| /* |
| * 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.uk; |
| |
| |
| import java.io.IOException; |
| import java.io.Reader; |
| import java.nio.charset.StandardCharsets; |
| |
| import morfologik.stemming.Dictionary; |
| import org.apache.lucene.analysis.Analyzer; |
| import org.apache.lucene.analysis.CharArraySet; |
| import org.apache.lucene.analysis.LowerCaseFilter; |
| import org.apache.lucene.analysis.StopFilter; |
| import org.apache.lucene.analysis.StopwordAnalyzerBase; |
| import org.apache.lucene.analysis.TokenStream; |
| import org.apache.lucene.analysis.Tokenizer; |
| import org.apache.lucene.analysis.WordlistLoader; |
| import org.apache.lucene.analysis.charfilter.MappingCharFilter; |
| import org.apache.lucene.analysis.charfilter.NormalizeCharMap; |
| import org.apache.lucene.analysis.miscellaneous.SetKeywordMarkerFilter; |
| import org.apache.lucene.analysis.morfologik.MorfologikFilter; |
| import org.apache.lucene.analysis.standard.StandardTokenizer; |
| import org.apache.lucene.util.IOUtils; |
| |
| /** |
| * A dictionary-based {@link Analyzer} for Ukrainian. |
| * |
| * @since 6.2.0 |
| */ |
| public final class UkrainianMorfologikAnalyzer extends StopwordAnalyzerBase { |
| private final CharArraySet stemExclusionSet; |
| |
| /** File containing default Ukrainian stopwords. */ |
| public final static String DEFAULT_STOPWORD_FILE = "stopwords.txt"; |
| |
| /** |
| * Returns an unmodifiable instance of the default stop words set. |
| * @return default stop words set. |
| */ |
| public static CharArraySet getDefaultStopSet() { |
| return DefaultSetHolder.DEFAULT_STOP_SET; |
| } |
| |
| /** |
| * Atomically loads the DEFAULT_STOP_SET in a lazy fashion once the outer class |
| * accesses the static final set the first time.; |
| */ |
| private static class DefaultSetHolder { |
| static final CharArraySet DEFAULT_STOP_SET; |
| |
| static { |
| try { |
| DEFAULT_STOP_SET = WordlistLoader.getSnowballWordSet(IOUtils.getDecodingReader(UkrainianMorfologikAnalyzer.class, |
| DEFAULT_STOPWORD_FILE, StandardCharsets.UTF_8)); |
| } catch (IOException ex) { |
| // default set should always be present as it is part of the |
| // distribution (JAR) |
| throw new RuntimeException("Unable to load default stopword set"); |
| } |
| } |
| } |
| |
| /** |
| * Builds an analyzer with the default stop words: {@link #DEFAULT_STOPWORD_FILE}. |
| */ |
| public UkrainianMorfologikAnalyzer() { |
| this(DefaultSetHolder.DEFAULT_STOP_SET); |
| } |
| |
| /** |
| * Builds an analyzer with the given stop words. |
| * |
| * @param stopwords a stopword set |
| */ |
| public UkrainianMorfologikAnalyzer(CharArraySet stopwords) { |
| this(stopwords, CharArraySet.EMPTY_SET); |
| } |
| |
| /** |
| * Builds an analyzer with the given stop words. If a non-empty stem exclusion set is |
| * provided this analyzer will add a {@link SetKeywordMarkerFilter} before |
| * stemming. |
| * |
| * @param stopwords a stopword set |
| * @param stemExclusionSet a set of terms not to be stemmed |
| */ |
| public UkrainianMorfologikAnalyzer(CharArraySet stopwords, CharArraySet stemExclusionSet) { |
| super(stopwords); |
| this.stemExclusionSet = CharArraySet.unmodifiableSet(CharArraySet.copy(stemExclusionSet)); |
| } |
| |
| @Override |
| protected Reader initReader(String fieldName, Reader reader) { |
| NormalizeCharMap.Builder builder = new NormalizeCharMap.Builder(); |
| // different apostrophes |
| builder.add("\u2019", "'"); |
| builder.add("\u2018", "'"); |
| builder.add("\u02BC", "'"); |
| builder.add("`", "'"); |
| builder.add("´", "'"); |
| // ignored characters |
| builder.add("\u0301", ""); |
| builder.add("\u00AD", ""); |
| builder.add("ґ", "г"); |
| builder.add("Ґ", "Г"); |
| |
| NormalizeCharMap normMap = builder.build(); |
| reader = new MappingCharFilter(normMap, reader); |
| return reader; |
| } |
| |
| /** |
| * Creates a |
| * {@link org.apache.lucene.analysis.Analyzer.TokenStreamComponents} |
| * which tokenizes all the text in the provided {@link Reader}. |
| * |
| * @return A |
| * {@link org.apache.lucene.analysis.Analyzer.TokenStreamComponents} |
| * built from an {@link StandardTokenizer} filtered with |
| * {@link LowerCaseFilter}, {@link StopFilter} |
| * , {@link SetKeywordMarkerFilter} if a stem exclusion set is |
| * provided and {@link MorfologikFilter} on the Ukrainian dictionary. |
| */ |
| @Override |
| protected TokenStreamComponents createComponents(String fieldName) { |
| Tokenizer source = new StandardTokenizer(); |
| TokenStream result = new LowerCaseFilter(source); |
| result = new StopFilter(result, stopwords); |
| |
| if (stemExclusionSet.isEmpty() == false) { |
| result = new SetKeywordMarkerFilter(result, stemExclusionSet); |
| } |
| |
| result = new MorfologikFilter(result, getDictionary()); |
| return new TokenStreamComponents(source, result); |
| } |
| |
| private static Dictionary getDictionary() { |
| try { |
| return Dictionary.read(UkrainianMorfologikAnalyzer.class.getClassLoader().getResource("ua/net/nlp/ukrainian.dict")); |
| } catch (IOException e) { |
| throw new RuntimeException(e); |
| } |
| } |
| } |