From 0c51608f6c11fd8e15679d77e7a9ae8c3a51fe78 Mon Sep 17 00:00:00 2001
From: Profpatsch <mail@profpatsch.de>
Date: Fri, 6 May 2022 00:32:49 +0200
Subject: feat(users/Profpatsch): add toINI
MIME-Version: 1.0
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This is a morph of the `pkgs.lib.generators.toINIWithGlobalSection`
function, which is simplified, inlined, and takes lists instead of
attrsets. This makes the key ordering stable and is easy to generate
from dhall.

Ideally I’d upstream it at one point (in the sense that
`generators.toINI` can also take lists), but that will be a lot more
work that is not necessary atm.

Change-Id: I7d6c129cfee9faedb62f69d479e59a6e05bb7ac6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5529
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>
---
 users/Profpatsch/toINI.nix | 79 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 users/Profpatsch/toINI.nix

diff --git a/users/Profpatsch/toINI.nix b/users/Profpatsch/toINI.nix
new file mode 100644
index 0000000000..537505d30b
--- /dev/null
+++ b/users/Profpatsch/toINI.nix
@@ -0,0 +1,79 @@
+{ lib, ... }:
+let
+  /* Generate an INI-style config file from an attrset
+   * specifying the global section (no header), and a
+   * list of sections which contain name/value pairs.
+   *
+   * generators.toINI {} {
+   *   globalSection = [
+   *     { name = "someGlobalKey"; value = "hi"; }
+   *   ];
+   *   sections = [
+   *     { name = "foo"; value = [
+   *         { name = "hi"; value = "${pkgs.hello}"; }
+   *         { name = "ciao"; value = "bar"; }
+   *       ];
+   *     }
+   *     { name = "baz";
+   *       value = [ { name = "also, integers"; value = 42; } ];
+   *     }
+   *   ];
+   * }
+   *
+   *> someGlobalKey=hi
+   *>
+   *> [foo]
+   *> hi=/nix/store/y93qql1p5ggfnaqjjqhxcw0vqw95rlz0-hello-2.10
+   *> ciao=bar
+   *>
+   *> [baz]
+   *> also, integers=42
+   *>
+   *
+   * The mk* configuration attributes can generically change
+   * the way sections and key-value strings are generated.
+   *
+   * Order of the sections and of keys is preserved,
+   * duplicate keys are allowed.
+   */
+  toINI =
+    {
+      # apply transformations (e.g. escapes) to section names
+      mkSectionName ? (name: lib.strings.escape [ "[" "]" ] name)
+    , # format a setting line from key and value
+      mkKeyValue ? lib.generators.mkKeyValueDefault { } "="
+    ,
+    }: { globalSection, sections }:
+    let
+      mkSection = sectName: sectValues: ''
+        [${mkSectionName sectName}]
+      '' + toKeyValue { inherit mkKeyValue; } sectValues;
+      # map input to ini sections
+      mkSections = lib.strings.concatMapStringsSep "\n"
+        ({ name, value }: mkSection name value)
+        sections;
+      mkGlobalSection =
+        if globalSection == [ ]
+        then ""
+        else toKeyValue { inherit mkKeyValue; } globalSection
+          + "\n";
+    in
+    mkGlobalSection
+    + mkSections;
+
+  /* Generate a name-value-style config file from a list.
+   *
+   * mkKeyValue is the same as in toINI.
+   */
+  toKeyValue =
+    { mkKeyValue ? lib.generators.mkKeyValueDefault { } "="
+    ,
+    }:
+    let
+      mkLine = k: v: mkKeyValue k v + "\n";
+      mkLines = k: v: [ (mkLine k v) ];
+    in
+    nameValues: lib.strings.concatStrings (lib.concatLists (map ({ name, value }: mkLines name value) nameValues));
+
+in
+toINI
-- 
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