org.eclipse.jdt.ui/ui refactoring/org/eclipse/jdt/internal/ui/refactoring/PreviewWizardPage.java - jdt/eclipse.jdt.ui - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2003 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.jdt.internal.ui.refactoring;

 import java.util.ArrayList;
 import java.util.List;

 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IProgressMonitor;

 import org.eclipse.swt.SWT;
 import org.eclipse.swt.custom.SashForm;
 import org.eclipse.swt.layout.GridData;
 import org.eclipse.swt.layout.GridLayout;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Label;

 import org.eclipse.jface.action.Action;
 import org.eclipse.jface.action.ToolBarManager;
 import org.eclipse.jface.dialogs.Dialog;
 import org.eclipse.jface.dialogs.IDialogConstants;
 import org.eclipse.jface.viewers.CheckStateChangedEvent;
 import org.eclipse.jface.viewers.ICheckStateListener;
 import org.eclipse.jface.viewers.ILabelProvider;
 import org.eclipse.jface.viewers.ISelectionChangedListener;
 import org.eclipse.jface.viewers.IStructuredSelection;
 import org.eclipse.jface.viewers.ITreeContentProvider;
 import org.eclipse.jface.viewers.SelectionChangedEvent;
 import org.eclipse.jface.viewers.StructuredSelection;

 import org.eclipse.ui.help.WorkbenchHelp;
 import org.eclipse.ui.part.PageBook;

 import org.eclipse.compare.CompareUI;

 import org.eclipse.jdt.core.ISourceReference;

 import org.eclipse.jdt.ui.JavaElementLabelProvider;

 import org.eclipse.jdt.internal.ui.IJavaHelpContextIds;
 import org.eclipse.jdt.internal.ui.refactoring.ComparePreviewer.CompareInput;
 import org.eclipse.jdt.internal.ui.util.ExceptionHandler;
 import org.eclipse.jdt.internal.ui.util.ViewerPane;

 import org.eclipse.jdt.internal.corext.refactoring.base.Change;
 import org.eclipse.jdt.internal.corext.refactoring.base.ChangeContext;
 import org.eclipse.jdt.internal.corext.refactoring.base.IChange;
 import org.eclipse.jdt.internal.corext.refactoring.base.ICompositeChange;
 import org.eclipse.jdt.internal.corext.refactoring.changes.CompilationUnitChange;
 import org.eclipse.jdt.internal.corext.refactoring.changes.TextChange;
 import org.eclipse.jdt.internal.corext.refactoring.changes.TextChange.EditChange;
 import org.eclipse.jdt.internal.corext.refactoring.nls.changes.CreateTextFileChange;

 /**
  * Presents the changes made by the refactoring.
  * Consists of a tree of changes and a compare viewer that shows the differences.
  */
 public class PreviewWizardPage extends RefactoringWizardPage implements IPreviewWizardPage {

 	// Dummy root node if input element isn't a composite change.
 	private static class DummyRootNode extends Change implements ICompositeChange {
 		private IChange[] fChildren;

 		public DummyRootNode(IChange change) {
 			fChildren= new IChange[] { change };
 		}
 		public IChange[] getChildren() {
 			return fChildren;
 		}
 		public String getName() {
 			return null;
 		}
 		public Object getModifiedLanguageElement() {
 			return null;
 		}
 		public IChange getUndoChange() {
 			return null;
 		}
 		public void perform(ChangeContext context, IProgressMonitor pm) {
 		}
 	}

 	private static class NullPreviewer implements IPreviewViewer {
 		private Label fLabel;
 		public NullPreviewer(Composite parent) {
 			fLabel= new Label(parent, SWT.CENTER | SWT.FLAT);
 			fLabel.setText(RefactoringMessages.getString("PreviewWizardPage.no_preview")); //$NON-NLS-1$
 		}
 		public void setInput(Object input) {
 			// do nothing
 		}
 		public void refresh() {
 			// do nothing
 		}
 		public Control getControl() {
 			return fLabel;
 		}
 	}

 	private class NextChange extends Action {
 		public NextChange() {
 			setImageDescriptor(CompareUI.DESC_ETOOL_NEXT);
 			setDisabledImageDescriptor(CompareUI.DESC_DTOOL_NEXT);
 			setHoverImageDescriptor(CompareUI.DESC_CTOOL_NEXT);
 			setToolTipText(RefactoringMessages.getString("PreviewWizardPage.next_Change")); //$NON-NLS-1$
 			WorkbenchHelp.setHelp(this, IJavaHelpContextIds.NEXT_CHANGE_ACTION);
 		}
 		public void run() {
 			fTreeViewer.revealNext();
 		}
 	}

 	private class PreviousChange extends Action {
 		public PreviousChange() {
 			setImageDescriptor(CompareUI.DESC_ETOOL_PREV);
 			setDisabledImageDescriptor(CompareUI.DESC_DTOOL_PREV);
 			setHoverImageDescriptor(CompareUI.DESC_CTOOL_PREV);
 			setToolTipText(RefactoringMessages.getString("PreviewWizardPage.previous_Change")); //$NON-NLS-1$
 			WorkbenchHelp.setHelp(this, IJavaHelpContextIds.PREVIOUS_CHANGE_ACTION);
 		}
 		public void run() {
 			fTreeViewer.revealPrevious();
 		}
 	}

 	private IChange fChange;
 	private ChangeElement fCurrentSelection;
 	private PageBook fPageContainer;
 	private Control fStandardPage;
 	private Control fNullPage;
 	private ChangeElementTreeViewer fTreeViewer;
 	private PageBook fPreviewContainer;
 	private IPreviewViewer fCurrentPreviewViewer;
 	private IPreviewViewer fNullPreviewer;
 	private ComparePreviewer fComparePreview;

