4 use itertools::Itertools;
5 use rustc_ast::token::{DelimToken, 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, 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 {
111 fields, path, rest, ..
113 rewrite_struct_lit(context, path, fields, rest, &expr.attrs, expr.span, shape)
115 ast::ExprKind::Tup(ref items) => {
116 rewrite_tuple(context, items.iter(), expr.span, shape, items.len() == 1)
118 ast::ExprKind::Let(..) => None,
119 ast::ExprKind::If(..)
120 | ast::ExprKind::ForLoop(..)
121 | ast::ExprKind::Loop(..)
122 | ast::ExprKind::While(..) => to_control_flow(expr, expr_type)
123 .and_then(|control_flow| control_flow.rewrite(context, shape)),
124 ast::ExprKind::ConstBlock(ref anon_const) => {
125 Some(format!("const {}", anon_const.rewrite(context, shape)?))
127 ast::ExprKind::Block(ref block, opt_label) => {
129 ExprType::Statement => {
130 if is_unsafe_block(block) {
131 rewrite_block(block, Some(&expr.attrs), opt_label, context, shape)
132 } else if let rw @ Some(_) =
133 rewrite_empty_block(context, block, Some(&expr.attrs), opt_label, "", shape)
135 // Rewrite block without trying to put it in a single line.
138 let prefix = block_prefix(context, block, shape)?;
140 rewrite_block_with_visitor(
151 ExprType::SubExpression => {
152 rewrite_block(block, Some(&expr.attrs), opt_label, context, shape)
156 ast::ExprKind::Match(ref cond, ref arms) => {
157 rewrite_match(context, cond, arms, shape, expr.span, &expr.attrs)
159 ast::ExprKind::Path(ref qself, ref path) => {
160 rewrite_path(context, PathContext::Expr, qself.as_ref(), path, shape)
162 ast::ExprKind::Assign(ref lhs, ref rhs, _) => {
163 rewrite_assignment(context, lhs, rhs, None, shape)
165 ast::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => {
166 rewrite_assignment(context, lhs, rhs, Some(op), shape)
168 ast::ExprKind::Continue(ref opt_label) => {
169 let id_str = match *opt_label {
170 Some(label) => format!(" {}", label.ident),
171 None => String::new(),
173 Some(format!("continue{}", id_str))
175 ast::ExprKind::Break(ref opt_label, ref opt_expr) => {
176 let id_str = match *opt_label {
177 Some(label) => format!(" {}", label.ident),
178 None => String::new(),
181 if let Some(ref expr) = *opt_expr {
182 rewrite_unary_prefix(context, &format!("break{} ", id_str), &**expr, shape)
184 Some(format!("break{}", id_str))
187 ast::ExprKind::Yield(ref opt_expr) => {
188 if let Some(ref expr) = *opt_expr {
189 rewrite_unary_prefix(context, "yield ", &**expr, shape)
191 Some("yield".to_string())
194 ast::ExprKind::Closure(capture, ref is_async, movability, ref fn_decl, ref body, _) => {
195 closures::rewrite_closure(
196 capture, is_async, movability, fn_decl, body, expr.span, context, shape,
199 ast::ExprKind::Try(..) | ast::ExprKind::Field(..) | ast::ExprKind::MethodCall(..) => {
200 rewrite_chain(expr, context, shape)
202 ast::ExprKind::MacCall(ref mac) => {
203 rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| {
205 context.snippet(expr.span).to_owned(),
206 context.config.max_width(),
211 ast::ExprKind::Ret(None) => Some("return".to_owned()),
212 ast::ExprKind::Ret(Some(ref expr)) => {
213 rewrite_unary_prefix(context, "return ", &**expr, shape)
215 ast::ExprKind::Box(ref expr) => rewrite_unary_prefix(context, "box ", &**expr, shape),
216 ast::ExprKind::AddrOf(borrow_kind, mutability, ref expr) => {
217 rewrite_expr_addrof(context, borrow_kind, mutability, expr, shape)
219 ast::ExprKind::Cast(ref expr, ref ty) => rewrite_pair(
222 PairParts::infix(" as "),
225 SeparatorPlace::Front,
227 ast::ExprKind::Type(ref expr, ref ty) => rewrite_pair(
230 PairParts::infix(": "),
233 SeparatorPlace::Back,
235 ast::ExprKind::Index(ref expr, ref index) => {
236 rewrite_index(&**expr, &**index, context, shape)
238 ast::ExprKind::Repeat(ref expr, ref repeats) => rewrite_pair(
241 PairParts::new("[", "; ", "]"),
244 SeparatorPlace::Back,
246 ast::ExprKind::Range(ref lhs, ref rhs, limits) => {
247 let delim = match limits {
248 ast::RangeLimits::HalfOpen => "..",
249 ast::RangeLimits::Closed => "..=",
252 fn needs_space_before_range(context: &RewriteContext<'_>, lhs: &ast::Expr) -> bool {
254 ast::ExprKind::Lit(ref lit) => match lit.kind {
255 ast::LitKind::Float(_, ast::LitFloatType::Unsuffixed) => {
256 context.snippet(lit.span).ends_with('.')
260 ast::ExprKind::Unary(_, ref expr) => needs_space_before_range(context, &expr),
265 fn needs_space_after_range(rhs: &ast::Expr) -> bool {
267 // Don't format `.. ..` into `....`, which is invalid.
269 // This check is unnecessary for `lhs`, because a range
270 // starting from another range needs parentheses as `(x ..) ..`
271 // (`x .. ..` is a range from `x` to `..`).
272 ast::ExprKind::Range(None, _, _) => true,
277 let default_sp_delim = |lhs: Option<&ast::Expr>, rhs: Option<&ast::Expr>| {
278 let space_if = |b: bool| if b { " " } else { "" };
282 lhs.map_or("", |lhs| space_if(needs_space_before_range(context, lhs))),
284 rhs.map_or("", |rhs| space_if(needs_space_after_range(rhs))),
288 match (lhs.as_ref().map(|x| &**x), rhs.as_ref().map(|x| &**x)) {
289 (Some(lhs), Some(rhs)) => {
290 let sp_delim = if context.config.spaces_around_ranges() {
291 format!(" {} ", delim)
293 default_sp_delim(Some(lhs), Some(rhs))
298 PairParts::infix(&sp_delim),
301 context.config.binop_separator(),
304 (None, Some(rhs)) => {
305 let sp_delim = if context.config.spaces_around_ranges() {
306 format!("{} ", delim)
308 default_sp_delim(None, Some(rhs))
310 rewrite_unary_prefix(context, &sp_delim, &*rhs, shape)
312 (Some(lhs), None) => {
313 let sp_delim = if context.config.spaces_around_ranges() {
314 format!(" {}", delim)
316 default_sp_delim(Some(lhs), None)
318 rewrite_unary_suffix(context, &sp_delim, &*lhs, shape)
320 (None, None) => Some(delim.to_owned()),
323 // We do not format these expressions yet, but they should still
324 // satisfy our width restrictions.
