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clause.rs
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clause.rs
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use ruff_formatter::{write, Argument, Arguments, FormatError};
use ruff_python_ast::AnyNodeRef;
use ruff_python_ast::{
ElifElseClause, ExceptHandlerExceptHandler, MatchCase, StmtClassDef, StmtFor, StmtFunctionDef,
StmtIf, StmtMatch, StmtTry, StmtWhile, StmtWith, Suite,
};
use ruff_python_trivia::{SimpleToken, SimpleTokenKind, SimpleTokenizer};
use ruff_text_size::{Ranged, TextRange, TextSize};
use crate::comments::{
leading_alternate_branch_comments, trailing_comments, SourceComment, SuppressionKind,
};
use crate::prelude::*;
use crate::statement::suite::{contains_only_an_ellipsis, SuiteKind};
use crate::verbatim::write_suppressed_clause_header;
/// The header of a compound statement clause.
///
/// > A compound statement consists of one or more ‘clauses.’ A clause consists of a header and a ‘suite.’
/// > The clause headers of a particular compound statement are all at the same indentation level.
/// > Each clause header begins with a uniquely identifying keyword and ends with a colon.
/// [source](https://docs.python.org/3/reference/compound_stmts.html#compound-statements)
#[derive(Copy, Clone)]
pub(crate) enum ClauseHeader<'a> {
Class(&'a StmtClassDef),
Function(&'a StmtFunctionDef),
If(&'a StmtIf),
ElifElse(&'a ElifElseClause),
Try(&'a StmtTry),
ExceptHandler(&'a ExceptHandlerExceptHandler),
TryFinally(&'a StmtTry),
Match(&'a StmtMatch),
MatchCase(&'a MatchCase),
For(&'a StmtFor),
While(&'a StmtWhile),
With(&'a StmtWith),
OrElse(ElseClause<'a>),
}
impl<'a> ClauseHeader<'a> {
/// The range from the clause keyword up to and including the final colon.
pub(crate) fn range(self, source: &str) -> FormatResult<TextRange> {
let keyword_range = self.first_keyword_range(source)?;
let mut last_child_end = None;
self.visit(&mut |child| last_child_end = Some(child.end()));
let end = match self {
ClauseHeader::Class(class) => Some(last_child_end.unwrap_or(class.name.end())),
ClauseHeader::Function(function) => Some(last_child_end.unwrap_or(function.name.end())),
ClauseHeader::ElifElse(_)
| ClauseHeader::Try(_)
| ClauseHeader::If(_)
| ClauseHeader::TryFinally(_)
| ClauseHeader::Match(_)
| ClauseHeader::MatchCase(_)
| ClauseHeader::For(_)
| ClauseHeader::While(_)
| ClauseHeader::With(_)
| ClauseHeader::OrElse(_) => last_child_end,
ClauseHeader::ExceptHandler(handler) => {
handler.name.as_ref().map(Ranged::end).or(last_child_end)
}
};
let colon = colon_range(end.unwrap_or(keyword_range.end()), source)?;
Ok(TextRange::new(keyword_range.start(), colon.end()))
}
/// Visits the nodes in the case header.
pub(crate) fn visit<F>(self, visitor: &mut F)
where
F: FnMut(AnyNodeRef),
{
fn visit<'a, N, F>(node: N, visitor: &mut F)
where
N: Into<AnyNodeRef<'a>>,
F: FnMut(AnyNodeRef<'a>),
{
visitor(node.into());
}
match self {
ClauseHeader::Class(StmtClassDef {
type_params,
arguments,
range: _,
decorator_list: _,
name: _,
body: _,
}) => {
if let Some(type_params) = type_params.as_deref() {
visit(type_params, visitor);
}
if let Some(arguments) = arguments {
visit(arguments.as_ref(), visitor);
}
}
ClauseHeader::Function(StmtFunctionDef {
type_params,
parameters,
range: _,
is_async: _,
decorator_list: _,
name: _,
returns,
body: _,
}) => {
if let Some(type_params) = type_params.as_ref() {
visit(type_params, visitor);
}
visit(parameters.as_ref(), visitor);
if let Some(returns) = returns.as_deref() {
visit(returns, visitor);
}
}
ClauseHeader::If(StmtIf {
test,
range: _,
body: _,
elif_else_clauses: _,
}) => {
visit(test.as_ref(), visitor);
}
ClauseHeader::ElifElse(ElifElseClause {
test,
range: _,
body: _,
}) => {
if let Some(test) = test.as_ref() {
visit(test, visitor);
}
}
ClauseHeader::ExceptHandler(ExceptHandlerExceptHandler {
type_: type_expr,
range: _,
name: _,
body: _,
}) => {
if let Some(type_expr) = type_expr.as_deref() {
visit(type_expr, visitor);
}
}
ClauseHeader::Match(StmtMatch {
subject,
range: _,
cases: _,
}) => {
visit(subject.as_ref(), visitor);
}
ClauseHeader::MatchCase(MatchCase {
guard,
pattern,
range: _,
body: _,
}) => {
visit(pattern, visitor);
if let Some(guard) = guard.as_deref() {
visit(guard, visitor);
}
}
ClauseHeader::For(StmtFor {
target,
iter,
range: _,
is_async: _,
body: _,
orelse: _,
}) => {
visit(target.as_ref(), visitor);
visit(iter.as_ref(), visitor);
}
ClauseHeader::While(StmtWhile {
test,
range: _,
body: _,
orelse: _,
}) => {
visit(test.as_ref(), visitor);
}
ClauseHeader::With(StmtWith {
items,
range: _,
is_async: _,
body: _,
}) => {
for item in items {
visit(item, visitor);
}
}
ClauseHeader::Try(_) | ClauseHeader::TryFinally(_) | ClauseHeader::OrElse(_) => {}
}
}
/// Returns the range of the first keyword that marks the start of the clause header.
