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


1 /*
2  * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/StartsWithFunction.java,v 1.8 2005/06/26 16:07:23 elharo Exp $
3  * $Revision: 1.8 $
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: StartsWithFunction.java,v 1.8 2005/06/26 16:07:23 elharo Exp $
60  */

61
62
63 package org.jaxen.function;
64
65 import java.util.List JavaDoc;
66
67 import org.jaxen.Context;
68 import org.jaxen.Function;
69 import org.jaxen.FunctionCallException;
70 import org.jaxen.Navigator;
71
72 /**
73  * <p><b>4.2</b> <code><i>boolean</i> starts-with(<i>string</i>,<i>string</i>)</code>
74  *
75  *
76  * <blockquote SRC="http://www.w3.org/TR/xpath">
77  * The <b>starts-with</b> function returns true if the first argument string starts
78  * with the second argument string, and otherwise returns false.
79  * </blockquote>
80  *
81  * @author bob mcwhirter (bob @ werken.com)
82  * @see <a HREF="http://www.w3.org/TR/xpath#function-starts-with" target="_top">Section 4.2 of the XPath Specification</a>
83  */

84 public class StartsWithFunction implements Function
85 {
86     
87     /**
88      * Create a new <code>StartsWithFunction</code> object.
89      */

90     public StartsWithFunction() {}
91     
92     /**
93      * Returns true if the string-value of the first item in <code>args</code>
94      * starts with the string-value of the second item in <code>args</code>.
95      * Otherwise it returns false.
96      *
97      * @param context the context at the point in the
98      * expression when the function is called
99      * @param args a list that contains two items
100      *
101      * @return <code>Boolean.TRUE</code> if the first item in <code>args</code>
102      * starts with the string-value of the second item in <code>args</code>;
103      * otherwise <code>Boolean.FALSE</code>
104      *
105      * @throws FunctionCallException if <code>args</code> does not have length two
106      */

107     public Object JavaDoc call(Context context,
108                        List JavaDoc args) throws FunctionCallException
109     {
110         if (args.size() == 2)
111         {
112             return evaluate( args.get(0),
113                              args.get(1),
114                              context.getNavigator() );
115         }
116
117         throw new FunctionCallException( "starts-with() requires two arguments." );
118     }
119
120     /**
121      * Returns true if the string-value of <code>strArg</code>
122      * starts with the string-value of <code>matchArg</code>.
123      * Otherwise it returns false.
124      *
125      * @param strArg the object whose string-value searched for the prefix
126      * @param matchArg the object whose string-value becomes the prefix string to compare against
127      * @param nav the navigator used to calculate the string-values of the arguments
128      *
129      * @return <code>Boolean.TRUE</code> if the string-value of <code>strArg</code>
130      * starts with the string-value of <code>matchArg</code>;
131      * otherwise <code>Boolean.FALSE</code>
132      *
133      */

134     public static Boolean JavaDoc evaluate(Object JavaDoc strArg,
135                                    Object JavaDoc matchArg,
136                                    Navigator nav)
137     {
138         String JavaDoc str = StringFunction.evaluate( strArg,
139                                                 nav );
140
141         String JavaDoc match = StringFunction.evaluate( matchArg,
142                                                 nav );
143
144         return ( str.startsWith(match)
145                  ? Boolean.TRUE
146                  : Boolean.FALSE
147                  );
148     }
149      
150 }
151
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