1 package org.apache.lucene.analysis.el;
4 * Copyright 2005 The Apache Software Foundation
6 * Licensed under the Apache License, Version 2.0 (the "License");
7 * you may not use this file except in compliance with the License.
8 * You may obtain a copy of the License at
10 * http://www.apache.org/licenses/LICENSE-2.0
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
19 import org.apache.lucene.analysis.Analyzer;
20 import org.apache.lucene.analysis.StopFilter;
21 import org.apache.lucene.analysis.StopwordAnalyzerBase;
22 import org.apache.lucene.analysis.TokenStream;
23 import org.apache.lucene.analysis.Tokenizer;
24 import org.apache.lucene.analysis.standard.StandardFilter;
25 import org.apache.lucene.analysis.standard.StandardTokenizer;
26 import org.apache.lucene.analysis.standard.StandardAnalyzer; // for javadoc
27 import org.apache.lucene.util.Version;
29 import java.io.IOException;
30 import java.io.Reader;
35 * {@link Analyzer} for the Greek language.
37 * Supports an external list of stopwords (words
38 * that will not be indexed at all).
39 * A default set of stopwords is used unless an alternative list is specified.
43 * <p>You must specify the required {@link Version}
44 * compatibility when creating GreekAnalyzer:
46 * <li> As of 3.1, StandardFilter and GreekStemmer are used by default.
47 * <li> As of 2.9, StopFilter preserves position
51 * <p><b>NOTE</b>: This class uses the same {@link Version}
52 * dependent settings as {@link StandardAnalyzer}.</p>
54 public final class GreekAnalyzer extends StopwordAnalyzerBase {
55 /** File containing default Greek stopwords. */
56 public final static String DEFAULT_STOPWORD_FILE = "stopwords.txt";
59 * Returns a set of default Greek-stopwords
60 * @return a set of default Greek-stopwords
62 public static final Set<?> getDefaultStopSet(){
63 return DefaultSetHolder.DEFAULT_SET;
66 private static class DefaultSetHolder {
67 private static final Set<?> DEFAULT_SET;
71 DEFAULT_SET = loadStopwordSet(false, GreekAnalyzer.class, DEFAULT_STOPWORD_FILE, "#");
72 } catch (IOException ex) {
73 // default set should always be present as it is part of the
75 throw new RuntimeException("Unable to load default stopword set");
81 * Builds an analyzer with the default stop words.
82 * @param matchVersion Lucene compatibility version,
83 * See <a href="#version">above</a>
85 public GreekAnalyzer(Version matchVersion) {
86 this(matchVersion, DefaultSetHolder.DEFAULT_SET);
90 * Builds an analyzer with the given stop words.
92 * <b>NOTE:</b> The stopwords set should be pre-processed with the logic of
93 * {@link GreekLowerCaseFilter} for best results.
95 * @param matchVersion Lucene compatibility version,
96 * See <a href="#version">above</a>
97 * @param stopwords a stopword set
99 public GreekAnalyzer(Version matchVersion, Set<?> stopwords) {
100 super(matchVersion, stopwords);
104 * Builds an analyzer with the given stop words.
105 * @param stopwords Array of stopwords to use.
106 * @deprecated use {@link #GreekAnalyzer(Version, Set)} instead
109 public GreekAnalyzer(Version matchVersion, String... stopwords) {
110 this(matchVersion, StopFilter.makeStopSet(matchVersion, stopwords));
114 * Builds an analyzer with the given stop words.
115 * @deprecated use {@link #GreekAnalyzer(Version, Set)} instead
118 public GreekAnalyzer(Version matchVersion, Map<?,?> stopwords) {
119 this(matchVersion, stopwords.keySet());
124 * {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
125 * used to tokenize all the text in the provided {@link Reader}.
127 * @return {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
128 * built from a {@link StandardTokenizer} filtered with
129 * {@link GreekLowerCaseFilter}, {@link StandardFilter},
130 * {@link StopFilter}, and {@link GreekStemFilter}
133 protected TokenStreamComponents createComponents(String fieldName,
135 final Tokenizer source = new StandardTokenizer(matchVersion, reader);
136 TokenStream result = new GreekLowerCaseFilter(matchVersion, source);
137 if (matchVersion.onOrAfter(Version.LUCENE_31))
138 result = new StandardFilter(matchVersion, result);
139 result = new StopFilter(matchVersion, result, stopwords);
140 if (matchVersion.onOrAfter(Version.LUCENE_31))
141 result = new GreekStemFilter(result);
142 return new TokenStreamComponents(source, result);