query/plugins/org.eclipse.acceleo.query.ide.ui/src/org/eclipse/acceleo/query/ide/ui/viewer/NonRuleBasedDamagerRepairer.java

/*******************************************************************************
 * Copyright (c) 2017 Obeo.
 * 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:
 *     Obeo - initial API and implementation
 *******************************************************************************/
package org.eclipse.acceleo.query.ide.ui.viewer;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DocumentEvent;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.ITypedRegion;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.TextAttribute;
import org.eclipse.jface.text.TextPresentation;
import org.eclipse.jface.text.presentation.IPresentationDamager;
import org.eclipse.jface.text.presentation.IPresentationRepairer;
import org.eclipse.swt.custom.StyleRange;

/**
 * Non rule based {@link IPresentationDamager} and {@link IPresentationRepairer}.
 * 
 * @author <a href="mailto:yvan.lussaud@obeo.fr">Yvan Lussaud</a>
 */
public class NonRuleBasedDamagerRepairer implements IPresentationDamager, IPresentationRepairer {

	/**
	 * The document this object works on.
	 */
	protected IDocument document;

	/**
	 * The default text attribute if non is returned as data by the current token.
	 */
	protected TextAttribute defaultTextAttribute;

	/**
	 * Constructor.
	 * 
	 * @param defaultTextAttribute
	 *            default {@link TextAttribute}.
	 */
	public NonRuleBasedDamagerRepairer(TextAttribute defaultTextAttribute) {
		assert defaultTextAttribute != null;

		this.defaultTextAttribute = defaultTextAttribute;
	}

	public void setDocument(IDocument doc) {
		this.document = doc;
	}

	/**
	 * Returns the end offset of the line that contains the specified offset or if the offset is inside a line
	 * delimiter, the end offset of the next line.
	 *
	 * @param offset
	 *            the offset whose line end offset must be computed
	 * @return the line end offset for the given offset
	 * @exception BadLocationException
	 *                if offset is invalid in the current document
	 */
	protected int endOfLineOf(int offset) throws BadLocationException {
		int res;

		IRegion info = document.getLineInformationOfOffset(offset);
		if (offset <= info.getOffset() + info.getLength()) {
			res = info.getOffset() + info.getLength();
		} else {
			int line = document.getLineOfOffset(offset);
			try {
				info = document.getLineInformation(line + 1);
				res = info.getOffset() + info.getLength();
			} catch (BadLocationException x) {
				res = document.getLength();
			}
		}

		return res;
	}

	/**
	 * {@inheritDoc}
	 *
	 * @see org.eclipse.jface.text.presentation.IPresentationDamager#getDamageRegion(org.eclipse.jface.text.ITypedRegion,
	 *      org.eclipse.jface.text.DocumentEvent, boolean)
	 */
	public IRegion getDamageRegion(ITypedRegion partition, DocumentEvent event,
			boolean documentPartitioningChanged) {
		if (!documentPartitioningChanged) {
			try {

				final IRegion info = document.getLineInformationOfOffset(event.getOffset());
				final int start = Math.max(partition.getOffset(), info.getOffset());

				int end;
				if (event.getText() == null) {
					end = event.getOffset() + event.getLength();
				} else {
					end = event.getOffset() + event.getText().length();
				}

				if (info.getOffset() <= end && end <= info.getOffset() + info.getLength()) {
					// optimize the case of the same line
					end = info.getOffset() + info.getLength();
				} else {
					end = endOfLineOf(end);
				}
				end = Math.min(partition.getOffset() + partition.getLength(), end);
				return new Region(start, end - start);

			} catch (BadLocationException x) {
				// nothing to do here
			}
		}

		return partition;
	}

	/**
	 * {@inheritDoc}
	 *
	 * @see org.eclipse.jface.text.presentation.IPresentationRepairer#createPresentation(org.eclipse.jface.text.TextPresentation,
	 *      org.eclipse.jface.text.ITypedRegion)
	 */
	public void createPresentation(TextPresentation presentation, ITypedRegion region) {
		addRange(presentation, region.getOffset(), region.getLength(), defaultTextAttribute);
	}

	/**
	 * Adds style information to the given text presentation.
	 *
	 * @param presentation
	 *            the text presentation to be extended
	 * @param offset
	 *            the offset of the range to be styled
	 * @param length
	 *            the length of the range to be styled
	 * @param attr
	 *            the attribute describing the style of the range to be styled
	 */
	protected void addRange(TextPresentation presentation, int offset, int length, TextAttribute attr) {
		if (attr != null) {
			presentation.addStyleRange(new StyleRange(offset, length, attr.getForeground(), attr
					.getBackground(), attr.getStyle()));
		}
	}
}