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Java > Open Source Codes > net > sf > retrotranslator > transformer > EnumVisitor


1 /***
2  * Retrotranslator: a Java bytecode transformer that translates Java classes
3  * compiled with JDK 5.0 into classes that can be run on JVM 1.4.
4  *
5  * Copyright (c) 2005 - 2007 Taras Puchko
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  * notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  * notice, this list of conditions and the following disclaimer in the
15  * documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the copyright holders nor the names of its
17  * contributors may be used to endorse or promote products derived from
18  * this software without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
21  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
24  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
30  * THE POSSIBILITY OF SUCH DAMAGE.
31  */
32 package net.sf.retrotranslator.transformer;
33
34 import net.sf.retrotranslator.runtime.asm.*;
35 import static net.sf.retrotranslator.runtime.asm.Opcodes.*;
36 import net.sf.retrotranslator.runtime.impl.RuntimeTools;
37 import net.sf.retrotranslator.runtime.java.lang.Enum_;
38
39 /**
40  * @author Taras Puchko
41  */
42 class EnumVisitor extends ClassAdapter {
43
44     private static final String JavaDoc ENUM_NAME = Type.getInternalName(Enum_.class);
45     private static final String JavaDoc SET_ENUM_CONSTANTS_NAME = "setEnumConstants";
46     private static final String JavaDoc SET_ENUM_CONSTANTS_DESC =
47             TransformerTools.descriptor(void.class, Class JavaDoc.class, Enum_[].class);
48
49     private Type type;
50
51     public EnumVisitor(final ClassVisitor cv) {
52         super(cv);
53     }
54
55     public void visit(final int version, final int access, final String JavaDoc name,
56                       final String JavaDoc signature, final String JavaDoc superName, final String JavaDoc[] interfaces) {
57         super.visit(version, access, name, signature, superName, interfaces);
58         if ((access & ACC_ENUM) != 0 && ENUM_NAME.equals(superName)) {
59             type = TransformerTools.getTypeByInternalName(name);
60         }
61     }
62
63     public MethodVisitor visitMethod(final int access, final String JavaDoc name,
64                                      final String JavaDoc desc, final String JavaDoc signature, final String JavaDoc[] exceptions) {
65         MethodVisitor visitor = super.visitMethod(access, name, desc, signature, exceptions);
66         if (visitor == null || type == null || !name.equals(RuntimeTools.STATIC_NAME)) return visitor;
67         return new MethodAdapter(visitor) {
68
69             private boolean alreadyProcessed;
70
71             public void visitMethodInsn(final int opcode, final String JavaDoc owner, final String JavaDoc name, final String JavaDoc desc) {
72                 if (opcode == INVOKESTATIC && owner.equals(ENUM_NAME) &&
73                         name.equals(SET_ENUM_CONSTANTS_NAME) && desc.equals(SET_ENUM_CONSTANTS_DESC)) {
74                     alreadyProcessed = true;
75                 }
76                 super.visitMethodInsn(opcode, owner, name, desc);
77             }
78
79             public void visitInsn(final int opcode) {
80                 if (opcode == RETURN && !alreadyProcessed) {
81                     mv.visitLdcInsn(type);
82                     mv.visitMethodInsn(INVOKESTATIC, type.getInternalName(), "values", "()[" + type.getDescriptor());
83                     mv.visitMethodInsn(INVOKESTATIC, ENUM_NAME, SET_ENUM_CONSTANTS_NAME, SET_ENUM_CONSTANTS_DESC);
84                 }
85                 super.visitInsn(opcode);
86             }
87         };
88     }
89 }
90
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