/*
* 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.hadoop.rdf.io.input.readers;
import java.io.IOException;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.jena.graph.Node ;
import org.apache.jena.hadoop.rdf.io.registry.HadoopRdfIORegistry;
import org.apache.jena.hadoop.rdf.types.QuadWritable;
import org.apache.jena.riot.Lang;
import org.apache.jena.riot.RDFLanguages;
import org.apache.jena.sparql.core.Quad ;
/**
* A record reader that reads RDF from any triples/quads format. Triples are
* converted into quads in the default graph. This behaviour can be changed by
* deriving from this class and overriding the {@link #getGraphNode()} method
*
*
*
*/
@SuppressWarnings("javadoc")
public class TriplesOrQuadsReader extends AbstractRdfReader<Quad, QuadWritable> {
@Override
protected RecordReader<LongWritable, QuadWritable> selectRecordReader(Lang lang) throws IOException {
if (!RDFLanguages.isQuads(lang) && !RDFLanguages.isTriples(lang))
throw new IOException(lang.getLabel() + " is not a RDF triples/quads format");
if (HadoopRdfIORegistry.hasQuadReader(lang)) {
// Supports quads directly
return HadoopRdfIORegistry.createQuadReader(lang);
} else {
// Try to create a triples reader and wrap upwards into quads
// This will throw an error if a triple reader is not available
return new TriplesToQuadsReader(HadoopRdfIORegistry.createTripleReader(lang));
}
}
/**
* Gets the graph node which represents the graph into which triples will be
* indicated to belong to when they are converting into quads.
* <p>
* Defaults to {@link Quad#defaultGraphNodeGenerated} which represents the
* default graph
* </p>
*
* @return Graph node
*/
protected Node getGraphNode() {
return Quad.defaultGraphNodeGenerated;
}
}