/*
 * 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
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.
 */
package org.apache.lucene.analysis.bg;


import static org.apache.lucene.analysis.util.StemmerUtil.*;

Light Stemmer for Bulgarian.

Implements the algorithm described in: Searching Strategies for the Bulgarian Language http://members.unine.ch/jacques.savoy/Papers/BUIR.pdf

/** * Light Stemmer for Bulgarian. * <p> * Implements the algorithm described in: * <i> * Searching Strategies for the Bulgarian Language * </i> * http://members.unine.ch/jacques.savoy/Papers/BUIR.pdf */
public class BulgarianStemmer {
Stem an input buffer of Bulgarian text.
Params:
  • s – input buffer
  • len – length of input buffer
Returns:length of input buffer after normalization
/** * Stem an input buffer of Bulgarian text. * * @param s input buffer * @param len length of input buffer * @return length of input buffer after normalization */
public int stem(final char s[], int len) { if (len < 4) // do not stem return len; if (len > 5 && endsWith(s, len, "ища")) return len - 3; len = removeArticle(s, len); len = removePlural(s, len); if (len > 3) { if (endsWith(s, len, "я")) len--; if (endsWith(s, len, "а") || endsWith(s, len, "о") || endsWith(s, len, "е")) len--; } // the rule to rewrite ен -> н is duplicated in the paper. // in the perl implementation referenced by the paper, this is fixed. // (it is fixed here as well) if (len > 4 && endsWith(s, len, "ен")) { s[len - 2] = 'н'; // replace with н len--; } if (len > 5 && s[len - 2] == 'ъ') { s[len - 2] = s[len - 1]; // replace ъN with N len--; } return len; }
Mainly remove the definite article
Params:
  • s – input buffer
  • len – length of input buffer
Returns:new stemmed length
/** * Mainly remove the definite article * @param s input buffer * @param len length of input buffer * @return new stemmed length */
private int removeArticle(final char s[], final int len) { if (len > 6 && endsWith(s, len, "ият")) return len - 3; if (len > 5) { if (endsWith(s, len, "ът") || endsWith(s, len, "то") || endsWith(s, len, "те") || endsWith(s, len, "та") || endsWith(s, len, "ия")) return len - 2; } if (len > 4 && endsWith(s, len, "ят")) return len - 2; return len; } private int removePlural(final char s[], final int len) { if (len > 6) { if (endsWith(s, len, "овци")) return len - 3; // replace with о if (endsWith(s, len, "ове")) return len - 3; if (endsWith(s, len, "еве")) { s[len - 3] = 'й'; // replace with й return len - 2; } } if (len > 5) { if (endsWith(s, len, "ища")) return len - 3; if (endsWith(s, len, "та")) return len - 2; if (endsWith(s, len, "ци")) { s[len - 2] = 'к'; // replace with к return len - 1; } if (endsWith(s, len, "зи")) { s[len - 2] = 'г'; // replace with г return len - 1; } if (s[len - 3] == 'е' && s[len - 1] == 'и') { s[len - 3] = 'я'; // replace е with я, remove и return len - 1; } } if (len > 4) { if (endsWith(s, len, "си")) { s[len - 2] = 'х'; // replace with х return len - 1; } if (endsWith(s, len, "и")) return len - 1; } return len; } }