How to remove comments from the scala code

Any ideas how to remove comments from the scala code so that:

Nested multi line or single line comments are removed.
Comments inside string literals are not removed.
Code can have single and triple quote literals.
String literals can contain escaped quote chars.

Here is example code with comments:

object TestCode {

  val a = "A" // a = "AA"
  val b = "B" /* b = "BB" */
  val c = "C" /* multi line comment
  /* c = "CC" nested */ // FOO
  */ // c = "CCC"
  val d = """D""" // d = """DD /* """
  val e = '"' // e = '"' = char literal
  val f = '\"' // f = '\"' = char literal
  val codeStr = " \"  \"\" \"\"\"/* This is literal */\"\"\" val x = \"\"\"5\"\"\" \" "
  "/* This is a literal */" // This is a comment 3
  "// This is a literal with extra comment end string */" // This is a comment 4
  "/* This is a litral with extra comment begin string" // This is a comment 5

}

Code compiles (with warnings about pure expressions).

The C preprocessor gets quite close but fails with nested comments.

object TestCode {
  val a = "A"
  val b = "B"
  val c = "C"
  */
  val d = """D"""
  val e = '"'
  val f = '\"'
  val codeStr = " \"  \"\" \"\"\"/* This is literal */\"\"\" val x = \"\"\"5\"\"\" \" "
  "/* This is a literal */"
  "// This is a literal with extra comment end string */"
  "/* This is a litral with extra comment begin string"
}

I also tried this regex solution but it seems that it fails in case of quote char literals and nested comments as you see:

str.replaceAll("//.*|/\\*(?s:.*?)\\*/|(\"(?:(?<!\\\\)(?:\\\\\\\\)*\\\\\"|[^\r\n\"])*\")", "$1")
res1: String = """object TestCode {

  val a = "A" 
  val b = "B" 
  val c = "C"  
  */ 
  val d = """D""" 
  val e = '"' // e = '"' = char literal
  val f = '\"' // f = '\"' = char literal
  val codeStr = " \"  \"\" \"\"\"/* This is literal */\"\"\" val x = \"\"\"5\"\"\" \" "
  "/* This is a literal */" 
  "// This is a literal with extra comment end string */" 
  "/* This is a literal with extra comment begin string" 

}"""

Scala compiler can do the job but for my understanding there is no compiler option to do just the comment removal.

Solution

I used Mateusz Kubuszok's proposal and used ScalaMeta for the implementation.

This is the scala-cli script file: SourceCodeCommentRemover.scala

//> using scala "2.13.5"
//> using lib "org.scalameta::scalameta:4.9.7"

import scala.meta._
import java.io.{File, PrintWriter}

object CommentRemover {
  def main(args: Array[String]): Unit = {
    if (args.length != 2) {
      println("Usage: CommentRemover <input file> <output file>")
      sys.exit(1)
    }

    val inputFile = new File(args(0))
    val outputFile = new File(args(1))

    if (!inputFile.exists()) {
      println(s"Input file ${inputFile.getAbsolutePath} does not exist.")
      sys.exit(1)
    }

    val sourceCode = {
      import scala.io.Source
      Source.fromFile(inputFile).mkString
    }

    println(s"Original source: BEGIN\n${sourceCode}\nEND")

    val tree = sourceCode.parse[Source] match {
      case parsers.Parsed.Success(tree) => tree
      case parsers.Parsed.Error(_, msg, _) =>
        println(s"Failed to parse the input file: $msg")
        sys.exit(1)
    }

    val codeWithoutComments = tree.tokens.collect {
      case token if !token.is[Token.Comment] => token.text
    }.mkString

    println(s"Comments removed: BEGIN\n${codeWithoutComments}\nEND")

    val writer = new PrintWriter(outputFile)
    try {
      writer.write(codeWithoutComments)
    } finally {
      writer.close()
    }

    println(s"Comments removed. Output written to ${outputFile.getAbsolutePath}.")
  }
}

This is the test input file: StackOverflowTestCode.scala

object TestCode {

  val a = "A" // a = "AA"
  val b = "B" /* b = "BB" */
  val c = "C" /* multi line comment
  /* c = "CC" nested */ // FOO
  */ // c = "CCC"
  val d = """D""" // d = """DD /* """
  val e = '"' // e = '"' = char literal
  val f = '\"' // f = '\"' = char literal
  val codeStr = " \"  \"\" \"\"\"/* This is literal */\"\"\" val x = \"\"\"5\"\"\" \" "
  "/* This is a literal */" // This is a comment 3
  "// This is a literal with extra comment end string */" // This is a comment 4
  "/* This is a litral with extra comment begin string" // This is a comment 5

}

Run the script:

scala-cli run SourceCodeCommentRemover.scala -- StackOverflowTestCode.scala out.scala

cat  out.scala

object TestCode {

  val a = "A" 
  val b = "B" 
  val c = "C"  
  val d = """D""" 
  val e = '"' 
  val f = '\"' 
  val codeStr = " \"  \"\" \"\"\"/* This is literal */\"\"\" val x = \"\"\"5\"\"\" \" "
  "/* This is a literal */" 
  "// This is a literal with extra comment end string */" 
  "/* This is a litral with extra comment begin string" 

}

Scala-cli version:

scala-cli --version
Scala CLI version: 1.4.1
Scala version (default): 3.4.2