ruff/crates/ruff_python_formatter/src/expression/mod.rs
2024-01-10 12:47:34 +01:00

1286 lines
48 KiB
Rust

use std::cmp::Ordering;
use std::slice;
use ruff_formatter::{
write, FormatOwnedWithRule, FormatRefWithRule, FormatRule, FormatRuleWithOptions,
};
use ruff_python_ast as ast;
use ruff_python_ast::parenthesize::parentheses_iterator;
use ruff_python_ast::visitor::preorder::{walk_expr, PreorderVisitor};
use ruff_python_ast::{AnyNodeRef, Expr, ExpressionRef, Operator};
use ruff_python_trivia::CommentRanges;
use ruff_text_size::Ranged;
use crate::builders::parenthesize_if_expands;
use crate::comments::{leading_comments, trailing_comments, LeadingDanglingTrailingComments};
use crate::context::{NodeLevel, WithNodeLevel};
use crate::expression::expr_generator_exp::is_generator_parenthesized;
use crate::expression::expr_tuple::is_tuple_parenthesized;
use crate::expression::parentheses::{
is_expression_parenthesized, optional_parentheses, parenthesized, HuggingStyle,
NeedsParentheses, OptionalParentheses, Parentheses, Parenthesize,
};
use crate::prelude::*;
use crate::preview::{
is_hug_parens_with_braces_and_square_brackets_enabled, is_multiline_string_handling_enabled,
};
use crate::string::AnyString;
mod binary_like;
pub(crate) mod expr_attribute;
pub(crate) mod expr_await;
pub(crate) mod expr_bin_op;
pub(crate) mod expr_bool_op;
pub(crate) mod expr_boolean_literal;
pub(crate) mod expr_bytes_literal;
pub(crate) mod expr_call;
pub(crate) mod expr_compare;
pub(crate) mod expr_dict;
pub(crate) mod expr_dict_comp;
pub(crate) mod expr_ellipsis_literal;
pub(crate) mod expr_f_string;
pub(crate) mod expr_generator_exp;
pub(crate) mod expr_if_exp;
pub(crate) mod expr_ipy_escape_command;
pub(crate) mod expr_lambda;
pub(crate) mod expr_list;
pub(crate) mod expr_list_comp;
pub(crate) mod expr_name;
pub(crate) mod expr_named_expr;
pub(crate) mod expr_none_literal;
pub(crate) mod expr_number_literal;
pub(crate) mod expr_set;
pub(crate) mod expr_set_comp;
pub(crate) mod expr_slice;
pub(crate) mod expr_starred;
pub(crate) mod expr_string_literal;
pub(crate) mod expr_subscript;
pub(crate) mod expr_tuple;
pub(crate) mod expr_unary_op;
pub(crate) mod expr_yield;
pub(crate) mod expr_yield_from;
mod operator;
pub(crate) mod parentheses;
#[derive(Copy, Clone, PartialEq, Eq, Default)]
pub struct FormatExpr {
parentheses: Parentheses,
}
impl FormatRuleWithOptions<Expr, PyFormatContext<'_>> for FormatExpr {
type Options = Parentheses;
fn with_options(mut self, options: Self::Options) -> Self {
self.parentheses = options;
self
}
}
impl FormatRule<Expr, PyFormatContext<'_>> for FormatExpr {
fn fmt(&self, expression: &Expr, f: &mut PyFormatter) -> FormatResult<()> {
let parentheses = self.parentheses;
let format_expr = format_with(|f| match expression {
Expr::BoolOp(expr) => expr.format().fmt(f),
Expr::NamedExpr(expr) => expr.format().fmt(f),
Expr::BinOp(expr) => expr.format().fmt(f),
Expr::UnaryOp(expr) => expr.format().fmt(f),
Expr::Lambda(expr) => expr.format().fmt(f),
Expr::IfExp(expr) => expr.format().fmt(f),
Expr::Dict(expr) => expr.format().fmt(f),
Expr::Set(expr) => expr.format().fmt(f),
Expr::ListComp(expr) => expr.format().fmt(f),
Expr::SetComp(expr) => expr.format().fmt(f),
Expr::DictComp(expr) => expr.format().fmt(f),
Expr::GeneratorExp(expr) => expr.format().fmt(f),
Expr::Await(expr) => expr.format().fmt(f),
Expr::Yield(expr) => expr.format().fmt(f),
Expr::YieldFrom(expr) => expr.format().fmt(f),
Expr::Compare(expr) => expr.format().fmt(f),
Expr::Call(expr) => expr.format().fmt(f),
Expr::FString(expr) => expr.format().fmt(f),
Expr::StringLiteral(expr) => expr.format().fmt(f),
Expr::BytesLiteral(expr) => expr.format().fmt(f),
Expr::NumberLiteral(expr) => expr.format().fmt(f),
Expr::BooleanLiteral(expr) => expr.format().fmt(f),
Expr::NoneLiteral(expr) => expr.format().fmt(f),
Expr::EllipsisLiteral(expr) => expr.format().fmt(f),
Expr::Attribute(expr) => expr.format().fmt(f),
Expr::Subscript(expr) => expr.format().fmt(f),
Expr::Starred(expr) => expr.format().fmt(f),
Expr::Name(expr) => expr.format().fmt(f),
Expr::List(expr) => expr.format().fmt(f),
Expr::Tuple(expr) => expr.format().fmt(f),
Expr::Slice(expr) => expr.format().fmt(f),
Expr::IpyEscapeCommand(expr) => expr.format().fmt(f),
});
let parenthesize = match parentheses {
Parentheses::Preserve => is_expression_parenthesized(
expression.into(),
f.context().comments().ranges(),
f.context().source(),
),
Parentheses::Always => true,
// Fluent style means we already have parentheses
Parentheses::Never => false,
};
if parenthesize {
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, ")")
.with_hugging(is_expression_huggable(expression, f.context()))
.fmt(f)
} else {
format_with_parentheses_comments(expression, &node_comments, f)
}
} else {
let level = match f.context().node_level() {
NodeLevel::TopLevel(_) | NodeLevel::CompoundStatement => {
NodeLevel::Expression(None)
}
saved_level @ (NodeLevel::Expression(_) | NodeLevel::ParenthesizedExpression) => {
saved_level
}
};
let mut f = WithNodeLevel::new(level, f);
write!(f, [format_expr])
}
}
}
/// The comments below are trailing on the addition, but it's also outside the
/// parentheses
/// ```python
/// x = [
/// # comment leading
/// (1 + 2) # comment trailing
/// ]
/// ```
/// as opposed to
/// ```python
/// x = [(
/// # comment leading
/// 1 + 2 # comment trailing
/// )]
/// ```
/// , where the comments are inside the parentheses. That is also affects list
/// formatting, where we want to avoid moving the comments after the comma inside
/// the parentheses:
/// ```python
/// data = [
/// (
/// b"\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00"
/// b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
