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/****************************************************************************
* 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.docshare.cola;
import org.eclipse.ecf.core.util.Trace;
import org.eclipse.ecf.internal.docshare.Activator;
import org.eclipse.ecf.internal.docshare.DocshareDebugOptions;
public class ColaDeletion implements TransformationStrategy {
private static final long serialVersionUID = -7430435392915553959L;
private static ColaDeletion INSTANCE;
private ColaDeletion() {
// default constructor is private to enforce singleton property via
// static factory method
}
public static TransformationStrategy getInstance() {
if (INSTANCE == null) {
INSTANCE = new ColaDeletion();
}
return INSTANCE;
}
public ColaUpdateMessage getOperationalTransform(ColaUpdateMessage remoteIncomingMsg, ColaUpdateMessage localAppliedMsg, boolean localMsgHighPrio) {
Trace.entering(Activator.PLUGIN_ID, DocshareDebugOptions.METHODS_ENTERING, this.getClass(), "getOperationalTransform", new Object[] {remoteIncomingMsg, localAppliedMsg, new Boolean(localMsgHighPrio)}); //$NON-NLS-1$
ColaUpdateMessage remoteTransformedMsg = remoteIncomingMsg;
if (remoteTransformedMsg.isDeletion()) {
if (remoteTransformedMsg.getOffset() < localAppliedMsg.getOffset()) {
if ((remoteTransformedMsg.getOffset() + remoteTransformedMsg.getLengthOfReplacedText()) < localAppliedMsg.getOffset()) {
//no overlap - remote OK as is, local needs modification
localAppliedMsg.setOffset(localAppliedMsg.getOffset() - remoteTransformedMsg.getLengthOfReplacedText());
} else if ((remoteTransformedMsg.getOffset() + remoteTransformedMsg.getLengthOfReplacedText()) < (localAppliedMsg.getOffset() + localAppliedMsg.getLengthOfReplacedText())) {
//remote del at lower index reaches into locally applied del, local del reaches further out
//shorten remote del appropriately, move and shorten local del left
remoteTransformedMsg.setLengthOfReplacedText((remoteTransformedMsg.getOffset() + remoteTransformedMsg.getLengthOfReplacedText()) - localAppliedMsg.getOffset());
localAppliedMsg.setLengthOfReplacedText((remoteTransformedMsg.getOffset() + remoteTransformedMsg.getLengthOfReplacedText()) - localAppliedMsg.getOffset());
localAppliedMsg.setOffset(remoteTransformedMsg.getOffset());
}//TODO remove this comment : too tired to continue 2008-06-15 00:42h
}
}
//--------------------------
/*if (localAppliedMsg.isInsertion()) {
// something has been inserted at a lower or same index --> move
// deletion right
if (localAppliedMsg.getOffset() <= remoteTransformedMsg.getOffset()) {
remoteTransformedMsg.setOffset(remoteTransformedMsg.getOffset() + localAppliedMsg.getText().length());
}
} else if (localAppliedMsg.isDeletion()) {
if (remoteTransformedMsg.getOffset() > localAppliedMsg.getOffset()) {
// move to remote deletion to the left
// check for overlap
if (remoteTransformedMsg.getOffset() < (localAppliedMsg.getOffset() + localAppliedMsg.getLength())) {
// partial overlap on the right side of local op
if ((remoteTransformedMsg.getOffset() + remoteTransformedMsg.getLength()) > (localAppliedMsg.getOffset() + localAppliedMsg.getLength())) {
// the case that some part of the beginning of the
// incoming
// remote del lies within the already executed deletion
// and extends beyond the already applied del
// shorten the remote deletion, cut off the redundant
// part
// at the beginning of rem del
remoteTransformedMsg.setLength(remoteTransformedMsg.getLength() - ((localAppliedMsg.getOffset() + localAppliedMsg.getLength()) - remoteTransformedMsg.getOffset()));
// move shortened remote del offset to correct pos.
remoteTransformedMsg.setOffset(localAppliedMsg.getOffset());
} else { // full overlap, remote op fully contained
// within local op
// case remote deletion is fully within already applied
// deletion, i.e. don't do anything
remoteTransformedMsg.setLength(0); // TODO check
remoteTransformedMsg.setOffset(0);// TODO check -
// should resolve
// nullpointerexc
// whether this is
// enough to make
// this a no-op
}
} else { // no overlap
// deletion is fully after the already applied deletion
remoteTransformedMsg.setOffset(remoteTransformedMsg.getOffset() - localAppliedMsg.getLength());
}
// if incoming deletion is at a lower or equal index
} else if (remoteTransformedMsg.getOffset() <= localAppliedMsg.getOffset()) {
// check for overlap
if ((remoteTransformedMsg.getOffset() + remoteIncomingMsg.getLength()) > localAppliedMsg.getOffset()) {
// case remote op reaches into or even over the local op
if ((remoteTransformedMsg.getOffset() + remoteIncomingMsg.getLength()) <= (localAppliedMsg.getOffset() + localAppliedMsg.getLength())) {
// case remote op does not reach over local op, i.e.
// shorten remote op by overlap
remoteTransformedMsg.setLength(remoteTransformedMsg.getLength() - ((remoteIncomingMsg.getOffset() + remoteTransformedMsg.getLength()) - localAppliedMsg.getOffset()));// same
// as
// remoteOffset
// - localOffset
} else {
// case remote op reaches over, i.e. cut out length of
// local del-op
remoteTransformedMsg.setLength(remoteTransformedMsg.getLength() - localAppliedMsg.getLength());
}
}
// no need to do anything if there is no overlap for del-op at
// lower index vs. local del-op
}
}
remoteTransformedMsg.remoteOperationsCount += 1;
localAppliedMsg.remoteOperationsCount += 1;*/
Trace.exiting(Activator.PLUGIN_ID, DocshareDebugOptions.METHODS_EXITING, this.getClass(), "getOperationalTransform", null); //$NON-NLS-1$
return remoteTransformedMsg;
}
}
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