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Java > Open Source Codes > org > jaxen > function > IdFunction


1 /*
2  * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/IdFunction.java,v 1.10 2005/06/26 16:07:23 elharo Exp $
3  * $Revision: 1.10 $
4  * $Date: 2005/06/26 16:07:23 $
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: IdFunction.java,v 1.10 2005/06/26 16:07:23 elharo Exp $
60  */
61
62 package org.jaxen.function;
63
64 import java.util.ArrayList JavaDoc;
65 import java.util.Collections JavaDoc;
66 import java.util.Iterator JavaDoc;
67 import java.util.List JavaDoc;
68 import java.util.StringTokenizer JavaDoc;
69
70 import org.jaxen.Context;
71 import org.jaxen.Function;
72 import org.jaxen.FunctionCallException;
73 import org.jaxen.Navigator;
74
75 /**
76  * <p><b>4.1</b> <code><i>node-set</i> id(<i>object</i>)</code> </p>
77  *
78  * <p>The <b>id</b> function returns a <code>List</code>
79  * of all the elements in the context document that have an ID
80  * matching one of a specified list of IDs. How an attribute is determined
81  * to be of type ID depends on the navigator, but it normally requires that
82  * the attribute be declared to have type ID in the DTD.
83  * </p>
84  *
85  * @author Erwin Bolwidt (ejb @ klomp.org)
86  * @author Jérôme Nègre (jerome.negre @ e-xmlmedia.fr)
87  *
88  * @see <a HREF="http://www.w3.org/TR/xpath#function-id" target="_top">Section 4.1 of the XPath Specification</a>
89  */
90 public class IdFunction implements Function
91 {
92
93     /**
94      * Create a new <code>IdFunction</code> object.
95      */
96     public IdFunction() {}
97     
98     /**
99      * Returns the node with the specified ID.
100      *
101      * @param context the context at the point in the
102      * expression when the function is called
103      * @param args a list with exactly one item which is either a string
104      * a node-set
105      *
106      * @return a <code>List</code> containing the node with the specified ID; or
107      * an empty list if there is no such node
108      *
109      * @throws FunctionCallException if <code>args</code> has more or less than one item
110      */
111     public Object JavaDoc call(Context context, List JavaDoc args) throws FunctionCallException
112     {
113         if ( args.size() == 1 ) {
114             return evaluate( context.getNodeSet(),
115                              args.get(0), context.getNavigator() );
116         }
117
118         throw new FunctionCallException( "id() requires one argument" );
119     }
120
121     /**
122      * Returns the node with the specified ID.
123      * @param contextNodes the context node-set. The first item in this list
124      * determines the document in which the search is performed.
125      * @param arg the ID or IDs to search for
126      * @param nav the navigator used to calculate string-values and search
127      * by ID
128      *
129      * @return a <code>List</code> containing the node with the specified ID; or
130      * an empty list if there is no such node
131      *
132      */
133     public static List JavaDoc evaluate(List JavaDoc contextNodes, Object JavaDoc arg, Navigator nav)
134     {
135         if (contextNodes.size() == 0) return Collections.EMPTY_LIST;
136       
137         List JavaDoc nodes = new ArrayList JavaDoc();
138
139         Object JavaDoc contextNode = contextNodes.get(0);
140
141         if (arg instanceof List JavaDoc) {
142             Iterator JavaDoc iter = ((List JavaDoc)arg).iterator();
143             while (iter.hasNext()) {
144                 String JavaDoc id = StringFunction.evaluate(iter.next(), nav);
145                 nodes.addAll( evaluate( contextNodes, id, nav ) );
146             }
147         }
148         else {
149             String JavaDoc ids = StringFunction.evaluate(arg, nav);
150             StringTokenizer JavaDoc tok = new StringTokenizer JavaDoc(ids, " \t\n\r");
151             while (tok.hasMoreTokens()) {
152                 String JavaDoc id = tok.nextToken();
153                 Object JavaDoc node = nav.getElementById(contextNode, id);
154                 if (node != null) {
155                     nodes.add(node);
156                 }
157             }
158         }
159         return nodes;
160     }
161     
162 }
163
164
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