a nix flake to build the qlever rdf store

flake.nix

{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { self, nixpkgs, flake-utils }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = import nixpkgs {
          inherit system;
          config.allowUnfree = true;
        };

        # Pre-fetch CMake FetchContent dependencies to avoid network access during build
        googletest-src = pkgs.fetchFromGitHub {
          owner = "google";
          repo = "googletest";
          rev = "7917641ff965959afae189afb5f052524395525c";
          hash = "sha256-Pfkx/hgtqryPz3wI0jpZwlRRco0s2FLcvUX1EgTGFIw=";
        };

        nlohmann-json-src = pkgs.fetchzip {
          url = "https://github.com/nlohmann/json/releases/download/v3.11.3/json.tar.xz";
          hash = "sha256-zGnGdxBar2dQmWYhqywdC4xBgPxerqDv8GtdMQ+k7mQ=";
          stripRoot = false;
        };

        antlr-src = pkgs.fetchFromGitHub {
          owner = "antlr";
          repo = "antlr4";
          rev = "cc82115a4e7f53d71d9d905caa2c2dfa4da58899";
          hash = "sha256-XuE/nalt2HEYaII9NytUs0rCLGHOUFEclO+0h7pu4V0=";
        };

        range-v3-src = pkgs.fetchFromGitHub {
          owner = "joka921";
          repo = "range-v3";
          rev = "5ae161451ec1baaac352d7567298d3ac143bccae";
          hash = "sha256-r7wxSE8dX3hCxtHn8bwAOc3hM8Eodi9V28HaT53AUH8=";
        };

        spatialjoin-src = pkgs.fetchFromGitHub {
          owner = "ad-freiburg";
          repo = "spatialjoin";
          rev = "7f5c9007090cd1b902ad1873beb064820caebf39";
          hash = "sha256-s7CdOqykBPmnaH3VYxNc+JxwIr4bI5wGffVVTOfJY2Q=";
        };

        ctre-src = pkgs.fetchFromGitHub {
          owner = "hanickadot";
          repo = "compile-time-regular-expressions";
          rev = "e34c26ba149b9fd9c34aa0f678e39739641a0d1e";
          hash = "sha256-/44oZi6j8+a1D6ZGZpoy82GHjPtqzOvuS7d3SPbH7fs=";
        };

        abseil-src = pkgs.fetchFromGitHub {
          owner = "abseil";
          repo = "abseil-cpp";
          rev = "93ac3a4f9ee7792af399cebd873ee99ce15aed08";
          hash = "sha256-a18+Yj9fvDigza4b2g38L96hge5feMwU6fgPmL/KVQU=";
        };

        s2-src = pkgs.fetchFromGitHub {
          owner = "google";
          repo = "s2geometry";
          rev = "5b5eccd54a08ae03b4467e79ffbb076d0b5f221e";
          hash = "sha256-VjgGcGgQlKmjUq+JU0JpyhOZ9pqwPcBUFEPGV9XoHc0=";
        };

        fsst-src = pkgs.fetchFromGitHub {
          owner = "cwida";
          repo = "fsst";
          rev = "b228af6356196095eaf9f8f5654b0635f969661e";
          hash = "sha256-DxxRL+FQFA+x0RudIXtLhewseU50aScHKSCDX7DE9bY=";
        };

        re2-src = pkgs.fetchFromGitHub {
          owner = "google";
          repo = "re2";
          rev = "bc0faab533e2b27b85b8ad312abf061e33ed6b5d";
          hash = "sha256-cKXe8r5MUag/z+seem4Zg/gmqIQjaCY7DBxiKlrnXPs=";
        };

      in {
        packages.default = pkgs.stdenv.mkDerivation {
          pname = "qlever";
          version = "0.1.0";

          src = ./.;

          nativeBuildInputs = with pkgs; [
            cmake
            ninja
            pkg-config
            git
          ];

          buildInputs = with pkgs; [
            boost
            icu
            jemalloc
            zstd
            openssl
            curl
          ];

          cmakeFlags = [
            "-DCMAKE_BUILD_TYPE=Release"
            "-GNinja"
            # Point FetchContent to pre-downloaded sources to avoid network access
            # Note: hyphens in FetchContent_Declare names become underscores in variable names
            "-DFETCHCONTENT_SOURCE_DIR_GOOGLETEST=${googletest-src}"
            "-DFETCHCONTENT_SOURCE_DIR_NLOHMANN_JSON=${nlohmann-json-src}"
            "-DFETCHCONTENT_SOURCE_DIR_ANTLR=${antlr-src}"
            "-DFETCHCONTENT_SOURCE_DIR_RANGE_V3=${range-v3-src}"
            "-DFETCHCONTENT_SOURCE_DIR_SPATIALJOIN=${spatialjoin-src}"
            "-DFETCHCONTENT_SOURCE_DIR_CTRE=${ctre-src}"
            "-DFETCHCONTENT_SOURCE_DIR_ABSEIL=${abseil-src}"
            "-DFETCHCONTENT_SOURCE_DIR_S2=${s2-src}"
            "-DFETCHCONTENT_SOURCE_DIR_FSST=${fsst-src}"
            "-DFETCHCONTENT_SOURCE_DIR_RE2=${re2-src}"
          ];

          meta = with pkgs.lib; {
            description = "A SPARQL engine that can efficiently index and query very large knowledge graphs";
            homepage = "https://github.com/ad-freiburg/qlever";
            license = licenses.asl20;
            platforms = platforms.unix;
          };
        };

        devShells.default = pkgs.mkShell {
          buildInputs = with pkgs; [
            claude-code
            cmake
            ninja
            pkg-config
            boost
            icu
            jemalloc
            zstd
            openssl
            curl
            # Development tools
            gdb
            clang-tools
          ];

          shellHook = ''
            echo "QLever development environment"
            echo "Build with: cmake -B build -G Ninja && ninja -C build"
          '';
        };
      });
}