/**
* Copyright (c) 2013, Institute of Information Systems (Sven Groppe and contributors of LUPOSDATE), University of Luebeck
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
* following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this list of conditions and the following
* disclaimer.
* - 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.
* - Neither the name of the University of Luebeck nor the names of its contributors may be used to endorse or promote
* products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS 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 COPYRIGHT HOLDER OR 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.
*/
package lupos.engine.operators.index;
import java.net.URISyntaxException;
import java.util.Collection;
import lupos.datastructures.bindings.Bindings;
import lupos.datastructures.bindings.BindingsFactory;
import lupos.datastructures.items.Item;
import lupos.datastructures.items.Triple;
import lupos.datastructures.items.Variable;
import lupos.datastructures.items.literal.LiteralFactory;
import lupos.datastructures.queryresult.QueryResult;
import lupos.engine.operators.OperatorIDTuple;
import lupos.engine.operators.messages.BindingsFactoryMessage;
import lupos.engine.operators.messages.Message;
import lupos.rdf.Prefix;
public class EmptyIndexScanSubmittingQueryResultWithOneEmptyBindings extends EmptyIndexScan {
protected final Root root;
protected final Item rdfGraph;
protected BindingsFactory bindingsFactory;
/**
*
*/
private static final long serialVersionUID = -6813056199050211285L;
public EmptyIndexScanSubmittingQueryResultWithOneEmptyBindings(final OperatorIDTuple succeedingOperator,
final Item graphConstraint,
final lupos.engine.operators.index.Root root_param) {
super(succeedingOperator);
this.root = root_param;
this.rdfGraph = graphConstraint;
}
@Override
public Message preProcessMessage(final BindingsFactoryMessage msg){
this.bindingsFactory = msg.getBindingsFactory();
return msg;
}
/**
* Creating a new query result with an empty binding to handle an empty BIND
* statement
*
* @param Dataset
*/
@Override
public QueryResult process(final Dataset dataset) {
final QueryResult queryResult = QueryResult.createInstance();
if(this.rdfGraph!=null && this.rdfGraph.isVariable()){
final Variable graphConstraint = (Variable) this.rdfGraph;
if (this.root.namedGraphs != null && this.root.namedGraphs.size() > 0) {
// Convert the named graphs' names into URILiterals
// to be applicable later on
for (final String name : this.root.namedGraphs) {
final Bindings graphConstraintBindings = this.bindingsFactory.createInstance();
try {
graphConstraintBindings.add(graphConstraint, LiteralFactory.createURILiteralWithoutLazyLiteral(name));
} catch (final URISyntaxException e) {
System.err.println(e);
e.printStackTrace();
}
queryResult.add(graphConstraintBindings);
}
} else {
final Collection<Indices> dataSetIndices = dataset.getNamedGraphIndices();
if (dataSetIndices != null) {
for (final Indices indices : dataSetIndices) {
final Bindings graphConstraintBindings = this.bindingsFactory.createInstance();
graphConstraintBindings.add(graphConstraint, indices.getRdfName());
queryResult.add(graphConstraintBindings);
}
}
}
} else {
queryResult.add(this.bindingsFactory.createInstance());
}
return queryResult;
}
@Override
public String toString() {
return super.toString()+"\nReturning queryResult with one empty bindings";
}
@Override
public String toString(final Prefix prefix) {
return super.toString(prefix)+"\nReturning queryResult with one empty bindings";
}
// just for using this also for the stream engine
protected boolean firstTime = true;
@Override
public void consume(final Triple triple) {
if(this.firstTime){
this.firstTime = false;
this.processAtSucceedingOperators(QueryResult.createInstance(this.bindingsFactory.createInstance()));
}
}
}