/// ), # Point (0 0)
/// ]
/// ```
/// We could mark those comments as trailing in list but it's easier to handle
/// them here too.
///
/// So given
/// ```python
/// x = [
/// # comment leading outer
/// (
/// # comment leading inner
/// 1 + 2 # comment trailing inner
/// ) # comment trailing outer
/// ]
/// ```
/// we want to keep the inner an outer comments outside the parentheses and the inner ones inside.
/// This is independent of whether they are own line or end-of-line comments, though end-of-line
/// comments can become own line comments when we discard nested parentheses.
///
/// Style decision: When there are multiple nested parentheses around an expression, we consider the
/// outermost parentheses the relevant ones and discard the others.
fn format_with_parentheses_comments(
expression: &Expr,
node_comments: &LeadingDanglingTrailingComments,
f: &mut PyFormatter,
) -> FormatResult<()> {
// First part: Split the comments
// TODO(konstin): We don't have the parent, which is a problem:
// ```python
// f(
// # a
// (a)
// )
// ```
// gets formatted as
// ```python
// f(
// (
// # a
// a
// )
// )
// ```
let range_with_parens = parentheses_iterator(
expression.into(),
None,
f.context().comments().ranges(),
f.context().source(),
)
.last();
let (leading_split, trailing_split) = if let Some(range_with_parens) = range_with_parens {
let leading_split = node_comments
.leading
.partition_point(|comment| comment.start() < range_with_parens.start());
let trailing_split = node_comments
.trailing
.partition_point(|comment| comment.start() < range_with_parens.end());
(leading_split, trailing_split)
} else {
(0, node_comments.trailing.len())
};
let (leading_outer, leading_inner) = node_comments.leading.split_at(leading_split);
let (trailing_inner, trailing_outer) = node_comments.trailing.split_at(trailing_split);
// Preserve an opening parentheses comment
// ```python
// a = ( # opening parentheses comment
// # leading inner
// 1
// )
// ```
let (parentheses_comment, leading_inner) = match leading_inner.split_first() {
Some((first, rest)) if first.line_position().is_end_of_line() => {
(slice::from_ref(first), rest)
}
_ => (Default::default(), node_comments.leading),
};
// Second Part: Format
// The code order is a bit strange here, we format:
// * outer leading comment
// * opening parenthesis
// * opening parenthesis comment
// * inner leading comments
// * the expression itself
// * inner trailing comments
// * the closing parenthesis
// * outer trailing comments
let fmt_fields = format_with(|f| match expression {
Expr::BoolOp(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::NamedExpr(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::BinOp(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::UnaryOp(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::Lambda(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::IfExp(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::Dict(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::Set(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::ListComp(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::SetComp(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::DictComp(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::GeneratorExp(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::Await(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::Yield(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::YieldFrom(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::Compare(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::Call(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::FString(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::StringLiteral(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::BytesLiteral(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::NumberLiteral(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::BooleanLiteral(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::NoneLiteral(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::EllipsisLiteral(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::Attribute(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::Subscript(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::Starred(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::Name(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::List(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::Tuple(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::Slice(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
Expr::IpyEscapeCommand(expr) => FormatNodeRule::fmt_fields(expr.format().rule(), expr, f),
});
leading_comments(leading_outer).fmt(f)?;
// Custom FormatNodeRule::fmt variant that only formats the inner comments
let format_node_rule_fmt = format_with(|f| {
// No need to handle suppression comments, those are statement only
leading_comments(leading_inner).fmt(f)?;
let is_source_map_enabled = f.options().source_map_generation().is_enabled();
if is_source_map_enabled {
source_position(expression.start()).fmt(f)?;
}
fmt_fields.fmt(f)?;
if is_source_map_enabled {
source_position(expression.end()).fmt(f)?;
}
trailing_comments(trailing_inner).fmt(f)
});
// The actual parenthesized formatting
parenthesized("(", &format_node_rule_fmt, ")")
.with_dangling_comments(parentheses_comment)
.fmt(f)?;
trailing_comments(trailing_outer).fmt(f)?;
Ok(())
}
/// Wraps an expression in an optional parentheses except if its [`NeedsParentheses::needs_parentheses`] implementation
/// indicates that it is okay to omit the parentheses. For example, parentheses can always be omitted for lists,
/// because they already bring their own parentheses.
