Case insensitive pattern matching for strings

Question

match (str) {
  case "String1" => ???
  case "String2" => ???
}

This is case sensitive matching. How to write case insensitive matching? I know I can call toLowerCase for each branch, but I want more elegant solution.

Answer 1

Basic approach:

You could use Pattern Guards and Regular Expressions

str match {
case s if s matches "(?i)String1" => 1
case s if s matches "(?i)String2" => 2
case _ => 0
}

Sophisticated method:

Implicits with String Interpolation and Regex

implicit class CaseInsensitiveRegex(sc: StringContext) {
  def ci = ( "(?i)" + sc.parts.mkString ).r
}

def doStringMatch(str: String) = str match {
  case ci"String1" => 1
  case ci"String2" => 2
  case _ => 0
}

Some example usage in the REPL:

scala> doStringMatch("StRINg1")
res5: Int = 1

scala> doStringMatch("sTring2")
res8: Int = 2

Answer 2

Easy solution:

val str = "string1"

str toUpperCase match (str) {
  case "STRING1" => ???
  case "STRING2" => ???
}