When there is a function or class definition at the end of a suite
followed by the beginning of an alternative block, we have to insert a
single empty line between them.
In the if-else-statement example below, we insert an empty line after
the `foo` in the if-block, but none after the else-block `foo`, since in
the latter case the enclosing suite already adds empty lines.
```python
if sys.version_info >= (3, 10):
def foo():
return "new"
else:
def foo():
return "old"
class Bar:
pass
```
To do so, we track whether the current suite is the last one in the
current statement with a new option on the suite kind.
Fixes#12199
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
## Summary
This PR updates the parser to remove building the `CommentRanges` and
instead it'll be built by the linter and the formatter when it's
required.
For the linter, it'll be built and owned by the `Indexer` while for the
formatter it'll be built from the `Tokens` struct and passed as an
argument.
## Test Plan
`cargo insta test`
## Summary
This PR updates the entire parser stack in multiple ways:
### Make the lexer lazy
* https://github.com/astral-sh/ruff/pull/11244
* https://github.com/astral-sh/ruff/pull/11473
Previously, Ruff's lexer would act as an iterator. The parser would
collect all the tokens in a vector first and then process the tokens to
create the syntax tree.
The first task in this project is to update the entire parsing flow to
make the lexer lazy. This includes the `Lexer`, `TokenSource`, and
`Parser`. For context, the `TokenSource` is a wrapper around the `Lexer`
to filter out the trivia tokens[^1]. Now, the parser will ask the token
source to get the next token and only then the lexer will continue and
emit the token. This means that the lexer needs to be aware of the
"current" token. When the `next_token` is called, the current token will
be updated with the newly lexed token.
The main motivation to make the lexer lazy is to allow re-lexing a token
in a different context. This is going to be really useful to make the
parser error resilience. For example, currently the emitted tokens
remains the same even if the parser can recover from an unclosed
parenthesis. This is important because the lexer emits a
`NonLogicalNewline` in parenthesized context while a normal `Newline` in
non-parenthesized context. This different kinds of newline is also used
to emit the indentation tokens which is important for the parser as it's
used to determine the start and end of a block.
Additionally, this allows us to implement the following functionalities:
1. Checkpoint - rewind infrastructure: The idea here is to create a
checkpoint and continue lexing. At a later point, this checkpoint can be
used to rewind the lexer back to the provided checkpoint.
2. Remove the `SoftKeywordTransformer` and instead use lookahead or
speculative parsing to determine whether a soft keyword is a keyword or
an identifier
3. Remove the `Tok` enum. The `Tok` enum represents the tokens emitted
by the lexer but it contains owned data which makes it expensive to
clone. The new `TokenKind` enum just represents the type of token which
is very cheap.
This brings up a question as to how will the parser get the owned value
which was stored on `Tok`. This will be solved by introducing a new
`TokenValue` enum which only contains a subset of token kinds which has
the owned value. This is stored on the lexer and is requested by the
parser when it wants to process the data. For example:
8196720f80/crates/ruff_python_parser/src/parser/expression.rs (L1260-L1262)
[^1]: Trivia tokens are `NonLogicalNewline` and `Comment`
### Remove `SoftKeywordTransformer`
* https://github.com/astral-sh/ruff/pull/11441
* https://github.com/astral-sh/ruff/pull/11459
* https://github.com/astral-sh/ruff/pull/11442
* https://github.com/astral-sh/ruff/pull/11443
* https://github.com/astral-sh/ruff/pull/11474
For context,
https://github.com/RustPython/RustPython/pull/4519/files#diff-5de40045e78e794aa5ab0b8aacf531aa477daf826d31ca129467703855408220
added support for soft keywords in the parser which uses infinite
lookahead to classify a soft keyword as a keyword or an identifier. This
is a brilliant idea as it basically wraps the existing Lexer and works
on top of it which means that the logic for lexing and re-lexing a soft
keyword remains separate. The change here is to remove
`SoftKeywordTransformer` and let the parser determine this based on
context, lookahead and speculative parsing.
* **Context:** The transformer needs to know the position of the lexer
between it being at a statement position or a simple statement position.
