1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
15 use syntax::codemap::{BytePos, CodeMap, Span};
16 use syntax::parse::token::DelimToken;
17 use syntax::{ast, ptr};
19 use chains::rewrite_chain;
21 use codemap::{LineRangeUtils, SpanUtils};
22 use comment::{combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
23 rewrite_comment, rewrite_missing_comment, CharClasses, FindUncommented};
24 use config::{Config, ControlBraceStyle, IndentStyle};
25 use lists::{definitive_tactic, itemize_list, shape_for_tactic, struct_lit_formatting,
26 struct_lit_shape, struct_lit_tactic, write_list, ListFormatting, ListItem, Separator};
27 use macros::{rewrite_macro, MacroArg, MacroPosition};
28 use matches::rewrite_match;
30 use patterns::{can_be_overflowed_pat, is_short_pattern, TuplePatField};
31 use rewrite::{Rewrite, RewriteContext};
32 use shape::{Indent, Shape};
34 use string::{rewrite_string, StringFormat};
35 use types::{can_be_overflowed_type, rewrite_path, PathContext};
36 use utils::{colon_spaces, contains_skip, count_newlines, first_line_width, inner_attributes,
37 last_line_extendable, last_line_width, mk_sp, outer_attributes, paren_overhead,
38 ptr_vec_to_ref_vec, semicolon_for_stmt, wrap_str};
39 use vertical::rewrite_with_alignment;
40 use visitor::FmtVisitor;
42 impl Rewrite for ast::Expr {
43 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
44 format_expr(self, ExprType::SubExpression, context, shape)
48 #[derive(Copy, Clone, PartialEq)]
57 context: &RewriteContext,
60 skip_out_of_file_lines_range!(context, expr.span);
62 if contains_skip(&*expr.attrs) {
63 return Some(context.snippet(expr.span()).to_owned());
66 let expr_rw = match expr.node {
67 ast::ExprKind::Array(ref expr_vec) => rewrite_array(
69 &ptr_vec_to_ref_vec(expr_vec),
76 ast::ExprKind::Lit(ref l) => rewrite_literal(context, l, shape),
77 ast::ExprKind::Call(ref callee, ref args) => {
78 let inner_span = mk_sp(callee.span.hi(), expr.span.hi());
79 let callee_str = callee.rewrite(context, shape)?;
80 rewrite_call(context, &callee_str, args, inner_span, shape)
82 ast::ExprKind::Paren(ref subexpr) => rewrite_paren(context, subexpr, shape, expr.span),
83 ast::ExprKind::Binary(ref op, ref lhs, ref rhs) => {
84 // FIXME: format comments between operands and operator
88 PairParts::new("", &format!(" {} ", context.snippet(op.span)), ""),
91 context.config.binop_separator(),
94 ast::ExprKind::Unary(ref op, ref subexpr) => rewrite_unary_op(context, op, subexpr, shape),
95 ast::ExprKind::Struct(ref path, ref fields, ref base) => rewrite_struct_lit(
99 base.as_ref().map(|e| &**e),
103 ast::ExprKind::Tup(ref items) => {
104 rewrite_tuple(context, &ptr_vec_to_ref_vec(items), expr.span, shape)
106 ast::ExprKind::If(..)
107 | ast::ExprKind::IfLet(..)
108 | ast::ExprKind::ForLoop(..)
109 | ast::ExprKind::Loop(..)
110 | ast::ExprKind::While(..)
111 | ast::ExprKind::WhileLet(..) => to_control_flow(expr, expr_type)
112 .and_then(|control_flow| control_flow.rewrite(context, shape)),
113 ast::ExprKind::Block(ref block) => {
115 ExprType::Statement => {
116 if is_unsafe_block(block) {
117 rewrite_block(block, Some(&expr.attrs), context, shape)
118 } else if let rw @ Some(_) =
119 rewrite_empty_block(context, block, Some(&expr.attrs), "", shape)
121 // Rewrite block without trying to put it in a single line.
124 let prefix = block_prefix(context, block, shape)?;
125 rewrite_block_with_visitor(
135 ExprType::SubExpression => rewrite_block(block, Some(&expr.attrs), context, shape),
138 ast::ExprKind::Match(ref cond, ref arms) => {
139 rewrite_match(context, cond, arms, shape, expr.span, &expr.attrs)
141 ast::ExprKind::Path(ref qself, ref path) => {
142 rewrite_path(context, PathContext::Expr, qself.as_ref(), path, shape)
144 ast::ExprKind::Assign(ref lhs, ref rhs) => {
145 rewrite_assignment(context, lhs, rhs, None, shape)
147 ast::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => {
148 rewrite_assignment(context, lhs, rhs, Some(op), shape)
150 ast::ExprKind::Continue(ref opt_label) => {
151 let id_str = match *opt_label {
152 Some(label) => format!(" {}", label.ident),
153 None => String::new(),
155 Some(format!("continue{}", id_str))
157 ast::ExprKind::Break(ref opt_label, ref opt_expr) => {
158 let id_str = match *opt_label {
159 Some(label) => format!(" {}", label.ident),
160 None => String::new(),
163 if let Some(ref expr) = *opt_expr {
164 rewrite_unary_prefix(context, &format!("break{} ", id_str), &**expr, shape)
166 Some(format!("break{}", id_str))
169 ast::ExprKind::Yield(ref opt_expr) => if let Some(ref expr) = *opt_expr {
170 rewrite_unary_prefix(context, "yield ", &**expr, shape)
172 Some("yield".to_string())
174 ast::ExprKind::Closure(capture, movability, ref fn_decl, ref body, _) => {
175 closures::rewrite_closure(
176 capture, movability, fn_decl, body, expr.span, context, shape,
179 ast::ExprKind::Try(..)
180 | ast::ExprKind::Field(..)
181 | ast::ExprKind::MethodCall(..) => rewrite_chain(expr, context, shape),
182 ast::ExprKind::Mac(ref mac) => {
183 rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| {
185 context.snippet(expr.span).to_owned(),
186 context.config.max_width(),
191 ast::ExprKind::Ret(None) => Some("return".to_owned()),
192 ast::ExprKind::Ret(Some(ref expr)) => {
193 rewrite_unary_prefix(context, "return ", &**expr, shape)
195 ast::ExprKind::Box(ref expr) => rewrite_unary_prefix(context, "box ", &**expr, shape),
196 ast::ExprKind::AddrOf(mutability, ref expr) => {
197 rewrite_expr_addrof(context, mutability, expr, shape)
199 ast::ExprKind::Cast(ref expr, ref ty) => rewrite_pair(
202 PairParts::new("", " as ", ""),
205 SeparatorPlace::Front,
207 ast::ExprKind::Type(ref expr, ref ty) => rewrite_pair(
210 PairParts::new("", ": ", ""),
213 SeparatorPlace::Back,
215 ast::ExprKind::Index(ref expr, ref index) => {
216 rewrite_index(&**expr, &**index, context, shape)
218 ast::ExprKind::Repeat(ref expr, ref repeats) => {
219 let (lbr, rbr) = if context.config.spaces_within_parens_and_brackets() {
227 PairParts::new(lbr, "; ", rbr),
230 SeparatorPlace::Back,
233 ast::ExprKind::Range(ref lhs, ref rhs, limits) => {
234 let delim = match limits {
235 ast::RangeLimits::HalfOpen => "..",
236 ast::RangeLimits::Closed => "..=",
239 fn needs_space_before_range(context: &RewriteContext, lhs: &ast::Expr) -> bool {
241 ast::ExprKind::Lit(ref lit) => match lit.node {
242 ast::LitKind::FloatUnsuffixed(..) => {
243 context.snippet(lit.span).ends_with('.')
