How to lowercase the capture group only in scala

Question

This code:

"""{"nAMe": "Deloise", "WINS": [["three of a kind", "5♣"]]}""".replaceAll("""(\"[^"]+\" *:)""", "|UPERCASETEST|$1|".toLowerCase())

Produces :

String = {|upercasetest|"nAMe":| "Deloise", |upercasetest|"WINS":| [["three of a kind", "5♣"]]}

While I was expecting :

String = {|upercasetest|"name":| "Deloise", |upercasetest|"wins":| [["three of a kind", "5♣"]]}

Any idea on why the capture group does not wish to lowercase and how to fix it?

Answer 1

You need to pass the match object to a lambda expression inside replaceAllIn where you may manipulate the contents, otherwise, inside replaceAll, the $1 does not get "expanded" to the actual Group 1 submatch value:

val s = """{"nAMe": "Deloise", "WINS": [["three of a kind", "5♣"]]}"""
val rx = """(\"[^"]+\" *:)""".r
val replacedStr = rx replaceAllIn (s, m => s"|UPERCASETEST|${m.group(1)}|".toLowerCase())
println(replacedStr)

See Scala demo

Output:

{|upercasetest|"name":| "Deloise", |upercasetest|"wins":| [["three of a kind", "5♣"]]}