/*
 * JasperReports - Free Java Reporting Library.
 * Copyright (C) 2001 - 2019 TIBCO Software Inc. All rights reserved.
 * http://www.jaspersoft.com
 *
 * Unless you have purchased a commercial license agreement from Jaspersoft,
 * the following license terms apply:
 *
 * This program is part of JasperReports.
 *
 * JasperReports is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * JasperReports 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with JasperReports. If not, see <http://www.gnu.org/licenses/>.
 */
package net.sf.jasperreports.util;

import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Supplier;

/**
 * 
 * @author Lucian Chirita (lucianc@users.sourceforge.net)
 */
public class CachingSupplier
{

	public static <T> Supplier<T> wrap(Supplier<T> supplier)
	{
		AtomicReference<T> ref = new AtomicReference<>();
		return () ->
		{
			T value = ref.get();
			if (value == null)
			{
				value = supplier.get();
				if (value == null)
				{
					throw new IllegalArgumentException("Supplier returned null");
				}
				ref.set(value);
			}
			return value;
		};
	}

}
