1/*
2 * ProGuard -- shrinking, optimization, obfuscation, and preverification
3 *             of Java bytecode.
4 *
5 * Copyright (c) 2002-2014 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.util;
22
23import proguard.classfile.ClassConstants;
24
25
26/**
27 * Utility methods for working with access flags. For convenience, this class
28 * defines access levels, in ascending order: <code>PRIVATE</code>,
29 * <code>PACKAGE_VISIBLE</code>, <code>PROTECTED</code>, and <code>PUBLIC</code>.
30 *
31 * @author Eric Lafortune
32 */
33public class AccessUtil
34{
35    public static final int PRIVATE         = 0;
36    public static final int PACKAGE_VISIBLE = 1;
37    public static final int PROTECTED       = 2;
38    public static final int PUBLIC          = 3;
39
40
41    // The mask of access flags.
42    private static final int ACCESS_MASK =
43        ClassConstants.ACC_PUBLIC  |
44        ClassConstants.ACC_PRIVATE |
45        ClassConstants.ACC_PROTECTED;
46
47
48    /**
49     * Returns the corresponding access level of the given access flags.
50     * @param accessFlags the internal access flags.
51     * @return the corresponding access level: <code>PRIVATE</code>,
52     *         <code>PACKAGE_VISIBLE</code>, <code>PROTECTED</code>, or
53     *         <code>PUBLIC</code>.
54     */
55    public static int accessLevel(int accessFlags)
56    {
57        switch (accessFlags & ACCESS_MASK)
58        {
59            case ClassConstants.ACC_PRIVATE:   return PRIVATE;
60            default:                           return PACKAGE_VISIBLE;
61            case ClassConstants.ACC_PROTECTED: return PROTECTED;
62            case ClassConstants.ACC_PUBLIC:    return PUBLIC;
63        }
64    }
65
66
67    /**
68     * Returns the corresponding access flags of the given access level.
69     * @param accessLevel the access level: <code>PRIVATE</code>,
70     *                    <code>PACKAGE_VISIBLE</code>, <code>PROTECTED</code>,
71     *                    or <code>PUBLIC</code>.
72     * @return the corresponding internal access flags,  the internal access
73     *         flags as a logical bit mask of <code>INTERNAL_ACC_PRIVATE</code>,
74     *         <code>INTERNAL_ACC_PROTECTED</code>, and
75     *         <code>INTERNAL_ACC_PUBLIC</code>.
76     */
77    public static int accessFlags(int accessLevel)
78    {
79        switch (accessLevel)
80        {
81            case PRIVATE:   return ClassConstants.ACC_PRIVATE;
82            default:        return 0;
83            case PROTECTED: return ClassConstants.ACC_PROTECTED;
84            case PUBLIC:    return ClassConstants.ACC_PUBLIC;
85        }
86    }
87
88
89    /**
90     * Replaces the access part of the given access flags.
91     * @param accessFlags the internal access flags.
92     * @param accessFlags the new internal access flags.
93     */
94    public static int replaceAccessFlags(int accessFlags, int newAccessFlags)
95    {
96        // A private class member should not be explicitly final.
97        if (newAccessFlags == ClassConstants.ACC_PRIVATE)
98        {
99            accessFlags &= ~ClassConstants.ACC_FINAL;
100        }
101
102        return (accessFlags    & ~ACCESS_MASK) |
103               (newAccessFlags &  ACCESS_MASK);
104    }
105}
106