From 2adf0bdd4f4c6fbcb1f0dbe4b125b35d11da909d Mon Sep 17 00:00:00 2001
From: Mikael Voss <mvs@nyantec.com>
Date: Sat, 24 Aug 2024 13:10:45 +0200
Subject: [PATCH] lib: Add auxiliary functions to deal with flags

---
 lib/flags.nix | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 lib/flags.nix

diff --git a/lib/flags.nix b/lib/flags.nix
new file mode 100644
index 0000000..24884f9
--- /dev/null
+++ b/lib/flags.nix
@@ -0,0 +1,24 @@
+{ nixpkgs, ... }:
+
+let
+  inherit (builtins) any filter isList isString stringLength;
+  inherit (nixpkgs.lib.strings) addContextFrom;
+
+  split = strOrList:
+    if isList strOrList then strOrList
+    else builtins.split "[[:space:]]+" strOrList
+      |> filter (flag: isString flag && stringLength flag > 0)
+      |> map (flag: addContextFrom strOrList flag);
+
+  remerge = strOrList: list:
+    if isList strOrList then list
+    else toString list;
+in {
+  remove = rem: strOrList: split strOrList
+    |> filter (flag: !any (elem: flag == elem) rem)
+    |> remerge strOrList;
+
+  subst = sub: strOrList: split strOrList
+    |> map (flag: sub.${flag} or flag)
+    |> remerge strOrList;
+}