`/*
* (c) Copyright 2007, 2008 Hewlett-Packard Development Company, LP
* All rights reserved.
* [See end of file]
*/
package arq.examples;
import java.util.ArrayList;
import java.util.List;
import com.hp.hpl.jena.datatypes.xsd.XSDDatatype;
import com.hp.hpl.jena.graph.Node;
import com.hp.hpl.jena.graph.Triple;
import com.hp.hpl.jena.rdf.model.*;
import com.hp.hpl.jena.sparql.algebra.Algebra;
import com.hp.hpl.jena.sparql.algebra.Op;
import com.hp.hpl.jena.sparql.algebra.op.OpBGP;
import com.hp.hpl.jena.sparql.algebra.op.OpFilter;
import com.hp.hpl.jena.sparql.core.BasicPattern;
import com.hp.hpl.jena.sparql.core.Var;
import com.hp.hpl.jena.sparql.engine.QueryIterator;
import com.hp.hpl.jena.sparql.engine.ResultSetStream;
import com.hp.hpl.jena.sparql.engine.binding.Binding;
import com.hp.hpl.jena.sparql.expr.E_LessThan;
import com.hp.hpl.jena.sparql.expr.Expr;
import com.hp.hpl.jena.sparql.expr.NodeValue;
import com.hp.hpl.jena.sparql.expr.ExprVar;
import com.hp.hpl.jena.sparql.util.FmtUtils;
import com.hp.hpl.jena.query.ResultSet;
import com.hp.hpl.jena.query.ResultSetFormatter;
/** Build an algebra expression and execute it */
public class AlgebraExec
{
public static void main (String[] argv)
{
String BASE = "http://example/" ;
BasicPattern bp = new BasicPattern() ;
Var var_x = Var.alloc("x") ;
Var var_z = Var.alloc("z") ;
// ---- Build expression
bp.add(new Triple(var_x, Node.createURI(BASE+"p"), var_z)) ;
Op op = new OpBGP(bp) ;
//Expr expr = ExprUtils.parse("?z < 2 ") ;
Expr expr = new E_LessThan(new ExprVar(var_z), NodeValue.makeNodeInteger(2)) ;
op = OpFilter.filter(expr, op) ;
// ---- Example setup
Model m = makeModel() ;
m.write(System.out, "TTL") ;
System.out.println("--------------") ;
System.out.print(op) ;
System.out.println("--------------") ;
// ---- Execute expression
QueryIterator qIter = Algebra.exec(op, m.getGraph()) ;
// -------- Either read the query iterator directly ...
if ( false )
{
for ( ; qIter.hasNext() ; )
{
Binding b = qIter.nextBinding() ;
Node n = b.get(var_x) ;
System.out.println(FmtUtils.stringForNode(n)) ;
System.out.println(b) ;
}
qIter.close() ;
}
else
{
// -------- Or make ResultSet from it (but not both - reading an
// iterator consumes the current solution)
List varNames = new ArrayList() ;
varNames.add("x") ;
varNames.add("z") ;
ResultSet rs = new ResultSetStream(varNames, m, qIter);
ResultSetFormatter.out(rs) ;
qIter.close() ;
}
System.exit(0) ;
}
private static Model makeModel()
{
String BASE = "http://example/" ;
Model model = ModelFactory.createDefaultModel() ;
model.setNsPrefix("", BASE) ;
Resource r1 = model.createResource(BASE+"r1") ;
Resource r2 = model.createResource(BASE+"r2") ;
Property p1 = model.createProperty(BASE+"p") ;
Property p2 = model.createProperty(BASE+"p2") ;
RDFNode v1 = model.createTypedLiteral("1", XSDDatatype.XSDinteger) ;
RDFNode v2 = model.createTypedLiteral("2", XSDDatatype.XSDinteger) ;
r1.addProperty(p1, v1).addProperty(p1, v2) ;
r1.addProperty(p2, v1).addProperty(p2, v2) ;
r2.addProperty(p1, v1).addProperty(p1, v2) ;
return model ;
}
}
/*
* (c) Copyright 2007, 2008 Hewlett-Packard Development Company, LP
* 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 name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/`