Add formatting script to allow contributers to easily format code

README.md

@@ -421,3 +421,34 @@ int main(const int argc, const char * argv[]) {
 - For the current set of unit tests, the working directory must be at the git
   root directory or in `build` directory so that the TOML configuration files in
   `config` directory can be found.
+
+## Contributions
+
+Pull requests are welcome!
+
+To make the code formatting more objective, `clang-format` is used to format
+all the source code files.
+
+Please try to run
+
+```bash
+./run-clang-format.sh
+```
+
+which will pull the appropriate Docker image to run the formatting command over
+the entire repository directory.
+
+If your `docker` command requires `sudo`, then you will need to run it as
+
+```bash
+sudo sh ./run-clang-format.sh
+```
+
+Alternatively, you could also try to set up your own `clang-format` (currently
+this repository uses version 7), and run
+
+```bash
+clang-format -i path_to_h_cpp_file
+```
+
+over the changed files.

run-clang-format.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env sh
+if ! which docker >/dev/null; then
+    echo "You need 'docker' command to run clang-format for this repository"
+    exit 1
+fi
+
+docker run \
+    -v $(pwd):/workdir -w /workdir \
+    -u "$(id -u):$(id -g)" \
+    --rm -t \
+    guangie88/clang-cmake:7 \
+    find include/ src/ -type f \( -iname *.h -o -iname *.cpp \) -print0 | \
+        xargs -0 -I {} clang-format -i {}