251 match (lhs.as_ref().map(|x| &**x), rhs.as_ref().map(|x| &**x)) {
252 (Some(lhs), Some(rhs)) => {
253 let sp_delim = if context.config.spaces_around_ranges() {
254 format!(" {} ", delim)
255 } else if needs_space_before_range(context, lhs) {
256 format!(" {}", delim)
263 PairParts::new("", &sp_delim, ""),
266 context.config.binop_separator(),
269 (None, Some(rhs)) => {
270 let sp_delim = if context.config.spaces_around_ranges() {
271 format!("{} ", delim)
275 rewrite_unary_prefix(context, &sp_delim, &*rhs, shape)
277 (Some(lhs), None) => {
278 let sp_delim = if context.config.spaces_around_ranges() {
279 format!(" {}", delim)
283 rewrite_unary_suffix(context, &sp_delim, &*lhs, shape)
285 (None, None) => Some(delim.to_owned()),
288 // We do not format these expressions yet, but they should still
289 // satisfy our width restrictions.
290 ast::ExprKind::InlineAsm(..) => Some(context.snippet(expr.span).to_owned()),
291 ast::ExprKind::Catch(ref block) => {
292 if let rw @ Some(_) =
293 rewrite_single_line_block(context, "do catch ", block, Some(&expr.attrs), shape)
298 let budget = shape.width.checked_sub(9).unwrap_or(0);
306 Shape::legacy(budget, shape.indent)
314 .and_then(|expr_str| recover_comment_removed(expr_str, expr.span, context))
315 .and_then(|expr_str| {
316 let attrs = outer_attributes(&expr.attrs);
317 let attrs_str = attrs.rewrite(context, shape)?;
319 attrs.last().map_or(expr.span.lo(), |attr| attr.span.hi()),
322 combine_strs_with_missing_comments(context, &attrs_str, &expr_str, span, shape, false)
326 #[derive(new, Clone, Copy)]
327 pub struct PairParts<'a> {
333 pub fn rewrite_pair<LHS, RHS>(
337 context: &RewriteContext,
339 separator_place: SeparatorPlace,
345 let lhs_overhead = match separator_place {
346 SeparatorPlace::Back => shape.used_width() + pp.prefix.len() + pp.infix.trim_right().len(),
347 SeparatorPlace::Front => shape.used_width(),
349 let lhs_shape = Shape {
350 width: context.budget(lhs_overhead),
353 let lhs_result = lhs.rewrite(context, lhs_shape)
354 .map(|lhs_str| format!("{}{}", pp.prefix, lhs_str))?;
356 // Try to put both lhs and rhs on the same line.
357 let rhs_orig_result = shape
358 .offset_left(last_line_width(&lhs_result) + pp.infix.len())
359 .and_then(|s| s.sub_width(pp.suffix.len()))
360 .and_then(|rhs_shape| rhs.rewrite(context, rhs_shape));
361 if let Some(ref rhs_result) = rhs_orig_result {
362 // If the length of the lhs is equal to or shorter than the tab width or
363 // the rhs looks like block expression, we put the rhs on the same
364 // line with the lhs even if the rhs is multi-lined.
365 let allow_same_line = lhs_result.len() <= context.config.tab_spaces()
369 .map(|first_line| first_line.ends_with('{'))
371 if !rhs_result.contains('\n') || allow_same_line {
372 let one_line_width = last_line_width(&lhs_result) + pp.infix.len()
373 + first_line_width(rhs_result) + pp.suffix.len();
374 if one_line_width <= shape.width {
377 lhs_result, pp.infix, rhs_result, pp.suffix
383 // We have to use multiple lines.
384 // Re-evaluate the rhs because we have more space now:
385 let mut rhs_shape = match context.config.indent_style() {
386 IndentStyle::Visual => shape
387 .sub_width(pp.suffix.len() + pp.prefix.len())?
388 .visual_indent(pp.prefix.len()),
389 IndentStyle::Block => {
390 // Try to calculate the initial constraint on the right hand side.
391 let rhs_overhead = shape.rhs_overhead(context.config);
392 Shape::indented(shape.indent.block_indent(context.config), context.config)
393 .sub_width(rhs_overhead)?
396 let infix = match separator_place {
397 SeparatorPlace::Back => pp.infix.trim_right(),
398 SeparatorPlace::Front => pp.infix.trim_left(),
400 if separator_place == SeparatorPlace::Front {
401 rhs_shape = rhs_shape.offset_left(infix.len())?;
403 let rhs_result = rhs.rewrite(context, rhs_shape)?;
404 let indent_str = rhs_shape.indent.to_string_with_newline(context.config);
405 let infix_with_sep = match separator_place {
406 SeparatorPlace::Back => format!("{}{}", infix, indent_str),
407 SeparatorPlace::Front => format!("{}{}", indent_str, infix),
411 lhs_result, infix_with_sep, rhs_result, pp.suffix
415 pub fn rewrite_array<T: Rewrite + Spanned + ToExpr>(
419 context: &RewriteContext,
421 force_separator_tactic: Option<SeparatorTactic>,
422 delim_token: Option<DelimToken>,
423 ) -> Option<String> {
424 overflow::rewrite_with_square_brackets(
430 force_separator_tactic,
435 fn rewrite_empty_block(
436 context: &RewriteContext,
438 attrs: Option<&[ast::Attribute]>,
441 ) -> Option<String> {
442 if attrs.map_or(false, |a| !inner_attributes(a).is_empty()) {
446 if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) && shape.width >= 2
448 return Some(format!("{}{{}}", prefix));
451 // If a block contains only a single-line comment, then leave it on one line.
452 let user_str = context.snippet(block.span);
453 let user_str = user_str.trim();
454 if user_str.starts_with('{') && user_str.ends_with('}') {
455 let comment_str = user_str[1..user_str.len() - 1].trim();
456 if block.stmts.is_empty() && !comment_str.contains('\n') && !comment_str.starts_with("//")
457 && comment_str.len() + 4 <= shape.width
459 return Some(format!("{}{{ {} }}", prefix, comment_str));
466 fn block_prefix(context: &RewriteContext, block: &ast::Block, shape: Shape) -> Option<String> {
467 Some(match block.rules {
468 ast::BlockCheckMode::Unsafe(..) => {
469 let snippet = context.snippet(block.span);
470 let open_pos = snippet.find_uncommented("{")?;
471 // Extract comment between unsafe and block start.
