ClassVersionFilter.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.classfile.visitor;
22
23import proguard.classfile.*;
24
25/**
26 * This <code>ClassVisitor</code> delegates its visits to program classes to
27 * another given <code>ClassVisitor</code>, but only when the class version
28 * number of the visited program class lies in a given range.
29 *
30 * @author Eric Lafortune
31 */
32public class ClassVersionFilter implements ClassVisitor
33{
34    private final int          minimumClassVersion;
35    private final int          maximumClassVersion;
36    private final ClassVisitor classVisitor;
37
38
39    /**
40     * Creates a new ClassVersionFilter.
41     * @param minimumClassVersion the minimum class version number.
42     * @param classVisitor        the <code>ClassVisitor</code> to which visits
43     *                            will be delegated.
44     */
45    public ClassVersionFilter(int          minimumClassVersion,
46                              ClassVisitor classVisitor)
47    {
48        this(minimumClassVersion, Integer.MAX_VALUE, classVisitor);
49    }
50
51
52    /**
53     * Creates a new ClassVersionFilter.
54     * @param minimumClassVersion the minimum class version number.
55     * @param maximumClassVersion the maximum class version number.
56     * @param classVisitor        the <code>ClassVisitor</code> to which visits
57     *                            will be delegated.
58     */
59    public ClassVersionFilter(int          minimumClassVersion,
60                              int          maximumClassVersion,
61                              ClassVisitor classVisitor)
62    {
63        this.minimumClassVersion = minimumClassVersion;
64        this.maximumClassVersion = maximumClassVersion;
65        this.classVisitor        = classVisitor;
66    }
67
68
69    // Implementations for ClassVisitor.
70
71    public void visitProgramClass(ProgramClass programClass)
72    {
73        if (programClass.u4version >= minimumClassVersion &&
74            programClass.u4version <= maximumClassVersion)
75        {
76            classVisitor.visitProgramClass(programClass);
77        }
78    }
79
80
81    public void visitLibraryClass(LibraryClass libraryClass)
82    {
83        // Library classes don't have version numbers.
84    }
85}
86