From 7cc1b04f796ff2ff95fc0a8403dd3343f0cede99 Mon Sep 17 00:00:00 2001
From: Ryan Burns <rtburns@protonmail.com>
Date: Tue, 12 Oct 2021 14:19:36 -0700
Subject: [PATCH] lib/attrsets: add filterAttrsRecursiveCond function

based on the mapAttrsRecursive{,Cond} functions
---
 lib/attrsets.nix | 31 ++++++++++++++++++++++++++++---
 lib/default.nix  |  1 +
 2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/lib/attrsets.nix b/lib/attrsets.nix
index c68806912321f..ed71618417917 100644
--- a/lib/attrsets.nix
+++ b/lib/attrsets.nix
@@ -697,8 +697,33 @@ rec {
 
     :::
   */
-  filterAttrsRecursive =
-    pred: set:
+  filterAttrsRecursive = filterAttrsRecursiveCond (_: true);
+
+  /**
+    Like `filterAttrsRecursive', but it takes an additional predicate that tells it whether to recurse into an attribute set.
+    If the predicate returns false, `filterAttrsRecursiveCond' does not recurse, but instead applies the filtering function.
+    If the predicate returns true, it does recurse, and does not apply the filtering function.
+
+    :::{#filter-attrs-recursive-cond-example .example}
+    # Filter over an leaf attributes defined by a condition
+
+    Filter derivations according to their `name` attribute.
+    Derivations are identified as attribute sets that contain `{ type = "derivation"; }`.
+    ```nix
+    filterAttrsRecursiveCond
+      (as: !(as ? "type" && as.type == "derivation"))
+      (x: x.name != "foo")
+      attrs
+    ```
+    :::
+
+    # Type:
+    ```
+    filterAttrsRecursiveCond :: (AttrSet -> Bool) -> (String -> a -> Bool) -> AttrSet -> AttrSet
+    ```
+  */
+  filterAttrsRecursiveCond =
+    cond: pred: set:
     listToAttrs (
       concatMap (
         name:
@@ -707,7 +732,7 @@ rec {
         in
         if pred name v then
           [
-            (nameValuePair name (if isAttrs v then filterAttrsRecursive pred v else v))
+            (nameValuePair name (if isAttrs v && cond v then filterAttrsRecursiveCond cond pred v else v))
           ]
         else
           [ ]
diff --git a/lib/default.nix b/lib/default.nix
index 875a1b9bb3efd..023f022e739ce 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -195,6 +195,7 @@ let
         catAttrs
         filterAttrs
         filterAttrsRecursive
+        filterAttrsRecursiveCond
         foldlAttrs
         foldAttrs
         collect