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, ptr_vec_to_ref_vec,
43 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(op, ref lhs, ref rhs) => {
90 // FIXME: format comments between operands and operator
91 rewrite_simple_binaries(context, expr, shape, op).or_else(|| {
95 PairParts::new("", &format!(" {} ", context.snippet(op.span)), ""),
98 context.config.binop_separator(),
102 ast::ExprKind::Unary(ref op, ref subexpr) => rewrite_unary_op(context, op, subexpr, shape),
103 ast::ExprKind::Struct(ref path, ref fields, ref base) => rewrite_struct_lit(
107 base.as_ref().map(|e| &**e),
111 ast::ExprKind::Tup(ref items) => {
112 rewrite_tuple(context, &ptr_vec_to_ref_vec(items), expr.span, shape)
114 ast::ExprKind::If(..)
115 | ast::ExprKind::IfLet(..)
116 | ast::ExprKind::ForLoop(..)
117 | ast::ExprKind::Loop(..)
118 | ast::ExprKind::While(..)
119 | ast::ExprKind::WhileLet(..) => to_control_flow(expr, expr_type)
120 .and_then(|control_flow| control_flow.rewrite(context, shape)),
121 ast::ExprKind::Block(ref block, opt_label) => {
123 ExprType::Statement => {
124 if is_unsafe_block(block) {
125 rewrite_block(block, Some(&expr.attrs), opt_label, context, shape)
126 } else if let rw @ Some(_) =
127 rewrite_empty_block(context, block, Some(&expr.attrs), "", shape)
129 // Rewrite block without trying to put it in a single line.
132 let prefix = block_prefix(context, block, shape)?;
134 rewrite_block_with_visitor(
144 ExprType::SubExpression => {
145 rewrite_block(block, Some(&expr.attrs), opt_label, context, shape)
149 ast::ExprKind::Match(ref cond, ref arms) => {
150 rewrite_match(context, cond, arms, shape, expr.span, &expr.attrs)
152 ast::ExprKind::Path(ref qself, ref path) => {
153 rewrite_path(context, PathContext::Expr, qself.as_ref(), path, shape)
155 ast::ExprKind::Assign(ref lhs, ref rhs) => {
156 rewrite_assignment(context, lhs, rhs, None, shape)
158 ast::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => {
159 rewrite_assignment(context, lhs, rhs, Some(op), shape)
161 ast::ExprKind::Continue(ref opt_label) => {
162 let id_str = match *opt_label {
163 Some(label) => format!(" {}", label.ident),
164 None => String::new(),
166 Some(format!("continue{}", id_str))
168 ast::ExprKind::Break(ref opt_label, ref opt_expr) => {
169 let id_str = match *opt_label {
170 Some(label) => format!(" {}", label.ident),
171 None => String::new(),
174 if let Some(ref expr) = *opt_expr {
175 rewrite_unary_prefix(context, &format!("break{} ", id_str), &**expr, shape)
177 Some(format!("break{}", id_str))
180 ast::ExprKind::Yield(ref opt_expr) => if let Some(ref expr) = *opt_expr {
181 rewrite_unary_prefix(context, "yield ", &**expr, shape)
183 Some("yield".to_string())
185 ast::ExprKind::Closure(capture, movability, ref fn_decl, ref body, _) => {
186 closures::rewrite_closure(
187 capture, movability, fn_decl, body, expr.span, context, shape,
190 ast::ExprKind::Try(..) | ast::ExprKind::Field(..) | ast::ExprKind::MethodCall(..) => {
191 rewrite_chain(expr, context, shape)
193 ast::ExprKind::Mac(ref mac) => {
194 rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| {
196 context.snippet(expr.span).to_owned(),
197 context.config.max_width(),
202 ast::ExprKind::Ret(None) => Some("return".to_owned()),
203 ast::ExprKind::Ret(Some(ref expr)) => {
204 rewrite_unary_prefix(context, "return ", &**expr, shape)
206 ast::ExprKind::Box(ref expr) => rewrite_unary_prefix(context, "box ", &**expr, shape),
207 ast::ExprKind::AddrOf(mutability, ref expr) => {
208 rewrite_expr_addrof(context, mutability, expr, shape)
210 ast::ExprKind::Cast(ref expr, ref ty) => rewrite_pair(
213 PairParts::new("", " as ", ""),
216 SeparatorPlace::Front,
218 ast::ExprKind::Type(ref expr, ref ty) => rewrite_pair(
221 PairParts::new("", ": ", ""),
224 SeparatorPlace::Back,
226 ast::ExprKind::Index(ref expr, ref index) => {
227 rewrite_index(&**expr, &**index, context, shape)
229 ast::ExprKind::Repeat(ref expr, ref repeats) => rewrite_pair(
232 PairParts::new("[", "; ", "]"),
235 SeparatorPlace::Back,
237 ast::ExprKind::Range(ref lhs, ref rhs, limits) => {
238 let delim = match limits {
239 ast::RangeLimits::HalfOpen => "..",
240 ast::RangeLimits::Closed => "..=",
243 fn needs_space_before_range(context: &RewriteContext, lhs: &ast::Expr) -> bool {
245 ast::ExprKind::Lit(ref lit) => match lit.node {
246 ast::LitKind::FloatUnsuffixed(..) => {
247 context.snippet(lit.span).ends_with('.')
255 fn needs_space_after_range(rhs: &ast::Expr) -> bool {
257 // Don't format `.. ..` into `....`, which is invalid.
259 // This check is unnecessary for `lhs`, because a range
260 // starting from another range needs parentheses as `(x ..) ..`
261 // (`x .. ..` is a range from `x` to `..`).
262 ast::ExprKind::Range(None, _, _) => true,
267 let default_sp_delim = |lhs: Option<&ast::Expr>, rhs: Option<&ast::Expr>| {
268 let space_if = |b: bool| if b { " " } else { "" };
272 lhs.map(|lhs| space_if(needs_space_before_range(context, lhs)))
275 rhs.map(|rhs| space_if(needs_space_after_range(rhs)))
280 match (lhs.as_ref().map(|x| &**x), rhs.as_ref().map(|x| &**x)) {
281 (Some(lhs), Some(rhs)) => {
282 let sp_delim = if context.config.spaces_around_ranges() {
283 format!(" {} ", delim)
285 default_sp_delim(Some(lhs), Some(rhs))
290 PairParts::new("", &sp_delim, ""),
293 context.config.binop_separator(),
296 (None, Some(rhs)) => {
297 let sp_delim = if context.config.spaces_around_ranges() {
298 format!("{} ", delim)
300 default_sp_delim(None, Some(rhs))
302 rewrite_unary_prefix(context, &sp_delim, &*rhs, shape)
304 (Some(lhs), None) => {
305 let sp_delim = if context.config.spaces_around_ranges() {
306 format!(" {}", delim)
308 default_sp_delim(Some(lhs), None)
310 rewrite_unary_suffix(context, &sp_delim, &*lhs, shape)
312 (None, None) => Some(delim.to_owned()),
315 // We do not format these expressions yet, but they should still
316 // satisfy our width restrictions.
