Advent of Code 2020 Day 8

import scala.io.Source

object Day8 extends App {
  abstract class Instruction(var f:(() => Unit), var timesRun:Int = 0){
    val originalF = f
    def run() = {pc += 1;f(); timesRun += 1}
    def switch() = ()
    def restore() = f = originalF
  }
  case class Acc(parameter:Int) extends Instruction(() => acc += parameter)
  case class Jmp(parameter:Int) extends Instruction(() => pc += parameter - 1){override def switch() = f = () => ()}
  case class Nop(parameter:Int) extends Instruction(() => ()){override def switch() = f = () => pc += parameter - 1}

  val PATTERN = """(\w{3}) ((?:[+]|[-])\d+)""".r
  val instructions = Source.fromFile("day8").getLines().map{
    case PATTERN(op,parameter) =>
      op match {
      case "acc" => new Acc(parameter.toInt) case "jmp" => new Jmp(parameter.toInt) case "nop" => new Nop(parameter.toInt)
    }
  }.toList
  var pc = 0; var acc = 0;

  def run(reset:Boolean = true):Boolean = {
    if(reset){ instructions.foreach(x => x.timesRun = 0); acc = 0; pc = 0 }
    instructions(pc).run()
    if(pc >= instructions.length) true else if (instructions(pc).timesRun < 1) run(false) else false
  }
  run()
  println("part 1: " + acc)
  println("part 2: " + instructions.indices.map{ x => instructions(x).switch(); val result = (run(),acc); instructions(x).restore(); result}.filter(x => x._1).head._2)
}