content: /*******************************************************************************
   * 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.javaeditor.selectionactions;
  
  import org.eclipse.ui.PlatformUI;
  import org.eclipse.wst.jsdt.core.ISourceRange;
  import org.eclipse.wst.jsdt.core.ISourceReference;
  import org.eclipse.wst.jsdt.core.JavaScriptModelException;
  import org.eclipse.wst.jsdt.core.dom.ASTNode;
  import org.eclipse.wst.jsdt.internal.corext.dom.GenericVisitor;
  import org.eclipse.wst.jsdt.internal.corext.dom.SelectionAnalyzer;
  import org.eclipse.wst.jsdt.internal.ui.IJavaHelpContextIds;
  import org.eclipse.wst.jsdt.internal.ui.javaeditor.JavaEditor;
  
  public class StructureSelectPreviousAction extends StructureSelectionAction {
  
  	private static class PreviousNodeAnalyzer extends GenericVisitor {
  		private final int fOffset;
  		private ASTNode fPreviousNode;
  		private PreviousNodeAnalyzer(int offset) {
  			super(true);
  			fOffset= offset;
  		}
  		public static ASTNode perform(int offset, ASTNode lastCoveringNode) {
  			PreviousNodeAnalyzer analyzer= new PreviousNodeAnalyzer(offset);
  			lastCoveringNode.accept(analyzer);
  			return analyzer.fPreviousNode;
  		}
  		protected boolean visitNode(ASTNode node) {
  			int start= node.getStartPosition();
  			int end= start + node.getLength();
  			if (end == fOffset) {
  				fPreviousNode= node;
  				return true;
  			} else {
  				return (start < fOffset && fOffset < end);
  			}
  		}
  	}
  
  	public StructureSelectPreviousAction(JavaEditor editor, SelectionHistory history) {
  		super(SelectionActionMessages.StructureSelectPrevious_label, editor, history);
  		setToolTipText(SelectionActionMessages.StructureSelectPrevious_tooltip);
  		setDescription(SelectionActionMessages.StructureSelectPrevious_description);
  		PlatformUI.getWorkbench().getHelpSystem().setHelp(this, IJavaHelpContextIds.STRUCTURED_SELECT_PREVIOUS_ACTION);
  	}
  
  	/*
  	 * This constructor is for testing purpose only.
  	 */
  	public StructureSelectPreviousAction() {
  	}
  
  	/* non java doc
  	 * @see StructureSelectionAction#internalGetNewSelectionRange(ISourceRange, IJavaScriptUnit, SelectionAnalyzer)
  	 */
  	ISourceRange internalGetNewSelectionRange(ISourceRange oldSourceRange, ISourceReference sr, SelectionAnalyzer selAnalyzer) throws JavaScriptModelException{
  		if (oldSourceRange.getLength() == 0 && selAnalyzer.getLastCoveringNode() != null) {
  			ASTNode previousNode= PreviousNodeAnalyzer.perform(oldSourceRange.getOffset(), selAnalyzer.getLastCoveringNode());
  			if (previousNode != null)
  				return getSelectedNodeSourceRange(sr, previousNode);
  		}
  		ASTNode first= selAnalyzer.getFirstSelectedNode();
  		if (first == null)
  			return getLastCoveringNodeRange(oldSourceRange, sr, selAnalyzer);
  
  		ASTNode parent= first.getParent();
  		if (parent == null)
  			return getLastCoveringNodeRange(oldSourceRange, sr, selAnalyzer);
  
  		ASTNode previousNode= getPreviousNode(parent, selAnalyzer.getSelectedNodes()[0]);
  		if (previousNode == parent)
  			return getSelectedNodeSourceRange(sr, parent);
  
  		int offset= previousNode.getStartPosition();
  		int end= oldSourceRange.getOffset() + oldSourceRange.getLength() - 1;
  		return StructureSelectionAction.createSourceRange(offset, end);
  	}
  
  	private static ASTNode getPreviousNode(ASTNode parent, ASTNode node){
  		ASTNode[] siblingNodes= StructureSelectionAction.getSiblingNodes(node);
  		if (siblingNodes == null || siblingNodes.length == 0)
  			return parent;
  		if (node == siblingNodes[0]) {
  			return parent;
  		} else {
  			int index= StructureSelectionAction.findIndex(siblingNodes, node);
  			if (index < 1)
  				return parent;
  			return siblingNodes[index - 1];
  		}
  	}
  }
  
  