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, MacroArg, MacroPosition};
31 use matches::rewrite_match;
33 use pairs::{rewrite_all_pairs, rewrite_pair, PairParts};
34 use patterns::{can_be_overflowed_pat, is_short_pattern, TuplePatField};
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::{can_be_overflowed_type, rewrite_path, PathContext};
42 colon_spaces, contains_skip, count_newlines, first_line_ends_with, first_line_width,
43 inner_attributes, last_line_extendable, last_line_width, mk_sp, outer_attributes,
44 ptr_vec_to_ref_vec, 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(
76 &ptr_vec_to_ref_vec(expr_vec),
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(ref 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, &ptr_vec_to_ref_vec(items), expr.span, shape)
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) => if let Some(ref expr) = *opt_expr {
183 rewrite_unary_prefix(context, "yield ", &**expr, shape)
185 Some("yield".to_string())
187 ast::ExprKind::Closure(capture, asyncness, movability, ref fn_decl, ref body, _) => {
188 closures::rewrite_closure(
189 capture, asyncness, movability, fn_decl, body, expr.span, context, shape,
192 ast::ExprKind::Try(..) | ast::ExprKind::Field(..) | ast::ExprKind::MethodCall(..) => {
193 rewrite_chain(expr, context, shape)
195 ast::ExprKind::Mac(ref mac) => {
196 rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| {
198 context.snippet(expr.span).to_owned(),
199 context.config.max_width(),
204 ast::ExprKind::Ret(None) => Some("return".to_owned()),
205 ast::ExprKind::Ret(Some(ref expr)) => {
206 rewrite_unary_prefix(context, "return ", &**expr, shape)
208 ast::ExprKind::Box(ref expr) => rewrite_unary_prefix(context, "box ", &**expr, shape),
209 ast::ExprKind::AddrOf(mutability, ref expr) => {
210 rewrite_expr_addrof(context, mutability, expr, shape)
212 ast::ExprKind::Cast(ref expr, ref ty) => rewrite_pair(
215 PairParts::infix(" as "),
218 SeparatorPlace::Front,
220 ast::ExprKind::Type(ref expr, ref ty) => rewrite_pair(
223 PairParts::infix(": "),
226 SeparatorPlace::Back,
228 ast::ExprKind::Index(ref expr, ref index) => {
229 rewrite_index(&**expr, &**index, context, shape)
231 ast::ExprKind::Repeat(ref expr, ref repeats) => rewrite_pair(
234 PairParts::new("[", "; ", "]"),
237 SeparatorPlace::Back,
239 ast::ExprKind::Range(ref lhs, ref rhs, limits) => {
240 let delim = match limits {
241 ast::RangeLimits::HalfOpen => "..",
242 ast::RangeLimits::Closed => "..=",
245 fn needs_space_before_range(context: &RewriteContext, lhs: &ast::Expr) -> bool {
247 ast::ExprKind::Lit(ref lit) => match lit.node {
248 ast::LitKind::FloatUnsuffixed(..) => {
249 context.snippet(lit.span).ends_with('.')
257 fn needs_space_after_range(rhs: &ast::Expr) -> bool {
259 // Don't format `.. ..` into `....`, which is invalid.
261 // This check is unnecessary for `lhs`, because a range
262 // starting from another range needs parentheses as `(x ..) ..`
263 // (`x .. ..` is a range from `x` to `..`).
264 ast::ExprKind::Range(None, _, _) => true,
269 let default_sp_delim = |lhs: Option<&ast::Expr>, rhs: Option<&ast::Expr>| {
270 let space_if = |b: bool| if b { " " } else { "" };
274 lhs.map(|lhs| space_if(needs_space_before_range(context, lhs)))
277 rhs.map(|rhs| space_if(needs_space_after_range(rhs)))
282 match (lhs.as_ref().map(|x| &**x), rhs.as_ref().map(|x| &**x)) {
283 (Some(lhs), Some(rhs)) => {
284 let sp_delim = if context.config.spaces_around_ranges() {
285 format!(" {} ", delim)
287 default_sp_delim(Some(lhs), Some(rhs))
292 PairParts::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::Catch(ref block) => {
321 if let rw @ Some(_) = rewrite_single_line_block(
332 let budget = shape.width.saturating_sub(9);
341 Shape::legacy(budget, shape.indent)
347 ast::ExprKind::ObsoleteInPlace(..) => unimplemented!(),
348 ast::ExprKind::Async(capture_by, _node_id, ref block) => {
349 let mover = if capture_by == ast::CaptureBy::Value {
354 if let rw @ Some(_) = rewrite_single_line_block(
356 format!("{}{}", "async ", mover).as_str(),
365 let budget = shape.width.saturating_sub(6);
375 Shape::legacy(budget, shape.indent)
383 .and_then(|expr_str| recover_comment_removed(expr_str, expr.span, context))
384 .and_then(|expr_str| {
385 let attrs = outer_attributes(&expr.attrs);
386 let attrs_str = attrs.rewrite(context, shape)?;
388 attrs.last().map_or(expr.span.lo(), |attr| attr.span.hi()),
391 combine_strs_with_missing_comments(context, &attrs_str, &expr_str, span, shape, false)
395 pub fn rewrite_array<T: Rewrite + Spanned + ToExpr>(
399 context: &RewriteContext,
401 force_separator_tactic: Option<SeparatorTactic>,
402 delim_token: Option<DelimToken>,
403 ) -> Option<String> {
404 overflow::rewrite_with_square_brackets(
410 force_separator_tactic,
415 fn rewrite_empty_block(
416 context: &RewriteContext,
418 attrs: Option<&[ast::Attribute]>,
419 label: Option<ast::Label>,
422 ) -> Option<String> {
423 let label_str = rewrite_label(label);
424 if attrs.map_or(false, |a| !inner_attributes(a).is_empty()) {
428 if block.stmts.is_empty()
429 && !block_contains_comment(block, context.source_map)
432 return Some(format!("{}{}{{}}", prefix, label_str));
435 // If a block contains only a single-line comment, then leave it on one line.
