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::parse::token::DelimToken;
16 use syntax::source_map::{BytePos, SourceMap, Span};
17 use syntax::{ast, ptr};
19 use chains::rewrite_chain;
22 combine_strs_with_missing_comments, contains_comment, recover_comment_removed, rewrite_comment,
23 rewrite_missing_comment, CharClasses, FindUncommented,
25 use config::{Config, ControlBraceStyle, IndentStyle};
27 definitive_tactic, itemize_list, shape_for_tactic, struct_lit_formatting, struct_lit_shape,
28 struct_lit_tactic, write_list, ListFormatting, ListItem, Separator,
30 use macros::{rewrite_macro, MacroPosition};
31 use matches::rewrite_match;
32 use overflow::{self, IntoOverflowableItem, OverflowableItem};
33 use pairs::{rewrite_all_pairs, rewrite_pair, PairParts};
34 use patterns::is_short_pattern;
35 use rewrite::{Rewrite, RewriteContext};
36 use shape::{Indent, Shape};
37 use source_map::{LineRangeUtils, SpanUtils};
39 use string::{rewrite_string, StringFormat};
40 use types::{rewrite_path, PathContext};
42 colon_spaces, contains_skip, count_newlines, first_line_ends_with, inner_attributes,
43 last_line_extendable, last_line_width, mk_sp, outer_attributes, ptr_vec_to_ref_vec,
44 semicolon_for_stmt, wrap_str,
46 use vertical::rewrite_with_alignment;
47 use visitor::FmtVisitor;
49 impl Rewrite for ast::Expr {
50 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
51 format_expr(self, ExprType::SubExpression, context, shape)
55 #[derive(Copy, Clone, PartialEq)]
64 context: &RewriteContext,
67 skip_out_of_file_lines_range!(context, expr.span);
69 if contains_skip(&*expr.attrs) {
70 return Some(context.snippet(expr.span()).to_owned());
73 let expr_rw = match expr.node {
74 ast::ExprKind::Array(ref expr_vec) => rewrite_array(
80 choose_separator_tactic(context, expr.span),
83 ast::ExprKind::Lit(ref l) => rewrite_literal(context, l, shape),
84 ast::ExprKind::Call(ref callee, ref args) => {
85 let inner_span = mk_sp(callee.span.hi(), expr.span.hi());
86 let callee_str = callee.rewrite(context, shape)?;
87 rewrite_call(context, &callee_str, args, inner_span, shape)
89 ast::ExprKind::Paren(ref subexpr) => rewrite_paren(context, subexpr, shape, expr.span),
90 ast::ExprKind::Binary(op, ref lhs, ref rhs) => {
91 // FIXME: format comments between operands and operator
92 rewrite_all_pairs(expr, shape, context).or_else(|| {
96 PairParts::infix(&format!(" {} ", context.snippet(op.span))),
99 context.config.binop_separator(),
103 ast::ExprKind::Unary(op, ref subexpr) => rewrite_unary_op(context, op, subexpr, shape),
104 ast::ExprKind::Struct(ref path, ref fields, ref base) => rewrite_struct_lit(
108 base.as_ref().map(|e| &**e),
112 ast::ExprKind::Tup(ref items) => {
113 rewrite_tuple(context, items.iter(), expr.span, shape, items.len() == 1)
115 ast::ExprKind::If(..)
116 | ast::ExprKind::IfLet(..)
117 | ast::ExprKind::ForLoop(..)
118 | ast::ExprKind::Loop(..)
119 | ast::ExprKind::While(..)
120 | ast::ExprKind::WhileLet(..) => to_control_flow(expr, expr_type)
121 .and_then(|control_flow| control_flow.rewrite(context, shape)),
122 ast::ExprKind::Block(ref block, opt_label) => {
124 ExprType::Statement => {
125 if is_unsafe_block(block) {
126 rewrite_block(block, Some(&expr.attrs), opt_label, context, shape)
127 } else if let rw @ Some(_) =
128 rewrite_empty_block(context, block, Some(&expr.attrs), opt_label, "", shape)
130 // Rewrite block without trying to put it in a single line.
133 let prefix = block_prefix(context, block, shape)?;
135 rewrite_block_with_visitor(
146 ExprType::SubExpression => {
147 rewrite_block(block, Some(&expr.attrs), opt_label, context, shape)
151 ast::ExprKind::Match(ref cond, ref arms) => {
152 rewrite_match(context, cond, arms, shape, expr.span, &expr.attrs)
154 ast::ExprKind::Path(ref qself, ref path) => {
155 rewrite_path(context, PathContext::Expr, qself.as_ref(), path, shape)
157 ast::ExprKind::Assign(ref lhs, ref rhs) => {
158 rewrite_assignment(context, lhs, rhs, None, shape)
160 ast::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => {
161 rewrite_assignment(context, lhs, rhs, Some(op), shape)
163 ast::ExprKind::Continue(ref opt_label) => {
164 let id_str = match *opt_label {
165 Some(label) => format!(" {}", label.ident),
166 None => String::new(),
168 Some(format!("continue{}", id_str))
170 ast::ExprKind::Break(ref opt_label, ref opt_expr) => {
171 let id_str = match *opt_label {
172 Some(label) => format!(" {}", label.ident),
173 None => String::new(),
176 if let Some(ref expr) = *opt_expr {
177 rewrite_unary_prefix(context, &format!("break{} ", id_str), &**expr, shape)
179 Some(format!("break{}", id_str))
182 ast::ExprKind::Yield(ref opt_expr) => {
183 if let Some(ref expr) = *opt_expr {
184 rewrite_unary_prefix(context, "yield ", &**expr, shape)
186 Some("yield".to_string())
189 ast::ExprKind::Closure(capture, asyncness, movability, ref fn_decl, ref body, _) => {
190 closures::rewrite_closure(
191 capture, asyncness, movability, fn_decl, body, expr.span, context, shape,
194 ast::ExprKind::Try(..) | ast::ExprKind::Field(..) | ast::ExprKind::MethodCall(..) => {
195 rewrite_chain(expr, context, shape)
197 ast::ExprKind::Mac(ref mac) => {
198 rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| {
200 context.snippet(expr.span).to_owned(),
201 context.config.max_width(),
206 ast::ExprKind::Ret(None) => Some("return".to_owned()),
207 ast::ExprKind::Ret(Some(ref expr)) => {
208 rewrite_unary_prefix(context, "return ", &**expr, shape)
210 ast::ExprKind::Box(ref expr) => rewrite_unary_prefix(context, "box ", &**expr, shape),
211 ast::ExprKind::AddrOf(mutability, ref expr) => {
212 rewrite_expr_addrof(context, mutability, expr, shape)
214 ast::ExprKind::Cast(ref expr, ref ty) => rewrite_pair(
217 PairParts::infix(" as "),
220 SeparatorPlace::Front,
222 ast::ExprKind::Type(ref expr, ref ty) => rewrite_pair(
225 PairParts::infix(": "),
228 SeparatorPlace::Back,
230 ast::ExprKind::Index(ref expr, ref index) => {
231 rewrite_index(&**expr, &**index, context, shape)
233 ast::ExprKind::Repeat(ref expr, ref repeats) => rewrite_pair(
236 PairParts::new("[", "; ", "]"),
239 SeparatorPlace::Back,
241 ast::ExprKind::Range(ref lhs, ref rhs, limits) => {
242 let delim = match limits {
243 ast::RangeLimits::HalfOpen => "..",
244 ast::RangeLimits::Closed => "..=",
247 fn needs_space_before_range(context: &RewriteContext, lhs: &ast::Expr) -> bool {
249 ast::ExprKind::Lit(ref lit) => match lit.node {
250 ast::LitKind::FloatUnsuffixed(..) => {
251 context.snippet(lit.span).ends_with('.')
