Translate Regex.IsMatch on SQLite

[scomert]

implements #18845

[dnfadmin]

All CLA requirements met.

[smitpatel]

Base branch change to main. Please rebase on latest main.

[roji]

One thing to be careful is the finer details of regex behavior. For example, in PostgreSQL the default is to have single-line behavior (where . doesn't match \n), while the .NET default behavior isn't. It may be OK to translate the default overload of IsMatch (the one without RegexOptions) to whatever the default behavior is on Sqlite, but it would mean a subtle behavior mismatch.

[roji]

For comparison, here's the regex SQL generation in EFCore.PG (and here's the translation). In PG regex is a 1st-class operator instead of a function.

[bricelam]

@roji The beauty here is that SQLite doesn't provide an implementation. (Well, outside of an optional extension that the user would need to compile themselves.) The idea being that you just re-use your platform's regex so the app and the database have the same semantics.

[roji]

Ah, I see - so this would end up calling back into .NET Regex.IsMatch then? Or some native implementation?

Just asking the question around behavioral discrepancy between Regex.IsMatch and what actually gets executed..

[bricelam]

Yes, the database would call back into Regex.IsMatch

[bricelam]

Looks like we need to override the test in Cosmos too

[bricelam]

(Rebased, squashed, and cleaned it up a bit)