Support for special groups?

[Birgos]

Hello,

after trying this framework i missed the support for the following special group functionality:

• Balancing Group )?)
• Match suffix but exclude it (?=)
• Match prefix but exclude it (?<=)
• Match if suffix is not present (?!)
• Match if prefix is not present (?<!)
• Greedy subexpression (?>)
• Comment (?#)

Example regex expression that i wanted to rewrite:
^(?!.*[\.]{2,}.*)[a-zA-Z0-9_%\&ß'+-]+((([a-zA-Z0-9_%.\&ß'+-]))*[a-zA-Z0-9_%\&ß'+-]+)?@(?:[a-zA-Z0-9üöäÜÖÄ-]+\.)+[a-zA-Z]{2,4}$

[Timothep]

Hi Birgos, good ideas! I am not sure how to beam it into the language in an elegant manner though. I don't think adding new high-level functions like BalancingGroup() would be a good idea. What about using some kind of options like the following?

magicWand.Group(x => x, GroupOptions.ExcludePrefix);

//Snip
enum GroupOptions
{
  Balancing = 0,
  ExcludeSuffix,
  ExcludePrefix,
  MatchMissingSuffix,
  MatchMissingPrefix,
  GreedySubexpression,
  Comment
}

I'm not so up to date with those constructs, can they be combined with named groups and other "elaborated" functions just with standard groups?

[Birgos]

Hi!
I think the code would be easier to read if the groups were not encapsulated inside the standard group with GroupOptions. My thoughts would be something like:

 [Test]
 public void MagicExpression_SpecialGroups()
 {
    const string regExpression = @"^(?!.*[\.]{2,}.*)$";
    var result = magicExpression
       .StartOfLine()
       .MatchIfSuffixIsAbsent(x => x.Character().Repeat.Any()
           .CharacterIn('\\', '.') // produces multiple backslashes? should be equal to [\.]
               .Repeat.Between(2) // here we would need an overload to accept missing parameter
           .Character().Repeat.Any()
           .EndOfLine());
    Assert.That(result.Expression.ToString(), Is.EqualTo(regExpression));
  }

Sometimes I have used the following tool for deciphering. Maybe you can have a look? (http://www.ultrapico.com/expresso.htm)

Sorry, but unfortunately, I have not properly understood your last question :-(