lucene/analysis/common/src/test/org/apache/lucene/analysis/snowball/TestSnowball.java

/*
 * 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.snowball;

import java.io.IOException;
import java.io.InputStream;
import java.io.UncheckedIOException;
import java.nio.charset.StandardCharsets;
import java.util.List;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.BaseTokenStreamTestCase;
import org.apache.lucene.analysis.MockTokenizer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.WordlistLoader;
import org.apache.lucene.analysis.core.KeywordTokenizer;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.FlagsAttribute;
import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.analysis.tokenattributes.PayloadAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
import org.apache.lucene.analysis.tokenattributes.TypeAttribute;
import org.apache.lucene.util.BytesRef;

public class TestSnowball extends BaseTokenStreamTestCase {

  public void testEnglish() throws Exception {
    Analyzer a =
        new Analyzer() {
          @Override
          protected TokenStreamComponents createComponents(String fieldName) {
            Tokenizer tokenizer = new MockTokenizer();
            return new TokenStreamComponents(tokenizer, new SnowballFilter(tokenizer, "English"));
          }
        };

    assertAnalyzesTo(a, "he abhorred accents", new String[] {"he", "abhor", "accent"});
    a.close();
  }

  public void testFilterTokens() throws Exception {
    SnowballFilter filter = new SnowballFilter(new TestTokenStream(), "English");
    CharTermAttribute termAtt = filter.getAttribute(CharTermAttribute.class);
    OffsetAttribute offsetAtt = filter.getAttribute(OffsetAttribute.class);
    TypeAttribute typeAtt = filter.getAttribute(TypeAttribute.class);
    PayloadAttribute payloadAtt = filter.getAttribute(PayloadAttribute.class);
    PositionIncrementAttribute posIncAtt = filter.getAttribute(PositionIncrementAttribute.class);
    FlagsAttribute flagsAtt = filter.getAttribute(FlagsAttribute.class);

    filter.incrementToken();

    assertEquals("accent", termAtt.toString());
    assertEquals(2, offsetAtt.startOffset());
    assertEquals(7, offsetAtt.endOffset());
    assertEquals("wrd", typeAtt.type());
    assertEquals(3, posIncAtt.getPositionIncrement());
    assertEquals(77, flagsAtt.getFlags());
    assertEquals(new BytesRef(new byte[] {0, 1, 2, 3}), payloadAtt.getPayload());
  }

  private static final class TestTokenStream extends TokenStream {
    private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
    private final OffsetAttribute offsetAtt = addAttribute(OffsetAttribute.class);
    private final TypeAttribute typeAtt = addAttribute(TypeAttribute.class);
    private final PayloadAttribute payloadAtt = addAttribute(PayloadAttribute.class);
    private final PositionIncrementAttribute posIncAtt =
        addAttribute(PositionIncrementAttribute.class);
    private final FlagsAttribute flagsAtt = addAttribute(FlagsAttribute.class);

    TestTokenStream() {
      super();
    }

    @Override
    public boolean incrementToken() {
      clearAttributes();
      termAtt.setEmpty().append("accents");
      offsetAtt.setOffset(2, 7);
      typeAtt.setType("wrd");
      posIncAtt.setPositionIncrement(3);
      payloadAtt.setPayload(new BytesRef(new byte[] {0, 1, 2, 3}));
      flagsAtt.setFlags(77);
      return true;
    }
  }

  /** for testing purposes ONLY */
  public static final List<String> SNOWBALL_LANGS;

  static {
    try (InputStream in = TestSnowball.class.getResourceAsStream("languages.txt")) {
      SNOWBALL_LANGS = WordlistLoader.getLines(in, StandardCharsets.UTF_8);
    } catch (IOException e) {
      throw new UncheckedIOException(e);
    }
  }

  public void testEmptyTerm() throws IOException {
    for (final String lang : SNOWBALL_LANGS) {
      Analyzer a =
          new Analyzer() {
            @Override
            protected TokenStreamComponents createComponents(String fieldName) {
              Tokenizer tokenizer = new KeywordTokenizer();
              return new TokenStreamComponents(tokenizer, new SnowballFilter(tokenizer, lang));
            }
          };
      checkOneTerm(a, "", "");
      a.close();
    }
  }

  public void testRandomStrings() throws IOException {
    for (String lang : SNOWBALL_LANGS) {
      checkRandomStrings(lang);
    }
  }

  public void checkRandomStrings(final String snowballLanguage) throws IOException {
    Analyzer a =
        new Analyzer() {
          @Override
          protected TokenStreamComponents createComponents(String fieldName) {
            Tokenizer t = new MockTokenizer();
            return new TokenStreamComponents(t, new SnowballFilter(t, snowballLanguage));
          }
        };
    checkRandomData(random(), a, 20 * RANDOM_MULTIPLIER);
    a.close();
  }
}