pub(crate) fn maybe_parenthesize_expression<'a, T>(
expression: &'a Expr,
parent: T,
parenthesize: Parenthesize,
) -> MaybeParenthesizeExpression<'a>
where
T: Into<AnyNodeRef<'a>>,
{
MaybeParenthesizeExpression {
expression,
parent: parent.into(),
parenthesize,
}
}
pub(crate) struct MaybeParenthesizeExpression<'a> {
expression: &'a Expr,
parent: AnyNodeRef<'a>,
parenthesize: Parenthesize,
}
impl Format<PyFormatContext<'_>> for MaybeParenthesizeExpression<'_> {
fn fmt(&self, f: &mut PyFormatter) -> FormatResult<()> {
let MaybeParenthesizeExpression {
expression,
parent,
parenthesize,
} = self;
let preserve_parentheses = parenthesize.is_optional()
&& is_expression_parenthesized(
(*expression).into(),
f.context().comments().ranges(),
f.context().source(),
);
// If we want to preserve parentheses, short-circuit.
if preserve_parentheses {
return expression.format().with_options(Parentheses::Always).fmt(f);
}
let comments = f.context().comments().clone();
let node_comments = comments.leading_dangling_trailing(*expression);
// If the expression has comments, we always want to preserve the parentheses. This also
// ensures that we correctly handle parenthesized comments, and don't need to worry about
// them in the implementation below.
if node_comments.has_leading() || node_comments.has_trailing_own_line() {
return expression.format().with_options(Parentheses::Always).fmt(f);
}
let needs_parentheses = match expression.needs_parentheses(*parent, f.context()) {
OptionalParentheses::Always => OptionalParentheses::Always,
// The reason to add parentheses is to avoid a syntax error when breaking an expression over multiple lines.
// Therefore, it is unnecessary to add an additional pair of parentheses if an outer expression
// is parenthesized.
_ if f.context().node_level().is_parenthesized() => OptionalParentheses::Never,
needs_parentheses => needs_parentheses,
};
match needs_parentheses {
OptionalParentheses::Multiline => match parenthesize {
Parenthesize::IfBreaksOrIfRequired => {
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))
.fmt(f)
} else {
parenthesize_if_expands(
&expression.format().with_options(Parentheses::Never),
)
.fmt(f)
}
}
},
OptionalParentheses::BestFit => match parenthesize {
Parenthesize::IfBreaksOrIfRequired => {
parenthesize_if_expands(&expression.format().with_options(Parentheses::Never))
.fmt(f)
}
Parenthesize::Optional | Parenthesize::IfRequired => {
expression.format().with_options(Parentheses::Never).fmt(f)
}
Parenthesize::IfBreaks => {
if node_comments.has_trailing() {
expression.format().with_options(Parentheses::Always).fmt(f)
} else {
// The group id is necessary because the nested expressions may reference it.
