1 /*
2 * $Header$
3 * $Revision$
4 * $Date$
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 * $Id$
46 */
47
48
49 package org.jaxen.function;
50
51 import java.util.List;
52
53 import org.jaxen.Context;
54 import org.jaxen.Function;
55 import org.jaxen.FunctionCallException;
56 import org.jaxen.Navigator;
57
58 /**
59 * <p><b>4.2</b> <code><i>boolean</i> starts-with(<i>string</i>,<i>string</i>)</code></p>
60 *
61 *
62 * <blockquote cite="http://www.w3.org/TR/xpath">
63 * The <b>starts-with</b> function returns true if the first argument string starts
64 * with the second argument string, and otherwise returns false.
65 * </blockquote>
66 *
67 * @author bob mcwhirter (bob @ werken.com)
68 * @see <a href="https://www.w3.org/TR/xpath#function-starts-with" target="_top">Section 4.2 of the XPath Specification</a>
69 */
70 public class StartsWithFunction implements Function
71 {
72
73 /**
74 * Create a new <code>StartsWithFunction</code> object.
75 */
76 public StartsWithFunction() {}
77
78 /**
79 * Returns true if the string-value of the first item in <code>args</code>
80 * starts with the string-value of the second item in <code>args</code>.
81 * Otherwise it returns false.
82 *
83 * @param context the context at the point in the
84 * expression when the function is called
85 * @param args a list that contains two items
86 *
87 * @return <code>Boolean.TRUE</code> if the first item in <code>args</code>
88 * starts with the string-value of the second item in <code>args</code>;
89 * otherwise <code>Boolean.FALSE</code>
90 *
91 * @throws FunctionCallException if <code>args</code> does not have length two
92 */
93 public Object call(Context context,
94 List args) throws FunctionCallException
95 {
96 if (args.size() == 2)
97 {
98 return evaluate( args.get(0),
99 args.get(1),
100 context.getNavigator() );
101 }
102
103 throw new FunctionCallException( "starts-with() requires two arguments." );
104 }
105
106 /**
107 * Returns true if the string-value of <code>strArg</code>
108 * starts with the string-value of <code>matchArg</code>.
109 * Otherwise it returns false.
110 *
111 * @param strArg the object whose string-value searched for the prefix
112 * @param matchArg the object whose string-value becomes the prefix string to compare against
113 * @param nav the navigator used to calculate the string-values of the arguments
114 *
115 * @return <code>Boolean.TRUE</code> if the string-value of <code>strArg</code>
116 * starts with the string-value of <code>matchArg</code>;
117 * otherwise <code>Boolean.FALSE</code>
118 *
119 */
120 public static Boolean evaluate(Object strArg,
121 Object matchArg,
122 Navigator nav)
123 {
124 String str = StringFunction.evaluate( strArg,
125 nav );
126
127 String match = StringFunction.evaluate( matchArg,
128 nav );
129
130 return ( str.startsWith(match)
131 ? Boolean.TRUE
132 : Boolean.FALSE
133 );
134 }
135
136 }