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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/expr/DefaultEqualityExpr.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: DefaultEqualityExpr.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.BooleanFunction;
72  import org.jaxen.function.NumberFunction;
73  import org.jaxen.function.StringFunction;
74  
75  abstract class DefaultEqualityExpr extends DefaultTruthExpr implements EqualityExpr 
76    {
77    public DefaultEqualityExpr( Expr lhs, Expr rhs )
78      {
79      super( lhs, rhs );
80      }
81  
82    public String toString()
83      {
84      return "[(DefaultEqualityExpr): " + getLHS() + ", " + getRHS() + "]";
85      }
86    
87    public Object evaluate( Context context ) throws JaxenException
88      {
89      Object lhsValue = getLHS().evaluate( context );
90      Object rhsValue = getRHS().evaluate( context );
91      
92      if( lhsValue == null || rhsValue == null )
93        {
94        return Boolean.FALSE;
95        }
96      
97      Navigator nav = context.getNavigator();
98  
99      if( bothAreSets( lhsValue, rhsValue ) )
100       {
101       return evaluateSetSet( (List) lhsValue, (List) rhsValue, nav );
102       }
103     else if ( eitherIsSet( lhsValue, rhsValue ) )
104       {
105       if ( isSet( lhsValue ) )
106         {
107         return evaluateSetSet( (List) lhsValue, convertToList( rhsValue ), nav );                
108         }
109       else
110         {
111         return evaluateSetSet( convertToList( lhsValue ), (List) rhsValue, nav );                                
112         }
113       }  
114     else
115       {
116       return evaluateObjectObject( lhsValue, rhsValue, nav ) ? Boolean.TRUE : Boolean.FALSE;
117       }    
118     }
119   
120   private Boolean evaluateSetSet( List lhsSet, List rhsSet, Navigator nav )
121     {
122     if( setIsEmpty( lhsSet ) || setIsEmpty( rhsSet ) )
123       {
124       return Boolean.FALSE;
125       }
126     
127     for( Iterator lhsIterator = lhsSet.iterator(); lhsIterator.hasNext(); )
128       {
129       Object lhs = lhsIterator.next();
130       
131       for( Iterator rhsIterator = rhsSet.iterator(); rhsIterator.hasNext(); )
132         {
133         Object rhs = rhsIterator.next();
134         
135         if( evaluateObjectObject( lhs, rhs, nav ) )
136           {
137           return Boolean.TRUE;
138           }
139         }
140       }
141     
142     return Boolean.FALSE;
143     }
144   
145   private boolean evaluateObjectObject( Object lhs, Object rhs, Navigator nav )
146     {
147     if( eitherIsBoolean( lhs, rhs ) )
148       {            
149       return evaluateObjectObject( BooleanFunction.evaluate( lhs, nav ),
150                                    BooleanFunction.evaluate( rhs, nav ) );
151       }
152     else if( eitherIsNumber( lhs, rhs ) )
153       {
154       return evaluateObjectObject( NumberFunction.evaluate( lhs,
155                                                             nav ),
156                                    NumberFunction.evaluate( rhs,
157                                                             nav ) );                                              
158       }
159     else
160       {
161       return evaluateObjectObject( StringFunction.evaluate( lhs,
162                                                             nav ),
163                                    StringFunction.evaluate( rhs,
164                                                             nav ) );
165       }
166     }
167   
168   protected abstract boolean evaluateObjectObject( Object lhs, Object rhs );
169   }