TypingRunDetector observes
* TypingRun events. A typing run is a sequence of similar text
* modifications, such as inserting or deleting single characters.
*
* Listeners are informed about the start and end of a TypingRun.
*
type.
*
* @param type
* the ChangeType of the new change
* @param nextOffset
* the offset of the next change in a typing run
*/
public Change(ChangeType type, int nextOffset) {
fType = type;
fNextOffset = nextOffset;
}
/**
* Returns true if the receiver can extend the typing
* range the last change of which is described by change.
*
* @param change
* the last change in a typing run
* @return true if the receiver is a valid extension to
* change,false otherwise
*/
public boolean canFollow(Change change) {
if (fType == TypingRun.NO_CHANGE)
return true;
else if (fType.equals(TypingRun.UNKNOWN))
return false;
if (fType.equals(change.fType)) {
if (fType == TypingRun.DELETE)
return fNextOffset == change.fNextOffset - 1;
else if (fType == TypingRun.INSERT)
return fNextOffset == change.fNextOffset + 1;
else if (fType == TypingRun.OVERTYPE)
return fNextOffset == change.fNextOffset + 1;
else if (fType == TypingRun.SELECTION)
return true;
}
return false;
}
/**
* Returns true if the receiver describes a text
* modification, false if it describes a focus /
* selection change.
*
* @return true if the receiver is a text modification
*/
public boolean isModification() {
return fType.isModification();
}
/*
* @see java.lang.Object#toString()
*/
public String toString() {
return fType.toString() + "@" + fNextOffset; //$NON-NLS-1$
}
/**
* Returns the change type of this change.
*
* @return the change type of this change
*/
public ChangeType getType() {
return fType;
}
}
/**
* Observes any events that modify the content of the document displayed in
* the editor. Since text events may start a new run, this listener is
* always registered if the detector is connected.
*/
private class TextListener implements ITextListener {
/*
* @see org.eclipse.jface.text.ITextListener#textChanged(org.eclipse.jface.text.TextEvent)
*/
public void textChanged(TextEvent event) {
handleTextChanged(event);
}
}
/**
* Observes non-modifying events that will end a run, such as clicking into
* the editor, moving the caret, and the editor losing focus. These events
* can never start a run, therefore this listener is only registered if
* there is an ongoing run.
*/
private class SelectionListener implements MouseListener, KeyListener,
FocusListener {
/*
* @see org.eclipse.swt.events.FocusListener#focusGained(org.eclipse.swt.events.FocusEvent)
*/
public void focusGained(FocusEvent e) {
handleSelectionChanged();
}
/*
* @see org.eclipse.swt.events.FocusListener#focusLost(org.eclipse.swt.events.FocusEvent)
*/
public void focusLost(FocusEvent e) {
}
/*
* @see MouseListener#mouseDoubleClick
*/
public void mouseDoubleClick(MouseEvent e) {
}
/*
* If the right mouse button is pressed, the current editing command is
* closed
*
* @see MouseListener#mouseDown
*/
public void mouseDown(MouseEvent e) {
if (e.button == 1)
handleSelectionChanged();
}
/*
* @see MouseListener#mouseUp
*/
public void mouseUp(MouseEvent e) {
}
/*
* @see KeyListener#keyPressed
*/
public void keyReleased(KeyEvent e) {
}
/*
* On cursor keys, the current editing command is closed
*
* @see KeyListener#keyPressed
*/
public void keyPressed(KeyEvent e) {
switch (e.keyCode) {
case SWT.ARROW_UP:
case SWT.ARROW_DOWN:
case SWT.ARROW_LEFT:
case SWT.ARROW_RIGHT:
case SWT.END:
case SWT.HOME:
case SWT.PAGE_DOWN:
case SWT.PAGE_UP:
handleSelectionChanged();
break;
}
}
}
/** The listeners. */
private final Set fListeners = new HashSet();
/**
* The viewer we work upon. Set to null in
* uninstall.
*/
private ITextViewer fViewer;
/** The text event listener. */
private final TextListener fTextListener = new TextListener();
/**
* The selection listener. Set to null when no run is active.
*/
private SelectionListener fSelectionListener;
/* state variables */
/** The most recently observed change. Never null. */
private Change fLastChange;
/** The current run, or null if there is none. */
private TypingRun fRun;
/**
* Installs the receiver with a text viewer.
*
* @param viewer
* the viewer to install on
*/
public void install(ITextViewer viewer) {
Assert.isLegal(viewer != null);
fViewer = viewer;
connect();
}
/**
* Initializes the state variables and registers any permanent listeners.
*/
private void connect() {
if (fViewer != null) {
fLastChange = new Change(TypingRun.UNKNOWN, -1);
fRun = null;
fSelectionListener = null;
fViewer.addTextListener(fTextListener);
}
}
/**
* Uninstalls the receiver and removes all listeners. install()
* must be called for events to be generated.
*/
public void uninstall() {
if (fViewer != null) {
fListeners.clear();
disconnect();
fViewer = null;
}
}
/**
* Disconnects any registered listeners.
