SmartBackspaceManager will manage
+ * the specfications and execute the contained TextEdits when
+ * backspace is pressed at the given offset and the specification is still
+ * valid.
+ * + * Undo specifications are removed after a number of typing runs. + *
+ * + * @since 3.0 + */ +public class SmartBackspaceManager { + /* independent of JDT - may be moved to jface.text */ + + /** + * An undo specification describes the change that should be executed if + * backspace is pressed at its trigger offset. + * + * @since 3.0 + */ + public static final class UndoSpec { + private final int triggerOffset; + + private final IRegion selection; + + private final TextEdit[] undoEdits; + + private final UndoSpec child; + + int lives; + + /** + * Creates a new spec. A specification consists of a number of + *TextEdit s that will be executed when backspace is
+ * pressed at triggerOffset. The spec will be removed
+ * when it is executed, or if more than lives
+ * TypingRuns
+ * have ended after registering the spec.
+ *
+ * Optionally, a child specification can be registered. After executing
+ * the spec, the child spec will be registered with the manager. This
+ * allows to create chains of UndoSpecs that will be
+ * executed upon repeated pressing of backspace.
+ *
TextEdit s to perform when executing
+ * the spec
+ * @param lives
+ * the number of TypingRun s before removing
+ * the spec
+ * @param child
+ * a child specification that will be registered after
+ * executing this spec, or null
+ */
+ public UndoSpec(int triggerOffset, IRegion selection, TextEdit[] edits,
+ int lives, UndoSpec child) {
+ Assert.isLegal(triggerOffset >= 0);
+ Assert.isLegal(selection != null);
+ Assert.isLegal(lives >= 0);
+ Assert.isLegal(edits != null);
+ Assert.isLegal(edits.length > 0);
+ for (int i = 0; i < edits.length; i++) {
+ Assert.isLegal(edits[i] != null);
+ }
+
+ this.triggerOffset = triggerOffset;
+ this.selection = selection;
+ this.undoEdits = edits;
+ this.lives = lives;
+ this.child = child;
+ }
+ }
+
+ private class BackspaceListener implements VerifyKeyListener {
+
+ /*
+ * @see org.eclipse.swt.custom.VerifyKeyListener#verifyKey(org.eclipse.swt.events.VerifyEvent)
+ */
+ public void verifyKey(VerifyEvent event) {
+ if (fViewer != null && isBackspace(event)) {
+ int offset = getCaretOffset();
+ UndoSpec spec = removeEdit(offset);
+ if (spec != null) {
+ try {
+ beginChange();
+ for (int i = 0; i < spec.undoEdits.length; i++) {
+ spec.undoEdits[i].apply(getDocument(),
+ TextEdit.UPDATE_REGIONS);
+ }
+ fViewer.setSelectedRange(spec.selection.getOffset(),
+ spec.selection.getLength());
+ if (spec.child != null)
+ register(spec.child);
+ } catch (MalformedTreeException e) {
+ // fall back to standard bs
+ return;
+ } catch (BadLocationException e) {
+ // fall back to standard bs
+ return;
+ } finally {
+ endChange();
+ }
+ event.doit = false;
+ }
+
+ }
+ }
+
+ private void beginChange() {
+ ITextViewer viewer = fViewer;
+ if (viewer instanceof TextViewer) {
+ TextViewer v = (TextViewer) viewer;
+ v.getRewriteTarget().beginCompoundChange();
+ v.setRedraw(false);
+ }
+ }
+
+ private void endChange() {
+ ITextViewer viewer = fViewer;
+ if (viewer instanceof TextViewer) {
+ TextViewer v = (TextViewer) viewer;
+ v.getRewriteTarget().endCompoundChange();
+ v.setRedraw(true);
+ }
+ }
+
+ private boolean isBackspace(VerifyEvent event) {
+ return event.doit == true && event.character == SWT.BS
+ && event.stateMask == 0;
+ }
+
+ private int getCaretOffset() {
+ ITextViewer viewer = fViewer;
+ Point point = viewer.getSelectedRange();
+ return point.x;
+ }
+
+ }
+
+ private ITextViewer fViewer;
+
+ private BackspaceListener fBackspaceListener;
+
+ private Map fSpecs;
+
+ private TypingRunDetector fRunDetector;
+
+ private ITypingRunListener fRunListener;
+
+ /**
+ * Registers an undo specification with this manager.