let group_id = f.group_id("optional_parentheses");
let f = &mut WithNodeLevel::new(NodeLevel::Expression(Some(group_id)), f);
best_fit_parenthesize(&expression.format().with_options(Parentheses::Never))
.with_group_id(Some(group_id))
.fmt(f)
}
}
},
OptionalParentheses::Never => match parenthesize {
Parenthesize::IfBreaksOrIfRequired => {
parenthesize_if_expands(&expression.format().with_options(Parentheses::Never))
.with_indent(is_expression_huggable(expression, f.context()).is_none())
.fmt(f)
}
Parenthesize::Optional | Parenthesize::IfBreaks | Parenthesize::IfRequired => {
expression.format().with_options(Parentheses::Never).fmt(f)
}
},
OptionalParentheses::Always => {
expression.format().with_options(Parentheses::Always).fmt(f)
}
}
}
}
impl NeedsParentheses for Expr {
fn needs_parentheses(
&self,
parent: AnyNodeRef,
context: &PyFormatContext,
) -> OptionalParentheses {
match self {
Expr::BoolOp(expr) => expr.needs_parentheses(parent, context),
Expr::NamedExpr(expr) => expr.needs_parentheses(parent, context),
Expr::BinOp(expr) => expr.needs_parentheses(parent, context),
Expr::UnaryOp(expr) => expr.needs_parentheses(parent, context),
Expr::Lambda(expr) => expr.needs_parentheses(parent, context),
Expr::IfExp(expr) => expr.needs_parentheses(parent, context),
Expr::Dict(expr) => expr.needs_parentheses(parent, context),
Expr::Set(expr) => expr.needs_parentheses(parent, context),
Expr::ListComp(expr) => expr.needs_parentheses(parent, context),
Expr::SetComp(expr) => expr.needs_parentheses(parent, context),
Expr::DictComp(expr) => expr.needs_parentheses(parent, context),
Expr::GeneratorExp(expr) => expr.needs_parentheses(parent, context),
Expr::Await(expr) => expr.needs_parentheses(parent, context),
Expr::Yield(expr) => expr.needs_parentheses(parent, context),
Expr::YieldFrom(expr) => expr.needs_parentheses(parent, context),
Expr::Compare(expr) => expr.needs_parentheses(parent, context),
Expr::Call(expr) => expr.needs_parentheses(parent, context),
Expr::FString(expr) => expr.needs_parentheses(parent, context),
Expr::StringLiteral(expr) => expr.needs_parentheses(parent, context),
Expr::BytesLiteral(expr) => expr.needs_parentheses(parent, context),
Expr::NumberLiteral(expr) => expr.needs_parentheses(parent, context),
Expr::BooleanLiteral(expr) => expr.needs_parentheses(parent, context),
Expr::NoneLiteral(expr) => expr.needs_parentheses(parent, context),
Expr::EllipsisLiteral(expr) => expr.needs_parentheses(parent, context),
Expr::Attribute(expr) => expr.needs_parentheses(parent, context),
Expr::Subscript(expr) => expr.needs_parentheses(parent, context),
Expr::Starred(expr) => expr.needs_parentheses(parent, context),
Expr::Name(expr) => expr.needs_parentheses(parent, context),
Expr::List(expr) => expr.needs_parentheses(parent, context),
Expr::Tuple(expr) => expr.needs_parentheses(parent, context),
Expr::Slice(expr) => expr.needs_parentheses(parent, context),
Expr::IpyEscapeCommand(expr) => expr.needs_parentheses(parent, context),
}
}
}
impl<'ast> AsFormat<PyFormatContext<'ast>> for Expr {
type Format<'a> = FormatRefWithRule<'a, Expr, FormatExpr, PyFormatContext<'ast>>;
fn format(&self) -> Self::Format<'_> {
FormatRefWithRule::new(self, FormatExpr::default())
}
}
impl<'ast> IntoFormat<PyFormatContext<'ast>> for Expr {
type Format = FormatOwnedWithRule<Expr, FormatExpr, PyFormatContext<'ast>>;
fn into_format(self) -> Self::Format {
FormatOwnedWithRule::new(self, FormatExpr::default())
}
}
/// Tests if it is safe to omit the optional parentheses.
///
/// We prefer parentheses at least in the following cases:
/// * The expression contains more than one unparenthesized expression with the same precedence. For example,
/// the expression `a * b * c` contains two multiply operations. We prefer parentheses in that case.
/// `(a * b) * c` or `a * b + c` are okay, because the subexpression is parenthesized, or the expression uses operands with a lower precedence
/// * The expression contains at least one parenthesized sub expression (optimization to avoid unnecessary work)
///
/// This mimics Black's [`_maybe_split_omitting_optional_parens`](https://github.com/psf/black/blob/d1248ca9beaf0ba526d265f4108836d89cf551b7/src/black/linegen.py#L746-L820)
#[allow(clippy::if_same_then_else)]
pub(crate) fn can_omit_optional_parentheses(expr: &Expr, context: &PyFormatContext) -> bool {
let mut visitor = CanOmitOptionalParenthesesVisitor::new(context);
visitor.visit_subexpression(expr);
if !visitor.any_parenthesized_expressions {
// Only use the more complex IR when there is any expression that we can possibly split by
false
} else if visitor.max_precedence_count > 1 {
false
} else if visitor.max_precedence == OperatorPrecedence::None {
// Micha: This seems to apply for lambda expressions where the body ends in a subscript.
// Subscripts are excluded by default because breaking them looks odd, but it seems to be fine for lambda expression.
//
// ```python
// mapper = lambda x: dict_with_default[
// np.nan if isinstance(x, float) and np.isnan(x) else x
// ]
// ```
//
// to prevent that it gets formatted as:
//
// ```python
// mapper = (
// lambda x: dict_with_default[
// np.nan if isinstance(x, float) and np.isnan(x) else x
// ]
// )
// ```
// I think we should remove this check in the future and instead parenthesize the body of the lambda expression:
//
// ```python
// mapper = lambda x: (
// dict_with_default[
// np.nan if isinstance(x, float) and np.isnan(x) else x
// ]
// )
// ```
//
// Another case are method chains:
// ```python
// xxxxxxxx.some_kind_of_method(
// some_argument=[
// "first",
// "second",
// "third",
// ]
// ).another_method(a)
// ```
true
} else if visitor.max_precedence == OperatorPrecedence::Attribute {
// A single method call inside a named expression (`:=`) or as the body of a lambda function:
// ```python
// kwargs["open_with"] = lambda path, _: fsspec.open(
// path, "wb", **(storage_options or {})
// ).open()
//
// if ret := subprocess.run(
// ["git", "rev-parse", "--short", "HEAD"],
// cwd=package_dir,
// capture_output=True,
// encoding="ascii",
// errors="surrogateescape",
// ).stdout:
// ```
true
} else {
fn is_parenthesized(expr: &Expr, context: &PyFormatContext) -> bool {
// Don't break subscripts except in parenthesized context. It looks weird.
