Reuse of iteration algorithms

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


namespace AlgorithmReuse
{
	public struct DisplayItem
	{
		public string Info;
		public string Message;
	}

	public class ProcessorBase
	{
		/// <summary>
		/// Messages from processors to show on UI.
		/// </summary>
		protected List<DisplayItem> m_DisplayItems = new List<DisplayItem>();

		/// <summary>
		/// Gets the messages to show on UI.
		/// </summary>
		public virtual List<DisplayItem> DisplayItems
		{
			get { return m_DisplayItems; }
		}
	}



	/// <summary>
	/// Processor to display all directories and all files.
	/// </summary>
	public class DisplayAllProcessor : ProcessorBase
	{
		#region Delegate properties

		public Iterators.DirectoryInfoHandler DisplayDirInfo
		{
			get { return MyDisplayDirInfo; }
		}

		public Iterators.FileInfoHandler DisplayFileInfo
		{
			get { return MyDisplayFileInfo; }
		}

		#endregion Delegate properties



		#region Functions returned by delegate properties

		private void MyDisplayDirInfo(DirectoryInfo Info)
		{
			DisplayItem di;
			di.Info = "Dir";
			di.Message = Info.FullName;
			m_DisplayItems.Add(di);
		}

		private void MyDisplayFileInfo(FileInfo Info)
		{
			DisplayItem di;
			di.Info = "File";
			di.Message = Info.FullName;
			m_DisplayItems.Add(di);
		}

		#endregion Functions returned by delegate properties
	}



	/// <summary>
	/// Processor to find an average and maximum file sizes in a collection.
	/// </summary>
	public class FindAvgAndMaxProcessor : ProcessorBase
	{
		private long m_MaxFileSize = 0;
		private FileInfo m_MaxFileInfo = null;
		private long m_TotalFileSizes = 0;
		private long m_TotalFiles = 0;


		public override List<DisplayItem> DisplayItems
		{
			get
			{
				m_DisplayItems.Clear();

				DisplayItem diAvg;
				diAvg.Info = "Avg file size";
				long lAverage = m_TotalFiles == 0 ? 0 : m_TotalFileSizes / m_TotalFiles;
				diAvg.Message = string.Format("{0} bytes", lAverage.ToString());
				DisplayItem diMax;
				diMax.Info = "Max file size";
				string strFileName = m_MaxFileInfo == null ? "None" : m_MaxFileInfo.FullName;
				diMax.Message = string.Format("File name: {0}, size: {1} bytes", strFileName, m_MaxFileSize);

				m_DisplayItems.Add(diAvg);
				m_DisplayItems.Add(diMax);

				return base.DisplayItems;
			}
		}

		protected virtual void ClearStats()
		{
			m_MaxFileSize = 0;
			m_MaxFileInfo = null;
			m_TotalFileSizes = 0;
			m_TotalFiles = 0;
		}


		#region Delegate properties

		public Iterators.FileInfoHandler CountFileSizes
		{
			get { return MyCountFileSizes; }
		}

		#endregion Delegate properties



		#region Functions returned by delegate properties

		protected virtual void MyCountFileSizes(FileInfo Info)
		{
			// Keep track of the biggest file.
			if (Info.Length > m_MaxFileSize)
			{
				m_MaxFileSize = Info.Length;
				m_MaxFileInfo = Info;
			}

			// Keep track of file count and the sum of all file sizes.
			++m_TotalFiles;
			m_TotalFileSizes += Info.Length;
		}

		#endregion Functions returned by delegate properties
	}



	public class FindAvgAndMaxByExtProcessor : FindAvgAndMaxProcessor
	{
		private string m_Extension;

		public FindAvgAndMaxByExtProcessor(string Extension)
		{
			m_Extension = Extension;
		}

		public string Extension
		{
			get { return m_Extension; }
			set
			{
				m_Extension = value;
				ClearStats();
			}
		}


		#region Functions returned by delegate properties

		protected override void MyCountFileSizes(FileInfo Info)
		{
			if (0 == string.Compare(Info.Extension, m_Extension, StringComparison.CurrentCultureIgnoreCase))
			{
				base.MyCountFileSizes(Info);
			}
		}

		#endregion Functions returned by delegate properties
	}
}