259 fn needs_space_after_range(rhs: &ast::Expr) -> bool {
261 // Don't format `.. ..` into `....`, which is invalid.
263 // This check is unnecessary for `lhs`, because a range
264 // starting from another range needs parentheses as `(x ..) ..`
265 // (`x .. ..` is a range from `x` to `..`).
266 ast::ExprKind::Range(None, _, _) => true,
271 let default_sp_delim = |lhs: Option<&ast::Expr>, rhs: Option<&ast::Expr>| {
272 let space_if = |b: bool| if b { " " } else { "" };
276 lhs.map_or("", |lhs| space_if(needs_space_before_range(context, lhs))),
278 rhs.map_or("", |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::infix(&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::TryBlock(ref block) => {
321 if let rw @ Some(_) =
322 rewrite_single_line_block(context, "try ", block, Some(&expr.attrs), None, shape)
327 let budget = shape.width.saturating_sub(9);
336 Shape::legacy(budget, shape.indent)
341 ast::ExprKind::ObsoleteInPlace(ref lhs, ref rhs) => lhs
342 .rewrite(context, shape)
344 .and_then(|lhs| rewrite_assign_rhs(context, lhs, &**rhs, shape)),
345 ast::ExprKind::Async(capture_by, _node_id, ref block) => {
346 let mover = if capture_by == ast::CaptureBy::Value {
351 if let rw @ Some(_) = rewrite_single_line_block(
353 format!("{}{}", "async ", mover).as_str(),
362 let budget = shape.width.saturating_sub(6);
372 Shape::legacy(budget, shape.indent)
380 .and_then(|expr_str| recover_comment_removed(expr_str, expr.span, context))
381 .and_then(|expr_str| {
382 let attrs = outer_attributes(&expr.attrs);
383 let attrs_str = attrs.rewrite(context, shape)?;
385 attrs.last().map_or(expr.span.lo(), |attr| attr.span.hi()),
388 combine_strs_with_missing_comments(context, &attrs_str, &expr_str, span, shape, false)
392 pub fn rewrite_array<'a, T: 'a + IntoOverflowableItem<'a>>(
394 exprs: impl Iterator<Item = &'a T>,
396 context: &'a RewriteContext,
398 force_separator_tactic: Option<SeparatorTactic>,
399 delim_token: Option<DelimToken>,
400 ) -> Option<String> {
401 overflow::rewrite_with_square_brackets(
407 force_separator_tactic,
412 fn rewrite_empty_block(
413 context: &RewriteContext,
415 attrs: Option<&[ast::Attribute]>,
416 label: Option<ast::Label>,
419 ) -> Option<String> {
420 let label_str = rewrite_label(label);
421 if attrs.map_or(false, |a| !inner_attributes(a).is_empty()) {
425 if block.stmts.is_empty()
426 && !block_contains_comment(block, context.source_map)
429 return Some(format!("{}{}{{}}", prefix, label_str));
432 // If a block contains only a single-line comment, then leave it on one line.
433 let user_str = context.snippet(block.span);
434 let user_str = user_str.trim();
435 if user_str.starts_with('{') && user_str.ends_with('}') {
436 let comment_str = user_str[1..user_str.len() - 1].trim();
437 if block.stmts.is_empty()
438 && !comment_str.contains('\n')
439 && !comment_str.starts_with("//")
440 && comment_str.len() + 4 <= shape.width
442 return Some(format!("{}{}{{ {} }}", prefix, label_str, comment_str));
449 fn block_prefix(context: &RewriteContext, block: &ast::Block, shape: Shape) -> Option<String> {
450 Some(match block.rules {
451 ast::BlockCheckMode::Unsafe(..) => {
452 let snippet = context.snippet(block.span);
453 let open_pos = snippet.find_uncommented("{")?;
454 // Extract comment between unsafe and block start.
455 let trimmed = &snippet[6..open_pos].trim();
457 if !trimmed.is_empty() {
458 // 9 = "unsafe {".len(), 7 = "unsafe ".len()
459 let budget = shape.width.checked_sub(9)?;
465 Shape::legacy(budget, shape.indent + 7),
473 ast::BlockCheckMode::Default => String::new(),
477 fn rewrite_single_line_block(
478 context: &RewriteContext,
481 attrs: Option<&[ast::Attribute]>,
482 label: Option<ast::Label>,
484 ) -> Option<String> {
485 if is_simple_block(block, attrs, context.source_map) {
486 let expr_shape = shape.offset_left(last_line_width(prefix))?;
487 let expr_str = block.stmts[0].rewrite(context, expr_shape)?;
488 let label_str = rewrite_label(label);
489 let result = format!("{}{}{{ {} }}", prefix, label_str, expr_str);
490 if result.len() <= shape.width && !result.contains('\n') {
497 pub fn rewrite_block_with_visitor(
498 context: &RewriteContext,
501 attrs: Option<&[ast::Attribute]>,
502 label: Option<ast::Label>,
505 ) -> Option<String> {
506 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, label, prefix, shape) {
510 let mut visitor = FmtVisitor::from_context(context);
511 visitor.block_indent = shape.indent;
512 visitor.is_if_else_block = context.is_if_else_block();
514 ast::BlockCheckMode::Unsafe(..) => {
515 let snippet = context.snippet(block.span);
516 let open_pos = snippet.find_uncommented("{")?;
517 visitor.last_pos = block.span.lo() + BytePos(open_pos as u32)
519 ast::BlockCheckMode::Default => visitor.last_pos = block.span.lo(),
522 let inner_attrs = attrs.map(inner_attributes);
523 let label_str = rewrite_label(label);
524 visitor.visit_block(block, inner_attrs.as_ref().map(|a| &**a), has_braces);
525 Some(format!("{}{}{}", prefix, label_str, visitor.buffer))
528 impl Rewrite for ast::Block {
529 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
530 rewrite_block(self, None, None, context, shape)
536 attrs: Option<&[ast::Attribute]>,
537 label: Option<ast::Label>,
538 context: &RewriteContext,
540 ) -> Option<String> {
541 let prefix = block_prefix(context, block, shape)?;
543 // shape.width is used only for the single line case: either the empty block `{}`,
544 // or an unsafe expression `unsafe { e }`.
