using System;
using System.Text;
using System.Collections;
using System.Collections.Generic;
 
namespace MyOwnGeneric
{
    class OwnObject<T>
    {
        private T content;
        private OwnObject<T> next;
 
        public T Content
        {
            get { return content; }
            set { content = value; }
        }
 
        public OwnObject<T> Next
        {
            get { return next; }
            set { next = value; }
        }
 
        public override string ToString()
        {
            return content.ToString();
        }
    }
 
    class LinList<T> : IEnumerable<T>
    {
        private OwnObject<T> first;
        private OwnObject<T> last;
 
        public OwnObject<T> First
        {
            get { return first; }
            set { first = value; }
        }
 
        public OwnObject<T> Last
        {
            get { return last; }
            set { last = value; }
        }
 
        public void Add(OwnObject<T> item)
        {
            if (first == null)
            {
                first = item;
                last = item;
            }
            else
            {
                last.Next = item;
                last = item;
            }
        }
 
        //function to count items in LinList
        public int Count()
        {
            int counter = 0;
            OwnObject<T> position = first;
            while (position != null)
            {
                counter++;
                position = position.Next;
            }
            return counter;
        }
 
        //function to get the content at a fix position in LinList
        public T GetItem(int pos)
        {
            int counter = 0;
            OwnObject<T> position = first;
            //T result = null not possible because value type
            T result = default(T);
            while (position != null)
            { 
                if (counter == pos)
                {
                    result = position.Content;
                    break;
                }
                counter++;
                position = position.Next;
            }
            return result;
        }
 
        public override string ToString()
        {
            string result = "";
            OwnObject<T> position = first;
            while (position != null)
            {
                result += position.ToString();
                if (position.Next != null)
                    result += " - ";
                position = position.Next;
            }
            return result;
        }
 
        //indexer
        public T this[int index]
        {
            get
            {
                return this.GetItem(index);
            }
        }
 
        //interface IEnumerable
        public IEnumerator<T> GetEnumerator()
        {
            OwnObject<T> position = first;
            while (position != null)
            {
                yield return position.Content;
                position = position.Next;
            }
        }
 
        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }
    }
 
    class Program
    {
        static void Main(string[] args)
        {
            LinList<string> test = new LinList<string>();
            OwnObject<string> testcont = new OwnObject<string>();
            testcont.Content = "test";
            OwnObject<string> testcont2 = new OwnObject<string>();
            testcont2.Content = "test2";
            OwnObject<string> testcont3 = new OwnObject<string>();
            testcont3.Content = "test3";
 
            test.Add(testcont);
            test.Add(testcont2);
            test.Add(testcont3);
 
            //using the interface of IEnumerable
            foreach (string item in test)
            {
                Console.WriteLine(item);
            }
 
            //using the indexer and the item counter
            for (int i = 0; i < test.Count(); i++)
            {
                Console.WriteLine(test[i]);
            }
        }
    }
}