblings of the same parent need to be ordered, then the
 * ORDER SIBLINGS BY clause should be used. Either ORDER BY
 * or GROUP BY should not be used, as they will destroy the hierarchical order
 * of the CONNECT BY results.
 *
 * BNF: order_sibling_by_clause ::= ORDER SIBLINGS BY {@link OrderByItem orderby_item} {, {@link OrderByItem orderby_item}}*
 *
 * @version 2.5
 * @since 2.5
 * @author Pascal Filion
 */
public final class OrderSiblingsByClause extends AbstractOrderByClause {

    /**
     * Creates a new OrderSiblingsByClause.
     *
     * @param parent The parent of this expression
     */
    public OrderSiblingsByClause(AbstractExpression parent) {
        super(parent, ORDER_SIBLINGS_BY);
    }

    @Override
    public void accept(ExpressionVisitor visitor) {
        acceptUnknownVisitor(visitor);
    }

    @Override
    public JPQLQueryBNF getQueryBNF() {
        return getQueryBNF(OrderSiblingsByClauseBNF.ID);
    }
}