xmladapter4prerequisites.java

来自「Mandarax是一个规则引擎的纯Java实现。它支持多类型的事实和基于反映的规」· Java 代码 · 共 131 行

package org.mandarax.xkb.framework;

/**
 *  Copyright (C) 1999-2004  Jens Dietrich (mailto:[e-mail])
 *
 *  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 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
 */

import java.util.Map;

import org.jdom.Element;
import org.mandarax.kernel.Fact;
import org.mandarax.kernel.LogicFactory;
import org.mandarax.kernel.Predicate;
import org.mandarax.kernel.Prerequisite;
import org.mandarax.kernel.Term;
import org.mandarax.lib.Cut;
import org.mandarax.xkb.XKBException;
/**
 * An adapter class for prerequisites.
 * @see org.mandarax.kernel.Prerequisite
 * @author <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</A>
 * @version 3.4 <7 March 05>
 * @since 2.0 
 * @deprecated from v 3.4 - support for new features such as validation will not be added to XKB, please use ZKB instead
 */

public class XMLAdapter4Prerequisites extends AbstractXMLAdapter {
      public static final String TERMS = "terms";
      public static final String PREREQUISITE = "prereq";
      public static final String OPERATOR = "_opr";
      public static final String NEGATED_AF = "neg_af";

/**
 * Export an object, i.e., convert it to an element in the DOM.
 * @param obj an object
 * @param driver the generic driver
 * @param cache a cache used in order to associate the same
 * id with various occurences of the same object
 * @exception an XKBException is thrown if export fails
 */
public Element exportObject(Object obj,GenericDriver driver,Map cache) throws  XKBException {
	  Prerequisite prereq = null;
      // extra support for versions prior 2.0: old version have used Fact in rule bodies,
      // we support this but warn -  if obj is a Fact, convert it to a prerequisite
      if (obj instanceof Fact) {
      	if (obj instanceof Prerequisite) {
      		prereq = (Prerequisite)obj;
      	}
      	else {
      		LOG_XKB.warn("Exporting fact from rule body - rule bodies should contain instances of Prerequisite " + obj);
      		Fact fact = (Fact)obj;
      		prereq = lfactory.createPrerequisite(fact.getPredicate(),fact.getTerms(),false);
      	}      	
      }
      else check(obj,Prerequisite.class);
      Element e = new Element(PREREQUISITE);
      e.setAttribute(NEGATED_AF,String.valueOf(prereq.isNegatedAF()));
      // add predicate
      Predicate p = prereq.getPredicate();
      Element eo = new Element(OPERATOR);
      e.addContent(eo);
      Element ep = exportObject(p,getPredicateType(p),driver,cache);
      eo.addContent(ep);
      // add terms
      Term[] terms = prereq.getTerms();
      Element eTerms = new Element(TERMS);
      e.addContent(eTerms);
      for (int i=0;i<terms.length;i++) {
            Element et = exportObject(terms[i],getTermType(terms[i]),driver,cache);
            eTerms.addContent(et);
      }
      addProperties(e,prereq);
      return e;
}
/**
 * Build an object from an XML element.
 * @param e an element
 * @param driver the generic driver
 * @param cache a cache used to identify objects that have the same id
 * @param lfactory the logic factory used to create objects
 * @exception an XKBException is thrown if import fails
 */
public Object importObject(Element e,GenericDriver driver,Map cache,LogicFactory lfactory) throws XKBException {
       // the first element is predicate
       Element eOperator = e.getChild(OPERATOR);
       Element ePredicate = (Element)eOperator.getChildren().get(0);
       XMLAdapter adapter = driver.getAdapterByTagName(ePredicate.getName());
       Predicate predicate = (Predicate)adapter.importObject(ePredicate,driver,cache,lfactory);
       // special handling for cut
       if (predicate instanceof Cut) return lfactory.createCut();
       
       // get the terms
       Element eTerm = (Element)e.getChild(TERMS);
       Term[] terms = (Term[])importChildren(eTerm,null,driver,cache,lfactory,Term.class);
       // negation
       boolean neg = "true".equals(e.getAttributeValue(NEGATED_AF));
       // assemble prerequisite
       Prerequisite prereq=lfactory.createPrerequisite(predicate,terms,neg);
       loadProperties(e,prereq);
       return prereq;
}
/**
 * Get the name of the associated tag (element).
 * @return a string
 */
public String getTagName() {
      return PREREQUISITE;
}
/**
 * Get the kind of object the adapter can export/import.
 * @return a string
 */
public String getKindOfObject() {
      return GenericDriver.PREREQUISITE;
}

}