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Generalize bracketed end-of-line comment handling (#6315)
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Micha suggested this in
#6274 (comment), and
it allows us to unify the implementations for arguments and type params.
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@charliermarsh
charliermarsh authored Aug 3, 2023
1 parent 8276b26 commit 5f225b1
Showing 1 changed file with 34 additions and 88 deletions.
122 changes: 34 additions & 88 deletions crates/ruff_python_formatter/src/comments/placement.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,8 @@ use std::cmp::Ordering;
use ruff_python_ast::node::AnyNodeRef;
use ruff_python_ast::whitespace::indentation;
use ruff_python_ast::{
self as ast, Arguments, Comprehension, Expr, ExprAttribute, ExprBinOp, ExprIfExp, ExprSlice,
ExprStarred, MatchCase, Parameters, Ranged, TypeParams,
self as ast, Comprehension, Expr, ExprAttribute, ExprBinOp, ExprIfExp, ExprSlice, ExprStarred,
MatchCase, Parameters, Ranged,
};
use ruff_python_trivia::{
indentation_at_offset, PythonWhitespace, SimpleToken, SimpleTokenKind, SimpleTokenizer,
Expand Down Expand Up @@ -46,7 +46,9 @@ pub(super) fn place_comment<'a>(
AnyNodeRef::Parameters(arguments) => {
handle_parameters_separator_comment(comment, arguments, locator)
}
AnyNodeRef::Arguments(arguments) => handle_arguments_comment(comment, arguments),
AnyNodeRef::Arguments(_) | AnyNodeRef::TypeParams(_) => {
handle_bracketed_end_of_line_comment(comment, locator)
}
AnyNodeRef::Comprehension(comprehension) => {
handle_comprehension_comment(comment, comprehension, locator)
}
Expand Down Expand Up @@ -85,7 +87,6 @@ pub(super) fn place_comment<'a>(
handle_leading_class_with_decorators_comment(comment, class_def)
}
AnyNodeRef::StmtImportFrom(import_from) => handle_import_from_comment(comment, import_from),
AnyNodeRef::TypeParams(type_params) => handle_type_params_comment(comment, type_params),
_ => CommentPlacement::Default(comment),
}
}
Expand Down Expand Up @@ -609,51 +610,6 @@ fn handle_own_line_comment_after_branch<'a>(
}
}

/// Attach an enclosed end-of-line comment to a set of [`TypeParams`].
///
/// For example, given:
/// ```python
/// type foo[ # comment
/// bar,
/// ] = ...
/// ```
///
/// The comment will be attached to the [`TypeParams`] node as a dangling comment, to ensure
/// that it remains on the same line as open bracket.
fn handle_type_params_comment<'a>(
comment: DecoratedComment<'a>,
type_params: &'a TypeParams,
) -> CommentPlacement<'a> {
// The comment needs to be on the same line, but before the first type param. For example, we want
// to treat this as a dangling comment:
// ```python
// type foo[ # comment
// bar,
// baz,
// qux,
// ]
// ```
// However, this should _not_ be treated as a dangling comment:
// ```python
// type foo[bar, # comment
// baz,
// qux,
// ] = ...
// ```
// Thus, we check whether the comment is an end-of-line comment _between_ the start of the
// statement and the first type param. If so, the only possible position is immediately following
// the open parenthesis.
if comment.line_position().is_end_of_line() {
if let Some(first_type_param) = type_params.type_params.first() {
if type_params.start() < comment.start() && comment.end() < first_type_param.start() {
return CommentPlacement::dangling(comment.enclosing_node(), comment);
}
}
}

CommentPlacement::Default(comment)
}

/// Attaches comments for the positional-only parameters separator `/` or the keywords-only
/// parameters separator `*` as dangling comments to the enclosing [`Parameters`] node.
///
Expand Down Expand Up @@ -1226,9 +1182,10 @@ fn find_only_token_in_range(
token
}

/// Attach an enclosed end-of-line comment to a set of [`Arguments`].
/// Attach an end-of-line comment immediately following an open bracket as a dangling comment on
/// enclosing node.
///
/// For example, given:
/// For example, given the following function call:
/// ```python
/// foo( # comment
/// bar,
Expand All @@ -1237,47 +1194,36 @@ fn find_only_token_in_range(
///
/// The comment will be attached to the [`Arguments`] node as a dangling comment, to ensure
/// that it remains on the same line as open parenthesis.
fn handle_arguments_comment<'a>(
///
/// Similarly, given:
/// ```python
/// type foo[ # comment
/// bar,
/// ] = ...
/// ```
///
/// The comment will be attached to the [`TypeParams`] node as a dangling comment, to ensure
/// that it remains on the same line as open bracket.
fn handle_bracketed_end_of_line_comment<'a>(
comment: DecoratedComment<'a>,
arguments: &'a Arguments,
locator: &Locator,
) -> CommentPlacement<'a> {
// The comment needs to be on the same line, but before the first argument. For example, we want
// to treat this as a dangling comment:
// ```python
// foo( # comment
// bar,
// baz,
// qux,
// )
// ```
// However, this should _not_ be treated as a dangling comment:
// ```python
// foo(bar, # comment
// baz,
// qux,
// )
// ```
// Thus, we check whether the comment is an end-of-line comment _between_ the start of the
// statement and the first argument. If so, the only possible position is immediately following
// the open parenthesis.
if comment.line_position().is_end_of_line() {
let first_argument = match (arguments.args.as_slice(), arguments.keywords.as_slice()) {
([first_arg, ..], [first_keyword, ..]) => {
if first_arg.start() < first_keyword.start() {
Some(first_arg.range())
} else {
Some(first_keyword.range())
}
}
([first_arg, ..], []) => Some(first_arg.range()),
([], [first_keyword, ..]) => Some(first_keyword.range()),
([], []) => None,
};
// Ensure that there are no tokens between the open bracket and the comment.
let mut lexer = SimpleTokenizer::new(
locator.contents(),
TextRange::new(comment.enclosing_node().start(), comment.start()),
)
.skip_trivia()
.skip_while(|t| {
matches!(
t.kind(),
SimpleTokenKind::LParen | SimpleTokenKind::LBrace | SimpleTokenKind::LBracket
)
});

if let Some(first_argument) = first_argument {
if arguments.start() < comment.start() && comment.end() < first_argument.start() {
return CommentPlacement::dangling(comment.enclosing_node(), comment);
}
if lexer.next().is_none() {
return CommentPlacement::dangling(comment.enclosing_node(), comment);
}
}

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