 	/**
 	 * Creates a new proposed changes wizard page.
 	 */
 	public PreviewWizardPage() {
 		super(PAGE_NAME);
 		setDescription(RefactoringMessages.getString("PreviewWizardPage.description")); //$NON-NLS-1$
 	}

 	/**
 	 * Sets the given change. Setting the change initializes the tree viewer with
 	 * the given change.
 	 * @param change the new change.
 	 */
 	public void setChange(IChange change){
 		if (fChange == change)
 			return;

 		fChange= change;
 		setTreeViewerInput();
 	}

 	/**
 	 * Creates the tree viewer to present the hierarchy of changes. Subclasses may override
 	 * to create their own custom tree viewer.
 	 *
 	 * @return the tree viewer to present the hierarchy of changes
 	 */
 	protected ChangeElementTreeViewer createTreeViewer(Composite parent) {
 		return new ChangeElementTreeViewer(parent);
 	}

 	/**
 	 * Creates the content provider used to fill the tree of changes. Subclasses may override
 	 * to create their own custom tree content provider.
 	 *
 	 * @return the tree content provider used to fill the tree of changes
 	 */
 	protected ITreeContentProvider createTreeContentProvider() {
 		return new ChangeElementContentProvider();
 	}

 	/**
 	 * Creates the label provider used to render the tree of changes. Subclasses may override
 	 * to create their own custom label provider.
 	 *
 	 * @return the label provider used to render the tree of changes
 	 */
 	protected ILabelProvider createTreeLabelProvider() {
 		return new ChangeElementLabelProvider(JavaElementLabelProvider.SHOW_DEFAULT | JavaElementLabelProvider.SHOW_SMALL_ICONS);
 	}

 	/**
 	 * Returns the <code>CompareInput</code> element, if the preview for the given
 	 * <code>ChangeElement</code> can be presented in a compare viewer. The method
 	 * may return <code>null</code> indicating that the preview cannot be displayed using
 	 * a compare viewer.
 	 * <p>
 	 * Subclasses may override to provide their own input element.
 	 *
 	 * @return the compare input if the preview for the given change element can be
 	 * 	presented using a compare viewer; otherwise <code>null</code>.
 	 */
 	protected CompareInput getCompareInput(ChangeElement element) {
 		try {
 			if (element instanceof DefaultChangeElement) {
 				IChange change= ((DefaultChangeElement)element).getChange();
 				if (change instanceof TextChange) {
 					TextChange cuc= (TextChange)change;
 					String type= ComparePreviewer.TEXT_TYPE;
 					if (change instanceof CompilationUnitChange)
 						type= ComparePreviewer.JAVA_TYPE;
 					return createCompareInput(
 						element,
 						cuc.getCurrentContent(),
 						cuc.getPreviewContent(),
 						type);
 				} else if (change instanceof CreateTextFileChange){
 					CreateTextFileChange ctfc= (CreateTextFileChange)change;
 					String type= ctfc.isJavaFile() ? ComparePreviewer.JAVA_TYPE: ComparePreviewer.TEXT_TYPE;
 					return createCompareInput(
 						element,
 						ctfc.getCurrentContent(),
 						ctfc.getPreview(),
 						type);
 				}
 			} else if (element instanceof TextEditChangeElement) {
 				EditChange tec= ((TextEditChangeElement)element).getTextEditChange();
 				TextChange change= tec.getTextChange();
 				if (change instanceof CompilationUnitChange) {
 					ISourceReference sourceReference= findSourceReference(element);
 					if (sourceReference != null) {
 						CompilationUnitChange cuc= (CompilationUnitChange)change;
 						return createCompareInput(
 							element,
 							cuc.getCurrentContent(sourceReference),
 							cuc.getPreviewContent(sourceReference, new EditChange[] {tec}),
 							ComparePreviewer.JAVA_TYPE);
 					}
 				}
 				return createCompareInput(
 					element,
 					change.getCurrentContent(tec, 2),
 					change.getPreviewContent(tec, 2),
 					ComparePreviewer.TEXT_TYPE);
 			} else if (element instanceof PseudoJavaChangeElement) {
 				PseudoJavaChangeElement pjce= (PseudoJavaChangeElement)element;
 				List l= collectTextEditChanges(pjce);
 				if (l.size() > 0) {
 					EditChange[] changes= (EditChange[]) l.toArray(new EditChange[l.size()]);
 					CompilationUnitChange change= (CompilationUnitChange)changes[0].getTextChange();
 					ISourceReference sourceReference= (ISourceReference)pjce.getJavaElement();
 					return createCompareInput(
 						element,
 						change.getCurrentContent(sourceReference),
 						change.getPreviewContent(sourceReference, changes),
 						ComparePreviewer.JAVA_TYPE);
 				}
 			}
 		} catch (CoreException e) {
 			ExceptionHandler.handle(e, getShell(), RefactoringMessages.getString("PreviewWizardPage.showing_preview"), RefactoringMessages.getString("PreviewWizardPage.exception")); //$NON-NLS-1$ //$NON-NLS-2$
 		}
 		return null;
 	}

