Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||||||
SubstringFunction |
|
| 9.333333333333334;9.333 |
1 | /* |
|
2 | * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/SubstringFunction.java,v 1.15 2005/06/28 13:44:45 elharo Exp $ |
|
3 | * $Revision: 1.15 $ |
|
4 | * $Date: 2005/06/28 13:44:45 $ |
|
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 | */ |
|
60 | package org.jaxen.function; |
|
61 | ||
62 | import java.util.List; |
|
63 | ||
64 | import org.jaxen.Context; |
|
65 | import org.jaxen.Function; |
|
66 | import org.jaxen.FunctionCallException; |
|
67 | import org.jaxen.Navigator; |
|
68 | /** |
|
69 | * <p> |
|
70 | * <b>4.2</b> |
|
71 | * <code><i>string</i> substring(<i>string</i>,<i>number</i>,<i>number?</i>)</code> |
|
72 | * </p> |
|
73 | * |
|
74 | * <blockquote src="http://www.w3.org/TR/xpath"> |
|
75 | * <p>The <b>substring</b> function returns the |
|
76 | * substring of the first argument starting at the position specified in |
|
77 | * the second argument with length specified in the third argument. For |
|
78 | * example, |
|
79 | * |
|
80 | * <code>substring("12345",2,3)</code> returns <code>"234"</code>. |
|
81 | * If the third argument is not specified, it returns the substring |
|
82 | * starting at the position specified in the second argument and |
|
83 | * continuing to the end of the string. For example, |
|
84 | * <code>substring("12345",2)</code> returns <code>"2345"</code>. |
|
85 | * </p> |
|
86 | * |
|
87 | * <p> |
|
88 | * More precisely, each character in the string (see <a |
|
89 | * href="http://www.w3.org/TR/xpath#strings">[<b>3.6 Strings</b>]</a>) is considered to have a |
|
90 | * numeric position: the position of the first character is 1, the |
|
91 | * position of the second character is 2 and so on. |
|
92 | * </p> |
|
93 | * |
|
94 | * <blockquote> <b>NOTE: </b>This differs from Java and ECMAScript, in |
|
95 | * which the <code>String.substring</code> method treats the position |
|
96 | * of the first character as 0.</blockquote> |
|
97 | * |
|
98 | * <p> |
|
99 | * The returned substring contains those characters for which the |
|
100 | * position of the character is greater than or equal to the rounded |
|
101 | * value of the second argument and, if the third argument is specified, |
|
102 | * less than the sum of the rounded value of the second argument and the |
|
103 | * rounded value of the third argument; the comparisons and addition |
|
104 | * used for the above follow the standard IEEE 754 rules; rounding is |
|
105 | * done as if by a call to the <b><a href="#function-round">round</a></b> |
|
106 | * function. The following examples illustrate various unusual cases: |
|
107 | * </p> |
|
108 | * |
|
109 | * <ul> |
|
110 | * |
|
111 | * <li> |
|
112 | * <p> |
|
113 | * <code>substring("12345", 1.5, 2.6)</code> returns |
|
114 | * <code>"234"</code> |
|
115 | * </p> |
|
116 | * </li> |
|
117 | * |
|
118 | * <li> |
|
119 | * <p> |
|
120 | * <code>substring("12345", 0, 3)</code> returns <code>"12"</code> |
|
121 | * |
|
122 | * </p> |
|
123 | * </li> |
|
124 | * |
|
125 | * <li> |
|
126 | * <p> |
|
127 | * <code>substring("12345", 0 div 0, 3)</code> returns <code>""</code> |
|
128 | * </p> |
|
129 | * </li> |
|
130 | * |
|
131 | * <li> |
|
132 | * <p>. |
|
133 | * <code>substring("12345", 1, 0 div 0)</code> returns |
|
134 | * |
|
135 | * <code>""</code> |
|
136 | * </p> |
|
137 | * </li> |
|
138 | * |
|
139 | * <li> |
|
140 | * <p> |
|
141 | * <code>substring("12345", -42, 1 div 0)</code> returns |
|
142 | * <code>"12345"</code> |
|
143 | * </p> |
|
144 | * </li> |
|
145 | * |
|
146 | * <li> |
|
147 | * <p> |
|
148 | * |
|
149 | * <code>substring("12345", -1 div 0, 1 div 0)</code> returns |
|
150 | * <code>""</code> </blockquote> |
|
151 | * |
|
152 | * @author bob mcwhirter (bob @ werken.com) |
|
153 | * |
|