This is because a `match` token starts a compound statement while a
`type` token starts a simple statement. **The parser already knows
this.**
* **Lookahead:** Now that the parser knows the context it can perform
lookahead of up to two tokens to classify the soft keyword. The logic
for this is mentioned in the PR implementing it for `type` and `match
soft keyword.
* **Speculative parsing:** This is where the checkpoint - rewind
infrastructure helps. For `match` soft keyword, there are certain cases
for which we can't classify based on lookahead. The idea here is to
create a checkpoint and keep parsing. Based on whether the parsing was
successful and what tokens are ahead we can classify the remaining
cases. Refer to #11443 for more details.
If the soft keyword is being parsed in an identifier context, it'll be
converted to an identifier and the emitted token will be updated as
well. Refer
8196720f80/crates/ruff_python_parser/src/parser/expression.rs (L487-L491).
The `case` soft keyword doesn't require any special handling because
it'll be a keyword only in the context of a match statement.
### Update the parser API
* https://github.com/astral-sh/ruff/pull/11494
* https://github.com/astral-sh/ruff/pull/11505
Now that the lexer is in sync with the parser, and the parser helps to
determine whether a soft keyword is a keyword or an identifier, the
lexer cannot be used on its own. The reason being that it's not
sensitive to the context (which is correct). This means that the parser
API needs to be updated to not allow any access to the lexer.
Previously, there were multiple ways to parse the source code:
1. Passing the source code itself
2. Or, passing the tokens
Now that the lexer and parser are working together, the API
corresponding to (2) cannot exists. The final API is mentioned in this
PR description: https://github.com/astral-sh/ruff/pull/11494.
### Refactor the downstream tools (linter and formatter)
* https://github.com/astral-sh/ruff/pull/11511
* https://github.com/astral-sh/ruff/pull/11515
* https://github.com/astral-sh/ruff/pull/11529
* https://github.com/astral-sh/ruff/pull/11562
* https://github.com/astral-sh/ruff/pull/11592
And, the final set of changes involves updating all references of the
lexer and `Tok` enum. This was done in two-parts:
1. Update all the references in a way that doesn't require any changes
from this PR i.e., it can be done independently
* https://github.com/astral-sh/ruff/pull/11402
* https://github.com/astral-sh/ruff/pull/11406
* https://github.com/astral-sh/ruff/pull/11418
* https://github.com/astral-sh/ruff/pull/11419
* https://github.com/astral-sh/ruff/pull/11420
* https://github.com/astral-sh/ruff/pull/11424
2. Update all the remaining references to use the changes made in this
PR
For (2), there were various strategies used:
1. Introduce a new `Tokens` struct which wraps the token vector and add
methods to query a certain subset of tokens. These includes:
1. `up_to_first_unknown` which replaces the `tokenize` function
2. `in_range` and `after` which replaces the `lex_starts_at` function
where the former returns the tokens within the given range while the
latter returns all the tokens after the given offset
2. Introduce a new `TokenFlags` which is a set of flags to query certain
information from a token. Currently, this information is only limited to
any string type token but can be expanded to include other information
in the future as needed. https://github.com/astral-sh/ruff/pull/11578
3. Move the `CommentRanges` to the parsed output because this
information is common to both the linter and the formatter. This removes
the need for `tokens_and_ranges` function.
## Test Plan
- [x] Update and verify the test snapshots
- [x] Make sure the entire test suite is passing
- [x] Make sure there are no changes in the ecosystem checks
- [x] Run the fuzzer on the parser
- [x] Run this change on dozens of open-source projects
### Running this change on dozens of open-source projects
Refer to the PR description to get the list of open source projects used
for testing.
Now, the following tests were done between `main` and this branch:
1. Compare the output of `--select=E999` (syntax errors)
2. Compare the output of default rule selection
3. Compare the output of `--select=ALL`
**Conclusion: all output were same**
## What's next?
The next step is to introduce re-lexing logic and update the parser to
feed the recovery information to the lexer so that it can emit the
correct token. This moves us one step closer to having error resilience
in the parser and provides Ruff the possibility to lint even if the
source code contains syntax errors.
