Generic

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

namespace Generics_CSharp
{
//Type parameter T in angle brackets.
public class MyList : IEnumerable
{
protected Node head;
protected Node current = null;

// Nested type is also generic on T
protected class Node
{
public Node next;
//T as private member datatype.
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; }
}
}

public MyList()
{
head = null;
}

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

// Implement GetEnumerator to return IEnumerator to enable
// foreach iteration of our list. Note that in C# 2.0
// you are not required to implement Current and MoveNext.
// The compiler will create a class that implements IEnumerator.
public IEnumerator GetEnumerator()
{
Node current = head;

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

// We must implement this method because
// IEnumerable inherits IEnumerable
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
}


public class SortedList : MyList where T : IComparable
{
// A simple, unoptimized sort algorithm that
// orders list elements from lowest to highest:
public void BubbleSort()
{
if (null == head || null == head.Next)
return;

bool swapped;
do
{
Node previous = null;
Node current = head;
swapped = false;

while (current.next != null)
{
// Because we need to call this method, the SortedList
// class is constrained on IEnumerable
if (current.Data.CompareTo(current.next.Data) > 0)
{
Node tmp = current.next;
current.next = current.next.next;
tmp.next = current;

if (previous == null)
{
head = tmp;
}
else
{
previous.next = tmp;
}
previous = tmp;
swapped = true;
}

else
{
previous = current;
current = current.next;
}

}// end while
} while (swapped);
}
}

// A simple class that implements IComparable
// using itself as the type argument. This is a
// common design pattern in objects that are
// stored in generic lists.
public class Person : IComparable
{
string name;
int age;

public Person(string s, int i)
{
name = s;
age = i;
}

// This will cause list elements
// to be sorted on age values.
public int CompareTo(Person p)
{
return age - p.age;
}

public override string ToString()
{
return name + ":" + age;
}

// Must implement Equals.
public bool Equals(Person p)
{
return (this.age == p.age);
}
}

class Generics
{
static void Main(string[] args)
{
//Declare and instantiate a new generic SortedList class.
//Person is the type argument.
SortedList list = new SortedList();

//Create name and age values to initialize Person objects.
string[] names = new string[] { "Franscoise", "Bill", "Li", "Sandra", "Gunnar", "Alok", "Hiroyuki", "Maria", "Alessandro", "Raul" };
int[] ages = new int[] { 45, 19, 28, 23, 18, 9, 108, 72, 30, 35 };

//Populate the list.
for (int x = 0; x < names.Length; x++)
{
list.AddHead(new Person(names[x], ages[x]));
}

Console.WriteLine("Unsorted List:");
//Print out unsorted list.
foreach (Person p in list)
{
Console.WriteLine(p.ToString());
}

//Sort the list.
list.BubbleSort();

Console.WriteLine(String.Format("{0}Sorted List:", Environment.NewLine));
//Print out sorted list.
foreach (Person p in list)
{
Console.WriteLine(p.ToString());
}

Console.WriteLine("Done");
}
}

}