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 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 fixes the bug where the formatter would format an f-string and
could potentially change the AST.
For a triple-quoted f-string, the element can't be formatted into
multiline if it has a format specifier because otherwise the newline
would be treated as part of the format specifier.
Given the following f-string:
```python
f"""aaaaaaaaaaaaaaaa bbbbbbbbbbbbbbbbbb ccccccccccc {
variable:.3f} ddddddddddddddd eeeeeeee"""
```
The formatter sees that the f-string is already multiline so it assumes
that it can contain line breaks i.e., broken into multiple lines. But,
in this specific case we can't format it as:
```python
f"""aaaaaaaaaaaaaaaa bbbbbbbbbbbbbbbbbb ccccccccccc {
variable:.3f
} ddddddddddddddd eeeeeeee"""
```
Because the format specifier string would become ".3f\n", which is not
the original string (`.3f`).
If the original source code already contained a newline, they'll be
preserved. For example:
```python
f"""aaaaaaaaaaaaaaaa bbbbbbbbbbbbbbbbbb ccccccccccc {
variable:.3f
} ddddddddddddddd eeeeeeee"""
```
The above will be formatted as:
```py
f"""aaaaaaaaaaaaaaaa bbbbbbbbbbbbbbbbbb ccccccccccc {variable:.3f
} ddddddddddddddd eeeeeeee"""
```
Note that the newline after `.3f` is part of the format specifier which
needs to be preserved.
The Python version is irrelevant in this case.
fixes: #10040
## Test Plan
Add some test cases to verify this behavior.
(Supersedes #9152, authored by @LaBatata101)
## Summary
This PR replaces the current parser generated from LALRPOP to a
hand-written recursive descent parser.
It also updates the grammar for [PEP
646](https://peps.python.org/pep-0646/) so that the parser outputs the
correct AST. For example, in `data[*x]`, the index expression is now a
tuple with a single starred expression instead of just a starred
expression.
Beyond the performance improvements, the parser is also error resilient
and can provide better error messages. The behavior as seen by any
downstream tools isn't changed. That is, the linter and formatter can
still assume that the parser will _stop_ at the first syntax error. This
will be updated in the following months.
For more details about the change here, refer to the PR corresponding to
the individual commits and the release blog post.
## Test Plan
Write _lots_ and _lots_ of tests for both valid and invalid syntax and
verify the output.
## Acknowledgements
- @MichaReiser for reviewing 100+ parser PRs and continuously providing
guidance throughout the project
- @LaBatata101 for initiating the transition to a hand-written parser in
#9152
- @addisoncrump for implementing the fuzzer which helped
[catch](https://github.com/astral-sh/ruff/pull/10903)
[a](https://github.com/astral-sh/ruff/pull/10910)
[lot](https://github.com/astral-sh/ruff/pull/10966)
[of](https://github.com/astral-sh/ruff/pull/10896)
[bugs](https://github.com/astral-sh/ruff/pull/10877)
---------
Co-authored-by: Victor Hugo Gomes <labatata101@linuxmail.org>
Co-authored-by: Micha Reiser <micha@reiser.io>
## Summary
This is a follow up on https://github.com/astral-sh/ruff/pull/10492
I incorrectly assumed that `subscript.value.end()` always points past
the value. However, this isn't the case for parenthesized values where
the end "ends" before the parentheses.
## Test Plan
I added new tests for the parenthesized case.
## Summary
This PR fixes an instability where formatting a subscribt
where the `slice` is not an `ExprSlice` and it has a trailing
end-of-line comment after its opening `[` required two formatting passes
to be stable.
The fix is to associate the trailing end-of-line comment as dangling
comment on `[` to preserve its position, similar to how Ruff does it for
other parenthesized expressions.
This also matches how trailing end-of-line subscript comments are
handled when the `slice` is an `ExprSlice`.
