home-manager/modules/lib/generators.nix
h7x4 fce9dbfeb4
lib: add generator for KDL
Added a generator for the KDL document language.
This is in order for home-manager to natively generate
the new config format for zellij, as described in nix-community#3364.

There is not a one to one mapping between KDL and nix types,
but attrset translation is heavily based on KDLs JSON-IN-KDL microsyntax.
The exception here is the `_args` and `_props` arguments, which lets you
specify arguments and properties as described in the spec.

See more here:
- https://kdl.dev/
- https://github.com/kdl-org/kdl/blob/main/SPEC.md

The generator also conforms to the interface from the nixpkgs manual:
https://nixos.org/manual/nixpkgs/stable/#sec-generators

Co-authored-by: Gaetan Lepage <gaetan@glepage.com>
2023-03-10 16:48:10 +01:00

102 lines
3.6 KiB
Nix

{ lib }:
{
toKDL = { }:
let
inherit (lib) concatStringsSep splitString mapAttrsToList any;
inherit (builtins) typeOf replaceStrings elem;
# ListOf String -> String
indentStrings = let
# Although the input of this function is a list of strings,
# the strings themselves *will* contain newlines, so you need
# to normalize the list by joining and resplitting them.
unlines = lib.splitString "\n";
lines = lib.concatStringsSep "\n";
indentAll = lines: concatStringsSep "\n" (map (x: " " + x) lines);
in stringsWithNewlines: indentAll (unlines (lines stringsWithNewlines));
# String -> String
sanitizeString = replaceStrings [ "\n" ''"'' ] [ "\\n" ''\"'' ];
# OneOf [Int Float String Bool Null] -> String
literalValueToString = element:
lib.throwIfNot
(elem (typeOf element) [ "int" "float" "string" "bool" "null" ])
"Cannot convert value of type ${typeOf element} to KDL literal."
(if typeOf element == "null" then
"null"
else if element == false then
"false"
else if element == true then
"true"
else if typeOf element == "string" then
''"${sanitizeString element}"''
else
toString element);
# Attrset Conversion
# String -> AttrsOf Anything -> String
convertAttrsToKDL = name: attrs:
let
optArgsString = lib.optionalString (attrs ? "_args")
(lib.pipe attrs._args [
(map literalValueToString)
(lib.concatStringsSep " ")
(s: s + " ")
]);
optPropsString = lib.optionalString (attrs ? "_props")
(lib.pipe attrs._props [
(lib.mapAttrsToList
(name: value: "${name}=${literalValueToString value}"))
(lib.concatStringsSep " ")
(s: s + " ")
]);
children =
lib.filterAttrs (name: _: !(elem name [ "_args" "_props" ])) attrs;
in ''
${name} ${optArgsString}${optPropsString}{
${indentStrings (mapAttrsToList convertAttributeToKDL children)}
}'';
# List Conversion
# String -> ListOf (OneOf [Int Float String Bool Null]) -> String
convertListOfFlatAttrsToKDL = name: list:
let flatElements = map literalValueToString list;
in "${name} ${concatStringsSep " " flatElements}";
# String -> ListOf Anything -> String
convertListOfNonFlatAttrsToKDL = name: list: ''
${name} {
${indentStrings (map (x: convertAttributeToKDL "-" x) list)}
}'';
# String -> ListOf Anything -> String
convertListToKDL = name: list:
let elementsAreFlat = !any (el: elem (typeOf el) [ "list" "set" ]) list;
in if elementsAreFlat then
convertListOfFlatAttrsToKDL name list
else
convertListOfNonFlatAttrsToKDL name list;
# Combined Conversion
# String -> Anything -> String
convertAttributeToKDL = name: value:
let vType = typeOf value;
in if elem vType [ "int" "float" "bool" "null" "string" ] then
"${name} ${literalValueToString value}"
else if vType == "set" then
convertAttrsToKDL name value
else if vType == "list" then
convertListToKDL name value
else
throw ''
Cannot convert type `(${typeOf value})` to KDL:
${name} = ${toString value}
'';
in attrs: ''
${concatStringsSep "\n" (mapAttrsToList convertAttributeToKDL attrs)}
'';
}