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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/ConcatFunction.java,v 1.7 2005/06/26 16:07:23 elharo Exp $
3    * $Revision: 1.7 $
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: ConcatFunction.java,v 1.7 2005/06/26 16:07:23 elharo Exp $
60   */
61  
62  
63  package org.jaxen.function;
64  
65  import java.util.Iterator;
66  import java.util.List;
67  
68  import org.jaxen.Context;
69  import org.jaxen.Function;
70  import org.jaxen.FunctionCallException;
71  import org.jaxen.Navigator;
72  
73  /***
74   * <b>4.2</b> <code><i>string</i> concat(<i>string</i>,<i>string</i>,<i>string*</i>)</code> 
75   * <p>
76   * Concatenates its arguments and returns the resulting string.
77   * </p>
78   *  
79   *  @author bob mcwhirter (bob@werken.com)
80   * 
81   * @see <a href="http://www.w3.org/TR/xpath#function-concat">Section 4.2 of the XPath Specification</a>
82   */
83  public class ConcatFunction implements Function
84  {
85  
86      /***
87       * Create a new <code>ConcatFunction</code> object.
88       */
89      public ConcatFunction() {}
90      
91      /*** 
92       * Concatenates the arguments and returns the resulting string.
93       * Non-string items are first converted to strings as if by the 
94       * XPath <code>string()<code> function.
95       *
96       * @param context the context at the point in the
97       *         expression when the function is called
98       * @param args the list of strings to be concatenated
99       * 
100      * @return a <code>String</code> containing the concatenation of the items 
101      *     of <code>args</code>
102      * 
103      * @throws FunctionCallException if <code>args</code> has less than two items
104      */
105     public Object call(Context context,
106                        List args) throws FunctionCallException
107     {
108         if ( args.size() >= 2 )
109         {
110             return evaluate( args,
111                              context.getNavigator() );
112         }
113 
114         throw new FunctionCallException("concat() requires at least two arguments");
115     }
116 
117     /*** 
118      * Converts each item in the list to a string and returns the 
119      * concatenation of these strings.
120      * If necessary, each item is first converted to a <code>String</code>
121      * as if by the XPath <code>string()</code> function.
122      * 
123      * @param list the items to be concatenated
124      * @param nav ignored
125      * 
126      * @return the concatenation of the arguments
127      */
128    public static String evaluate(List list,
129                                   Navigator nav)
130     {
131         StringBuffer result = new StringBuffer();
132         Iterator argIter = list.iterator();
133         while ( argIter.hasNext() )
134         {
135             result.append( StringFunction.evaluate( argIter.next(),
136                                                     nav ) );
137         }
138     
139         return result.toString();
140     }
141 }