Scala equivalent for 'matches' regex method? - regex

Question

Struggling with my first (ever) Scala regex here. I need to see if a given String matches the regex: "animal<[a-zA-Z0-9]+,[a-zA-Z0-9]+>".
So, some examples:
animal<0,sega> => valid
animal<fizz,buzz> => valid
animAl<fizz,buzz> => illegal; animAl contains upper-case (and this is case-sensitive)
animal<fizz,3d> => valid
animal<,3d> => illegal; there needs to be something [a-zA-Z0-9]+ between '<' and ','
animal<fizz,> => illegal; there needs to be something [a-zA-Z0-9]+ between ',' and '>'
animal<fizz,%> => illegal; '%' doesn't match [a-zA-Z0-9]+
etc.
My best attempt so far:
val animalRegex = "animal<[a-zA-Z0-9]+,[a-zA-Z0-9]+>".r
animalRegex.findFirstIn("animal<fizz,buzz")
Unfortunately that's where I'm hitting a brick wall. findFirstIn and all the other obvious methods available of animalRegex all return Option[String] types. I was hoping to find something that returns a boolean, so something like:
val animalRegex = "animal<[a-zA-Z0-9]+,[a-zA-Z0-9]+>".r
if(animalRegex.matches("animal<fizz,buzz>")) {
val leftOperand : String = getLeftOperandSomehow(...)
val rightOperand : String = getRightOperandSomehow(...)
}
So I need the equivalent of Java's matches method, and then need a way to access the "left operand" (that is, the value of the first [a-zA-Z0-9]+ group, which in the current case is "fizz"), and then ditto for the right/second operand ("buzz"). Any ideas where I'm going awry?

Answer 1

To be able to extract the matched parts from your string, you'll need to add capture groups to your regex expression, like so (note the parentheses):
val animalRegex = "animal<([a-zA-Z0-9]+),([a-zA-Z0-9]+)>".r
Then, you can use Scala's pattern matching to check for a match and extract the operands from the string:
val str = "animal<fizz,3d>"
val result = str match {
case animalRegex(op1,op2) => s"$op1, $op2"
case _ => "Did not match"
}
In this example, result will contain "fizz, 3d"