My regular expression savvy is not up-to-snuff and I'm having trouble getting an expression exactly correct. Any help is greatly appreciated.

I need an expression that will match strings that contain exactly 1 set of outer-most curly braces. Whatever happens between those braces is legit, including nested braces. So, for example:

{test} OK
this is a {test} string OK
{this} is a {test} FAIL
{this {is} a test} OK
this { is {{{ a t}est OK

I hope that's clear. Thanks!

using System;
using System.Text.RegularExpressions;
namespace myapp
{
    class Class1
    {
        static void Main(string[] args)
        {
            String sourcestring = "this { is {{{ a t}est";
            Regex re = new Regex(@"\{(?>[^{}]+|\{(?<DEPTH>)|\}(?<-DEPTH>))*(?(DEPTH)(?!))\}");
            MatchCollection mc = re.Matches(sourcestring);
            if (mc.Count != 1)
            {
                Console.WriteLine("Fail!");
            }
            else
            {
                Console.WriteLine("Pass!");
            }
        }
    }
}

Wow, thanks. I guess it wasn't trivial.... Now I need to look up all those patterns being used and figure out what they mean!

Thanks!

I would recommend Mastering Regular Expressions by Friedl, that's where I first saw that pattern.