Reputation: 188
This has gotta be something stupid, but I'm wondering if someone can help me out here. The following regex pattern match within a case class match is not working as I would expect. Can someone provide some insight? Thanks.
object Confused {
case class MyCaseClass(s: String)
val WS = """\s*""".r
def matcher(myCaseClass: MyCaseClass) = myCaseClass match {
case MyCaseClass(WS(_)) => println("Found WS")
case MyCaseClass(s) => println(s"Found >>$s<<")
}
def main(args: Array[String]): Unit = {
val ws = " "
matcher(MyCaseClass(ws))
}
}
I would expect the the first case in the pattern match to be the one that matches, but it is not.
This prints
Found >> <<
Upvotes: 3
Views: 1885
Reputation: 14227
It should be:
val WS = """(\s*)""".r
For your question, you want to match a pattern of spaces, In Scala,
A regular expression is used to determine whether a string matches a pattern and, if it does, to extract or transform the parts that match.
for extracting match parts we need to use group
to pattern a string. It means that we need to use parentheses
to around our pattern string.
Example:
val date = """(\d\d\d\d)-(\d\d)-(\d\d)""".r
"2004-01-20" match {
case date(year, month, day) => s"$year was a good year for PLs."
}
Upvotes: 10