!expr.is_subscript_expr()
&& has_parentheses(expr, context).is_some_and(OwnParentheses::is_non_empty)
}
// Only use the layout if the first expression starts with parentheses
// or the last expression ends with parentheses of some sort, and
// those parentheses are non-empty.
visitor
.last
.is_some_and(|last| is_parenthesized(last, context))
|| visitor
.first
.expression()
.is_some_and(|first| is_parenthesized(first, context))
}
}
#[derive(Clone, Debug)]
struct CanOmitOptionalParenthesesVisitor<'input> {
max_precedence: OperatorPrecedence,
max_precedence_count: u32,
any_parenthesized_expressions: bool,
last: Option<&'input Expr>,
first: First<'input>,
context: &'input PyFormatContext<'input>,
}
impl<'input> CanOmitOptionalParenthesesVisitor<'input> {
fn new(context: &'input PyFormatContext) -> Self {
Self {
context,
max_precedence: OperatorPrecedence::None,
max_precedence_count: 0,
any_parenthesized_expressions: false,
last: None,
first: First::None,
}
}
fn update_max_precedence(&mut self, precedence: OperatorPrecedence) {
self.update_max_precedence_with_count(precedence, 1);
}
fn update_max_precedence_with_count(&mut self, precedence: OperatorPrecedence, count: u32) {
match self.max_precedence.cmp(&precedence) {
Ordering::Less => {
self.max_precedence_count = count;
self.max_precedence = precedence;
}
Ordering::Equal => {
self.max_precedence_count += count;
}
Ordering::Greater => {}
}
}
// Visits a subexpression, ignoring whether it is parenthesized or not
fn visit_subexpression(&mut self, expr: &'input Expr) {
match expr {
Expr::Dict(_)
| Expr::List(_)
| Expr::Set(_)
| Expr::ListComp(_)
| Expr::SetComp(_)
| Expr::DictComp(_) => {
self.any_parenthesized_expressions = true;
// The values are always parenthesized, don't visit.
return;
}
Expr::Tuple(tuple) if is_tuple_parenthesized(tuple, self.context.source()) => {
self.any_parenthesized_expressions = true;
// The values are always parenthesized, don't visit.
return;
}
Expr::GeneratorExp(generator)
if is_generator_parenthesized(generator, self.context.source()) =>
{
self.any_parenthesized_expressions = true;
// The values are always parenthesized, don't visit.
return;
}
// It's impossible for a file smaller or equal to 4GB to contain more than 2^32 comparisons
// because each comparison requires a left operand, and `n` `operands` and right sides.
#[allow(clippy::cast_possible_truncation)]
Expr::BoolOp(ast::ExprBoolOp {
range: _,
op: _,
values,
}) => self.update_max_precedence_with_count(
OperatorPrecedence::BooleanOperation,
values.len().saturating_sub(1) as u32,
),
Expr::BinOp(ast::ExprBinOp {
op,
left: _,
right: _,
range: _,
}) => self.update_max_precedence(OperatorPrecedence::from(*op)),
Expr::IfExp(_) => {
// + 1 for the if and one for the else
self.update_max_precedence_with_count(OperatorPrecedence::Conditional, 2);
}
// It's impossible for a file smaller or equal to 4GB to contain more than 2^32 comparisons
// because each comparison requires a left operand, and `n` `operands` and right sides.
#[allow(clippy::cast_possible_truncation)]
Expr::Compare(ast::ExprCompare {
range: _,
left: _,
ops,
comparators: _,
}) => {
self.update_max_precedence_with_count(
OperatorPrecedence::Comparator,
ops.len() as u32,
);
}
Expr::Call(ast::ExprCall {
range: _,
func,
arguments: _,
}) => {
self.any_parenthesized_expressions = true;
// Only walk the function, the arguments are always parenthesized
self.visit_expr(func);
self.last = Some(expr);
return;
}
Expr::Subscript(ast::ExprSubscript { value, .. }) => {
self.any_parenthesized_expressions = true;
// Only walk the function, the subscript is always parenthesized
self.visit_expr(value);
self.last = Some(expr);
// Don't walk the slice, because the slice is always parenthesized.
return;
}
// `[a, b].test.test[300].dot`
Expr::Attribute(ast::ExprAttribute {
range: _,
value,
attr: _,
ctx: _,
}) => {
self.visit_expr(value);
if has_parentheses(value, self.context).is_some() {
self.update_max_precedence(OperatorPrecedence::Attribute);
}
self.last = Some(expr);
return;
}
Expr::StringLiteral(ast::ExprStringLiteral { value, .. })
if value.is_implicit_concatenated() =>
{
self.update_max_precedence(OperatorPrecedence::String);
}
Expr::BytesLiteral(ast::ExprBytesLiteral { value, .. })
if value.is_implicit_concatenated() =>
{
self.update_max_precedence(OperatorPrecedence::String);
}
Expr::FString(ast::ExprFString { value, .. }) if value.is_implicit_concatenated() => {
self.update_max_precedence(OperatorPrecedence::String);
return;
}
// Non terminal nodes that don't have a termination token.
