Nushell completions pack

Moving on...

I think I'm going to abandon this project. Man pages are inconsistent across distributions, even for packages that are the same version. Whether you go all overboard like this and try to track a patch set, or just generate the completions once and track those completion files, you're stuck tracking changes to man pages in some way or another constantly for every distro.

Even if you do manage to put together enough people to do that thankless work and manage to get this overengineered solution to be robust and less klunky, there's another problem: nu takes about 1 second to load 1000 completion files on launch, meaning that launching my shell took at least 4.5-5 seconds every time. I put up with this for a little while, but then realized in a near-OOM situation I had no way to get to a shell that would open without compounding the problem by a lot (since nu was my default shell).

I think that I'll probably be trying out these instructions for setting up Carapace for completions next time I need to scratch this itch.

If you're interested in continuing this work feel free to fork it, and reach out to me if you need any help understanding the source, I've just gotten to the point where I can tell that the maintenance burden of this project is higher than I expected to take on when I wrote it.

This is a system for generating extern defs (tab-completion) in nu.

Note: This is not yet in a working state. Well, that is to say, it works fine if you're running Arch Linux, but testing on other distributions has immediately revealed that there are significant differences between distributions. We may need to start keeping track of patch-sets separately for each distribution, or perhaps switch to keeping track of the files themselves rather than a set of patches, or maybe both.

Background

The fish shell project has a long, complicated script for parsing man pages to gather completions definitions. Fortunately for us, Fish completions are defined in simple command line arguments, which we parse here and use to generate completions for Nu.

Installation and basic usage

Download and optionally install this script. For a prebuilt binary, use cargo-binstall...
```
cargo binstall nu-completion-script
```
...or if you don't have cargo-binstall, download the release from the releases page on Github.

You may also build from source using cargo install, or cloning the repository and building with cargo install. See Development Process for instructions.
Have fish installed.
From a fish shell, run
```
fish_update_completions
```

Generate the nu definitions.

nu-completions ~/.local/share/fish/generated_completions/*.fish

Source the definitions
```
nu-completions --install
```

Reporting bugs

If an error occurs, please run your command again with -vvvv, save the logs, and include them when submitting a Github Issue. For example, if an error occurs while running the above command to generate the definitions, run this command instead:

nu-completions -vvvv ~/.local/share/fish/generated_completions/*.fish | save log.json

And include the contents of log.json within a preformatted block, like this:

```json
{"level":30,"time":1677171831187,"msg":"beginning translation phase"}
{"level":30,"time":1677171831187,"msg":"processing file or directory","file":"../../../.local/share/fish/generated_completions/7z.fish"}
{"level":30,"time":1677171831187,"msg":"processing file","file":"../../../.local/share/fish/generated_completions/7z.fish"}
{"level":10,"time":1677171831187,"msg":"opened file for processing","file":"\"../../../.local/share/fish/generated_completions/7z.fish\""}

...

{"level":10,"time":1677171833182,"msg":"opened file for processing","file":"\"../../../.local/share/fish/generated_completions/java-openjdk8.fish\""}
{"level":50,"time":1677171833182,"msg":"error parsing shell words","line":"complete -c java-openjdk8 -o 'disablesystemassertions"}
{"level":50,"time":1677171833182,"msg":"failed to process completions at \"../../../.local/share/fish/generated_completions/java-openjdk8.fish\": missing closing quote"}
```

Development state

Since these definitions are auto-generated and incomplete, we need to modify the auto-generated output to provide additional application-specific functions to each definition. In order to provide a consistent workflow which smoothly (we hope) handles upstream man-page updates, these application-specific modifications take the form of a set of patches which are a part of this repository.

Development process

Note: These directions assume you're using Linux, and have git and cargo installed)

Fork this repository

Clone your fork and enter the directory

git clone https://github.com/YOUR-GITHUB-USER/nu-completions.git
cd nu-completions

Compile the binary
```
cargo build --release
```
Alternatively, install the latest release's prebuilt binary (requires cargo-binstall)...
```
cargo binstall nu-completion-script
```
...or if you don't have cargo-binstall, download the release from the releases page on Github.
Have fish installed.
From a fish shell, run
```
fish_update_completions
```