org.eclipse.jface.text/src/org/eclipse/jface/text/contentassist/ContentAssistant.java

/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.jface.text.contentassist;


import java.util.HashMap;
import java.util.Map;

import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTError;
import org.eclipse.swt.custom.VerifyKeyListener;
import org.eclipse.swt.events.ControlEvent;
import org.eclipse.swt.events.ControlListener;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.events.FocusEvent;
import org.eclipse.swt.events.FocusListener;
import org.eclipse.swt.events.KeyAdapter;
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.swt.events.VerifyEvent;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Widget;

import org.eclipse.jface.contentassist.*;
import org.eclipse.jface.dialogs.IDialogSettings;

import org.eclipse.jface.text.Assert;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IDocumentExtension3;
import org.eclipse.jface.text.IEventConsumer;
import org.eclipse.jface.text.IInformationControlCreator;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.IViewportListener;
import org.eclipse.jface.text.IWidgetTokenKeeper;
import org.eclipse.jface.text.IWidgetTokenKeeperExtension;
import org.eclipse.jface.text.IWidgetTokenOwner;
import org.eclipse.jface.text.IWidgetTokenOwnerExtension;
import org.eclipse.jface.text.TextUtilities;



/**
 * The standard implementation of the <code>IContentAssistant</code> interface.
 * Usually, clients instantiate this class and configure it before using it.
 */
public class ContentAssistant implements IContentAssistant, IContentAssistantExtension, IWidgetTokenKeeper, IWidgetTokenKeeperExtension {
	
	/**
	 * A generic closer class used to monitor various 
	 * interface events in order to determine whether
	 * content-assist should be terminated and all
	 * associated windows closed.
	 */
	class Closer implements ControlListener, MouseListener, FocusListener, DisposeListener, IViewportListener {

		/** The shell that a <code>ControlListener</code> is registered with. */
		private Control fShell;
		/** The control that a <code>MouseListener</code>, a<code>FocusListener</code> and a <code>DisposeListener</code> are registered with. */
		private Control fControl;
		
		/**
		 * Installs this closer on it's viewer's text widget.
		 */
		protected void install() {
			Control control= fContentAssistSubjectControlAdapter.getControl();
			fControl= control;
			if (Helper.okToUse(control)) {
				
				Control shell= control.getShell();
				fShell= shell;
				shell.addControlListener(this);
					
				control.addMouseListener(this);
				control.addFocusListener(this);
				
				/*
				 * 1GGYYWK: ITPJUI:ALL - Dismissing editor with code assist up causes lots of Internal Errors
				 */
				control.addDisposeListener(this);
			}
			if (fViewer != null)
				fViewer.addViewportListener(this);
		}
		
		/**
		 * Uninstalls this closer from the viewer's text widget.
		 */
		protected void uninstall() {
			Control shell= fShell;
			fShell= null;
			if (Helper.okToUse(shell))
				shell.removeControlListener(this);
			
			Control control= fControl;
			fControl= null;
			if (Helper.okToUse(control)) {
				
				control.removeMouseListener(this);
				control.removeFocusListener(this);
				
				/*
				 * 1GGYYWK: ITPJUI:ALL - Dismissing editor with code assist up causes lots of Internal Errors
				 */
				control.removeDisposeListener(this);
			}
			
			if (fViewer != null)
				fViewer.removeViewportListener(this);
		}

		/*
		 * @see ControlListener#controlResized(ControlEvent)
		 */
		public void controlResized(ControlEvent e) {
			hide();
		}

		/*
		 * @see ControlListener#controlMoved(ControlEvent)
		 */
		public void controlMoved(ControlEvent e) {
			hide();
		}

		/*
		 * @see MouseListener#mouseDown(MouseEvent)
		 */
		public void mouseDown(MouseEvent e) {
			hide();
		}

		/*
		 * @see MouseListener#mouseUp(MouseEvent)
		 */
		public void mouseUp(MouseEvent e) {
		}

		/*
		 * @see MouseListener#mouseDoubleClick(MouseEvent)
		 */
		public void mouseDoubleClick(MouseEvent e) {
			hide();
		}

		/* 
		 * @see FocusListener#focusGained(FocusEvent)
		 */
		public void focusGained(FocusEvent e) {
		}

		/*
		 * @see FocusListener#focusLost(FocusEvent)
		 */
		public void focusLost(FocusEvent e) {
			Control control= fControl;
			if (Helper.okToUse(control)) {
				Display d= control.getDisplay();
				if (d != null) {
					d.asyncExec(new Runnable() {
						public void run() {
							if (!fProposalPopup.hasFocus() && (fContextInfoPopup == null || !fContextInfoPopup.hasFocus()))
								hide();
						}
					});
				}
			}
		}
		
		/*
		 * @seeDisposeListener#widgetDisposed(DisposeEvent)
		 */
		public void widgetDisposed(DisposeEvent e) {
			/*
			 * 1GGYYWK: ITPJUI:ALL - Dismissing editor with code assist up causes lots of Internal Errors
			 */
			hide();
		}

		/*
		 * @see IViewportListener#viewportChanged(int)
		 */
		public void viewportChanged(int topIndex) {
			hide();
		}
	}
	
	/**
	 * An implementation of <code>IContentAssistListener</code>, this class is
	 * used to monitor key events in support of automatic activation
	 * of the content assistant. If enabled, the implementation utilizes a
	 * thread to watch for input characters matching the activation
	 * characters specified by the content assist processor, and if
	 * detected, will wait the indicated delay interval before
	 * activating the content assistant.
	 */
	class AutoAssistListener extends KeyAdapter implements KeyListener, Runnable, VerifyKeyListener {
		
		private Thread fThread;
		private boolean fIsReset= false;
		private Object fMutex= new Object();
		private int fShowStyle;
		
		private final static int SHOW_PROPOSALS= 1;
		private final static int SHOW_CONTEXT_INFO= 2;
		
		protected AutoAssistListener() {
		}

		protected void start(int showStyle) {
			fShowStyle= showStyle;
			fThread= new Thread(this, JFaceTextMessages.getString("ContentAssistant.assist_delay_timer_name")); //$NON-NLS-1$
			fThread.start();
		}

		public void run() {
			try {
				while (true) {
					synchronized (fMutex) {
						if (fAutoActivationDelay != 0)
							fMutex.wait(fAutoActivationDelay);
						if (fIsReset) {
							fIsReset= false;
							continue;
						}
					}
					showAssist(fShowStyle);
					break;
				}
			} catch (InterruptedException e) {
			}
			fThread= null;
		}
		
		protected void reset(int showStyle) {
			synchronized (fMutex) {
				fShowStyle= showStyle;
				fIsReset= true;
				fMutex.notifyAll();
			}
		}

		protected void stop() {
			if (fThread != null) {
				fThread.interrupt();
			}
		}
		
		private boolean contains(char[] characters, char character) {
			if (characters != null) {
				for (int i= 0; i < characters.length; i++) {
					if (character == characters[i])
						return true;
				}
			}
			return false;
		}
		
		public void keyPressed(KeyEvent e) {
			// Only act on typed characters and ignore modifier-only events
			if (e.character == 0 && (e.keyCode & SWT.KEYCODE_BIT) == 0)
				return;

			int showStyle;
			int pos= fContentAssistSubjectControlAdapter.getSelectedRange().x;
			char[] activation;
			
			activation= fContentAssistSubjectControlAdapter.getCompletionProposalAutoActivationCharacters(ContentAssistant.this, pos);
			
			if (contains(activation, e.character) && !fProposalPopup.isActive())
				showStyle= SHOW_PROPOSALS;
			else {
				activation= fContentAssistSubjectControlAdapter.getContextInformationAutoActivationCharacters(ContentAssistant.this, pos);
				if (contains(activation, e.character) && fContextInfoPopup != null && !fContextInfoPopup.isActive())
					showStyle= SHOW_CONTEXT_INFO;
				else {
					if (fThread != null && fThread.isAlive())
						stop();
					return;
				}
			}
			
			if (fThread != null && fThread.isAlive())
				reset(showStyle);
			else
				start(showStyle);
		}

