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From "Federica Falini Data Management S.p.A" <>
Subject Sort on TermEnum
Date Fri, 08 May 2009 07:58:44 GMT
in Lucene 2.4.1 (as such in Lucene 2.2) the term enumeration is sorted 
case-sensitive: first capital and then small;
For example,  this sort on TermEnum is wrong for human consumption:


this is the correct sort in this case :


In Lucene 2.2 i have made modification on,
(see below)  in order to have  Term enumerations sorted case-insensitive:

TermEnum terms = reader.terms(new Term("myFieldNotTokenized", ""));
      while ("myFieldNotTokenized".equals(terms.term().field())) {
        System.out.println( "     " + terms.term());
        if (! break;

Now in Lucene 2.4 i find it difficult because the package "index" is
changed a lot; can i have some indications to keep my sort?
Thanks in advance

*Here below the modified class on Lucene 2.2*

 package org.apache.lucene.index;

 import java.text.CollationKey;

  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You under the Apache License, Version 2.0
  * (the "License"); you may not use this file except in compliance with
  * the License.  You may obtain a copy of the License at
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.

   A Term represents a word from text.  This is the unit of search.  It is
   composed of two elements, the text of the word, as a string, and the name
   the field that the text occured in, an interned string.

   Note that terms may represent more than words from text fields, but also
   things like dates, email addresses, urls, etc.  */

 public final class Term implements Comparable, {
   String field;
   String text;
   transient CollationKey ckText;

   /** Constructs a Term with the given field and text.
    * <p>Note that a null field or null text value results in undefined
    * behavior for most Lucene APIs that accept a Term parameter. */
   public Term(String fld, String txt) {

     this(fld, txt, true);
   Term(String fld, String txt, boolean intern) {
     field = intern ? fld.intern() : fld;      // field names are interned
     text = txt;                      // unless already known to be
     ckText = OpacCollator.getInstancePool().getCollationKey(text);


   /** Returns the field of this term, an interned string.   The field
     the part of a document which this term came from. */
   public final String field() { return field; }

   /** Returns the text of this term.  In the case of words, this is simply
     text of the word.  In the case of dates and other types, this is an
     encoding of the object as a string.  */
   public final String text() { return text; }

    * Optimized construction of new Terms by reusing same field as this Term
    * - avoids field.intern() overhead
    * @param text The text of the new term (field is implicitly same as this
 Term instance)
    * @return A new Term
   public Term createTerm(String text)
       return new Term(field,text,false);

   /** Compares two terms, returning true iff they have the same
       field and text. */
   public final boolean equals(Object o) {
     if (o == this)
       return true;
     if (o == null)
       return false;
     if (!(o instanceof Term))
       return false;
     Term other = (Term)o;
     //return field == other.field && text.equals(other.text);
     return field == other.field && text.equalsIgnoreCase(other.text);

   /** Combines the hashCode() of the field and the text. */
   public final int hashCode() {
     return field.hashCode() + text.hashCode();

   public int compareTo(Object other) {
     return compareTo((Term)other);

   /** Compares two terms, returning a negative integer if this
     term belongs before the argument, zero if this term is equal to the
     argument, and a positive integer if this term belongs after the

     The ordering of terms is first by field, then by text.*/
 //  public final int compareTo(Term other) {
 //    if (field == other.field)              // fields are interned
 //      return text.compareTo(other.text);
 //    else
 //      return field.compareTo(other.field);
 //  }
   public final int compareTo(Term other) {

       if (field == other.field) { // fields are interned
           return  ckText.compareTo(other.ckText);
       } else {
           return field.compareToIgnoreCase(other.field);

   /** Resets the field and text of a Term. */
   final void set(String fld, String txt) {
     field = fld;
     text = txt;
     ckText = OpacCollator.getInstancePool().getCollationKey(text);

   public final String toString() { return field + ":" + text; }

   private void readObject( in)
     throws, ClassNotFoundException
       field = field.intern();
       ckText = OpacCollator.getInstancePool().getCollationKey(text);


 public final int compareTo(TermBuffer other) {
     if (field == other.field)    {          // fields are interned
       return compareChars(text, textLength, other.text, other.textLength);
     else {
       return field.compareTo(other.field);


 private static final int compareChars(char[] v1, int len1,
                                          char[] v2, int len2) {
     String v1s = new String(v1,0,len1);
     String v2s = new String(v2,0,len2);
     OpacCollator oc = OpacCollator.getInstancePool();
     CollationKey v1k  = oc.getCollationKey(v1s);
     CollationKey v2k  = oc.getCollationKey(v2s);
     return v1k.compareTo(v2k);

 package org.apache.lucene.index;

 import java.text.CollationKey;
 import java.text.Collator;
 import java.text.ParseException;
 import java.text.RuleBasedCollator;
 import java.util.BitSet;
 import java.util.Locale;

 import org.apache.log4j.Logger;

  * Collator che considera lo spazio '\u0020' come primo carattere
  * sembra essere il primo di tutti
 public class OpacCollator extends RuleBasedCollator {
    * logger
   private static Logger log =
   private static String spacesRules = null;
   /** progressivo identificativo oggetto */
   // private static int seqIdPool = 0;
   /** identificativo dell'oggetto */
   private int id = 0;

   private final static int POOL =
   Integer.parseInt(System.getProperty("sebina.opac.collatorpool", "256"));
   private final static OpacCollator[] collatorPool = new OpacCollator[POOL];
   private static BitSet bs = new BitSet(POOL);
   // private static int cntPool = 0;
   static {
     RuleBasedCollator it_ITcollator = (RuleBasedCollator) Collator.getInstance(new Locale("it",
     spacesRules = it_ITcollator.getRules().replaceAll("='\t'=", "=");
     spacesRules = spacesRules.replaceAll(";'\t' ;", ";");
     spacesRules = spacesRules.replaceAll("<'_'", "<'\t'<'\u0020'<'_'");

     for (int i = 0; i < POOL; i++) {
       try {
         collatorPool[i] = new OpacCollator(i);
       } catch (ParseException e) {
         log.fatal("Rules:" + it_ITcollator.getRules(), e);


   public static synchronized OpacCollator getInstancePool() {
     int pos = -1;
     while (pos < 0) {
       pos = bs.nextSetBit(0);
     return collatorPool[pos];

    * Constructor for OpacCollator.
    * @throws ParseException
   private OpacCollator() throws ParseException {

    * Constructor for OpacCollator.
    * @param id
    * @throws ParseException
   public OpacCollator(int ident) throws ParseException {
     this(); = ident;

    * @see java.text.Collator#getCollationKey(String)
   public CollationKey getCollationKey(String arg0) {
     CollationKey ck = super.getCollationKey(arg0);
     return ck;

*Federica FALINI
Divisione Beni Culturali
Data Management S.p.A. 

tel: +39.0544.503.*886*
fax: +39.0544.461697
e-mail: <>
web: <>
48100 - Ravenna (RA)
Via S.Cavina, n 7 
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