scalapb.json4s.NameUtils.scala Maven / Gradle / Ivy

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package scalapb.json4s

object NameUtils {
  def snakeCaseToCamelCase(
      name: String,
      upperInitial: Boolean = false
  ): String = {
    val b = new StringBuilder()
    @annotation.tailrec
    def inner(name: String, index: Int, capNext: Boolean): Unit =
      if (name.nonEmpty) {
        val (r, capNext2) = name.head match {
          case c if c.isLower => (Some(if (capNext) c.toUpper else c), false)
          case c if c.isUpper =>
            // force first letter to lower unless forced to capitalize it.
            (Some(if (index == 0 && !capNext) c.toLower else c), false)
          case c if c.isDigit => (Some(c), true)
          case _              => (None, true)
        }
        r.foreach(b.append)
        inner(name.tail, index + 1, capNext2)
      }
    inner(name, 0, upperInitial)
    b.toString
  }
}