LUCENE-7287: add UkrainianMorfologikAnalyzer, a dictionary-based analyzer for the Ukrainian language

lucene/CHANGES.txt

@@ -27,6 +27,10 @@ New Features
   recording key/values from a provided iterable based on when the
   commit actually takes place (Mike McCandless)
 
+* LUCENE-7287: UkrainianMorfologikAnalyzer is a new dictionary-based
+  analyzer for the Ukrainian language (Andriy Rysin via Mike
+  McCandless)
+
 Bug Fixes
 
 * LUCENE-6662: Fixed potential resource leaks. (Rishabh Patel via Adrien Grand)

lucene/analysis/morfologik/src/java/org/apache/lucene/analysis/uk/UkrainianMorfologikAnalyzer.java

@@ -0,0 +1,154 @@
+/*
+ * 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.
+ */
+package org.apache.lucene.analysis.uk;
+
+
+import java.io.IOException;
+import java.io.Reader;
+import java.nio.charset.StandardCharsets;
+
+import org.apache.lucene.analysis.Analyzer;
+import org.apache.lucene.analysis.CharArraySet;
+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.charfilter.MappingCharFilter;
+import org.apache.lucene.analysis.charfilter.NormalizeCharMap;
+import org.apache.lucene.analysis.miscellaneous.SetKeywordMarkerFilter;
+import org.apache.lucene.analysis.morfologik.MorfologikFilter;
+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 morfologik.stemming.Dictionary;
+
+/**
+ * A dictionary-based {@link Analyzer} for Ukrainian.
+ */
+public final class UkrainianMorfologikAnalyzer extends StopwordAnalyzerBase {
+  private final CharArraySet stemExclusionSet;
+  
+  /** File containing default Ukrainian stopwords. */
+  public final static String DEFAULT_STOPWORD_FILE = "/org/apache/lucene/analysis/uk/stopwords.txt";
+  
+  /**
+   * Returns an unmodifiable instance of the default stop words set.
+   * @return default stop words set.
+   */
+  public static CharArraySet 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 CharArraySet DEFAULT_STOP_SET;
+
+    static {
+      try {
+        DEFAULT_STOP_SET = WordlistLoader.getSnowballWordSet(IOUtils.getDecodingReader(SnowballFilter.class, 
+            DEFAULT_STOPWORD_FILE, StandardCharsets.UTF_8));
+      } 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 UkrainianMorfologikAnalyzer() {
+    this(DefaultSetHolder.DEFAULT_STOP_SET);
+  }
+  
+  /**
+   * Builds an analyzer with the given stop words.
+   * 
+   * @param stopwords a stopword set
+   */
+  public UkrainianMorfologikAnalyzer(CharArraySet stopwords) {
+    this(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 SetKeywordMarkerFilter} before
+   * stemming.
+   * 
+   * @param stopwords a stopword set
+   * @param stemExclusionSet a set of terms not to be stemmed
+   */
+  public UkrainianMorfologikAnalyzer(CharArraySet stopwords, CharArraySet stemExclusionSet) {
+    super(stopwords);
+    this.stemExclusionSet = CharArraySet.unmodifiableSet(CharArraySet.copy(stemExclusionSet));
+  }
+
+  @Override
+  protected Reader initReader(String fieldName, Reader reader) {
+    NormalizeCharMap.Builder builder = new NormalizeCharMap.Builder();
+    builder.add("\u2019", "'");
+    builder.add("\u02BC", "'");
+    builder.add("\u0301", "");
+    NormalizeCharMap normMap = builder.build();
+
+    reader = new MappingCharFilter(normMap, reader);
+    return reader;
+  }
+
+  /**
+   * Creates a
+   * {@link org.apache.lucene.analysis.Analyzer.TokenStreamComponents}
+   * which tokenizes all the text in the provided {@link Reader}.
+   * 
+   * @return A
+   *         {@link org.apache.lucene.analysis.Analyzer.TokenStreamComponents}
+   *         built from an {@link StandardTokenizer} filtered with
+   *         {@link StandardFilter}, {@link LowerCaseFilter}, {@link StopFilter}
+   *         , {@link SetKeywordMarkerFilter} if a stem exclusion set is
+   *         provided and {@link MorfologikFilter} on the Ukrainian dictionary.
+   */
+  @Override
+  protected TokenStreamComponents createComponents(String fieldName) {
+    Tokenizer source = new StandardTokenizer();
+    TokenStream result = new StandardFilter(source);
+    result = new LowerCaseFilter(result);
+    result = new StopFilter(result, stopwords);
+
+    if (stemExclusionSet.isEmpty() == false) {
+      result = new SetKeywordMarkerFilter(result, stemExclusionSet);
+    }
+
+    result = new MorfologikFilter(result, getDictionary());
+    return new TokenStreamComponents(source, result);
+  }
+
+  private static Dictionary getDictionary() {
+    try {
+      return Dictionary.read(UkrainianMorfologikAnalyzer.class.getResource("/org/apache/lucene/analysis/uk/ukrainian.dict"));
+    } catch (IOException e) {
+      throw new RuntimeException(e);
+    }
+  }
+}

