1
package org.apache.lucene.analysis.it;
4
* Licensed to the Apache Software Foundation (ASF) under one or more
5
* contributor license agreements. See the NOTICE file distributed with
6
* this work for additional information regarding copyright ownership.
7
* The ASF licenses this file to You under the Apache License, Version 2.0
8
* (the "License"); you may not use this file except in compliance with
9
* the License. You may obtain a copy of the License at
11
* http://www.apache.org/licenses/LICENSE-2.0
13
* Unless required by applicable law or agreed to in writing, software
14
* distributed under the License is distributed on an "AS IS" BASIS,
15
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16
* See the License for the specific language governing permissions and
17
* limitations under the License.
20
import java.io.IOException;
21
import java.io.Reader;
22
import java.util.Arrays;
25
import org.apache.lucene.analysis.Analyzer;
26
import org.apache.lucene.analysis.CharArraySet;
27
import org.apache.lucene.analysis.KeywordMarkerFilter;
28
import org.apache.lucene.analysis.LowerCaseFilter;
29
import org.apache.lucene.analysis.StopFilter;
30
import org.apache.lucene.analysis.StopwordAnalyzerBase;
31
import org.apache.lucene.analysis.fr.ElisionFilter;
32
import org.apache.lucene.analysis.TokenStream;
33
import org.apache.lucene.analysis.Tokenizer;
34
import org.apache.lucene.analysis.WordlistLoader;
35
import org.apache.lucene.analysis.snowball.SnowballFilter;
36
import org.apache.lucene.analysis.standard.StandardFilter;
37
import org.apache.lucene.analysis.standard.StandardTokenizer;
38
import org.apache.lucene.util.IOUtils;
39
import org.apache.lucene.util.Version;
40
import org.tartarus.snowball.ext.ItalianStemmer;
43
* {@link Analyzer} for Italian.
46
* <p>You must specify the required {@link Version}
47
* compatibility when creating ItalianAnalyzer:
49
* <li> As of 3.2, ElisionFilter with a set of Italian
50
* contractions is used by default.
53
public final class ItalianAnalyzer extends StopwordAnalyzerBase {
54
private final Set<?> stemExclusionSet;
56
/** File containing default Italian stopwords. */
57
public final static String DEFAULT_STOPWORD_FILE = "italian_stop.txt";
59
private static final CharArraySet DEFAULT_ARTICLES = CharArraySet.unmodifiableSet(
60
new CharArraySet(Version.LUCENE_CURRENT,
62
"c", "l", "all", "dall", "dell", "nell", "sull", "coll", "pell",
63
"gl", "agl", "dagl", "degl", "negl", "sugl", "un", "m", "t", "s", "v", "d"
67
* Returns an unmodifiable instance of the default stop words set.
68
* @return default stop words set.
70
public static Set<?> getDefaultStopSet(){
71
return DefaultSetHolder.DEFAULT_STOP_SET;
75
* Atomically loads the DEFAULT_STOP_SET in a lazy fashion once the outer class
76
* accesses the static final set the first time.;
78
private static class DefaultSetHolder {
79
static final Set<?> DEFAULT_STOP_SET;
83
DEFAULT_STOP_SET = WordlistLoader.getSnowballWordSet(IOUtils.getDecodingReader(SnowballFilter.class,
84
DEFAULT_STOPWORD_FILE, IOUtils.CHARSET_UTF_8), Version.LUCENE_CURRENT);
85
} catch (IOException ex) {
86
// default set should always be present as it is part of the
88
throw new RuntimeException("Unable to load default stopword set");
94
* Builds an analyzer with the default stop words: {@link #DEFAULT_STOPWORD_FILE}.
96
public ItalianAnalyzer(Version matchVersion) {
97
this(matchVersion, DefaultSetHolder.DEFAULT_STOP_SET);
101
* Builds an analyzer with the given stop words.
103
* @param matchVersion lucene compatibility version
104
* @param stopwords a stopword set
106
public ItalianAnalyzer(Version matchVersion, Set<?> stopwords) {
107
this(matchVersion, stopwords, CharArraySet.EMPTY_SET);
111
* Builds an analyzer with the given stop words. If a non-empty stem exclusion set is
112
* provided this analyzer will add a {@link KeywordMarkerFilter} before
115
* @param matchVersion lucene compatibility version
116
* @param stopwords a stopword set
117
* @param stemExclusionSet a set of terms not to be stemmed
119
public ItalianAnalyzer(Version matchVersion, Set<?> stopwords, Set<?> stemExclusionSet) {
120
super(matchVersion, stopwords);
121
this.stemExclusionSet = CharArraySet.unmodifiableSet(CharArraySet.copy(
122
matchVersion, stemExclusionSet));
127
* {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
128
* which tokenizes all the text in the provided {@link Reader}.
131
* {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
132
* built from an {@link StandardTokenizer} filtered with
133
* {@link StandardFilter}, {@link ElisionFilter}, {@link LowerCaseFilter}, {@link StopFilter}
134
* , {@link KeywordMarkerFilter} if a stem exclusion set is
135
* provided and {@link SnowballFilter}.
138
protected TokenStreamComponents createComponents(String fieldName,
140
final Tokenizer source = new StandardTokenizer(matchVersion, reader);
141
TokenStream result = new StandardFilter(matchVersion, source);
142
if (matchVersion.onOrAfter(Version.LUCENE_32)) {
143
result = new ElisionFilter(matchVersion, result, DEFAULT_ARTICLES);
145
result = new LowerCaseFilter(matchVersion, result);
146
result = new StopFilter(matchVersion, result, stopwords);
147
if(!stemExclusionSet.isEmpty())
148
result = new KeywordMarkerFilter(result, stemExclusionSet);
149
result = new SnowballFilter(result, new ItalianStemmer());
150
return new TokenStreamComponents(source, result);