VB.Net Matching and replacing the contents of multiple overlapping sets of brackets in a string

I am using vb.net to parse my own basic scripting language, sample below. I am a bit stuck trying to deal with the 2 separate types of nested brackets.

Assuming name = Sam
Assuming timeFormat = hh:mm:ss
Assuming time(开发者_StackOverflow中文版) is a function that takes a format string but  
         has a default value and returns a string.


Hello [[name]], the time is [[time(hh:mm:ss)]].
Result: Hello Sam, the time is 19:54:32.

The full time is [[time()]].
Result: The full time is 05/06/2011 19:54:32.

The time in the format of your choice is [[time([[timeFormat]])]].
Result: The time in the format of your choice is 19:54:32.

I could in theory change the syntax of the script completely but I would rather not. It is designed like this to enable strings without quotes because it will be included in an XML file and quotes in that context were getting messy and very prone to errors and readability issues. If this fails I could redesign using something other than quotes to mark out strings but I would rather use this method.

Preferably, unless there is some other way I am not aware of, I would like to do this using regex. I am aware that the standard regex is not really capable of this but I believe this is possible using MatchEvaluators in vb.net and some form of recursion based replacing. However I have not been able to get my head around it for the last day or so, possibly because it is hugely difficult, possibly because I am ill, or possibly because I am plain thick.

I do have the following regex for parts of it.

Detecting the parentheses: (\w*?)\((.*?)\)(?=[^\(+\)]*(\(|$))
Detecting the square brackets: \[\[(.*?)\]\](?=[^\[+\]]*(\[\[|$))

I would really appreciate some help with this as it is holding the rest of my project back at the moment. And sorry if I have babbled on too much or not put enough detail, this is my first question on here.

Here's a little sample which might help you iterate through several matches/groups/captures. I realize that I am posting C# code, but it would be easy for you to convert that into VB.Net

//these two may be passed in as parameters:
string tosearch;//the string you are searching through
string regex;//your pattern to match
//...
Match m;
CaptureCollection cc;
GroupCollection gc;

Regex r = new Regex(regex, RegexOptions.IgnoreCase);
m = r.Match(tosearch);
gc = m.Groups;
Debug.WriteLine("Number of groups found = " + gc.Count.ToString());

// Loop through each group.
for (int i = 0; i < gc.Count; i++)
{
  cc = gc[i].Captures;
  counter = cc.Count;
  int grpnum = i + 1;
  Debug.WriteLine("Scanning group: " + grpnum.ToString() );

  // Print number of captures in this group.
  Debug.WriteLine("  Captures count = " + counter.ToString());

  if (cc.Count >= 1)
  {
    foreach (Capture cap in cc)
    {
      Debug.WriteLine(string.format("  Capture found: {0}", cap.ToString()));
    }
  }
}

Here is a slightly simplified version of the code I wrote for this. Thanks for the help everyone and sorry I forgot to post this before. If you have any questions or anything feel free to ask.

Function processString(ByVal scriptString As String)
    ' Functions
    Dim pattern As String = "\[\[((\w+?)\((.*?)\))(?=[^\(+\)]*(\(|$))\]\]"
    scriptString = Regex.Replace(scriptString, pattern, New MatchEvaluator(Function(match) processFunction(match)))

    ' Variables
    pattern = "\[\[([A-Za-z0-9+_]+)\]\]"
    scriptString = Regex.Replace(scriptString, pattern, New MatchEvaluator(Function(match) processVariable(match)))
    Return scriptString
End Function

Function processFunction(ByVal match As Match)
    Dim nameString As String = match.Groups(2).Value
    Dim paramString As String = match.Groups(3).Value
    paramString = processString(paramString)
    Select Case nameString
        Case "time"
            Return getLocalValueTime(paramString)
        Case "math"
            Return getLocalValueMath(paramString)
    End Select
    Return ""
End Function

Function processVariable(ByVal match As Match)
    Try
        Return moduleDictionary("properties")("vars")(match.Groups(1).Value)
    Catch ex As Exception
    End Try
End Function