472 let trimmed = &snippet[6..open_pos].trim();
474 if !trimmed.is_empty() {
475 // 9 = "unsafe {".len(), 7 = "unsafe ".len()
476 let budget = shape.width.checked_sub(9)?;
482 Shape::legacy(budget, shape.indent + 7),
490 ast::BlockCheckMode::Default => String::new(),
494 fn rewrite_single_line_block(
495 context: &RewriteContext,
498 attrs: Option<&[ast::Attribute]>,
500 ) -> Option<String> {
501 if is_simple_block(block, attrs, context.codemap) {
502 let expr_shape = shape.offset_left(last_line_width(prefix))?;
503 let expr_str = block.stmts[0].rewrite(context, expr_shape)?;
504 let result = format!("{}{{ {} }}", prefix, expr_str);
505 if result.len() <= shape.width && !result.contains('\n') {
512 pub fn rewrite_block_with_visitor(
513 context: &RewriteContext,
516 attrs: Option<&[ast::Attribute]>,
519 ) -> Option<String> {
520 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, prefix, shape) {
524 let mut visitor = FmtVisitor::from_context(context);
525 visitor.block_indent = shape.indent;
526 visitor.is_if_else_block = context.is_if_else_block();
528 ast::BlockCheckMode::Unsafe(..) => {
529 let snippet = context.snippet(block.span);
530 let open_pos = snippet.find_uncommented("{")?;
531 visitor.last_pos = block.span.lo() + BytePos(open_pos as u32)
533 ast::BlockCheckMode::Default => visitor.last_pos = block.span.lo(),
536 let inner_attrs = attrs.map(inner_attributes);
537 visitor.visit_block(block, inner_attrs.as_ref().map(|a| &**a), has_braces);
538 Some(format!("{}{}", prefix, visitor.buffer))
541 impl Rewrite for ast::Block {
542 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
543 rewrite_block(self, None, context, shape)
549 attrs: Option<&[ast::Attribute]>,
550 context: &RewriteContext,
552 ) -> Option<String> {
553 let prefix = block_prefix(context, block, shape)?;
555 // shape.width is used only for the single line case: either the empty block `{}`,
556 // or an unsafe expression `unsafe { e }`.
557 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, &prefix, shape) {
561 let result = rewrite_block_with_visitor(context, &prefix, block, attrs, shape, true);
562 if let Some(ref result_str) = result {
563 if result_str.lines().count() <= 3 {
564 if let rw @ Some(_) = rewrite_single_line_block(context, &prefix, block, attrs, shape) {
573 impl Rewrite for ast::Stmt {
574 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
575 skip_out_of_file_lines_range!(context, self.span());
577 let result = match self.node {
578 ast::StmtKind::Local(ref local) => local.rewrite(context, shape),
579 ast::StmtKind::Expr(ref ex) | ast::StmtKind::Semi(ref ex) => {
580 let suffix = if semicolon_for_stmt(context, self) {
586 let shape = shape.sub_width(suffix.len())?;
587 format_expr(ex, ExprType::Statement, context, shape).map(|s| s + suffix)
589 ast::StmtKind::Mac(..) | ast::StmtKind::Item(..) => None,
591 result.and_then(|res| recover_comment_removed(res, self.span(), context))
595 // Rewrite condition if the given expression has one.
596 pub fn rewrite_cond(context: &RewriteContext, expr: &ast::Expr, shape: Shape) -> Option<String> {
598 ast::ExprKind::Match(ref cond, _) => {
600 let cond_shape = match context.config.indent_style() {
601 IndentStyle::Visual => shape.shrink_left(6).and_then(|s| s.sub_width(2))?,
602 IndentStyle::Block => shape.offset_left(8)?,
604 cond.rewrite(context, cond_shape)
606 _ => to_control_flow(expr, ExprType::SubExpression).and_then(|control_flow| {
608 String::from("\n") + &shape.indent.block_only().to_string(context.config);
610 .rewrite_cond(context, shape, &alt_block_sep)
611 .and_then(|rw| Some(rw.0))
616 // Abstraction over control flow expressions
618 struct ControlFlow<'a> {
619 cond: Option<&'a ast::Expr>,
620 block: &'a ast::Block,
621 else_block: Option<&'a ast::Expr>,
622 label: Option<ast::Label>,
623 pats: Vec<&'a ast::Pat>,
627 allow_single_line: bool,
628 // True if this is an `if` expression in an `else if` :-( hacky
633 fn to_control_flow(expr: &ast::Expr, expr_type: ExprType) -> Option<ControlFlow> {
635 ast::ExprKind::If(ref cond, ref if_block, ref else_block) => Some(ControlFlow::new_if(
639 else_block.as_ref().map(|e| &**e),
640 expr_type == ExprType::SubExpression,
644 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref else_block) => {
645 Some(ControlFlow::new_if(
647 ptr_vec_to_ref_vec(pat),
649 else_block.as_ref().map(|e| &**e),
650 expr_type == ExprType::SubExpression,
655 ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
656 Some(ControlFlow::new_for(pat, cond, block, label, expr.span))
658 ast::ExprKind::Loop(ref block, label) => {
659 Some(ControlFlow::new_loop(block, label, expr.span))
661 ast::ExprKind::While(ref cond, ref block, label) => Some(ControlFlow::new_while(
668 ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => Some(
669 ControlFlow::new_while(ptr_vec_to_ref_vec(pat), cond, block, label, expr.span),
675 fn choose_matcher(pats: &[&ast::Pat]) -> &'static str {
683 impl<'a> ControlFlow<'a> {
686 pats: Vec<&'a ast::Pat>,
687 block: &'a ast::Block,
688 else_block: Option<&'a ast::Expr>,
689 allow_single_line: bool,
692 ) -> ControlFlow<'a> {
693 let matcher = choose_matcher(&pats);
709 fn new_loop(block: &'a ast::Block, label: Option<ast::Label>, span: Span) -> ControlFlow<'a> {
719 allow_single_line: false,
726 pats: Vec<&'a ast::Pat>,
728 block: &'a ast::Block,
729 label: Option<ast::Label>,
731 ) -> ControlFlow<'a> {
732 let matcher = choose_matcher(&pats);
742 allow_single_line: false,
751 block: &'a ast::Block,
752 label: Option<ast::Label>,
754 ) -> ControlFlow<'a> {
764 allow_single_line: false,
770 fn rewrite_single_line(
773 context: &RewriteContext,
775 ) -> Option<String> {
776 assert!(self.allow_single_line);
777 let else_block = self.else_block?;
778 let fixed_cost = self.keyword.len() + " { } else { }".len();
780 if let ast::ExprKind::Block(ref else_node) = else_block.node {
781 if !is_simple_block(self.block, None, context.codemap)
782 || !is_simple_block(else_node, None, context.codemap)
783 || pat_expr_str.contains('\n')
788 let new_width = width.checked_sub(pat_expr_str.len() + fixed_cost)?;
789 let expr = &self.block.stmts[0];
790 let if_str = expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
792 let new_width = new_width.checked_sub(if_str.len())?;
793 let else_expr = &else_node.stmts[0];
794 let else_str = else_expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
796 if if_str.contains('\n') || else_str.contains('\n') {
800 let result = format!(
801 "{} {} {{ {} }} else {{ {} }}",
802 self.keyword, pat_expr_str, if_str, else_str
805 if result.len() <= width {
814 impl<'a> ControlFlow<'a> {
817 context: &RewriteContext,
821 ) -> Option<String> {
822 debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, self.pats, expr);
824 let cond_shape = shape.offset_left(offset)?;
825 if !self.pats.is_empty() {
826 let matcher = if self.matcher.is_empty() {
827 self.matcher.to_owned()
829 format!("{} ", self.matcher)
831 let pat_shape = cond_shape
832 .offset_left(matcher.len())?
