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Subject [GitHub] [lucenenet] NightOwl888 commented on issue #246: Custom StopWord Analyzer - Exception Cannot read from a closed TextReader.
Date Tue, 28 Apr 2020 19:28:49 GMT

NightOwl888 commented on issue #246:

   As `CreateComponents()` is a factory method (meaning it is a creational operation), only
short-lived dependencies should be disposed there. Since you are disposing the stream first
before returning it, it is not in a state where the caller of `CreateComponents()` can utilize
   To make a customized standard analyzer, the best approach would be to model your new class
after the [existing StandardAnalyzer class](
       public sealed class MyStopwordAnalyzer : StopwordAnalyzerBase
           /// <summary>
           /// An unmodifiable set containing some common English words that are usually not
           /// useful for searching. 
           /// </summary>
           public static readonly CharArraySet STOP_WORDS_SET = LoadEnglishStopWordsSet();
           private static CharArraySet LoadEnglishStopWordsSet() // LUCENENET: Avoid static
constructors (see
               IList<string> stopWords = new string[] { "a", "an", "and", "are", "as",
"at", "be",
                   "but", "by", "for", "if", "in", "into", "is", "it", "no", "not", "of",
                   "or", "such", "that", "the", "their", "then", "there", "these", "they",
                   "to", "was", "will", "with" };
   #pragma warning disable 612, 618
               var stopSet = new CharArraySet(LuceneVersion.LUCENE_CURRENT, stopWords, false);
   #pragma warning restore 612, 618
               return CharArraySet.UnmodifiableSet(stopSet);
           /// <summary>
           /// Builds an analyzer with the given stop words. </summary>
           /// <param name="matchVersion"> Lucene compatibility version - See <see
cref="MyStopwordAnalyzer"/> </param>
           /// <param name="stopWords"> stop words  </param>
           public MyStopwordAnalyzer(LuceneVersion matchVersion, CharArraySet stopWords)
               : base(matchVersion, stopWords)
           /// <summary>
           /// Builds an analyzer with the default stop words (<see cref="STOP_WORDS_SET"/>).
           /// <param name="matchVersion"> Lucene compatibility version - See <see
cref="MyStopwordAnalyzer"/> </param>
           public MyStopwordAnalyzer(LuceneVersion matchVersion)
               : this(matchVersion, STOP_WORDS_SET)
           /// <summary>
           /// Builds an analyzer with the stop words from the given reader. </summary>
           /// <seealso cref="WordlistLoader.GetWordSet(TextReader, LuceneVersion)"/>
           /// <param name="matchVersion"> Lucene compatibility version - See <see
cref="MyStopwordAnalyzer"/> </param>
           /// <param name="stopwords"> <see cref="TextReader"/> to read stop
words from  </param>
           public MyStopwordAnalyzer(LuceneVersion matchVersion, TextReader stopwords)
               : this(matchVersion, LoadStopwordSet(stopwords, matchVersion))
           protected override TokenStreamComponents CreateComponents(string fieldName, TextReader
               var src = new StandardTokenizer(m_matchVersion, reader);
               TokenStream tok = new StandardFilter(m_matchVersion, src);
               // tok = new LowerCaseFilter(m_matchVersion, tok); // optional
               tok = new StopFilter(m_matchVersion, tok, m_stopwords);
               return new TokenStreamComponents(src, tok);
   Do note that the existing `StandardAnalyzer` class also allows passing in a `CharArraySet`
containing stopwords, which may meet your needs if you wish to use the `LowerCaseFilter` to
normalize your text.

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