nixos/dconf: support generating from attrs

doc/default.nix

@@ -21,6 +21,7 @@ let
       { name = "filesystem"; description = "filesystem functions"; }
       { name = "sources"; description = "source filtering functions"; }
       { name = "cli"; description = "command-line serialization functions"; }
+      { name = "gvariant"; description = "GVariant formatted string serialization functions"; }
     ];
   };
 

lib/default.nix

@@ -41,6 +41,7 @@ let
 
     # serialization
     cli = callLibs ./cli.nix;
+    gvariant = callLibs ./gvariant.nix;
     generators = callLibs ./generators.nix;
 
     # misc

lib/generators.nix

@@ -230,6 +230,14 @@ rec {
     in
       toINI_ (gitFlattenAttrs attrs);
 
+  # mkKeyValueDefault wrapper that handles dconf INI quirks.
+  # The main differences of the format is that it requires strings to be quoted.
+  mkDconfKeyValue = mkKeyValueDefault { mkValueString = v: toString (lib.gvariant.mkValue v); } "=";
+
+  # Generates INI in dconf keyfile style. See https://help.gnome.org/admin/system-admin-guide/stable/dconf-keyfiles.html.en
+  # for details.
+  toDconfINI = toINI { mkKeyValue = mkDconfKeyValue; };
+
   /* Generates JSON from an arbitrary (non-function) value.
     * For more information see the documentation of the builtin.
     */