 	private CompareInput createCompareInput(ChangeElement element, String left, String right, String type) {
 		if (element == null || left == null || right == null || type == null)
 			return null;
 		return new CompareInput(element, left, right, type);
 	}

 	/**
 	 * Returns a viewer used to show a preview for the given change element. The returned viewer
 	 * is kept referenced until the wizard page gets disposed. So it is up to the implementor of this
 	 * method to reuse existing viewers over different change elements. The method may return
 	 * <code>nulll</code> indicating that no preview is available for the given change element.
 	 * <p>
 	 * Subclasses may override to provide their own preview.
 	 *
 	 * @param element the change element for which a preview control is requested
 	 * @param currentViewer the currently used preview viewer
 	 * @param parent the parent to be used if a new preview viewer must be created
 	 * @return the viewer to show a preview for the given change element
 	 */
 	protected IPreviewViewer getPreviewer(ChangeElement element, IPreviewViewer currentViewer, Composite parent) {
 		CompareInput input= getCompareInput(element);
 		if (input != null) {
 			fComparePreview.setInput(input);
 			return fComparePreview;
 		}
 		return null;
 	}

 	/* (non-JavaDoc)
 	 * Method defined in RefactoringWizardPage
 	 */
 	protected boolean performFinish() {
 		return getRefactoringWizard().performFinish(new PerformChangeOperation(fChange));
 	}

 	/* (non-JavaDoc)
 	 * Method defined in IWizardPage
 	 */
 	public boolean canFlipToNextPage() {
 		return false;
 	}

 	/* (Non-JavaDoc)
 	 * Method defined in IWizardPage
 	 */
 	public void createControl(Composite parent) {
 		initializeDialogUnits(parent);
 		fPageContainer= new PageBook(parent, SWT.NONE);
 		fStandardPage= createStandardPreviewPage(fPageContainer);
 		fNullPage= createNullPage(fPageContainer);
 		setControl(fPageContainer);
 		WorkbenchHelp.setHelp(getControl(), IJavaHelpContextIds.REFACTORING_PREVIEW_WIZARD_PAGE);
 	}

 	private Composite createStandardPreviewPage(Composite parent) {
 		// XXX The composite is needed to limit the width of the SashForm. See http://bugs.eclipse.org/bugs/show_bug.cgi?id=6854
 		Composite result= new Composite(parent, SWT.NONE);
 		GridLayout layout= new GridLayout();
 		layout.marginHeight= 0; layout.marginWidth= 0;
 		result.setLayout(layout);

 		SashForm sashForm= new SashForm(result, SWT.VERTICAL);

 		ViewerPane pane= new ViewerPane(sashForm, SWT.BORDER | SWT.FLAT);
 		pane.setText(RefactoringMessages.getString("PreviewWizardPage.changes")); //$NON-NLS-1$
 		ToolBarManager tbm= pane.getToolBarManager();
 		tbm.add(new NextChange());
 		tbm.add(new PreviousChange());
 		tbm.update(true);

 		fTreeViewer= createTreeViewer(pane);
 		fTreeViewer.setContentProvider(createTreeContentProvider());
 		fTreeViewer.setLabelProvider(createTreeLabelProvider());
 		fTreeViewer.addSelectionChangedListener(createSelectionChangedListener());
 		fTreeViewer.addCheckStateListener(createCheckStateListener());
 		pane.setContent(fTreeViewer.getControl());
 		setTreeViewerInput();

 		fPreviewContainer= new PageBook(sashForm, SWT.NONE);
 		fComparePreview= new ComparePreviewer(fPreviewContainer);
 		fNullPreviewer= new NullPreviewer(fPreviewContainer);
 		fPreviewContainer.showPage(fNullPreviewer.getControl());

 		sashForm.setWeights(new int[]{33, 67});
 		GridData gd= new GridData(GridData.FILL_BOTH);
 		gd.widthHint= convertWidthInCharsToPixels(80);
 		sashForm.setLayoutData(gd);
 		Dialog.applyDialogFont(result);
 		return result;
 	}

 	private Control createNullPage(Composite parent) {
 		Composite result= new Composite(parent, SWT.NONE);
 		GridLayout layout= new GridLayout();
 		layout.marginWidth = convertHorizontalDLUsToPixels(IDialogConstants.HORIZONTAL_MARGIN);
 		layout.marginHeight = convertVerticalDLUsToPixels(IDialogConstants.VERTICAL_MARGIN);
 		result.setLayout(layout);
 		Label label= new Label(result, SWT.CENTER);
 		label.setText(RefactoringMessages.getString("PreviewWizardPage.no_source_code_change")); //$NON-NLS-1$
 		label.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
 		Dialog.applyDialogFont(result);
 		return result;
 	}

