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.optimize.info;
22
23import proguard.classfile.*;
24import proguard.classfile.util.MethodLinker;
25import proguard.evaluation.value.*;
26
27/**
28 * This class stores some optimization information that can be attached to
29 * a field.
30 *
31 * @author Eric Lafortune
32 */
33public class FieldOptimizationInfo
34{
35    private static final SpecificValueFactory VALUE_FACTORY = new SpecificValueFactory();
36
37    private boolean        isWritten;
38    private boolean        isRead;
39    private boolean        canBeMadePrivate = true;
40    private ReferenceValue referencedClass;
41    private Value          value;
42
43
44    public FieldOptimizationInfo(Clazz clazz, Field field)
45    {
46        isWritten =
47        isRead    = (field.getAccessFlags() & ClassConstants.INTERNAL_ACC_VOLATILE) != 0;
48        value     = initialValue(field.getDescriptor(clazz));
49    }
50
51
52    public void setWritten()
53    {
54        isWritten = true;
55    }
56
57
58    public boolean isWritten()
59    {
60        return isWritten;
61    }
62
63
64    public void setRead()
65    {
66        isRead = true;
67    }
68
69
70    public boolean isRead()
71    {
72        return isRead;
73    }
74
75
76    public void setCanNotBeMadePrivate()
77    {
78        canBeMadePrivate = false;
79    }
80
81
82    public boolean canBeMadePrivate()
83    {
84        return canBeMadePrivate;
85    }
86
87
88    public void generalizeReferencedClass(ReferenceValue referencedClass)
89    {
90        this.referencedClass = this.referencedClass != null ?
91            this.referencedClass.generalize(referencedClass) :
92            referencedClass;
93    }
94
95
96    public ReferenceValue getReferencedClass()
97    {
98        return referencedClass;
99    }
100
101
102    public void generalizeValue(Value value)
103    {
104        this.value = this.value != null ?
105            this.value.generalize(value) :
106            value;
107    }
108
109
110    public Value getValue()
111    {
112        return value;
113    }
114
115
116    // Small utility methods.
117
118    private Value initialValue(String type)
119    {
120        switch (type.charAt(0))
121        {
122            case ClassConstants.INTERNAL_TYPE_BOOLEAN:
123            case ClassConstants.INTERNAL_TYPE_BYTE:
124            case ClassConstants.INTERNAL_TYPE_CHAR:
125            case ClassConstants.INTERNAL_TYPE_SHORT:
126            case ClassConstants.INTERNAL_TYPE_INT:
127                return VALUE_FACTORY.createIntegerValue(0);
128
129            case ClassConstants.INTERNAL_TYPE_LONG:
130                return VALUE_FACTORY.createLongValue(0L);
131
132            case ClassConstants.INTERNAL_TYPE_FLOAT:
133                return VALUE_FACTORY.createFloatValue(0.0f);
134
135            case ClassConstants.INTERNAL_TYPE_DOUBLE:
136                return VALUE_FACTORY.createDoubleValue(0.0);
137
138            case ClassConstants.INTERNAL_TYPE_CLASS_START:
139            case ClassConstants.INTERNAL_TYPE_ARRAY:
140                return VALUE_FACTORY.createReferenceValueNull();
141
142            default:
143                throw new IllegalArgumentException("Invalid type ["+type+"]");
144        }
145    }
146
147
148    public static void setFieldOptimizationInfo(Clazz clazz, Field field)
149    {
150        MethodLinker.lastMember(field).setVisitorInfo(new FieldOptimizationInfo(clazz, field));
151    }
152
153
154    public static FieldOptimizationInfo getFieldOptimizationInfo(Field field)
155    {
156        Object visitorInfo = MethodLinker.lastMember(field).getVisitorInfo();
157
158        return visitorInfo instanceof FieldOptimizationInfo ?
159            (FieldOptimizationInfo)visitorInfo :
160            null;
161    }
162}
163