Scala regexps: how to return matches as array or list

Question

Is there a simple way to return regex matches as an array?
Here is how I am trying in 2.7.7:

val s = \"\"\"6 1 2\"\"\"
val re = \"\"\"(\\d+)         


        

Answer 1

There is a difference between how unapplySeq interprets mulitple groups and how findAllIn does. findAllIn scans your pattern over the string and returns each string that matches (advancing by the match if it succeeds, or one character if it fails).

So, for example:

scala> val s = "gecko 6 1 2 3 4 5"
scala> re.findAllIn(s).toList
res3: List[String] = List(6 1 2, 3 4 5)

On the other hand, unapplySeq assumes a perfect match to the sequence.

scala> re.unapplySeq(s)
res4: Option[List[String]] = None

So, if you want to parse apart groups that you have specified in an exact regex string, use unapplySeq. If you want to find those subsets of the string that look like your regex pattern, use findAllIn. If you want to do both, chain them yourself:

scala> re.findAllIn(s).flatMap(text => re.unapplySeq(text).elements )
res5: List[List[String]] = List(List(6, 1, 2), List(3, 4, 5))