317 ast::ExprKind::InlineAsm(..) => Some(context.snippet(expr.span).to_owned()),
318 ast::ExprKind::Catch(ref block) => {
319 if let rw @ Some(_) =
320 rewrite_single_line_block(context, "do catch ", block, Some(&expr.attrs), shape)
325 let budget = shape.width.saturating_sub(9);
334 Shape::legacy(budget, shape.indent)
342 .and_then(|expr_str| recover_comment_removed(expr_str, expr.span, context))
343 .and_then(|expr_str| {
344 let attrs = outer_attributes(&expr.attrs);
345 let attrs_str = attrs.rewrite(context, shape)?;
347 attrs.last().map_or(expr.span.lo(), |attr| attr.span.hi()),
350 combine_strs_with_missing_comments(context, &attrs_str, &expr_str, span, shape, false)
354 /// Collect operands that appears in the given binary operator in the opposite order.
355 /// e.g. `collect_binary_items(e, ||)` for `a && b || c || d` returns `[d, c, a && b]`.
356 fn collect_binary_items<'a>(mut expr: &'a ast::Expr, binop: ast::BinOp) -> Vec<&'a ast::Expr> {
357 let mut result = vec![];
358 let mut prev_lhs = None;
361 ast::ExprKind::Binary(inner_binop, ref lhs, ref rhs)
362 if inner_binop.node == binop.node =>
366 prev_lhs = Some(lhs);
369 if let Some(lhs) = prev_lhs {
379 /// Rewrites a binary expression whose operands fits within a single line.
380 fn rewrite_simple_binaries(
381 context: &RewriteContext,
385 ) -> Option<String> {
386 let op_str = context.snippet(op.span);
388 // 2 = spaces around a binary operator.
389 let sep_overhead = op_str.len() + 2;
390 let nested_overhead = sep_overhead - 1;
392 let nested_shape = (match context.config.indent_style() {
393 IndentStyle::Visual => shape.visual_indent(0),
394 IndentStyle::Block => shape.block_indent(context.config.tab_spaces()),
395 }).with_max_width(context.config);
396 let nested_shape = match context.config.binop_separator() {
397 SeparatorPlace::Back => nested_shape.sub_width(nested_overhead)?,
398 SeparatorPlace::Front => nested_shape.offset_left(nested_overhead)?,
401 let opt_rewrites: Option<Vec<_>> = collect_binary_items(expr, op)
404 .map(|e| e.rewrite(context, nested_shape))
406 if let Some(rewrites) = opt_rewrites {
407 if rewrites.iter().all(|e| ::utils::is_single_line(e)) {
408 let total_width = rewrites.iter().map(|s| s.len()).sum::<usize>()
409 + sep_overhead * (rewrites.len() - 1);
411 let sep_str = if total_width <= shape.width {
412 format!(" {} ", op_str)
414 let indent_str = nested_shape.indent.to_string_with_newline(context.config);
415 match context.config.binop_separator() {
416 SeparatorPlace::Back => format!(" {}{}", op_str.trim_right(), indent_str),
417 SeparatorPlace::Front => format!("{}{} ", indent_str, op_str.trim_left()),
421 return wrap_str(rewrites.join(&sep_str), context.config.max_width(), shape);
428 #[derive(new, Clone, Copy)]
429 pub struct PairParts<'a> {
435 pub fn rewrite_pair<LHS, RHS>(
439 context: &RewriteContext,
441 separator_place: SeparatorPlace,
447 let lhs_overhead = match separator_place {
448 SeparatorPlace::Back => shape.used_width() + pp.prefix.len() + pp.infix.trim_right().len(),
449 SeparatorPlace::Front => shape.used_width(),
451 let lhs_shape = Shape {
452 width: context.budget(lhs_overhead),
456 .rewrite(context, lhs_shape)
457 .map(|lhs_str| format!("{}{}", pp.prefix, lhs_str))?;
459 // Try to put both lhs and rhs on the same line.
460 let rhs_orig_result = shape
461 .offset_left(last_line_width(&lhs_result) + pp.infix.len())
462 .and_then(|s| s.sub_width(pp.suffix.len()))
463 .and_then(|rhs_shape| rhs.rewrite(context, rhs_shape));
464 if let Some(ref rhs_result) = rhs_orig_result {
465 // If the length of the lhs is equal to or shorter than the tab width or
466 // the rhs looks like block expression, we put the rhs on the same
467 // line with the lhs even if the rhs is multi-lined.
468 let allow_same_line = lhs_result.len() <= context.config.tab_spaces()
472 .map(|first_line| first_line.ends_with('{'))
474 if !rhs_result.contains('\n') || allow_same_line {
475 let one_line_width = last_line_width(&lhs_result)
477 + first_line_width(rhs_result)
479 if one_line_width <= shape.width {
482 lhs_result, pp.infix, rhs_result, pp.suffix
488 // We have to use multiple lines.
489 // Re-evaluate the rhs because we have more space now:
490 let mut rhs_shape = match context.config.indent_style() {
491 IndentStyle::Visual => shape
492 .sub_width(pp.suffix.len() + pp.prefix.len())?
493 .visual_indent(pp.prefix.len()),
494 IndentStyle::Block => {
495 // Try to calculate the initial constraint on the right hand side.
496 let rhs_overhead = shape.rhs_overhead(context.config);
497 Shape::indented(shape.indent.block_indent(context.config), context.config)
498 .sub_width(rhs_overhead)?
501 let infix = match separator_place {
502 SeparatorPlace::Back => pp.infix.trim_right(),
503 SeparatorPlace::Front => pp.infix.trim_left(),
505 if separator_place == SeparatorPlace::Front {
506 rhs_shape = rhs_shape.offset_left(infix.len())?;
508 let rhs_result = rhs.rewrite(context, rhs_shape)?;
509 let indent_str = rhs_shape.indent.to_string_with_newline(context.config);
510 let infix_with_sep = match separator_place {
511 SeparatorPlace::Back => format!("{}{}", infix, indent_str),
512 SeparatorPlace::Front => format!("{}{}", indent_str, infix),
516 lhs_result, infix_with_sep, rhs_result, pp.suffix
520 pub fn rewrite_array<T: Rewrite + Spanned + ToExpr>(
524 context: &RewriteContext,
526 force_separator_tactic: Option<SeparatorTactic>,
527 delim_token: Option<DelimToken>,
528 ) -> Option<String> {
529 overflow::rewrite_with_square_brackets(
535 force_separator_tactic,
540 fn rewrite_empty_block(
541 context: &RewriteContext,
543 attrs: Option<&[ast::Attribute]>,
546 ) -> Option<String> {
547 if attrs.map_or(false, |a| !inner_attributes(a).is_empty()) {
551 if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) && shape.width >= 2
553 return Some(format!("{}{{}}", prefix));
556 // If a block contains only a single-line comment, then leave it on one line.
