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};
23 combine_strs_with_missing_comments, contains_comment, recover_comment_removed, rewrite_comment,
24 rewrite_missing_comment, CharClasses, FindUncommented,
26 use config::{Config, ControlBraceStyle, IndentStyle};
28 definitive_tactic, itemize_list, shape_for_tactic, struct_lit_formatting, struct_lit_shape,
29 struct_lit_tactic, write_list, ListFormatting, ListItem, Separator,
31 use macros::{rewrite_macro, MacroArg, MacroPosition};
32 use matches::rewrite_match;
34 use patterns::{can_be_overflowed_pat, is_short_pattern, TuplePatField};
35 use rewrite::{Rewrite, RewriteContext};
36 use shape::{Indent, Shape};
38 use string::{rewrite_string, StringFormat};
39 use types::{can_be_overflowed_type, rewrite_path, PathContext};
41 colon_spaces, contains_skip, count_newlines, first_line_width, inner_attributes,
42 last_line_extendable, last_line_width, mk_sp, outer_attributes, paren_overhead,
43 ptr_vec_to_ref_vec, semicolon_for_stmt, wrap_str,
45 use vertical::rewrite_with_alignment;
46 use visitor::FmtVisitor;
48 impl Rewrite for ast::Expr {
49 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
50 format_expr(self, ExprType::SubExpression, context, shape)
54 #[derive(Copy, Clone, PartialEq)]
63 context: &RewriteContext,
66 skip_out_of_file_lines_range!(context, expr.span);
68 if contains_skip(&*expr.attrs) {
69 return Some(context.snippet(expr.span()).to_owned());
72 let expr_rw = match expr.node {
73 ast::ExprKind::Array(ref expr_vec) => rewrite_array(
75 &ptr_vec_to_ref_vec(expr_vec),
79 choose_separator_tactic(context, expr.span),
82 ast::ExprKind::Lit(ref l) => rewrite_literal(context, l, shape),
83 ast::ExprKind::Call(ref callee, ref args) => {
84 let inner_span = mk_sp(callee.span.hi(), expr.span.hi());
85 let callee_str = callee.rewrite(context, shape)?;
86 rewrite_call(context, &callee_str, args, inner_span, shape)
88 ast::ExprKind::Paren(ref subexpr) => rewrite_paren(context, subexpr, shape, expr.span),
89 ast::ExprKind::Binary(ref op, ref lhs, ref rhs) => {
90 // FIXME: format comments between operands and operator
94 PairParts::new("", &format!(" {} ", context.snippet(op.span)), ""),
97 context.config.binop_separator(),
100 ast::ExprKind::Unary(ref op, ref subexpr) => rewrite_unary_op(context, op, subexpr, shape),
101 ast::ExprKind::Struct(ref path, ref fields, ref base) => rewrite_struct_lit(
105 base.as_ref().map(|e| &**e),
109 ast::ExprKind::Tup(ref items) => {
110 rewrite_tuple(context, &ptr_vec_to_ref_vec(items), expr.span, shape)
112 ast::ExprKind::If(..)
113 | ast::ExprKind::IfLet(..)
114 | ast::ExprKind::ForLoop(..)
115 | ast::ExprKind::Loop(..)
116 | ast::ExprKind::While(..)
117 | ast::ExprKind::WhileLet(..) => to_control_flow(expr, expr_type)
118 .and_then(|control_flow| control_flow.rewrite(context, shape)),
119 ast::ExprKind::Block(ref block) => {
121 ExprType::Statement => {
122 if is_unsafe_block(block) {
123 rewrite_block(block, Some(&expr.attrs), context, shape)
124 } else if let rw @ Some(_) =
125 rewrite_empty_block(context, block, Some(&expr.attrs), "", shape)
127 // Rewrite block without trying to put it in a single line.
130 let prefix = block_prefix(context, block, shape)?;
131 rewrite_block_with_visitor(
141 ExprType::SubExpression => rewrite_block(block, Some(&expr.attrs), context, shape),
144 ast::ExprKind::Match(ref cond, ref arms) => {
145 rewrite_match(context, cond, arms, shape, expr.span, &expr.attrs)
147 ast::ExprKind::Path(ref qself, ref path) => {
148 rewrite_path(context, PathContext::Expr, qself.as_ref(), path, shape)
150 ast::ExprKind::Assign(ref lhs, ref rhs) => {
151 rewrite_assignment(context, lhs, rhs, None, shape)
153 ast::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => {
154 rewrite_assignment(context, lhs, rhs, Some(op), shape)
156 ast::ExprKind::Continue(ref opt_label) => {
157 let id_str = match *opt_label {
158 Some(label) => format!(" {}", label.ident),
159 None => String::new(),
161 Some(format!("continue{}", id_str))
163 ast::ExprKind::Break(ref opt_label, ref opt_expr) => {
164 let id_str = match *opt_label {
165 Some(label) => format!(" {}", label.ident),
166 None => String::new(),
169 if let Some(ref expr) = *opt_expr {
170 rewrite_unary_prefix(context, &format!("break{} ", id_str), &**expr, shape)
172 Some(format!("break{}", id_str))
175 ast::ExprKind::Yield(ref opt_expr) => if let Some(ref expr) = *opt_expr {
176 rewrite_unary_prefix(context, "yield ", &**expr, shape)
178 Some("yield".to_string())
180 ast::ExprKind::Closure(capture, movability, ref fn_decl, ref body, _) => {
181 closures::rewrite_closure(
182 capture, movability, fn_decl, body, expr.span, context, shape,
185 ast::ExprKind::Try(..) | ast::ExprKind::Field(..) | ast::ExprKind::MethodCall(..) => {
186 rewrite_chain(expr, context, shape)
188 ast::ExprKind::Mac(ref mac) => {
189 rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| {
191 context.snippet(expr.span).to_owned(),
192 context.config.max_width(),
197 ast::ExprKind::Ret(None) => Some("return".to_owned()),
198 ast::ExprKind::Ret(Some(ref expr)) => {
199 rewrite_unary_prefix(context, "return ", &**expr, shape)
201 ast::ExprKind::Box(ref expr) => rewrite_unary_prefix(context, "box ", &**expr, shape),
202 ast::ExprKind::AddrOf(mutability, ref expr) => {
203 rewrite_expr_addrof(context, mutability, expr, shape)
205 ast::ExprKind::Cast(ref expr, ref ty) => rewrite_pair(
208 PairParts::new("", " as ", ""),
211 SeparatorPlace::Front,
213 ast::ExprKind::Type(ref expr, ref ty) => rewrite_pair(
216 PairParts::new("", ": ", ""),
219 SeparatorPlace::Back,
221 ast::ExprKind::Index(ref expr, ref index) => {
222 rewrite_index(&**expr, &**index, context, shape)
224 ast::ExprKind::Repeat(ref expr, ref repeats) => {
225 let (lbr, rbr) = if context.config.spaces_within_parens_and_brackets() {
233 PairParts::new(lbr, "; ", rbr),
236 SeparatorPlace::Back,
239 ast::ExprKind::Range(ref lhs, ref rhs, limits) => {
240 let delim = match limits {
241 ast::RangeLimits::HalfOpen => "..",
242 ast::RangeLimits::Closed => "..=",
245 fn needs_space_before_range(context: &RewriteContext, lhs: &ast::Expr) -> bool {
247 ast::ExprKind::Lit(ref lit) => match lit.node {
248 ast::LitKind::FloatUnsuffixed(..) => {
249 context.snippet(lit.span).ends_with('.')