436 let user_str = context.snippet(block.span);
437 let user_str = user_str.trim();
438 if user_str.starts_with('{') && user_str.ends_with('}') {
439 let comment_str = user_str[1..user_str.len() - 1].trim();
440 if block.stmts.is_empty()
441 && !comment_str.contains('\n')
442 && !comment_str.starts_with("//")
443 && comment_str.len() + 4 <= shape.width
445 return Some(format!("{}{}{{ {} }}", prefix, label_str, comment_str));
452 fn block_prefix(context: &RewriteContext, block: &ast::Block, shape: Shape) -> Option<String> {
453 Some(match block.rules {
454 ast::BlockCheckMode::Unsafe(..) => {
455 let snippet = context.snippet(block.span);
456 let open_pos = snippet.find_uncommented("{")?;
457 // Extract comment between unsafe and block start.
458 let trimmed = &snippet[6..open_pos].trim();
460 if !trimmed.is_empty() {
461 // 9 = "unsafe {".len(), 7 = "unsafe ".len()
462 let budget = shape.width.checked_sub(9)?;
468 Shape::legacy(budget, shape.indent + 7),
476 ast::BlockCheckMode::Default => String::new(),
480 fn rewrite_single_line_block(
481 context: &RewriteContext,
484 attrs: Option<&[ast::Attribute]>,
485 label: Option<ast::Label>,
487 ) -> Option<String> {
488 if is_simple_block(block, attrs, context.source_map) {
489 let expr_shape = shape.offset_left(last_line_width(prefix))?;
490 let expr_str = block.stmts[0].rewrite(context, expr_shape)?;
491 let label_str = rewrite_label(label);
492 let result = format!("{}{}{{ {} }}", prefix, label_str, expr_str);
493 if result.len() <= shape.width && !result.contains('\n') {
500 pub fn rewrite_block_with_visitor(
501 context: &RewriteContext,
504 attrs: Option<&[ast::Attribute]>,
505 label: Option<ast::Label>,
508 ) -> Option<String> {
509 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, label, prefix, shape) {
513 let mut visitor = FmtVisitor::from_context(context);
514 visitor.block_indent = shape.indent;
515 visitor.is_if_else_block = context.is_if_else_block();
517 ast::BlockCheckMode::Unsafe(..) => {
518 let snippet = context.snippet(block.span);
519 let open_pos = snippet.find_uncommented("{")?;
520 visitor.last_pos = block.span.lo() + BytePos(open_pos as u32)
522 ast::BlockCheckMode::Default => visitor.last_pos = block.span.lo(),
525 let inner_attrs = attrs.map(inner_attributes);
526 let label_str = rewrite_label(label);
527 visitor.visit_block(block, inner_attrs.as_ref().map(|a| &**a), has_braces);
528 Some(format!("{}{}{}", prefix, label_str, visitor.buffer))
531 impl Rewrite for ast::Block {
532 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
533 rewrite_block(self, None, None, context, shape)
539 attrs: Option<&[ast::Attribute]>,
540 label: Option<ast::Label>,
541 context: &RewriteContext,
543 ) -> Option<String> {
544 let prefix = block_prefix(context, block, shape)?;
546 // shape.width is used only for the single line case: either the empty block `{}`,
547 // or an unsafe expression `unsafe { e }`.
548 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, label, &prefix, shape) {
552 let result = rewrite_block_with_visitor(context, &prefix, block, attrs, label, shape, true);
553 if let Some(ref result_str) = result {
554 if result_str.lines().count() <= 3 {
555 if let rw @ Some(_) =
556 rewrite_single_line_block(context, &prefix, block, attrs, label, shape)
566 impl Rewrite for ast::Stmt {
567 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
568 skip_out_of_file_lines_range!(context, self.span());
570 let result = match self.node {
571 ast::StmtKind::Local(ref local) => local.rewrite(context, shape),
572 ast::StmtKind::Expr(ref ex) | ast::StmtKind::Semi(ref ex) => {
573 let suffix = if semicolon_for_stmt(context, self) {
579 let shape = shape.sub_width(suffix.len())?;
580 format_expr(ex, ExprType::Statement, context, shape).map(|s| s + suffix)
582 ast::StmtKind::Mac(..) | ast::StmtKind::Item(..) => None,
584 result.and_then(|res| recover_comment_removed(res, self.span(), context))
588 // Rewrite condition if the given expression has one.
589 pub fn rewrite_cond(context: &RewriteContext, expr: &ast::Expr, shape: Shape) -> Option<String> {
591 ast::ExprKind::Match(ref cond, _) => {
593 let cond_shape = match context.config.indent_style() {
594 IndentStyle::Visual => shape.shrink_left(6).and_then(|s| s.sub_width(2))?,
595 IndentStyle::Block => shape.offset_left(8)?,
597 cond.rewrite(context, cond_shape)
599 _ => to_control_flow(expr, ExprType::SubExpression).and_then(|control_flow| {
601 String::from("\n") + &shape.indent.block_only().to_string(context.config);
603 .rewrite_cond(context, shape, &alt_block_sep)
604 .and_then(|rw| Some(rw.0))
609 // Abstraction over control flow expressions
611 struct ControlFlow<'a> {
612 cond: Option<&'a ast::Expr>,
613 block: &'a ast::Block,
614 else_block: Option<&'a ast::Expr>,
615 label: Option<ast::Label>,
616 pats: Vec<&'a ast::Pat>,
620 allow_single_line: bool,
621 // True if this is an `if` expression in an `else if` :-( hacky
626 fn to_control_flow(expr: &ast::Expr, expr_type: ExprType) -> Option<ControlFlow> {
628 ast::ExprKind::If(ref cond, ref if_block, ref else_block) => Some(ControlFlow::new_if(
632 else_block.as_ref().map(|e| &**e),
633 expr_type == ExprType::SubExpression,
637 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref else_block) => {
638 Some(ControlFlow::new_if(
640 ptr_vec_to_ref_vec(pat),
642 else_block.as_ref().map(|e| &**e),
643 expr_type == ExprType::SubExpression,
648 ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
649 Some(ControlFlow::new_for(pat, cond, block, label, expr.span))
651 ast::ExprKind::Loop(ref block, label) => {
652 Some(ControlFlow::new_loop(block, label, expr.span))
654 ast::ExprKind::While(ref cond, ref block, label) => Some(ControlFlow::new_while(
661 ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => Some(
662 ControlFlow::new_while(ptr_vec_to_ref_vec(pat), cond, block, label, expr.span),
668 fn choose_matcher(pats: &[&ast::Pat]) -> &'static str {
