Coverage Report - org.jaxen.function.SubstringFunction

Classes in this File Line Coverage Branch Coverage Complexity
SubstringFunction
98% 
100% 
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  
 }