code: /*
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  package tool.util;
  
  /*
  
     Porter stemmer in Java. The original paper is in
  
         Porter, 1980, An algorithm for suffix stripping, Program, Vol. 14,
         no. 3, pp 130-137,
  
     See also http://www.tartarus.org/~martin/PorterStemmer
  
     History:
  
     Release 1
  
     Bug 1 (reported by Gonzalo Parra 16/10/99) fixed as marked below.
     The words 'aed', 'eed', 'oed' leave k at 'a' for step 3, and b[k-1]
     is then out outside the bounds of b.
  
     Release 2
  
     Similarly,
  
     Bug 2 (reported by Steve Dyrdahl 22/2/00) fixed as marked below.
     'ion' by itself leaves j = -1 in the test for 'ion' in step 5, and
     b[j] is then outside the bounds of b.
  
     Release 3
  
     Considerably revised 4/9/00 in the light of many helpful suggestions
     from Brian Goetz of Quiotix Corporation (brian@quiotix.com).
  
     Release 4
  
  */
  
  import java.io.*;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  
  /**
    * Stemmer, implementing the Porter Stemming Algorithm
    *
    * The Stemmer class transforms a word into its root form.  The input
    * word can be provided a character at time (by calling add()), or at once
    * by calling one of the various stem(something) methods.
    */
  
  public class PorterStemmer
  {  private char[] b;
     private int i,     /* offset into b */
                 i_end, /* offset to end of stemmed word */
                 j, k;
     private static final int INC = 50;
                       /* unit of size whereby b is increased */
     public PorterStemmer()
     {  b = new char[INC];
        i = 0;
        i_end = 0;
     }
  
     /**
      * Add a character to the word being stemmed.  When you are finished
      * adding characters, you can call stem(void) to stem the word.
      */
  
     public void add(char ch)
     {  if (i == b.length)
        {  char[] new_b = new char[i+INC];
           for (int c = 0; c < i; c++) new_b[c] = b[c];
           b = new_b;
        }
        b[i++] = ch;
     }
  
  
     /** Adds wLen characters to the word being stemmed contained in a portion
      * of a char[] array. This is like repeated calls of add(char ch), but
      * faster.
      */
  
     public void add(char[] w, int wLen)
     {  if (i+wLen >= b.length)
        {  char[] new_b = new char[i+wLen+INC];
           for (int c = 0; c < i; c++) new_b[c] = b[c];
           b = new_b;
        }
        for (int c = 0; c < wLen; c++) b[i++] = w[c];
     }
  
     /**
      * After a word has been stemmed, it can be retrieved by toString(),
      * or a reference to the internal buffer can be retrieved by getResultBuffer
      * and getResultLength (which is generally more efficient.)
      */
     public String toString() { return new String(b,0,i_end); }
  
     /**
      * Returns the length of the word resulting from the stemming process.
      */
     public int getResultLength() { return i_end; }
  
     /**
      * Returns a reference to a character buffer containing the results of
      * the stemming process.  You also need to consult getResultLength()
      * to determine the length of the result.
      */
     public char[] getResultBuffer() { return b; }
  
     /* cons(i) is true <=> b[i] is a consonant. */
  
     private final boolean cons(int i)
     {  switch (b[i])
        {  case 'a': case 'e': case 'i': case 'o': case 'u': return false;
           case 'y': return (i==0) ? true : !cons(i-1);
           default: return true;
        }
     }
  
     /* m() measures the number of consonant sequences between 0 and j. if c is
        a consonant sequence and v a vowel sequence, and <..> indicates arbitrary
        presence,
  
           <c><v>       gives 0
           <c>vc<v>     gives 1
           <c>vcvc<v>   gives 2
           <c>vcvcvc<v> gives 3
           ....
     */
  
     private final int m()
     {  int n = 0;
        int i = 0;
        while(true)
        {  if (i > j) return n;
           if (! cons(i)) break; i++;
        }
        i++;
        while(true)
        {  while(true)
           {  if (i > j) return n;
                 if (cons(i)) break;
                 i++;
           }
           i++;
           n++;
           while(true)
           {  if (i > j) return n;
              if (! cons(i)) break;
              i++;
           }
           i++;
         }
     }
  
