ActsTrk::detail::ExpectedLayerPatternHelper Node1 ActsTrk::detail::Expected LayerPatternHelper + add() + exists() + set() + get() Node2 std::string_view Node2->Node1 +kExpectedLayerPatternColumnName Node3 std::basic_string_view < char > Node3->Node2 Node4 std::string Node4->Node1 +kStripBarrel +kPixelEndcap +kStripEndcap +kPixelBarrel Node5 std::basic_string< char > Node5->Node4