Implement multiline dictionary and list hugging for preview style (#8293)

## Summary

This PR implement's Black's new single-argument hugging for lists, sets,
and dictionaries under preview style.

For example, this:

```python
foo(
    [
        1,
        2,
        3,
    ]
)
```

Would instead now be formatted as:

```python
foo([
    1,
    2,
    3,
])
```

A couple notes:

- This doesn't apply when the argument has a magic trailing comma.
- This _does_ apply when the argument is starred or double-starred.
- We don't apply this when there are comments before or after the
argument, though Black does in some cases (and moves the comments
outside the call parentheses).

It doesn't say it in the originating PR
(https://github.com/psf/black/pull/3964), but I think this also applies
to parenthesized expressions? At least, it does in my testing of preview
vs. stable, though it's possible that behavior predated the linked PR.

See: #8279.

## Test Plan

Before:

| project | similarity index | total files | changed files |

|----------------|------------------:|------------------:|------------------:|
| cpython | 0.75804 | 1799 | 1648 |
| django | 0.99984 | 2772 | 34 |
| home-assistant | 0.99963 | 10596 | 146 |
| poetry | 0.99925 | 317 | 12 |
| transformers | 0.99967 | 2657 | 322 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99980 | 3669 | 18 |
| warehouse | 0.99977 | 654 | 13 |
| zulip | 0.99970 | 1459 | 21 |

After:

| project | similarity index | total files | changed files |

|----------------|------------------:|------------------:|------------------:|
| cpython | 0.75804 | 1799 | 1648 |
| django | 0.99984 | 2772 | 34 |
| home-assistant | 0.99963 | 10596 | 146 |
| poetry | 0.96215 | 317 | 34 |
| transformers | 0.99967 | 2657 | 322 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99980 | 3669 | 18 |
| warehouse | 0.99977 | 654 | 13 |
| zulip | 0.99970 | 1459 | 21 |
This commit is contained in:
Charlie Marsh 2023-11-30 21:11:14 -05:00 committed by GitHub
parent f06c5dc896
commit 019d9aebe9
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
11 changed files with 1969 additions and 15 deletions

View file

@ -23,6 +23,7 @@ use crate::expression::parentheses::{
OptionalParentheses, Parentheses, Parenthesize,
};
use crate::prelude::*;
use crate::PyFormatOptions;
mod binary_like;
pub(crate) mod expr_attribute;
@ -126,10 +127,12 @@ impl FormatRule<Expr, PyFormatContext<'_>> for FormatExpr {
Parentheses::Never => false,
};
if parenthesize {
let comment = f.context().comments().clone();
let node_comments = comment.leading_dangling_trailing(expression);
let comments = f.context().comments().clone();
let node_comments = comments.leading_dangling_trailing(expression);
if !node_comments.has_leading() && !node_comments.has_trailing() {
parenthesized("(", &format_expr, ")").fmt(f)
parenthesized("(", &format_expr, ")")
.with_indent(!is_expression_huggable(expression, f.options()))
.fmt(f)
} else {
format_with_parentheses_comments(expression, &node_comments, f)
}
@ -403,9 +406,11 @@ impl Format<PyFormatContext<'_>> for MaybeParenthesizeExpression<'_> {
parenthesize_if_expands(&expression.format().with_options(Parentheses::Never))
.fmt(f)
}
Parenthesize::IfRequired => {
expression.format().with_options(Parentheses::Never).fmt(f)
}
Parenthesize::Optional | Parenthesize::IfBreaks => {
if can_omit_optional_parentheses(expression, f.context()) {
optional_parentheses(&expression.format().with_options(Parentheses::Never))
@ -427,6 +432,7 @@ impl Format<PyFormatContext<'_>> for MaybeParenthesizeExpression<'_> {
Parenthesize::Optional | Parenthesize::IfRequired => {
expression.format().with_options(Parentheses::Never).fmt(f)
}
Parenthesize::IfBreaks => {
// Is the expression the last token in the parent statement.
// Excludes `await` and `yield` for which Black doesn't seem to apply the layout?
@ -534,6 +540,7 @@ impl Format<PyFormatContext<'_>> for MaybeParenthesizeExpression<'_> {
OptionalParentheses::Never => match parenthesize {
Parenthesize::IfBreaksOrIfRequired => {
parenthesize_if_expands(&expression.format().with_options(Parentheses::Never))
.with_indent(!is_expression_huggable(expression, f.options()))
.fmt(f)
}
@ -1119,6 +1126,86 @@ pub(crate) fn has_own_parentheses(
}
}
/// Returns `true` if the expression can hug directly to enclosing parentheses, as in Black's
/// `hug_parens_with_braces_and_square_brackets` preview style behavior.
///
/// For example, in preview style, given:
/// ```python
/// ([1, 2, 3,])
/// ```
///
/// We want to format it as:
/// ```python
/// ([
/// 1,
/// 2,
/// 3,
/// ])
/// ```
///
/// As opposed to:
/// ```python
/// (
/// [
/// 1,
/// 2,
/// 3,
/// ]
/// )
/// ```
pub(crate) fn is_expression_huggable(expr: &Expr, options: &PyFormatOptions) -> bool {
if !options.preview().is_enabled() {
return false;
}
match expr {
Expr::Tuple(_)
| Expr::List(_)
| Expr::Set(_)
| Expr::Dict(_)
| Expr::ListComp(_)
| Expr::SetComp(_)
| Expr::DictComp(_) => true,
Expr::Starred(ast::ExprStarred { value, .. }) => matches!(
value.as_ref(),
Expr::Tuple(_)
| Expr::List(_)
| Expr::Set(_)
| Expr::Dict(_)
| Expr::ListComp(_)
| Expr::SetComp(_)
| Expr::DictComp(_)
),
Expr::BoolOp(_)
| Expr::NamedExpr(_)
| Expr::BinOp(_)
| Expr::UnaryOp(_)
| Expr::Lambda(_)
| Expr::IfExp(_)
| Expr::GeneratorExp(_)
| Expr::Await(_)
| Expr::Yield(_)
| Expr::YieldFrom(_)
| Expr::Compare(_)
| Expr::Call(_)
| Expr::FormattedValue(_)
| Expr::FString(_)
| Expr::Attribute(_)
| Expr::Subscript(_)
| Expr::Name(_)
| Expr::Slice(_)
| Expr::IpyEscapeCommand(_)
| Expr::StringLiteral(_)
| Expr::BytesLiteral(_)
| Expr::NumberLiteral(_)
| Expr::BooleanLiteral(_)
| Expr::NoneLiteral(_)
| Expr::EllipsisLiteral(_) => false,
}
}
/// The precedence of [python operators](https://docs.python.org/3/reference/expressions.html#operator-precedence) from
/// highest to lowest priority.
///
@ -1144,7 +1231,7 @@ enum OperatorPrecedence {
Conditional,
}
impl From<ast::Operator> for OperatorPrecedence {
impl From<Operator> for OperatorPrecedence {
fn from(value: Operator) -> Self {
match value {
Operator::Add | Operator::Sub => OperatorPrecedence::Additive,