833 .sub_width(self.connector.len())?;
834 let pat_string = rewrite_multiple_patterns(context, &self.pats, pat_shape)?;
835 let result = format!("{}{}{}", matcher, pat_string, self.connector);
836 return rewrite_assign_rhs(context, result, expr, cond_shape);
839 let expr_rw = expr.rewrite(context, cond_shape);
840 // The expression may (partially) fit on the current line.
841 // We do not allow splitting between `if` and condition.
842 if self.keyword == "if" || expr_rw.is_some() {
846 // The expression won't fit on the current line, jump to next.
847 let nested_shape = shape
848 .block_indent(context.config.tab_spaces())
849 .with_max_width(context.config);
850 let nested_indent_str = nested_shape.indent.to_string_with_newline(context.config);
851 expr.rewrite(context, nested_shape)
852 .map(|expr_rw| format!("{}{}", nested_indent_str, expr_rw))
857 context: &RewriteContext,
860 ) -> Option<(String, usize)> {
861 // Do not take the rhs overhead from the upper expressions into account
862 // when rewriting pattern.
863 let new_width = context.budget(shape.used_width());
864 let fresh_shape = Shape {
868 let constr_shape = if self.nested_if {
869 // We are part of an if-elseif-else chain. Our constraints are tightened.
870 // 7 = "} else " .len()
871 fresh_shape.offset_left(7)?
876 let label_string = rewrite_label(self.label);
877 // 1 = space after keyword.
878 let offset = self.keyword.len() + label_string.len() + 1;
880 let pat_expr_string = match self.cond {
881 Some(cond) => self.rewrite_pat_expr(context, cond, constr_shape, offset)?,
882 None => String::new(),
886 if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
892 let one_line_budget = context
895 .checked_sub(constr_shape.used_width() + offset + brace_overhead)
897 let force_newline_brace = (pat_expr_string.contains('\n')
898 || pat_expr_string.len() > one_line_budget)
899 && !last_line_extendable(&pat_expr_string);
901 // Try to format if-else on single line.
902 if self.allow_single_line
906 .single_line_if_else_max_width > 0
908 let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width);
910 if let Some(cond_str) = trial {
915 .single_line_if_else_max_width
917 return Some((cond_str, 0));
922 let cond_span = if let Some(cond) = self.cond {
925 mk_sp(self.block.span.lo(), self.block.span.lo())
928 // `for event in event`
929 // Do not include label in the span.
931 .map_or(self.span.lo(), |label| label.ident.span.hi());
932 let between_kwd_cond = mk_sp(
935 .span_after(mk_sp(lo, self.span.hi()), self.keyword.trim()),
936 if self.pats.is_empty() {
938 } else if self.matcher.is_empty() {
939 self.pats[0].span.lo()
943 .span_before(self.span, self.matcher.trim())
947 let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape);
949 let after_cond_comment =
950 extract_comment(mk_sp(cond_span.hi(), self.block.span.lo()), context, shape);
952 let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
954 } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine
955 || force_newline_brace
962 let used_width = if pat_expr_string.contains('\n') {
963 last_line_width(&pat_expr_string)
965 // 2 = spaces after keyword and condition.
966 label_string.len() + self.keyword.len() + pat_expr_string.len() + 2
974 between_kwd_cond_comment.as_ref().map_or(
975 if pat_expr_string.is_empty() || pat_expr_string.starts_with('\n') {
983 after_cond_comment.as_ref().map_or(block_sep, |s| &**s)
990 impl<'a> Rewrite for ControlFlow<'a> {
991 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
992 debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
994 let alt_block_sep = &shape.indent.to_string_with_newline(context.config);
995 let (cond_str, used_width) = self.rewrite_cond(context, shape, alt_block_sep)?;
996 // If `used_width` is 0, it indicates that whole control flow is written in a single line.
998 return Some(cond_str);
1001 let block_width = shape.width.checked_sub(used_width).unwrap_or(0);
1002 // This is used only for the empty block case: `{}`. So, we use 1 if we know
1003 // we should avoid the single line case.
1004 let block_width = if self.else_block.is_some() || self.nested_if {
1009 let block_shape = Shape {
1014 let old_val = context.is_if_else_block.replace(self.else_block.is_some());
1016 rewrite_block_with_visitor(context, "", self.block, None, block_shape, true);
1017 context.is_if_else_block.replace(old_val);
1021 let mut result = format!("{}{}", cond_str, block_str);
1023 if let Some(else_block) = self.else_block {
1024 let shape = Shape::indented(shape.indent, context.config);
1025 let mut last_in_chain = false;
1026 let rewrite = match else_block.node {
1027 // If the else expression is another if-else expression, prevent it
1028 // from being formatted on a single line.
1029 // Note how we're passing the original shape, as the
1030 // cost of "else" should not cascade.
1031 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref next_else_block) => {
1032 ControlFlow::new_if(
1034 ptr_vec_to_ref_vec(pat),
1036 next_else_block.as_ref().map(|e| &**e),
1039 mk_sp(else_block.span.lo(), self.span.hi()),
1040 ).rewrite(context, shape)
1042 ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => {
1043 ControlFlow::new_if(
1047 next_else_block.as_ref().map(|e| &**e),
1050 mk_sp(else_block.span.lo(), self.span.hi()),
1051 ).rewrite(context, shape)
1054 last_in_chain = true;
1055 // When rewriting a block, the width is only used for single line
1056 // blocks, passing 1 lets us avoid that.
1057 let else_shape = Shape {
1058 width: min(1, shape.width),
1061 format_expr(else_block, ExprType::Statement, context, else_shape)
1065 let between_kwd_else_block = mk_sp(
1066 self.block.span.hi(),
1069 .span_before(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1071 let between_kwd_else_block_comment =
1072 extract_comment(between_kwd_else_block, context, shape);
1074 let after_else = mk_sp(
1077 .span_after(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1078 else_block.span.lo(),
1080 let after_else_comment = extract_comment(after_else, context, shape);
1082 let between_sep = match context.config.control_brace_style() {
1083 ControlBraceStyle::AlwaysNextLine | ControlBraceStyle::ClosingNextLine => {
1086 ControlBraceStyle::AlwaysSameLine => " ",
1088 let after_sep = match context.config.control_brace_style() {
1089 ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep,
1093 result.push_str(&format!(
1095 between_kwd_else_block_comment
1097 .map_or(between_sep, |s| &**s),
1098 after_else_comment.as_ref().map_or(after_sep, |s| &**s),
1100 result.push_str(&rewrite?);
1107 fn rewrite_label(opt_label: Option<ast::Label>) -> Cow<'static, str> {
1109 Some(label) => Cow::from(format!("{}: ", label.ident)),
1110 None => Cow::from(""),
1114 fn extract_comment(span: Span, context: &RewriteContext, shape: Shape) -> Option<String> {
1115 match rewrite_missing_comment(span, shape, context) {
1116 Some(ref comment) if !comment.is_empty() => Some(format!(
1117 "{indent}{}{indent}",
1119 indent = shape.indent.to_string_with_newline(context.config)
1125 pub fn block_contains_comment(block: &ast::Block, codemap: &CodeMap) -> bool {
1126 let snippet = codemap.span_to_snippet(block.span).unwrap();
1127 contains_comment(&snippet)
1130 // Checks that a block contains no statements, an expression and no comments or
1132 // FIXME: incorrectly returns false when comment is contained completely within
1134 pub fn is_simple_block(
1136 attrs: Option<&[ast::Attribute]>,
1139 (block.stmts.len() == 1 && stmt_is_expr(&block.stmts[0])
1140 && !block_contains_comment(block, codemap) && attrs.map_or(true, |a| a.is_empty()))
1143 /// Checks whether a block contains at most one statement or expression, and no
1144 /// comments or attributes.
1145 pub fn is_simple_block_stmt(
1147 attrs: Option<&[ast::Attribute]>,
1150 block.stmts.len() <= 1 && !block_contains_comment(block, codemap)
1151 && attrs.map_or(true, |a| a.is_empty())
1154 /// Checks whether a block contains no statements, expressions, comments, or
1155 /// inner attributes.
1156 pub fn is_empty_block(
1158 attrs: Option<&[ast::Attribute]>,
1161 block.stmts.is_empty() && !block_contains_comment(block, codemap)
1162 && attrs.map_or(true, |a| inner_attributes(a).is_empty())
1165 pub fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
1167 ast::StmtKind::Expr(..) => true,
1172 pub fn is_unsafe_block(block: &ast::Block) -> bool {
1173 if let ast::BlockCheckMode::Unsafe(..) = block.rules {
1180 pub fn rewrite_multiple_patterns(
1181 context: &RewriteContext,
1184 ) -> Option<String> {
1185 let pat_strs = pats.iter()
1186 .map(|p| p.rewrite(context, shape))
1187 .collect::<Option<Vec<_>>>()?;
1189 let use_mixed_layout = pats.iter()
1190 .zip(pat_strs.iter())
1191 .all(|(pat, pat_str)| is_short_pattern(pat, pat_str));
1192 let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
1193 let tactic = if use_mixed_layout {
1194 DefinitiveListTactic::Mixed
1198 ListTactic::HorizontalVertical,
1199 Separator::VerticalBar,
1203 let fmt = ListFormatting {
1206 trailing_separator: SeparatorTactic::Never,
1207 separator_place: context.config.binop_separator(),
1209 ends_with_newline: false,
1210 preserve_newline: false,
1211 config: context.config,
1213 write_list(&items, &fmt)
1216 pub fn rewrite_literal(context: &RewriteContext, l: &ast::Lit, shape: Shape) -> Option<String> {
1218 ast::LitKind::Str(_, ast::StrStyle::Cooked) => rewrite_string_lit(context, l.span, shape),
1220 context.snippet(l.span).to_owned(),
1221 context.config.max_width(),
1227 fn rewrite_string_lit(context: &RewriteContext, span: Span, shape: Shape) -> Option<String> {
1228 let string_lit = context.snippet(span);
1230 if !context.config.format_strings() {
1235 .all(|line| line.ends_with('\\'))
1237 let new_indent = shape.visual_indent(1).indent;
1238 let indented_string_lit = String::from(
1244 new_indent.to_string(context.config),
1248 .collect::<Vec<_>>()
1252 return wrap_str(indented_string_lit, context.config.max_width(), shape);
1254 return wrap_str(string_lit.to_owned(), context.config.max_width(), shape);
1258 // Remove the quote characters.
1259 let str_lit = &string_lit[1..string_lit.len() - 1];
1263 &StringFormat::new(shape.visual_indent(0), context.config),
1268 /// In case special-case style is required, returns an offset from which we start horizontal layout.
1269 pub fn maybe_get_args_offset<T: ToExpr>(callee_str: &str, args: &[&T]) -> Option<(bool, usize)> {
1270 if let Some(&(_, num_args_before)) = SPECIAL_MACRO_WHITELIST
1272 .find(|&&(s, _)| s == callee_str)
1274 let all_simple = args.len() > num_args_before && is_every_expr_simple(args);
1276 Some((all_simple, num_args_before))
1282 /// A list of `format!`-like macros, that take a long format string and a list of arguments to
1285 /// Organized as a list of `(&str, usize)` tuples, giving the name of the macro and the number of
1286 /// arguments before the format string (none for `format!("format", ...)`, one for `assert!(result,
1287 /// "format", ...)`, two for `assert_eq!(left, right, "format", ...)`).
1288 const SPECIAL_MACRO_WHITELIST: &[(&str, usize)] = &[
1289 // format! like macros
1290 // From the Rust Standard Library.
1294 ("format_args!", 0),
1298 ("unreachable!", 0),
1299 // From the `log` crate.
1304 // write! like macros
1306 ("debug_assert!", 1),
1309 // assert_eq! like macros
1312 ("debug_assert_eq!", 2),
1313 ("debug_assert_ne!", 2),
1316 pub fn rewrite_call(
1317 context: &RewriteContext,
1319 args: &[ptr::P<ast::Expr>],
1322 ) -> Option<String> {
1323 overflow::rewrite_with_parens(
1326 &ptr_vec_to_ref_vec(args),
1329 context.config.width_heuristics().fn_call_width,
1330 if context.inside_macro() {
1331 if span_ends_with_comma(context, span) {
1332 Some(SeparatorTactic::Always)
1334 Some(SeparatorTactic::Never)
1342 fn is_simple_expr(expr: &ast::Expr) -> bool {
1344 ast::ExprKind::Lit(..) => true,
1345 ast::ExprKind::Path(ref qself, ref path) => qself.is_none() && path.segments.len() <= 1,
1346 ast::ExprKind::AddrOf(_, ref expr)
1347 | ast::ExprKind::Box(ref expr)
1348 | ast::ExprKind::Cast(ref expr, _)
1349 | ast::ExprKind::Field(ref expr, _)
1350 | ast::ExprKind::Try(ref expr)
1351 | ast::ExprKind::Unary(_, ref expr) => is_simple_expr(expr),
1352 ast::ExprKind::Index(ref lhs, ref rhs) | ast::ExprKind::Repeat(ref lhs, ref rhs) => {
1353 is_simple_expr(lhs) && is_simple_expr(rhs)
1359 pub fn is_every_expr_simple<T: ToExpr>(lists: &[&T]) -> bool {
1362 .all(|arg| arg.to_expr().map_or(false, is_simple_expr))
1365 pub fn can_be_overflowed_expr(context: &RewriteContext, expr: &ast::Expr, args_len: usize) -> bool {
1367 ast::ExprKind::Match(..) => {
1368 (context.use_block_indent() && args_len == 1)
1369 || (context.config.indent_style() == IndentStyle::Visual && args_len > 1)
1371 ast::ExprKind::If(..)
