/*
 * 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.tr;


import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;

import java.io.IOException;

Strips all characters after an apostrophe (including the apostrophe itself).

In Turkish, apostrophe is used to separate suffixes from proper names
(continent, sea, river, lake, mountain, upland, proper names related to
religion and mythology). This filter intended to be used before stem filters.
For more information, see 
Role of Apostrophes in Turkish Information Retrieval

/**
 * Strips all characters after an apostrophe (including the apostrophe itself).
 * <p>
 * In Turkish, apostrophe is used to separate suffixes from proper names
 * (continent, sea, river, lake, mountain, upland, proper names related to
 * religion and mythology). This filter intended to be used before stem filters.
 * For more information, see <a href="http://www.ipcsit.com/vol57/015-ICNI2012-M021.pdf">
 * Role of Apostrophes in Turkish Information Retrieval</a>
 * </p>
 */
public final class ApostropheFilter extends TokenFilter {

  private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);

  public ApostropheFilter(TokenStream in) {
    super(in);
  }

  @Override
  public final boolean incrementToken() throws IOException {
    if (!input.incrementToken())
      return false;

    final char[] buffer = termAtt.buffer();
    final int length = termAtt.length();

    for (int i = 0; i < length; i++)
      if (buffer[i] == '\'' || buffer[i] == '\u2019') {
        termAtt.setLength(i);
        return true;
      }
    return true;
  }
}