SpecialTagHandler


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54  
55  /**
56   * <CODE>SpecialTagHandler</CODE> represents a tag which requires
57   * handling within server side parsed page. This could be a
58   * class handling &lt;SERVLET&gt;-Tags or any other tag. See
59   * PageParser, SSI and ParameterPropagatingSSI for examples.
60   *
61   * <p>A class to plug into PageParser <em>must</em> implement 
62   * this interface and <em>must</em> have a simple constructor 
63   * without parameters and can then be added with
64   * <code>addTagHandler()</code> to a PageParser servlet.
65   *
66   * @version $Revision: 1.5 $ $Date: 2004/12/01 07:54:28 $
67   * @author <A HREF="mailto:zeller@think.de">Henner Zeller</A>
68   */
69  
70  /*
71   * $Id: SpecialTagHandler.java,v 1.5 2004/12/01 07:54:28 hengels Exp $
72   * Copyright 2000,2005 wingS development team.
73   *
74   * This file is part of wingS (http://www.j-wings.org).
75   *
76   * wingS is free software; you can redistribute it and/or modify
77   * it under the terms of the GNU Lesser General Public License
78   * as published by the Free Software Foundation; either version 2.1
79   * of the License, or (at your option) any later version.
80   *
81   * Please see COPYING for the complete licence.
82   */
83  package org.wings.template.parser;
84  
85  import java.io.IOException  ;
86  import java.io.InputStream  ;
87  
88  public interface SpecialTagHandler {
89      /**
90       * Parse tag.
91       * This method is invoked if a tag with a name
92       * this class is registered for is found.
93       * It gets the ServletConfiguration of the PageParser
94       * servet and a PositionReader, placed after name of
95       * the current tag.<p>
96       * The <CODE>parseTag()</CODE> method is called <em>before</em>
97       * any processing is done. Its purpose is to parse the area
98       * this tag spans and probably read in parameters used at
99       * execution time.<p>
100      * This method returns the last tag belonging to the
101      * area handled by this handler (for server side included
102      * servlets, this would be <CODE>&lt;/SERVLET&gt;</CODE>).
103      * For simple one-tag Handlers this is simply the tag passed
104      * to this method. If the Handler decides not to handle this tag, this
105      * method should return <CODE>null</CODE>.
106      *
107      * @param context The context used while parsing; contains
108      *                at least the HttpServletRequest and HttpServletResponse.
109      * @param input    The PositionReader, located after the Name token
110      *                 of the Tag
111      * @param startPos The Position parsing of this token began
112      * @param startTag the SGMLTag found in the file.
113      */
114     SGMLTag parseTag(ParseContext context,
115                      PositionReader input,
116                      long startPos,
117                      SGMLTag startTag)
118             throws IOException  ;
119 
120     /**
121      * Get start position of the area in the sourcefile this
122      * handler processes.
123      * This is usually the position of the &quot;<code>&lt;</code>&quot;
124      * of the <code>&lt;SpecialTag&gt;</code> within the inputfile.
125      */
126     long getTagStart();
127 
128     /**
129      * Get the length of the area in the sourcefile.
130      * The area this handler processes is skipped in the inputfile.
131      * Usually this represents the length of the single
132      * <code>&lt;SpecialTag&gt;</code> or the
133      * area <code>&lt;SpecialTag&gt;...&lt;/SpecialTag&gt;</code>
134      */
135     long getTagLength();
136 
137     /**
138      * actually perform the action associated with this tag.
139      *
140      * @throws Exception anything can happen .. and throw an Exception
141      *                   which is caught in PageParser
142      */
143     void executeTag(ParseContext context, InputStream   input)
144             throws Exception  ;
145 }
146 
147 /* 
148  * Local variables:
149  * c-basic-offset: 4
150  * compile-command: "ant -emacs -find build.xml"
151  * End:
152  */
153 
154 
155
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