crunch-core/src/main/java/org/apache/crunch/types/writable/WritablePairConverter.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.crunch.types.writable;

import org.apache.crunch.Pair;
import org.apache.crunch.types.Converter;

class WritablePairConverter<K, V> implements Converter<K, V, Pair<K, V>, Pair<K, Iterable<V>>> {

  private final Class<K> keyClass;
  private final Class<V> valueClass;

  public WritablePairConverter(Class<K> keyClass, Class<V> valueClass) {
    this.keyClass = keyClass;
    this.valueClass = valueClass;
  }

  @Override
  public Pair<K, V> convertInput(K key, V value) {
    return Pair.of(key, value);
  }

  @Override
  public K outputKey(Pair<K, V> value) {
    return value.first();
  }

  @Override
  public V outputValue(Pair<K, V> value) {
    return value.second();
  }

  @Override
  public Class<K> getKeyClass() {
    return keyClass;
  }

  @Override
  public Class<V> getValueClass() {
    return valueClass;
  }

  @Override
  public boolean applyPTypeTransforms() {
    return true;
  }

  @Override
  public Pair<K, Iterable<V>> convertIterableInput(K key, Iterable<V> value) {
    return Pair.of(key, value);
  }
}