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use ruff_formatter::{FormatRuleWithOptions, write};
use ruff_python_ast::AnyNodeRef;
use ruff_python_ast::{Expr, ExprAttribute, ExprNumberLiteral, Number};
use ruff_python_trivia::{SimpleTokenKind, SimpleTokenizer, find_only_token_in_range};
use ruff_text_size::{Ranged, TextRange};
use crate::comments::dangling_comments;
use crate::expression::CallChainLayout;
use crate::expression::parentheses::{
NeedsParentheses, OptionalParentheses, Parentheses, is_expression_parenthesized,
};
use crate::prelude::*;
use crate::preview::is_fluent_layout_split_first_call_enabled;
#[derive(Default)]
pub struct FormatExprAttribute {
call_chain_layout: CallChainLayout,
}
impl FormatRuleWithOptions<ExprAttribute, PyFormatContext<'_>> for FormatExprAttribute {
type Options = CallChainLayout;
fn with_options(mut self, options: Self::Options) -> Self {
self.call_chain_layout = options;
self
}
}
impl FormatNodeRule<ExprAttribute> for FormatExprAttribute {
fn fmt_fields(&self, item: &ExprAttribute, f: &mut PyFormatter) -> FormatResult<()> {
let ExprAttribute {
value,
range: _,
node_index: _,
attr,
ctx: _,
} = item;
let call_chain_layout = self.call_chain_layout.apply_in_node(item, f);
let format_inner = format_with(|f: &mut PyFormatter| {
let parenthesize_value =
is_base_ten_number_literal(value.as_ref(), f.context().source()) || {
is_expression_parenthesized(
value.into(),
f.context().comments().ranges(),
f.context().source(),
)
};
if call_chain_layout.is_fluent() {
if parenthesize_value {
// Don't propagate the call chain layout.
value.format().with_options(Parentheses::Always).fmt(f)?;
} else {
match value.as_ref() {
Expr::Attribute(expr) => {
expr.format()
.with_options(call_chain_layout.transition_after_attribute())
.fmt(f)?;
}
Expr::Call(expr) => {
expr.format()
.with_options(call_chain_layout.transition_after_attribute())
.fmt(f)?;
}
Expr::Subscript(expr) => {
expr.format()
.with_options(call_chain_layout.transition_after_attribute())
.fmt(f)?;
}
_ => {
value.format().with_options(Parentheses::Never).fmt(f)?;
}
}
}
} else if parenthesize_value {
value.format().with_options(Parentheses::Always).fmt(f)?;
} else {
value.format().with_options(Parentheses::Never).fmt(f)?;
}
let comments = f.context().comments().clone();
// Always add a line break if the value is parenthesized and there's an
// end of line comment on the same line as the closing parenthesis.
// ```python
// (
// (
// a
// ) # `end_of_line_comment`
// .
// b
// )
// ```
let has_trailing_end_of_line_comment =
SimpleTokenizer::starts_at(value.end(), f.context().source())
.skip_trivia()
.take_while(|token| token.kind == SimpleTokenKind::RParen)
.last()
.is_some_and(|right_paren| {
let trailing_value_comments = comments.trailing(&**value);
trailing_value_comments.iter().any(|comment| {
comment.line_position().is_end_of_line()
&& comment.start() > right_paren.end()
})
});
if has_trailing_end_of_line_comment {
hard_line_break().fmt(f)?;
}
// Allow the `.` on its own line if this is a fluent call chain
// and the value either requires parenthesizing or is a call or subscript expression
// (it's a fluent chain but not the first element).
//
// In preview we also break _at_ the first call in the chain.
// For example:
//
// ```diff
// # stable formatting vs. preview
// x = (
// - df.merge()
// + df
// + .merge()
// .groupby()
// .agg()
// .filter()
// )
// ```
else if call_chain_layout.is_fluent() {
if parenthesize_value
|| value.is_call_expr()
|| value.is_subscript_expr()
// Remember to update the doc-comment above when
// stabilizing this behavior.
|| (is_fluent_layout_split_first_call_enabled(f.context())
&& call_chain_layout.is_first_call_like())
{
soft_line_break().fmt(f)?;
}
}
// Identify dangling comments before and after the dot:
// ```python
// (
// (
// a
// )
// # `before_dot`
// . # `after_dot`
// # `after_dot`
// b
// )
// ```
let dangling = comments.dangling(item);
let (before_dot, after_dot) = if dangling.is_empty() {
(dangling, dangling)
} else {
let dot_token = find_only_token_in_range(
TextRange::new(item.value.end(), item.attr.start()),
SimpleTokenKind::Dot,
f.context().source(),
);
dangling.split_at(
dangling.partition_point(|comment| comment.start() < dot_token.start()),
)
};
write!(
f,
[
dangling_comments(before_dot),
token("."),
dangling_comments(after_dot),
attr.format()
]
)
});
let is_call_chain_root =
self.call_chain_layout == CallChainLayout::Default && call_chain_layout.is_fluent();
if is_call_chain_root {
write!(f, [group(&format_inner)])
} else {
write!(f, [format_inner])
}
}
}
impl NeedsParentheses for ExprAttribute {
fn needs_parentheses(
&self,
_parent: AnyNodeRef,
context: &PyFormatContext,
) -> OptionalParentheses {
// Checks if there are any own line comments in an attribute chain (a.b.c).
if CallChainLayout::from_expression(
self.into(),
context.comments().ranges(),
context.source(),
)
.is_fluent()
{
OptionalParentheses::Multiline
} else if context.comments().has_dangling(self) {
OptionalParentheses::Always
} else if is_expression_parenthesized(
self.value.as_ref().into(),
context.comments().ranges(),
context.source(),
) {
// We have to avoid creating syntax errors like
// ```python
// variable = (something) # trailing
// .my_attribute
// ```
// See https://github.com/astral-sh/ruff/issues/19350
if context
.comments()
.trailing(self.value.as_ref())
.iter()
.any(|comment| comment.line_position().is_end_of_line())
{
OptionalParentheses::Multiline
} else {
OptionalParentheses::Never
}
} else {
self.value.needs_parentheses(self.into(), context)
}
}
}
// Non Hex, octal or binary number literals need parentheses to disambiguate the attribute `.` from
// a decimal point. Floating point numbers don't strictly need parentheses but it reads better (rather than 0.0.test()).
fn is_base_ten_number_literal(expr: &Expr, source: &str) -> bool {
if let Some(ExprNumberLiteral {
value,
range,
node_index: _,
}) = expr.as_number_literal_expr()
{
match value {
Number::Float(_) => true,
Number::Int(_) => {
let text = &source[*range];
!matches!(
text.as_bytes().get(0..2),
Some([b'0', b'x' | b'X' | b'o' | b'O' | b'b' | b'B'])
)
}
Number::Complex { .. } => false,
}
} else {
false
}
}