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

/**
 * This operator does a logical comparison of a constant with a tuple.
 * <p>
 *
 * @see If the constant is equal to tuple, then the pair is
 *      emitted on equalTo, greaterThanEqualTo, and lessThanEqualTo ports. If
 *      the constant is less than tuple, then the pair is emitted on notEqualTo,
 *      lessThan and lessThanEqualTo ports. If the constant is greater than
 *      tuple, then the pair is emitted on notEqualTo, greaterThan and
 *      greaterThanEqualTo ports. This is a pass through operator
 *      <p>
 *      <br>
 *      StateFull : No, comparison is done in current window. <br>
 *      Partitions : Yes, no state dependency among input tuples. <br>
 *      <br>
 *      <b>Ports</b>:<br>
 *      <b>input</b>: expects T<br>
 *      <b>equalTo</b>: emits T<br>
 *      <b>notEqualTo</b>: emits T<br>
 *      <b>greaterThanEqualTo</b>: emits T<br>
 *      <b>greaterThan</b>: emits T<br>
 *      <b>lessThanEqualTo</b>: emits T<br>
 *      <b>lessThan</b>: emits T<br>
 *      <br>
 * @displayname: Logical Compare To Constant
 * @category: math
 * @tags: comparison, logical, key value, constant
 * @since 0.3.3
 */
@Stateless
public class LogicalCompareToConstant<T extends Comparable<? super T>> extends
		BaseOperator
{

	/**
	 * Compare constant, set by application.
	 */
	private T constant;

	/**
	 * Input port that takes a comparable to compare it with a constant.
	 */
	public final transient DefaultInputPort<T> input = new DefaultInputPort<T>()
	{
		@Override
		public void process(T tuple)
		{
			int i = constant.compareTo(tuple);
			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<T> equalTo = new DefaultOutputPort<T>();

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

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

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

	/**
	 * Set constant for comparison.
	 * 
	 * @param constant
	 *          the constant to set
	 */
	public void setConstant(T constant)
	{
		this.constant = constant;
	}

	/**
	 * returns the value of constant
	 */
	public T getConstant()
	{
		return constant;
	}
}