Added --compact arg to rc2nix.py for outputting nested Nix attr sets

[c0d3m0nky]

For me the way rc2nix.py outputs it's Nix conversion is unreadable. Not a criticism, just an accommodation I need, so I made it an option

When executing rc2nix.py with no arguments the output remains unchanged

{
  programs.plasma = {
    enable = true;
    shortcuts = {
      ActivityManager.switch-to-activity-1595ee1f-09c7-4e54-9969-1f629be88458 = [ ];
      "KDE Keyboard Layout Switcher"."Switch to Last-Used Keyboard Layout" = "Meta+Alt+L";
      "KDE Keyboard Layout Switcher"."Switch to Next Keyboard Layout" = "Meta+Alt+K";
      ksmserver."Lock Session" = [ "Meta+L" "Screensaver,Meta+L" "Screensaver,Lock Session" ];
      ...
    };
    ...
}

But with the -n|--nested-format argument it will nest the output, attr sets and lists with a single child remain in-line

{
  programs.plasma = {
    enable = true;
    shortcuts = {
      ActivityManager.switch-to-activity-1595ee1f-09c7-4e54-9969-1f629be88458 = [ ];
      "KDE Keyboard Layout Switcher" = {
        "Switch to Last-Used Keyboard Layout" = "Meta+Alt+L";
        "Switch to Next Keyboard Layout" = "Meta+Alt+K";
      };
      ksmserver."Lock Session" = [
        "Meta+L"
        "Screensaver,Meta+L"
        "Screensaver,Lock Session"
      ];
      ...
    };
    ...
}

I also introduced a minor change that will only quote keys when necessary using this regular expression

^[a-z_][\w_-]*?$

If the key begins with a letter or underscore, and the rest of the characters are all alphanumeric, underscore, or dash, it will not unnecessarily quote the key. I'm actually not 100% sure those are all the valid characters, but by making it inclusive it is fail-safe

Additional bugfixes:

• When splitting shortcut values, a regular expression pattern was being used but called in a way it was treating it as a literal string. Using the split function from re now. See this comment for an example

[AlexNabokikh]

A very much needed change!

[c0d3m0nky]

I'm starting to think 'compact' is the wrong term here. Should I change it to 'pretty'? Other suggestions welcome

[AlexNabokikh]

@c0d3m0nky --format or --fmt also could work

[c0d3m0nky]

@c0d3m0nky --format or --fmt also could work

'format' feels too vague

The other option I'm thinking is --nested

Why is coming up with good names always the hardest part? 🥲

[AlexNabokikh]

The official Nix formatting RFC uses expanded and nestedattribute terms, so maybe stick to them. Adding format for clarity wouldn't hurt, though (e.g., --expanded-format or --nested-format)

[c0d3m0nky]

Changed it to -n|--nested-format

[c0d3m0nky]

So I found a bug in rc2nix.py but I'm not sure I should include it in this PR or wait and make a followup PR.

For shortcuts when multiple or none are set it outputs invalid values like

{
        "Window Minimize" = [
          "Meta+Down"
          "Meta+PgDown,Meta+PgDown,Minimize Window"
        ];
        "Window Move" = "none,,Move Window";
}

I have confirmed it happens with the HEAD of this repo too, I did not accidentally introduce this.

Should I include the fix in this PR?

[c0d3m0nky]

Turned out to be an extremely simple fix, so I just included it.