/*
 * Bytecode Analysis Framework
 * Copyright (C) 2003,2004 University of Maryland
 * 
 * This library 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 2.1 of the License, or (at your option) any later version.
 * 
 * This library 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 this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.ba;

import java.util.Comparator;

/**
 * A BlockOrder for visiting the blocks of a CFG in
 * the order they would be visited in a depth first search
 * of the reversed CFG.  This is the most efficient visitation
 * order for backwards dataflow analyses.
 *
 * @see BlockOrder
 * @see ReverseDepthFirstSearch
 * @see CFG
 * @see BasicBlock
 */
public class ReverseDFSOrder extends AbstractBlockOrder {
	public ReverseDepthFirstSearch rdfs;
	public DepthFirstSearch dfs;
	private static class ReverseDFSComparator implements Comparator<BasicBlock> {
		public ReverseDepthFirstSearch rdfs;
		public DepthFirstSearch dfs;
		public ReverseDFSComparator(ReverseDepthFirstSearch rdfs, DepthFirstSearch dfs) {
			if (rdfs == null) throw new IllegalArgumentException();
			this.rdfs = rdfs;
			if (dfs == null) throw new IllegalArgumentException();
			this.dfs = dfs;
		}
		public int compare(BasicBlock a, BasicBlock b) {
			return dfs.getFinishTime(a) - dfs.getFinishTime(b);
		}
	}

	/**
	 * Constructor.
	 *
	 * @param cfg  the CFG
	 * @param rdfs the ReverseDepthFirstSearch of the CFG
	 * @param dfs TODO
	 */
	public ReverseDFSOrder(CFG cfg, ReverseDepthFirstSearch rdfs, DepthFirstSearch dfs) {
		super(cfg, new ReverseDFSComparator(rdfs, dfs));
		this.rdfs = rdfs;
		this.dfs = dfs;
	}
}

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