org.graphstream.util.parser.Token Maven / Gradle / Ivy

/*
 * This file is part of GraphStream .
 * 
 * GraphStream is a library whose purpose is to handle static or dynamic
 * graph, create them from scratch, file or any source and display them.
 * 
 * This program is free software distributed under the terms of two licenses, the
 * CeCILL-C license that fits European law, and the GNU Lesser General Public
 * License. You can  use, modify and/ or redistribute the software under the terms
 * of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
 * URL  or under the terms of the GNU LGPL 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 Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see .
 * 
 * The fact that you are presently reading this means that you have had
 * knowledge of the CeCILL-C and LGPL licenses and that you accept their terms.
 */

/**
 * @since 2009-03-09
 * 
 * @author Guilhelm Savin 
 * @author Hicham Brahimi 
 */
package org.graphstream.util.parser;

/**
 * Describes the input token stream.
 */

public class Token implements java.io.Serializable {

	/**
	 * The version identifier for this Serializable class. Increment only if the
	 * serialized form of the class changes.
	 */
	private static final long serialVersionUID = 1L;

	/**
	 * An integer that describes the kind of this token. This numbering system is
	 * determined by JavaCCParser, and a table of these numbers is stored in the
	 * file ...Constants.java.
	 */
	public int kind;

	/** The line number of the first character of this Token. */
	public int beginLine;
	/** The column number of the first character of this Token. */
	public int beginColumn;
	/** The line number of the last character of this Token. */
	public int endLine;
	/** The column number of the last character of this Token. */
	public int endColumn;

	/**
	 * The string image of the token.
	 */
	public String image;

	/**
	 * A reference to the next regular (non-special) token from the input stream. If
	 * this is the last token from the input stream, or if the token manager has not
	 * read tokens beyond this one, this field is set to null. This is true only if
	 * this token is also a regular token. Otherwise, see below for a description of
	 * the contents of this field.
	 */
	public Token next;

	/**
	 * This field is used to access special tokens that occur prior to this token,
	 * but after the immediately preceding regular (non-special) token. If there are
	 * no such special tokens, this field is set to null. When there are more than
	 * one such special token, this field refers to the last of these special
	 * tokens, which in turn refers to the next previous special token through its
	 * specialToken field, and so on until the first special token (whose
	 * specialToken field is null). The next fields of special tokens refer to other
	 * special tokens that immediately follow it (without an intervening regular
	 * token). If there is no such token, this field is null.
	 */
	public Token specialToken;

	/**
	 * An optional attribute value of the Token. Tokens which are not used as
	 * syntactic sugar will often contain meaningful values that will be used later
	 * on by the compiler or interpreter. This attribute value is often different
	 * from the image. Any subclass of Token that actually wants to return a
	 * non-null value can override this method as appropriate.
	 */
	public Object getValue() {
		return null;
	}

	/**
	 * No-argument constructor
	 */
	public Token() {
	}

	/**
	 * Constructs a new token for the specified Image.
	 */
	public Token(int kind) {
		this(kind, null);
	}

	/**
	 * Constructs a new token for the specified Image and Kind.
	 */
	public Token(int kind, String image) {
		this.kind = kind;
		this.image = image;
	}

	/**
	 * Returns the image.
	 */
	public String toString() {
		return image;
	}

	/**
	 * Returns a new Token object, by default. However, if you want, you can create
	 * and return subclass objects based on the value of ofKind. Simply add the
	 * cases to the switch for all those special cases. For example, if you have a
	 * subclass of Token called IDToken that you want to create if ofKind is ID,
	 * simply add something like :
	 * 
	 * case MyParserConstants.ID : return new IDToken(ofKind, image);
	 * 
	 * to the following switch statement. Then you can cast matchedToken variable to
	 * the appropriate type and use sit in your lexical actions.
	 */
	public static Token newToken(int ofKind, String image) {
		switch (ofKind) {
		default:
			return new Token(ofKind, image);
		}
	}

	public static Token newToken(int ofKind) {
		return newToken(ofKind, null);
	}

}