org.eclipse.ui.workbench.texteditor/src/org/eclipse/ui/texteditor/MoveLinesAction.java - platform/eclipse.platform.text - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2009 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
  * which accompanies this distribution, and is available at
  * https://www.eclipse.org/legal/epl-2.0/
  *
  * SPDX-License-Identifier: EPL-2.0
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *     Tom Eicher (Avaloq Evolution AG) - block selection mode
  *******************************************************************************/
 package org.eclipse.ui.texteditor;

 import java.util.ResourceBundle;

 import org.eclipse.swt.custom.StyledText;
 import org.eclipse.swt.widgets.Event;

 import org.eclipse.core.runtime.Assert;

 import org.eclipse.jface.text.BadLocationException;
 import org.eclipse.jface.text.IDocument;
 import org.eclipse.jface.text.IRegion;
 import org.eclipse.jface.text.IRewriteTarget;
 import org.eclipse.jface.text.ITextSelection;
 import org.eclipse.jface.text.ITextViewer;
 import org.eclipse.jface.text.ITextViewerExtension5;
 import org.eclipse.jface.text.TextSelection;
 import org.eclipse.jface.text.TextUtilities;

 import org.eclipse.ui.internal.texteditor.CompoundEditExitStrategy;

 /**
  * Action for moving selected lines in an editor.
  * @since 3.0
  */
 public class MoveLinesAction extends TextEditorAction {

 	/* configuration variables - define what this action does */

 	/** <code>true</code> if lines are shifted upwards, <code>false</code> otherwise. */
 	private final boolean fUpwards;
 	/** <code>true</code> if lines are to be copied instead of moved. */
 	private final boolean fCopy;
 	/**
 	 * The text viewer we are working on.
 	 * @since 3.5
 	 */
 	private ITextViewer fTextViewer;

 	/* compound members of this action */

 	/**
 	 * The exit strategy that will detect the ending of a compound edit.
 	 * @since 3.1
 	 */
 	private final CompoundEditExitStrategy fStrategy;

 	/* process variables - may change in every run() */

 	/**
 	 * Set to <code>true</code> by <code>getMovingSelection</code> if the resulting selection
 	 * should include the last delimiter.
 	 */
 	private boolean fAddDelimiter;
 	/** <code>true</code> if a compound move / copy is going on. */
 	private boolean fEditInProgress= false;

 	/**
 	 * Creates and initializes the action for the given text editor. The action configures its
 	 * visual representation from the given resource bundle.
 	 *
 	 * @param bundle the resource bundle
 	 * @param prefix a prefix to be prepended to the various resource keys (described in
 	 *            <code>ResourceAction</code> constructor), or <code>null</code> if none
 	 * @param editor the text editor
 	 * @param textViewer the text viewer
 	 * @param upwards <code>true</code>if the selected lines should be moved upwards,
 	 *            <code>false</code> if downwards
 	 * @param copy if <code>true</code>, the action will copy lines instead of moving them
 	 * @see TextEditorAction#TextEditorAction(ResourceBundle, String, ITextEditor)
 	 * @since 3.5
 	 */
 	public MoveLinesAction(ResourceBundle bundle, String prefix, ITextEditor editor, ITextViewer textViewer, boolean upwards, boolean copy) {
 		super(bundle, prefix, editor);
 		fTextViewer= textViewer;
 		fUpwards= upwards;
 		fCopy= copy;
 		String[] commandIds= copy ? new String[] {ITextEditorActionDefinitionIds.COPY_LINES_UP, ITextEditorActionDefinitionIds.COPY_LINES_DOWN } : new String[] {ITextEditorActionDefinitionIds.MOVE_LINES_UP, ITextEditorActionDefinitionIds.MOVE_LINES_DOWN };
 		fStrategy= new CompoundEditExitStrategy(commandIds);
 		fStrategy.addCompoundListener(MoveLinesAction.this::endCompoundEdit);
 		update();
 	}

