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::TupField(..)
182 | ast::ExprKind::MethodCall(..) => rewrite_chain(expr, context, shape),
183 ast::ExprKind::Mac(ref mac) => {
184 rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| {
186 context.snippet(expr.span).to_owned(),
187 context.config.max_width(),
192 ast::ExprKind::Ret(None) => Some("return".to_owned()),
193 ast::ExprKind::Ret(Some(ref expr)) => {
194 rewrite_unary_prefix(context, "return ", &**expr, shape)
196 ast::ExprKind::Box(ref expr) => rewrite_unary_prefix(context, "box ", &**expr, shape),
197 ast::ExprKind::AddrOf(mutability, ref expr) => {
198 rewrite_expr_addrof(context, mutability, expr, shape)
200 ast::ExprKind::Cast(ref expr, ref ty) => rewrite_pair(
203 PairParts::new("", " as ", ""),
206 SeparatorPlace::Front,
208 ast::ExprKind::Type(ref expr, ref ty) => rewrite_pair(
211 PairParts::new("", ": ", ""),
214 SeparatorPlace::Back,
216 ast::ExprKind::Index(ref expr, ref index) => {
217 rewrite_index(&**expr, &**index, context, shape)
219 ast::ExprKind::Repeat(ref expr, ref repeats) => {
220 let (lbr, rbr) = if context.config.spaces_within_parens_and_brackets() {
228 PairParts::new(lbr, "; ", rbr),
231 SeparatorPlace::Back,
234 ast::ExprKind::Range(ref lhs, ref rhs, limits) => {
235 let delim = match limits {
236 ast::RangeLimits::HalfOpen => "..",
237 ast::RangeLimits::Closed => "..=",
240 fn needs_space_before_range(context: &RewriteContext, lhs: &ast::Expr) -> bool {
242 ast::ExprKind::Lit(ref lit) => match lit.node {
243 ast::LitKind::FloatUnsuffixed(..) => {
244 context.snippet(lit.span).ends_with('.')
252 match (lhs.as_ref().map(|x| &**x), rhs.as_ref().map(|x| &**x)) {
253 (Some(lhs), Some(rhs)) => {
254 let sp_delim = if context.config.spaces_around_ranges() {
255 format!(" {} ", delim)
256 } else if needs_space_before_range(context, lhs) {
257 format!(" {}", delim)
264 PairParts::new("", &sp_delim, ""),
267 context.config.binop_separator(),
270 (None, Some(rhs)) => {
271 let sp_delim = if context.config.spaces_around_ranges() {
272 format!("{} ", delim)
276 rewrite_unary_prefix(context, &sp_delim, &*rhs, shape)
278 (Some(lhs), None) => {
279 let sp_delim = if context.config.spaces_around_ranges() {
280 format!(" {}", delim)
284 rewrite_unary_suffix(context, &sp_delim, &*lhs, shape)
286 (None, None) => Some(delim.to_owned()),
289 // We do not format these expressions yet, but they should still
290 // satisfy our width restrictions.
291 ast::ExprKind::InPlace(..) | ast::ExprKind::InlineAsm(..) => {
292 Some(context.snippet(expr.span).to_owned())
294 ast::ExprKind::Catch(ref block) => {
295 if let rw @ Some(_) =
296 rewrite_single_line_block(context, "do catch ", block, Some(&expr.attrs), shape)
301 let budget = shape.width.checked_sub(9).unwrap_or(0);
309 Shape::legacy(budget, shape.indent)
317 .and_then(|expr_str| recover_comment_removed(expr_str, expr.span, context))
318 .and_then(|expr_str| {
319 let attrs = outer_attributes(&expr.attrs);
320 let attrs_str = attrs.rewrite(context, shape)?;
322 attrs.last().map_or(expr.span.lo(), |attr| attr.span.hi()),
325 combine_strs_with_missing_comments(context, &attrs_str, &expr_str, span, shape, false)
329 #[derive(new, Clone, Copy)]
330 pub struct PairParts<'a> {
336 pub fn rewrite_pair<LHS, RHS>(
340 context: &RewriteContext,
342 separator_place: SeparatorPlace,
348 let lhs_overhead = match separator_place {
349 SeparatorPlace::Back => shape.used_width() + pp.prefix.len() + pp.infix.trim_right().len(),
350 SeparatorPlace::Front => shape.used_width(),
352 let lhs_shape = Shape {
353 width: context.budget(lhs_overhead),
356 let lhs_result = lhs.rewrite(context, lhs_shape)
357 .map(|lhs_str| format!("{}{}", pp.prefix, lhs_str))?;
359 // Try to put both lhs and rhs on the same line.
360 let rhs_orig_result = shape
361 .offset_left(last_line_width(&lhs_result) + pp.infix.len())
362 .and_then(|s| s.sub_width(pp.suffix.len()))
363 .and_then(|rhs_shape| rhs.rewrite(context, rhs_shape));
364 if let Some(ref rhs_result) = rhs_orig_result {
365 // If the length of the lhs is equal to or shorter than the tab width or
366 // the rhs looks like block expression, we put the rhs on the same
367 // line with the lhs even if the rhs is multi-lined.
368 let allow_same_line = lhs_result.len() <= context.config.tab_spaces()
372 .map(|first_line| first_line.ends_with('{'))
374 if !rhs_result.contains('\n') || allow_same_line {
375 let one_line_width = last_line_width(&lhs_result) + pp.infix.len()
376 + first_line_width(rhs_result) + pp.suffix.len();
377 if one_line_width <= shape.width {
380 lhs_result, pp.infix, rhs_result, pp.suffix
386 // We have to use multiple lines.
387 // Re-evaluate the rhs because we have more space now:
388 let mut rhs_shape = match context.config.indent_style() {
389 IndentStyle::Visual => shape
390 .sub_width(pp.suffix.len() + pp.prefix.len())?
391 .visual_indent(pp.prefix.len()),
392 IndentStyle::Block => {
393 // Try to calculate the initial constraint on the right hand side.
394 let rhs_overhead = shape.rhs_overhead(context.config);
395 Shape::indented(shape.indent.block_indent(context.config), context.config)
396 .sub_width(rhs_overhead)?