 	/* (Non-JavaDoc)
 	 * Method defined in IWizardPage
 	 */
 	public void setVisible(boolean visible) {
 		fCurrentSelection= null;
 		if (hasChanges()) {
 			fPageContainer.showPage(fStandardPage);
 			ChangeElement treeViewerInput= (ChangeElement)fTreeViewer.getInput();
 			if (visible && treeViewerInput != null) {
 				IStructuredSelection selection= (IStructuredSelection)fTreeViewer.getSelection();
 				if (selection.isEmpty()) {
 					ITreeContentProvider provider= (ITreeContentProvider)fTreeViewer.getContentProvider();
 					Object[] elements= provider.getElements(treeViewerInput);
 					if (elements != null && elements.length > 0) {
 						Object element= elements[0];
 						if (getRefactoringWizard().getExpandFirstNode()) {
 							Object[] subElements= provider.getElements(element);
 							if (subElements != null && subElements.length > 0) {
 								fTreeViewer.expandToLevel(element, 999);
 							}
 						}
 						fTreeViewer.setSelection(new StructuredSelection(element));
 					}
 				}
 			}
 			super.setVisible(visible);
 			fTreeViewer.getControl().setFocus();
 		} else {
 			fPageContainer.showPage(fNullPage);
 			super.setVisible(visible);
 		}
 		getRefactoringWizard().setPreviewShown(visible);
 	}

 	private void setTreeViewerInput() {
 		ChangeElement input;
 		if (fChange == null) {
 			input= null;
 		} else if (fChange instanceof ICompositeChange && !(fChange instanceof TextChange)) {
 			input= new DefaultChangeElement(null, fChange);
 		} else {
 			input= new DefaultChangeElement(null, new DummyRootNode(fChange));
 		}
 		if (fTreeViewer != null) {
 			fTreeViewer.setInput(input);
 		}
 	}

 	private ICheckStateListener createCheckStateListener() {
 		return new ICheckStateListener() {
 			public void checkStateChanged(CheckStateChangedEvent event){
 				ChangeElement element= (ChangeElement)event.getElement();
 				if (isChild(fCurrentSelection, element) || isChild(element, fCurrentSelection)) {
 					showPreview(fCurrentSelection);
 				}
 			}
 			private boolean isChild(ChangeElement element, ChangeElement child) {
 				while (child != null) {
 					if (child == element)
 						return true;
 					child= child.getParent();
 				}
 				return false;
 			}
 		};
 	}

 	private ISelectionChangedListener createSelectionChangedListener() {
 		return new ISelectionChangedListener(){
 			public void selectionChanged(SelectionChangedEvent event) {
 				IStructuredSelection sel= (IStructuredSelection) event.getSelection();
 				if (sel.size() == 1) {
 					ChangeElement newSelection= (ChangeElement)sel.getFirstElement();
 					if (newSelection != fCurrentSelection) {
 						fCurrentSelection= newSelection;
 						showPreview(newSelection);
 					}
 				} else {
 					showPreview(null);
 				}
 			}
 		};
 	}

 	private void showPreview(ChangeElement element) {
 		if (element != null)
 			fCurrentPreviewViewer= getPreviewer(element, fCurrentPreviewViewer, fPreviewContainer);
 		else
 			fCurrentPreviewViewer= null;

 		if (fCurrentPreviewViewer == null)
 			fCurrentPreviewViewer= fNullPreviewer;
 		fPreviewContainer.showPage(fCurrentPreviewViewer.getControl());
 	}

 	private ISourceReference findSourceReference(ChangeElement element) {
 		if (element == null) {
 			return null;
 		} else if (element instanceof PseudoJavaChangeElement) {
 			return (ISourceReference)((PseudoJavaChangeElement)element).getJavaElement();
 		} else if (element instanceof DefaultChangeElement) {
 			IChange change= ((DefaultChangeElement)element).getChange();
 			if (change instanceof CompilationUnitChange) {
 				return ((CompilationUnitChange)change).getCompilationUnit();
 			}
 		}
 		return findSourceReference(element.getParent());
 	}

 	private List collectTextEditChanges(PseudoJavaChangeElement element) {
 		List result= new ArrayList(10);
 		ChangeElement[] children= element.getChildren();
 		for (int i= 0; i < children.length; i++) {
 			ChangeElement child= children[i];
 			if (child instanceof TextEditChangeElement) {
 				result.add(((TextEditChangeElement)child).getTextEditChange());
 			} else if (child instanceof PseudoJavaChangeElement) {
 				result.addAll(collectTextEditChanges((PseudoJavaChangeElement)child));
 			}
 		}
 		return result;
 	}