 	/**
 	 * Creates and initializes the action for the given text editor. The action configures its
 	 * visual representation from the given resource bundle.
 	 *
 	 * @param bundle the resource bundle
 	 * @param prefix a prefix to be prepended to the various resource keys (described in
 	 *            <code>ResourceAction</code> constructor), or <code>null</code> if none
 	 * @param editor the text editor
 	 * @param upwards <code>true</code>if the selected lines should be moved upwards,
 	 *            <code>false</code> if downwards
 	 * @param copy if <code>true</code>, the action will copy lines instead of moving them
 	 * @see TextEditorAction#TextEditorAction(ResourceBundle, String, ITextEditor)
 	 * @deprecated As of 3.5, replaced by
 	 *             {@link #MoveLinesAction(ResourceBundle, String, ITextEditor, ITextViewer, boolean, boolean)}
 	 */
 	@Deprecated
 	public MoveLinesAction(ResourceBundle bundle, String prefix, AbstractTextEditor editor, boolean upwards, boolean copy) {
 		this(bundle, prefix, editor, editor != null ? editor.getSourceViewer() : null, upwards, copy);
 	}

 	/**
 	 * Ends the compound change.
 	 */
 	private void beginCompoundEdit() {
 		ITextEditor editor= getTextEditor();
 		if (fEditInProgress || fTextViewer == null || editor == null)
 			return;

 		fEditInProgress= true;

 		fStrategy.arm(fTextViewer);

 		IRewriteTarget target= editor.getAdapter(IRewriteTarget.class);
 		if (target != null) {
 			target.beginCompoundChange();
 		}
 	}

 	/**
 	 * Checks if <code>selection</code> is contained by the visible region of <code>viewer</code>.
 	 * As a special case, a selection is considered contained even if it extends over the visible
 	 * region, but the extension stays on a partially contained line and contains only white space.
 	 *
 	 * @param selection the selection to be checked
 	 * @param viewer the viewer displaying a visible region of <code>selection</code>'s document.
 	 * @return <code>true</code>, if <code>selection</code> is contained, <code>false</code> otherwise.
 	 */
 	private boolean containedByVisibleRegion(ITextSelection selection, ITextViewer viewer) {
 		int min= selection.getOffset();
 		int max= min + selection.getLength();
 		IDocument document= viewer.getDocument();

 		IRegion visible;
 		if (viewer instanceof ITextViewerExtension5)
 			visible= ((ITextViewerExtension5) viewer).getModelCoverage();
 		else
 			visible= viewer.getVisibleRegion();

 		int visOffset= visible.getOffset();
 		try {
 			if (visOffset > min) {
 				if (document.getLineOfOffset(visOffset) != selection.getStartLine())
 					return false;
 				if (!isWhitespace(document.get(min, visOffset - min))) {
 					showStatus();
 					return false;
 				}
 			}
 			int visEnd= visOffset + visible.getLength();
 			if (visEnd < max) {
 				if (document.getLineOfOffset(visEnd) != selection.getEndLine())
 					return false;
 				if (!isWhitespace(document.get(visEnd, max - visEnd))) {
 					showStatus();
 					return false;
 				}
 			}
 			return true;
 		} catch (BadLocationException e) {
 		}
 		return false;
 	}

 	/**
 	 * Ends the compound change.
 	 */
 	private void endCompoundEdit() {
 		ITextEditor editor= getTextEditor();
 		if (!fEditInProgress || editor == null)
 			return;

