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update rewrite_chain to return RewriteResult
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@ding-young @ytmimi
ding-young authored and ytmimi committed Aug 15, 2024
1 parent caaa612 commit fbe0424
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Showing 2 changed files with 107 additions and 56 deletions.
161 changes: 106 additions & 55 deletions src/chains.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -79,6 +79,9 @@ use thin_vec::ThinVec;
/// Provides the original input contents from the span
/// of a chain element with trailing spaces trimmed.
fn format_overflow_style(span: Span, context: &RewriteContext<'_>) -> Option<String> {
// TODO(ding-young): Currently returning None when the given span is out of the range
// covered by the snippet provider. If this is a common cause for internal
// rewrite failure, add a new enum variant and return RewriteError instead of None
context.snippet_provider.span_to_snippet(span).map(|s| {
s.lines()
.map(|l| l.trim_end())
Expand All @@ -92,12 +95,16 @@ fn format_chain_item(
context: &RewriteContext<'_>,
rewrite_shape: Shape,
allow_overflow: bool,
) -> Option<String> {
) -> RewriteResult {
if allow_overflow {
item.rewrite(context, rewrite_shape)
.or_else(|| format_overflow_style(item.span, context))
// TODO(ding-young): Consider calling format_overflow_style()
// only when item.rewrite_result() returns RewriteError::ExceedsMaxWidth.
// It may be inappropriate to call format_overflow_style on other RewriteError
// since the current approach retries formatting if allow_overflow is true
item.rewrite_result(context, rewrite_shape)
.or_else(|_| format_overflow_style(item.span, context).unknown_error())
} else {
item.rewrite(context, rewrite_shape)
item.rewrite_result(context, rewrite_shape)
}
}

Expand Down Expand Up @@ -134,17 +141,17 @@ pub(crate) fn rewrite_chain(
expr: &ast::Expr,
context: &RewriteContext<'_>,
shape: Shape,
) -> Option<String> {
) -> RewriteResult {
let chain = Chain::from_ast(expr, context);
debug!("rewrite_chain {:?} {:?}", chain, shape);

// If this is just an expression with some `?`s, then format it trivially and
// return early.
if chain.children.is_empty() {
return chain.parent.rewrite(context, shape);
return chain.parent.rewrite_result(context, shape);
}

chain.rewrite(context, shape)
chain.rewrite_result(context, shape)
}

#[derive(Debug)]
Expand Down Expand Up @@ -524,6 +531,10 @@ impl Chain {

impl Rewrite for Chain {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
self.rewrite_result(context, shape).ok()
}

fn rewrite_result(&self, context: &RewriteContext<'_>, shape: Shape) -> RewriteResult {
debug!("rewrite chain {:?} {:?}", self, shape);

let mut formatter = match context.config.indent_style() {
Expand All @@ -537,17 +548,25 @@ impl Rewrite for Chain {

formatter.format_root(&self.parent, context, shape)?;
if let Some(result) = formatter.pure_root() {
return wrap_str(result, context.config.max_width(), shape);
return wrap_str(result, context.config.max_width(), shape)
.max_width_error(shape.width, self.parent.span);
}

let first = self.children.first().unwrap_or(&self.parent);
let last = self.children.last().unwrap_or(&self.parent);
let children_span = mk_sp(first.span.lo(), last.span.hi());
let full_span = self.parent.span.with_hi(children_span.hi());

// Decide how to layout the rest of the chain.
let child_shape = formatter.child_shape(context, shape)?;
let child_shape = formatter
.child_shape(context, shape)
.max_width_error(shape.width, children_span)?;

formatter.format_children(context, child_shape)?;
formatter.format_last_child(context, shape, child_shape)?;

let result = formatter.join_rewrites(context, child_shape)?;
wrap_str(result, context.config.max_width(), shape)
wrap_str(result, context.config.max_width(), shape).max_width_error(shape.width, full_span)
}
}

