/*

  * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/expr/DefaultUnionExpr.java,v 1.17 2006/11/30 18:49:27 elharo Exp $

  * $Revision: 1.17 $

  * $Date: 2006/11/30 18:49:27 $

  *

  * ====================================================================

  *

  * Copyright 2000-2002 bob mcwhirter & James Strachan.

  * All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions are

  * met:

  * 

  *   * Redistributions of source code must retain the above copyright

  *     notice, this list of conditions and the following disclaimer.

  * 

  *   * Redistributions in binary form must reproduce the above copyright

  *     notice, this list of conditions and the following disclaimer in the

  *     documentation and/or other materials provided with the distribution.

  * 

  *   * Neither the name of the Jaxen Project nor the names of its

  *     contributors may be used to endorse or promote products derived 

  *     from this software without specific prior written permission.

  * 

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

  * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED

  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A

  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER

  * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

  *

  * ====================================================================

  * This software consists of voluntary contributions made by many 

  * individuals on behalf of the Jaxen Project and was originally 

  * created by bob mcwhirter <bob@werken.com> and 

  * James Strachan <jstrachan@apache.org>.  For more information on the 

  * Jaxen Project, please see <http://www.jaxen.org/>.

  * 

  * $Id: DefaultUnionExpr.java,v 1.17 2006/11/30 18:49:27 elharo Exp $

  */

 package org.jaxen.expr;

 import java.util.ArrayList;

 import java.util.Collections;

 import java.util.HashSet;

 import java.util.Iterator;

 import java.util.List;

 import java.util.Set;

 import org.jaxen.Context;

 import org.jaxen.JaxenException;

 import org.jaxen.XPathSyntaxException;

 /**

  * @deprecated this class will become non-public in the future;

  *     use the interface instead

  */

 public class DefaultUnionExpr extends DefaultBinaryExpr implements UnionExpr

 {

     /**

      * 

      */

     private static final long serialVersionUID = 7629142718276852707L;

     public DefaultUnionExpr(Expr lhs,

                             Expr rhs)

     {

         super( lhs,

                rhs );

     }

     public String getOperator()

     {

         return "|";

     }

     public String toString()

     {

         return "[(DefaultUnionExpr): " + getLHS() + ", " + getRHS() + "]";

     }

     public Object evaluate(Context context) throws JaxenException

     {

         List results = new ArrayList();

         try {

             List lhsResults = (List) getLHS().evaluate( context );

             List rhsResults = (List) getRHS().evaluate( context );

             Set unique = new HashSet();

             results.addAll( lhsResults );

             unique.addAll( lhsResults );

             Iterator rhsIter = rhsResults.iterator();

             while ( rhsIter.hasNext() )

             {

                 Object each = rhsIter.next();

                 if ( ! unique.contains( each ) )

                 {

                     results.add( each );

                     unique.add( each );

                 }

             }

             Collections.sort(results, new NodeComparator(context.getNavigator()));

             return results;

         }

         catch (ClassCastException e) {

             throw new XPathSyntaxException(this.getText(), context.getPosition(), "Unions are only allowed over node-sets");

         }

     }

 }