net.sourceforge.phpeclipse.ui/src/net/sourceforge/phpdt/internal/ui/text/SmartBackspaceManager.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2003 IBM Corporation and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v1.0
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v10.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - initial API and implementation
  10  *******************************************************************************/
  11 package net.sourceforge.phpdt.internal.ui.text;
  12
  13 import java.util.HashMap;
  14 import java.util.Iterator;
  15 import java.util.Map;
  16
  17 import net.sourceforge.phpdt.internal.ui.text.TypingRun.ChangeType;
  18
  19 import org.eclipse.jface.text.Assert;
  20 import org.eclipse.jface.text.BadLocationException;
  21 import org.eclipse.jface.text.IDocument;
  22 import org.eclipse.jface.text.IRegion;
  23 import org.eclipse.jface.text.ITextViewer;
  24 import org.eclipse.jface.text.ITextViewerExtension;
  25 import org.eclipse.jface.text.TextViewer;
  26 import org.eclipse.swt.SWT;
  27 import org.eclipse.swt.custom.VerifyKeyListener;
  28 import org.eclipse.swt.events.VerifyEvent;
  29 import org.eclipse.swt.graphics.Point;
  30 import org.eclipse.text.edits.MalformedTreeException;
  31 import org.eclipse.text.edits.TextEdit;
  32
  33 /**
  34  * Installs as a verify key listener on a viewer and overwrites the behaviour of
  35  * the backspace key. Clients may register undo specifications for certain
  36  * offsets in a document. The <code>SmartBackspaceManager</code> will manage
  37  * the specfications and execute the contained <code>TextEdit</code>s when
  38  * backspace is pressed at the given offset and the specification is still
  39  * valid.
  40  * <p>
  41  * Undo specifications are removed after a number of typing runs.
  42  * </p>
  43  *
  44  * @since 3.0
  45  */
  46 public class SmartBackspaceManager {
  47         /* independent of JDT - may be moved to jface.text */
  48
  49         /**
  50          * An undo specification describes the change that should be executed if
  51          * backspace is pressed at its trigger offset.
  52          *
  53          * @since 3.0
  54          */
  55         public static final class UndoSpec {
  56                 private final int triggerOffset;
  57
  58                 private final IRegion selection;
  59
  60                 private final TextEdit[] undoEdits;
  61
  62                 private final UndoSpec child;
  63
  64                 int lives;
  65
  66                 /**
  67                  * Creates a new spec. A specification consists of a number of
  68                  * <code>TextEdit</code> s that will be executed when backspace is
  69                  * pressed at <code>triggerOffset</code>. The spec will be removed
  70                  * when it is executed, or if more than <code>lives</code>
  71                  * <code>TypingRun</code>s
  72                  * have ended after registering the spec.
  73                  * <p>
  74                  * Optionally, a child specification can be registered. After executing
  75                  * the spec, the child spec will be registered with the manager. This
  76                  * allows to create chains of <code>UndoSpec</code>s that will be
  77                  * executed upon repeated pressing of backspace.
  78                  * </p>
  79                  *
  80                  * @param triggerOffset
  81                  *            the offset where this spec is active
  82                  * @param selection
  83                  *            the selection after executing the undo spec
  84                  * @param edits
  85                  *            the <code>TextEdit</code> s to perform when executing
  86                  *            the spec
  87                  * @param lives
  88                  *            the number of <code>TypingRun</code> s before removing
  89                  *            the spec
  90                  * @param child
  91                  *            a child specification that will be registered after
  92                  *            executing this spec, or <code>null</code>
  93                  */
  94                 public UndoSpec(int triggerOffset, IRegion selection, TextEdit[] edits,
  95                                 int lives, UndoSpec child) {
  96                         Assert.isLegal(triggerOffset >= 0);
  97                         Assert.isLegal(selection != null);
  98                         Assert.isLegal(lives >= 0);
  99                         Assert.isLegal(edits != null);
 100                         Assert.isLegal(edits.length > 0);
 101                         for (int i = 0; i < edits.length; i++) {
 102                                 Assert.isLegal(edits[i] != null);
 103                         }
 104
 105                         this.triggerOffset = triggerOffset;
 106                         this.selection = selection;
 107                         this.undoEdits = edits;
 108                         this.lives = lives;
 109                         this.child = child;
 110                 }
 111         }
 112
 113         private class BackspaceListener implements VerifyKeyListener {
 114
 115                 /*
 116                  * @see org.eclipse.swt.custom.VerifyKeyListener#verifyKey(org.eclipse.swt.events.VerifyEvent)
 117                  */
 118                 public void verifyKey(VerifyEvent event) {
 119                         if (fViewer != null && isBackspace(event)) {
 120                                 int offset = getCaretOffset();
 121                                 UndoSpec spec = removeEdit(offset);
 122                                 if (spec != null) {
 123                                         try {
 124                                                 beginChange();
 125                                                 for (int i = 0; i < spec.undoEdits.length; i++) {
 126                                                         spec.undoEdits[i].apply(getDocument(),
 127                                                                         TextEdit.UPDATE_REGIONS);
 128                                                 }
 129                                                 fViewer.setSelectedRange(spec.selection.getOffset(),
 130                                                                 spec.selection.getLength());
 131                                                 if (spec.child != null)
 132                                                         register(spec.child);
 133                                         } catch (MalformedTreeException e) {
 134                                                 // fall back to standard bs
 135                                                 return;
 136                                         } catch (BadLocationException e) {
 137                                                 // fall back to standard bs
 138                                                 return;
 139                                         } finally {
 140                                                 endChange();
 141                                         }
 142                                         event.doit = false;
 143                                 }
 144
 145                         }
 146                 }
 147
 148                 private void beginChange() {
 149                         ITextViewer viewer = fViewer;
 150                         if (viewer instanceof TextViewer) {
 151                                 TextViewer v = (TextViewer) viewer;
 152                                 v.getRewriteTarget().beginCompoundChange();
 153                                 v.setRedraw(false);
 154                         }
 155                 }
 156
 157                 private void endChange() {
 158                         ITextViewer viewer = fViewer;
 159                         if (viewer instanceof TextViewer) {
 160                                 TextViewer v = (TextViewer) viewer;
 161                                 v.getRewriteTarget().endCompoundChange();
 162                                 v.setRedraw(true);
 163                         }
 164                 }
 165
 166                 private boolean isBackspace(VerifyEvent event) {
 167                         return event.doit == true && event.character == SWT.BS
 168                                         && event.stateMask == 0;
 169                 }
 170
 171                 private int getCaretOffset() {
 172                         ITextViewer viewer = fViewer;
 173                         Point point = viewer.getSelectedRange();
 174                         return point.x;
 175                 }
 176
 177         }
 178
 179         private ITextViewer fViewer;
 180
 181         private BackspaceListener fBackspaceListener;
 182
 183         private Map fSpecs;
 184
 185         private TypingRunDetector fRunDetector;
 186
 187         private ITypingRunListener fRunListener;
 188
 189         /**
 190          * Registers an undo specification with this manager.
