jena-arq/src/main/java/org/apache/jena/sparql/engine/iterator/QueryIterBlockTriplesStar.java

/*
 * 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.jena.sparql.engine.iterator;

import org.apache.jena.atlas.io.IndentedWriter;
import org.apache.jena.graph.Triple;
import org.apache.jena.sparql.core.BasicPattern;
import org.apache.jena.sparql.engine.ExecutionContext;
import org.apache.jena.sparql.engine.QueryIterator;
import org.apache.jena.sparql.engine.binding.Binding;
import org.apache.jena.sparql.serializer.SerializationContext;

/**
 * Like {@link QueryIterBlockTriples} except it process triple term patterns (RDF*)
 * as well.
 */
public class QueryIterBlockTriplesStar extends QueryIter1 {

    public static QueryIterator create(QueryIterator input, BasicPattern pattern, ExecutionContext execContext) {
        return new QueryIterBlockTriplesStar(input, pattern, execContext);
    }

    private final BasicPattern pattern;
    private QueryIterator output;

    private QueryIterBlockTriplesStar(QueryIterator input, BasicPattern pattern, ExecutionContext execContext) {
        super(input, execContext);
        this.pattern = pattern;
        QueryIterator chain = getInput();
        for (Triple triple : pattern) {
            chain = RX.rdfStarTriple(chain, triple, execContext);
        }
        output = chain;
    }

    @Override
    protected boolean hasNextBinding() {
        return output.hasNext();
    }

    @Override
    protected Binding moveToNextBinding() {
        return output.nextBinding();
    }

    @Override
    protected void closeSubIterator() {
        if ( output != null )
            output.close();
        output = null;
    }

    @Override
    protected void requestSubCancel() {
        if ( output != null )
            output.cancel();
    }

    @Override
    protected void details(IndentedWriter out, SerializationContext sCxt) {
        out.print(this.getClass().getSimpleName()+": " + pattern);
    }
}