Expand All @@ -569,16 +588,20 @@ trait ChainFormatter {
parent: &ChainItem,
context: &RewriteContext<'_>,
shape: Shape,
) -> Option<()>;
) -> Result<(), RewriteError>;
fn child_shape(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<Shape>;
fn format_children(&mut self, context: &RewriteContext<'_>, child_shape: Shape) -> Option<()>;
fn format_children(
&mut self,
context: &RewriteContext<'_>,
child_shape: Shape,
) -> Result<(), RewriteError>;
fn format_last_child(
&mut self,
context: &RewriteContext<'_>,
shape: Shape,
child_shape: Shape,
) -> Option<()>;
fn join_rewrites(&self, context: &RewriteContext<'_>, child_shape: Shape) -> Option<String>;
) -> Result<(), RewriteError>;
fn join_rewrites(&self, context: &RewriteContext<'_>, child_shape: Shape) -> RewriteResult;
// Returns `Some` if the chain is only a root, None otherwise.
fn pure_root(&mut self) -> Option<String>;
}
Expand Down Expand Up @@ -621,12 +644,16 @@ impl<'a> ChainFormatterShared<'a> {
}
}

fn format_children(&mut self, context: &RewriteContext<'_>, child_shape: Shape) -> Option<()> {
fn format_children(
&mut self,
context: &RewriteContext<'_>,
child_shape: Shape,
) -> Result<(), RewriteError> {
for item in &self.children[..self.children.len() - 1] {
let rewrite = format_chain_item(item, context, child_shape, self.allow_overflow)?;
self.rewrites.push(rewrite);
}
Some(())
Ok(())
}

// Rewrite the last child. The last child of a chain requires special treatment. We need to
Expand Down Expand Up @@ -667,8 +694,8 @@ impl<'a> ChainFormatterShared<'a> {
context: &RewriteContext<'_>,
shape: Shape,
child_shape: Shape,
) -> Option<()> {
let last = self.children.last()?;
) -> Result<(), RewriteError> {
let last = self.children.last().unknown_error()?;
let extendable = may_extend && last_line_extendable(&self.rewrites[0]);
let prev_last_line_width = last_line_width(&self.rewrites[0]);

Expand All @@ -692,11 +719,17 @@ impl<'a> ChainFormatterShared<'a> {
&& self.rewrites.iter().all(|s| !s.contains('\n'))
&& one_line_budget > 0;
let last_shape = if all_in_one_line {
shape.sub_width(last.tries)?
shape
.sub_width(last.tries)
.max_width_error(shape.width, last.span)?
} else if extendable {
child_shape.sub_width(last.tries)?
child_shape
.sub_width(last.tries)
.max_width_error(child_shape.width, last.span)?
} else {
child_shape.sub_width(shape.rhs_overhead(context.config) + last.tries)?
child_shape
.sub_width(shape.rhs_overhead(context.config) + last.tries)
.max_width_error(child_shape.width, last.span)?
};

let mut last_subexpr_str = None;
Expand All @@ -712,7 +745,7 @@ impl<'a> ChainFormatterShared<'a> {
};

if let Some(one_line_shape) = one_line_shape {
if let Some(rw) = last.rewrite(context, one_line_shape) {
if let Ok(rw) = last.rewrite_result(context, one_line_shape) {
// We allow overflowing here only if both of the following conditions match:
// 1. The entire chain fits in a single line except the last child.
// 2. `last_child_str.lines().count() >= 5`.
Expand All @@ -727,17 +760,18 @@ impl<'a> ChainFormatterShared<'a> {
// last child on its own line, and compare two rewrites to choose which is
// better.
let last_shape = child_shape
.sub_width(shape.rhs_overhead(context.config) + last.tries)?;
match last.rewrite(context, last_shape) {
Some(ref new_rw) if !could_fit_single_line => {
.sub_width(shape.rhs_overhead(context.config) + last.tries)
.max_width_error(child_shape.width, last.span)?;
match last.rewrite_result(context, last_shape) {
Ok(ref new_rw) if !could_fit_single_line => {
last_subexpr_str = Some(new_rw.clone());
}
Some(ref new_rw) if new_rw.lines().count() >= line_count => {
Ok(ref new_rw) if new_rw.lines().count() >= line_count => {
last_subexpr_str = Some(rw);
self.fits_single_line = could_fit_single_line && all_in_one_line;
}
new_rw @ Some(..) => {
last_subexpr_str = new_rw;
Ok(new_rw) => {
last_subexpr_str = Some(new_rw);
}
_ => {
last_subexpr_str = Some(rw);
Expand All @@ -752,22 +786,28 @@ impl<'a> ChainFormatterShared<'a> {
let last_shape = if context.use_block_indent() {
last_shape
} else {
child_shape.sub_width(shape.rhs_overhead(context.config) + last.tries)?
child_shape
.sub_width(shape.rhs_overhead(context.config) + last.tries)
.max_width_error(child_shape.width, last.span)?
};