fn first_keyword_range(self, source: &str) -> FormatResult<TextRange> {
match self {
ClauseHeader::Class(header) => {
let start_position = header
.decorator_list
.last()
.map_or_else(|| header.start(), Ranged::end);
find_keyword(start_position, SimpleTokenKind::Class, source)
}
ClauseHeader::Function(header) => {
let start_position = header
.decorator_list
.last()
.map_or_else(|| header.start(), Ranged::end);
let keyword = if header.is_async {
SimpleTokenKind::Async
} else {
SimpleTokenKind::Def
};
find_keyword(start_position, keyword, source)
}
ClauseHeader::If(header) => find_keyword(header.start(), SimpleTokenKind::If, source),
ClauseHeader::ElifElse(ElifElseClause {
test: None, range, ..
}) => find_keyword(range.start(), SimpleTokenKind::Else, source),
ClauseHeader::ElifElse(ElifElseClause {
test: Some(_),
range,
..
}) => find_keyword(range.start(), SimpleTokenKind::Elif, source),
ClauseHeader::Try(header) => find_keyword(header.start(), SimpleTokenKind::Try, source),
ClauseHeader::ExceptHandler(header) => {
find_keyword(header.start(), SimpleTokenKind::Except, source)
}
ClauseHeader::TryFinally(header) => {
let last_statement = header
.orelse
.last()
.map(AnyNodeRef::from)
.or_else(|| header.handlers.last().map(AnyNodeRef::from))
.or_else(|| header.body.last().map(AnyNodeRef::from))
.unwrap();
find_keyword(last_statement.end(), SimpleTokenKind::Finally, source)
}
ClauseHeader::Match(header) => {
find_keyword(header.start(), SimpleTokenKind::Match, source)
}
ClauseHeader::MatchCase(header) => {
find_keyword(header.start(), SimpleTokenKind::Case, source)
}
ClauseHeader::For(header) => {
let keyword = if header.is_async {
SimpleTokenKind::Async
} else {
SimpleTokenKind::For
};
find_keyword(header.start(), keyword, source)
}
ClauseHeader::While(header) => {
find_keyword(header.start(), SimpleTokenKind::While, source)
}
ClauseHeader::With(header) => {
let keyword = if header.is_async {
SimpleTokenKind::Async
} else {
SimpleTokenKind::With
};
find_keyword(header.start(), keyword, source)
}
ClauseHeader::OrElse(header) => match header {
ElseClause::Try(try_stmt) => {
let last_statement = try_stmt
.handlers
.last()
.map(AnyNodeRef::from)
.or_else(|| try_stmt.body.last().map(AnyNodeRef::from))
.unwrap();
find_keyword(last_statement.end(), SimpleTokenKind::Else, source)
}
ElseClause::For(StmtFor { body, .. })
| ElseClause::While(StmtWhile { body, .. }) => {
find_keyword(body.last().unwrap().end(), SimpleTokenKind::Else, source)
}
},
}
}
}
#[derive(Copy, Clone)]
pub(crate) enum ElseClause<'a> {
Try(&'a StmtTry),
For(&'a StmtFor),
While(&'a StmtWhile),
}
pub(crate) struct FormatClauseHeader<'a, 'ast> {
header: ClauseHeader<'a>,
/// How to format the clause header
formatter: Argument<'a, PyFormatContext<'ast>>,
/// Leading comments coming before the branch, together with the previous node, if any. Only relevant
/// for alternate branches.
leading_comments: Option<(&'a [SourceComment], Option<AnyNodeRef<'a>>)>,
/// The trailing comments coming after the colon.
trailing_colon_comment: &'a [SourceComment],
}
/// Formats a clause header, handling the case where the clause header is suppressed and should not be formatted.
///
/// Calls the `formatter` to format the content of the `header`, except if the `trailing_colon_comment` is a `fmt: skip` suppression comment.
