1 /*
2  * $Header: /cvsroot/jaxen/jaxen/src/java/main/org/jaxen/expr/DefaultUnionExpr.java,v 1.5 2002/04/26 17:17:34 jstrachan Exp $
3  * $Revision: 1.5 $
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: DefaultUnionExpr.java,v 1.5 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.JaxenException;
68 
69 import java.util.List;
70 import java.util.ArrayList;
71 import java.util.Set;
72 import java.util.HashSet;
73 import java.util.Iterator;
74 
75 public class DefaultUnionExpr extends DefaultBinaryExpr implements UnionExpr
76 {
DefaultUnionExpr(Expr lhs, Expr rhs)77     public DefaultUnionExpr(Expr lhs,
78                             Expr rhs)
79     {
80         super( lhs,
81                rhs );
82     }
83 
getOperator()84     public String getOperator()
85     {
86         return "|";
87     }
88 
toString()89     public String toString()
90     {
91         return "[(DefaultUnionExpr): " + getLHS() + ", " + getRHS() + "]";
92     }
93 
evaluate(Context context)94     public Object evaluate(Context context) throws JaxenException
95     {
96         List results = new ArrayList();
97 
98         List lhsResults = convertToList( getLHS().evaluate( context ) );
99         List rhsResults = convertToList( getRHS().evaluate( context ) );
100 
101         Set unique = new HashSet();
102 
103         results.addAll( lhsResults );
104         unique.addAll( lhsResults );
105 
106         Iterator rhsIter = rhsResults.iterator();
107         Object   each    = null;
108 
109         while ( rhsIter.hasNext() )
110         {
111             each = rhsIter.next();
112 
113             if ( ! unique.contains( each ) )
114             {
115                 results.add( each );
116                 unique.add( each );
117             }
118         }
119 
120         return results;
121     }
122 }
123 
124