lib: add two new gvariant types

Add GVariant variant and dictionary entry types

docs/writing-modules.adoc

@@ -167,9 +167,11 @@ Builds a GVariant array containing the given list of elements, where each elemen
 - `hm.gvariant.type.int64`
 - `hm.gvariant.type.uint64`
 - `hm.gvariant.type.double`
+- `hm.gvariant.type.variant`
 - `hm.gvariant.type.arrayOf type`
 - `hm.gvariant.type.maybeOf type`
 - `hm.gvariant.type.tupleOf types`
+- `hm.gvariant.type.dictionaryEntryOf types`
 --
 +
 where `type` and `types` are themselves a type and list of types, respectively.
@@ -185,3 +187,9 @@ Builds a GVariant maybe value containing the given GVariant element.
 +
 `hm.gvariant.mkTuple elements`:::
 Builds a GVariant tuple containing the given list of elements, where each element is a GVariant value.
++
+`hm.gvariant.mkVariant element`:::
+Builds a GVariant variant which contains the value of a GVariant element.
++
+`hm.gvariant.mkDictionaryEntry elements`:::
+Builds a GVariant dictionary entry containing the given list of elements, where each element is a GVariant value.

modules/lib/gvariant.nix

@@ -20,6 +20,7 @@ let
     arrayOf = t: "a${t}";
     maybeOf = t: "m${t}";
     tupleOf = ts: "(${concatStrings ts})";
+    dictionaryEntryOf = ts: "{${concatStrings ts}}";
     string = "s";
     boolean = "b";
     uchar = "y";
@@ -30,6 +31,7 @@ let
     int64 = "x";
     uint64 = "t";
     double = "d";
+    variant = "v";
   };
 
   # Returns the GVariant type of a given Nix value. If no type can be
@@ -74,13 +76,13 @@ in rec {
   isGVariant = v: v._type or "" == "gvariant";
 
   isArray = hasPrefix "a";
+  isDictionaryEntry = hasPrefix "{";
   isMaybe = hasPrefix "m";
   isTuple = hasPrefix "(";
 
   # Returns the GVariant value that most closely matches the given Nix
   # value. If no GVariant value can be found then `null` is returned.
-  #
+
-  # No support for dictionaries, maybe types, or variants.
   mkValue = v:
     if builtins.isBool v then
       mkBoolean v
@@ -105,6 +107,21 @@ in rec {
 
   mkEmptyArray = elemType: mkArray elemType [ ];
 
+  mkVariant = elem:
+    let gvarElem = mkValue elem;
+    in mkPrimitive type.variant gvarElem // {
+      __toString = self: "@${self.type} <${toString self.value}>";
+    };
+
+  mkDictionaryEntry = elems:
+    let
+      gvarElems = map mkValue elems;
+      dictionaryType = type.dictionaryEntryOf (map (e: e.type) gvarElems);
+    in mkPrimitive dictionaryType gvarElems // {
+      __toString = self:
+        "@${self.type} {${concatMapStringsSep "," toString self.value}}";
+    };
+
   mkNothing = elemType: mkMaybe elemType null;
 
   mkJust = elem: let gvarElem = mkValue elem; in mkMaybe gvarElem.type gvarElem;

modules/lib/types.nix

@@ -95,6 +95,10 @@ in rec {
         mergeOneOption loc defs
       else if gvar.isMaybe sharedDefType && allChecked then
         mergeOneOption loc defs
+      else if gvar.isDictionaryEntry sharedDefType && allChecked then
+        mergeOneOption loc defs
+      else if gvar.type.variant == sharedDefType && allChecked then
+        mergeOneOption loc defs
       else if gvar.type.string == sharedDefType && allChecked then
         types.str.merge loc defs
       else if gvar.type.double == sharedDefType && allChecked then

tests/lib/types/gvariant-merge.nix

@@ -50,6 +50,11 @@ in {
 
         { maybe1 = mkNothing type.string; }
         { maybe2 = mkJust (mkUint32 4); }
+
+        { variant1 = mkVariant "foo"; }
+        { variant2 = mkVariant 42; }
+
+        { dictionaryEntry = mkDictionaryEntry [ 1 [ "foo" ] ]; }
       ];
 
     home.file."result.txt".text = let
@@ -65,6 +70,7 @@ in {
             array1 = @as ['one','two']
             array2 = @au [1,2]
             bool = true
+            dictionaryEntry = @{ias} {1,@as ['foo']}
             emptyArray1 = @as []
             emptyArray2 = @au []
             escapedString = '\'\\\n'
@@ -79,6 +85,8 @@ in {
             uint16 = @q 42
             uint32 = @u 42
             uint64 = @t 42
+            variant1 = @v <'foo'>
+            variant2 = @v <42>
           ''
         }
     '';