399 let infix = match separator_place {
400 SeparatorPlace::Back => pp.infix.trim_right(),
401 SeparatorPlace::Front => pp.infix.trim_left(),
403 if separator_place == SeparatorPlace::Front {
404 rhs_shape = rhs_shape.offset_left(infix.len())?;
406 let rhs_result = rhs.rewrite(context, rhs_shape)?;
407 let indent_str = rhs_shape.indent.to_string_with_newline(context.config);
408 let infix_with_sep = match separator_place {
409 SeparatorPlace::Back => format!("{}{}", infix, indent_str),
410 SeparatorPlace::Front => format!("{}{}", indent_str, infix),
414 lhs_result, infix_with_sep, rhs_result, pp.suffix
418 pub fn rewrite_array<T: Rewrite + Spanned + ToExpr>(
422 context: &RewriteContext,
424 force_separator_tactic: Option<SeparatorTactic>,
425 delim_token: Option<DelimToken>,
426 ) -> Option<String> {
427 overflow::rewrite_with_square_brackets(
433 force_separator_tactic,
438 fn rewrite_empty_block(
439 context: &RewriteContext,
441 attrs: Option<&[ast::Attribute]>,
444 ) -> Option<String> {
445 if attrs.map_or(false, |a| !inner_attributes(a).is_empty()) {
449 if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) && shape.width >= 2
451 return Some(format!("{}{{}}", prefix));
454 // If a block contains only a single-line comment, then leave it on one line.
455 let user_str = context.snippet(block.span);
456 let user_str = user_str.trim();
457 if user_str.starts_with('{') && user_str.ends_with('}') {
458 let comment_str = user_str[1..user_str.len() - 1].trim();
459 if block.stmts.is_empty() && !comment_str.contains('\n') && !comment_str.starts_with("//")
460 && comment_str.len() + 4 <= shape.width
462 return Some(format!("{}{{ {} }}", prefix, comment_str));
469 fn block_prefix(context: &RewriteContext, block: &ast::Block, shape: Shape) -> Option<String> {
470 Some(match block.rules {
471 ast::BlockCheckMode::Unsafe(..) => {
472 let snippet = context.snippet(block.span);
473 let open_pos = snippet.find_uncommented("{")?;
474 // Extract comment between unsafe and block start.
475 let trimmed = &snippet[6..open_pos].trim();
477 if !trimmed.is_empty() {
478 // 9 = "unsafe {".len(), 7 = "unsafe ".len()
479 let budget = shape.width.checked_sub(9)?;
485 Shape::legacy(budget, shape.indent + 7),
493 ast::BlockCheckMode::Default => String::new(),
497 fn rewrite_single_line_block(
498 context: &RewriteContext,
501 attrs: Option<&[ast::Attribute]>,
503 ) -> Option<String> {
504 if is_simple_block(block, attrs, context.codemap) {
505 let expr_shape = shape.offset_left(last_line_width(prefix))?;
506 let expr_str = block.stmts[0].rewrite(context, expr_shape)?;
507 let result = format!("{}{{ {} }}", prefix, expr_str);
508 if result.len() <= shape.width && !result.contains('\n') {
515 pub fn rewrite_block_with_visitor(
516 context: &RewriteContext,
519 attrs: Option<&[ast::Attribute]>,
522 ) -> Option<String> {
523 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, prefix, shape) {
527 let mut visitor = FmtVisitor::from_context(context);
528 visitor.block_indent = shape.indent;
529 visitor.is_if_else_block = context.is_if_else_block();
531 ast::BlockCheckMode::Unsafe(..) => {
532 let snippet = context.snippet(block.span);
533 let open_pos = snippet.find_uncommented("{")?;
534 visitor.last_pos = block.span.lo() + BytePos(open_pos as u32)
536 ast::BlockCheckMode::Default => visitor.last_pos = block.span.lo(),
539 let inner_attrs = attrs.map(inner_attributes);
540 visitor.visit_block(block, inner_attrs.as_ref().map(|a| &**a), has_braces);
541 Some(format!("{}{}", prefix, visitor.buffer))
544 impl Rewrite for ast::Block {
545 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
546 rewrite_block(self, None, context, shape)
552 attrs: Option<&[ast::Attribute]>,
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, &prefix, shape) {
564 let result = rewrite_block_with_visitor(context, &prefix, block, attrs, shape, true);
565 if let Some(ref result_str) = result {
566 if result_str.lines().count() <= 3 {
567 if let rw @ Some(_) = rewrite_single_line_block(context, &prefix, block, attrs, shape) {
576 impl Rewrite for ast::Stmt {
577 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
578 skip_out_of_file_lines_range!(context, self.span());
580 let result = match self.node {
581 ast::StmtKind::Local(ref local) => local.rewrite(context, shape),
582 ast::StmtKind::Expr(ref ex) | ast::StmtKind::Semi(ref ex) => {
583 let suffix = if semicolon_for_stmt(context, self) {
589 let shape = shape.sub_width(suffix.len())?;
590 format_expr(ex, ExprType::Statement, context, shape).map(|s| s + suffix)
592 ast::StmtKind::Mac(..) | ast::StmtKind::Item(..) => None,
594 result.and_then(|res| recover_comment_removed(res, self.span(), context))
598 // Rewrite condition if the given expression has one.
