Add generator for single crate flake

flake.nix

@@ -11,14 +11,23 @@
       url = "github:oxalica/rust-overlay";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+    # Advisory db from rust-sec
+    advisory-db = {
+      url = "github:RustSec/advisory-db";
+      flake = false;
+    };
   };
 
   description = "Rust Toolchain and Utility Flake";
 
   outputs = { self, nixpkgs, utils, ... }@inputs:
-    (utils.lib.eachDefaultSystem (system: {
+    with builtins;
+    let
+      sources = fromJSON (readFile ./sources/sources.json);
+      rustPackageNames = attrValues sources;
+      # Build the rust packages we'll be using
+    in (utils.lib.eachDefaultSystem (system: {
       packages = let
-        sources = builtins.fromJSON (builtins.readFile ./sources/sources.json);
         pkgs = import nixpkgs {
           inherit system;
           overlays = [ (import inputs.rust-overlay) ];
@@ -30,10 +39,127 @@
           rustc = rust;
           cargo = rust;
         };
-      in builtins.mapAttrs (name: source:
+      in mapAttrs (name: source:
         naersk-lib.buildPackage {
           pname = source.pname;
           src = pkgs.fetchCrate source;
         }) sources;
-    }));
+    })) //
+    # Now provide our builder functions
+    {
+      # Build a rust flake with a single crate
+      single = { src, crateName, sharedDeps ? (system: [ ])
+        , sharedNativeDeps ? (system: [ ]) }:
+        utils.lib.eachDefaultsystem (system:
+          let
+            pkgs = import nixpkgs {
+              inherit system;
+              overlays = [ (import inputs.rust-overlay) ];
+            };
+            rust = pkgs.rust-bin.stable.latest.default.override {
+              extensions = [ "llvm-tools-preview" ];
+            };
+            naersk-lib = inputs.naersk.lib."${system}".override {
+              rustc = rust;
+              cargo = rust;
+            };
+            devBase = with pkgs;
+              [
+                # Build tools
+                openssl
+                pkg-config
+                rust-analyzer
+                cmake
+                gnuplot
+                # git tooling
+                gitFull
+                pre-commit
+                git-lfs
+                git-cliff
+                # Formatters
+                nixfmt
+                python311Packages.mdformat
+              ] ++ map (x: self.packages.${system}.${x}) rustPackageNames;
+          in rec {
+            # Main binary
+            packages.${crateName} = naersk-lib.buildPackage {
+              pname = "${crateName}";
+              buildInputs = sharedDeps system;
+              nativeBuildInputs = sharedNativeDeps system;
+              root = src;
+            };
+            # binary + tests
+            packages.tests.${crateName} = naersk-lib.buildPackage {
+              pname = "${crateName}";
+              buildInputs = sharedDeps system;
+              nativeBuildInputs = sharedNativeDeps system;
+              root = src;
+              doCheck = true;
+            };
+            # Docs
+            packages.docs.${crateName} = naersk-lib.buildPackage {
+              pname = "${crateName}";
+              buildInputs = sharedDeps system;
+              nativeBuildInputs = sharedNativeDeps system;
+              root = src;
+              dontBuild = true;
+              doDoc = true;
+              doDocFail = true;
+            };
+
+            # Set the default package to the main binary
+            defaultPackage = packages.${crateName};
+
+            # CI tasks
+            packages.lints = {
+              # lint formatting
+              format.${crateName} = with import nixpkgs { inherit system; };
+                stdenv.mkDerivation {
+                  name = "format lint";
+                  src = src;
+                  nativeBuildInputs = with pkgs;
+                    [ rust-bin.stable.latest.default ]
+                    ++ (sharedNativeDeps system);
+                  buildInputs = sharedDeps system;
+                  buildPhase = "cargo fmt -- --check";
+                  installPhase = "mkdir -p $out; echo 'done'";
+                };
+              # audit against stored advisory db
+              audit.${crateName} = with import nixpkgs { inherit system; };
+                stdenv.mkDerivation {
+                  name = "audit lint";
+                  src = src;
+                  nativeBuildInputs = with pkgs;
+                    [ rust-bin.stable.latest.default cargo-audit ]
+                    ++ (sharedNativeDeps system);
+                  buildInputs = sharedDeps system;
+                  buildPhase = ''
+                    export HOME=$TMP
+                    mkdir -p ~/.cargo
+                    cp -r ${advisory-db} ~/.cargo/advisory-db
+                    cargo audit -n
+                  '';
+                  installPhase = "mkdir -p $out; echo 'done'";
+                };
+              # Clippy
+              clippy.${crateName} = naersk-lib.buildPackage {
+                pname = "${crateName}";
+                root = src;
+                buildInputs = sharedDeps system;
+                nativeBuildInputs = sharedNativeDeps system;
+                cargoTestCommands = (old: [ "cargo $cargo_options clippy" ]);
+                doCheck = true;
+                dontBuild = true;
+              };
+            };
+
+            # Development environments
+            devShell = pkgs.mkShell {
+              inputsFrom = builtins.attrValues packages.${system};
+              buildInputs = [ rust ] ++ devBase ++ (sharedDeps system)
+                ++ (sharedNativeDeps system);
+            };
+
+          });
+    };
 }