557 let user_str = context.snippet(block.span);
558 let user_str = user_str.trim();
559 if user_str.starts_with('{') && user_str.ends_with('}') {
560 let comment_str = user_str[1..user_str.len() - 1].trim();
561 if block.stmts.is_empty()
562 && !comment_str.contains('\n')
563 && !comment_str.starts_with("//")
564 && comment_str.len() + 4 <= shape.width
566 return Some(format!("{}{{ {} }}", prefix, comment_str));
573 fn block_prefix(context: &RewriteContext, block: &ast::Block, shape: Shape) -> Option<String> {
574 Some(match block.rules {
575 ast::BlockCheckMode::Unsafe(..) => {
576 let snippet = context.snippet(block.span);
577 let open_pos = snippet.find_uncommented("{")?;
578 // Extract comment between unsafe and block start.
579 let trimmed = &snippet[6..open_pos].trim();
581 if !trimmed.is_empty() {
582 // 9 = "unsafe {".len(), 7 = "unsafe ".len()
583 let budget = shape.width.checked_sub(9)?;
589 Shape::legacy(budget, shape.indent + 7),
597 ast::BlockCheckMode::Default => String::new(),
601 fn rewrite_single_line_block(
602 context: &RewriteContext,
605 attrs: Option<&[ast::Attribute]>,
607 ) -> Option<String> {
608 if is_simple_block(block, attrs, context.codemap) {
609 let expr_shape = shape.offset_left(last_line_width(prefix))?;
610 let expr_str = block.stmts[0].rewrite(context, expr_shape)?;
611 let result = format!("{}{{ {} }}", prefix, expr_str);
612 if result.len() <= shape.width && !result.contains('\n') {
619 pub fn rewrite_block_with_visitor(
620 context: &RewriteContext,
623 attrs: Option<&[ast::Attribute]>,
626 ) -> Option<String> {
627 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, prefix, shape) {
631 let mut visitor = FmtVisitor::from_context(context);
632 visitor.block_indent = shape.indent;
633 visitor.is_if_else_block = context.is_if_else_block();
635 ast::BlockCheckMode::Unsafe(..) => {
636 let snippet = context.snippet(block.span);
637 let open_pos = snippet.find_uncommented("{")?;
638 visitor.last_pos = block.span.lo() + BytePos(open_pos as u32)
640 ast::BlockCheckMode::Default => visitor.last_pos = block.span.lo(),
643 let inner_attrs = attrs.map(inner_attributes);
644 visitor.visit_block(block, inner_attrs.as_ref().map(|a| &**a), has_braces);
645 Some(format!("{}{}", prefix, visitor.buffer))
648 impl Rewrite for ast::Block {
649 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
650 rewrite_block(self, None, None, context, shape)
656 attrs: Option<&[ast::Attribute]>,
657 label: Option<ast::Label>,
658 context: &RewriteContext,
660 ) -> Option<String> {
661 let unsafe_string = block_prefix(context, block, shape)?;
662 let label_string = rewrite_label(label);
663 let prefix = format!("{}{}", unsafe_string, label_string);
665 // shape.width is used only for the single line case: either the empty block `{}`,
666 // or an unsafe expression `unsafe { e }`.
667 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, &prefix, shape) {
671 let result = rewrite_block_with_visitor(context, &prefix, block, attrs, shape, true);
672 if let Some(ref result_str) = result {
673 if result_str.lines().count() <= 3 {
674 if let rw @ Some(_) = rewrite_single_line_block(context, &prefix, block, attrs, shape) {
683 impl Rewrite for ast::Stmt {
684 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
685 skip_out_of_file_lines_range!(context, self.span());
687 let result = match self.node {
688 ast::StmtKind::Local(ref local) => local.rewrite(context, shape),
689 ast::StmtKind::Expr(ref ex) | ast::StmtKind::Semi(ref ex) => {
690 let suffix = if semicolon_for_stmt(context, self) {
696 let shape = shape.sub_width(suffix.len())?;
697 format_expr(ex, ExprType::Statement, context, shape).map(|s| s + suffix)
699 ast::StmtKind::Mac(..) | ast::StmtKind::Item(..) => None,
701 result.and_then(|res| recover_comment_removed(res, self.span(), context))
705 // Rewrite condition if the given expression has one.
706 pub fn rewrite_cond(context: &RewriteContext, expr: &ast::Expr, shape: Shape) -> Option<String> {
708 ast::ExprKind::Match(ref cond, _) => {
710 let cond_shape = match context.config.indent_style() {
711 IndentStyle::Visual => shape.shrink_left(6).and_then(|s| s.sub_width(2))?,
712 IndentStyle::Block => shape.offset_left(8)?,
714 cond.rewrite(context, cond_shape)
716 _ => to_control_flow(expr, ExprType::SubExpression).and_then(|control_flow| {
718 String::from("\n") + &shape.indent.block_only().to_string(context.config);
720 .rewrite_cond(context, shape, &alt_block_sep)
721 .and_then(|rw| Some(rw.0))
726 // Abstraction over control flow expressions
728 struct ControlFlow<'a> {
729 cond: Option<&'a ast::Expr>,
730 block: &'a ast::Block,
731 else_block: Option<&'a ast::Expr>,
732 label: Option<ast::Label>,
733 pats: Vec<&'a ast::Pat>,
737 allow_single_line: bool,
738 // True if this is an `if` expression in an `else if` :-( hacky
743 fn to_control_flow(expr: &ast::Expr, expr_type: ExprType) -> Option<ControlFlow> {
745 ast::ExprKind::If(ref cond, ref if_block, ref else_block) => Some(ControlFlow::new_if(
749 else_block.as_ref().map(|e| &**e),
750 expr_type == ExprType::SubExpression,
754 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref else_block) => {
755 Some(ControlFlow::new_if(
757 ptr_vec_to_ref_vec(pat),
759 else_block.as_ref().map(|e| &**e),
760 expr_type == ExprType::SubExpression,
765 ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
766 Some(ControlFlow::new_for(pat, cond, block, label, expr.span))
768 ast::ExprKind::Loop(ref block, label) => {
769 Some(ControlFlow::new_loop(block, label, expr.span))
771 ast::ExprKind::While(ref cond, ref block, label) => Some(ControlFlow::new_while(
778 ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => Some(
779 ControlFlow::new_while(ptr_vec_to_ref_vec(pat), cond, block, label, expr.span),
785 fn choose_matcher(pats: &[&ast::Pat]) -> &'static str {
793 impl<'a> ControlFlow<'a> {
796 pats: Vec<&'a ast::Pat>,
797 block: &'a ast::Block,
798 else_block: Option<&'a ast::Expr>,
799 allow_single_line: bool,
802 ) -> ControlFlow<'a> {
803 let matcher = choose_matcher(&pats);
819 fn new_loop(block: &'a ast::Block, label: Option<ast::Label>, span: Span) -> ControlFlow<'a> {
829 allow_single_line: false,
836 pats: Vec<&'a ast::Pat>,
838 block: &'a ast::Block,
839 label: Option<ast::Label>,
841 ) -> ControlFlow<'a> {
842 let matcher = choose_matcher(&pats);
852 allow_single_line: false,
861 block: &'a ast::Block,
862 label: Option<ast::Label>,
864 ) -> ControlFlow<'a> {
874 allow_single_line: false,
880 fn rewrite_single_line(
883 context: &RewriteContext,
885 ) -> Option<String> {
886 assert!(self.allow_single_line);
887 let else_block = self.else_block?;
888 let fixed_cost = self.keyword.len() + " { } else { }".len();
890 if let ast::ExprKind::Block(ref else_node, _) = else_block.node {
891 if !is_simple_block(self.block, None, context.codemap)
892 || !is_simple_block(else_node, None, context.codemap)
893 || pat_expr_str.contains('\n')
898 let new_width = width.checked_sub(pat_expr_str.len() + fixed_cost)?;
899 let expr = &self.block.stmts[0];
900 let if_str = expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
902 let new_width = new_width.checked_sub(if_str.len())?;
903 let else_expr = &else_node.stmts[0];
904 let else_str = else_expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
906 if if_str.contains('\n') || else_str.contains('\n') {
910 let result = format!(
911 "{} {} {{ {} }} else {{ {} }}",
912 self.keyword, pat_expr_str, if_str, else_str
915 if result.len() <= width {
924 impl<'a> ControlFlow<'a> {
927 context: &RewriteContext,
931 ) -> Option<String> {
932 debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, self.pats, expr);
934 let cond_shape = shape.offset_left(offset)?;
935 if !self.pats.is_empty() {
936 let matcher = if self.matcher.is_empty() {
937 self.matcher.to_owned()
939 format!("{} ", self.matcher)
941 let pat_shape = cond_shape
942 .offset_left(matcher.len())?
