/*******************************************************************************
* Copyright (c) 2000, 2009 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.events;
import org.eclipse.core.internal.resources.ICoreConstants;
import org.eclipse.core.internal.resources.ResourceInfo;
import org.eclipse.core.internal.watson.IElementComparator;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IResourceDelta;
/**
* Compares two Resources and returns flags describing how
* they have changed, for use in computing deltas.
* Implementation note: rather than defining a partial order
* as specified by IComparator, the compare operation returns
* a set of flags instead. The delta computation only cares
* whether the comparison is zero (equal) or non-zero (not equal).
*/
public class ResourceComparator implements IElementComparator, ICoreConstants {
/* Singleton instances */
protected static final ResourceComparator notificationSingleton = new ResourceComparator(true, false);
protected static final ResourceComparator buildSingleton = new ResourceComparator(false, false);
/**
* Boolean indicating whether or not this comparator is to be used for
* a notification. (as opposed to a build) Notifications include extra information
* like marker and sync info changes.
*/
private boolean notification;
/**
* Boolean indicating whether or not this comparator is to be used for
* snapshot. Snapshots care about extra information such as the used bit.
*/
private boolean save;
/**
* Returns a comparator which compares resource infos, suitable for computing
* save and snapshot deltas.
*/
public static ResourceComparator getSaveComparator() {
return new ResourceComparator(false, true);
}
/**
* Returns a comparator which compares resource infos, suitable for computing
* build deltas.
*/
public static ResourceComparator getBuildComparator() {
return buildSingleton;
}
/**
* Returns a comparator which compares resource infos, suitable for computing
* build deltas.
*/
public static ResourceComparator getNotificationComparator() {
return notificationSingleton;
}
/**
* Create a comparator which compares resource infos.
* @param notification if true, check for marker deltas.
* @param save if true, check for all resource changes that snapshot needs
*/
private ResourceComparator(boolean notification, boolean save) {
this.notification = notification;
this.save = save;
}
/**
* Compare the ElementInfos for two resources.
*/
public int compare(Object o1, Object o2) {
// == handles null, null.
if (o1 == o2)
return IResourceDelta.NO_CHANGE;
int result = 0;
if (o1 == null)
return ((ResourceInfo) o2).isSet(M_PHANTOM) ? IResourceDelta.ADDED_PHANTOM : IResourceDelta.ADDED;
if (o2 == null)
return ((ResourceInfo) o1).isSet(M_PHANTOM) ? IResourceDelta.REMOVED_PHANTOM : IResourceDelta.REMOVED;
if (!(o1 instanceof ResourceInfo && o2 instanceof ResourceInfo))
return IResourceDelta.NO_CHANGE;
ResourceInfo oldElement = (ResourceInfo) o1;
ResourceInfo newElement = (ResourceInfo) o2;
if (!oldElement.isSet(M_PHANTOM) && newElement.isSet(M_PHANTOM))
return IResourceDelta.REMOVED;
if (oldElement.isSet(M_PHANTOM) && !newElement.isSet(M_PHANTOM))
return IResourceDelta.ADDED;
if (!compareOpen(oldElement, newElement))
result |= IResourceDelta.OPEN;
if (!compareContents(oldElement, newElement)) {
if (oldElement.getType() == IResource.PROJECT)
result |= IResourceDelta.DESCRIPTION;
else if (newElement.getType() == IResource.FILE || oldElement.getType() == IResource.FILE)
result |= IResourceDelta.CONTENT;
}
if (!compareType(oldElement, newElement))
result |= IResourceDelta.TYPE;
if (!compareNodeIDs(oldElement, newElement)) {
result |= IResourceDelta.REPLACED;
// if the node was replaced and the old and new were files, this is also a content change.
if (oldElement.getType() == IResource.FILE && newElement.getType() == IResource.FILE)
result |= IResourceDelta.CONTENT;
}
if (compareLocal(oldElement, newElement))
result |= IResourceDelta.LOCAL_CHANGED;
if (!compareCharsets(oldElement, newElement))
result |= IResourceDelta.ENCODING;
if (!compareDerived(oldElement, newElement))
result |= IResourceDelta.DERIVED_CHANGED;
if (notification && !compareSync(oldElement, newElement))
result |= IResourceDelta.SYNC;
if (notification && !compareMarkers(oldElement, newElement))
result |= IResourceDelta.MARKERS;
if (save && !compareUsed(oldElement, newElement))
result |= IResourceDelta.CHANGED;
return result == 0 ? 0 : result | IResourceDelta.CHANGED;
}
private boolean compareDerived(ResourceInfo oldElement, ResourceInfo newElement) {
return oldElement.isSet(ICoreConstants.M_DERIVED) == newElement.isSet(ICoreConstants.M_DERIVED);
}
private boolean compareCharsets(ResourceInfo oldElement, ResourceInfo newElement) {
return oldElement.getCharsetGenerationCount() == newElement.getCharsetGenerationCount();
}
/**
* Compares the contents of the ResourceInfo.
*/
private boolean compareContents(ResourceInfo oldElement, ResourceInfo newElement) {
return oldElement.getContentId() == newElement.getContentId();
}
/**
* Compares the existence of local files/folders for two linked resources.
*/
private boolean compareLocal(ResourceInfo oldElement, ResourceInfo newElement) {
//only applicable for linked resources
if (!oldElement.isSet(ICoreConstants.M_LINK) || !newElement.isSet(ICoreConstants.M_LINK))
return false;
long oldStamp = oldElement.getModificationStamp();
long newStamp = newElement.getModificationStamp();
return (oldStamp == -1 || newStamp == -1) && (oldStamp != newStamp);
}
private boolean compareMarkers(ResourceInfo oldElement, ResourceInfo newElement) {
// If both sets of markers are null then perhaps we added some markers
// but then deleted them right away before notification. In that case
// don't signify a marker change in the delta.
boolean bothNull = oldElement.getMarkers(false) == null && newElement.getMarkers(false) == null;
return bothNull || oldElement.getMarkerGenerationCount() == newElement.getMarkerGenerationCount();
}
/**
* Compares the node IDs of the ElementInfos for two resources.
*/
private boolean compareNodeIDs(ResourceInfo oldElement, ResourceInfo newElement) {
return oldElement.getNodeId() == newElement.getNodeId();
}
/**
* Compares the open state of the ElementInfos for two resources.
*/
private boolean compareOpen(ResourceInfo oldElement, ResourceInfo newElement) {
return oldElement.isSet(M_OPEN) == newElement.isSet(M_OPEN);
}
/**
* Compares the sync state for two resources.
*/
private boolean compareSync(ResourceInfo oldElement, ResourceInfo newElement) {
return oldElement.getSyncInfoGenerationCount() == newElement.getSyncInfoGenerationCount();
}
/**
* Compares the type of the ResourceInfo.
*/
private boolean compareType(ResourceInfo oldElement, ResourceInfo newElement) {
return oldElement.getType() == newElement.getType();
}
/**
* Compares the used state of the ElementInfos for two resources.
*/
private boolean compareUsed(ResourceInfo oldElement, ResourceInfo newElement) {
return oldElement.isSet(M_USED) == newElement.isSet(M_USED);
}
}