545 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, label, &prefix, shape) {
549 let result = rewrite_block_with_visitor(context, &prefix, block, attrs, label, shape, true);
550 if let Some(ref result_str) = result {
551 if result_str.lines().count() <= 3 {
552 if let rw @ Some(_) =
553 rewrite_single_line_block(context, &prefix, block, attrs, label, shape)
563 impl Rewrite for ast::Stmt {
564 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
565 skip_out_of_file_lines_range!(context, self.span());
567 let result = match self.node {
568 ast::StmtKind::Local(ref local) => local.rewrite(context, shape),
569 ast::StmtKind::Expr(ref ex) | ast::StmtKind::Semi(ref ex) => {
570 let suffix = if semicolon_for_stmt(context, self) {
576 let shape = shape.sub_width(suffix.len())?;
577 format_expr(ex, ExprType::Statement, context, shape).map(|s| s + suffix)
579 ast::StmtKind::Mac(..) | ast::StmtKind::Item(..) => None,
581 result.and_then(|res| recover_comment_removed(res, self.span(), context))
585 // Rewrite condition if the given expression has one.
586 pub fn rewrite_cond(context: &RewriteContext, expr: &ast::Expr, shape: Shape) -> Option<String> {
588 ast::ExprKind::Match(ref cond, _) => {
590 let cond_shape = match context.config.indent_style() {
591 IndentStyle::Visual => shape.shrink_left(6).and_then(|s| s.sub_width(2))?,
592 IndentStyle::Block => shape.offset_left(8)?,
594 cond.rewrite(context, cond_shape)
596 _ => to_control_flow(expr, ExprType::SubExpression).and_then(|control_flow| {
598 String::from("\n") + &shape.indent.block_only().to_string(context.config);
600 .rewrite_cond(context, shape, &alt_block_sep)
601 .and_then(|rw| Some(rw.0))
606 // Abstraction over control flow expressions
608 struct ControlFlow<'a> {
609 cond: Option<&'a ast::Expr>,
610 block: &'a ast::Block,
611 else_block: Option<&'a ast::Expr>,
612 label: Option<ast::Label>,
613 pats: Vec<&'a ast::Pat>,
617 allow_single_line: bool,
618 // True if this is an `if` expression in an `else if` :-( hacky
623 fn to_control_flow(expr: &ast::Expr, expr_type: ExprType) -> Option<ControlFlow> {
625 ast::ExprKind::If(ref cond, ref if_block, ref else_block) => Some(ControlFlow::new_if(
629 else_block.as_ref().map(|e| &**e),
630 expr_type == ExprType::SubExpression,
634 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref else_block) => {
635 Some(ControlFlow::new_if(
637 ptr_vec_to_ref_vec(pat),
639 else_block.as_ref().map(|e| &**e),
640 expr_type == ExprType::SubExpression,
645 ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
646 Some(ControlFlow::new_for(pat, cond, block, label, expr.span))
648 ast::ExprKind::Loop(ref block, label) => {
649 Some(ControlFlow::new_loop(block, label, expr.span))
651 ast::ExprKind::While(ref cond, ref block, label) => Some(ControlFlow::new_while(
658 ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => Some(
659 ControlFlow::new_while(ptr_vec_to_ref_vec(pat), cond, block, label, expr.span),
665 fn choose_matcher(pats: &[&ast::Pat]) -> &'static str {
673 impl<'a> ControlFlow<'a> {
676 pats: Vec<&'a ast::Pat>,
677 block: &'a ast::Block,
678 else_block: Option<&'a ast::Expr>,
679 allow_single_line: bool,
682 ) -> ControlFlow<'a> {
683 let matcher = choose_matcher(&pats);
699 fn new_loop(block: &'a ast::Block, label: Option<ast::Label>, span: Span) -> ControlFlow<'a> {
709 allow_single_line: false,
716 pats: Vec<&'a ast::Pat>,
718 block: &'a ast::Block,
719 label: Option<ast::Label>,
721 ) -> ControlFlow<'a> {
722 let matcher = choose_matcher(&pats);
732 allow_single_line: false,
741 block: &'a ast::Block,
742 label: Option<ast::Label>,
744 ) -> ControlFlow<'a> {
754 allow_single_line: false,
760 fn rewrite_single_line(
763 context: &RewriteContext,
765 ) -> Option<String> {
766 assert!(self.allow_single_line);
767 let else_block = self.else_block?;
768 let fixed_cost = self.keyword.len() + " { } else { }".len();
770 if let ast::ExprKind::Block(ref else_node, _) = else_block.node {
771 if !is_simple_block(self.block, None, context.source_map)
772 || !is_simple_block(else_node, None, context.source_map)
773 || pat_expr_str.contains('\n')
778 let new_width = width.checked_sub(pat_expr_str.len() + fixed_cost)?;
779 let expr = &self.block.stmts[0];
780 let if_str = expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
782 let new_width = new_width.checked_sub(if_str.len())?;
783 let else_expr = &else_node.stmts[0];
784 let else_str = else_expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
786 if if_str.contains('\n') || else_str.contains('\n') {
790 let result = format!(
791 "{} {} {{ {} }} else {{ {} }}",
792 self.keyword, pat_expr_str, if_str, else_str
795 if result.len() <= width {
804 /// Returns true if the last line of pat_str has leading whitespace and it is wider than the
806 fn last_line_offsetted(start_column: usize, pat_str: &str) -> bool {
807 let mut leading_whitespaces = 0;
808 for c in pat_str.chars().rev() {
811 _ if c.is_whitespace() => leading_whitespaces += 1,
812 _ => leading_whitespaces = 0,
815 leading_whitespaces > start_column
818 impl<'a> ControlFlow<'a> {
821 context: &RewriteContext,
825 ) -> Option<String> {
826 debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, self.pats, expr);
828 let cond_shape = shape.offset_left(offset)?;
829 if !self.pats.is_empty() {
830 let matcher = if self.matcher.is_empty() {
831 self.matcher.to_owned()
833 format!("{} ", self.matcher)
835 let pat_shape = cond_shape
836 .offset_left(matcher.len())?
837 .sub_width(self.connector.len())?;
838 let pat_string = rewrite_multiple_patterns(context, &self.pats, pat_shape)?;
839 let result = format!("{}{}{}", matcher, pat_string, self.connector);
840 return rewrite_assign_rhs(context, result, expr, cond_shape);
843 let expr_rw = expr.rewrite(context, cond_shape);
844 // The expression may (partially) fit on the current line.
