override def sumOption()

in algebird-core/src/main/scala/com/twitter/algebird/Eventually.scala [77:114]

33 lines of code
10 McCabe index (conditional complexity)


  override def sumOption(iter: TraversableOnce[Either[E, O]]): Option[Either[E, O]] = {

    def toEventualBuffer[R](buffer: Buffer[O], e: E): Left[Buffer[E], R] = {
      val newBuffer = Buffer[E]()
      Semigroup.sumOption(buffer).foreach(sum => newBuffer += convert(sum))
      newBuffer += e
      Left(newBuffer)
    }

    iter.iterator.foldLeft[Either[Buffer[E], Buffer[O]]](Right(Buffer[O]())) {
      case (buffer @ Left(be), v) =>
        // turns the list of either into an either of lists
        checkSize(be)
        v match {
          case Left(ve)  => be += ve
          case Right(vo) => be += convert(vo)
        }
        buffer // left stays left we just add to the buffer and convert if needed
      case (buffer @ Right(bo), v) =>
        checkSize(bo)
        v match {
          // one Left eventual value => the right list needs to be converted
          case Left(ve) => toEventualBuffer(bo, ve)
          // otherwise stays Right, just add to the buffer
          case Right(vo) =>
            bo += vo
            buffer
        }
    } match { // finally apply sumOption accordingly
      case Left(be) => Semigroup.sumOption(be).map(left(_))
      case Right(bo) =>
        if (bo.lengthCompare(1) <= 0) bo.headOption.map(Right(_))
        else
          Semigroup
            .sumOption(bo)
            .map(conditionallyConvert(_)) // and optionally convert
    }
  }