Unverified Commit bbb4adee authored by adisbladis's avatar adisbladis Committed by GitHub
Browse files

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

lib.(has|)attrByPath: Don't needlessly allocate lists in loop
parents 8cfef698 544a1d37

lib/attrsets.nix

+25 −11
Original line number Diff line number Diff line
@@ -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 attrPath == [] then set

      else if set ? ${attr}

      then attrByPath (tail attrPath) default set.${attr}

      else default;

          if s ? ${attr} then attrByPath' (n + 1) s.${attr}

          else default

        )

      );

    in

      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 attrPath == [] then true

      else if e ? ${attr}

      then hasAttrByPath (tail attrPath) e.${attr}

      else false;



          if s ? ${attr} then hasAttrByPath' (n + 1) s.${attr}

          else false

        )

      );

    in

      hasAttrByPath' 0 e;



  /* Create a new attribute set with `value` set at the nested attribute location specified in `attrPath`.