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  */
21 package proguard.optimize.evaluation;
22 
23 import proguard.classfile.*;
24 import proguard.classfile.util.SimplifiedVisitor;
25 import proguard.classfile.visitor.*;
26 import proguard.evaluation.value.*;
27 import proguard.optimize.info.*;
28 
29 /**
30  * This ClassVisitor propagates the value of the $VALUES field to the values()
31  * method in the simple enum classes that it visits.
32  *
33  * @see SimpleEnumMarker
34  * @author Eric Lafortune
35  */
36 public class SimpleEnumArrayPropagator
37 extends      SimplifiedVisitor
38 implements   ClassVisitor,
39              MemberVisitor
40 {
41     private final ValueFactory valueFactory = new ParticularValueFactory();
42 
43     private Value array;
44 
45 
46     // Implementations for ClassVisitor.
47 
visitProgramClass(ProgramClass programClass)48     public void visitProgramClass(ProgramClass programClass)
49     {
50         // Update the return value of the "int[] values()" method.
51         programClass.methodsAccept(new MemberDescriptorFilter("()[I", this));
52     }
53 
54 
55     // Implementations for MemberVisitor.
56 
visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)57     public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)
58     {
59         // Find the array length of the "int[] $VALUES" field.
60         programClass.fieldsAccept(new MemberDescriptorFilter("[I", this));
61 
62         if (array != null)
63         {
64             // Set the array value with the found array length. We can't use
65             // the original array, because its elements might get overwritten.
66             Value propagatedArray =
67                 valueFactory.createArrayReferenceValue("I",
68                                                        null,
69                                                        array.referenceValue().arrayLength(
70                                                            valueFactory));
71 
72             setMethodReturnValue(programMethod, propagatedArray);
73 
74             array = null;
75         }
76     }
77 
visitProgramField(ProgramClass programClass, ProgramField programField)78     public void visitProgramField(ProgramClass programClass, ProgramField programField)
79     {
80         array = StoringInvocationUnit.getFieldValue(programField);
81     }
82 
83 
84     // Small utility methods.
85 
setMethodReturnValue(Method method, Value value)86     private static void setMethodReturnValue(Method method, Value value)
87     {
88         MethodOptimizationInfo info = MethodOptimizationInfo.getMethodOptimizationInfo(method);
89         if (info != null)
90         {
91             info.setReturnValue(value);
92         }
93     }
94 }
95