257 fn needs_space_after_range(rhs: &ast::Expr) -> bool {
259 // Don't format `.. ..` into `....`, which is invalid.
261 // This check is unnecessary for `lhs`, because a range
262 // starting from another range needs parentheses as `(x ..) ..`
263 // (`x .. ..` is a range from `x` to `..`).
264 ast::ExprKind::Range(None, _, _) => true,
269 let default_sp_delim = |lhs: Option<&ast::Expr>, rhs: Option<&ast::Expr>| {
270 let space_if = |b: bool| if b { " " } else { "" };
274 lhs.map(|lhs| space_if(needs_space_before_range(context, lhs)))
277 rhs.map(|rhs| space_if(needs_space_after_range(rhs)))
282 match (lhs.as_ref().map(|x| &**x), rhs.as_ref().map(|x| &**x)) {
283 (Some(lhs), Some(rhs)) => {
284 let sp_delim = if context.config.spaces_around_ranges() {
285 format!(" {} ", delim)
287 default_sp_delim(Some(lhs), Some(rhs))
292 PairParts::new("", &sp_delim, ""),
295 context.config.binop_separator(),
298 (None, Some(rhs)) => {
299 let sp_delim = if context.config.spaces_around_ranges() {
300 format!("{} ", delim)
302 default_sp_delim(None, Some(rhs))
304 rewrite_unary_prefix(context, &sp_delim, &*rhs, shape)
306 (Some(lhs), None) => {
307 let sp_delim = if context.config.spaces_around_ranges() {
308 format!(" {}", delim)
310 default_sp_delim(Some(lhs), None)
312 rewrite_unary_suffix(context, &sp_delim, &*lhs, shape)
314 (None, None) => Some(delim.to_owned()),
317 // We do not format these expressions yet, but they should still
318 // satisfy our width restrictions.
319 ast::ExprKind::InlineAsm(..) => Some(context.snippet(expr.span).to_owned()),
320 ast::ExprKind::Catch(ref block) => {
321 if let rw @ Some(_) =
322 rewrite_single_line_block(context, "do catch ", block, Some(&expr.attrs), shape)
327 let budget = shape.width.checked_sub(9).unwrap_or(0);
335 Shape::legacy(budget, shape.indent)
343 .and_then(|expr_str| recover_comment_removed(expr_str, expr.span, context))
344 .and_then(|expr_str| {
345 let attrs = outer_attributes(&expr.attrs);
346 let attrs_str = attrs.rewrite(context, shape)?;
348 attrs.last().map_or(expr.span.lo(), |attr| attr.span.hi()),
351 combine_strs_with_missing_comments(context, &attrs_str, &expr_str, span, shape, false)
355 #[derive(new, Clone, Copy)]
356 pub struct PairParts<'a> {
362 pub fn rewrite_pair<LHS, RHS>(
366 context: &RewriteContext,
368 separator_place: SeparatorPlace,
374 let lhs_overhead = match separator_place {
375 SeparatorPlace::Back => shape.used_width() + pp.prefix.len() + pp.infix.trim_right().len(),
376 SeparatorPlace::Front => shape.used_width(),
378 let lhs_shape = Shape {
379 width: context.budget(lhs_overhead),
382 let lhs_result = lhs.rewrite(context, lhs_shape)
383 .map(|lhs_str| format!("{}{}", pp.prefix, lhs_str))?;
385 // Try to put both lhs and rhs on the same line.
386 let rhs_orig_result = shape
387 .offset_left(last_line_width(&lhs_result) + pp.infix.len())
388 .and_then(|s| s.sub_width(pp.suffix.len()))
389 .and_then(|rhs_shape| rhs.rewrite(context, rhs_shape));
390 if let Some(ref rhs_result) = rhs_orig_result {
391 // If the length of the lhs is equal to or shorter than the tab width or
392 // the rhs looks like block expression, we put the rhs on the same
393 // line with the lhs even if the rhs is multi-lined.
394 let allow_same_line = lhs_result.len() <= context.config.tab_spaces()
398 .map(|first_line| first_line.ends_with('{'))
400 if !rhs_result.contains('\n') || allow_same_line {
401 let one_line_width = last_line_width(&lhs_result) + pp.infix.len()
402 + first_line_width(rhs_result) + pp.suffix.len();
403 if one_line_width <= shape.width {
406 lhs_result, pp.infix, rhs_result, pp.suffix
412 // We have to use multiple lines.
413 // Re-evaluate the rhs because we have more space now:
414 let mut rhs_shape = match context.config.indent_style() {
415 IndentStyle::Visual => shape
416 .sub_width(pp.suffix.len() + pp.prefix.len())?
417 .visual_indent(pp.prefix.len()),
418 IndentStyle::Block => {
419 // Try to calculate the initial constraint on the right hand side.
420 let rhs_overhead = shape.rhs_overhead(context.config);
421 Shape::indented(shape.indent.block_indent(context.config), context.config)
422 .sub_width(rhs_overhead)?
425 let infix = match separator_place {
426 SeparatorPlace::Back => pp.infix.trim_right(),
427 SeparatorPlace::Front => pp.infix.trim_left(),
429 if separator_place == SeparatorPlace::Front {
430 rhs_shape = rhs_shape.offset_left(infix.len())?;
432 let rhs_result = rhs.rewrite(context, rhs_shape)?;
433 let indent_str = rhs_shape.indent.to_string_with_newline(context.config);
434 let infix_with_sep = match separator_place {
435 SeparatorPlace::Back => format!("{}{}", infix, indent_str),
436 SeparatorPlace::Front => format!("{}{}", indent_str, infix),
440 lhs_result, infix_with_sep, rhs_result, pp.suffix
444 pub fn rewrite_array<T: Rewrite + Spanned + ToExpr>(
448 context: &RewriteContext,
450 force_separator_tactic: Option<SeparatorTactic>,
451 delim_token: Option<DelimToken>,
452 ) -> Option<String> {
453 overflow::rewrite_with_square_brackets(
459 force_separator_tactic,
464 fn rewrite_empty_block(
465 context: &RewriteContext,
467 attrs: Option<&[ast::Attribute]>,
470 ) -> Option<String> {
471 if attrs.map_or(false, |a| !inner_attributes(a).is_empty()) {
475 if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) && shape.width >= 2
477 return Some(format!("{}{{}}", prefix));
480 // If a block contains only a single-line comment, then leave it on one line.