676 impl<'a> ControlFlow<'a> {
679 pats: Vec<&'a ast::Pat>,
680 block: &'a ast::Block,
681 else_block: Option<&'a ast::Expr>,
682 allow_single_line: bool,
685 ) -> ControlFlow<'a> {
686 let matcher = choose_matcher(&pats);
702 fn new_loop(block: &'a ast::Block, label: Option<ast::Label>, span: Span) -> ControlFlow<'a> {
712 allow_single_line: false,
719 pats: Vec<&'a ast::Pat>,
721 block: &'a ast::Block,
722 label: Option<ast::Label>,
724 ) -> ControlFlow<'a> {
725 let matcher = choose_matcher(&pats);
735 allow_single_line: false,
744 block: &'a ast::Block,
745 label: Option<ast::Label>,
747 ) -> ControlFlow<'a> {
757 allow_single_line: false,
763 fn rewrite_single_line(
766 context: &RewriteContext,
768 ) -> Option<String> {
769 assert!(self.allow_single_line);
770 let else_block = self.else_block?;
771 let fixed_cost = self.keyword.len() + " { } else { }".len();
773 if let ast::ExprKind::Block(ref else_node, _) = else_block.node {
774 if !is_simple_block(self.block, None, context.source_map)
775 || !is_simple_block(else_node, None, context.source_map)
776 || pat_expr_str.contains('\n')
781 let new_width = width.checked_sub(pat_expr_str.len() + fixed_cost)?;
782 let expr = &self.block.stmts[0];
783 let if_str = expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
785 let new_width = new_width.checked_sub(if_str.len())?;
786 let else_expr = &else_node.stmts[0];
787 let else_str = else_expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
789 if if_str.contains('\n') || else_str.contains('\n') {
793 let result = format!(
794 "{} {} {{ {} }} else {{ {} }}",
795 self.keyword, pat_expr_str, if_str, else_str
798 if result.len() <= width {
807 impl<'a> ControlFlow<'a> {
810 context: &RewriteContext,
814 ) -> Option<String> {
815 debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, self.pats, expr);
817 let cond_shape = shape.offset_left(offset)?;
818 if !self.pats.is_empty() {
819 let matcher = if self.matcher.is_empty() {
820 self.matcher.to_owned()
822 format!("{} ", self.matcher)
824 let pat_shape = cond_shape
825 .offset_left(matcher.len())?
826 .sub_width(self.connector.len())?;
827 let pat_string = rewrite_multiple_patterns(context, &self.pats, pat_shape)?;
828 let result = format!("{}{}{}", matcher, pat_string, self.connector);
829 return rewrite_assign_rhs(context, result, expr, cond_shape);
832 let expr_rw = expr.rewrite(context, cond_shape);
833 // The expression may (partially) fit on the current line.
834 // We do not allow splitting between `if` and condition.
835 if self.keyword == "if" || expr_rw.is_some() {
839 // The expression won't fit on the current line, jump to next.
840 let nested_shape = shape
841 .block_indent(context.config.tab_spaces())
842 .with_max_width(context.config);
843 let nested_indent_str = nested_shape.indent.to_string_with_newline(context.config);
844 expr.rewrite(context, nested_shape)
845 .map(|expr_rw| format!("{}{}", nested_indent_str, expr_rw))
850 context: &RewriteContext,
853 ) -> Option<(String, usize)> {
854 // Do not take the rhs overhead from the upper expressions into account
855 // when rewriting pattern.
856 let new_width = context.budget(shape.used_width());
857 let fresh_shape = Shape {
861 let constr_shape = if self.nested_if {
862 // We are part of an if-elseif-else chain. Our constraints are tightened.
863 // 7 = "} else " .len()
864 fresh_shape.offset_left(7)?
869 let label_string = rewrite_label(self.label);
870 // 1 = space after keyword.
871 let offset = self.keyword.len() + label_string.len() + 1;
873 let pat_expr_string = match self.cond {
874 Some(cond) => self.rewrite_pat_expr(context, cond, constr_shape, offset)?,
875 None => String::new(),
879 if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
885 let one_line_budget = context
888 .saturating_sub(constr_shape.used_width() + offset + brace_overhead);
889 let force_newline_brace = (pat_expr_string.contains('\n')
890 || pat_expr_string.len() > one_line_budget)
891 && !last_line_extendable(&pat_expr_string);
893 // Try to format if-else on single line.
894 if self.allow_single_line
898 .single_line_if_else_max_width
901 let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width);
903 if let Some(cond_str) = trial {
904 if cond_str.len() <= context
907 .single_line_if_else_max_width
909 return Some((cond_str, 0));
914 let cond_span = if let Some(cond) = self.cond {
917 mk_sp(self.block.span.lo(), self.block.span.lo())
920 // `for event in event`
921 // Do not include label in the span.
924 .map_or(self.span.lo(), |label| label.ident.span.hi());
925 let between_kwd_cond = mk_sp(
928 .span_after(mk_sp(lo, self.span.hi()), self.keyword.trim()),
929 if self.pats.is_empty() {
931 } else if self.matcher.is_empty() {
932 self.pats[0].span.lo()
936 .span_before(self.span, self.matcher.trim())
940 let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape);
942 let after_cond_comment =
943 extract_comment(mk_sp(cond_span.hi(), self.block.span.lo()), context, shape);
945 let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
947 } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine
948 || force_newline_brace
955 let used_width = if pat_expr_string.contains('\n') {
956 last_line_width(&pat_expr_string)
958 // 2 = spaces after keyword and condition.
959 label_string.len() + self.keyword.len() + pat_expr_string.len() + 2
967 between_kwd_cond_comment.as_ref().map_or(
968 if pat_expr_string.is_empty() || pat_expr_string.starts_with('\n') {
976 after_cond_comment.as_ref().map_or(block_sep, |s| &**s)
983 impl<'a> Rewrite for ControlFlow<'a> {
984 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
985 debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
987 let alt_block_sep = &shape.indent.to_string_with_newline(context.config);
988 let (cond_str, used_width) = self.rewrite_cond(context, shape, alt_block_sep)?;
989 // If `used_width` is 0, it indicates that whole control flow is written in a single line.
