1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
15 use syntax::codemap::{BytePos, CodeMap, Span};
16 use syntax::parse::token::DelimToken;
17 use syntax::{ast, ptr};
19 use chains::rewrite_chain;
21 use codemap::{LineRangeUtils, SpanUtils};
23 combine_strs_with_missing_comments, contains_comment, recover_comment_removed, rewrite_comment,
24 rewrite_missing_comment, CharClasses, FindUncommented,
26 use config::{Config, ControlBraceStyle, IndentStyle};
28 definitive_tactic, itemize_list, shape_for_tactic, struct_lit_formatting, struct_lit_shape,
29 struct_lit_tactic, write_list, ListFormatting, ListItem, Separator,
31 use macros::{rewrite_macro, MacroArg, MacroPosition};
32 use matches::rewrite_match;
34 use pairs::{rewrite_all_pairs, rewrite_pair, PairParts};
35 use patterns::{can_be_overflowed_pat, is_short_pattern, TuplePatField};
36 use rewrite::{Rewrite, RewriteContext};
37 use shape::{Indent, Shape};
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 // FIXME(topecongiro) Format async block.
349 ast::ExprKind::Async(..) => None,
353 .and_then(|expr_str| recover_comment_removed(expr_str, expr.span, context))
354 .and_then(|expr_str| {
355 let attrs = outer_attributes(&expr.attrs);
356 let attrs_str = attrs.rewrite(context, shape)?;
358 attrs.last().map_or(expr.span.lo(), |attr| attr.span.hi()),
361 combine_strs_with_missing_comments(context, &attrs_str, &expr_str, span, shape, false)
365 pub fn rewrite_array<T: Rewrite + Spanned + ToExpr>(
369 context: &RewriteContext,
371 force_separator_tactic: Option<SeparatorTactic>,
372 delim_token: Option<DelimToken>,
373 ) -> Option<String> {
374 overflow::rewrite_with_square_brackets(
380 force_separator_tactic,
385 fn rewrite_empty_block(
386 context: &RewriteContext,
388 attrs: Option<&[ast::Attribute]>,
389 label: Option<ast::Label>,
392 ) -> Option<String> {
393 let label_str = rewrite_label(label);
394 if attrs.map_or(false, |a| !inner_attributes(a).is_empty()) {
398 if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) && shape.width >= 2
400 return Some(format!("{}{}{{}}", prefix, label_str));
403 // If a block contains only a single-line comment, then leave it on one line.
404 let user_str = context.snippet(block.span);
405 let user_str = user_str.trim();
406 if user_str.starts_with('{') && user_str.ends_with('}') {
407 let comment_str = user_str[1..user_str.len() - 1].trim();
408 if block.stmts.is_empty()
409 && !comment_str.contains('\n')
410 && !comment_str.starts_with("//")
411 && comment_str.len() + 4 <= shape.width
413 return Some(format!("{}{}{{ {} }}", prefix, label_str, comment_str));
420 fn block_prefix(context: &RewriteContext, block: &ast::Block, shape: Shape) -> Option<String> {
421 Some(match block.rules {
422 ast::BlockCheckMode::Unsafe(..) => {
423 let snippet = context.snippet(block.span);
424 let open_pos = snippet.find_uncommented("{")?;
425 // Extract comment between unsafe and block start.