		/*
		 * @see org.eclipse.swt.custom.VerifyKeyListener#verifyKey(org.eclipse.swt.events.VerifyEvent)
		 */
		public void verifyKey(VerifyEvent event) {
			keyPressed(event);
		}
		
		protected void showAssist(final int showStyle) {
			Display d= fContentAssistSubjectControlAdapter.getControl().getDisplay();
			if (d != null) {
				try {
					d.syncExec(new Runnable() {
						public void run() {
							if (showStyle == SHOW_PROPOSALS)
								fProposalPopup.showProposals(true);
							else if (showStyle == SHOW_CONTEXT_INFO && fContextInfoPopup != null)
								fContextInfoPopup.showContextProposals(true);
						}
					});
				} catch (SWTError e) {
				}
			}
		}
	}
	
	/**
	 * The layout manager layouts the various
	 * windows associated with the content assistant based on the
	 * settings of the content assistant.
	 */
	class LayoutManager implements Listener {
		
		// Presentation types.
		/** The presentation type for the proposal selection popup. */
		public final static int LAYOUT_PROPOSAL_SELECTOR= 0;
		/** The presentation type for the context selection popup. */
		public final static int LAYOUT_CONTEXT_SELECTOR= 1;
		/** The presentation type for the context information hover .*/
		public final static int LAYOUT_CONTEXT_INFO_POPUP= 2;

		int fContextType= LAYOUT_CONTEXT_SELECTOR;
		Shell[] fShells= new Shell[3];
		Object[] fPopups= new Object[3];

		protected void add(Object popup, Shell shell, int type, int offset) {
			Assert.isNotNull(popup);
			Assert.isTrue(shell != null && !shell.isDisposed());
			checkType(type);
			
			if (fShells[type] != shell) {
				if (fShells[type] != null)
					fShells[type].removeListener(SWT.Dispose, this);
				shell.addListener(SWT.Dispose, this);
				fShells[type]= shell;
			}
			
			fPopups[type]= popup;
			if (type == LAYOUT_CONTEXT_SELECTOR || type == LAYOUT_CONTEXT_INFO_POPUP)
				fContextType= type;
			
			layout(type, offset);
			adjustListeners(type);
		}
	
		protected void checkType(int type) {
			Assert.isTrue(type == LAYOUT_PROPOSAL_SELECTOR ||
				type == LAYOUT_CONTEXT_SELECTOR || type == LAYOUT_CONTEXT_INFO_POPUP);
		}
		
		public void handleEvent(Event event) {
			Widget source= event.widget;
			source.removeListener(SWT.Dispose, this);
			
			int type= getShellType(source);
			checkType(type);
			fShells[type]= null;
						
			switch (type) {
				case LAYOUT_PROPOSAL_SELECTOR:
					if (fContextType == LAYOUT_CONTEXT_SELECTOR &&
							Helper.okToUse(fShells[LAYOUT_CONTEXT_SELECTOR])) {
						// Restore event notification to the tip popup.
						addContentAssistListener((IContentAssistListener) fPopups[LAYOUT_CONTEXT_SELECTOR], CONTEXT_SELECTOR);						
					}
					break;
				
				case LAYOUT_CONTEXT_SELECTOR:
					if (Helper.okToUse(fShells[LAYOUT_PROPOSAL_SELECTOR])) {
						if (fProposalPopupOrientation == PROPOSAL_STACKED)
							layout(LAYOUT_PROPOSAL_SELECTOR, getSelectionOffset());
						// Restore event notification to the proposal popup.
						addContentAssistListener((IContentAssistListener) fPopups[LAYOUT_PROPOSAL_SELECTOR], PROPOSAL_SELECTOR);						
					}
					fContextType= LAYOUT_CONTEXT_INFO_POPUP;
					break;
				
				case LAYOUT_CONTEXT_INFO_POPUP:
					if (Helper.okToUse(fShells[LAYOUT_PROPOSAL_SELECTOR])) {
						if (fContextInfoPopupOrientation == CONTEXT_INFO_BELOW)
							layout(LAYOUT_PROPOSAL_SELECTOR, getSelectionOffset());
					}
					fContextType= LAYOUT_CONTEXT_SELECTOR;
					break;
			}
		}
		
		protected int getShellType(Widget shell) {
			for (int i=0; i<fShells.length; i++) {
				if (fShells[i] == shell)
					return i;
			}
			return -1;
		}
		
		protected void layout(int type, int offset) {
			switch (type) {
				case LAYOUT_PROPOSAL_SELECTOR:
					layoutProposalSelector(offset);
					break;
				case LAYOUT_CONTEXT_SELECTOR:
					layoutContextSelector(offset);
					break;
				case LAYOUT_CONTEXT_INFO_POPUP:
					layoutContextInfoPopup(offset);
					break;
			}
		}

		protected void layoutProposalSelector(int offset) {
			if (fContextType == LAYOUT_CONTEXT_INFO_POPUP &&
					fContextInfoPopupOrientation == CONTEXT_INFO_BELOW &&
					Helper.okToUse(fShells[LAYOUT_CONTEXT_INFO_POPUP])) {
				// Stack proposal selector beneath the tip box.
				Shell shell= fShells[LAYOUT_PROPOSAL_SELECTOR];
				Shell parent= fShells[LAYOUT_CONTEXT_INFO_POPUP];
				shell.setLocation(getStackedLocation(shell, parent));
			} else if (fContextType != LAYOUT_CONTEXT_SELECTOR ||
						!Helper.okToUse(fShells[LAYOUT_CONTEXT_SELECTOR])) {
				// There are no other presentations to be concerned with,
				// so place the proposal selector beneath the cursor line.
				Shell shell= fShells[LAYOUT_PROPOSAL_SELECTOR];
				shell.setLocation(getBelowLocation(shell, offset));
			} else {
				switch (fProposalPopupOrientation) {
					case PROPOSAL_REMOVE: {
						// Remove the tip selector and place the
						// proposal selector beneath the cursor line.
						fShells[LAYOUT_CONTEXT_SELECTOR].dispose();
						Shell shell= fShells[LAYOUT_PROPOSAL_SELECTOR];
						shell.setLocation(getBelowLocation(shell, offset));
						break;
					}
					case PROPOSAL_OVERLAY: {
						// Overlay the tip selector with the proposal selector.
						Shell shell= fShells[LAYOUT_PROPOSAL_SELECTOR];
						shell.setLocation(getBelowLocation(shell, offset));
						break;
					}
					case PROPOSAL_STACKED: {
						// Stack the proposal selector beneath the tip selector.
						Shell shell= fShells[LAYOUT_PROPOSAL_SELECTOR];
						Shell parent= fShells[LAYOUT_CONTEXT_SELECTOR];
						shell.setLocation(getStackedLocation(shell, parent));
						break;
					}
				}
			}
		}
		