 		IRewriteTarget target= editor.getAdapter(IRewriteTarget.class);
 		if (target != null) {
 			target.endCompoundChange();
 		}

 		fEditInProgress= false;
 	}

 	/**
 	 * Given a selection on a document, computes the lines fully or partially covered by
 	 * <code>selection</code>. A line in the document is considered covered if
 	 * <code>selection</code> comprises any characters on it, including the terminating delimiter.
 	 * <p>Note that the last line in a selection is not considered covered if the selection only
 	 * comprises the line delimiter at its beginning (that is considered part of the second last
 	 * line).
 	 * As a special case, if the selection is empty, a line is considered covered if the caret is
 	 * at any position in the line, including between the delimiter and the start of the line. The
 	 * line containing the delimiter is not considered covered in that case.
 	 * </p>
 	 *
 	 * @param document the document <code>selection</code> refers to
 	 * @param selection a selection on <code>document</code>
 	 * @param viewer the <code>ISourceViewer</code> displaying <code>document</code>
 	 * @return a selection describing the range of lines (partially) covered by
 	 * <code>selection</code>, without any terminating line delimiters
 	 * @throws BadLocationException if the selection is out of bounds (when the underlying document has changed during the call)
 	 */
 	private ITextSelection getMovingSelection(IDocument document, ITextSelection selection, ITextViewer viewer) throws BadLocationException {
 		int low= document.getLineOffset(selection.getStartLine());
 		int endLine= selection.getEndLine();
 		int high= document.getLineOffset(endLine) + document.getLineLength(endLine);

 		// get everything up to last line without its delimiter
 		String delim= document.getLineDelimiter(endLine);
 		if (delim != null)
 			high -= delim.length();

 		// the new selection will cover the entire lines being moved, except for the last line's
 		// delimiter. The exception to this rule is an empty last line, which will stay covered
 		// including its delimiter
 		if (delim != null && document.getLineLength(endLine) == delim.length())
 			fAddDelimiter= true;
 		else
 			fAddDelimiter= false;

 		return new TextSelection(document, low, high - low);
 	}

 	/**
 	 * Computes the region of the skipped line given the text block to be moved. If
 	 * <code>fUpwards</code> is <code>true</code>, the line above <code>selection</code>
 	 * is selected, otherwise the line below.
 	 *
 	 * @param document the document <code>selection</code> refers to
 	 * @param selection the selection on <code>document</code> that will be moved.
 	 * @return the region comprising the line that <code>selection</code> will be moved over, without its terminating delimiter.
 	 */
 	private ITextSelection getSkippedLine(IDocument document, ITextSelection selection) {
 		int skippedLineN= (fUpwards ? selection.getStartLine() - 1 : selection.getEndLine() + 1);
 		if (skippedLineN > document.getNumberOfLines() || (!fCopy && (skippedLineN < 0 ||  skippedLineN == document.getNumberOfLines())))
 			return null;
 		try {
 			if (fCopy && skippedLineN == -1)
 				skippedLineN= 0;
 			IRegion line= document.getLineInformation(skippedLineN);
 			return new TextSelection(document, line.getOffset(), line.getLength());
 		} catch (BadLocationException e) {
 			// only happens on concurrent modifications
 			return null;
 		}
 	}

 	/**
 	 * Checks for white space in a string.
 	 *
 	 * @param string the string to be checked or <code>null</code>
 	 * @return <code>true</code> if <code>string</code> contains only white space or is
 	 * <code>null</code>, <code>false</code> otherwise
 	 */
 	private boolean isWhitespace(String string) {
 		return string == null ? true : string.trim().isEmpty();
 	}

 	/*
 	 * @see org.eclipse.jface.action.IAction#run()
 	 */
 	@Override
 	public void runWithEvent(Event event) {
 		if (fTextViewer == null)
 			return;

 		if (!validateEditorInputState())
 			return;

 		// get involved objects

 		IDocument document= fTextViewer.getDocument();
 		if (document == null)
 			return;

 		StyledText widget= fTextViewer.getTextWidget();
 		if (widget == null)
 			return;

 		// get selection
 		ITextSelection sel= (ITextSelection) fTextViewer.getSelectionProvider().getSelection();
 		if (sel.isEmpty())
 			return;

 		ITextSelection skippedLine= getSkippedLine(document, sel);
 		if (skippedLine == null)
 			return;

 		try {

 			ITextSelection movingArea= getMovingSelection(document, sel, fTextViewer);

