Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
StringLengthFunction |
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1 | /* | |
2 | * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/StringLengthFunction.java,v 1.12 2006/02/05 21:47:41 elharo Exp $ | |
3 | * $Revision: 1.12 $ | |
4 | * $Date: 2006/02/05 21:47:41 $ | |
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: StringLengthFunction.java,v 1.12 2006/02/05 21:47:41 elharo Exp $ | |
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>number</i> string-length(<i>string</i>)</code></p> | |
60 | * | |
61 | * <p> | |
62 | * The <b>string-length</b> function returns the number of <strong>Unicode characters</strong> | |
63 | * in its argument. This is <strong>not</strong> necessarily | |
64 | * the same as the number <strong>Java chars</strong> | |
65 | * in the corresponding Java string. In particular, if the Java <code>String</code> | |
66 | * contains surrogate pairs each such pair will be counted as only one character | |
67 | * by this function. If the argument is omitted, | |
68 | * it returns the length of the string-value of the context node. | |
69 | * </p> | |
70 | * | |
71 | * @author bob mcwhirter (bob @ werken.com) | |
72 | * @see <a href="http://www.w3.org/TR/xpath#function-string-length" target="_top">Section | |
73 | * 4.2 of the XPath Specification</a> | |
74 | */ | |
75 | public class StringLengthFunction implements Function | |
76 | { | |
77 | ||
78 | ||
79 | /** | |
80 | * Create a new <code>StringLengthFunction</code> object. | |
81 | */ | |
82 | 106 | public StringLengthFunction() {} |
83 | ||
84 | ||
85 | /** | |
86 | * <p> | |
87 | * Returns the number of Unicode characters in the string-value of the argument. | |
88 | * </p> | |
89 | * | |
90 | * @param context the context at the point in the | |
91 | * expression when the function is called | |
92 | * @param args a list containing the item whose string-value is to be counted. | |
93 | * If empty, the length of the context node's string-value is returned. | |
94 | * | |
95 | * @return a <code>Double</code> giving the number of Unicode characters | |
96 | * | |
97 | * @throws FunctionCallException if args has more than one item | |
98 | */ | |
99 | public Object call(Context context, | |
100 | List args) throws FunctionCallException | |
101 | { | |
102 | 14 | if (args.size() == 0) |
103 | { | |
104 | 2 | return evaluate( context.getNodeSet(), |
105 | context.getNavigator() ); | |
106 | } | |
107 | 12 | else if (args.size() == 1) |
108 | { | |
109 | 10 | return evaluate( args.get(0), |
110 | context.getNavigator() ); | |
111 | } | |
112 | ||
113 | 2 | throw new FunctionCallException( "string-length() requires one argument." ); |
114 | } | |
115 | ||
116 | /** | |
117 | * <p> | |
118 | * Returns the number of Unicode characters in the string-value of | |
119 | * an object. | |
120 | * </p> | |
121 | * | |
122 | * @param obj the object whose string-value is counted | |
123 | * @param nav used to calculate the string-values of the first two arguments | |
124 | * | |
125 | * @return a <code>Double</code> giving the number of Unicode characters | |
126 | * | |
127 | * @throws FunctionCallException if the string contains mismatched surrogates | |
128 | */ | |
129 | public static Double evaluate(Object obj, Navigator nav) throws FunctionCallException | |
130 | { | |
131 | 112 | String str = StringFunction.evaluate( obj, nav ); |
132 | // String.length() counts UTF-16 code points; not Unicode characters | |
133 | 112 | char[] data = str.toCharArray(); |
134 | 112 | int length = 0; |
135 | 606 | for (int i = 0; i < data.length; i++) { |
136 | 496 | char c = data[i]; |
137 | 496 | length++; |
138 | // if this is a high surrogate; assume the next character is | |
139 | // is a low surrogate and skip it | |
140 | 496 | if (c >= 0xD800) { |
141 | try { | |
142 | 10 | char low = data[i+1]; |
143 | 10 | if (low < 0xDC00 || low > 0xDFFF) { |
144 | 2 | throw new FunctionCallException("Bad surrogate pair in string " + str); |
145 | } | |
146 | 8 | i++; // increment past low surrogate |
147 | } | |
148 | 0 | catch (ArrayIndexOutOfBoundsException ex) { |
149 | 0 | throw new FunctionCallException("Bad surrogate pair in string " + str); |
150 | 8 | } |
151 | } | |
152 | } | |
153 | 110 | return new Double(length); |
154 | } | |
155 | ||
156 | } |