C# Regex Atomic Opening and Closing Brackets

Question

I have the following which is a placeholder, I'm trying to use Atomic groups to catch double opening and closing brackets in pairs:

{{(?>{{(?)|}}(<-DEPTH>)|[^{}])*}}(?(DEPTH)(?!))

I am {{name}} and I have {{scales}: red {{metallic_scales}: shiny and glistering}} scales}}

Safe to say, I'm not really having much success.

So I'd want something like:

1. {{name}}
2. {{scales}: red {{metallic_scales}: shiny and glistering}} scales}}
3. {{metallic_scales}: shiny and glistering}}

Answer 1

You may use

(?=                    # Start of a positive lookahead to enable overlapping matches
  (?<results>          # The group storing the results
    {{                 # {{ (left-hand delimiter)
      (?>              # Start of an atomic group
        (?!{{|}}).|    # Any char not starting {{ or }} char sequence, or
        {{(?<DEPTH>)|  # {{ and a value pushed on to DEPTH group stack, or
        }}(?<-DEPTH>)  # }} and a value popped from the DEPTH group stack
      )*               # Zero or more repetitions of the atomic group patterns
    }}                 # }} substring
    (?(DEPTH)(?!))     # Conditional construct failing the match if DEPTH stack is not empty
  )                    # End of the results group
)                      # End of the lookahead

See the regex demo.

C# declaration:

Regex reg = new Regex(@"
    (?=                  # Start of a positive lookahead to enable overlapping matches
      (?<results>          # The group storing the results
        {{                 # {{ (left-hand delimiter)
          (?>              # Start of an atomic group
            (?!{{|}}).|    # Any char not starting {{ or }} char sequence, or
            {{(?<DEPTH>)|  # {{ and a value pushed on to DEPTH group stack, or
            }}(?<-DEPTH>)  # }} and a value popped from the DEPTH group stack
          )*               # Zero or more repetitions of the atomic group patterns
        }}                 # }} substring
        (?(DEPTH)(?!))     # Conditional construct failing the match if DEPTH stack is not empty
      )                    # End of the results group
    )                      # End of the lookahead", 
    RegexOptions.IgnorePatternWhitespace | RegexOptions.Singleline);
var results = reg.Matches(text).Cast<Match>().Select(x => x.Groups["results"].Value);