1/*
2 * ProGuard -- shrinking, optimization, obfuscation, and preverification
3 *             of Java bytecode.
4 *
5 * Copyright (c) 2002-2009 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.VerificationTypeVisitor;
26
27/**
28 * This abstract class represents a verification type of a local variable or
29 * a stack element. Specific verification types are subclassed from it.
30 *
31 * @author Eric Lafortune
32 */
33public abstract class VerificationType implements VisitorAccepter
34{
35    public static final int TOP_TYPE                = 0;
36    public static final int INTEGER_TYPE            = 1;
37    public static final int FLOAT_TYPE              = 2;
38    public static final int DOUBLE_TYPE             = 3;
39    public static final int LONG_TYPE               = 4;
40    public static final int NULL_TYPE               = 5;
41    public static final int UNINITIALIZED_THIS_TYPE = 6;
42    public static final int OBJECT_TYPE             = 7;
43    public static final int UNINITIALIZED_TYPE      = 8;
44
45
46    /**
47     * An extra field in which visitors can store information.
48     */
49    public Object visitorInfo;
50
51
52    /**
53     * Returns the tag of the verification type.
54     */
55    public abstract int getTag();
56
57
58    /**
59     * Accepts the given visitor in the context of a method's code, either on
60     * a stack or as a variable.
61     */
62    public abstract void accept(Clazz clazz, Method method, CodeAttribute codeAttribute, int instructionOffset, VerificationTypeVisitor verificationTypeVisitor);
63
64
65    /**
66     * Accepts the given visitor in the context of a stack in a method's code .
67     */
68    public abstract void stackAccept(Clazz clazz, Method method, CodeAttribute codeAttribute, int instructionOffset, int stackIndex, VerificationTypeVisitor verificationTypeVisitor);
69
70
71    /**
72     * Accepts the given visitor in the context of a variable in a method's code.
73     */
74    public abstract void variablesAccept(Clazz clazz, Method method, CodeAttribute codeAttribute, int instructionOffset, int variableIndex, VerificationTypeVisitor verificationTypeVisitor);
75
76
77    // Implementations for VisitorAccepter.
78
79    public Object getVisitorInfo()
80    {
81        return visitorInfo;
82    }
83
84    public void setVisitorInfo(Object visitorInfo)
85    {
86        this.visitorInfo = visitorInfo;
87    }
88
89
90    // Implementations for Object.
91
92    public boolean equals(Object object)
93    {
94        return object != null &&
95               this.getClass() == object.getClass();
96    }
97
98
99    public int hashCode()
100    {
101        return this.getClass().hashCode();
102    }
103}
104