845 // We do not allow splitting between `if` and condition.
846 if self.keyword == "if" || expr_rw.is_some() {
850 // The expression won't fit on the current line, jump to next.
851 let nested_shape = shape
852 .block_indent(context.config.tab_spaces())
853 .with_max_width(context.config);
854 let nested_indent_str = nested_shape.indent.to_string_with_newline(context.config);
855 expr.rewrite(context, nested_shape)
856 .map(|expr_rw| format!("{}{}", nested_indent_str, expr_rw))
861 context: &RewriteContext,
864 ) -> Option<(String, usize)> {
865 // Do not take the rhs overhead from the upper expressions into account
866 // when rewriting pattern.
867 let new_width = context.budget(shape.used_width());
868 let fresh_shape = Shape {
872 let constr_shape = if self.nested_if {
873 // We are part of an if-elseif-else chain. Our constraints are tightened.
874 // 7 = "} else " .len()
875 fresh_shape.offset_left(7)?
880 let label_string = rewrite_label(self.label);
881 // 1 = space after keyword.
882 let offset = self.keyword.len() + label_string.len() + 1;
884 let pat_expr_string = match self.cond {
885 Some(cond) => self.rewrite_pat_expr(context, cond, constr_shape, offset)?,
886 None => String::new(),
890 if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
896 let one_line_budget = context
899 .saturating_sub(constr_shape.used_width() + offset + brace_overhead);
900 let force_newline_brace = (pat_expr_string.contains('\n')
901 || pat_expr_string.len() > one_line_budget)
902 && (!last_line_extendable(&pat_expr_string)
903 || last_line_offsetted(shape.used_width(), &pat_expr_string));
905 // Try to format if-else on single line.
906 if self.allow_single_line
910 .single_line_if_else_max_width
913 let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width);
915 if let Some(cond_str) = trial {
920 .single_line_if_else_max_width
922 return Some((cond_str, 0));
927 let cond_span = if let Some(cond) = self.cond {
930 mk_sp(self.block.span.lo(), self.block.span.lo())
933 // `for event in event`
934 // Do not include label in the span.
937 .map_or(self.span.lo(), |label| label.ident.span.hi());
938 let between_kwd_cond = mk_sp(
941 .span_after(mk_sp(lo, self.span.hi()), self.keyword.trim()),
942 if self.pats.is_empty() {
944 } else if self.matcher.is_empty() {
945 self.pats[0].span.lo()
949 .span_before(self.span, self.matcher.trim())
953 let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape);
955 let after_cond_comment =
956 extract_comment(mk_sp(cond_span.hi(), self.block.span.lo()), context, shape);
958 let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
960 } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine
961 || force_newline_brace
968 let used_width = if pat_expr_string.contains('\n') {
969 last_line_width(&pat_expr_string)
971 // 2 = spaces after keyword and condition.
972 label_string.len() + self.keyword.len() + pat_expr_string.len() + 2
980 between_kwd_cond_comment.as_ref().map_or(
981 if pat_expr_string.is_empty() || pat_expr_string.starts_with('\n') {
989 after_cond_comment.as_ref().map_or(block_sep, |s| &**s)
996 impl<'a> Rewrite for ControlFlow<'a> {
997 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
998 debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
1000 let alt_block_sep = &shape.indent.to_string_with_newline(context.config);
1001 let (cond_str, used_width) = self.rewrite_cond(context, shape, alt_block_sep)?;
1002 // If `used_width` is 0, it indicates that whole control flow is written in a single line.
1003 if used_width == 0 {
1004 return Some(cond_str);
1007 let block_width = shape.width.saturating_sub(used_width);
1008 // This is used only for the empty block case: `{}`. So, we use 1 if we know
1009 // we should avoid the single line case.
1010 let block_width = if self.else_block.is_some() || self.nested_if {
1015 let block_shape = Shape {
1020 let old_val = context.is_if_else_block.replace(self.else_block.is_some());
1022 rewrite_block_with_visitor(context, "", self.block, None, None, block_shape, true);
1023 context.is_if_else_block.replace(old_val);
1027 let mut result = format!("{}{}", cond_str, block_str);
1029 if let Some(else_block) = self.else_block {
1030 let shape = Shape::indented(shape.indent, context.config);
1031 let mut last_in_chain = false;
1032 let rewrite = match else_block.node {
1033 // If the else expression is another if-else expression, prevent it
1034 // from being formatted on a single line.
1035 // Note how we're passing the original shape, as the
1036 // cost of "else" should not cascade.
1037 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref next_else_block) => {
1038 ControlFlow::new_if(
1040 ptr_vec_to_ref_vec(pat),
1042 next_else_block.as_ref().map(|e| &**e),
1045 mk_sp(else_block.span.lo(), self.span.hi()),
1047 .rewrite(context, shape)
1049 ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => {
1050 ControlFlow::new_if(
1054 next_else_block.as_ref().map(|e| &**e),
1057 mk_sp(else_block.span.lo(), self.span.hi()),
1059 .rewrite(context, shape)
1062 last_in_chain = true;
1063 // When rewriting a block, the width is only used for single line
1064 // blocks, passing 1 lets us avoid that.
1065 let else_shape = Shape {
1066 width: min(1, shape.width),
1069 format_expr(else_block, ExprType::Statement, context, else_shape)
1073 let between_kwd_else_block = mk_sp(
1074 self.block.span.hi(),
1077 .span_before(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1079 let between_kwd_else_block_comment =
1080 extract_comment(between_kwd_else_block, context, shape);
1082 let after_else = mk_sp(
1085 .span_after(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1086 else_block.span.lo(),
1088 let after_else_comment = extract_comment(after_else, context, shape);
1090 let between_sep = match context.config.control_brace_style() {
1091 ControlBraceStyle::AlwaysNextLine | ControlBraceStyle::ClosingNextLine => {
1094 ControlBraceStyle::AlwaysSameLine => " ",
1096 let after_sep = match context.config.control_brace_style() {
1097 ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep,
1101 result.push_str(&format!(
1103 between_kwd_else_block_comment
1105 .map_or(between_sep, |s| &**s),
1106 after_else_comment.as_ref().map_or(after_sep, |s| &**s),
1108 result.push_str(&rewrite?);
1115 fn rewrite_label(opt_label: Option<ast::Label>) -> Cow<'static, str> {
1117 Some(label) => Cow::from(format!("{}: ", label.ident)),
1118 None => Cow::from(""),
1122 fn extract_comment(span: Span, context: &RewriteContext, shape: Shape) -> Option<String> {
1123 match rewrite_missing_comment(span, shape, context) {
1124 Some(ref comment) if !comment.is_empty() => Some(format!(
1125 "{indent}{}{indent}",
1127 indent = shape.indent.to_string_with_newline(context.config)
1133 pub fn block_contains_comment(block: &ast::Block, source_map: &SourceMap) -> bool {
1134 let snippet = source_map.span_to_snippet(block.span).unwrap();
1135 contains_comment(&snippet)
1138 // Checks that a block contains no statements, an expression and no comments or
1140 // FIXME: incorrectly returns false when comment is contained completely within
1142 pub fn is_simple_block(
1144 attrs: Option<&[ast::Attribute]>,
1145 source_map: &SourceMap,
1147 (block.stmts.len() == 1
1148 && stmt_is_expr(&block.stmts[0])
1149 && !block_contains_comment(block, source_map)
1150 && attrs.map_or(true, |a| a.is_empty()))
1153 /// Checks whether a block contains at most one statement or expression, and no
1154 /// comments or attributes.