426 let trimmed = &snippet[6..open_pos].trim();
428 if !trimmed.is_empty() {
429 // 9 = "unsafe {".len(), 7 = "unsafe ".len()
430 let budget = shape.width.checked_sub(9)?;
436 Shape::legacy(budget, shape.indent + 7),
444 ast::BlockCheckMode::Default => String::new(),
448 fn rewrite_single_line_block(
449 context: &RewriteContext,
452 attrs: Option<&[ast::Attribute]>,
453 label: Option<ast::Label>,
455 ) -> Option<String> {
456 if is_simple_block(block, attrs, context.codemap) {
457 let expr_shape = shape.offset_left(last_line_width(prefix))?;
458 let expr_str = block.stmts[0].rewrite(context, expr_shape)?;
459 let label_str = rewrite_label(label);
460 let result = format!("{}{}{{ {} }}", prefix, label_str, expr_str);
461 if result.len() <= shape.width && !result.contains('\n') {
468 pub fn rewrite_block_with_visitor(
469 context: &RewriteContext,
472 attrs: Option<&[ast::Attribute]>,
473 label: Option<ast::Label>,
476 ) -> Option<String> {
477 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, label, prefix, shape) {
481 let mut visitor = FmtVisitor::from_context(context);
482 visitor.block_indent = shape.indent;
483 visitor.is_if_else_block = context.is_if_else_block();
485 ast::BlockCheckMode::Unsafe(..) => {
486 let snippet = context.snippet(block.span);
487 let open_pos = snippet.find_uncommented("{")?;
488 visitor.last_pos = block.span.lo() + BytePos(open_pos as u32)
490 ast::BlockCheckMode::Default => visitor.last_pos = block.span.lo(),
493 let inner_attrs = attrs.map(inner_attributes);
494 let label_str = rewrite_label(label);
495 visitor.visit_block(block, inner_attrs.as_ref().map(|a| &**a), has_braces);
496 Some(format!("{}{}{}", prefix, label_str, visitor.buffer))
499 impl Rewrite for ast::Block {
500 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
501 rewrite_block(self, None, None, context, shape)
507 attrs: Option<&[ast::Attribute]>,
508 label: Option<ast::Label>,
509 context: &RewriteContext,
511 ) -> Option<String> {
512 let prefix = block_prefix(context, block, shape)?;
514 // shape.width is used only for the single line case: either the empty block `{}`,
515 // or an unsafe expression `unsafe { e }`.
516 if let rw @ Some(_) = rewrite_empty_block(context, block, attrs, label, &prefix, shape) {
520 let result = rewrite_block_with_visitor(context, &prefix, block, attrs, label, shape, true);
521 if let Some(ref result_str) = result {
522 if result_str.lines().count() <= 3 {
523 if let rw @ Some(_) =
524 rewrite_single_line_block(context, &prefix, block, attrs, label, shape)
534 impl Rewrite for ast::Stmt {
535 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
536 skip_out_of_file_lines_range!(context, self.span());
538 let result = match self.node {
539 ast::StmtKind::Local(ref local) => local.rewrite(context, shape),
540 ast::StmtKind::Expr(ref ex) | ast::StmtKind::Semi(ref ex) => {
541 let suffix = if semicolon_for_stmt(context, self) {
547 let shape = shape.sub_width(suffix.len())?;
548 format_expr(ex, ExprType::Statement, context, shape).map(|s| s + suffix)
550 ast::StmtKind::Mac(..) | ast::StmtKind::Item(..) => None,
552 result.and_then(|res| recover_comment_removed(res, self.span(), context))
556 // Rewrite condition if the given expression has one.
557 pub fn rewrite_cond(context: &RewriteContext, expr: &ast::Expr, shape: Shape) -> Option<String> {
559 ast::ExprKind::Match(ref cond, _) => {
561 let cond_shape = match context.config.indent_style() {
562 IndentStyle::Visual => shape.shrink_left(6).and_then(|s| s.sub_width(2))?,
563 IndentStyle::Block => shape.offset_left(8)?,
565 cond.rewrite(context, cond_shape)
567 _ => to_control_flow(expr, ExprType::SubExpression).and_then(|control_flow| {
569 String::from("\n") + &shape.indent.block_only().to_string(context.config);
571 .rewrite_cond(context, shape, &alt_block_sep)
572 .and_then(|rw| Some(rw.0))
577 // Abstraction over control flow expressions
579 struct ControlFlow<'a> {
580 cond: Option<&'a ast::Expr>,
581 block: &'a ast::Block,
582 else_block: Option<&'a ast::Expr>,
583 label: Option<ast::Label>,
584 pats: Vec<&'a ast::Pat>,
588 allow_single_line: bool,
589 // True if this is an `if` expression in an `else if` :-( hacky
