core/plugins/org.eclipse.dltk.ui/src/org/eclipse/dltk/ui/text/PartitionDoubleClickSelector.java

/*******************************************************************************
 * Copyright (c) 2008, 2017 IBM Corporation and others.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 * 
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.dltk.ui.text;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DefaultTextDoubleClickStrategy;
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.TextUtilities;

/**
 * Double click strategy that selects the partition if double click occurs at
 * the partition boundaries.
 *
 * @since 3.0
 */
public class PartitionDoubleClickSelector extends
		DefaultTextDoubleClickStrategy {

	private String fPartitioning;

	int fLeftBorder;
	int fRightBorder;
	int fHitDelta;

	/**
	 * Creates a new partition double click selector for the given document
	 * partitioning.
	 *
	 * @param partitioning
	 *            the document partitioning
	 * @param leftBorder
	 *            number of characters to ignore from the left border of the
	 *            partition
	 * @param rightBorder
	 *            number of characters to ignore from the right border of the
	 *            partition
	 */
	public PartitionDoubleClickSelector(String partitioning, int leftBorder,
			int rightBorder) {
		this(partitioning, leftBorder, rightBorder, 1);
	}

	/**
	 * Creates a new partition double click selector for the given document
	 * partitioning.
	 *
	 * @param partitioning
	 *            the document partitioning
	 * @param leftBorder
	 *            number of characters to ignore from the left border of the
	 *            partition
	 * @param rightBorder
	 *            number of characters to ignore from the right border of the
	 *            partition
	 * @param hitDeltaOffset
	 *            character offset delta relative to partition borders used to
	 *            define the trigger character
	 * @since 3.0
	 */
	public PartitionDoubleClickSelector(String partitioning, int leftBorder,
			int rightBorder, int hitDeltaOffset) {
		fPartitioning = partitioning;
		fLeftBorder = leftBorder;
		fRightBorder = rightBorder;
		fHitDelta = hitDeltaOffset;
	}

	/*
	 * @see DefaultTextDoubleClickStrategy#findExtendedDoubleClickSelection()
	 *
	 * @since Eclipse 3.5
	 */
	@Override
	protected IRegion findExtendedDoubleClickSelection(IDocument document,
			int offset) {
		IRegion match = super
				.findExtendedDoubleClickSelection(document, offset);
		if (match != null)
			return match;

		try {
			ITypedRegion region = TextUtilities.getPartition(document,
					fPartitioning, offset, true);
			if (offset == region.getOffset() + fHitDelta
					|| offset == region.getOffset() + region.getLength()
							- fHitDelta) {
				if (fLeftBorder == 0 && fRightBorder == 0)
					return region;
				if (fRightBorder == -1) {
					String delimiter = document.getLineDelimiter(document
							.getLineOfOffset(region.getOffset()
									+ region.getLength() - 1));
					if (delimiter == null)
						fRightBorder = 0;
					else
						fRightBorder = delimiter.length();
				}
				return new Region(region.getOffset() + fLeftBorder,
						region.getLength() - fLeftBorder - fRightBorder);
			}
		} catch (BadLocationException e) {
			return null;
		}
		return null;
	}
}