Expr::NamedExpr(_) | Expr::GeneratorExp(_) | Expr::Tuple(_) => {}
// Expressions with sub expressions but a preceding token
// Mark this expression as first expression and not the sub expression.
// Visit the sub-expressions because the sub expressions may be the end of the entire expression.
Expr::UnaryOp(ast::ExprUnaryOp {
range: _,
op,
operand: _,
}) => {
if op.is_invert() {
self.update_max_precedence(OperatorPrecedence::BitwiseInversion);
}
self.first.set_if_none(First::Token);
}
Expr::Lambda(_)
| Expr::Await(_)
| Expr::Yield(_)
| Expr::YieldFrom(_)
| Expr::Starred(_) => {
self.first.set_if_none(First::Token);
}
// Terminal nodes or nodes that wrap a sub-expression (where the sub expression can never be at the end).
Expr::FString(_)
| Expr::StringLiteral(_)
| Expr::BytesLiteral(_)
| Expr::NumberLiteral(_)
| Expr::BooleanLiteral(_)
| Expr::NoneLiteral(_)
| Expr::EllipsisLiteral(_)
| Expr::Name(_)
| Expr::Slice(_)
| Expr::IpyEscapeCommand(_) => {
return;
}
};
walk_expr(self, expr);
}
}
impl<'input> PreorderVisitor<'input> for CanOmitOptionalParenthesesVisitor<'input> {
fn visit_expr(&mut self, expr: &'input Expr) {
self.last = Some(expr);
// Rule only applies for non-parenthesized expressions.
if is_expression_parenthesized(
expr.into(),
self.context.comments().ranges(),
self.context.source(),
) {
self.any_parenthesized_expressions = true;
} else {
self.visit_subexpression(expr);
}
self.first.set_if_none(First::Expression(expr));
}
}
#[derive(Copy, Clone, Debug)]
enum First<'a> {
None,
/// Expression starts with a non-parentheses token. E.g. `not a`
Token,
Expression(&'a Expr),
}
impl<'a> First<'a> {
#[inline]
fn set_if_none(&mut self, first: First<'a>) {
if matches!(self, First::None) {
*self = first;
}
}
fn expression(self) -> Option<&'a Expr> {
match self {
First::None | First::Token => None,
First::Expression(expr) => Some(expr),
}
}
}
/// A call chain consists only of attribute access (`.` operator), function/method calls and
/// subscripts. We use fluent style for the call chain if there are at least two attribute dots
/// after call parentheses or subscript brackets. In case of fluent style the parentheses/bracket
/// will close on the previous line and the dot gets its own line, otherwise the line will start
/// with the closing parentheses/bracket and the dot follows immediately after.
///
/// Below, the left hand side of the addition has only a single attribute access after a call, the
/// second `.filter`. The first `.filter` is a call, but it doesn't follow a call. The right hand
/// side has two, the `.limit_results` after the call and the `.filter` after the subscript, so it
/// gets formatted in fluent style. The outer expression we assign to `blogs` has zero since the
/// `.all` follows attribute parentheses and not call parentheses.
///
/// ```python
/// blogs = (
/// Blog.objects.filter(
/// entry__headline__contains="Lennon",
/// ).filter(
/// entry__pub_date__year=2008,
/// )
/// + Blog.objects.filter(
/// entry__headline__contains="McCartney",
/// )
/// .limit_results[:10]
/// .filter(
/// entry__pub_date__year=2010,
/// )
/// ).all()
/// ```
#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
pub enum CallChainLayout {
/// The root of a call chain
#[default]
Default,
/// A nested call chain element that uses fluent style.
Fluent,
/// A nested call chain element not using fluent style.
NonFluent,
}
impl CallChainLayout {
pub(crate) fn from_expression(
mut expr: ExpressionRef,
comment_ranges: &CommentRanges,
source: &str,
) -> Self {
let mut attributes_after_parentheses = 0;
loop {
match expr {
ExpressionRef::Attribute(ast::ExprAttribute { value, .. }) => {
// ```
// f().g
// ^^^ value
// data[:100].T
// ^^^^^^^^^^ value
// ```
if is_expression_parenthesized(value.into(), comment_ranges, source) {
// `(a).b`. We preserve these parentheses so don't recurse
attributes_after_parentheses += 1;
break;
} else if matches!(value.as_ref(), Expr::Call(_) | Expr::Subscript(_)) {
attributes_after_parentheses += 1;
}
expr = ExpressionRef::from(value.as_ref());
}
// ```
// f()
// ^^^ expr
// ^ func
// data[:100]
// ^^^^^^^^^^ expr
// ^^^^ value
// ```
ExpressionRef::Call(ast::ExprCall { func: inner, .. })
| ExpressionRef::Subscript(ast::ExprSubscript { value: inner, .. }) => {
expr = ExpressionRef::from(inner.as_ref());
}
_ => {
// We to format the following in fluent style:
// ```
// f2 = (a).w().t(1,)
// ^ expr
// ```
if is_expression_parenthesized(expr, comment_ranges, source) {
attributes_after_parentheses += 1;
}
break;
}
}
// We preserve these parentheses so don't recurse
if is_expression_parenthesized(expr, comment_ranges, source) {
break;
}
}
if attributes_after_parentheses < 2 {
CallChainLayout::NonFluent
} else {
CallChainLayout::Fluent
}
}
/// Determine whether to actually apply fluent layout in attribute, call and subscript
/// formatting
pub(crate) fn apply_in_node<'a>(
self,
item: impl Into<ExpressionRef<'a>>,
f: &mut PyFormatter,
) -> CallChainLayout {
match self {
CallChainLayout::Default => {
if f.context().node_level().is_parenthesized() {
CallChainLayout::from_expression(
item.into(),
f.context().comments().ranges(),
f.context().source(),
)
} else {
CallChainLayout::NonFluent
}
}
layout @ (CallChainLayout::Fluent | CallChainLayout::NonFluent) => layout,
}
}
}
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub(crate) enum OwnParentheses {
/// The node has parentheses, but they are empty (e.g., `[]` or `f()`).
