DefaultVariable


1   /*******************************************************************************
2    * Copyright (c) 2000, 2006 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    *
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  package org.eclipse.core.internal.expressions;
12  
13  import org.eclipse.core.runtime.Assert;
14  import org.eclipse.core.runtime.CoreException;
15  
16  import org.eclipse.core.expressions.IEvaluationContext;
17  
18  /**
19   * An evaluation context that can be used to add a new default variable
20   * to a hierarchy of evaluation contexts.
21   * 
22   * @since 3.0
23   */
24  public final class DefaultVariable implements IEvaluationContext {
25  
26      private Object   fDefaultVariable;
27      private IEvaluationContext fParent;
28      private IEvaluationContext fManagedPool;
29      
30      /**
31       * Constructs a new variable pool for a single default variable.
32       * 
33       * @param parent the parent context for the default variable. Must not 
34       *  be <code>null</code>.
35       * @param defaultVariable the default variable
36       */
37      public DefaultVariable(IEvaluationContext parent, Object   defaultVariable) {
38          Assert.isNotNull(parent);
39          Assert.isNotNull(defaultVariable);
40          fParent= parent;
41          while (parent instanceof DefaultVariable) {
42              parent= parent.getParent();
43          }
44          fManagedPool= parent;
45          fDefaultVariable= defaultVariable;
46      }
47  
48      /**
49       * {@inheritDoc}
50       */
51      public IEvaluationContext getParent() {
52          return fParent;
53      }
54  
55      /**
56       * {@inheritDoc}
57       */
58      public IEvaluationContext getRoot() {
59          return fParent.getRoot();
60      }
61  
62      /**
63       * {@inheritDoc}
64       */
65      public Object   getDefaultVariable() {
66          return fDefaultVariable;
67      }
68      
69      /**
70       * {@inheritDoc}
71       */
72      public void setAllowPluginActivation(boolean value) {
73          fParent.setAllowPluginActivation(value);
74      }
75      
76      /**
77       * {@inheritDoc}
78       */
79      public boolean getAllowPluginActivation() {
80          return fParent.getAllowPluginActivation();
81      }
82  
83      /**
84       * {@inheritDoc}
85       */
86      public void addVariable(String   name, Object   value) {
87          fManagedPool.addVariable(name, value);
88      }
89  
90      /**
91       * {@inheritDoc}
92       */
93      public Object   removeVariable(String   name) {
94          return fManagedPool.removeVariable(name);
95      }
96  
97      /**
98       * {@inheritDoc}
99       */
100     public Object   getVariable(String   name) {
101         return fManagedPool.getVariable(name);
102     }
103 
104     /**
105      * {@inheritDoc}
106      */
107     public Object   resolveVariable(String   name, Object  [] args) throws CoreException {
108         return fManagedPool.resolveVariable(name, args);
109     }
110 }
111
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