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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/NormalizeSpaceFunction.java,v 1.15 2005/06/26 16:07:23 elharo Exp $
3    * $Revision: 1.15 $
4    * $Date: 2005/06/26 16:07:23 $
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   * $Id: NormalizeSpaceFunction.java,v 1.15 2005/06/26 16:07:23 elharo Exp $
60   */
61  
62  
63  package org.jaxen.function;
64  
65  import java.util.List;
66  
67  import org.jaxen.Context;
68  import org.jaxen.Function;
69  import org.jaxen.FunctionCallException;
70  import org.jaxen.Navigator;
71  
72  /***
73   * <p>
74   * <b>4.2</b> <code><i>string</i> normalize-space(<i>string</i>)</code>
75   * </p>
76   * 
77   * <blockquote src="http://www.w3.org/TR/xpath#function-normalize-space"> 
78   * The <b>normalize-space</b> function
79   * returns the argument string with whitespace normalized by stripping
80   * leading and trailing whitespace and replacing sequences of whitespace
81   * characters by a single space. Whitespace characters are the same as
82   * those allowed by the <a href="http://www.w3.org/TR/REC-xml#NT-S" target="_top">S</a>
83   * production in XML. If the argument is omitted, it defaults to the
84   * context node converted to a string, in other words the <a
85   * href="http://www.w3.org/TR/xpath#dt-string-value"  
86   * target="_top">string-value</a> of the context node.
87   * </blockquote>
88   * 
89   * @author James Strachan (james@metastuff.com)
90   * @see <a href="http://www.w3.org/TR/xpath#function-normalize-space"
91   *      target="_top">Section 4.2 of the XPath Specification</a>
92   */
93  public class NormalizeSpaceFunction implements Function
94  {
95  
96  
97      /***
98       * Create a new <code>NormalizeSpaceFunction</code> object.
99       */
100     public NormalizeSpaceFunction() {}
101     
102     /*** 
103      * Returns the string-value of the first item in <code>args</code>
104      * after removing all leading and trailing white space, and 
105      * replacing each other sequence of whitespace by a single space.
106      * Whitespace consists of the characters space (0x32), carriage return (0x0D),
107      * linefeed (0x0A), and tab (0x09).
108      *
109      * @param context the context at the point in the
110      *         expression when the function is called
111      * @param args a list that contains exactly one item
112      * 
113      * @return a normalized <code>String</code>
114      * 
115      * @throws FunctionCallException if <code>args</code> does not have length one
116      */
117     public Object call(Context context,
118                        List args) throws FunctionCallException
119     {
120         
121         if (args.size() == 0) {
122             return evaluate( context.getNodeSet(),
123                              context.getNavigator() );
124         }
125         else if (args.size() == 1)
126         {
127             return evaluate( args.get(0),
128                              context.getNavigator() );
129         }
130     
131         throw new FunctionCallException( "normalize-space() cannot have more than one argument" );
132     }
133 
134     /*** 
135      * Returns the string-value of <code>strArg</code> after removing
136      * all leading and trailing white space, and 
137      * replacing each other sequence of whitespace by a single space.
138      * Whitespace consists of the characters space (0x32), carriage return (0x0D),
139      * linefeed (0x0A), and tab (0x09).
140      *
141      * @param strArg the object whose string-value is normalized
142      * @param nav the context at the point in the
143      *         expression when the function is called
144      * 
145      * @return the normalized string-value
146      */
147     public static String evaluate(Object strArg,
148                                   Navigator nav) 
149     {
150         String str = StringFunction.evaluate( strArg,
151                                               nav );
152 
153         char[] buffer = str.toCharArray();
154         int write = 0;
155         int lastWrite = 0;
156         boolean wroteOne = false;
157         int read = 0;
158         while (read < buffer.length)
159         {
160             if (isXMLSpace(buffer[read]))
161             {
162                 if (wroteOne)
163                 {
164                     buffer[write++] = ' ';
165                 }
166                 do
167                 {
168                     read++;
169                 }
170                 while(read < buffer.length && isXMLSpace(buffer[read]));
171             }
172             else
173             {
174                 buffer[write++] = buffer[read++];
175                 wroteOne = true;
176                 lastWrite = write;
177             }
178         }
179 
180         return new String(buffer, 0, lastWrite);
181     }
182     
183     
184     private static boolean isXMLSpace(char c) {
185         return c == ' ' || c == '\n' || c == '\r' || c == '\t';
186     }
187     
188 }