code: /**
   * Copyright (c) 2006, Regents of the University of California
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * Redistributions of source code must retain the above copyright notice,
   * this list of conditions and the following disclaimer.
   *
   * Redistributions in binary form must reproduce the above copyright
   * notice, this list of conditions and the following disclaimer in the
   * documentation and/or other materials provided with the distribution.
   *
   * Neither the name of the University of California, Los Angeles nor the
   * names of its contributors may be used to endorse or promote products
   * derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * Created May 27, 2006
   */
  package cck.text;
  
  /**
   * The <code>CharUtil</code> class includes a number of useful utilities in dealing
   * with characters. For example, testing whether a character is within a certain set,
   * converting between characters and digits in various base systems, etc.
   *
   * @author Ben L. Titzer
   */
  public class CharUtil {
      public static final char[] HEX_CHARS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
      public static final char[] LOW_HEX_CHARS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
  
      /**
       * The <code>isHexDigit()</code> method checks whether the specified character
       * represents a valid hexadecimal character. This method is case-insensitive.
       *
       * @param c the character to check
       * @return true if the specified character is a valid hexadecimal value; false
       *         otherwise
       */
      public static boolean isHexDigit(char c) {
          switch (c) {
              case '0':
              case '1':
              case '2':
              case '3':
              case '4':
              case '5':
              case '6':
              case '7':
              case '8':
              case '9':
              case 'a':
              case 'b':
              case 'c':
              case 'd':
              case 'e':
              case 'f':
              case 'A':
              case 'B':
              case 'C':
              case 'D':
              case 'E':
              case 'F':
                  return true;
          }
          return false;
      }
  
      public static char toUpperHexChar(int digitValue) {
          if ( digitValue < 10 ) return (char)(digitValue | '0');
          return (char)('A' + digitValue - 10);
      }
  
      public static char toLowerHexChar(int digitValue) {
          if ( digitValue < 10 ) return (char)(digitValue | '0');
          return (char)('a' + digitValue - 10);
      }
  
      /**
       * The <code>hexValueOf()</code> method converts a character into an integer
       * value according to the hexadecimal base system.
       *
       * @param c the character to convert
       * @return the value of the character in the hexadecimal base system
       */
      public static int hexValueOf(char c) {
          return Character.digit(c, 16);
      }
  
      /**
       * The <code>isDecDigit()</code> method checks whether the specified character
       * represents a valid decimal character. .
       *
       * @param c the character to check
       * @return true if the specified character is a valid decimal digit; false
       *         otherwise
       */
      public static boolean isDecDigit(char c) {
          if (c < '0') return false;
          return c <= '9';
      }
  
      /**
       * The <code>decValueOf()</code> method converts a character into an integer
       * value according to the decimal base system.
       *
       * @param c the character to convert
       * @return the value of the character in the decimal base system
       */
      public static int decValueOf(char c) {
          return Character.digit(c, 10);
      }
  
      /**
       * The <code>isOctDigit()</code> method checks whether the specified character
       * represents a valid octal character.
       *
       * @param c the character to check
       * @return true if the specified character is a valid octal digit; false
       *         otherwise
       */
      public static boolean isOctDigit(char c) {
          if (c < '0') return false;
          return c <= '7';
      }
  
      /**
       * The <code>octValueOf()</code> method converts a character into an integer
       * value according to the octal base system.
       *
       * @param c the character to convert
       * @return the value of the character in the octal base system
       */
      public static int octValueOf(char c) {
          return Character.digit(c, 8);
      }
  
      /**
       * The <code>isBinDigit()</code> method checks whether the specified character
       * represents a valid binary character.
       *
       * @param c the character to check
       * @return true if the specified character is a valid binary digit; false
       *         otherwise
       */
      public static boolean isBinDigit(char c) {
          return c == '0' || c == '1';
      }
  
      /**
       * The <code>binValueOf()</code> method converts a character into an integer
       * value according to the binary base system.
       *
       * @param c the character to convert
       * @return the value of the character in the binary base system
       */
      public static int binValueOf(char c) {
          return c == '0' ? 0 : 1;
      }
  
  }
  