943 .sub_width(self.connector.len())?;
944 let pat_string = rewrite_multiple_patterns(context, &self.pats, pat_shape)?;
945 let result = format!("{}{}{}", matcher, pat_string, self.connector);
946 return rewrite_assign_rhs(context, result, expr, cond_shape);
949 let expr_rw = expr.rewrite(context, cond_shape);
950 // The expression may (partially) fit on the current line.
951 // We do not allow splitting between `if` and condition.
952 if self.keyword == "if" || expr_rw.is_some() {
956 // The expression won't fit on the current line, jump to next.
957 let nested_shape = shape
958 .block_indent(context.config.tab_spaces())
959 .with_max_width(context.config);
960 let nested_indent_str = nested_shape.indent.to_string_with_newline(context.config);
961 expr.rewrite(context, nested_shape)
962 .map(|expr_rw| format!("{}{}", nested_indent_str, expr_rw))
967 context: &RewriteContext,
970 ) -> Option<(String, usize)> {
971 // Do not take the rhs overhead from the upper expressions into account
972 // when rewriting pattern.
973 let new_width = context.budget(shape.used_width());
974 let fresh_shape = Shape {
978 let constr_shape = if self.nested_if {
979 // We are part of an if-elseif-else chain. Our constraints are tightened.
980 // 7 = "} else " .len()
981 fresh_shape.offset_left(7)?
986 let label_string = rewrite_label(self.label);
987 // 1 = space after keyword.
988 let offset = self.keyword.len() + label_string.len() + 1;
990 let pat_expr_string = match self.cond {
991 Some(cond) => self.rewrite_pat_expr(context, cond, constr_shape, offset)?,
992 None => String::new(),
996 if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
1002 let one_line_budget = context
1005 .saturating_sub(constr_shape.used_width() + offset + brace_overhead);
1006 let force_newline_brace = (pat_expr_string.contains('\n')
1007 || pat_expr_string.len() > one_line_budget)
1008 && !last_line_extendable(&pat_expr_string);
1010 // Try to format if-else on single line.
1011 if self.allow_single_line
1015 .single_line_if_else_max_width > 0
1017 let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width);
1019 if let Some(cond_str) = trial {
1024 .single_line_if_else_max_width
1026 return Some((cond_str, 0));
1031 let cond_span = if let Some(cond) = self.cond {
1034 mk_sp(self.block.span.lo(), self.block.span.lo())
1037 // `for event in event`
1038 // Do not include label in the span.
1041 .map_or(self.span.lo(), |label| label.ident.span.hi());
1042 let between_kwd_cond = mk_sp(
1045 .span_after(mk_sp(lo, self.span.hi()), self.keyword.trim()),
1046 if self.pats.is_empty() {
1048 } else if self.matcher.is_empty() {
1049 self.pats[0].span.lo()
1053 .span_before(self.span, self.matcher.trim())
1057 let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape);
1059 let after_cond_comment =
1060 extract_comment(mk_sp(cond_span.hi(), self.block.span.lo()), context, shape);
1062 let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
1064 } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine
1065 || force_newline_brace
1072 let used_width = if pat_expr_string.contains('\n') {
1073 last_line_width(&pat_expr_string)
1075 // 2 = spaces after keyword and condition.
1076 label_string.len() + self.keyword.len() + pat_expr_string.len() + 2
1084 between_kwd_cond_comment.as_ref().map_or(
1085 if pat_expr_string.is_empty() || pat_expr_string.starts_with('\n') {
1093 after_cond_comment.as_ref().map_or(block_sep, |s| &**s)
1100 impl<'a> Rewrite for ControlFlow<'a> {
1101 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1102 debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
1104 let alt_block_sep = &shape.indent.to_string_with_newline(context.config);
1105 let (cond_str, used_width) = self.rewrite_cond(context, shape, alt_block_sep)?;
1106 // If `used_width` is 0, it indicates that whole control flow is written in a single line.
1107 if used_width == 0 {
1108 return Some(cond_str);
1111 let block_width = shape.width.saturating_sub(used_width);
1112 // This is used only for the empty block case: `{}`. So, we use 1 if we know
1113 // we should avoid the single line case.
1114 let block_width = if self.else_block.is_some() || self.nested_if {
1119 let block_shape = Shape {
1124 let old_val = context.is_if_else_block.replace(self.else_block.is_some());
1126 rewrite_block_with_visitor(context, "", self.block, None, block_shape, true);
1127 context.is_if_else_block.replace(old_val);
1131 let mut result = format!("{}{}", cond_str, block_str);
1133 if let Some(else_block) = self.else_block {
1134 let shape = Shape::indented(shape.indent, context.config);
1135 let mut last_in_chain = false;
1136 let rewrite = match else_block.node {
1137 // If the else expression is another if-else expression, prevent it
1138 // from being formatted on a single line.
1139 // Note how we're passing the original shape, as the
1140 // cost of "else" should not cascade.
1141 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref next_else_block) => {
1142 ControlFlow::new_if(
1144 ptr_vec_to_ref_vec(pat),
1146 next_else_block.as_ref().map(|e| &**e),
1149 mk_sp(else_block.span.lo(), self.span.hi()),
1150 ).rewrite(context, shape)
1152 ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => {
1153 ControlFlow::new_if(
1157 next_else_block.as_ref().map(|e| &**e),
1160 mk_sp(else_block.span.lo(), self.span.hi()),
1161 ).rewrite(context, shape)
1164 last_in_chain = true;
1165 // When rewriting a block, the width is only used for single line
1166 // blocks, passing 1 lets us avoid that.
