def unescapeSQLString()

in kyuubi-server/src/main/scala/org/apache/kyuubi/sql/parser/KyuubiParserBase.scala [52:113]
51 lines of code
22 McCabe index (conditional complexity)

  def unescapeSQLString(b: String): String = {
    val sb = new StringBuilder(b.length())

    def appendEscapedChar(n: Char): Unit = {
      n match {
        case '0' => sb.append('\u0000')
        case '\'' => sb.append('\'')
        case '"' => sb.append('\"')
        case 'b' => sb.append('\b')
        case 'n' => sb.append('\n')
        case 'r' => sb.append('\r')
        case 't' => sb.append('\t')
        case 'Z' => sb.append('\u001A')
        case '\\' => sb.append('\\')
        // The following 2 lines are exactly what MySQL does TODO: why do we do this?
        case '%' => sb.append("\\%")
        case '_' => sb.append("\\_")
        case _ => sb.append(n)
      }
    }

    if (b.startsWith("r") || b.startsWith("R")) {
      b.substring(2, b.length - 1)
    } else {
      // Skip the first and last quotations enclosing the string literal.
      val charBuffer = CharBuffer.wrap(b, 1, b.length - 1)

      while (charBuffer.remaining() > 0) {
        charBuffer match {
          case U16_CHAR_PATTERN(cp) =>
            // \u0000 style 16-bit unicode character literals.
            sb.append(Integer.parseInt(cp, 16).toChar)
            charBuffer.position(charBuffer.position() + 6)
          case U32_CHAR_PATTERN(cp) =>
            // \U00000000 style 32-bit unicode character literals.
            // Use Long to treat codePoint as unsigned in the range of 32-bit.
            val codePoint = JLong.parseLong(cp, 16)
            if (codePoint < 0x10000) {
              sb.append((codePoint & 0xFFFF).toChar)
            } else {
              val highSurrogate = (codePoint - 0x10000) / 0x400 + 0xD800
              val lowSurrogate = (codePoint - 0x10000) % 0x400 + 0xDC00
              sb.append(highSurrogate.toChar)
              sb.append(lowSurrogate.toChar)
            }
            charBuffer.position(charBuffer.position() + 10)
          case OCTAL_CHAR_PATTERN(cp) =>
            // \000 style character literals.
            sb.append(Integer.parseInt(cp, 8).toChar)
            charBuffer.position(charBuffer.position() + 4)
          case ESCAPED_CHAR_PATTERN(c) =>
            // escaped character literals.
            appendEscapedChar(c.charAt(0))
            charBuffer.position(charBuffer.position() + 2)
          case _ =>
            // non-escaped character literals.
            sb.append(charBuffer.get())
        }
      }
      sb.toString()
    }
  }