/*
 * Copyright (c) 2014, 2015, Dynatrace and/or its affiliates. All rights reserved.
 * 
 * This file is part of the Lock Contention Tracing Subsystem for the HotSpot
 * Virtual Machine, which is developed at Christian Doppler Laboratory on
 * Monitoring and Evolution of Very-Large-Scale Software Systems. Please
 * contact us at <http://mevss.jku.at/> if you need additional information
 * or have any questions.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work. If not, see <http://www.gnu.org/licenses/>.
 *
 */ 
package sun.evtracing.processing.statistics.aggregator;

public abstract class AggregatorFactory<T extends Aggregator> {
	private final AggregatorFactory<? extends Aggregator> nextFactory;
	private final AggregationConfiguration configuration;

	public AggregatorFactory(AggregationConfiguration configuration) {
		this(null, configuration);
	}

	public AggregatorFactory(AggregatorFactory<? extends Aggregator> nextFactory, AggregationConfiguration configuration) {
		this.nextFactory = nextFactory;
		this.configuration = configuration;
	}

	public abstract T create();

	public abstract T merge(T x, T y);

	public AggregationConfiguration configuration() {
		return configuration;
	}

	T mergeChecked(Aggregator x, Aggregator y) {
		if (x.factory() != this) {
			throw new IllegalArgumentException("aggregator x not an instance of factory");
		}
		if (y.factory() != this) {
			throw new IllegalArgumentException("aggregator y not an instance of factory");
		}
		@SuppressWarnings("unchecked")
		T xt = (T) x;
		@SuppressWarnings("unchecked")
		T yt = (T) y;
		return merge(xt, yt);
	}

	AggregatorFactory<? extends Aggregator> nextFactory() {
		return nextFactory;
	}
}