| package org.apache.lucene.analysis.th; |
| |
| /** |
| * Copyright 2006 The Apache Software Foundation |
| * |
| * Licensed 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. |
| */ |
| |
| import java.io.IOException; |
| import java.io.Reader; |
| |
| import org.apache.lucene.analysis.Analyzer; |
| import org.apache.lucene.analysis.TokenStream; |
| import org.apache.lucene.analysis.Tokenizer; |
| import org.apache.lucene.analysis.core.LowerCaseFilter; |
| import org.apache.lucene.analysis.core.StopAnalyzer; |
| import org.apache.lucene.analysis.core.StopFilter; |
| import org.apache.lucene.analysis.standard.StandardFilter; |
| import org.apache.lucene.analysis.standard.StandardTokenizer; |
| import org.apache.lucene.analysis.util.CharArraySet; |
| import org.apache.lucene.analysis.util.StopwordAnalyzerBase; |
| import org.apache.lucene.util.Version; |
| |
| /** |
| * {@link Analyzer} for Thai language. It uses {@link java.text.BreakIterator} to break words. |
| * <p> |
| * <a name="version"/> |
| * <p>You must specify the required {@link Version} |
| * compatibility when creating ThaiAnalyzer: |
| * <ul> |
| * <li> As of 3.6, a set of Thai stopwords is used by default |
| * </ul> |
| */ |
| public final class ThaiAnalyzer extends StopwordAnalyzerBase { |
| |
| /** File containing default Thai stopwords. */ |
| public final static String DEFAULT_STOPWORD_FILE = "stopwords.txt"; |
| /** |
| * The comment character in the stopwords file. |
| * All lines prefixed with this will be ignored. |
| */ |
| private static final String STOPWORDS_COMMENT = "#"; |
| |
| /** |
| * 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 = loadStopwordSet(false, ThaiAnalyzer.class, |
| DEFAULT_STOPWORD_FILE, STOPWORDS_COMMENT); |
| } 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. |
| */ |
| public ThaiAnalyzer() { |
| this(DefaultSetHolder.DEFAULT_STOP_SET); |
| } |
| |
| /** |
| * @deprecated Use {@link #ThaiAnalyzer()} |
| */ |
| @Deprecated |
| public ThaiAnalyzer(Version matchVersion) { |
| this(matchVersion, matchVersion.onOrAfter(Version.LUCENE_3_6) ? DefaultSetHolder.DEFAULT_STOP_SET : StopAnalyzer.ENGLISH_STOP_WORDS_SET); |
| } |
| |
| /** |
| * Builds an analyzer with the given stop words. |
| * |
| * @param stopwords a stopword set |
| */ |
| public ThaiAnalyzer(CharArraySet stopwords) { |
| super(stopwords); |
| } |
| |
| /** |
| * @deprecated Use {@link #ThaiAnalyzer(CharArraySet)} |
| */ |
| @Deprecated |
| public ThaiAnalyzer(Version matchVersion, CharArraySet stopwords) { |
| super(matchVersion, stopwords); |
| } |
| |
| /** |
| * Creates |
| * {@link org.apache.lucene.analysis.Analyzer.TokenStreamComponents} |
| * used to tokenize all the text in the provided {@link Reader}. |
| * |
| * @return {@link org.apache.lucene.analysis.Analyzer.TokenStreamComponents} |
| * built from a {@link StandardTokenizer} filtered with |
| * {@link StandardFilter}, {@link LowerCaseFilter}, {@link ThaiWordFilter}, and |
| * {@link StopFilter} |
| */ |
| @Override |
| protected TokenStreamComponents createComponents(String fieldName, |
| Reader reader) { |
| if (getVersion().onOrAfter(Version.LUCENE_4_8_0)) { |
| final Tokenizer source = new ThaiTokenizer(reader); |
| TokenStream result = new LowerCaseFilter(getVersion(), source); |
| result = new StopFilter(getVersion(), result, stopwords); |
| return new TokenStreamComponents(source, result); |
| } else { |
| final Tokenizer source = new StandardTokenizer(getVersion(), reader); |
| TokenStream result = new StandardFilter(getVersion(), source); |
| if (getVersion().onOrAfter(Version.LUCENE_3_1_0)) |
| result = new LowerCaseFilter(getVersion(), result); |
| result = new ThaiWordFilter(getVersion(), result); |
| return new TokenStreamComponents(source, new StopFilter(getVersion(), |
| result, stopwords)); |
| } |
| } |
| } |