Stupid and simple convert a Scala file (already renamed to .kt extension) to Kotlin

scala-to-kotlin.kts

#!/usr/bin/env kscript

import java.io.File

// usage - one argument a .kt file (Scala file that was only renamed)
// or a directory
try {
  main(args)
} catch (e: Exception) {
  e.printStackTrace()
}

fun convert(lines: List<String>): List<String> {
  val methodNoBracsRegex = ".*fun\\s+\\w+\\s+[:=].*".toRegex()
  val linesWithoutLicense = lines
//  The below lines just removed license comment
//       if (lines[0].startsWith("package "))
//         lines
//       else
//         lines.drop(15)
  val result = mutableListOf<String>()
  linesWithoutLicense.forEach { lineBeforeConv ->
    val convertedLine = lineBeforeConv
        .replace("extends", ":")
        .replace(" def ", " fun ")
        .replace("BigInt(", "BigInteger(")
        .replace("trait", "interface")
        .replace("[", "<")
        .replace("]", ">")
        .replace(" = {", " {")
        .replace(" new ", " ")
        .replace(" Future<", " CompletableFuture<")
        .replace(" Promise<", " CompletableFuture<")
        .replace(" Array<Byte>(", " ByteArray(")
        .replace(" Array<Char>(", " CharArray(")
        .replace("with", ",")
        .replace("match", "when")
        .replace("case class", "data class")
        .replace("case _", "else")
        .replace("case ", "")
        .replace("=>", "->")
        .replace(".asInstanceOf<", " as ") //manually fix >
        .replace("final ", "")
        .replace("fun this(", "constructor(")
        .replace(" Seq<", " List<")
        .replace(" IndexedSeq<", " List<")
        .replace("<:", ":")
    when {
      convertedLine.startsWith("import ") -> {
        val importsLines = if (convertedLine.contains("{")) {
          val before = convertedLine.substringBefore("{")
          convertedLine.substringAfter("{").substringBefore("}").split(",")
              .map { "$before${it.trim()}" }
        } else listOf(convertedLine)
        importsLines.map { it.replace("_", "*") }.forEach {
          result.add(it)
        }
      }
      convertedLine.matches(methodNoBracsRegex) -> {
        if (convertedLine.contains(":"))
          result.add(convertedLine.replace(":", "():"))
        else
          result.add(convertedLine.replace("=", "()="))
      }
      else -> result.add(convertedLine)
    }
  }
  return result
}

fun main(args: Array<String>) {
  val fileName = args[0]
  if (fileName.endsWith(".kt")) {
    workOnFile(fileName)
  } else {
    File(fileName).walk().forEach {
      if (it.name.endsWith(".kt")) {
        workOnFile(it.path)
      }
    }
  }
}

fun readFileAsLinesUsingReadLines(fileName: String): List<String> = File(fileName).readLines()

fun workOnFile(fileName: String) {
  if (!fileName.fileExists) {
    println("WARN: file not exists $fileName")
    return
  }
  println("working on $fileName")
  val lines = readFileAsLinesUsingReadLines(fileName)
  val fileContent = convert(lines).joinToString("\n")
  File(fileName).writeText(fileContent)
}

fileName.fileExists ? how about !File(fileName).isFile

what is the difference?

fun workOnFile(fileName: String) {
if (!fileName.fileExists) {

String.fileExists is not implemented

fileName.fileExists ? how about !File(fileName).isFile

what is the difference?

fun workOnFile(fileName: String) {
if (!fileName.fileExists) {

String.fileExists is not implemented

😀 probably I had this extension somewhere