Files
ruff/crates/ruff_python_formatter/src/statement/stmt_assign.rs

316 lines
10 KiB
Rust

use ruff_formatter::{format_args, write, FormatError};
use ruff_python_ast::{AnyNodeRef, Expr, StmtAssign};
use crate::comments::{trailing_comments, SourceComment, SuppressionKind};
use crate::context::{NodeLevel, WithNodeLevel};
use crate::expression::parentheses::{
NeedsParentheses, OptionalParentheses, Parentheses, Parenthesize,
};
use crate::expression::{has_own_parentheses, maybe_parenthesize_expression};
use crate::prelude::*;
use crate::statement::trailing_semicolon;
#[derive(Default)]
pub struct FormatStmtAssign;
impl FormatNodeRule<StmtAssign> for FormatStmtAssign {
fn fmt_fields(&self, item: &StmtAssign, f: &mut PyFormatter) -> FormatResult<()> {
let StmtAssign {
range: _,
targets,
value,
} = item;
let (first, rest) = targets.split_first().ok_or(FormatError::syntax_error(
"Expected at least on assignment target",
))?;
write!(
f,
[
first.format(),
space(),
token("="),
space(),
FormatTargets { targets: rest }
]
)?;
FormatStatementsLastExpression::new(value, item).fmt(f)?;
if f.options().source_type().is_ipynb()
&& f.context().node_level().is_last_top_level_statement()
&& rest.is_empty()
&& first.is_name_expr()
&& trailing_semicolon(item.into(), f.context().source()).is_some()
{
token(";").fmt(f)?;
}
Ok(())
}
fn is_suppressed(
&self,
trailing_comments: &[SourceComment],
context: &PyFormatContext,
) -> bool {
SuppressionKind::has_skip_comment(trailing_comments, context.source())
}
}
#[derive(Debug)]
struct FormatTargets<'a> {
targets: &'a [Expr],
}
impl Format<PyFormatContext<'_>> for FormatTargets<'_> {
fn fmt(&self, f: &mut PyFormatter) -> FormatResult<()> {
if let Some((first, rest)) = self.targets.split_first() {
let comments = f.context().comments();
let parenthesize = if comments.has_leading(first) {
ParenthesizeTarget::Always
} else if has_own_parentheses(first, f.context()).is_some() {
ParenthesizeTarget::Never
} else {
ParenthesizeTarget::IfBreaks
};
let group_id = if parenthesize == ParenthesizeTarget::Never {
Some(f.group_id("assignment_parentheses"))
} else {
None
};
let format_first = format_with(|f: &mut PyFormatter| {
let mut f = WithNodeLevel::new(NodeLevel::Expression(group_id), f);
match parenthesize {
ParenthesizeTarget::Always => {
write!(f, [first.format().with_options(Parentheses::Always)])
}
ParenthesizeTarget::Never => {
write!(f, [first.format().with_options(Parentheses::Never)])
}
ParenthesizeTarget::IfBreaks => {
write!(
f,
[
if_group_breaks(&token("(")),
soft_block_indent(&first.format().with_options(Parentheses::Never)),
if_group_breaks(&token(")"))
]
)
}
}
});
write!(
f,
[group(&format_args![
format_first,
space(),
token("="),
space(),
FormatTargets { targets: rest }
])
.with_group_id(group_id)]
)
} else {
Ok(())
}
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum ParenthesizeTarget {
Always,
Never,
IfBreaks,
}
/// Formats the last expression in statements that start with a keyword (like `return`) or after an operator (assignments).
///
/// It avoids parenthesizing unsplittable values (like `None`, `True`, `False`, Names, a subset of strings) just to make
/// the trailing comment fit and inlines a trailing comment if the value itself exceeds the configured line width:
///
/// The implementation formats the statement's and value's trailing end of line comments:
/// * after the expression if the expression needs no parentheses (necessary or the `expand_parent` makes the group never fit).
/// * inside the parentheses if the expression exceeds the line-width.
///
/// ```python
/// a = loooooooooooooooooooooooooooong # with_comment
/// b = (
/// short # with_comment
/// )
/// ```
///
/// Which gets formatted to:
///
/// ```python
/// # formatted
/// a = (
/// loooooooooooooooooooooooooooong # with comment
/// )
/// b = short # with comment
/// ```
///
/// The long name gets parenthesized because it exceeds the configured line width and the trailing comma of the
/// statement gets formatted inside (instead of outside) the parentheses.
///
/// The `short` name gets unparenthesized because it fits into the configured line length, regardless of whether
/// the comment exceeds the line width or not.
