/*******************************************************************************
 * 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
 *******************************************************************************/
module org.eclipse.core.internal.databinding.observable.tree.TreePath;

import java.lang.all;

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 this(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 is 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 is 0) {
            return null;
        }
        return segments[segments.length - 1];
    }

    /*
     * (non-Javadoc)
     * 
     * @see java.lang.Object#equals(java.lang.Object)
     */
    public override equals_t opEquals(Object other) {
        if (!( null !is cast(TreePath)other )) {
            return false;
        }
        TreePath otherPath = cast(TreePath) other;
        if (segments.length !is 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 override hash_t toHash() {
        if (hash is 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 bool startsWith(TreePath treePath) {
        int thisSegmentCount = getSegmentCount();
        int otherSegmentCount = treePath.getSegmentCount();
        if (otherSegmentCount is 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);
    }
}