cpp-utilities/cmake/modules/ListToString.cmake

cmake_minimum_required(VERSION 3.3.0 FATAL_ERROR)

# prevent multiple inclusion
if (DEFINED LIST_TO_STRING_LOADED)
    return()
endif ()
set(LIST_TO_STRING_LOADED ON)

function (list_to_string separator prefix suffix input_list output_string_var)
    set(res "")
    # get list length
    list(LENGTH input_list list_length)
    # if the list has 0 or 1 element, there is no need to loop over
    if (list_length LESS 2)
        set(res "${prefix}${input_list}${suffix}")
    else ()
        math(EXPR last_element_index "${list_length} - 1")
        foreach (index RANGE ${last_element_index})
            # get current item_value
            list(GET input_list ${index} item_value)
            if (NOT item_value STREQUAL "")
                # .. and append non-empty value to output string
                set(res "${res}${prefix}${item_value}${suffix}")
                # append separator if current element is NOT the last one.
                if (NOT index EQUAL last_element_index)
                    set(res "${res}${separator}")
                endif ()
            endif ()
        endforeach ()
    endif ()
    set(${output_string_var}
        "${res}"
        PARENT_SCOPE)
endfunction ()