481 let user_str = context.snippet(block.span);
482 let user_str = user_str.trim();
483 if user_str.starts_with('{') && user_str.ends_with('}') {
484 let comment_str = user_str[1..user_str.len() - 1].trim();
485 if block.stmts.is_empty() && !comment_str.contains('\n') && !comment_str.starts_with("//")
486 && comment_str.len() + 4 <= shape.width
488 return Some(format!("{}{{ {} }}", prefix, comment_str));
495 fn block_prefix(context: &RewriteContext, block: &ast::Block, shape: Shape) -> Option<String> {
496 Some(match block.rules {
497 ast::BlockCheckMode::Unsafe(..) => {
498 let snippet = context.snippet(block.span);
499 let open_pos = snippet.find_uncommented("{")?;
500 // Extract comment between unsafe and block start.
501 let trimmed = &snippet[6..open_pos].trim();
503 if !trimmed.is_empty() {
504 // 9 = "unsafe {".len(), 7 = "unsafe ".len()
505 let budget = shape.width.checked_sub(9)?;
511 Shape::legacy(budget, shape.indent + 7),
519 ast::BlockCheckMode::Default => String::new(),
523 fn rewrite_single_line_block(
524 context: &RewriteContext,
527 attrs: Option<&[ast::Attribute]>,
529 ) -> Option<String> {
530 if is_simple_block(block, attrs, context.codemap) {
531 let expr_shape = shape.offset_left(last_line_width(prefix))?;
532 let expr_str = block.stmts[0].rewrite(context, expr_shape)?;
533 let result = format!("{}{{ {} }}", prefix, expr_str);
534 if result.len() <= shape.width && !result.contains('\n') {
541 pub fn rewrite_block_with_visitor(
542 context: &RewriteContext,
545 attrs: Option<&[ast::Attribute]>,
548 ) -> Option<String> {
549 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, prefix, shape) {
553 let mut visitor = FmtVisitor::from_context(context);
554 visitor.block_indent = shape.indent;
555 visitor.is_if_else_block = context.is_if_else_block();
557 ast::BlockCheckMode::Unsafe(..) => {
558 let snippet = context.snippet(block.span);
559 let open_pos = snippet.find_uncommented("{")?;
560 visitor.last_pos = block.span.lo() + BytePos(open_pos as u32)
562 ast::BlockCheckMode::Default => visitor.last_pos = block.span.lo(),
565 let inner_attrs = attrs.map(inner_attributes);
566 visitor.visit_block(block, inner_attrs.as_ref().map(|a| &**a), has_braces);
567 Some(format!("{}{}", prefix, visitor.buffer))
570 impl Rewrite for ast::Block {
571 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
572 rewrite_block(self, None, context, shape)
578 attrs: Option<&[ast::Attribute]>,
579 context: &RewriteContext,
581 ) -> Option<String> {
582 let prefix = block_prefix(context, block, shape)?;
584 // shape.width is used only for the single line case: either the empty block `{}`,
585 // or an unsafe expression `unsafe { e }`.
586 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, &prefix, shape) {
590 let result = rewrite_block_with_visitor(context, &prefix, block, attrs, shape, true);
591 if let Some(ref result_str) = result {
592 if result_str.lines().count() <= 3 {
593 if let rw @ Some(_) = rewrite_single_line_block(context, &prefix, block, attrs, shape) {
602 impl Rewrite for ast::Stmt {
603 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
604 skip_out_of_file_lines_range!(context, self.span());
606 let result = match self.node {
607 ast::StmtKind::Local(ref local) => local.rewrite(context, shape),
608 ast::StmtKind::Expr(ref ex) | ast::StmtKind::Semi(ref ex) => {
609 let suffix = if semicolon_for_stmt(context, self) {
615 let shape = shape.sub_width(suffix.len())?;
616 format_expr(ex, ExprType::Statement, context, shape).map(|s| s + suffix)
618 ast::StmtKind::Mac(..) | ast::StmtKind::Item(..) => None,
620 result.and_then(|res| recover_comment_removed(res, self.span(), context))
624 // Rewrite condition if the given expression has one.
625 pub fn rewrite_cond(context: &RewriteContext, expr: &ast::Expr, shape: Shape) -> Option<String> {
627 ast::ExprKind::Match(ref cond, _) => {
629 let cond_shape = match context.config.indent_style() {
630 IndentStyle::Visual => shape.shrink_left(6).and_then(|s| s.sub_width(2))?,
631 IndentStyle::Block => shape.offset_left(8)?,
633 cond.rewrite(context, cond_shape)
635 _ => to_control_flow(expr, ExprType::SubExpression).and_then(|control_flow| {
637 String::from("\n") + &shape.indent.block_only().to_string(context.config);
639 .rewrite_cond(context, shape, &alt_block_sep)
640 .and_then(|rw| Some(rw.0))
645 // Abstraction over control flow expressions
647 struct ControlFlow<'a> {
648 cond: Option<&'a ast::Expr>,
649 block: &'a ast::Block,
650 else_block: Option<&'a ast::Expr>,
651 label: Option<ast::Label>,
652 pats: Vec<&'a ast::Pat>,
656 allow_single_line: bool,
657 // True if this is an `if` expression in an `else if` :-( hacky
662 fn to_control_flow(expr: &ast::Expr, expr_type: ExprType) -> Option<ControlFlow> {
664 ast::ExprKind::If(ref cond, ref if_block, ref else_block) => Some(ControlFlow::new_if(
668 else_block.as_ref().map(|e| &**e),
669 expr_type == ExprType::SubExpression,
673 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref else_block) => {
674 Some(ControlFlow::new_if(
676 ptr_vec_to_ref_vec(pat),
678 else_block.as_ref().map(|e| &**e),
679 expr_type == ExprType::SubExpression,
684 ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
685 Some(ControlFlow::new_for(pat, cond, block, label, expr.span))
687 ast::ExprKind::Loop(ref block, label) => {
688 Some(ControlFlow::new_loop(block, label, expr.span))
690 ast::ExprKind::While(ref cond, ref block, label) => Some(ControlFlow::new_while(
697 ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => Some(
698 ControlFlow::new_while(ptr_vec_to_ref_vec(pat), cond, block, label, expr.span),
704 fn choose_matcher(pats: &[&ast::Pat]) -> &'static str {
712 impl<'a> ControlFlow<'a> {
715 pats: Vec<&'a ast::Pat>,
716 block: &'a ast::Block,
717 else_block: Option<&'a ast::Expr>,
718 allow_single_line: bool,
721 ) -> ControlFlow<'a> {
722 let matcher = choose_matcher(&pats);
738 fn new_loop(block: &'a ast::Block, label: Option<ast::Label>, span: Span) -> ControlFlow<'a> {
748 allow_single_line: false,
755 pats: Vec<&'a ast::Pat>,
757 block: &'a ast::Block,
758 label: Option<ast::Label>,
760 ) -> ControlFlow<'a> {
761 let matcher = choose_matcher(&pats);
771 allow_single_line: false,
780 block: &'a ast::Block,
781 label: Option<ast::Label>,
783 ) -> ControlFlow<'a> {
793 allow_single_line: false,
799 fn rewrite_single_line(
802 context: &RewriteContext,
804 ) -> Option<String> {
805 assert!(self.allow_single_line);
806 let else_block = self.else_block?;
807 let fixed_cost = self.keyword.len() + " { } else { }".len();
809 if let ast::ExprKind::Block(ref else_node) = else_block.node {
810 if !is_simple_block(self.block, None, context.codemap)
811 || !is_simple_block(else_node, None, context.codemap)
812 || pat_expr_str.contains('\n')
817 let new_width = width.checked_sub(pat_expr_str.len() + fixed_cost)?;
818 let expr = &self.block.stmts[0];
819 let if_str = expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
821 let new_width = new_width.checked_sub(if_str.len())?;
822 let else_expr = &else_node.stmts[0];
823 let else_str = else_expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
825 if if_str.contains('\n') || else_str.contains('\n') {
829 let result = format!(
830 "{} {} {{ {} }} else {{ {} }}",
831 self.keyword, pat_expr_str, if_str, else_str
834 if result.len() <= width {
843 impl<'a> ControlFlow<'a> {
846 context: &RewriteContext,
850 ) -> Option<String> {
851 debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, self.pats, expr);
853 let cond_shape = shape.offset_left(offset)?;
854 if !self.pats.is_empty() {
855 let matcher = if self.matcher.is_empty() {
856 self.matcher.to_owned()
858 format!("{} ", self.matcher)
860 let pat_shape = cond_shape
861 .offset_left(matcher.len())?
