| /******************************************************************************* |
| * Copyright (c) 2005, 2008 IBM Corporation 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: |
| * IBM Corporation - initial API and implementation |
| * Matthew Hall - bug 118516 |
| *******************************************************************************/ |
| package org.eclipse.core.internal.databinding.observable.tree; |
| |
| import org.eclipse.core.runtime.Assert; |
| |
| /** |
| * A tree path denotes a model element in a tree viewer. Tree path objects have |
| * value semantics. A model element is represented by a path of elements in the |
| * tree from the root element to the leaf element. |
| * <p> |
| * Clients may instantiate this class. Not intended to be subclassed. |
| * </p> |
| * |
| * @since 3.2 |
| */ |
| public final class TreePath { |
| |
| /** |
| * Constant for representing an empty tree path. |
| */ |
| public static final TreePath EMPTY = new TreePath(new Object[0]); |
| |
| private Object[] segments; |
| |
| private int hash; |
| |
| /** |
| * Constructs a path identifying a leaf node in a tree. |
| * |
| * @param segments |
| * path of elements to a leaf node in a tree, starting with the |
| * root element |
| */ |
| public TreePath(Object[] segments) { |
| Assert.isNotNull(segments, "Segments array cannot be null"); //$NON-NLS-1$ |
| this.segments = new Object[segments.length]; |
| for (int i = 0; i < segments.length; i++) { |
| Assert.isNotNull(segments[i], "Segments array cannot contain null"); //$NON-NLS-1$ |
| this.segments[i] = segments[i]; |
| } |
| } |
| |
| /** |
| * Returns the element at the specified index in this path. |
| * |
| * @param index |
| * index of element to return |
| * @return element at the specified index |
| */ |
| public Object getSegment(int index) { |
| return segments[index]; |
| } |
| |
| /** |
| * Returns the number of elements in this path. |
| * |
| * @return the number of elements in this path |
| */ |
| public int getSegmentCount() { |
| return segments.length; |
| } |
| |
| /** |
| * Returns the first element in this path. |
| * |
| * @return the first element in this path |
| */ |
| public Object getFirstSegment() { |
| if (segments.length == 0) { |
| return null; |
| } |
| return segments[0]; |
| } |
| |
| /** |
| * Returns the last element in this path. |
| * |
| * @return the last element in this path |
| */ |
| public Object getLastSegment() { |
| if (segments.length == 0) { |
| return null; |
| } |
| return segments[segments.length - 1]; |
| } |
| |
| /* |
| * (non-Javadoc) |
| * |
| * @see java.lang.Object#equals(java.lang.Object) |
| */ |
| public boolean equals(Object other) { |
| if (!(other instanceof TreePath)) { |
| return false; |
| } |
| TreePath otherPath = (TreePath) other; |
| if (segments.length != otherPath.segments.length) { |
| return false; |
| } |
| for (int i = 0; i < segments.length; i++) { |
| if (!segments[i].equals(otherPath.segments[i])) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| public int hashCode() { |
| if (hash == 0) { |
| for (int i = 0; i < segments.length; i++) { |
| hash += segments[i].hashCode(); |
| } |
| } |
| return hash; |
| } |
| |
| /** |
| * Returns whether this path starts with the same segments as the given |
| * path, using the given comparer to compare segments. |
| * |
| * @param treePath |
| * path to compare to |
| * @return whether the given path is a prefix of this path, or the same as |
| * this path |
| */ |
| public boolean startsWith(TreePath treePath) { |
| int thisSegmentCount = getSegmentCount(); |
| int otherSegmentCount = treePath.getSegmentCount(); |
| if (otherSegmentCount == thisSegmentCount) { |
| return equals(treePath); |
| } |
| if (otherSegmentCount > thisSegmentCount) { |
| return false; |
| } |
| for (int i = 0; i < otherSegmentCount; i++) { |
| Object otherSegment = treePath.getSegment(i); |
| if (!otherSegment.equals(segments[i])) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| /** |
| * Returns a copy of this tree path with one segment removed from the end, |
| * or <code>null</code> if this tree path has no segments. |
| * @return a tree path |
| */ |
| public TreePath getParentPath() { |
| int segmentCount = getSegmentCount(); |
| if (segmentCount <= 1) { |
| return null; |
| } |
| Object[] parentSegments = new Object[segmentCount - 1]; |
| System.arraycopy(segments, 0, parentSegments, 0, segmentCount - 1); |
| return new TreePath(parentSegments); |
| } |
| |
| /** |
| * Returns a copy of this tree path with the given segment added at the end. |
| * @param newSegment |
| * @return a tree path |
| */ |
| public TreePath createChildPath(Object newSegment) { |
| int segmentCount = getSegmentCount(); |
| Object[] childSegments = new Object[segmentCount + 1]; |
| if(segmentCount>0) { |
| System.arraycopy(segments, 0, childSegments, 0, segmentCount); |
| } |
| childSegments[segmentCount] = newSegment; |
| return new TreePath(childSegments); |
| } |
| } |