//------------------------------------------------------------------------------
// <copyright file="XmlLinkedNode.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
// <owner current="true" primary="true">Microsoft</owner>
//------------------------------------------------------------------------------
 
namespace System.Xml {
 
    // Gets the node immediately preceeding or following this node.
    public abstract class XmlLinkedNode: XmlNode {
        internal XmlLinkedNode next;
 
        internal XmlLinkedNode(): base() {
            next = null;
        }
        internal XmlLinkedNode( XmlDocument doc ): base( doc ) {
            next = null;
        }
 
        // Gets the node immediately preceding this node.
        public override XmlNode PreviousSibling {
            get {
                XmlNode parent = ParentNode;
                if (parent != null) {
                    XmlNode node = parent.FirstChild;
                    while (node != null) {
                        XmlNode nextSibling = node.NextSibling; 
                        if (nextSibling == this) {
                            break;
                        }
                        node = nextSibling;
                    }
                    return node;
                }
                return null;
            }
        }
 
        // Gets the node immediately following this node.
        public override XmlNode NextSibling {
            get {
                XmlNode parent = ParentNode;
                if (parent != null) {
                    if (next != parent.FirstChild)
                        return next;
                }
                return null;
            }
        }
    }
}