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      1 /*
      2  * ProGuard -- shrinking, optimization, obfuscation, and preverification
      3  *             of Java bytecode.
      4  *
      5  * Copyright (c) 2002-2014 Eric Lafortune (eric (at) 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.classfile.visitor;
     22 
     23 import proguard.classfile.*;
     24 
     25 /**
     26  * This <code>ClassVisitor</code> delegates its visits to one of two
     27  * <code>ClassVisitor</code> instances, depending on whether the name of
     28  * the visited class file is present in a given <code>ClassPool</code> or not.
     29  *
     30  * @author Eric Lafortune
     31  */
     32 public class ClassPresenceFilter implements ClassVisitor
     33 {
     34     private final ClassPool    classPool;
     35     private final ClassVisitor presentClassVisitor;
     36     private final ClassVisitor missingClassVisitor;
     37 
     38 
     39     /**
     40      * Creates a new ClassPresenceFilter.
     41      * @param classPool           the <code>ClassPool</code> in which the
     42      *                            presence will be tested.
     43      * @param presentClassVisitor the <code>ClassVisitor</code> to which visits
     44      *                            of present class files will be delegated.
     45      * @param missingClassVisitor the <code>ClassVisitor</code> to which visits
     46      *                            of missing class files will be delegated.
     47      */
     48     public ClassPresenceFilter(ClassPool    classPool,
     49                                ClassVisitor presentClassVisitor,
     50                                ClassVisitor missingClassVisitor)
     51     {
     52         this.classPool           = classPool;
     53         this.presentClassVisitor = presentClassVisitor;
     54         this.missingClassVisitor = missingClassVisitor;
     55     }
     56 
     57 
     58     // Implementations for ClassVisitor.
     59 
     60     public void visitProgramClass(ProgramClass programClass)
     61     {
     62         ClassVisitor classFileVisitor = classFileVisitor(programClass);
     63 
     64         if (classFileVisitor != null)
     65         {
     66             classFileVisitor.visitProgramClass(programClass);
     67         }
     68     }
     69 
     70 
     71     public void visitLibraryClass(LibraryClass libraryClass)
     72     {
     73         ClassVisitor classFileVisitor = classFileVisitor(libraryClass);
     74 
     75         if (classFileVisitor != null)
     76         {
     77             classFileVisitor.visitLibraryClass(libraryClass);
     78         }
     79     }
     80 
     81 
     82     // Small utility methods.
     83 
     84     /**
     85      * Returns the appropriate <code>ClassVisitor</code>.
     86      */
     87     private ClassVisitor classFileVisitor(Clazz clazz)
     88     {
     89         return classPool.getClass(clazz.getName()) != null ?
     90             presentClassVisitor :
     91             missingClassVisitor;
     92     }
     93 }
     94