nushell/crates/nu-protocol
Leon 774769a7ad
color_config now accepts closures as color values (#7141)
# Description

Closes #6909. You can now add closures to your `color_config` themes.
Whenever a value would be printed with `table`, the closure is run with
the value piped-in. The closure must return either a {fg,bg,attr} record
or a color name (`'light_red'` etc.). This returned style is used to
colour the value.

This is entirely backwards-compatible with existing config.nu files.

Example code excerpt:
```
let my_theme = {
    header: green_bold
    bool: { if $in { 'light_cyan' } else { 'light_red' } }
    int: purple_bold
    filesize: { |e| if $e == 0b { 'gray' } else if $e < 1mb { 'purple_bold' } else { 'cyan_bold' } }
    duration: purple_bold
    date: { (date now) - $in | if $in > 1wk { 'cyan_bold' } else if $in > 1day { 'green_bold' } else { 'yellow_bold' } }
    range: yellow_bold
    string: { if $in =~ '^#\w{6}$' { $in } else { 'white' } }
    nothing: white
```
Example output with this in effect:
![2022-11-16 12 47 23 AM - style_computer
rs_-_nushell_-_VSCodium](https://user-images.githubusercontent.com/83939/201952558-482de05d-69c7-4bf2-91fc-d0964bf71264.png)
![2022-11-16 12 39 41 AM - style_computer
rs_-_nushell_-_VSCodium](https://user-images.githubusercontent.com/83939/201952580-2384bb86-b680-40fe-8192-71bae396c738.png)
![2022-11-15 09 21 54 PM - run_external
rs_-_nushell_-_VSCodium](https://user-images.githubusercontent.com/83939/201952601-343fc15d-e4a8-4a92-ad89-9a7d17d42748.png)

Slightly important notes:

* Some color_config names, namely "separator", "empty" and "hints", pipe
in `null` instead of a value.
* Currently, doing anything non-trivial inside a closure has an
understandably big perf hit. I currently do not actually recommend
something like `string: { if $in =~ '^#\w{6}$' { $in } else { 'white' }
}` for serious work, mainly because of the abundance of string-type data
in the world. Nevertheless, lesser-used types like "date" and "duration"
work well with this.
* I had to do some reorganisation in order to make it possible to call
`eval_block()` that late in table rendering. I invented a new struct
called "StyleComputer" which holds the engine_state and stack of the
initial `table` command (implicit or explicit).
* StyleComputer has a `compute()` method which takes a color_config name
and a nu value, and always returns the correct Style, so you don't have
to worry about A) the color_config value was set at all, B) whether it
was set to a closure or not, or C) which default style to use in those
cases.
* Currently, errors encountered during execution of the closures are
thrown in the garbage. Any other ideas are welcome. (Nonetheless, errors
result in a huge perf hit when they are encountered. I think what should
be done is to assume something terrible happened to the user's config
and invalidate the StyleComputer for that `table` run, thus causing
subsequent output to just be Style::default().)
* More thorough tests are forthcoming - ran into some difficulty using
`nu!` to take an alternative config, and for some reason `let-env config
=` statements don't seem to work inside `nu!` pipelines(???)
* The default config.nu has not been updated to make use of this yet. Do
tell if you think I should incorporate that into this.

# User-Facing Changes

See above.

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace --features=extra -- -D warnings -D
clippy::unwrap_used -A clippy::needless_collect` to check that you're
using the standard code style
- `cargo test --workspace --features=extra` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.
2022-12-17 07:07:56 -06:00
..
src color_config now accepts closures as color values (#7141) 2022-12-17 07:07:56 -06:00
tests $env.config now always holds a record with only valid values (#7309) 2022-12-10 15:34:46 +02:00
Cargo.toml Use nu-path correctly in nu! test macro to make dev-dependency transitive (#7488) 2022-12-15 18:53:26 +01:00
LICENSE Include license text in all crates (#5094) 2022-04-08 10:47:13 +02:00
README.md Add nu-protocol 2021-09-02 13:29:43 +12:00

nu-protocol

The nu-protocol crate holds the definitions of structs/traits that are used throughout Nushell. This gives us one way to expose them to many other crates, as well as make these definitions available to each other, without causing mutually recursive dependencies.