system.cpp

// system graphs - only a few interesting systems; many aren't useful on their own
file.open(Args::datapath+"/graphs/systemgraphs.csv");
getline(file, line);  // ignore header line

while (getline(file, line))
  try {	HighwaySystem* const h = HighwaySystem::sysname_hash.at(line);
	if (h->active_or_preview())
	{   GraphListEntry::add_group(
		h->systemname + "-system",
		h->systemname + " (" + h->fullname + ")",
		's', nullptr, new vector<HighwaySystem*>(1, h), nullptr, el);
			      // deleted @ end of HighwayGraph::write_subgraphs_tmg
	    h->is_subgraph_system = 1;
	} else el.add_error("devel system "+h->systemname+" in systemgraphs.csv");
      }
  catch (const std::out_of_range&)
      {	el.add_error("unrecognized system code "+line+" in systemgraphs.csv");
      }
file.close();
graph_types.push_back({"system", "Routes Within a Single Highway System",
		       "These graphs contain the routes within a single highway system and are not restricted by region."});