How to check whether a String fully matches a Regex in Scala?
Assume I have a Regex pattern I want to match many Strings to.
val Digit = """d""".r
I just want to check whether a given String fully matches the Regex. What is a good and idiomatic way to do this in Scala?
I know that I can pattern match on Regexes, but this is syntactically not very pleasing in this case, because I have no groups to extract:
scala> "5" match { case Digit() => true case _ => false }
res4: Boolean = true
Or I could fall back to the underlying Java pattern:
scala> Digit.pattern.matcher("5").matches
res6: Boolean = true
which is not elegant, either.
Is there a better solution?
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.
I don't know Scala all that well, but it looks like you can just do:
"5".matches("d")
References
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
上一篇: 正则表达式在Java中，并忽略空白