594 fn to_control_flow(expr: &ast::Expr, expr_type: ExprType) -> Option<ControlFlow> {
596 ast::ExprKind::If(ref cond, ref if_block, ref else_block) => Some(ControlFlow::new_if(
600 else_block.as_ref().map(|e| &**e),
601 expr_type == ExprType::SubExpression,
605 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref else_block) => {
606 Some(ControlFlow::new_if(
608 ptr_vec_to_ref_vec(pat),
610 else_block.as_ref().map(|e| &**e),
611 expr_type == ExprType::SubExpression,
616 ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
617 Some(ControlFlow::new_for(pat, cond, block, label, expr.span))
619 ast::ExprKind::Loop(ref block, label) => {
620 Some(ControlFlow::new_loop(block, label, expr.span))
622 ast::ExprKind::While(ref cond, ref block, label) => Some(ControlFlow::new_while(
629 ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => Some(
630 ControlFlow::new_while(ptr_vec_to_ref_vec(pat), cond, block, label, expr.span),
636 fn choose_matcher(pats: &[&ast::Pat]) -> &'static str {
644 impl<'a> ControlFlow<'a> {
647 pats: Vec<&'a ast::Pat>,
648 block: &'a ast::Block,
649 else_block: Option<&'a ast::Expr>,
650 allow_single_line: bool,
653 ) -> ControlFlow<'a> {
654 let matcher = choose_matcher(&pats);
670 fn new_loop(block: &'a ast::Block, label: Option<ast::Label>, span: Span) -> ControlFlow<'a> {
680 allow_single_line: false,
687 pats: Vec<&'a ast::Pat>,
689 block: &'a ast::Block,
690 label: Option<ast::Label>,
692 ) -> ControlFlow<'a> {
693 let matcher = choose_matcher(&pats);
703 allow_single_line: false,
712 block: &'a ast::Block,
713 label: Option<ast::Label>,
715 ) -> ControlFlow<'a> {
725 allow_single_line: false,
731 fn rewrite_single_line(
734 context: &RewriteContext,
736 ) -> Option<String> {
737 assert!(self.allow_single_line);
738 let else_block = self.else_block?;
739 let fixed_cost = self.keyword.len() + " { } else { }".len();
741 if let ast::ExprKind::Block(ref else_node, _) = else_block.node {
742 if !is_simple_block(self.block, None, context.codemap)
743 || !is_simple_block(else_node, None, context.codemap)
744 || pat_expr_str.contains('\n')
749 let new_width = width.checked_sub(pat_expr_str.len() + fixed_cost)?;
750 let expr = &self.block.stmts[0];
751 let if_str = expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
753 let new_width = new_width.checked_sub(if_str.len())?;
754 let else_expr = &else_node.stmts[0];
755 let else_str = else_expr.rewrite(context, Shape::legacy(new_width, Indent::empty()))?;
757 if if_str.contains('\n') || else_str.contains('\n') {
761 let result = format!(
762 "{} {} {{ {} }} else {{ {} }}",
763 self.keyword, pat_expr_str, if_str, else_str
766 if result.len() <= width {
775 impl<'a> ControlFlow<'a> {
778 context: &RewriteContext,
782 ) -> Option<String> {
783 debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, self.pats, expr);
785 let cond_shape = shape.offset_left(offset)?;
786 if !self.pats.is_empty() {
787 let matcher = if self.matcher.is_empty() {
788 self.matcher.to_owned()
790 format!("{} ", self.matcher)
792 let pat_shape = cond_shape
793 .offset_left(matcher.len())?
794 .sub_width(self.connector.len())?;
795 let pat_string = rewrite_multiple_patterns(context, &self.pats, pat_shape)?;
796 let result = format!("{}{}{}", matcher, pat_string, self.connector);
797 return rewrite_assign_rhs(context, result, expr, cond_shape);
800 let expr_rw = expr.rewrite(context, cond_shape);
801 // The expression may (partially) fit on the current line.
802 // We do not allow splitting between `if` and condition.
803 if self.keyword == "if" || expr_rw.is_some() {
807 // The expression won't fit on the current line, jump to next.
808 let nested_shape = shape
809 .block_indent(context.config.tab_spaces())
810 .with_max_width(context.config);
811 let nested_indent_str = nested_shape.indent.to_string_with_newline(context.config);
812 expr.rewrite(context, nested_shape)
813 .map(|expr_rw| format!("{}{}", nested_indent_str, expr_rw))
818 context: &RewriteContext,
821 ) -> Option<(String, usize)> {
822 // Do not take the rhs overhead from the upper expressions into account
823 // when rewriting pattern.
