IntroEvaluationContext


1   /*******************************************************************************
2    * Copyright (c) 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.ui.internal.intro.impl.util;
12  
13  import org.eclipse.core.expressions.EvaluationContext;
14  import org.eclipse.core.runtime.Platform;
15  import org.eclipse.ui.PlatformUI;
16  
17  /*
18   * Supplies en evaluation context for filtering intro documents. This is used for
19   * resolving variables in enablement expressions.
20   */
21  public final class IntroEvaluationContext {
22  
23      private static final String   VARIABLE_PLATFORM = "platform"; //$NON-NLS-1$
24      private static final String   VARIABLE_WORKBENCH = "workbench"; //$NON-NLS-1$
25      
26      private static EvaluationContext context;
27      
28      /*
29       * Returns the evaluation context to use in intro documents.
30       */
31      public static EvaluationContext getContext() {
32          if (context == null) {
33              context = new EvaluationContext(null, Platform.class) {
34                  public Object   getVariable(String   name) {
35                      if (VARIABLE_PLATFORM.equals(name)) {
36                          return Platform.class;
37                      }
38                      else if (VARIABLE_WORKBENCH.equals(name)) {
39                          return PlatformUI.getWorkbench();
40                      }
41                      return null;
42                  }
43              };
44          }
45          return context;
46      }
47      
48      /*
49       * Not meant to be instantiated.
50       */
51      private IntroEvaluationContext() {
52      }
53  }
54
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