 	/**
 	 * Returns <code>true</code> if the preview page will show any changes when
 	 * it becomes visibile. Otherwise <code>false</code> is returned.
 	 */
 	public boolean hasChanges() {
 		if (fChange == null)
 			return false;
 		if (fChange instanceof ICompositeChange)
 			return ((ICompositeChange)fChange).getChildren().length > 0;
 		return true;
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2000, 2003 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.jdt.internal.ui.refactoring;

	import java.util.ArrayList;
	import java.util.List;

	import org.eclipse.core.runtime.CoreException;
	import org.eclipse.core.runtime.IProgressMonitor;

	import org.eclipse.swt.SWT;
	import org.eclipse.swt.custom.SashForm;
	import org.eclipse.swt.layout.GridData;
	import org.eclipse.swt.layout.GridLayout;
	import org.eclipse.swt.widgets.Composite;
	import org.eclipse.swt.widgets.Control;
	import org.eclipse.swt.widgets.Label;

	import org.eclipse.jface.action.Action;
	import org.eclipse.jface.action.ToolBarManager;
	import org.eclipse.jface.dialogs.Dialog;
	import org.eclipse.jface.dialogs.IDialogConstants;
	import org.eclipse.jface.viewers.CheckStateChangedEvent;
	import org.eclipse.jface.viewers.ICheckStateListener;
	import org.eclipse.jface.viewers.ILabelProvider;
	import org.eclipse.jface.viewers.ISelectionChangedListener;
	import org.eclipse.jface.viewers.IStructuredSelection;
	import org.eclipse.jface.viewers.ITreeContentProvider;
	import org.eclipse.jface.viewers.SelectionChangedEvent;
	import org.eclipse.jface.viewers.StructuredSelection;

	import org.eclipse.ui.help.WorkbenchHelp;
	import org.eclipse.ui.part.PageBook;

	import org.eclipse.compare.CompareUI;

	import org.eclipse.jdt.core.ISourceReference;

	import org.eclipse.jdt.ui.JavaElementLabelProvider;

	import org.eclipse.jdt.internal.ui.IJavaHelpContextIds;
	import org.eclipse.jdt.internal.ui.refactoring.ComparePreviewer.CompareInput;
	import org.eclipse.jdt.internal.ui.util.ExceptionHandler;
	import org.eclipse.jdt.internal.ui.util.ViewerPane;

	import org.eclipse.jdt.internal.corext.refactoring.base.Change;
	import org.eclipse.jdt.internal.corext.refactoring.base.ChangeContext;
	import org.eclipse.jdt.internal.corext.refactoring.base.IChange;
	import org.eclipse.jdt.internal.corext.refactoring.base.ICompositeChange;
	import org.eclipse.jdt.internal.corext.refactoring.changes.CompilationUnitChange;
	import org.eclipse.jdt.internal.corext.refactoring.changes.TextChange;
	import org.eclipse.jdt.internal.corext.refactoring.changes.TextChange.EditChange;
	import org.eclipse.jdt.internal.corext.refactoring.nls.changes.CreateTextFileChange;

	/**
	* Presents the changes made by the refactoring.
	* Consists of a tree of changes and a compare viewer that shows the differences.
	*/
	public class PreviewWizardPage extends RefactoringWizardPage implements IPreviewWizardPage {

	// Dummy root node if input element isn't a composite change.
	private static class DummyRootNode extends Change implements ICompositeChange {
	private IChange[] fChildren;

	public DummyRootNode(IChange change) {
	fChildren= new IChange[] { change };
	}
	public IChange[] getChildren() {
	return fChildren;
	}
	public String getName() {
	return null;
	}
	public Object getModifiedLanguageElement() {
	return null;
	}
	public IChange getUndoChange() {
	return null;
	}
	public void perform(ChangeContext context, IProgressMonitor pm) {
	}
	}

	private static class NullPreviewer implements IPreviewViewer {
	private Label fLabel;
	public NullPreviewer(Composite parent) {
	fLabel= new Label(parent, SWT.CENTER \| SWT.FLAT);
	fLabel.setText(RefactoringMessages.getString("PreviewWizardPage.no_preview")); //$NON-NLS-1$
	}
	public void setInput(Object input) {
	// do nothing
	}
	public void refresh() {
	// do nothing
	}
	public Control getControl() {
	return fLabel;
	}
	}

	private class NextChange extends Action {
	public NextChange() {
	setImageDescriptor(CompareUI.DESC_ETOOL_NEXT);
	setDisabledImageDescriptor(CompareUI.DESC_DTOOL_NEXT);
	setHoverImageDescriptor(CompareUI.DESC_CTOOL_NEXT);
	setToolTipText(RefactoringMessages.getString("PreviewWizardPage.next_Change")); //$NON-NLS-1$
	WorkbenchHelp.setHelp(this, IJavaHelpContextIds.NEXT_CHANGE_ACTION);
	}
	public void run() {
	fTreeViewer.revealNext();
	}
	}

