Add amalgamte workflow

.github/publish_amal.yml

@@ -0,0 +1,42 @@
+# release amalgamated code using cpp-amalgamate
+name: Publish Amalgamated Code
+on:
+  push:
+    branches:
+      - main
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - name: cargo install cpp-amalgamate
+        run: cargo install cpp-amalgamate
+      - name: cpp-amalgamate
+        run: |
+          rm -f amalgamated.hpp
+          cpp-amalgamate ./src/** >> amalgamated.hpp
+      # create new release
+      - name: Create Release
+        id: create_release
+        uses: actions/create-release@v1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          tag_name: ${{ github.ref }}
+          release_name: Release ${{ github.ref }}
+          draft: false
+          prerelease: false
+      # upload amalgamated code
+      - name: Upload Release Asset
+        id: upload-release-asset
+        uses: actions/upload-release-asset@v1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          upload_url: ${{ steps.create_release.outputs.upload_url }}
+          asset_path: ./amalgamated.hpp
+          asset_name: amalgamated.hpp
+          asset_content_type: text/plain