View Javadoc

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.VelocityException;
25  import org.apache.velocity.runtime.RuntimeServices;
26  import org.apache.velocity.runtime.log.Log;
27  import org.apache.velocity.runtime.parser.node.Node;
28  
29  /**
30   * Break directive used for interrupting scopes.
31   *
32   * @author <a href="mailto:wyla@removethis.sci.fi">Jarkko Viinamaki</a>
33   * @author Nathan Bubna
34   * @version $Id$
35   */
36  public class Break extends Directive
37  {
38      private boolean scoped = false;
39  
40      /**
41       * Return name of this directive.
42       * @return The name of this directive.
43       */
44      public String getName()
45      {
46          return "break";
47      }
48  
49      /**
50       * Return type of this directive.
51       * @return The type of this directive.
52       */
53      public int getType()
54      {
55          return LINE;
56      }
57  
58      /**
59       * Since there is no processing of content,
60       * there is never a need for an internal scope.
61       */
62      public boolean isScopeProvided()
63      {
64          return false;
65      }
66  
67      /**
68       *  simple init - init the tree and get the elementKey from
69       *  the AST
70       * @param rs
71       * @param context
72       * @param node
73       * @throws TemplateInitException
74       */
75      public void init(RuntimeServices rs, InternalContextAdapter context, Node node)
76      {
77          super.init(rs, context, node);
78  
79          int kids = node.jjtGetNumChildren();
80          if (kids > 1)
81          {  
82              throw new VelocityException("The #stop directive only accepts a single scope object at "
83                   + Log.formatFileString(this));
84          }
85          else
86          {
87              this.scoped = (kids == 1);
88          }
89      }
90  
91      /**
92       * Break directive does not actually do any rendering. 
93       * 
94       * This directive throws a StopCommand which signals either
95       * the nearest Scope or the specified scope to stop rendering
96       * its content.
97       * 
98       * @param context
99       * @param writer
100      * @param node
101      * @return never, always throws a StopCommand
102      */
103     public boolean render(InternalContextAdapter context, Writer writer, Node node)
104     {
105         if (!scoped)
106         {
107             throw new StopCommand();
108         }
109 
110         Object argument = node.jjtGetChild(0).value(context);
111         if (argument instanceof Scope)
112         {
113             ((Scope)argument).stop();
114         }
115         else
116         {
117             throw new VelocityException(node.jjtGetChild(0).literal()+
118                 " is not a valid " + Scope.class.getName() + " instance at "
119                 + Log.formatFileString(this));
120         }
121         return false;
122     }
123 
124 }