	private class PreviousChange extends Action {
	public PreviousChange() {
	setImageDescriptor(CompareUI.DESC_ETOOL_PREV);
	setDisabledImageDescriptor(CompareUI.DESC_DTOOL_PREV);
	setHoverImageDescriptor(CompareUI.DESC_CTOOL_PREV);
	setToolTipText(RefactoringMessages.getString("PreviewWizardPage.previous_Change")); //$NON-NLS-1$
	WorkbenchHelp.setHelp(this, IJavaHelpContextIds.PREVIOUS_CHANGE_ACTION);
	}
	public void run() {
	fTreeViewer.revealPrevious();
	}
	}

	private IChange fChange;
	private ChangeElement fCurrentSelection;
	private PageBook fPageContainer;
	private Control fStandardPage;
	private Control fNullPage;
	private ChangeElementTreeViewer fTreeViewer;
	private PageBook fPreviewContainer;
	private IPreviewViewer fCurrentPreviewViewer;
	private IPreviewViewer fNullPreviewer;
	private ComparePreviewer fComparePreview;

	/**
	* Creates a new proposed changes wizard page.
	*/
	public PreviewWizardPage() {
	super(PAGE_NAME);
	setDescription(RefactoringMessages.getString("PreviewWizardPage.description")); //$NON-NLS-1$
	}

	/**
	* Sets the given change. Setting the change initializes the tree viewer with
	* the given change.
	* @param change the new change.
	*/
	public void setChange(IChange change){
	if (fChange == change)
	return;

	fChange= change;
	setTreeViewerInput();
	}

	/**
	* Creates the tree viewer to present the hierarchy of changes. Subclasses may override
	* to create their own custom tree viewer.
	*
	* @return the tree viewer to present the hierarchy of changes
	*/
	protected ChangeElementTreeViewer createTreeViewer(Composite parent) {
	return new ChangeElementTreeViewer(parent);
	}

	/**
	* Creates the content provider used to fill the tree of changes. Subclasses may override
	* to create their own custom tree content provider.
	*
	* @return the tree content provider used to fill the tree of changes
	*/
	protected ITreeContentProvider createTreeContentProvider() {
	return new ChangeElementContentProvider();
	}

	/**
	* Creates the label provider used to render the tree of changes. Subclasses may override
	* to create their own custom label provider.
	*
	* @return the label provider used to render the tree of changes
	*/
	protected ILabelProvider createTreeLabelProvider() {
	return new ChangeElementLabelProvider(JavaElementLabelProvider.SHOW_DEFAULT \| JavaElementLabelProvider.SHOW_SMALL_ICONS);
	}

	/**
	* Returns the <code>CompareInput</code> element, if the preview for the given
	* <code>ChangeElement</code> can be presented in a compare viewer. The method
	* may return <code>null</code> indicating that the preview cannot be displayed using
	* a compare viewer.
	* <p>
	* Subclasses may override to provide their own input element.
	*
	* @return the compare input if the preview for the given change element can be
	* presented using a compare viewer; otherwise <code>null</code>.
	*/
	protected CompareInput getCompareInput(ChangeElement element) {
	try {
	if (element instanceof DefaultChangeElement) {
	IChange change= ((DefaultChangeElement)element).getChange();
	if (change instanceof TextChange) {
	TextChange cuc= (TextChange)change;
	String type= ComparePreviewer.TEXT_TYPE;
	if (change instanceof CompilationUnitChange)
	type= ComparePreviewer.JAVA_TYPE;
	return createCompareInput(
	element,
	cuc.getCurrentContent(),
	cuc.getPreviewContent(),
	type);
	} else if (change instanceof CreateTextFileChange){
	CreateTextFileChange ctfc= (CreateTextFileChange)change;
	String type= ctfc.isJavaFile() ? ComparePreviewer.JAVA_TYPE: ComparePreviewer.TEXT_TYPE;
	return createCompareInput(
	element,
	ctfc.getCurrentContent(),
	ctfc.getPreview(),
	type);
	}
	} else if (element instanceof TextEditChangeElement) {
	EditChange tec= ((TextEditChangeElement)element).getTextEditChange();
	TextChange change= tec.getTextChange();
	if (change instanceof CompilationUnitChange) {
	ISourceReference sourceReference= findSourceReference(element);
	if (sourceReference != null) {
	CompilationUnitChange cuc= (CompilationUnitChange)change;
	return createCompareInput(
	element,
	cuc.getCurrentContent(sourceReference),
	cuc.getPreviewContent(sourceReference, new EditChange[] {tec}),
	ComparePreviewer.JAVA_TYPE);
	}
	}
	return createCompareInput(
	element,
	change.getCurrentContent(tec, 2),
	change.getPreviewContent(tec, 2),
	ComparePreviewer.TEXT_TYPE);
	} else if (element instanceof PseudoJavaChangeElement) {
	PseudoJavaChangeElement pjce= (PseudoJavaChangeElement)element;
	List l= collectTextEditChanges(pjce);
	if (l.size() > 0) {
	EditChange[] changes= (EditChange[]) l.toArray(new EditChange[l.size()]);
	CompilationUnitChange change= (CompilationUnitChange)changes[0].getTextChange();
	ISourceReference sourceReference= (ISourceReference)pjce.getJavaElement();
	return createCompareInput(
	element,
	change.getCurrentContent(sourceReference),
	change.getPreviewContent(sourceReference, changes),
	ComparePreviewer.JAVA_TYPE);
	}
	}
	} catch (CoreException e) {
	ExceptionHandler.handle(e, getShell(), RefactoringMessages.getString("PreviewWizardPage.showing_preview"), RefactoringMessages.getString("PreviewWizardPage.exception")); //$NON-NLS-1$ //$NON-NLS-2$
	}
	return null;
	}