599 pub fn rewrite_cond(context: &RewriteContext, expr: &ast::Expr, shape: Shape) -> Option<String> {
601 ast::ExprKind::Match(ref cond, _) => {
603 let cond_shape = match context.config.indent_style() {
604 IndentStyle::Visual => shape.shrink_left(6).and_then(|s| s.sub_width(2))?,
605 IndentStyle::Block => shape.offset_left(8)?,
607 cond.rewrite(context, cond_shape)
609 _ => to_control_flow(expr, ExprType::SubExpression).and_then(|control_flow| {
611 String::from("\n") + &shape.indent.block_only().to_string(context.config);
613 .rewrite_cond(context, shape, &alt_block_sep)
614 .and_then(|rw| Some(rw.0))
619 // Abstraction over control flow expressions
621 struct ControlFlow<'a> {
622 cond: Option<&'a ast::Expr>,
623 block: &'a ast::Block,
624 else_block: Option<&'a ast::Expr>,
625 label: Option<ast::Label>,
626 pats: Vec<&'a ast::Pat>,
630 allow_single_line: bool,
631 // True if this is an `if` expression in an `else if` :-( hacky
636 fn to_control_flow(expr: &ast::Expr, expr_type: ExprType) -> Option<ControlFlow> {
638 ast::ExprKind::If(ref cond, ref if_block, ref else_block) => Some(ControlFlow::new_if(
642 else_block.as_ref().map(|e| &**e),
643 expr_type == ExprType::SubExpression,
647 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref else_block) => {
648 Some(ControlFlow::new_if(
650 ptr_vec_to_ref_vec(pat),
652 else_block.as_ref().map(|e| &**e),
653 expr_type == ExprType::SubExpression,
658 ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
659 Some(ControlFlow::new_for(pat, cond, block, label, expr.span))
661 ast::ExprKind::Loop(ref block, label) => {
662 Some(ControlFlow::new_loop(block, label, expr.span))
664 ast::ExprKind::While(ref cond, ref block, label) => Some(ControlFlow::new_while(
671 ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => Some(
672 ControlFlow::new_while(ptr_vec_to_ref_vec(pat), cond, block, label, expr.span),
678 fn choose_matcher(pats: &[&ast::Pat]) -> &'static str {
686 impl<'a> ControlFlow<'a> {
689 pats: Vec<&'a ast::Pat>,
690 block: &'a ast::Block,
691 else_block: Option<&'a ast::Expr>,
692 allow_single_line: bool,
695 ) -> ControlFlow<'a> {
696 let matcher = choose_matcher(&pats);
712 fn new_loop(block: &'a ast::Block, label: Option<ast::Label>, span: Span) -> ControlFlow<'a> {
722 allow_single_line: false,
729 pats: Vec<&'a ast::Pat>,
731 block: &'a ast::Block,
732 label: Option<ast::Label>,
734 ) -> ControlFlow<'a> {
735 let matcher = choose_matcher(&pats);
745 allow_single_line: false,
754 block: &'a ast::Block,
755 label: Option<ast::Label>,
757 ) -> ControlFlow<'a> {
767 allow_single_line: false,
773 fn rewrite_single_line(
776 context: &RewriteContext,
778 ) -> Option<String> {
779 assert!(self.allow_single_line);
780 let else_block = self.else_block?;
781 let fixed_cost = self.keyword.len() + " { } else { }".len();
783 if let ast::ExprKind::Block(ref else_node) = else_block.node {
784 if !is_simple_block(self.block, None, context.codemap)
785 || !is_simple_block(else_node, None, context.codemap)
786 || pat_expr_str.contains('\n')
791 let new_width = width.checked_sub(pat_expr_str.len() + fixed_cost)?;
792 let expr = &self.block.stmts[0];
793 let if_str = expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
795 let new_width = new_width.checked_sub(if_str.len())?;
796 let else_expr = &else_node.stmts[0];
797 let else_str = else_expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
799 if if_str.contains('\n') || else_str.contains('\n') {
803 let result = format!(
804 "{} {} {{ {} }} else {{ {} }}",
805 self.keyword, pat_expr_str, if_str, else_str
808 if result.len() <= width {
817 impl<'a> ControlFlow<'a> {
820 context: &RewriteContext,
824 ) -> Option<String> {
825 debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, self.pats, expr);
827 let cond_shape = shape.offset_left(offset)?;
828 if !self.pats.is_empty() {
829 let matcher = if self.matcher.is_empty() {
830 self.matcher.to_owned()
832 format!("{} ", self.matcher)
834 let pat_shape = cond_shape
835 .offset_left(matcher.len())?
836 .sub_width(self.connector.len())?;
837 let pat_string = rewrite_multiple_patterns(context, &self.pats, pat_shape)?;
838 let result = format!("{}{}{}", matcher, pat_string, self.connector);
839 return rewrite_assign_rhs(context, result, expr, cond_shape);
842 let expr_rw = expr.rewrite(context, cond_shape);
843 // The expression may (partially) fit on the current line.
844 // We do not allow splitting between `if` and condition.
845 if self.keyword == "if" || expr_rw.is_some() {
849 // The expression won't fit on the current line, jump to next.
850 let nested_shape = shape
851 .block_indent(context.config.tab_spaces())
852 .with_max_width(context.config);
853 let nested_indent_str = nested_shape.indent.to_string_with_newline(context.config);
854 expr.rewrite(context, nested_shape)
855 .map(|expr_rw| format!("{}{}", nested_indent_str, expr_rw))
860 context: &RewriteContext,
863 ) -> Option<(String, usize)> {
864 // Do not take the rhs overhead from the upper expressions into account
865 // when rewriting pattern.
866 let new_width = context.budget(shape.used_width());
867 let fresh_shape = Shape {
871 let constr_shape = if self.nested_if {
872 // We are part of an if-elseif-else chain. Our constraints are tightened.
873 // 7 = "} else " .len()
874 fresh_shape.offset_left(7)?
879 let label_string = rewrite_label(self.label);
880 // 1 = space after keyword.
881 let offset = self.keyword.len() + label_string.len() + 1;
883 let pat_expr_string = match self.cond {
884 Some(cond) => self.rewrite_pat_expr(context, cond, constr_shape, offset)?,
885 None => String::new(),
889 if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
895 let one_line_budget = context
898 .checked_sub(constr_shape.used_width() + offset + brace_overhead)
900 let force_newline_brace = (pat_expr_string.contains('\n')
901 || pat_expr_string.len() > one_line_budget)
902 && !last_line_extendable(&pat_expr_string);
904 // Try to format if-else on single line.
905 if self.allow_single_line
909 .single_line_if_else_max_width > 0
911 let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width);
913 if let Some(cond_str) = trial {
918 .single_line_if_else_max_width
920 return Some((cond_str, 0));
925 let cond_span = if let Some(cond) = self.cond {
928 mk_sp(self.block.span.lo(), self.block.span.lo())
931 // `for event in event`
932 // Do not include label in the span.
