Refactor select with new maybe selector

This is a great refactor of the select functionality in the flake class.
This now uses the same parser as the nix code, but runs it in python for
nice stacktraces.

Also we now have a maybe selector which can be used by prepending the
selector with a ?

Tests have been expanded to make sure the code is more stable and easier
to understand

lib/default.nix

@@ -30,6 +30,6 @@ lib.fix (clanLib: {
   # Plain imports.
   values = import ./introspection { inherit lib; };
   jsonschema = import ./jsonschema { inherit lib; };
-  select = import select/default.nix;
+  select = self.inputs.nix-select.lib;
   facts = import ./facts.nix { inherit lib; };
 })

lib/flake-module.nix

@@ -11,7 +11,6 @@ rec {
     ./introspection/flake-module.nix
     ./inventory/flake-module.nix
     ./jsonschema/flake-module.nix
-    ./select/flake-module.nix
   ];
   flake.clanLib = import ./default.nix {
     inherit lib inputs self;

lib/select/default.nix

@@ -1,68 +0,0 @@
-let
-  recursiveSelect =
-    selectorIndex: selectorList: target:
-    let
-      selector = builtins.elemAt selectorList selectorIndex;
-    in
-
-    # selector is empty, we are done
-    if selectorIndex + 1 > builtins.length selectorList then
-      target
-
-    else if builtins.isList target then
-      # support bla.* for lists and recurse into all elements
-      if selector == "*" then
-        builtins.map (v: recursiveSelect (selectorIndex + 1) selectorList v) target
-      # support bla.3 for lists and recurse into the 4th element
-      else if (builtins.match "[[:digit:]]*" selector) == [ ] then
-        recursiveSelect (selectorIndex + 1) selectorList (
-          builtins.elemAt target (builtins.fromJSON selector)
-        )
-      else
-        throw "only * or a number is allowed in list selector"
-
-    else if builtins.isAttrs target then
-      # handle the case bla.x.*.z where x is an attrset and we recurse into all elements
-      if selector == "*" then
-        builtins.mapAttrs (_: v: recursiveSelect (selectorIndex + 1) selectorList v) target
-      # support bla.{x,y,z}.world where we get world from each of x, y and z
-      else if (builtins.match ''^\{([^}]*)}$'' selector) != null then
-        let
-          attrsAsList = (
-            builtins.filter (x: !builtins.isList x) (
-              builtins.split "," (builtins.head (builtins.match ''^\{([^}]*)}$'' selector))
-            )
-          );
-          dummyAttrSet = builtins.listToAttrs (
-            map (x: {
-              name = x;
-              value = null;
-            }) attrsAsList
-          );
-          filteredAttrs = builtins.intersectAttrs dummyAttrSet target;
-        in
-        builtins.mapAttrs (_: v: recursiveSelect (selectorIndex + 1) selectorList v) filteredAttrs
-      else
-        recursiveSelect (selectorIndex + 1) selectorList (builtins.getAttr selector target)
-    else
-      throw "Expected a list or an attrset";
-
-  parseSelector =
-    selector:
-    let
-      splitByQuote = x: builtins.filter (x: !builtins.isList x) (builtins.split ''"'' x);
-      splitByDot =
-        x:
-        builtins.filter (x: x != "") (
-          map (builtins.replaceStrings [ "." ] [ "" ]) (
-            builtins.filter (x: !builtins.isList x) (builtins.split ''\.'' x)
-          )
-        );
-      handleQuoted =
-        x: if x == [ ] then [ ] else [ (builtins.head x) ] ++ handleUnquoted (builtins.tail x);
-      handleUnquoted =
-        x: if x == [ ] then [ ] else splitByDot (builtins.head x) ++ handleQuoted (builtins.tail x);
-    in
-    handleUnquoted (splitByQuote selector);
-in
-selector: target: recursiveSelect 0 (parseSelector selector) target

lib/select/flake-module.nix

@@ -1,45 +0,0 @@
-{ self, inputs, ... }:
-let
-  inputOverrides = builtins.concatStringsSep " " (
-    builtins.map (input: " --override-input ${input} ${inputs.${input}}") (builtins.attrNames inputs)
-  );
-in
-{
-  perSystem =
-    {
-      pkgs,
-      lib,
-      system,
-      ...
-    }:
-    {
-      # Run: nix-unit --extra-experimental-features flakes --flake .#legacyPackages.x86_64-linux.evalTests
-      legacyPackages.evalTests-select = import ./tests.nix {
-        inherit lib;
-        inherit (self) clanLib;
-      };
-
-      checks = {
-        lib-select-eval = pkgs.runCommand "tests" { nativeBuildInputs = [ pkgs.nix-unit ]; } ''
-          export HOME="$(realpath .)"
-          export NIX_ABORT_ON_WARN=1
-          nix-unit --eval-store "$HOME" \
-            --extra-experimental-features flakes \
-            --show-trace \
-            ${inputOverrides} \
-            --flake ${
-              self.filter {
-                include = [
-                  "flakeModules"
-                  "lib"
-                  "clanModules/flake-module.nix"
-                  "clanModules/borgbackup"
-                ];
-              }
-            }#legacyPackages.${system}.evalTests-select
-
-          touch $out
-        '';
-      };
-    };
-}

lib/select/tests.nix

@@ -1,10 +0,0 @@
-{ clanLib, ... }:
-let
-  inherit (clanLib) select;
-in
-{
-  test_simple_1 = {
-    expr = select "a" { a = 1; };
-    expected = 1;
-  };
-}