file(GLOB SUBDIRECTORIES RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} "*")
foreach(SUBDIRECTORY ${SUBDIRECTORIES})
    if(IS_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/${SUBDIRECTORY}" AND EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/${SUBDIRECTORY}/CMakeLists.txt")
        add_subdirectory(${SUBDIRECTORY})
    endif()
endforeach()