AndExpressionFactory.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;

/**
 * This {@link AndExpression} creates a new {@link AdditionExpression} when the portion of the query
 * to parse starts with <b>AND</b>.
 *
 * @see AndExpression
 *
 * @version 2.4
 * @since 2.3
 * @author Pascal Filion
 */
public final class AndExpressionFactory extends ExpressionFactory {

    /**
     * This {@link ExpressionVisitor} is used to check if the {@link Expression}
     * passed to this factory is an {@link OrExpression}.
     */
    private OrExpressionVisitor visitor;

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

    /**
     * Creates a new <code>AndExpressionFactory</code>.
     */
    public AndExpressionFactory() {
        super(ID, Expression.AND);
    }

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

        if (expression != null) {
            expression.accept(visitor());
        }

        if ((visitor != null) && visitor.found) {
            visitor.found = false;
            OrExpression orExpression = (OrExpression) expression;

            AndExpression andExpression = new AndExpression(parent);
            andExpression.setLeftExpression((AbstractExpression) orExpression.getRightExpression());
            andExpression.parse(wordParser, tolerant);
            orExpression.setRightExpression(andExpression);

            return orExpression;
        }
        else {
            AndExpression andExpression = new AndExpression(parent);

            if (expression != null) {
                andExpression.setLeftExpression(expression);
            }

            andExpression.parse(wordParser, tolerant);
            return andExpression;
        }
    }

    private OrExpressionVisitor visitor() {
        if (visitor == null) {
            visitor = new OrExpressionVisitor();
        }
        return visitor;
    }

    // Made static final for performance reasons.
    /**
     * This {@link ExpressionVisitor} is used to check if the {@link Expression} passed to this
     * factory is an {@link OrExpression}.
     */
    private static final class OrExpressionVisitor extends AbstractExpressionVisitor {

        /**
         * This flag is turned on if the {@link Expression} visited is {@link OrExpression}.
         */
        boolean found;

        /**
         * {@inheritDoc}
         */
        @Override
        public void visit(OrExpression expression) {
            found = true;
        }
    }
}