[Pitch] Regex-powered string processing algorithms

Evolution Pitches
11

This pitch has methods for both finding matches and checking if there is a match. However, there is a gap:

Has Match Return Match Anchoring
contains(_:) -> Bool firstMatch(of:) Unanchored
starts(with:) -> Bool prefixMatch(of:) Anchored at start ^
??? wholeMatch(of:) Anchored at start and end ^...$

Is this intentional? If not, could it be added? Maybe matchesWhole(of:)?

Related:

Should the ~= operator be for anchored or unanchored matching (ie. wholeMatch/matchesWhole or firstMatch/contains)?

The two languages I’ve used that allow using Regex in a switch have gone for different options:

case "abcde"
when /bcd/
  print "matched"
end
  • Scala does anchored matching (unless unanchored is used)
val pattern = "bcd".r

"abcde" match {
  case pattern(_*) => "Matches"
  case _ => "No match"
}

The same behaviour can be achieved whether it's anchored or not:

Anchored:

switch "abcde" {
  case /bcd/: 
     // no match
  case /.*bcd.*/:
    // matches
}

Unanchored

switch "abcde" {
  case /^bcd$/: 
     // no match
  case /bcd/:
    // matches
}

I think the unanchored option is possibly less surprising?

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