Unverified Commit acb6191c authored by Robert Hensing's avatar Robert Hensing Committed by GitHub
Browse files

lib: Add splicing utilities (#426889)

parents 87102544 f8566d22

lib/customisation.nix

+135 −0
Original line number Diff line number Diff line
@@ -864,4 +864,139 @@ rec { 
        transformDrv

        ;

    };



  /**

    Removes a prefix from the attribute names of a cross index.



    A cross index (short for "Cross Platform Pair Index") is a 6-field structure

    organizing values by cross-compilation platform relationships.



    # Inputs



    `prefix`

    : The prefix to remove from cross index attribute names



    `crossIndex`

    : A cross index with prefixed names



    # Type



    ```

    renameCrossIndexFrom :: String -> AttrSet -> AttrSet

    ```



    # Examples



    :::{.example}

    ## `lib.customisation.renameCrossIndexFrom` usage example



    ```nix

    renameCrossIndexFrom "pkgs" { pkgsBuildBuild = ...; pkgsBuildHost = ...; ... }

    => { buildBuild = ...; buildHost = ...; ... }

    ```

    :::

  */

  renameCrossIndexFrom = prefix: x: {

    buildBuild = x."${prefix}BuildBuild";

    buildHost = x."${prefix}BuildHost";

    buildTarget = x."${prefix}BuildTarget";

    hostHost = x."${prefix}HostHost";

    hostTarget = x."${prefix}HostTarget";

    targetTarget = x."${prefix}TargetTarget";

  };



  /**

    Adds a prefix to the attribute names of a cross index.



    A cross index (short for "Cross Platform Pair Index") is a 6-field structure

    organizing values by cross-compilation platform relationships.



    # Inputs



    `prefix`

    : The prefix to add to cross index attribute names



    `crossIndex`

    : A cross index to be prefixed



    # Type



    ```

    renameCrossIndexTo :: String -> AttrSet -> AttrSet

    ```



    # Examples



    :::{.example}

    ## `lib.customisation.renameCrossIndexTo` usage example



    ```nix

    renameCrossIndexTo "self" { buildBuild = ...; buildHost = ...; ... }

    => { selfBuildBuild = ...; selfBuildHost = ...; ... }

    ```

    :::

  */

  renameCrossIndexTo = prefix: x: {

    "${prefix}BuildBuild" = x.buildBuild;

    "${prefix}BuildHost" = x.buildHost;

    "${prefix}BuildTarget" = x.buildTarget;

    "${prefix}HostHost" = x.hostHost;

    "${prefix}HostTarget" = x.hostTarget;

    "${prefix}TargetTarget" = x.targetTarget;

  };



  /**

    Takes a function and applies it pointwise to each field of a cross index.



    A cross index (short for "Cross Platform Pair Index") is a 6-field structure

    organizing values by cross-compilation platform relationships.



    # Inputs



    `f`

    : Function to apply to each cross index value



    `crossIndex`

    : A cross index to transform



    # Type



    ```

    mapCrossIndex :: (a -> b) -> AttrSet -> AttrSet

    ```



    # Examples



    :::{.example}

    ## `lib.customisation.mapCrossIndex` usage example



    ```nix

    mapCrossIndex (x: x * 10) { buildBuild = 1; buildHost = 2; ... }

    => { buildBuild = 10; buildHost = 20; ... }

    ```



    ```nix

    # Extract a package from package sets

    mapCrossIndex (pkgs: pkgs.hello) crossIndexedPackageSets

    ```

    :::

  */

  mapCrossIndex =

    f:

    {

      buildBuild,

      buildHost,

      buildTarget,

      hostHost,

      hostTarget,

      targetTarget,

    }:

    {

      buildBuild = f buildBuild;

      buildHost = f buildHost;

      buildTarget = f buildTarget;

      hostHost = f hostHost;

      hostTarget = f hostTarget;

      targetTarget = f targetTarget;

    };

}

lib/default.nix

+3 −0
Original line number Diff line number Diff line
@@ -397,6 +397,9 @@ let 
        makeScopeWithSplicing

        makeScopeWithSplicing'

        extendMkDerivation

        renameCrossIndexFrom

        renameCrossIndexTo

        mapCrossIndex

        ;

      inherit (self.derivations) lazyDerivation optionalDrvAttr warnOnInstantiate;

      inherit (self.generators) mkLuaInline;

lib/tests/misc.nix

+78 −0
Original line number Diff line number Diff line
@@ -4741,4 +4741,82 @@ runTests { 
    expected = "/non-existent/this/does/not/exist/for/real/please-dont-mess-with-your-local-fs/default.nix";

  };



  # Tests for cross index utilities



  testRenameCrossIndexFrom = {

    expr = lib.renameCrossIndexFrom "pkgs" {

      pkgsBuildBuild = "dummy-build-build";

      pkgsBuildHost = "dummy-build-host";

      pkgsBuildTarget = "dummy-build-target";

      pkgsHostHost = "dummy-host-host";

      pkgsHostTarget = "dummy-host-target";

      pkgsTargetTarget = "dummy-target-target";

    };

    expected = {

      buildBuild = "dummy-build-build";

      buildHost = "dummy-build-host";

      buildTarget = "dummy-build-target";

      hostHost = "dummy-host-host";

      hostTarget = "dummy-host-target";

      targetTarget = "dummy-target-target";

    };

  };



  testRenameCrossIndexTo = {

    expr = lib.renameCrossIndexTo "self" {

      buildBuild = "dummy-build-build";

      buildHost = "dummy-build-host";

      buildTarget = "dummy-build-target";

      hostHost = "dummy-host-host";

      hostTarget = "dummy-host-target";

      targetTarget = "dummy-target-target";

