Patterns in SOME –Iterator

Code in C#:   namespace Iterator_DesignPattern {      using System;      using System.Collections;        class Node      {          private string name;          public string Name          {               get               {                    return name;                }          }          public Node(string s)          {               name = s;          }      }           class NodeCollection      {          private ArrayList list = new ArrayList();          private int nodeMax = 0;                   // left as a student exercise - implement collection          // functions to remove and edit entries also          public void AddNode(Node n)          {               list.Add(n);               nodeMax++;                      }                 public Node GetNode(int i)          {               return ((Node) list[i]);          }            public int NodeMax          {                           get               {                    return nodeMax;               }          }      }        /*       * The iterator needs to understand how to traverse the collection       * It can do that as way it pleases - forward, reverse, depth-first,       */      abstract class Iterator      {          abstract public Node Next();              }        class ReverseIterator : Iterator      {          private NodeCollection nodeCollection;          private int currentIndex;            public ReverseIterator (NodeCollection c)          {               nodeCollection = c;                            currentIndex = c.NodeMax -1; // array index starts at 0!          }            // note: as the code stands, if the collection changes,          // the iterator needs to be restarted          override public Node Next()          {               if (currentIndex == -1)                    return null;               else                    return(nodeCollection.GetNode(currentIndex--));          }      }           ///<summary>      ///    Summary description for Client.      ///</summary>      public class Client      {          public static int Main(string[] args)          {                 NodeCollection c = new NodeCollection();               c.AddNode(new Node("first"));               c.AddNode(new Node("second"));               c.AddNode(new Node("third"));                 // now use iterator to traverse this               ReverseIterator i = new ReverseIterator(c);                 // the code below will work with any iterator type               Node n;               do               {                    n = i.Next();                    if (n != null)                        Console.WriteLine("{0}", n.Name);               } while (n != null);                                  return 0;          }      } }   Code in SOME:    CNode        (string r_Name)                   //constructor and a read-only property   CNodeCollection ->CNode[][_list]            //collection referrence define        int r_NodeMax        AddNode(CNode)        GetNode(int)   AIterator        CNode a_Next()        CReverseIterator : AIterator ->CNodeCollection[_nodeCollection]        int _currentIndex        (CNodeCollection)        CNode o_Next()   CClient        main     CClient.main {        CNodeCollection c.();        CNode node1.("first");               c.AddNode(node[node1])        {               <%               _list.Add(node);                nodeMax++;               %>        };               CNode node2.("second");        c.AddNode(node2);                            //need not re-define               CNode node3.("third"); //need not re-define        c.AddNode(node3);          // now use iterator to traverse this        CReverseIterator i.(_nodeCollection = c)        {               <% _currentIndex = c.NodeMax -1; /*array index starts at 0!*/ %>        };          // the code below will work with any iterator type        CNode n;        <%        do        {        %>               n = i.Next<CReverseIterator>()               {                      <%                   if (_currentIndex == -1)                   {                                    return null;                             }                             else                             {                                    return(_nodeCollection.GetNode(i[_currentIndex--]))                                    {                                           return ((CNode) list[i]);                                    };                             }                      %>               };        <%               if (n != null)               {                      Console.WriteLine("{0}", n.Name);               }        } while (n != null);                              return 0;  %> }