/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.clerezza.rdf.core.sparql;
import java.io.StringReader;
import java.util.HashSet;
import java.util.Set;
import org.apache.clerezza.rdf.core.UriRef;
import org.apache.clerezza.rdf.core.access.TcProvider;
import org.apache.clerezza.rdf.core.sparql.query.DataSet;
import org.apache.clerezza.rdf.core.sparql.query.Query;
import org.apache.clerezza.rdf.core.sparql.query.SparqlUnit;
import org.apache.clerezza.rdf.core.sparql.update.Update;
/**
* This class implements an OSGi service to provide a method to obtain referred Graphs in a SPARQL Query or Update.
*
* @author hasan
*/
public class SparqlPreParser {
TcProvider tcProvider;
public SparqlPreParser() {
}
public SparqlPreParser(TcProvider tcProvider) {
this.tcProvider = tcProvider;
}
/**
* This returns the graphs targeted by the queryString. This are the the
* triple collections explicitely refreded in FROM and FROM NAMED clauses,
* and if the queryString contains no FROM clause the defaultGraph.
*
* For queries that are not limited to specified set of graphs null is returned.
*
*
* @param queryString
* @param defaultGraph
* @return
* @throws ParseException
*/
public Set<UriRef> getReferredGraphs(String queryString, UriRef defaultGraph) throws ParseException {
Set<UriRef> referredGraphs;
JavaCCGeneratedSparqlPreParser parser = new JavaCCGeneratedSparqlPreParser(new StringReader(queryString));
SparqlUnit sparqlUnit;
sparqlUnit = parser.parse();
if (sparqlUnit.isQuery()) {
Query q = sparqlUnit.getQuery();
DataSet dataSet = q.getDataSet();
if (dataSet != null) {
referredGraphs = dataSet.getDefaultGraphs();
referredGraphs.addAll(dataSet.getNamedGraphs());
} else {
referredGraphs = new HashSet<UriRef>();
}
} else {
Update u = sparqlUnit.getUpdate();
referredGraphs = u.getReferredGraphs(defaultGraph, tcProvider);
}
if (referredGraphs.isEmpty()) {
return null;
// referredGraphs.add(defaultGraph);
}
return referredGraphs;
}
}