 			// if either the skipped line or the moving lines are outside the widget's
 			// visible area, bail out
 			if (!containedByVisibleRegion(movingArea, fTextViewer) || !containedByVisibleRegion(skippedLine, fTextViewer))
 				return;

 			// get the content to be moved around: the moving (selected) area and the skipped line
 			String moving= movingArea.getText();
 			String skipped= skippedLine.getText();
 			if (moving == null || skipped == null || document.getLength() == 0)
 				return;

 			String delim;
 			String insertion;
 			int offset, deviation;
 			if (fUpwards) {
 				delim= document.getLineDelimiter(skippedLine.getEndLine());
 				if (fCopy) {
 					delim= TextUtilities.getDefaultLineDelimiter(document);
 					insertion= moving + delim;
 					offset= movingArea.getOffset();
 					deviation= 0;
 				} else {
 					Assert.isNotNull(delim);
 					insertion= moving + delim + skipped;
 					offset= skippedLine.getOffset();
 					deviation= -skippedLine.getLength() - delim.length();
 				}
 			} else {
 				delim= document.getLineDelimiter(movingArea.getEndLine());
 				if (fCopy) {
 					if (delim == null) {
 						delim= TextUtilities.getDefaultLineDelimiter(document);
 						insertion= delim + moving;
 					} else {
 						insertion= moving + delim;
 					}
 					offset= skippedLine.getOffset();
 					deviation= movingArea.getLength() + delim.length();
 				} else {
 					Assert.isNotNull(delim);
 					insertion= skipped + delim + moving;
 					offset= movingArea.getOffset();
 					deviation= skipped.length() + delim.length();
 				}
 			}

 			// modify the document
 			beginCompoundEdit();
 			if (fCopy) {
 //				fDescription= new EditDescription(offset, 0, insertion.length());
 				document.replace(offset, 0, insertion);
 			} else {
 //				fDescription= new EditDescription(offset, insertion.length(), insertion.length());
 				document.replace(offset, insertion.length(), insertion);
 			}

 			// move the selection along
 			int selOffset= movingArea.getOffset() + deviation;
 			int selLength= movingArea.getLength() + (fAddDelimiter ? delim.length() : 0);
 			if (! (fTextViewer instanceof ITextViewerExtension5))
 				selLength= Math.min(selLength, fTextViewer.getVisibleRegion().getOffset() + fTextViewer.getVisibleRegion().getLength() - selOffset);
 			else {
 				// TODO need to check what is necessary in the projection case
 			}
 			selectAndReveal(fTextViewer, selOffset, selLength);
 		} catch (BadLocationException x) {
 			// won't happen without concurrent modification - bail out
 			return;
 		}
 	}

 	/**
 	 * Performs similar to AbstractTextEditor.selectAndReveal, but does not update
 	 * the viewers highlight area.
 	 *
 	 * @param viewer the viewer that we want to select on
 	 * @param offset the offset of the selection
 	 * @param length the length of the selection
 	 */
 	private void selectAndReveal(ITextViewer viewer, int offset, int length) {
 		// invert selection to avoid jumping to the end of the selection in st.showSelection()
 		viewer.setSelectedRange(offset + length, -length);
 		//viewer.revealRange(offset, length); // will trigger jumping
 		StyledText st= viewer.getTextWidget();
 		if (st != null)
 			st.showSelection(); // only minimal scrolling
 	}

 	/**
 	 * Displays information in the status line why a line move is not possible
 	 */
 	private void showStatus() {
 		ITextEditor editor= getTextEditor();
 		if (editor == null)
 			return;

 		IEditorStatusLine status= editor.getAdapter(IEditorStatusLine.class);
 		if (status == null)
 			return;
 		status.setMessage(false, EditorMessages.Editor_MoveLines_IllegalMove_status, null);
 	}