824 let new_width = context.budget(shape.used_width());
825 let fresh_shape = Shape {
829 let constr_shape = if self.nested_if {
830 // We are part of an if-elseif-else chain. Our constraints are tightened.
831 // 7 = "} else " .len()
832 fresh_shape.offset_left(7)?
837 let label_string = rewrite_label(self.label);
838 // 1 = space after keyword.
839 let offset = self.keyword.len() + label_string.len() + 1;
841 let pat_expr_string = match self.cond {
842 Some(cond) => self.rewrite_pat_expr(context, cond, constr_shape, offset)?,
843 None => String::new(),
847 if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
853 let one_line_budget = context
856 .saturating_sub(constr_shape.used_width() + offset + brace_overhead);
857 let force_newline_brace = (pat_expr_string.contains('\n')
858 || pat_expr_string.len() > one_line_budget)
859 && !last_line_extendable(&pat_expr_string);
861 // Try to format if-else on single line.
862 if self.allow_single_line
866 .single_line_if_else_max_width
869 let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width);
871 if let Some(cond_str) = trial {
872 if cond_str.len() <= context
875 .single_line_if_else_max_width
877 return Some((cond_str, 0));
882 let cond_span = if let Some(cond) = self.cond {
885 mk_sp(self.block.span.lo(), self.block.span.lo())
888 // `for event in event`
889 // Do not include label in the span.
892 .map_or(self.span.lo(), |label| label.ident.span.hi());
893 let between_kwd_cond = mk_sp(
896 .span_after(mk_sp(lo, self.span.hi()), self.keyword.trim()),
897 if self.pats.is_empty() {
899 } else if self.matcher.is_empty() {
900 self.pats[0].span.lo()
904 .span_before(self.span, self.matcher.trim())
908 let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape);
910 let after_cond_comment =
911 extract_comment(mk_sp(cond_span.hi(), self.block.span.lo()), context, shape);
913 let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
915 } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine
916 || force_newline_brace
923 let used_width = if pat_expr_string.contains('\n') {
924 last_line_width(&pat_expr_string)
926 // 2 = spaces after keyword and condition.
927 label_string.len() + self.keyword.len() + pat_expr_string.len() + 2
935 between_kwd_cond_comment.as_ref().map_or(
936 if pat_expr_string.is_empty() || pat_expr_string.starts_with('\n') {
944 after_cond_comment.as_ref().map_or(block_sep, |s| &**s)
951 impl<'a> Rewrite for ControlFlow<'a> {
952 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
953 debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
955 let alt_block_sep = &shape.indent.to_string_with_newline(context.config);
956 let (cond_str, used_width) = self.rewrite_cond(context, shape, alt_block_sep)?;
957 // If `used_width` is 0, it indicates that whole control flow is written in a single line.
959 return Some(cond_str);
962 let block_width = shape.width.saturating_sub(used_width);
963 // This is used only for the empty block case: `{}`. So, we use 1 if we know
964 // we should avoid the single line case.
965 let block_width = if self.else_block.is_some() || self.nested_if {
970 let block_shape = Shape {
975 let old_val = context.is_if_else_block.replace(self.else_block.is_some());
977 rewrite_block_with_visitor(context, "", self.block, None, None, block_shape, true);
978 context.is_if_else_block.replace(old_val);
982 let mut result = format!("{}{}", cond_str, block_str);
984 if let Some(else_block) = self.else_block {
985 let shape = Shape::indented(shape.indent, context.config);
986 let mut last_in_chain = false;
987 let rewrite = match else_block.node {
988 // If the else expression is another if-else expression, prevent it
989 // from being formatted on a single line.
990 // Note how we're passing the original shape, as the
991 // cost of "else" should not cascade.
