/****************************************************************************
* Copyright (c) 2008 Mustafa K. Isik 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:
* Mustafa K. Isik - initial API and implementation
*****************************************************************************/
package org.eclipse.ecf.internal.sync.doc.cola;
import org.eclipse.ecf.core.util.Trace;
import org.eclipse.ecf.internal.sync.Activator;
import org.eclipse.ecf.internal.sync.SyncDebugOptions;
import org.eclipse.ecf.sync.doc.DocumentChangeMessage;
public class ColaInsertionTransformationStategy implements ColaTransformationStrategy {
private static final long serialVersionUID = 5192625383622519749L;
private static ColaInsertionTransformationStategy INSTANCE;
private ColaInsertionTransformationStategy() {
// default constructor is private to enforce singleton property via
// static factory method
}
public static ColaTransformationStrategy getInstance() {
if (INSTANCE == null) {
INSTANCE = new ColaInsertionTransformationStategy();
}
return INSTANCE;
}
/**
* Resolves two conflicting <code>ColaDocumentChangeMessage</code>s by applying an appropriate operational transform.
*
* If necessary, modifies <code>localAppliedMsg</code> as well to reflect knowledge of <code>remoteIncomingMsg</code>
* in case more conflicting/further diverging remote messages arrive.
*
* @param remoteIncomingMsg message originating from remote site, generated on same document state as <code>localAppliedMsg</code>
* @param localAppliedMsg message already applied to local document, generation state corresponds to that of <code>remoteIncomingMsg</code>
* @param localMsgHighPrio determines insertion preference for same offsets, if true localAppliedMsg comes first
* @return operational transform of remote message, not conflicting with applied local message
*/
public ColaDocumentChangeMessage getOperationalTransform(ColaDocumentChangeMessage remoteIncomingMsg, ColaDocumentChangeMessage localAppliedMsg, boolean localMsgHighPrio) {
Trace.entering(Activator.PLUGIN_ID, SyncDebugOptions.METHODS_ENTERING, this.getClass(), "getOperationalTransform", new Object[] {remoteIncomingMsg, localAppliedMsg, new Boolean(localMsgHighPrio)}); //$NON-NLS-1$
final ColaDocumentChangeMessage remoteTransformedMsg = remoteIncomingMsg;
if (localAppliedMsg.isInsertion()) {
if (remoteTransformedMsg.getOffset() < localAppliedMsg.getOffset()) {
//coopt(remote(low),local(high)) --> (remote(low),local(low + high))
localAppliedMsg.setOffset(localAppliedMsg.getOffset() + remoteTransformedMsg.getOffset());
} else if (remoteTransformedMsg.getOffset() == localAppliedMsg.getOffset()) {
//coopt(remote(same),local(same))
if (localMsgHighPrio) {
//at owner --> (remote(high),local(same))
remoteTransformedMsg.setOffset(remoteTransformedMsg.getOffset() + localAppliedMsg.getText().length());
} else {
//at participant --> (remote(same),local(high))
localAppliedMsg.setOffset(localAppliedMsg.getOffset() + remoteTransformedMsg.getText().length());
}
} else if (remoteTransformedMsg.getOffset() > localAppliedMsg.getOffset()) {
//coopt(remote(high),local(low)) --> (remote(low + high),local(low))
remoteTransformedMsg.setOffset(remoteTransformedMsg.getOffset() + localAppliedMsg.getText().length());
}
} else if (localAppliedMsg.isDeletion()) {
if (remoteTransformedMsg.getOffset() <= localAppliedMsg.getOffset()) {
localAppliedMsg.setOffset(localAppliedMsg.getOffset() + remoteTransformedMsg.getLengthOfInsertedText());
} else if (remoteTransformedMsg.getOffset() > localAppliedMsg.getOffset()) {
if (remoteTransformedMsg.getOffset() > (localAppliedMsg.getOffset() + localAppliedMsg.getLengthOfReplacedText())) {
remoteTransformedMsg.setOffset(remoteTransformedMsg.getOffset() - localAppliedMsg.getLengthOfReplacedText());
} else if (remoteTransformedMsg.getOffset() <= (localAppliedMsg.getOffset() + localAppliedMsg.getLengthOfReplacedText())) {
//TODO test this ^#$%^#$ case
final DocumentChangeMessage deletionFirstMessage = new DocumentChangeMessage(localAppliedMsg.getOffset(), remoteTransformedMsg.getOffset() - localAppliedMsg.getOffset(), localAppliedMsg.getText());
final ColaDocumentChangeMessage deletionFirstPart = new ColaDocumentChangeMessage(deletionFirstMessage, localAppliedMsg.getLocalOperationsCount(), localAppliedMsg.getRemoteOperationsCount());
localAppliedMsg.addToSplitUpRepresentation(deletionFirstPart);
final DocumentChangeMessage deletionSecondMessage = new DocumentChangeMessage(localAppliedMsg.getOffset() + remoteTransformedMsg.getLengthOfInsertedText(), localAppliedMsg.getLengthOfReplacedText() - deletionFirstPart.getLengthOfReplacedText(), localAppliedMsg.getText());
final ColaDocumentChangeMessage deletionSecondPart = new ColaDocumentChangeMessage(deletionSecondMessage, localAppliedMsg.getLocalOperationsCount(), localAppliedMsg.getRemoteOperationsCount());
localAppliedMsg.addToSplitUpRepresentation(deletionSecondPart);
localAppliedMsg.setSplitUp(true);
remoteTransformedMsg.setOffset(localAppliedMsg.getOffset());
}
}
}
Trace.exiting(Activator.PLUGIN_ID, SyncDebugOptions.METHODS_EXITING, this.getClass(), "getOperationalTransform", remoteTransformedMsg); //$NON-NLS-1$
return remoteTransformedMsg;
}
}