*/
private void disconnect() {
fViewer.removeTextListener(fTextListener);
ensureSelectionListenerRemoved();
}
/**
* Adds a listener for TypingRun events. Repeatedly adding
* the same listener instance has no effect. Listeners may be added even if
* the receiver is neither connected nor installed.
*
* @param listener
* the listener add
*/
public void addTypingRunListener(ITypingRunListener listener) {
Assert.isLegal(listener != null);
fListeners.add(listener);
if (fListeners.size() == 1)
connect();
}
/**
* Removes the listener from this manager. If listener is not
* registered with the receiver, nothing happens.
*
* @param listener
* the listener to remove, or null
*/
public void removeTypingRunListener(ITypingRunListener listener) {
fListeners.remove(listener);
if (fListeners.size() == 0)
disconnect();
}
/**
* Handles an incoming text event.
*
* @param event
* the text event that describes the text modification
*/
void handleTextChanged(TextEvent event) {
Change type = computeChange(event);
handleChange(type);
}
/**
* Computes the change abstraction given a text event.
*
* @param event
* the text event to analyze
* @return a change object describing the event
*/
private Change computeChange(TextEvent event) {
DocumentEvent e = event.getDocumentEvent();
if (e == null)
return new Change(TypingRun.NO_CHANGE, -1);
int start = e.getOffset();
int end = e.getOffset() + e.getLength();
String newText = e.getText();
if (newText == null)
newText = new String();
if (start == end) {
// no replace / delete / overwrite
if (newText.length() == 1)
return new Change(TypingRun.INSERT, end + 1);
} else if (start == end - 1) {
if (newText.length() == 1)
return new Change(TypingRun.OVERTYPE, end);
if (newText.length() == 0)
return new Change(TypingRun.DELETE, start);
}
return new Change(TypingRun.UNKNOWN, -1);
}
/**
* Handles an incoming selection event.
*/
void handleSelectionChanged() {
handleChange(new Change(TypingRun.SELECTION, -1));
}
/**
* State machine. Changes state given the current state and the incoming
* change.
*
* @param change
* the incoming change
*/
private void handleChange(Change change) {
if (change.getType() == TypingRun.NO_CHANGE)
return;
if (DEBUG)
System.err.println("Last change: " + fLastChange); //$NON-NLS-1$
if (!change.canFollow(fLastChange))
endIfStarted(change);
fLastChange = change;
if (change.isModification())
startOrContinue();
if (DEBUG)
System.err.println("New change: " + change); //$NON-NLS-1$
}
/**
* Starts a new run if there is none and informs all listeners. If there
* already is a run, nothing happens.
*/
private void startOrContinue() {
if (!hasRun()) {
if (DEBUG)
System.err.println("+Start run"); //$NON-NLS-1$
fRun = new TypingRun(fLastChange.getType());
ensureSelectionListenerAdded();
fireRunBegun(fRun);
}
}
/**
* Returns true if there is an active run, false
* otherwise.
*
* @return true if there is an active run, false
* otherwise
*/
private boolean hasRun() {
return fRun != null;
}
/**
* Ends any active run and informs all listeners. If there is none, nothing
* happens.
*
* @param change
* the change that triggered ending the active run
*/
private void endIfStarted(Change change) {
if (hasRun()) {
ensureSelectionListenerRemoved();
if (DEBUG)
System.err.println("-End run"); //$NON-NLS-1$
fireRunEnded(fRun, change.getType());
fRun = null;
}
}
/**
* Adds the selection listener to the text widget underlying the viewer, if
* not already done.
*/
private void ensureSelectionListenerAdded() {
if (fSelectionListener == null) {
fSelectionListener = new SelectionListener();
StyledText textWidget = fViewer.getTextWidget();
textWidget.addFocusListener(fSelectionListener);
textWidget.addKeyListener(fSelectionListener);
textWidget.addMouseListener(fSelectionListener);
}
}
/**
* If there is a selection listener, it is removed from the text widget
* underlying the viewer.
*/
private void ensureSelectionListenerRemoved() {
if (fSelectionListener != null) {
StyledText textWidget = fViewer.getTextWidget();
textWidget.removeFocusListener(fSelectionListener);
textWidget.removeKeyListener(fSelectionListener);
textWidget.removeMouseListener(fSelectionListener);
fSelectionListener = null;
}
}
/**
* Informs all listeners about a newly started TypingRun.
*
* @param run
* the new run
*/
private void fireRunBegun(TypingRun run) {
List listeners = new ArrayList(fListeners);
for (Iterator it = listeners.iterator(); it.hasNext();) {
ITypingRunListener listener = (ITypingRunListener) it.next();
listener.typingRunStarted(fRun);
}
}
/**
* Informs all listeners about an ended TypingRun.
*
* @param run
* the previously active run
* @param reason
* the type of change that caused the run to be ended
*/
private void fireRunEnded(TypingRun run, ChangeType reason) {
List listeners = new ArrayList(fListeners);
for (Iterator it = listeners.iterator(); it.hasNext();) {
ITypingRunListener listener = (ITypingRunListener) it.next();
listener.typingRunEnded(fRun, reason);
}
}
}