992 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref next_else_block) => {
995 ptr_vec_to_ref_vec(pat),
997 next_else_block.as_ref().map(|e| &**e),
1000 mk_sp(else_block.span.lo(), self.span.hi()),
1001 ).rewrite(context, shape)
1003 ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => {
1004 ControlFlow::new_if(
1008 next_else_block.as_ref().map(|e| &**e),
1011 mk_sp(else_block.span.lo(), self.span.hi()),
1012 ).rewrite(context, shape)
1015 last_in_chain = true;
1016 // When rewriting a block, the width is only used for single line
1017 // blocks, passing 1 lets us avoid that.
1018 let else_shape = Shape {
1019 width: min(1, shape.width),
1022 format_expr(else_block, ExprType::Statement, context, else_shape)
1026 let between_kwd_else_block = mk_sp(
1027 self.block.span.hi(),
1030 .span_before(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1032 let between_kwd_else_block_comment =
1033 extract_comment(between_kwd_else_block, context, shape);
1035 let after_else = mk_sp(
1038 .span_after(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1039 else_block.span.lo(),
1041 let after_else_comment = extract_comment(after_else, context, shape);
1043 let between_sep = match context.config.control_brace_style() {
1044 ControlBraceStyle::AlwaysNextLine | ControlBraceStyle::ClosingNextLine => {
1047 ControlBraceStyle::AlwaysSameLine => " ",
1049 let after_sep = match context.config.control_brace_style() {
1050 ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep,
1054 result.push_str(&format!(
1056 between_kwd_else_block_comment
1058 .map_or(between_sep, |s| &**s),
1059 after_else_comment.as_ref().map_or(after_sep, |s| &**s),
1061 result.push_str(&rewrite?);
1068 fn rewrite_label(opt_label: Option<ast::Label>) -> Cow<'static, str> {
1070 Some(label) => Cow::from(format!("{}: ", label.ident)),
1071 None => Cow::from(""),
1075 fn extract_comment(span: Span, context: &RewriteContext, shape: Shape) -> Option<String> {
1076 match rewrite_missing_comment(span, shape, context) {
1077 Some(ref comment) if !comment.is_empty() => Some(format!(
1078 "{indent}{}{indent}",
1080 indent = shape.indent.to_string_with_newline(context.config)
1086 pub fn block_contains_comment(block: &ast::Block, codemap: &CodeMap) -> bool {
1087 let snippet = codemap.span_to_snippet(block.span).unwrap();
1088 contains_comment(&snippet)
1091 // Checks that a block contains no statements, an expression and no comments or
1093 // FIXME: incorrectly returns false when comment is contained completely within
1095 pub fn is_simple_block(
1097 attrs: Option<&[ast::Attribute]>,
1100 (block.stmts.len() == 1
1101 && stmt_is_expr(&block.stmts[0])
1102 && !block_contains_comment(block, codemap)
1103 && attrs.map_or(true, |a| a.is_empty()))
1106 /// Checks whether a block contains at most one statement or expression, and no
1107 /// comments or attributes.
1108 pub fn is_simple_block_stmt(
1110 attrs: Option<&[ast::Attribute]>,
1113 block.stmts.len() <= 1
1114 && !block_contains_comment(block, codemap)
1115 && attrs.map_or(true, |a| a.is_empty())
1118 /// Checks whether a block contains no statements, expressions, comments, or
1119 /// inner attributes.