 	@Override
 	public void setEditor(ITextEditor editor) {
 		ITextEditor currentEditor= getTextEditor();
 		if (currentEditor != editor && currentEditor != null && editor != null) {
 			if (editor instanceof AbstractTextEditor)
 				fTextViewer= ((AbstractTextEditor)editor).getSourceViewer();
 			else
 				fTextViewer= null;
 		}
 		super.setEditor(editor);
 	}

 	@Override
 	public void update() {
 		super.update();

 		if (isEnabled())
 			setEnabled(canModifyEditor() && fTextViewer != null);

 	}
 }
	/*******************************************************************************
	* Copyright (c) 2000, 2009 IBM Corporation and others.
	*
	* This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License 2.0
	* which accompanies this distribution, and is available at
	* https://www.eclipse.org/legal/epl-2.0/
	*
	* SPDX-License-Identifier: EPL-2.0
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	* Tom Eicher (Avaloq Evolution AG) - block selection mode
	*******************************************************************************/
	package org.eclipse.ui.texteditor;

	import java.util.ResourceBundle;

	import org.eclipse.swt.custom.StyledText;
	import org.eclipse.swt.widgets.Event;

	import org.eclipse.core.runtime.Assert;

	import org.eclipse.jface.text.BadLocationException;
	import org.eclipse.jface.text.IDocument;
	import org.eclipse.jface.text.IRegion;
	import org.eclipse.jface.text.IRewriteTarget;
	import org.eclipse.jface.text.ITextSelection;
	import org.eclipse.jface.text.ITextViewer;
	import org.eclipse.jface.text.ITextViewerExtension5;
	import org.eclipse.jface.text.TextSelection;
	import org.eclipse.jface.text.TextUtilities;

	import org.eclipse.ui.internal.texteditor.CompoundEditExitStrategy;

	/**
	* Action for moving selected lines in an editor.
	* @since 3.0
	*/
	public class MoveLinesAction extends TextEditorAction {

	/* configuration variables - define what this action does */

	/** <code>true</code> if lines are shifted upwards, <code>false</code> otherwise. */
	private final boolean fUpwards;
	/** <code>true</code> if lines are to be copied instead of moved. */
	private final boolean fCopy;
	/**
	* The text viewer we are working on.
	* @since 3.5
	*/
	private ITextViewer fTextViewer;

	/* compound members of this action */

	/**
	* The exit strategy that will detect the ending of a compound edit.
	* @since 3.1
	*/
	private final CompoundEditExitStrategy fStrategy;

	/* process variables - may change in every run() */

	/**
	* Set to <code>true</code> by <code>getMovingSelection</code> if the resulting selection
	* should include the last delimiter.
	*/
	private boolean fAddDelimiter;
	/** <code>true</code> if a compound move / copy is going on. */
	private boolean fEditInProgress= false;

	/**
	* Creates and initializes the action for the given text editor. The action configures its
	* visual representation from the given resource bundle.
	*
	* @param bundle the resource bundle
	* @param prefix a prefix to be prepended to the various resource keys (described in
	* <code>ResourceAction</code> constructor), or <code>null</code> if none
	* @param editor the text editor
	* @param textViewer the text viewer
	* @param upwards <code>true</code>if the selected lines should be moved upwards,
	* <code>false</code> if downwards
	* @param copy if <code>true</code>, the action will copy lines instead of moving them
	* @see TextEditorAction#TextEditorAction(ResourceBundle, String, ITextEditor)
	* @since 3.5
	*/
	public MoveLinesAction(ResourceBundle bundle, String prefix, ITextEditor editor, ITextViewer textViewer, boolean upwards, boolean copy) {
	super(bundle, prefix, editor);
	fTextViewer= textViewer;
	fUpwards= upwards;
	fCopy= copy;
	String[] commandIds= copy ? new String[] {ITextEditorActionDefinitionIds.COPY_LINES_UP, ITextEditorActionDefinitionIds.COPY_LINES_DOWN } : new String[] {ITextEditorActionDefinitionIds.MOVE_LINES_UP, ITextEditorActionDefinitionIds.MOVE_LINES_DOWN };
	fStrategy= new CompoundEditExitStrategy(commandIds);
	fStrategy.addCompoundListener(MoveLinesAction.this::endCompoundEdit);
	update();
	}

