Coverage Report - org.jaxen.function.StringLengthFunction
 
Classes in this File Line Coverage Branch Coverage Complexity
StringLengthFunction
90%
19/21
100%
5/5
4.667
 
 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  
 }