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Java > Open Source Codes > soot > util > SharedBitSetCache


1 /* Soot - a J*va Optimization Framework
2  * Copyright (C) 2003 Ondrej Lhotak
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 package soot.util;
21 import soot.*;
22
23 public final class SharedBitSetCache {
24     public SharedBitSetCache( Singletons.Global g ) {}
25     public static SharedBitSetCache v() { return G.v().soot_util_SharedBitSetCache(); }
26
27     public static final int size = 32749; // a nice prime about 32k
28

29     public BitVector[] cache = new BitVector[size];
30     public BitVector[] orAndAndNotCache = new BitVector[size];
31
32     public BitVector canonicalize( BitVector set ) {
33         int hash = set.hashCode();
34         if( hash < 0 ) hash = -hash;
35         hash %= size;
36         if( cache[hash] == null || !cache[hash].equals(set) ) {
37             return cache[hash] = set;
38         }
39         return cache[hash];
40     }
41 }
42
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