func parseIndividualArg()

in Sources/ArgumentParser/Parsing/SplitArguments.swift [529:578]

• 42 lines of code
• 10 McCabe index (conditional complexity)

func parseIndividualArg(_ arg: String, at position: Int) throws -> [SplitArguments.Element] {
  let index = SplitArguments.Index(inputIndex: .init(rawValue: position))
  if let nonDashIdx = arg.firstIndex(where: { $0 != "-" }) {
    let dashCount = arg.distance(from: arg.startIndex, to: nonDashIdx)
    let remainder = arg[nonDashIdx..<arg.endIndex]
    switch dashCount {
    case 0:
      return [.value(arg, index: index)]
    case 1:
      // Long option:
      let parsed = try ParsedArgument(longArgWithSingleDashRemainder: remainder)
      
      // Short options:
      let parts = parsed.subarguments
      switch parts.count {
      case 0:
        // This is a '-name=value' style argument
        return [.option(parsed, index: index)]
      case 1:
        // This is a single short '-n' style argument
        return [.option(.name(.short(remainder.first!)), index: index)]
      default:
        var result: [SplitArguments.Element] = [.option(parsed, index: index)]
        for (sub, a) in parts {
          var i = index
          i.subIndex = .sub(sub)
          result.append(.option(a, index: i))
        }
        return result
      }
    case 2:
      return [.option(ParsedArgument(arg), index: index)]
    default:
      throw ParserError.invalidOption(arg)
    }
  } else {
    // All dashes
    let dashCount = arg.count
    switch dashCount {
    case 0, 1:
      // Empty string or single dash
      return [.value(arg, index: index)]
    case 2:
      // We found the 1st "--". All the remaining are positional.
      return [.terminator(index: index)]
    default:
      throw ParserError.invalidOption(arg)
    }
  }
}