| /* |
| * 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 arq.examples; |
| |
| import org.apache.jena.query.Query ; |
| import org.apache.jena.query.QueryFactory ; |
| import org.apache.jena.sparql.algebra.Algebra ; |
| import org.apache.jena.sparql.algebra.Op ; |
| import org.apache.jena.sparql.engine.QueryIterator ; |
| import org.apache.jena.sparql.engine.binding.Binding ; |
| |
| /** Simple example to show parsing a query and producing the |
| * SPARQL algebra expression for the query. */ |
| public class AlgebraEx |
| { |
| public static void main(String []args) |
| { |
| String s = "SELECT DISTINCT ?s { ?s ?p ?o }"; |
| |
| // Parse |
| Query query = QueryFactory.create(s) ; |
| System.out.println(query) ; |
| |
| // Generate algebra |
| Op op = Algebra.compile(query) ; |
| op = Algebra.optimize(op) ; |
| System.out.println(op) ; |
| |
| // Execute it. |
| QueryIterator qIter = Algebra.exec(op, ExQuerySelect1.createModel()) ; |
| |
| // Results |
| for ( ; qIter.hasNext() ; ) |
| { |
| Binding b = qIter.nextBinding() ; |
| System.out.println(b) ; |
| } |
| qIter.close() ; |
| } |
| } |