add default.nix

build this project from NixOS with `nix-build`

default.nix

@@ -0,0 +1,44 @@
+{ pkgs ? import <nixpkgs> {} }:
+with pkgs;
+stdenv.mkDerivation {
+  pname = "rofi";
+  version = "1.7.5-unstable";
+  src = ./.;
+
+  depsBuildBuild = [
+    buildPackages.stdenv.cc
+    pkg-config
+    glib
+  ];
+  nativeBuildInputs = [
+    meson
+    ninja
+    pkg-config
+    flex
+    bison
+    pandoc
+    wayland-protocols
+    wayland-scanner
+  ];
+  buildInputs = [
+    libxkbcommon
+    pango
+    cairo
+    git
+    librsvg
+    check
+    libstartup_notification
+    xorg.libxcb
+    xcb-imdkit
+    xcb-util-cursor
+    xorg.xcbutilkeysyms
+    xorg.xcbutil
+    xorg.xcbutilwm
+    xcbutilxrm
+    wayland
+    wayland-protocols
+    which
+  ];
+
+  mesonFlags = [ "-Dimdkit=true" ];
+}