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1   /*
2    * $Header$
3    * $Revision: 1128 $
4    * $Date: 2006-02-05 13:49:04 -0800 (Sun, 05 Feb 2006) $
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: FalseFunction.java 1128 2006-02-05 21:49:04Z elharo $
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  
57  /**
58   * <p><b>4.3</b> <code><i>boolean</i> false()</code> 
59   * 
60   * <p>Returns false.</p>
61   * 
62   * @author bob mcwhirter (bob @ werken.com)
63   * 
64   * @see <a href="http://www.w3.org/TR/xpath#function-false">Section 4.3 of the XPath Specification</a>
65   */
66  public class FalseFunction implements Function
67  {
68  
69      /**
70       * Create a new <code>FalseFunction</code> object.
71       */
72      public FalseFunction() {}
73      
74      /** Returns <code>Boolean.FALSE</code>
75       *
76       * @param context the context at the point in the
77       *         expression when the function is called
78       * @param args an empty list
79       * 
80       * @return <code>Boolean.FALSE</code>
81       * 
82       * @throws FunctionCallException if <code>args</code> is not empty
83       */
84      public Object call(Context context,
85                         List args) throws FunctionCallException
86      {
87          if (args.size() == 0)
88          {
89              return evaluate();
90          }
91  
92          throw new FunctionCallException( "false() requires no arguments." );
93      }
94  
95      /**
96       * Returns false.
97       * 
98       * @return <code>Boolean.FALSE</code>
99       */
100     public static Boolean evaluate()
101     {
102         return Boolean.FALSE;
103     }
104 }