## Summary
This PR implements the `blank_line_after_nested_stub_class` preview
style in the formatter.
The logic is divided into 3 parts:
1. In between preceding and following nodes at top level and nested
suite
2. When there's a trailing comment after the class
3. When there is no following node from (1) which is the case when it's
the last or the only node in a suite
We handle (3) with `FormatLeadingAlternateBranchComments`.
## Test Plan
- Add new test cases and update existing snapshots
- Checked the `typeshed` diff
fixes: #8891
## Summary
I always found it odd that we had to pass this in, since it's really
higher-level context for the error. The awkwardness is further evidenced
by the fact that we pass in fake values everywhere (even outside of
tests). The source path isn't actually used to display the error; it's
only accessed elsewhere to _re-display_ the error in certain cases. This
PR modifies to instead pass the path directly in those cases.
This PR splits the string formatting code in the formatter to be handled
by the respective nodes.
Previously, the string formatting was done through a single
`FormatString` interface. Now, the nodes themselves are responsible for
formatting.
The following changes were made:
1. Remove `StringLayout::ImplicitStringConcatenationInBinaryLike` and
inline the call to `FormatStringContinuation`. After the refactor, the
binary like formatting would delegate to `FormatString` which would then
delegate to `FormatStringContinuation`. This removes the intermediary
steps.
2. Add formatter implementation for `FStringPart` which delegates it to
the respective string literal or f-string node.
3. Add `ExprStringLiteralKind` which is either `String` or `Docstring`.
If it's a docstring variant, then the string expression would not be
implicitly concatenated. This is guaranteed by the
`DocstringStmt::try_from_expression` constructor.
4. Add `StringLiteralKind` which is either a `String`, `Docstring` or
`InImplicitlyConcatenatedFString`. The last variant is for when the
string literal is implicitly concatenated with an f-string (`"foo" f"bar
{x}"`).
5. Remove `FormatString`.
6. Extract the f-string quote detection as a standalone function which
is public to the crate. This is used to detect the quote to be used for
an f-string at the expression level (`ExprFString` or
`FormatStringContinuation`).
### Formatter ecosystem result
**This PR**
| project | similarity index | total files | changed files |
|----------------|------------------:|------------------:|------------------:|
| cpython | 0.75804 | 1799 | 1648 |
| django | 0.99984 | 2772 | 34 |
| home-assistant | 0.99955 | 10596 | 214 |
| poetry | 0.99905 | 321 | 15 |
| transformers | 0.99967 | 2657 | 324 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99980 | 3669 | 18 |
| warehouse | 0.99976 | 654 | 14 |
| zulip | 0.99958 | 1459 | 36 |
**main**
| project | similarity index | total files | changed files |
|----------------|------------------:|------------------:|------------------:|
| cpython | 0.75804 | 1799 | 1648 |
| django | 0.99984 | 2772 | 34 |
| home-assistant | 0.99955 | 10596 | 214 |
| poetry | 0.99905 | 321 | 15 |
| transformers | 0.99967 | 2657 | 324 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99980 | 3669 | 18 |
| warehouse | 0.99976 | 654 | 14 |
| zulip | 0.99958 | 1459 | 36 |
## Summary
This PR changes the internal `docstring-code-line-width` setting to
additionally accept a string value `dynamic`. When `dynamic` is set, the
line width is dynamically adjusted when reformatting code snippets in
docstrings based on the indent level of the docstring. The result is
that the reformatted lines from the code snippet should not exceed the
"global" line width configuration for the surrounding source.
This PR does not change the default behavior, although I suspect the
default should probably be `dynamic`.
## Test Plan
I added a new configuration to the existing docstring code tests and
also added a new set of tests dedicated to the new `dynamic` mode.
## Summary
We should avoid inlining the ellipsis in:
```python
def h():
...
# bye
```
Just as we omit the ellipsis in:
```python
def h():
# bye
...
```
Closes https://github.com/astral-sh/ruff/issues/8905.
## Summary
This PR updates the string nodes (`ExprStringLiteral`,
`ExprBytesLiteral`, and `ExprFString`) to account for implicit string
concatenation.
