C# Stream Array Merge Extension Method

If the need to sort a collection larger than the amount of RAM available arises, merge sort algorithms are a good solution. The following extension method is a merge algorithm implementation that combines two or more sorted Streams using Read and Output functions passed as parameters.

public static class StreamArrayExtension
{
    public static void Merge<T>(this Stream[] Streams,
        Func<Stream, T> ReadItem, Action<T> OutputItem)
        where T : IComparable<T>
    {
        T[] buffer = new T[Streams.Length];

        for (int x = 0; x < Streams.Length; x++)
            buffer[x] = ReadItem(Streams[x]);

        int end = Streams.Length - 1;

        bool[] completed = new bool[Streams.Length];

        int completedCount = 0;

        while (completedCount < Streams.Length)
            for (int x = 0; x < Streams.Length; x++)
                if (completed[x])
                    continue;
                else
                    for (int y = 0; y < Streams.Length; y++)
                        if (x == y && x != end)
                            continue;
                        else if (!completed[y] &&
                            buffer[x].CompareTo(buffer[y]) == 1)
                            break;
                        else if (y == end)
                        {
                            OutputItem(buffer[x]);

                            if (Streams[x].Position != Streams[x].Length)
                                buffer[x] = ReadItem(Streams[x]);
                            else
                            {
                                completed[x] = true;

                                completedCount++;
                            }
                        }
    }
}

It can be used as follows:

Stream[] sortedStreams = new Stream[]
{
    new MemoryStream(new byte[] { 1, 2, 3 }),
    new MemoryStream(new byte[] { 0, 4 }),
    new MemoryStream(new byte[] { 1, 5 }),
};

sortedStreams.Merge(x => x.ReadByte(), x => Console.WriteLine(x));

Console.ReadKey();

With the resulting output:

0
1
1
2
3
4
5