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Lucene example source code file (PositionFilterTest.java)

This example Lucene source code file (PositionFilterTest.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

exception, io, override, positionfilter, positionfilter, shinglefilter, six_gram_no_positions_tokens, string, string, test_token, test_token, test_token_non_zero_position_increments, test_token_position_increments, testtokenstream, testtokenstream

The Lucene PositionFilterTest.java source code

package org.apache.lucene.analysis.position;

/**
 * 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 org.apache.lucene.analysis.BaseTokenStreamTestCase;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.shingle.ShingleFilter;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;

public class PositionFilterTest extends BaseTokenStreamTestCase {

  public class TestTokenStream extends TokenStream {

    protected int index = 0;
    protected String[] testToken;
    protected final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);

    public TestTokenStream(String[] testToken) {
      super();
      this.testToken = testToken;
    }

    @Override
    public final boolean incrementToken() throws IOException {
      clearAttributes();
      if (index < testToken.length) {
        termAtt.setEmpty().append(testToken[index++]);
        return true;
      } else {
        return false;
      }
    }
    @Override
    public void reset() {
      index = 0;
    }
  }

  public static final String[] TEST_TOKEN = new String[]{
    "please",
    "divide",
    "this",
    "sentence",
    "into",
    "shingles",
  };
  public static final int[] TEST_TOKEN_POSITION_INCREMENTS = new int[]{
    1, 0, 0, 0, 0, 0
  };
  public static final int[] TEST_TOKEN_NON_ZERO_POSITION_INCREMENTS = new int[]{
    1, 5, 5, 5, 5, 5
  };

  public static final String[] SIX_GRAM_NO_POSITIONS_TOKENS = new String[]{
    "please",
    "please divide",
    "please divide this",
    "please divide this sentence",
    "please divide this sentence into",
    "please divide this sentence into shingles",
    "divide",
    "divide this",
    "divide this sentence",
    "divide this sentence into",
    "divide this sentence into shingles",
    "this",
    "this sentence",
    "this sentence into",
    "this sentence into shingles",
    "sentence",
    "sentence into",
    "sentence into shingles",
    "into",
    "into shingles",
    "shingles",
  };
  public static final int[] SIX_GRAM_NO_POSITIONS_INCREMENTS = new int[]{
    1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
  };
  public static final String[] SIX_GRAM_NO_POSITIONS_TYPES = new String[]{
    "word", "shingle", "shingle", "shingle", "shingle", "shingle",
    "word", "shingle", "shingle", "shingle", "shingle",
    "word", "shingle", "shingle", "shingle",
    "word", "shingle", "shingle",
    "word", "shingle",
    "word"
  };

  public void testFilter() throws Exception {

    assertTokenStreamContents(new PositionFilter(new TestTokenStream(TEST_TOKEN)),
               TEST_TOKEN,
               TEST_TOKEN_POSITION_INCREMENTS);
  }

  public void testNonZeroPositionIncrement() throws Exception {
    
    assertTokenStreamContents(new PositionFilter(new TestTokenStream(TEST_TOKEN), 5),
               TEST_TOKEN,
               TEST_TOKEN_NON_ZERO_POSITION_INCREMENTS);
  }
  
  public void testReset() throws Exception {

    PositionFilter filter = new PositionFilter(new TestTokenStream(TEST_TOKEN));
    assertTokenStreamContents(filter, TEST_TOKEN, TEST_TOKEN_POSITION_INCREMENTS);
    filter.reset();
    // Make sure that the reset filter provides correct position increments
    assertTokenStreamContents(filter, TEST_TOKEN, TEST_TOKEN_POSITION_INCREMENTS);
  }
  
  /** Tests ShingleFilter up to six shingles against six terms.
   *  Tests PositionFilter setting all but the first positionIncrement to zero.
   * @throws java.io.IOException @see Token#next(Token)
   */
  public void test6GramFilterNoPositions() throws Exception {

    ShingleFilter filter = new ShingleFilter(new TestTokenStream(TEST_TOKEN), 6);
    assertTokenStreamContents(new PositionFilter(filter),
               SIX_GRAM_NO_POSITIONS_TOKENS,
               SIX_GRAM_NO_POSITIONS_INCREMENTS);
  }

}

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