Fixes https://github.com/astral-sh/ruff/issues/10355
## Versioning
Shipping this as part of a patch release is fine because:
* It fixes a stability issue
* It doesn't impact already formatted code because Ruff would already
have moved to the comment to the end of the line (instead of preserving
it)
## Test Plan
Added tests
## Summary
I used `codespell` and `gramma` to identify mispellings and grammar
errors throughout the codebase and fixed them. I tried not to make any
controversial changes, but feel free to revert as you see fit.
## Summary
This PR changes how we format `with` statements with a single with item
for Python 3.8 or older. This change is not compatible with Black.
This is how we format a single-item with statement today
```python
def run(data_path, model_uri):
with pyspark.sql.SparkSession.builder.config(
key="spark.python.worker.reuse", value=True
).config(key="spark.ui.enabled", value=False).master(
"local-cluster[2, 1, 1024]"
).getOrCreate():
# ignore spark log output
spark.sparkContext.setLogLevel("OFF")
print(score_model(spark, data_path, model_uri))
```
This is different than how we would format the same expression if it is
inside any other clause header (`while`, `if`, ...):
```python
def run(data_path, model_uri):
while (
pyspark.sql.SparkSession.builder.config(
key="spark.python.worker.reuse", value=True
)
.config(key="spark.ui.enabled", value=False)
.master("local-cluster[2, 1, 1024]")
.getOrCreate()
):
# ignore spark log output
spark.sparkContext.setLogLevel("OFF")
print(score_model(spark, data_path, model_uri))
```
Which seems inconsistent to me.
This PR changes the formatting of the single-item with Python 3.8 or
older to match that of other clause headers.
```python
def run(data_path, model_uri):
with (
pyspark.sql.SparkSession.builder.config(
key="spark.python.worker.reuse", value=True
)
.config(key="spark.ui.enabled", value=False)
.master("local-cluster[2, 1, 1024]")
.getOrCreate()
):
# ignore spark log output
spark.sparkContext.setLogLevel("OFF")
print(score_model(spark, data_path, model_uri))
```
According to our versioning policy, this style change is gated behind a
preview flag.
## Test Plan
See added tests.
Added
## Summary
Fixes https://github.com/astral-sh/ruff/issues/10267
The issue with the current formatting is that the formatter flips
between the `SingleParenthesizedContextManager` and
`ParenthesizeIfExpands` or `SingleWithTarget` because the layouts use
incompatible formatting ( `SingleParenthesizedContextManager`:
`maybe_parenthesize_expression(context)` vs `ParenthesizeIfExpands`:
`parenthesize_if_expands(item)`, `SingleWithTarget`:
`optional_parentheses(item)`.
The fix is to ensure that the layouts between which the formatter flips
when adding or removing parentheses are the same. I do this by
introducing a new `SingleWithoutTarget` layout that uses the same
formatting as `SingleParenthesizedContextManager` if it has no target
and prefer `SingleWithoutTarget` over using `ParenthesizeIfExpands` or
`SingleWithTarget`.
## Formatting change
The downside is that we now use `maybe_parenthesize_expression` over
`parenthesize_if_expands` for expressions where
`can_omit_optional_parentheses` returns `false`. This can lead to stable
formatting changes. I only found one formatting change in our ecosystem
check and, unfortunately, this is necessary to fix the instability (and
instability fixes are okay to have as part of minor changes according to
our versioning policy)
The benefit of the change is that `with` items with a single context
manager and without a target are now formatted identically to how the
same expression would be formatted in other clause headers.
## Test Plan
I ran the ecosystem check locally
## Summary
Fixes the handling end of line comments that belong to `**kwargs` when
the `**kwargs` come after a slash.
The issue was that we missed to include the `**kwargs` start position
when determining the start of the next node coming after the `/`.
