A straight forward way to finding class definitions is via Doxygen. e.g. for AnalyticalFfromSuperF2D.
AnalyticalFfromSuperF2D interpolates using the node locations as sampling points while BlockReduction2D2D performs a reduction of the resolution (there is e.g. also a BlockReduction3D2D for extracting a hyperplane, BlockReduction functors generally use interpolation functors internally).