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Java > Open Source Codes > org > eclipse > ui > internal > navigator > NavigatorExtensionStateService


1 /*******************************************************************************
2  * Copyright (c) 2007 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
12 package org.eclipse.ui.internal.navigator;
13
14 import java.util.HashMap JavaDoc;
15 import java.util.Map JavaDoc;
16
17 import org.eclipse.ui.internal.navigator.extensions.ExtensionStateModel;
18 import org.eclipse.ui.navigator.IExtensionStateModel;
19 import org.eclipse.ui.navigator.INavigatorContentDescriptor;
20 import org.eclipse.ui.navigator.INavigatorContentService;
21
22 /**
23  *
24  * A content extension may have its content and label providers disposed
25  * whenever the extension is activated or deactivated. However, the state model
26  * lives throughout the life of the viewer to allow Action Providers to drive
27  * their behavior from it.
28  *
29  * @since 3.3
30  *
31  */
32 public class NavigatorExtensionStateService {
33
34     private final Object JavaDoc lock = new Object JavaDoc();
35     private INavigatorContentService contentService;
36
37     /**
38      * Create an ExtensionStateServie that will keep track of the state models
39      * of content extensions.
40      *
41      * @param theContentService
42      * The content service which manages this state model service.
43      */
44     public NavigatorExtensionStateService(INavigatorContentService theContentService) {
45         contentService = theContentService;
46     }
47
48     /*
49      * A map of (String-based-Navigator-Content-Extension-IDs,
50      * NavigatorContentExtension-objects)-pairs
51      */
52     private final Map JavaDoc/* <INavigatorContentDescriptor, IExtensionStateModel> */stateModels = new HashMap JavaDoc();
53
54     /**
55      * Return the state model for the given descriptor.
56      *
57      * @param aDescriptor A content descriptor
58      * @return The state model for the given descriptor.
59      */
60     public IExtensionStateModel getExtensionStateModel(
61             INavigatorContentDescriptor aDescriptor) {
62         synchronized (lock) {
63             IExtensionStateModel model = (IExtensionStateModel) stateModels
64                     .get(aDescriptor);
65             if (model == null)
66                 stateModels.put(aDescriptor, model = new ExtensionStateModel(
67                         aDescriptor.getId(), contentService.getViewerId()));
68             return model;
69         }
70     }
71
72 }
73
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