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Java > Open Source Codes > edu > umd > cs > findbugs > ba > ReversePostOrder


1 /*
2  * Bytecode Analysis Framework
3  * Copyright (C) 2003,2004 University of Maryland
4  *
5  * This library is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU Lesser General Public
7  * License as published by the Free Software Foundation; either
8  * version 2.1 of the License, or (at your option) any later version.
9  *
10  * This library is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13  * Lesser General Public License for more details.
14  *
15  * You should have received a copy of the GNU Lesser General Public
16  * License along with this library; if not, write to the Free Software
17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18  */
19
20 package edu.umd.cs.findbugs.ba;
21
22 import java.util.Comparator JavaDoc;
23
24 /**
25  * A BlockOrder for visiting the blocks of a CFG in
26  * the reverse of the order in which they are finished in
27  * a depth first search. This is the most efficient visitation
28  * order for forward dataflow analyses.
29  *
30  * @see BlockOrder
31  * @see DepthFirstSearch
32  * @see CFG
33  * @see BasicBlock
34  */
35 public class ReversePostOrder extends AbstractBlockOrder {
36     /**
37      * A Comparator to order the blocks in the reverse of the
38      * order in which they would be finished by a depth first search.
39      */
40     private static class ReversePostfixComparator implements Comparator JavaDoc<BasicBlock> {
41         private DepthFirstSearch dfs;
42
43         public ReversePostfixComparator(DepthFirstSearch dfs) {
44             this.dfs = dfs;
45         }
46
47         public int compare(BasicBlock aa, BasicBlock bb) {
48             return dfs.getFinishTime(bb) - dfs.getFinishTime(aa);
49         }
50     }
51
52     /**
53      * Constructor.
54      *
55      * @param cfg the CFG for the method
56      * @param dfs the DepthFirstSearch on the method
57      */
58     public ReversePostOrder(CFG cfg, DepthFirstSearch dfs) {
59         super(cfg, new ReversePostfixComparator(dfs));
60     }
61 }
62
63 // vim:ts=4
64
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