HQ9Plus.kt

fun <T> Array<T>.component1() = this.get(0)
fun <T> Array<T>.component2() = this.get(1)

class HQ9Plus(private val src: String) {
  private var count = 0

  fun eval() {
    src.forEach {
      when(it){
        'H' -> hello()
        'Q' -> printSrc()
        '9' -> print99BottlesOfBeer()
        '+' -> increment()
        else -> null
      }
    }
  }

  private fun printSrc() = println(src)

  private fun hello() = println("Hello, world")

  private fun print99BottlesOfBeer() {
    99.downTo(0).forEach { i ->
      var (before, after) = when (i) {
        0 -> array("no more bottles", "99 bottles")
        1 -> array("1 bottle", "no more bottles")
        2 -> array("2 bottles", "1 bottle")
        else -> array("$i bottles", "${i - 1} bottles")
      }

      var action = if(i == 0){
        "Go to the store and buy some more"
      } else {
        "Take one down and pass it around"
      }

      println("${before.capitalize()} of beer on the wall, $before of beer.")
      println("$action, $after of beer on the wall.")
      if(i != 0){ println() }
    }
  }

  private fun increment() = count++
}