991 return Some(cond_str);
994 let block_width = shape.width.saturating_sub(used_width);
995 // This is used only for the empty block case: `{}`. So, we use 1 if we know
996 // we should avoid the single line case.
997 let block_width = if self.else_block.is_some() || self.nested_if {
1002 let block_shape = Shape {
1007 let old_val = context.is_if_else_block.replace(self.else_block.is_some());
1009 rewrite_block_with_visitor(context, "", self.block, None, None, block_shape, true);
1010 context.is_if_else_block.replace(old_val);
1014 let mut result = format!("{}{}", cond_str, block_str);
1016 if let Some(else_block) = self.else_block {
1017 let shape = Shape::indented(shape.indent, context.config);
1018 let mut last_in_chain = false;
1019 let rewrite = match else_block.node {
1020 // If the else expression is another if-else expression, prevent it
1021 // from being formatted on a single line.
1022 // Note how we're passing the original shape, as the
1023 // cost of "else" should not cascade.
1024 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref next_else_block) => {
1025 ControlFlow::new_if(
1027 ptr_vec_to_ref_vec(pat),
1029 next_else_block.as_ref().map(|e| &**e),
1032 mk_sp(else_block.span.lo(), self.span.hi()),
1033 ).rewrite(context, shape)
1035 ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => {
1036 ControlFlow::new_if(
1040 next_else_block.as_ref().map(|e| &**e),
1043 mk_sp(else_block.span.lo(), self.span.hi()),
1044 ).rewrite(context, shape)
1047 last_in_chain = true;
1048 // When rewriting a block, the width is only used for single line
1049 // blocks, passing 1 lets us avoid that.
1050 let else_shape = Shape {
1051 width: min(1, shape.width),
1054 format_expr(else_block, ExprType::Statement, context, else_shape)
1058 let between_kwd_else_block = mk_sp(
1059 self.block.span.hi(),
1062 .span_before(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1064 let between_kwd_else_block_comment =
1065 extract_comment(between_kwd_else_block, context, shape);
1067 let after_else = mk_sp(
1070 .span_after(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1071 else_block.span.lo(),
1073 let after_else_comment = extract_comment(after_else, context, shape);
1075 let between_sep = match context.config.control_brace_style() {
1076 ControlBraceStyle::AlwaysNextLine | ControlBraceStyle::ClosingNextLine => {
1079 ControlBraceStyle::AlwaysSameLine => " ",
1081 let after_sep = match context.config.control_brace_style() {
1082 ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep,
1086 result.push_str(&format!(
1088 between_kwd_else_block_comment
1090 .map_or(between_sep, |s| &**s),
1091 after_else_comment.as_ref().map_or(after_sep, |s| &**s),
1093 result.push_str(&rewrite?);
1100 fn rewrite_label(opt_label: Option<ast::Label>) -> Cow<'static, str> {
1102 Some(label) => Cow::from(format!("{}: ", label.ident)),
1103 None => Cow::from(""),
1107 fn extract_comment(span: Span, context: &RewriteContext, shape: Shape) -> Option<String> {
1108 match rewrite_missing_comment(span, shape, context) {
1109 Some(ref comment) if !comment.is_empty() => Some(format!(
1110 "{indent}{}{indent}",
1112 indent = shape.indent.to_string_with_newline(context.config)
1118 pub fn block_contains_comment(block: &ast::Block, source_map: &SourceMap) -> bool {
1119 let snippet = source_map.span_to_snippet(block.span).unwrap();
1120 contains_comment(&snippet)
1123 // Checks that a block contains no statements, an expression and no comments or
1125 // FIXME: incorrectly returns false when comment is contained completely within
1127 pub fn is_simple_block(
1129 attrs: Option<&[ast::Attribute]>,
1130 source_map: &SourceMap,
1132 (block.stmts.len() == 1
1133 && stmt_is_expr(&block.stmts[0])
1134 && !block_contains_comment(block, source_map)
1135 && attrs.map_or(true, |a| a.is_empty()))
1138 /// Checks whether a block contains at most one statement or expression, and no
1139 /// comments or attributes.
1140 pub fn is_simple_block_stmt(
1142 attrs: Option<&[ast::Attribute]>,
1143 source_map: &SourceMap,
1145 block.stmts.len() <= 1
1146 && !block_contains_comment(block, source_map)
1147 && attrs.map_or(true, |a| a.is_empty())
1150 /// Checks whether a block contains no statements, expressions, comments, or
1151 /// inner attributes.
1152 pub fn is_empty_block(
1154 attrs: Option<&[ast::Attribute]>,
1155 source_map: &SourceMap,
1157 block.stmts.is_empty()
1158 && !block_contains_comment(block, source_map)
1159 && attrs.map_or(true, |a| inner_attributes(a).is_empty())
1162 pub fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
1164 ast::StmtKind::Expr(..) => true,
1169 pub fn is_unsafe_block(block: &ast::Block) -> bool {
1170 if let ast::BlockCheckMode::Unsafe(..) = block.rules {
1177 pub fn rewrite_multiple_patterns(
1178 context: &RewriteContext,
1181 ) -> Option<String> {
1184 .map(|p| p.rewrite(context, shape))
1185 .collect::<Option<Vec<_>>>()?;
1187 let use_mixed_layout = pats
1189 .zip(pat_strs.iter())
1190 .all(|(pat, pat_str)| is_short_pattern(pat, pat_str));
1191 let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
1192 let tactic = if use_mixed_layout {
1193 DefinitiveListTactic::Mixed
1197 ListTactic::HorizontalVertical,
1198 Separator::VerticalBar,
1202 let fmt = ListFormatting::new(shape, context.config)
1205 .separator_place(context.config.binop_separator())
1206 .ends_with_newline(false);
1207 write_list(&items, &fmt)
1210 pub fn rewrite_literal(context: &RewriteContext, l: &ast::Lit, shape: Shape) -> Option<String> {
1212 ast::LitKind::Str(_, ast::StrStyle::Cooked) => rewrite_string_lit(context, l.span, shape),
1214 context.snippet(l.span).to_owned(),
1215 context.config.max_width(),
1221 fn rewrite_string_lit(context: &RewriteContext, span: Span, shape: Shape) -> Option<String> {
1222 let string_lit = context.snippet(span);
1224 if !context.config.format_strings() {
1229 .all(|line| line.ends_with('\\'))
1231 let new_indent = shape.visual_indent(1).indent;
1232 let indented_string_lit = String::from(
1238 new_indent.to_string(context.config),
1241 }).collect::<Vec<_>>()
1245 return wrap_str(indented_string_lit, context.config.max_width(), shape);
1247 return wrap_str(string_lit.to_owned(), context.config.max_width(), shape);
1251 // Remove the quote characters.
