System.Xml.XmlDocument.AddElementWithId C# (CSharp) Method

        internal void AddElementWithId(string id, XmlElement elem)
        {
            if (_htElementIdMap == null || !_htElementIdMap.Contains(id))
            {
                if (_htElementIdMap == null)
                    _htElementIdMap = new Hashtable();
                ArrayList elementList = new ArrayList();
                elementList.Add(new WeakReference(elem));
                _htElementIdMap.Add(id, elementList);
            }
            else
            {
                // there are other element(s) that has the same id
                ArrayList elementList = (ArrayList)(_htElementIdMap[id]);
                if (GetElement(elementList, elem) == null)
                    elementList.Add(new WeakReference(elem));
            }
        }

        internal void ResetParentInElementIdAttrMap(string oldVal, string newVal)
        {
            XmlElement  parent        = base.parent as XmlElement;
            XmlDocument ownerDocument = base.parent.OwnerDocument;

            ownerDocument.RemoveElementWithId(oldVal, parent);
            ownerDocument.AddElementWithId(newVal, parent);
        }