C# regex - not getting outer group

Question

I am using the following Regular expression for finding the groups

string pattern = @"(?<member>(?>\w+))\((?:(?<parameter>(?:(?>[^,()""']+)|""(?>[^\\""]+|\\"")*""|@""(?>[^""]+|"""")*""|'(?:[^']|\\')*'|\((?:(?<nest>\()|(?<-nest>\))|(?>[^()]+))*(?(nest)(?!))\))+)\s*(?(?=,),\s*|(?=\))))+\)";

from the expression like

string Exp = "GetValue(GetValue(GetValue(1 + 2) * GetValue(3 * 4)) / GetValue(GetValue(5 * 6) / 7) / 8)";

I am getting the below groups :

a) GetValue(GetValue(1 + 2) * GetValue(3 * 4))

b) GetValue(GetValue(5 * 6) / 7)

I am getting all the groups but the outer group (GetValue(.... / 8)) is not getting ???

What could be the problem in the pattern ??

I tried creating a regexr, but it matches nothing at all: http://regexr.com?2voqv — Anders Marzi Tornblad, Jan 18 '12 at 14:01
Can you explain the desired result a little further? Specifically, what would you expect to be captured in each group: member, parameter, nest, -nest. — Grinn, Jan 18 '12 at 15:20

score 0 · Answer 1 · answered Jan 18 '12 at 15:05

0

My best help for you is to download and use this RegexDesigner

http://www.radsoftware.com.au/regexdesigner/

answered Jan 18 '12 at 15:05

Luis Filipe

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score 0 · Answer 2 · answered Jan 18 '12 at 15:19

0

Since it's a complicated RegEx, it would be good to have and actual example for your search string. I have found in most of these cases you'll need to have a greedy RegEx match.

For example:

Non-Greedy:
"a.+?b":

Greedy:
"a.*b":

answered Jan 18 '12 at 15:19

Orin

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score 0 · Answer 3 · edited May 23 '17 at 12:21

If you are trying to have the following matches, it is not possible with regular expressions, alone:

GetValue(GetValue(GetValue(1 + 2) * GetValue(3 * 4)) / GetValue(GetValue(5 * 6) / 7) / 8)
GetValue(GetValue(1 + 2) * GetValue(3 * 4))
GetValue(1 + 2)
GetValue(3 * 4)
GetValue(GetValue(5 * 6) / 7) / 8)
GetValue(5 * 6) / 7)

See this article for why. You could, however, use recursion to get the matches within your match, like (grossly untested pseudocode):

private List<string> getEmAll(string search)
{
    var matches = (new Regex(@"Your Expression Here")).Match(search);
    var ret = new List<string>();
    while (matches.Success)
    {
        ret.Add(matches.Value);
        ret.AddRange(getEmAll(matches.Value));
        matches = matches.NextMatch();
    }
    return ret;
}

...

getEmAll("GetValue(GetValue(GetValue(1 + 2) * GetValue(3 * 4)) / GetValue(GetValue(5 * 6) / 7) / 8)");

If you were wanting to separate out the matches further into matching groups, it would be slightly more complicated - but you get the gist.

C# regex - not getting outer group

3 Answers3