862 .sub_width(self.connector.len())?;
863 let pat_string = rewrite_multiple_patterns(context, &self.pats, pat_shape)?;
864 let result = format!("{}{}{}", matcher, pat_string, self.connector);
865 return rewrite_assign_rhs(context, result, expr, cond_shape);
868 let expr_rw = expr.rewrite(context, cond_shape);
869 // The expression may (partially) fit on the current line.
870 // We do not allow splitting between `if` and condition.
871 if self.keyword == "if" || expr_rw.is_some() {
875 // The expression won't fit on the current line, jump to next.
876 let nested_shape = shape
877 .block_indent(context.config.tab_spaces())
878 .with_max_width(context.config);
879 let nested_indent_str = nested_shape.indent.to_string_with_newline(context.config);
880 expr.rewrite(context, nested_shape)
881 .map(|expr_rw| format!("{}{}", nested_indent_str, expr_rw))
886 context: &RewriteContext,
889 ) -> Option<(String, usize)> {
890 // Do not take the rhs overhead from the upper expressions into account
891 // when rewriting pattern.
892 let new_width = context.budget(shape.used_width());
893 let fresh_shape = Shape {
897 let constr_shape = if self.nested_if {
898 // We are part of an if-elseif-else chain. Our constraints are tightened.
899 // 7 = "} else " .len()
900 fresh_shape.offset_left(7)?
905 let label_string = rewrite_label(self.label);
906 // 1 = space after keyword.
907 let offset = self.keyword.len() + label_string.len() + 1;
909 let pat_expr_string = match self.cond {
910 Some(cond) => self.rewrite_pat_expr(context, cond, constr_shape, offset)?,
911 None => String::new(),
915 if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
921 let one_line_budget = context
924 .checked_sub(constr_shape.used_width() + offset + brace_overhead)
926 let force_newline_brace = (pat_expr_string.contains('\n')
927 || pat_expr_string.len() > one_line_budget)
928 && !last_line_extendable(&pat_expr_string);
930 // Try to format if-else on single line.
931 if self.allow_single_line
935 .single_line_if_else_max_width > 0
937 let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width);
939 if let Some(cond_str) = trial {
944 .single_line_if_else_max_width
946 return Some((cond_str, 0));
951 let cond_span = if let Some(cond) = self.cond {
954 mk_sp(self.block.span.lo(), self.block.span.lo())
957 // `for event in event`
958 // Do not include label in the span.
960 .map_or(self.span.lo(), |label| label.ident.span.hi());
961 let between_kwd_cond = mk_sp(
964 .span_after(mk_sp(lo, self.span.hi()), self.keyword.trim()),
965 if self.pats.is_empty() {
967 } else if self.matcher.is_empty() {
968 self.pats[0].span.lo()
972 .span_before(self.span, self.matcher.trim())
976 let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape);
978 let after_cond_comment =
979 extract_comment(mk_sp(cond_span.hi(), self.block.span.lo()), context, shape);
981 let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
983 } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine
984 || force_newline_brace
991 let used_width = if pat_expr_string.contains('\n') {
992 last_line_width(&pat_expr_string)
994 // 2 = spaces after keyword and condition.
995 label_string.len() + self.keyword.len() + pat_expr_string.len() + 2
1003 between_kwd_cond_comment.as_ref().map_or(
1004 if pat_expr_string.is_empty() || pat_expr_string.starts_with('\n') {
1012 after_cond_comment.as_ref().map_or(block_sep, |s| &**s)
1019 impl<'a> Rewrite for ControlFlow<'a> {
1020 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1021 debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
1023 let alt_block_sep = &shape.indent.to_string_with_newline(context.config);
1024 let (cond_str, used_width) = self.rewrite_cond(context, shape, alt_block_sep)?;
1025 // If `used_width` is 0, it indicates that whole control flow is written in a single line.
1026 if used_width == 0 {
1027 return Some(cond_str);
1030 let block_width = shape.width.checked_sub(used_width).unwrap_or(0);
1031 // This is used only for the empty block case: `{}`. So, we use 1 if we know
1032 // we should avoid the single line case.
1033 let block_width = if self.else_block.is_some() || self.nested_if {
1038 let block_shape = Shape {
1043 let old_val = context.is_if_else_block.replace(self.else_block.is_some());
1045 rewrite_block_with_visitor(context, "", self.block, None, block_shape, true);
1046 context.is_if_else_block.replace(old_val);
1050 let mut result = format!("{}{}", cond_str, block_str);
1052 if let Some(else_block) = self.else_block {
1053 let shape = Shape::indented(shape.indent, context.config);
1054 let mut last_in_chain = false;
1055 let rewrite = match else_block.node {
1056 // If the else expression is another if-else expression, prevent it
1057 // from being formatted on a single line.
1058 // Note how we're passing the original shape, as the
1059 // cost of "else" should not cascade.
1060 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref next_else_block) => {
1061 ControlFlow::new_if(
1063 ptr_vec_to_ref_vec(pat),
1065 next_else_block.as_ref().map(|e| &**e),
1068 mk_sp(else_block.span.lo(), self.span.hi()),
1069 ).rewrite(context, shape)
1071 ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => {
1072 ControlFlow::new_if(
1076 next_else_block.as_ref().map(|e| &**e),
1079 mk_sp(else_block.span.lo(), self.span.hi()),
1080 ).rewrite(context, shape)
1083 last_in_chain = true;
1084 // When rewriting a block, the width is only used for single line
1085 // blocks, passing 1 lets us avoid that.