1252 let str_lit = &string_lit[1..string_lit.len() - 1];
1256 &StringFormat::new(shape.visual_indent(0), context.config),
1260 /// In case special-case style is required, returns an offset from which we start horizontal layout.
1261 pub fn maybe_get_args_offset<T: ToExpr>(callee_str: &str, args: &[&T]) -> Option<(bool, usize)> {
1262 if let Some(&(_, num_args_before)) = SPECIAL_MACRO_WHITELIST
1264 .find(|&&(s, _)| s == callee_str)
1266 let all_simple = args.len() > num_args_before && is_every_expr_simple(args);
1268 Some((all_simple, num_args_before))
1274 /// A list of `format!`-like macros, that take a long format string and a list of arguments to
1277 /// Organized as a list of `(&str, usize)` tuples, giving the name of the macro and the number of
1278 /// arguments before the format string (none for `format!("format", ...)`, one for `assert!(result,
1279 /// "format", ...)`, two for `assert_eq!(left, right, "format", ...)`).
1280 const SPECIAL_MACRO_WHITELIST: &[(&str, usize)] = &[
1281 // format! like macros
1282 // From the Rust Standard Library.
1286 ("format_args!", 0),
1290 ("unreachable!", 0),
1291 // From the `log` crate.
1296 // write! like macros
1298 ("debug_assert!", 1),
1301 // assert_eq! like macros
1304 ("debug_assert_eq!", 2),
1305 ("debug_assert_ne!", 2),
1308 fn choose_separator_tactic(context: &RewriteContext, span: Span) -> Option<SeparatorTactic> {
1309 if context.inside_macro() {
1310 if span_ends_with_comma(context, span) {
1311 Some(SeparatorTactic::Always)
1313 Some(SeparatorTactic::Never)
1320 pub fn rewrite_call(
1321 context: &RewriteContext,
1323 args: &[ptr::P<ast::Expr>],
1326 ) -> Option<String> {
1327 overflow::rewrite_with_parens(
1330 &ptr_vec_to_ref_vec(args),
1333 context.config.width_heuristics().fn_call_width,
1334 choose_separator_tactic(context, span),
1338 fn is_simple_expr(expr: &ast::Expr) -> bool {
1340 ast::ExprKind::Lit(..) => true,
1341 ast::ExprKind::Path(ref qself, ref path) => qself.is_none() && path.segments.len() <= 1,
1342 ast::ExprKind::AddrOf(_, ref expr)
1343 | ast::ExprKind::Box(ref expr)
1344 | ast::ExprKind::Cast(ref expr, _)
1345 | ast::ExprKind::Field(ref expr, _)
1346 | ast::ExprKind::Try(ref expr)
1347 | ast::ExprKind::Unary(_, ref expr) => is_simple_expr(expr),
1348 ast::ExprKind::Index(ref lhs, ref rhs) => is_simple_expr(lhs) && is_simple_expr(rhs),
1349 ast::ExprKind::Repeat(ref lhs, ref rhs) => {
1350 is_simple_expr(lhs) && is_simple_expr(&*rhs.value)
1356 pub fn is_every_expr_simple<T: ToExpr>(lists: &[&T]) -> bool {
1359 .all(|arg| arg.to_expr().map_or(false, is_simple_expr))
1362 pub fn can_be_overflowed_expr(context: &RewriteContext, expr: &ast::Expr, args_len: usize) -> bool {
1364 ast::ExprKind::Match(..) => {
1365 (context.use_block_indent() && args_len == 1)
1366 || (context.config.indent_style() == IndentStyle::Visual && args_len > 1)
1368 ast::ExprKind::If(..)
1369 | ast::ExprKind::IfLet(..)
1370 | ast::ExprKind::ForLoop(..)
1371 | ast::ExprKind::Loop(..)
1372 | ast::ExprKind::While(..)
1373 | ast::ExprKind::WhileLet(..) => {
1374 context.config.combine_control_expr() && context.use_block_indent() && args_len == 1
1376 ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => {
1377 context.use_block_indent()
1378 || context.config.indent_style() == IndentStyle::Visual && args_len > 1
1380 ast::ExprKind::Array(..)
1381 | ast::ExprKind::Call(..)
1382 | ast::ExprKind::Mac(..)
1383 | ast::ExprKind::MethodCall(..)
1384 | ast::ExprKind::Struct(..)
1385 | ast::ExprKind::Tup(..) => context.use_block_indent() && args_len == 1,
1386 ast::ExprKind::AddrOf(_, ref expr)
1387 | ast::ExprKind::Box(ref expr)
1388 | ast::ExprKind::Try(ref expr)
1389 | ast::ExprKind::Unary(_, ref expr)
1390 | ast::ExprKind::Cast(ref expr, _) => can_be_overflowed_expr(context, expr, args_len),
1395 pub fn is_nested_call(expr: &ast::Expr) -> bool {
1397 ast::ExprKind::Call(..) | ast::ExprKind::Mac(..) => true,
1398 ast::ExprKind::AddrOf(_, ref expr)
1399 | ast::ExprKind::Box(ref expr)
1400 | ast::ExprKind::Try(ref expr)
1401 | ast::ExprKind::Unary(_, ref expr)
1402 | ast::ExprKind::Cast(ref expr, _) => is_nested_call(expr),
1407 /// Return true if a function call or a method call represented by the given span ends with a
1408 /// trailing comma. This function is used when rewriting macro, as adding or removing a trailing
1409 /// comma from macro can potentially break the code.
