--- /dev/null
+package org.apache.lucene.analysis.da;
+
+/**
+ * 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.
+ */
+
+import java.io.IOException;
+import java.io.Reader;
+import java.util.Set;
+
+import org.apache.lucene.analysis.Analyzer;
+import org.apache.lucene.analysis.CharArraySet;
+import org.apache.lucene.analysis.KeywordMarkerFilter;
+import org.apache.lucene.analysis.LowerCaseFilter;
+import org.apache.lucene.analysis.StopFilter;
+import org.apache.lucene.analysis.StopwordAnalyzerBase;
+import org.apache.lucene.analysis.TokenStream;
+import org.apache.lucene.analysis.Tokenizer;
+import org.apache.lucene.analysis.WordlistLoader;
+import org.apache.lucene.analysis.snowball.SnowballFilter;
+import org.apache.lucene.analysis.standard.StandardFilter;
+import org.apache.lucene.analysis.standard.StandardTokenizer;
+import org.apache.lucene.util.IOUtils;
+import org.apache.lucene.util.Version;
+import org.tartarus.snowball.ext.DanishStemmer;
+
+/**
+ * {@link Analyzer} for Danish.
+ */
+public final class DanishAnalyzer extends StopwordAnalyzerBase {
+ private final Set<?> stemExclusionSet;
+
+ /** File containing default Danish stopwords. */
+ public final static String DEFAULT_STOPWORD_FILE = "danish_stop.txt";
+
+ /**
+ * Returns an unmodifiable instance of the default stop words set.
+ * @return default stop words set.
+ */
+ public static Set<?> 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 Set<?> DEFAULT_STOP_SET;
+
+ static {
+ try {
+ DEFAULT_STOP_SET = WordlistLoader.getSnowballWordSet(IOUtils.getDecodingReader(SnowballFilter.class,
+ DEFAULT_STOPWORD_FILE, IOUtils.CHARSET_UTF_8), Version.LUCENE_CURRENT);
+ } 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: {@link #DEFAULT_STOPWORD_FILE}.
+ */
+ public DanishAnalyzer(Version matchVersion) {
+ this(matchVersion, DefaultSetHolder.DEFAULT_STOP_SET);
+ }
+
+ /**
+ * Builds an analyzer with the given stop words.
+ *
+ * @param matchVersion lucene compatibility version
+ * @param stopwords a stopword set
+ */
+ public DanishAnalyzer(Version matchVersion, Set<?> stopwords) {
+ this(matchVersion, stopwords, CharArraySet.EMPTY_SET);
+ }
+
+ /**
+ * Builds an analyzer with the given stop words. If a non-empty stem exclusion set is
+ * provided this analyzer will add a {@link KeywordMarkerFilter} before
+ * stemming.
+ *
+ * @param matchVersion lucene compatibility version
+ * @param stopwords a stopword set
+ * @param stemExclusionSet a set of terms not to be stemmed
+ */
+ public DanishAnalyzer(Version matchVersion, Set<?> stopwords, Set<?> stemExclusionSet) {
+ super(matchVersion, stopwords);
+ this.stemExclusionSet = CharArraySet.unmodifiableSet(CharArraySet.copy(
+ matchVersion, stemExclusionSet));
+ }
+
+ /**
+ * Creates a
+ * {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
+ * which tokenizes all the text in the provided {@link Reader}.
+ *
+ * @return A
+ * {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
+ * built from an {@link StandardTokenizer} filtered with
+ * {@link StandardFilter}, {@link LowerCaseFilter}, {@link StopFilter}
+ * , {@link KeywordMarkerFilter} if a stem exclusion set is
+ * provided and {@link SnowballFilter}.
+ */
+ @Override
+ protected TokenStreamComponents createComponents(String fieldName,
+ Reader reader) {
+ final Tokenizer source = new StandardTokenizer(matchVersion, reader);
+ TokenStream result = new StandardFilter(matchVersion, source);
+ result = new LowerCaseFilter(matchVersion, result);
+ result = new StopFilter(matchVersion, result, stopwords);
+ if(!stemExclusionSet.isEmpty())
+ result = new KeywordMarkerFilter(result, stemExclusionSet);
+ result = new SnowballFilter(result, new DanishStemmer());
+ return new TokenStreamComponents(source, result);
+ }
+}