net.sourceforge.phpeclipse.ui/src/net/sourceforge/phpdt/internal/ui/viewsupport/SelectionListenerWithASTManager.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 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 net.sourceforge.phpdt.internal.ui.viewsupport;
  12
  13 import java.util.HashMap;
  14 import java.util.Map;
  15
  16 import org.eclipse.core.runtime.IProgressMonitor;
  17 import org.eclipse.core.runtime.IStatus;
  18 import org.eclipse.core.runtime.NullProgressMonitor;
  19 import org.eclipse.core.runtime.OperationCanceledException;
  20 import org.eclipse.core.runtime.Status;
  21 import org.eclipse.core.runtime.jobs.Job;
  22 import org.eclipse.jface.text.ITextSelection;
  23 import org.eclipse.jface.util.ListenerList;
  24 import org.eclipse.jface.viewers.IPostSelectionProvider;
  25 import org.eclipse.jface.viewers.ISelection;
  26 import org.eclipse.jface.viewers.ISelectionChangedListener;
  27 import org.eclipse.jface.viewers.ISelectionProvider;
  28 import org.eclipse.jface.viewers.SelectionChangedEvent;
  29 import org.eclipse.ui.texteditor.ITextEditor;
  30
  31 /**
  32  * Infrastructure to share an AST for editor post selection listeners.
  33  */
  34 public class SelectionListenerWithASTManager {
  35
  36         private static SelectionListenerWithASTManager fgDefault;
  37
  38         /**
  39          * @return Returns the default manager instance.
  40          */
  41         public static SelectionListenerWithASTManager getDefault() {
  42                 if (fgDefault == null) {
  43                         fgDefault = new SelectionListenerWithASTManager();
  44                 }
  45                 return fgDefault;
  46         }
  47
  48         private final static class PartListenerGroup {
  49                 private ITextEditor fPart;
  50
  51                 private ISelectionChangedListener fSelectionListener,
  52                                 fPostSelectionListener;
  53
  54                 private Job fCurrentJob;
  55
  56                 private ListenerList fAstListeners;
  57
  58                 /**
  59                  * Lock to avoid having more than one calculateAndInform job in
  60                  * parallel. Only jobs may synchronize on this as otherwise deadlocks
  61                  * are possible.
  62                  */
  63                 private final Object fJobLock = new Object();
  64
  65                 public PartListenerGroup(ITextEditor part) {
  66                         fPart = part;
  67                         fCurrentJob = null;
  68                         fAstListeners = new ListenerList();
  69
  70                         fSelectionListener = new ISelectionChangedListener() {
  71                                 public void selectionChanged(SelectionChangedEvent event) {
  72                                         ISelection selection = event.getSelection();
  73                                         if (selection instanceof ITextSelection) {
  74                                                 fireSelectionChanged((ITextSelection) selection);
  75                                         }
  76                                 }
  77                         };
  78
  79                         fPostSelectionListener = new ISelectionChangedListener() {
  80                                 public void selectionChanged(SelectionChangedEvent event) {
  81                                         ISelection selection = event.getSelection();
  82                                         if (selection instanceof ITextSelection) {
  83                                                 firePostSelectionChanged((ITextSelection) selection);
  84                                         }
  85                                 }
  86                         };
  87                 }
  88
  89                 public boolean isEmpty() {
  90                         return fAstListeners.isEmpty();
  91                 }
  92
  93                 public void install(ISelectionListenerWithAST listener) {
  94                         if (isEmpty()) {
  95                                 ISelectionProvider selectionProvider = fPart
  96                                                 .getSelectionProvider();
  97                                 if (selectionProvider instanceof IPostSelectionProvider) {
  98                                         ((IPostSelectionProvider) selectionProvider)
  99                                                         .addPostSelectionChangedListener(fPostSelectionListener);
 100                                         selectionProvider
 101                                                         .addSelectionChangedListener(fSelectionListener);
 102                                 }
 103                         }
 104                         fAstListeners.add(listener);
 105                 }
 106
 107                 public void uninstall(ISelectionListenerWithAST listener) {
 108                         fAstListeners.remove(listener);
 109                         if (isEmpty()) {
 110                                 ISelectionProvider selectionProvider = fPart
 111                                                 .getSelectionProvider();
 112                                 if (selectionProvider instanceof IPostSelectionProvider) {
 113                                         ((IPostSelectionProvider) selectionProvider)
 114                                                         .removePostSelectionChangedListener(fPostSelectionListener);
 115                                         selectionProvider
 116                                                         .removeSelectionChangedListener(fSelectionListener);
 117                                 }
 118                         }
 119                 }
 120
 121                 public void fireSelectionChanged(final ITextSelection selection) {
 122                         if (fCurrentJob != null) {
 123                                 fCurrentJob.cancel();
 124                         }
 125                 }
 126
 127                 public void firePostSelectionChanged(final ITextSelection selection) {
 128                         if (fCurrentJob != null) {