lib/gvariant.nix

@@ -0,0 +1,290 @@
+# This file is based on https://github.com/nix-community/home-manager
+# Copyright (c) 2017-2022 Home Manager contributors
+#
+
+
+{ lib }:
+
+/* A partial and basic implementation of GVariant formatted strings.
+   See https://docs.gtk.org/glib/gvariant-format-strings.html for detauls.
+
+   Note, this API is not considered fully stable and it might therefore
+   change in backwards incompatible ways without prior notice.
+*/
+let
+  inherit (lib)
+    concatMapStringsSep concatStrings escape head replaceStrings;
+
+  mkPrimitive = t: v: {
+    _type = "gvariant";
+    type = t;
+    value = v;
+    __toString = self: "@${self.type} ${toString self.value}"; # https://docs.gtk.org/glib/gvariant-text.html
+  };
+
+  type = {
+    arrayOf = t: "a${t}";
+    maybeOf = t: "m${t}";
+    tupleOf = ts: "(${concatStrings ts})";
+    dictionaryEntryOf = nameType: valueType: "{${nameType}${valueType}}";
+    string = "s";
+    boolean = "b";
+    uchar = "y";
+    int16 = "n";
+    uint16 = "q";
+    int32 = "i";
+    uint32 = "u";
+    int64 = "x";
+    uint64 = "t";
+    double = "d";
+    variant = "v";
+  };
+
+  /* Check if a value is a GVariant value
+
+     Type:
+       isGVariant :: Any -> Bool
+  */
+  isGVariant = v: v._type or "" == "gvariant";
+
+in
+rec {
+
+  inherit type isGVariant;
+
+  /* Returns the GVariant value that most closely matches the given Nix value.
+     If no GVariant value can be found unambiguously then error is thrown.
+
+     Type:
+       mkValue :: Any -> gvariant
+  */
+  mkValue = v:
+    if builtins.isBool v then
+      mkBoolean v
+    else if builtins.isFloat v then
+      mkDouble v
+    else if builtins.isString v then
+      mkString v
+    else if builtins.isList v then
+      mkArray v
+    else if isGVariant v then
+      v
+    else
+      throw "The GVariant type of ${v} can't be inferred.";
+
+  /* Returns the GVariant array from the given type of the elements and a Nix list.
+
+     Type:
+       mkArray :: [Any] -> gvariant
+
+     Example:
+       # Creating a string array
+       lib.gvariant.mkArray [ "a" "b" "c" ]
+  */
+  mkArray = elems:
+    let
+      vs = map mkValue (lib.throwIf (elems == [ ]) "Please create empty array with mkEmptyArray." elems);
+      elemType = lib.throwIfNot (lib.all (t: (head vs).type == t) (map (v: v.type) vs))
+        "Elements in a list should have same type."
+        (head vs).type;
+    in
+    mkPrimitive (type.arrayOf elemType) vs // {
+      __toString = self:
+        "@${self.type} [${concatMapStringsSep "," toString self.value}]";
+    };
+
+  /* Returns the GVariant array from the given empty Nix list.
+
+     Type:
+       mkEmptyArray :: gvariant.type -> gvariant
+
+     Example:
+       # Creating an empty string array
+       lib.gvariant.mkEmptyArray (lib.gvariant.type.string)
+  */
+  mkEmptyArray = elemType: mkPrimitive (type.arrayOf elemType) [ ] // {
+    __toString = self: "@${self.type} []";
+  };
+
+
+  /* Returns the GVariant variant from the given Nix value. Variants are containers
+     of different GVariant type.
+
+     Type:
+       mkVariant :: Any -> gvariant
+
+     Example:
+       lib.gvariant.mkArray [
+         (lib.gvariant.mkVariant "a string")
+         (lib.gvariant.mkVariant (lib.gvariant.mkInt32 1))
+       ]
+  */
+  mkVariant = elem:
+    let gvarElem = mkValue elem;
+    in mkPrimitive type.variant gvarElem // {
+      __toString = self: "<${toString self.value}>";
+    };
+
+  /* Returns the GVariant dictionary entry from the given key and value.
+
+     Type:
+       mkDictionaryEntry :: String -> Any -> gvariant
+
+     Example:
+       # A dictionary describing an Epiphany’s search provider
+       [
+         (lib.gvariant.mkDictionaryEntry "url" (lib.gvariant.mkVariant "https://duckduckgo.com/?q=%s&t=epiphany"))
+         (lib.gvariant.mkDictionaryEntry "bang" (lib.gvariant.mkVariant "!d"))
+         (lib.gvariant.mkDictionaryEntry "name" (lib.gvariant.mkVariant "DuckDuckGo"))
+       ]
+  */
+  mkDictionaryEntry =
+    # The key of the entry
+    name:
+    # The value of the entry
+    value:
+    let
+      name' = mkValue name;
+      value' = mkValue value;
+      dictionaryType = type.dictionaryEntryOf name'.type value'.type;
+    in
+    mkPrimitive dictionaryType { inherit name value; } // {
+      __toString = self: "@${self.type} {${name'},${value'}}";
+    };
+
+  /* Returns the GVariant maybe from the given element type.
+
+     Type:
+       mkMaybe :: gvariant.type -> Any -> gvariant
+  */
+  mkMaybe = elemType: elem:
+    mkPrimitive (type.maybeOf elemType) elem // {
+      __toString = self:
+        if self.value == null then
+          "@${self.type} nothing"
+        else
+          "just ${toString self.value}";
+    };
+
+  /* Returns the GVariant nothing from the given element type.
+
+     Type:
+       mkNothing :: gvariant.type -> gvariant
+  */
+  mkNothing = elemType: mkMaybe elemType null;
+
+  /* Returns the GVariant just from the given Nix value.
+
+     Type:
+       mkJust :: Any -> gvariant
+  */
+  mkJust = elem: let gvarElem = mkValue elem; in mkMaybe gvarElem.type gvarElem;
+
+  /* Returns the GVariant tuple from the given Nix list.
+
+     Type:
+       mkTuple :: [Any] -> gvariant
+  */
+  mkTuple = elems:
+    let
+      gvarElems = map mkValue elems;
+      tupleType = type.tupleOf (map (e: e.type) gvarElems);
+    in
+    mkPrimitive tupleType gvarElems // {
+      __toString = self:
+        "@${self.type} (${concatMapStringsSep "," toString self.value})";
+    };
+
+  /* Returns the GVariant boolean from the given Nix bool value.
+
+     Type:
+       mkBoolean :: Bool -> gvariant
+  */
+  mkBoolean = v:
+    mkPrimitive type.boolean v // {
+      __toString = self: if self.value then "true" else "false";
+    };
+
+  /* Returns the GVariant string from the given Nix string value.
+
+     Type:
+       mkString :: String -> gvariant
+  */
+  mkString = v:
+    let sanitize = s: replaceStrings [ "\n" ] [ "\\n" ] (escape [ "'" "\\" ] s);
+    in mkPrimitive type.string v // {
+      __toString = self: "'${sanitize self.value}'";
+    };
+
+  /* Returns the GVariant object path from the given Nix string value.
+
+     Type:
+       mkObjectpath :: String -> gvariant
+  */
+  mkObjectpath = v:
+    mkPrimitive type.string v // {
+      __toString = self: "objectpath '${escape [ "'" ] self.value}'";
+    };
+
+  /* Returns the GVariant uchar from the given Nix int value.
+
+     Type:
+       mkUchar :: Int -> gvariant
+  */
+  mkUchar = mkPrimitive type.uchar;
+
+  /* Returns the GVariant int16 from the given Nix int value.
+
+     Type:
+       mkInt16 :: Int -> gvariant
+  */
+  mkInt16 = mkPrimitive type.int16;
+
+  /* Returns the GVariant uint16 from the given Nix int value.
+
+     Type:
+       mkUint16 :: Int -> gvariant
+  */
+  mkUint16 = mkPrimitive type.uint16;
+
+  /* Returns the GVariant int32 from the given Nix int value.
+
+     Type:
+       mkInt32 :: Int -> gvariant
+  */
+  mkInt32 = v:
+    mkPrimitive type.int32 v // {
+      __toString = self: toString self.value;
+    };
+
+  /* Returns the GVariant uint32 from the given Nix int value.
+
+     Type:
+       mkUint32 :: Int -> gvariant
+  */
+  mkUint32 = mkPrimitive type.uint32;
+
+  /* Returns the GVariant int64 from the given Nix int value.
+
+     Type:
+       mkInt64 :: Int -> gvariant
+  */
+  mkInt64 = mkPrimitive type.int64;
+
+  /* Returns the GVariant uint64 from the given Nix int value.
+
+     Type:
+       mkUint64 :: Int -> gvariant
+  */
+  mkUint64 = mkPrimitive type.uint64;
+
+  /* Returns the GVariant double from the given Nix float value.
+
+     Type:
+       mkDouble :: Float -> gvariant
+  */
+  mkDouble = v:
+    mkPrimitive type.double v // {
+      __toString = self: toString self.value;
+    };
+}