def parseTimestampString()

in sql/api/src/main/scala/org/apache/spark/sql/catalyst/util/SparkDateTimeUtils.scala [478:627]
139 lines of code
52 McCabe index (conditional complexity)

  def parseTimestampString(s: UTF8String): (Array[Int], Option[ZoneId], Boolean) = {
    def isValidDigits(segment: Int, digits: Int): Boolean = {
      // A Long is able to represent a timestamp within [+-]200 thousand years
      val maxDigitsYear = 6
      // For the nanosecond part, more than 6 digits is allowed, but will be truncated.
      segment == 6 || (segment == 0 && digits >= 4 && digits <= maxDigitsYear) ||
      // For the zoneId segment(7), it's could be zero digits when it's a region-based zone ID
      (segment == 7 && digits <= 2) ||
      (segment != 0 && segment != 6 && segment != 7 && digits > 0 && digits <= 2)
    }
    if (s == null) {
      return (Array.empty, None, false)
    }
    var tz: Option[String] = None
    val segments: Array[Int] = Array[Int](1, 1, 1, 0, 0, 0, 0, 0, 0)
    var i = 0
    var currentSegmentValue = 0
    var currentSegmentDigits = 0
    val bytes = s.getBytes
    var j = getTrimmedStart(bytes)
    val strEndTrimmed = getTrimmedEnd(j, bytes)

    if (j == strEndTrimmed) {
      return (Array.empty, None, false)
    }

    var digitsMilli = 0
    var justTime = false
    var yearSign: Option[Int] = None
    if (bytes(j) == '-' || bytes(j) == '+') {
      yearSign = if (bytes(j) == '-') Some(-1) else Some(1)
      j += 1
    }
    while (j < strEndTrimmed) {
      val b = bytes(j)
      val parsedValue = b - '0'.toByte
      if (parsedValue < 0 || parsedValue > 9) {
        if (j == 0 && b == 'T') {
          justTime = true
          i += 3
        } else if (i < 2) {
          if (b == '-') {
            if (!isValidDigits(i, currentSegmentDigits)) {
              return (Array.empty, None, false)
            }
            segments(i) = currentSegmentValue
            currentSegmentValue = 0
            currentSegmentDigits = 0
            i += 1
          } else if (i == 0 && b == ':' && yearSign.isEmpty) {
            justTime = true
            if (!isValidDigits(3, currentSegmentDigits)) {
              return (Array.empty, None, false)
            }
            segments(3) = currentSegmentValue
            currentSegmentValue = 0
            currentSegmentDigits = 0
            i = 4
          } else {
            return (Array.empty, None, false)
          }
        } else if (i == 2) {
          if (b == ' ' || b == 'T') {
            if (!isValidDigits(i, currentSegmentDigits)) {
              return (Array.empty, None, false)
            }
            segments(i) = currentSegmentValue
            currentSegmentValue = 0
            currentSegmentDigits = 0
            i += 1
          } else {
            return (Array.empty, None, false)
          }
        } else if (i == 3 || i == 4) {
          if (b == ':') {
            if (!isValidDigits(i, currentSegmentDigits)) {
              return (Array.empty, None, false)
            }
            segments(i) = currentSegmentValue
            currentSegmentValue = 0
            currentSegmentDigits = 0
            i += 1
          } else {
            return (Array.empty, None, false)
          }
        } else if (i == 5 || i == 6) {
          if (b == '.' && i == 5) {
            if (!isValidDigits(i, currentSegmentDigits)) {
              return (Array.empty, None, false)
            }
            segments(i) = currentSegmentValue
            currentSegmentValue = 0
            currentSegmentDigits = 0
            i += 1
          } else {
            if (!isValidDigits(i, currentSegmentDigits)) {
              return (Array.empty, None, false)
            }
            segments(i) = currentSegmentValue
            currentSegmentValue = 0
            currentSegmentDigits = 0
            i += 1
            tz = Some(new String(bytes, j, strEndTrimmed - j))
            j = strEndTrimmed - 1
          }
          if (i == 6 && b != '.') {
            i += 1
          }
        } else {
          if (i < segments.length && (b == ':' || b == ' ')) {
            if (!isValidDigits(i, currentSegmentDigits)) {
              return (Array.empty, None, false)
            }
            segments(i) = currentSegmentValue
            currentSegmentValue = 0
            currentSegmentDigits = 0
            i += 1
          } else {
            return (Array.empty, None, false)
          }
        }
      } else {
        if (i == 6) {
          digitsMilli += 1
        }
        // We will truncate the nanosecond part if there are more than 6 digits, which results
        // in loss of precision
        if (i != 6 || currentSegmentDigits < 6) {
          currentSegmentValue = currentSegmentValue * 10 + parsedValue
        }
        currentSegmentDigits += 1
      }
      j += 1
    }

    if (!isValidDigits(i, currentSegmentDigits)) {
      return (Array.empty, None, false)
    }
    segments(i) = currentSegmentValue

    while (digitsMilli < 6) {
      segments(6) *= 10
      digitsMilli += 1
    }

    // This step also validates time zone part
    val zoneId = tz.map(zoneName => getZoneId(zoneName.trim))
    segments(0) *= yearSign.getOrElse(1)
    (segments, zoneId, justTime)
  }