325 // Style Guide RFC for InlineAsm variant pending
326 // https://github.com/rust-dev-tools/fmt-rfcs/issues/152
327 ast::ExprKind::LlvmInlineAsm(..) | ast::ExprKind::InlineAsm(..) => {
328 Some(context.snippet(expr.span).to_owned())
330 ast::ExprKind::TryBlock(ref block) => {
331 if let rw @ Some(_) =
332 rewrite_single_line_block(context, "try ", block, Some(&expr.attrs), None, shape)
337 let budget = shape.width.saturating_sub(9);
346 Shape::legacy(budget, shape.indent)
351 ast::ExprKind::Async(capture_by, _node_id, ref block) => {
352 let mover = if capture_by == ast::CaptureBy::Value {
357 if let rw @ Some(_) = rewrite_single_line_block(
359 format!("{}{}", "async ", mover).as_str(),
368 let budget = shape.width.saturating_sub(6);
378 Shape::legacy(budget, shape.indent)
383 ast::ExprKind::Await(_) => rewrite_chain(expr, context, shape),
384 ast::ExprKind::Underscore => Some("_".to_owned()),
385 ast::ExprKind::Err => None,
389 .and_then(|expr_str| recover_comment_removed(expr_str, expr.span, context))
390 .and_then(|expr_str| {
391 let attrs = outer_attributes(&expr.attrs);
392 let attrs_str = attrs.rewrite(context, shape)?;
394 attrs.last().map_or(expr.span.lo(), |attr| attr.span.hi()),
397 combine_strs_with_missing_comments(context, &attrs_str, &expr_str, span, shape, false)
401 pub(crate) fn rewrite_array<'a, T: 'a + IntoOverflowableItem<'a>>(
403 exprs: impl Iterator<Item = &'a T>,
405 context: &'a RewriteContext<'_>,
407 force_separator_tactic: Option<SeparatorTactic>,
408 delim_token: Option<DelimToken>,
409 ) -> Option<String> {
410 overflow::rewrite_with_square_brackets(
416 force_separator_tactic,
421 fn rewrite_empty_block(
422 context: &RewriteContext<'_>,
424 attrs: Option<&[ast::Attribute]>,
425 label: Option<ast::Label>,
428 ) -> Option<String> {
429 if block_has_statements(&block) {
433 let label_str = rewrite_label(label);
434 if attrs.map_or(false, |a| !inner_attributes(a).is_empty()) {
438 if !block_contains_comment(context, block) && shape.width >= 2 {
439 return Some(format!("{}{}{{}}", prefix, label_str));
442 // If a block contains only a single-line comment, then leave it on one line.
443 let user_str = context.snippet(block.span);
444 let user_str = user_str.trim();
445 if user_str.starts_with('{') && user_str.ends_with('}') {
446 let comment_str = user_str[1..user_str.len() - 1].trim();
447 if block.stmts.is_empty()
448 && !comment_str.contains('\n')
449 && !comment_str.starts_with("//")
450 && comment_str.len() + 4 <= shape.width
452 return Some(format!("{}{}{{ {} }}", prefix, label_str, comment_str));
459 fn block_prefix(context: &RewriteContext<'_>, block: &ast::Block, shape: Shape) -> Option<String> {
460 Some(match block.rules {
461 ast::BlockCheckMode::Unsafe(..) => {
462 let snippet = context.snippet(block.span);
463 let open_pos = snippet.find_uncommented("{")?;
464 // Extract comment between unsafe and block start.
465 let trimmed = &snippet[6..open_pos].trim();
467 if !trimmed.is_empty() {
468 // 9 = "unsafe {".len(), 7 = "unsafe ".len()
469 let budget = shape.width.checked_sub(9)?;
475 Shape::legacy(budget, shape.indent + 7),
483 ast::BlockCheckMode::Default => String::new(),
487 fn rewrite_single_line_block(
488 context: &RewriteContext<'_>,
491 attrs: Option<&[ast::Attribute]>,
492 label: Option<ast::Label>,
494 ) -> Option<String> {
495 if is_simple_block(context, block, attrs) {
496 let expr_shape = shape.offset_left(last_line_width(prefix))?;
497 let expr_str = block.stmts[0].rewrite(context, expr_shape)?;
498 let label_str = rewrite_label(label);
499 let result = format!("{}{}{{ {} }}", prefix, label_str, expr_str);
500 if result.len() <= shape.width && !result.contains('\n') {
507 pub(crate) fn rewrite_block_with_visitor(
508 context: &RewriteContext<'_>,
511 attrs: Option<&[ast::Attribute]>,
512 label: Option<ast::Label>,
515 ) -> Option<String> {
516 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, label, prefix, shape) {
520 let mut visitor = FmtVisitor::from_context(context);
521 visitor.block_indent = shape.indent;
522 visitor.is_if_else_block = context.is_if_else_block();
523 match (block.rules, label) {
524 (ast::BlockCheckMode::Unsafe(..), _) | (ast::BlockCheckMode::Default, Some(_)) => {
525 let snippet = context.snippet(block.span);
526 let open_pos = snippet.find_uncommented("{")?;
527 visitor.last_pos = block.span.lo() + BytePos(open_pos as u32)
529 (ast::BlockCheckMode::Default, None) => visitor.last_pos = block.span.lo(),
532 let inner_attrs = attrs.map(inner_attributes);
533 let label_str = rewrite_label(label);
534 visitor.visit_block(block, inner_attrs.as_ref().map(|a| &**a), has_braces);
535 let visitor_context = visitor.get_context();
539 .append(&mut visitor_context.skipped_range.borrow_mut());
540 Some(format!("{}{}{}", prefix, label_str, visitor.buffer))
543 impl Rewrite for ast::Block {
544 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
545 rewrite_block(self, None, None, context, shape)
551 attrs: Option<&[ast::Attribute]>,
552 label: Option<ast::Label>,
553 context: &RewriteContext<'_>,
555 ) -> Option<String> {
556 let prefix = block_prefix(context, block, shape)?;
558 // shape.width is used only for the single line case: either the empty block `{}`,
559 // or an unsafe expression `unsafe { e }`.
560 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, label, &prefix, shape) {
564 let result = rewrite_block_with_visitor(context, &prefix, block, attrs, label, shape, true);
565 if let Some(ref result_str) = result {
566 if result_str.lines().count() <= 3 {
567 if let rw @ Some(_) =
568 rewrite_single_line_block(context, &prefix, block, attrs, label, shape)
578 // Rewrite condition if the given expression has one.
579 pub(crate) fn rewrite_cond(
580 context: &RewriteContext<'_>,
583 ) -> Option<String> {
585 ast::ExprKind::Match(ref cond, _) => {
587 let cond_shape = match context.config.indent_style() {
588 IndentStyle::Visual => shape.shrink_left(6).and_then(|s| s.sub_width(2))?,
589 IndentStyle::Block => shape.offset_left(8)?,
591 cond.rewrite(context, cond_shape)
593 _ => to_control_flow(expr, ExprType::SubExpression).and_then(|control_flow| {
595 String::from("\n") + &shape.indent.block_only().to_string(context.config);
597 .rewrite_cond(context, shape, &alt_block_sep)
598 .and_then(|rw| Some(rw.0))
603 // Abstraction over control flow expressions
605 struct ControlFlow<'a> {
606 cond: Option<&'a ast::Expr>,
607 block: &'a ast::Block,
608 else_block: Option<&'a ast::Expr>,
609 label: Option<ast::Label>,
610 pat: Option<&'a ast::Pat>,
614 allow_single_line: bool,
615 // HACK: `true` if this is an `if` expression in an `else if`.
620 fn extract_pats_and_cond(expr: &ast::Expr) -> (Option<&ast::Pat>, &ast::Expr) {
622 ast::ExprKind::Let(ref pat, ref cond) => (Some(pat), cond),
627 // FIXME: Refactor this.
628 fn to_control_flow(expr: &ast::Expr, expr_type: ExprType) -> Option<ControlFlow<'_>> {
630 ast::ExprKind::If(ref cond, ref if_block, ref else_block) => {
631 let (pat, cond) = extract_pats_and_cond(cond);
632 Some(ControlFlow::new_if(
636 else_block.as_ref().map(|e| &**e),
637 expr_type == ExprType::SubExpression,
642 ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
643 Some(ControlFlow::new_for(pat, cond, block, label, expr.span))
645 ast::ExprKind::Loop(ref block, label) => {
646 Some(ControlFlow::new_loop(block, label, expr.span))
648 ast::ExprKind::While(ref cond, ref block, label) => {
649 let (pat, cond) = extract_pats_and_cond(cond);
650 Some(ControlFlow::new_while(pat, cond, block, label, expr.span))
656 fn choose_matcher(pat: Option<&ast::Pat>) -> &'static str {
657 pat.map_or("", |_| "let")
660 impl<'a> ControlFlow<'a> {
663 pat: Option<&'a ast::Pat>,
664 block: &'a ast::Block,
665 else_block: Option<&'a ast::Expr>,
666 allow_single_line: bool,
669 ) -> ControlFlow<'a> {
670 let matcher = choose_matcher(pat);
686 fn new_loop(block: &'a ast::Block, label: Option<ast::Label>, span: Span) -> ControlFlow<'a> {
696 allow_single_line: false,
703 pat: Option<&'a ast::Pat>,
705 block: &'a ast::Block,
706 label: Option<ast::Label>,
708 ) -> ControlFlow<'a> {
709 let matcher = choose_matcher(pat);
719 allow_single_line: false,
728 block: &'a ast::Block,
729 label: Option<ast::Label>,
731 ) -> ControlFlow<'a> {
741 allow_single_line: false,
747 fn rewrite_single_line(
750 context: &RewriteContext<'_>,
752 ) -> Option<String> {
753 assert!(self.allow_single_line);
754 let else_block = self.else_block?;
755 let fixed_cost = self.keyword.len() + " { } else { }".len();
757 if let ast::ExprKind::Block(ref else_node, _) = else_block.kind {
758 if !is_simple_block(context, self.block, None)
759 || !is_simple_block(context, else_node, None)
760 || pat_expr_str.contains('\n')
765 let new_width = width.checked_sub(pat_expr_str.len() + fixed_cost)?;
766 let expr = &self.block.stmts[0];
767 let if_str = expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
769 let new_width = new_width.checked_sub(if_str.len())?;
770 let else_expr = &else_node.stmts[0];
771 let else_str = else_expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
773 if if_str.contains('\n') || else_str.contains('\n') {
777 let result = format!(
778 "{} {} {{ {} }} else {{ {} }}",
779 self.keyword, pat_expr_str, if_str, else_str
782 if result.len() <= width {
791 /// Returns `true` if the last line of pat_str has leading whitespace and it is wider than the
793 fn last_line_offsetted(start_column: usize, pat_str: &str) -> bool {
794 let mut leading_whitespaces = 0;
795 for c in pat_str.chars().rev() {
798 _ if c.is_whitespace() => leading_whitespaces += 1,
799 _ => leading_whitespaces = 0,
802 leading_whitespaces > start_column
805 impl<'a> ControlFlow<'a> {
808 context: &RewriteContext<'_>,
812 ) -> Option<String> {
813 debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, self.pat, expr);
815 let cond_shape = shape.offset_left(offset)?;
816 if let Some(pat) = self.pat {
817 let matcher = if self.matcher.is_empty() {
818 self.matcher.to_owned()
820 format!("{} ", self.matcher)
822 let pat_shape = cond_shape
823 .offset_left(matcher.len())?
824 .sub_width(self.connector.len())?;
825 let pat_string = pat.rewrite(context, pat_shape)?;
826 let comments_lo = context
828 .span_after(self.span, self.connector.trim());
829 let comments_span = mk_sp(comments_lo, expr.span.lo());
830 return rewrite_assign_rhs_with_comments(
832 &format!("{}{}{}", matcher, pat_string, self.connector),
841 let expr_rw = expr.rewrite(context, cond_shape);
842 // The expression may (partially) fit on the current line.
843 // We do not allow splitting between `if` and condition.
844 if self.keyword == "if" || expr_rw.is_some() {
848 // The expression won't fit on the current line, jump to next.
849 let nested_shape = shape
850 .block_indent(context.config.tab_spaces())
851 .with_max_width(context.config);
852 let nested_indent_str = nested_shape.indent.to_string_with_newline(context.config);
853 expr.rewrite(context, nested_shape)
854 .map(|expr_rw| format!("{}{}", nested_indent_str, expr_rw))
859 context: &RewriteContext<'_>,
862 ) -> Option<(String, usize)> {
863 // Do not take the rhs overhead from the upper expressions into account
864 // when rewriting pattern.
865 let new_width = context.budget(shape.used_width());
866 let fresh_shape = Shape {
870 let constr_shape = if self.nested_if {
871 // We are part of an if-elseif-else chain. Our constraints are tightened.
872 // 7 = "} else " .len()
873 fresh_shape.offset_left(7)?
878 let label_string = rewrite_label(self.label);
879 // 1 = space after keyword.
880 let offset = self.keyword.len() + label_string.len() + 1;
882 let pat_expr_string = match self.cond {
883 Some(cond) => self.rewrite_pat_expr(context, cond, constr_shape, offset)?,
884 None => String::new(),
888 if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
894 let one_line_budget = context
897 .saturating_sub(constr_shape.used_width() + offset + brace_overhead);
898 let force_newline_brace = (pat_expr_string.contains('\n')
899 || pat_expr_string.len() > one_line_budget)
900 && (!last_line_extendable(&pat_expr_string)
901 || last_line_offsetted(shape.used_width(), &pat_expr_string));
903 // Try to format if-else on single line.
904 if self.allow_single_line && context.config.single_line_if_else_max_width() > 0 {
905 let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width);
907 if let Some(cond_str) = trial {
908 if cond_str.len() <= context.config.single_line_if_else_max_width() {
909 return Some((cond_str, 0));
914 let cond_span = if let Some(cond) = self.cond {
917 mk_sp(self.block.span.lo(), self.block.span.lo())
920 // `for event in event`
921 // Do not include label in the span.
924 .map_or(self.span.lo(), |label| label.ident.span.hi());
925 let between_kwd_cond = mk_sp(
928 .span_after(mk_sp(lo, self.span.hi()), self.keyword.trim()),
929 if self.pat.is_none() {
931 } else if self.matcher.is_empty() {
932 self.pat.unwrap().span.lo()
936 .span_before(self.span, self.matcher.trim())
940 let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape);
942 let after_cond_comment =
943 extract_comment(mk_sp(cond_span.hi(), self.block.span.lo()), context, shape);
945 let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
947 } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine
948 || force_newline_brace
955 let used_width = if pat_expr_string.contains('\n') {
956 last_line_width(&pat_expr_string)
958 // 2 = spaces after keyword and condition.
959 label_string.len() + self.keyword.len() + pat_expr_string.len() + 2
967 between_kwd_cond_comment.as_ref().map_or(
968 if pat_expr_string.is_empty() || pat_expr_string.starts_with('\n') {
976 after_cond_comment.as_ref().map_or(block_sep, |s| &**s)
983 impl<'a> Rewrite for ControlFlow<'a> {
984 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
985 debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
987 let alt_block_sep = &shape.indent.to_string_with_newline(context.config);
988 let (cond_str, used_width) = self.rewrite_cond(context, shape, alt_block_sep)?;
989 // If `used_width` is 0, it indicates that whole control flow is written in a single line.
991 return Some(cond_str);
994 let block_width = shape.width.saturating_sub(used_width);
995 // This is used only for the empty block case: `{}`. So, we use 1 if we know
996 // we should avoid the single line case.
997 let block_width = if self.else_block.is_some() || self.nested_if {
1002 let block_shape = Shape {
1007 let old_val = context.is_if_else_block.replace(self.else_block.is_some());
1009 rewrite_block_with_visitor(context, "", self.block, None, None, block_shape, true);
1010 context.is_if_else_block.replace(old_val);
1014 let mut result = format!("{}{}", cond_str, block_str);
1016 if let Some(else_block) = self.else_block {
1017 let shape = Shape::indented(shape.indent, context.config);
1018 let mut last_in_chain = false;
1019 let rewrite = match else_block.kind {
1020 // If the else expression is another if-else expression, prevent it
1021 // from being formatted on a single line.
1022 // Note how we're passing the original shape, as the
1023 // cost of "else" should not cascade.
1024 ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => {
1025 let (pats, cond) = extract_pats_and_cond(cond);
1026 ControlFlow::new_if(
1030 next_else_block.as_ref().map(|e| &**e),
1033 mk_sp(else_block.span.lo(), self.span.hi()),
1035 .rewrite(context, shape)
1038 last_in_chain = true;
1039 // When rewriting a block, the width is only used for single line
1040 // blocks, passing 1 lets us avoid that.
1041 let else_shape = Shape {
1042 width: min(1, shape.width),
1045 format_expr(else_block, ExprType::Statement, context, else_shape)
1049 let between_kwd_else_block = mk_sp(
1050 self.block.span.hi(),
1053 .span_before(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1055 let between_kwd_else_block_comment =
1056 extract_comment(between_kwd_else_block, context, shape);
1058 let after_else = mk_sp(
1061 .span_after(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1062 else_block.span.lo(),
1064 let after_else_comment = extract_comment(after_else, context, shape);
1066 let between_sep = match context.config.control_brace_style() {
1067 ControlBraceStyle::AlwaysNextLine | ControlBraceStyle::ClosingNextLine => {
1070 ControlBraceStyle::AlwaysSameLine => " ",
1072 let after_sep = match context.config.control_brace_style() {
1073 ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep,
1077 result.push_str(&format!(
1079 between_kwd_else_block_comment
1081 .map_or(between_sep, |s| &**s),
1082 after_else_comment.as_ref().map_or(after_sep, |s| &**s),
1084 result.push_str(&rewrite?);
1091 fn rewrite_label(opt_label: Option<ast::Label>) -> Cow<'static, str> {
1093 Some(label) => Cow::from(format!("{}: ", label.ident)),
1094 None => Cow::from(""),
1098 fn extract_comment(span: Span, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1099 match rewrite_missing_comment(span, shape, context) {
1100 Some(ref comment) if !comment.is_empty() => Some(format!(
1101 "{indent}{}{indent}",
1103 indent = shape.indent.to_string_with_newline(context.config)
1109 pub(crate) fn block_contains_comment(context: &RewriteContext<'_>, block: &ast::Block) -> bool {
1110 contains_comment(context.snippet(block.span))
1113 // Checks that a block contains no statements, an expression and no comments or
1115 // FIXME: incorrectly returns false when comment is contained completely within
1117 pub(crate) fn is_simple_block(
1118 context: &RewriteContext<'_>,
1120 attrs: Option<&[ast::Attribute]>,
1122 block.stmts.len() == 1
1123 && stmt_is_expr(&block.stmts[0])
1124 && !block_contains_comment(context, block)
1125 && attrs.map_or(true, |a| a.is_empty())
1128 /// Checks whether a block contains at most one statement or expression, and no
1129 /// comments or attributes.
1130 pub(crate) fn is_simple_block_stmt(
1131 context: &RewriteContext<'_>,
1133 attrs: Option<&[ast::Attribute]>,
1135 block.stmts.len() <= 1
1136 && !block_contains_comment(context, block)
1137 && attrs.map_or(true, |a| a.is_empty())
1140 fn block_has_statements(block: &ast::Block) -> bool {
1144 .any(|stmt| !matches!(stmt.kind, ast::StmtKind::Empty))
1147 /// Checks whether a block contains no statements, expressions, comments, or
1148 /// inner attributes.
1149 pub(crate) fn is_empty_block(
1150 context: &RewriteContext<'_>,
1152 attrs: Option<&[ast::Attribute]>,
1154 !block_has_statements(&block)
1155 && !block_contains_comment(context, block)
1156 && attrs.map_or(true, |a| inner_attributes(a).is_empty())
1159 pub(crate) fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
1161 ast::StmtKind::Expr(..) => true,
1166 pub(crate) fn is_unsafe_block(block: &ast::Block) -> bool {
1167 if let ast::BlockCheckMode::Unsafe(..) = block.rules {
1174 pub(crate) fn rewrite_literal(
1175 context: &RewriteContext<'_>,
1178 ) -> Option<String> {
1180 ast::LitKind::Str(_, ast::StrStyle::Cooked) => rewrite_string_lit(context, l.span, shape),
1182 context.snippet(l.span).to_owned(),
1183 context.config.max_width(),
1189 fn rewrite_string_lit(context: &RewriteContext<'_>, span: Span, shape: Shape) -> Option<String> {
1190 let string_lit = context.snippet(span);
1192 if !context.config.format_strings() {
1196 .all(|line| line.ends_with('\\'))
1197 && context.config.version() == Version::Two
1199 return Some(string_lit.to_owned());
1201 return wrap_str(string_lit.to_owned(), context.config.max_width(), shape);
1205 // Remove the quote characters.
