regex for nested parentheses

Question

Brief

I have the following text:

[atdSd[asdasd<4REGEH22>asdosy] ***oopprefs[ew<16REGEH30>rdtr]pppp555b

My matches should be as follows:

1. [asdasd<4REGEH22>asdosy]
2. [ew<16REGEH30>rdtr]

My attempts

I have tried to make it on my own but the result was:

1. [atdSd[asdasd<4REGEH22>asdosy]
2. [ew<16REGEH30>rdtr]

I am using the following expression:

\[\S+<(\d+)REGEH(\d+)>\S+\]

Specifics

The conditions are:

• You must have no whitespaces inside the match.
• Inside the match you must have [(ASCII Symbols)<(Some digits)REGEH(Some digits)>(ASCII Symbols)]
• If you have nested brackets you need to match the inner most. [asdSd[asdasd<4REGEH23>asdUsd] should match [asdasd<4REGEH23>asdUsd]

An example that should yield no matches

[atdSd[<4REGEH22>asdosy] ***oopprefs[ew<16REGEH>rdtr]pppp555b

Question

How can I match the inner parentheses?

Answer 1

  var st = "[atdSd[asdasd<4REGEH22>asdosy] ***oopprefs[ew<16REGEH30>rdtr]pppp555b";

        List<string> result = new List<string>
                            (Regex.Matches(st, @"\[[^[]+REGEH.*?\]")
                            .Cast<Match>()
                            .Select(x => x.Value)
                            .ToList());

        // [asdasd<4REGEH22>asdosy] [ew<16REGEH30>rdtr]

Answer 2

How about this?

\[[^\s\[]+<(\d+)REGEH(\d+)>[[^\s\[]+\]

Basically replaced the \S with [^\s\[], ie a negated char class matching for not whitepsace chars and, crucially - for not [.

http://regexr.com/3glld