code: package it.unibz.inf.ontop.protege.utils;
  
  /*
   * #%L
   * ontop-protege
   * %%
   * Copyright (C) 2009 - 2013 KRDB Research Centre. Free University of Bozen Bolzano.
   * %%
   * Licensed 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.
   * #L%
   */
  
  import java.awt.Color;
  import java.awt.Font;
  import java.util.stream.Collectors;
  import java.util.stream.IntStream;
  
  import javax.swing.text.*;
  
  public class SQLQueryStyledDocument extends DefaultStyledDocument {
  
  	private static final Font SQL_FONT = new Font("Courier", Font.PLAIN, 14);
  	private static final Color SQL_COLOR = new Color(38,128,2);
  
  	private final SimpleAttributeSet plainStyle = new SimpleAttributeSet();
  	private final SimpleAttributeSet boldStyle = new SimpleAttributeSet();
  
  	public SQLQueryStyledDocument() {
  		StyleConstants.setFontSize(plainStyle, SQL_FONT.getSize());
  		StyleConstants.setFontFamily(plainStyle, SQL_FONT.getFamily());
  
  		StyleConstants.setBold(boldStyle, true);
  		StyleConstants.setForeground(boldStyle, SQL_COLOR);
  	}
  
  	@Override
  	public void insertString(int offset, String str, AttributeSet a) throws BadLocationException {
  		super.insertString(offset, str, a);
  		highlightKeywords();
  	}
  
  	@Override
  	public void remove(int offs, int len) throws BadLocationException {
  		super.remove(offs, len);
  		highlightKeywords();
  	}
  
  	private void highlightKeywords() throws BadLocationException {
  		setCharacterAttributes(0, getLength(), plainStyle, true);
  		highlight("SELECT");
  		highlight("FROM");
  		highlight("WHERE");
  		highlight("ON");
  		highlight("JOIN");
  		highlight("AND");
  		highlight("AS");
  	}
  
  	private void highlight(String keyword) throws BadLocationException {
  		int length = keyword.length();
  		String pattern = IntStream.range(0, length)
  				.mapToObj(keyword::charAt)
  				.map(c -> "[" + Character.toUpperCase(c) + Character.toLowerCase(c) + "]")
  				.collect(Collectors.joining("", "(", ")"));
  		String input = getText(0, getLength()).replaceAll(pattern, keyword.toUpperCase());
  		int total = input.length();
  		int index, offset = 0;
  		while ((index = input.indexOf(keyword, offset)) != -1) {
  			offset = index + length;
  			if ((index == 0 || Character.isWhitespace(input.charAt(index - 1))) &&
  					(offset >= total || Character.isWhitespace(input.charAt(offset))))
  				setCharacterAttributes(index, length, boldStyle, false);
  		}
  	}
  }
  