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.obfuscate; 22 23 import java.util.*; 24 25 26 /** 27 * This <code>NameFactory</code> generates unique short names, using mixed-case 28 * characters or lower-case characters only. 29 * 30 * @author Eric Lafortune 31 */ 32 public class SimpleNameFactory implements NameFactory 33 { 34 private static final int CHARACTER_COUNT = 26; 35 36 private static final List cachedMixedCaseNames = new ArrayList(); 37 private static final List cachedLowerCaseNames = new ArrayList(); 38 39 private final boolean generateMixedCaseNames; 40 private int index = 0; 41 42 43 /** 44 * Creates a new <code>SimpleNameFactory</code> that generates mixed-case names. 45 */ SimpleNameFactory()46 public SimpleNameFactory() 47 { 48 this(true); 49 } 50 51 52 /** 53 * Creates a new <code>SimpleNameFactory</code>. 54 * @param generateMixedCaseNames a flag to indicate whether the generated 55 * names will be mixed-case, or lower-case only. 56 */ SimpleNameFactory(boolean generateMixedCaseNames)57 public SimpleNameFactory(boolean generateMixedCaseNames) 58 { 59 this.generateMixedCaseNames = generateMixedCaseNames; 60 } 61 62 63 // Implementations for NameFactory. 64 reset()65 public void reset() 66 { 67 index = 0; 68 } 69 70 nextName()71 public String nextName() 72 { 73 return name(index++); 74 } 75 76 77 /** 78 * Returns the name at the given index. 79 */ name(int index)80 private String name(int index) 81 { 82 // Which cache do we need? 83 List cachedNames = generateMixedCaseNames ? 84 cachedMixedCaseNames : 85 cachedLowerCaseNames; 86 87 // Do we have the name in the cache? 88 if (index < cachedNames.size()) 89 { 90 return (String)cachedNames.get(index); 91 } 92 93 // Create a new name and cache it. 94 String name = newName(index); 95 cachedNames.add(index, name); 96 97 return name; 98 } 99 100 101 /** 102 * Creates and returns the name at the given index. 103 */ newName(int index)104 private String newName(int index) 105 { 106 // If we're allowed to generate mixed-case names, we can use twice as 107 // many characters. 108 int totalCharacterCount = generateMixedCaseNames ? 109 2 * CHARACTER_COUNT : 110 CHARACTER_COUNT; 111 112 int baseIndex = index / totalCharacterCount; 113 int offset = index % totalCharacterCount; 114 115 char newChar = charAt(offset); 116 117 String newName = baseIndex == 0 ? 118 new String(new char[] { newChar }) : 119 (name(baseIndex-1) + newChar); 120 121 return newName; 122 } 123 124 125 /** 126 * Returns the character with the given index, between 0 and the number of 127 * acceptable characters. 128 */ charAt(int index)129 private char charAt(int index) 130 { 131 return (char)((index < CHARACTER_COUNT ? 'a' - 0 : 132 'A' - CHARACTER_COUNT) + index); 133 } 134 135 main(String[] args)136 public static void main(String[] args) 137 { 138 System.out.println("Some mixed-case names:"); 139 printNameSamples(new SimpleNameFactory(true), 60); 140 System.out.println("Some lower-case names:"); 141 printNameSamples(new SimpleNameFactory(false), 60); 142 System.out.println("Some more mixed-case names:"); 143 printNameSamples(new SimpleNameFactory(true), 80); 144 System.out.println("Some more lower-case names:"); 145 printNameSamples(new SimpleNameFactory(false), 80); 146 } 147 148 printNameSamples(SimpleNameFactory factory, int count)149 private static void printNameSamples(SimpleNameFactory factory, int count) 150 { 151 for (int counter = 0; counter < count; counter++) 152 { 153 System.out.println(" ["+factory.nextName()+"]"); 154 } 155 } 156 } 157