//This example is based on http://msdn2.microsoft.com/en-us/library/0x6a29h6(VS.80).aspx

using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;

namespace Generic1
{
    class Program
    {
        static void Main(string[] args)
        {
            // int is the type argument
            GenericList<int> list = new GenericList<int>();

            for (int x = 0; x < 10; x++)
            {
                list.AddHead(x);
            }

            foreach (int i in list)
            {
                System.Console.Write(i + " ");
            }
            System.Console.WriteLine("\nDone\n");

            // string is the type argument
            GenericList<string> slist = new GenericList<string>();

            for (int x = 0; x < 10; x++)
            {
                slist.AddHead(x.ToString());
            }

            foreach (string str in slist)
            {
                System.Console.Write(str + " ");
            }
            System.Console.WriteLine("\nDone");
        }
    }

    // type parameter T in angle brackets
    public class GenericList<T> : IEnumerable<T>
    {
        // The nested class is also generic on T since it uses T
        private class Node
        {
            private Node next;
            // T as private member data type
            private T data;

            // T used in non-generic constructor
            public Node(T t)
            {
                next = null;
                data = t;
            }

            public Node Next
            {
                get { return next; }
                set { next = value; }
            }

            // T as return type of property
            public T Data
            {
                get { return data; }
                set { data = value; }
            }
        }

        private Node _head;

        // constructor
        public GenericList()
        {
            _head = null;
        }

        // T as method parameter type:
        public void AddHead(T t)
        {
            Node n = new Node(t);
            n.Next = _head;
            _head = n;
        }

        //This is needed if supporting IEnumerable<T> since it derives from IEnumerable.
        //It doesn't get called by the foreach loops.

        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }

        public IEnumerator<T> GetEnumerator()  //Use IEnumerator<T> if supporting IEnumerable<T>
        {
            Node current = _head;

            while (current != null)
            {
                yield return current.Data;
                current = current.Next;
            }
        }
    }


}