History


1   /*******************************************************************************
2    * Copyright (c) 2004, 2005 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.model;
12  
13  import java.util.List  ;
14  import java.util.Vector  ;
15  
16  import org.eclipse.ui.internal.intro.impl.model.url.IntroURLParser;
17  
18  /*
19   * Intro History Model.
20   */
21  public class History {
22      // History of Intro Pages and real URL visited by Intro Browser. All
23      // elements are all of type HistoryObject.
24      private Vector   history = new Vector  ();
25      private int navigationLocation = 0;
26  
27  
28      // Model class for history objects. A history object may be a url or an
29      // Intro page. A url is a regular URL navigated to from a fully qualified
30      // link. An intro page may be an IFrame page. IFrame pages are not created
31      // for every Help topic navigated in an embedded IFrame. Instead the same
32      // IFrame is stored in history as a different object with the IFrameURL set.
33      // This way the model actually creates one page for every embedded Help
34      // Topic target but the navigation history updates the IFrame accordingly.
35      class HistoryObject {
36          AbstractIntroPage page;
37          String   iframeUrl;
38          String   url;
39  
40          HistoryObject(Object   location) {
41              if (location instanceof String  )
42                  this.url = (String  ) location;
43  
44              if (location instanceof AbstractIntroPage) {
45                  this.page = (AbstractIntroPage) location;
46                  // will be set to null if the page is not an IFrame page.
47                  this.iframeUrl = this.page.getIFrameURL();
48              }
49          }
50  
51          /**
52           * returns the history page. If iframe page, updated to correct url.
53           * 
54           * @return
55           */
56          AbstractIntroPage getPage() {
57              if (page.isIFramePage())
58                  // when page was stored, the IFrame url was also stored. Make
59                  // sure to return the same state. The page is the same, only the
60                  // IFrame url changes.
61                  page.setIFrameURL(getIFrameUrl());
62              return page;
63          }
64  
65          String   getPageId() {
66              return page.getId();
67          }
68  
69          String   getIFrameUrl() {
70              return iframeUrl;
71          }
72  
73          String   getUrl() {
74              return url;
75          }
76  
77          boolean isURL() {
78              return (url != null) ? true : false;
79          }
80  
81          boolean isIntroPage() {
82              return (page != null) ? true : false;
83          }
84  
85          boolean isIFramePage() {
86              return (iframeUrl != null) ? true : false;
87          }
88  
89      }
90  
91  
92      /**
93       * Updates the UI navigation history with either a real URL, or a page ID.
94       * 
95       * @param pageId
96       */
97      public void updateHistory(String   location) {
98          // quick exit.
99          if (!history.isEmpty() && isSameLocation(location))
100             // resetting the same location is useless.
101             return;
102         doUpdateHistory(location);
103     }
104 
105     /**
106      * Updates the UI navigation history with either a real URL, or a page ID.
107      * 
108      * @param page
109      */
110     public void updateHistory(AbstractIntroPage page) {
111         // quick exit.
112         if (!history.isEmpty() && isSameLocation(page))
113             // resetting the same location is useless.
114             return;
115         doUpdateHistory(page);
116     }
117 
118     private void doUpdateHistory(Object   location) {
119         // we got here due to an intro URL listener or an SWT Form hyperlink
120         // listener. location may be a url or an IntroPage.
121         if (navigationLocation == getHistoryEndPosition())
122             // we are at the end of the vector, just push.
123             pushToHistory(location);
124         else
125             // we already navigated. add item at current location, and clear
126             // rest of history. (Same as browser behavior.)
127             trimHistory(location);
128     }
129 
130 
131     private boolean isSameLocation(Object   location) {
132         HistoryObject currentLocation = getCurrentLocation();
133         if (location instanceof String   && currentLocation.isURL())
134             return currentLocation.getUrl().equals(location);
135 
136         if (location instanceof AbstractIntroPage
137                 && currentLocation.isIntroPage()) {
138 
139             AbstractIntroPage locationPage = (AbstractIntroPage) location;
140             // be carefull here with calling getPage on historyOvject.
141             if (!currentLocation.getPageId().equals(locationPage.getId()))
142                 return false;
143 
144             // both pages have same ids, they are either both regular pages or
145             // both are Iframe pages. check if they have the same IFrame urls
146             if (currentLocation.isIFramePage() && locationPage.isIFramePage())
147                 return currentLocation.getIFrameUrl().equals(
148                     locationPage.getIFrameURL());
149 
150             // both pages are not IFrame pages, and they have same id.
151             return true;
152         }
153 
154         return false;
155     }
156 
157 
158 
159 
160     private void pushToHistory(Object   location) {
161         history.add(new HistoryObject(location));
162         // point the nav location to the end of the vector.
163         navigationLocation = getHistoryEndPosition();
164     }
165     
166      public void removeLastHistory() {
167         history.remove(getHistoryEndPosition());
168         // point the nav location to the end of the vector.
169         navigationLocation = getHistoryEndPosition();
170     }
171 
172     private void trimHistory(Object   location) {
173         List   newHistory = history.subList(0, navigationLocation + 1);
174         history = new Vector  (newHistory);
175         history.add(new HistoryObject(location));
176         // point the nav location to the end of the vector.
177         navigationLocation = getHistoryEndPosition();
178     }
179 
180     /**
181      * Return the position of the last element in the navigation history. If
182      * vector is empty, return 0.
183      * 
184      * @param vector
185      * @return
186      */
187     private int getHistoryEndPosition() {
188         if (history.isEmpty())
189             return 0;
190         return history.size() - 1;
191     }
192 
193     public void navigateHistoryBackward() {
194         if (badNavigationLocation(navigationLocation - 1))
195             // do nothing. We are at the begining.
196             return;
197         --navigationLocation;
198     }
199 
200     /**
201      * Navigate forward in the history.
202      * 
203      * @return
204      */
205     public void navigateHistoryForward() {
206         if (badNavigationLocation(navigationLocation + 1))
207             // do nothing. We are at the begining.
208             return;
209         ++navigationLocation;
210     }
211 
212 
213     private boolean badNavigationLocation(int navigationLocation) {
214         if (navigationLocation < 0 || navigationLocation >= history.size())
215             // bad nav location.
216             return true;
217         return false;
218     }
219 
220 
221     /**
222      * Returns true if the current location in the navigation history represents
223      * a URL. False if the location is an Intro Page id.
224      * 
225      * @return Returns the locationIsURL.
226      */
227     private HistoryObject getCurrentLocation() {
228         return (HistoryObject) history.elementAt(navigationLocation);
229     }
230 
231     public boolean canNavigateForward() {
232         return navigationLocation != getHistoryEndPosition() ? true : false;
233     }
234 
235     public boolean canNavigateBackward() {
236         return navigationLocation == 0 ? false : true;
237     }
238 
239     public boolean currentLocationIsUrl() {
240         return getCurrentLocation().isURL();
241     }
242 
243     public String   getCurrentLocationAsUrl() {
244         return getCurrentLocation().getUrl();
245     }
246 
247     public AbstractIntroPage getCurrentLocationAsPage() {
248         return getCurrentLocation().getPage();
249     }
250 
251     public static boolean isURL(String   aString) {
252         IntroURLParser parser = new IntroURLParser(aString);
253         if (parser.hasProtocol())
254             return true;
255         return false;
256     }
257 
258 
259     public void clear() {
260         history.clear();
261         navigationLocation = 0;
262     }
263 
264 
265 
266 
267 }
268
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