jena-arq/src/main/java/org/apache/jena/sparql/engine/iterator/QueryIteratorCopy.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 java.util.ArrayList ;
import java.util.Collections ;
import java.util.List ;

import org.apache.jena.atlas.io.IndentedWriter ;
import org.apache.jena.sparql.engine.QueryIterator ;
import org.apache.jena.sparql.engine.binding.Binding ;
import org.apache.jena.sparql.serializer.SerializationContext ;

/** A QueryIterator that copies an iterator.
 *  @see QueryIter#materialize
 */  

class QueryIteratorCopy extends QueryIteratorBase
{
    // Not tracked.
    List<Binding> elements = new ArrayList<>() ;
    QueryIterator iterator ;
    
    QueryIterator original ;        // Keep for debugging - This is closed as it is copied.
    
    public QueryIteratorCopy(QueryIterator qIter)
    {
        for ( ; qIter.hasNext() ; )
            elements.add(qIter.nextBinding()) ;
        qIter.close() ;
        iterator = copy() ;
        original = qIter ;
    }

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

    @Override
    public void output(IndentedWriter out, SerializationContext sCxt)
    {
        out.print("QueryIteratorCopy") ;
        out.incIndent() ;
        original.output(out, sCxt) ;
        out.decIndent() ;
    }
    
    
    public List<Binding> elements()
    {
        return Collections.unmodifiableList(elements) ;
    }
    
    public QueryIterator copy()
    {
        return new QueryIterPlainWrapper(elements.iterator()) ;
    }

    @Override
    protected void closeIterator()
    { iterator.close() ; }
    
    @Override
    protected void requestCancel()
    { iterator.cancel() ; }

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