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;
}
}
}