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/*******************************************************************************
* 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.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.NullProgressMonitor;
import org.eclipse.core.runtime.OperationCanceledException;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.jobs.Job;
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;
import org.eclipse.wst.jsdt.core.IJavaScriptElement;
import org.eclipse.wst.jsdt.core.dom.JavaScriptUnit;
import org.eclipse.wst.jsdt.internal.ui.JavaScriptPlugin;
import org.eclipse.wst.jsdt.internal.ui.JavaUIMessages;
import org.eclipse.wst.jsdt.internal.ui.javaeditor.ASTProvider;
import org.eclipse.wst.jsdt.internal.ui.javaeditor.EditorUtility;
/**
* 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 {
private ITextEditor fPart;
private ISelectionListener fPostSelectionListener;
private ISelectionChangedListener fSelectionListener;
private Job fCurrentJob;
private ListenerList fAstListeners;
/**
* Lock to avoid having more than one calculateAndInform job in parallel.
* Only jobs may synchronize on this as otherwise deadlocks are possible.
*/
private 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);
}
}
public void fireSelectionChanged(final ITextSelection selection) {
if (fCurrentJob != null) {
fCurrentJob.cancel();
}
}
public void firePostSelectionChanged(final ITextSelection selection) {
if (fCurrentJob != null) {
fCurrentJob.cancel();
}
final IJavaScriptElement input= EditorUtility.getEditorInputJavaElement(fPart, false);
if (input == null) {
return;
}
fCurrentJob= new Job(JavaUIMessages.SelectionListenerWithASTManager_job_title) {
public IStatus run(IProgressMonitor monitor) {
if (monitor == null) {
monitor= new NullProgressMonitor();
}
synchronized (fJobLock) {
return calculateASTandInform(input, selection, monitor);
}
}
};
fCurrentJob.setPriority(Job.DECORATE);
fCurrentJob.setSystem(true);
fCurrentJob.schedule();
}
protected IStatus calculateASTandInform(IJavaScriptElement input, ITextSelection selection, IProgressMonitor monitor) {
if (monitor.isCanceled()) {
return Status.CANCEL_STATUS;
}
// create AST
try {
JavaScriptUnit astRoot= JavaScriptPlugin.getDefault().getASTProvider().getAST(input, ASTProvider.WAIT_ACTIVE_ONLY, monitor);
if (astRoot != null && !monitor.isCanceled()) {
Object[] listeners;
synchronized (PartListenerGroup.this) {
listeners= fAstListeners.getListeners();
}
for (int i= 0; i < listeners.length; i++) {
((ISelectionListenerWithAST) listeners[i]).selectionChanged(fPart, selection, 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 fListenerGroups;
private SelectionListenerWithASTManager() {
fListenerGroups= new HashMap();
}
/**
* 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= (PartListenerGroup) 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= (PartListenerGroup) fListenerGroups.get(part);
if (partListener != null) {
partListener.uninstall(listener);
if (partListener.isEmpty()) {
fListenerGroups.remove(part);
}
}
}
}
}
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