### Motivation
In Python, implicit string concatenation are joined while parsing
because the interpreter doesn't require the information for each part.
While that's feasible for an interpreter, it falls short for a static
analysis tool where having such information is more useful. Currently,
various parts of the code uses the lexer to get the individual string
parts.
One of the main challenge this solves is that of string formatting.
Currently, the formatter relies on the lexer to get the individual
string parts, and formats them including the comments accordingly. But,
with PEP 701, f-string can also contain comments. Without this change,
it becomes very difficult to add support for f-string formatting.
### Implementation
The initial proposal was made in this discussion:
https://github.com/astral-sh/ruff/discussions/6183#discussioncomment-6591993.
There were various AST designs which were explored for this task which
are available in the linked internal document[^1].
The selected variant was the one where the nodes were kept as it is
except that the `implicit_concatenated` field was removed and instead a
new struct was added to the `Expr*` struct. This would be a private
struct would contain the actual implementation of how the AST is
designed for both single and implicitly concatenated strings.
This implementation is achieved through an enum with two variants:
`Single` and `Concatenated` to avoid allocating a vector even for single
strings. There are various public methods available on the value struct
to query certain information regarding the node.
The nodes are structured in the following way:
```
ExprStringLiteral - "foo" "bar"
|- StringLiteral - "foo"
|- StringLiteral - "bar"
ExprBytesLiteral - b"foo" b"bar"
|- BytesLiteral - b"foo"
|- BytesLiteral - b"bar"
ExprFString - "foo" f"bar {x}"
|- FStringPart::Literal - "foo"
|- FStringPart::FString - f"bar {x}"
|- StringLiteral - "bar "
|- FormattedValue - "x"
```
[^1]: Internal document:
https://www.notion.so/astral-sh/Implicit-String-Concatenation-e036345dc48943f89e416c087bf6f6d9?pvs=4
#### Visitor
The way the nodes are structured is that the entire string, including
all the parts that are implicitly concatenation, is a single node
containing individual nodes for the parts. The previous section has a
representation of that tree for all the string nodes. This means that
new visitor methods are added to visit the individual parts of string,
bytes, and f-strings for `Visitor`, `PreorderVisitor`, and
`Transformer`.
## Test Plan
- `cargo insta test --workspace --all-features --unreferenced reject`
- Verify that the ecosystem results are unchanged
Update to [Rust
1.74](https://blog.rust-lang.org/2023/11/16/Rust-1.74.0.html) and use
the new clippy lints table.
The update itself introduced a new clippy lint about superfluous hashes
in raw strings, which got removed.
I moved our lint config from `rustflags` to the newly stabilized
[workspace.lints](https://doc.rust-lang.org/stable/cargo/reference/workspaces.html#the-lints-table).
One consequence is that we have to `unsafe_code = "warn"` instead of
"forbid" because the latter now actually bans unsafe code:
```
error[E0453]: allow(unsafe_code) incompatible with previous forbid
--> crates/ruff_source_file/src/newlines.rs:62:17
|
62 | #[allow(unsafe_code)]
| ^^^^^^^^^^^ overruled by previous forbid
|
= note: `forbid` lint level was set on command line
```
---------
Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>
## Summary
This PR updates the formatter to preserve trailing semicolon for Jupyter
Notebooks.
The motivation behind the change is that semicolons in notebooks are
typically used to hide the output, for example when plotting. This is
highlighted in the linked issue.
The conditions required as to when the trailing semicolon should be
preserved are:
1. It should be a top-level statement which is last in the module.
2. For statement, it can be either assignment, annotated assignment, or
augmented assignment. Here, the target should only be a single
identifier i.e., multiple assignments or tuple unpacking isn't
considered.
3. For expression, it can be any.
## Test Plan
Add a new integration test in `ruff_cli`. The test notebook basically
acts as a document as to which trailing semicolons are to be preserved.
fixes: #8254
**Summary** Previously, own line comment following after a docstring
followed by newline(s) before the first content statement were treated
as trailing on the docstring and we didn't insert a newline after the
docstring as black would.
Before:
```python
class ModuleBrowser:
"""Browse module classes and functions in IDLE."""
