Scala string pattern matching by multiple possible groups

Question

Given an input Map[String,String] such as

val in = Map("name1"                -> "description1",
             "name2.name22"         -> "description 22",
             "name3.name33.name333" -> "description 333")

what is a simple way to extract each name and each description and feed them into a method such as

def process(description: String, name: String*): Unit = name match {
  case Seq(n)     =>  // find(n).set(description)
  case Seq(n,m)   =>  // find(n).find(m).set(description)
  case Seq(n,m,o) =>  // find(n).find(m).find(o).set(description)
  case _          =>  // possible error reporting
}

Many Thanks

I guess you mean def process(tuple: (String, String)*) or def process(description: String, name: String), as either you can to process each entry one by one, or process all entries at once (which mean more than one 1 description). — cchantep
– cchantep, Commented Aug 18, 2014 at 10:14

Ende Neu · Accepted Answer · 2014-08-18 10:15:01Z

2

You can use the splat operator _*:

val in = Map("name1" -> "description1",
  "name2.name22" -> "description 22",
  "name3.name33.name333" -> "description 333")

def process(description: String, name: String*) = ???


in.map { x =>
  process(x._2, x._1.split("\\."): _*)
}

Note that * parameters must come last in the function signature (otherwise the compiler won't be able to decide where to stop).

From the REPL:

scala>   def process(description: String, name: String*) = {
     |     name.foreach(println)
     |     println(description)
     |   }
process: (description: String, name: String*)Unit

scala>   in.map { x =>
      |    process(x._2, x._1.split("\\."): _*)
      |   }
    name1
    description1
    name2
    name22
    description 22
    name3
    name33
    name333
    description 333

edited Aug 18, 2014 at 10:15

answered Aug 18, 2014 at 10:07

Ende Neu

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Comments

elm · Accepted Answer · 2014-08-18 10:36:54Z

1

You can do something like:

in foreach { case (ns, d) => process(d, ns.split("\\."): _*) }

edited Aug 18, 2014 at 10:36

elm

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answered Aug 18, 2014 at 10:25

cchantep

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