feat: initial v3 rewrite

lib/impl/helpers.nix

@@ -0,0 +1,90 @@
+{
+  pkgs,
+  lib,
+} @ args: let
+  inherit (lib) types isAttrs filterAttrs mapAttrs mkOption mkOptionType isType;
+in rec {
+  prepend = key: arr: job: {
+    ${key} = arr ++ (job.${key} or []);
+  };
+  append = key: arr: job: {
+    ${key} = (job.${key} or []) ++ arr;
+  };
+  prependToBeforeScript = prepend "before_script";
+  appendToAfterScript = append "after_script";
+
+  # json is also valid yaml and this removes dependency on jq and/or remarshal
+  # (used in pkgs.formats.json and pkgs.formats.yaml respectively)
+  toYaml = name: value: builtins.toFile name (builtins.toJSON value);
+  toYamlPretty = (pkgs.formats.yaml {}).generate;
+
+  customMapAttrs = cb: set: builtins.listToAttrs (builtins.map (key: cb key (builtins.getAttr key set)) (builtins.attrNames set));
+
+  filterAttrsRec = pred: v:
+    if isAttrs v
+    then filterAttrs pred (mapAttrs (_path: filterAttrsRec pred) v)
+    else v;
+
+  # filter job's variables to either only those containing store paths
+  # or those that do not
+  filterJobVariables = nix: job:
+    lib.concatMapAttrs (
+      name: value:
+        lib.optionalAttrs ((lib.hasInfix "/nix/store/" value) == nix) {
+          ${name} = value;
+        }
+    )
+    (job.variables or {});
+
+  deepMerge = lhs: rhs:
+    lhs
+    // rhs
+    // (builtins.mapAttrs (
+        rName: rValue: let
+          lValue = lhs.${rName} or null;
+        in
+          if builtins.isAttrs lValue && builtins.isAttrs rValue
+          then deepMerge lValue rValue
+          else if builtins.isList lValue && builtins.isList rValue
+          then lValue ++ rValue
+          else rValue
+      )
+      rhs);
+
+  unsetType = mkOptionType {
+    name = "unset";
+    description = "unset";
+    descriptionClass = "noun";
+    check = _value: true;
+  };
+  unset = {
+    _type = "unset";
+  };
+  isUnset = isType "unset";
+  unsetOr = types.either unsetType;
+  mkUnsetOption = opts:
+    mkOption (opts
+      // {
+        type = unsetOr opts.type;
+        default = opts.default or unset;
+      });
+
+  filterUnset = value:
+    if builtins.isAttrs value && !builtins.hasAttr "_type" value
+    then let
+      filteredAttrs = builtins.mapAttrs (_n: filterUnset) value;
+    in
+      filterAttrs (_name: value: (!isUnset value)) filteredAttrs
+    else if builtins.isList value
+    then builtins.filter (elem: !isUnset elem) (map filterUnset value)
+    else value;
+
+  # args.pkgs so "pkgs" does not need to be passed all the time
+  stdenvMinimal = args.pkgs.stdenvNoCC.override {
+    cc = null;
+    preHook = "";
+    allowedRequisites = null;
+    initialPath = with args.pkgs; [coreutils findutils];
+    extraNativeBuildInputs = [];
+  };
+}