parserstack.java

iiitAccessServer是一个用Java编写的基于规则的企业鉴别系统。它作为一个服务器工作

/*******************************************************************************
 * Copyright (C) 2002, 2003
 * ingenieurbuero fuer innovative informationstechnik (iiit)
 * Dipl.-Ing. Joerg Beckmann, Dortmund, Germany
 *
 * 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.
 *
 * version $Id: ParserStack.java,v 1.5 2003/04/13 21:09:56 joerg Exp $
 ******************************************************************************/

package de.iiit.access.server.plugins.parser;

import de.iiit.access.common.api.*;

import de.iiit.access.server.api.*;

import java.util.*;

/** This stack is used to pass the expressions and its subexpression between the
 * parser and the resolver. Each time the result of the current expression is also an
 * expression it is pushed onto the stack and the parser is called recursively.
 * When the result of the current expression is a set the expression is pulled from
 * the stack. Everytime a new element is pushed onto it, the stack reviews its
 * content. When the same expression is already there it throws a ParserException
 * to show that it recognized circular references inside the expression.
 * @version $Revision: 1.5 $ $Date: 2003/04/13 21:09:56 $
 */
public class ParserStack extends Stack
implements ParserStackIf
{
    /** CVS Version Tag */
    private static final String vcid = "$Id: ParserStack.java,v 1.5 2003/04/13 21:09:56 joerg Exp $";
    
    /** Creates a new instance of ParserStack */
    public ParserStack()
    {
    }
    
    /** Pushes a new item onto the stack. This method search the stack for the new item.
     * If it is already there a ParserExeption is thrown to show that a circular references
     * inside the expression was recognized.
     * @param item The new item
     * @throws ParserException if the new item is already on the stack
     * @return the new item.
     */    
    public Object pushArgument(Object item) throws ParserException
    {
        if (search(item) != -1)
            throw new ParserException("Circular references found");

        return push(item);
    }
}

/**
 * $Log: ParserStack.java,v $
 * Revision 1.5  2003/04/13 21:09:56  joerg
 * Package structure modified
 *
 * Revision 1.4  2003/04/13 20:28:01  joerg
 * Package structure modified
 *
 * Revision 1.3  2003/04/13 20:16:42  joerg
 * Package structure modified
 *
 * Revision 1.2  2003/01/01 21:04:18  joerg
 * Copyright-Statement aktualisiert
 *
 * Revision 1.1  2002/12/19 15:24:23  joerg
 * Reparatur des CVS-Repositories
 *
 * Revision 1.3  2002/12/09 19:29:17  joerg
 * Versionsdaten in allen JavaDoc-Klassenbeschreibungen ergaenzt
 *
 * Revision 1.2  2002/12/09 16:32:26  joerg
 * JavaDoc Kommentare ergaenzt
 *
 * Revision 1.1  2002/11/27 16:40:39  joerg
 * Spezialisierter Parameter-Stack fuer den Parser
 *
 */