library/src/main/java/com/datatorrent/lib/stream/KeyValPairToHashMap.java

/*
 * Copyright (c) 2013 DataTorrent, Inc. ALL Rights Reserved.
 *
 * Licensed 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 com.datatorrent.lib.stream;

import com.datatorrent.api.DefaultInputPort;
import com.datatorrent.api.DefaultOutputPort;
import com.datatorrent.api.annotation.InputPortFieldAnnotation;
import com.datatorrent.api.annotation.OutputPortFieldAnnotation;
import com.datatorrent.api.annotation.Stateless;
import com.datatorrent.lib.util.BaseKeyValueOperator;
import com.datatorrent.lib.util.KeyValPair;
import java.util.HashMap;

/**
 * An implementation of BaseKeyValueOperator that converts Key Value Pair to a HashMap tuple. 
 * <p>
 * Takes a KeyValPair and emits a HashMap(1), Used for for converting KeyValPair
 * to a HashMap(1) tuple
 * <p>
 * This is a pass through operator<br>
 * <br>
 * <b>Ports</b>:<br>
 * <b>keyval</b>: expects KeyValPair&lt;K,V&gt;<br>
 * <b>map</b>: emits HashMap&lt;K,V&gt;<br>
 * <br>
 * @displayName: Key Value Pair To HashMap
 * @category: stream
 * @tag: key value
 * @since 0.3.3
 */
@Stateless
public class KeyValPairToHashMap<K, V> extends BaseKeyValueOperator<K, V>
{
	/**
	 * Input port that takes a key value pair.
	 */
	@InputPortFieldAnnotation(name = "data")
	public final transient DefaultInputPort<KeyValPair<K, V>> keyval = new DefaultInputPort<KeyValPair<K, V>>()
	{
		/**
		 * Emits key, key/val pair, and val based on port connections
		 */
		@Override
		public void process(KeyValPair<K, V> tuple)
		{
			HashMap<K, V> otuple = new HashMap<K, V>(1);
			otuple.put(tuple.getKey(), tuple.getValue());
			map.emit(otuple);
		}
	};

	/**
	 * key/value map output port.
	 */
	@OutputPortFieldAnnotation(name = "map")
	public final transient DefaultOutputPort<HashMap<K, V>> map = new DefaultOutputPort<HashMap<K, V>>();
}