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Java > Open Source Codes > soot > toolkits > scalar > FlowAnalysis


1 /* Soot - a J*va Optimization Framework
2  * Copyright (C) 1997-1999 Raja Vallee-Rai
3  *
4  * This library is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * This library is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with this library; if not, write to the
16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17  * Boston, MA 02111-1307, USA.
18  */

19
20 /*
21  * Modified by the Sable Research Group and others 1997-1999.
22  * See the 'credits' file distributed with Soot for the complete list of
23  * contributors. (Soot is distributed at http://www.sable.mcgill.ca/soot)
24  */

25
26
27 package soot.toolkits.scalar;
28
29 import soot.*;
30 import soot.toolkits.graph.*;
31 import soot.util.*;
32 import java.util.*;
33
34 /** An abstract class providing a framework for carrying out dataflow analysis.
35  * Subclassing either BackwardFlowAnalysis or ForwardFlowAnalysis and providing
36  * implementations for the abstract methods will allow Soot to compute the
37  * corresponding flow analysis. */

38 public abstract class FlowAnalysis extends AbstractFlowAnalysis
39 {
40     /** Maps graph nodes to OUT sets. */
41     protected Map unitToAfterFlow;
42
43     /** Filtered: Maps graph nodes to OUT sets. */
44     protected Map filterUnitToAfterFlow;
45
46     /** Constructs a flow analysis on the given <code>DirectedGraph</code>. */
47     public FlowAnalysis(DirectedGraph graph)
48     {
49         super(graph);
50         unitToAfterFlow = new HashMap(graph.size() * 2 + 1, 0.7f);
51     }
52
53     /** Given the merge of the <code>out</code> sets, compute the <code>in</code> set for <code>s</code> (or in to out, depending on direction). */
54     protected abstract void flowThrough(Object JavaDoc in, Object JavaDoc d, Object JavaDoc out);
55
56     /** Accessor function returning value of OUT set for s. */
57     public Object JavaDoc getFlowAfter(Object JavaDoc s)
58     {
59         return unitToAfterFlow.get(s);
60     }
61 }
62
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