SE-0357: Regex String Processing Algorithms

[Michael_Ilseman]

@Paul_Cantrell

The correct spelling would be /(?m).*foo.*/ (I think? Although the syntax proposal does not mention . matching newlines in multiline mode as it does in other languages…).

That would be the semantic definition of the any character class, which would probably be formalized as part of [Pitch] Unicode for String Processing.

@Paul_Cantrell

Conversely, if Swift cases match partial strings by default, the naive solution of /^fo+$/ to match "fooooo" but exclude "foobar" is in fact correct , because in the proposed syntax, ^ and $ match beginning / end of string, not beginning / end of line, when not in multiline mode. (This is a notable departure from other languages, which would require /\Afo+\Z/ in order to exclude "foobar" .)

Minor process note, we should probably treat the definitions in the syntax description as temporary and update them after the Unicode pitch happens. I do think it's clearer to have them there, but they're not normative.

That being said, could we discuss departure from other languages more? Perl, Python, ICU/NSRegularExpression, Rust, Javascript, C#, ... all have the behavior of being beginning/end of input unless multi-line is specified. I couldn't quickly figure out Ruby, but that might be the language that diverges from the pack here.

It might end up being the case that we argue for multi-line as the default.