Makefile find in array

Question

If I have something like this:

PROJECTS += path/to/first
PROJECTS += path/to/second
PROJECTS += path/to/third

and

LIBS += lib_output/first.lib
LIBS += lib_output/second.lib
LIBS += lib_output/third.lib

How could I associate the project from PROJECTS += path/to/first with LIBS += lib_output/first.lib? Is there something like a hashmap available in a makefile? Or possibility to search in an array?

Answer 1

You can simulate lookup tables using computed variable names and the fact that make variable names can include some special characters like dot and forward slash:

PROJECTS += path/to/first
PROJECTS += path/to/second
PROJECTS += path/to/third

LIBS += lib_output/first.lib
LIBS += lib_output/second.lib
LIBS += lib_output/third.lib

lookup.path/to/first  := lib_output/first.lib
lookup.path/to/second := lib_output/second.lib
lookup.path/to/third  := lib_output/third.lib

path := path/to/first
$(info ${path} -> ${lookup.${path}})
path := path/to/second
$(info ${path} -> ${lookup.${path}})
path := path/to/third
$(info ${path} -> ${lookup.${path}})

Outputs:

$ make
path/to/first -> lib_output/first.lib
path/to/second -> lib_output/second.lib
path/to/third -> lib_output/third.lib

Answer 2

I'm not sure if I completely understand your question, but I think the word function might be what you need (it may be a GNU make extension):

$(word 2, $(PROJECTS)) returns path/to/second,
$(word 2, $(LIBS)) returns lib_output/second.lib.