grammarexception.java

Grammatica是一个C#和Java的语法分析程序生成器(编译器的编译器)。它可以用LL(k)语法创建可读的和带有注释的源代码。它也支持创建一个运行时语法分析器

/*
 * GrammarException.java
 *
 * This work 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 work 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
 *
 * As a special exception, the copyright holders of this library give
 * you permission to link this library with independent modules to
 * produce an executable, regardless of the license terms of these
 * independent modules, and to copy and distribute the resulting
 * executable under terms of your choice, provided that you also meet,
 * for each linked independent module, the terms and conditions of the
 * license of that module. An independent module is a module which is
 * not derived from or based on this library. If you modify this
 * library, you may extend this exception to your version of the
 * library, but you are not obligated to do so. If you do not wish to
 * do so, delete this exception statement from your version.
 *
 * Copyright (c) 2003 Per Cederberg. All rights reserved.
 */

package net.percederberg.grammatica;

/**
 * A grammar validation exception. This exception is used for 
 * signalling an error in the grammar file.
 *
 * @author   Per Cederberg, <per at percederberg dot net>
 * @version  1.0
 */
public class GrammarException extends Exception {

    /**
     * The grammar file name.
     */
    private String file;
    
    /**
     * The detailed error message.
     */
    private String message;
    
    /**
     * The first error line, or -1 for unknown. 
     */
    private int startLine;
    
    /**
     * The last error line, or -1 for unknown. 
     */
    private int endLine;

    /**
     * Creates a new grammar exception.
     * 
     * @param file           the grammar file name
     * @param message        the detailed error message
     */
    public GrammarException(String file, String message) {
        this(file, message, -1, -1);
    }
    
    /**
     * Creates a new grammar exception.
     * 
     * @param file           the grammar file name
     * @param message        the detailed error message
     * @param startLine      the starting line number, or -1 for unknown
     * @param endLine        the ending line number, or -1 for unknown
     */
    public GrammarException(String file, 
                            String message, 
                            int startLine, 
                            int endLine) {

        this.file = file;
        this.message = message;
        this.startLine = startLine;
        this.endLine = endLine;
    }
    
    /**
     * Returns the grammar file name.
     * 
     * @return the grammar file name
     */
    public String getFile() {
        return file;
    }

    /**
     * Returns the start line number for the error.
     * 
     * @return the starting line number, or 
     *         -1 if unknown
     */
    public int getStartLine() {
        return startLine;
    }
    
    /**
     * Returns the end line number for the error.
     * 
     * @return the ending line number, or 
     *         -1 if unknown
     */
    public int getEndLine() {
        return endLine;
    }
    
    /**
     * Returns the detailed error message. This message will contain 
     * the same string as getErrorMessage(), but with line number 
     * information appended.
     * 
     * @return the detailed error message
     */
    public String getMessage() {
        StringBuffer  buffer = new StringBuffer();

        // Add error description
        buffer.append(getErrorMessage());

        // Add line numbers
        if (startLine > 0 && endLine > 0) {
            if (startLine == endLine) {
                buffer.append(", on line ");
                buffer.append(startLine);
            } else {
                buffer.append(", on lines ");
                buffer.append(startLine);
                buffer.append("-");
                buffer.append(endLine);
            }
        }

        return buffer.toString();
    }
    
    /**
     * Returns the error message.
     * 
     * @return the error message.
     */
    public String getErrorMessage() {
        return message;
    }
}