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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/expr/DefaultTruthExpr.java,v 1.10 2006/02/05 21:47:40 elharo Exp $
3    * $Revision: 1.10 $
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: DefaultTruthExpr.java,v 1.10 2006/02/05 21:47:40 elharo Exp $
46   */
47  
48  
49  
50  package org.jaxen.expr;
51  
52  import java.util.List;
53  
54  abstract class DefaultTruthExpr extends DefaultBinaryExpr 
55  {
56      DefaultTruthExpr(Expr lhs,
57                              Expr rhs)
58      {
59          super( lhs,
60                 rhs );
61      }
62  
63      public String toString()
64      {
65          return "[(DefaultTruthExpr): " + getLHS() + ", " + getRHS() + "]";
66      }
67  
68      protected boolean bothAreSets(Object lhs,
69                                    Object rhs)
70      {
71          return ( lhs instanceof List
72                   &&
73                   rhs instanceof List );
74      }
75  
76      protected boolean eitherIsSet(Object lhs,
77                                    Object rhs)
78      {
79          return ( lhs instanceof List
80                   ||
81                   rhs instanceof List );
82      }
83  
84      protected boolean isSet(Object obj)
85      {
86          return ( obj instanceof List );
87      }
88      
89      protected boolean setIsEmpty( List set )
90        {
91        return (set == null || set.size() == 0);
92        }
93  
94      protected boolean eitherIsBoolean(Object lhs,
95                                        Object rhs)
96      {
97          return ( lhs instanceof Boolean
98                   ||
99                   rhs instanceof Boolean );
100     }
101 
102     protected boolean bothAreBoolean(Object lhs,
103                                      Object rhs)
104     {
105         return ( lhs instanceof Boolean
106                  &&
107                  rhs instanceof Boolean );
108     }
109 
110     protected boolean eitherIsNumber(Object lhs,
111                                      Object rhs)
112     {
113         return ( lhs instanceof Number
114                  ||
115                  rhs instanceof Number );
116     } 
117 
118 }
119