CMake: allow use of installed JRL-cmakemodules

CMakeLists.txt

@@ -24,9 +24,40 @@ set(PROJECT_USE_KEYWORD_LINK_LIBRARIES TRUE)
 set(CXX_DISABLE_WERROR true)
 set(DOXYGEN_USE_TEMPLATE_CSS TRUE)
 
-include(cmake/base.cmake)
-include(cmake/idl.cmake)
-include(cmake/apple.cmake)
+# Check if the submodule cmake have been initialized
+set(JRL_CMAKE_MODULES "${CMAKE_CURRENT_LIST_DIR}/cmake")
+if(EXISTS "${JRL_CMAKE_MODULES}/base.cmake")
+  message(STATUS "JRL cmakemodules found in 'cmake/' git submodule")
+else()
+  find_package(jrl-cmakemodules QUIET CONFIG)
+  if(jrl-cmakemodules_FOUND)
+    get_property(
+      JRL_CMAKE_MODULES
+      TARGET jrl-cmakemodules::jrl-cmakemodules
+      PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
+    message(STATUS "JRL cmakemodules found on system at ${JRL_CMAKE_MODULES}")
+  elseif(${CMAKE_VERSION} VERSION_LESS "3.14.0")
+    message(
+      FATAL_ERROR
+        "\nCan't find jrl-cmakemodules. Please either:\n"
+        "  - use git submodule: 'git submodule update --init'\n"
+        "  - or install https://github.com/jrl-umi3218/jrl-cmakemodules\n"
+        "  - or upgrade your CMake version to >= 3.14 to allow automatic fetching\n"
+    )
+  else()
+    message(STATUS "JRL cmakemodules not found. Let's fetch it.")
+    include(FetchContent)
+    FetchContent_Declare(
+      "jrl-cmakemodules"
+      GIT_REPOSITORY "https://github.com/jrl-umi3218/jrl-cmakemodules.git")
+    FetchContent_MakeAvailable("jrl-cmakemodules")
+    FetchContent_GetProperties("jrl-cmakemodules" SOURCE_DIR JRL_CMAKE_MODULES)
+  endif()
+endif()
+
+include("${JRL_CMAKE_MODULES}/base.cmake")
+include("${JRL_CMAKE_MODULES}/idl.cmake")
+include("${JRL_CMAKE_MODULES}/apple.cmake")
 
 set(CLIENT_ONLY
     FALSE