1155 pub fn is_simple_block_stmt(
1157 attrs: Option<&[ast::Attribute]>,
1158 source_map: &SourceMap,
1160 block.stmts.len() <= 1
1161 && !block_contains_comment(block, source_map)
1162 && attrs.map_or(true, |a| a.is_empty())
1165 /// Checks whether a block contains no statements, expressions, comments, or
1166 /// inner attributes.
1167 pub fn is_empty_block(
1169 attrs: Option<&[ast::Attribute]>,
1170 source_map: &SourceMap,
1172 block.stmts.is_empty()
1173 && !block_contains_comment(block, source_map)
1174 && attrs.map_or(true, |a| inner_attributes(a).is_empty())
1177 pub fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
1179 ast::StmtKind::Expr(..) => true,
1184 pub fn is_unsafe_block(block: &ast::Block) -> bool {
1185 if let ast::BlockCheckMode::Unsafe(..) = block.rules {
1192 pub fn rewrite_multiple_patterns(
1193 context: &RewriteContext,
1196 ) -> Option<String> {
1199 .map(|p| p.rewrite(context, shape))
1200 .collect::<Option<Vec<_>>>()?;
1202 let use_mixed_layout = pats
1204 .zip(pat_strs.iter())
1205 .all(|(pat, pat_str)| is_short_pattern(pat, pat_str));
1206 let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
1207 let tactic = if use_mixed_layout {
1208 DefinitiveListTactic::Mixed
1212 ListTactic::HorizontalVertical,
1213 Separator::VerticalBar,
1217 let fmt = ListFormatting::new(shape, context.config)
1220 .separator_place(context.config.binop_separator())
1221 .ends_with_newline(false);
1222 write_list(&items, &fmt)
1225 pub fn rewrite_literal(context: &RewriteContext, l: &ast::Lit, shape: Shape) -> Option<String> {
1227 ast::LitKind::Str(_, ast::StrStyle::Cooked) => rewrite_string_lit(context, l.span, shape),
1229 context.snippet(l.span).to_owned(),
1230 context.config.max_width(),
1236 fn rewrite_string_lit(context: &RewriteContext, span: Span, shape: Shape) -> Option<String> {
1237 let string_lit = context.snippet(span);
1239 if !context.config.format_strings() {
1244 .all(|line| line.ends_with('\\'))
1246 let new_indent = shape.visual_indent(1).indent;
1247 let indented_string_lit = String::from(
1253 new_indent.to_string(context.config),
1257 .collect::<Vec<_>>()
1261 return wrap_str(indented_string_lit, context.config.max_width(), shape);
1263 return wrap_str(string_lit.to_owned(), context.config.max_width(), shape);
1267 // Remove the quote characters.
1268 let str_lit = &string_lit[1..string_lit.len() - 1];
1272 &StringFormat::new(shape.visual_indent(0), context.config),
1273 shape.width.saturating_sub(2),
1277 fn choose_separator_tactic(context: &RewriteContext, span: Span) -> Option<SeparatorTactic> {
1278 if context.inside_macro() {
1279 if span_ends_with_comma(context, span) {
1280 Some(SeparatorTactic::Always)
1282 Some(SeparatorTactic::Never)
1289 pub fn rewrite_call(
1290 context: &RewriteContext,
1292 args: &[ptr::P<ast::Expr>],
1295 ) -> Option<String> {
1296 overflow::rewrite_with_parens(
1302 context.config.width_heuristics().fn_call_width,
1303 choose_separator_tactic(context, span),
1307 pub fn is_simple_expr(expr: &ast::Expr) -> bool {
1309 ast::ExprKind::Lit(..) => true,
1310 ast::ExprKind::Path(ref qself, ref path) => qself.is_none() && path.segments.len() <= 1,
1311 ast::ExprKind::AddrOf(_, ref expr)
1312 | ast::ExprKind::Box(ref expr)
1313 | ast::ExprKind::Cast(ref expr, _)
1314 | ast::ExprKind::Field(ref expr, _)
1315 | ast::ExprKind::Try(ref expr)
1316 | ast::ExprKind::Unary(_, ref expr) => is_simple_expr(expr),
1317 ast::ExprKind::Index(ref lhs, ref rhs) => is_simple_expr(lhs) && is_simple_expr(rhs),
1318 ast::ExprKind::Repeat(ref lhs, ref rhs) => {
1319 is_simple_expr(lhs) && is_simple_expr(&*rhs.value)
1325 pub fn is_every_expr_simple(lists: &[OverflowableItem]) -> bool {
1326 lists.iter().all(OverflowableItem::is_simple)
1329 pub fn can_be_overflowed_expr(context: &RewriteContext, expr: &ast::Expr, args_len: usize) -> bool {
1331 ast::ExprKind::Match(..) => {
1332 (context.use_block_indent() && args_len == 1)
1333 || (context.config.indent_style() == IndentStyle::Visual && args_len > 1)
1335 ast::ExprKind::If(..)
1336 | ast::ExprKind::IfLet(..)
1337 | ast::ExprKind::ForLoop(..)
1338 | ast::ExprKind::Loop(..)
1339 | ast::ExprKind::While(..)
1340 | ast::ExprKind::WhileLet(..) => {
1341 context.config.combine_control_expr() && context.use_block_indent() && args_len == 1
1343 ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => {
1344 context.use_block_indent() || context.config.indent_style() == IndentStyle::Visual
1346 ast::ExprKind::Array(..)
1347 | ast::ExprKind::Call(..)
1348 | ast::ExprKind::Mac(..)
1349 | ast::ExprKind::MethodCall(..)
1350 | ast::ExprKind::Struct(..)
1351 | ast::ExprKind::Tup(..) => context.use_block_indent() && args_len == 1,
1352 ast::ExprKind::AddrOf(_, ref expr)
1353 | ast::ExprKind::Box(ref expr)
1354 | ast::ExprKind::Try(ref expr)
1355 | ast::ExprKind::Unary(_, ref expr)
1356 | ast::ExprKind::Cast(ref expr, _) => can_be_overflowed_expr(context, expr, args_len),
1361 pub fn is_nested_call(expr: &ast::Expr) -> bool {
1363 ast::ExprKind::Call(..) | ast::ExprKind::Mac(..) => true,
1364 ast::ExprKind::AddrOf(_, ref expr)
1365 | ast::ExprKind::Box(ref expr)
1366 | ast::ExprKind::Try(ref expr)
1367 | ast::ExprKind::Unary(_, ref expr)
1368 | ast::ExprKind::Cast(ref expr, _) => is_nested_call(expr),
1373 /// Return true if a function call or a method call represented by the given span ends with a
1374 /// trailing comma. This function is used when rewriting macro, as adding or removing a trailing
1375 /// comma from macro can potentially break the code.
1376 pub fn span_ends_with_comma(context: &RewriteContext, span: Span) -> bool {
1377 let mut result: bool = Default::default();
1378 let mut prev_char: char = Default::default();
1379 let closing_delimiters = &[')', '}', ']'];
1381 for (kind, c) in CharClasses::new(context.snippet(span).chars()) {
1383 _ if kind.is_comment() || c.is_whitespace() => continue,
1384 c if closing_delimiters.contains(&c) => {
1385 result &= !closing_delimiters.contains(&prev_char);
1387 ',' => result = true,
1388 _ => result = false,
1397 context: &RewriteContext,
1398 mut subexpr: &ast::Expr,
1401 ) -> Option<String> {
1402 debug!("rewrite_paren, shape: {:?}", shape);
1404 // Extract comments within parens.
1407 let mut pre_comment;
1408 let mut post_comment;
1409 let remove_nested_parens = context.config.remove_nested_parens();
1412 pre_span = mk_sp(span.lo() + BytePos(1), subexpr.span.lo());
1413 post_span = mk_sp(subexpr.span.hi(), span.hi() - BytePos(1));
1414 pre_comment = rewrite_missing_comment(pre_span, shape, context)?;
1415 post_comment = rewrite_missing_comment(post_span, shape, context)?;
1417 // Remove nested parens if there are no comments.
1418 if let ast::ExprKind::Paren(ref subsubexpr) = subexpr.node {
1419 if remove_nested_parens && pre_comment.is_empty() && post_comment.is_empty() {
1420 span = subexpr.span;
1421 subexpr = subsubexpr;
1430 let sub_shape = shape.offset_left(1)?.sub_width(1)?;
1431 let subexpr_str = subexpr.rewrite(context, sub_shape)?;
1432 let fits_single_line = !pre_comment.contains("//") && !post_comment.contains("//");
1433 if fits_single_line {
1434 Some(format!("({}{}{})", pre_comment, &subexpr_str, post_comment))
1436 rewrite_paren_in_multi_line(context, subexpr, shape, pre_span, post_span)
1440 fn rewrite_paren_in_multi_line(
1441 context: &RewriteContext,
1442 subexpr: &ast::Expr,
1446 ) -> Option<String> {
1447 let nested_indent = shape.indent.block_indent(context.config);
1448 let nested_shape = Shape::indented(nested_indent, context.config);
1449 let pre_comment = rewrite_missing_comment(pre_span, nested_shape, context)?;
1450 let post_comment = rewrite_missing_comment(post_span, nested_shape, context)?;
1451 let subexpr_str = subexpr.rewrite(context, nested_shape)?;
1453 let mut result = String::with_capacity(subexpr_str.len() * 2);
1455 if !pre_comment.is_empty() {
1456 result.push_str(&nested_indent.to_string_with_newline(context.config));
1457 result.push_str(&pre_comment);
1459 result.push_str(&nested_indent.to_string_with_newline(context.config));
1460 result.push_str(&subexpr_str);
1461 if !post_comment.is_empty() {
1462 result.push_str(&nested_indent.to_string_with_newline(context.config));
1463 result.push_str(&post_comment);
1465 result.push_str(&shape.indent.to_string_with_newline(context.config));
1474 context: &RewriteContext,
1476 ) -> Option<String> {
1477 let expr_str = expr.rewrite(context, shape)?;
1479 let offset = last_line_width(&expr_str) + 1;
1480 let rhs_overhead = shape.rhs_overhead(context.config);
1481 let index_shape = if expr_str.contains('\n') {
1482 Shape::legacy(context.config.max_width(), shape.indent)
1483 .offset_left(offset)
1484 .and_then(|shape| shape.sub_width(1 + rhs_overhead))
1486 match context.config.indent_style() {
1487 IndentStyle::Block => shape
1488 .offset_left(offset)
1489 .and_then(|shape| shape.sub_width(1)),
1490 IndentStyle::Visual => shape.visual_indent(offset).sub_width(offset + 1),
1493 let orig_index_rw = index_shape.and_then(|s| index.rewrite(context, s));
1495 // Return if index fits in a single line.
1496 match orig_index_rw {
1497 Some(ref index_str) if !index_str.contains('\n') => {
1498 return Some(format!("{}[{}]", expr_str, index_str));
1503 // Try putting index on the next line and see if it fits in a single line.
1504 let indent = shape.indent.block_indent(context.config);
1505 let index_shape = Shape::indented(indent, context.config).offset_left(1)?;
1506 let index_shape = index_shape.sub_width(1 + rhs_overhead)?;
1507 let new_index_rw = index.rewrite(context, index_shape);
1508 match (orig_index_rw, new_index_rw) {
1509 (_, Some(ref new_index_str)) if !new_index_str.contains('\n') => Some(format!(
1512 indent.to_string_with_newline(context.config),
1515 (None, Some(ref new_index_str)) => Some(format!(
1518 indent.to_string_with_newline(context.config),
1521 (Some(ref index_str), _) => Some(format!("{}[{}]", expr_str, index_str)),
1526 fn struct_lit_can_be_aligned(fields: &[ast::Field], base: Option<&ast::Expr>) -> bool {
1531 fields.iter().all(|field| !field.is_shorthand)
1534 fn rewrite_struct_lit<'a>(
1535 context: &RewriteContext,
1537 fields: &'a [ast::Field],
1538 base: Option<&'a ast::Expr>,
1541 ) -> Option<String> {
1542 debug!("rewrite_struct_lit: shape {:?}", shape);
1544 enum StructLitField<'a> {
1545 Regular(&'a ast::Field),
1546 Base(&'a ast::Expr),
1550 let path_shape = shape.sub_width(2)?;
1551 let path_str = rewrite_path(context, PathContext::Expr, None, path, path_shape)?;
1553 if fields.is_empty() && base.is_none() {
1554 return Some(format!("{} {{}}", path_str));
1557 // Foo { a: Foo } - indent is +3, width is -5.
