XorCondition.java

/* 
* IzPack - Copyright 2001-2008 Julien Ponge, All Rights Reserved. 
* 
* http://izpack.org/ 
* http://izpack.codehaus.org/ 
* 
* Copyright 2007 Dennis Reil 
* 
* Licensed under the Apache License, Version 2.0 (the "License"); 
* you may not use this file except in compliance with the License. 
* You may obtain a copy of the License at 
* 
 *     http://www.apache.org/licenses/LICENSE-2.0 
* 
 * Unless required by applicable law or agreed to in writing, software 
* distributed under the License is distributed on an "AS IS" BASIS, 
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
* See the License for the specific language governing permissions and 
 * limitations under the License. 
 */ 
package com.izforge.izpack.rules; 
  
import com.izforge.izpack.util.Debug;
import com.izforge.izpack.adaptator.IXMLElement;

/**
 * @author Dennis Reil, <Dennis.Reil@reddot.de> 
  * @version $Id: XOrCondition.java,v 1.1 2006/09/29 14:40:38 dennis Exp $ 
  */ 
public class XorCondition extends OrCondition 
 { 
    /** 
      * 
     */ 
     private static final long serialVersionUID = 3148555083095194992L; 
 /** 
    * 
   */ 
    public XorCondition() 
    { 
       super(); 
    } 
 
  /** 
   * @param operand1 
    * @param operand2 
     */ 
    public XorCondition(Condition operand1, Condition operand2) 
   { 
      super(operand1, operand2); 
   } 

    /* 
    * (non-Javadoc) 
    *  
    * @see de.reddot.installer.rules.Condition#readFromXML(net.n3.nanoxml.XMLElement) 
    */ 
  public void readFromXML(IXMLElement xmlcondition) 
    { 
    try 
      { 
        if (xmlcondition.getChildrenCount() != 2) 
          { 
             Debug.log("xor-condition needs two conditions as operands"); 
             return; 
         } 
         this.leftoperand = RulesEngine.analyzeCondition(xmlcondition.getChildAtIndex(0)); 
           this.rightoperand = RulesEngine.analyzeCondition(xmlcondition.getChildAtIndex(1)); 
       } 
      catch (Exception e) 
       { 
           Debug.log("missing element in xor-condition"); 
       } 
   } 

    public boolean isTrue() 
    { 
        boolean op1true = leftoperand.isTrue(); 
        boolean op2true = rightoperand.isTrue(); 

       if (op1true && op2true) 
       { 
           // in case where both are true 
          return false; 
        } 
       return op1true || op2true; 
    } 
 
 /* (non-Javadoc) 
     * @see com.izforge.izpack.rules.OrCondition#getDependenciesDetails() 
     */ 
   public String getDependenciesDetails() 
    { 
        StringBuffer details = new StringBuffer(); 
        details.append(this.id); 
       details.append(" depends on:<ul><li>"); 
        details.append(leftoperand.getDependenciesDetails()); 
         details.append("</li> XOR <li>"); 
       details.append(rightoperand.getDependenciesDetails()); 
        details.append("</li></ul>"); 
       return details.toString(); 
    } 
}