SameZeroFrame.java revision 8a6199f0c36a778f22394364347a301b0b28e94b 
1/*
2 * ProGuard -- shrinking, optimization, obfuscation, and preverification
3 *             of Java bytecode.
4 *
5 * Copyright (c) 2002-2013 Eric Lafortune (eric@graphics.cornell.edu)
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License as published by the Free
9 * Software Foundation; either version 2 of the License, or (at your option)
10 * any later version.
11 *
12 * This program is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 * more details.
16 *
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, write to the Free Software Foundation, Inc.,
19 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 */
21package proguard.classfile.attribute.preverification;
22
23import proguard.classfile.*;
24import proguard.classfile.attribute.CodeAttribute;
25import proguard.classfile.attribute.preverification.visitor.StackMapFrameVisitor;
26
27/**
28 * This StackMapFrame represents a "same frame" or a "same frame extended".
29 *
30 * @author Eric Lafortune
31 * @noinspection PointlessArithmeticExpression
32 */
33public class SameZeroFrame extends StackMapFrame
34{
35    /**
36     * Creates an uninitialized SameZeroFrame.
37     */
38    public SameZeroFrame()
39    {
40    }
41
42
43    /**
44     * Creates a SameZeroFrame with the given tag.
45     */
46    public SameZeroFrame(int tag)
47    {
48        u2offsetDelta = tag - SAME_ZERO_FRAME;
49    }
50
51
52    // Implementations for StackMapFrame.
53
54    public int getTag()
55    {
56        return u2offsetDelta < 64 ?
57            SAME_ZERO_FRAME + u2offsetDelta :
58            SAME_ZERO_FRAME_EXTENDED;
59    }
60
61
62    public void accept(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, StackMapFrameVisitor stackMapFrameVisitor)
63    {
64        stackMapFrameVisitor.visitSameZeroFrame(clazz, method, codeAttribute, offset, this);
65    }
66
67
68    // Implementations for Object.
69
70    public String toString()
71    {
72        return super.toString()+"Var: ..., Stack: (empty)";
73    }
74}
75