std::shared_ptr buildMysqlDateTimeFormatter()

in velox/functions/lib/DateTimeFormatter.cpp [307:429]

• 120 lines of code
• 38 McCabe index (conditional complexity)

std::shared_ptr<DateTimeFormatter> buildMysqlDateTimeFormatter(
    const std::string_view& format) {
  // For %r we should reserve 1 extra space because it has 3 literals ':' ':'
  // and ' '
  DateTimeFormatterBuilder builder(
      format.size() + countOccurence(format, "%r"));

  const char* cur = format.data();
  const char* end = cur + format.size();
  while (cur < end) {
    auto tokenEnd = cur;
    if (*tokenEnd == '%') { // pattern
      ++tokenEnd;
      if (tokenEnd == end) {
        break;
      }
      switch (*tokenEnd) {
        case 'a':
          builder.appendDayOfWeekText(3);
          break;
        case 'b':
          builder.appendMonthOfYearText(3);
          break;
        case 'c':
          builder.appendMonthOfYear(1);
          break;
        case 'd':
          builder.appendDayOfMonth(2);
          break;
        case 'e':
          builder.appendDayOfMonth(1);
          break;
        case 'f':
          builder.appendFractionOfSecond(6);
          break;
        case 'H':
          builder.appendHourOfDay(2);
          break;
        case 'h':
        case 'I':
          builder.appendClockHourOfHalfDay(2);
          break;
        case 'i':
          builder.appendMinuteOfHour(2);
          break;
        case 'j':
          builder.appendDayOfYear(3);
          break;
        case 'k':
          builder.appendHourOfDay(1);
          break;
        case 'l':
          builder.appendClockHourOfHalfDay(1);
          break;
        case 'M':
          builder.appendMonthOfYearText(4);
          break;
        case 'm':
          builder.appendMonthOfYear(2);
          break;
        case 'p':
          builder.appendHalfDayOfDay();
          break;
        case 'r':
          builder.appendClockHourOfHalfDay(2);
          builder.appendLiteral(":");
          builder.appendMinuteOfHour(2);
          builder.appendLiteral(":");
          builder.appendSecondOfMinute(2);
          builder.appendLiteral(" ");
          builder.appendHalfDayOfDay();
          break;
        case 'S':
        case 's':
          builder.appendSecondOfMinute(2);
          break;
        case 'T':
          builder.appendHourOfDay(2);
          builder.appendLiteral(":");
          builder.appendMinuteOfHour(2);
          builder.appendLiteral(":");
          builder.appendSecondOfMinute(2);
          break;
        case 'v':
          builder.appendWeekOfWeekYear(2);
          break;
        case 'W':
          builder.appendDayOfWeekText(4);
          break;
        case 'x':
          builder.appendWeekYear(4);
          break;
        case 'Y':
          builder.appendYear(4);
          break;
        case 'y':
          builder.appendYear(2);
          break;
        case '%':
          builder.appendLiteral("%");
          break;
        case 'D':
        case 'U':
        case 'u':
        case 'V':
        case 'w':
        case 'X':
          VELOX_UNSUPPORTED("Specifier {} is not supported.", *tokenEnd)
        default:
          builder.appendLiteral(tokenEnd, 1);
          break;
      }
      ++tokenEnd;
    } else {
      while (tokenEnd < end && *tokenEnd != '%') {
        ++tokenEnd;
      }
      builder.appendLiteral(cur, tokenEnd - cur);
    }
    cur = tokenEnd;
  }
  return builder.build();
}