View Javadoc

1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/expr/DefaultEqualityExpr.java,v 1.14 2006/02/05 21:47:40 elharo Exp $
3    * $Revision: 1.14 $
4    * $Date: 2006/02/05 21:47:40 $
5    *
6    * ====================================================================
7    *
8    * Copyright 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 are
13   * met:
14   * 
15   *   * Redistributions of source code must retain the above copyright
16   *     notice, this list of conditions and the following disclaimer.
17   * 
18   *   * Redistributions in binary form must reproduce the above copyright
19   *     notice, this list of conditions and the following disclaimer in the
20   *     documentation and/or other materials provided with the distribution.
21   * 
22   *   * Neither the name of the Jaxen Project nor the names of its
23   *     contributors may be used to endorse or promote products derived 
24   *     from this software without specific prior written permission.
25   * 
26   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
27   * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
29   * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
30   * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
31   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
32   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
33   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
34   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
35   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
36   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37   *
38   * ====================================================================
39   * This software consists of voluntary contributions made by many 
40   * individuals on behalf of the Jaxen Project and was originally 
41   * created by bob mcwhirter <bob@werken.com> and 
42   * James Strachan <jstrachan@apache.org>.  For more information on the 
43   * Jaxen Project, please see <http://www.jaxen.org/>.
44   * 
45   * $Id: DefaultEqualityExpr.java,v 1.14 2006/02/05 21:47:40 elharo Exp $
46   */
47  
48  
49  
50  package org.jaxen.expr;
51  
52  import java.util.Iterator;
53  import java.util.List;
54  import org.jaxen.Context;
55  import org.jaxen.JaxenException;
56  import org.jaxen.Navigator;
57  import org.jaxen.function.BooleanFunction;
58  import org.jaxen.function.NumberFunction;
59  import org.jaxen.function.StringFunction;
60  
61  abstract class DefaultEqualityExpr extends DefaultTruthExpr implements EqualityExpr 
62    {
63    DefaultEqualityExpr( Expr lhs, Expr rhs )
64      {
65      super( lhs, rhs );
66      }
67  
68    public String toString()
69      {
70      return "[(DefaultEqualityExpr): " + getLHS() + ", " + getRHS() + "]";
71      }
72    
73    public Object evaluate( Context context ) throws JaxenException
74      {
75      Object lhsValue = getLHS().evaluate( context );
76      Object rhsValue = getRHS().evaluate( context );
77      
78      if( lhsValue == null || rhsValue == null )
79        {
80        return Boolean.FALSE;
81        }
82      
83      Navigator nav = context.getNavigator();
84  
85      if( bothAreSets( lhsValue, rhsValue ) )
86        {
87        return evaluateSetSet( (List) lhsValue, (List) rhsValue, nav );
88        }
89      else if ( eitherIsSet( lhsValue, rhsValue ) )
90        {
91        if ( isSet( lhsValue ) )
92          {
93          return evaluateSetSet( (List) lhsValue, convertToList( rhsValue ), nav );                
94          }
95        else
96          {
97          return evaluateSetSet( convertToList( lhsValue ), (List) rhsValue, nav );                                
98          }
99        }  
100     else
101       {
102       return evaluateObjectObject( lhsValue, rhsValue, nav ) ? Boolean.TRUE : Boolean.FALSE;
103       }    
104     }
105   
106   private Boolean evaluateSetSet( List lhsSet, List rhsSet, Navigator nav )
107     {
108     if( setIsEmpty( lhsSet ) || setIsEmpty( rhsSet ) )
109       {
110       return Boolean.FALSE;
111       }
112     
113     for( Iterator lhsIterator = lhsSet.iterator(); lhsIterator.hasNext(); )
114       {
115       Object lhs = lhsIterator.next();
116       
117       for( Iterator rhsIterator = rhsSet.iterator(); rhsIterator.hasNext(); )
118         {
119         Object rhs = rhsIterator.next();
120         
121         if( evaluateObjectObject( lhs, rhs, nav ) )
122           {
123           return Boolean.TRUE;
124           }
125         }
126       }
127     
128     return Boolean.FALSE;
129     }
130   
131   private boolean evaluateObjectObject( Object lhs, Object rhs, Navigator nav )
132     {
133     if( eitherIsBoolean( lhs, rhs ) )
134       {            
135       return evaluateObjectObject( BooleanFunction.evaluate( lhs, nav ),
136                                    BooleanFunction.evaluate( rhs, nav ) );
137       }
138     else if( eitherIsNumber( lhs, rhs ) )
139       {
140       return evaluateObjectObject( NumberFunction.evaluate( lhs,
141                                                             nav ),
142                                    NumberFunction.evaluate( rhs,
143                                                             nav ) );                                              
144       }
145     else
146       {
147       return evaluateObjectObject( StringFunction.evaluate( lhs,
148                                                             nav ),
149                                    StringFunction.evaluate( rhs,
150                                                             nav ) );
151       }
152     }
153   
154   protected abstract boolean evaluateObjectObject( Object lhs, Object rhs );
155   }