DeletedNode.java

/*******************************************************************************
 * Copyright (c) 2000, 2005 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.core.internal.dtree;

import org.eclipse.core.internal.utils.Messages;
import org.eclipse.core.runtime.IPath;
import org.eclipse.osgi.util.NLS;

/**
 * A <code>DeletedNode</code> represents a node that has been deleted in a 
 * <code>DeltaDataTree</code>.  It is a node that existed in the parent tree, 
 * but no longer exists in the current delta tree.  It has no children or data.
 */
public class DeletedNode extends AbstractDataTreeNode {

	/**
	 * Creates a new tree with the given name
	 */
	DeletedNode(String localName) {
		super(localName, NO_CHILDREN);
	}

	/**
	 * @see AbstractDataTreeNode#asBackwardDelta(DeltaDataTree, DeltaDataTree, IPath)
	 */
	AbstractDataTreeNode asBackwardDelta(DeltaDataTree myTree, DeltaDataTree parentTree, IPath key) {
		if (parentTree.includes(key))
			return parentTree.copyCompleteSubtree(key);
		return this;
	}

	/**
	 * Returns the child with the given local name
	 */
	AbstractDataTreeNode childAt(String localName) {
		/* deleted nodes do not have children */
		throw new ObjectNotFoundException(NLS.bind(Messages.dtree_missingChild, localName));
	}

	/**
	 * Returns the child with the given local name
	 */
	AbstractDataTreeNode childAtOrNull(String localName) {
		/* deleted nodes do not have children */
		return null;
	}

	AbstractDataTreeNode compareWithParent(IPath key, DeltaDataTree parent, IComparator comparator) {
		/**
		 * Just because there is a deleted node, it doesn't mean there must
		 * be a corresponding node in the parent.  Deleted nodes can live
		 * in isolation.
		 */
		if (parent.includes(key)) 
			return convertToRemovedComparisonNode(parent.copyCompleteSubtree(key), NodeComparison.K_REMOVED);
		// Node doesn't exist in either tree.  Return an empty comparison.
		// Empty comparisons are omitted from the delta.
		return new DataTreeNode(key.lastSegment(), new NodeComparison(null, null, 0, 0));
	}

	/**
	 * Creates and returns a new copy of the receiver.  Makes a deep copy of 
	 * children, but a shallow copy of name and data.
	 */
	AbstractDataTreeNode copy() {
		return new DeletedNode(name);
	}

	/**
	 * Returns true if the receiver represents a deleted node, false otherwise.
	 */
	boolean isDeleted() {
		return true;
	}

	/** 
	 * Simplifies the given node, and returns its replacement.
	 */
	AbstractDataTreeNode simplifyWithParent(IPath key, DeltaDataTree parent, IComparator comparer) {
		if (parent.includes(key))
			return this;
		return new NoDataDeltaNode(name);
	}

	/**
	 * Returns the number of children of the receiver
	 */
	int size() {
		/* deleted nodes have no children */
		return 0;
	}

	/**
	 * Return a unicode representation of the node.  This method
	 * is used for debugging purposes only (no NLS please)
	 */
	public String toString() {
		return "a DeletedNode(" + this.getName() + ")"; //$NON-NLS-1$ //$NON-NLS-2$
	}

	/**
	 * Returns a string describing the type of node.
	 */
	int type() {
		return T_DELETED_NODE;
	}

	AbstractDataTreeNode childAtIgnoreCase(String localName) {
		/* deleted nodes do not have children */
		return null;
	}
}