1167 let else_shape = Shape {
1168 width: min(1, shape.width),
1171 format_expr(else_block, ExprType::Statement, context, else_shape)
1175 let between_kwd_else_block = mk_sp(
1176 self.block.span.hi(),
1179 .span_before(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1181 let between_kwd_else_block_comment =
1182 extract_comment(between_kwd_else_block, context, shape);
1184 let after_else = mk_sp(
1187 .span_after(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1188 else_block.span.lo(),
1190 let after_else_comment = extract_comment(after_else, context, shape);
1192 let between_sep = match context.config.control_brace_style() {
1193 ControlBraceStyle::AlwaysNextLine | ControlBraceStyle::ClosingNextLine => {
1196 ControlBraceStyle::AlwaysSameLine => " ",
1198 let after_sep = match context.config.control_brace_style() {
1199 ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep,
1203 result.push_str(&format!(
1205 between_kwd_else_block_comment
1207 .map_or(between_sep, |s| &**s),
1208 after_else_comment.as_ref().map_or(after_sep, |s| &**s),
1210 result.push_str(&rewrite?);
1217 fn rewrite_label(opt_label: Option<ast::Label>) -> Cow<'static, str> {
1219 Some(label) => Cow::from(format!("{}: ", label.ident)),
1220 None => Cow::from(""),
1224 fn extract_comment(span: Span, context: &RewriteContext, shape: Shape) -> Option<String> {
1225 match rewrite_missing_comment(span, shape, context) {
1226 Some(ref comment) if !comment.is_empty() => Some(format!(
1227 "{indent}{}{indent}",
1229 indent = shape.indent.to_string_with_newline(context.config)
1235 pub fn block_contains_comment(block: &ast::Block, codemap: &CodeMap) -> bool {
1236 let snippet = codemap.span_to_snippet(block.span).unwrap();
1237 contains_comment(&snippet)
1240 // Checks that a block contains no statements, an expression and no comments or
1242 // FIXME: incorrectly returns false when comment is contained completely within
1244 pub fn is_simple_block(
1246 attrs: Option<&[ast::Attribute]>,
1249 (block.stmts.len() == 1
1250 && stmt_is_expr(&block.stmts[0])
1251 && !block_contains_comment(block, codemap)
1252 && attrs.map_or(true, |a| a.is_empty()))
1255 /// Checks whether a block contains at most one statement or expression, and no
1256 /// comments or attributes.
1257 pub fn is_simple_block_stmt(
1259 attrs: Option<&[ast::Attribute]>,
1262 block.stmts.len() <= 1
1263 && !block_contains_comment(block, codemap)
1264 && attrs.map_or(true, |a| a.is_empty())
1267 /// Checks whether a block contains no statements, expressions, comments, or
1268 /// inner attributes.
1269 pub fn is_empty_block(
1271 attrs: Option<&[ast::Attribute]>,
1274 block.stmts.is_empty()
1275 && !block_contains_comment(block, codemap)
1276 && attrs.map_or(true, |a| inner_attributes(a).is_empty())
1279 pub fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
1281 ast::StmtKind::Expr(..) => true,
1286 pub fn is_unsafe_block(block: &ast::Block) -> bool {
1287 if let ast::BlockCheckMode::Unsafe(..) = block.rules {
1294 pub fn rewrite_multiple_patterns(
1295 context: &RewriteContext,
1298 ) -> Option<String> {
1301 .map(|p| p.rewrite(context, shape))
1302 .collect::<Option<Vec<_>>>()?;
1304 let use_mixed_layout = pats
1306 .zip(pat_strs.iter())
1307 .all(|(pat, pat_str)| is_short_pattern(pat, pat_str));
1308 let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
1309 let tactic = if use_mixed_layout {
1310 DefinitiveListTactic::Mixed
1314 ListTactic::HorizontalVertical,
1315 Separator::VerticalBar,
1319 let fmt = ListFormatting {
1322 trailing_separator: SeparatorTactic::Never,
1323 separator_place: context.config.binop_separator(),
1325 ends_with_newline: false,
1326 preserve_newline: false,
1327 config: context.config,
1329 write_list(&items, &fmt)
1332 pub fn rewrite_literal(context: &RewriteContext, l: &ast::Lit, shape: Shape) -> Option<String> {
1334 ast::LitKind::Str(_, ast::StrStyle::Cooked) => rewrite_string_lit(context, l.span, shape),
1336 context.snippet(l.span).to_owned(),
1337 context.config.max_width(),
1343 fn rewrite_string_lit(context: &RewriteContext, span: Span, shape: Shape) -> Option<String> {
1344 let string_lit = context.snippet(span);
1346 if !context.config.format_strings() {
1351 .all(|line| line.ends_with('\\'))
1353 let new_indent = shape.visual_indent(1).indent;
1354 let indented_string_lit = String::from(
1360 new_indent.to_string(context.config),
1364 .collect::<Vec<_>>()
1368 return wrap_str(indented_string_lit, context.config.max_width(), shape);
1370 return wrap_str(string_lit.to_owned(), context.config.max_width(), shape);
1374 // Remove the quote characters.
1375 let str_lit = &string_lit[1..string_lit.len() - 1];
1379 &StringFormat::new(shape.visual_indent(0), context.config),
1384 /// In case special-case style is required, returns an offset from which we start horizontal layout.
1385 pub fn maybe_get_args_offset<T: ToExpr>(callee_str: &str, args: &[&T]) -> Option<(bool, usize)> {
1386 if let Some(&(_, num_args_before)) = SPECIAL_MACRO_WHITELIST
1388 .find(|&&(s, _)| s == callee_str)
1390 let all_simple = args.len() > num_args_before && is_every_expr_simple(args);
1392 Some((all_simple, num_args_before))
1398 /// A list of `format!`-like macros, that take a long format string and a list of arguments to
1401 /// Organized as a list of `(&str, usize)` tuples, giving the name of the macro and the number of
1402 /// arguments before the format string (none for `format!("format", ...)`, one for `assert!(result,
1403 /// "format", ...)`, two for `assert_eq!(left, right, "format", ...)`).
1404 const SPECIAL_MACRO_WHITELIST: &[(&str, usize)] = &[
1405 // format! like macros
1406 // From the Rust Standard Library.
1410 ("format_args!", 0),
1414 ("unreachable!", 0),
1415 // From the `log` crate.
