/*
 * Copyright (c) 2006, 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;

import org.eclipse.persistence.jpa.jpql.EclipseLinkVersion;
import org.eclipse.persistence.jpa.jpql.JPAVersion;

/**
 * <p>This {@link JPQLGrammar} provides support for parsing JPQL queries defined in <a
 * href="http://jcp.org/en/jsr/detail?id=317">JSR-337 - Java Persistence 2.0</a>. EclipseLink 2.0
 * does not add any additional support.</p>
 *
 * The BNFs of the additional support are the following:
 *
 * <pre><code> in_expression ::= in_expression_expression [NOT] IN { ( in_item {, in_item}* ) | (subquery) | collection_valued_input_parameter }
 *
 * in_expression_expression ::= { state_field_path_expression | type_discriminator |
 *                                single_valued_input_parameter | identification_variable }</code></pre>
 *
 * <p>Provisional API: This interface is part of an interim API that is still under development and
 * expected to change significantly before reaching stability. It is available at this early stage
 * to solicit feedback from pioneering adopters on the understanding that any code that uses this
 * API will almost certainly be broken (repeatedly) as the API evolves.</p>
 *
 * @version 2.5
 * @since 2.4
 * @author Pascal Filion
 */
@SuppressWarnings("nls")
public final class EclipseLinkJPQLGrammar2_0 extends AbstractJPQLGrammar {

    /**
     * The singleton instance of this {@link EclipseLinkJPQLGrammar2_0}.
     */
    private static final JPQLGrammar INSTANCE = new EclipseLinkJPQLGrammar2_0();

    /**
     * The EclipseLink version, which is 2.0.
     */
    public static final EclipseLinkVersion VERSION = EclipseLinkVersion.VERSION_2_0;

    /**
     * Creates a new <code>EclipseLinkJPQLGrammar2_0</code>.
     */
    public EclipseLinkJPQLGrammar2_0() {
        super();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String getProvider() {
        return DefaultEclipseLinkJPQLGrammar.PROVIDER_NAME;
    }

    /**
     * Creates a new <code>EclipseLinkJPQLGrammar2_0</code>.
     *
     * @param jpqlGrammar The {@link JPQLGrammar} to extend with the content of this one without
     * instantiating the base {@link JPQLGrammar}
     */
    private EclipseLinkJPQLGrammar2_0(AbstractJPQLGrammar jpqlGrammar) {
        super(jpqlGrammar);
    }

    /**
     * Extends the given {@link JPQLGrammar} with the information of this one without instantiating
     * the base {@link JPQLGrammar}.
     *
     * @param jpqlGrammar The {@link JPQLGrammar} to extend with the content of this one without
     * instantiating the base {@link JPQLGrammar}
     */
    public static void extend(AbstractJPQLGrammar jpqlGrammar) {
        new EclipseLinkJPQLGrammar2_0(jpqlGrammar);
    }

    /**
     * Returns the singleton instance of this class.
     *
     * @return The {@link EclipseLinkJPQLGrammar2_0}
     */
    public static JPQLGrammar instance() {
        return INSTANCE;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected JPQLGrammar buildBaseGrammar() {
        return new JPQLGrammar2_0();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public JPAVersion getJPAVersion() {
        return JPAVersion.VERSION_2_0;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String getProviderVersion() {
        return VERSION.getVersion();
    }

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

        // The expression left to IN can be an identification variable or input parameter
        addChildBNF(InExpressionExpressionBNF.ID, IdentificationVariableBNF.ID);
        addChildBNF(InExpressionExpressionBNF.ID, InputParameterBNF.ID);
    }

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

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

    /**
     * {@inheritDoc}
     */
    @Override
    public String toString() {
        return "EclipseLink 2.0";
    }
}