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Java > Open Source Codes > com > caucho > jsp > java > JstlXmlWhen


1 /*
2  * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
3  *
4  * This file is part of Resin(R) Open Source
5  *
6  * Each copy or derived work must preserve the copyright notice and this
7  * notice unmodified.
8  *
9  * Resin Open Source is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * Resin Open Source is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
17  * of NON-INFRINGEMENT. See the GNU General Public License for more
18  * details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with Resin Open Source; if not, write to the
22  * Free SoftwareFoundation, Inc.
23  * 59 Temple Place, Suite 330
24  * Boston, MA 02111-1307 USA
25  *
26  * @author Scott Ferguson
27  */
28
29 package com.caucho.jsp.java;
30
31 import com.caucho.jsp.JspParseException;
32 import com.caucho.vfs.WriteStream;
33 import com.caucho.xml.QName;
34
35 import java.io.IOException JavaDoc;
36
37 /**
38  * Special generator for a JSTL x:when tag.
39  */
40 public class JstlXmlWhen extends JstlNode {
41   private static final QName SELECT = new QName("select");
42   
43   private String JavaDoc _select;
44   
45   /**
46    * Adds an attribute.
47    */
48   public void addAttribute(QName name, String JavaDoc value)
49     throws JspParseException
50   {
51     if (SELECT.equals(name))
52       _select = value;
53     else
54       throw error(L.l("`{0}' is an unknown attribute for <{1}>.",
55                       name.getName(), getTagName()));
56   }
57   
58   /**
59    * Adds an attribute.
60    */
61   public void addAttribute(QName name, JspAttribute value)
62     throws JspParseException
63   {
64     if (false)
65       throw error(L.l("`{0}' is an unknown jsp:attribute for <{1}>.",
66                       name.getName(), getTagName()));
67   }
68
69   /**
70    * Generates the XML text representation for the tag validation.
71    *
72    * @param os write stream to the generated XML.
73    */
74   public void printXml(WriteStream os)
75     throws IOException JavaDoc
76   {
77     os.print("<x:when select=\"");
78     printXmlText(os, _select);
79     os.print("\">");
80
81     printXmlChildren(os);
82
83     os.print("</x:when>");
84   }
85   
86   /**
87    * Generates the code for the x:when tag.
88    */
89   public void generate(JspJavaWriter out)
90     throws Exception JavaDoc
91   {
92     if (_select == null)
93       throw error(L.l("required attribute `select' missing from <{0}>",
94                       getTagName()));
95
96
97     String JavaDoc ifExpr = ("com.caucho.jstl.el.XmlIfTag.evalBoolean(pageContext, " +
98              _gen.addXPathExpr(_select, getNamespaceContext()) + ")");
99
100
101     out.println("if (" + ifExpr + ") {");
102     out.pushDepth();
103     
104     generateChildren(out);
105
106     out.popDepth();
107     out.println("}");
108   }
109 }
110
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