lucene/analysis/morfologik/src/java/org/apache/lucene/analysis/uk/package-info.java

@@ -0,0 +1,21 @@
+/*
+ * 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.
+ */
+
+/**
+ * Analyzer for Ukrainian.
+ */
+package org.apache.lucene.analysis.uk;

lucene/analysis/morfologik/src/resources/org/apache/lucene/analysis/uk/ukrainian.info

@@ -0,0 +1,10 @@
+#
+# Dictionary properties.
+#
+
+fsa.dict.separator=+
+fsa.dict.encoding=cp1251
+
+fsa.dict.encoder=SUFFIX
+
+fsa.dict.speller.ignore-diacritics=false

lucene/analysis/morfologik/src/test/org/apache/lucene/analysis/uk/TestUkrainianAnalyzer.java

@@ -0,0 +1,65 @@
+/*
+ * 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.
+ */
+package org.apache.lucene.analysis.uk;
+
+
+import java.io.IOException;
+
+import org.apache.lucene.analysis.Analyzer;
+import org.apache.lucene.analysis.BaseTokenStreamTestCase;
+
+/**
+ * Test case for UkrainianAnalyzer.
+ */
+
+public class TestUkrainianAnalyzer extends BaseTokenStreamTestCase {
+
+  /** Check that UkrainianAnalyzer doesn't discard any numbers */
+  public void testDigitsInUkrainianCharset() throws IOException {
+    UkrainianMorfologikAnalyzer ra = new UkrainianMorfologikAnalyzer();
+    assertAnalyzesTo(ra, "text 1000", new String[] { "text", "1000" });
+    ra.close();
+  }
+
+  public void testReusableTokenStream() throws Exception {
+    Analyzer a = new UkrainianMorfologikAnalyzer();
+    assertAnalyzesTo(a, "Ця п'єса у свою чергу рухається по колу.",
+                     new String[] { "п'єса", "черга", "рухатися", "кола", "коло", "коло", "кіл", "кіл" });
+    a.close();
+  }
+
+  public void testSpecialCharsTokenStream() throws Exception {
+    Analyzer a = new UkrainianMorfologikAnalyzer();
+    assertAnalyzesTo(a, "Ця пʼєса, у сво́ю чергу, рухається по колу.",
+                     new String[] { "п'єса", "черга", "рухатися", "кола", "коло", "коло", "кіл", "кіл" });
+    a.close();
+  }
+
+  public void testCapsTokenStream() throws Exception {
+    Analyzer a = new UkrainianMorfologikAnalyzer();
+    assertAnalyzesTo(a, "Цей Чайковський.",
+                     new String[] { "чайковський" });
+    a.close();
+  }
+
+  /** blast some random strings through the analyzer */
+  public void testRandomStrings() throws Exception {
+    Analyzer analyzer = new UkrainianMorfologikAnalyzer();
+    checkRandomData(random(), analyzer, 1000*RANDOM_MULTIPLIER);
+    analyzer.close();
+  }
+}