stevelacy/go-urbit noun from string

noun_fromstr.go

func IsStrAtom(str string) bool {
  for _, c := range str {
    if !unicode.IsDigit(c) {
      return false
    }
  }
  return true
}

// is this string noun an explicit cell?
// explicit: begins and ends with [ and ] respectively
//           and has valid inner brackets
func IsStrXCell(str string) bool {
  if str[0] != '[' {
    return false
  }

  brax := 0
  for i, c := range str {
    if c == '[' {
      brax += 1
    }
    if c == ']' {
      brax -= 1
    }

    if brax == 0 {
      return i == len(str)-1
    }
  }
  return false
}

// return split index
func SplitStrCell(str string) int {
  brax := 0
  for i, c := range str {
    if c == '[' {
      brax += 1
    }
    if c == ']' {
      brax -= 1
    }
    if c == ' ' && brax == 0 {
      return i
    }
  }

  // TODO error here
  return -99
}

func NounFromString(str string) Noun {
  if IsStrAtom(str) {
    i, err := strconv.ParseInt(str, 10, 64)
    if err != nil {
      bi := B(0)
      bi, ok := bi.SetString(str, 10)
      if !ok {
        fmt.Println("SetString: error")
        panic(err)
      }
      return MakeNoun(bi)
    }
    return MakeNoun(i)
  }

  if IsStrXCell(str) {
    str = str[1 : len(str)-1]
  }

  split := SplitStrCell(str)

  headRes := NounFromString(str[:split])
  tailRes := NounFromString(str[split+1:])
  res := MakeNoun([]interface{}{headRes, tailRes})
  return res
}
// example:
// n := NounFromString("[[[1 1] [2 2]] 2 2]")