933 let lo = self.label.map_or(self.span.lo(), |label| label.span.hi());
934 let between_kwd_cond = mk_sp(
937 .span_after(mk_sp(lo, self.span.hi()), self.keyword.trim()),
938 if self.pats.is_empty() {
940 } else if self.matcher.is_empty() {
941 self.pats[0].span.lo()
945 .span_before(self.span, self.matcher.trim())
949 let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape);
951 let after_cond_comment =
952 extract_comment(mk_sp(cond_span.hi(), self.block.span.lo()), context, shape);
954 let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
956 } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine
957 || force_newline_brace
964 let used_width = if pat_expr_string.contains('\n') {
965 last_line_width(&pat_expr_string)
967 // 2 = spaces after keyword and condition.
968 label_string.len() + self.keyword.len() + pat_expr_string.len() + 2
976 between_kwd_cond_comment.as_ref().map_or(
977 if pat_expr_string.is_empty() || pat_expr_string.starts_with('\n') {
985 after_cond_comment.as_ref().map_or(block_sep, |s| &**s)
992 impl<'a> Rewrite for ControlFlow<'a> {
993 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
994 debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
996 let alt_block_sep = &shape.indent.to_string_with_newline(context.config);
997 let (cond_str, used_width) = self.rewrite_cond(context, shape, alt_block_sep)?;
998 // If `used_width` is 0, it indicates that whole control flow is written in a single line.
1000 return Some(cond_str);
1003 let block_width = shape.width.checked_sub(used_width).unwrap_or(0);
1004 // This is used only for the empty block case: `{}`. So, we use 1 if we know
1005 // we should avoid the single line case.
1006 let block_width = if self.else_block.is_some() || self.nested_if {
1011 let block_shape = Shape {
1016 let old_val = context.is_if_else_block.replace(self.else_block.is_some());
1018 rewrite_block_with_visitor(context, "", self.block, None, block_shape, true);
1019 context.is_if_else_block.replace(old_val);
1023 let mut result = format!("{}{}", cond_str, block_str);
1025 if let Some(else_block) = self.else_block {
1026 let shape = Shape::indented(shape.indent, context.config);
1027 let mut last_in_chain = false;
1028 let rewrite = match else_block.node {
1029 // If the else expression is another if-else expression, prevent it
1030 // from being formatted on a single line.
1031 // Note how we're passing the original shape, as the
1032 // cost of "else" should not cascade.
1033 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref next_else_block) => {
1034 ControlFlow::new_if(
1036 ptr_vec_to_ref_vec(pat),
1038 next_else_block.as_ref().map(|e| &**e),
1041 mk_sp(else_block.span.lo(), self.span.hi()),
1042 ).rewrite(context, shape)
1044 ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => {
1045 ControlFlow::new_if(
1049 next_else_block.as_ref().map(|e| &**e),
1052 mk_sp(else_block.span.lo(), self.span.hi()),
1053 ).rewrite(context, shape)
1056 last_in_chain = true;
1057 // When rewriting a block, the width is only used for single line
1058 // blocks, passing 1 lets us avoid that.
1059 let else_shape = Shape {
1060 width: min(1, shape.width),
1063 format_expr(else_block, ExprType::Statement, context, else_shape)
1067 let between_kwd_else_block = mk_sp(
1068 self.block.span.hi(),
1071 .span_before(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1073 let between_kwd_else_block_comment =
1074 extract_comment(between_kwd_else_block, context, shape);
1076 let after_else = mk_sp(
1079 .span_after(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1080 else_block.span.lo(),
1082 let after_else_comment = extract_comment(after_else, context, shape);
1084 let between_sep = match context.config.control_brace_style() {
1085 ControlBraceStyle::AlwaysNextLine | ControlBraceStyle::ClosingNextLine => {
1088 ControlBraceStyle::AlwaysSameLine => " ",
1090 let after_sep = match context.config.control_brace_style() {
1091 ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep,
1095 result.push_str(&format!(
1097 between_kwd_else_block_comment
1099 .map_or(between_sep, |s| &**s),
1100 after_else_comment.as_ref().map_or(after_sep, |s| &**s),
1102 result.push_str(&rewrite?);
1109 fn rewrite_label(opt_label: Option<ast::Label>) -> Cow<'static, str> {
1111 Some(label) => Cow::from(format!("{}: ", label.ident)),
1112 None => Cow::from(""),
1116 fn extract_comment(span: Span, context: &RewriteContext, shape: Shape) -> Option<String> {
1117 match rewrite_missing_comment(span, shape, context) {
1118 Some(ref comment) if !comment.is_empty() => Some(format!(
1119 "{indent}{}{indent}",
1121 indent = shape.indent.to_string_with_newline(context.config)
1127 pub fn block_contains_comment(block: &ast::Block, codemap: &CodeMap) -> bool {
1128 let snippet = codemap.span_to_snippet(block.span).unwrap();
1129 contains_comment(&snippet)
1132 // Checks that a block contains no statements, an expression and no comments or
1134 // FIXME: incorrectly returns false when comment is contained completely within
1136 pub fn is_simple_block(
1138 attrs: Option<&[ast::Attribute]>,
1141 (block.stmts.len() == 1 && stmt_is_expr(&block.stmts[0])
1142 && !block_contains_comment(block, codemap) && attrs.map_or(true, |a| a.is_empty()))
1145 /// Checks whether a block contains at most one statement or expression, and no
1146 /// comments or attributes.
1147 pub fn is_simple_block_stmt(
1149 attrs: Option<&[ast::Attribute]>,
1152 block.stmts.len() <= 1 && !block_contains_comment(block, codemap)
1153 && attrs.map_or(true, |a| a.is_empty())
1156 /// Checks whether a block contains no statements, expressions, comments, or
1157 /// inner attributes.
