TypeExpression.java

/*******************************************************************************
 * Copyright (c) 2006, 2015 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;

import org.eclipse.persistence.jpa.jpql.WordParser;

/**
 * An entity type expression can be used to restrict query polymorphism. The <b>TYPE</b> operator
 * returns the exact type of the argument.
 * <p>
 * Part of JPA 2.0.
 *
 * <div><b>BNF:</b> <code>type_discriminator ::= TYPE(identification_variable |
 *                                                           single_valued_object_path_expression |
 *                                                           input_parameter)</code><p></div>
 *
 * @version 2.5
 * @since 2.3
 * @author Pascal Filion
 */
public final class TypeExpression extends AbstractSingleEncapsulatedExpression {

    /**
     * Creates a new <code>TypeExpression</code>.
     *
     * @param parent The parent of this expression
     */
    public TypeExpression(AbstractExpression parent) {
        super(parent, TYPE);
    }

    /**
     * {@inheritDoc}
     */
    public void accept(ExpressionVisitor visitor) {
        visitor.visit(this);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String getEncapsulatedExpressionQueryBNFId() {
        return InternalEntityTypeExpressionBNF.ID;
    }

    /**
     * {@inheritDoc}
     */
    public JPQLQueryBNF getQueryBNF() {
        return getQueryBNF(TypeExpressionBNF.ID);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected AbstractExpression parse(WordParser wordParser, String queryBNFId, boolean tolerant) {

        if (tolerant) {
            return super.parse(wordParser, queryBNFId, tolerant);
        }

        return buildExpressionFromFallingBack(
            wordParser,
            wordParser.word(),
            getQueryBNF(InternalEntityTypeExpressionBNF.ID),
            null,
            tolerant
        );
    }
}