1120 pub fn is_empty_block(
1122 attrs: Option<&[ast::Attribute]>,
1125 block.stmts.is_empty()
1126 && !block_contains_comment(block, codemap)
1127 && attrs.map_or(true, |a| inner_attributes(a).is_empty())
1130 pub fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
1132 ast::StmtKind::Expr(..) => true,
1137 pub fn is_unsafe_block(block: &ast::Block) -> bool {
1138 if let ast::BlockCheckMode::Unsafe(..) = block.rules {
1145 pub fn rewrite_multiple_patterns(
1146 context: &RewriteContext,
1149 ) -> Option<String> {
1152 .map(|p| p.rewrite(context, shape))
1153 .collect::<Option<Vec<_>>>()?;
1155 let use_mixed_layout = pats
1157 .zip(pat_strs.iter())
1158 .all(|(pat, pat_str)| is_short_pattern(pat, pat_str));
1159 let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
1160 let tactic = if use_mixed_layout {
1161 DefinitiveListTactic::Mixed
1165 ListTactic::HorizontalVertical,
1166 Separator::VerticalBar,
1170 let fmt = ListFormatting {
1173 trailing_separator: SeparatorTactic::Never,
1174 separator_place: context.config.binop_separator(),
1176 ends_with_newline: false,
1177 preserve_newline: false,
1179 config: context.config,
1181 write_list(&items, &fmt)
1184 pub fn rewrite_literal(context: &RewriteContext, l: &ast::Lit, shape: Shape) -> Option<String> {
1186 ast::LitKind::Str(_, ast::StrStyle::Cooked) => rewrite_string_lit(context, l.span, shape),
1188 context.snippet(l.span).to_owned(),
1189 context.config.max_width(),
1195 fn rewrite_string_lit(context: &RewriteContext, span: Span, shape: Shape) -> Option<String> {
1196 let string_lit = context.snippet(span);
1198 if !context.config.format_strings() {
1203 .all(|line| line.ends_with('\\'))
1205 let new_indent = shape.visual_indent(1).indent;
1206 let indented_string_lit = String::from(
1212 new_indent.to_string(context.config),
1215 }).collect::<Vec<_>>()
1219 return wrap_str(indented_string_lit, context.config.max_width(), shape);
1221 return wrap_str(string_lit.to_owned(), context.config.max_width(), shape);
1225 // Remove the quote characters.
1226 let str_lit = &string_lit[1..string_lit.len() - 1];
1230 &StringFormat::new(shape.visual_indent(0), context.config),
1234 /// In case special-case style is required, returns an offset from which we start horizontal layout.
1235 pub fn maybe_get_args_offset<T: ToExpr>(callee_str: &str, args: &[&T]) -> Option<(bool, usize)> {
1236 if let Some(&(_, num_args_before)) = SPECIAL_MACRO_WHITELIST
1238 .find(|&&(s, _)| s == callee_str)
1240 let all_simple = args.len() > num_args_before && is_every_expr_simple(args);
1242 Some((all_simple, num_args_before))
1248 /// A list of `format!`-like macros, that take a long format string and a list of arguments to
1251 /// Organized as a list of `(&str, usize)` tuples, giving the name of the macro and the number of
1252 /// arguments before the format string (none for `format!("format", ...)`, one for `assert!(result,
1253 /// "format", ...)`, two for `assert_eq!(left, right, "format", ...)`).
1254 const SPECIAL_MACRO_WHITELIST: &[(&str, usize)] = &[
1255 // format! like macros
1256 // From the Rust Standard Library.
1260 ("format_args!", 0),
1264 ("unreachable!", 0),
1265 // From the `log` crate.
1270 // write! like macros
1272 ("debug_assert!", 1),
1275 // assert_eq! like macros
1278 ("debug_assert_eq!", 2),
1279 ("debug_assert_ne!", 2),
1282 fn choose_separator_tactic(context: &RewriteContext, span: Span) -> Option<SeparatorTactic> {
1283 if context.inside_macro() {
1284 if span_ends_with_comma(context, span) {
1285 Some(SeparatorTactic::Always)
1287 Some(SeparatorTactic::Never)
1294 pub fn rewrite_call(
1295 context: &RewriteContext,
1297 args: &[ptr::P<ast::Expr>],
1300 ) -> Option<String> {
1301 overflow::rewrite_with_parens(
1304 &ptr_vec_to_ref_vec(args),
1307 context.config.width_heuristics().fn_call_width,
1308 choose_separator_tactic(context, span),
1312 fn is_simple_expr(expr: &ast::Expr) -> bool {
1314 ast::ExprKind::Lit(..) => true,
1315 ast::ExprKind::Path(ref qself, ref path) => qself.is_none() && path.segments.len() <= 1,
1316 ast::ExprKind::AddrOf(_, ref expr)
1317 | ast::ExprKind::Box(ref expr)
1318 | ast::ExprKind::Cast(ref expr, _)
1319 | ast::ExprKind::Field(ref expr, _)
1320 | ast::ExprKind::Try(ref expr)
1321 | ast::ExprKind::Unary(_, ref expr) => is_simple_expr(expr),
1322 ast::ExprKind::Index(ref lhs, ref rhs) => is_simple_expr(lhs) && is_simple_expr(rhs),
1323 ast::ExprKind::Repeat(ref lhs, ref rhs) => {
1324 is_simple_expr(lhs) && is_simple_expr(&*rhs.value)
1330 pub fn is_every_expr_simple<T: ToExpr>(lists: &[&T]) -> bool {
1333 .all(|arg| arg.to_expr().map_or(false, is_simple_expr))
1336 pub fn can_be_overflowed_expr(context: &RewriteContext, expr: &ast::Expr, args_len: usize) -> bool {
1338 ast::ExprKind::Match(..) => {
1339 (context.use_block_indent() && args_len == 1)
1340 || (context.config.indent_style() == IndentStyle::Visual && args_len > 1)
1342 ast::ExprKind::If(..)