1086 let else_shape = Shape {
1087 width: min(1, shape.width),
1090 format_expr(else_block, ExprType::Statement, context, else_shape)
1094 let between_kwd_else_block = mk_sp(
1095 self.block.span.hi(),
1098 .span_before(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1100 let between_kwd_else_block_comment =
1101 extract_comment(between_kwd_else_block, context, shape);
1103 let after_else = mk_sp(
1106 .span_after(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1107 else_block.span.lo(),
1109 let after_else_comment = extract_comment(after_else, context, shape);
1111 let between_sep = match context.config.control_brace_style() {
1112 ControlBraceStyle::AlwaysNextLine | ControlBraceStyle::ClosingNextLine => {
1115 ControlBraceStyle::AlwaysSameLine => " ",
1117 let after_sep = match context.config.control_brace_style() {
1118 ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep,
1122 result.push_str(&format!(
1124 between_kwd_else_block_comment
1126 .map_or(between_sep, |s| &**s),
1127 after_else_comment.as_ref().map_or(after_sep, |s| &**s),
1129 result.push_str(&rewrite?);
1136 fn rewrite_label(opt_label: Option<ast::Label>) -> Cow<'static, str> {
1138 Some(label) => Cow::from(format!("{}: ", label.ident)),
1139 None => Cow::from(""),
1143 fn extract_comment(span: Span, context: &RewriteContext, shape: Shape) -> Option<String> {
1144 match rewrite_missing_comment(span, shape, context) {
1145 Some(ref comment) if !comment.is_empty() => Some(format!(
1146 "{indent}{}{indent}",
1148 indent = shape.indent.to_string_with_newline(context.config)
1154 pub fn block_contains_comment(block: &ast::Block, codemap: &CodeMap) -> bool {
1155 let snippet = codemap.span_to_snippet(block.span).unwrap();
1156 contains_comment(&snippet)
1159 // Checks that a block contains no statements, an expression and no comments or
1161 // FIXME: incorrectly returns false when comment is contained completely within
1163 pub fn is_simple_block(
1165 attrs: Option<&[ast::Attribute]>,
1168 (block.stmts.len() == 1 && stmt_is_expr(&block.stmts[0])
1169 && !block_contains_comment(block, codemap) && attrs.map_or(true, |a| a.is_empty()))
1172 /// Checks whether a block contains at most one statement or expression, and no
1173 /// comments or attributes.
1174 pub fn is_simple_block_stmt(
1176 attrs: Option<&[ast::Attribute]>,
1179 block.stmts.len() <= 1 && !block_contains_comment(block, codemap)
1180 && attrs.map_or(true, |a| a.is_empty())
1183 /// Checks whether a block contains no statements, expressions, comments, or
1184 /// inner attributes.
1185 pub fn is_empty_block(
1187 attrs: Option<&[ast::Attribute]>,
1190 block.stmts.is_empty() && !block_contains_comment(block, codemap)
1191 && attrs.map_or(true, |a| inner_attributes(a).is_empty())
1194 pub fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
1196 ast::StmtKind::Expr(..) => true,
1201 pub fn is_unsafe_block(block: &ast::Block) -> bool {
1202 if let ast::BlockCheckMode::Unsafe(..) = block.rules {
1209 pub fn rewrite_multiple_patterns(
1210 context: &RewriteContext,
1213 ) -> Option<String> {
1214 let pat_strs = pats.iter()
1215 .map(|p| p.rewrite(context, shape))
1216 .collect::<Option<Vec<_>>>()?;
1218 let use_mixed_layout = pats.iter()
1219 .zip(pat_strs.iter())
1220 .all(|(pat, pat_str)| is_short_pattern(pat, pat_str));
1221 let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
1222 let tactic = if use_mixed_layout {
1223 DefinitiveListTactic::Mixed
1227 ListTactic::HorizontalVertical,
1228 Separator::VerticalBar,
1232 let fmt = ListFormatting {
1235 trailing_separator: SeparatorTactic::Never,
1236 separator_place: context.config.binop_separator(),
1238 ends_with_newline: false,
1239 preserve_newline: false,
1240 config: context.config,
1242 write_list(&items, &fmt)
1245 pub fn rewrite_literal(context: &RewriteContext, l: &ast::Lit, shape: Shape) -> Option<String> {
1247 ast::LitKind::Str(_, ast::StrStyle::Cooked) => rewrite_string_lit(context, l.span, shape),
1249 context.snippet(l.span).to_owned(),
1250 context.config.max_width(),
1256 fn rewrite_string_lit(context: &RewriteContext, span: Span, shape: Shape) -> Option<String> {
1257 let string_lit = context.snippet(span);
1259 if !context.config.format_strings() {
1264 .all(|line| line.ends_with('\\'))
1266 let new_indent = shape.visual_indent(1).indent;
1267 let indented_string_lit = String::from(
1273 new_indent.to_string(context.config),
1277 .collect::<Vec<_>>()
1281 return wrap_str(indented_string_lit, context.config.max_width(), shape);
1283 return wrap_str(string_lit.to_owned(), context.config.max_width(), shape);
1287 // Remove the quote characters.
1288 let str_lit = &string_lit[1..string_lit.len() - 1];
1292 &StringFormat::new(shape.visual_indent(0), context.config),
1297 /// In case special-case style is required, returns an offset from which we start horizontal layout.
1298 pub fn maybe_get_args_offset<T: ToExpr>(callee_str: &str, args: &[&T]) -> Option<(bool, usize)> {
1299 if let Some(&(_, num_args_before)) = SPECIAL_MACRO_WHITELIST
1301 .find(|&&(s, _)| s == callee_str)
1303 let all_simple = args.len() > num_args_before && is_every_expr_simple(args);
1305 Some((all_simple, num_args_before))
1311 /// A list of `format!`-like macros, that take a long format string and a list of arguments to
1314 /// Organized as a list of `(&str, usize)` tuples, giving the name of the macro and the number of
1315 /// arguments before the format string (none for `format!("format", ...)`, one for `assert!(result,
1316 /// "format", ...)`, two for `assert_eq!(left, right, "format", ...)`).
1317 const SPECIAL_MACRO_WHITELIST: &[(&str, usize)] = &[
1318 // format! like macros
1319 // From the Rust Standard Library.
1323 ("format_args!", 0),
1327 ("unreachable!", 0),
1328 // From the `log` crate.
