// CSortedSet.cs.
// http://svc.luckstar.com.tw/CodeHelper/cs/KeyWord/SortedSet.txt
// CodeHelper for SortedSet.

// 2017-03-19, honda@luckstar.com.tw, Create Based on CollectionSample.sln.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
// add
using System.Collections;
using System.IO;


namespace ConsoleBase
{
    public class CSortedSet
    {
        public void Run()
        {
            try
            {
                // Get a list of the files to use for the sorted set.
                //IEnumerable<string> files1 = Directory.EnumerateFiles(@"\\archives\2007\media",
                //    "*", SearchOption.AllDirectories);

                IEnumerable<string> files1 = Directory.EnumerateFiles(@"c:\temp",
                    "*", SearchOption.AllDirectories);

                // Create a sorted set using the ByFileExtension comparer.
                SortedSet<string> mediaFiles1 =
                    new SortedSet<string>(new ByFileExtension());

                // Note that there is a SortedSet constructor that takes an IEnumerable,
                // but to remove the path information they must be added individually.
                foreach (string f in files1)
                {
                    mediaFiles1.Add(f.Substring(f.LastIndexOf(@"\") + 1));
                }

                // Remove elements that have non-media extensions.
                // See the 'isDoc' method.
                Console.WriteLine("Remove docs from the set...");
                Console.WriteLine("\tCount before: {0}", mediaFiles1.Count.ToString());
                mediaFiles1.RemoveWhere(isDoc);
                Console.WriteLine("\tCount after: {0}", mediaFiles1.Count.ToString());


                Console.WriteLine();

                // List all the avi files.
                SortedSet<string> aviFiles = mediaFiles1.GetViewBetween("avi", "avj");

                Console.WriteLine("AVI files:");
                foreach (string avi in aviFiles)
                {
                    Console.WriteLine("\t{0}", avi);
                }

                Console.WriteLine();

                // Create another sorted set.
                //IEnumerable<string> files2 =
                //    Directory.EnumerateFiles(@"\\archives\2008\media",
                //        "*", SearchOption.AllDirectories);
                IEnumerable<string> files2 =
                    Directory.EnumerateFiles(@"c:\temp",
                        "*", SearchOption.AllDirectories);

                SortedSet<string> mediaFiles2 = new SortedSet<string>(new ByFileExtension());

                foreach (string f in files2)
                {
                    mediaFiles2.Add(f.Substring(f.LastIndexOf(@"\") + 1));
                }

                // Remove elements in mediaFiles1 that are also in mediaFiles2.
                Console.WriteLine("Remove duplicates (of mediaFiles2) from the set...");
                Console.WriteLine("\tCount before: {0}", mediaFiles1.Count.ToString());
                mediaFiles1.ExceptWith(mediaFiles2);
                Console.WriteLine("\tCount after: {0}", mediaFiles1.Count.ToString());

                Console.WriteLine();

                Console.WriteLine("List of mediaFiles1:");
                foreach (string f in mediaFiles1)
                {
                    Console.WriteLine("\t{0}", f);
                }

                // Create a set of the sets.
                IEqualityComparer<SortedSet<string>> comparer =
                    SortedSet<string>.CreateSetComparer();

                HashSet<SortedSet<string>> allMedia =
                    new HashSet<SortedSet<string>>(comparer);
                allMedia.Add(mediaFiles1);
                allMedia.Add(mediaFiles2);
            }
            catch (IOException ioEx)
            {
                Console.WriteLine(ioEx.Message);
            }

            catch (UnauthorizedAccessException AuthEx)
            {
                Console.WriteLine(AuthEx.Message);

            }

        }
        // Defines a predicate delegate to use
        // for the SortedSet.RemoveWhere method.
        private bool isDoc(string s)
        {
            if (s.ToLower().EndsWith(".txt") ||
                s.ToLower().EndsWith(".doc") ||
                s.ToLower().EndsWith(".xls") ||
                s.ToLower().EndsWith(".xlsx") ||
                s.ToLower().EndsWith(".pdf") ||
                s.ToLower().EndsWith(".doc") ||
                s.ToLower().EndsWith(".docx"))
            {
                return true;
            }
            else
            {
                return false;
            }
        }

    }
    // Defines a comparer to create a sorted set
    // that is sorted by the file extensions.
    public class ByFileExtension : IComparer<string>
    {
        string xExt, yExt;

        CaseInsensitiveComparer caseiComp = new CaseInsensitiveComparer();

        public int Compare(string x, string y)
        {
            // Parse the extension from the file name. 
            xExt = x.Substring(x.LastIndexOf(".") + 1);
            yExt = y.Substring(y.LastIndexOf(".") + 1);

            // Compare the file extensions. 
            int vExt = caseiComp.Compare(xExt, yExt);
            if (vExt != 0)
            {
                return vExt;
            }
            else
            {
                // The extension is the same, 
                // so compare the filenames. 
                return caseiComp.Compare(x, y);
            }
        }
    }


}

result:
Remove docs from the set...
	Count before: 12
	Count after: 10

AVI files:

Remove duplicates (of mediaFiles2) from the set...
	Count before: 10
	Count after: 0

List of mediaFiles1: