code: /* LanguageTool, a natural language style checker 
   * Copyright (C) 2016 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;
  
  import java.util.Objects;
  
  /**
   * @since 3.5
   */
  public abstract class ExampleSentence {
  
    protected final String example;
  
    public ExampleSentence(String example) {
      this.example = Objects.requireNonNull(example);
      int markerStart= example.indexOf("<marker>");
      int markerEnd = example.indexOf("</marker>");
      if (markerStart != -1 && markerEnd == -1) {
        throw new IllegalArgumentException("Example contains <marker> but lacks </marker>:" + example);
      }
      if (markerStart == -1 && markerEnd != -1) {
        throw new IllegalArgumentException("Example contains </marker> but lacks <marker>:" + example);
      }
      if (markerStart > markerEnd) {
        throw new IllegalArgumentException("Example <marker> comes before </marker>:" + example);
      }
    }
  
    public static String cleanMarkersInExample(String str) {
      return str.replace("<marker>", "").replace("</marker>", "");
    }
  
    /**
     * Return the example, typically one sentence.
     */
    public String getExample() {
      return example;
    }
  
    @Override
    public String toString() {
      return example;
    }
  
  }
  