core/src/main/scala/org/apache/spark/api/java/function/PairFunction.java


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45

/*
 * 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.spark.api.java.function;

import scala.Tuple2;
import scala.reflect.ClassManifest;
import scala.reflect.ClassManifest$;
import scala.runtime.AbstractFunction1;

import java.io.Serializable;

/**
 * A function that returns key-value pairs (Tuple2<K, V>), and can be used to construct PairRDDs.
 */
// PairFunction does not extend Function because some UDF functions, like map,
// are overloaded for both Function and PairFunction.
public abstract class PairFunction<T, K, V>
  extends WrappedFunction1<T, Tuple2<K, V>>
  implements Serializable {

  public abstract Tuple2<K, V> call(T t) throws Exception;

  public ClassManifest<K> keyType() {
    return (ClassManifest<K>) ClassManifest$.MODULE$.fromClass(Object.class);
  }

  public ClassManifest<V> valueType() {
    return (ClassManifest<V>) ClassManifest$.MODULE$.fromClass(Object.class);
  }
}