From ea24675e4f4f4c494ccb04f6645db2a394d348ee Mon Sep 17 00:00:00 2001
From: Quentin Smith <quentin@mit.edu>
Date: Sat, 12 Jul 2025 15:32:14 -0400
Subject: [PATCH] lib: Improve KDL generator (#7429)

This adds support for generating ordered children and nodes with
attributes and/or properties but no children. These are both needed to
generate zellij keybinding configuration.
---
 modules/lib/generators.nix            | 48 +++++++++++++--------------
 tests/lib/generators/tokdl-result.txt |  5 +++
 tests/lib/generators/tokdl.nix        | 13 ++++++++
 3 files changed, 42 insertions(+), 24 deletions(-)

diff --git a/modules/lib/generators.nix b/modules/lib/generators.nix
index 5fe3d8afb..2fdbdca18 100644
--- a/modules/lib/generators.nix
+++ b/modules/lib/generators.nix
@@ -116,34 +116,34 @@
       convertAttrsToKDL =
         name: attrs:
         let
-          optArgsString = lib.optionalString (attrs ? "_args") (
-            lib.pipe attrs._args [
-              (map literalValueToString)
-              (lib.concatStringsSep " ")
-              (s: s + " ")
-            ]
+          optArgs = map literalValueToString (attrs._args or [ ]);
+          optProps = lib.mapAttrsToList (name: value: "${name}=${literalValueToString value}") (
+            attrs._props or { }
           );
 
-          optPropsString = lib.optionalString (attrs ? "_props") (
-            lib.pipe attrs._props [
-              (lib.mapAttrsToList (name: value: "${name}=${literalValueToString value}"))
-              (lib.concatStringsSep " ")
-              (s: s + " ")
-            ]
-          );
+          orderedChildren = lib.pipe (attrs._children or [ ]) [
+            (map (child: mapAttrsToList convertAttributeToKDL child))
+            lib.flatten
+          ];
+          unorderedChildren = lib.pipe attrs [
+            (lib.filterAttrs (
+              name: _:
+              !(elem name [
+                "_args"
+                "_props"
+                "_children"
+              ])
+            ))
+            (mapAttrsToList convertAttributeToKDL)
+          ];
+          children = orderedChildren ++ unorderedChildren;
+          optChildren = lib.optional (children != [ ]) ''
+            {
+            ${indentStrings children}
+            }'';
 
-          children = lib.filterAttrs (
-            name: _:
-            !(elem name [
-              "_args"
-              "_props"
-            ])
-          ) attrs;
         in
-        ''
-          ${name} ${optArgsString}${optPropsString}{
-          ${indentStrings (mapAttrsToList convertAttributeToKDL children)}
-          }'';
+        lib.concatStringsSep " " ([ name ] ++ optArgs ++ optProps ++ optChildren);
 
       # List Conversion
       # String -> ListOf (OneOf [Int Float String Bool Null])  -> String
diff --git a/tests/lib/generators/tokdl-result.txt b/tests/lib/generators/tokdl-result.txt
index 6ad2af368..ea48b7bec 100644
--- a/tests/lib/generators/tokdl-result.txt
+++ b/tests/lib/generators/tokdl-result.txt
@@ -1,7 +1,12 @@
 a 1
+argsAndProps 1 2 a=3
 b "string"
 bigFlatItems 23847590283751 1.239000 "multiline \" \" \"\nstring\n" null
 c "multiline string\nwith special characters:\n\t \n \\" \"\n"
+duplicateChildren {
+	child 2
+	child 1
+}
 extraAttrs 2 true arg1=1 arg2=false {
 	nested {
 		a 1
diff --git a/tests/lib/generators/tokdl.nix b/tests/lib/generators/tokdl.nix
index abe4a9862..7bb6dc8af 100644
--- a/tests/lib/generators/tokdl.nix
+++ b/tests/lib/generators/tokdl.nix
@@ -38,6 +38,10 @@
       [ ]
       [ null ]
     ];
+    duplicateChildren._children = [
+      { child = [ 2 ]; }
+      { child = [ 1 ]; }
+    ];
     extraAttrs = {
       _args = [
         2
@@ -52,6 +56,15 @@
         b = null;
       };
     };
+    argsAndProps = {
+      _args = [
+        1
+        2
+      ];
+      _props = {
+        a = 3;
+      };
+    };
     listInAttrsInList = {
       list1 = [
         { a = 1; }