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/*******************************************************************************
 * Copyright (c) 2005, 2015 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Lars Vogel  - Bug 430873
 *******************************************************************************/
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.
 * 

* Clients may instantiate this class. Not intended to be subclassed. *

* * @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 (Object segment : segments) { Assert.isNotNull(segment); } 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 null 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 null 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]; } @Override public boolean equals(Object other) { if (!(other instanceof TreePath)) { return false; } return equals((TreePath) other, null); } @Override 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 null 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 (Object segment : segments) { if (comparer == null) { result += segment.hashCode(); } else { result += comparer.hashCode(segment); } } 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 null 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 null 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 null 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 the segment to be added * @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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