1372 | ast::ExprKind::IfLet(..)
1373 | ast::ExprKind::ForLoop(..)
1374 | ast::ExprKind::Loop(..)
1375 | ast::ExprKind::While(..)
1376 | ast::ExprKind::WhileLet(..) => {
1377 context.config.combine_control_expr() && context.use_block_indent() && args_len == 1
1379 ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => {
1380 context.use_block_indent()
1381 || context.config.indent_style() == IndentStyle::Visual && args_len > 1
1383 ast::ExprKind::Array(..)
1384 | ast::ExprKind::Call(..)
1385 | ast::ExprKind::Mac(..)
1386 | ast::ExprKind::MethodCall(..)
1387 | ast::ExprKind::Struct(..)
1388 | ast::ExprKind::Tup(..) => context.use_block_indent() && args_len == 1,
1389 ast::ExprKind::AddrOf(_, ref expr)
1390 | ast::ExprKind::Box(ref expr)
1391 | ast::ExprKind::Try(ref expr)
1392 | ast::ExprKind::Unary(_, ref expr)
1393 | ast::ExprKind::Cast(ref expr, _) => can_be_overflowed_expr(context, expr, args_len),
1398 pub fn is_nested_call(expr: &ast::Expr) -> bool {
1400 ast::ExprKind::Call(..) | ast::ExprKind::Mac(..) => true,
1401 ast::ExprKind::AddrOf(_, ref expr)
1402 | ast::ExprKind::Box(ref expr)
1403 | ast::ExprKind::Try(ref expr)
1404 | ast::ExprKind::Unary(_, ref expr)
1405 | ast::ExprKind::Cast(ref expr, _) => is_nested_call(expr),
1410 /// Return true if a function call or a method call represented by the given span ends with a
1411 /// trailing comma. This function is used when rewriting macro, as adding or removing a trailing
1412 /// comma from macro can potentially break the code.
1413 pub fn span_ends_with_comma(context: &RewriteContext, span: Span) -> bool {
1414 let mut result: bool = Default::default();
1415 let mut prev_char: char = Default::default();
1417 for (kind, c) in CharClasses::new(context.snippet(span).chars()) {
1419 _ if kind.is_comment() || c.is_whitespace() => continue,
1420 ')' | '}' => result = result && prev_char != ')' && prev_char != '}',
1421 ',' => result = true,
1422 _ => result = false,
1431 context: &RewriteContext,
1432 mut subexpr: &ast::Expr,
1435 ) -> Option<String> {
1436 debug!("rewrite_paren, shape: {:?}", shape);
1438 // Extract comments within parens.
1439 let mut pre_comment;
1440 let mut post_comment;
1443 let pre_span = mk_sp(span.lo() + BytePos(1), subexpr.span.lo());
1444 let post_span = mk_sp(subexpr.span.hi(), span.hi() - BytePos(1));
1445 pre_comment = rewrite_missing_comment(pre_span, shape, context)?;
1446 post_comment = rewrite_missing_comment(post_span, shape, context)?;
1448 // Remove nested parens if there are no comments.
1449 if let ast::ExprKind::Paren(ref subsubexpr) = subexpr.node {
1450 if pre_comment.is_empty() && post_comment.is_empty() {
1451 span = subexpr.span;
1452 subexpr = subsubexpr;
1460 let total_paren_overhead = paren_overhead(context);
1461 let paren_overhead = total_paren_overhead / 2;
1462 let sub_shape = shape
1463 .offset_left(paren_overhead)
1464 .and_then(|s| s.sub_width(paren_overhead))?;
1466 let paren_wrapper = |s: &str| {
1467 if context.config.spaces_within_parens_and_brackets() && !s.is_empty() {
1468 format!("( {}{}{} )", pre_comment, s, post_comment)
1470 format!("({}{}{})", pre_comment, s, post_comment)
1474 let subexpr_str = subexpr.rewrite(context, sub_shape)?;
1475 debug!("rewrite_paren, subexpr_str: `{:?}`", subexpr_str);
1477 if subexpr_str.contains('\n')
1478 || first_line_width(&subexpr_str) + total_paren_overhead <= shape.width
1480 Some(paren_wrapper(&subexpr_str))
1489 context: &RewriteContext,
1491 ) -> Option<String> {
1492 let expr_str = expr.rewrite(context, shape)?;
1494 let (lbr, rbr) = if context.config.spaces_within_parens_and_brackets() {
1500 let offset = last_line_width(&expr_str) + lbr.len();
1501 let rhs_overhead = shape.rhs_overhead(context.config);
1502 let index_shape = if expr_str.contains('\n') {
1503 Shape::legacy(context.config.max_width(), shape.indent)
1504 .offset_left(offset)
1505 .and_then(|shape| shape.sub_width(rbr.len() + rhs_overhead))
1507 shape.visual_indent(offset).sub_width(offset + rbr.len())
1509 let orig_index_rw = index_shape.and_then(|s| index.rewrite(context, s));
1511 // Return if index fits in a single line.
1512 match orig_index_rw {
1513 Some(ref index_str) if !index_str.contains('\n') => {
1514 return Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr));
1519 // Try putting index on the next line and see if it fits in a single line.
