## Summary
This fixes a bug where the parser would panic when there is a "gap" in
the token source.
What's a gap?
The reason it's `<=` instead of just `==` is because there could be
whitespaces between
the two tokens. For example:
```python
# last token end
# | current token (newline) start
# v v
def foo \n
# ^
# assume there's trailing whitespace here
```
Or, there could tokens that are considered "trivia" and thus aren't
emitted by the token
source. These are comments and non-logical newlines. For example:
```python
# last token end
# v
def foo # comment\n
# ^ current token (newline) start
```
In either of the above cases, there's a "gap" between the end of the
last token and start
of the current token.
## Test Plan
Add test cases and update the snapshots.
## Summary
This PR adds a new `Clause::Case` and uses it to parse the body of a
`case` block. Earlier, it was using `Match` which would give an
incorrect error message like:
```
|
1 | match subject:
2 | case 1:
3 | case 2: ...
| ^^^^ Syntax Error: Expected an indented block after `match` statement
|
```
## Test Plan
Add test case and update the snapshot.
## Summary
This PR fixes the bug in with items parsing where it would fail to
recognize that the parenthesized expression is part of a large binary
expression.
## Test Plan
Add test cases and verified the snapshots.
## Summary
This PR fixes the bug in parenthesized with items parsing where the `if`
expression would result into a syntax error.
The reason being that once we identify that the ambiguous left
parenthesis belongs to the context expression, the parser converts the
parsed with item into an equivalent expression. Then, the parser
continuous to parse any postfix expressions. Now, attribute, subscript,
and call are taken into account as they're grouped in
`parse_postfix_expression` but `if` expression has it's own parsing
function.
Use `parse_if_expression` once all postfix expressions have been parsed.
Ideally, I think that `if` could be included in postfix expression
parsing as they can be chained as well (`x if True else y if True else
z`).
## Test Plan
Add test cases and verified the snapshots.
## Summary
This PR fixes a bug in the new parser which involves the parser context
w.r.t. for statement. This is specifically around the `in` keyword which
can be present in the target expression and shouldn't be considered to
be part of the `for` statement header. Ideally it should use a context
which is passed between functions, thus using a call stack to set /
unset a specific variant which will be done in a follow-up PR as it
requires some amount of refactor.
## Test Plan
Add test cases and update the snapshots.
(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>
