| using Lucene.Net.Analysis; |
| using Lucene.Net.Analysis.Core; |
| using Lucene.Net.Analysis.Miscellaneous; |
| using Lucene.Net.Analysis.Snowball; |
| using Lucene.Net.Analysis.Standard; |
| using Lucene.Net.Analysis.Util; |
| using Lucene.Net.Support; |
| using Lucene.Net.Tartarus.Snowball.Ext; |
| using Lucene.Net.Util; |
| using System; |
| using System.IO; |
| using System.Text; |
| |
| namespace Lucene.Net.Analysis.De |
| { |
| // This file is encoded in UTF-8 |
| |
| /* |
| * 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. |
| */ |
| |
| /// <summary> |
| /// <seealso cref="Analyzer"/> for German language. |
| /// <para> |
| /// Supports an external list of stopwords (words that |
| /// will not be indexed at all) and an external list of exclusions (word that will |
| /// not be stemmed, but indexed). |
| /// A default set of stopwords is used unless an alternative list is specified, but the |
| /// exclusion list is empty by default. |
| /// </para> |
| /// |
| /// <a name="version"/> |
| /// <para>You must specify the required <seealso cref="Version"/> |
| /// compatibility when creating GermanAnalyzer: |
| /// <ul> |
| /// <li> As of 3.6, GermanLightStemFilter is used for less aggressive stemming. |
| /// <li> As of 3.1, Snowball stemming is done with SnowballFilter, and |
| /// Snowball stopwords are used by default. |
| /// <li> As of 2.9, StopFilter preserves position |
| /// increments |
| /// </ul> |
| /// |
| /// </para> |
| /// <para><b>NOTE</b>: This class uses the same <seealso cref="Version"/> |
| /// dependent settings as <seealso cref="StandardAnalyzer"/>.</para> |
| /// </summary> |
| public sealed class GermanAnalyzer : StopwordAnalyzerBase |
| { |
| |
| /// @deprecated in 3.1, remove in Lucene 5.0 (index bw compat) |
| [Obsolete("in 3.1, remove in Lucene 5.0 (index bw compat)")] |
| private static readonly string[] GERMAN_STOP_WORDS = new string[] { "einer", "eine", "eines", "einem", "einen", "der", "die", "das", "dass", "daß", "du", "er", "sie", "es", "was", "wer", "wie", "wir", "und", "oder", "ohne", "mit", "am", "im", "in", "aus", "auf", "ist", "sein", "war", "wird", "ihr", "ihre", "ihres", "als", "für", "von", "mit", "dich", "dir", "mich", "mir", "mein", "sein", "kein", "durch", "wegen", "wird" }; |
| |
| /// <summary> |
| /// File containing default German stopwords. </summary> |
| public const string DEFAULT_STOPWORD_FILE = "german_stop.txt"; |
| |
| /// <summary> |
| /// Returns a set of default German-stopwords </summary> |
| /// <returns> a set of default German-stopwords </returns> |
| public static CharArraySet DefaultStopSet |
| { |
| get |
| { |
| return DefaultSetHolder.DEFAULT_SET; |
| } |
| } |
| |
| private class DefaultSetHolder |
| { |
| /// @deprecated in 3.1, remove in Lucene 5.0 (index bw compat) |
| [Obsolete("in 3.1, remove in Lucene 5.0 (index bw compat)")] |
| internal static readonly CharArraySet DEFAULT_SET_30 = CharArraySet.UnmodifiableSet(new CharArraySet(LuceneVersion.LUCENE_CURRENT, Arrays.AsList(GERMAN_STOP_WORDS), false)); |
| internal static readonly CharArraySet DEFAULT_SET; |
| static DefaultSetHolder() |
| { |
| try |
| { |
| DEFAULT_SET = WordlistLoader.GetSnowballWordSet( |
| IOUtils.GetDecodingReader(typeof(SnowballFilter), typeof(SnowballFilter).Namespace + "." + DEFAULT_STOPWORD_FILE, Encoding.UTF8), |
| LuceneVersion.LUCENE_CURRENT); |
