01: /*
02: * ProGuard -- shrinking, optimization, obfuscation, and preverification
03: * of Java bytecode.
04: *
05: * Copyright (c) 2002-2007 Eric Lafortune (eric@graphics.cornell.edu)
06: *
07: * This library is free software; you can redistribute it and/or modify it
08: * under the terms of the GNU General Public License as published by the Free
09: * Software Foundation; either version 2 of the License, or (at your option)
10: * any later version.
11: *
12: * This library 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 Lesser General Public License
15: * for more details.
16: *
17: * You should have received a copy of the GNU Lesser General Public License
18: * along with this library; if not, write to the Free Software Foundation,
19: * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20: */
21: package proguard.optimize;
22:
23: import proguard.classfile.*;
24: import proguard.classfile.util.SimplifiedVisitor;
25: import proguard.classfile.visitor.MemberVisitor;
26: import proguard.evaluation.value.Value;
27: import proguard.optimize.evaluation.StoringInvocationUnit;
28:
29: /**
30: * This <code>MemberVisitor</code> delegates its visits to program class members
31: * to another given <code>MemberVisitor</code>, but only when the visited
32: * field has been marked as a constant.
33: *
34: * @see StoringInvocationUnit
35: * @author Eric Lafortune
36: */
37: public class ConstantMemberFilter extends SimplifiedVisitor implements
38: MemberVisitor {
39: private final MemberVisitor constantMemberVisitor;
40:
41: /**
42: * Creates a new ConstantMemberFilter.
43: * @param constantMemberVisitor the <code>MemberVisitor</code> to which
44: * visits to constant members will be delegated.
45: */
46: public ConstantMemberFilter(MemberVisitor constantMemberVisitor) {
47: this .constantMemberVisitor = constantMemberVisitor;
48: }
49:
50: // Implementations for MemberVisitor.
51:
52: public void visitProgramField(ProgramClass programClass,
53: ProgramField programField) {
54: Value value = StoringInvocationUnit.getFieldValue(programField);
55: if (value != null && value.isSpecific()) {
56: constantMemberVisitor.visitProgramField(programClass,
57: programField);
58: }
59: }
60:
61: public void visitProgramMethod(ProgramClass programClass,
62: ProgramMethod programMethod) {
63: Value value = StoringInvocationUnit
64: .getMethodReturnValue(programMethod);
65: if (value != null && value.isSpecific()) {
66: constantMemberVisitor.visitProgramMethod(programClass,
67: programMethod);
68: }
69: }
70: }
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