--- /dev/null
+package org.apache.lucene.analysis.nl;
+
+/**
+ * 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 org.apache.lucene.analysis.Analyzer;
+import org.apache.lucene.analysis.CharArrayMap;
+import org.apache.lucene.analysis.CharArraySet;
+import org.apache.lucene.analysis.KeywordMarkerFilter;
+import org.apache.lucene.analysis.LowerCaseFilter;
+import org.apache.lucene.analysis.ReusableAnalyzerBase;
+import org.apache.lucene.analysis.StopFilter;
+import org.apache.lucene.analysis.TokenStream;
+import org.apache.lucene.analysis.Tokenizer;
+import org.apache.lucene.analysis.WordlistLoader;
+import org.apache.lucene.analysis.miscellaneous.StemmerOverrideFilter;
+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.analysis.standard.StandardAnalyzer; // for javadoc
+import org.apache.lucene.util.IOUtils;
+import org.apache.lucene.util.Version;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.Reader;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.Map;
+
+/**
+ * {@link Analyzer} for Dutch language.
+ * <p>
+ * Supports an external list of stopwords (words that
+ * will not be indexed at all), an external list of exclusions (word that will
+ * not be stemmed, but indexed) and an external list of word-stem pairs that overrule
+ * the algorithm (dictionary stemming).
+ * A default set of stopwords is used unless an alternative list is specified, but the
+ * exclusion list is empty by default.
+ * </p>
+ *
+ * <a name="version"/>
+ * <p>You must specify the required {@link Version}
+ * compatibility when creating DutchAnalyzer:
+ * <ul>
+ * <li> As of 3.1, Snowball stemming is done with SnowballFilter,
+ * LowerCaseFilter is used prior to StopFilter, and Snowball
+ * stopwords are used by default.
+ * <li> As of 2.9, StopFilter preserves position
+ * increments
+ * </ul>
+ *
+ * <p><b>NOTE</b>: This class uses the same {@link Version}
+ * dependent settings as {@link StandardAnalyzer}.</p>
+ */
+public final class DutchAnalyzer extends ReusableAnalyzerBase {
+ /**
+ * List of typical Dutch stopwords.
+ * @deprecated use {@link #getDefaultStopSet()} instead
+ */
+ @Deprecated
+ public final static String[] DUTCH_STOP_WORDS;
+
+ /** File containing default Dutch stopwords. */
+ public final static String DEFAULT_STOPWORD_FILE = "dutch_stop.txt";
+
+ static {
+ Set<?> defaultStopSet = getDefaultStopSet();
+ DUTCH_STOP_WORDS = new String[defaultStopSet.size()];
+ int i = 0;
+ for (Object object: defaultStopSet) {
+ DUTCH_STOP_WORDS[i++] = new String((char[])object);
+ } // what a hack!
+ }
+
+ /**
+ * Returns an unmodifiable instance of the default stop-words set.
+ * @return an unmodifiable instance of the default stop-words set.
+ */
+ public static Set<?> getDefaultStopSet(){
+ return DefaultSetHolder.DEFAULT_STOP_SET;
+ }
+
+ 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");
+ }
+ }
+
+ }
+
+
+ /**
+ * Contains the stopwords used with the StopFilter.
+ */
+ private final Set<?> stoptable;
+
+ /**
+ * Contains words that should be indexed but not stemmed.
+ */
+ private Set<?> excltable = Collections.emptySet();
+
+ private Map<Object,String> stemdict = CharArrayMap.emptyMap();
+ private final Version matchVersion;
+
+ /**
+ * Builds an analyzer with the default stop words ({@link #getDefaultStopSet()})
+ * and a few default entries for the stem exclusion table.
+ *
+ */
+ public DutchAnalyzer(Version matchVersion) {
+ this(matchVersion, DefaultSetHolder.DEFAULT_STOP_SET);
+ stemdict = new CharArrayMap<String>(matchVersion, 16, false);
+ stemdict.put("fiets", "fiets"); //otherwise fiet
+ stemdict.put("bromfiets", "bromfiets"); //otherwise bromfiet
+ stemdict.put("ei", "eier");
+ stemdict.put("kind", "kinder");
+ }
+
+ public DutchAnalyzer(Version matchVersion, Set<?> stopwords){
+ this(matchVersion, stopwords, CharArraySet.EMPTY_SET);
+ }
+
+ public DutchAnalyzer(Version matchVersion, Set<?> stopwords, Set<?> stemExclusionTable){
+ stoptable = CharArraySet.unmodifiableSet(CharArraySet.copy(matchVersion, stopwords));
+ excltable = CharArraySet.unmodifiableSet(CharArraySet.copy(matchVersion, stemExclusionTable));
+ this.matchVersion = matchVersion;
+ }
+
+ /**
+ * Builds an analyzer with the given stop words.
+ *
+ * @param matchVersion
+ * @param stopwords
+ * @deprecated use {@link #DutchAnalyzer(Version, Set)} instead
+ */
+ @Deprecated
+ public DutchAnalyzer(Version matchVersion, String... stopwords) {
+ this(matchVersion, StopFilter.makeStopSet(matchVersion, stopwords));
+ }
+
+ /**
+ * Builds an analyzer with the given stop words.