1410 pub fn span_ends_with_comma(context: &RewriteContext, span: Span) -> bool {
1411 let mut result: bool = Default::default();
1412 let mut prev_char: char = Default::default();
1413 let closing_delimiters = &[')', '}', ']'];
1415 for (kind, c) in CharClasses::new(context.snippet(span).chars()) {
1417 _ if kind.is_comment() || c.is_whitespace() => continue,
1418 c if closing_delimiters.contains(&c) => {
1419 result &= !closing_delimiters.contains(&prev_char);
1421 ',' => result = true,
1422 _ => result = false,
1431 context: &RewriteContext,
1432 mut subexpr: &ast::Expr,
1435 ) -> Option<String> {
1436 debug!("rewrite_paren, shape: {:?}", shape);
1438 // Extract comments within parens.
1439 let mut pre_comment;
1440 let mut post_comment;
1441 let remove_nested_parens = context.config.remove_nested_parens();
1444 let pre_span = mk_sp(span.lo() + BytePos(1), subexpr.span.lo());
1445 let post_span = mk_sp(subexpr.span.hi(), span.hi() - BytePos(1));
1446 pre_comment = rewrite_missing_comment(pre_span, shape, context)?;
1447 post_comment = rewrite_missing_comment(post_span, shape, context)?;
1449 // Remove nested parens if there are no comments.
1450 if let ast::ExprKind::Paren(ref subsubexpr) = subexpr.node {
1451 if remove_nested_parens && pre_comment.is_empty() && post_comment.is_empty() {
1452 span = subexpr.span;
1453 subexpr = subsubexpr;
1462 let sub_shape = shape.offset_left(1).and_then(|s| s.sub_width(1))?;
1464 let subexpr_str = subexpr.rewrite(context, sub_shape)?;
1465 debug!("rewrite_paren, subexpr_str: `{:?}`", subexpr_str);
1468 if subexpr_str.contains('\n') || first_line_width(&subexpr_str) + 2 <= shape.width {
1469 Some(format!("({}{}{})", pre_comment, &subexpr_str, post_comment))
1478 context: &RewriteContext,
1480 ) -> Option<String> {
1481 let expr_str = expr.rewrite(context, shape)?;
1483 let offset = last_line_width(&expr_str) + 1;
1484 let rhs_overhead = shape.rhs_overhead(context.config);
1485 let index_shape = if expr_str.contains('\n') {
1486 Shape::legacy(context.config.max_width(), shape.indent)
1487 .offset_left(offset)
1488 .and_then(|shape| shape.sub_width(1 + rhs_overhead))
1490 shape.visual_indent(offset).sub_width(offset + 1)
1492 let orig_index_rw = index_shape.and_then(|s| index.rewrite(context, s));
1494 // Return if index fits in a single line.
1495 match orig_index_rw {
1496 Some(ref index_str) if !index_str.contains('\n') => {
1497 return Some(format!("{}[{}]", expr_str, index_str));
1502 // Try putting index on the next line and see if it fits in a single line.
1503 let indent = shape.indent.block_indent(context.config);
1504 let index_shape = Shape::indented(indent, context.config).offset_left(1)?;
1505 let index_shape = index_shape.sub_width(1 + rhs_overhead)?;
1506 let new_index_rw = index.rewrite(context, index_shape);
1507 match (orig_index_rw, new_index_rw) {
1508 (_, Some(ref new_index_str)) if !new_index_str.contains('\n') => Some(format!(
1511 indent.to_string_with_newline(context.config),
1514 (None, Some(ref new_index_str)) => Some(format!(
1517 indent.to_string_with_newline(context.config),
1520 (Some(ref index_str), _) => Some(format!("{}[{}]", expr_str, index_str)),
1525 fn struct_lit_can_be_aligned(fields: &[ast::Field], base: &Option<&ast::Expr>) -> bool {
1530 fields.iter().all(|field| !field.is_shorthand)
1533 fn rewrite_struct_lit<'a>(
1534 context: &RewriteContext,
1536 fields: &'a [ast::Field],
1537 base: Option<&'a ast::Expr>,
1540 ) -> Option<String> {
1541 debug!("rewrite_struct_lit: shape {:?}", shape);
1543 enum StructLitField<'a> {
1544 Regular(&'a ast::Field),
1545 Base(&'a ast::Expr),
1549 let path_shape = shape.sub_width(2)?;
1550 let path_str = rewrite_path(context, PathContext::Expr, None, path, path_shape)?;
1552 if fields.is_empty() && base.is_none() {
1553 return Some(format!("{} {{}}", path_str));
1556 // Foo { a: Foo } - indent is +3, width is -5.
1557 let (h_shape, v_shape) = struct_lit_shape(shape, context, path_str.len() + 3, 2)?;
1559 let one_line_width = h_shape.map_or(0, |shape| shape.width);
1560 let body_lo = context.snippet_provider.span_after(span, "{");
1561 let fields_str = if struct_lit_can_be_aligned(fields, &base)
1562 && context.config.struct_field_align_threshold() > 0
1564 rewrite_with_alignment(
1568 mk_sp(body_lo, span.hi()),
1572 let field_iter = fields
1574 .map(StructLitField::Regular)
1575 .chain(base.into_iter().map(StructLitField::Base));
1577 let span_lo = |item: &StructLitField| match *item {
1578 StructLitField::Regular(field) => field.span().lo(),
1579 StructLitField::Base(expr) => {
1580 let last_field_hi = fields.last().map_or(span.lo(), |field| field.span.hi());
1581 let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo()));
1582 let pos = snippet.find_uncommented("..").unwrap();
1583 last_field_hi + BytePos(pos as u32)
1586 let span_hi = |item: &StructLitField| match *item {
1587 StructLitField::Regular(field) => field.span().hi(),
1588 StructLitField::Base(expr) => expr.span.hi(),
1590 let rewrite = |item: &StructLitField| match *item {
1591 StructLitField::Regular(field) => {
1592 // The 1 taken from the v_budget is for the comma.
1593 rewrite_field(context, field, v_shape.sub_width(1)?, 0)
1595 StructLitField::Base(expr) => {
1597 expr.rewrite(context, v_shape.offset_left(2)?)
