add CI for GitHub

.github/workflows/ci.yaml

@@ -0,0 +1,47 @@
+name: Viper Roots CI
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+  workflow_dispatch:
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        os: [ubuntu-latest]
+      fail-fast: false
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          submodules: 'true'
+
+      - name: Download and install Isabelle
+        run: |
+          wget --quiet https://isabelle.in.tum.de/website-Isabelle2024/dist/Isabelle2024_linux.tar.gz -O isabelle.tar.gz
+          mkdir -p isabelle
+          tar -xzf isabelle.tar.gz -C isabelle --strip-components=1
+          rm isabelle.tar.gz
+          isabelle/bin/isabelle version
+          echo isabelle/bin >> $GITHUB_PATH
+
+      - name: Setup Isabelle sessions
+        run: |
+          isabelle components -u foundational_boogie/BoogieLang
+          isabelle components -u vipersemcommon
+          isabelle components -u viper-total-heaps
+          isabelle components -u vipersemabstract
+          isabelle components -u viper-abstract-refines-total
+          isabelle components -u simple-frontend
+
+      - name: Check whether Isabelle theories go through successfully
+        # viper-total-heaps/paper-results has viper-total-heaps as a parent session
+        run: |
+          isabelle build -j4 -D viper-total-heaps/paper-results
+          isabelle build -j4 -D vipersemabstract
+          isabelle build -j4 -D viper-abstract-refines-total
+          isabelle build -j4 -D simple-frontend
+          isabelle build -j4 -D main-results