--- /dev/null
+package org.apache.lucene.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.
+ */
+
+import java.io.File;
+import java.io.IOException;
+import java.io.Reader;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+import org.apache.lucene.analysis.Analyzer;
+import org.apache.lucene.analysis.CharArraySet;
+import org.apache.lucene.analysis.LowerCaseFilter;
+import org.apache.lucene.analysis.KeywordMarkerFilter;
+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.StandardAnalyzer;
+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.German2Stemmer;
+
+/**
+ * {@link Analyzer} for German language.
+ * <p>
+ * 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.
+ * </p>
+ *
+ * <a name="version"/>
+ * <p>You must specify the required {@link Version}
+ * compatibility when creating GermanAnalyzer:
+ * <ul>
+ * <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>
+ *
+ * <p><b>NOTE</b>: This class uses the same {@link Version}
+ * dependent settings as {@link StandardAnalyzer}.</p>
+ */
+public final class GermanAnalyzer extends StopwordAnalyzerBase {
+
+ /**
+ * List of typical german stopwords.
+ * @deprecated use {@link #getDefaultStopSet()} instead
+ */
+ @Deprecated
+ public final static String[] GERMAN_STOP_WORDS = {
+ "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"
+ };
+
+ /** File containing default German stopwords. */
+ public final static String DEFAULT_STOPWORD_FILE = "german_stop.txt";
+
+ /**
+ * Returns a set of default German-stopwords
+ * @return a set of default German-stopwords
+ */
+ public static final Set<?> getDefaultStopSet(){
+ return DefaultSetHolder.DEFAULT_SET;
+ }
+
+ private static class DefaultSetHolder {
+ /** @deprecated remove in Lucene 5.0 */
+ @Deprecated
+ private static final Set<?> DEFAULT_SET_30 = CharArraySet.unmodifiableSet(new CharArraySet(
+ Version.LUCENE_CURRENT, Arrays.asList(GERMAN_STOP_WORDS), false));
+ private static final Set<?> DEFAULT_SET;
+ static {
+ try {
+ DEFAULT_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 {@link StopFilter}.
+ */
+
+ /**
+ * Contains words that should be indexed but not stemmed.
+ */
+ // TODO make this final in 3.1
+ private Set<?> exclusionSet;
+
+ /**
+ * Builds an analyzer with the default stop words:
+ * {@link #getDefaultStopSet()}.
+ */
+ public GermanAnalyzer(Version matchVersion) {
+ this(matchVersion,
+ matchVersion.onOrAfter(Version.LUCENE_31) ? DefaultSetHolder.DEFAULT_SET
+ : DefaultSetHolder.DEFAULT_SET_30);
+ }
+
+ /**
+ * Builds an analyzer with the given stop words
+ *
+ * @param matchVersion
+ * lucene compatibility version
+ * @param stopwords
+ * a stopword set
+ */
+ public GermanAnalyzer(Version matchVersion, Set<?> stopwords) {
+ this(matchVersion, stopwords, CharArraySet.EMPTY_SET);
+ }
+
+ /**
+ * Builds an analyzer with the given stop words
+ *
+ * @param matchVersion
+ * lucene compatibility version
+ * @param stopwords
+ * a stopword set
+ * @param stemExclusionSet
+ * a stemming exclusion set
+ */
+ public GermanAnalyzer(Version matchVersion, Set<?> stopwords, Set<?> stemExclusionSet) {
+ super(matchVersion, stopwords);
+ exclusionSet = CharArraySet.unmodifiableSet(CharArraySet.copy(matchVersion, stemExclusionSet));
+ }
+
+ /**
+ * Builds an analyzer with the given stop words.
+ * @deprecated use {@link #GermanAnalyzer(Version, Set)}
+ */
+ @Deprecated
+ public GermanAnalyzer(Version matchVersion, String... stopwords) {
+ this(matchVersion, StopFilter.makeStopSet(matchVersion, stopwords));
+ }
+
+ /**
+ * Builds an analyzer with the given stop words.
+ * @deprecated use {@link #GermanAnalyzer(Version, Set)}
+ */
+ @Deprecated
+ public GermanAnalyzer(Version matchVersion, Map<?,?> stopwords) {
+ this(matchVersion, stopwords.keySet());
+
+ }
+
+ /**
+ * Builds an analyzer with the given stop words.
+ * @deprecated use {@link #GermanAnalyzer(Version, Set)}
+ */
+ @Deprecated
+ public GermanAnalyzer(Version matchVersion, File stopwords) throws IOException {
+ this(matchVersion, WordlistLoader.getWordSet(
+ IOUtils.getDecodingReader(stopwords, IOUtils.CHARSET_UTF_8), matchVersion));
+ }
+
+ /**
+ * Builds an exclusionlist from an array of Strings.
+ * @deprecated use {@link #GermanAnalyzer(Version, Set, Set)} instead
+ */
+ @Deprecated
+ public void setStemExclusionTable(String[] exclusionlist) {
+ exclusionSet = StopFilter.makeStopSet(matchVersion, exclusionlist);
+ setPreviousTokenStream(null); // force a new stemmer to be created
+ }
+
+ /**
+ * Builds an exclusionlist from a {@link Map}
+ * @deprecated use {@link #GermanAnalyzer(Version, Set, Set)} instead
+ */
+ @Deprecated
+ public void setStemExclusionTable(Map<?,?> exclusionlist) {
+ exclusionSet = new HashSet<Object>(exclusionlist.keySet());
+ setPreviousTokenStream(null); // force a new stemmer to be created
+ }
+
+ /**
+ * Builds an exclusionlist from the words contained in the given file.
+ * @deprecated use {@link #GermanAnalyzer(Version, Set, Set)} instead
+ */
+ @Deprecated
+ public void setStemExclusionTable(File exclusionlist) throws IOException {
+ exclusionSet = WordlistLoader.getWordSet(IOUtils.getDecodingReader(exclusionlist,
+ IOUtils.CHARSET_UTF_8), matchVersion);
+ setPreviousTokenStream(null); // force a new stemmer to be created
+ }
+
+ /**
+ * Creates
+ * {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
+ * used to tokenize all the text in the provided {@link Reader}.
+ *
+ * @return {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
+ * built from a {@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);
+ result = new KeywordMarkerFilter(result, exclusionSet);
+ if (matchVersion.onOrAfter(Version.LUCENE_31))
+ result = new SnowballFilter(result, new German2Stemmer());
+ else
+ result = new GermanStemFilter(result);
+ return new TokenStreamComponents(source, result);
+ }
+}
fnp / pylucene.git / blobdiff