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/*
 * Copyright (c) 2006, 2021 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;

/**
 * The query BNF for a select expression.
 * 
 * JPA 1.0:
 * 
BNF: select_expression ::= single_valued_path_expression |
 *                                                     aggregate_expression |
 *                                                     identification_variable |
 *                                                     OBJECT(identification_variable) |
 *                                                     constructor_expression
 * 

 * JPA 2.0:
 * BNF: select_expression ::= single_valued_path_expression |
 *                                                     scalar_expression |
 *                                                     aggregate_expression |
 *                                                     identification_variable |
 *                                                     OBJECT(identification_variable) |
 *                                                     constructor_expression
 * @version 2.5
 * @since 2.3
 * @author Pascal Filion
 */
@SuppressWarnings("nls")
public final class SelectExpressionBNF extends JPQLQueryBNF {

    /**
     * The unique identifier of this BNF rule.
     */
    public static final String ID = "select_expression";

    /**
     * Creates a new SelectExpressionBNF.
     */
    public SelectExpressionBNF() {
        super(ID);
    }

    @Override
    protected void initialize() {
        super.initialize();
        setHandleCollection(true);
        setFallbackBNFId(ID);
        setFallbackExpressionFactoryId(LiteralExpressionFactory.ID);
        registerChild(AggregateExpressionBNF.ID);
        registerChild(SingleValuedPathExpressionBNF.ID);
        registerChild(IdentificationVariableBNF.ID);
        registerChild(ObjectExpressionBNF.ID);
        registerChild(ConstructorExpressionBNF.ID);
    }
}