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Java > Open Source Codes > org > apache > commons > jelly > tags > define > ExtendTag


1 /*
2  * Copyright 1999-2002,2004 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.apache.commons.jelly.tags.define;
17
18 import org.apache.commons.jelly.JellyTagException;
19 import org.apache.commons.jelly.Script;
20 import org.apache.commons.jelly.XMLOutput;
21 import org.apache.commons.jelly.impl.DynamicTagLibrary;
22
23 /**
24  * <extend> is used to extend a dynamic tag defined in an inherited
25  * dynamic tag library
26  * <p/>
27  *
28  * @author <a HREF="mailto:tima@intalio.com">Tim Anderson</a>
29  * @version $Revision: 155420 $
30  * @see SuperTag
31  */
32 public class ExtendTag extends DefineTagSupport {
33
34     private String JavaDoc name;
35
36     private Script superScript;
37
38     public ExtendTag() {
39     }
40
41     // Tag interface
42 //-------------------------------------------------------------------------
43 public void doTag(XMLOutput output) throws JellyTagException {
44         DynamicTagLibrary library = getTagLibrary();
45         DynamicTagLibrary owner = library.find(getName());
46         if (owner == null) {
47             throw new JellyTagException(
48                 "Cannot extend " + getName() + ": dynamic tag not defined");
49         }
50         if (owner == library) {
51             // disallow extension of tags defined within the same tag
52 // library
53 throw new JellyTagException("Cannot extend " + getName() +
54                                      ": dynamic tag defined locally");
55         }
56         superScript = owner.getDynamicTag(name);
57         if (superScript == null) {
58             // tag doesn't define a script - disallow this for the moment.
59 throw new JellyTagException("Cannot extend " + getName() +
60                                      ": tag is not a dynamic tag");
61         }
62
63         owner.registerDynamicTag(getName() , getBody());
64     }
65
66     // Properties
67 //-------------------------------------------------------------------------
68
69     /**
70      * @return the name of the tag to create
71      */
72     public String JavaDoc getName() {
73         return name;
74     }
75
76     /**
77      * Sets the name of the tag to create
78      */
79     public void setName(String JavaDoc name) {
80         this.name = name;
81     }
82
83     /**
84      * Returns the parent implementation of this tag
85      */
86     public Script getSuperScript() {
87         return superScript;
88     }
89 }
90
91
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