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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: SubstringBeforeFunction.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  import org.jaxen.Navigator;
57  
58  /**
59   * <p><b>4.2</b> <code><i>string</i> substring-before(<i>string</i>,<i>string</i>)</code></p>
60   * 
61   * 
62   * <blockquote src="http://www.w3.org/TR/xpath#function-substring-before">
63   * The substring-before function returns the substring of the first argument 
64   * string that precedes the first occurrence of the second argument string 
65   * in the first argument string, or the empty string if the 
66   * first argument string does not contain the second argument string. 
67   * For example, substring-before("1999/04/01","/") returns 1999.
68   * </blockquote>
69   * 
70   * @author bob mcwhirter (bob @ werken.com)
71   * 
72   * @see <a href="http://www.w3.org/TR/xpath#function-substring-before" target="_top">Section 4.2 of the XPath Specification</a>
73   */
74  public class SubstringBeforeFunction implements Function
75  {
76  
77      
78      /**
79       * Create a new <code>SubstringBeforeFunction</code> object.
80       */
81      public SubstringBeforeFunction() {}
82      
83      
84      /** 
85       * Returns the part of the string-value of the first item in <code>args</code>
86       * that comes before the string-value of the second item in <code>args</code>;
87       * or the empty string if the second string is not a substring of the first string.
88       *
89       * @param context the context at the point in the
90       *         expression when the function is called
91       * @param args a list that contains two items
92       * 
93       * @return a <code>String</code> containing that 
94       *     part of the string-value of the first item in <code>args</code>
95       *     that comes before the string-value of the second item in <code>args</code>
96       * 
97       * @throws FunctionCallException if <code>args</code> does not have length two
98       */
99      public Object call(Context context,
100                        List args) throws FunctionCallException
101     {
102         if (args.size() == 2)
103         {
104             return evaluate( args.get(0),
105                              args.get(1),
106                              context.getNavigator() );
107         }
108 
109         throw new FunctionCallException( "substring-before() requires two arguments." );
110     }
111 
112     /** 
113      * Returns the part of <code>strArg</code> that precedes the first occurence 
114      * of <code>matchArg</code>; or the empty string if the 
115      * <code>strArg</code> does not contain <code>matchArg</code>
116      * 
117      * @param strArg the string from which the substring is extracted
118      * @param matchArg the string that marks the boundary of the substring
119      * @param nav the <code>Navigator</code> used to calculate the string-values of
120      *     the first two arguments
121      * 
122      * @return a <code>String</code> containing the part of <code>strArg</code> that precedes the first occurence 
123      * of <code>matchArg</code>
124      * 
125      */
126     public static String evaluate(Object strArg,
127                                   Object matchArg,
128                                   Navigator nav)
129     {
130         String str   = StringFunction.evaluate( strArg,
131                                                 nav );
132 
133         String match = StringFunction.evaluate( matchArg,
134                                                 nav );
135 
136         int loc = str.indexOf(match);
137 
138         if ( loc < 0 )
139         {
140             return "";
141         }
142 
143         return str.substring(0, loc);
144 
145     }
146 }