1598 .map(|s| format!("..{}", s))
1602 let items = itemize_list(
1603 context.snippet_provider,
1614 let item_vec = items.collect::<Vec<_>>();
1616 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
1617 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
1619 let ends_with_comma = span_ends_with_comma(context, span);
1620 let force_no_trailing_comma = context.inside_macro() && !ends_with_comma;
1622 let fmt = struct_lit_formatting(
1626 force_no_trailing_comma || base.is_some(),
1629 write_list(&item_vec, &fmt)?
1632 let fields_str = wrap_struct_field(context, &fields_str, shape, v_shape, one_line_width);
1633 Some(format!("{} {{{}}}", path_str, fields_str))
1635 // FIXME if context.config.indent_style() == Visual, but we run out
1636 // of space, we should fall back to BlockIndent.
1639 pub fn wrap_struct_field(
1640 context: &RewriteContext,
1643 nested_shape: Shape,
1644 one_line_width: usize,
1646 if context.config.indent_style() == IndentStyle::Block
1647 && (fields_str.contains('\n')
1648 || !context.config.struct_lit_single_line()
1649 || fields_str.len() > one_line_width)
1653 nested_shape.indent.to_string_with_newline(context.config),
1655 shape.indent.to_string_with_newline(context.config)
1658 // One liner or visual indent.
1659 format!(" {} ", fields_str)
1663 pub fn struct_lit_field_separator(config: &Config) -> &str {
1664 colon_spaces(config.space_before_colon(), config.space_after_colon())
1667 pub fn rewrite_field(
1668 context: &RewriteContext,
1671 prefix_max_width: usize,
1672 ) -> Option<String> {
1673 if contains_skip(&field.attrs) {
1674 return Some(context.snippet(field.span()).to_owned());
1676 let mut attrs_str = field.attrs.rewrite(context, shape)?;
1677 if !attrs_str.is_empty() {
1678 attrs_str.push_str(&shape.indent.to_string_with_newline(context.config));
1680 let name = context.snippet(field.ident.span);
1681 if field.is_shorthand {
1682 Some(attrs_str + &name)
1684 let mut separator = String::from(struct_lit_field_separator(context.config));
1685 for _ in 0..prefix_max_width.saturating_sub(name.len()) {
1686 separator.push(' ');
1688 let overhead = name.len() + separator.len();
1689 let expr_shape = shape.offset_left(overhead)?;
1690 let expr = field.expr.rewrite(context, expr_shape);
1693 Some(ref e) if e.as_str() == name && context.config.use_field_init_shorthand() => {
1694 Some(attrs_str + &name)
1696 Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)),
1698 let expr_offset = shape.indent.block_indent(context.config);
1701 .rewrite(context, Shape::indented(expr_offset, context.config));
1707 expr_offset.to_string(context.config),
1716 fn rewrite_tuple_in_visual_indent_style<'a, T>(
1717 context: &RewriteContext,
1723 T: Rewrite + Spanned + ToExpr + 'a,
1725 let mut items = items.iter();
1726 // In case of length 1, need a trailing comma
1727 debug!("rewrite_tuple_in_visual_indent_style {:?}", shape);
1728 if items.len() == 1 {
1730 let nested_shape = shape.sub_width(3)?.visual_indent(1);
1734 .rewrite(context, nested_shape)
1735 .map(|s| format!("({},)", s));
1738 let list_lo = context.snippet_provider.span_after(span, "(");
1739 let nested_shape = shape.sub_width(2)?.visual_indent(1);
1740 let items = itemize_list(
1741 context.snippet_provider,
1745 |item| item.span().lo(),
1746 |item| item.span().hi(),
1747 |item| item.rewrite(context, nested_shape),
1749 span.hi() - BytePos(1),
1752 let item_vec: Vec<_> = items.collect();
1753 let tactic = definitive_tactic(
1755 ListTactic::HorizontalVertical,
1759 let fmt = ListFormatting::new(shape, context.config)
1761 .ends_with_newline(false);
1762 let list_str = write_list(&item_vec, &fmt)?;
1764 Some(format!("({})", list_str))
1767 pub fn rewrite_tuple<'a, T>(
1768 context: &RewriteContext,
1774 T: Rewrite + Spanned + ToExpr + 'a,
1776 debug!("rewrite_tuple {:?}", shape);
1777 if context.use_block_indent() {
1778 // We use the same rule as function calls for rewriting tuples.
1779 let force_tactic = if context.inside_macro() {
1780 if span_ends_with_comma(context, span) {
1781 Some(SeparatorTactic::Always)
1783 Some(SeparatorTactic::Never)
1785 } else if items.len() == 1 {
1786 Some(SeparatorTactic::Always)
1790 overflow::rewrite_with_parens(
1796 context.config.width_heuristics().fn_call_width,
1800 rewrite_tuple_in_visual_indent_style(context, items, span, shape)
1804 pub fn rewrite_unary_prefix<R: Rewrite>(
1805 context: &RewriteContext,
1809 ) -> Option<String> {
1811 .rewrite(context, shape.offset_left(prefix.len())?)
1812 .map(|r| format!("{}{}", prefix, r))
1815 // FIXME: this is probably not correct for multi-line Rewrites. we should
1816 // subtract suffix.len() from the last line budget, not the first!
1817 pub fn rewrite_unary_suffix<R: Rewrite>(
1818 context: &RewriteContext,
1822 ) -> Option<String> {
1824 .rewrite(context, shape.sub_width(suffix.len())?)
1831 fn rewrite_unary_op(
1832 context: &RewriteContext,
1836 ) -> Option<String> {
1837 // For some reason, an UnOp is not spanned like BinOp!
1838 let operator_str = match *op {
1839 ast::UnOp::Deref => "*",
1840 ast::UnOp::Not => "!",
1841 ast::UnOp::Neg => "-",
1843 rewrite_unary_prefix(context, operator_str, expr, shape)
1846 fn rewrite_assignment(
1847 context: &RewriteContext,
1850 op: Option<&ast::BinOp>,
1852 ) -> Option<String> {
1853 let operator_str = match op {
1854 Some(op) => context.snippet(op.span),
1858 // 1 = space between lhs and operator.
1859 let lhs_shape = shape.sub_width(operator_str.len() + 1)?;
1860 let lhs_str = format!("{} {}", lhs.rewrite(context, lhs_shape)?, operator_str);
1862 rewrite_assign_rhs(context, lhs_str, rhs, shape)
1865 /// Controls where to put the rhs.
