How to check whether a String fully matches a Regex in Scala?

Solution 1:

Answering my own question I'll use the "pimp my library pattern"

object RegexUtils {
  implicit class RichRegex(val underlying: Regex) extends AnyVal {
    def matches(s: String) = underlying.pattern.matcher(s).matches
  }
}

and use it like this

import RegexUtils._
val Digit = """\d""".r
if (Digit matches "5") println("match")
else println("no match")

unless someone comes up with a better (standard) solution.

Notes

I didn't pimp String to limit the scope of potential side effects.
unapplySeq does not read very well in that context.

Solution 2:

I don't know Scala all that well, but it looks like you can just do:

"5".matches("\\d")

References

http://langref.org/scala/pattern-matching/matching

Solution 3:

For the full match you may use unapplySeq. This method tries to match target (whole match) and returns the matches.

scala> val Digit = """\d""".r
Digit: scala.util.matching.Regex = \d

scala> Digit unapplySeq "1"
res9: Option[List[String]] = Some(List())

scala> Digit unapplySeq "123"
res10: Option[List[String]] = None

scala> Digit unapplySeq "string"
res11: Option[List[String]] = None

Solution 4:

  """\d""".r.unapplySeq("5").isDefined            //> res1: Boolean = true
  """\d""".r.unapplySeq("a").isDefined            //> res2: Boolean = false