1558 let (h_shape, v_shape) = struct_lit_shape(shape, context, path_str.len() + 3, 2)?;
1560 let one_line_width = h_shape.map_or(0, |shape| shape.width);
1561 let body_lo = context.snippet_provider.span_after(span, "{");
1562 let fields_str = if struct_lit_can_be_aligned(fields, base)
1563 && context.config.struct_field_align_threshold() > 0
1565 rewrite_with_alignment(
1569 mk_sp(body_lo, span.hi()),
1573 let field_iter = fields
1575 .map(StructLitField::Regular)
1576 .chain(base.into_iter().map(StructLitField::Base));
1578 let span_lo = |item: &StructLitField| match *item {
1579 StructLitField::Regular(field) => field.span().lo(),
1580 StructLitField::Base(expr) => {
1581 let last_field_hi = fields.last().map_or(span.lo(), |field| field.span.hi());
1582 let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo()));
1583 let pos = snippet.find_uncommented("..").unwrap();
1584 last_field_hi + BytePos(pos as u32)
1587 let span_hi = |item: &StructLitField| match *item {
1588 StructLitField::Regular(field) => field.span().hi(),
1589 StructLitField::Base(expr) => expr.span.hi(),
1591 let rewrite = |item: &StructLitField| match *item {
1592 StructLitField::Regular(field) => {
1593 // The 1 taken from the v_budget is for the comma.
1594 rewrite_field(context, field, v_shape.sub_width(1)?, 0)
1596 StructLitField::Base(expr) => {
1598 expr.rewrite(context, v_shape.offset_left(2)?)
1599 .map(|s| format!("..{}", s))
1603 let items = itemize_list(
1604 context.snippet_provider,
1615 let item_vec = items.collect::<Vec<_>>();
1617 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
1618 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
1620 let ends_with_comma = span_ends_with_comma(context, span);
1621 let force_no_trailing_comma = context.inside_macro() && !ends_with_comma;
1623 let fmt = struct_lit_formatting(
1627 force_no_trailing_comma || base.is_some() || !context.use_block_indent(),
1630 write_list(&item_vec, &fmt)?
1633 let fields_str = wrap_struct_field(context, &fields_str, shape, v_shape, one_line_width);
1634 Some(format!("{} {{{}}}", path_str, fields_str))
1636 // FIXME if context.config.indent_style() == Visual, but we run out
1637 // of space, we should fall back to BlockIndent.
1640 pub fn wrap_struct_field(
1641 context: &RewriteContext,
1644 nested_shape: Shape,
1645 one_line_width: usize,
1647 if context.config.indent_style() == IndentStyle::Block
1648 && (fields_str.contains('\n')
1649 || !context.config.struct_lit_single_line()
1650 || fields_str.len() > one_line_width)
1654 nested_shape.indent.to_string_with_newline(context.config),
1656 shape.indent.to_string_with_newline(context.config)
1659 // One liner or visual indent.
1660 format!(" {} ", fields_str)
1664 pub fn struct_lit_field_separator(config: &Config) -> &str {
1665 colon_spaces(config.space_before_colon(), config.space_after_colon())
1668 pub fn rewrite_field(
1669 context: &RewriteContext,
1672 prefix_max_width: usize,
1673 ) -> Option<String> {
1674 if contains_skip(&field.attrs) {
1675 return Some(context.snippet(field.span()).to_owned());
1677 let mut attrs_str = field.attrs.rewrite(context, shape)?;
1678 if !attrs_str.is_empty() {
1679 attrs_str.push_str(&shape.indent.to_string_with_newline(context.config));
1681 let name = context.snippet(field.ident.span);
1682 if field.is_shorthand {
1683 Some(attrs_str + name)
1685 let mut separator = String::from(struct_lit_field_separator(context.config));
1686 for _ in 0..prefix_max_width.saturating_sub(name.len()) {
1687 separator.push(' ');
1689 let overhead = name.len() + separator.len();
1690 let expr_shape = shape.offset_left(overhead)?;
1691 let expr = field.expr.rewrite(context, expr_shape);
1694 Some(ref e) if e.as_str() == name && context.config.use_field_init_shorthand() => {
1695 Some(attrs_str + name)
1697 Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)),
1699 let expr_offset = shape.indent.block_indent(context.config);
1702 .rewrite(context, Shape::indented(expr_offset, context.config));
1708 expr_offset.to_string(context.config),
1717 fn rewrite_tuple_in_visual_indent_style<'a, T: 'a + IntoOverflowableItem<'a>>(
1718 context: &RewriteContext,
1719 mut items: impl Iterator<Item = &'a T>,
1722 is_singleton_tuple: bool,
1723 ) -> Option<String> {
1724 // In case of length 1, need a trailing comma
1725 debug!("rewrite_tuple_in_visual_indent_style {:?}", shape);
1726 if is_singleton_tuple {
1728 let nested_shape = shape.sub_width(3)?.visual_indent(1);
1732 .rewrite(context, nested_shape)
1733 .map(|s| format!("({},)", s));
1736 let list_lo = context.snippet_provider.span_after(span, "(");
1737 let nested_shape = shape.sub_width(2)?.visual_indent(1);
1738 let items = itemize_list(
1739 context.snippet_provider,
1743 |item| item.span().lo(),
1744 |item| item.span().hi(),
1745 |item| item.rewrite(context, nested_shape),
1747 span.hi() - BytePos(1),
1750 let item_vec: Vec<_> = items.collect();
1751 let tactic = definitive_tactic(
1753 ListTactic::HorizontalVertical,
1757 let fmt = ListFormatting::new(nested_shape, context.config)
1759 .ends_with_newline(false);
1760 let list_str = write_list(&item_vec, &fmt)?;
1762 Some(format!("({})", list_str))
1765 pub fn rewrite_tuple<'a, T: 'a + IntoOverflowableItem<'a>>(
1766 context: &'a RewriteContext,
1767 items: impl Iterator<Item = &'a T>,
1770 is_singleton_tuple: bool,
1771 ) -> Option<String> {
1772 debug!("rewrite_tuple {:?}", shape);
1773 if context.use_block_indent() {
1774 // We use the same rule as function calls for rewriting tuples.
1775 let force_tactic = if context.inside_macro() {
1776 if span_ends_with_comma(context, span) {
1777 Some(SeparatorTactic::Always)
1779 Some(SeparatorTactic::Never)
1781 } else if is_singleton_tuple {
1782 Some(SeparatorTactic::Always)
1786 overflow::rewrite_with_parens(
1792 context.config.width_heuristics().fn_call_width,
1796 rewrite_tuple_in_visual_indent_style(context, items, span, shape, is_singleton_tuple)
1800 pub fn rewrite_unary_prefix<R: Rewrite>(
1801 context: &RewriteContext,
1805 ) -> Option<String> {
1807 .rewrite(context, shape.offset_left(prefix.len())?)
