InternalTypeEnumeration.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.util;
22
23import proguard.classfile.ClassConstants;
24
25
26/**
27 * An <code>InternalTypeEnumeration</code> provides an enumeration of all
28 * parameter types listed in a given internal method descriptor or signature.
29 * The signature can also be a class signature. The return type of a method
30 * descriptor can be retrieved separately.
31 *
32 * @author Eric Lafortune
33 */
34public class InternalTypeEnumeration
35{
36    private String descriptor;
37    private int    firstIndex;
38    private int    lastIndex;
39    private int    index;
40
41
42    /**
43     * Creates a new InternalTypeEnumeration for the given method descriptor.
44     */
45    public InternalTypeEnumeration(String descriptor)
46    {
47        this.descriptor = descriptor;
48        this.firstIndex = descriptor.indexOf(ClassConstants.INTERNAL_METHOD_ARGUMENTS_OPEN);
49        this.lastIndex  = descriptor.indexOf(ClassConstants.INTERNAL_METHOD_ARGUMENTS_CLOSE);
50        this.index      = firstIndex + 1;
51
52        if (lastIndex < 0)
53        {
54            lastIndex = descriptor.length();
55        }
56    }
57
58
59    /**
60     * Returns the formal type parameters from the descriptor, assuming it's a
61     * method descriptor.
62     */
63    public String formalTypeParameters()
64    {
65        return descriptor.substring(0, firstIndex);
66    }
67
68
69    /**
70     * Returns whether the enumeration can provide more types from the method
71     * descriptor.
72     */
73    public boolean hasMoreTypes()
74    {
75        return index < lastIndex;
76    }
77
78
79    /**
80     * Returns the next type from the method descriptor.
81     */
82    public String nextType()
83    {
84        int startIndex = index;
85
86        skipArray();
87
88        char c = descriptor.charAt(index++);
89        switch (c)
90        {
91            case ClassConstants.INTERNAL_TYPE_CLASS_START:
92            case ClassConstants.INTERNAL_TYPE_GENERIC_VARIABLE_START:
93            {
94                skipClass();
95                break;
96            }
97            case ClassConstants.INTERNAL_TYPE_GENERIC_START:
98            {
99                skipGeneric();
100                break;
101            }
102        }
103
104        return descriptor.substring(startIndex, index);
105    }
106
107
108    /**
109     * Returns the return type from the descriptor, assuming it's a method
110     * descriptor.
111     */
112    public String returnType()
113    {
114        return descriptor.substring(lastIndex + 1);
115    }
116
117
118    // Small utility methods.
119
120    private void skipArray()
121    {
122        while (descriptor.charAt(index) == ClassConstants.INTERNAL_TYPE_ARRAY)
123        {
124            index++;
125        }
126    }
127
128
129    private void skipClass()
130    {
131        while (true)
132        {
133            char c = descriptor.charAt(index++);
134            switch (c)
135            {
136                case ClassConstants.INTERNAL_TYPE_GENERIC_START:
137                    skipGeneric();
138                    break;
139
140                case ClassConstants.INTERNAL_TYPE_CLASS_END:
141                    return;
142            }
143        }
144    }
145
146
147    private void skipGeneric()
148    {
149        int nestingLevel = 1;
150
151        do
152        {
153            char c = descriptor.charAt(index++);
154            switch (c)
155            {
156                case ClassConstants.INTERNAL_TYPE_GENERIC_START:
157                    nestingLevel++;
158                    break;
159
160                case ClassConstants.INTERNAL_TYPE_GENERIC_END:
161                    nestingLevel--;
162                    break;
163            }
164        }
165        while (nestingLevel > 0);
166    }
167
168
169    /**
170     * A main method for testing the type enumeration.
171     */
172    public static void main(String[] args)
173    {
174        try
175        {
176            for (int index = 0; index < args.length; index++)
177            {
178                String descriptor = args[index];
179
180                System.out.println("Descriptor ["+descriptor+"]");
181                InternalTypeEnumeration enumeration = new InternalTypeEnumeration(descriptor);
182
183                if (enumeration.firstIndex >= 0)
184                {
185                    System.out.println("  Formal type parameters ["+enumeration.formalTypeParameters()+"]");
186                }
187
188                while (enumeration.hasMoreTypes())
189                {
190                    System.out.println("  Type ["+enumeration.nextType()+"]");
191                }
192
193                if (enumeration.lastIndex < descriptor.length())
194                {
195                    System.out.println("  Return type ["+enumeration.returnType()+"]");
196                }
197            }
198        }
199        catch (Exception ex)
200        {
201            ex.printStackTrace();
202        }
203    }
204}
205