    };

    expected = {

      selfBuildBuild = "dummy-build-build";

      selfBuildHost = "dummy-build-host";

      selfBuildTarget = "dummy-build-target";

      selfHostHost = "dummy-host-host";

      selfHostTarget = "dummy-host-target";

      selfTargetTarget = "dummy-target-target";

    };

  };



  testMapCrossIndex = {

    expr = lib.mapCrossIndex (x: x * 10) {

      buildBuild = 1;

      buildHost = 2;

      buildTarget = 3;

      hostHost = 4;

      hostTarget = 5;

      targetTarget = 6;

    };

    expected = {

      buildBuild = 10;

      buildHost = 20;

      buildTarget = 30;

      hostHost = 40;

      hostTarget = 50;

      targetTarget = 60;

    };

  };



  testMapCrossIndexString = {

    expr = lib.mapCrossIndex (x: "prefix-${x}") {

      buildBuild = "bb";

      buildHost = "bh";

      buildTarget = "bt";

      hostHost = "hh";

      hostTarget = "ht";

      targetTarget = "tt";

    };

    expected = {

      buildBuild = "prefix-bb";

      buildHost = "prefix-bh";

      buildTarget = "prefix-bt";

      hostHost = "prefix-hh";

      hostTarget = "prefix-ht";

      targetTarget = "prefix-tt";

    };

  };



}

pkgs/top-level/splice.nix

+16 −49
Original line number Diff line number Diff line
@@ -17,48 +17,30 @@ 
lib: pkgs: actuallySplice:



let

  inherit (lib.customisation) mapCrossIndex renameCrossIndexFrom;



  spliceReal =

    {

      pkgsBuildBuild,

      pkgsBuildHost,

      pkgsBuildTarget,

      pkgsHostHost,

      pkgsHostTarget,

      pkgsTargetTarget,

    }:

    inputs:

    let

      mash =

        # Other pkgs sets

        pkgsBuildBuild

        // pkgsBuildTarget

        // pkgsHostHost

        // pkgsTargetTarget

        inputs.buildBuild

        // inputs.buildTarget

        // inputs.hostHost

        // inputs.targetTarget

        # The same pkgs sets one probably intends

        // pkgsBuildHost

        // pkgsHostTarget;

        // inputs.buildHost

        // inputs.hostTarget;

      merge = name: {

        inherit name;

        value =

          let

            defaultValue = mash.${name};

            # `or {}` is for the non-derivation attsert splicing case, where `{}` is the identity.

            valueBuildBuild = pkgsBuildBuild.${name} or { };

            valueBuildHost = pkgsBuildHost.${name} or { };

            valueBuildTarget = pkgsBuildTarget.${name} or { };

            valueHostHost = pkgsHostHost.${name} or { };

            valueHostTarget = pkgsHostTarget.${name} or { };

            valueTargetTarget = pkgsTargetTarget.${name} or { };

            value' = mapCrossIndex (x: x.${name} or { }) inputs;



            augmentedValue = defaultValue // {

              __spliced =

                (lib.optionalAttrs (pkgsBuildBuild ? ${name}) { buildBuild = valueBuildBuild; })

                // (lib.optionalAttrs (pkgsBuildHost ? ${name}) { buildHost = valueBuildHost; })

                // (lib.optionalAttrs (pkgsBuildTarget ? ${name}) { buildTarget = valueBuildTarget; })

                // (lib.optionalAttrs (pkgsHostHost ? ${name}) { hostHost = valueHostHost; })

                // (lib.optionalAttrs (pkgsHostTarget ? ${name}) { hostTarget = valueHostTarget; })

                // (lib.optionalAttrs (pkgsTargetTarget ? ${name}) {

                  targetTarget = valueTargetTarget;

                });

              __spliced = lib.filterAttrs (k: v: inputs.${k} ? ${name}) value';

            };

            # Get the set of outputs of a derivation. If one derivation fails to

            # evaluate we don't want to diverge the entire splice, so we fall back
@@ -76,27 +58,12 @@ let 
          # on to splice them together.

          if lib.isDerivation defaultValue then

            augmentedValue

            // spliceReal {

              pkgsBuildBuild = tryGetOutputs valueBuildBuild;

              pkgsBuildHost = tryGetOutputs valueBuildHost;

              pkgsBuildTarget = tryGetOutputs valueBuildTarget;

              pkgsHostHost = tryGetOutputs valueHostHost;

              pkgsHostTarget = getOutputs valueHostTarget;

              pkgsTargetTarget = tryGetOutputs valueTargetTarget;

              # Just recur on plain attrsets

            }

            // spliceReal (mapCrossIndex tryGetOutputs value' // { hostTarget = getOutputs value'.hostTarget; })

          else if lib.isAttrs defaultValue then

            spliceReal {

              pkgsBuildBuild = valueBuildBuild;

              pkgsBuildHost = valueBuildHost;

              pkgsBuildTarget = valueBuildTarget;

              pkgsHostHost = valueHostHost;

              pkgsHostTarget = valueHostTarget;

              pkgsTargetTarget = valueTargetTarget;

            spliceReal value'

          else

            # Don't be fancy about non-derivations. But we could have used used

            # `__functor__` for functions instead.

            }

          else

            defaultValue;

      };

    in
@@ -111,7 +78,7 @@ let 
      pkgsHostTarget,

      pkgsTargetTarget,

    }@args:

    if actuallySplice then spliceReal args else pkgsHostTarget;

    if actuallySplice then spliceReal (renameCrossIndexFrom "pkgs" args) else pkgsHostTarget;



  splicedPackages =

    splicePackages {