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package benchmark.ubt.api;

/*
 * #%L
 * nohr-benchmark
 * %%
 * Copyright (C) 2014 - 2015 NOVA Laboratory of Computer Science and Informatics (NOVA LINCS)
 * %%
 * This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
 * #L%
 */

/**
 * by Yuanbo Guo
 * Semantic Web and Agent Technology Lab, CSE Department, Lehigh University, USA
 * Copyright (C) 2004
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation; either version 2 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place, Suite 330, Boston, MA 02111-1307 USA
 */

import java.io.*;

abstract public class ConfigParser {
	/** comment prefix */
	public static final String COMMENT_PREFIX = "#";
	/** beginning character of a section id */
	public static final char C_SEC_BEGIN = '[';
	/** closing character of a section id */
	public static final char C_SEC_END = ']';

	/** file reader */
	private LineNumberReader reader_;
	/** file name */
	private String fileName_;

	/**
	 * constructor
	 */
	public ConfigParser() {
	}

	/**
	 * Throws an exception when a syntax/content error is encountered in the file.
	 * 
	 * @param error
	 *            The error message.
	 * @throws java.lang.Exception
	 *             when a syntax/content error is encountered in the file.
	 */
	void error(String error) throws Exception {
		final String err = fileName_ + ": Line " + reader_.getLineNumber() + ": " + error;
		throw new Exception(err);
	}

	/**
	 * Processor of begin of file.
	 * 
	 * @throws java.lang.Exception
	 *             upon syntax/context errors.
	 */
	void handleBeginOfFile() throws Exception {
		// do nothing
	}

	/**
	 * Processor of end of file.
	 * 
	 * @throws java.lang.Exception
	 *             upon syntax/context errors.
	 */
	void handleEndOfFile() throws Exception {
		// do nothing
	}

	/**
	 * Line processor.
	 * 
	 * @param line
	 *            A line retrieved from the file.
	 * @throws java.lang.Exception
	 *             upon syntax/context errors.
	 */
	abstract void handleLine(String line) throws Exception;

	/**
	 * Check if the specified line is a section id line.
	 * 
	 * @param line
	 *            Line string.
	 * @return True if the line is a section id line, otherwise false.
	 * @throws java.lang.Exception
	 *             upon a syntax error
	 */
	boolean isStartOfSection(String line) throws Exception {
		if (line.charAt(0) != C_SEC_BEGIN)
			return false;
		else {
			if (line.charAt(line.length() - 1) != C_SEC_END) {
				error("Syntax error!");
				return false;
			}
			return true;
		}
	}

	/**
	 * Parses the specified file line by line.
	 * 
	 * @param fileName
	 *            The config file.
	 * @throws java.lang.Exception
	 *             if there are IO errors or syntax/content errors.
	 */
	void parse(String fileName) throws Exception {
		fileName_ = fileName;
		reader_ = new LineNumberReader(new FileReader(fileName));

		String line;
		handleBeginOfFile();
		while ((line = readLine()) != null)
			handleLine(line);
		handleEndOfFile();
	}

	/**
	 * Reads the next line. Empty line will be skipped.
	 * 
	 * @return The next line.
	 * @throws java.lang.Exception
	 *             if an IO error occurs.
	 */
	private String readLine() throws Exception {
		String line = null;

		while ((line = reader_.readLine()) != null) {
			line.trim();
			if (line.length() > 0)
				break;
		}

		return line;
	}
}