001    /*
002     * Cumulus4j - Securing your data in the cloud - http://cumulus4j.org
003     * Copyright (C) 2011 NightLabs Consulting GmbH
004     *
005     * This program is free software: you can redistribute it and/or modify
006     * it under the terms of the GNU Affero General Public License as
007     * published by the Free Software Foundation, either version 3 of the
008     * License, or (at your option) any later version.
009     *
010     * This program is distributed in the hope that it will be useful,
011     * but WITHOUT ANY WARRANTY; without even the implied warranty of
012     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
013     * GNU Affero General Public License for more details.
014     *
015     * You should have received a copy of the GNU Affero General Public License
016     * along with this program.  If not, see <http://www.gnu.org/licenses/>.
017     */
018    package org.cumulus4j.store.query.eval;
019    
020    import java.util.Set;
021    
022    import org.cumulus4j.store.query.QueryEvaluator;
023    import org.datanucleus.query.QueryUtils;
024    import org.datanucleus.query.expression.ParameterExpression;
025    
026    /**
027     * Evaluator representing query parameters.
028     *
029     * @author Marco หงุ่ยตระกูล-Schulze - marco at nightlabs dot de
030     * @see ParameterExpression
031     */
032    public class ParameterExpressionEvaluator
033    extends AbstractExpressionEvaluator<ParameterExpression>
034    {
035            public ParameterExpressionEvaluator(QueryEvaluator queryEvaluator, AbstractExpressionEvaluator<?> parent, ParameterExpression expression) {
036                    super(queryEvaluator, parent, expression);
037            }
038    
039            @Override
040            protected Set<Long> _queryResultDataEntryIDs(ResultDescriptor resultDescriptor)
041            {
042                    throw new UnsupportedOperationException("It is impossible to get a result set for a ParameterExpression alone!");
043            }
044    
045            public Object getParameterValue()
046            {
047                    return QueryUtils.getValueForParameterExpression(getQueryEvaluator().getParameterValues(), getExpression());
048            }
049    }