SubstringBeforeFunction


1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/SubstringBeforeFunction.java,v 1.8 2005/06/26 16:07:23 elharo Exp $
3    * $Revision: 1.8 $
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/
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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
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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: SubstringBeforeFunction.java,v 1.8 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><b>4.2</b> <code><i>string</i> substring-before(<i>string</i>,<i>string</i>)</code></p>
74   * 
75   * 
76   * <blockquote SRC="http://www.w3.org/TR/xpath#function-substring-before">
77   * The substring-before function returns the substring of the first argument 
78   * string that precedes the first occurrence of the second argument string 
79   * in the first argument string, or the empty string if the 
80   * first argument string does not contain the second argument string. 
81   * For example, substring-before("1999/04/01","/") returns 1999.
82   * </blockquote>
83   * 
84   * @author bob mcwhirter (bob @ werken.com)
85   * 
86   * @see <a HREF="http://www.w3.org/TR/xpath#function-substring-before" target="_top">Section 4.2 of the XPath Specification</a>
87   */
88  public class SubstringBeforeFunction implements Function
89  {
90  
91      
92      /**
93       * Create a new <code>SubstringBeforeFunction</code> object.
94       */
95      public SubstringBeforeFunction() {}
96      
97      
98      /** 
99       * Returns the part of the string-value of the first item in <code>args</code>
100      * that comes before the string-value of the second item in <code>args</code>;
101      * or the empty string if the second string is not a substring of the first string.
102      *
103      * @param context the context at the point in the
104      *         expression when the function is called
105      * @param args a list that contains two items
106      * 
107      * @return a <code>String</code> containing that 
108      *     part of the string-value of the first item in <code>args</code>
109      *     that comes before the string-value of the second item in <code>args</code>
110      * 
111      * @throws FunctionCallException if <code>args</code> does not have length two
112      */
113     public Object   call(Context context,
114                        List   args) throws FunctionCallException
115     {
116         if (args.size() == 2)
117         {
118             return evaluate( args.get(0),
119                              args.get(1),
120                              context.getNavigator() );
121         }
122 
123         throw new FunctionCallException( "substring-before() requires two arguments." );
124     }
125 
126     /** 
127      * Returns the part of <code>strArg</code> that precedes the first occurence 
128      * of <code>matchArg</code>; or the empty string if the 
129      * <code>strArg</code> does not contain <code>matchArg</code>
130      * 
131      * @param strArg the string from which the substring is extracted
132      * @param matchArg the string that marks the boundary of the substring
133      * @param nav the <code>Navigator</code> used to calculate the string-values of
134      *     the first two arguments
135      * 
136      * @return a <code>String</code> containing the part of <code>strArg</code> that precedes the first occurence 
137      * of <code>matchArg</code>
138      * 
139      */
140     public static String   evaluate(Object   strArg,
141                                   Object   matchArg,
142                                   Navigator nav)
143     {
144         String   str   = StringFunction.evaluate( strArg,
145                                                 nav );
146 
147         String   match = StringFunction.evaluate( matchArg,
148                                                 nav );
149 
150         int loc = str.indexOf(match);
151 
152         if ( loc < 0 )
153         {
154             return "";
155         }
156 
157         return str.substring(0, loc);
158 
159     }
160 }
161
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