1158 pub fn is_empty_block(
1160 attrs: Option<&[ast::Attribute]>,
1163 block.stmts.is_empty() && !block_contains_comment(block, codemap)
1164 && attrs.map_or(true, |a| inner_attributes(a).is_empty())
1167 pub fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
1169 ast::StmtKind::Expr(..) => true,
1174 pub fn is_unsafe_block(block: &ast::Block) -> bool {
1175 if let ast::BlockCheckMode::Unsafe(..) = block.rules {
1182 pub fn rewrite_multiple_patterns(
1183 context: &RewriteContext,
1186 ) -> Option<String> {
1187 let pat_strs = pats.iter()
1188 .map(|p| p.rewrite(context, shape))
1189 .collect::<Option<Vec<_>>>()?;
1191 let use_mixed_layout = pats.iter()
1192 .zip(pat_strs.iter())
1193 .all(|(pat, pat_str)| is_short_pattern(pat, pat_str));
1194 let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
1195 let tactic = if use_mixed_layout {
1196 DefinitiveListTactic::Mixed
1200 ListTactic::HorizontalVertical,
1201 Separator::VerticalBar,
1205 let fmt = ListFormatting {
1208 trailing_separator: SeparatorTactic::Never,
1209 separator_place: context.config.binop_separator(),
1211 ends_with_newline: false,
1212 preserve_newline: false,
1213 config: context.config,
1215 write_list(&items, &fmt)
1218 pub fn rewrite_literal(context: &RewriteContext, l: &ast::Lit, shape: Shape) -> Option<String> {
1220 ast::LitKind::Str(_, ast::StrStyle::Cooked) => rewrite_string_lit(context, l.span, shape),
1222 context.snippet(l.span).to_owned(),
1223 context.config.max_width(),
1229 fn rewrite_string_lit(context: &RewriteContext, span: Span, shape: Shape) -> Option<String> {
1230 let string_lit = context.snippet(span);
1232 if !context.config.format_strings() {
1237 .all(|line| line.ends_with('\\'))
1239 let new_indent = shape.visual_indent(1).indent;
1240 let indented_string_lit = String::from(
1246 new_indent.to_string(context.config),
1250 .collect::<Vec<_>>()
1254 return wrap_str(indented_string_lit, context.config.max_width(), shape);
1256 return wrap_str(string_lit.to_owned(), context.config.max_width(), shape);
1260 // Remove the quote characters.
1261 let str_lit = &string_lit[1..string_lit.len() - 1];
1265 &StringFormat::new(shape.visual_indent(0), context.config),
1270 /// In case special-case style is required, returns an offset from which we start horizontal layout.
1271 pub fn maybe_get_args_offset<T: ToExpr>(callee_str: &str, args: &[&T]) -> Option<(bool, usize)> {
1272 if let Some(&(_, num_args_before)) = SPECIAL_MACRO_WHITELIST
1274 .find(|&&(s, _)| s == callee_str)
1276 let all_simple = args.len() > num_args_before && is_every_expr_simple(args);
1278 Some((all_simple, num_args_before))
1284 /// A list of `format!`-like macros, that take a long format string and a list of arguments to
1287 /// Organized as a list of `(&str, usize)` tuples, giving the name of the macro and the number of
1288 /// arguments before the format string (none for `format!("format", ...)`, one for `assert!(result,
1289 /// "format", ...)`, two for `assert_eq!(left, right, "format", ...)`).
1290 const SPECIAL_MACRO_WHITELIST: &[(&str, usize)] = &[
1291 // format! like macros
1292 // From the Rust Standard Library.
1296 ("format_args!", 0),
1300 ("unreachable!", 0),
1301 // From the `log` crate.
1306 // write! like macros
1308 ("debug_assert!", 1),
1311 // assert_eq! like macros
1314 ("debug_assert_eq!", 2),
1315 ("debug_assert_ne!", 2),
1318 pub fn rewrite_call(
1319 context: &RewriteContext,
1321 args: &[ptr::P<ast::Expr>],
1324 ) -> Option<String> {
1325 overflow::rewrite_with_parens(
1328 &ptr_vec_to_ref_vec(args),
1331 context.config.width_heuristics().fn_call_width,
1332 if context.inside_macro() {
1333 if span_ends_with_comma(context, span) {
1334 Some(SeparatorTactic::Always)
1336 Some(SeparatorTactic::Never)
1344 fn is_simple_expr(expr: &ast::Expr) -> bool {
1346 ast::ExprKind::Lit(..) => true,
1347 ast::ExprKind::Path(ref qself, ref path) => qself.is_none() && path.segments.len() <= 1,
1348 ast::ExprKind::AddrOf(_, ref expr)
1349 | ast::ExprKind::Box(ref expr)
1350 | ast::ExprKind::Cast(ref expr, _)
1351 | ast::ExprKind::Field(ref expr, _)
1352 | ast::ExprKind::Try(ref expr)
1353 | ast::ExprKind::TupField(ref expr, _)
1354 | ast::ExprKind::Unary(_, ref expr) => is_simple_expr(expr),
1355 ast::ExprKind::Index(ref lhs, ref rhs) | ast::ExprKind::Repeat(ref lhs, ref rhs) => {
1356 is_simple_expr(lhs) && is_simple_expr(rhs)
1362 pub fn is_every_expr_simple<T: ToExpr>(lists: &[&T]) -> bool {
1365 .all(|arg| arg.to_expr().map_or(false, is_simple_expr))
1368 pub fn can_be_overflowed_expr(context: &RewriteContext, expr: &ast::Expr, args_len: usize) -> bool {
1370 ast::ExprKind::Match(..) => {
1371 (context.use_block_indent() && args_len == 1)
1372 || (context.config.indent_style() == IndentStyle::Visual && args_len > 1)
1374 ast::ExprKind::If(..)
1375 | ast::ExprKind::IfLet(..)
1376 | ast::ExprKind::ForLoop(..)
1377 | ast::ExprKind::Loop(..)
1378 | ast::ExprKind::While(..)
1379 | ast::ExprKind::WhileLet(..) => {
1380 context.config.combine_control_expr() && context.use_block_indent() && args_len == 1
1382 ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => {
1383 context.use_block_indent()
1384 || context.config.indent_style() == IndentStyle::Visual && args_len > 1
1386 ast::ExprKind::Array(..)
1387 | ast::ExprKind::Call(..)
1388 | ast::ExprKind::Mac(..)
1389 | ast::ExprKind::MethodCall(..)
1390 | ast::ExprKind::Struct(..)