1206 let str_lit = &string_lit[1..string_lit.len() - 1];
1210 &StringFormat::new(shape.visual_indent(0), context.config),
1211 shape.width.saturating_sub(2),
1215 fn choose_separator_tactic(context: &RewriteContext<'_>, span: Span) -> Option<SeparatorTactic> {
1216 if context.inside_macro() {
1217 if span_ends_with_comma(context, span) {
1218 Some(SeparatorTactic::Always)
1220 Some(SeparatorTactic::Never)
1227 pub(crate) fn rewrite_call(
1228 context: &RewriteContext<'_>,
1230 args: &[ptr::P<ast::Expr>],
1233 ) -> Option<String> {
1234 overflow::rewrite_with_parens(
1240 context.config.fn_call_width(),
1241 choose_separator_tactic(context, span),
1245 pub(crate) fn is_simple_expr(expr: &ast::Expr) -> bool {
1247 ast::ExprKind::Lit(..) => true,
1248 ast::ExprKind::Path(ref qself, ref path) => qself.is_none() && path.segments.len() <= 1,
1249 ast::ExprKind::AddrOf(_, _, ref expr)
1250 | ast::ExprKind::Box(ref expr)
1251 | ast::ExprKind::Cast(ref expr, _)
1252 | ast::ExprKind::Field(ref expr, _)
1253 | ast::ExprKind::Try(ref expr)
1254 | ast::ExprKind::Unary(_, ref expr) => is_simple_expr(expr),
1255 ast::ExprKind::Index(ref lhs, ref rhs) => is_simple_expr(lhs) && is_simple_expr(rhs),
1256 ast::ExprKind::Repeat(ref lhs, ref rhs) => {
1257 is_simple_expr(lhs) && is_simple_expr(&*rhs.value)
1263 pub(crate) fn is_every_expr_simple(lists: &[OverflowableItem<'_>]) -> bool {
1264 lists.iter().all(OverflowableItem::is_simple)
1267 pub(crate) fn can_be_overflowed_expr(
1268 context: &RewriteContext<'_>,
1273 _ if !expr.attrs.is_empty() => false,
1274 ast::ExprKind::Match(..) => {
1275 (context.use_block_indent() && args_len == 1)
1276 || (context.config.indent_style() == IndentStyle::Visual && args_len > 1)
1277 || context.config.overflow_delimited_expr()
1279 ast::ExprKind::If(..)
1280 | ast::ExprKind::ForLoop(..)
1281 | ast::ExprKind::Loop(..)
1282 | ast::ExprKind::While(..) => {
1283 context.config.combine_control_expr() && context.use_block_indent() && args_len == 1
1286 // Handle always block-like expressions
1287 ast::ExprKind::Async(..) | ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => true,
1289 // Handle `[]` and `{}`-like expressions
1290 ast::ExprKind::Array(..) | ast::ExprKind::Struct(..) => {
1291 context.config.overflow_delimited_expr()
1292 || (context.use_block_indent() && args_len == 1)
1294 ast::ExprKind::MacCall(ref mac) => {
1296 rustc_ast::ast::MacDelimiter::from_token(mac.args.delim()),
1297 context.config.overflow_delimited_expr(),
1299 (Some(ast::MacDelimiter::Bracket), true)
1300 | (Some(ast::MacDelimiter::Brace), true) => true,
1301 _ => context.use_block_indent() && args_len == 1,
1305 // Handle parenthetical expressions
1306 ast::ExprKind::Call(..) | ast::ExprKind::MethodCall(..) | ast::ExprKind::Tup(..) => {
1307 context.use_block_indent() && args_len == 1
1310 // Handle unary-like expressions
1311 ast::ExprKind::AddrOf(_, _, ref expr)
1312 | ast::ExprKind::Box(ref expr)
1313 | ast::ExprKind::Try(ref expr)
1314 | ast::ExprKind::Unary(_, ref expr)
1315 | ast::ExprKind::Cast(ref expr, _) => can_be_overflowed_expr(context, expr, args_len),
1320 pub(crate) fn is_nested_call(expr: &ast::Expr) -> bool {
1322 ast::ExprKind::Call(..) | ast::ExprKind::MacCall(..) => true,
1323 ast::ExprKind::AddrOf(_, _, ref expr)
1324 | ast::ExprKind::Box(ref expr)
1325 | ast::ExprKind::Try(ref expr)
1326 | ast::ExprKind::Unary(_, ref expr)
1327 | ast::ExprKind::Cast(ref expr, _) => is_nested_call(expr),
1332 /// Returns `true` if a function call or a method call represented by the given span ends with a
1333 /// trailing comma. This function is used when rewriting macro, as adding or removing a trailing
1334 /// comma from macro can potentially break the code.
1335 pub(crate) fn span_ends_with_comma(context: &RewriteContext<'_>, span: Span) -> bool {
1336 let mut result: bool = Default::default();
1337 let mut prev_char: char = Default::default();
1338 let closing_delimiters = &[')', '}', ']'];
1340 for (kind, c) in CharClasses::new(context.snippet(span).chars()) {
1342 _ if kind.is_comment() || c.is_whitespace() => continue,
1343 c if closing_delimiters.contains(&c) => {
1344 result &= !closing_delimiters.contains(&prev_char);
1346 ',' => result = true,
1347 _ => result = false,
1356 context: &RewriteContext<'_>,
1357 mut subexpr: &ast::Expr,
1360 ) -> Option<String> {
1361 debug!("rewrite_paren, shape: {:?}", shape);
1363 // Extract comments within parens.
1366 let mut pre_comment;
1367 let mut post_comment;
1368 let remove_nested_parens = context.config.remove_nested_parens();
1371 pre_span = mk_sp(span.lo() + BytePos(1), subexpr.span.lo());
1372 post_span = mk_sp(subexpr.span.hi(), span.hi() - BytePos(1));
1373 pre_comment = rewrite_missing_comment(pre_span, shape, context)?;
1374 post_comment = rewrite_missing_comment(post_span, shape, context)?;
1376 // Remove nested parens if there are no comments.
