fix finding rapidjson & rm

CMakeLists.txt

@@ -49,10 +49,26 @@ if ( HYTEG_BUILD_WITH_TRILINOS )
 endif()
 
 if ( HYTEG_BUILD_WITH_GINKGO )
-    find_package( Ginkgo REQUIRED )
-    find_package( RapidJSON REQUIRED)
+    find_package(Ginkgo REQUIRED)
+    find_package(RapidJSON QUIET)
+    if(NOT RapidJSON_FOUND)
+      include(FetchContent)
+      FetchContent_Declare(
+        rapidjson
+        GIT_REPOSITORY https://github.com/Tencent/rapidjson.git
+        GIT_TAG 48fbd8cd202ca54031fe799db2ad44ffa8e77c13
+      )
+      FetchContent_GetProperties(rapidjson)
+      if(NOT rapidjson_POPULATED)
+        FetchContent_Populate(rapidjson)
+      endif()
+      set(RapidJSON_INCLUDE_DIR "${rapidjson_SOURCE_DIR}/include")
+      add_library(rapidjson INTERFACE)
+      set_target_properties(rapidjson PROPERTIES INTERFACE_INCLUDE_DIRECTORIES "${RapidJSON_INCLUDE_DIR}")
+    endif()
     message(STATUS "Found Ginkgo! Ginkgo_DIR = ${Ginkgo_DIR}")
-    list ( APPEND SERVICE_LIBS Ginkgo::ginkgo rapidjson)
+    include_directories(${Ginkgo_RM_DIR})
+    list(APPEND SERVICE_LIBS Ginkgo::ginkgo rapidjson)
 endif()
 
 find_package( waLBerla )