+ *
+ * @param stopwords
+ * @deprecated use {@link #DutchAnalyzer(Version, Set)} instead
+ */
+ @Deprecated
+ public DutchAnalyzer(Version matchVersion, HashSet<?> stopwords) {
+ this(matchVersion, (Set<?>)stopwords);
+ }
+
+ /**
+ * Builds an analyzer with the given stop words.
+ *
+ * @param stopwords
+ * @deprecated use {@link #DutchAnalyzer(Version, Set)} instead
+ */
+ @Deprecated
+ public DutchAnalyzer(Version matchVersion, File stopwords) {
+ // this is completely broken!
+ try {
+ stoptable = WordlistLoader.getWordSet(IOUtils.getDecodingReader(stopwords,
+ IOUtils.CHARSET_UTF_8), matchVersion);
+ } catch (IOException e) {
+ // TODO: throw IOException
+ throw new RuntimeException(e);
+ }
+ this.matchVersion = matchVersion;
+ }
+
+ /**
+ * Builds an exclusionlist from an array of Strings.
+ *
+ * @param exclusionlist
+ * @deprecated use {@link #DutchAnalyzer(Version, Set, Set)} instead
+ */
+ @Deprecated
+ public void setStemExclusionTable(String... exclusionlist) {
+ excltable = StopFilter.makeStopSet(matchVersion, exclusionlist);
+ setPreviousTokenStream(null); // force a new stemmer to be created
+ }
+
+ /**
+ * Builds an exclusionlist from a Hashtable.
+ * @deprecated use {@link #DutchAnalyzer(Version, Set, Set)} instead
+ */
+ @Deprecated
+ public void setStemExclusionTable(HashSet<?> exclusionlist) {
+ excltable = exclusionlist;
+ setPreviousTokenStream(null); // force a new stemmer to be created
+ }
+
+ /**
+ * Builds an exclusionlist from the words contained in the given file.
+ * @deprecated use {@link #DutchAnalyzer(Version, Set, Set)} instead
+ */
+ @Deprecated
+ public void setStemExclusionTable(File exclusionlist) {
+ try {
+
+ excltable = WordlistLoader.getWordSet(IOUtils.getDecodingReader(exclusionlist,
+ IOUtils.CHARSET_UTF_8), matchVersion);
+ setPreviousTokenStream(null); // force a new stemmer to be created
+ } catch (IOException e) {
+ // TODO: throw IOException
+ throw new RuntimeException(e);
+ }
+ }
+
+ /**
+ * Reads a stemdictionary file , that overrules the stemming algorithm
+ * This is a textfile that contains per line
+ * <tt>word<b>\t</b>stem</tt>, i.e: two tab seperated words
+ * @deprecated This prevents reuse of TokenStreams. If you wish to use a custom
+ * stem dictionary, create your own Analyzer with {@link StemmerOverrideFilter}
+ */
+ @Deprecated
+ public void setStemDictionary(File stemdictFile) {
+ try {
+ stemdict = WordlistLoader.getStemDict(IOUtils.getDecodingReader(stemdictFile,
+ IOUtils.CHARSET_UTF_8), new CharArrayMap<String>(matchVersion, 16, false));
+ setPreviousTokenStream(null); // force a new stemmer to be created
+ } catch (IOException e) {
+ // TODO: throw IOException
+ throw new RuntimeException(e);
+ }
+ }
+
+
+ /**
+ * Returns a (possibly reused) {@link TokenStream} which tokenizes all the
+ * text in the provided {@link Reader}.
+ *
+ * @return A {@link TokenStream} built from a {@link StandardTokenizer}
+ * filtered with {@link StandardFilter}, {@link LowerCaseFilter},
+ * {@link StopFilter}, {@link KeywordMarkerFilter} if a stem exclusion set is provided,
+ * {@link StemmerOverrideFilter}, and {@link SnowballFilter}
+ */
+ @Override
+ protected TokenStreamComponents createComponents(String fieldName,
+ Reader aReader) {
+ if (matchVersion.onOrAfter(Version.LUCENE_31)) {
+ final Tokenizer source = new StandardTokenizer(matchVersion, aReader);
+ TokenStream result = new StandardFilter(matchVersion, source);
+ result = new LowerCaseFilter(matchVersion, result);
+ result = new StopFilter(matchVersion, result, stoptable);
+ if (!excltable.isEmpty())
+ result = new KeywordMarkerFilter(result, excltable);
+ if (!stemdict.isEmpty())
+ result = new StemmerOverrideFilter(matchVersion, result, stemdict);
+ result = new SnowballFilter(result, new org.tartarus.snowball.ext.DutchStemmer());
+ return new TokenStreamComponents(source, result);
+ } else {
+ final Tokenizer source = new StandardTokenizer(matchVersion, aReader);
+ TokenStream result = new StandardFilter(matchVersion, source);
+ result = new StopFilter(matchVersion, result, stoptable);
+ if (!excltable.isEmpty())
+ result = new KeywordMarkerFilter(result, excltable);
+ result = new DutchStemFilter(result, stemdict);
+ return new TokenStreamComponents(source, result);
+ }
+ }
+}
fnp / pylucene.git / blobdiff