154 | * @see <a href="http://www.w3.org/TR/xpath#function-substring" |
|
155 | * target="_top">Section 4.2 of the XPath Specification</a> |
|
156 | */ |
|
157 | public class SubstringFunction implements Function |
|
158 | { |
|
159 | ||
160 | /** |
|
161 | * Create a new <code>SubstringFunction</code> object. |
|
162 | */ |
|
163 | 294 | public SubstringFunction() {} |
164 | ||
165 | ||
166 | /** Returns a substring of an XPath string-value by character index. |
|
167 | * |
|
168 | * @param context the context at the point in the |
|
169 | * expression when the function is called |
|
170 | * @param args a list that contains two or three items |
|
171 | * |
|
172 | * @return a <code>String</code> containing the specifed character subsequence of |
|
173 | * the original string or the string-value of the context node |
|
174 | * |
|
175 | * @throws FunctionCallException if <code>args</code> has more than three |
|
176 | * or less than two items |
|
177 | */ |
|
178 | public Object call(Context context, |
|
179 | List args) throws FunctionCallException |
|
180 | { |
|
181 | 312 | final int argc = args.size(); |
182 | 312 | if (argc < 2 || argc > 3){ |
183 | 12 | throw new FunctionCallException( "substring() requires two or three arguments." ); |
184 | } |
|
185 | ||
186 | 300 | final Navigator nav = context.getNavigator(); |
187 | ||
188 | 300 | final String str = StringFunction.evaluate(args.get(0), nav ); |
189 | // The spec doesn't really address this case |
|
190 | 300 | if (str == null) { |
191 | 0 | return ""; |
192 | } |
|
193 | ||
194 | 300 | final int stringLength = (StringLengthFunction.evaluate(args.get(0), nav )).intValue(); |
195 | ||
196 | 300 | if (stringLength == 0) { |
197 | 6 | return ""; |
198 | } |
|
199 | ||
200 | 294 | Double d1 = NumberFunction.evaluate(args.get(1), nav); |
201 | ||
202 | 294 | if (d1.isNaN()){ |
203 | 30 | return ""; |
204 | } |
|
205 | // Round the value and subtract 1 as Java strings are zero based |
|
206 | 264 | int start = RoundFunction.evaluate(d1, nav).intValue() - 1; |
207 | ||
208 | 264 | int substringLength = stringLength; |
209 | 264 | if (argc == 3){ |
210 | 222 | Double d2 = NumberFunction.evaluate(args.get(2), nav); |
211 | ||
212 | 222 | if (!d2.isNaN()){ |
213 | 192 | substringLength = RoundFunction.evaluate(d2, nav ).intValue(); |
214 | } |
|
215 | else { |
|
216 | 30 | substringLength = 0; |
217 | } |
|
218 | } |
|
219 | ||
220 | 264 | if (substringLength < 0) return ""; |
221 | ||
222 | 252 | int end = start + substringLength; |
223 | 252 | if (argc == 2) end = stringLength; |
224 | ||
225 | // negative start is treated as 0 |
|
226 | 252 | if ( start < 0){ |
227 | 72 | start = 0; |
228 | } |
|
229 | 180 | else if (start > stringLength){ |
230 | 30 | return ""; |
231 | } |
|
232 | ||
233 | 222 | if (end > stringLength){ |
234 | 66 | end = stringLength; |
235 | } |
|
236 | 156 | else if (end < start) return ""; |
237 | ||
238 | 216 | if (stringLength == str.length()) { |
239 | // easy case; no surrogate pairs |
|
240 | 198 | return str.substring(start, end); |
241 | } |
|
242 | else { |
|
243 | 18 | return unicodeSubstring(str, start, end); |
244 | } |
|
245 | ||
246 | } |
|
247 | ||
248 | private static String unicodeSubstring(String s, int start, int end) { |
|
249 | ||
250 | 18 | StringBuffer result = new StringBuffer(s.length()); |
251 | 66 | for (int jChar = 0, uChar=0; uChar < end; jChar++, uChar++) { |
252 | 48 | char c = s.charAt(jChar); |
253 | 48 | if (uChar >= start) result.append(c); |
254 | 48 | if (c >= 0xD800) { // get the low surrogate |
255 | // ???? we could check here that this is indeed a low surroagte |
|
256 | // we could also catch StringIndexOutOfBoundsException |
|
257 | 18 | jChar++; |
258 | 18 | if (uChar >= start) result.append(s.charAt(jChar)); |
259 | } |
|
260 | } |
|
261 | 18 | return result.toString(); |
262 | } |
|
263 | } |