cmake - How to prepend all filenames on the list with common path?

Question

How can I prepend all filenames on the list with a common path prefix automatically? For instance having a list of files in CMakeLists.txt:

SET(SRC_FILES foo1.cpp foo2.cpp)

I'd like to get a list that is equivalent to this:

${CMAKE_CURRENT_SOURCE_DIR}/foo1.cpp ${CMAKE_CURRENT_SOURCE_DIR}/foo2.cpp

I need this to use filenames in a PARENT_SCOPE context, e.g.

SET(FILES_TO_TRANSLATE ${FILES_TO_TRANSLATE} ${SRC_FILES} PARENT_SCOPE)

so, that a CMakeFiles.txt in another directory can still find these files.

In essence, I'd expect something like this (pseudo-code):

SET(FILES_TO_TRANSLATE PREPEND_ALL_NAMES(${CMAKE_CURRENT_SOURCE_DIR} ${SRC_FILES}) PARENT_SCOPE)

Is this is easily doable, or do I have to user "foreach" loop to create new list of files?

Answer 1

CMake 3.12 added list transformers - one of these transformers is PREPEND. Thus, the following can be used inline to prepend all entries in a list:

list(TRANSFORM FILES_TO_TRANSLATE PREPEND ${CMAKE_CURRENT_SOURCE_DIR})

...where FILES_TO_TRANSLATE is the variable name of the list.

More information can be found in the CMake documentation.