Empty,
/// The node has parentheses, and they are non-empty (e.g., `[1]` or `f(1)`).
NonEmpty,
}
impl OwnParentheses {
const fn is_non_empty(self) -> bool {
matches!(self, OwnParentheses::NonEmpty)
}
}
/// Returns the [`OwnParentheses`] value for a given [`Expr`], to indicate whether it has its
/// own parentheses or is itself parenthesized.
///
/// Differs from [`has_own_parentheses`] in that it returns [`OwnParentheses::NonEmpty`] for
/// parenthesized expressions, like `(1)` or `([1])`, regardless of whether those expression have
/// their _own_ parentheses.
pub(crate) fn has_parentheses(expr: &Expr, context: &PyFormatContext) -> Option<OwnParentheses> {
let own_parentheses = has_own_parentheses(expr, context);
// If the node has its own non-empty parentheses, we don't need to check for surrounding
// parentheses (e.g., `[1]`, or `([1])`).
if own_parentheses == Some(OwnParentheses::NonEmpty) {
return own_parentheses;
}
// Otherwise, if the node lacks parentheses (e.g., `(1)`) or only contains empty parentheses
// (e.g., `([])`), we need to check for surrounding parentheses.
if is_expression_parenthesized(expr.into(), context.comments().ranges(), context.source()) {
return Some(OwnParentheses::NonEmpty);
}
own_parentheses
}
/// Returns the [`OwnParentheses`] value for a given [`Expr`], to indicate whether it has its
/// own parentheses, and whether those parentheses are empty.
///
/// A node is considered to have its own parentheses if it includes a `[]`, `()`, or `{}` pair
/// that is inherent to the node (e.g., as in `f()`, `[]`, or `{1: 2}`, but not `(a.b.c)`).
///
/// Parentheses are considered to be non-empty if they contain any elements or comments.
pub(crate) fn has_own_parentheses(
expr: &Expr,
context: &PyFormatContext,
) -> Option<OwnParentheses> {
match expr {
// These expressions are always non-empty.
Expr::ListComp(_) | Expr::SetComp(_) | Expr::DictComp(_) | Expr::Subscript(_) => {
Some(OwnParentheses::NonEmpty)
}
Expr::GeneratorExp(generator)
if is_generator_parenthesized(generator, context.source()) =>
{
Some(OwnParentheses::NonEmpty)
}
// These expressions must contain _some_ child or trivia token in order to be non-empty.
Expr::List(ast::ExprList { elts, .. }) | Expr::Set(ast::ExprSet { elts, .. }) => {
if !elts.is_empty() || context.comments().has_dangling(AnyNodeRef::from(expr)) {
Some(OwnParentheses::NonEmpty)
} else {
Some(OwnParentheses::Empty)
}
}
Expr::Tuple(tuple) if is_tuple_parenthesized(tuple, context.source()) => {
if !tuple.elts.is_empty() || context.comments().has_dangling(AnyNodeRef::from(expr)) {
Some(OwnParentheses::NonEmpty)
} else {
Some(OwnParentheses::Empty)
}
}
Expr::Dict(ast::ExprDict { keys, .. }) => {
if !keys.is_empty() || context.comments().has_dangling(AnyNodeRef::from(expr)) {
Some(OwnParentheses::NonEmpty)
} else {
Some(OwnParentheses::Empty)
}
}
Expr::Call(ast::ExprCall { arguments, .. }) => {
if !arguments.is_empty() || context.comments().has_dangling(AnyNodeRef::from(expr)) {
Some(OwnParentheses::NonEmpty)
} else {
Some(OwnParentheses::Empty)
}
}
_ => None,
}
}
/// Returns `true` if the expression can hug directly to enclosing parentheses, as in Black's
/// `hug_parens_with_braces_and_square_brackets` or `multiline_string_handling` preview styles 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,
context: &PyFormatContext,
) -> Option<HuggingStyle> {
match expr {
Expr::Tuple(_)
| Expr::List(_)
| Expr::Set(_)
| Expr::Dict(_)
| Expr::ListComp(_)
| Expr::SetComp(_)
| Expr::DictComp(_) => is_hug_parens_with_braces_and_square_brackets_enabled(context)
.then_some(HuggingStyle::Always),
Expr::Starred(ast::ExprStarred { value, .. }) => is_expression_huggable(value, context),
Expr::StringLiteral(string) => is_huggable_string(AnyString::String(string), context),
Expr::BytesLiteral(bytes) => is_huggable_string(AnyString::Bytes(bytes), context),
Expr::FString(fstring) => is_huggable_string(AnyString::FString(fstring), context),
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::Attribute(_)
| Expr::Subscript(_)
| Expr::Name(_)
| Expr::Slice(_)
| Expr::IpyEscapeCommand(_)
| Expr::NumberLiteral(_)
| Expr::BooleanLiteral(_)
| Expr::NoneLiteral(_)
| Expr::EllipsisLiteral(_) => None,
}
}
/// Returns `true` if `string` is a multiline string that is not implicitly concatenated.
