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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/expr/DefaultRelationalExpr.java,v 1.11 2005/03/21 22:39:16 elharo Exp $
3    * $Revision: 1.11 $
4    * $Date: 2005/03/21 22:39:16 $
5    *
6    * ====================================================================
7    *
8    * Copyright (C) 2000-2002 bob mcwhirter & James Strachan.
9    * All rights reserved.
10   *
11   * Redistribution and use in source and binary forms, with or without
12   * modification, are permitted provided that the following conditions
13   * are met:
14   * 
15   * 1. Redistributions of source code must retain the above copyright
16   *    notice, this list of conditions, and the following disclaimer.
17   *
18   * 2. Redistributions in binary form must reproduce the above copyright
19   *    notice, this list of conditions, and the disclaimer that follows 
20   *    these conditions in the documentation and/or other materials 
21   *    provided with the distribution.
22   *
23   * 3. The name "Jaxen" must not be used to endorse or promote products
24   *    derived from this software without prior written permission.  For
25   *    written permission, please contact license@jaxen.org.
26   * 
27   * 4. Products derived from this software may not be called "Jaxen", nor
28   *    may "Jaxen" appear in their name, without prior written permission
29   *    from the Jaxen Project Management (pm@jaxen.org).
30   * 
31   * In addition, we request (but do not require) that you include in the 
32   * end-user documentation provided with the redistribution and/or in the 
33   * software itself an acknowledgement equivalent to the following:
34   *     "This product includes software developed by the
35   *      Jaxen Project (http://www.jaxen.org/)."
36   * Alternatively, the acknowledgment may be graphical using the logos 
37   * available at http://www.jaxen.org/
38   *
39   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
40   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
41   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
42   * DISCLAIMED.  IN NO EVENT SHALL THE Jaxen AUTHORS OR THE PROJECT
43   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
45   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
46   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
47   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
48   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
49   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50   * SUCH DAMAGE.
51   *
52   * ====================================================================
53   * This software consists of voluntary contributions made by many 
54   * individuals on behalf of the Jaxen Project and was originally 
55   * created by bob mcwhirter <bob@werken.com> and 
56   * James Strachan <jstrachan@apache.org>.  For more information on the 
57   * Jaxen Project, please see <http://www.jaxen.org/>.
58   * 
59   * $Id: DefaultRelationalExpr.java,v 1.11 2005/03/21 22:39:16 elharo Exp $
60   */
61  
62  
63  
64  package org.jaxen.expr;
65  
66  import java.util.Iterator;
67  import java.util.List;
68  import org.jaxen.Context;
69  import org.jaxen.JaxenException;
70  import org.jaxen.Navigator;
71  import org.jaxen.function.NumberFunction;
72  
73  abstract class DefaultRelationalExpr extends DefaultTruthExpr implements RelationalExpr 
74    {
75    public DefaultRelationalExpr( Expr lhs, Expr rhs )
76      {
77      super( lhs, rhs );
78      }
79    
80    public String toString()
81      {
82      return "[(DefaultRelationalExpr): " + getLHS() + ", " + getRHS() + "]";
83      }
84  
85    public Object evaluate( Context context ) throws JaxenException
86      {
87      Object lhsValue = getLHS().evaluate( context );
88      Object rhsValue = getRHS().evaluate( context );
89      Navigator nav = context.getNavigator();
90  
91      if( bothAreSets( lhsValue, rhsValue ) )
92        {
93        return evaluateSetSet( (List) lhsValue, (List) rhsValue, nav );
94        }
95  
96      if( eitherIsSet( lhsValue, rhsValue ) )
97        {
98        if( isSet( lhsValue ) )
99          {        
100         return evaluateSetSet( (List) lhsValue, convertToList( rhsValue ), nav );              
101         }
102       else
103         {
104         return evaluateSetSet( convertToList( lhsValue ), (List) rhsValue, nav );              
105         }
106       }
107     
108     return evaluateObjectObject( lhsValue, rhsValue, nav ) ? Boolean.TRUE : Boolean.FALSE;
109     }
110 
111   private Object evaluateSetSet( List lhsSet, List rhsSet, Navigator nav )
112     {
113     if( setIsEmpty( lhsSet ) || setIsEmpty( rhsSet ) ) // return false if either is null or empty
114       {
115       return Boolean.FALSE;
116       }    
117     
118     for( Iterator lhsIterator = lhsSet.iterator(); lhsIterator.hasNext(); )
119       {
120       Object lhs = lhsIterator.next();        
121       
122       for( Iterator rhsIterator = rhsSet.iterator(); rhsIterator.hasNext(); )
123         {
124         Object rhs = rhsIterator.next();
125         
126         if( evaluateObjectObject( lhs, rhs, nav ) )
127           {
128           return Boolean.TRUE;
129           }
130         }
131       }      
132     
133     return Boolean.FALSE;
134     }
135   
136   private boolean evaluateObjectObject( Object lhs, Object rhs, Navigator nav )
137     {
138     if( lhs == null || rhs == null )
139       {
140       return false;
141       }
142     
143     Double lhsNum = NumberFunction.evaluate( lhs, nav );
144     Double rhsNum = NumberFunction.evaluate( rhs, nav );      
145     
146     if( NumberFunction.isNaN( lhsNum ) || NumberFunction.isNaN( rhsNum ) )
147       {
148       return false;
149       }
150     
151     return evaluateDoubleDouble( lhsNum, rhsNum );
152     }
153   
154   protected abstract boolean evaluateDoubleDouble( Double lhs, Double rhs );    
155   }
156