Silverlight Auto Complete Treeview

using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Collections.Generic;
using System.Linq;




namespace AutoCompleteTextBox
{
    public class HierarchicalCity : INotifyPropertyChanged
    {
        #region Constructors
        public HierarchicalCity(string city)
        {
            CityName = city;
            SubClass = new ObservableCollection<HierarchicalCity>();
        }
        public HierarchicalCity(string City, ObservableCollection<HierarchicalCity> sub)
        {
            CityName = City;
            SubClass = sub;
        }
        #endregion

        #region Data Properties
        private string _CityName = "";
        public string CityName
        {
            get { return _CityName; }
            set { _CityName = value; OnPropertyChanged("CityName"); }
        }

        private bool isExpanded;
        public bool IsExpanded
        {
            get { return isExpanded; }
            set
            {
                isExpanded = value;
                OnPropertyChanged("IsExpanded");
            }
        }


        private bool isSelected;
        public bool IsSelected
        {
            get { return isSelected; }
            set
            {
                isSelected = value;
                OnPropertyChanged("IsSelected");
            }
        }

        private ObservableCollection<HierarchicalCity> _SubClass = new ObservableCollection<HierarchicalCity>();
        public ObservableCollection<HierarchicalCity> SubClass
        {
            get { return _SubClass; }
            set { _SubClass = value; OnPropertyChanged("SubClass"); }
        }
        #endregion

        #region INotify Implementation
        public event PropertyChangedEventHandler PropertyChanged;


        protected virtual void OnPropertyChanged(string propertyName)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(propertyName));
            }
        }
        #endregion

        #region Expansion / Collapse Function
        public bool ExpandSuperclasses(HierarchicalCity itemToLookFor)
        {
            return ApplyActionToSuperclasses(itemToLookFor, superclass => superclass.IsExpanded = true);
        }

        public void CollapseAll()
        {
            ApplyActionToAllItems();//item => item.IsExpanded = false);
            //ApplyActionToAllItems(item => item.IsSelected = false);
        }

        void ActionCollapse(HierarchicalCity item)
        {
            item.IsExpanded = false;
            item.IsSelected = false;
        }

        private void ApplyActionToAllItems()//Action<HierarchicalCity> itemAction)
        {
            Stack<HierarchicalCity> dataItemStack = new Stack<HierarchicalCity>();
            dataItemStack.Push(this);

            while (dataItemStack.Count != 0)
            {
                HierarchicalCity currentItem = dataItemStack.Pop();
                ActionCollapse(currentItem);//itemAction(currentItem);
                foreach (HierarchicalCity childItem in currentItem.SubClass)
                {
                    dataItemStack.Push(childItem);
                }
            }
        }

        private bool ApplyActionToSuperclasses(HierarchicalCity itemToLookFor, Action<HierarchicalCity> itemAction)
        {
            if (itemToLookFor == this)
            {
                return true;
            }
            else
            {
                foreach (HierarchicalCity subclass in this.SubClass)
                {
                    bool foundItem = subclass.ApplyActionToSuperclasses(itemToLookFor, itemAction);
                    if (foundItem)
                    {
                        itemAction(this);
                        return true;
                    }
                }
                return false;
            }
        }

        #endregion



    }

}