XmlLinkedNode.cs

namespace System.Xml
{
    public abstract class XmlLinkedNode : XmlNode
    {
        internal XmlLinkedNode next;

        public override XmlNode PreviousSibling
        {
            get
            {
                XmlNode parentNode = ParentNode;
                if (parentNode != null)
                {
                    XmlNode xmlNode;
                    XmlNode nextSibling;
                    for (xmlNode = parentNode.FirstChild; xmlNode != null; xmlNode = nextSibling)
                    {
                        nextSibling = xmlNode.NextSibling;
                        if (nextSibling == this)
                        {
                            break;
                        }
                    }
                    return xmlNode;
                }
                return null;
            }
        }

        public override XmlNode NextSibling
        {
            get
            {
                XmlNode parentNode = ParentNode;
                if (parentNode != null && next != parentNode.FirstChild)
                {
                    return next;
                }
                return null;
            }
        }

        internal XmlLinkedNode()
        {
            next = null;
        }

        internal XmlLinkedNode(XmlDocument doc)
            : base(doc)
        {
            next = null;
        }
    }
}