/*******************************************************************************
* 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.dltk.ui.viewsupport;
import java.util.HashMap;
import java.util.Map;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.ListenerList;
import org.eclipse.core.runtime.OperationCanceledException;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.jobs.Job;
import org.eclipse.dltk.ast.parser.IModuleDeclaration;
import org.eclipse.dltk.core.IModelElement;
import org.eclipse.dltk.core.ISourceModule;
import org.eclipse.dltk.core.ModelException;
import org.eclipse.dltk.core.SourceParserUtil;
import org.eclipse.dltk.internal.ui.DLTKUIMessages;
import org.eclipse.dltk.internal.ui.editor.EditorUtility;
import org.eclipse.jface.text.ITextSelection;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.ISelectionChangedListener;
import org.eclipse.jface.viewers.ISelectionProvider;
import org.eclipse.jface.viewers.SelectionChangedEvent;
import org.eclipse.ui.ISelectionListener;
import org.eclipse.ui.IWorkbenchPart;
import org.eclipse.ui.texteditor.ITextEditor;
/**
* Infrastructure to share an AST for editor post selection listeners.
*/
public class SelectionListenerWithASTManager {
private static SelectionListenerWithASTManager fgDefault;
/**
* @return Returns the default manager instance.
*/
public static SelectionListenerWithASTManager getDefault() {
if (fgDefault == null) {
fgDefault = new SelectionListenerWithASTManager();
}
return fgDefault;
}
private final static class PartListenerGroup {
protected final ITextEditor fPart;
private ISelectionListener fPostSelectionListener;
private ISelectionChangedListener fSelectionListener;
private Job fCurrentJob;
protected final ListenerList fAstListeners;
/**
* Lock to avoid having more than one calculateAndInform job in
* parallel. Only jobs may synchronize on this as otherwise deadlocks
* are possible.
*/
protected final Object fJobLock = new Object();
public PartListenerGroup(ITextEditor editorPart) {
fPart = editorPart;
fCurrentJob = null;
fAstListeners = new ListenerList(ListenerList.IDENTITY);
fSelectionListener = new ISelectionChangedListener() {
public void selectionChanged(SelectionChangedEvent event) {
ISelection selection = event.getSelection();
if (selection instanceof ITextSelection) {
fireSelectionChanged((ITextSelection) selection);
}
}
};
fPostSelectionListener = new ISelectionListener() {
public void selectionChanged(IWorkbenchPart part,
ISelection selection) {
if (part == fPart && selection instanceof ITextSelection)
firePostSelectionChanged((ITextSelection) selection);
}
};
}
public boolean isEmpty() {
return fAstListeners.isEmpty();
}
public void install(ISelectionListenerWithAST listener) {
if (isEmpty()) {
fPart.getEditorSite().getPage()
.addPostSelectionListener(fPostSelectionListener);
ISelectionProvider selectionProvider = fPart
.getSelectionProvider();
if (selectionProvider != null)
selectionProvider
.addSelectionChangedListener(fSelectionListener);
}
fAstListeners.add(listener);
}
public void uninstall(ISelectionListenerWithAST listener) {
fAstListeners.remove(listener);
if (isEmpty()) {
fPart.getEditorSite().getPage()
.removePostSelectionListener(fPostSelectionListener);
ISelectionProvider selectionProvider = fPart
.getSelectionProvider();
if (selectionProvider != null)
selectionProvider
.removeSelectionChangedListener(fSelectionListener);
}
}
/**
* A selection event has occurred.
*
* @param selection
* the selection
*/
public void fireSelectionChanged(final ITextSelection selection) {
if (fCurrentJob != null) {
fCurrentJob.cancel();
}
}
/**
* A post selection event has occurred.
*
* @param selection
* the selection
*/
public void firePostSelectionChanged(final ITextSelection selection) {
cancelJob();
IModelElement input = EditorUtility.getEditorInputModelElement(
fPart, false);
if (!(input instanceof ISourceModule)) {
return;
}
fCurrentJob = new ASTJob(this, (ISourceModule) input, selection);
fCurrentJob.schedule();
}
void cancelJob() {
if (fCurrentJob != null) {
fCurrentJob.cancel();
fCurrentJob = null;
}
}
}
protected static class ASTJob extends Job {
private final PartListenerGroup owner;
private final ISourceModule input;
private final ITextSelection selection;
public ASTJob(PartListenerGroup owner, ISourceModule module,
ITextSelection selection) {
super(DLTKUIMessages.SelectionListenerWithASTManager_job_title);
this.owner = owner;
this.input = module;
this.selection = selection;
setPriority(Job.DECORATE);
setSystem(true);
}
@Override
protected void canceling() {
synchronized (this) {
wasCancel = true;
}
}
private boolean wasCancel;
@Override
public IStatus run(IProgressMonitor monitor) {
try {
if (!input.isConsistent()) {
synchronized (this) {
if (!wasCancel) {
schedule(1000);
}
}
return Status.OK_STATUS;
}
} catch (ModelException e) {
// never happens, fall thru
}
synchronized (owner.fJobLock) {
// The monitor is never null
return calculateASTandInform(monitor);
}
}
protected final IStatus calculateASTandInform(IProgressMonitor monitor) {
if (monitor.isCanceled()) {
return Status.CANCEL_STATUS;
}
// create AST
try {
IModuleDeclaration astRoot = SourceParserUtil
.parse(input, null);
if (astRoot != null && !monitor.isCanceled()) {
Object[] listeners = owner.fAstListeners.getListeners();
for (int i = 0; i < listeners.length; i++) {
((ISelectionListenerWithAST) listeners[i])
.selectionChanged(owner.fPart, selection,
input, astRoot);
if (monitor.isCanceled()) {
return Status.CANCEL_STATUS;
}
}
return Status.OK_STATUS;
}
} catch (OperationCanceledException e) {
// thrown when canceling the AST creation
}
return Status.CANCEL_STATUS;
}
}
private Map<ITextEditor, PartListenerGroup> fListenerGroups;
private SelectionListenerWithASTManager() {
fListenerGroups = new HashMap<ITextEditor, PartListenerGroup>();
}
/**
* Registers a selection listener for the given editor part.
*
* @param part
* The editor part to listen to.
* @param listener
* The listener to register.
*/
public void addListener(ITextEditor part, ISelectionListenerWithAST listener) {
synchronized (this) {
PartListenerGroup partListener = fListenerGroups.get(part);
if (partListener == null) {
partListener = new PartListenerGroup(part);
fListenerGroups.put(part, partListener);
}
partListener.install(listener);
}
}
/**
* Unregisters a selection listener.
*
* @param part
* The editor part the listener was registered.
* @param listener
* The listener to unregister.
*/
public void removeListener(ITextEditor part,
ISelectionListenerWithAST listener) {
synchronized (this) {
PartListenerGroup partListener = fListenerGroups.get(part);
if (partListener != null) {
partListener.uninstall(listener);
if (partListener.isEmpty()) {
partListener.cancelJob();
fListenerGroups.remove(part);
}
}
}
}
}