crunch-core/src/main/java/org/apache/crunch/types/writable/WritableValueConverter.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.types.Converter;
import org.apache.hadoop.io.NullWritable;

class WritableValueConverter<W> implements Converter<Object, W, W, Iterable<W>> {

  private final Class<W> serializationClass;

  public WritableValueConverter(Class<W> serializationClass) {
    this.serializationClass = serializationClass;
  }

  @Override
  public W convertInput(Object key, W value) {
    return value;
  }

  @Override
  public Object outputKey(W value) {
    return NullWritable.get();
  }

  @Override
  public W outputValue(W value) {
    return value;
  }

  @Override
  public Class<Object> getKeyClass() {
    return (Class<Object>) (Class<?>) NullWritable.class;
  }

  @Override
  public Class<W> getValueClass() {
    return serializationClass;
  }

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

  @Override
  public Iterable<W> convertIterableInput(Object key, Iterable<W> value) {
    return value;
  }
}