/// Takes care of formatting the `trailing_colon_comment` and adds the `:` at the end of the header.
pub(crate) fn clause_header<'a, 'ast, Content>(
header: ClauseHeader<'a>,
trailing_colon_comment: &'a [SourceComment],
formatter: &'a Content,
) -> FormatClauseHeader<'a, 'ast>
where
Content: Format<PyFormatContext<'ast>>,
{
FormatClauseHeader {
header,
formatter: Argument::new(formatter),
leading_comments: None,
trailing_colon_comment,
}
}
impl<'a> FormatClauseHeader<'a, '_> {
/// Sets the leading comments that precede an alternate branch.
#[must_use]
pub(crate) fn with_leading_comments<N>(
mut self,
comments: &'a [SourceComment],
last_node: Option<N>,
) -> Self
where
N: Into<AnyNodeRef<'a>>,
{
self.leading_comments = Some((comments, last_node.map(Into::into)));
self
}
}
impl<'ast> Format<PyFormatContext<'ast>> for FormatClauseHeader<'_, 'ast> {
fn fmt(&self, f: &mut Formatter<PyFormatContext<'ast>>) -> FormatResult<()> {
if let Some((leading_comments, last_node)) = self.leading_comments {
leading_alternate_branch_comments(leading_comments, last_node).fmt(f)?;
}
if SuppressionKind::has_skip_comment(self.trailing_colon_comment, f.context().source()) {
write_suppressed_clause_header(self.header, f)?;
} else {
// Write a source map entry for the colon for range formatting to support formatting the clause header without
// the clause body. Avoid computing `self.header.range()` otherwise because it's somewhat involved.
let clause_end = if f.options().source_map_generation().is_enabled() {
Some(source_position(
self.header.range(f.context().source())?.end(),
))
} else {
None
};
write!(
f,
[Arguments::from(&self.formatter), token(":"), clause_end]
)?;
}
trailing_comments(self.trailing_colon_comment).fmt(f)
}
}
pub(crate) struct FormatClauseBody<'a> {
body: &'a Suite,
kind: SuiteKind,
trailing_comments: &'a [SourceComment],
}
impl<'a> FormatClauseBody<'a> {
#[must_use]
pub(crate) fn with_kind(mut self, kind: SuiteKind) -> Self {
self.kind = kind;
self
}
}
pub(crate) fn clause_body<'a>(
body: &'a Suite,
trailing_comments: &'a [SourceComment],
) -> FormatClauseBody<'a> {
FormatClauseBody {
body,
kind: SuiteKind::default(),
trailing_comments,
}
}
impl Format<PyFormatContext<'_>> for FormatClauseBody<'_> {
fn fmt(&self, f: &mut Formatter<PyFormatContext<'_>>) -> FormatResult<()> {
// In stable, stubs are only collapsed in stub files, in preview stubs in functions
// or classes are collapsed too
let should_collapse_stub = f.options().source_type().is_stub()
|| matches!(self.kind, SuiteKind::Function | SuiteKind::Class);
if should_collapse_stub
&& contains_only_an_ellipsis(self.body, f.context().comments())
&& self.trailing_comments.is_empty()
{
write!(
f,
[
space(),
self.body.format().with_options(self.kind),
hard_line_break()
]
)
} else {
write!(
f,
[
trailing_comments(self.trailing_comments),
block_indent(&self.body.format().with_options(self.kind))
]
)
}
}
}
/// Finds the range of `keyword` starting the search at `start_position`. Expects only comments and `(` between
/// the `start_position` and the `keyword` token.
fn find_keyword(
start_position: TextSize,
keyword: SimpleTokenKind,
source: &str,
) -> FormatResult<TextRange> {
let mut tokenizer = SimpleTokenizer::starts_at(start_position, source).skip_trivia();
match tokenizer.next() {
Some(token) if token.kind() == keyword => Ok(token.range()),
Some(other) => {
debug_assert!(
false,
"Expected the keyword token {keyword:?} but found the token {other:?} instead."
);
Err(FormatError::syntax_error(
"Expected the keyword token but found another token instead.",
))
}
None => {
debug_assert!(
false,
"Expected the keyword token {keyword:?} but reached the end of the source instead."
);
Err(FormatError::syntax_error(
"Expected the case header keyword token but reached the end of the source instead.",
))
}
}
}
/// Returns the range of the `:` ending the clause header or `Err` if the colon can't be found.
fn colon_range(after_keyword_or_condition: TextSize, source: &str) -> FormatResult<TextRange> {
let mut tokenizer = SimpleTokenizer::starts_at(after_keyword_or_condition, source)
.skip_trivia()
.skip_while(|token| {
matches!(
token.kind(),
SimpleTokenKind::RParen | SimpleTokenKind::Comma
)
});
match tokenizer.next() {
Some(SimpleToken {
kind: SimpleTokenKind::Colon,
range,
}) => Ok(range),
Some(token) => {
debug_assert!(false, "Expected the colon marking the end of the case header but found {token:?} instead.");
Err(FormatError::syntax_error("Expected colon marking the end of the case header but found another token instead."))
}
None => {
debug_assert!(false, "Expected the colon marking the end of the case header but found the end of the range.");
Err(FormatError::syntax_error("Expected the colon marking the end of the case header but found the end of the range."))
}
}
}