# This class is also the base class for pathbrowser.PathBrowser.
def __init__(self, master, path, *, _htest=False, _utest=False):
pass
```
After:
```python
class ModuleBrowser:
"""Browse module classes and functions in IDLE."""
# This class is also the base class for pathbrowser.PathBrowser.
def __init__(self, master, path, *, _htest=False, _utest=False):
pass
```
I'm not entirely happy about hijacking
`handle_own_line_comment_between_statements`, but i don't know a better
spot to put it.
Fixes#7948
**Test Plan** Fixtures
We previously incorrectly treated byte strings in docstring position as
docstrings because black does so
(https://github.com/astral-sh/ruff/pull/8283#discussion_r1375682931,
https://github.com/psf/black/issues/4002), even CPython doesn't
recognize them:
```console
$ python3.12
Python 3.12.0 (main, Oct 6 2023, 17:57:44) [GCC 11.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> def f():
... b""" a"""
...
>>> print(str(f.__doc__))
None
```
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## Summary
This PR splits the `Constant` enum as individual literal nodes. It
introduces the following new nodes for each variant:
* `ExprStringLiteral`
* `ExprBytesLiteral`
* `ExprNumberLiteral`
* `ExprBooleanLiteral`
* `ExprNoneLiteral`
* `ExprEllipsisLiteral`
The main motivation behind this refactor is to introduce the new AST
node for implicit string concatenation in the coming PR. The elements of
that node will be either a string literal, bytes literal or a f-string
which can be implemented using an enum. This means that a string or
bytes literal cannot be represented by `Constant::Str` /
`Constant::Bytes` which creates an inconsistency.
This PR avoids that inconsistency by splitting the constant nodes into
it's own literal nodes, literal being the more appropriate naming
convention from a static analysis tool perspective.
This also makes working with literals in the linter and formatter much
more ergonomic like, for example, if one would want to check if this is
a string literal, it can be done easily using
`Expr::is_string_literal_expr` or matching against `Expr::StringLiteral`
as oppose to matching against the `ExprConstant` and enum `Constant`. A
few AST helper methods can be simplified as well which will be done in a
follow-up PR.
This introduces a new `Expr::is_literal_expr` method which is the same
as `Expr::is_constant_expr`. There are also intermediary changes related
to implicit string concatenation which are quiet less. This is done so
as to avoid having a huge PR which this already is.
## Test Plan
1. Verify and update all of the existing snapshots (parser, visitor)
2. Verify that the ecosystem check output remains **unchanged** for both
the linter and formatter
### Formatter ecosystem check
#### `main`
| project | similarity index | total files | changed files |
|----------------|------------------:|------------------:|------------------:|
| cpython | 0.75803 | 1799 | 1647 |
| django | 0.99983 | 2772 | 34 |
| home-assistant | 0.99953 | 10596 | 186 |
| poetry | 0.99891 | 317 | 17 |
| transformers | 0.99966 | 2657 | 330 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99978 | 3669 | 20 |
| warehouse | 0.99977 | 654 | 13 |
| zulip | 0.99970 | 1459 | 22 |
#### `dhruv/constant-to-literal`
| project | similarity index | total files | changed files |
|----------------|------------------:|------------------:|------------------:|
| cpython | 0.75803 | 1799 | 1647 |
| django | 0.99983 | 2772 | 34 |
| home-assistant | 0.99953 | 10596 | 186 |
| poetry | 0.99891 | 317 | 17 |
| transformers | 0.99966 | 2657 | 330 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99978 | 3669 | 20 |
| warehouse | 0.99977 | 654 | 13 |
| zulip | 0.99970 | 1459 | 22 |
Change
```python
"""Test docstring"""
a = 1
```
to
```python
"""Test docstring"""
a = 1
```
in preview style, but don't touch the docstring otherwise.
Do we want to ask black to also format the content of module level
docstrings? Seems inconsistent to me that we change function and class
docstring indentation/contents but not module docstrings.
Fixes https://github.com/astral-sh/ruff/issues/7995
**Summary** Insert a newline after nested function and class
definitions, unless there is a trailing own line comment.
