/*******************************************************************************
* Copyright (c) 2000, 2008 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.wst.jsdt.internal.ui.text;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.text.DocumentEvent;
import org.eclipse.jface.text.ITextListener;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.TextEvent;
import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.StyledText;
import org.eclipse.swt.events.FocusEvent;
import org.eclipse.swt.events.FocusListener;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.events.KeyListener;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.events.MouseListener;
import org.eclipse.wst.jsdt.internal.ui.text.TypingRun.ChangeType;
/**
* When connected to a text viewer, a <code>TypingRunDetector</code> observes
* <code>TypingRun</code> events. A typing run is a sequence of similar text
* modifications, such as inserting or deleting single characters.
* <p>
* Listeners are informed about the start and end of a <code>TypingRun</code>.
* </p>
*
*
*/
public class TypingRunDetector {
/*
* Implementation note: This class is independent of JDT and may be pulled
* up to jface.text if needed.
*/
/** Debug flag. */
private static final boolean DEBUG= false;
/**
* Instances of this class abstract a text modification into a simple
* description. Typing runs consists of a sequence of one or more modifying
* changes of the same type. Every change records the type of change
* described by a text modification, and an offset it can be followed by
* another change of the same run.
*/
private static final class Change {
private ChangeType fType;
private int fNextOffset;
/**
* Creates a new change of type <code>type</code>.
*
* @param type the <code>ChangeType</code> 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 <code>true</code> if the receiver can extend the typing run
* the last change of which is described by <code>change</code>.
*
* @param change the last change in a typing run
* @return <code>true</code> if the receiver is a valid extension to
* <code>change</code>, <code>false</code> otherwise
*/
public boolean canFollow(Change change) {
if (fType == TypingRun.NO_CHANGE)
return true;
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 <code>true</code> if the receiver describes a text
* modification, <code>false</code> if it describes a focus /
* selection change.
*
* @return <code>true</code> 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 <code>null</code> in
* <code>uninstall</code>.
*/
private ITextViewer fViewer;
/** The text event listener. */
private final TextListener fTextListener= new TextListener();
/**
* The selection listener. Set to <code>null</code> when no run is active.
*/
private SelectionListener fSelectionListener;
/* state variables */
/** The most recently observed change. Never <code>null</code>. */
private Change fLastChange;
/** The current run, or <code>null</code> 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. <code>install()</code>
* 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 <code>TypingRun</code> 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 <code>listener</code> is not
* registered with the receiver, nothing happens.
*
* @param listener the listener to remove, or <code>null</code>
*/
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 <code>true</code> if there is an active run, <code>false</code>
* otherwise.
*
* @return <code>true</code> if there is an active run, <code>false</code>
* 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 <code>TypingRun</code>.
*
* @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 <code>TypingRun</code>.
*
* @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);
}
}
}