 191          *
 192          * @param spec
 193          *            the specification to register
 194          * @throws IllegalStateException
 195          *             if the manager is not installed
 196          */
 197         public void register(UndoSpec spec) {
 198                 if (fViewer == null)
 199                         throw new IllegalStateException();
 200
 201                 ensureListenerInstalled();
 202                 addEdit(spec);
 203         }
 204
 205         private void addEdit(UndoSpec spec) {
 206                 Integer i = new Integer(spec.triggerOffset);
 207                 fSpecs.put(i, spec);
 208         }
 209
 210         private UndoSpec removeEdit(int offset) {
 211                 Integer i = new Integer(offset);
 212                 UndoSpec spec = (UndoSpec) fSpecs.remove(i);
 213                 return spec;
 214         }
 215
 216         private void ensureListenerInstalled() {
 217                 if (fBackspaceListener == null) {
 218                         fBackspaceListener = new BackspaceListener();
 219                         ITextViewer viewer = fViewer;
 220                         if (viewer instanceof ITextViewerExtension)
 221                                 ((ITextViewerExtension) viewer)
 222                                                 .prependVerifyKeyListener(fBackspaceListener);
 223                         else
 224                                 viewer.getTextWidget().addVerifyKeyListener(fBackspaceListener);
 225                 }
 226         }
 227
 228         private void ensureListenerRemoved() {
 229                 if (fBackspaceListener != null) {
 230                         ITextViewer viewer = fViewer;
 231                         if (viewer instanceof ITextViewerExtension)
 232                                 ((ITextViewerExtension) viewer)
 233                                                 .removeVerifyKeyListener(fBackspaceListener);
 234                         else
 235                                 viewer.getTextWidget().removeVerifyKeyListener(
 236                                                 fBackspaceListener);
 237                         fBackspaceListener = null;
 238                 }
 239         }
 240
 241         private IDocument getDocument() {
 242                 return fViewer.getDocument();
 243         }
 244
 245         /**
 246          * Installs the receiver on a text viewer.
 247          *
 248          * @param viewer
 249          */
 250         public void install(ITextViewer viewer) {
 251                 Assert.isLegal(viewer != null);
 252
 253                 fViewer = viewer;
 254                 fSpecs = new HashMap();
 255                 fRunDetector = new TypingRunDetector();
 256                 fRunDetector.install(viewer);
 257                 fRunListener = new ITypingRunListener() {
 258
 259                         /*
 260                          * @see org.eclipse.jface.text.TypingRunDetector.ITypingRunListener#typingRunStarted(org.eclipse.jface.text.TypingRunDetector.TypingRun)
 261                          */
 262                         public void typingRunStarted(TypingRun run) {
 263                         }
 264
 265                         /*
 266                          * @see org.eclipse.jface.text.TypingRunDetector.ITypingRunListener#typingRunEnded(org.eclipse.jface.text.TypingRunDetector.TypingRun)
 267                          */
 268                         public void typingRunEnded(TypingRun run, ChangeType reason) {
 269                                 if (reason == TypingRun.SELECTION)
 270                                         fSpecs.clear();
 271                                 else
 272                                         prune();
 273                         }
 274                 };
 275                 fRunDetector.addTypingRunListener(fRunListener);
 276         }
 277
 278         private void prune() {
 279                 for (Iterator it = fSpecs.values().iterator(); it.hasNext();) {
 280                         UndoSpec spec = (UndoSpec) it.next();
 281                         if (--spec.lives < 0)
 282                                 it.remove();
 283                 }
 284         }
 285
 286         /**
 287          * Uninstalls the receiver. No undo specifications may be registered on an
 288          * uninstalled manager.
 289          */
 290         public void uninstall() {
 291                 if (fViewer != null) {
 292                         fRunDetector.removeTypingRunListener(fRunListener);
 293                         fRunDetector.uninstall();
 294                         fRunDetector = null;
 295                         ensureListenerRemoved();
 296                         fViewer = null;
 297                 }
 298         }
 299 }