package playground

import org.parboiled2._


class Playground (val input: ParserInput) extends Parser {

  type R0 = Rule0
  type R[T] = Rule1[T]
  type R1 = R[String]

  def TestedRule = rule {
    Expr ~ EOI
  }

  def Expr: R1 = rule {Plus | Mult | Prim}

  def Prim: R1 = rule {capture(CharPredicate.Digit.*)}

  def Mult: R1 = rule {TwoOrMoreSil(() => MultSeq, () => MultSign) ~> {seq: Seq[String] => Stringify(seq, "mult")}}
  def MultSeq: R1 = rule {Prim ~ &(MultSign | EOI) | Plus}

  def Plus: R1 = rule {TwoOrMoreSil(() => PlusSeq, () => PlusSign) ~> {seq: Seq[String] => Stringify(seq, "plus")}}
  def PlusSeq: R1 = rule {Prim ~ &(PlusSign | EOI) | Mult}

  def PlusSign: R0 = rule('+')
  def MultSign: R0 = rule('*')

  def WL: R0 = rule {"\n"}
  def WS: R0 = rule {" "}

  def Stringify(seq: Seq[String], method: String) = s"""$method(${seq.mkString(",")})"""

  def TwoOrMoreSil[T](term: () => Rule1[T], delim: () => Rule0): Rule1[Seq[T]] = rule {
    term() ~ delim() ~ term().+(delim()) ~> {(first: T, rest: Seq[T]) => first +: rest}
  }

}