1391 | ast::ExprKind::Tup(..) => context.use_block_indent() && args_len == 1,
1392 ast::ExprKind::AddrOf(_, ref expr)
1393 | ast::ExprKind::Box(ref expr)
1394 | ast::ExprKind::Try(ref expr)
1395 | ast::ExprKind::Unary(_, ref expr)
1396 | ast::ExprKind::Cast(ref expr, _) => can_be_overflowed_expr(context, expr, args_len),
1401 pub fn is_nested_call(expr: &ast::Expr) -> bool {
1403 ast::ExprKind::Call(..) | ast::ExprKind::Mac(..) => true,
1404 ast::ExprKind::AddrOf(_, ref expr)
1405 | ast::ExprKind::Box(ref expr)
1406 | ast::ExprKind::Try(ref expr)
1407 | ast::ExprKind::Unary(_, ref expr)
1408 | ast::ExprKind::Cast(ref expr, _) => is_nested_call(expr),
1413 /// Return true if a function call or a method call represented by the given span ends with a
1414 /// trailing comma. This function is used when rewriting macro, as adding or removing a trailing
1415 /// comma from macro can potentially break the code.
1416 pub fn span_ends_with_comma(context: &RewriteContext, span: Span) -> bool {
1417 let mut result: bool = Default::default();
1418 let mut prev_char: char = Default::default();
1420 for (kind, c) in CharClasses::new(context.snippet(span).chars()) {
1422 _ if kind.is_comment() || c.is_whitespace() => continue,
1423 ')' | '}' => result = result && prev_char != ')' && prev_char != '}',
1424 ',' => result = true,
1425 _ => result = false,
1434 context: &RewriteContext,
1435 mut subexpr: &ast::Expr,
1438 ) -> Option<String> {
1439 debug!("rewrite_paren, shape: {:?}", shape);
1441 // Extract comments within parens.
1442 let mut pre_comment;
1443 let mut post_comment;
1446 let pre_span = mk_sp(span.lo() + BytePos(1), subexpr.span.lo());
1447 let post_span = mk_sp(subexpr.span.hi(), span.hi() - BytePos(1));
1448 pre_comment = rewrite_missing_comment(pre_span, shape, context)?;
1449 post_comment = rewrite_missing_comment(post_span, shape, context)?;
1451 // Remove nested parens if there are no comments.
1452 if let ast::ExprKind::Paren(ref subsubexpr) = subexpr.node {
1453 if pre_comment.is_empty() && post_comment.is_empty() {
1454 span = subexpr.span;
1455 subexpr = subsubexpr;
1463 let total_paren_overhead = paren_overhead(context);
1464 let paren_overhead = total_paren_overhead / 2;
1465 let sub_shape = shape
1466 .offset_left(paren_overhead)
1467 .and_then(|s| s.sub_width(paren_overhead))?;
1469 let paren_wrapper = |s: &str| {
1470 if context.config.spaces_within_parens_and_brackets() && !s.is_empty() {
1471 format!("( {}{}{} )", pre_comment, s, post_comment)
1473 format!("({}{}{})", pre_comment, s, post_comment)
1477 let subexpr_str = subexpr.rewrite(context, sub_shape)?;
1478 debug!("rewrite_paren, subexpr_str: `{:?}`", subexpr_str);
1480 if subexpr_str.contains('\n')
1481 || first_line_width(&subexpr_str) + total_paren_overhead <= shape.width
1483 Some(paren_wrapper(&subexpr_str))
1492 context: &RewriteContext,
1494 ) -> Option<String> {
1495 let expr_str = expr.rewrite(context, shape)?;
1497 let (lbr, rbr) = if context.config.spaces_within_parens_and_brackets() {
1503 let offset = last_line_width(&expr_str) + lbr.len();
1504 let rhs_overhead = shape.rhs_overhead(context.config);
1505 let index_shape = if expr_str.contains('\n') {
1506 Shape::legacy(context.config.max_width(), shape.indent)
1507 .offset_left(offset)
1508 .and_then(|shape| shape.sub_width(rbr.len() + rhs_overhead))
1510 shape.visual_indent(offset).sub_width(offset + rbr.len())
1512 let orig_index_rw = index_shape.and_then(|s| index.rewrite(context, s));
1514 // Return if index fits in a single line.
1515 match orig_index_rw {
1516 Some(ref index_str) if !index_str.contains('\n') => {
1517 return Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr));
1522 // Try putting index on the next line and see if it fits in a single line.
1523 let indent = shape.indent.block_indent(context.config);
1524 let index_shape = Shape::indented(indent, context.config).offset_left(lbr.len())?;
1525 let index_shape = index_shape.sub_width(rbr.len() + rhs_overhead)?;
1526 let new_index_rw = index.rewrite(context, index_shape);
1527 match (orig_index_rw, new_index_rw) {
1528 (_, Some(ref new_index_str)) if !new_index_str.contains('\n') => Some(format!(
1531 indent.to_string_with_newline(context.config),
1536 (None, Some(ref new_index_str)) => Some(format!(
1539 indent.to_string_with_newline(context.config),
1544 (Some(ref index_str), _) => Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr)),
1549 fn struct_lit_can_be_aligned(fields: &[ast::Field], base: &Option<&ast::Expr>) -> bool {
1554 fields.iter().all(|field| !field.is_shorthand)
1557 fn rewrite_struct_lit<'a>(
1558 context: &RewriteContext,
1560 fields: &'a [ast::Field],
1561 base: Option<&'a ast::Expr>,
1564 ) -> Option<String> {
1565 debug!("rewrite_struct_lit: shape {:?}", shape);
1567 enum StructLitField<'a> {
1568 Regular(&'a ast::Field),
1569 Base(&'a ast::Expr),
1573 let path_shape = shape.sub_width(2)?;
1574 let path_str = rewrite_path(context, PathContext::Expr, None, path, path_shape)?;
1576 if fields.is_empty() && base.is_none() {
1577 return Some(format!("{} {{}}", path_str));
1580 // Foo { a: Foo } - indent is +3, width is -5.