1866 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
1867 pub enum RhsTactics {
1870 /// Put the rhs on the next line if it uses multiple line, without extra indentation.
1871 ForceNextLineWithoutIndent,
1874 // The left hand side must contain everything up to, and including, the
1875 // assignment operator.
1876 pub fn rewrite_assign_rhs<S: Into<String>, R: Rewrite>(
1877 context: &RewriteContext,
1881 ) -> Option<String> {
1882 rewrite_assign_rhs_with(context, lhs, ex, shape, RhsTactics::Default)
1885 pub fn rewrite_assign_rhs_with<S: Into<String>, R: Rewrite>(
1886 context: &RewriteContext,
1890 rhs_tactics: RhsTactics,
1891 ) -> Option<String> {
1892 let lhs = lhs.into();
1893 let last_line_width = last_line_width(&lhs).saturating_sub(if lhs.contains('\n') {
1894 shape.indent.width()
1898 // 1 = space between operator and rhs.
1899 let orig_shape = shape.offset_left(last_line_width + 1).unwrap_or(Shape {
1901 offset: shape.offset + last_line_width + 1,
1904 let rhs = choose_rhs(
1908 ex.rewrite(context, orig_shape),
1914 fn choose_rhs<R: Rewrite>(
1915 context: &RewriteContext,
1918 orig_rhs: Option<String>,
1919 rhs_tactics: RhsTactics,
1920 ) -> Option<String> {
1922 Some(ref new_str) if !new_str.contains('\n') && new_str.len() <= shape.width => {
1923 Some(format!(" {}", new_str))
1926 // Expression did not fit on the same line as the identifier.
1927 // Try splitting the line and see if that works better.
1928 let new_shape = shape_from_rhs_tactic(context, shape, rhs_tactics)?;
1929 let new_rhs = expr.rewrite(context, new_shape);
1930 let new_indent_str = &shape
1932 .block_indent(context.config)
1933 .to_string_with_newline(context.config);
1935 match (orig_rhs, new_rhs) {
1936 (Some(ref orig_rhs), Some(ref new_rhs))
1937 if wrap_str(new_rhs.clone(), context.config.max_width(), new_shape)
1940 Some(format!(" {}", orig_rhs))
1942 (Some(ref orig_rhs), Some(ref new_rhs))
1943 if prefer_next_line(orig_rhs, new_rhs, rhs_tactics) =>
1945 Some(format!("{}{}", new_indent_str, new_rhs))
1947 (None, Some(ref new_rhs)) => Some(format!("{}{}", new_indent_str, new_rhs)),
1948 (None, None) => None,
1949 (Some(orig_rhs), _) => Some(format!(" {}", orig_rhs)),
1955 fn shape_from_rhs_tactic(
1956 context: &RewriteContext,
1958 rhs_tactic: RhsTactics,
1959 ) -> Option<Shape> {
1961 RhsTactics::ForceNextLineWithoutIndent => Some(shape.with_max_width(context.config)),
1962 RhsTactics::Default => {
1963 Shape::indented(shape.indent.block_indent(context.config), context.config)
1964 .sub_width(shape.rhs_overhead(context.config))
1969 pub fn prefer_next_line(orig_rhs: &str, next_line_rhs: &str, rhs_tactics: RhsTactics) -> bool {
1970 rhs_tactics == RhsTactics::ForceNextLineWithoutIndent
1971 || !next_line_rhs.contains('\n')
1972 || count_newlines(orig_rhs) > count_newlines(next_line_rhs) + 1
1973 || first_line_ends_with(orig_rhs, '(') && !first_line_ends_with(next_line_rhs, '(')
1974 || first_line_ends_with(orig_rhs, '{') && !first_line_ends_with(next_line_rhs, '{')
1975 || first_line_ends_with(orig_rhs, '[') && !first_line_ends_with(next_line_rhs, '[')
1978 fn rewrite_expr_addrof(
1979 context: &RewriteContext,
1980 mutability: ast::Mutability,
1983 ) -> Option<String> {
1984 let operator_str = match mutability {
1985 ast::Mutability::Immutable => "&",
1986 ast::Mutability::Mutable => "&mut ",
1988 rewrite_unary_prefix(context, operator_str, expr, shape)
1992 fn to_expr(&self) -> Option<&ast::Expr>;
1993 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool;
1996 impl ToExpr for ast::Expr {
1997 fn to_expr(&self) -> Option<&ast::Expr> {
2001 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2002 can_be_overflowed_expr(context, self, len)
2006 impl ToExpr for ast::Ty {
2007 fn to_expr(&self) -> Option<&ast::Expr> {
2011 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2012 can_be_overflowed_type(context, self, len)
2016 impl<'a> ToExpr for TuplePatField<'a> {
2017 fn to_expr(&self) -> Option<&ast::Expr> {
2021 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2022 can_be_overflowed_pat(context, self, len)
2026 impl<'a> ToExpr for ast::StructField {
2027 fn to_expr(&self) -> Option<&ast::Expr> {
2031 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {
2036 impl<'a> ToExpr for MacroArg {
2037 fn to_expr(&self) -> Option<&ast::Expr> {
2039 MacroArg::Expr(ref expr) => Some(expr),
2044 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2046 MacroArg::Expr(ref expr) => can_be_overflowed_expr(context, expr, len),
2047 MacroArg::Ty(ref ty) => can_be_overflowed_type(context, ty, len),
2048 MacroArg::Pat(..) => false,
2049 MacroArg::Item(..) => len == 1,
2054 impl ToExpr for ast::GenericParam {
2055 fn to_expr(&self) -> Option<&ast::Expr> {
2059 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {
2064 pub fn is_method_call(expr: &ast::Expr) -> bool {
2066 ast::ExprKind::MethodCall(..) => true,
2067 ast::ExprKind::AddrOf(_, ref expr)
2068 | ast::ExprKind::Box(ref expr)
2069 | ast::ExprKind::Cast(ref expr, _)
2070 | ast::ExprKind::Try(ref expr)
2071 | ast::ExprKind::Unary(_, ref expr) => is_method_call(expr),