refactor option parsing

src/eval.nix

@@ -0,0 +1,114 @@
+{ configurationnix ? "/etc/nixos/configuration.nix" }:
+with import <nixpkgs/lib>;
+let
+  pkgs = import <nixpkgs> { config = { allowBroken = true; allowUnfree = true; }; system = builtins.currentSystem; };
+
+  configuration = (import configurationnix { inherit pkgs; config = pkgs.config;}) // {nixpkgs.system = builtins.currentSystem;};
+
+  baseModules = import <nixpkgs/nixos/modules/module-list.nix>;
+
+  eval = import <nixpkgs/nixos/lib/eval-config.nix> {
+    modules = [ configurationnix ] ++ baseModules;
+    # system = builtins.currentSystem;
+    inherit pkgs;
+    # check = true;
+    # prefix = [ "boot" ];
+    # lib = pkgs.lib;
+    # baseModules = [];
+  };
+
+
+  scrubOptionValue_ = path: x: visitList:
+    let
+      t = tryScrubOptionValue path x visitList;
+    in
+      (if t.success then
+        t.value
+      else
+        "<error>");
+
+  tryScrubOptionValue = path: x: visitList:
+    let
+      visitList_ = [x] ++ visitList;
+    in
+      builtins.tryEval (
+        if pkgs.lib.any (element: element == x) visitList then "<recursion>"
+        else if pkgs.lib.isDerivation x then "<drv>"+(toString x.outPath)+"</drv>"
+        else if pkgs.lib.isInt x then x
+        else if pkgs.lib.isString x then x
+        else if pkgs.lib.isBool x then x
+        else if pkgs.lib.isFunction x then "<function>"
+        else if pkgs.lib.isList x then (map (y: scrubOptionValue_ path y visitList_) x)
+        else if pkgs.lib.isAttrs x then (pkgs.lib.mapAttrs (n: v: (scrubOptionValue_ path v visitList_)) x)
+        else if builtins.typeOf x == "lambda" then "<lambda>"
+        else toString x);
+
+  optionAttrSetToDocList_ = prefix: options:
+    fold (opt: rest:
+      let
+        docOption = rec {
+          name = showOption opt.loc;
+          description = opt.description or (builtins.trace "Option `${name}' has no description." "");
+          declarations = filter (x: x != unknownModule) opt.declarations;
+          internal = opt.internal or false;
+          visible = opt.visible or true;
+          type = opt.type.name or null;
+        }
+        // (if opt ? example then { example = scrubOptionValue_ (pkgs.lib.splitString "." opt.loc) opt.example []; } else {})
+        // (if opt ? default then { default = scrubOptionValue_ (pkgs.lib.splitString "." opt.loc) opt.default []; } else {})
+        // (if opt ? defaultText then { default = opt.defaultText; } else {});
+
+        subOptions =
+          let ss = opt.type.getSubOptions opt.loc;
+          in if ss != {} then optionAttrSetToDocList_ opt.loc ss else [];
+      in
+        # FIXME: expensive, O(n^2)
+        [ docOption ] ++ subOptions ++ rest) [] (collect isOption options);
+
+
+  prefix = toString <nixpkgs>;
+
+  # Remove invisible and internal options.
+  optionsList = filter (opt: opt.visible && !opt.internal) (optionAttrSetToDocList_ [] eval.options);
+
+  stripPrefix = fn:
+  if substring 0 (stringLength prefix) fn == prefix then
+    substring (stringLength prefix + 1) 1000 fn
+  else
+    fn;
+
+  substFunction = x:
+    if builtins.isAttrs x then mapAttrs (name: substFunction) x
+    else if builtins.isList x then map substFunction x
+    else if builtins.isFunction x then "<function>"
+    else x;
+
+  # Clean up declaration sites to not refer to the NixOS source tree.
+  optionsList_ = flip map optionsList (opt: opt // {
+    declarations = map (fn: stripPrefix fn) opt.declarations;
+  }
+  // optionalAttrs (opt ? example) { example = substFunction opt.example; }
+  // optionalAttrs (opt ? default) { default = substFunction opt.default; }
+  // optionalAttrs (opt ? type) { type = substFunction opt.type; });
+
+
+  createEntry = path: root: visitList:
+    let
+      value = if path == [""] then root else pkgs.lib.attrByPath path "<error>" root;
+      val = scrubOptionValue_ path value visitList;
+    in (
+      {inherit val path;}
+    );
+  values = attrs: createEntry (pkgs.lib.splitString "." attrs) configuration [];
+  getValue = path:
+    let
+      value = pkgs.lib.attrByPath path null (values "");
+    in
+      { val = scrubOptionValue_ [""] value []; };
+      # { val = scrubOptionValue_ [""] value []; };
+
+in {
+  # output = optionAttrSetToDocList_ [] eval.options;
+  options = (builtins.unsafeDiscardStringContext (builtins.toJSON (listToAttrs (map (o: { name = o.name; value = removeAttrs o ["name" "visible" "internal"]; }) optionsList_))));
+  config = builtins.toJSON (values "services");
+}