1520 let indent = shape.indent.block_indent(context.config);
1521 let index_shape = Shape::indented(indent, context.config).offset_left(lbr.len())?;
1522 let index_shape = index_shape.sub_width(rbr.len() + rhs_overhead)?;
1523 let new_index_rw = index.rewrite(context, index_shape);
1524 match (orig_index_rw, new_index_rw) {
1525 (_, Some(ref new_index_str)) if !new_index_str.contains('\n') => Some(format!(
1528 indent.to_string_with_newline(context.config),
1533 (None, Some(ref new_index_str)) => Some(format!(
1536 indent.to_string_with_newline(context.config),
1541 (Some(ref index_str), _) => Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr)),
1546 fn struct_lit_can_be_aligned(fields: &[ast::Field], base: &Option<&ast::Expr>) -> bool {
1551 fields.iter().all(|field| !field.is_shorthand)
1554 fn rewrite_struct_lit<'a>(
1555 context: &RewriteContext,
1557 fields: &'a [ast::Field],
1558 base: Option<&'a ast::Expr>,
1561 ) -> Option<String> {
1562 debug!("rewrite_struct_lit: shape {:?}", shape);
1564 enum StructLitField<'a> {
1565 Regular(&'a ast::Field),
1566 Base(&'a ast::Expr),
1570 let path_shape = shape.sub_width(2)?;
1571 let path_str = rewrite_path(context, PathContext::Expr, None, path, path_shape)?;
1573 if fields.is_empty() && base.is_none() {
1574 return Some(format!("{} {{}}", path_str));
1577 // Foo { a: Foo } - indent is +3, width is -5.
1578 let (h_shape, v_shape) = struct_lit_shape(shape, context, path_str.len() + 3, 2)?;
1580 let one_line_width = h_shape.map_or(0, |shape| shape.width);
1581 let body_lo = context.snippet_provider.span_after(span, "{");
1582 let fields_str = if struct_lit_can_be_aligned(fields, &base)
1583 && context.config.struct_field_align_threshold() > 0
1585 rewrite_with_alignment(
1589 mk_sp(body_lo, span.hi()),
1593 let field_iter = fields
1595 .map(StructLitField::Regular)
1596 .chain(base.into_iter().map(StructLitField::Base));
1598 let span_lo = |item: &StructLitField| match *item {
1599 StructLitField::Regular(field) => field.span().lo(),
1600 StructLitField::Base(expr) => {
1601 let last_field_hi = fields.last().map_or(span.lo(), |field| field.span.hi());
1602 let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo()));
1603 let pos = snippet.find_uncommented("..").unwrap();
1604 last_field_hi + BytePos(pos as u32)
1607 let span_hi = |item: &StructLitField| match *item {
1608 StructLitField::Regular(field) => field.span().hi(),
1609 StructLitField::Base(expr) => expr.span.hi(),
1611 let rewrite = |item: &StructLitField| match *item {
1612 StructLitField::Regular(field) => {
1613 // The 1 taken from the v_budget is for the comma.
1614 rewrite_field(context, field, v_shape.sub_width(1)?, 0)
1616 StructLitField::Base(expr) => {
1618 expr.rewrite(context, v_shape.offset_left(2)?)
1619 .map(|s| format!("..{}", s))
1623 let items = itemize_list(
1624 context.snippet_provider,
1635 let item_vec = items.collect::<Vec<_>>();
1637 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
1638 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
1640 let ends_with_comma = span_ends_with_comma(context, span);
1641 let force_no_trailing_comma = if context.inside_macro() && !ends_with_comma {
1647 let fmt = struct_lit_formatting(
1651 force_no_trailing_comma || base.is_some(),
1654 write_list(&item_vec, &fmt)?
1657 let fields_str = wrap_struct_field(context, &fields_str, shape, v_shape, one_line_width);
1658 Some(format!("{} {{{}}}", path_str, fields_str))
1660 // FIXME if context.config.indent_style() == Visual, but we run out
1661 // of space, we should fall back to BlockIndent.
1664 pub fn wrap_struct_field(
1665 context: &RewriteContext,
1668 nested_shape: Shape,
1669 one_line_width: usize,
1671 if context.config.indent_style() == IndentStyle::Block
1672 && (fields_str.contains('\n') || !context.config.struct_lit_single_line()
1673 || fields_str.len() > one_line_width)
1677 nested_shape.indent.to_string_with_newline(context.config),
1679 shape.indent.to_string_with_newline(context.config)
1682 // One liner or visual indent.
1683 format!(" {} ", fields_str)
1687 pub fn struct_lit_field_separator(config: &Config) -> &str {
1688 colon_spaces(config.space_before_colon(), config.space_after_colon())
1691 pub fn rewrite_field(
1692 context: &RewriteContext,
1695 prefix_max_width: usize,
1696 ) -> Option<String> {
1697 if contains_skip(&field.attrs) {
1698 return Some(context.snippet(field.span()).to_owned());
1700 let mut attrs_str = field.attrs.rewrite(context, shape)?;
1701 if !attrs_str.is_empty() {
1702 attrs_str.push_str(&shape.indent.to_string_with_newline(context.config));
1704 let name = &field.ident.name.to_string();
1705 if field.is_shorthand {
1706 Some(attrs_str + &name)
1708 let mut separator = String::from(struct_lit_field_separator(context.config));
1709 for _ in 0..prefix_max_width.checked_sub(name.len()).unwrap_or(0) {
1710 separator.push(' ');
1712 let overhead = name.len() + separator.len();
1713 let expr_shape = shape.offset_left(overhead)?;
1714 let expr = field.expr.rewrite(context, expr_shape);
1717 Some(ref e) if e.as_str() == name && context.config.use_field_init_shorthand() => {
1718 Some(attrs_str + &name)
1720 Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)),
1722 let expr_offset = shape.indent.block_indent(context.config);
1725 .rewrite(context, Shape::indented(expr_offset, context.config));
1731 expr_offset.to_string(context.config),
1740 fn rewrite_tuple_in_visual_indent_style<'a, T>(
1741 context: &RewriteContext,
1747 T: Rewrite + Spanned + ToExpr + 'a,
1749 let mut items = items.iter();
1750 // In case of length 1, need a trailing comma
1751 debug!("rewrite_tuple_in_visual_indent_style {:?}", shape);
1752 if items.len() == 1 {
1754 let nested_shape = shape.sub_width(3)?.visual_indent(1);
1758 .rewrite(context, nested_shape)
1760 if context.config.spaces_within_parens_and_brackets() {
1761 format!("( {}, )", s)
1768 let list_lo = context.snippet_provider.span_after(span, "(");
1769 let nested_shape = shape.sub_width(2)?.visual_indent(1);
1770 let items = itemize_list(
1771 context.snippet_provider,
1775 |item| item.span().lo(),
1776 |item| item.span().hi(),
1777 |item| item.rewrite(context, nested_shape),
1779 span.hi() - BytePos(1),
1782 let item_vec: Vec<_> = items.collect();
1783 let tactic = definitive_tactic(
1785 ListTactic::HorizontalVertical,
1789 let fmt = ListFormatting {
1792 trailing_separator: SeparatorTactic::Never,
1793 separator_place: SeparatorPlace::Back,
1795 ends_with_newline: false,
1796 preserve_newline: false,
1797 config: context.config,
1799 let list_str = write_list(&item_vec, &fmt)?;
1801 if context.config.spaces_within_parens_and_brackets() && !list_str.is_empty() {
1802 Some(format!("( {} )", list_str))
1804 Some(format!("({})", list_str))
1808 pub fn rewrite_tuple<'a, T>(
1809 context: &RewriteContext,
1815 T: Rewrite + Spanned + ToExpr + 'a,
1817 debug!("rewrite_tuple {:?}", shape);
1818 if context.use_block_indent() {
1819 // We use the same rule as function calls for rewriting tuples.
