/** A class representing strings that implements
      the Lexicographical interface.  Here we assume
      that strings consist only of lower-case letters.
    The constructor for this class will accept arbitrary
      strings, replacing all illegal characters with
      the terminator character.
*/


public class TrieString implements Lexicographical
{

   // the string being represented

   private String data;


   // the number of legal characters, including
   //   the terminator.

   private static int alphabetSize = 27;


   /** A constructor taking a string to
         be represented.
       @param d the string to be represented
   */
   public TrieString(String d)                {
     data=d;                                  }

   /**
      @return the string being represented
   */

   public String toString()                   {
     return data;                             }



   // implementation of the Lexicographical interface

   /**
     @return the length of the string being
       represented (including any illegal
       characters).
   */

   public int length()                        {
     return data.length();                    }

   /**
     @return the number of legal characters,
      including the terminator
   */
   public int getAlphabetSize()               {
     return alphabetSize;                     }


   /**
      @return the character code of the
       character of the string in the
       given position (that is, the
       position of the character in
       the alphabet's natural ordering,
       with the terminator character counting
       as the 0th character.  Returns 0 if
       there is no legal character in the
       given position.
   */
   public int elementAt(int i)                {
     if (i>=data.length())
       return 0;
     char c=data.charAt(i);
     if (c>='a' && c<='z')
       return 1 + (int) c - (int) 'a';
     else
       return 0;                             }

};