1420 // write! like macros
1422 ("debug_assert!", 1),
1425 // assert_eq! like macros
1428 ("debug_assert_eq!", 2),
1429 ("debug_assert_ne!", 2),
1432 fn choose_separator_tactic(context: &RewriteContext, span: Span) -> Option<SeparatorTactic> {
1433 if context.inside_macro() {
1434 if span_ends_with_comma(context, span) {
1435 Some(SeparatorTactic::Always)
1437 Some(SeparatorTactic::Never)
1444 pub fn rewrite_call(
1445 context: &RewriteContext,
1447 args: &[ptr::P<ast::Expr>],
1450 ) -> Option<String> {
1451 overflow::rewrite_with_parens(
1454 &ptr_vec_to_ref_vec(args),
1457 context.config.width_heuristics().fn_call_width,
1458 choose_separator_tactic(context, span),
1462 fn is_simple_expr(expr: &ast::Expr) -> bool {
1464 ast::ExprKind::Lit(..) => true,
1465 ast::ExprKind::Path(ref qself, ref path) => qself.is_none() && path.segments.len() <= 1,
1466 ast::ExprKind::AddrOf(_, ref expr)
1467 | ast::ExprKind::Box(ref expr)
1468 | ast::ExprKind::Cast(ref expr, _)
1469 | ast::ExprKind::Field(ref expr, _)
1470 | ast::ExprKind::Try(ref expr)
1471 | ast::ExprKind::Unary(_, ref expr) => is_simple_expr(expr),
1472 ast::ExprKind::Index(ref lhs, ref rhs) | ast::ExprKind::Repeat(ref lhs, ref rhs) => {
1473 is_simple_expr(lhs) && is_simple_expr(rhs)
1479 pub fn is_every_expr_simple<T: ToExpr>(lists: &[&T]) -> bool {
1482 .all(|arg| arg.to_expr().map_or(false, is_simple_expr))
1485 pub fn can_be_overflowed_expr(context: &RewriteContext, expr: &ast::Expr, args_len: usize) -> bool {
1487 ast::ExprKind::Match(..) => {
1488 (context.use_block_indent() && args_len == 1)
1489 || (context.config.indent_style() == IndentStyle::Visual && args_len > 1)
1491 ast::ExprKind::If(..)
1492 | ast::ExprKind::IfLet(..)
1493 | ast::ExprKind::ForLoop(..)
1494 | ast::ExprKind::Loop(..)
1495 | ast::ExprKind::While(..)
1496 | ast::ExprKind::WhileLet(..) => {
1497 context.config.combine_control_expr() && context.use_block_indent() && args_len == 1
1499 ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => {
1500 context.use_block_indent()
1501 || context.config.indent_style() == IndentStyle::Visual && args_len > 1
1503 ast::ExprKind::Array(..)
1504 | ast::ExprKind::Call(..)
1505 | ast::ExprKind::Mac(..)
1506 | ast::ExprKind::MethodCall(..)
1507 | ast::ExprKind::Struct(..)
1508 | ast::ExprKind::Tup(..) => context.use_block_indent() && args_len == 1,
1509 ast::ExprKind::AddrOf(_, ref expr)
1510 | ast::ExprKind::Box(ref expr)
1511 | ast::ExprKind::Try(ref expr)
1512 | ast::ExprKind::Unary(_, ref expr)
1513 | ast::ExprKind::Cast(ref expr, _) => can_be_overflowed_expr(context, expr, args_len),
1518 pub fn is_nested_call(expr: &ast::Expr) -> bool {
1520 ast::ExprKind::Call(..) | ast::ExprKind::Mac(..) => true,
1521 ast::ExprKind::AddrOf(_, ref expr)
1522 | ast::ExprKind::Box(ref expr)
1523 | ast::ExprKind::Try(ref expr)
1524 | ast::ExprKind::Unary(_, ref expr)
1525 | ast::ExprKind::Cast(ref expr, _) => is_nested_call(expr),
1530 /// Return true if a function call or a method call represented by the given span ends with a
1531 /// trailing comma. This function is used when rewriting macro, as adding or removing a trailing
1532 /// comma from macro can potentially break the code.
1533 pub fn span_ends_with_comma(context: &RewriteContext, span: Span) -> bool {
1534 let mut result: bool = Default::default();
1535 let mut prev_char: char = Default::default();
1536 let closing_delimiters = &[')', '}', ']'];
1538 for (kind, c) in CharClasses::new(context.snippet(span).chars()) {
1540 _ if kind.is_comment() || c.is_whitespace() => continue,
1541 c if closing_delimiters.contains(&c) => {
1542 result &= !closing_delimiters.contains(&prev_char);
1544 ',' => result = true,
1545 _ => result = false,
1554 context: &RewriteContext,
1555 mut subexpr: &ast::Expr,
1558 ) -> Option<String> {
1559 debug!("rewrite_paren, shape: {:?}", shape);
1561 // Extract comments within parens.
1562 let mut pre_comment;
1563 let mut post_comment;
1564 let remove_nested_parens = context.config.remove_nested_parens();
1567 let pre_span = mk_sp(span.lo() + BytePos(1), subexpr.span.lo());
1568 let post_span = mk_sp(subexpr.span.hi(), span.hi() - BytePos(1));
1569 pre_comment = rewrite_missing_comment(pre_span, shape, context)?;
1570 post_comment = rewrite_missing_comment(post_span, shape, context)?;
1572 // Remove nested parens if there are no comments.
1573 if let ast::ExprKind::Paren(ref subsubexpr) = subexpr.node {
1574 if remove_nested_parens && pre_comment.is_empty() && post_comment.is_empty() {
1575 span = subexpr.span;
1576 subexpr = subsubexpr;
1585 let sub_shape = shape.offset_left(1).and_then(|s| s.sub_width(1))?;
1587 let subexpr_str = subexpr.rewrite(context, sub_shape)?;
1588 debug!("rewrite_paren, subexpr_str: `{:?}`", subexpr_str);
1591 if subexpr_str.contains('\n') || first_line_width(&subexpr_str) + 2 <= shape.width {
1592 Some(format!("({}{}{})", pre_comment, &subexpr_str, post_comment))
1601 context: &RewriteContext,
1603 ) -> Option<String> {
1604 let expr_str = expr.rewrite(context, shape)?;
1606 let offset = last_line_width(&expr_str) + 1;
1607 let rhs_overhead = shape.rhs_overhead(context.config);
1608 let index_shape = if expr_str.contains('\n') {
1609 Shape::legacy(context.config.max_width(), shape.indent)
1610 .offset_left(offset)
1611 .and_then(|shape| shape.sub_width(1 + rhs_overhead))
1613 shape.visual_indent(offset).sub_width(offset + 1)
1615 let orig_index_rw = index_shape.and_then(|s| index.rewrite(context, s));
1617 // Return if index fits in a single line.
1618 match orig_index_rw {
1619 Some(ref index_str) if !index_str.contains('\n') => {
1620 return Some(format!("{}[{}]", expr_str, index_str));
1625 // Try putting index on the next line and see if it fits in a single line.