1333 // write! like macros
1335 ("debug_assert!", 1),
1338 // assert_eq! like macros
1341 ("debug_assert_eq!", 2),
1342 ("debug_assert_ne!", 2),
1345 fn choose_separator_tactic(context: &RewriteContext, span: Span) -> Option<SeparatorTactic> {
1346 if context.inside_macro() {
1347 if span_ends_with_comma(context, span) {
1348 Some(SeparatorTactic::Always)
1350 Some(SeparatorTactic::Never)
1357 pub fn rewrite_call(
1358 context: &RewriteContext,
1360 args: &[ptr::P<ast::Expr>],
1363 ) -> Option<String> {
1364 overflow::rewrite_with_parens(
1367 &ptr_vec_to_ref_vec(args),
1370 context.config.width_heuristics().fn_call_width,
1371 choose_separator_tactic(context, span),
1375 fn is_simple_expr(expr: &ast::Expr) -> bool {
1377 ast::ExprKind::Lit(..) => true,
1378 ast::ExprKind::Path(ref qself, ref path) => qself.is_none() && path.segments.len() <= 1,
1379 ast::ExprKind::AddrOf(_, ref expr)
1380 | ast::ExprKind::Box(ref expr)
1381 | ast::ExprKind::Cast(ref expr, _)
1382 | ast::ExprKind::Field(ref expr, _)
1383 | ast::ExprKind::Try(ref expr)
1384 | ast::ExprKind::Unary(_, ref expr) => is_simple_expr(expr),
1385 ast::ExprKind::Index(ref lhs, ref rhs) | ast::ExprKind::Repeat(ref lhs, ref rhs) => {
1386 is_simple_expr(lhs) && is_simple_expr(rhs)
1392 pub fn is_every_expr_simple<T: ToExpr>(lists: &[&T]) -> bool {
1395 .all(|arg| arg.to_expr().map_or(false, is_simple_expr))
1398 pub fn can_be_overflowed_expr(context: &RewriteContext, expr: &ast::Expr, args_len: usize) -> bool {
1400 ast::ExprKind::Match(..) => {
1401 (context.use_block_indent() && args_len == 1)
1402 || (context.config.indent_style() == IndentStyle::Visual && args_len > 1)
1404 ast::ExprKind::If(..)
1405 | ast::ExprKind::IfLet(..)
1406 | ast::ExprKind::ForLoop(..)
1407 | ast::ExprKind::Loop(..)
1408 | ast::ExprKind::While(..)
1409 | ast::ExprKind::WhileLet(..) => {
1410 context.config.combine_control_expr() && context.use_block_indent() && args_len == 1
1412 ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => {
1413 context.use_block_indent()
1414 || context.config.indent_style() == IndentStyle::Visual && args_len > 1
1416 ast::ExprKind::Array(..)
1417 | ast::ExprKind::Call(..)
1418 | ast::ExprKind::Mac(..)
1419 | ast::ExprKind::MethodCall(..)
1420 | ast::ExprKind::Struct(..)
1421 | ast::ExprKind::Tup(..) => context.use_block_indent() && args_len == 1,
1422 ast::ExprKind::AddrOf(_, ref expr)
1423 | ast::ExprKind::Box(ref expr)
1424 | ast::ExprKind::Try(ref expr)
1425 | ast::ExprKind::Unary(_, ref expr)
1426 | ast::ExprKind::Cast(ref expr, _) => can_be_overflowed_expr(context, expr, args_len),
1431 pub fn is_nested_call(expr: &ast::Expr) -> bool {
1433 ast::ExprKind::Call(..) | ast::ExprKind::Mac(..) => true,
1434 ast::ExprKind::AddrOf(_, ref expr)
1435 | ast::ExprKind::Box(ref expr)
1436 | ast::ExprKind::Try(ref expr)
1437 | ast::ExprKind::Unary(_, ref expr)
1438 | ast::ExprKind::Cast(ref expr, _) => is_nested_call(expr),
1443 /// Return true if a function call or a method call represented by the given span ends with a
1444 /// trailing comma. This function is used when rewriting macro, as adding or removing a trailing
1445 /// comma from macro can potentially break the code.
1446 pub fn span_ends_with_comma(context: &RewriteContext, span: Span) -> bool {
1447 let mut result: bool = Default::default();
1448 let mut prev_char: char = Default::default();
1449 let closing_delimiters = &[')', '}', ']'];
1451 for (kind, c) in CharClasses::new(context.snippet(span).chars()) {
1453 _ if kind.is_comment() || c.is_whitespace() => continue,
1454 c if closing_delimiters.contains(&c) => {
1455 result &= !closing_delimiters.contains(&prev_char);
1457 ',' => result = true,
1458 _ => result = false,
1467 context: &RewriteContext,
1468 mut subexpr: &ast::Expr,
1471 ) -> Option<String> {
1472 debug!("rewrite_paren, shape: {:?}", shape);
1474 // Extract comments within parens.
1475 let mut pre_comment;
1476 let mut post_comment;
1477 let remove_nested_parens = context.config.remove_nested_parens();
1480 let pre_span = mk_sp(span.lo() + BytePos(1), subexpr.span.lo());
1481 let post_span = mk_sp(subexpr.span.hi(), span.hi() - BytePos(1));
1482 pre_comment = rewrite_missing_comment(pre_span, shape, context)?;
1483 post_comment = rewrite_missing_comment(post_span, shape, context)?;
1485 // Remove nested parens if there are no comments.
1486 if let ast::ExprKind::Paren(ref subsubexpr) = subexpr.node {
1487 if remove_nested_parens && pre_comment.is_empty() && post_comment.is_empty() {
1488 span = subexpr.span;
1489 subexpr = subsubexpr;
1497 let total_paren_overhead = paren_overhead(context);
1498 let paren_overhead = total_paren_overhead / 2;
1499 let sub_shape = shape
1500 .offset_left(paren_overhead)
1501 .and_then(|s| s.sub_width(paren_overhead))?;
1503 let paren_wrapper = |s: &str| {
1504 if context.config.spaces_within_parens_and_brackets() && !s.is_empty() {
1505 format!("( {}{}{} )", pre_comment, s, post_comment)
1507 format!("({}{}{})", pre_comment, s, post_comment)
1511 let subexpr_str = subexpr.rewrite(context, sub_shape)?;
1512 debug!("rewrite_paren, subexpr_str: `{:?}`", subexpr_str);
1514 if subexpr_str.contains('\n')
1515 || first_line_width(&subexpr_str) + total_paren_overhead <= shape.width
1517 Some(paren_wrapper(&subexpr_str))
1526 context: &RewriteContext,
1528 ) -> Option<String> {
1529 let expr_str = expr.rewrite(context, shape)?;
1531 let (lbr, rbr) = if context.config.spaces_within_parens_and_brackets() {
1537 let offset = last_line_width(&expr_str) + lbr.len();
1538 let rhs_overhead = shape.rhs_overhead(context.config);
1539 let index_shape = if expr_str.contains('\n') {
1540 Shape::legacy(context.config.max_width(), shape.indent)
1541 .offset_left(offset)
1542 .and_then(|shape| shape.sub_width(rbr.len() + rhs_overhead))
1544 shape.visual_indent(offset).sub_width(offset + rbr.len())
1546 let orig_index_rw = index_shape.and_then(|s| index.rewrite(context, s));
1548 // Return if index fits in a single line.
1549 match orig_index_rw {
1550 Some(ref index_str) if !index_str.contains('\n') => {
1551 return Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr));
1556 // Try putting index on the next line and see if it fits in a single line.
