/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2014 by RapidMiner and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapidminer.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.gui.tools.syntax;
/*
 * TeXTokenMarker.java - TeX/LaTeX/AMS-TeX token marker
 * Copyright (C) 1998 Slava Pestov
 *
 * You may use and modify this package for any purpose. Redistribution is
 * permitted, in both source and binary form, provided that this notice
 * remains intact in all source distributions of this package.
 */

import javax.swing.text.Segment;

/**
 * TeX token marker.
 * 
 * @author Slava Pestov, Ingo Mierswa
 */
public class TeXTokenMarker extends TokenMarker {
	// public members
	public static final byte BDFORMULA = Token.INTERNAL_FIRST;

	public static final byte EDFORMULA = (byte) (Token.INTERNAL_FIRST + 1);

	@Override
	public byte markTokensImpl(byte token, Segment line, int lineIndex) {
		char[] array = line.array;
		int offset = line.offset;
		int lastOffset = offset;
		int length = line.count + offset;
		boolean backslash = false;
		loop: for (int i = offset; i < length; i++) {
			int i1 = (i + 1);

			char c = array[i];
			// if a backslash is followed immediately
			// by a non-alpha character, the command at
			// the non-alpha char. If we have a backslash,
			// some text, and then a non-alpha char,
			// the command ends before the non-alpha char.
			if (Character.isLetter(c)) {
				backslash = false;
			} else {
				if (backslash) {
					// \<non alpha>
					// we skip over this character,
					// hence the `continue'
					backslash = false;
					if (token == Token.KEYWORD2 || token == EDFORMULA)
						token = Token.KEYWORD2;
					addToken(i1 - lastOffset, token);
					lastOffset = i1;
					if (token == Token.KEYWORD1)
						token = Token.NULL;
					continue;
				} else {
					// \blah<non alpha>
					// we leave the character in
					// the stream, and it's not
					// part of the command token
					if (token == BDFORMULA || token == EDFORMULA)
						token = Token.KEYWORD2;
					addToken(i - lastOffset, token);
					if (token == Token.KEYWORD1)
						token = Token.NULL;
					lastOffset = i;
				}
			}
			switch (c) {
			case '%':
				if (backslash) {
					backslash = false;
					break;
				}
				addToken(i - lastOffset, token);
				addToken(length - i, Token.COMMENT1);
				lastOffset = length;
				break loop;
			case '\\':
				backslash = true;
				if (token == Token.NULL) {
					token = Token.KEYWORD1;
					addToken(i - lastOffset, Token.NULL);
					lastOffset = i;
				}
				break;
			case '$':
				backslash = false;
				if (token == Token.NULL) // singe $
				{
					token = Token.KEYWORD2;
					addToken(i - lastOffset, Token.NULL);
					lastOffset = i;
				} else if (token == Token.KEYWORD1) // \...$
				{
					token = Token.KEYWORD2;
					addToken(i - lastOffset, Token.KEYWORD1);
					lastOffset = i;
				} else if (token == Token.KEYWORD2) // $$aaa
				{
					if (i - lastOffset == 1 && array[i - 1] == '$') {
						token = BDFORMULA;
						break;
					}
					token = Token.NULL;
					addToken(i1 - lastOffset, Token.KEYWORD2);
					lastOffset = i1;
				} else if (token == BDFORMULA) // $$aaa$
				{
					token = EDFORMULA;
				} else if (token == EDFORMULA) // $$aaa$$
				{
					token = Token.NULL;
					addToken(i1 - lastOffset, Token.KEYWORD2);
					lastOffset = i1;
				}
				break;
			}
		}
		if (lastOffset != length)
			addToken(length - lastOffset, token == BDFORMULA || token == EDFORMULA ? Token.KEYWORD2 : token);
		return (token != Token.KEYWORD1 ? token : Token.NULL);
	}
}