CODEWITHSUNDEEP
c#regexbalancing-groups
user342552
user342552

Reputation:

Regular Expressions Balancing Group

I am trying to match balancing braces ({}) in strings. For example, I want to balance the following:

if (a == 2)
{
  doSomething();
  { 
     int x = 10;
  }
}

// this is a comment

while (a <= b){
  print(a++);
}

I came up with this regex from MSDN, but it doesn't work well. I want to extract multiple nested matching sets of {}. I am only interested in the parent match

   "[^{}]*" +
   "(" + 
   "((?'Open'{)[^{}]*)+" +
   "((?'Close-Open'})[^{}]*)+" +
   ")*" +
   "(?(Open)(?!))";

Upvotes: 1

Views: 2070

Answers (1)

mathematical.coffee
mathematical.coffee

Reputation: 56905

You're pretty close.

Adapted from the second answer on this question (I use that as my canonical "balancing xxx in C#/.NET regex engine" answer, upvote it if it helped you! It has helped me in the past):

var r = new Regex(@"
[^{}]*                  # any non brace stuff.
\{(                     # First '{' + capturing bracket
    (?:                 
    [^{}]               # Match all non-braces
    |
    (?<open> \{ )       # Match '{', and capture into 'open'
    |
    (?<-open> \} )      # Match '}', and delete the 'open' capture
    )+                  # Change to * if you want to allow {}
    (?(open)(?!))       # Fails if 'open' stack isn't empty!
)\}                     # Last '}' + close capturing bracket
"; RegexOptions.IgnoreWhitespace);

Upvotes: 6

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