code: Add clang-format target and CI workflow (#82)

* code: Add clang format target, rules and CI workflow

* code: Run clang format on sources

CMakeLists.txt

@@ -27,6 +27,57 @@ function(create_target_directory_groups target_name)
     endforeach()
 endfunction()
 
+
+# Setup a custom clang-format target (if clang-format can be found) that will run
+# against all the src files. This should be used before making a pull request.
+# =======================================================================
+
+set(CLANG_FORMAT_POSTFIX "-15")
+find_program(CLANG_FORMAT
+    NAMES clang-format${CLANG_FORMAT_POSTFIX}
+          clang-format
+    PATHS ${PROJECT_BINARY_DIR}/externals)
+# if find_program doesn't find it, try to download from externals
+if (NOT CLANG_FORMAT)
+    if (WIN32)
+        message(STATUS "Clang format not found! Downloading...")
+        set(CLANG_FORMAT "${PROJECT_BINARY_DIR}/externals/clang-format${CLANG_FORMAT_POSTFIX}.exe")
+        file(DOWNLOAD
+            https://github.com/citra-emu/ext-windows-bin/raw/master/clang-format${CLANG_FORMAT_POSTFIX}.exe
+            "${CLANG_FORMAT}" SHOW_PROGRESS
+            STATUS DOWNLOAD_SUCCESS)
+        if (NOT DOWNLOAD_SUCCESS EQUAL 0)
+            message(WARNING "Could not download clang format! Disabling the clang format target")
+            file(REMOVE ${CLANG_FORMAT})
+            unset(CLANG_FORMAT)
+        endif()
+    else()
+        message(WARNING "Clang format not found! Disabling the clang format target")
+    endif()
+endif()
+
+if (CLANG_FORMAT)
+    set(SRCS ${PROJECT_SOURCE_DIR}/src)
+    set(CCOMMENT "Running clang format against all the .h and .cpp files in src/")
+    if (WIN32)
+        if(MINGW)
+            add_custom_target(clang-format
+                COMMAND find `cygpath -u ${SRCS}` -iname *.h -o -iname *.cpp -o -iname *.mm | xargs `cygpath -u ${CLANG_FORMAT}` -i
+                COMMENT ${CCOMMENT})
+        else()
+            add_custom_target(clang-format
+                COMMAND powershell.exe -Command "Get-ChildItem '${SRCS}/*' -Include *.cpp,*.h,*.mm -Recurse | Foreach {&'${CLANG_FORMAT}' -i $_.fullname}"
+                COMMENT ${CCOMMENT})
+        endif()
+    else()
+        add_custom_target(clang-format
+            COMMAND find ${SRCS} -iname *.h -o -iname *.cpp -o -iname *.mm | xargs ${CLANG_FORMAT} -i
+            COMMENT ${CCOMMENT})
+    endif()
+    unset(SRCS)
+    unset(CCOMMENT)
+endif()
+
 add_subdirectory(third-party)
 include_directories(src)