     /* vowelinstem() is true <=> 0,...j contains a vowel */
  
     private final boolean vowelinstem()
     {  int i; for (i = 0; i <= j; i++) if (! cons(i)) return true;
        return false;
     }
  
     /* doublec(j) is true <=> j,(j-1) contain a double consonant. */
  
     private final boolean doublec(int j)
     {  if (j < 1) return false;
        if (b[j] != b[j-1]) return false;
        return cons(j);
     }
  
     /* cvc(i) is true <=> i-2,i-1,i has the form consonant - vowel - consonant
        and also if the second c is not w,x or y. this is used when trying to
        restore an e at the end of a short word. e.g.
  
           cav(e), lov(e), hop(e), crim(e), but
           snow, box, tray.
  
     */
  
     private final boolean cvc(int i)
     {  if (i < 2 || !cons(i) || cons(i-1) || !cons(i-2)) return false;
        {  int ch = b[i];
           if (ch == 'w' || ch == 'x' || ch == 'y') return false;
        }
        return true;
     }
  
     private final boolean ends(String s)
     {  int l = s.length();
        int o = k-l+1;
        if (o < 0) return false;
        for (int i = 0; i < l; i++) if (b[o+i] != s.charAt(i)) return false;
        j = k-l;
        return true;
     }
  
     /* setto(s) sets (j+1),...k to the characters in the string s, readjusting
        k. */
  
     private final void setto(String s)
     {  int l = s.length();
        int o = j+1;
        for (int i = 0; i < l; i++) b[o+i] = s.charAt(i);
        k = j+l;
     }
  
     /* r(s) is used further down. */
  
     private final void r(String s) { if (m() > 0) setto(s); }
  
     /* step1() gets rid of plurals and -ed or -ing. e.g.
  
            caresses  ->  caress
            ponies    ->  poni
            ties      ->  ti
            caress    ->  caress
            cats      ->  cat
  
            feed      ->  feed
            agreed    ->  agree
            disabled  ->  disable
  
            matting   ->  mat
            mating    ->  mate
            meeting   ->  meet
            milling   ->  mill
            messing   ->  mess
  
            meetings  ->  meet
  
     */
  
     private final void step1()
     {  if (b[k] == 's')
        {  if (ends("sses")) k -= 2; else
           if (ends("ies")) setto("i"); else
           if (b[k-1] != 's') k--;
        }
        if (ends("eed")) { if (m() > 0) k--; } else
        if ((ends("ed") || ends("ing")) && vowelinstem())
        {  k = j;
           if (ends("at")) setto("ate"); else
           if (ends("bl")) setto("ble"); else
           if (ends("iz")) setto("ize"); else
           if (doublec(k))
           {  k--;
              {  int ch = b[k];
                 if (ch == 'l' || ch == 's' || ch == 'z') k++;
              }
           }
           else if (m() == 1 && cvc(k)) setto("e");
       }
     }
  
     /* step2() turns terminal y to i when there is another vowel in the stem. */
  
     private final void step2() { if (ends("y") && vowelinstem()) b[k] = 'i'; }
  
     /* step3() maps double suffices to single ones. so -ization ( = -ize plus
        -ation) maps to -ize etc. note that the string before the suffix must give
        m() > 0. */
  
     private final void step3() { if (k == 0) return; /* For Bug 1 */ switch (b[k-1])
     {
         case 'a': if (ends("ational")) { r("ate"); break; }
                   if (ends("tional")) { r("tion"); break; }
                   break;
         case 'c': if (ends("enci")) { r("ence"); break; }
                   if (ends("anci")) { r("ance"); break; }
                   break;
         case 'e': if (ends("izer")) { r("ize"); break; }
                   break;
         case 'l': if (ends("bli")) { r("ble"); break; }
                   if (ends("alli")) { r("al"); break; }
                   if (ends("entli")) { r("ent"); break; }
                   if (ends("eli")) { r("e"); break; }
                   if (ends("ousli")) { r("ous"); break; }
                   break;
         case 'o': if (ends("ization")) { r("ize"); break; }
                   if (ends("ation")) { r("ate"); break; }
                   if (ends("ator")) { r("ate"); break; }
                   break;
         case 's': if (ends("alism")) { r("al"); break; }
                   if (ends("iveness")) { r("ive"); break; }
                   if (ends("fulness")) { r("ful"); break; }
                   if (ends("ousness")) { r("ous"); break; }
                   break;
         case 't': if (ends("aliti")) { r("al"); break; }
                   if (ends("iviti")) { r("ive"); break; }
                   if (ends("biliti")) { r("ble"); break; }
                   break;
         case 'g': if (ends("logi")) { r("log"); break; }
     } }
  
