I am writing a web based app at the moment and I am wanting to maintain a history of the persons movements around the site to enable some business logic for handling back button clicks.

I wanted to use a Stack but I did not want to let it get too out of control in memory if people take weird navigation choices around the site. So I wanted a stack that would push on the top but have a maximum limit so that when the maximum was reached the oldest items on the stack just fell out the bottom.

So I wrote the MaxStack. Hope you like it. It uses a generic linked list to implement the stack like interface.

Note its also serializable as I am storing it in session.
(Sorry about the indenting wordpress has mashed it)

MaxStack
[csharp]
using System;
using System.Collections.Generic;

namespace MyArchitecture
{
///

/// Generic stack implementation with a maximum limit
/// When something is pushed on the last item is removed from the list
///

[Serializable]
public class MaxStack
{
#region Fields

private int _limit;
private LinkedList _list;

#endregion

#region Constructors

public MaxStack(int maxSize)
{
_limit = maxSize;
_list = new LinkedList();

}

#endregion

#region Public Stack Implementation

public void Push(T value)
{
if (_list.Count == _limit)
{
_list.RemoveLast();
}
_list.AddFirst(value);
}

public T Pop()
{
if (_list.Count > 0)
{
T value = _list.First.Value;
_list.RemoveFirst();
return value;
}
else
{
throw new InvalidOperationException(“The Stack is empty”);
}

}

public T Peek()
{
if (_list.Count > 0)
{
T value = _list.First.Value;
return value;
}
else
{
throw new InvalidOperationException(“The Stack is empty”);
}

}

public void Clear()
{
_list.Clear();

}

public int Count
{
get { return _list.Count; }
}

///

/// Checks if the top object on the stack matches the value passed in
///

/// ///
public bool IsTop(T value)
{
bool result = false;
if (this.Count > 0)
{
result = Peek().Equals(value);
}
return result;
}

public bool Contains(T value)
{
bool result = false;
if (this.Count > 0)
{
result = _list.Contains(value);
}
return result;
}

public IEnumerator GetEnumerator()
{
return _list.GetEnumerator();
}

#endregion

}
}
[/csharp]