[SOLVED] Can we use CMake foreach in template source file?

Issue

For unit testing my functions, i have auto-generated the name, like it:

test_implode test_range

into a CMake variable.

I want to call all automatically in C. I also used config file (.in.c) in CMake

set(CONFIG configuration)
configure_file(${CONFIG}.in.c ${CONFIG}.c)
set(CONFIG_SRC ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG}.c)

But the name of the function are just in a List in CMake, the C syntax is not valid. I could generate a variable in CMake with appropriate syntax, but generating output in config file would let the CMake source file clean and could be possibly very powerful.

Concretly, what I would like to do is that (imaginary syntax):

#include "tests.h"

void all_tests() {

    void(*tests)()[] = {
    @FOREACH(FUNC FUNCTIONS)@
        test_@FUNC@,
    @ENDFOREACH()@
        NULL
    };

    void(*test_function)() = tests[0];

    while(test_function) {
        test_function();
        test_function++;
    }
}

Similarly to blade or php. Can I use CMake as a scripting language (or a foreach) or is it mandatory to put this in the CMake source file and store it into a variable ?

What I currently do, which is acceptable, works. But I'm learning and I would like to know if it's still possible or not

foreach(PHP_FUNCTION ${PHP_FUNCTIONS})
  list(APPEND GENERATED_C_CODE_RUN_TEST "\n\ttest_${PHP_FUNCTION}()")
endforeach()

set(GENERATED_C_CODE_RUN_TEST "${GENERATED_C_CODE_RUN_TEST};")
set(CONFIG configuration)
configure_file(${CONFIG}.in.c ${CONFIG}.c)
set(CONFIG_SRC ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG}.c)
add_executable(...);

#include "tests.h"

void all_tests() {

    @GENERATED_C_CODE_RUN_TEST@
}

Solution

One solution is to append the test_ prefix to each test name in a list, then use list(JOIN ...) to construct a string representing a comma-separated list (which is valid C syntax).

list(APPEND PHP_FUNCTIONS
    func1
    func2
    func3
)

# Append the 'test_' prefix to each test function name.
foreach(PHP_FUNCTION ${PHP_FUNCTIONS})
    list(APPEND FUNCTION_NAMES_LIST "test_${PHP_FUNCTION}")
endforeach()
message(STATUS "FUNCTION_NAMES_LIST: ${FUNCTION_NAMES_LIST}")

# Construct a comma-separated string from the list.
list(JOIN FUNCTION_NAMES_LIST "," FUNCTION_NAMES_STRING)
message(STATUS "FUNCTION_NAMES_STRING: ${FUNCTION_NAMES_STRING}")

This prints the following:

FUNCTION_NAMES_LIST: test_func1;test_func2;test_func3
FUNCTION_NAMES_STRING: test_func1,test_func2,test_func3

Then, you can modify your configuration.in.c file so only one variable needs to be substituted:

void all_tests() {

    void(*tests)()[] = {
        @FUNCTION_NAMES_STRING@,
        NULL
    };

    void(*test_function)() = tests[0];

    while(test_function) {
        test_function();
        test_function++;
    }
}

You can play around with the "glue" or separator string used to join the CMake list together. In my example, I used "," but you can use ", " or ",\n\t" to make the resultant C code more visually pleasing. CMake list() (and string()) have lots of manipulation options to play around with, so I encourage you to check them out.

Answered By - Kevin