fn is_huggable_string(string: AnyString, context: &PyFormatContext) -> Option<HuggingStyle> {
if !is_multiline_string_handling_enabled(context) {
return None;
}
if !string.is_implicit_concatenated() && string.is_multiline(context.source()) {
Some(HuggingStyle::IfFirstLineFits)
} else {
None
}
}
/// The precedence of [python operators](https://docs.python.org/3/reference/expressions.html#operator-precedence) from
/// highest to lowest priority.
///
/// Ruff uses the operator precedence to decide in which order to split operators:
/// Operators with a lower precedence split before higher-precedence operators.
/// Splitting by precedence ensures that the visual grouping reflects the precedence.
#[derive(Debug, Copy, Clone, Ord, PartialOrd, Eq, PartialEq)]
enum OperatorPrecedence {
None,
Attribute,
Exponential,
BitwiseInversion,
Multiplicative,
Additive,
Shift,
BitwiseAnd,
BitwiseXor,
BitwiseOr,
Comparator,
// Implicit string concatenation
String,
BooleanOperation,
Conditional,
}
impl From<Operator> for OperatorPrecedence {
fn from(value: Operator) -> Self {
match value {
Operator::Add | Operator::Sub => OperatorPrecedence::Additive,
Operator::Mult
| Operator::MatMult
| Operator::Div
| Operator::Mod
| Operator::FloorDiv => OperatorPrecedence::Multiplicative,
Operator::Pow => OperatorPrecedence::Exponential,
Operator::LShift | Operator::RShift => OperatorPrecedence::Shift,
Operator::BitOr => OperatorPrecedence::BitwiseOr,
Operator::BitXor => OperatorPrecedence::BitwiseXor,
Operator::BitAnd => OperatorPrecedence::BitwiseAnd,
}
}
}
/// Returns `true` if `expr` is an expression that can be split into multiple lines.
///
/// Returns `false` for expressions that are guaranteed to never split.
pub(crate) fn is_splittable_expression(expr: &Expr, context: &PyFormatContext) -> bool {
match expr {
// Single token expressions. They never have any split points.
Expr::NamedExpr(_)
| Expr::Name(_)
| Expr::NumberLiteral(_)
| Expr::BooleanLiteral(_)
| Expr::NoneLiteral(_)
| Expr::EllipsisLiteral(_)
| Expr::Slice(_)
| Expr::IpyEscapeCommand(_) => false,
// Expressions that insert split points when parenthesized.
Expr::Compare(_)
| Expr::BinOp(_)
| Expr::BoolOp(_)
| Expr::IfExp(_)
| Expr::GeneratorExp(_)
| Expr::Subscript(_)
| Expr::Await(_)
| Expr::ListComp(_)
| Expr::SetComp(_)
| Expr::DictComp(_)
| Expr::YieldFrom(_) => true,
// Sequence types can split if they contain at least one element.
Expr::Tuple(tuple) => !tuple.elts.is_empty(),
Expr::Dict(dict) => !dict.values.is_empty(),
Expr::Set(set) => !set.elts.is_empty(),
Expr::List(list) => !list.elts.is_empty(),
Expr::UnaryOp(unary) => is_splittable_expression(unary.operand.as_ref(), context),
Expr::Yield(ast::ExprYield { value, .. }) => value.is_some(),
Expr::Call(ast::ExprCall {
arguments, func, ..
}) => {
!arguments.is_empty()
|| is_expression_parenthesized(
func.as_ref().into(),
context.comments().ranges(),
context.source(),
)
}
// String like literals can expand if they are implicit concatenated.
Expr::FString(fstring) => fstring.value.is_implicit_concatenated(),
Expr::StringLiteral(string) => string.value.is_implicit_concatenated(),
Expr::BytesLiteral(bytes) => bytes.value.is_implicit_concatenated(),
// Expressions that have no split points per se, but they contain nested sub expressions that might expand.
Expr::Lambda(ast::ExprLambda {
body: expression, ..
})
| Expr::Starred(ast::ExprStarred {
value: expression, ..
})
| Expr::Attribute(ast::ExprAttribute {
value: expression, ..
}) => {
is_expression_parenthesized(
expression.into(),
context.comments().ranges(),
context.source(),
) || is_splittable_expression(expression.as_ref(), context)
}
}
}