A Skip List in C#

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Threading;
using LSCollections;

namespace SkipListStressTest
{
	/// <summary>
	/// Form for inserting items into the dictionary.
	/// </summary>
	public class InsertForm : System.Windows.Forms.Form
	{
        private System.Windows.Forms.Label label1;
        private System.Windows.Forms.Button cancelButton;
		/// <summary>
		/// Required designer variable.
		/// </summary>
		private System.ComponentModel.Container components = null;

        // Indicates the type of insertion operation to perform.
        public enum Operation { Forward, Reverse, Random };

        // The dictionary used for insertion.
        private IDictionary dic;

        // For shuffling numbers for random insertion.
        private Shuffler shuffler = new Shuffler();

        // The type of insertion operation to perform.
        private Operation op;

        // The time the operation took place.
        private double time = 0.0;

        // Number of items to insert.
        private int numItems;

        // Cancel operation flag.
        private bool cancel = false;

        // Worker thread for performing the insertion operation.
        private Thread workerThread;

        /// <summary>
        /// Initializes an instance of the InsertForm class.
        /// </summary>
        /// <param name="dic">
        /// The dictionary to use for insertion.
        /// </param>
        /// <param name="op">
        /// The type of insertion operation to perform.
        /// </param>
        /// <param name="numItems">
        /// The number of items to insert.
        /// </param>
		public InsertForm(IDictionary dic, Operation op, int numItems)
		{
			//
			// Required for Windows Form Designer support
			//
			InitializeComponent();

            this.dic = dic;
            this.op = op;
            this.numItems = numItems;
            Load += new EventHandler(OnLoad);  
            CancelButton = cancelButton;
		}

		/// <summary>
		/// Clean up any resources being used.
		/// </summary>
		protected override void Dispose( bool disposing )
		{
			if( disposing )
			{
				if(components != null)
				{
					components.Dispose();
				}
			}
			base.Dispose( disposing );
		}

		#region Windows Form Designer generated code
		/// <summary>
		/// Required method for Designer support - do not modify
		/// the contents of this method with the code editor.
		/// </summary>
		private void InitializeComponent()
		{
            this.label1 = new System.Windows.Forms.Label();
            this.cancelButton = new System.Windows.Forms.Button();
            this.SuspendLayout();
            // 
            // label1
            // 
            this.label1.Location = new System.Drawing.Point(32, 8);
            this.label1.Name = "label1";
            this.label1.TabIndex = 0;
            this.label1.Text = "Cancel operation";
            this.label1.TextAlign = System.Drawing.ContentAlignment.MiddleCenter;
            // 
            // cancelButton
            // 
            this.cancelButton.Location = new System.Drawing.Point(40, 40);
            this.cancelButton.Name = "cancelButton";
            this.cancelButton.TabIndex = 1;
            this.cancelButton.Text = "Cancel";
            this.cancelButton.Click += new System.EventHandler(this.cancelButton_Click);
            // 
            // InsertForm
            // 
            this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
            this.ClientSize = new System.Drawing.Size(168, 86);
            this.Controls.Add(this.cancelButton);
            this.Controls.Add(this.label1);
            this.Name = "InsertForm";
            this.StartPosition = System.Windows.Forms.FormStartPosition.CenterParent;
            this.Text = "Inserting...";
            this.ResumeLayout(false);

        }
		#endregion

        /// <summary>
        /// Event handler for the Cancel button.
        /// </summary>
        private void cancelButton_Click(object sender, System.EventArgs e)
        {
            // Operation has been cancelled.
            cancel = true;
        }

        /// <summary>
        /// Form is loaded.
        /// </summary>
        private void OnLoad(object sender, EventArgs e)
        {
            // Determine which operation to perform and begin the worker
            // thread accordingly.
            switch(op)
            {
                case Operation.Forward:
                    workerThread = new Thread(new ThreadStart(InsertForward));
                    break;

                case Operation.Reverse:
                    workerThread = new Thread(new ThreadStart(InsertReverse));
                    break;

                case Operation.Random:
                    workerThread = new Thread(new ThreadStart(InsertRandom));
                    break;
            }

            // Begin thread.
            workerThread.Start();
        }

        /// <summary>
        /// Worker thread function for inserting items in forward order.
        /// </summary>
        private void InsertForward()
        {
            // Get current tick count. This will be used to determine the 
            // timing results.
            int startTick = Environment.TickCount;

            // Insert items into the dictionary.
            for(int i = 0; i < numItems && !cancel; i++)
            {
                dic.Add(i, i);
            } 

            // If the operation was not cancelled, calculate time results.
            if(!cancel)
            {            
                time = (double)(Environment.TickCount - startTick) / 1000.0;
                DialogResult = DialogResult.OK;
            }
            // Else indicate that the operation was cancelled.
            else
            {
                DialogResult = DialogResult.Cancel;
            }

            // Close form.
            Close();
        }

        /// <summary>
        /// Worker thread function for inserting items in reverse order.
        /// </summary>
        private void InsertReverse()
        {
            // Get current tick count. This will be used to determine the 
            // timing results.
            int startTick = Environment.TickCount;

            // Insert items into the dictionary.
            for(int i = numItems; i >= 0 && !cancel; i--)
            {
                dic.Add(i, i);
            } 

            // If the operation was not cancelled, calculate time results.
            if(!cancel)
            {            
                time = (double)(Environment.TickCount - startTick) / 1000.0;
                DialogResult = DialogResult.OK;
            }
            // Else indicate that the operation was cancelled.
            else
            {
                DialogResult = DialogResult.Cancel;
            }

            // Close form.
            Close();
        }

        /// <summary>
        /// Worker thread function for inserting items in random order.
        /// </summary>
        private void InsertRandom()
        {
            // Create an array to hold numbers.
            int[] array = new int[numItems];

            // Fill array with numbers.
            for(int i = 0; i < array.Length && !cancel; i++)
            {
                array[i] = i;
            }

            // If the operation has not been cancelled, shuffle the numbers.
            if(!cancel)
            {
                shuffler.Shuffle(array);
            }

            // Get current tick count. This will be used to determine the 
            // timing results.
            int startTick = Environment.TickCount;

            // Insert items into the dictionary.
            for(int i = 0; i < array.Length && !cancel; i++)
            {
                dic.Add(array[i], array[i]);
            }

            // If the operation was not cancelled, calculate time results.
            if(!cancel)
            {            
                time = (double)(Environment.TickCount - startTick) / 1000.0;
                DialogResult = DialogResult.OK;
            }
            // Else indicate that the operation was cancelled.
            else
            {
                DialogResult = DialogResult.Cancel;
            }

            // Close form.
            Close();
        }

        /// <summary>
        /// Time property - how long the operation took.
        /// </summary>
        public double Time
        {
            get
            {
                return time;
            }
        }
	}
}