LogLevel stringToLogLevel()

in folly/logging/LogLevel.cpp [43:108]

• 57 lines of code
• 24 McCabe index (conditional complexity)

LogLevel stringToLogLevel(StringPiece name) {
  string lowerNameStr;
  lowerNameStr.reserve(name.size());
  for (char c : name) {
    lowerNameStr.push_back(static_cast<char>(std::tolower(c)));
  }
  StringPiece lowerName{lowerNameStr};

  // If the string is of the form "LogLevel::foo" or "LogLevel(foo)"
  // strip it down just to "foo".  This makes sure we can process both
  // the "LogLevel::WARN" and "LogLevel(1234)" formats produced by
  // logLevelToString().
  constexpr StringPiece lowercasePrefix{"loglevel::"};
  constexpr StringPiece wrapperPrefix{"loglevel("};
  if (lowerName.startsWith(lowercasePrefix)) {
    lowerName.advance(lowercasePrefix.size());
  } else if (lowerName.startsWith(wrapperPrefix) && lowerName.endsWith(")")) {
    lowerName.advance(wrapperPrefix.size());
    lowerName.subtract(1);
  }

  if (lowerName == "uninitialized") {
    return LogLevel::UNINITIALIZED;
  } else if (lowerName == "none") {
    return LogLevel::NONE;
  } else if (lowerName == "debug" || lowerName == "dbg") {
    return LogLevel::DBG;
  } else if (lowerName == "info") {
    return LogLevel::INFO;
  } else if (lowerName == "warn" || lowerName == "warning") {
    return LogLevel::WARN;
  } else if (lowerName == "error" || lowerName == "err") {
    return LogLevel::ERR;
  } else if (lowerName == "critical") {
    return LogLevel::CRITICAL;
  } else if (lowerName == "dfatal") {
    return LogLevel::DFATAL;
  } else if (lowerName == "fatal") {
    return LogLevel::FATAL;
  } else if (lowerName == "max" || lowerName == "max_level") {
    return LogLevel::MAX_LEVEL;
  }

  for (const auto& info : numberedLogLevels) {
    if (!lowerName.startsWith(info.lowerPrefix)) {
      continue;
    }
    auto remainder = lowerName.subpiece(info.lowerPrefix.size());
    auto level = folly::tryTo<int>(remainder).value_or(-1);
    if (level < 0 ||
        static_cast<unsigned int>(level) > (static_cast<uint32_t>(info.max) -
                                            static_cast<uint32_t>(info.min))) {
      throw std::range_error(to<string>(
          "invalid ", info.lowerPrefix, " logger level: ", name.str()));
    }
    return info.max - level;
  }

  // Try as an plain integer if all else fails
  try {
    auto level = folly::to<uint32_t>(lowerName);
    return static_cast<LogLevel>(level);
  } catch (const std::exception&) {
    throw std::range_error("invalid logger level: " + name.str());
  }
}