1343 | ast::ExprKind::IfLet(..)
1344 | ast::ExprKind::ForLoop(..)
1345 | ast::ExprKind::Loop(..)
1346 | ast::ExprKind::While(..)
1347 | ast::ExprKind::WhileLet(..) => {
1348 context.config.combine_control_expr() && context.use_block_indent() && args_len == 1
1350 ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => {
1351 context.use_block_indent()
1352 || context.config.indent_style() == IndentStyle::Visual && args_len > 1
1354 ast::ExprKind::Array(..)
1355 | ast::ExprKind::Call(..)
1356 | ast::ExprKind::Mac(..)
1357 | ast::ExprKind::MethodCall(..)
1358 | ast::ExprKind::Struct(..)
1359 | ast::ExprKind::Tup(..) => context.use_block_indent() && args_len == 1,
1360 ast::ExprKind::AddrOf(_, ref expr)
1361 | ast::ExprKind::Box(ref expr)
1362 | ast::ExprKind::Try(ref expr)
1363 | ast::ExprKind::Unary(_, ref expr)
1364 | ast::ExprKind::Cast(ref expr, _) => can_be_overflowed_expr(context, expr, args_len),
1369 pub fn is_nested_call(expr: &ast::Expr) -> bool {
1371 ast::ExprKind::Call(..) | ast::ExprKind::Mac(..) => true,
1372 ast::ExprKind::AddrOf(_, ref expr)
1373 | ast::ExprKind::Box(ref expr)
1374 | ast::ExprKind::Try(ref expr)
1375 | ast::ExprKind::Unary(_, ref expr)
1376 | ast::ExprKind::Cast(ref expr, _) => is_nested_call(expr),
1381 /// Return true if a function call or a method call represented by the given span ends with a
1382 /// trailing comma. This function is used when rewriting macro, as adding or removing a trailing
1383 /// comma from macro can potentially break the code.
1384 pub fn span_ends_with_comma(context: &RewriteContext, span: Span) -> bool {
1385 let mut result: bool = Default::default();
1386 let mut prev_char: char = Default::default();
1387 let closing_delimiters = &[')', '}', ']'];
1389 for (kind, c) in CharClasses::new(context.snippet(span).chars()) {
1391 _ if kind.is_comment() || c.is_whitespace() => continue,
1392 c if closing_delimiters.contains(&c) => {
1393 result &= !closing_delimiters.contains(&prev_char);
1395 ',' => result = true,
1396 _ => result = false,
1405 context: &RewriteContext,
1406 mut subexpr: &ast::Expr,
1409 ) -> Option<String> {
1410 debug!("rewrite_paren, shape: {:?}", shape);
1412 // Extract comments within parens.
1413 let mut pre_comment;
1414 let mut post_comment;
1415 let remove_nested_parens = context.config.remove_nested_parens();
1418 let pre_span = mk_sp(span.lo() + BytePos(1), subexpr.span.lo());
1419 let post_span = mk_sp(subexpr.span.hi(), span.hi() - BytePos(1));
1420 pre_comment = rewrite_missing_comment(pre_span, shape, context)?;
1421 post_comment = rewrite_missing_comment(post_span, shape, context)?;
1423 // Remove nested parens if there are no comments.
