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1   package org.apache.velocity.runtime.directive;
2   
3   /*
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *   http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.    
20   */
21  
22  import java.io.Writer;
23  import org.apache.velocity.context.InternalContextAdapter;
24  import org.apache.velocity.exception.TemplateInitException;
25  import org.apache.velocity.exception.VelocityException;
26  import org.apache.velocity.runtime.log.Log;
27  import org.apache.velocity.runtime.RuntimeConstants;
28  import org.apache.velocity.runtime.RuntimeServices;
29  import org.apache.velocity.runtime.parser.node.Node;
30  
31  /**
32   * Directive that puts an unrendered AST block in the context
33   * under the specified key, postponing rendering until the
34   * reference is used and rendered.
35   *
36   * @author Andrew Tetlaw
37   * @author Nathan Bubna
38   * @version $Id: Define.java 686842 2008-08-18 18:29:31Z nbubna $
39   */
40  public class Define extends Block
41  {
42      /**
43       * Return name of this directive.
44       */
45      public String getName()
46      {
47          return "define";
48      }
49  
50      /**
51       *  simple init - get the key
52       */
53      public void init(RuntimeServices rs, InternalContextAdapter context, Node node)
54          throws TemplateInitException
55      {
56          super.init(rs, context, node);
57  
58          // the first child is the block name (key), the second child is the block AST body
59          if ( node.jjtGetNumChildren() != 2 )
60          {
61              throw new VelocityException("parameter missing: block name at "
62                   + Log.formatFileString(this));
63          }
64          
65          /*
66           * first token is the name of the block. We don't even check the format,
67           * just assume it looks like this: $block_name. Should we check if it has
68           * a '$' or not?
69           */
70          key = node.jjtGetChild(0).getFirstToken().image.substring(1);
71  
72          /*
73           * default max depth of two is used because intentional recursion is
74           * unlikely and discouraged, so make unintentional ones end fast
75           */
76          maxDepth = rs.getInt(RuntimeConstants.DEFINE_DIRECTIVE_MAXDEPTH, 2);
77      }
78  
79      /**
80       * directive.render() simply makes an instance of the Block inner class
81       * and places it into the context as indicated.
82       */
83      public boolean render(InternalContextAdapter context, Writer writer, Node node)
84      {
85          /* put a Block.Reference instance into the context,
86           * using the user-defined key, for later inline rendering.
87           */
88          context.put(key, new Reference(context, this));
89          return true;
90      }
91  
92  }