Method ReadLinearScalingFactor

src/cpp/web-ifc/cache/IfcCache.cpp:184–303

  }

  void IfcCache::ReadLinearScalingFactor()
  {
    auto projects = _loader.GetExpressIDsWithType(schema::IFCPROJECT);

    if (projects.size() != 1)
    {
      spdlog::error("[ReadLinearScalingFactor()] unexpected empty ifc project");
      return;
    }

    auto projectEID = projects[0];
    _loader.MoveToArgumentOffset(projectEID, 8);
    auto tk = _loader.GetTokenType();
    _loader.StepBack();
    if (tk != parsing::REF)
    {
        // IfcProject::UnitsInContext is an optional argument, no error or warning
        return;
    }

    auto unitsID = _loader.GetRefArgument();
    _loader.MoveToArgumentOffset(unitsID, 0);

    tk = _loader.GetTokenType();
    _loader.StepBack();
    if (tk != parsing::SET_BEGIN)
    {
        // IfcUnitAssignment::Units vector can be empty. Avoid infinite loop in _loader.GetSetArgument()
        return;
    }
    auto unitIds = _loader.GetSetArgument();

    for (auto &unitID : unitIds)
    {
      auto unitRef = _loader.GetRefArgument(unitID);
      auto lineType = _loader.GetLineType(unitRef);

      if (lineType == schema::IFCSIUNIT)
      {
        _loader.MoveToArgumentOffset(unitRef, 1);
        std::string_view unitType = _loader.GetStringArgument();

        std::string_view unitPrefix;

        _loader.MoveToArgumentOffset(unitRef, 2);
        if (_loader.GetTokenType() == parsing::IfcTokenType::ENUM)
        {
          _loader.StepBack();
          unitPrefix = _loader.GetStringArgument();
        }

        _loader.MoveToArgumentOffset(unitRef, 3);
        std::string_view unitName = _loader.GetStringArgument();

        if (unitType == "LENGTHUNIT" && unitName == "METRE")
        {
          double prefix = ConvertPrefix(unitPrefix);
          _linearScalingFactor *= prefix;