1581 let (h_shape, v_shape) = struct_lit_shape(shape, context, path_str.len() + 3, 2)?;
1583 let one_line_width = h_shape.map_or(0, |shape| shape.width);
1584 let body_lo = context.snippet_provider.span_after(span, "{");
1585 let fields_str = if struct_lit_can_be_aligned(fields, &base)
1586 && context.config.struct_field_align_threshold() > 0
1588 rewrite_with_alignment(
1592 mk_sp(body_lo, span.hi()),
1596 let field_iter = fields
1598 .map(StructLitField::Regular)
1599 .chain(base.into_iter().map(StructLitField::Base));
1601 let span_lo = |item: &StructLitField| match *item {
1602 StructLitField::Regular(field) => field.span().lo(),
1603 StructLitField::Base(expr) => {
1604 let last_field_hi = fields.last().map_or(span.lo(), |field| field.span.hi());
1605 let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo()));
1606 let pos = snippet.find_uncommented("..").unwrap();
1607 last_field_hi + BytePos(pos as u32)
1610 let span_hi = |item: &StructLitField| match *item {
1611 StructLitField::Regular(field) => field.span().hi(),
1612 StructLitField::Base(expr) => expr.span.hi(),
1614 let rewrite = |item: &StructLitField| match *item {
1615 StructLitField::Regular(field) => {
1616 // The 1 taken from the v_budget is for the comma.
1617 rewrite_field(context, field, v_shape.sub_width(1)?, 0)
1619 StructLitField::Base(expr) => {
1621 expr.rewrite(context, v_shape.offset_left(2)?)
1622 .map(|s| format!("..{}", s))
1626 let items = itemize_list(
1627 context.snippet_provider,
1638 let item_vec = items.collect::<Vec<_>>();
1640 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
1641 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
1643 let ends_with_comma = span_ends_with_comma(context, span);
1644 let force_no_trailing_comma = if context.inside_macro() && !ends_with_comma {
1650 let fmt = struct_lit_formatting(
1654 force_no_trailing_comma || base.is_some(),
1657 write_list(&item_vec, &fmt)?
1660 let fields_str = wrap_struct_field(context, &fields_str, shape, v_shape, one_line_width);
1661 Some(format!("{} {{{}}}", path_str, fields_str))
1663 // FIXME if context.config.indent_style() == Visual, but we run out
1664 // of space, we should fall back to BlockIndent.
1667 pub fn wrap_struct_field(
1668 context: &RewriteContext,
1671 nested_shape: Shape,
1672 one_line_width: usize,
1674 if context.config.indent_style() == IndentStyle::Block
1675 && (fields_str.contains('\n') || !context.config.struct_lit_single_line()
1676 || fields_str.len() > one_line_width)
1680 nested_shape.indent.to_string_with_newline(context.config),
1682 shape.indent.to_string_with_newline(context.config)
1685 // One liner or visual indent.
1686 format!(" {} ", fields_str)
1690 pub fn struct_lit_field_separator(config: &Config) -> &str {
1691 colon_spaces(config.space_before_colon(), config.space_after_colon())
1694 pub fn rewrite_field(
1695 context: &RewriteContext,
1698 prefix_max_width: usize,
1699 ) -> Option<String> {
1700 if contains_skip(&field.attrs) {
1701 return Some(context.snippet(field.span()).to_owned());
1703 let mut attrs_str = field.attrs.rewrite(context, shape)?;
1704 if !attrs_str.is_empty() {
1705 attrs_str.push_str(&shape.indent.to_string_with_newline(context.config));
1707 let name = field.ident.node.to_string();
1708 if field.is_shorthand {
1709 Some(attrs_str + &name)
1711 let mut separator = String::from(struct_lit_field_separator(context.config));
1712 for _ in 0..prefix_max_width.checked_sub(name.len()).unwrap_or(0) {
1713 separator.push(' ');
1715 let overhead = name.len() + separator.len();
1716 let expr_shape = shape.offset_left(overhead)?;
1717 let expr = field.expr.rewrite(context, expr_shape);
1720 Some(ref e) if e.as_str() == name && context.config.use_field_init_shorthand() => {
1721 Some(attrs_str + &name)
1723 Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)),
1725 let expr_offset = shape.indent.block_indent(context.config);
1728 .rewrite(context, Shape::indented(expr_offset, context.config));
1734 expr_offset.to_string(context.config),
1743 fn rewrite_tuple_in_visual_indent_style<'a, T>(
1744 context: &RewriteContext,
1750 T: Rewrite + Spanned + ToExpr + 'a,
1752 let mut items = items.iter();
1753 // In case of length 1, need a trailing comma
1754 debug!("rewrite_tuple_in_visual_indent_style {:?}", shape);
1755 if items.len() == 1 {
1757 let nested_shape = shape.sub_width(3)?.visual_indent(1);
1761 .rewrite(context, nested_shape)
1763 if context.config.spaces_within_parens_and_brackets() {
1764 format!("( {}, )", s)
1771 let list_lo = context.snippet_provider.span_after(span, "(");
1772 let nested_shape = shape.sub_width(2)?.visual_indent(1);
1773 let items = itemize_list(
1774 context.snippet_provider,
1778 |item| item.span().lo(),
1779 |item| item.span().hi(),
1780 |item| item.rewrite(context, nested_shape),
1782 span.hi() - BytePos(1),
1785 let item_vec: Vec<_> = items.collect();
1786 let tactic = definitive_tactic(
1788 ListTactic::HorizontalVertical,
1792 let fmt = ListFormatting {
1795 trailing_separator: SeparatorTactic::Never,
1796 separator_place: SeparatorPlace::Back,
1798 ends_with_newline: false,
1799 preserve_newline: false,
1800 config: context.config,
1802 let list_str = write_list(&item_vec, &fmt)?;
1804 if context.config.spaces_within_parens_and_brackets() && !list_str.is_empty() {
1805 Some(format!("( {} )", list_str))
1807 Some(format!("({})", list_str))
1811 pub fn rewrite_tuple<'a, T>(
1812 context: &RewriteContext,
1818 T: Rewrite + Spanned + ToExpr + 'a,
1820 debug!("rewrite_tuple {:?}", shape);
1821 if context.use_block_indent() {
1822 // We use the same rule as function calls for rewriting tuples.
1823 let force_tactic = if context.inside_macro() {
1824 if span_ends_with_comma(context, span) {
1825 Some(SeparatorTactic::Always)
1827 Some(SeparatorTactic::Never)
1830 if items.len() == 1 {
1831 Some(SeparatorTactic::Always)
1836 overflow::rewrite_with_parens(
1842 context.config.width_heuristics().fn_call_width,
1846 rewrite_tuple_in_visual_indent_style(context, items, span, shape)
1850 pub fn rewrite_unary_prefix<R: Rewrite>(
1851 context: &RewriteContext,
1855 ) -> Option<String> {
1857 .rewrite(context, shape.offset_left(prefix.len())?)
