There is a well known technique within black-hat SEO called content spinning. Content spinning involves writing an article using a specific syntax which allows a text processor to generate random variations. These variations can then be used for multiple purposes without fear of being labelled as duplicate content.

I was searching for a C# algorithm which I could re-purpose into a nAnt script, but a few searches on the internet gave no results. I found a python version which seemed good enough, so I rewrote it for C#.

public static class Spinner
{
    private readonly static Random Randomizer = new Random();

    public static string Spin(string content)
    {
        const char OPEN_BRACE = '{';
        const char CLOSE_BRACE = '}';
        const char DELIMITER = '|';

        var start = content.IndexOf(OPEN_BRACE);
        var end = content.IndexOf(CLOSE_BRACE);

        if (start == -1 && end == -1 || start == -1 || end < start)
        {
            return content;
        }

        if (end == -1)
        {
            throw new ArgumentException("Unbalanced brace.");
        }

        var substring = content.Substring(start + 1, content.Length - (start + 1));
        var rest = Spin(substring);
        end = rest.IndexOf(CLOSE_BRACE);

        if (end == -1)
        {
            throw new ArgumentException("Unbalanced brace.");
        }

        var splits = rest.Substring(0, end).Split(DELIMITER);
        var item = splits[Randomizer.Next(0, splits.Length)];
        return content.Substring(0, start) + item + Spin(rest.Substring(end + 1, rest.Length - (end + 1)));
    }
}

Usage:

Spinner.Spin("{Hi|Hello|Good morning}, my name is {Matt|Bob} and I {certainly |might |should |}have {something {important|special} to {say|eat|share}|a favorite {toy|book|poem|song}}.");