library/src/main/java/com/datatorrent/lib/math/LogicalCompare.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.math;

import com.datatorrent.api.BaseOperator;
import com.datatorrent.api.DefaultInputPort;
import com.datatorrent.api.DefaultOutputPort;
import com.datatorrent.api.annotation.Stateless;
import com.datatorrent.common.util.Pair;

/**
 * This operator compares the two values in a given pair <T,T> object which are of the comparable property, and emits the pair on appropriate port denoting the result of the comparison.
 * <p>
 * If the first value is equal to second value, then the pair is emitted on equalTo, greaterThanEqualTo, and lessThanEqualTo ports.
 * If the first value is less than second value, then the pair is emitted on notEqualTo, lessThan and lessThanEqualTo ports.
 * If the first value is greater than second value, then the pair is emitted on notEqualTo, greaterThan and greaterThanEqualTo ports. 
 * This is a pass through operator.
 * <br>
 * StateFull : No, output is computed during current window. <br>
 * Partitions : Yes, no dependency among input tuples. <br>
 * <br>
 * <b>Ports</b>:<br>
 * <b>input</b>: expects Pair&lt;T,T&gt;<br>
 * <b>equalTo</b>: emits Pair&lt;T,T&gt;<br>
 * <b>notEqualTo</b>: emits Pair&lt;T,T&gt;<br>
 * <b>greaterThanEqualTo</b>: emits Pair&lt;T,T&gt;<br>
 * <b>greaterThan</b>: emits Pair&lt;T,T&gt;<br>
 * <b>lessThanEqualTo</b>: emits Pair&lt;T,T&gt;<br>
 * <b>lessThan</b>: emits Pair&lt;T,T&gt;<br>
 * <br>
 * @displayname: Logical Compare
 * @category: math
 * @tags: comparison, logical, key value
 * @since 0.3.3
 */
@Stateless
public abstract class LogicalCompare<T extends Comparable<? super T>> extends
		BaseOperator
{
	/**
	 * Input port that takes a key, value pair for comparison.
	 */
	public final transient DefaultInputPort<Pair<T, T>> input = new DefaultInputPort<Pair<T, T>>()
	{
		@Override
		public void process(Pair<T, T> tuple)
		{
			int i = tuple.first.compareTo(tuple.second);
			if (i > 0) {
				greaterThan.emit(tuple);
				greaterThanOrEqualTo.emit(tuple);
				notEqualTo.emit(tuple);
			} else if (i < 0) {
				lessThan.emit(tuple);
				lessThanOrEqualTo.emit(tuple);
				notEqualTo.emit(tuple);
			} else {
				equalTo.emit(tuple);
				lessThanOrEqualTo.emit(tuple);
				greaterThanOrEqualTo.emit(tuple);
			}
		}

	};

	/**
	 * Equal output port.
	 */
	public final transient DefaultOutputPort<Pair<T, T>> equalTo = new DefaultOutputPort<Pair<T, T>>();

	/**
	 * Not Equal output port.
	 */
	public final transient DefaultOutputPort<Pair<T, T>> notEqualTo = new DefaultOutputPort<Pair<T, T>>();

	/**
	 * Less than output port.
	 */
	public final transient DefaultOutputPort<Pair<T, T>> lessThan = new DefaultOutputPort<Pair<T, T>>();

	/**
	 * Greater than output port.
	 */
	public final transient DefaultOutputPort<Pair<T, T>> greaterThan = new DefaultOutputPort<Pair<T, T>>();

	/**
	 * Less than equal to output port.
	 */
	public final transient DefaultOutputPort<Pair<T, T>> lessThanOrEqualTo = new DefaultOutputPort<Pair<T, T>>();

	/**
	 * Greater than equal to output port.
	 */
	public final transient DefaultOutputPort<Pair<T, T>> greaterThanOrEqualTo = new DefaultOutputPort<Pair<T, T>>();
}