/*
* 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.mapreduce.count.datatypes;
import org.apache.jena.graph.Node ;
import org.apache.jena.graph.NodeFactory ;
import org.apache.jena.hadoop.rdf.mapreduce.count.NodeCountReducer;
import org.apache.jena.hadoop.rdf.mapreduce.count.TripleNodeCountMapper;
import org.apache.jena.hadoop.rdf.types.NodeWritable;
import org.apache.jena.hadoop.rdf.types.TripleWritable;
/**
* A mapper for counting data type usages within triples designed primarily for
* use in conjunction with {@link NodeCountReducer}
* <p>
* This mapper extracts the data types for typed literal objects and converts
* them into nodes so they can be counted
* </p>
*
*
*
* @param <TKey>
* Key type
*/
public class TripleDataTypeCountMapper<TKey> extends TripleNodeCountMapper<TKey> {
private static final NodeWritable[] EMPTY = new NodeWritable[0];
@Override
protected NodeWritable[] getNodes(TripleWritable tuple) {
Node object = tuple.get().getObject();
if (!object.isLiteral())
return EMPTY;
String dtUri = object.getLiteralDatatypeURI();
if (dtUri == null)
return EMPTY;
return new NodeWritable[] { new NodeWritable(NodeFactory.createURI(dtUri)) };
}
}