Add format target for running clang-format

cmake/Format.cmake

@@ -0,0 +1,27 @@
+# Check executable exists
+if(NOT EXISTS ${CLANG_FORMAT_EXECUTABLE})
+    find_program(CLANG_FORMAT_EXEC_TEMP ${CLANG_FORMAT_EXECUTABLE})
+    if(CLANG_FORMAT_EXEC_TEMP)
+        set(CLANG_FORMAT_EXECUTABLE ${CLANG_FORMAT_EXEC_TEMP})
+        unset(CLANG_FORMAT_EXEC_TEMP)
+    else()
+        message(FATAL_ERROR "Unable to find clang-format executable: \"${CLANG_FORMAT_EXECUTABLE}\"")
+    endif()
+endif()
+
+# Check executable version
+execute_process(COMMAND ${CLANG_FORMAT_EXECUTABLE} --version OUTPUT_VARIABLE CLANG_FORMAT_VERSION)
+string(REGEX MATCH "clang-format version ([0-9]+)" CLANG_FORMAT_VERSION ${CLANG_FORMAT_VERSION})
+unset(CLANG_FORMAT_VERSION)
+if(NOT CMAKE_MATCH_1 EQUAL 14)
+    message(FATAL_ERROR "clang-format version ${CMAKE_MATCH_1} not supported. Must use version 14")
+endif()
+
+# Run
+set(SOURCES "")
+foreach(FOLDER IN ITEMS examples include src test)
+    file(GLOB_RECURSE folder_files "${FOLDER}/*.h" "${FOLDER}/*.hpp" "${FOLDER}/*.c" "${FOLDER}/*.cpp")
+    list(APPEND SOURCES ${folder_files})
+endforeach()
+
+execute_process(COMMAND ${CLANG_FORMAT_EXECUTABLE} -i ${SOURCES})