1557 let indent = shape.indent.block_indent(context.config);
1558 let index_shape = Shape::indented(indent, context.config).offset_left(lbr.len())?;
1559 let index_shape = index_shape.sub_width(rbr.len() + rhs_overhead)?;
1560 let new_index_rw = index.rewrite(context, index_shape);
1561 match (orig_index_rw, new_index_rw) {
1562 (_, Some(ref new_index_str)) if !new_index_str.contains('\n') => Some(format!(
1565 indent.to_string_with_newline(context.config),
1570 (None, Some(ref new_index_str)) => Some(format!(
1573 indent.to_string_with_newline(context.config),
1578 (Some(ref index_str), _) => Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr)),
1583 fn struct_lit_can_be_aligned(fields: &[ast::Field], base: &Option<&ast::Expr>) -> bool {
1588 fields.iter().all(|field| !field.is_shorthand)
1591 fn rewrite_struct_lit<'a>(
1592 context: &RewriteContext,
1594 fields: &'a [ast::Field],
1595 base: Option<&'a ast::Expr>,
1598 ) -> Option<String> {
1599 debug!("rewrite_struct_lit: shape {:?}", shape);
1601 enum StructLitField<'a> {
1602 Regular(&'a ast::Field),
1603 Base(&'a ast::Expr),
1607 let path_shape = shape.sub_width(2)?;
1608 let path_str = rewrite_path(context, PathContext::Expr, None, path, path_shape)?;
1610 if fields.is_empty() && base.is_none() {
1611 return Some(format!("{} {{}}", path_str));
1614 // Foo { a: Foo } - indent is +3, width is -5.
1615 let (h_shape, v_shape) = struct_lit_shape(shape, context, path_str.len() + 3, 2)?;
1617 let one_line_width = h_shape.map_or(0, |shape| shape.width);
1618 let body_lo = context.snippet_provider.span_after(span, "{");
1619 let fields_str = if struct_lit_can_be_aligned(fields, &base)
1620 && context.config.struct_field_align_threshold() > 0
1622 rewrite_with_alignment(
1626 mk_sp(body_lo, span.hi()),
1630 let field_iter = fields
1632 .map(StructLitField::Regular)
1633 .chain(base.into_iter().map(StructLitField::Base));
1635 let span_lo = |item: &StructLitField| match *item {
1636 StructLitField::Regular(field) => field.span().lo(),
1637 StructLitField::Base(expr) => {
1638 let last_field_hi = fields.last().map_or(span.lo(), |field| field.span.hi());
1639 let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo()));
1640 let pos = snippet.find_uncommented("..").unwrap();
1641 last_field_hi + BytePos(pos as u32)
1644 let span_hi = |item: &StructLitField| match *item {
1645 StructLitField::Regular(field) => field.span().hi(),
1646 StructLitField::Base(expr) => expr.span.hi(),
1648 let rewrite = |item: &StructLitField| match *item {
1649 StructLitField::Regular(field) => {
1650 // The 1 taken from the v_budget is for the comma.
1651 rewrite_field(context, field, v_shape.sub_width(1)?, 0)
1653 StructLitField::Base(expr) => {
1655 expr.rewrite(context, v_shape.offset_left(2)?)
1656 .map(|s| format!("..{}", s))
1660 let items = itemize_list(
1661 context.snippet_provider,
1672 let item_vec = items.collect::<Vec<_>>();
1674 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
1675 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
1677 let ends_with_comma = span_ends_with_comma(context, span);
1678 let force_no_trailing_comma = context.inside_macro() && !ends_with_comma;
1680 let fmt = struct_lit_formatting(
1684 force_no_trailing_comma || base.is_some(),
1687 write_list(&item_vec, &fmt)?
1690 let fields_str = wrap_struct_field(context, &fields_str, shape, v_shape, one_line_width);
1691 Some(format!("{} {{{}}}", path_str, fields_str))
1693 // FIXME if context.config.indent_style() == Visual, but we run out
1694 // of space, we should fall back to BlockIndent.
1697 pub fn wrap_struct_field(
1698 context: &RewriteContext,
1701 nested_shape: Shape,
1702 one_line_width: usize,
1704 if context.config.indent_style() == IndentStyle::Block
1705 && (fields_str.contains('\n') || !context.config.struct_lit_single_line()
1706 || fields_str.len() > one_line_width)
1710 nested_shape.indent.to_string_with_newline(context.config),
1712 shape.indent.to_string_with_newline(context.config)
1715 // One liner or visual indent.
1716 format!(" {} ", fields_str)
1720 pub fn struct_lit_field_separator(config: &Config) -> &str {
1721 colon_spaces(config.space_before_colon(), config.space_after_colon())
1724 pub fn rewrite_field(
1725 context: &RewriteContext,
1728 prefix_max_width: usize,
1729 ) -> Option<String> {
1730 if contains_skip(&field.attrs) {
1731 return Some(context.snippet(field.span()).to_owned());
1733 let mut attrs_str = field.attrs.rewrite(context, shape)?;
1734 if !attrs_str.is_empty() {
1735 attrs_str.push_str(&shape.indent.to_string_with_newline(context.config));
1737 let name = &field.ident.name.to_string();
1738 if field.is_shorthand {
1739 Some(attrs_str + &name)
1741 let mut separator = String::from(struct_lit_field_separator(context.config));
1742 for _ in 0..prefix_max_width.checked_sub(name.len()).unwrap_or(0) {
1743 separator.push(' ');
1745 let overhead = name.len() + separator.len();
1746 let expr_shape = shape.offset_left(overhead)?;
1747 let expr = field.expr.rewrite(context, expr_shape);
1750 Some(ref e) if e.as_str() == name && context.config.use_field_init_shorthand() => {
1751 Some(attrs_str + &name)
1753 Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)),
1755 let expr_offset = shape.indent.block_indent(context.config);
1758 .rewrite(context, Shape::indented(expr_offset, context.config));
1764 expr_offset.to_string(context.config),
1773 fn rewrite_tuple_in_visual_indent_style<'a, T>(
1774 context: &RewriteContext,
1780 T: Rewrite + Spanned + ToExpr + 'a,
1782 let mut items = items.iter();
1783 // In case of length 1, need a trailing comma
1784 debug!("rewrite_tuple_in_visual_indent_style {:?}", shape);
1785 if items.len() == 1 {
1787 let nested_shape = shape.sub_width(3)?.visual_indent(1);
1791 .rewrite(context, nested_shape)
1793 if context.config.spaces_within_parens_and_brackets() {
1794 format!("( {}, )", s)
1801 let list_lo = context.snippet_provider.span_after(span, "(");
1802 let nested_shape = shape.sub_width(2)?.visual_indent(1);
1803 let items = itemize_list(
1804 context.snippet_provider,
1808 |item| item.span().lo(),
1809 |item| item.span().hi(),
1810 |item| item.rewrite(context, nested_shape),
1812 span.hi() - BytePos(1),
1815 let item_vec: Vec<_> = items.collect();
1816 let tactic = definitive_tactic(
1818 ListTactic::HorizontalVertical,
1822 let fmt = ListFormatting {
1825 trailing_separator: SeparatorTactic::Never,
1826 separator_place: SeparatorPlace::Back,
1828 ends_with_newline: false,
1829 preserve_newline: false,
1830 config: context.config,
1832 let list_str = write_list(&item_vec, &fmt)?;
1834 if context.config.spaces_within_parens_and_brackets() && !list_str.is_empty() {
1835 Some(format!("( {} )", list_str))
1837 Some(format!("({})", list_str))
1841 pub fn rewrite_tuple<'a, T>(
1842 context: &RewriteContext,
1848 T: Rewrite + Spanned + ToExpr + 'a,
1850 debug!("rewrite_tuple {:?}", shape);
1851 if context.use_block_indent() {
1852 // We use the same rule as function calls for rewriting tuples.
