Function fromTimestampWithTimezoneString

bolt/type/TimestampConversion.cpp:1030–1080

  if (pos < len) {
    size_t timezonePos = pos;
    while (timezonePos < len && !characterIsSpace(str[timezonePos])) {
      timezonePos++;
    }
    std::string_view timezone(str + pos, timezonePos - pos);

    if (timezone.size() > 3) {
      auto opPos = findFirstPlusOrMinus(timezone);
      if (opPos > 0 && opPos != std::string_view::npos) {
        std::set<std::string_view> targets = {
            "UTC", "UCT", "GMT0", "GMT", "UT"};
        if (matchSubstring(timezone, 0, opPos, targets)) {
          timezone = timezone.substr(opPos);
        } else {
          return std::nullopt;
        }
      }
    }

    if ((timezoneID = tz::getTimeZoneID(timezone, false)) == -1) {
      return std::nullopt;
    }

    // Skip any spaces at the end.
    pos = timezonePos;
    skipSpaces(str, len, pos);

    if (pos < len) {
      return std::nullopt;
    }
  }
  return std::make_pair(resultTimestamp, timezoneID);
}

namespace {
CivilDate civilFromDaysSinceEpoch(int64_t daysSinceEpoch) {
  // Algorithm derived from Howard Hinnant's civil calendar conversions.
  // https://howardhinnant.github.io/date_algorithms.html
  // Copyright (c) 2015, 2016 Howard Hinnant
  //
  // This code is licensed under the MIT license.
  // https://github.com/HowardHinnant/date
  int64_t z = daysSinceEpoch + 719468;
  const int64_t era = (z >= 0 ? z : z - 146096) / 146097;
  const uint32_t doe = static_cast<uint32_t>(z - era * 146097);
  const uint32_t yoe =
      (doe - doe / 1460 + doe / 36524 - doe / 146096) / 365; // [0, 399]
  int64_t y = static_cast<int64_t>(yoe) + era * 400;
  const uint32_t doy = doe - (365 * yoe + yoe / 4 - yoe / 100); // [0, 365]
  const uint32_t mp = (5 * doy + 2) / 153; // [0, 11]
  const uint32_t day = doy - (153 * mp + 2) / 5 + 1; // [1, 31]
  const uint32_t month = mp + (mp < 10 ? 3 : -9); // [1, 12]
  y += (month <= 2);
  return {
      static_cast<int32_t>(y),