/*
* 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.group;
import org.apache.jena.hadoop.rdf.types.NodeWritable;
import org.apache.jena.hadoop.rdf.types.QuadWritable;
import org.apache.jena.sparql.core.Quad ;
/**
* Abstract mapper implementation which helps in grouping quads by assigning
* them a {@link NodeWritable} key in place of their existing key. Derived
* implementations of this may select the key based on some component of the
* quad or by other custom logic.
*
*
*
* @param <TKey>
*/
public abstract class AbstractQuadGroupingMapper<TKey> extends AbstractNodeTupleGroupingMapper<TKey, Quad, QuadWritable> {
protected final NodeWritable selectKey(QuadWritable tuple) {
return this.selectKey(tuple.get());
}
/**
* Selects the key to use
*
* @param quad
* Quad
* @return Key to use
*/
protected abstract NodeWritable selectKey(Quad quad);
}