Currently classic_runtime_planner_for_sbe.h, and classic_runtime_planner_for_sbe.cpp have methods for various different classes. It's cleaner to separate them into different files like so:

• planner_interface.h
• planner_interface.cpp
• single_solution_planner.cpp
• multi_planner.cpp
• sub_planner.cpp
• cached_planner.cpp

Since there is only one consumer (get_executor.cpp) for classic_runtime_planner_for_sbe.h as it stands today and it would need all the subfiles, it would be ideal to have one header file and multiple specialized cpp files.