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## Summary
This PR introduces the `ruff_server` crate and a new `ruff server`
command. `ruff_server` is a re-implementation of
[`ruff-lsp`](https://github.com/astral-sh/ruff-lsp), written entirely in
Rust. It brings significant performance improvements, much tighter
integration with Ruff, a foundation for supporting entirely new language
server features, and more!
This PR is an early version of `ruff_lsp` that we're calling the
**pre-release** version. Anyone is more than welcome to use it and
submit bug reports for any issues they encounter - we'll have some
documentation on how to set it up with a few common editors, and we'll
also provide a pre-release VSCode extension for those interested.
This pre-release version supports:
- **Diagnostics for `.py` files**
- **Quick fixes**
- **Full-file formatting**
- **Range formatting**
- **Multiple workspace folders**
- **Automatic linter/formatter configuration** - taken from any
`pyproject.toml` files in the workspace.
Many thanks to @MichaReiser for his [proof-of-concept
work](https://github.com/astral-sh/ruff/pull/7262), which was important
groundwork for making this PR possible.
## Architectural Decisions
I've made an executive choice to go with `lsp-server` as a base
framework for the LSP, in favor of `tower-lsp`. There were several
reasons for this:
1. I would like to avoid `async` in our implementation. LSPs are mostly
computationally bound rather than I/O bound, and `async` adds a lot of
complexity to the API, while also making harder to reason about
execution order. This leads into the second reason, which is...
2. Any handlers that mutate state should be blocking and run in the
event loop, and the state should be lock-free. This is the approach that
`rust-analyzer` uses (also with the `lsp-server`/`lsp-types` crates as a
framework), and it gives us assurances about data mutation and execution
order. `tower-lsp` doesn't support this, which has caused some
[issues](https://github.com/ebkalderon/tower-lsp/issues/284) around data
races and out-of-order handler execution.
3. In general, I think it makes sense to have tight control over
scheduling and the specifics of our implementation, in exchange for a
slightly higher up-front cost of writing it ourselves. We'll be able to
fine-tune it to our needs and support future LSP features without
depending on an upstream maintainer.
## Test Plan
The pre-release of `ruff_server` will have snapshot tests for common
document editing scenarios. An expanded test suite is on the roadmap for
future version of `ruff_server`.
## Summary
This PR changes the `E3*` rules to respect the `isort`
`lines-after-imports` and `lines-between-types` settings. Specifically,
the following rules required changing
* `TooManyBlannkLines` : Respects both settings.
* `BlankLinesTopLevel`: Respects `lines-after-imports`. Doesn't need to
respect `lines-between-types` because it only applies to classes and
functions
The downside of this approach is that `isort` and the blank line rules
emit a diagnostic when there are too many blank lines. The fixes aren't
identical, the blank line is less opinionated, but blank lines accepts
the fix of `isort`.
<details>
<summary>Outdated approach</summary>
Fixes
https://github.com/astral-sh/ruff/issues/10077#issuecomment-1961266981
This PR changes the blank line rules to not enforce the number of blank
lines after imports (top-level) if isort is enabled and leave it to
isort to enforce the right number of lines (depends on the
`isort.lines-after-imports` and `isort.lines-between-types` settings).
The reason to give `isort` precedence over the blank line rules is that
they are configurable. Users that always want to blank lines after
imports can use `isort.lines-after-imports=2` to enforce that
(specifically for imports).
This PR does not fix the incompatibility with the formatter in pyi files
that only uses 0 to 1 blank lines. I'll address this separately.
</details>
## Review
The first commit is a small refactor that simplified implementing the
fix (and makes it easier to reason about what's mutable and what's not).
## Test Plan
I added a new test and verified that it fails with an error that the fix
never converges. I verified the snapshot output after implementing the
fix.
---------
Co-authored-by: Hoël Bagard <34478245+hoel-bagard@users.noreply.github.com>
## Summary
As a small quality-of-life improvement, the locator can now slice like
`locator.slice(stmt)` instead of requiring
`locator.slice(stmt.range())`.
## Test Plan
`cargo test`
## Summary
The motivation here is that this enables us to implement `Ranged` in
crates that don't depend on `ruff_python_ast`.
Largely a mechanical refactor with a lot of regex, Clippy help, and
manual fixups.
## Test Plan
`cargo test`
## Summary
If a file has a BOM, the import sorter _always_ reports the imports as
unsorted. The acute issue is that we detect that the line has leading
content (before the imports), which we always consider a violation.
Rather than fixing that one site, this PR instead makes `.line_start`
BOM-aware.
Fixes https://github.com/astral-sh/ruff/issues/6155.
