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Merge pull request #270133 from adisbladis/lib-attrbypath-allocs

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lib.(has|)attrByPath: Don't needlessly allocate lists in loop
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adisbladis 2023-11-27 21:33:42 +13:00 committed by GitHub
commit bbb4adee2f
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1 changed files with 25 additions and 11 deletions
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36
lib/attrsets.nix
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@ -34,12 +34,20 @@ rec {
default:
# The nested attribute set to select values from
set:
let attr = head attrPath;
let
lenAttrPath = length attrPath;
attrByPath' = n: s: (
if n == lenAttrPath then s
else (
let
attr = elemAt attrPath n;
in
if s ? ${attr} then attrByPath' (n + 1) s.${attr}
else default
)
);
in
if attrPath == [] then set
else if set ? ${attr}
then attrByPath (tail attrPath) default set.${attr}
else default;
attrByPath' 0 set;
/* Return if an attribute from nested attribute set exists.
@ -58,13 +66,19 @@ rec {
attrPath:
# The nested attribute set to check
e:
let attr = head attrPath;
let
lenAttrPath = length attrPath;
hasAttrByPath' = n: s: (
n == lenAttrPath || (
let
attr = elemAt attrPath n;
in
if s ? ${attr} then hasAttrByPath' (n + 1) s.${attr}
else false
)
);
in
if attrPath == [] then true
else if e ? ${attr}
then hasAttrByPath (tail attrPath) e.${attr}
else false;
hasAttrByPath' 0 e;
/* Create a new attribute set with `value` set at the nested attribute location specified in `attrPath`.