     /* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */
  
     private final void step4() { switch (b[k])
     {
         case 'e': if (ends("icate")) { r("ic"); break; }
                   if (ends("ative")) { r(""); break; }
                   if (ends("alize")) { r("al"); break; }
                   break;
         case 'i': if (ends("iciti")) { r("ic"); break; }
                   break;
         case 'l': if (ends("ical")) { r("ic"); break; }
                   if (ends("ful")) { r(""); break; }
                   break;
         case 's': if (ends("ness")) { r(""); break; }
                   break;
     } }
  
     /* step5() takes off -ant, -ence etc., in context <c>vcvc<v>. */
  
     private final void step5()
     {   if (k == 0) return; /* for Bug 1 */ switch (b[k-1])
         {  case 'a': if (ends("al")) break; return;
            case 'c': if (ends("ance")) break;
                      if (ends("ence")) break; return;
            case 'e': if (ends("er")) break; return;
            case 'i': if (ends("ic")) break; return;
            case 'l': if (ends("able")) break;
                      if (ends("ible")) break; return;
            case 'n': if (ends("ant")) break;
                      if (ends("ement")) break;
                      if (ends("ment")) break;
                      /* element etc. not stripped before the m */
                      if (ends("ent")) break; return;
            case 'o': if (ends("ion") && j >= 0 && (b[j] == 's' || b[j] == 't')) break;
                                      /* j >= 0 fixes Bug 2 */
                      if (ends("ou")) break; return;
                      /* takes care of -ous */
            case 's': if (ends("ism")) break; return;
            case 't': if (ends("ate")) break;
                      if (ends("iti")) break; return;
            case 'u': if (ends("ous")) break; return;
            case 'v': if (ends("ive")) break; return;
            case 'z': if (ends("ize")) break; return;
            default: return;
         }
         if (m() > 1) k = j;
     }
  
     /* step6() removes a final -e if m() > 1. */
  
     private final void step6()
     {  j = k;
        if (b[k] == 'e')
        {  int a = m();
           if (a > 1 || a == 1 && !cvc(k-1)) k--;
        }
        if (b[k] == 'l' && doublec(k) && m() > 1) k--;
     }
  
     /** Stem the word placed into the Stemmer buffer through calls to add().
      * Returns true if the stemming process resulted in a word different
      * from the input.  You can retrieve the result with
      * getResultLength()/getResultBuffer() or toString().
      */
     public void stem()
     {  k = i - 1;
        if (k > 1) { step1(); step2(); step3(); step4(); step5(); step6(); }
        i_end = k+1; i = 0;
     }
  
     public static String get_stem(String string) {
         
         String stem_string = "";
         char[] w = new char[501];
         int j = 0;
         PorterStemmer s = new PorterStemmer();       
         for (char ch : string.toCharArray()) {
             
             if (Character.isLetter((char) ch)) {
                 ch = Character.toLowerCase((char) ch);
                 w[j] = (char) ch;
                 
                 if (j < 500) j++;
                 
                 if (!Character.isLetter((char) ch)) {
                     for (int c = 0; c < j; c++) s.add(w[c]);
                     s.stem();
                     stem_string = s.toString();
                     break;
  
                  }   
             }
             
         }
         
         if (stem_string.equals("")) {
             for (int c = 0; c < j; c++) s.add(w[c]);
             s.stem();
             stem_string = s.toString();           
         }
         
         return stem_string;
     }
     
     public static void main(String[] args) {
         if (args.length == 1) {
             System.out.println("stem is: "+get_stem(args[0]));
         }
         else {
             System.out.println("Usage: java GeneralScripts.PorterStemmer <word>");
             System.exit(1);
         }
     }
  
  }
  