		protected void layoutContextSelector(int offset) {
			// Always place the context selector beneath the cursor line.
			Shell shell= fShells[LAYOUT_CONTEXT_SELECTOR];
			shell.setLocation(getBelowLocation(shell, offset));
			
			if (Helper.okToUse(fShells[LAYOUT_PROPOSAL_SELECTOR])) {
				switch (fProposalPopupOrientation) {
					case PROPOSAL_REMOVE:
						// Remove the proposal selector.
						fShells[LAYOUT_PROPOSAL_SELECTOR].dispose();
						break;
	
					case PROPOSAL_OVERLAY:
						// The proposal selector has been overlayed by the tip selector.
						break;
	
					case PROPOSAL_STACKED: {
						// Stack the proposal selector beneath the tip selector.
						shell= fShells[LAYOUT_PROPOSAL_SELECTOR];
						Shell parent= fShells[LAYOUT_CONTEXT_SELECTOR];
						shell.setLocation(getStackedLocation(shell, parent));
						break;
					}
				}
			}
		}
		
		protected void layoutContextInfoPopup(int offset) {
			switch (fContextInfoPopupOrientation) {
				case CONTEXT_INFO_ABOVE: {
					// Place the popup above the cursor line.
					Shell shell= fShells[LAYOUT_CONTEXT_INFO_POPUP];
					shell.setLocation(getAboveLocation(shell, offset));
					break;
				}
				case CONTEXT_INFO_BELOW: {
					// Place the popup beneath the cursor line.
					Shell parent= fShells[LAYOUT_CONTEXT_INFO_POPUP];
					parent.setLocation(getBelowLocation(parent, offset));
					if (Helper.okToUse(fShells[LAYOUT_PROPOSAL_SELECTOR])) {
						// Stack the proposal selector beneath the context info popup.
						Shell shell= fShells[LAYOUT_PROPOSAL_SELECTOR];
						shell.setLocation(getStackedLocation(shell, parent));
					}
					break;
				}
			}
		}
		
		protected void shiftHorizontalLocation(Point location, Rectangle shellBounds, Rectangle displayBounds) {
			if (location.x + shellBounds.width > displayBounds.width)
				location.x= displayBounds.width - shellBounds.width;
			
			if (location.x < displayBounds.x)
				location.x= displayBounds.x;
		}
		
		protected void shiftVerticalLocation(Point location, Rectangle shellBounds, Rectangle displayBounds) {
			if (location.y + shellBounds.height > displayBounds.height)
				location.y= displayBounds.height - shellBounds.height;
			
			if (location.y < displayBounds.y)
				location.y= displayBounds.y;
		}
				
		protected Point getAboveLocation(Shell shell, int offset) {
			Point location= fContentAssistSubjectControlAdapter.getLocationAtOffset(offset);
			location= fContentAssistSubjectControlAdapter.getControl().toDisplay(location);
			
			Rectangle shellBounds= shell.getBounds();
			Rectangle displayBounds= shell.getDisplay().getClientArea();
			
			location.y=location.y - shellBounds.height;
			
			shiftHorizontalLocation(location, shellBounds, displayBounds);
			shiftVerticalLocation(location, shellBounds, displayBounds);
			
			return location;
		}
		
		protected Point getBelowLocation(Shell shell, int offset) {
			Point location= fContentAssistSubjectControlAdapter.getLocationAtOffset(offset);
			if (location.x < 0) location.x= 0;
			if (location.y < 0) location.y= 0;
			location= fContentAssistSubjectControlAdapter.getControl().toDisplay(location);
			
			Rectangle shellBounds= shell.getBounds();
			Rectangle displayBounds= shell.getDisplay().getClientArea();
			
			location.y= location.y + fContentAssistSubjectControlAdapter.getLineHeight();
			shiftHorizontalLocation(location, shellBounds, displayBounds);
			shiftVerticalLocation(location, shellBounds, displayBounds);
			
			return location;
		}	
		
		protected Point getStackedLocation(Shell shell, Shell parent) {
			Point p= parent.getLocation();
			Point size= parent.getSize();
			p.x += size.x / 4;
			p.y += size.y;
			
			p= parent.toDisplay(p);

			Rectangle shellBounds= shell.getBounds();
			Rectangle displayBounds= shell.getDisplay().getClientArea();
			shiftHorizontalLocation(p, shellBounds, displayBounds);
			shiftVerticalLocation(p, shellBounds, displayBounds);
			
			return p;
		}

		protected void adjustListeners(int type) {
			switch (type) {
				case LAYOUT_PROPOSAL_SELECTOR:
					if (fContextType == LAYOUT_CONTEXT_SELECTOR &&
							Helper.okToUse(fShells[LAYOUT_CONTEXT_SELECTOR]))
						// Disable event notification to the tip selector.
						removeContentAssistListener((IContentAssistListener) fPopups[LAYOUT_CONTEXT_SELECTOR], CONTEXT_SELECTOR);						
					break;
				case LAYOUT_CONTEXT_SELECTOR:
					if (Helper.okToUse(fShells[LAYOUT_PROPOSAL_SELECTOR]))
						// Disable event notification to the proposal selector.
						removeContentAssistListener((IContentAssistListener) fPopups[LAYOUT_PROPOSAL_SELECTOR], PROPOSAL_SELECTOR);						
					break;
				case LAYOUT_CONTEXT_INFO_POPUP:
					break;
			}
		}
	}
	
	/**
	 * Internal key listener and event consumer.
	 */
	class InternalListener implements VerifyKeyListener, IEventConsumer {
		
		/**
		 * Verifies key events by notifying the registered listeners.
		 * Each listener is allowed to indicate that the event has been
		 * handled and should not be further processed.
		 *
		 * @param e the verify event
		 * @see VerifyKeyListener#verifyKey(org.eclipse.swt.events.VerifyEvent)
		 */
		public void verifyKey(VerifyEvent e) {
			IContentAssistListener[] listeners= (IContentAssistListener[]) fListeners.clone();
			for (int i= 0; i < listeners.length; i++) {
				if (listeners[i] != null) {
					if (!listeners[i].verifyKey(e) || !e.doit)
						break;
				}
			}
			if (fAutoAssistListener != null)
				fAutoAssistListener.keyPressed(e);
		}
				
		/*
		 * @see IEventConsumer#processEvent
		 */
		public void processEvent(VerifyEvent event) {
			
			installKeyListener();
			
			IContentAssistListener[] listeners= (IContentAssistListener[])fListeners.clone();
			for (int i= 0; i < listeners.length; i++) {
				if (listeners[i] != null) {
					listeners[i].processEvent(event);
					if (!event.doit)
						return;
				}
			}
		}
	}
	
	/**
	 * Dialog store constants.
	 * @since 3.0
	 */
	public static final String STORE_SIZE_X= "size.x"; //$NON-NLS-1$
	public static final String STORE_SIZE_Y= "size.y"; //$NON-NLS-1$
	
	// Content-Assist Listener types
	final static int CONTEXT_SELECTOR= 0;
	final static int PROPOSAL_SELECTOR= 1;
	final static int CONTEXT_INFO_POPUP= 2;
	
