## Summary
The problem: given a (row, column) number (e.g., for a token in the AST), we need to be able to map it to a precise byte index in the source code. A while ago, we moved to `ropey` for this, since it was faster in practice (mostly, I think, because it's able to defer indexing). However, at some threshold of accesses, it becomes faster to index the string in advance, as we're doing here.
## Benchmark
It looks like this is ~3.6% slower for the default rule set, but ~9.3% faster for `--select ALL`.
**I suspect there's a strategy that would be strictly faster in both cases**, based on deferring even more computation (right now, we lazily compute these offsets, but we do it for the entire file at once, even if we only need some slice at the top), or caching the `ropey` lookups in some way.
Before:
After:
## Alternatives
I tried tweaking the `Vec::with_capacity` hints, and even trying `Vec::with_capacity(str_indices::lines_crlf::count_breaks(contents))` to do a quick scan of the number of lines, but that turned out to be slower.
Add tests.
Ensure that these cases are caught by ICN001:
```python
from xml.dom import minidom
from xml.dom.minidom import parseString
```
with config:
```toml
[tool.ruff.flake8-import-conventions.extend-aliases]
"dask.dataframe" = "dd"
"xml.dom.minidom" = "md"
"xml.dom.minidom.parseString" = "pstr"
```
The idea is the same as #1867. Avoids emitting `SIM102` twice for the following code:
```python
if a:
if b:
if c:
d
```
```
resources/test/fixtures/flake8_simplify/SIM102.py:1:1: SIM102 Use a single `if` statement instead of nested `if` statements
resources/test/fixtures/flake8_simplify/SIM102.py:2:5: SIM102 Use a single `if` statement instead of nested `if` statements
```
This PR adds the scaffolding files for `flake8-type-checking`, along with the simplest rule (`empty-type-checking-block`), just as an example to get us started.
See: #1785.
Tracking issue: https://github.com/charliermarsh/ruff/issues/2024
Implementation for EXE003, EXE004 and EXE005 of `flake8-executable`
(shebang should contain "python", not have whitespace before, and should be on the first line)
Please take in mind that this is my first rust contribution.
The remaining EXE-rules are a combination of shebang (`lines.rs`), file permissions (`fs.rs`) and if-conditions (`ast.rs`). I was not able to find other rules that have interactions/dependencies in them. Any advice on how this can be best implemented would be very welcome.
For autofixing `EXE005`, I had in mind to _move_ the shebang line to the top op the file. This could be achieved by a combination of `Fix::insert` and `Fix::delete` (multiple fixes per diagnostic), or by implementing a dedicated `Fix::move`, or perhaps in other ways. For now I've left it out, but keen on hearing what you think would be most consistent with the package, and pointer where to start (if at all).
---
If you care about another testimonial:
`ruff` not only helps staying on top of the many excellent flake8 plugins and other Python code quality tools that are available, it also applies them at baffling speed.
(Planning to implement it soon for github.com/pandas-profiling/pandas-profiling (as largest contributor) and github.com/ing-bank/popmon.)
Rule described here: https://www.flake8rules.com/rules/E101.html
I tried to follow contributing guidelines closely, I've never worked with Rust before. Stumbled across Ruff a few days ago and would like to use it in our project, but we use a bunch of flake8 rules that are not yet implemented in ruff, so I decided to give it a go.
For now, we're just gonna avoid flagging this for `elif` blocks, following the same reasoning as for ternaries. We can handle all of these cases, but we'll knock out the TODOs as a pair, and this avoids broken code.
Closes#2007.
This PR adds a new check that turns expressions such as `[1, 2, 3] + foo` into `[1, 2, 3, *foo]`, since the latter is easier to read and faster:
```
~ $ python3.11 -m timeit -s 'b = [6, 5, 4]' '[1, 2, 3] + b'
5000000 loops, best of 5: 81.4 nsec per loop
~ $ python3.11 -m timeit -s 'b = [6, 5, 4]' '[1, 2, 3, *b]'
5000000 loops, best of 5: 66.2 nsec per loop
```
However there's a couple of gotchas:
* This felt like a `simplify` rule, so I borrowed an unused `SIM` code even if the upstream `flake8-simplify` doesn't do this transform. If it should be assigned some other code, let me know 😄
* **More importantly** this transform could be unsafe if the other operand of the `+` operation has overridden `__add__` to do something else. What's the `ruff` policy around potentially unsafe operations? (I think some of the suggestions other ported rules give could be semantically different from the original code, but I'm not sure.)
* I'm not a very established Rustacean, so there's no doubt my code isn't quite idiomatic. (For instance, is there a neater way to write that four-way `match` statement?)
Thanks for `ruff`, by the way! :)
This is slightly buggy due to Instagram/LibCST#855; it will complain `[ERROR] Failed to fix nested with: Failed to extract CST from source` when trying to fix nested parenthesized `with` statements lacking trailing commas. But presumably people who write parenthesized `with` statements already knew that they don’t need to nest them.
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
If a `try` block has multiple statements, a compound statement, or
control flow, rewriting it with `contextlib.suppress` would obfuscate
the fact that the exception still short-circuits further statements in
the block.
Fixes#1947.
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
Since our binding tracking is somewhat limited, I opted to favor false negatives over false positives. So, e.g., this won't trigger SIM115:
```py
with contextlib.ExitStack():
f = exit_stack.enter_context(open("filename"))
```
(Notice that `exit_stack` is unbound.)
The alternative strategy required us to incorrectly trigger SIM115 on this:
```py
with contextlib.ExitStack() as exit_stack:
exit_stack_ = exit_stack
f = exit_stack_.enter_context(open("filename"))
```
Closes#1945.
I accept any suggestion. By the way, I have a doubt, I have checked and all flake8-pie plugins can be fixed by ruff, but is it necessary that this one is also fixed automatically ?
rel #1543
Implements [flake8-commas](https://github.com/PyCQA/flake8-commas). Fixes#1058.
The plugin is mostly redundant with Black (and also deprecated upstream), but very useful for projects which can't/won't use an auto-formatter.
This linter works on tokens. Before porting to Rust, I cleaned up the Python code ([link](https://gist.github.com/bluetech/7c5dcbdec4a73dd5a74d4bc09c72b8b9)) and made sure the tests pass. In the Rust version I tried to add explanatory comments, to the best of my understanding of the original logic.
Some changes I did make:
- Got rid of rule C814 - "missing trailing comma in Python 2". Ruff doesn't support Python 2.
- Merged rules C815 - "missing trailing comma in Python 3.5+" and C816 - "missing trailing comma in Python 3.6+" into C812 - "missing trailing comma". These Python versions are outdated, didn't think it was worth the complication.
- Added autofixes for C812 and C819.
Autofix is missing for C818 - "trailing comma on bare tuple prohibited". It needs to turn e.g. `x = 1,` into `x = (1, )`, it's a bit difficult to do with tokens only, so I skipped it for now.
I ran the rules on cpython/Lib and on a big internal code base and it works as intended (though I only sampled the diffs).