+ *
+ * @param spec
+ * the specification to register
+ * @throws IllegalStateException
+ * if the manager is not installed
+ */
+ public void register(UndoSpec spec) {
+ if (fViewer == null)
+ throw new IllegalStateException();
+
+ ensureListenerInstalled();
+ addEdit(spec);
+ }
+
+ private void addEdit(UndoSpec spec) {
+ Integer i = new Integer(spec.triggerOffset);
+ fSpecs.put(i, spec);
+ }
+
+ private UndoSpec removeEdit(int offset) {
+ Integer i = new Integer(offset);
+ UndoSpec spec = (UndoSpec) fSpecs.remove(i);
+ return spec;
+ }
+
+ private void ensureListenerInstalled() {
+ if (fBackspaceListener == null) {
+ fBackspaceListener = new BackspaceListener();
+ ITextViewer viewer = fViewer;
+ if (viewer instanceof ITextViewerExtension)
+ ((ITextViewerExtension) viewer)
+ .prependVerifyKeyListener(fBackspaceListener);
+ else
+ viewer.getTextWidget().addVerifyKeyListener(fBackspaceListener);
+ }
+ }
+
+ private void ensureListenerRemoved() {
+ if (fBackspaceListener != null) {
+ ITextViewer viewer = fViewer;
+ if (viewer instanceof ITextViewerExtension)
+ ((ITextViewerExtension) viewer)
+ .removeVerifyKeyListener(fBackspaceListener);
+ else
+ viewer.getTextWidget().removeVerifyKeyListener(
+ fBackspaceListener);
+ fBackspaceListener = null;
+ }
+ }
+
+ private IDocument getDocument() {
+ return fViewer.getDocument();
+ }
+
+ /**
+ * Installs the receiver on a text viewer.
+ *
+ * @param viewer
+ */
+ public void install(ITextViewer viewer) {
+ Assert.isLegal(viewer != null);
+
+ fViewer = viewer;
+ fSpecs = new HashMap();
+ fRunDetector = new TypingRunDetector();
+ fRunDetector.install(viewer);
+ fRunListener = new ITypingRunListener() {
+
+ /*
+ * @see org.eclipse.jface.text.TypingRunDetector.ITypingRunListener#typingRunStarted(org.eclipse.jface.text.TypingRunDetector.TypingRun)
+ */
+ public void typingRunStarted(TypingRun run) {
+ }
+
+ /*
+ * @see org.eclipse.jface.text.TypingRunDetector.ITypingRunListener#typingRunEnded(org.eclipse.jface.text.TypingRunDetector.TypingRun)
+ */
+ public void typingRunEnded(TypingRun run, ChangeType reason) {
+ if (reason == TypingRun.SELECTION)
+ fSpecs.clear();
+ else
+ prune();
+ }
+ };
+ fRunDetector.addTypingRunListener(fRunListener);
+ }
+
+ private void prune() {
+ for (Iterator it = fSpecs.values().iterator(); it.hasNext();) {
+ UndoSpec spec = (UndoSpec) it.next();
+ if (--spec.lives < 0)
+ it.remove();
+ }
+ }
+
+ /**
+ * Uninstalls the receiver. No undo specifications may be registered on an
+ * uninstalled manager.
+ */
+ public void uninstall() {
+ if (fViewer != null) {
+ fRunDetector.removeTypingRunListener(fRunListener);
+ fRunDetector.uninstall();
+ fRunDetector = null;
+ ensureListenerRemoved();
+ fViewer = null;
+ }
+ }
+}