This commit should finish the `coloring_in_tokens` feature, which moves
the shape accumulator into the token stream. This allows rollbacks of
the token stream to also roll back any shapes that were added.
This commit also adds a much nicer syntax highlighter trace, which shows
all of the paths the highlighter took to arrive at a particular coloring
output. This change is fairly substantial, but really improves the
understandability of the flow. I intend to update the normal parser with
a similar tracing view.
In general, this change also fleshes out the concept of "atomic" token
stream operations.
A good next step would be to try to make the parser more
error-correcting, using the coloring infrastructure. A follow-up step
would involve merging the parser and highlighter shapes themselves.
This commit adds the ability to work on features behind a feature flag
that won't be included in normal builds of nu.
These features are not exposed as Cargo features, as they reflect
incomplete features that are not yet stable.
To create a feature, add it to `features.toml`:
```toml
[hintsv1]
description = "Adding hints based on error states in the highlighter"
enabled = false
```
Each feature in `features.toml` becomes a feature flag accessible to `cfg`:
```rs
println!("hintsv1 is enabled");
```
By default, features are enabled based on the value of the `enabled` field.
You can also enable a feature from the command line via the
`NUSHELL_ENABLE_FLAGS` environment variable:
```sh
$ NUSHELL_ENABLE_FLAGS=hintsv1 cargo run
```
You can enable all flags via `NUSHELL_ENABLE_ALL_FLAGS`.
This commit also updates the CI setup to run the build with all flags off and
with all flags on. It also extracts the linting test into its own
parallelizable test, which means it doesn't need to run together with every
other test anymore.
When working on a feature, you should also add tests behind the same flag. A
commit is mergable if all tests pass with and without the flag, allowing
incomplete commits to land on master as long as the incomplete code builds and
passes tests.
I'm gonna use a VecDeque now instead of trying to get async streams
working to make progress, but the intent is that we should be able to
use async streams in and out to interleave the work better.
