jpa/org.eclipse.persistence.jpa.jpql/src/main/java/org/eclipse/persistence/jpa/jpql/parser/InternalFromClauseBNF.java

/*
 * 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 the <code><b>FROM</b></code> declaration, basically what follows the
 * <code><b>FROM</b></code> identifier.
 * <p></p>
 * JPA:
 * <div><b>BNF:</b> <code>from_clause ::= FROM identification_variable_declaration {, {identification_variable_declaration | collection_member_declaration}}*</code></div>
 * <p></p>
 * EclipseLink 2.4:
 * <div><b>BNF:</b> <code>from_clause ::= FROM identification_variable_declaration {, {identification_variable_declaration |
 *                                                                                            collection_member_declaration |
 *                                                                                            (subquery) |
 *                                                                                            table_declaration }}*</code></div>
 * <p></p>
 *
 * @version 2.4
 * @since 2.3
 * @author Pascal Filion
 */
@SuppressWarnings("nls")
public final class InternalFromClauseBNF extends JPQLQueryBNF {

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

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

    @Override
    protected void initialize() {
        super.initialize();
        setHandleAggregate(true); // To support invalid queries
        setHandleCollection(true);
        setFallbackBNFId(IdentificationVariableDeclarationBNF.ID);
        registerExpressionFactory(CollectionMemberDeclarationBNF.ID);
        registerChild(IdentificationVariableDeclarationBNF.ID);
    }
}