last_subexpr_str = last_subexpr_str.or_else(|| last.rewrite(context, last_shape));
self.rewrites.push(last_subexpr_str?);
Some(())
let last_subexpr_str =
last_subexpr_str.unwrap_or(last.rewrite_result(context, last_shape)?);
self.rewrites.push(last_subexpr_str);
Ok(())
}

fn join_rewrites(&self, context: &RewriteContext<'_>, child_shape: Shape) -> Option<String> {
fn join_rewrites(&self, context: &RewriteContext<'_>, child_shape: Shape) -> RewriteResult {
let connector = if self.fits_single_line {
// Yay, we can put everything on one line.
Cow::from("")
} else {
// Use new lines.
if context.force_one_line_chain.get() {
return None;
return Err(RewriteError::ExceedsMaxWidth {
configured_width: child_shape.width,
span: self.children.last().unknown_error()?.span,
});
}
child_shape.to_string_with_newline(context.config)
};
Expand All @@ -786,7 +826,7 @@ impl<'a> ChainFormatterShared<'a> {
result.push_str(rewrite);
}

Some(result)
Ok(result)
}
}

Expand All @@ -811,8 +851,8 @@ impl<'a> ChainFormatter for ChainFormatterBlock<'a> {
parent: &ChainItem,
context: &RewriteContext<'_>,
shape: Shape,
) -> Option<()> {
let mut root_rewrite: String = parent.rewrite(context, shape)?;
) -> Result<(), RewriteError> {
let mut root_rewrite: String = parent.rewrite_result(context, shape)?;

let mut root_ends_with_block = parent.kind.is_block_like(context, &root_rewrite);
let tab_width = context.config.tab_spaces().saturating_sub(shape.offset);
Expand All @@ -822,10 +862,12 @@ impl<'a> ChainFormatter for ChainFormatterBlock<'a> {
if let ChainItemKind::Comment(..) = item.kind {
break;
}
let shape = shape.offset_left(root_rewrite.len())?;
match &item.rewrite(context, shape) {
Some(rewrite) => root_rewrite.push_str(rewrite),
None => break,
let shape = shape
.offset_left(root_rewrite.len())
.max_width_error(shape.width, item.span)?;
match &item.rewrite_result(context, shape) {
Ok(rewrite) => root_rewrite.push_str(rewrite),
Err(_) => break,
}

root_ends_with_block = last_line_extendable(&root_rewrite);
Expand All @@ -837,15 +879,19 @@ impl<'a> ChainFormatter for ChainFormatterBlock<'a> {
}
self.shared.rewrites.push(root_rewrite);
self.root_ends_with_block = root_ends_with_block;
Some(())
Ok(())
}

fn child_shape(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<Shape> {
let block_end = self.root_ends_with_block;
Some(get_block_child_shape(block_end, context, shape))
}

fn format_children(&mut self, context: &RewriteContext<'_>, child_shape: Shape) -> Option<()> {
fn format_children(
&mut self,
context: &RewriteContext<'_>,
child_shape: Shape,
) -> Result<(), RewriteError> {
self.shared.format_children(context, child_shape)
}