	/** 
	 * The popup priority: &gt; linked position proposals and hover popups.
	 * Default value: <code>20</code>;
	 *  
	 * @since 3.0
	 */
	public static final int WIDGET_PRIORITY= 20;
	
	private static final int DEFAULT_AUTO_ACTIVATION_DELAY= 500;
	
	private IInformationControlCreator fInformationControlCreator;
	private int fAutoActivationDelay= DEFAULT_AUTO_ACTIVATION_DELAY;
	private boolean fIsAutoActivated= false;
	private boolean fIsAutoInserting= false;
	private int fProposalPopupOrientation= PROPOSAL_OVERLAY;
	private int fContextInfoPopupOrientation= CONTEXT_INFO_ABOVE;	
	private Map fProcessors;
	private String fPartitioning;
	
	private Color fContextInfoPopupBackground;
	private Color fContextInfoPopupForeground;
	private Color fContextSelectorBackground;
	private Color fContextSelectorForeground;
	private Color fProposalSelectorBackground;
	private Color fProposalSelectorForeground;

	private ITextViewer fViewer;
	private String fLastErrorMessage;
	
	private Closer fCloser;
	private LayoutManager fLayoutManager;
	private AutoAssistListener fAutoAssistListener;
	private InternalListener fInternalListener;
	private CompletionProposalPopup fProposalPopup;
	private ContextInformationPopup fContextInfoPopup;
	
	private boolean fVerifyKeyListenerHooked= false;
	private IContentAssistListener[] fListeners= new IContentAssistListener[4];
	/**
	 * The content assist subject control.
	 * 
	 * @since 3.0
	 */
	private IContentAssistSubjectControl fContentAssistSubjectControl;
	/**
	 * The content assist subject control adapter.
	 * 
	 * @since 3.0
	 */
	private ContentAssistSubjectControlAdapter fContentAssistSubjectControlAdapter;	
	/**
	 * The dialog settings for the control's bounds.
	 * 
	 * @since 3.0
	 */
	private IDialogSettings fDialogSettings;
	/**
	 * Prefix completion setting.
	 * 
	 * @since 3.0
	 */
	private boolean fIsPrefixCompletionEnabled= false;
	
	/**
	 * Creates a new content assistant. The content assistant is not automatically activated,
	 * overlays the completion proposals with context information list if necessary, and
	 * shows the context information above the location at which it was activated. If auto
	 * activation will be enabled, without further configuration steps, this content assistant
	 * is activated after a 500 ms delay. It uses the default partitioning.
	 */	
	public ContentAssistant() {
		fPartitioning= IDocumentExtension3.DEFAULT_PARTITIONING;
	}
	
	/**
	 * Sets the document partitioning this content assistant is using.
	 * 
	 * @param partitioning the document partitioning for this content assistant
	 */
	public void setDocumentPartitioning(String partitioning) {
		Assert.isNotNull(partitioning);
		fPartitioning= partitioning;
	}
	
	/*
	 * @see org.eclipse.jface.text.contentassist.IContentAssistantExtension#getDocumentPartitioning()
	 * @since 3.0
	 */
	public String getDocumentPartitioning() {
		return fPartitioning;
	}
	
	/**
	 * Registers a given content assist processor for a particular content type.
	 * If there is already a processor registered for this type, the new processor 
	 * is registered instead of the old one.
	 *
	 * @param processor the content assist processor to register, or <code>null</code> to remove an existing one
	 * @param contentType the content type under which to register
	 */	
	 public void setContentAssistProcessor(IContentAssistProcessor processor, String contentType) {
		
		Assert.isNotNull(contentType);
					
		if (fProcessors == null)
			fProcessors= new HashMap();
			
		if (processor == null)
			fProcessors.remove(contentType);
		else
			fProcessors.put(contentType, processor);
	}
	
	/*
	 * @see IContentAssistant#getContentAssistProcessor 	 
	 */
	public IContentAssistProcessor getContentAssistProcessor(String contentType) {
		if (fProcessors == null)
			return null;
						
		return (IContentAssistProcessor) fProcessors.get(contentType);
	}
	
	/**
	 * Enables the content assistant's auto activation mode.
	 *
	 * @param enabled indicates whether auto activation is enabled or not
	 */
	public void enableAutoActivation(boolean enabled) {
		fIsAutoActivated= enabled;
		manageAutoActivation(fIsAutoActivated);
	}
	
	/**
	 * Enables the content assistant's auto insertion mode. If enabled,
	 * the content assistant inserts a proposal automatically if it is
	 * the only proposal. In the case of ambiguities, the user must
	 * make the choice.
	 * 
	 * @param enabled indicates whether auto insertion is enabled or not
	 * @since 2.0
	 */
	public void enableAutoInsert(boolean enabled) {
		fIsAutoInserting= enabled;
	}
	
	/**
	 * Returns whether this content assistant is in the auto insertion
	 * mode or not.
	 * 
	 * @return <code>true</code> if in auto insertion mode
	 * @since 2.0
	 */
	boolean isAutoInserting() {
		return fIsAutoInserting;
	}
	
	/**
	 * Installs and uninstall the listeners needed for autoactivation.
	 * @param start <code>true</code> if listeners must be installed,
	 * 	<code>false</code> if they must be removed
	 * @since 2.0
	 */
	private void manageAutoActivation(boolean start) {			
		if (start) {
			
			if ((fContentAssistSubjectControlAdapter != null) && fAutoAssistListener == null) {
				fAutoAssistListener= new AutoAssistListener();
				// TODO see bug 49212 
				if (fContentAssistSubjectControlAdapter.supportsVerifyKeyListener())
					fContentAssistSubjectControlAdapter.appendVerifyKeyListener(fAutoAssistListener);
				else
					fContentAssistSubjectControlAdapter.addKeyListener(fAutoAssistListener);
			}
			
		} else if (fAutoAssistListener != null) {
			// TODO see bug 49212 
			if (fContentAssistSubjectControlAdapter.supportsVerifyKeyListener())
				fContentAssistSubjectControlAdapter.removeVerifyKeyListener(fAutoAssistListener);
			else
				fContentAssistSubjectControlAdapter.removeKeyListener(fAutoAssistListener);
			fAutoAssistListener= null;
		}
	}
	
	/**
	 * Sets the delay after which the content assistant is automatically invoked
	 * if the cursor is behind an auto activation character. 
	 *
	 * @param delay the auto activation delay
	 */
	public void setAutoActivationDelay(int delay) {
		fAutoActivationDelay= delay;
	}
	
	/**
	 * Sets the proposal popups' orientation.
	 * The following values may be used:
	 * <ul>
	 *   <li>PROPOSAL_OVERLAY<p>
	 *     proposal popup windows should overlay each other
	 *   </li>
	 *   <li>PROPOSAL_REMOVE<p>
	 *     any currently shown proposal popup should be closed
	 *   </li>
	 *   <li>PROPOSAL_STACKED<p>
	 *     proposal popup windows should be vertical stacked, with no overlap,
	 *     beneath the line containing the current cursor location
	 *   </li>
	 * </ul>
	 *
	 * @param orientation the popup's orientation
	 */	 
	public void setProposalPopupOrientation(int orientation) {
		fProposalPopupOrientation= orientation;
	}
	