1377 if let ast::ExprKind::Paren(ref subsubexpr) = subexpr.kind {
1378 if remove_nested_parens && pre_comment.is_empty() && post_comment.is_empty() {
1379 span = subexpr.span;
1380 subexpr = subsubexpr;
1389 let sub_shape = shape.offset_left(1)?.sub_width(1)?;
1390 let subexpr_str = subexpr.rewrite(context, sub_shape)?;
1391 let fits_single_line = !pre_comment.contains("//") && !post_comment.contains("//");
1392 if fits_single_line {
1393 Some(format!("({}{}{})", pre_comment, subexpr_str, post_comment))
1395 rewrite_paren_in_multi_line(context, subexpr, shape, pre_span, post_span)
1399 fn rewrite_paren_in_multi_line(
1400 context: &RewriteContext<'_>,
1401 subexpr: &ast::Expr,
1405 ) -> Option<String> {
1406 let nested_indent = shape.indent.block_indent(context.config);
1407 let nested_shape = Shape::indented(nested_indent, context.config);
1408 let pre_comment = rewrite_missing_comment(pre_span, nested_shape, context)?;
1409 let post_comment = rewrite_missing_comment(post_span, nested_shape, context)?;
1410 let subexpr_str = subexpr.rewrite(context, nested_shape)?;
1412 let mut result = String::with_capacity(subexpr_str.len() * 2);
1414 if !pre_comment.is_empty() {
1415 result.push_str(&nested_indent.to_string_with_newline(context.config));
1416 result.push_str(&pre_comment);
1418 result.push_str(&nested_indent.to_string_with_newline(context.config));
1419 result.push_str(&subexpr_str);
1420 if !post_comment.is_empty() {
1421 result.push_str(&nested_indent.to_string_with_newline(context.config));
1422 result.push_str(&post_comment);
1424 result.push_str(&shape.indent.to_string_with_newline(context.config));
1433 context: &RewriteContext<'_>,
1435 ) -> Option<String> {
1436 let expr_str = expr.rewrite(context, shape)?;
1438 let offset = last_line_width(&expr_str) + 1;
1439 let rhs_overhead = shape.rhs_overhead(context.config);
1440 let index_shape = if expr_str.contains('\n') {
1441 Shape::legacy(context.config.max_width(), shape.indent)
1442 .offset_left(offset)
1443 .and_then(|shape| shape.sub_width(1 + rhs_overhead))
1445 match context.config.indent_style() {
1446 IndentStyle::Block => shape
1447 .offset_left(offset)
1448 .and_then(|shape| shape.sub_width(1)),
1449 IndentStyle::Visual => shape.visual_indent(offset).sub_width(offset + 1),
1452 let orig_index_rw = index_shape.and_then(|s| index.rewrite(context, s));
1454 // Return if index fits in a single line.
1455 match orig_index_rw {
1456 Some(ref index_str) if !index_str.contains('\n') => {
1457 return Some(format!("{}[{}]", expr_str, index_str));
1462 // Try putting index on the next line and see if it fits in a single line.
1463 let indent = shape.indent.block_indent(context.config);
1464 let index_shape = Shape::indented(indent, context.config).offset_left(1)?;
1465 let index_shape = index_shape.sub_width(1 + rhs_overhead)?;
1466 let new_index_rw = index.rewrite(context, index_shape);
1467 match (orig_index_rw, new_index_rw) {
1468 (_, Some(ref new_index_str)) if !new_index_str.contains('\n') => Some(format!(
1471 indent.to_string_with_newline(context.config),
1474 (None, Some(ref new_index_str)) => Some(format!(
1477 indent.to_string_with_newline(context.config),
1480 (Some(ref index_str), _) => Some(format!("{}[{}]", expr_str, index_str)),
1485 fn struct_lit_can_be_aligned(fields: &[ast::ExprField], has_base: bool) -> bool {
1486 !has_base && fields.iter().all(|field| !field.is_shorthand)
1489 fn rewrite_struct_lit<'a>(
1490 context: &RewriteContext<'_>,
1492 fields: &'a [ast::ExprField],
1493 struct_rest: &ast::StructRest,
1494 attrs: &[ast::Attribute],
1497 ) -> Option<String> {
1498 debug!("rewrite_struct_lit: shape {:?}", shape);
1500 enum StructLitField<'a> {
1501 Regular(&'a ast::ExprField),
1502 Base(&'a ast::Expr),
1507 let path_shape = shape.sub_width(2)?;
1508 let path_str = rewrite_path(context, PathContext::Expr, None, path, path_shape)?;
1510 let has_base = match struct_rest {
1511 ast::StructRest::None if fields.is_empty() => return Some(format!("{} {{}}", path_str)),
1512 ast::StructRest::Rest(_) if fields.is_empty() => {
1513 return Some(format!("{} {{ .. }}", path_str));
1515 ast::StructRest::Base(_) => true,
1519 // Foo { a: Foo } - indent is +3, width is -5.
1520 let (h_shape, v_shape) = struct_lit_shape(shape, context, path_str.len() + 3, 2)?;
1522 let one_line_width = h_shape.map_or(0, |shape| shape.width);
1523 let body_lo = context.snippet_provider.span_after(span, "{");
1524 let fields_str = if struct_lit_can_be_aligned(fields, has_base)
1525 && context.config.struct_field_align_threshold() > 0
1527 rewrite_with_alignment(
1531 mk_sp(body_lo, span.hi()),
1535 let field_iter = fields.iter().map(StructLitField::Regular).chain(
1537 ast::StructRest::Base(expr) => Some(StructLitField::Base(&**expr)),
1538 ast::StructRest::Rest(span) => Some(StructLitField::Rest(span)),
1539 ast::StructRest::None => None,
1544 let span_lo = |item: &StructLitField<'_>| match *item {
1545 StructLitField::Regular(field) => field.span().lo(),
1546 StructLitField::Base(expr) => {
1547 let last_field_hi = fields.last().map_or(span.lo(), |field| field.span.hi());
1548 let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo()));
1549 let pos = snippet.find_uncommented("..").unwrap();
1550 last_field_hi + BytePos(pos as u32)
1552 StructLitField::Rest(span) => span.lo(),
1554 let span_hi = |item: &StructLitField<'_>| match *item {
1555 StructLitField::Regular(field) => field.span().hi(),
1556 StructLitField::Base(expr) => expr.span.hi(),
1557 StructLitField::Rest(span) => span.hi(),
1559 let rewrite = |item: &StructLitField<'_>| match *item {
1560 StructLitField::Regular(field) => {
1561 // The 1 taken from the v_budget is for the comma.
1562 rewrite_field(context, field, v_shape.sub_width(1)?, 0)
1564 StructLitField::Base(expr) => {
1566 expr.rewrite(context, v_shape.offset_left(2)?)
1567 .map(|s| format!("..{}", s))
1569 StructLitField::Rest(_) => Some("..".to_owned()),
1572 let items = itemize_list(
1573 context.snippet_provider,
1584 let item_vec = items.collect::<Vec<_>>();
1586 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
1587 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
1589 let ends_with_comma = span_ends_with_comma(context, span);
1590 let force_no_trailing_comma = context.inside_macro() && !ends_with_comma;
1592 let fmt = struct_lit_formatting(
1596 force_no_trailing_comma
1598 || !context.use_block_indent()
1599 || matches!(struct_rest, ast::StructRest::Rest(_)),
1602 write_list(&item_vec, &fmt)?
1606 wrap_struct_field(context, &attrs, &fields_str, shape, v_shape, one_line_width)?;
1607 Some(format!("{} {{{}}}", path_str, fields_str))
1609 // FIXME if context.config.indent_style() == Visual, but we run out
1610 // of space, we should fall back to BlockIndent.
1613 pub(crate) fn wrap_struct_field(
1614 context: &RewriteContext<'_>,
1615 attrs: &[ast::Attribute],
1618 nested_shape: Shape,
1619 one_line_width: usize,
1620 ) -> Option<String> {
1621 let should_vertical = context.config.indent_style() == IndentStyle::Block
1622 && (fields_str.contains('\n')
1623 || !context.config.struct_lit_single_line()
1624 || fields_str.len() > one_line_width);
1626 let inner_attrs = &inner_attributes(attrs);
1627 if inner_attrs.is_empty() {
1628 if should_vertical {
1631 nested_shape.indent.to_string_with_newline(context.config),
1633 shape.indent.to_string_with_newline(context.config)
1636 // One liner or visual indent.
1637 Some(format!(" {} ", fields_str))
1642 nested_shape.indent.to_string_with_newline(context.config),
1643 inner_attrs.rewrite(context, shape)?,
1644 nested_shape.indent.to_string_with_newline(context.config),
1646 shape.indent.to_string_with_newline(context.config)
1651 pub(crate) fn struct_lit_field_separator(config: &Config) -> &str {
1652 colon_spaces(config)
1655 pub(crate) fn rewrite_field(
1656 context: &RewriteContext<'_>,
1657 field: &ast::ExprField,
1659 prefix_max_width: usize,
1660 ) -> Option<String> {
1661 if contains_skip(&field.attrs) {
1662 return Some(context.snippet(field.span()).to_owned());
1664 let mut attrs_str = field.attrs.rewrite(context, shape)?;
1665 if !attrs_str.is_empty() {
1666 attrs_str.push_str(&shape.indent.to_string_with_newline(context.config));
1668 let name = context.snippet(field.ident.span);
1669 if field.is_shorthand {
1670 Some(attrs_str + name)
1672 let mut separator = String::from(struct_lit_field_separator(context.config));
1673 for _ in 0..prefix_max_width.saturating_sub(name.len()) {
1674 separator.push(' ');
1676 let overhead = name.len() + separator.len();
1677 let expr_shape = shape.offset_left(overhead)?;
1678 let expr = field.expr.rewrite(context, expr_shape);
1681 Some(ref e) if e.as_str() == name && context.config.use_field_init_shorthand() => {
1682 Some(attrs_str + name)
1684 Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)),
1686 let expr_offset = shape.indent.block_indent(context.config);
1689 .rewrite(context, Shape::indented(expr_offset, context.config));
1695 expr_offset.to_string(context.config),
1704 fn rewrite_tuple_in_visual_indent_style<'a, T: 'a + IntoOverflowableItem<'a>>(
1705 context: &RewriteContext<'_>,
1706 mut items: impl Iterator<Item = &'a T>,
1709 is_singleton_tuple: bool,
1710 ) -> Option<String> {
1711 // In case of length 1, need a trailing comma
1712 debug!("rewrite_tuple_in_visual_indent_style {:?}", shape);
1713 if is_singleton_tuple {
1715 let nested_shape = shape.sub_width(3)?.visual_indent(1);
1719 .rewrite(context, nested_shape)
1720 .map(|s| format!("({},)", s));
1723 let list_lo = context.snippet_provider.span_after(span, "(");
1724 let nested_shape = shape.sub_width(2)?.visual_indent(1);
1725 let items = itemize_list(
1726 context.snippet_provider,
1730 |item| item.span().lo(),
1731 |item| item.span().hi(),
1732 |item| item.rewrite(context, nested_shape),
1734 span.hi() - BytePos(1),
1737 let item_vec: Vec<_> = items.collect();
1738 let tactic = definitive_tactic(
1740 ListTactic::HorizontalVertical,
1744 let fmt = ListFormatting::new(nested_shape, context.config)
1746 .ends_with_newline(false);
1747 let list_str = write_list(&item_vec, &fmt)?;
1749 Some(format!("({})", list_str))
1752 pub(crate) fn rewrite_tuple<'a, T: 'a + IntoOverflowableItem<'a>>(
1753 context: &'a RewriteContext<'_>,
1754 items: impl Iterator<Item = &'a T>,
1757 is_singleton_tuple: bool,
1758 ) -> Option<String> {
1759 debug!("rewrite_tuple {:?}", shape);
1760 if context.use_block_indent() {
1761 // We use the same rule as function calls for rewriting tuples.
1762 let force_tactic = if context.inside_macro() {
1763 if span_ends_with_comma(context, span) {
1764 Some(SeparatorTactic::Always)
1766 Some(SeparatorTactic::Never)
1768 } else if is_singleton_tuple {
1769 Some(SeparatorTactic::Always)
1773 overflow::rewrite_with_parens(
1779 context.config.fn_call_width(),
1783 rewrite_tuple_in_visual_indent_style(context, items, span, shape, is_singleton_tuple)
1787 pub(crate) fn rewrite_unary_prefix<R: Rewrite>(
1788 context: &RewriteContext<'_>,
1792 ) -> Option<String> {
1794 .rewrite(context, shape.offset_left(prefix.len())?)
1795 .map(|r| format!("{}{}", prefix, r))
1798 // FIXME: this is probably not correct for multi-line Rewrites. we should
1799 // subtract suffix.len() from the last line budget, not the first!
1800 pub(crate) fn rewrite_unary_suffix<R: Rewrite>(
1801 context: &RewriteContext<'_>,
1805 ) -> Option<String> {
1807 .rewrite(context, shape.sub_width(suffix.len())?)
1814 fn rewrite_unary_op(
1815 context: &RewriteContext<'_>,
1819 ) -> Option<String> {
1820 // For some reason, an UnOp is not spanned like BinOp!
1821 rewrite_unary_prefix(context, ast::UnOp::to_string(op), expr, shape)
1824 fn rewrite_assignment(
1825 context: &RewriteContext<'_>,
1828 op: Option<&ast::BinOp>,
1830 ) -> Option<String> {
1831 let operator_str = match op {
1832 Some(op) => context.snippet(op.span),
1836 // 1 = space between lhs and operator.
1837 let lhs_shape = shape.sub_width(operator_str.len() + 1)?;
1838 let lhs_str = format!("{} {}", lhs.rewrite(context, lhs_shape)?, operator_str);
1840 rewrite_assign_rhs(context, lhs_str, rhs, shape)
1843 /// Controls where to put the rhs.
1844 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
1845 pub(crate) enum RhsTactics {
1848 /// Put the rhs on the next line if it uses multiple line, without extra indentation.
1849 ForceNextLineWithoutIndent,
1850 /// Allow overflowing max width if neither `Default` nor `ForceNextLineWithoutIndent`
1855 // The left hand side must contain everything up to, and including, the
1856 // assignment operator.
1857 pub(crate) fn rewrite_assign_rhs<S: Into<String>, R: Rewrite>(
1858 context: &RewriteContext<'_>,
1862 ) -> Option<String> {
1863 rewrite_assign_rhs_with(context, lhs, ex, shape, RhsTactics::Default)
1866 pub(crate) fn rewrite_assign_rhs_expr<R: Rewrite>(
1867 context: &RewriteContext<'_>,
1871 rhs_tactics: RhsTactics,
1872 ) -> Option<String> {
1873 let last_line_width = last_line_width(&lhs).saturating_sub(if lhs.contains('\n') {
1874 shape.indent.width()
1878 // 1 = space between operator and rhs.
