I have a source file like this:
replace 1 3 xyz
reverse 0 2
print 1 4
And I would like to assign these elements line by line using Array:
val Array(action, start, end, sub) = src.next.split(“ “)
As you can see the 4th element is optional, and I don’t know how I can manage this inconsistency. Is there any way to make the last assignment optional?
val Array(action, start, end, x @ _*) = src.next.split(" ")
This will match action, start, end to the first 3 elements, and x to a Seq[String]. You can then use x.headOption to get the 4th element as an Option.
If there are more than 4, they will all be contained in x
val line = "replace 1 3 xyz"
val Array(action, start, end, x @ _*) = line.split(" ")
// action: String = replace
// start: String = 1
// end: String = 3
// x: Seq[String] = Vector(xyz)
There are a number of different ways to approach this. Here's one that is concise but it turns everything into an Option.
val line = "reverse 0 2".split(" ")
val Seq(action, start, end, sub) = 0.to(3).map(line.lift)
//action: Option[String] = Some(reverse)
//start: Option[String] = Some(0)
//end: Option[String] = Some(2)
//sub: Option[String] = None
If you only want the 4th as an Option then you have to make it a separate assignment.
val Array(action, start, end) = line.take(3)
val sub = line.lift(3)