	/**
	 * Sets the context information popup's orientation.
	 * The following values may be used:
	 * <ul>
	 *   <li>CONTEXT_ABOVE<p>
	 *     context information popup should always appear above the line containing
	 *     the current cursor location
	 *   </li>
	 *   <li>CONTEXT_BELOW<p>
	 *     context information popup should always appear below the line containing
	 *     the current cursor location
	 *   </li>
	 * </ul>
	 *
	 * @param orientation the popup's orientation
	 */	
	public void setContextInformationPopupOrientation(int orientation) {
		fContextInfoPopupOrientation= orientation;
	}
	
	/**
	 * Sets the context information popup's background color.
	 *
	 * @param background the background color
	 */
	public void setContextInformationPopupBackground(Color background) {
		fContextInfoPopupBackground= background;
	}
	
	/**
	 * Returns the background of the context information popup.
	 *
	 * @return the background of the context information popup
	 * @since 2.0
	 */
	Color getContextInformationPopupBackground() {
		return fContextInfoPopupBackground;
	}
	
	/**
	 * Sets the context information popup's foreground color.
	 *
	 * @param foreground the foreground color
	 * @since 2.0
	 */
	public void setContextInformationPopupForeground(Color foreground) {
		fContextInfoPopupForeground= foreground;
	}
	
	/**
	 * Returns the foreground of the context information popup.
	 *
	 * @return the foreground of the context information popup
	 * @since 2.0
	 */
	Color getContextInformationPopupForeground() {
		return fContextInfoPopupForeground;
	}
	
	/**
	 * Sets the proposal selector's background color.
	 *
	 * @param background the background color
	 * @since 2.0
	 */
	public void setProposalSelectorBackground(Color background) {
		fProposalSelectorBackground= background;
	}
	
	/**
	 * Returns the background of the proposal selector.
	 *
	 * @return the background of the proposal selector
	 * @since 2.0
	 */
	Color getProposalSelectorBackground() {
		return fProposalSelectorBackground;
	}
	
	/**
	 * Sets the proposal's foreground color.
	 *
	 * @param foreground the foreground color
	 * @since 2.0
	 */
	public void setProposalSelectorForeground(Color foreground) {
		fProposalSelectorForeground= foreground;
	}
	
	/**
	 * Returns the foreground of the proposal selector.
	 *
	 * @return the foreground of the proposal selector
	 * @since 2.0
	 */
	Color getProposalSelectorForeground() {
		return fProposalSelectorForeground;
	}
	
	/**
	 * Sets the context selector's background color.
	 *
	 * @param background the background color
	 * @since 2.0
	 */
	public void setContextSelectorBackground(Color background) {
		fContextSelectorBackground= background;
	}
	
	/**
	 * Returns the background of the context selector.
	 *
	 * @return the background of the context selector
	 * @since 2.0
	 */
	Color getContextSelectorBackground() {
		return fContextSelectorBackground;
	}
	
	/**
	 * Sets the context selector's foreground color.
	 *
	 * @param foreground the foreground color
	 * @since 2.0
	 */
	public void setContextSelectorForeground(Color foreground) {
		fContextSelectorForeground= foreground;
	}
	
	/**
	 * Returns the foreground of the context selector.
	 *
	 * @return the foreground of the context selector
	 * @since 2.0
	 */
	Color getContextSelectorForeground() {
		return fContextSelectorForeground;
	}
	
	/**
	 * Sets the information control creator for the additional information control.
	 * 
	 * @param creator the information control creator for the additional information control
	 * @since 2.0
	 */
	public void setInformationControlCreator(IInformationControlCreator creator) {
		fInformationControlCreator= creator;
	}

	/*
	 * @see IControlContentAssistant#install(IContentAssistSubjectControl)
	 */
	protected void install(IContentAssistSubjectControl contentAssistSubjectControl) {
		fContentAssistSubjectControl= contentAssistSubjectControl;
		fContentAssistSubjectControlAdapter= new ContentAssistSubjectControlAdapter(fContentAssistSubjectControl);
		install();
	}
	
	/*
	 * @see IContentAssist#install
	 */
	public void install(ITextViewer textViewer) {
		fViewer= textViewer;
		fContentAssistSubjectControlAdapter= new ContentAssistSubjectControlAdapter(fViewer);
		install();
	}
	
	protected void install() {
		
		fLayoutManager= new LayoutManager();
		fInternalListener= new InternalListener();
		
		AdditionalInfoController controller= null;
		if (fInformationControlCreator != null) {
			int delay= fAutoActivationDelay;
			if (delay == 0)
				delay= DEFAULT_AUTO_ACTIVATION_DELAY;
			delay= Math.round(delay * 1.5f);
			controller= new AdditionalInfoController(fInformationControlCreator, delay);
		}
		
		fContextInfoPopup= fContentAssistSubjectControlAdapter.createContextInfoPopup(this);
		fProposalPopup= fContentAssistSubjectControlAdapter.createCompletionProposalPopup(this, controller);
		
		manageAutoActivation(fIsAutoActivated);
	}
	
	/*
	 * @see IContentAssist#uninstall
	 */
	public void uninstall() {
		hide();
		manageAutoActivation(false);
		
		if (fCloser != null) {
			fCloser.uninstall();
			fCloser= null;
		}
		
		fViewer= null;
		fContentAssistSubjectControl= null;
		fContentAssistSubjectControlAdapter= null;
	}

	/**
	 * Adds the given shell of the specified type to the layout.
	 * Valid types are defined by <code>LayoutManager</code>.
	 *
	 * @param popup a content assist popup
	 * @param shell the shell of the content-assist popup
	 * @param type the type of popup
	 * @param visibleOffset the offset at which to layout the popup relative to the offset of the viewer's visible region
	 * @since 2.0
	 */
	void addToLayout(Object popup, Shell shell, int type, int visibleOffset) {
		fLayoutManager.add(popup, shell, type, visibleOffset);
	}
	
	/**
	 * Layouts the registered popup of the given type relative to the
	 * given offset. The offset is relative to the offset of the viewer's visible region.
	 * Valid types are defined by <code>LayoutManager</code>.
	 * 
	 * @param type the type of popup to layout
	 * @param visibleOffset the offset at which to layout relative to the offset of the viewer's visible region
	 * @since 2.0
	 */
	void layout(int type, int visibleOffset) {
		fLayoutManager.layout(type, visibleOffset);
	}
	
	/**
	 * Notifies the controller that a popup has lost focus.
	 *
	 * @param e the focus event
	 */
	void popupFocusLost(FocusEvent e) {
		fCloser.focusLost(e);
	}
	
	/**
	 * Returns the offset of the selection relative to the offset of the visible region.
	 * 
	 * @return the offset of the selection relative to the offset of the visible region
	 * @since 2.0
	 */
	int getSelectionOffset() {
		return fContentAssistSubjectControlAdapter.getWidgetSelectionRange().x;
	}
	