Fixes https://github.com/astral-sh/ruff/issues/10281
## Test Plan
Added test
## Summary
_This is preview only feature and is available using the `--preview`
command-line flag._
With the implementation of [PEP 701] in Python 3.12, f-strings can now
be broken into multiple lines, can contain comments, and can re-use the
same quote character. Currently, no other Python formatter formats the
f-strings so there's some discussion which needs to happen in defining
the style used for f-string formatting. Relevant discussion:
https://github.com/astral-sh/ruff/discussions/9785
The goal for this PR is to add minimal support for f-string formatting.
This would be to format expression within the replacement field without
introducing any major style changes.
### Newlines
The heuristics for adding newline is similar to that of
[Prettier](https://prettier.io/docs/en/next/rationale.html#template-literals)
where the formatter would only split an expression in the replacement
field across multiple lines if there was already a line break within the
replacement field.
In other words, the formatter would not add any newlines unless they
were already present i.e., they were added by the user. This makes
breaking any expression inside an f-string optional and in control of
the user. For example,
```python
# We wouldn't break this
aaaaaaaaaaa = f"asaaaaaaaaaaaaaaaa { aaaaaaaaaaaa + bbbbbbbbbbbb + ccccccccccccccc } cccccccccc"
# But, we would break the following as there's already a newline
aaaaaaaaaaa = f"asaaaaaaaaaaaaaaaa {
aaaaaaaaaaaa + bbbbbbbbbbbb + ccccccccccccccc } cccccccccc"
```
If there are comments in any of the replacement field of the f-string,
then it will always be a multi-line f-string in which case the formatter
would prefer to break expressions i.e., introduce newlines. For example,
```python
x = f"{ # comment
a }"
```
### Quotes
The logic for formatting quotes remains unchanged. The existing logic is
used to determine the necessary quote char and is used accordingly.
Now, if the expression inside an f-string is itself a string like, then
we need to make sure to preserve the existing quote and not change it to
the preferred quote unless it's 3.12. For example,
```python
f"outer {'inner'} outer"
# For pre 3.12, preserve the single quote
f"outer {'inner'} outer"
# While for 3.12 and later, the quotes can be changed
f"outer {"inner"} outer"
```
But, for triple-quoted strings, we can re-use the same quote char unless
the inner string is itself a triple-quoted string.
```python
f"""outer {"inner"} outer""" # valid
f"""outer {'''inner'''} outer""" # preserve the single quote char for the inner string
```
### Debug expressions
If debug expressions are present in the replacement field of a f-string,
then the whitespace needs to be preserved as they will be rendered as it
is (for example, `f"{ x = }"`. If there are any nested f-strings, then
the whitespace in them needs to be preserved as well which means that
we'll stop formatting the f-string as soon as we encounter a debug
expression.
```python
f"outer { x = !s :.3f}"
# ^^
# We can remove these whitespaces
```
Now, the whitespace doesn't need to be preserved around conversion spec
and format specifiers, so we'll format them as usual but we won't be
formatting any nested f-string within the format specifier.
### Miscellaneous
- The
[`hug_parens_with_braces_and_square_brackets`](https://github.com/astral-sh/ruff/issues/8279)
preview style isn't implemented w.r.t. the f-string curly braces.
- The
[indentation](https://github.com/astral-sh/ruff/discussions/9785#discussioncomment-8470590)
is always relative to the f-string containing statement
## Test Plan
* Add new test cases
* Review existing snapshot changes
* Review the ecosystem changes
[PEP 701]: https://peps.python.org/pep-0701/
## 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
This is similar to https://github.com/astral-sh/ruff/pull/8876, but more
limited in scope:
1. It only applies to `# fmt: skip` (like Black). Like `# isort: on`, `#
fmt: on` needs to be on its own line (still).
2. It only delimits on `#`, so you can do `# fmt: skip # noqa`, but not
`# fmt: skip - some other content` or `# fmt: skip; noqa`.
If we want to support the `;`-delimited version, we should revisit
later, since we don't support that in the linter (so `# fmt: skip; noqa`
wouldn't register a `noqa`).
Closes https://github.com/astral-sh/ruff/issues/8892.
## 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.