1808 .map(|r| format!("{}{}", prefix, r))
1811 // FIXME: this is probably not correct for multi-line Rewrites. we should
1812 // subtract suffix.len() from the last line budget, not the first!
1813 pub fn rewrite_unary_suffix<R: Rewrite>(
1814 context: &RewriteContext,
1818 ) -> Option<String> {
1820 .rewrite(context, shape.sub_width(suffix.len())?)
1827 fn rewrite_unary_op(
1828 context: &RewriteContext,
1832 ) -> Option<String> {
1833 // For some reason, an UnOp is not spanned like BinOp!
1834 rewrite_unary_prefix(context, ast::UnOp::to_string(op), expr, shape)
1837 fn rewrite_assignment(
1838 context: &RewriteContext,
1841 op: Option<&ast::BinOp>,
1843 ) -> Option<String> {
1844 let operator_str = match op {
1845 Some(op) => context.snippet(op.span),
1849 // 1 = space between lhs and operator.
1850 let lhs_shape = shape.sub_width(operator_str.len() + 1)?;
1851 let lhs_str = format!("{} {}", lhs.rewrite(context, lhs_shape)?, operator_str);
1853 rewrite_assign_rhs(context, lhs_str, rhs, shape)
1856 /// Controls where to put the rhs.
1857 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
1858 pub enum RhsTactics {
1861 /// Put the rhs on the next line if it uses multiple line, without extra indentation.
1862 ForceNextLineWithoutIndent,
1865 // The left hand side must contain everything up to, and including, the
1866 // assignment operator.
1867 pub fn rewrite_assign_rhs<S: Into<String>, R: Rewrite>(
1868 context: &RewriteContext,
1872 ) -> Option<String> {
1873 rewrite_assign_rhs_with(context, lhs, ex, shape, RhsTactics::Default)
1876 pub fn rewrite_assign_rhs_with<S: Into<String>, R: Rewrite>(
1877 context: &RewriteContext,
1881 rhs_tactics: RhsTactics,
1882 ) -> Option<String> {
1883 let lhs = lhs.into();
1884 let last_line_width = last_line_width(&lhs).saturating_sub(if lhs.contains('\n') {
1885 shape.indent.width()
1889 // 1 = space between operator and rhs.
1890 let orig_shape = shape.offset_left(last_line_width + 1).unwrap_or(Shape {
1892 offset: shape.offset + last_line_width + 1,
1895 let rhs = choose_rhs(
1899 ex.rewrite(context, orig_shape),
1905 fn choose_rhs<R: Rewrite>(
1906 context: &RewriteContext,
1909 orig_rhs: Option<String>,
1910 rhs_tactics: RhsTactics,
1911 ) -> Option<String> {
1913 Some(ref new_str) if !new_str.contains('\n') && new_str.len() <= shape.width => {
1914 Some(format!(" {}", new_str))
1917 // Expression did not fit on the same line as the identifier.
1918 // Try splitting the line and see if that works better.
1919 let new_shape = shape_from_rhs_tactic(context, shape, rhs_tactics)?;
1920 let new_rhs = expr.rewrite(context, new_shape);
1921 let new_indent_str = &shape
1923 .block_indent(context.config)
1924 .to_string_with_newline(context.config);
1926 match (orig_rhs, new_rhs) {
1927 (Some(ref orig_rhs), Some(ref new_rhs))
1928 if wrap_str(new_rhs.clone(), context.config.max_width(), new_shape)
1931 Some(format!(" {}", orig_rhs))
1933 (Some(ref orig_rhs), Some(ref new_rhs))
1934 if prefer_next_line(orig_rhs, new_rhs, rhs_tactics) =>
1936 Some(format!("{}{}", new_indent_str, new_rhs))
1938 (None, Some(ref new_rhs)) => Some(format!("{}{}", new_indent_str, new_rhs)),
1939 (None, None) => None,
1940 (Some(orig_rhs), _) => Some(format!(" {}", orig_rhs)),
1946 fn shape_from_rhs_tactic(
1947 context: &RewriteContext,
1949 rhs_tactic: RhsTactics,
1950 ) -> Option<Shape> {
1952 RhsTactics::ForceNextLineWithoutIndent => shape
1953 .with_max_width(context.config)
1954 .sub_width(shape.indent.width()),
1955 RhsTactics::Default => {
1956 Shape::indented(shape.indent.block_indent(context.config), context.config)
1957 .sub_width(shape.rhs_overhead(context.config))
1962 pub fn prefer_next_line(orig_rhs: &str, next_line_rhs: &str, rhs_tactics: RhsTactics) -> bool {
1963 rhs_tactics == RhsTactics::ForceNextLineWithoutIndent
1964 || !next_line_rhs.contains('\n')
1965 || count_newlines(orig_rhs) > count_newlines(next_line_rhs) + 1
1966 || first_line_ends_with(orig_rhs, '(') && !first_line_ends_with(next_line_rhs, '(')
1967 || first_line_ends_with(orig_rhs, '{') && !first_line_ends_with(next_line_rhs, '{')
1968 || first_line_ends_with(orig_rhs, '[') && !first_line_ends_with(next_line_rhs, '[')
1971 fn rewrite_expr_addrof(
1972 context: &RewriteContext,
1973 mutability: ast::Mutability,
1976 ) -> Option<String> {
1977 let operator_str = match mutability {
1978 ast::Mutability::Immutable => "&",
1979 ast::Mutability::Mutable => "&mut ",
1981 rewrite_unary_prefix(context, operator_str, expr, shape)
1984 pub fn is_method_call(expr: &ast::Expr) -> bool {
1986 ast::ExprKind::MethodCall(..) => true,
1987 ast::ExprKind::AddrOf(_, ref expr)
1988 | ast::ExprKind::Box(ref expr)
1989 | ast::ExprKind::Cast(ref expr, _)
1990 | ast::ExprKind::Try(ref expr)
1991 | ast::ExprKind::Unary(_, ref expr) => is_method_call(expr),
1998 use super::last_line_offsetted;
2001 fn test_last_line_offsetted() {
2002 let lines = "one\n two";
2003 assert_eq!(last_line_offsetted(2, lines), true);
2004 assert_eq!(last_line_offsetted(4, lines), false);
2005 assert_eq!(last_line_offsetted(6, lines), false);
2007 let lines = "one two";
2008 assert_eq!(last_line_offsetted(2, lines), false);
2009 assert_eq!(last_line_offsetted(0, lines), false);
2011 let lines = "\ntwo";
2012 assert_eq!(last_line_offsetted(2, lines), false);
2013 assert_eq!(last_line_offsetted(0, lines), false);
2015 let lines = "one\n two three";
2016 assert_eq!(last_line_offsetted(2, lines), true);
2017 let lines = "one\n two three";
2018 assert_eq!(last_line_offsetted(2, lines), false);