using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
		var text = "{token1:param1}stuff{token2}more stuff{token3:param3}";
		var pattern = @"\{(?<key>[^:}]*)(?::(?<value>[^}]*))?}";
		var matches = Regex.Matches(text, pattern);
        foreach (Match m in matches)
        {
        	Console.WriteLine(m.Value);
        	Console.WriteLine(m.Groups["key"].Value);
        	Console.WriteLine(m.Groups["value"].Value);
        }
	}
	
}