	/**
	* Creates and initializes the action for the given text editor. The action configures its
	* visual representation from the given resource bundle.
	*
	* @param bundle the resource bundle
	* @param prefix a prefix to be prepended to the various resource keys (described in
	* <code>ResourceAction</code> constructor), or <code>null</code> if none
	* @param editor the text editor
	* @param upwards <code>true</code>if the selected lines should be moved upwards,
	* <code>false</code> if downwards
	* @param copy if <code>true</code>, the action will copy lines instead of moving them
	* @see TextEditorAction#TextEditorAction(ResourceBundle, String, ITextEditor)
	* @deprecated As of 3.5, replaced by
	* {@link #MoveLinesAction(ResourceBundle, String, ITextEditor, ITextViewer, boolean, boolean)}
	*/
	@Deprecated
	public MoveLinesAction(ResourceBundle bundle, String prefix, AbstractTextEditor editor, boolean upwards, boolean copy) {
	this(bundle, prefix, editor, editor != null ? editor.getSourceViewer() : null, upwards, copy);
	}

	/**
	* Ends the compound change.
	*/
	private void beginCompoundEdit() {
	ITextEditor editor= getTextEditor();
	if (fEditInProgress \|\| fTextViewer == null \|\| editor == null)
	return;

	fEditInProgress= true;

	fStrategy.arm(fTextViewer);

	IRewriteTarget target= editor.getAdapter(IRewriteTarget.class);
	if (target != null) {
	target.beginCompoundChange();
	}
	}

	/**
	* Checks if <code>selection</code> is contained by the visible region of <code>viewer</code>.
	* As a special case, a selection is considered contained even if it extends over the visible
	* region, but the extension stays on a partially contained line and contains only white space.
	*
	* @param selection the selection to be checked
	* @param viewer the viewer displaying a visible region of <code>selection</code>'s document.
	* @return <code>true</code>, if <code>selection</code> is contained, <code>false</code> otherwise.
	*/
	private boolean containedByVisibleRegion(ITextSelection selection, ITextViewer viewer) {
	int min= selection.getOffset();
	int max= min + selection.getLength();
	IDocument document= viewer.getDocument();

	IRegion visible;
	if (viewer instanceof ITextViewerExtension5)
	visible= ((ITextViewerExtension5) viewer).getModelCoverage();
	else
	visible= viewer.getVisibleRegion();

	int visOffset= visible.getOffset();
	try {
	if (visOffset > min) {
	if (document.getLineOfOffset(visOffset) != selection.getStartLine())
	return false;
	if (!isWhitespace(document.get(min, visOffset - min))) {
	showStatus();
	return false;
	}
	}
	int visEnd= visOffset + visible.getLength();
	if (visEnd < max) {
	if (document.getLineOfOffset(visEnd) != selection.getEndLine())
	return false;
	if (!isWhitespace(document.get(visEnd, max - visEnd))) {
	showStatus();
	return false;
	}
	}
	return true;
	} catch (BadLocationException e) {
	}
	return false;
	}

	/**
	* Ends the compound change.
	*/
	private void endCompoundEdit() {
	ITextEditor editor= getTextEditor();
	if (!fEditInProgress \|\| editor == null)
	return;

