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      1 /*
      2  * ProGuard -- shrinking, optimization, obfuscation, and preverification
      3  *             of Java bytecode.
      4  *
      5  * Copyright (c) 2002-2009 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.util;
     22 
     23 /**
     24  * This StringMatcher tests whether strings start with a specified variable
     25  * string and then match another given StringMatcher.
     26  *
     27  * @author Eric Lafortune
     28  */
     29 public class VariableStringMatcher implements StringMatcher
     30 {
     31     private final char[]        allowedCharacters;
     32     private final char[]        disallowedCharacters;
     33     private final int           minimumLength;
     34     private final int           maximumLength;
     35     private final StringMatcher nextMatcher;
     36 
     37 
     38     public VariableStringMatcher(char[]        allowedCharacters,
     39                                  char[]        disallowedCharacters,
     40                                  int           minimumLength,
     41                                  int           maximumLength,
     42                                  StringMatcher nextMatcher)
     43     {
     44         this.allowedCharacters    = allowedCharacters;
     45         this.disallowedCharacters = disallowedCharacters;
     46         this.minimumLength        = minimumLength;
     47         this.maximumLength        = maximumLength;
     48         this.nextMatcher          = nextMatcher;
     49     }
     50 
     51     // Implementations for StringMatcher.
     52 
     53     public boolean matches(String string)
     54     {
     55         if (string.length() < minimumLength)
     56         {
     57             return false;
     58         }
     59 
     60         // Check the first minimum number of characters.
     61         for (int index = 0; index < minimumLength; index++)
     62         {
     63             if (!isAllowedCharacter(string.charAt(index)))
     64             {
     65                 return false;
     66             }
     67         }
     68 
     69         int maximumLength = Math.min(this.maximumLength, string.length());
     70 
     71         // Check the remaining characters, up to the maximum number.
     72         for (int index = minimumLength; index < maximumLength; index++)
     73         {
     74             if (nextMatcher.matches(string.substring(index)))
     75             {
     76                 return true;
     77             }
     78 
     79             if (!isAllowedCharacter(string.charAt(index)))
     80             {
     81                 return false;
     82             }
     83         }
     84 
     85         // Check the remaining characters in the string.
     86         return nextMatcher.matches(string.substring(maximumLength));
     87     }
     88 
     89 
     90     // Small utility methods.
     91 
     92     /**
     93      * Returns whether the given character is allowed in the variable string.
     94      */
     95     private boolean isAllowedCharacter(char character)
     96     {
     97         // Check the allowed characters.
     98         if (allowedCharacters != null)
     99         {
    100             for (int index = 0; index < allowedCharacters.length; index++)
    101             {
    102                 if (allowedCharacters[index] == character)
    103                 {
    104                     return true;
    105                 }
    106             }
    107 
    108             return false;
    109         }
    110 
    111         // Check the disallowed characters.
    112         if (disallowedCharacters != null)
    113         {
    114             for (int index = 0; index < disallowedCharacters.length; index++)
    115             {
    116                 if (disallowedCharacters[index] == character)
    117                 {
    118                     return false;
    119                 }
    120             }
    121         }
    122 
    123         // Any remaining character is allowed.
    124         return true;
    125     }
    126 }
    127