1626 let indent = shape.indent.block_indent(context.config);
1627 let index_shape = Shape::indented(indent, context.config).offset_left(1)?;
1628 let index_shape = index_shape.sub_width(1 + rhs_overhead)?;
1629 let new_index_rw = index.rewrite(context, index_shape);
1630 match (orig_index_rw, new_index_rw) {
1631 (_, Some(ref new_index_str)) if !new_index_str.contains('\n') => Some(format!(
1634 indent.to_string_with_newline(context.config),
1637 (None, Some(ref new_index_str)) => Some(format!(
1640 indent.to_string_with_newline(context.config),
1643 (Some(ref index_str), _) => Some(format!("{}[{}]", expr_str, index_str)),
1648 fn struct_lit_can_be_aligned(fields: &[ast::Field], base: &Option<&ast::Expr>) -> bool {
1653 fields.iter().all(|field| !field.is_shorthand)
1656 fn rewrite_struct_lit<'a>(
1657 context: &RewriteContext,
1659 fields: &'a [ast::Field],
1660 base: Option<&'a ast::Expr>,
1663 ) -> Option<String> {
1664 debug!("rewrite_struct_lit: shape {:?}", shape);
1666 enum StructLitField<'a> {
1667 Regular(&'a ast::Field),
1668 Base(&'a ast::Expr),
1672 let path_shape = shape.sub_width(2)?;
1673 let path_str = rewrite_path(context, PathContext::Expr, None, path, path_shape)?;
1675 if fields.is_empty() && base.is_none() {
1676 return Some(format!("{} {{}}", path_str));
1679 // Foo { a: Foo } - indent is +3, width is -5.
1680 let (h_shape, v_shape) = struct_lit_shape(shape, context, path_str.len() + 3, 2)?;
1682 let one_line_width = h_shape.map_or(0, |shape| shape.width);
1683 let body_lo = context.snippet_provider.span_after(span, "{");
1684 let fields_str = if struct_lit_can_be_aligned(fields, &base)
1685 && context.config.struct_field_align_threshold() > 0
1687 rewrite_with_alignment(
1691 mk_sp(body_lo, span.hi()),
1695 let field_iter = fields
1697 .map(StructLitField::Regular)
1698 .chain(base.into_iter().map(StructLitField::Base));
1700 let span_lo = |item: &StructLitField| match *item {
1701 StructLitField::Regular(field) => field.span().lo(),
1702 StructLitField::Base(expr) => {
1703 let last_field_hi = fields.last().map_or(span.lo(), |field| field.span.hi());
1704 let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo()));
1705 let pos = snippet.find_uncommented("..").unwrap();
1706 last_field_hi + BytePos(pos as u32)
1709 let span_hi = |item: &StructLitField| match *item {
1710 StructLitField::Regular(field) => field.span().hi(),
1711 StructLitField::Base(expr) => expr.span.hi(),
1713 let rewrite = |item: &StructLitField| match *item {
1714 StructLitField::Regular(field) => {
1715 // The 1 taken from the v_budget is for the comma.
1716 rewrite_field(context, field, v_shape.sub_width(1)?, 0)
1718 StructLitField::Base(expr) => {
1720 expr.rewrite(context, v_shape.offset_left(2)?)
1721 .map(|s| format!("..{}", s))
1725 let items = itemize_list(
1726 context.snippet_provider,
1737 let item_vec = items.collect::<Vec<_>>();
1739 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
1740 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
1742 let ends_with_comma = span_ends_with_comma(context, span);
1743 let force_no_trailing_comma = context.inside_macro() && !ends_with_comma;
1745 let fmt = struct_lit_formatting(
1749 force_no_trailing_comma || base.is_some(),
1752 write_list(&item_vec, &fmt)?
1755 let fields_str = wrap_struct_field(context, &fields_str, shape, v_shape, one_line_width);
1756 Some(format!("{} {{{}}}", path_str, fields_str))
1758 // FIXME if context.config.indent_style() == Visual, but we run out
1759 // of space, we should fall back to BlockIndent.
1762 pub fn wrap_struct_field(
1763 context: &RewriteContext,
1766 nested_shape: Shape,
1767 one_line_width: usize,
1769 if context.config.indent_style() == IndentStyle::Block
1770 && (fields_str.contains('\n')
1771 || !context.config.struct_lit_single_line()
1772 || fields_str.len() > one_line_width)
1776 nested_shape.indent.to_string_with_newline(context.config),
1778 shape.indent.to_string_with_newline(context.config)
1781 // One liner or visual indent.
1782 format!(" {} ", fields_str)
1786 pub fn struct_lit_field_separator(config: &Config) -> &str {
1787 colon_spaces(config.space_before_colon(), config.space_after_colon())
1790 pub fn rewrite_field(
1791 context: &RewriteContext,
1794 prefix_max_width: usize,
1795 ) -> Option<String> {
1796 if contains_skip(&field.attrs) {
1797 return Some(context.snippet(field.span()).to_owned());
1799 let mut attrs_str = field.attrs.rewrite(context, shape)?;
1800 if !attrs_str.is_empty() {
1801 attrs_str.push_str(&shape.indent.to_string_with_newline(context.config));
1803 let name = &field.ident.name.to_string();
1804 if field.is_shorthand {
1805 Some(attrs_str + &name)
1807 let mut separator = String::from(struct_lit_field_separator(context.config));
1808 for _ in 0..prefix_max_width.saturating_sub(name.len()) {
1809 separator.push(' ');
1811 let overhead = name.len() + separator.len();
1812 let expr_shape = shape.offset_left(overhead)?;
1813 let expr = field.expr.rewrite(context, expr_shape);
1816 Some(ref e) if e.as_str() == name && context.config.use_field_init_shorthand() => {
1817 Some(attrs_str + &name)
1819 Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)),
1821 let expr_offset = shape.indent.block_indent(context.config);
1824 .rewrite(context, Shape::indented(expr_offset, context.config));
1830 expr_offset.to_string(context.config),
1839 fn rewrite_tuple_in_visual_indent_style<'a, T>(
1840 context: &RewriteContext,
1846 T: Rewrite + Spanned + ToExpr + 'a,
1848 let mut items = items.iter();
1849 // In case of length 1, need a trailing comma
1850 debug!("rewrite_tuple_in_visual_indent_style {:?}", shape);
1851 if items.len() == 1 {
1853 let nested_shape = shape.sub_width(3)?.visual_indent(1);
1857 .rewrite(context, nested_shape)
1858 .map(|s| format!("({},)", s));
1861 let list_lo = context.snippet_provider.span_after(span, "(");
1862 let nested_shape = shape.sub_width(2)?.visual_indent(1);
1863 let items = itemize_list(
1864 context.snippet_provider,
1868 |item| item.span().lo(),
1869 |item| item.span().hi(),
1870 |item| item.rewrite(context, nested_shape),
1872 span.hi() - BytePos(1),
1875 let item_vec: Vec<_> = items.collect();
1876 let tactic = definitive_tactic(
1878 ListTactic::HorizontalVertical,
1882 let fmt = ListFormatting {
1885 trailing_separator: SeparatorTactic::Never,
1886 separator_place: SeparatorPlace::Back,
1888 ends_with_newline: false,
1889 preserve_newline: false,
1890 config: context.config,
1892 let list_str = write_list(&item_vec, &fmt)?;
1894 Some(format!("({})", list_str))
1897 pub fn rewrite_tuple<'a, T>(
1898 context: &RewriteContext,
1904 T: Rewrite + Spanned + ToExpr + 'a,
1906 debug!("rewrite_tuple {:?}", shape);
1907 if context.use_block_indent() {
1908 // We use the same rule as function calls for rewriting tuples.