	IRewriteTarget target= editor.getAdapter(IRewriteTarget.class);
	if (target != null) {
	target.endCompoundChange();
	}

	fEditInProgress= false;
	}

	/**
	* Given a selection on a document, computes the lines fully or partially covered by
	* <code>selection</code>. A line in the document is considered covered if
	* <code>selection</code> comprises any characters on it, including the terminating delimiter.
	* <p>Note that the last line in a selection is not considered covered if the selection only
	* comprises the line delimiter at its beginning (that is considered part of the second last
	* line).
	* As a special case, if the selection is empty, a line is considered covered if the caret is
	* at any position in the line, including between the delimiter and the start of the line. The
	* line containing the delimiter is not considered covered in that case.
	* </p>
	*
	* @param document the document <code>selection</code> refers to
	* @param selection a selection on <code>document</code>
	* @param viewer the <code>ISourceViewer</code> displaying <code>document</code>
	* @return a selection describing the range of lines (partially) covered by
	* <code>selection</code>, without any terminating line delimiters
	* @throws BadLocationException if the selection is out of bounds (when the underlying document has changed during the call)
	*/
	private ITextSelection getMovingSelection(IDocument document, ITextSelection selection, ITextViewer viewer) throws BadLocationException {
	int low= document.getLineOffset(selection.getStartLine());
	int endLine= selection.getEndLine();
	int high= document.getLineOffset(endLine) + document.getLineLength(endLine);

	// get everything up to last line without its delimiter
	String delim= document.getLineDelimiter(endLine);
	if (delim != null)
	high -= delim.length();

	// the new selection will cover the entire lines being moved, except for the last line's
	// delimiter. The exception to this rule is an empty last line, which will stay covered
	// including its delimiter
	if (delim != null && document.getLineLength(endLine) == delim.length())
	fAddDelimiter= true;
	else
	fAddDelimiter= false;

	return new TextSelection(document, low, high - low);
	}

	/**
	* Computes the region of the skipped line given the text block to be moved. If
	* <code>fUpwards</code> is <code>true</code>, the line above <code>selection</code>
	* is selected, otherwise the line below.
	*
	* @param document the document <code>selection</code> refers to
	* @param selection the selection on <code>document</code> that will be moved.
	* @return the region comprising the line that <code>selection</code> will be moved over, without its terminating delimiter.
	*/
	private ITextSelection getSkippedLine(IDocument document, ITextSelection selection) {
	int skippedLineN= (fUpwards ? selection.getStartLine() - 1 : selection.getEndLine() + 1);
	if (skippedLineN > document.getNumberOfLines() \|\| (!fCopy && (skippedLineN < 0 \|\| skippedLineN == document.getNumberOfLines())))
	return null;
	try {
	if (fCopy && skippedLineN == -1)
	skippedLineN= 0;
	IRegion line= document.getLineInformation(skippedLineN);
	return new TextSelection(document, line.getOffset(), line.getLength());
	} catch (BadLocationException e) {
	// only happens on concurrent modifications
	return null;
	}
	}

	/**
	* Checks for white space in a string.
	*
	* @param string the string to be checked or <code>null</code>
	* @return <code>true</code> if <code>string</code> contains only white space or is
	* <code>null</code>, <code>false</code> otherwise
	*/
	private boolean isWhitespace(String string) {
	return string == null ? true : string.trim().isEmpty();
	}

	/*
	* @see org.eclipse.jface.action.IAction#run()
	*/
	@Override
	public void runWithEvent(Event event) {
	if (fTextViewer == null)
	return;

	if (!validateEditorInputState())
	return;

	// get involved objects

	IDocument document= fTextViewer.getDocument();
	if (document == null)
	return;

	StyledText widget= fTextViewer.getTextWidget();
	if (widget == null)
	return;

	// get selection
	ITextSelection sel= (ITextSelection) fTextViewer.getSelectionProvider().getSelection();
	if (sel.isEmpty())
	return;

	ITextSelection skippedLine= getSkippedLine(document, sel);
	if (skippedLine == null)
	return;

	try {

	ITextSelection movingArea= getMovingSelection(document, sel, fTextViewer);

	// if either the skipped line or the moving lines are outside the widget's
	// visible area, bail out
	if (!containedByVisibleRegion(movingArea, fTextViewer) \|\| !containedByVisibleRegion(skippedLine, fTextViewer))
	return;

