//******************************************************************************
//
// File:    ItemHolder.java
// Package: edu.rit.pj
// Unit:    Class edu.rit.pj.ItemHolder
//
// This Java source file is copyright (C) 2007 by Alan Kaminsky. All rights
// reserved. For further information, contact the author, Alan Kaminsky, at
// ark@cs.rit.edu.
//
// This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
// software; you can redistribute it and/or modify it under the terms of the GNU
// General Public License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// PJ is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
//
// Linking this library statically or dynamically with other modules is making a
// combined work based on this library. Thus, the terms and conditions of the
// GNU General Public License cover the whole combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent modules, and
// to copy and distribute the resulting executable under terms of your choice,
// provided that you also meet, for each linked independent module, the terms
// and conditions of the license of that module. An independent module is a
// module which is not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the library, but
// you are not obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
//
// A copy of the GNU General Public License is provided in the file gpl.txt. You
// may also obtain a copy of the GNU General Public License on the World Wide
// Web at http://www.gnu.org/licenses/gpl.html.
//
//******************************************************************************

package edu.rit.pj;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

/**
 * Class ItemHolder provides an object that holds one item to be processed
 * by a {@linkplain ParallelIteration} along with associated information.
 *
 * @param  <T>  Data type of the items iterated over.
 *
 * @author  Alan Kaminsky
 * @version 07-Oct-2010
 */
class ItemHolder<T>
	implements Externalizable
	{

// Hidden data members.

	private static final long serialVersionUID = -5475933248018589590L;

// Exported data members.

	/**
	 * The item itself (may be null).
	 */
	public T myItem;

	/**
	 * The item's sequence number in the iteration. Sequence numbers start
	 * at 0 and increase by 1 for each item.
	 */
	public int mySequenceNumber;

// Exported constructors.

	/**
	 * Construct a new item holder.
	 */
	public ItemHolder()
		{
		}

// Exported operations.

	/**
	 * Write this object holder to the given object output stream.
	 *
	 * @param  out  Object output stream.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void writeExternal
		(ObjectOutput out)
		throws IOException
		{
		out.writeObject (myItem);
		out.writeInt (mySequenceNumber);
		}

	/**
	 * Read this object holder from the given object input stream.
	 *
	 * @param  in  Object input stream.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 * @exception  ClassNotFoundException
	 *     Thrown if the class of the object could not be found.
	 */
	public void readExternal
		(ObjectInput in)
		throws IOException, ClassNotFoundException
		{
		myItem = (T) in.readObject();
		mySequenceNumber = in.readInt();
		}

	}