	private CompareInput createCompareInput(ChangeElement element, String left, String right, String type) {
	if (element == null \|\| left == null \|\| right == null \|\| type == null)
	return null;
	return new CompareInput(element, left, right, type);
	}

	/**
	* Returns a viewer used to show a preview for the given change element. The returned viewer
	* is kept referenced until the wizard page gets disposed. So it is up to the implementor of this
	* method to reuse existing viewers over different change elements. The method may return
	* <code>nulll</code> indicating that no preview is available for the given change element.
	* <p>
	* Subclasses may override to provide their own preview.
	*
	* @param element the change element for which a preview control is requested
	* @param currentViewer the currently used preview viewer
	* @param parent the parent to be used if a new preview viewer must be created
	* @return the viewer to show a preview for the given change element
	*/
	protected IPreviewViewer getPreviewer(ChangeElement element, IPreviewViewer currentViewer, Composite parent) {
	CompareInput input= getCompareInput(element);
	if (input != null) {
	fComparePreview.setInput(input);
	return fComparePreview;
	}
	return null;
	}

	/* (non-JavaDoc)
	* Method defined in RefactoringWizardPage
	*/
	protected boolean performFinish() {
	return getRefactoringWizard().performFinish(new PerformChangeOperation(fChange));
	}

	/* (non-JavaDoc)
	* Method defined in IWizardPage
	*/
	public boolean canFlipToNextPage() {
	return false;
	}

	/* (Non-JavaDoc)
	* Method defined in IWizardPage
	*/
	public void createControl(Composite parent) {
	initializeDialogUnits(parent);
	fPageContainer= new PageBook(parent, SWT.NONE);
	fStandardPage= createStandardPreviewPage(fPageContainer);
	fNullPage= createNullPage(fPageContainer);
	setControl(fPageContainer);
	WorkbenchHelp.setHelp(getControl(), IJavaHelpContextIds.REFACTORING_PREVIEW_WIZARD_PAGE);
	}

	private Composite createStandardPreviewPage(Composite parent) {
	// XXX The composite is needed to limit the width of the SashForm. See http://bugs.eclipse.org/bugs/show_bug.cgi?id=6854
	Composite result= new Composite(parent, SWT.NONE);
	GridLayout layout= new GridLayout();
	layout.marginHeight= 0; layout.marginWidth= 0;
	result.setLayout(layout);

	SashForm sashForm= new SashForm(result, SWT.VERTICAL);

	ViewerPane pane= new ViewerPane(sashForm, SWT.BORDER \| SWT.FLAT);
	pane.setText(RefactoringMessages.getString("PreviewWizardPage.changes")); //$NON-NLS-1$
	ToolBarManager tbm= pane.getToolBarManager();
	tbm.add(new NextChange());
	tbm.add(new PreviousChange());
	tbm.update(true);

	fTreeViewer= createTreeViewer(pane);
	fTreeViewer.setContentProvider(createTreeContentProvider());
	fTreeViewer.setLabelProvider(createTreeLabelProvider());
	fTreeViewer.addSelectionChangedListener(createSelectionChangedListener());
	fTreeViewer.addCheckStateListener(createCheckStateListener());
	pane.setContent(fTreeViewer.getControl());
	setTreeViewerInput();

	fPreviewContainer= new PageBook(sashForm, SWT.NONE);
	fComparePreview= new ComparePreviewer(fPreviewContainer);
	fNullPreviewer= new NullPreviewer(fPreviewContainer);
	fPreviewContainer.showPage(fNullPreviewer.getControl());

	sashForm.setWeights(new int[]{33, 67});
	GridData gd= new GridData(GridData.FILL_BOTH);
	gd.widthHint= convertWidthInCharsToPixels(80);
	sashForm.setLayoutData(gd);
	Dialog.applyDialogFont(result);
	return result;
	}

	private Control createNullPage(Composite parent) {
	Composite result= new Composite(parent, SWT.NONE);
	GridLayout layout= new GridLayout();
	layout.marginWidth = convertHorizontalDLUsToPixels(IDialogConstants.HORIZONTAL_MARGIN);
	layout.marginHeight = convertVerticalDLUsToPixels(IDialogConstants.VERTICAL_MARGIN);
	result.setLayout(layout);
	Label label= new Label(result, SWT.CENTER);
	label.setText(RefactoringMessages.getString("PreviewWizardPage.no_source_code_change")); //$NON-NLS-1$
	label.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
	Dialog.applyDialogFont(result);
	return result;
	}