	// get the content to be moved around: the moving (selected) area and the skipped line
	String moving= movingArea.getText();
	String skipped= skippedLine.getText();
	if (moving == null \|\| skipped == null \|\| document.getLength() == 0)
	return;

	String delim;
	String insertion;
	int offset, deviation;
	if (fUpwards) {
	delim= document.getLineDelimiter(skippedLine.getEndLine());
	if (fCopy) {
	delim= TextUtilities.getDefaultLineDelimiter(document);
	insertion= moving + delim;
	offset= movingArea.getOffset();
	deviation= 0;
	} else {
	Assert.isNotNull(delim);
	insertion= moving + delim + skipped;
	offset= skippedLine.getOffset();
	deviation= -skippedLine.getLength() - delim.length();
	}
	} else {
	delim= document.getLineDelimiter(movingArea.getEndLine());
	if (fCopy) {
	if (delim == null) {
	delim= TextUtilities.getDefaultLineDelimiter(document);
	insertion= delim + moving;
	} else {
	insertion= moving + delim;
	}
	offset= skippedLine.getOffset();
	deviation= movingArea.getLength() + delim.length();
	} else {
	Assert.isNotNull(delim);
	insertion= skipped + delim + moving;
	offset= movingArea.getOffset();
	deviation= skipped.length() + delim.length();
	}
	}

	// modify the document
	beginCompoundEdit();
	if (fCopy) {
	// fDescription= new EditDescription(offset, 0, insertion.length());
	document.replace(offset, 0, insertion);
	} else {
	// fDescription= new EditDescription(offset, insertion.length(), insertion.length());
	document.replace(offset, insertion.length(), insertion);
	}

	// move the selection along
	int selOffset= movingArea.getOffset() + deviation;
	int selLength= movingArea.getLength() + (fAddDelimiter ? delim.length() : 0);
	if (! (fTextViewer instanceof ITextViewerExtension5))
	selLength= Math.min(selLength, fTextViewer.getVisibleRegion().getOffset() + fTextViewer.getVisibleRegion().getLength() - selOffset);
	else {
	// TODO need to check what is necessary in the projection case
	}
	selectAndReveal(fTextViewer, selOffset, selLength);
	} catch (BadLocationException x) {
	// won't happen without concurrent modification - bail out
	return;
	}
	}

	/**
	* Performs similar to AbstractTextEditor.selectAndReveal, but does not update
	* the viewers highlight area.
	*
	* @param viewer the viewer that we want to select on
	* @param offset the offset of the selection
	* @param length the length of the selection
	*/
	private void selectAndReveal(ITextViewer viewer, int offset, int length) {
	// invert selection to avoid jumping to the end of the selection in st.showSelection()
	viewer.setSelectedRange(offset + length, -length);
	//viewer.revealRange(offset, length); // will trigger jumping
	StyledText st= viewer.getTextWidget();
	if (st != null)
	st.showSelection(); // only minimal scrolling
	}

	/**
	* Displays information in the status line why a line move is not possible
	*/
	private void showStatus() {
	ITextEditor editor= getTextEditor();
	if (editor == null)
	return;

	IEditorStatusLine status= editor.getAdapter(IEditorStatusLine.class);
	if (status == null)
	return;
	status.setMessage(false, EditorMessages.Editor_MoveLines_IllegalMove_status, null);
	}

	@Override
	public void setEditor(ITextEditor editor) {
	ITextEditor currentEditor= getTextEditor();
	if (currentEditor != editor && currentEditor != null && editor != null) {
	if (editor instanceof AbstractTextEditor)
	fTextViewer= ((AbstractTextEditor)editor).getSourceViewer();
	else
	fTextViewer= null;
	}
	super.setEditor(editor);
	}

	@Override
	public void update() {
	super.update();

	if (isEnabled())
	setEnabled(canModifyEditor() && fTextViewer != null);

	}
	}