Add Nix Flake support and CI workflow

.github/workflows/flake.yml

@@ -0,0 +1,32 @@
+name: Nix Flake CI
+
+on:
+  pull_request:
+  push:
+    branches: [master]
+
+jobs:
+  check-and-build:
+    name: Check and Build Nix Flake
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        system: [x86_64-linux, aarch64-linux]  # Check for multiple systems
+      fail-fast: false
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Install Nix
+        uses: cachix/install-nix-action@v30
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+
+      - name: Check Flake
+        run: nix flake check --all-systems --system ${{ matrix.system }}
+
+      - name: Build Flake
+        run: nix build .# --system ${{ matrix.system }}
+

.gitignore

@@ -56,3 +56,6 @@ install_manifest.txt
 *.dylib
 *.so
 *.dll
+
+# Nix build results
+result*

flake.nix

@@ -0,0 +1,34 @@
+{
+  description = "A Package for Automatic Differentiation of Algorithms Written in C/C++ ";
+
+  inputs = {
+    flake-utils.url = "github:numtide/flake-utils";
+    nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
+  };
+
+  outputs =
+    { flake-utils, nixpkgs, ... }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        pkgs = import nixpkgs { inherit system; };
+      in
+      {
+        packages = rec {
+          adolc-cmake = pkgs.stdenv.mkDerivation {
+            name = "adolc";
+            src = ./.;
+            nativeBuildInputs = [ pkgs.cmake ];
+          };
+
+          adolc-autotools = adolc-cmake.overrideAttrs (
+            _: _: {
+              nativeBuildInputs = [ pkgs.autoreconfHook ];
+            }
+          );
+
+          default = adolc-cmake;
+        };
+      }
+    );
+}