Let rapidjson as a module in cmake

bindings/c/CMakeLists.txt

@@ -73,6 +73,7 @@ if(NOT WIN32)
     test/mako/utils.h)
   add_subdirectory(test/unit/third_party)
   find_package(Threads REQUIRED)
+  include(Compilerapidjson)
   set(UNIT_TEST_SRCS
     test/unit/unit_tests.cpp
     test/unit/fdb_api.cpp

bindings/c/test/unit/third_party/CMakeLists.txt

@@ -16,19 +16,3 @@ ExternalProject_Add(
 
 ExternalProject_Get_Property(doctest source_dir)
 set(DOCTEST_INCLUDE_DIR ${source_dir}/doctest CACHE INTERNAL "Path to include folder for doctest")
-
-# Download rapidjson repo.
-ExternalProject_Add(
-    rapidjson
-    PREFIX ${CMAKE_BINARY_DIR}/rapidjson
-    GIT_REPOSITORY https://github.com/Tencent/rapidjson.git
-    GIT_TAG f54b0e47a08782a6131cc3d60f94d038fa6e0a51 # v1.1.0
-    TIMEOUT 10
-    CONFIGURE_COMMAND ""
-    BUILD_COMMAND ""
-    INSTALL_COMMAND ""
-    LOG_DOWNLOAD ON
-)
-
-ExternalProject_Get_Property(rapidjson source_dir)
-set(RAPIDJSON_INCLUDE_DIR ${source_dir}/include CACHE INTERNAL "Path to include folder for rapidjson")

cmake/Compilerapidjson.cmake

@@ -0,0 +1,38 @@
+# Findrapidjson
+
+find_package(rapidjson)
+
+include(ExternalProject)
+
+if (rapidjson_FOUND)
+  message(STATUS "Found rapidjson library!")
+  ExternalProject_Add(rapidjson
+    PREFIX ${CMAKE_BINARY_DIR}/rapidjson
+    DOWNLOAD_COMMAND ""
+    INSTALL_COMMAND ""
+  )
+else()
+  message(STATUS "rapidjson not found. Downloading ...")
+  ExternalProject_Add(
+    rapidjson
+    PREFIX ${CMAKE_BINARY_DIR}/rapidjson
+    GIT_REPOSITORY https://github.com/Tencent/rapidjson.git
+    GIT_TAG f54b0e47a08782a6131cc3d60f94d038fa6e0a51 # v1.1.0
+    TIMEOUT 10s
+    CONFIGURE_COMMAND ""
+    BUILD_COMMAND ""
+    INSTALL_COMMAND ""
+    LOG_DOWNLOAD ON
+  )
+
+  ExternalProject_Get_Property(rapidjson SOURCE_DIR)
+  set (RAPIDJSON_INCLUDE_DIR "${SOURCE_DIR}/include")
+
+  # set(rapidjson_FOUND TRUE)
+endif()
+
+message(STATUS "Found rapidjson includes: ${RAPIDJSON_INCLUDE_DIR}")
+
+mark_as_advanced(
+    RAPIDJSON_INCLUDE_DIR
+)

cmake/Findrapidjson.cmake

@@ -0,0 +1,8 @@
+# Findrapidjson
+
+find_path(RAPIDJSON_INCLUDE_DIR
+  NAMES rapidjson/rapidjson.h
+  PATH_SUFFIXES include)
+
+find_package_handle_standard_args(rapidjson
+  DEFAULT_MSG RAPIDJSON_INCLUDE_DIR)