We need to e.g. format
```python
if platform.system() == "Linux":
if sys.version > (3, 10):
def f():
print("old")
else:
def f():
print("new")
f()
```
as
```python
if platform.system() == "Linux":
if sys.version > (3, 10):
def f():
print("old")
else:
def f():
print("new")
f()
```
even though `f()` is directly preceded by an if statement, not a
function or class definition. See the comments and fixtures for trailing
own line comment handling.
**Test Plan** I checked that the new content of `newlines.py` matches
black's formatting.
---------
Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>
## Summary
Given:
```python
if True:
if True:
pass
else:
pass
# a
# b
# c
else:
pass
```
We want to preserve the newline after the `# c` (before the `else`).
However, the `last_node` ends at the `pass`, and the comments are
trailing comments on the `pass`, not trailing comments on the
`last_node` (the `if`). As such, when counting the trailing newlines on
the outer `if`, we abort as soon as we see the comment (`# a`).
This PR changes the logic to skip _all_ comments (even those with
newlines between them). This is safe as we know that there are no
"leading" comments on the `else`, so there's no risk of skipping those
accidentally.
Closes https://github.com/astral-sh/ruff/issues/7602.
## Test Plan
No change in compatibility.
Before:
| project | similarity index | total files | changed files |
|--------------|------------------:|------------------:|------------------:|
| cpython | 0.76083 | 1789 | 1631 |
| django | 0.99983 | 2760 | 36 |
| transformers | 0.99963 | 2587 | 319 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99979 | 3496 | 22 |
| warehouse | 0.99967 | 648 | 15 |
| zulip | 0.99972 | 1437 | 21 |
After:
| project | similarity index | total files | changed files |
|--------------|------------------:|------------------:|------------------:|
| cpython | 0.76083 | 1789 | 1631 |
| django | 0.99983 | 2760 | 36 |
| transformers | 0.99963 | 2587 | 319 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99983 | 3496 | 18 |
| warehouse | 0.99967 | 648 | 15 |
| zulip | 0.99972 | 1437 | 21 |
## Summary
Given:
```python
# -*- coding: utf-8 -*-
import random
# Defaults for arguments are defined here
# args.threshold = None;
logger = logging.getLogger("FastProject")
```
We want to count the number of newlines after `import random`, to ensure
that there's _at least one_, but up to two.
Previously, we used the end range of the statement (then skipped
trivia); instead, we need to use the end of the _last comment_. This is
similar to #7556.
Closes https://github.com/astral-sh/ruff/issues/7604.
## Summary
The tokenizer was split into a forward and a backwards tokenizer. The
backwards tokenizer uses the same names as the forwards ones (e.g.
`next_token`). The backwards tokenizer gets the comment ranges that we
already built to skip comments.
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
## Summary
Fix all but one empty line differences with the black preview style in
typeshed. The remaining differences are breaking with type comments and
trailing commas in function definitions.
I compared the empty line differences with the preview mode of black
since stable has some oddities that would have been hard to replicate
(https://github.com/psf/black/issues/3861). Additionally, it assumes the
style proposed in https://github.com/psf/black/issues/3862.
An edge case that also surfaced with typeshed are newline before
trailing module comments.
**main**
| project | similarity index | total files | changed files |
|--------------|------------------:|------------------:|------------------:|
| cpython | 0.76083 | 1789 | 1632 |
| django | 0.99966 | 2760 | 58 |
| transformers | 0.99930 | 2587 | 447 |
| twine | 1.00000 | 33 | 0 |
| **typeshed** | 0.99978 | 3496 | **2173** |
| warehouse | 0.99825 | 648 | 22 |
| zulip | 0.99950 | 1437 | 27 |
**PR**
| project | similarity index | total files | changed files |
|--------------|------------------:|------------------:|------------------:|
| cpython | 0.76083 | 1789 | 1632 |
| django | 0.99966 | 2760 | 58 |
| transformers | 0.99930 | 2587 | 447 |
| twine | 1.00000 | 33 | 0 |
| **typeshed** | 0.99983 | 3496 | **18** |
| warehouse | 0.99825 | 648 | 22 |
| zulip | 0.99950 | 1437 | 27 |
Closes#6723
## Test Plan
The main driver was the typeshed diff. I added new test cases for all
kinds of possible empty line combinations in stub files, test cases for
newlines before trailing module comments.
