turtleutil.java

这是外国一个开源推理机

/*  Sesame - Storage and Querying architecture for RDF and RDF Schema
 *  Copyright (C) 2001-2005 Aduna
 *
 *  Contact: 
 *  	Aduna
 *  	Prinses Julianaplein 14 b
 *  	3817 CS Amersfoort
 *  	The Netherlands
 *  	tel. [phone]
 *  	fax. [phone]
 *
 *  	http://aduna.biz/
 *  	http://www.openrdf.org/
 *  
 *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package org.openrdf.rio.turtle;

import org.openrdf.util.ASCIIUtil;

import org.openrdf.rio.ntriples.NTriplesUtil;

/**
 * Utility methods for Turtle encoding/decoding.
 **/
public class TurtleUtil {

/*--------------+
| Methods       |
+--------------*/

	public static boolean isWhitespace(int c) {
		// Whitespace character are space, tab, newline and carriage return:
		return c == 0x20 || c == 0x9 || c == 0xA || c == 0xD;
	}

	public static boolean isNameStartChar(int c) {
		return ASCIIUtil.isLetter(c) || c == '_';
	}

	public static boolean isNameChar(int c) {
		return isNameStartChar(c) || ASCIIUtil.isNumber(c) || c == '-';
	}

	public static boolean isLegalName(String name) {
		if (name.length() == 0) {
			return false;
		}
		if (!isNameStartChar(name.charAt(0))) {
			return false;
		}
		for (int i = 1; i < name.length(); i++) {
			if (!isNameChar( name.charAt(i) )) {
				return false;
			}
		}
		return true;
	}

	public static boolean isPrefixStartChar(int c) {
		return ASCIIUtil.isLetter(c);
	}

	public static boolean isPrefixChar(int c) {
		return isNameChar(c);
	}

	public static boolean isLegalPrefix(String prefix) {
		if (prefix.length() == 0) {
			return false;
		}
		if (!isPrefixStartChar(prefix.charAt(0))) {
			return false;
		}
		for (int i = 1; i < prefix.length(); i++) {
			if (!isPrefixChar( prefix.charAt(i) )) {
				return false;
			}
		}
		return true;
	}

	public static boolean isLanguageStartChar(int c) {
		return ASCIIUtil.isLowerCaseLetter(c);
	}

	public static boolean isLanguageChar(int c) {
		return isLanguageStartChar(c) || ASCIIUtil.isNumber(c) || c == '-';
	}

	/**
	 * Escapes any characters that have a special meaning according to the
	 * Turtle specification (<tt>"</tt> becomes <tt>\"</tt>, etc.).
	 **/
	public static String escapeString(String label) {
		int labelLength = label.length();
		StringBuffer result = new StringBuffer((int)(1.1 * labelLength));

		for (int i = 0; i < labelLength; i++) {
			char c = label.charAt(i);

			if (c == '\\') {
				result.append("\\\\");
			}
			else if (c == '"') {
				result.append("\\\"");
			}
			else if (c == '\n') {
				result.append("\\n");
			}
			else if (c == '\r') {
				result.append("\\r");
			}
			else if (c == '\t') {
				result.append("\\t");
			}
			else {
				result.append(c);
			}
		}

		return result.toString();
	}

	/**
	 * Unescapes an escaped Unicode string. This method simply uses
	 * <tt>NTriplesUtil.unescapeString(String)</tt>.
	 *
	 * @param s An escaped Turtle string.
	 * @return The unescaped string.
	 * @exception IllegalArgumentException If the supplied string is not a
	 * correctly escaped Turtle string.
	 * @see org.openrdf.rio.ntriples.NTriplesUtil#unescapeString
	 **/
	public static String unescapeString(String s) {
		return NTriplesUtil.unescapeString(s);
	}
}