 129                                 fCurrentJob.cancel();
 130                         }
 131
 132                         fCurrentJob = new Job("SelectionListenerWithASTManager Job") {// JavaUIMessages.SelectionListenerWithASTManager_job_title)
 133                                                                                                                                                         // {
 134                                 public IStatus run(IProgressMonitor monitor) {
 135                                         if (monitor == null) {
 136                                                 monitor = new NullProgressMonitor();
 137                                         }
 138                                         synchronized (fJobLock) {
 139                                                 return calculateASTandInform(/*input,*/ selection, monitor);
 140                                         }
 141                                 }
 142                         };
 143                         fCurrentJob.setPriority(Job.DECORATE);
 144                         fCurrentJob.setSystem(true);
 145                         fCurrentJob.schedule();
 146                 }
 147
 148                 protected IStatus calculateASTandInform(/*IJavaElement input,*/
 149                                 ITextSelection selection, IProgressMonitor monitor) {
 150                         if (monitor.isCanceled()) {
 151                                 return Status.CANCEL_STATUS;
 152                         }
 153                         // create AST
 154                         try {
 155                                 // CompilationUnit astRoot=
 156                                 // PHPeclipsePlugin.getDefault().getASTProvider().getAST(input,
 157                                 // ASTProvider.WAIT_ACTIVE_ONLY, monitor);
 158
 159                                 // if (astRoot != null && !monitor.isCanceled()) {
 160                                 Object[] listeners;
 161                                 synchronized (PartListenerGroup.this) {
 162                                         listeners = fAstListeners.getListeners();
 163                                 }
 164                                 for (int i = 0; i < listeners.length; i++) {
 165                                         ((ISelectionListenerWithAST) listeners[i])
 166                                                         .selectionChanged(fPart, selection);// , astRoot);
 167                                         if (monitor.isCanceled()) {
 168                                                 return Status.CANCEL_STATUS;
 169                                         }
 170                                 }
 171                                 return Status.OK_STATUS;
 172                                 // }
 173                         } catch (OperationCanceledException e) {
 174                                 // thrown when cancelling the AST creation
 175                         }
 176                         return Status.CANCEL_STATUS;
 177                 }
 178         }
 179
 180         private Map fListenerGroups;
 181
 182         private SelectionListenerWithASTManager() {
 183                 fListenerGroups = new HashMap();
 184         }
 185
 186         /**
 187          * Registers a selection listener for the given editor part.
 188          *
 189          * @param part
 190          *            The editor part to listen to.
 191          * @param listener
 192          *            The listener to register.
 193          */
 194         public void addListener(ITextEditor part, ISelectionListenerWithAST listener) {
 195                 synchronized (this) {
 196                         PartListenerGroup partListener = (PartListenerGroup) fListenerGroups
 197                                         .get(part);
 198                         if (partListener == null) {
 199                                 partListener = new PartListenerGroup(part);
 200                                 fListenerGroups.put(part, partListener);
 201                         }
 202                         partListener.install(listener);
 203                 }
 204         }
 205
 206         /**
 207          * Unregisters a selection listener.
 208          *
 209          * @param part
 210          *            The editor part the listener was registered.
 211          * @param listener
 212          *            The listener to unregister.
 213          */
 214         public void removeListener(ITextEditor part,
 215                         ISelectionListenerWithAST listener) {
 216                 synchronized (this) {
 217                         PartListenerGroup partListener = (PartListenerGroup) fListenerGroups
 218                                         .get(part);
 219                         if (partListener != null) {
 220                                 partListener.uninstall(listener);
 221                                 if (partListener.isEmpty()) {
 222                                         fListenerGroups.remove(part);
 223                                 }
 224                         }
 225                 }
 226         }
 227
 228         /**
 229          * Forces a selection changed event that is sent to all listeners registered
 230          * to the given editor part. The event is sent from a background thread:
 231          * this method call can return before the listeners are informed.
 232          *
 233          * @param part
 234          *            The editor part that has a changed selection
 235          * @param selection
 236          *            The new text selection
 237          */
 238         public void forceSelectionChange(ITextEditor part, ITextSelection selection) {
 239                 synchronized (this) {
 240                         PartListenerGroup partListener = (PartListenerGroup) fListenerGroups
 241                                         .get(part);
 242                         if (partListener != null) {
 243                                 partListener.firePostSelectionChanged(selection);
 244                         }
 245                 }
 246         }
 247 }