| } |
| catch (IOException) |
| { |
| // default set should always be present as it is part of the |
| // distribution (JAR) |
| throw new Exception("Unable to load default stopword set"); |
| } |
| } |
| } |
| |
| /// <summary> |
| /// Contains the stopwords used with the <seealso cref="StopFilter"/>. |
| /// </summary> |
| |
| /// <summary> |
| /// Contains words that should be indexed but not stemmed. |
| /// </summary> |
| private readonly CharArraySet exclusionSet; |
| |
| /// <summary> |
| /// Builds an analyzer with the default stop words: |
| /// <seealso cref="#getDefaultStopSet()"/>. |
| /// </summary> |
| public GermanAnalyzer(LuceneVersion matchVersion) |
| : this(matchVersion, matchVersion.OnOrAfter(LuceneVersion.LUCENE_31) ? DefaultSetHolder.DEFAULT_SET : DefaultSetHolder.DEFAULT_SET_30) |
| { |
| } |
| |
| /// <summary> |
| /// Builds an analyzer with the given stop words |
| /// </summary> |
| /// <param name="matchVersion"> |
| /// lucene compatibility version </param> |
| /// <param name="stopwords"> |
| /// a stopword set </param> |
| public GermanAnalyzer(LuceneVersion matchVersion, CharArraySet stopwords) |
| : this(matchVersion, stopwords, CharArraySet.EMPTY_SET) |
| { |
| } |
| |
| /// <summary> |
| /// Builds an analyzer with the given stop words |
| /// </summary> |
| /// <param name="matchVersion"> |
| /// lucene compatibility version </param> |
| /// <param name="stopwords"> |
| /// a stopword set </param> |
| /// <param name="stemExclusionSet"> |
| /// a stemming exclusion set </param> |
| public GermanAnalyzer(LuceneVersion matchVersion, CharArraySet stopwords, CharArraySet stemExclusionSet) |
| : base(matchVersion, stopwords) |
| { |
| exclusionSet = CharArraySet.UnmodifiableSet(CharArraySet.Copy(matchVersion, stemExclusionSet)); |
| } |
| |
| /// <summary> |
| /// Creates |
| /// <seealso cref="org.apache.lucene.analysis.Analyzer.TokenStreamComponents"/> |
| /// used to tokenize all the text in the provided <seealso cref="Reader"/>. |
| /// </summary> |
| /// <returns> <seealso cref="org.apache.lucene.analysis.Analyzer.TokenStreamComponents"/> |
| /// built from a <seealso cref="StandardTokenizer"/> filtered with |
| /// <seealso cref="StandardFilter"/>, <seealso cref="LowerCaseFilter"/>, <seealso cref="StopFilter"/> |
| /// , <seealso cref="SetKeywordMarkerFilter"/> if a stem exclusion set is |
| /// provided, <seealso cref="GermanNormalizationFilter"/> and <seealso cref="GermanLightStemFilter"/> </returns> |
| public override TokenStreamComponents CreateComponents(string fieldName, TextReader reader) |
| { |
| Tokenizer source = new StandardTokenizer(matchVersion, reader); |
| TokenStream result = new StandardFilter(matchVersion, source); |
| result = new LowerCaseFilter(matchVersion, result); |
| result = new StopFilter(matchVersion, result, stopwords); |
| result = new SetKeywordMarkerFilter(result, exclusionSet); |
| if (matchVersion.OnOrAfter(LuceneVersion.LUCENE_36)) |
| { |
| result = new GermanNormalizationFilter(result); |
| result = new GermanLightStemFilter(result); |
| } |
| else if (matchVersion.OnOrAfter(LuceneVersion.LUCENE_31)) |
| { |
| result = new SnowballFilter(result, new German2Stemmer()); |
| } |
| else |
| { |
| result = new GermanStemFilter(result); |
| } |
| return new TokenStreamComponents(source, result); |
| } |
| } |
| } |
