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/*******************************************************************************
* Copyright (c) 2005, 2006 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
*******************************************************************************/
package org.eclipse.jface.viewers;
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);
for (int i = 0; i < segments.length; i++) {
Assert.isNotNull(segments[i]);
}
this.segments = segments;
}
/**
* 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, or <code>null</code> if this
* path has no segments.
*
* @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, or <code>null</code> if this
* path has no segments.
*
* @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;
}
return equals((TreePath) other, null);
}
/**
* (non-Javadoc)
*
* @see java.lang.Object#hashCode()
*/
public int hashCode() {
if (hash == 0) {
hash = hashCode(null);
}
return hash;
}
/**
* Returns a hash code computed from the hash codes of the segments, using
* the given comparer to compute the hash codes of the segments.
*
* @param comparer
* comparer to use or <code>null</code> if the segments' hash
* codes should be computed by calling their hashCode() methods.
* @return the computed hash code
*/
public int hashCode(IElementComparer comparer) {
int result = 0;
for (int i = 0; i < segments.length; i++) {
if (comparer == null) {
result += segments[i].hashCode();
} else {
result += comparer.hashCode(segments[i]);
}
}
return result;
}
/**
* Returns whether this path is equivalent to the given path using the
* specified comparer to compare individual elements.
*
* @param otherPath
* tree path to compare to
* @param comparer
* comparator to use or <code>null</code> if segments should be
* compared using equals()
* @return whether the paths are equal
*/
public boolean equals(TreePath otherPath, IElementComparer comparer) {
if (otherPath == null) {
return false;
}
if (segments.length != otherPath.segments.length) {
return false;
}
for (int i = 0; i < segments.length; i++) {
if (comparer == null) {
if (!segments[i].equals(otherPath.segments[i])) {
return false;
}
} else {
if (!comparer.equals(segments[i], otherPath.segments[i])) {
return false;
}
}
}
return true;
}
/**
* 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
* @param comparer
* the comparer to use, or <code>null</code> if equals() should
* be used to compare segments
* @return whether the given path is a prefix of this path, or the same as
* this path
*/
public boolean startsWith(TreePath treePath, IElementComparer comparer) {
int thisSegmentCount = getSegmentCount();
int otherSegmentCount = treePath.getSegmentCount();
if (otherSegmentCount == thisSegmentCount) {
return equals(treePath, comparer);
}
if (otherSegmentCount > thisSegmentCount) {
return false;
}
for (int i = 0; i < otherSegmentCount; i++) {
Object otherSegment = treePath.getSegment(i);
if (comparer == null) {
if (!otherSegment.equals(segments[i])) {
return false;
}
} else {
if (!comparer.equals(otherSegment, 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;
} else if (segmentCount == 1) {
return EMPTY;
}
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);
}
}
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