Method AsNumberWithUnit

simcore/framework/src/cli/cli.hpp:2961–3022

  template <typename Number>
  explicit AsNumberWithUnit(std::map<std::string, Number> mapping, Options opts = DEFAULT,
                            const std::string &unit_name = "UNIT") {
    description(generate_description<Number>(unit_name, opts));
    validate_mapping(mapping, opts);

    // transform function
    func_ = [mapping, opts](std::string &input) -> std::string {
      Number num;

      detail::rtrim(input);
      if (input.empty()) {
        throw ValidationError("Input is empty");
      }

      // Find split position between number and prefix
      auto unit_begin = input.end();
      while (unit_begin > input.begin() && std::isalpha(*(unit_begin - 1), std::locale())) {
        --unit_begin;
      }

      std::string unit{unit_begin, input.end()};
      input.resize(static_cast<std::size_t>(std::distance(input.begin(), unit_begin)));
      detail::trim(input);

      if (opts & UNIT_REQUIRED && unit.empty()) {
        throw ValidationError("Missing mandatory unit");
      }
      if (opts & CASE_INSENSITIVE) {
        unit = detail::to_lower(unit);
      }

      bool converted = detail::lexical_cast(input, num);
      if (!converted) {
        throw ValidationError(std::string("Value ") + input + " could not be converted to " +
                              detail::type_name<Number>());
      }

      if (unit.empty()) {
        // No need to modify input if no unit passed
        return {};
      }

      // find corresponding factor
      auto it = mapping.find(unit);
      if (it == mapping.end()) {
        throw ValidationError(unit +
                              " unit not recognized. "
                              "Allowed values: " +
                              detail::generate_map(mapping, true));
      }

      // perform safe multiplication
      bool ok = detail::checked_multiply(num, it->second);
      if (!ok) {
        throw ValidationError(detail::to_string(num) + " multiplied by " + unit +
                              " factor would cause number overflow. Use smaller value.");
      }
      input = detail::to_string(num);