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1   package net.sourceforge.pmd.lang.vm.ast;
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  /**
23   * This class is responsible for handling the references in VTL ($foo).
24   * 
25   * Please look at the Parser.jjt file which is what controls the generation of this class.
26   * 
27   * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
28   * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
29   * @author <a href="mailto:Christoph.Reck@dlr.de">Christoph Reck</a>
30   * @author <a href="mailto:kjohnson@transparent.com>Kent Johnson</a>
31   * @version $Id: ASTReference.java 806597 2009-08-21 15:21:44Z nbubna $
32   */
33  public class ASTReference extends AbstractVmNode {
34      private String rootString;
35  
36      private String literal = null;
37  
38      /**
39       * Indicates if we are running in strict reference mode.
40       */
41      public boolean strictRef = false;
42  
43      /**
44       * Indicates if toString() should be called during condition evaluation just to ensure it does not return null.
45       * Check is unnecessary if all toString() implementations are known to have non-null return values. Disabling the
46       * check will give a performance improval since toString() may be a complex operation on large objects.
47       */
48      public boolean toStringNullCheck = true;
49  
50      /**
51       * @param id
52       */
53      public ASTReference(final int id) {
54          super(id);
55      }
56  
57      /**
58       * @param p
59       * @param id
60       */
61      public ASTReference(final VmParser p, final int id) {
62          super(p, id);
63      }
64  
65      /**
66       * @see org.apache.velocity.runtime.parser.node.SimpleNode#jjtAccept(org.apache.velocity.runtime.parser.node.VmParserVisitor,
67       *      java.lang.Object)
68       */
69      @Override
70      public Object jjtAccept(final VmParserVisitor visitor, final Object data) {
71          return visitor.visit(this, data);
72      }
73  
74      /**
75       * Returns the 'root string', the reference key
76       * 
77       * @return the root string.
78       */
79      public String getRootString() {
80          return rootString;
81      }
82  
83      /**
84       * Routine to allow the literal representation to be externally overridden. Used now in the VM system to override a
85       * reference in a VM tree with the literal of the calling arg to make it work nicely when calling arg is null. It
86       * seems a bit much, but does keep things consistant.
87       * 
88       * Note, you can only set the literal once...
89       * 
90       * @param literal String to render to when null
91       */
92      public void setLiteral(final String literal) {
93          /*
94           * do only once
95           */
96  
97          if (this.literal == null) {
98              this.literal = literal;
99          }
100     }
101 
102     /**
103      * Override of the SimpleNode method literal() Returns the literal representation of the node. Should be something
104      * like $<token>.
105      * 
106      * @return A literal string.
107      */
108     @Override
109     public String literal() {
110         if (literal != null) {
111             return literal;
112         }
113 
114         // this value could be cached in this.literal but it increases memory usage
115         return super.literal();
116     }
117 }