	/**
	 * Returns whether the widget token could be acquired.
	 * The following are valid listener types:
	 * <ul>
	 *   <li>AUTO_ASSIST
	 *   <li>CONTEXT_SELECTOR
	 *   <li>PROPOSAL_SELECTOR
	 *   <li>CONTEXT_INFO_POPUP
	 * <ul>
	 * @param type the listener type for which to acquire
	 * @return <code>true</code> if the widget token could be acquired
	 * @since 2.0
	 */
	private boolean acquireWidgetToken(int type) {
		switch (type) {
			case CONTEXT_SELECTOR:
			case PROPOSAL_SELECTOR:
				if (fContentAssistSubjectControl instanceof IWidgetTokenOwnerExtension)  {
					IWidgetTokenOwnerExtension extension= (IWidgetTokenOwnerExtension)fContentAssistSubjectControl;
					return extension.requestWidgetToken(this, WIDGET_PRIORITY);
				} else if (fContentAssistSubjectControl instanceof IWidgetTokenOwner) {
					IWidgetTokenOwner owner= (IWidgetTokenOwner)fContentAssistSubjectControl;
					return owner.requestWidgetToken(this);
				} else if (fViewer instanceof IWidgetTokenOwnerExtension)  {
					IWidgetTokenOwnerExtension extension= (IWidgetTokenOwnerExtension) fViewer;
					return extension.requestWidgetToken(this, WIDGET_PRIORITY);
				} else if (fViewer instanceof IWidgetTokenOwner) {
					IWidgetTokenOwner owner= (IWidgetTokenOwner) fViewer;
					return owner.requestWidgetToken(this);
				}
		}	
		return true;
	}
	
	/**
	 * Registers a content assist listener.
	 * The following are valid listener types:
	 * <ul>
	 *   <li>AUTO_ASSIST
	 *   <li>CONTEXT_SELECTOR
	 *   <li>PROPOSAL_SELECTOR
	 *   <li>CONTEXT_INFO_POPUP
	 * <ul>
	 * Returns whether the listener could be added successfully. A listener
	 * can not be added if the widget token could not be acquired.
	 *
	 * @param listener the listener to register
	 * @param type the type of listener
	 * @return <code>true</code> if the listener could be added
	 */
	boolean addContentAssistListener(IContentAssistListener listener, int type) {
		
		if (acquireWidgetToken(type)) {
			
			fListeners[type]= listener;
			
			if (fCloser == null && getNumberOfListeners() == 1) {
				fCloser= new Closer();
				fCloser.install();
				fContentAssistSubjectControlAdapter.setEventConsumer(fInternalListener);
				installKeyListener();
			} else
				promoteKeyListener();
			return true;
		}
		
		return false;
	}
	
	/**
	 * Repromotes the keylistener to the first position, using
	 * prependVerifyKeyListener. This ensures no other instance is
	 * filtering away the keystrokes underneath, if we've been up for a
	 * while (e.g. when the context info is showing.
	 * 
	 * @since 3.0
	 */
	private void promoteKeyListener() {
		uninstallVerifyKeyListener();
		installKeyListener();
	}

	/**
	 * Installs a key listener on the text viewer's widget.
	 */
	private void installKeyListener() {
		if (!fVerifyKeyListenerHooked) {
			if (Helper.okToUse(fContentAssistSubjectControlAdapter.getControl())) {
				fVerifyKeyListenerHooked= fContentAssistSubjectControlAdapter.prependVerifyKeyListener(fInternalListener);
			}
		}
	}
	
	/**
	 * Releases the previously acquired widget token if the token
	 * is no longer necessary.
	 * The following are valid listener types:
	 * <ul>
	 *   <li>AUTO_ASSIST
	 *   <li>CONTEXT_SELECTOR
	 *   <li>PROPOSAL_SELECTOR
	 *   <li>CONTEXT_INFO_POPUP
	 * <ul>
	 * 
	 * @param type the listener type
	 * @since 2.0
	 */
	private void releaseWidgetToken(int type) {
		if (fListeners[CONTEXT_SELECTOR] == null && fListeners[PROPOSAL_SELECTOR] == null) {
			IWidgetTokenOwner owner= null;
			if (fContentAssistSubjectControl instanceof IWidgetTokenOwner)
				owner= (IWidgetTokenOwner)fContentAssistSubjectControl;
			else if (fViewer instanceof IWidgetTokenOwner)
				owner= (IWidgetTokenOwner)fViewer;
			if (owner != null)
				owner.releaseWidgetToken(this);
		}
	}
	
	/**
	 * Unregisters a content assist listener.
	 *
	 * @param listener the listener to unregister
	 * @param type the type of listener
	 *
	 * @see #addContentAssistListener(IContentAssistListener, int)
	 */
	void removeContentAssistListener(IContentAssistListener listener, int type) {
		fListeners[type]= null;
		
		if (getNumberOfListeners() == 0) {
			
			if (fCloser != null) {
				fCloser.uninstall();
				fCloser= null;
			}
		
			uninstallVerifyKeyListener();
			fContentAssistSubjectControlAdapter.setEventConsumer(null);
		}
		
		releaseWidgetToken(type);
	}
	
	/**
	 * Uninstall the key listener from the text viewer's widget.
	 */
	private void uninstallVerifyKeyListener() {
		if (fVerifyKeyListenerHooked) {
			if (Helper.okToUse(fContentAssistSubjectControlAdapter.getControl()))
				fContentAssistSubjectControlAdapter.removeVerifyKeyListener(fInternalListener);
			fVerifyKeyListenerHooked= false;
		}
	}
	
	/**
	 * Returns the number of listeners.
	 *
	 * @return the number of listeners
	 * @since 2.0
	 */
	private int getNumberOfListeners() {
		int count= 0;
		for (int i= 0; i <= CONTEXT_INFO_POPUP; i++) {
			if (fListeners[i] != null)
				++ count;
		}
		return count;
	}
		
	/*
	 * @see IContentAssist#showPossibleCompletions
	 */
	public String showPossibleCompletions() {
		promoteKeyListener();
		if (fIsPrefixCompletionEnabled)
			return fProposalPopup.incrementalComplete();
		else
			return fProposalPopup.showProposals(false);
	}
	
	/*
	 * @see org.eclipse.jface.text.contentassist.IContentAssistantExtension#completePrefix()
	 */
	public String completePrefix() {
		promoteKeyListener();
		return fProposalPopup.incrementalComplete();
	}
	
	/**
	 * Callback to signal this content assistant that the presentation of the possible completions has been stopped.
	 * @since 2.1 
	 */
	protected void possibleCompletionsClosed() {
		storeCompletionProposalPopupSize();
	}
	
	/*
	 * @see IContentAssist#showContextInformation
	 */
	public String showContextInformation() {
		promoteKeyListener();
		if (fContextInfoPopup != null)
			return fContextInfoPopup.showContextProposals(false);
		else
			return null;
	}
	
	/**
	 * Callback to signal this content assistant that the presentation of the context information has been stopped.
	 * @since 2.1 
	 */
	protected void contextInformationClosed() {
	}
	
	/**
	 * Requests that the specified context information to be shown.
	 *
	 * @param contextInformation the context information to be shown
	 * @param position the position to which the context information refers to
	 * @since 2.0
	 */
	void showContextInformation(IContextInformation contextInformation, int position) {
		if (fContextInfoPopup != null)
			fContextInfoPopup.showContextInformation(contextInformation, position);
	}
	
	/**
	 * Returns the current content assist error message.
	 *
	 * @return an error message or <code>null</code> if no error has occurred
	 */
	String getErrorMessage() {
		return fLastErrorMessage;
	}
	
