1 /*
2  * $Header: /cvsroot/jaxen/jaxen/src/java/main/org/jaxen/expr/DefaultTruthExpr.java,v 1.4 2002/04/26 17:17:34 jstrachan Exp $
3  * $Revision: 1.4 $
4  * $Date: 2002/04/26 17:17:34 $
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: DefaultTruthExpr.java,v 1.4 2002/04/26 17:17:34 jstrachan Exp $
60  */
61 
62 
63 
64 package org.jaxen.expr;
65 
66 import org.jaxen.Context;
67 import org.jaxen.util.SingleObjectIterator;
68 
69 import java.util.List;
70 import java.util.Iterator;
71 import java.util.Collections;
72 
73 abstract class DefaultTruthExpr extends DefaultBinaryExpr
74 {
DefaultTruthExpr(Expr lhs, Expr rhs)75     public DefaultTruthExpr(Expr lhs,
76                             Expr rhs)
77     {
78         super( lhs,
79                rhs );
80     }
81 
toString()82     public String toString()
83     {
84         return "[(DefaultTruthExpr): " + getLHS() + ", " + getRHS() + "]";
85     }
86 
bothAreSets(Object lhs, Object rhs)87     protected boolean bothAreSets(Object lhs,
88                                   Object rhs)
89     {
90         return ( lhs instanceof List
91                  &&
92                  rhs instanceof List );
93     }
94 
eitherIsSet(Object lhs, Object rhs)95     protected boolean eitherIsSet(Object lhs,
96                                   Object rhs)
97     {
98         return ( lhs instanceof List
99                  ||
100                  rhs instanceof List );
101     }
102 
isSet(Object obj)103     protected boolean isSet(Object obj)
104     {
105         return ( obj instanceof List );
106     }
107 
setIsEmpty( List set )108     protected boolean setIsEmpty( List set )
109       {
110       return (set == null || set.size() == 0);
111       }
112 
eitherIsBoolean(Object lhs, Object rhs)113     protected boolean eitherIsBoolean(Object lhs,
114                                       Object rhs)
115     {
116         return ( lhs instanceof Boolean
117                  ||
118                  rhs instanceof Boolean );
119     }
120 
bothAreBoolean(Object lhs, Object rhs)121     protected boolean bothAreBoolean(Object lhs,
122                                      Object rhs)
123     {
124         return ( lhs instanceof Boolean
125                  &&
126                  rhs instanceof Boolean );
127     }
128 
eitherIsNumber(Object lhs, Object rhs)129     protected boolean eitherIsNumber(Object lhs,
130                                      Object rhs)
131     {
132         return ( lhs instanceof Number
133                  ||
134                  rhs instanceof Number );
135     }
136 
isNumber(Object obj)137     protected boolean isNumber(Object obj)
138     {
139         return ( obj instanceof Number );
140     }
141 
isString(Object obj)142     protected boolean isString(Object obj)
143     {
144         return ( obj instanceof String );
145     }
146 
isBoolean(Object obj)147     protected boolean isBoolean(Object obj)
148     {
149         return ( obj instanceof Boolean );
150     }
151 }
152 
153