add clang-format to github actions

.github/workflows/clang-format.yml

@@ -0,0 +1,13 @@
+name: clang-format
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: install clang-format
+      run: sudo apt-get install clang-format
+    - uses: actions/checkout@v2
+    - run: ./clang-format.sh

clang-format.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+set -xe
+SRCDIRS=(include src tests)
+clang-format --version
+find "${SRCDIRS[@]}"  -type f -name '*.h' -o -name '*.cpp' -o -name '*.hpp' | xargs -I{} -P1 clang-format -i -style=file {}
+git diff
+if [[ -z "$(git status --porcelain "${SRCDIRS[@]}" ]] ; then
+	git status
+	git diff
+	exit 1
+fi