Function GetCrossBorderPoints

generator/world_roads_builder/world_roads_builder.cpp:120–171

using CrossBorderIndexes = std::vector<size_t>;

std::pair<NodePoints, CrossBorderIndexes> GetCrossBorderPoints(
    std::vector<uint64_t> const & nodeIds, ankerl::unordered_dense::map<uint64_t, ms::LatLon> const & nodes,
    feature::CountriesFilesAffiliation const & mwmMatcher,
    ankerl::unordered_dense::map<std::string, NumMwmId> const & regionToIdMap)
{
  NodePoints nodePoints;
  CrossBorderIndexes crossBorderIndexes;

  std::string prevRegion;
  m2::PointD prevPoint;

  for (auto const & nodeId : nodeIds)
  {
    auto const itNodes = nodes.find(nodeId);
    CHECK(itNodes != nodes.end(), (nodeId));

    m2::PointD const & curPoint = mercator::FromLatLon(itNodes->second);
    auto const & regions = mwmMatcher.GetAffiliations(curPoint);

    if (regions.size() > 1)
    {
      LOG(LWARNING, ("Point", itNodes->second, "belongs to multiple mwms:", regions));
      continue;
    }

    if (regions.empty())
    {
      LOG(LWARNING, ("Point", itNodes->second, "doesn't belong to any mwm."));
      continue;
    }

    auto const & curRegion = regions[0];
    auto const & curMwmId = regionToIdMap.at(curRegion);
    nodePoints.emplace_back(curPoint, curMwmId);

    if (curRegion != prevRegion)
    {
      if (!prevRegion.empty())
      {
        CHECK_GREATER(nodePoints.size(), 1, ());
        // We add index of the previous point.
        crossBorderIndexes.push_back(nodePoints.size() - 2);
      }

      prevRegion = curRegion;
    }

    prevPoint = curPoint;
  }

  return std::make_pair(nodePoints, crossBorderIndexes);
}

std::optional<std::pair<m2::PointD, double>> GetPointInMwm(NodePoints const & points, size_t index, bool forward)
{