Expand All @@ -854,12 +900,12 @@ impl<'a> ChainFormatter for ChainFormatterBlock<'a> {
context: &RewriteContext<'_>,
shape: Shape,
child_shape: Shape,
) -> Option<()> {
) -> Result<(), RewriteError> {
self.shared
.format_last_child(true, context, shape, child_shape)
}

fn join_rewrites(&self, context: &RewriteContext<'_>, child_shape: Shape) -> Option<String> {
fn join_rewrites(&self, context: &RewriteContext<'_>, child_shape: Shape) -> RewriteResult {
self.shared.join_rewrites(context, child_shape)
}

Expand Down Expand Up @@ -890,9 +936,9 @@ impl<'a> ChainFormatter for ChainFormatterVisual<'a> {
parent: &ChainItem,
context: &RewriteContext<'_>,
shape: Shape,
) -> Option<()> {
) -> Result<(), RewriteError> {
let parent_shape = shape.visual_indent(0);
let mut root_rewrite = parent.rewrite(context, parent_shape)?;
let mut root_rewrite = parent.rewrite_result(context, parent_shape)?;
let multiline = root_rewrite.contains('\n');
self.offset = if multiline {
last_line_width(&root_rewrite).saturating_sub(shape.used_width())
Expand All @@ -904,18 +950,19 @@ impl<'a> ChainFormatter for ChainFormatterVisual<'a> {
let item = &self.shared.children[0];
if let ChainItemKind::Comment(..) = item.kind {
self.shared.rewrites.push(root_rewrite);
return Some(());
return Ok(());
}
let child_shape = parent_shape
.visual_indent(self.offset)
.sub_width(self.offset)?;
let rewrite = item.rewrite(context, child_shape)?;
.sub_width(self.offset)
.max_width_error(parent_shape.width, item.span)?;
let rewrite = item.rewrite_result(context, child_shape)?;
if filtered_str_fits(&rewrite, context.config.max_width(), shape) {
root_rewrite.push_str(&rewrite);
} else {
// We couldn't fit in at the visual indent, try the last
// indent.
let rewrite = item.rewrite(context, parent_shape)?;
let rewrite = item.rewrite_result(context, parent_shape)?;
root_rewrite.push_str(&rewrite);
self.offset = 0;
}
Expand All @@ -924,7 +971,7 @@ impl<'a> ChainFormatter for ChainFormatterVisual<'a> {
}

self.shared.rewrites.push(root_rewrite);
Some(())
Ok(())
}

fn child_shape(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<Shape> {
Expand All @@ -937,7 +984,11 @@ impl<'a> ChainFormatter for ChainFormatterVisual<'a> {
)
}

fn format_children(&mut self, context: &RewriteContext<'_>, child_shape: Shape) -> Option<()> {
fn format_children(
&mut self,
context: &RewriteContext<'_>,
child_shape: Shape,
) -> Result<(), RewriteError> {
self.shared.format_children(context, child_shape)
}

Expand All @@ -946,12 +997,12 @@ impl<'a> ChainFormatter for ChainFormatterVisual<'a> {
context: &RewriteContext<'_>,
shape: Shape,
child_shape: Shape,
) -> Option<()> {
) -> Result<(), RewriteError> {
self.shared
.format_last_child(false, context, shape, child_shape)
}

fn join_rewrites(&self, context: &RewriteContext<'_>, child_shape: Shape) -> Option<String> {
fn join_rewrites(&self, context: &RewriteContext<'_>, child_shape: Shape) -> RewriteResult {
self.shared.join_rewrites(context, child_shape)
}

Expand Down
2 changes: 1 addition & 1 deletion src/expr.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -241,7 +241,7 @@ pub(crate) fn format_expr(
ast::ExprKind::Try(..)
| ast::ExprKind::Field(..)
| ast::ExprKind::MethodCall(..)
| ast::ExprKind::Await(_, _) => rewrite_chain(expr, context, shape),
| ast::ExprKind::Await(_, _) => rewrite_chain(expr, context, shape).ok(),
ast::ExprKind::MacCall(ref mac) => {
rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| {
wrap_str(
Expand Down

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