1853 let force_tactic = if context.inside_macro() {
1854 if span_ends_with_comma(context, span) {
1855 Some(SeparatorTactic::Always)
1857 Some(SeparatorTactic::Never)
1859 } else if items.len() == 1 {
1860 Some(SeparatorTactic::Always)
1864 overflow::rewrite_with_parens(
1870 context.config.width_heuristics().fn_call_width,
1874 rewrite_tuple_in_visual_indent_style(context, items, span, shape)
1878 pub fn rewrite_unary_prefix<R: Rewrite>(
1879 context: &RewriteContext,
1883 ) -> Option<String> {
1885 .rewrite(context, shape.offset_left(prefix.len())?)
1886 .map(|r| format!("{}{}", prefix, r))
1889 // FIXME: this is probably not correct for multi-line Rewrites. we should
1890 // subtract suffix.len() from the last line budget, not the first!
1891 pub fn rewrite_unary_suffix<R: Rewrite>(
1892 context: &RewriteContext,
1896 ) -> Option<String> {
1898 .rewrite(context, shape.sub_width(suffix.len())?)
1905 fn rewrite_unary_op(
1906 context: &RewriteContext,
1910 ) -> Option<String> {
1911 // For some reason, an UnOp is not spanned like BinOp!
1912 let operator_str = match *op {
1913 ast::UnOp::Deref => "*",
1914 ast::UnOp::Not => "!",
1915 ast::UnOp::Neg => "-",
1917 rewrite_unary_prefix(context, operator_str, expr, shape)
1920 fn rewrite_assignment(
1921 context: &RewriteContext,
1924 op: Option<&ast::BinOp>,
1926 ) -> Option<String> {
1927 let operator_str = match op {
1928 Some(op) => context.snippet(op.span),
1932 // 1 = space between lhs and operator.
1933 let lhs_shape = shape.sub_width(operator_str.len() + 1)?;
1934 let lhs_str = format!("{} {}", lhs.rewrite(context, lhs_shape)?, operator_str);
1936 rewrite_assign_rhs(context, lhs_str, rhs, shape)
1939 /// Controls where to put the rhs.
1940 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
1941 pub enum RhsTactics {
1944 /// Put the rhs on the next line if it uses multiple line.
1948 // The left hand side must contain everything up to, and including, the
1949 // assignment operator.
1950 pub fn rewrite_assign_rhs<S: Into<String>, R: Rewrite>(
1951 context: &RewriteContext,
1955 ) -> Option<String> {
1956 rewrite_assign_rhs_with(context, lhs, ex, shape, RhsTactics::Default)
1959 pub fn rewrite_assign_rhs_with<S: Into<String>, R: Rewrite>(
1960 context: &RewriteContext,
1964 rhs_tactics: RhsTactics,
1965 ) -> Option<String> {
1966 let lhs = lhs.into();
1967 let last_line_width = last_line_width(&lhs)
1968 .checked_sub(if lhs.contains('\n') {
1969 shape.indent.width()
1974 // 1 = space between operator and rhs.
1975 let orig_shape = shape.offset_left(last_line_width + 1).unwrap_or(Shape {
1977 offset: shape.offset + last_line_width + 1,
1980 let rhs = choose_rhs(
1984 ex.rewrite(context, orig_shape),
1990 fn choose_rhs<R: Rewrite>(
1991 context: &RewriteContext,
1994 orig_rhs: Option<String>,
1995 rhs_tactics: RhsTactics,
1996 ) -> Option<String> {
1998 Some(ref new_str) if !new_str.contains('\n') && new_str.len() <= shape.width => {
1999 Some(format!(" {}", new_str))
2002 // Expression did not fit on the same line as the identifier.
2003 // Try splitting the line and see if that works better.
2005 Shape::indented(shape.indent.block_indent(context.config), context.config)
2006 .sub_width(shape.rhs_overhead(context.config))?;
2007 let new_rhs = expr.rewrite(context, new_shape);
2008 let new_indent_str = &new_shape.indent.to_string_with_newline(context.config);
2010 match (orig_rhs, new_rhs) {
2011 (Some(ref orig_rhs), Some(ref new_rhs))
2012 if wrap_str(new_rhs.clone(), context.config.max_width(), new_shape)
2015 Some(format!(" {}", orig_rhs))
2017 (Some(ref orig_rhs), Some(ref new_rhs))
2018 if prefer_next_line(orig_rhs, new_rhs, rhs_tactics) =>
2020 Some(format!("{}{}", new_indent_str, new_rhs))
2022 (None, Some(ref new_rhs)) => Some(format!("{}{}", new_indent_str, new_rhs)),
2023 (None, None) => None,
2024 (Some(ref orig_rhs), _) => Some(format!(" {}", orig_rhs)),
2030 pub fn prefer_next_line(orig_rhs: &str, next_line_rhs: &str, rhs_tactics: RhsTactics) -> bool {
2031 rhs_tactics == RhsTactics::ForceNextLine || !next_line_rhs.contains('\n')
2032 || count_newlines(orig_rhs) > count_newlines(next_line_rhs) + 1
2035 fn rewrite_expr_addrof(
2036 context: &RewriteContext,
2037 mutability: ast::Mutability,
2040 ) -> Option<String> {
2041 let operator_str = match mutability {
2042 ast::Mutability::Immutable => "&",
2043 ast::Mutability::Mutable => "&mut ",
2045 rewrite_unary_prefix(context, operator_str, expr, shape)
2049 fn to_expr(&self) -> Option<&ast::Expr>;
2050 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool;
2053 impl ToExpr for ast::Expr {
2054 fn to_expr(&self) -> Option<&ast::Expr> {
2058 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2059 can_be_overflowed_expr(context, self, len)
2063 impl ToExpr for ast::Ty {
2064 fn to_expr(&self) -> Option<&ast::Expr> {
2068 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2069 can_be_overflowed_type(context, self, len)
2073 impl<'a> ToExpr for TuplePatField<'a> {
2074 fn to_expr(&self) -> Option<&ast::Expr> {
2078 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2079 can_be_overflowed_pat(context, self, len)
2083 impl<'a> ToExpr for ast::StructField {
2084 fn to_expr(&self) -> Option<&ast::Expr> {
2088 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {
2093 impl<'a> ToExpr for MacroArg {
2094 fn to_expr(&self) -> Option<&ast::Expr> {
2096 MacroArg::Expr(ref expr) => Some(expr),
2101 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2103 MacroArg::Expr(ref expr) => can_be_overflowed_expr(context, expr, len),
2104 MacroArg::Ty(ref ty) => can_be_overflowed_type(context, ty, len),
2105 MacroArg::Pat(..) => false,
2106 MacroArg::Item(..) => len == 1,
2111 impl ToExpr for ast::GenericParam {
2112 fn to_expr(&self) -> Option<&ast::Expr> {
2116 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {