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ruff/crates/ruff_python_parser
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Dhruv Manilawala 1b7d08c2c9
Consider : to terminate parenthesized with items (#11775) 
## Summary

This PR is a follow-up to this discussion
(https://github.com/astral-sh/ruff/pull/11770#discussion_r1628917209)
which adds the `:` token in the terminator set for parenthesized with
items.

The main motivation is to avoid parsing too much in speculative mode.
This is evident with the following _before_ and _after_ parsed with
items list for the following code:

```py
with (item1, item2:
    foo
```

<table>
  <tr>
    <th>Before (3 items)</th>
    <th>After (2 items)</th>
  </tr>
  <tr>
    <td>
<pre>
parsed_with_items: [
    ParsedWithItem {
        item: WithItem {
            range: 6..11,
            context_expr: Name(
                ExprName {
                    range: 6..11,
                    id: "item1",
                    ctx: Load,
                },
            ),
            optional_vars: None,
        },
        is_parenthesized: false,
    },
    ParsedWithItem {
        item: WithItem {
            range: 13..18,
            context_expr: Name(
                ExprName {
                    range: 13..18,
                    id: "item2",
                    ctx: Load,
                },
            ),
            optional_vars: None,
        },
        is_parenthesized: false,
    },
    ParsedWithItem {
        item: WithItem {
            range: 24..27,
            context_expr: Name(
                ExprName {
                    range: 24..27,
                    id: "foo",
                    ctx: Load,
                },
            ),
            optional_vars: None,
        },
        is_parenthesized: false,
    },
]
</pre>
	</td>
    <td>
<pre>
parsed_with_items: [
    ParsedWithItem {
        item: WithItem {
            range: 6..11,
            context_expr: Name(
                ExprName {
                    range: 6..11,
                    id: "item1",
                    ctx: Load,
                },
            ),
            optional_vars: None,
        },
        is_parenthesized: false,
    },
    ParsedWithItem {
        item: WithItem {
            range: 13..18,
            context_expr: Name(
                ExprName {
                    range: 13..18,
                    id: "item2",
                    ctx: Load,
                },
            ),
            optional_vars: None,
        },
        is_parenthesized: false,
    },
]
</pre>
	</td>
  </tr>
</table>

## Test Plan

`cargo insta test`
2024-06-06 18:40:44 +05:30
..
resources Use speculative parsing for with-items (#11770) 2024-06-06 08:59:56 +00:00
src Consider : to terminate parenthesized with items (#11775) 2024-06-06 18:40:44 +05:30
tests Use speculative parsing for with-items (#11770) 2024-06-06 08:59:56 +00:00
Cargo.toml Remove less used parser dependencies (#11718) 2024-06-03 13:08:24 +00:00
CONTRIBUTING.md Add basic docs for the parser crate (#11199) 2024-04-29 17:08:07 +00:00
README.md Add basic docs for the parser crate (#11199) 2024-04-29 17:08:07 +00:00

README.md

Ruff Python Parser

Ruff's Python parser is a hand-written recursive descent parser which can parse Python source code into an Abstract Syntax Tree (AST). It also utilizes the Pratt parsing technique to parse expressions with different precedence.

Try out the parser in the playground.

Python version support

The parser supports the latest Python syntax, which is currently Python 3.12. It does not throw syntax errors if it encounters a syntax feature that is not supported by the target-version. This will be fixed in a future release (see https://github.com/astral-sh/ruff/issues/6591).

Contributing

Refer to the contributing guidelines to get started and GitHub issues with the parser label for issues that need help.