1820 let force_tactic = if context.inside_macro() {
1821 if span_ends_with_comma(context, span) {
1822 Some(SeparatorTactic::Always)
1824 Some(SeparatorTactic::Never)
1827 if items.len() == 1 {
1828 Some(SeparatorTactic::Always)
1833 overflow::rewrite_with_parens(
1839 context.config.width_heuristics().fn_call_width,
1843 rewrite_tuple_in_visual_indent_style(context, items, span, shape)
1847 pub fn rewrite_unary_prefix<R: Rewrite>(
1848 context: &RewriteContext,
1852 ) -> Option<String> {
1854 .rewrite(context, shape.offset_left(prefix.len())?)
1855 .map(|r| format!("{}{}", prefix, r))
1858 // FIXME: this is probably not correct for multi-line Rewrites. we should
1859 // subtract suffix.len() from the last line budget, not the first!
1860 pub fn rewrite_unary_suffix<R: Rewrite>(
1861 context: &RewriteContext,
1865 ) -> Option<String> {
1867 .rewrite(context, shape.sub_width(suffix.len())?)
1874 fn rewrite_unary_op(
1875 context: &RewriteContext,
1879 ) -> Option<String> {
1880 // For some reason, an UnOp is not spanned like BinOp!
1881 let operator_str = match *op {
1882 ast::UnOp::Deref => "*",
1883 ast::UnOp::Not => "!",
1884 ast::UnOp::Neg => "-",
1886 rewrite_unary_prefix(context, operator_str, expr, shape)
1889 fn rewrite_assignment(
1890 context: &RewriteContext,
1893 op: Option<&ast::BinOp>,
1895 ) -> Option<String> {
1896 let operator_str = match op {
1897 Some(op) => context.snippet(op.span),
1901 // 1 = space between lhs and operator.
1902 let lhs_shape = shape.sub_width(operator_str.len() + 1)?;
1903 let lhs_str = format!("{} {}", lhs.rewrite(context, lhs_shape)?, operator_str);
1905 rewrite_assign_rhs(context, lhs_str, rhs, shape)
1908 /// Controls where to put the rhs.
1909 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
1910 pub enum RhsTactics {
1913 /// Put the rhs on the next line if it uses multiple line.
1917 // The left hand side must contain everything up to, and including, the
1918 // assignment operator.
1919 pub fn rewrite_assign_rhs<S: Into<String>, R: Rewrite>(
1920 context: &RewriteContext,
1924 ) -> Option<String> {
1925 rewrite_assign_rhs_with(context, lhs, ex, shape, RhsTactics::Default)
1928 pub fn rewrite_assign_rhs_with<S: Into<String>, R: Rewrite>(
1929 context: &RewriteContext,
1933 rhs_tactics: RhsTactics,
1934 ) -> Option<String> {
1935 let lhs = lhs.into();
1936 let last_line_width = last_line_width(&lhs)
1937 .checked_sub(if lhs.contains('\n') {
1938 shape.indent.width()
1943 // 1 = space between operator and rhs.
1944 let orig_shape = shape.offset_left(last_line_width + 1).unwrap_or(Shape {
1946 offset: shape.offset + last_line_width + 1,
1949 let rhs = choose_rhs(
1953 ex.rewrite(context, orig_shape),
1959 fn choose_rhs<R: Rewrite>(
1960 context: &RewriteContext,
1963 orig_rhs: Option<String>,
1964 rhs_tactics: RhsTactics,
1965 ) -> Option<String> {
1967 Some(ref new_str) if !new_str.contains('\n') && new_str.len() <= shape.width => {
1968 Some(format!(" {}", new_str))
1971 // Expression did not fit on the same line as the identifier.
1972 // Try splitting the line and see if that works better.
1974 Shape::indented(shape.indent.block_indent(context.config), context.config)
1975 .sub_width(shape.rhs_overhead(context.config))?;
1976 let new_rhs = expr.rewrite(context, new_shape);
1977 let new_indent_str = &new_shape.indent.to_string_with_newline(context.config);
1979 match (orig_rhs, new_rhs) {
1980 (Some(ref orig_rhs), Some(ref new_rhs))
1981 if wrap_str(new_rhs.clone(), context.config.max_width(), new_shape)
1984 Some(format!(" {}", orig_rhs))
1986 (Some(ref orig_rhs), Some(ref new_rhs))
1987 if prefer_next_line(orig_rhs, new_rhs, rhs_tactics) =>
1989 Some(format!("{}{}", new_indent_str, new_rhs))
1991 (None, Some(ref new_rhs)) => Some(format!("{}{}", new_indent_str, new_rhs)),
1992 (None, None) => None,
1993 (Some(ref orig_rhs), _) => Some(format!(" {}", orig_rhs)),
1999 pub fn prefer_next_line(orig_rhs: &str, next_line_rhs: &str, rhs_tactics: RhsTactics) -> bool {
2000 rhs_tactics == RhsTactics::ForceNextLine || !next_line_rhs.contains('\n')
2001 || count_newlines(orig_rhs) > count_newlines(next_line_rhs) + 1
2004 fn rewrite_expr_addrof(
2005 context: &RewriteContext,
2006 mutability: ast::Mutability,
2009 ) -> Option<String> {
2010 let operator_str = match mutability {
2011 ast::Mutability::Immutable => "&",
2012 ast::Mutability::Mutable => "&mut ",
2014 rewrite_unary_prefix(context, operator_str, expr, shape)
2018 fn to_expr(&self) -> Option<&ast::Expr>;
2019 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool;
2022 impl ToExpr for ast::Expr {
2023 fn to_expr(&self) -> Option<&ast::Expr> {
2027 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2028 can_be_overflowed_expr(context, self, len)
2032 impl ToExpr for ast::Ty {
2033 fn to_expr(&self) -> Option<&ast::Expr> {
2037 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2038 can_be_overflowed_type(context, self, len)
2042 impl<'a> ToExpr for TuplePatField<'a> {
2043 fn to_expr(&self) -> Option<&ast::Expr> {
2047 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2048 can_be_overflowed_pat(context, self, len)
2052 impl<'a> ToExpr for ast::StructField {
2053 fn to_expr(&self) -> Option<&ast::Expr> {
2057 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {
2062 impl<'a> ToExpr for MacroArg {
2063 fn to_expr(&self) -> Option<&ast::Expr> {
2065 MacroArg::Expr(ref expr) => Some(expr),
2070 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2072 MacroArg::Expr(ref expr) => can_be_overflowed_expr(context, expr, len),
2073 MacroArg::Ty(ref ty) => can_be_overflowed_type(context, ty, len),
2074 MacroArg::Pat(..) => false,
2075 MacroArg::Item(..) => len == 1,
2080 impl ToExpr for ast::GenericParam {
2081 fn to_expr(&self) -> Option<&ast::Expr> {
2085 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {