Copyright (c) 2000, 2007 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2007 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.text.projection;


import org.eclipse.core.runtime.Assert;

import org.eclipse.jface.text.BadPositionCategoryException;
import org.eclipse.jface.text.DefaultPositionUpdater;
import org.eclipse.jface.text.DocumentEvent;
import org.eclipse.jface.text.Position;


The position updater used to adapt the segments of a projection document to
changes of the master document. Depending on the flags set on a segment, a
segment is either extended to shifted if an insertion happens at a segment's
offset. The last segment is extended if an insert operation happens at the
end of the segment.
Since:
3.0/**
 * The position updater used to adapt the segments of a projection document to
 * changes of the master document. Depending on the flags set on a segment, a
 * segment is either extended to shifted if an insertion happens at a segment's
 * offset. The last segment is extended if an insert operation happens at the
 * end of the segment.
 *
 * @since 3.0
 */
class SegmentUpdater extends DefaultPositionUpdater {

	private Segment fNextSegment= null;
	private boolean fIsProjectionChange= false;

	
Creates the segment updater for the given category.
Params:
segmentCategory – the position category used for managing the segments of a projection document/**
	 * Creates the segment updater for the given category.
	 *
	 * @param segmentCategory the position category used for managing the segments of a projection document
	 */
	protected SegmentUpdater(String segmentCategory) {
		super(segmentCategory);
	}

	@Override
	public void update(DocumentEvent event) {

		Assert.isTrue(event instanceof ProjectionDocumentEvent);
		fIsProjectionChange= ((ProjectionDocumentEvent) event).getChangeType() == ProjectionDocumentEvent.PROJECTION_CHANGE;

		try {

			Position[] category= event.getDocument().getPositions(getCategory());

			fOffset= event.getOffset();
			fLength= event.getLength();
			fReplaceLength= (event.getText() == null ? 0 : event.getText().length());
			fDocument= event.getDocument();

			for (int i= 0; i < category.length; i++) {

				fPosition= category[i];
				Assert.isTrue(fPosition instanceof Segment);

				if (i < category.length - 1)
					fNextSegment= (Segment) category[i + 1];
				else
					fNextSegment= null;

				fOriginalPosition.offset= fPosition.offset;
				fOriginalPosition.length= fPosition.length;

				if (notDeleted())
					adaptToReplace();

			}

		} catch (BadPositionCategoryException x) {
			// do nothing
		}
	}

	@Override
	protected void adaptToInsert() {

		Segment segment= (Segment) fPosition;
		int myStart= segment.offset;
		int myEnd= segment.offset + segment.length - (segment.isMarkedForStretch || fNextSegment == null || isAffectingReplace() ? 0 : 1);
		myEnd= Math.max(myStart, myEnd);
		int yoursStart= fOffset;

		try {

			if (myEnd < yoursStart)
				return;

			if (segment.isMarkedForStretch) {
				Assert.isTrue(fIsProjectionChange);
				segment.isMarkedForShift= false;
				if (fNextSegment != null) {
					fNextSegment.isMarkedForShift= true;
					fNextSegment.isMarkedForStretch= false;
				}
			}

			if (fLength <= 0) {

				if (myStart < (yoursStart + (segment.isMarkedForShift ? 0 : 1)))
					fPosition.length += fReplaceLength;
				else
					fPosition.offset += fReplaceLength;

			} else {

				if (myStart <= yoursStart && fOriginalPosition.offset <= yoursStart)
					fPosition.length += fReplaceLength;
				else
					fPosition.offset += fReplaceLength;
			}

		} finally {
			segment.clearMark();
		}
	}
}