1879 let orig_shape = shape.offset_left(last_line_width + 1).unwrap_or(Shape {
1881 offset: shape.offset + last_line_width + 1,
1884 let has_rhs_comment = if let Some(offset) = lhs.find_last_uncommented("=") {
1885 lhs.trim_end().len() > offset + 1
1894 ex.rewrite(context, orig_shape),
1900 pub(crate) fn rewrite_assign_rhs_with<S: Into<String>, R: Rewrite>(
1901 context: &RewriteContext<'_>,
1905 rhs_tactics: RhsTactics,
1906 ) -> Option<String> {
1907 let lhs = lhs.into();
1908 let rhs = rewrite_assign_rhs_expr(context, &lhs, ex, shape, rhs_tactics)?;
1912 pub(crate) fn rewrite_assign_rhs_with_comments<S: Into<String>, R: Rewrite>(
1913 context: &RewriteContext<'_>,
1917 rhs_tactics: RhsTactics,
1920 ) -> Option<String> {
1921 let lhs = lhs.into();
1922 let contains_comment = contains_comment(context.snippet(between_span));
1923 let shape = if contains_comment {
1924 shape.block_left(context.config.tab_spaces())?
1928 let rhs = rewrite_assign_rhs_expr(context, &lhs, ex, shape, rhs_tactics)?;
1930 if contains_comment {
1931 let rhs = rhs.trim_start();
1932 combine_strs_with_missing_comments(context, &lhs, &rhs, between_span, shape, allow_extend)
1938 fn choose_rhs<R: Rewrite>(
1939 context: &RewriteContext<'_>,
1942 orig_rhs: Option<String>,
1943 rhs_tactics: RhsTactics,
1944 has_rhs_comment: bool,
1945 ) -> Option<String> {
1948 if !new_str.contains('\n') && unicode_str_width(new_str) <= shape.width =>
1950 Some(format!(" {}", new_str))
1953 // Expression did not fit on the same line as the identifier.
1954 // Try splitting the line and see if that works better.
1955 let new_shape = shape_from_rhs_tactic(context, shape, rhs_tactics)?;
1956 let new_rhs = expr.rewrite(context, new_shape);
1957 let new_indent_str = &shape
1959 .block_indent(context.config)
1960 .to_string_with_newline(context.config);
1961 let before_space_str = if has_rhs_comment { "" } else { " " };
1963 match (orig_rhs, new_rhs) {
1964 (Some(ref orig_rhs), Some(ref new_rhs))
1965 if wrap_str(new_rhs.clone(), context.config.max_width(), new_shape)
1968 Some(format!("{}{}", before_space_str, orig_rhs))
1970 (Some(ref orig_rhs), Some(ref new_rhs))
1971 if prefer_next_line(orig_rhs, new_rhs, rhs_tactics) =>
1973 Some(format!("{}{}", new_indent_str, new_rhs))
1975 (None, Some(ref new_rhs)) => Some(format!("{}{}", new_indent_str, new_rhs)),
1976 (None, None) if rhs_tactics == RhsTactics::AllowOverflow => {
1977 let shape = shape.infinite_width();
1978 expr.rewrite(context, shape)
1979 .map(|s| format!("{}{}", before_space_str, s))
1981 (None, None) => None,
1982 (Some(orig_rhs), _) => Some(format!("{}{}", before_space_str, orig_rhs)),
1988 fn shape_from_rhs_tactic(
1989 context: &RewriteContext<'_>,
1991 rhs_tactic: RhsTactics,
1992 ) -> Option<Shape> {
1994 RhsTactics::ForceNextLineWithoutIndent => shape
1995 .with_max_width(context.config)
1996 .sub_width(shape.indent.width()),
1997 RhsTactics::Default | RhsTactics::AllowOverflow => {
1998 Shape::indented(shape.indent.block_indent(context.config), context.config)
1999 .sub_width(shape.rhs_overhead(context.config))
2004 /// Returns true if formatting next_line_rhs is better on a new line when compared to the
2005 /// original's line formatting.
2007 /// It is considered better if:
2008 /// 1. the tactic is ForceNextLineWithoutIndent
2009 /// 2. next_line_rhs doesn't have newlines
2010 /// 3. the original line has more newlines than next_line_rhs
2011 /// 4. the original formatting of the first line ends with `(`, `{`, or `[` and next_line_rhs
2013 pub(crate) fn prefer_next_line(
2015 next_line_rhs: &str,
2016 rhs_tactics: RhsTactics,
2018 rhs_tactics == RhsTactics::ForceNextLineWithoutIndent
2019 || !next_line_rhs.contains('\n')
2020 || count_newlines(orig_rhs) > count_newlines(next_line_rhs) + 1
2021 || first_line_ends_with(orig_rhs, '(') && !first_line_ends_with(next_line_rhs, '(')
2022 || first_line_ends_with(orig_rhs, '{') && !first_line_ends_with(next_line_rhs, '{')
2023 || first_line_ends_with(orig_rhs, '[') && !first_line_ends_with(next_line_rhs, '[')
2026 fn rewrite_expr_addrof(
2027 context: &RewriteContext<'_>,
2028 borrow_kind: ast::BorrowKind,
2029 mutability: ast::Mutability,
2032 ) -> Option<String> {
2033 let operator_str = match (mutability, borrow_kind) {
2034 (ast::Mutability::Not, ast::BorrowKind::Ref) => "&",
2035 (ast::Mutability::Not, ast::BorrowKind::Raw) => "&raw const ",
2036 (ast::Mutability::Mut, ast::BorrowKind::Ref) => "&mut ",
2037 (ast::Mutability::Mut, ast::BorrowKind::Raw) => "&raw mut ",
2039 rewrite_unary_prefix(context, operator_str, expr, shape)
2042 pub(crate) fn is_method_call(expr: &ast::Expr) -> bool {
2044 ast::ExprKind::MethodCall(..) => true,
2045 ast::ExprKind::AddrOf(_, _, ref expr)
2046 | ast::ExprKind::Box(ref expr)
2047 | ast::ExprKind::Cast(ref expr, _)
2048 | ast::ExprKind::Try(ref expr)
2049 | ast::ExprKind::Unary(_, ref expr) => is_method_call(expr),
2056 use super::last_line_offsetted;
2059 fn test_last_line_offsetted() {
2060 let lines = "one\n two";
2061 assert_eq!(last_line_offsetted(2, lines), true);
2062 assert_eq!(last_line_offsetted(4, lines), false);
2063 assert_eq!(last_line_offsetted(6, lines), false);
2065 let lines = "one two";
2066 assert_eq!(last_line_offsetted(2, lines), false);
2067 assert_eq!(last_line_offsetted(0, lines), false);
2069 let lines = "\ntwo";
2070 assert_eq!(last_line_offsetted(2, lines), false);
2071 assert_eq!(last_line_offsetted(0, lines), false);
2073 let lines = "one\n two three";
2074 assert_eq!(last_line_offsetted(2, lines), true);
2075 let lines = "one\n two three";
2076 assert_eq!(last_line_offsetted(2, lines), false);