///
/// This logic isn't implemented in [`place_comment`] by associating trailing statement comments to the expression because
/// doing so breaks the suite empty lines formatting that relies on trailing comments to be stored on the statement.
pub(super) struct FormatStatementsLastExpression<'a> {
expression: &'a Expr,
parent: AnyNodeRef<'a>,
}
impl<'a> FormatStatementsLastExpression<'a> {
pub(super) fn new<P: Into<AnyNodeRef<'a>>>(expression: &'a Expr, parent: P) -> Self {
Self {
expression,
parent: parent.into(),
}
}
}
impl Format<PyFormatContext<'_>> for FormatStatementsLastExpression<'_> {
fn fmt(&self, f: &mut Formatter<PyFormatContext<'_>>) -> FormatResult<()> {
let can_inline_comment = match self.expression {
Expr::Name(_)
| Expr::NoneLiteral(_)
| Expr::NumberLiteral(_)
| Expr::BooleanLiteral(_) => true,
Expr::StringLiteral(string) => {
string.needs_parentheses(self.parent, f.context()) == OptionalParentheses::BestFit
}
Expr::BytesLiteral(bytes) => {
bytes.needs_parentheses(self.parent, f.context()) == OptionalParentheses::BestFit
}
Expr::FString(fstring) => {
fstring.needs_parentheses(self.parent, f.context()) == OptionalParentheses::BestFit
}
_ => false,
};
if !can_inline_comment {
return maybe_parenthesize_expression(
self.expression,
self.parent,
Parenthesize::IfBreaks,
)
.fmt(f);
}
let comments = f.context().comments().clone();
let expression_comments = comments.leading_dangling_trailing(self.expression);
if expression_comments.has_leading() {
// Preserve the parentheses if the expression has any leading comments,
// same as `maybe_parenthesize_expression`
return self
.expression
.format()
.with_options(Parentheses::Always)
.fmt(f);
}
let statement_trailing_comments = comments.trailing(self.parent);
let after_end_of_line = statement_trailing_comments
.partition_point(|comment| comment.line_position().is_end_of_line());
let (stmt_inline_comments, _) = statement_trailing_comments.split_at(after_end_of_line);
let after_end_of_line = expression_comments
.trailing
.partition_point(|comment| comment.line_position().is_end_of_line());
let (expression_inline_comments, expression_trailing_comments) =
expression_comments.trailing.split_at(after_end_of_line);
if expression_trailing_comments.is_empty() {
let inline_comments = OptionalParenthesesInlinedComments {
expression: expression_inline_comments,
statement: stmt_inline_comments,
};
let group_id = f.group_id("optional_parentheses");
let f = &mut WithNodeLevel::new(NodeLevel::Expression(Some(group_id)), f);
best_fit_parenthesize(&format_with(|f| {
inline_comments.mark_formatted();
self.expression
.format()
.with_options(Parentheses::Never)
.fmt(f)?;
if !inline_comments.is_empty() {
// If the expressions exceeds the line width, format the comments in the parentheses
if_group_breaks(&inline_comments)
.with_group_id(Some(group_id))
.fmt(f)?;
}
Ok(())
}))
.with_group_id(Some(group_id))
.fmt(f)?;
if !inline_comments.is_empty() {
// If the line fits into the line width, format the comments after the parenthesized expression
if_group_fits_on_line(&inline_comments)
.with_group_id(Some(group_id))
.fmt(f)?;
}
Ok(())
} else {
self.expression
.format()
.with_options(Parentheses::Always)
.fmt(f)
}
}
}
#[derive(Debug, Default)]
struct OptionalParenthesesInlinedComments<'a> {
expression: &'a [SourceComment],
statement: &'a [SourceComment],
}
impl<'a> OptionalParenthesesInlinedComments<'a> {
fn is_empty(&self) -> bool {
self.expression.is_empty() && self.statement.is_empty()
}
fn iter_comments(&self) -> impl Iterator<Item = &'a SourceComment> {
self.expression.iter().chain(self.statement)
}
fn mark_formatted(&self) {
for comment in self.expression {
comment.mark_formatted();
}
}
}
impl Format<PyFormatContext<'_>> for OptionalParenthesesInlinedComments<'_> {
fn fmt(&self, f: &mut Formatter<PyFormatContext<'_>>) -> FormatResult<()> {
for comment in self.iter_comments() {
comment.mark_unformatted();
}
write!(
f,
[
trailing_comments(self.expression),
trailing_comments(self.statement)
]
)
}
}