	/**
	 * Returns the content assist processor for the content
	 * type of the specified document position.
	 *
	 * @param viewer the text viewer
	 * @param offset a offset within the document
	 * @return a content-assist processor or <code>null</code> if none exists
	 */
	private IContentAssistProcessor getProcessor(ITextViewer viewer, int offset) {
		try {
			
			IDocument document= viewer.getDocument();
			String type= TextUtilities.getContentType(document, getDocumentPartitioning(), offset, true);
			
			return getContentAssistProcessor(type);
		
		} catch (BadLocationException x) {
		}
		
		return null;
	}

	/**
	 * Returns the content assist processor for the content
	 * type of the specified document position.
	 *
	 * @param contentAssistSubjectControl the content assist subject control
	 * @param offset a offset within the document
	 * @return a content-assist processor or <code>null</code> if none exists
	 */
	private IContentAssistProcessor getProcessor(IContentAssistSubjectControl contentAssistSubjectControl, int offset) {
		try {
			
			IDocument document= contentAssistSubjectControl.getDocument();
			String type;
			if (document != null)
				type= TextUtilities.getContentType(document, getDocumentPartitioning(), offset, true);
			else 
				type= IDocument.DEFAULT_CONTENT_TYPE;
			
			return getContentAssistProcessor(type);
		
		} catch (BadLocationException x) {
		}
		
		return null;
	}
	
	/**
	 * Returns an array of completion proposals computed based on 
	 * the specified document position. The position is used to 
	 * determine the appropriate content assist processor to invoke.
	 *
	 * @param contentAssistSubjectControl the content assist subject control
	 * @param position a document position
	 * @return an array of completion proposals
	 *
	 * @see IContentAssistProcessor#computeCompletionProposals(ITextViewer, int)
	 */
	ICompletionProposal[] computeCompletionProposals(IContentAssistSubjectControl contentAssistSubjectControl, int position) {
		fLastErrorMessage= null;
		
		ICompletionProposal[] result= null;
		
		IContentAssistProcessor p= getProcessor(contentAssistSubjectControl, position);
		if (p instanceof ISubjectControlContentAssistProcessor) {
			result= ((ISubjectControlContentAssistProcessor)p).computeCompletionProposals(contentAssistSubjectControl, position);
			fLastErrorMessage= p.getErrorMessage();
		}
		
		return result;
	}
		
	/**
	 * Returns an array of completion proposals computed based on 
	 * the specified document position. The position is used to 
	 * determine the appropriate content assist processor to invoke.
	 *
	 * @param viewer the viewer for which to compute the proposals
	 * @param position a document position
	 * @return an array of completion proposals
	 *
	 * @see IContentAssistProcessor#computeCompletionProposals(ITextViewer, int)
	 */
	ICompletionProposal[] computeCompletionProposals(ITextViewer viewer, int position) {
		fLastErrorMessage= null;
		
		ICompletionProposal[] result= null;
		
		IContentAssistProcessor p= getProcessor(viewer, position);
		if (p != null) {
			result= p.computeCompletionProposals(viewer, position);
			fLastErrorMessage= p.getErrorMessage();
		}
		
		return result;
	}
	
	/**
	 * Returns an array of context information objects computed based
	 * on the specified document position. The position is used to determine 
	 * the appropriate content assist processor to invoke.
	 *
	 * @param viewer the viewer for which to compute the context information
	 * @param position a document position
	 * @return an array of context information objects
	 *
	 * @see IContentAssistProcessor#computeContextInformation(ITextViewer, int)
	 */
	IContextInformation[] computeContextInformation(ITextViewer viewer, int position) {
		fLastErrorMessage= null;
		
		IContextInformation[] result= null;
		
		IContentAssistProcessor p= getProcessor(viewer, position);
		if (p != null) {
			result= p.computeContextInformation(viewer, position);
			fLastErrorMessage= p.getErrorMessage();
		}
		
		return result;
	}

	/**
	 * Returns an array of context information objects computed based
	 * on the specified document position. The position is used to determine 
	 * the appropriate content assist processor to invoke.
	 *
	 * @param contentAssistSubjectControl the content assist subject control
	 * @param position a document position
	 * @return an array of context information objects
	 *
	 * @see IContentAssistProcessor#computeContextInformation(ITextViewer, int)
	 */
	IContextInformation[] computeContextInformation(IContentAssistSubjectControl contentAssistSubjectControl, int position) {
		fLastErrorMessage= null;
		
		IContextInformation[] result= null;
		
		IContentAssistProcessor p= getProcessor(contentAssistSubjectControl, position);
		if (p instanceof ISubjectControlContentAssistProcessor) {
			result= ((ISubjectControlContentAssistProcessor)p).computeContextInformation(contentAssistSubjectControl, position);
			fLastErrorMessage= p.getErrorMessage();
		}
		
		return result;
	}
	
	/**
	 * Returns the context information validator that should be used to 
	 * determine when the currently displayed context information should
	 * be dismissed. The position is used to determine the appropriate 
	 * content assist processor to invoke.
	 *
	 * @param viewer the text viewer
	 * @param offset a document offset
	 * @return an validator
	 *
	 * @see IContentAssistProcessor#getContextInformationValidator()
	 */
	IContextInformationValidator getContextInformationValidator(ITextViewer viewer, int offset) {
		IContentAssistProcessor p= getProcessor(viewer, offset);
		return p != null ? p.getContextInformationValidator() : null;
	}

	/**
	 * Returns the context information validator that should be used to 
	 * determine when the currently displayed context information should
	 * be dismissed. The position is used to determine the appropriate 
	 * content assist processor to invoke.
	 *
	 * @param contentAssistSubjectControl the content assist subject control
	 * @param offset a document offset
	 * @return an validator
	 * @see IContentAssistProcessor#getContextInformationValidator()
	 * @since 3.0
	 */
	IContextInformationValidator getContextInformationValidator(IContentAssistSubjectControl contentAssistSubjectControl, int offset) {
		IContentAssistProcessor p= getProcessor(contentAssistSubjectControl, offset);
		return p != null ? p.getContextInformationValidator() : null;
	}

	/**
	 * Returns the context information presenter that should be used to 
	 * display context information. The position is used to determine the appropriate 
	 * content assist processor to invoke.
	 *
	 * @param viewer the text viewer
	 * @param offset a document offset
	 * @return a presenter
	 * @since 2.0
	 */
	IContextInformationPresenter getContextInformationPresenter(ITextViewer viewer, int offset) {
		IContextInformationValidator validator= getContextInformationValidator(viewer, offset);
		if (validator instanceof IContextInformationPresenter)
			return (IContextInformationPresenter) validator;
		return null;
	}
	
	/**
	 * Returns the context information presenter that should be used to 
	 * display context information. The position is used to determine the appropriate 
	 * content assist processor to invoke.
	 *
	 * @param contentAssistSubjectControl the content assist subject control
	 * @param offset a document offset
	 * @return a presenter
	 * @since 3.0
	 */
	IContextInformationPresenter getContextInformationPresenter(IContentAssistSubjectControl contentAssistSubjectControl, int offset) {
		IContextInformationValidator validator= getContextInformationValidator(contentAssistSubjectControl, offset);
		if (validator instanceof IContextInformationPresenter)
			return (IContextInformationPresenter) validator;
		return null;
	}
	