	/* (Non-JavaDoc)
	* Method defined in IWizardPage
	*/
	public void setVisible(boolean visible) {
	fCurrentSelection= null;
	if (hasChanges()) {
	fPageContainer.showPage(fStandardPage);
	ChangeElement treeViewerInput= (ChangeElement)fTreeViewer.getInput();
	if (visible && treeViewerInput != null) {
	IStructuredSelection selection= (IStructuredSelection)fTreeViewer.getSelection();
	if (selection.isEmpty()) {
	ITreeContentProvider provider= (ITreeContentProvider)fTreeViewer.getContentProvider();
	Object[] elements= provider.getElements(treeViewerInput);
	if (elements != null && elements.length > 0) {
	Object element= elements[0];
	if (getRefactoringWizard().getExpandFirstNode()) {
	Object[] subElements= provider.getElements(element);
	if (subElements != null && subElements.length > 0) {
	fTreeViewer.expandToLevel(element, 999);
	}
	}
	fTreeViewer.setSelection(new StructuredSelection(element));
	}
	}
	}
	super.setVisible(visible);
	fTreeViewer.getControl().setFocus();
	} else {
	fPageContainer.showPage(fNullPage);
	super.setVisible(visible);
	}
	getRefactoringWizard().setPreviewShown(visible);
	}

	private void setTreeViewerInput() {
	ChangeElement input;
	if (fChange == null) {
	input= null;
	} else if (fChange instanceof ICompositeChange && !(fChange instanceof TextChange)) {
	input= new DefaultChangeElement(null, fChange);
	} else {
	input= new DefaultChangeElement(null, new DummyRootNode(fChange));
	}
	if (fTreeViewer != null) {
	fTreeViewer.setInput(input);
	}
	}

	private ICheckStateListener createCheckStateListener() {
	return new ICheckStateListener() {
	public void checkStateChanged(CheckStateChangedEvent event){
	ChangeElement element= (ChangeElement)event.getElement();
	if (isChild(fCurrentSelection, element) \|\| isChild(element, fCurrentSelection)) {
	showPreview(fCurrentSelection);
	}
	}
	private boolean isChild(ChangeElement element, ChangeElement child) {
	while (child != null) {
	if (child == element)
	return true;
	child= child.getParent();
	}
	return false;
	}
	};
	}

	private ISelectionChangedListener createSelectionChangedListener() {
	return new ISelectionChangedListener(){
	public void selectionChanged(SelectionChangedEvent event) {
	IStructuredSelection sel= (IStructuredSelection) event.getSelection();
	if (sel.size() == 1) {
	ChangeElement newSelection= (ChangeElement)sel.getFirstElement();
	if (newSelection != fCurrentSelection) {
	fCurrentSelection= newSelection;
	showPreview(newSelection);
	}
	} else {
	showPreview(null);
	}
	}
	};
	}

	private void showPreview(ChangeElement element) {
	if (element != null)
	fCurrentPreviewViewer= getPreviewer(element, fCurrentPreviewViewer, fPreviewContainer);
	else
	fCurrentPreviewViewer= null;

	if (fCurrentPreviewViewer == null)
	fCurrentPreviewViewer= fNullPreviewer;
	fPreviewContainer.showPage(fCurrentPreviewViewer.getControl());
	}

	private ISourceReference findSourceReference(ChangeElement element) {
	if (element == null) {
	return null;
	} else if (element instanceof PseudoJavaChangeElement) {
	return (ISourceReference)((PseudoJavaChangeElement)element).getJavaElement();
	} else if (element instanceof DefaultChangeElement) {
	IChange change= ((DefaultChangeElement)element).getChange();
	if (change instanceof CompilationUnitChange) {
	return ((CompilationUnitChange)change).getCompilationUnit();
	}
	}
	return findSourceReference(element.getParent());
	}

	private List collectTextEditChanges(PseudoJavaChangeElement element) {
	List result= new ArrayList(10);
	ChangeElement[] children= element.getChildren();
	for (int i= 0; i < children.length; i++) {
	ChangeElement child= children[i];
	if (child instanceof TextEditChangeElement) {
	result.add(((TextEditChangeElement)child).getTextEditChange());
	} else if (child instanceof PseudoJavaChangeElement) {
	result.addAll(collectTextEditChanges((PseudoJavaChangeElement)child));
	}
	}
	return result;
	}

	/**
	* Returns <code>true</code> if the preview page will show any changes when
	* it becomes visibile. Otherwise <code>false</code> is returned.
	*/
	public boolean hasChanges() {
	if (fChange == null)
	return false;
	if (fChange instanceof ICompositeChange)
	return ((ICompositeChange)fChange).getChildren().length > 0;
	return true;
	}
	}