Automate running clang-format if it is available.

CMakeLists.txt

@@ -1,13 +1,38 @@
 cmake_minimum_required (VERSION 3.7.0)
 project (DiscordRPCExample)
 
+# format
+file(GLOB_RECURSE ALL_SOURCE_FILES
+    examples/*.cpp examples/*.h examples/*.c
+    include/*.h
+    src/*.cpp src/*.h src/*.c
+)
+
+find_program(CLANG_FORMAT_CMD clang-format)
+
+if (CLANG_FORMAT_CMD)
+    add_custom_target(
+        clangformat
+        COMMAND clang-format
+        -i -style=file -fallback-style=none
+        ${ALL_SOURCE_FILES}
+        DEPENDS
+        ${ALL_SOURCE_FILES}
+    )
+else(CLANG_FORMAT_CMD)
+    add_custom_target(
+        clangformat
+        COMMENT "no clang format"
+    )
+endif(CLANG_FORMAT_CMD)
+
+# thirdparty stuff
 execute_process( 
     COMMAND mkdir ${CMAKE_SOURCE_DIR}/thirdparty
     ERROR_QUIET
 )
 
 find_file(RAPIDJSON NAMES rapidjson rapidjson-1.1.0 PATHS ${CMAKE_SOURCE_DIR}/thirdparty)
-
 if (NOT RAPIDJSON)
     message("no rapidjson, download")
     set(RJ_TAR_FILE ${CMAKE_SOURCE_DIR}/thirdparty/v1.1.0.tar.gz)
@@ -18,8 +43,9 @@ if (NOT RAPIDJSON)
     )
     file(REMOVE ${RJ_TAR_FILE})
 endif(NOT RAPIDJSON)
-
 add_library(rapidjson STATIC IMPORTED ${RAPIDJSON})
 
+# add subdirs
+
 add_subdirectory(src)
 add_subdirectory(examples/send-presence)