Value.java revision b9cc48a43ed984587c939d02fba5316bf5c0df6e 
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.evaluation.value;
22
23/**
24 * This abstract class represents a partially evaluated value.
25 *
26 * @author Eric Lafortune
27 */
28public abstract class Value
29{
30    public static final int NEVER  = -1;
31    public static final int MAYBE  = 0;
32    public static final int ALWAYS = 1;
33
34    public static final int TYPE_INTEGER            = 1;
35    public static final int TYPE_LONG               = 2;
36    public static final int TYPE_FLOAT              = 3;
37    public static final int TYPE_DOUBLE             = 4;
38    public static final int TYPE_REFERENCE          = 5;
39    public static final int TYPE_INSTRUCTION_OFFSET = 6;
40    public static final int TYPE_TOP                = 7;
41
42
43    /**
44     * Returns this Value as a Category1Value.
45     */
46    public Category1Value category1Value()
47    {
48        throw new IllegalArgumentException("Value is not a Category 1 value [" + this.getClass().getName() + "]");
49    }
50
51    /**
52     * Returns this Value as a Category2Value.
53     */
54    public Category2Value category2Value()
55    {
56        throw new IllegalArgumentException("Value is not a Category 2 value [" + this.getClass().getName() + "]");
57    }
58
59
60    /**
61     * Returns this Value as an IntegerValue.
62     */
63    public IntegerValue integerValue()
64    {
65        throw new IllegalArgumentException("Value is not an integer value [" + this.getClass().getName() + "]");
66    }
67
68    /**
69     * Returns this Value as a LongValue.
70     */
71    public LongValue longValue()
72    {
73        throw new IllegalArgumentException("Value is not a long value [" + this.getClass().getName() + "]");
74    }
75
76    /**
77     * Returns this Value as a FloatValue.
78     */
79    public FloatValue floatValue()
80    {
81        throw new IllegalArgumentException("Value is not a float value [" + this.getClass().getName() + "]");
82    }
83
84    /**
85     * Returns this Value as a DoubleValue.
86     */
87    public DoubleValue doubleValue()
88    {
89        throw new IllegalArgumentException("Value is not a double value [" + this.getClass().getName() + "]");
90    }
91
92    /**
93     * Returns this Value as a ReferenceValue.
94     */
95    public ReferenceValue referenceValue()
96    {
97        throw new IllegalArgumentException("Value is not a reference value [" + this.getClass().getName() + "]");
98    }
99
100    /**
101     * Returns this Value as an InstructionOffsetValue.
102     */
103    public InstructionOffsetValue instructionOffsetValue()
104    {
105        throw new IllegalArgumentException("Value is not an instruction offset value [" + this.getClass().getName() + "]");
106    }
107
108
109    /**
110     * Returns whether this Value represents a single specific (but possibly
111     * unknown) value.
112     */
113    public boolean isSpecific()
114    {
115        return false;
116    }
117
118
119    /**
120     * Returns whether this Value represents a single particular (known)
121     * value.
122     */
123    public boolean isParticular()
124    {
125        return false;
126    }
127
128
129    /**
130     * Returns the generalization of this Value and the given other Value.
131     */
132    public abstract Value generalize(Value other);
133
134
135    /**
136     * Returns whether the computational type of this Value is a category 2 type.
137     * This means that it takes up the space of two category 1 types on the
138     * stack, for instance.
139     */
140    public abstract boolean isCategory2();
141
142
143    /**
144     * Returns the computational type of this Value.
145     * @return <code>TYPE_INTEGER</code>,
146     *         <code>TYPE_LONG</code>,
147     *         <code>TYPE_FLOAT</code>,
148     *         <code>TYPE_DOUBLE</code>,
149     *         <code>TYPE_REFERENCE</code>, or
150     *         <code>TYPE_INSTRUCTION_OFFSET</code>.
151     */
152    public abstract int computationalType();
153
154
155    /**
156     * Returns the internal type of this Value.
157     * @return <code>ClassConstants.INTERNAL_TYPE_BOOLEAN</code>,
158     *         <code>ClassConstants.INTERNAL_TYPE_BYTE</code>,
159     *         <code>ClassConstants.INTERNAL_TYPE_CHAR</code>,
160     *         <code>ClassConstants.INTERNAL_TYPE_SHORT</code>,
161     *         <code>ClassConstants.INTERNAL_TYPE_INT</code>,
162     *         <code>ClassConstants.INTERNAL_TYPE_LONG</code>,
163     *         <code>ClassConstants.INTERNAL_TYPE_FLOAT</code>,
164     *         <code>ClassConstants.INTERNAL_TYPE_DOUBLE</code>,
165     *         <code>ClassConstants.INTERNAL_TYPE_CLASS_START ... ClassConstants.INTERNAL_TYPE_CLASS_END</code>, or
166     *         an array type containing any of these types (always as String).
167     */
168    public abstract String internalType();
169}
170