1909 let force_tactic = if context.inside_macro() {
1910 if span_ends_with_comma(context, span) {
1911 Some(SeparatorTactic::Always)
1913 Some(SeparatorTactic::Never)
1915 } else if items.len() == 1 {
1916 Some(SeparatorTactic::Always)
1920 overflow::rewrite_with_parens(
1926 context.config.width_heuristics().fn_call_width,
1930 rewrite_tuple_in_visual_indent_style(context, items, span, shape)
1934 pub fn rewrite_unary_prefix<R: Rewrite>(
1935 context: &RewriteContext,
1939 ) -> Option<String> {
1941 .rewrite(context, shape.offset_left(prefix.len())?)
1942 .map(|r| format!("{}{}", prefix, r))
1945 // FIXME: this is probably not correct for multi-line Rewrites. we should
1946 // subtract suffix.len() from the last line budget, not the first!
1947 pub fn rewrite_unary_suffix<R: Rewrite>(
1948 context: &RewriteContext,
1952 ) -> Option<String> {
1954 .rewrite(context, shape.sub_width(suffix.len())?)
1961 fn rewrite_unary_op(
1962 context: &RewriteContext,
1966 ) -> Option<String> {
1967 // For some reason, an UnOp is not spanned like BinOp!
1968 let operator_str = match *op {
1969 ast::UnOp::Deref => "*",
1970 ast::UnOp::Not => "!",
1971 ast::UnOp::Neg => "-",
1973 rewrite_unary_prefix(context, operator_str, expr, shape)
1976 fn rewrite_assignment(
1977 context: &RewriteContext,
1980 op: Option<&ast::BinOp>,
1982 ) -> Option<String> {
1983 let operator_str = match op {
1984 Some(op) => context.snippet(op.span),
1988 // 1 = space between lhs and operator.
1989 let lhs_shape = shape.sub_width(operator_str.len() + 1)?;
1990 let lhs_str = format!("{} {}", lhs.rewrite(context, lhs_shape)?, operator_str);
1992 rewrite_assign_rhs(context, lhs_str, rhs, shape)
1995 /// Controls where to put the rhs.
1996 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
1997 pub enum RhsTactics {
2000 /// Put the rhs on the next line if it uses multiple line.
2004 // The left hand side must contain everything up to, and including, the
2005 // assignment operator.
2006 pub fn rewrite_assign_rhs<S: Into<String>, R: Rewrite>(
2007 context: &RewriteContext,
2011 ) -> Option<String> {
2012 rewrite_assign_rhs_with(context, lhs, ex, shape, RhsTactics::Default)
2015 pub fn rewrite_assign_rhs_with<S: Into<String>, R: Rewrite>(
2016 context: &RewriteContext,
2020 rhs_tactics: RhsTactics,
2021 ) -> Option<String> {
2022 let lhs = lhs.into();
2023 let last_line_width = last_line_width(&lhs).saturating_sub(if lhs.contains('\n') {
2024 shape.indent.width()
2028 // 1 = space between operator and rhs.
2029 let orig_shape = shape.offset_left(last_line_width + 1).unwrap_or(Shape {
2031 offset: shape.offset + last_line_width + 1,
2034 let rhs = choose_rhs(
2038 ex.rewrite(context, orig_shape),
2044 fn choose_rhs<R: Rewrite>(
2045 context: &RewriteContext,
2048 orig_rhs: Option<String>,
2049 rhs_tactics: RhsTactics,
2050 ) -> Option<String> {
2052 Some(ref new_str) if !new_str.contains('\n') && new_str.len() <= shape.width => {
2053 Some(format!(" {}", new_str))
2056 // Expression did not fit on the same line as the identifier.
2057 // Try splitting the line and see if that works better.
2059 Shape::indented(shape.indent.block_indent(context.config), context.config)
2060 .sub_width(shape.rhs_overhead(context.config))?;
2061 let new_rhs = expr.rewrite(context, new_shape);
2062 let new_indent_str = &new_shape.indent.to_string_with_newline(context.config);
2064 match (orig_rhs, new_rhs) {
2065 (Some(ref orig_rhs), Some(ref new_rhs))
2066 if wrap_str(new_rhs.clone(), context.config.max_width(), new_shape)
2069 Some(format!(" {}", orig_rhs))
2071 (Some(ref orig_rhs), Some(ref new_rhs))
2072 if prefer_next_line(orig_rhs, new_rhs, rhs_tactics) =>
2074 Some(format!("{}{}", new_indent_str, new_rhs))
2076 (None, Some(ref new_rhs)) => Some(format!("{}{}", new_indent_str, new_rhs)),
2077 (None, None) => None,
2078 (Some(ref orig_rhs), _) => Some(format!(" {}", orig_rhs)),
2084 pub fn prefer_next_line(orig_rhs: &str, next_line_rhs: &str, rhs_tactics: RhsTactics) -> bool {
2085 rhs_tactics == RhsTactics::ForceNextLine
2086 || !next_line_rhs.contains('\n')
2087 || count_newlines(orig_rhs) > count_newlines(next_line_rhs) + 1
2090 fn rewrite_expr_addrof(
2091 context: &RewriteContext,
2092 mutability: ast::Mutability,
2095 ) -> Option<String> {
2096 let operator_str = match mutability {
2097 ast::Mutability::Immutable => "&",
2098 ast::Mutability::Mutable => "&mut ",
2100 rewrite_unary_prefix(context, operator_str, expr, shape)
2104 fn to_expr(&self) -> Option<&ast::Expr>;
2105 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool;
2108 impl ToExpr for ast::Expr {
2109 fn to_expr(&self) -> Option<&ast::Expr> {
2113 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2114 can_be_overflowed_expr(context, self, len)
2118 impl ToExpr for ast::Ty {
2119 fn to_expr(&self) -> Option<&ast::Expr> {
2123 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2124 can_be_overflowed_type(context, self, len)
2128 impl<'a> ToExpr for TuplePatField<'a> {
2129 fn to_expr(&self) -> Option<&ast::Expr> {
2133 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2134 can_be_overflowed_pat(context, self, len)
2138 impl<'a> ToExpr for ast::StructField {
2139 fn to_expr(&self) -> Option<&ast::Expr> {
2143 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {
2148 impl<'a> ToExpr for MacroArg {
2149 fn to_expr(&self) -> Option<&ast::Expr> {
2151 MacroArg::Expr(ref expr) => Some(expr),
2156 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2158 MacroArg::Expr(ref expr) => can_be_overflowed_expr(context, expr, len),
2159 MacroArg::Ty(ref ty) => can_be_overflowed_type(context, ty, len),
2160 MacroArg::Pat(..) => false,
2161 MacroArg::Item(..) => len == 1,
2166 impl ToExpr for ast::GenericParam {
2167 fn to_expr(&self) -> Option<&ast::Expr> {
2171 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {
2176 pub fn is_method_call(expr: &ast::Expr) -> bool {
2178 ast::ExprKind::MethodCall(..) => true,
2179 ast::ExprKind::AddrOf(_, ref expr)
2180 | ast::ExprKind::Box(ref expr)
2181 | ast::ExprKind::Cast(ref expr, _)
2182 | ast::ExprKind::Try(ref expr)
2183 | ast::ExprKind::Unary(_, ref expr) => is_method_call(expr),