4 use itertools::Itertools;
5 use rustc_ast::token::{Delimiter, LitKind};
6 use rustc_ast::{ast, ptr};
7 use rustc_span::{BytePos, Span};
9 use crate::chains::rewrite_chain;
12 combine_strs_with_missing_comments, contains_comment, recover_comment_removed, rewrite_comment,
13 rewrite_missing_comment, CharClasses, FindUncommented,
15 use crate::config::lists::*;
16 use crate::config::{Config, ControlBraceStyle, HexLiteralCase, IndentStyle, Version};
18 definitive_tactic, itemize_list, shape_for_tactic, struct_lit_formatting, struct_lit_shape,
19 struct_lit_tactic, write_list, ListFormatting, Separator,
21 use crate::macros::{rewrite_macro, MacroPosition};
22 use crate::matches::rewrite_match;
23 use crate::overflow::{self, IntoOverflowableItem, OverflowableItem};
24 use crate::pairs::{rewrite_all_pairs, rewrite_pair, PairParts};
25 use crate::rewrite::{Rewrite, RewriteContext};
26 use crate::shape::{Indent, Shape};
27 use crate::source_map::{LineRangeUtils, SpanUtils};
28 use crate::spanned::Spanned;
29 use crate::string::{rewrite_string, StringFormat};
30 use crate::types::{rewrite_path, PathContext};
32 colon_spaces, contains_skip, count_newlines, first_line_ends_with, inner_attributes,
33 last_line_extendable, last_line_width, mk_sp, outer_attributes, semicolon_for_expr,
34 unicode_str_width, wrap_str,
36 use crate::vertical::rewrite_with_alignment;
37 use crate::visitor::FmtVisitor;
39 impl Rewrite for ast::Expr {
40 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
41 format_expr(self, ExprType::SubExpression, context, shape)
45 #[derive(Copy, Clone, PartialEq)]
46 pub(crate) enum ExprType {
51 pub(crate) fn format_expr(
54 context: &RewriteContext<'_>,
57 skip_out_of_file_lines_range!(context, expr.span);
59 if contains_skip(&*expr.attrs) {
60 return Some(context.snippet(expr.span()).to_owned());
62 let shape = if expr_type == ExprType::Statement && semicolon_for_expr(context, expr) {
68 let expr_rw = match expr.kind {
69 ast::ExprKind::Array(ref expr_vec) => rewrite_array(
75 choose_separator_tactic(context, expr.span),
78 ast::ExprKind::Lit(ref l) => {
79 if let Some(expr_rw) = rewrite_literal(context, l, shape) {
82 if let LitKind::StrRaw(_) = l.token.kind {
83 Some(context.snippet(l.span).trim().into())
89 ast::ExprKind::Call(ref callee, ref args) => {
90 let inner_span = mk_sp(callee.span.hi(), expr.span.hi());
91 let callee_str = callee.rewrite(context, shape)?;
92 rewrite_call(context, &callee_str, args, inner_span, shape)
94 ast::ExprKind::Paren(ref subexpr) => rewrite_paren(context, subexpr, shape, expr.span),
95 ast::ExprKind::Binary(op, ref lhs, ref rhs) => {
96 // FIXME: format comments between operands and operator
97 rewrite_all_pairs(expr, shape, context).or_else(|| {
101 PairParts::infix(&format!(" {} ", context.snippet(op.span))),
104 context.config.binop_separator(),
108 ast::ExprKind::Unary(op, ref subexpr) => rewrite_unary_op(context, op, subexpr, shape),
109 ast::ExprKind::Struct(ref struct_expr) => {
110 let ast::StructExpr {
127 ast::ExprKind::Tup(ref items) => {
128 rewrite_tuple(context, items.iter(), expr.span, shape, items.len() == 1)
130 ast::ExprKind::Let(..) => None,
131 ast::ExprKind::If(..)
132 | ast::ExprKind::ForLoop(..)
133 | ast::ExprKind::Loop(..)
134 | ast::ExprKind::While(..) => to_control_flow(expr, expr_type)
135 .and_then(|control_flow| control_flow.rewrite(context, shape)),
136 ast::ExprKind::ConstBlock(ref anon_const) => {
137 Some(format!("const {}", anon_const.rewrite(context, shape)?))
139 ast::ExprKind::Block(ref block, opt_label) => {
141 ExprType::Statement => {
142 if is_unsafe_block(block) {
143 rewrite_block(block, Some(&expr.attrs), opt_label, context, shape)
144 } else if let rw @ Some(_) =
145 rewrite_empty_block(context, block, Some(&expr.attrs), opt_label, "", shape)
147 // Rewrite block without trying to put it in a single line.
150 let prefix = block_prefix(context, block, shape)?;
152 rewrite_block_with_visitor(
163 ExprType::SubExpression => {
164 rewrite_block(block, Some(&expr.attrs), opt_label, context, shape)
168 ast::ExprKind::Match(ref cond, ref arms) => {
169 rewrite_match(context, cond, arms, shape, expr.span, &expr.attrs)
171 ast::ExprKind::Path(ref qself, ref path) => {
172 rewrite_path(context, PathContext::Expr, qself.as_ref(), path, shape)
174 ast::ExprKind::Assign(ref lhs, ref rhs, _) => {
175 rewrite_assignment(context, lhs, rhs, None, shape)
177 ast::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => {
178 rewrite_assignment(context, lhs, rhs, Some(op), shape)
180 ast::ExprKind::Continue(ref opt_label) => {
181 let id_str = match *opt_label {
182 Some(label) => format!(" {}", label.ident),
183 None => String::new(),
185 Some(format!("continue{}", id_str))
187 ast::ExprKind::Break(ref opt_label, ref opt_expr) => {
188 let id_str = match *opt_label {
189 Some(label) => format!(" {}", label.ident),
190 None => String::new(),
193 if let Some(ref expr) = *opt_expr {
194 rewrite_unary_prefix(context, &format!("break{} ", id_str), &**expr, shape)
196 Some(format!("break{}", id_str))
199 ast::ExprKind::Yield(ref opt_expr) => {
200 if let Some(ref expr) = *opt_expr {
201 rewrite_unary_prefix(context, "yield ", &**expr, shape)
203 Some("yield".to_string())
206 ast::ExprKind::Closure(capture, ref is_async, movability, ref fn_decl, ref body, _) => {
207 closures::rewrite_closure(
208 capture, is_async, movability, fn_decl, body, expr.span, context, shape,
211 ast::ExprKind::Try(..)
212 | ast::ExprKind::Field(..)
213 | ast::ExprKind::MethodCall(..)
214 | ast::ExprKind::Await(_) => rewrite_chain(expr, context, shape),
215 ast::ExprKind::MacCall(ref mac) => {
216 rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| {
218 context.snippet(expr.span).to_owned(),
219 context.config.max_width(),
224 ast::ExprKind::Ret(None) => Some("return".to_owned()),
225 ast::ExprKind::Ret(Some(ref expr)) => {
226 rewrite_unary_prefix(context, "return ", &**expr, shape)
228 ast::ExprKind::Yeet(None) => Some("do yeet".to_owned()),
229 ast::ExprKind::Yeet(Some(ref expr)) => {
230 rewrite_unary_prefix(context, "do yeet ", &**expr, shape)
232 ast::ExprKind::Box(ref expr) => rewrite_unary_prefix(context, "box ", &**expr, shape),
233 ast::ExprKind::AddrOf(borrow_kind, mutability, ref expr) => {
234 rewrite_expr_addrof(context, borrow_kind, mutability, expr, shape)
236 ast::ExprKind::Cast(ref expr, ref ty) => rewrite_pair(
239 PairParts::infix(" as "),
242 SeparatorPlace::Front,
244 ast::ExprKind::Type(ref expr, ref ty) => rewrite_pair(
247 PairParts::infix(": "),
250 SeparatorPlace::Back,
252 ast::ExprKind::Index(ref expr, ref index) => {
253 rewrite_index(&**expr, &**index, context, shape)
255 ast::ExprKind::Repeat(ref expr, ref repeats) => rewrite_pair(
258 PairParts::new("[", "; ", "]"),
261 SeparatorPlace::Back,
263 ast::ExprKind::Range(ref lhs, ref rhs, limits) => {
264 let delim = match limits {
265 ast::RangeLimits::HalfOpen => "..",
266 ast::RangeLimits::Closed => "..=",
269 fn needs_space_before_range(context: &RewriteContext<'_>, lhs: &ast::Expr) -> bool {
271 ast::ExprKind::Lit(ref lit) => match lit.kind {
272 ast::LitKind::Float(_, ast::LitFloatType::Unsuffixed) => {
273 context.snippet(lit.span).ends_with('.')
277 ast::ExprKind::Unary(_, ref expr) => needs_space_before_range(context, expr),
282 fn needs_space_after_range(rhs: &ast::Expr) -> bool {
283 // Don't format `.. ..` into `....`, which is invalid.
285 // This check is unnecessary for `lhs`, because a range
286 // starting from another range needs parentheses as `(x ..) ..`
287 // (`x .. ..` is a range from `x` to `..`).
288 matches!(rhs.kind, ast::ExprKind::Range(None, _, _))
291 let default_sp_delim = |lhs: Option<&ast::Expr>, rhs: Option<&ast::Expr>| {
292 let space_if = |b: bool| if b { " " } else { "" };
296 lhs.map_or("", |lhs| space_if(needs_space_before_range(context, lhs))),
298 rhs.map_or("", |rhs| space_if(needs_space_after_range(rhs))),
302 match (lhs.as_ref().map(|x| &**x), rhs.as_ref().map(|x| &**x)) {
303 (Some(lhs), Some(rhs)) => {
304 let sp_delim = if context.config.spaces_around_ranges() {
305 format!(" {} ", delim)
307 default_sp_delim(Some(lhs), Some(rhs))
312 PairParts::infix(&sp_delim),
315 context.config.binop_separator(),
318 (None, Some(rhs)) => {
319 let sp_delim = if context.config.spaces_around_ranges() {
320 format!("{} ", delim)
322 default_sp_delim(None, Some(rhs))
324 rewrite_unary_prefix(context, &sp_delim, &*rhs, shape)
326 (Some(lhs), None) => {
327 let sp_delim = if context.config.spaces_around_ranges() {
328 format!(" {}", delim)
330 default_sp_delim(Some(lhs), None)
332 rewrite_unary_suffix(context, &sp_delim, &*lhs, shape)
334 (None, None) => Some(delim.to_owned()),
337 // We do not format these expressions yet, but they should still
338 // satisfy our width restrictions.
339 // Style Guide RFC for InlineAsm variant pending
340 // https://github.com/rust-dev-tools/fmt-rfcs/issues/152
341 ast::ExprKind::InlineAsm(..) => Some(context.snippet(expr.span).to_owned()),
342 ast::ExprKind::TryBlock(ref block) => {
343 if let rw @ Some(_) =
344 rewrite_single_line_block(context, "try ", block, Some(&expr.attrs), None, shape)
349 let budget = shape.width.saturating_sub(9);
358 Shape::legacy(budget, shape.indent)
363 ast::ExprKind::Async(capture_by, _node_id, ref block) => {
364 let mover = if capture_by == ast::CaptureBy::Value {
369 if let rw @ Some(_) = rewrite_single_line_block(
371 format!("{}{}", "async ", mover).as_str(),
380 let budget = shape.width.saturating_sub(6);
390 Shape::legacy(budget, shape.indent)
395 ast::ExprKind::Underscore => Some("_".to_owned()),
396 ast::ExprKind::Err => None,
400 .and_then(|expr_str| recover_comment_removed(expr_str, expr.span, context))
401 .and_then(|expr_str| {
402 let attrs = outer_attributes(&expr.attrs);
403 let attrs_str = attrs.rewrite(context, shape)?;
405 attrs.last().map_or(expr.span.lo(), |attr| attr.span.hi()),
408 combine_strs_with_missing_comments(context, &attrs_str, &expr_str, span, shape, false)
412 pub(crate) fn rewrite_array<'a, T: 'a + IntoOverflowableItem<'a>>(
414 exprs: impl Iterator<Item = &'a T>,
416 context: &'a RewriteContext<'_>,
418 force_separator_tactic: Option<SeparatorTactic>,
419 delim_token: Option<Delimiter>,
420 ) -> Option<String> {
421 overflow::rewrite_with_square_brackets(
427 force_separator_tactic,
432 fn rewrite_empty_block(
433 context: &RewriteContext<'_>,
435 attrs: Option<&[ast::Attribute]>,
436 label: Option<ast::Label>,
439 ) -> Option<String> {
440 if block_has_statements(block) {
444 let label_str = rewrite_label(label);
445 if attrs.map_or(false, |a| !inner_attributes(a).is_empty()) {
449 if !block_contains_comment(context, block) && shape.width >= 2 {
450 return Some(format!("{}{}{{}}", prefix, label_str));
453 // If a block contains only a single-line comment, then leave it on one line.
454 let user_str = context.snippet(block.span);
455 let user_str = user_str.trim();
456 if user_str.starts_with('{') && user_str.ends_with('}') {
457 let comment_str = user_str[1..user_str.len() - 1].trim();
458 if block.stmts.is_empty()
459 && !comment_str.contains('\n')
460 && !comment_str.starts_with("//")
461 && comment_str.len() + 4 <= shape.width
463 return Some(format!("{}{}{{ {} }}", prefix, label_str, comment_str));
470 fn block_prefix(context: &RewriteContext<'_>, block: &ast::Block, shape: Shape) -> Option<String> {
471 Some(match block.rules {
472 ast::BlockCheckMode::Unsafe(..) => {
473 let snippet = context.snippet(block.span);
474 let open_pos = snippet.find_uncommented("{")?;
475 // Extract comment between unsafe and block start.
476 let trimmed = &snippet[6..open_pos].trim();
478 if !trimmed.is_empty() {
479 // 9 = "unsafe {".len(), 7 = "unsafe ".len()
480 let budget = shape.width.checked_sub(9)?;
486 Shape::legacy(budget, shape.indent + 7),
494 ast::BlockCheckMode::Default => String::new(),
498 fn rewrite_single_line_block(
499 context: &RewriteContext<'_>,
502 attrs: Option<&[ast::Attribute]>,
503 label: Option<ast::Label>,
505 ) -> Option<String> {
506 if is_simple_block(context, block, attrs) {
507 let expr_shape = shape.offset_left(last_line_width(prefix))?;
508 let expr_str = block.stmts[0].rewrite(context, expr_shape)?;
509 let label_str = rewrite_label(label);
510 let result = format!("{}{}{{ {} }}", prefix, label_str, expr_str);
511 if result.len() <= shape.width && !result.contains('\n') {
518 pub(crate) fn rewrite_block_with_visitor(
519 context: &RewriteContext<'_>,
522 attrs: Option<&[ast::Attribute]>,
523 label: Option<ast::Label>,
526 ) -> Option<String> {
527 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, label, prefix, shape) {
531 let mut visitor = FmtVisitor::from_context(context);
532 visitor.block_indent = shape.indent;
533 visitor.is_if_else_block = context.is_if_else_block();
534 match (block.rules, label) {
535 (ast::BlockCheckMode::Unsafe(..), _) | (ast::BlockCheckMode::Default, Some(_)) => {
536 let snippet = context.snippet(block.span);
537 let open_pos = snippet.find_uncommented("{")?;
538 visitor.last_pos = block.span.lo() + BytePos(open_pos as u32)
540 (ast::BlockCheckMode::Default, None) => visitor.last_pos = block.span.lo(),
543 let inner_attrs = attrs.map(inner_attributes);
544 let label_str = rewrite_label(label);
545 visitor.visit_block(block, inner_attrs.as_deref(), has_braces);
546 let visitor_context = visitor.get_context();
550 .append(&mut visitor_context.skipped_range.borrow_mut());
551 Some(format!("{}{}{}", prefix, label_str, visitor.buffer))
554 impl Rewrite for ast::Block {
555 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
556 rewrite_block(self, None, None, context, shape)
562 attrs: Option<&[ast::Attribute]>,
563 label: Option<ast::Label>,
564 context: &RewriteContext<'_>,
566 ) -> Option<String> {
567 let prefix = block_prefix(context, block, shape)?;
569 // shape.width is used only for the single line case: either the empty block `{}`,
570 // or an unsafe expression `unsafe { e }`.
571 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, label, &prefix, shape) {
575 let result = rewrite_block_with_visitor(context, &prefix, block, attrs, label, shape, true);
576 if let Some(ref result_str) = result {
577 if result_str.lines().count() <= 3 {
578 if let rw @ Some(_) =
579 rewrite_single_line_block(context, &prefix, block, attrs, label, shape)
589 // Rewrite condition if the given expression has one.
590 pub(crate) fn rewrite_cond(
591 context: &RewriteContext<'_>,
594 ) -> Option<String> {
596 ast::ExprKind::Match(ref cond, _) => {
598 let cond_shape = match context.config.indent_style() {
599 IndentStyle::Visual => shape.shrink_left(6).and_then(|s| s.sub_width(2))?,
600 IndentStyle::Block => shape.offset_left(8)?,
602 cond.rewrite(context, cond_shape)
604 _ => to_control_flow(expr, ExprType::SubExpression).and_then(|control_flow| {
606 String::from("\n") + &shape.indent.block_only().to_string(context.config);
608 .rewrite_cond(context, shape, &alt_block_sep)
614 // Abstraction over control flow expressions
616 struct ControlFlow<'a> {
617 cond: Option<&'a ast::Expr>,
618 block: &'a ast::Block,
619 else_block: Option<&'a ast::Expr>,
620 label: Option<ast::Label>,
621 pat: Option<&'a ast::Pat>,
625 allow_single_line: bool,
626 // HACK: `true` if this is an `if` expression in an `else if`.
631 fn extract_pats_and_cond(expr: &ast::Expr) -> (Option<&ast::Pat>, &ast::Expr) {
633 ast::ExprKind::Let(ref pat, ref cond, _) => (Some(pat), cond),
638 // FIXME: Refactor this.
639 fn to_control_flow(expr: &ast::Expr, expr_type: ExprType) -> Option<ControlFlow<'_>> {
641 ast::ExprKind::If(ref cond, ref if_block, ref else_block) => {
642 let (pat, cond) = extract_pats_and_cond(cond);
643 Some(ControlFlow::new_if(
647 else_block.as_ref().map(|e| &**e),
648 expr_type == ExprType::SubExpression,
653 ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
654 Some(ControlFlow::new_for(pat, cond, block, label, expr.span))
656 ast::ExprKind::Loop(ref block, label) => {
657 Some(ControlFlow::new_loop(block, label, expr.span))
659 ast::ExprKind::While(ref cond, ref block, label) => {
660 let (pat, cond) = extract_pats_and_cond(cond);
661 Some(ControlFlow::new_while(pat, cond, block, label, expr.span))
667 fn choose_matcher(pat: Option<&ast::Pat>) -> &'static str {
668 pat.map_or("", |_| "let")
671 impl<'a> ControlFlow<'a> {
674 pat: Option<&'a ast::Pat>,
675 block: &'a ast::Block,
676 else_block: Option<&'a ast::Expr>,
677 allow_single_line: bool,
680 ) -> ControlFlow<'a> {
681 let matcher = choose_matcher(pat);
697 fn new_loop(block: &'a ast::Block, label: Option<ast::Label>, span: Span) -> ControlFlow<'a> {
707 allow_single_line: false,
714 pat: Option<&'a ast::Pat>,
716 block: &'a ast::Block,
717 label: Option<ast::Label>,
719 ) -> ControlFlow<'a> {
720 let matcher = choose_matcher(pat);
730 allow_single_line: false,
739 block: &'a ast::Block,
740 label: Option<ast::Label>,
742 ) -> ControlFlow<'a> {
752 allow_single_line: false,
758 fn rewrite_single_line(
761 context: &RewriteContext<'_>,
763 ) -> Option<String> {
764 assert!(self.allow_single_line);
765 let else_block = self.else_block?;
766 let fixed_cost = self.keyword.len() + " { } else { }".len();
768 if let ast::ExprKind::Block(ref else_node, _) = else_block.kind {
769 if !is_simple_block(context, self.block, None)
770 || !is_simple_block(context, else_node, None)
771 || pat_expr_str.contains('\n')
776 let new_width = width.checked_sub(pat_expr_str.len() + fixed_cost)?;
777 let expr = &self.block.stmts[0];
778 let if_str = expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
780 let new_width = new_width.checked_sub(if_str.len())?;
781 let else_expr = &else_node.stmts[0];
782 let else_str = else_expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
784 if if_str.contains('\n') || else_str.contains('\n') {
788 let result = format!(
789 "{} {} {{ {} }} else {{ {} }}",
790 self.keyword, pat_expr_str, if_str, else_str
793 if result.len() <= width {
802 /// Returns `true` if the last line of pat_str has leading whitespace and it is wider than the
804 fn last_line_offsetted(start_column: usize, pat_str: &str) -> bool {
805 let mut leading_whitespaces = 0;
806 for c in pat_str.chars().rev() {
809 _ if c.is_whitespace() => leading_whitespaces += 1,
810 _ => leading_whitespaces = 0,
813 leading_whitespaces > start_column
816 impl<'a> ControlFlow<'a> {
819 context: &RewriteContext<'_>,
823 ) -> Option<String> {
824 debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, self.pat, expr);
826 let cond_shape = shape.offset_left(offset)?;
827 if let Some(pat) = self.pat {
828 let matcher = if self.matcher.is_empty() {
829 self.matcher.to_owned()
831 format!("{} ", self.matcher)
833 let pat_shape = cond_shape
834 .offset_left(matcher.len())?
835 .sub_width(self.connector.len())?;
836 let pat_string = pat.rewrite(context, pat_shape)?;
837 let comments_lo = context
839 .span_after(self.span.with_lo(pat.span.hi()), self.connector.trim());
840 let comments_span = mk_sp(comments_lo, expr.span.lo());
841 return rewrite_assign_rhs_with_comments(
843 &format!("{}{}{}", matcher, pat_string, self.connector),
846 &RhsAssignKind::Expr(&expr.kind, expr.span),
853 let expr_rw = expr.rewrite(context, cond_shape);
854 // The expression may (partially) fit on the current line.
855 // We do not allow splitting between `if` and condition.
856 if self.keyword == "if" || expr_rw.is_some() {
860 // The expression won't fit on the current line, jump to next.
861 let nested_shape = shape
862 .block_indent(context.config.tab_spaces())
863 .with_max_width(context.config);
864 let nested_indent_str = nested_shape.indent.to_string_with_newline(context.config);
865 expr.rewrite(context, nested_shape)
866 .map(|expr_rw| format!("{}{}", nested_indent_str, expr_rw))
871 context: &RewriteContext<'_>,
874 ) -> Option<(String, usize)> {
875 // Do not take the rhs overhead from the upper expressions into account
876 // when rewriting pattern.
877 let new_width = context.budget(shape.used_width());
878 let fresh_shape = Shape {
882 let constr_shape = if self.nested_if {
883 // We are part of an if-elseif-else chain. Our constraints are tightened.
884 // 7 = "} else " .len()
885 fresh_shape.offset_left(7)?
890 let label_string = rewrite_label(self.label);
891 // 1 = space after keyword.
892 let offset = self.keyword.len() + label_string.len() + 1;
894 let pat_expr_string = match self.cond {
895 Some(cond) => self.rewrite_pat_expr(context, cond, constr_shape, offset)?,
896 None => String::new(),
900 if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
906 let one_line_budget = context
909 .saturating_sub(constr_shape.used_width() + offset + brace_overhead);
910 let force_newline_brace = (pat_expr_string.contains('\n')
911 || pat_expr_string.len() > one_line_budget)
912 && (!last_line_extendable(&pat_expr_string)
913 || last_line_offsetted(shape.used_width(), &pat_expr_string));
915 // Try to format if-else on single line.
916 if self.allow_single_line && context.config.single_line_if_else_max_width() > 0 {
917 let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width);
919 if let Some(cond_str) = trial {
920 if cond_str.len() <= context.config.single_line_if_else_max_width() {
921 return Some((cond_str, 0));
926 let cond_span = if let Some(cond) = self.cond {
929 mk_sp(self.block.span.lo(), self.block.span.lo())
932 // `for event in event`
933 // Do not include label in the span.
936 .map_or(self.span.lo(), |label| label.ident.span.hi());
937 let between_kwd_cond = mk_sp(
940 .span_after(mk_sp(lo, self.span.hi()), self.keyword.trim()),
941 if self.pat.is_none() {
943 } else if self.matcher.is_empty() {
944 self.pat.unwrap().span.lo()
948 .span_before(self.span, self.matcher.trim())
952 let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape);
954 let after_cond_comment =
955 extract_comment(mk_sp(cond_span.hi(), self.block.span.lo()), context, shape);
957 let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
959 } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine
960 || force_newline_brace
967 let used_width = if pat_expr_string.contains('\n') {
968 last_line_width(&pat_expr_string)
970 // 2 = spaces after keyword and condition.
971 label_string.len() + self.keyword.len() + pat_expr_string.len() + 2
979 between_kwd_cond_comment.as_ref().map_or(
980 if pat_expr_string.is_empty() || pat_expr_string.starts_with('\n') {
988 after_cond_comment.as_ref().map_or(block_sep, |s| &**s)
995 impl<'a> Rewrite for ControlFlow<'a> {
996 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
997 debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
999 let alt_block_sep = &shape.indent.to_string_with_newline(context.config);
1000 let (cond_str, used_width) = self.rewrite_cond(context, shape, alt_block_sep)?;
1001 // If `used_width` is 0, it indicates that whole control flow is written in a single line.
1002 if used_width == 0 {
1003 return Some(cond_str);
1006 let block_width = shape.width.saturating_sub(used_width);
1007 // This is used only for the empty block case: `{}`. So, we use 1 if we know
1008 // we should avoid the single line case.
1009 let block_width = if self.else_block.is_some() || self.nested_if {
1014 let block_shape = Shape {
1019 let old_val = context.is_if_else_block.replace(self.else_block.is_some());
1021 rewrite_block_with_visitor(context, "", self.block, None, None, block_shape, true);
1022 context.is_if_else_block.replace(old_val);
1026 let mut result = format!("{}{}", cond_str, block_str);
1028 if let Some(else_block) = self.else_block {
1029 let shape = Shape::indented(shape.indent, context.config);
1030 let mut last_in_chain = false;
1031 let rewrite = match else_block.kind {
1032 // If the else expression is another if-else expression, prevent it
1033 // from being formatted on a single line.
1034 // Note how we're passing the original shape, as the
1035 // cost of "else" should not cascade.
1036 ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => {
1037 let (pats, cond) = extract_pats_and_cond(cond);
1038 ControlFlow::new_if(
1042 next_else_block.as_ref().map(|e| &**e),
1045 mk_sp(else_block.span.lo(), self.span.hi()),
1047 .rewrite(context, shape)
1050 last_in_chain = true;
1051 // When rewriting a block, the width is only used for single line
1052 // blocks, passing 1 lets us avoid that.
1053 let else_shape = Shape {
1054 width: min(1, shape.width),
1057 format_expr(else_block, ExprType::Statement, context, else_shape)
1061 let between_kwd_else_block = mk_sp(
1062 self.block.span.hi(),
1065 .span_before(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1067 let between_kwd_else_block_comment =
1068 extract_comment(between_kwd_else_block, context, shape);
1070 let after_else = mk_sp(
1073 .span_after(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1074 else_block.span.lo(),
1076 let after_else_comment = extract_comment(after_else, context, shape);
1078 let between_sep = match context.config.control_brace_style() {
1079 ControlBraceStyle::AlwaysNextLine | ControlBraceStyle::ClosingNextLine => {
1082 ControlBraceStyle::AlwaysSameLine => " ",
1084 let after_sep = match context.config.control_brace_style() {
1085 ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep,
1089 result.push_str(&format!(
1091 between_kwd_else_block_comment
1093 .map_or(between_sep, |s| &**s),
1094 after_else_comment.as_ref().map_or(after_sep, |s| &**s),
1096 result.push_str(&rewrite?);
1103 fn rewrite_label(opt_label: Option<ast::Label>) -> Cow<'static, str> {
1105 Some(label) => Cow::from(format!("{}: ", label.ident)),
1106 None => Cow::from(""),
1110 fn extract_comment(span: Span, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1111 match rewrite_missing_comment(span, shape, context) {
1112 Some(ref comment) if !comment.is_empty() => Some(format!(
1113 "{indent}{}{indent}",
1115 indent = shape.indent.to_string_with_newline(context.config)
1121 pub(crate) fn block_contains_comment(context: &RewriteContext<'_>, block: &ast::Block) -> bool {
1122 contains_comment(context.snippet(block.span))
1125 // Checks that a block contains no statements, an expression and no comments or
1127 // FIXME: incorrectly returns false when comment is contained completely within
1129 pub(crate) fn is_simple_block(
1130 context: &RewriteContext<'_>,
1132 attrs: Option<&[ast::Attribute]>,
1134 block.stmts.len() == 1
1135 && stmt_is_expr(&block.stmts[0])
1136 && !block_contains_comment(context, block)
1137 && attrs.map_or(true, |a| a.is_empty())
1140 /// Checks whether a block contains at most one statement or expression, and no
1141 /// comments or attributes.
1142 pub(crate) fn is_simple_block_stmt(
1143 context: &RewriteContext<'_>,
1145 attrs: Option<&[ast::Attribute]>,
1147 block.stmts.len() <= 1
1148 && !block_contains_comment(context, block)
1149 && attrs.map_or(true, |a| a.is_empty())
1152 fn block_has_statements(block: &ast::Block) -> bool {
1156 .any(|stmt| !matches!(stmt.kind, ast::StmtKind::Empty))
1159 /// Checks whether a block contains no statements, expressions, comments, or
1160 /// inner attributes.
1161 pub(crate) fn is_empty_block(
1162 context: &RewriteContext<'_>,
1164 attrs: Option<&[ast::Attribute]>,
1166 !block_has_statements(block)
1167 && !block_contains_comment(context, block)
1168 && attrs.map_or(true, |a| inner_attributes(a).is_empty())
1171 pub(crate) fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
1172 matches!(stmt.kind, ast::StmtKind::Expr(..))
1175 pub(crate) fn is_unsafe_block(block: &ast::Block) -> bool {
1176 matches!(block.rules, ast::BlockCheckMode::Unsafe(..))
1179 pub(crate) fn rewrite_literal(
1180 context: &RewriteContext<'_>,
1183 ) -> Option<String> {
1185 ast::LitKind::Str(_, ast::StrStyle::Cooked) => rewrite_string_lit(context, l.span, shape),
1186 ast::LitKind::Int(..) => rewrite_int_lit(context, l, shape),
1188 context.snippet(l.span).to_owned(),
1189 context.config.max_width(),
1195 fn rewrite_string_lit(context: &RewriteContext<'_>, span: Span, shape: Shape) -> Option<String> {
1196 let string_lit = context.snippet(span);
1198 if !context.config.format_strings() {
1202 .all(|line| line.ends_with('\\'))
1203 && context.config.version() == Version::Two
1205 return Some(string_lit.to_owned());
1207 return wrap_str(string_lit.to_owned(), context.config.max_width(), shape);
1211 // Remove the quote characters.
1212 let str_lit = &string_lit[1..string_lit.len() - 1];
1216 &StringFormat::new(shape.visual_indent(0), context.config),
1217 shape.width.saturating_sub(2),
1221 fn rewrite_int_lit(context: &RewriteContext<'_>, lit: &ast::Lit, shape: Shape) -> Option<String> {
1222 let span = lit.span;
1223 let symbol = lit.token.symbol.as_str();
1225 if let Some(symbol_stripped) = symbol.strip_prefix("0x") {
1226 let hex_lit = match context.config.hex_literal_case() {
1227 HexLiteralCase::Preserve => None,
1228 HexLiteralCase::Upper => Some(symbol_stripped.to_ascii_uppercase()),
1229 HexLiteralCase::Lower => Some(symbol_stripped.to_ascii_lowercase()),
1231 if let Some(hex_lit) = hex_lit {
1236 lit.token.suffix.map_or(String::new(), |s| s.to_string())
1238 context.config.max_width(),
1245 context.snippet(span).to_owned(),
1246 context.config.max_width(),
1251 fn choose_separator_tactic(context: &RewriteContext<'_>, span: Span) -> Option<SeparatorTactic> {
1252 if context.inside_macro() {
1253 if span_ends_with_comma(context, span) {
1254 Some(SeparatorTactic::Always)
1256 Some(SeparatorTactic::Never)
1263 pub(crate) fn rewrite_call(
1264 context: &RewriteContext<'_>,
1266 args: &[ptr::P<ast::Expr>],
1269 ) -> Option<String> {
1270 overflow::rewrite_with_parens(
1276 context.config.fn_call_width(),
1277 choose_separator_tactic(context, span),
1281 pub(crate) fn is_simple_expr(expr: &ast::Expr) -> bool {
1283 ast::ExprKind::Lit(..) => true,
1284 ast::ExprKind::Path(ref qself, ref path) => qself.is_none() && path.segments.len() <= 1,
1285 ast::ExprKind::AddrOf(_, _, ref expr)
1286 | ast::ExprKind::Box(ref expr)
1287 | ast::ExprKind::Cast(ref expr, _)
1288 | ast::ExprKind::Field(ref expr, _)
1289 | ast::ExprKind::Try(ref expr)
1290 | ast::ExprKind::Unary(_, ref expr) => is_simple_expr(expr),
1291 ast::ExprKind::Index(ref lhs, ref rhs) => is_simple_expr(lhs) && is_simple_expr(rhs),
1292 ast::ExprKind::Repeat(ref lhs, ref rhs) => {
1293 is_simple_expr(lhs) && is_simple_expr(&*rhs.value)
1299 pub(crate) fn is_every_expr_simple(lists: &[OverflowableItem<'_>]) -> bool {
1300 lists.iter().all(OverflowableItem::is_simple)
1303 pub(crate) fn can_be_overflowed_expr(
1304 context: &RewriteContext<'_>,
1309 _ if !expr.attrs.is_empty() => false,
1310 ast::ExprKind::Match(..) => {
1311 (context.use_block_indent() && args_len == 1)
1312 || (context.config.indent_style() == IndentStyle::Visual && args_len > 1)
1313 || context.config.overflow_delimited_expr()
1315 ast::ExprKind::If(..)
1316 | ast::ExprKind::ForLoop(..)
1317 | ast::ExprKind::Loop(..)
1318 | ast::ExprKind::While(..) => {
1319 context.config.combine_control_expr() && context.use_block_indent() && args_len == 1
1322 // Handle always block-like expressions
1323 ast::ExprKind::Async(..) | ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => true,
1325 // Handle `[]` and `{}`-like expressions
1326 ast::ExprKind::Array(..) | ast::ExprKind::Struct(..) => {
1327 context.config.overflow_delimited_expr()
1328 || (context.use_block_indent() && args_len == 1)
1330 ast::ExprKind::MacCall(ref mac) => {
1332 rustc_ast::ast::MacDelimiter::from_token(mac.args.delim().unwrap()),
1333 context.config.overflow_delimited_expr(),
1335 (Some(ast::MacDelimiter::Bracket), true)
1336 | (Some(ast::MacDelimiter::Brace), true) => true,
1337 _ => context.use_block_indent() && args_len == 1,
1341 // Handle parenthetical expressions
1342 ast::ExprKind::Call(..) | ast::ExprKind::MethodCall(..) | ast::ExprKind::Tup(..) => {
1343 context.use_block_indent() && args_len == 1
1346 // Handle unary-like expressions
1347 ast::ExprKind::AddrOf(_, _, ref expr)
1348 | ast::ExprKind::Box(ref expr)
1349 | ast::ExprKind::Try(ref expr)
1350 | ast::ExprKind::Unary(_, ref expr)
1351 | ast::ExprKind::Cast(ref expr, _) => can_be_overflowed_expr(context, expr, args_len),
1356 pub(crate) fn is_nested_call(expr: &ast::Expr) -> bool {
1358 ast::ExprKind::Call(..) | ast::ExprKind::MacCall(..) => true,
1359 ast::ExprKind::AddrOf(_, _, ref expr)
1360 | ast::ExprKind::Box(ref expr)
1361 | ast::ExprKind::Try(ref expr)
1362 | ast::ExprKind::Unary(_, ref expr)
1363 | ast::ExprKind::Cast(ref expr, _) => is_nested_call(expr),
1368 /// Returns `true` if a function call or a method call represented by the given span ends with a
1369 /// trailing comma. This function is used when rewriting macro, as adding or removing a trailing
1370 /// comma from macro can potentially break the code.
1371 pub(crate) fn span_ends_with_comma(context: &RewriteContext<'_>, span: Span) -> bool {
1372 let mut result: bool = Default::default();
1373 let mut prev_char: char = Default::default();
1374 let closing_delimiters = &[')', '}', ']'];
1376 for (kind, c) in CharClasses::new(context.snippet(span).chars()) {
1378 _ if kind.is_comment() || c.is_whitespace() => continue,
1379 c if closing_delimiters.contains(&c) => {
1380 result &= !closing_delimiters.contains(&prev_char);
1382 ',' => result = true,
1383 _ => result = false,
1392 context: &RewriteContext<'_>,
1393 mut subexpr: &ast::Expr,
1396 ) -> Option<String> {
1397 debug!("rewrite_paren, shape: {:?}", shape);
1399 // Extract comments within parens.
1402 let mut pre_comment;
1403 let mut post_comment;
1404 let remove_nested_parens = context.config.remove_nested_parens();
1407 pre_span = mk_sp(span.lo() + BytePos(1), subexpr.span.lo());
1408 post_span = mk_sp(subexpr.span.hi(), span.hi() - BytePos(1));
1409 pre_comment = rewrite_missing_comment(pre_span, shape, context)?;
1410 post_comment = rewrite_missing_comment(post_span, shape, context)?;
1412 // Remove nested parens if there are no comments.
1413 if let ast::ExprKind::Paren(ref subsubexpr) = subexpr.kind {
1414 if remove_nested_parens && pre_comment.is_empty() && post_comment.is_empty() {
1415 span = subexpr.span;
1416 subexpr = subsubexpr;
1425 let sub_shape = shape.offset_left(1)?.sub_width(1)?;
1426 let subexpr_str = subexpr.rewrite(context, sub_shape)?;
1427 let fits_single_line = !pre_comment.contains("//") && !post_comment.contains("//");
1428 if fits_single_line {
1429 Some(format!("({}{}{})", pre_comment, subexpr_str, post_comment))
1431 rewrite_paren_in_multi_line(context, subexpr, shape, pre_span, post_span)
1435 fn rewrite_paren_in_multi_line(
1436 context: &RewriteContext<'_>,
1437 subexpr: &ast::Expr,
1441 ) -> Option<String> {
1442 let nested_indent = shape.indent.block_indent(context.config);
1443 let nested_shape = Shape::indented(nested_indent, context.config);
1444 let pre_comment = rewrite_missing_comment(pre_span, nested_shape, context)?;
1445 let post_comment = rewrite_missing_comment(post_span, nested_shape, context)?;
1446 let subexpr_str = subexpr.rewrite(context, nested_shape)?;
1448 let mut result = String::with_capacity(subexpr_str.len() * 2);
1450 if !pre_comment.is_empty() {
1451 result.push_str(&nested_indent.to_string_with_newline(context.config));
1452 result.push_str(&pre_comment);
1454 result.push_str(&nested_indent.to_string_with_newline(context.config));
1455 result.push_str(&subexpr_str);
1456 if !post_comment.is_empty() {
1457 result.push_str(&nested_indent.to_string_with_newline(context.config));
1458 result.push_str(&post_comment);
1460 result.push_str(&shape.indent.to_string_with_newline(context.config));
1469 context: &RewriteContext<'_>,
1471 ) -> Option<String> {
1472 let expr_str = expr.rewrite(context, shape)?;
1474 let offset = last_line_width(&expr_str) + 1;
1475 let rhs_overhead = shape.rhs_overhead(context.config);
1476 let index_shape = if expr_str.contains('\n') {
1477 Shape::legacy(context.config.max_width(), shape.indent)
1478 .offset_left(offset)
1479 .and_then(|shape| shape.sub_width(1 + rhs_overhead))
1481 match context.config.indent_style() {
1482 IndentStyle::Block => shape
1483 .offset_left(offset)
1484 .and_then(|shape| shape.sub_width(1)),
1485 IndentStyle::Visual => shape.visual_indent(offset).sub_width(offset + 1),
1488 let orig_index_rw = index_shape.and_then(|s| index.rewrite(context, s));
1490 // Return if index fits in a single line.
1491 match orig_index_rw {
1492 Some(ref index_str) if !index_str.contains('\n') => {
1493 return Some(format!("{}[{}]", expr_str, index_str));
1498 // Try putting index on the next line and see if it fits in a single line.
1499 let indent = shape.indent.block_indent(context.config);
1500 let index_shape = Shape::indented(indent, context.config).offset_left(1)?;
1501 let index_shape = index_shape.sub_width(1 + rhs_overhead)?;
1502 let new_index_rw = index.rewrite(context, index_shape);
1503 match (orig_index_rw, new_index_rw) {
1504 (_, Some(ref new_index_str)) if !new_index_str.contains('\n') => Some(format!(
1507 indent.to_string_with_newline(context.config),
1510 (None, Some(ref new_index_str)) => Some(format!(
1513 indent.to_string_with_newline(context.config),
1516 (Some(ref index_str), _) => Some(format!("{}[{}]", expr_str, index_str)),
1521 fn struct_lit_can_be_aligned(fields: &[ast::ExprField], has_base: bool) -> bool {
1522 !has_base && fields.iter().all(|field| !field.is_shorthand)
1525 fn rewrite_struct_lit<'a>(
1526 context: &RewriteContext<'_>,
1528 qself: Option<&ast::QSelf>,
1529 fields: &'a [ast::ExprField],
1530 struct_rest: &ast::StructRest,
1531 attrs: &[ast::Attribute],
1534 ) -> Option<String> {
1535 debug!("rewrite_struct_lit: shape {:?}", shape);
1537 enum StructLitField<'a> {
1538 Regular(&'a ast::ExprField),
1539 Base(&'a ast::Expr),
1544 let path_shape = shape.sub_width(2)?;
1545 let path_str = rewrite_path(context, PathContext::Expr, qself, path, path_shape)?;
1547 let has_base_or_rest = match struct_rest {
1548 ast::StructRest::None if fields.is_empty() => return Some(format!("{} {{}}", path_str)),
1549 ast::StructRest::Rest(_) if fields.is_empty() => {
1550 return Some(format!("{} {{ .. }}", path_str));
1552 ast::StructRest::Rest(_) | ast::StructRest::Base(_) => true,
1556 // Foo { a: Foo } - indent is +3, width is -5.
1557 let (h_shape, v_shape) = struct_lit_shape(shape, context, path_str.len() + 3, 2)?;
1559 let one_line_width = h_shape.map_or(0, |shape| shape.width);
1560 let body_lo = context.snippet_provider.span_after(span, "{");
1561 let fields_str = if struct_lit_can_be_aligned(fields, has_base_or_rest)
1562 && context.config.struct_field_align_threshold() > 0
1564 rewrite_with_alignment(
1568 mk_sp(body_lo, span.hi()),
1572 let field_iter = fields.iter().map(StructLitField::Regular).chain(
1574 ast::StructRest::Base(expr) => Some(StructLitField::Base(&**expr)),
1575 ast::StructRest::Rest(span) => Some(StructLitField::Rest(*span)),
1576 ast::StructRest::None => None,
1581 let span_lo = |item: &StructLitField<'_>| match *item {
1582 StructLitField::Regular(field) => field.span().lo(),
1583 StructLitField::Base(expr) => {
1584 let last_field_hi = fields.last().map_or(span.lo(), |field| field.span.hi());
1585 let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo()));
1586 let pos = snippet.find_uncommented("..").unwrap();
1587 last_field_hi + BytePos(pos as u32)
1589 StructLitField::Rest(span) => span.lo(),
1591 let span_hi = |item: &StructLitField<'_>| match *item {
1592 StructLitField::Regular(field) => field.span().hi(),
1593 StructLitField::Base(expr) => expr.span.hi(),
1594 StructLitField::Rest(span) => span.hi(),
1596 let rewrite = |item: &StructLitField<'_>| match *item {
1597 StructLitField::Regular(field) => {
1598 // The 1 taken from the v_budget is for the comma.
1599 rewrite_field(context, field, v_shape.sub_width(1)?, 0)
1601 StructLitField::Base(expr) => {
1603 expr.rewrite(context, v_shape.offset_left(2)?)
1604 .map(|s| format!("..{}", s))
1606 StructLitField::Rest(_) => Some("..".to_owned()),
1609 let items = itemize_list(
1610 context.snippet_provider,
1621 let item_vec = items.collect::<Vec<_>>();
1623 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
1624 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
1626 let ends_with_comma = span_ends_with_comma(context, span);
1627 let force_no_trailing_comma = context.inside_macro() && !ends_with_comma;
1629 let fmt = struct_lit_formatting(
1633 force_no_trailing_comma || has_base_or_rest || !context.use_block_indent(),
1636 write_list(&item_vec, &fmt)?
1640 wrap_struct_field(context, attrs, &fields_str, shape, v_shape, one_line_width)?;
1641 Some(format!("{} {{{}}}", path_str, fields_str))
1643 // FIXME if context.config.indent_style() == Visual, but we run out
1644 // of space, we should fall back to BlockIndent.
1647 pub(crate) fn wrap_struct_field(
1648 context: &RewriteContext<'_>,
1649 attrs: &[ast::Attribute],
1652 nested_shape: Shape,
1653 one_line_width: usize,
1654 ) -> Option<String> {
1655 let should_vertical = context.config.indent_style() == IndentStyle::Block
1656 && (fields_str.contains('\n')
1657 || !context.config.struct_lit_single_line()
1658 || fields_str.len() > one_line_width);
1660 let inner_attrs = &inner_attributes(attrs);
1661 if inner_attrs.is_empty() {
1662 if should_vertical {
1665 nested_shape.indent.to_string_with_newline(context.config),
1667 shape.indent.to_string_with_newline(context.config)
1670 // One liner or visual indent.
1671 Some(format!(" {} ", fields_str))
1676 nested_shape.indent.to_string_with_newline(context.config),
1677 inner_attrs.rewrite(context, shape)?,
1678 nested_shape.indent.to_string_with_newline(context.config),
1680 shape.indent.to_string_with_newline(context.config)
1685 pub(crate) fn struct_lit_field_separator(config: &Config) -> &str {
1686 colon_spaces(config)
1689 pub(crate) fn rewrite_field(
1690 context: &RewriteContext<'_>,
1691 field: &ast::ExprField,
1693 prefix_max_width: usize,
1694 ) -> Option<String> {
1695 if contains_skip(&field.attrs) {
1696 return Some(context.snippet(field.span()).to_owned());
1698 let mut attrs_str = field.attrs.rewrite(context, shape)?;
1699 if !attrs_str.is_empty() {
1700 attrs_str.push_str(&shape.indent.to_string_with_newline(context.config));
1702 let name = context.snippet(field.ident.span);
1703 if field.is_shorthand {
1704 Some(attrs_str + name)
1706 let mut separator = String::from(struct_lit_field_separator(context.config));
1707 for _ in 0..prefix_max_width.saturating_sub(name.len()) {
1708 separator.push(' ');
1710 let overhead = name.len() + separator.len();
1711 let expr_shape = shape.offset_left(overhead)?;
1712 let expr = field.expr.rewrite(context, expr_shape);
1715 Some(ref e) if e.as_str() == name && context.config.use_field_init_shorthand() => {
1716 Some(attrs_str + name)
1718 Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)),
1720 let expr_offset = shape.indent.block_indent(context.config);
1723 .rewrite(context, Shape::indented(expr_offset, context.config));
1729 expr_offset.to_string(context.config),
1738 fn rewrite_tuple_in_visual_indent_style<'a, T: 'a + IntoOverflowableItem<'a>>(
1739 context: &RewriteContext<'_>,
1740 mut items: impl Iterator<Item = &'a T>,
1743 is_singleton_tuple: bool,
1744 ) -> Option<String> {
1745 // In case of length 1, need a trailing comma
1746 debug!("rewrite_tuple_in_visual_indent_style {:?}", shape);
1747 if is_singleton_tuple {
1749 let nested_shape = shape.sub_width(3)?.visual_indent(1);
1753 .rewrite(context, nested_shape)
1754 .map(|s| format!("({},)", s));
1757 let list_lo = context.snippet_provider.span_after(span, "(");
1758 let nested_shape = shape.sub_width(2)?.visual_indent(1);
1759 let items = itemize_list(
1760 context.snippet_provider,
1764 |item| item.span().lo(),
1765 |item| item.span().hi(),
1766 |item| item.rewrite(context, nested_shape),
1768 span.hi() - BytePos(1),
1771 let item_vec: Vec<_> = items.collect();
1772 let tactic = definitive_tactic(
1774 ListTactic::HorizontalVertical,
1778 let fmt = ListFormatting::new(nested_shape, context.config)
1780 .ends_with_newline(false);
1781 let list_str = write_list(&item_vec, &fmt)?;
1783 Some(format!("({})", list_str))
1786 pub(crate) fn rewrite_tuple<'a, T: 'a + IntoOverflowableItem<'a>>(
1787 context: &'a RewriteContext<'_>,
1788 items: impl Iterator<Item = &'a T>,
1791 is_singleton_tuple: bool,
1792 ) -> Option<String> {
1793 debug!("rewrite_tuple {:?}", shape);
1794 if context.use_block_indent() {
1795 // We use the same rule as function calls for rewriting tuples.
1796 let force_tactic = if context.inside_macro() {
1797 if span_ends_with_comma(context, span) {
1798 Some(SeparatorTactic::Always)
1800 Some(SeparatorTactic::Never)
1802 } else if is_singleton_tuple {
1803 Some(SeparatorTactic::Always)
1807 overflow::rewrite_with_parens(
1813 context.config.fn_call_width(),
1817 rewrite_tuple_in_visual_indent_style(context, items, span, shape, is_singleton_tuple)
1821 pub(crate) fn rewrite_unary_prefix<R: Rewrite>(
1822 context: &RewriteContext<'_>,
1826 ) -> Option<String> {
1828 .rewrite(context, shape.offset_left(prefix.len())?)
1829 .map(|r| format!("{}{}", prefix, r))
1832 // FIXME: this is probably not correct for multi-line Rewrites. we should
1833 // subtract suffix.len() from the last line budget, not the first!
1834 pub(crate) fn rewrite_unary_suffix<R: Rewrite>(
1835 context: &RewriteContext<'_>,
1839 ) -> Option<String> {
1841 .rewrite(context, shape.sub_width(suffix.len())?)
1848 fn rewrite_unary_op(
1849 context: &RewriteContext<'_>,
1853 ) -> Option<String> {
1854 // For some reason, an UnOp is not spanned like BinOp!
1855 rewrite_unary_prefix(context, ast::UnOp::to_string(op), expr, shape)
1858 pub(crate) enum RhsAssignKind<'ast> {
1859 Expr(&'ast ast::ExprKind, Span),
1864 impl<'ast> RhsAssignKind<'ast> {
1865 // TODO(calebcartwright)
1866 // Preemptive addition for handling RHS with chains, not yet utilized.
1867 // It may make more sense to construct the chain first and then check
1868 // whether there are actually chain elements.
1870 fn is_chain(&self) -> bool {
1872 RhsAssignKind::Expr(kind, _) => {
1875 ast::ExprKind::Try(..)
1876 | ast::ExprKind::Field(..)
1877 | ast::ExprKind::MethodCall(..)
1878 | ast::ExprKind::Await(_)
1886 fn rewrite_assignment(
1887 context: &RewriteContext<'_>,
1890 op: Option<&ast::BinOp>,
1892 ) -> Option<String> {
1893 let operator_str = match op {
1894 Some(op) => context.snippet(op.span),
1898 // 1 = space between lhs and operator.
1899 let lhs_shape = shape.sub_width(operator_str.len() + 1)?;
1900 let lhs_str = format!("{} {}", lhs.rewrite(context, lhs_shape)?, operator_str);
1906 &RhsAssignKind::Expr(&rhs.kind, rhs.span),
1911 /// Controls where to put the rhs.
1912 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
1913 pub(crate) enum RhsTactics {
1916 /// Put the rhs on the next line if it uses multiple line, without extra indentation.
1917 ForceNextLineWithoutIndent,
1918 /// Allow overflowing max width if neither `Default` nor `ForceNextLineWithoutIndent`
1923 // The left hand side must contain everything up to, and including, the
1924 // assignment operator.
1925 pub(crate) fn rewrite_assign_rhs<S: Into<String>, R: Rewrite>(
1926 context: &RewriteContext<'_>,
1929 rhs_kind: &RhsAssignKind<'_>,
1931 ) -> Option<String> {
1932 rewrite_assign_rhs_with(context, lhs, ex, shape, rhs_kind, RhsTactics::Default)
1935 pub(crate) fn rewrite_assign_rhs_expr<R: Rewrite>(
1936 context: &RewriteContext<'_>,
1940 rhs_kind: &RhsAssignKind<'_>,
1941 rhs_tactics: RhsTactics,
1942 ) -> Option<String> {
1943 let last_line_width = last_line_width(lhs).saturating_sub(if lhs.contains('\n') {
1944 shape.indent.width()
1948 // 1 = space between operator and rhs.
1949 let orig_shape = shape.offset_left(last_line_width + 1).unwrap_or(Shape {
1951 offset: shape.offset + last_line_width + 1,
1954 let has_rhs_comment = if let Some(offset) = lhs.find_last_uncommented("=") {
1955 lhs.trim_end().len() > offset + 1
1964 ex.rewrite(context, orig_shape),
1971 pub(crate) fn rewrite_assign_rhs_with<S: Into<String>, R: Rewrite>(
1972 context: &RewriteContext<'_>,
1976 rhs_kind: &RhsAssignKind<'_>,
1977 rhs_tactics: RhsTactics,
1978 ) -> Option<String> {
1979 let lhs = lhs.into();
1980 let rhs = rewrite_assign_rhs_expr(context, &lhs, ex, shape, rhs_kind, rhs_tactics)?;
1984 pub(crate) fn rewrite_assign_rhs_with_comments<S: Into<String>, R: Rewrite>(
1985 context: &RewriteContext<'_>,
1989 rhs_kind: &RhsAssignKind<'_>,
1990 rhs_tactics: RhsTactics,
1993 ) -> Option<String> {
1994 let lhs = lhs.into();
1995 let contains_comment = contains_comment(context.snippet(between_span));
1996 let shape = if contains_comment {
1997 shape.block_left(context.config.tab_spaces())?
2001 let rhs = rewrite_assign_rhs_expr(context, &lhs, ex, shape, rhs_kind, rhs_tactics)?;
2003 if contains_comment {
2004 let rhs = rhs.trim_start();
2005 combine_strs_with_missing_comments(context, &lhs, rhs, between_span, shape, allow_extend)
2011 fn choose_rhs<R: Rewrite>(
2012 context: &RewriteContext<'_>,
2015 orig_rhs: Option<String>,
2016 _rhs_kind: &RhsAssignKind<'_>,
2017 rhs_tactics: RhsTactics,
2018 has_rhs_comment: bool,
2019 ) -> Option<String> {
2021 Some(ref new_str) if new_str.is_empty() => Some(String::new()),
2023 if !new_str.contains('\n') && unicode_str_width(new_str) <= shape.width =>
2025 Some(format!(" {}", new_str))
2028 // Expression did not fit on the same line as the identifier.
2029 // Try splitting the line and see if that works better.
2030 let new_shape = shape_from_rhs_tactic(context, shape, rhs_tactics)?;
2031 let new_rhs = expr.rewrite(context, new_shape);
2032 let new_indent_str = &shape
2034 .block_indent(context.config)
2035 .to_string_with_newline(context.config);
2036 let before_space_str = if has_rhs_comment { "" } else { " " };
2038 match (orig_rhs, new_rhs) {
2039 (Some(ref orig_rhs), Some(ref new_rhs))
2040 if wrap_str(new_rhs.clone(), context.config.max_width(), new_shape)
2043 Some(format!("{}{}", before_space_str, orig_rhs))
2045 (Some(ref orig_rhs), Some(ref new_rhs))
2046 if prefer_next_line(orig_rhs, new_rhs, rhs_tactics) =>
2048 Some(format!("{}{}", new_indent_str, new_rhs))
2050 (None, Some(ref new_rhs)) => Some(format!("{}{}", new_indent_str, new_rhs)),
2051 (None, None) if rhs_tactics == RhsTactics::AllowOverflow => {
2052 let shape = shape.infinite_width();
2053 expr.rewrite(context, shape)
2054 .map(|s| format!("{}{}", before_space_str, s))
2056 (None, None) => None,
2057 (Some(orig_rhs), _) => Some(format!("{}{}", before_space_str, orig_rhs)),
2063 fn shape_from_rhs_tactic(
2064 context: &RewriteContext<'_>,
2066 rhs_tactic: RhsTactics,
2067 ) -> Option<Shape> {
2069 RhsTactics::ForceNextLineWithoutIndent => shape
2070 .with_max_width(context.config)
2071 .sub_width(shape.indent.width()),
2072 RhsTactics::Default | RhsTactics::AllowOverflow => {
2073 Shape::indented(shape.indent.block_indent(context.config), context.config)
2074 .sub_width(shape.rhs_overhead(context.config))
2079 /// Returns true if formatting next_line_rhs is better on a new line when compared to the
2080 /// original's line formatting.
2082 /// It is considered better if:
2083 /// 1. the tactic is ForceNextLineWithoutIndent
2084 /// 2. next_line_rhs doesn't have newlines
2085 /// 3. the original line has more newlines than next_line_rhs
2086 /// 4. the original formatting of the first line ends with `(`, `{`, or `[` and next_line_rhs
2088 pub(crate) fn prefer_next_line(
2090 next_line_rhs: &str,
2091 rhs_tactics: RhsTactics,
2093 rhs_tactics == RhsTactics::ForceNextLineWithoutIndent
2094 || !next_line_rhs.contains('\n')
2095 || count_newlines(orig_rhs) > count_newlines(next_line_rhs) + 1
2096 || first_line_ends_with(orig_rhs, '(') && !first_line_ends_with(next_line_rhs, '(')
2097 || first_line_ends_with(orig_rhs, '{') && !first_line_ends_with(next_line_rhs, '{')
2098 || first_line_ends_with(orig_rhs, '[') && !first_line_ends_with(next_line_rhs, '[')
2101 fn rewrite_expr_addrof(
2102 context: &RewriteContext<'_>,
2103 borrow_kind: ast::BorrowKind,
2104 mutability: ast::Mutability,
2107 ) -> Option<String> {
2108 let operator_str = match (mutability, borrow_kind) {
2109 (ast::Mutability::Not, ast::BorrowKind::Ref) => "&",
2110 (ast::Mutability::Not, ast::BorrowKind::Raw) => "&raw const ",
2111 (ast::Mutability::Mut, ast::BorrowKind::Ref) => "&mut ",
2112 (ast::Mutability::Mut, ast::BorrowKind::Raw) => "&raw mut ",
2114 rewrite_unary_prefix(context, operator_str, expr, shape)
2117 pub(crate) fn is_method_call(expr: &ast::Expr) -> bool {
2119 ast::ExprKind::MethodCall(..) => true,
2120 ast::ExprKind::AddrOf(_, _, ref expr)
2121 | ast::ExprKind::Box(ref expr)
2122 | ast::ExprKind::Cast(ref expr, _)
2123 | ast::ExprKind::Try(ref expr)
2124 | ast::ExprKind::Unary(_, ref expr) => is_method_call(expr),
2131 use super::last_line_offsetted;
2134 fn test_last_line_offsetted() {
2135 let lines = "one\n two";
2136 assert_eq!(last_line_offsetted(2, lines), true);
2137 assert_eq!(last_line_offsetted(4, lines), false);
2138 assert_eq!(last_line_offsetted(6, lines), false);
2140 let lines = "one two";
2141 assert_eq!(last_line_offsetted(2, lines), false);
2142 assert_eq!(last_line_offsetted(0, lines), false);
2144 let lines = "\ntwo";
2145 assert_eq!(last_line_offsetted(2, lines), false);
2146 assert_eq!(last_line_offsetted(0, lines), false);
2148 let lines = "one\n two three";
2149 assert_eq!(last_line_offsetted(2, lines), true);
2150 let lines = "one\n two three";
2151 assert_eq!(last_line_offsetted(2, lines), false);