1858 .map(|r| format!("{}{}", prefix, r))
1861 // FIXME: this is probably not correct for multi-line Rewrites. we should
1862 // subtract suffix.len() from the last line budget, not the first!
1863 pub fn rewrite_unary_suffix<R: Rewrite>(
1864 context: &RewriteContext,
1868 ) -> Option<String> {
1870 .rewrite(context, shape.sub_width(suffix.len())?)
1877 fn rewrite_unary_op(
1878 context: &RewriteContext,
1882 ) -> Option<String> {
1883 // For some reason, an UnOp is not spanned like BinOp!
1884 let operator_str = match *op {
1885 ast::UnOp::Deref => "*",
1886 ast::UnOp::Not => "!",
1887 ast::UnOp::Neg => "-",
1889 rewrite_unary_prefix(context, operator_str, expr, shape)
1892 fn rewrite_assignment(
1893 context: &RewriteContext,
1896 op: Option<&ast::BinOp>,
1898 ) -> Option<String> {
1899 let operator_str = match op {
1900 Some(op) => context.snippet(op.span),
1904 // 1 = space between lhs and operator.
1905 let lhs_shape = shape.sub_width(operator_str.len() + 1)?;
1906 let lhs_str = format!("{} {}", lhs.rewrite(context, lhs_shape)?, operator_str);
1908 rewrite_assign_rhs(context, lhs_str, rhs, shape)
1911 /// Controls where to put the rhs.
1912 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
1913 pub enum RhsTactics {
1916 /// Put the rhs on the next line if it uses multiple line.
1920 // The left hand side must contain everything up to, and including, the
1921 // assignment operator.
1922 pub fn rewrite_assign_rhs<S: Into<String>, R: Rewrite>(
1923 context: &RewriteContext,
1927 ) -> Option<String> {
1928 rewrite_assign_rhs_with(context, lhs, ex, shape, RhsTactics::Default)
1931 pub fn rewrite_assign_rhs_with<S: Into<String>, R: Rewrite>(
1932 context: &RewriteContext,
1936 rhs_tactics: RhsTactics,
1937 ) -> Option<String> {
1938 let lhs = lhs.into();
1939 let last_line_width = last_line_width(&lhs)
1940 .checked_sub(if lhs.contains('\n') {
1941 shape.indent.width()
1946 // 1 = space between operator and rhs.
1947 let orig_shape = shape.offset_left(last_line_width + 1).unwrap_or(Shape {
1949 offset: shape.offset + last_line_width + 1,
1952 let rhs = choose_rhs(
1956 ex.rewrite(context, orig_shape),
1962 fn choose_rhs<R: Rewrite>(
1963 context: &RewriteContext,
1966 orig_rhs: Option<String>,
1967 rhs_tactics: RhsTactics,
1968 ) -> Option<String> {
1970 Some(ref new_str) if !new_str.contains('\n') && new_str.len() <= shape.width => {
1971 Some(format!(" {}", new_str))
1974 // Expression did not fit on the same line as the identifier.
1975 // Try splitting the line and see if that works better.
1977 Shape::indented(shape.indent.block_indent(context.config), context.config)
1978 .sub_width(shape.rhs_overhead(context.config))?;
1979 let new_rhs = expr.rewrite(context, new_shape);
1980 let new_indent_str = &new_shape.indent.to_string_with_newline(context.config);
1982 match (orig_rhs, new_rhs) {
1983 (Some(ref orig_rhs), Some(ref new_rhs))
1984 if wrap_str(new_rhs.clone(), context.config.max_width(), new_shape)
1987 Some(format!(" {}", orig_rhs))
1989 (Some(ref orig_rhs), Some(ref new_rhs))
1990 if prefer_next_line(orig_rhs, new_rhs, rhs_tactics) =>
1992 Some(format!("{}{}", new_indent_str, new_rhs))
1994 (None, Some(ref new_rhs)) => Some(format!("{}{}", new_indent_str, new_rhs)),
1995 (None, None) => None,
1996 (Some(ref orig_rhs), _) => Some(format!(" {}", orig_rhs)),
2002 pub fn prefer_next_line(orig_rhs: &str, next_line_rhs: &str, rhs_tactics: RhsTactics) -> bool {
2003 rhs_tactics == RhsTactics::ForceNextLine || !next_line_rhs.contains('\n')
2004 || count_newlines(orig_rhs) > count_newlines(next_line_rhs) + 1
2007 fn rewrite_expr_addrof(
2008 context: &RewriteContext,
2009 mutability: ast::Mutability,
2012 ) -> Option<String> {
2013 let operator_str = match mutability {
2014 ast::Mutability::Immutable => "&",
2015 ast::Mutability::Mutable => "&mut ",
2017 rewrite_unary_prefix(context, operator_str, expr, shape)
2021 fn to_expr(&self) -> Option<&ast::Expr>;
2022 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool;
2025 impl ToExpr for ast::Expr {
2026 fn to_expr(&self) -> Option<&ast::Expr> {
2030 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2031 can_be_overflowed_expr(context, self, len)
2035 impl ToExpr for ast::Ty {
2036 fn to_expr(&self) -> Option<&ast::Expr> {
2040 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2041 can_be_overflowed_type(context, self, len)
2045 impl<'a> ToExpr for TuplePatField<'a> {
2046 fn to_expr(&self) -> Option<&ast::Expr> {
2050 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2051 can_be_overflowed_pat(context, self, len)
2055 impl<'a> ToExpr for ast::StructField {
2056 fn to_expr(&self) -> Option<&ast::Expr> {
2060 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {
2065 impl<'a> ToExpr for MacroArg {
2066 fn to_expr(&self) -> Option<&ast::Expr> {
2068 MacroArg::Expr(ref expr) => Some(expr),
2073 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2075 MacroArg::Expr(ref expr) => can_be_overflowed_expr(context, expr, len),
2076 MacroArg::Ty(ref ty) => can_be_overflowed_type(context, ty, len),
2077 MacroArg::Pat(..) => false,
2078 MacroArg::Item(..) => len == 1,
2083 impl ToExpr for ast::GenericParam {
2084 fn to_expr(&self) -> Option<&ast::Expr> {
2088 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {