PathUtil.java

package org.csstudio.sds.util;

import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.Path;

/**
 * Utility to deal with relative paths.
 * 
 * @author Kai Meyer (C1 WPS)
 * 
 */
public final class PathUtil {

	/**
	 * Path to get one folder back.
	 */
	private static IPath _folderBackPath = new Path("../");

	/**
	 * Private constructor.
	 */
	private PathUtil() {
		// nothing to do
	}

	/**
	 * Creates a new relativ {@link IPath} based on the given path, but relative
	 * to the anchorPath.
	 * 
	 * If the parameters are
	 * "C:/Program/Development/SDS/Scripts/Script.css-sdss" as path and
	 * "C:/Program/Development/SDS/Display.css-sds" as anchorPath the result
	 * will be "/Scripts/Script.css-sdss".
	 * 
	 * @param path
	 *            The path to convert
	 * @param anchorPath
	 *            The The related path
	 * @return A new {@link IPath} based on path and relative to the anchorPath
	 */
	public static IPath makePathRelativToAnchor(final IPath path,
			final IPath anchorPath) {
		IPath result = path;
		IPath referencePath = anchorPath;
		String lastSegment = referencePath.lastSegment();
		if (lastSegment.contains(".")) {
			referencePath = referencePath.removeLastSegments(1);
		}
		if (referencePath.isPrefixOf(result)) {
			result = result.setDevice(null);
			int count = referencePath.segmentCount();
			result = result.removeFirstSegments(count);
		} else {
			String device = getDevice(result);
			String anchorDevice = getDevice(referencePath);
			if ((device == null && anchorDevice == null)
					|| (device != null && device.equals(anchorDevice))) {
				if (device != null) {
					result = removeDevice(result);
					referencePath = removeDevice(referencePath);
				}
				for (int i = 0; i < referencePath.segmentCount(); i++) {
					String resultSegment = result.segment(i);
					String anchorSegment = referencePath.segment(i);
					if (resultSegment.equals(anchorSegment)) {
						result = result.removeFirstSegments(1);
					} else {
						result = _folderBackPath.append(result);
					}
				}
			}
		}
		result = result.makeRelative();
		return result;
	}

	/**
	 * Returns the device of the given path.
	 * 
	 * @param path
	 *            The {@link IPath}
	 * @return The device (ending with ':') or <code>null</code> if no device
	 *         exists
	 */
	private static String getDevice(final IPath path) {
		String string = path.toString();
		String device = null;
		if (string.charAt(1) == IPath.DEVICE_SEPARATOR) {
			device = string.substring(0, 2);
		}
		return device;
	}

	/**
	 * Removes the device of the given path.
	 * 
	 * @param path
	 *            The {@link IPath}
	 * @return The path without the device
	 */
	private static IPath removeDevice(final IPath path) {
		IPath result = path;
		String string = path.toString();
		if (string.charAt(1) == IPath.DEVICE_SEPARATOR) {
			result = new Path(string.substring(2));
		}
		return result;
	}

	/**
	 * Creates a new absolute {@link IPath} based on the relativePath and the
	 * anchorPath.
	 * 
	 * If the parameters are "/Scripts/Script.css-sdss" as path and
	 * "C:/Program/Development/SDS/Display.css-sds" as anchorPath the result
	 * will be "C:/Program/Development/SDS/Scripts/Script.css-sdss".
	 * 
	 * @param relativePath
	 *            The path to convert
	 * @param anchorPath
	 *            The The related path
	 * @return A new {@link IPath} based on path and relative to the anchorPath
	 */
	public static IPath getFullPath(final IPath relativePath,
			final IPath anchorPath) {
		IPath result = relativePath;
		if (!result.isAbsolute()) {
			if (_folderBackPath.isPrefixOf(relativePath)) {
				int segmentsToRemove = 0;
				String folderBackSegment = _folderBackPath.toString();
				String currentSegment = result.segment(0);
				while (currentSegment.equals(folderBackSegment)) {
					segmentsToRemove++;
					result = result.removeFirstSegments(1);
					currentSegment = result.segment(0);
				}
				IPath path = anchorPath.removeLastSegments(segmentsToRemove);
				result = path.append(result);
			} else {
				if (!anchorPath.isPrefixOf(result)) {
					result = anchorPath.append(result);
				}
			}
		}
		return result;
	}

}