/*
* $Header$
* $Revision: 982 $
* $Date: 2006-12-08 18:42:51 +1000 (Fri, 08 Dec 2006) $
*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 2003-2009 The JRDF Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* the JRDF Project (http://jrdf.sf.net/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The JRDF Project" and "JRDF" must not be used to endorse
* or promote products derived from this software without prior written
* permission. For written permission, please contact
* newmana@users.sourceforge.net.
*
* 5. Products derived from this software may not be called "JRDF"
* nor may "JRDF" appear in their names without prior written
* permission of the JRDF Project.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the JRDF Project. For more
* information on JRDF, please see <http://jrdf.sourceforge.net/>.
*
*/
package org.jrdf.sparql;
import org.jrdf.graph.Graph;
import org.jrdf.graph.GraphException;
import org.jrdf.query.AskQueryImpl;
import org.jrdf.query.InvalidQuerySyntaxException;
import org.jrdf.query.Query;
import org.jrdf.query.answer.Answer;
import org.jrdf.query.answer.AskAnswerImpl;
import static org.jrdf.query.answer.EmptySelectAnswer.EMPTY_ANSWER;
import org.jrdf.query.execute.QueryEngine;
import org.jrdf.sparql.builder.QueryBuilder;
import static org.jrdf.util.param.ParameterUtil.checkNotEmptyString;
import static org.jrdf.util.param.ParameterUtil.checkNotNull;
/**
* Default implementation of a {@link SparqlConnection}.
*
* @author Tom Adams
* @version $Id: SparqlConnectionImpl.java 982 2006-12-08 08:42:51Z newmana $
*/
public final class SparqlConnectionImpl implements SparqlConnection {
// FIXME TJA: Ensure connections are threadsafe.
private final QueryBuilder builder;
private final QueryEngine queryEngine;
/**
* Creates a new SPARQL connection.
*
* @param newBuilder the query builder that builds queries.
* @param newQueryEngine the engine that executed the query.
*/
public SparqlConnectionImpl(QueryBuilder newBuilder, QueryEngine newQueryEngine) {
checkNotNull(newBuilder, newQueryEngine);
this.queryEngine = newQueryEngine;
this.builder = newBuilder;
}
public Answer executeQuery(Graph graph, String queryText) throws InvalidQuerySyntaxException, GraphException {
checkNotNull(graph, queryText);
checkNotEmptyString("queryText", queryText);
Query query = builder.buildQuery(graph, queryText);
if (graph.isEmpty()) {
return getEmptyAnswer(query);
}
return query.executeQuery(graph, queryEngine);
}
private Answer getEmptyAnswer(Query query) {
if (query instanceof AskQueryImpl) {
return new AskAnswerImpl(0, false);
} else {
return EMPTY_ANSWER;
}
}
}