code: /* LanguageTool, a natural language style checker 
   * Copyright (C) 2014 Daniel Naber (http://www.danielnaber.de)
   * 
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
   * USA
   */
  package org.languagetool.rules.en;
  
  import org.languagetool.tokenizers.WordTokenizer;
  
  import java.util.*;
  
  /**
   * Tokenize sentences to tokens like Google does for its ngram index. Note: there
   * doesn't seem to be official documentation about the way Google tokenizes there,
   * so this is just an approximation.
   * @since 3.2
   */
  public class GoogleStyleWordTokenizer extends WordTokenizer {
  
    @Override
    public String getTokenizingCharacters() {
      return super.getTokenizingCharacters() + "-";
    }
    
    @Override
    public List<String> tokenize(String text) {
      List<String> tokens = super.tokenize(text);
      String prev = null;
      Stack<String> l = new Stack<>();
      for (String token : tokens) {
        if ("'".equals(prev)) {
          // TODO: add more cases if needed:
          if (token.equals("m")) {
            l.pop();
            l.push("'m");
          } else if (token.equals("re")) {
            l.pop();
            l.push("'re");
          } else if (token.equals("ve")) {
            l.pop();
            l.push("'ve");
          } else if (token.equals("ll")) {
            l.pop();
            l.push("'ll");
          } else {
            l.push(token);
          }
        } else {
          l.push(token);
        }
        prev = token;
      }
      return l;
    }
  
  }
  