UnionClauseFactory.java

/*******************************************************************************
 * Copyright (c) 2012, 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;

/**
 * This {@link UnionClauseFactory} creates a new {@link UnionClause} when the portion of the
 * query to parse starts with <b>UNION</b>, <code>INTERSECT</code> or <code>EXCEPT</code>.
 *
 * @see UnionClause
 * @version 2.4
 * @since 2.4
 * @author James Sutherland
 */
public final class UnionClauseFactory extends ExpressionFactory {

    /**
     * The unique identifier of this {@link UnionClauseFactory}.
     */
    public static final String ID = Expression.UNION;

    /**
     * Creates a new <code>UnionClauseFactory</code>.
     */
    public UnionClauseFactory() {
        super(ID, Expression.UNION,
                  Expression.INTERSECT,
                  Expression.EXCEPT);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected AbstractExpression buildExpression(AbstractExpression parent,
                                                 WordParser wordParser,
                                                 String word,
                                                 JPQLQueryBNF queryBNF,
                                                 AbstractExpression expression,
                                                 boolean tolerant) {

        expression = new UnionClause(parent, word);
        expression.parse(wordParser, tolerant);
        return expression;
    }
}