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
## Summary
This PR modifies our between-statement comment handling such that
comments that are not separated by a statement by any newlines continue
to be treated as leading comments on the statement, but comments that
_are_ separated are instead formatted as trailing comments on the
preceding statement.
See, e.g., the originating snippet:
```python
DEFAULT_TEMPLATE = "flatpages/default.html"
# This view is called from FlatpageFallbackMiddleware.process_response
# when a 404 is raised, which often means CsrfViewMiddleware.process_view
# has not been called even if CsrfViewMiddleware is installed. So we need
# to use @csrf_protect, in case the template needs {% csrf_token %}.
# However, we can't just wrap this view; if no matching flatpage exists,
# or a redirect is required for authentication, the 404 needs to be returned
# without any CSRF checks. Therefore, we only
# CSRF protect the internal implementation.
def flatpage(request, url):
pass
```
Here, we need to ensure that the `def flatpage` is precede by two empty
lines. However, we want those two empty lines to be enforced from the
_end_ of the comment block, _unless_ the comments are directly atop the
`def flatpage`.
I played with this a bit, and I think the simplest conceptual model and
implementation is to instead treat those as trailing comments on the
preceding node. The main difficulty with this approach is that, in order
to be fully compatible with Black, we'd sometimes need to insert
newlines _between_ the preceding node and its trailing comments. See,
e.g.:
```python
def func():
...
# comment
x = 1
```
In this case, we'd need to insert two blank lines between `def func():
...` and `# comment`, but `# comment` is trailing comment on `def
func(): ...`. So, we'd need to take this case into account in the
various nodes that _require_ newlines after them: functions, classes,
and imports. After some discussion, we've opted _not_ to support this,
and just treat these as trailing comments -- so we won't insert newlines
there. This means our handling is still identical to Black's on
Black-formatted code, but avoids moving such trailing comments on
unformatted code.
I dislike that the empty handling is so complex, and that it's split
between so many different nodes, but this is really tricky. Continuing
to treat these as leading comments is very difficult too, since we'd
need to do similar tricks for the leading comment handling in those
nodes, and influencing leading comments is even harder, since they're
all formatted _before_ the node itself.
Closes https://github.com/astral-sh/ruff/issues/6761.
## Test Plan
`cargo test`
Surprisingly, it doesn't change the similarity at all (apart from a
0.00001 change in CPython), but I manually confirmed that it did fix the
originating issue in Django.
Before:
| project | similarity index |
|--------------|------------------|
| cpython | 0.76082 |
| django | 0.99921 |
| transformers | 0.99854 |
| twine | 0.99982 |
| typeshed | 0.99953 |
| warehouse | 0.99648 |
| zulip | 0.99928 |
After:
| project | similarity index |
|--------------|------------------|
| cpython | 0.76081 |
| django | 0.99921 |
| transformers | 0.99854 |
| twine | 0.99982 |
| typeshed | 0.99953 |
| warehouse | 0.99648 |
| zulip | 0.99928 |
## 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
For imports, we enforce that there's _at least_ one empty line after an
import (assuming the next statement is _not_ an import), but allow up to
two at the module level.
Closes https://github.com/astral-sh/ruff/issues/6760.
## Test Plan
`cargo test`
Avoid the nesting in a macro by using the new `WithNodeLevel` to
`PyFormatter` deref. No changes otherwise.
I wanted to follow this up with quickly fixing the typeshed empty line
rules but they turned out a lot more complex than i had anticipated.
## Summary
We're using LibCST to ensure that we return the full parenthesized range
of an expression, for display purposes. We can just use
`parenthesized_range` which is more efficient and removes one LibCST
dependency.
## Test Plan
`cargo test`
## Summary
In https://github.com/astral-sh/ruff/pull/6512, we added a flag to the
AST to mark implicitly-concatenated string expressions. This PR makes
use of that flag to remove the `is_implicit_concatenation` method.
## Test Plan
`cargo test`