	/**
	 * Returns the characters which when typed by the user should automatically
	 * initiate proposing completions. The position is used to determine the 
	 * appropriate content assist processor to invoke.
	 *
	 * @param contentAssistSubjectControl the content assist subject control
	 * @param offset a document offset
	 * @return the auto activation characters
	 * @see IContentAssistProcessor#getCompletionProposalAutoActivationCharacters()
	 * @since 3.0
	 */
	char[] getCompletionProposalAutoActivationCharacters(IContentAssistSubjectControl contentAssistSubjectControl, int offset) {
		IContentAssistProcessor p= getProcessor(contentAssistSubjectControl, offset);
		return p != null ? p.getCompletionProposalAutoActivationCharacters() : null;
	}
	
	/**
	 * Returns the characters which when typed by the user should automatically
	 * initiate proposing completions. The position is used to determine the 
	 * appropriate content assist processor to invoke.
	 *
	 * @param viewer the text viewer
	 * @param offset a document offset
	 * @return the auto activation characters
	 *
	 * @see IContentAssistProcessor#getCompletionProposalAutoActivationCharacters()
	 */
	char[] getCompletionProposalAutoActivationCharacters(ITextViewer viewer, int offset) {
		IContentAssistProcessor p= getProcessor(viewer, offset);
		return p != null ? p.getCompletionProposalAutoActivationCharacters() : null;
	}
	
	/**
	 * Returns the characters which when typed by the user should automatically
	 * initiate the presentation of context information. The position is used
	 * to determine the appropriate content assist processor to invoke.
	 *
	 * @param viewer the text viewer
	 * @param offset a document offset
	 * @return the auto activation characters
	 *
	 * @see IContentAssistProcessor#getContextInformationAutoActivationCharacters()
	 */
	char[] getContextInformationAutoActivationCharacters(ITextViewer viewer, int offset) {
		IContentAssistProcessor p= getProcessor(viewer, offset);
		return p != null ? p.getContextInformationAutoActivationCharacters() : null;
	}
	
	/**
	 * Returns the characters which when typed by the user should automatically
	 * initiate the presentation of context information. The position is used
	 * to determine the appropriate content assist processor to invoke.
	 *
	 * @param contentAssistSubjectControl the content assist subject control
	 * @param offset a document offset
	 * @return the auto activation characters
	 *
	 * @see IContentAssistProcessor#getContextInformationAutoActivationCharacters()
	 */
	char[] getContextInformationAutoActivationCharacters(IContentAssistSubjectControl contentAssistSubjectControl, int offset) {
		IContentAssistProcessor p= getProcessor(contentAssistSubjectControl, offset);
		return p != null ? p.getContextInformationAutoActivationCharacters() : null;
	}
	
	/*
	 * @see org.eclipse.jface.text.IWidgetTokenKeeper#requestWidgetToken(IWidgetTokenOwner)
	 * @since 2.0
	 */
	public boolean requestWidgetToken(IWidgetTokenOwner owner) {
		return false;
	}

	/*
	 * @see org.eclipse.jface.text.IWidgetTokenKeeperExtension#requestWidgetToken(org.eclipse.jface.text.IWidgetTokenOwner, int)
	 * @since 3.0
	 */
	public boolean requestWidgetToken(IWidgetTokenOwner owner, int priority) {
		if (priority > WIDGET_PRIORITY) {
			hide();
			return true;
		} else  {
			return false;
		}
	}

	/*
	 * @see org.eclipse.jface.text.IWidgetTokenKeeperExtension#setFocus(org.eclipse.jface.text.IWidgetTokenOwner)
	 * @since 3.0
	 */
	public boolean setFocus(IWidgetTokenOwner owner) {
		if (fProposalPopup != null) {
			fProposalPopup.setFocus();
			return fProposalPopup.hasFocus();
		}
		return false;
	}
	
	/**
	 * Hides any open popups.
	 */
	protected void hide() {
		if (fProposalPopup != null)
			fProposalPopup.hide();
			
		if (fContextInfoPopup != null)
			fContextInfoPopup.hide();
	}
	// ------ control's size handling dialog settings ------
	
	/**
	 * Tells this information control manager to open the information control
	 * with the values contained in the given dialog settings and to store the
	 * control's last valid size in the given dialog settings.
	 * <p>
	 * Note: This API is only valid if the information control implements
	 * {@link org.eclipse.jface.text.IInformationControlExtension3}. Not
	 * following this restriction will later result in an
	 * {@link UnsupportedOperationException}.
	 * </p>
	 * <p>
	 * The constants used to store the values are:
	 * <ul>
	 * <li>{@link ContentAssistant#STORE_SIZE_X}</li>
	 * <li>{@link ContentAssistant#STORE_SIZE_Y}</li>
	 * </ul>
	 * </p>
	 * 
	 * @param dialogSettings
	 * @since 3.0
	 */
	public void setRestoreCompletionProposalSize(IDialogSettings dialogSettings) {
		Assert.isTrue(dialogSettings != null);
		fDialogSettings= dialogSettings;
	}
	
	/**
	 * Stores the content assist pop-up's size.
	 */
	protected void storeCompletionProposalPopupSize() {
		if (fDialogSettings == null || fProposalPopup == null)
			return;
		
		Point size= fProposalPopup.getSize();
		if (size == null)
			return;
		
		fDialogSettings.put(STORE_SIZE_X, size.x);
		fDialogSettings.put(STORE_SIZE_Y, size.y);
	}
	
	/**
	 * Restores the content assist pop-up's size.
	 * 
	 * @return the stored size
	 * @since 3.0
	 */
	protected Point restoreCompletionProposalPopupSize() {
		if (fDialogSettings == null)
			return null;
		
		Point size= new Point(-1, -1);
		
		try {
			size.x= fDialogSettings.getInt(STORE_SIZE_X);
			size.y= fDialogSettings.getInt(STORE_SIZE_Y);
		} catch (NumberFormatException ex) {
			size.x= -1;
			size.y= -1;
		}
		
		// sanity check
		if (size.x == -1 && size.y == -1)
			return null;
		
		Rectangle maxBounds= null;
		if (fContentAssistSubjectControl != null && !fContentAssistSubjectControl.getControl().isDisposed())
			maxBounds= fContentAssistSubjectControl.getControl().getDisplay().getBounds();
		else {
			// fallback
			Display display= Display.getCurrent();
			if (display == null)
				display= Display.getDefault();
			if (display != null && !display.isDisposed())
				maxBounds= display.getBounds();
		}
			
		
		if (size.x > -1 && size.y > -1) {
			if (maxBounds != null) {
				size.x= Math.min(size.x, maxBounds.width);
				size.y= Math.min(size.y, maxBounds.height);
			}
			
			// Enforce an absolute minimal size
			size.x= Math.max(size.x, 30);
			size.y= Math.max(size.y, 30);
		}
		
		return size;
	}

	/**
	 * Sets the prefix completion property. If enabled, content assist delegates
	 * completion to prefix completion.
	 * 
	 * @param enabled <code>true</code> to enable prefix completion,
	 *        <code>false</code> to disable
	 */
	public void enablePrefixCompletion(boolean enabled) {
		fIsPrefixCompletionEnabled= enabled;
	}
	
	/**
	 * Returns whether the content assistant proposal popup has the focus.
	 * 
	 * @return <code>true</code> if the proposal popup has the focus
	 * @since 3.0
	 */
	public boolean hasProposalPopupFocus() {
		return fProposalPopup.hasFocus();
	}
}