1424 if let ast::ExprKind::Paren(ref subsubexpr) = subexpr.node {
1425 if remove_nested_parens && pre_comment.is_empty() && post_comment.is_empty() {
1426 span = subexpr.span;
1427 subexpr = subsubexpr;
1436 let sub_shape = shape.offset_left(1).and_then(|s| s.sub_width(1))?;
1438 let subexpr_str = subexpr.rewrite(context, sub_shape)?;
1439 debug!("rewrite_paren, subexpr_str: `{:?}`", subexpr_str);
1442 if subexpr_str.contains('\n') || first_line_width(&subexpr_str) + 2 <= shape.width {
1443 Some(format!("({}{}{})", pre_comment, &subexpr_str, post_comment))
1452 context: &RewriteContext,
1454 ) -> Option<String> {
1455 let expr_str = expr.rewrite(context, shape)?;
1457 let offset = last_line_width(&expr_str) + 1;
1458 let rhs_overhead = shape.rhs_overhead(context.config);
1459 let index_shape = if expr_str.contains('\n') {
1460 Shape::legacy(context.config.max_width(), shape.indent)
1461 .offset_left(offset)
1462 .and_then(|shape| shape.sub_width(1 + rhs_overhead))
1464 shape.visual_indent(offset).sub_width(offset + 1)
1466 let orig_index_rw = index_shape.and_then(|s| index.rewrite(context, s));
1468 // Return if index fits in a single line.
1469 match orig_index_rw {
1470 Some(ref index_str) if !index_str.contains('\n') => {
1471 return Some(format!("{}[{}]", expr_str, index_str));
1476 // Try putting index on the next line and see if it fits in a single line.
1477 let indent = shape.indent.block_indent(context.config);
1478 let index_shape = Shape::indented(indent, context.config).offset_left(1)?;
1479 let index_shape = index_shape.sub_width(1 + rhs_overhead)?;
1480 let new_index_rw = index.rewrite(context, index_shape);
1481 match (orig_index_rw, new_index_rw) {
1482 (_, Some(ref new_index_str)) if !new_index_str.contains('\n') => Some(format!(
1485 indent.to_string_with_newline(context.config),
1488 (None, Some(ref new_index_str)) => Some(format!(
1491 indent.to_string_with_newline(context.config),
1494 (Some(ref index_str), _) => Some(format!("{}[{}]", expr_str, index_str)),
1499 fn struct_lit_can_be_aligned(fields: &[ast::Field], base: &Option<&ast::Expr>) -> bool {
1504 fields.iter().all(|field| !field.is_shorthand)
1507 fn rewrite_struct_lit<'a>(
1508 context: &RewriteContext,
1510 fields: &'a [ast::Field],
1511 base: Option<&'a ast::Expr>,
1514 ) -> Option<String> {
1515 debug!("rewrite_struct_lit: shape {:?}", shape);
1517 enum StructLitField<'a> {
1518 Regular(&'a ast::Field),
1519 Base(&'a ast::Expr),
1523 let path_shape = shape.sub_width(2)?;
1524 let path_str = rewrite_path(context, PathContext::Expr, None, path, path_shape)?;
1526 if fields.is_empty() && base.is_none() {
1527 return Some(format!("{} {{}}", path_str));
1530 // Foo { a: Foo } - indent is +3, width is -5.
1531 let (h_shape, v_shape) = struct_lit_shape(shape, context, path_str.len() + 3, 2)?;
1533 let one_line_width = h_shape.map_or(0, |shape| shape.width);
1534 let body_lo = context.snippet_provider.span_after(span, "{");
1535 let fields_str = if struct_lit_can_be_aligned(fields, &base)
1536 && context.config.struct_field_align_threshold() > 0
1538 rewrite_with_alignment(
1542 mk_sp(body_lo, span.hi()),
1546 let field_iter = fields
1548 .map(StructLitField::Regular)
1549 .chain(base.into_iter().map(StructLitField::Base));
1551 let span_lo = |item: &StructLitField| match *item {
1552 StructLitField::Regular(field) => field.span().lo(),
1553 StructLitField::Base(expr) => {
1554 let last_field_hi = fields.last().map_or(span.lo(), |field| field.span.hi());
1555 let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo()));
1556 let pos = snippet.find_uncommented("..").unwrap();
1557 last_field_hi + BytePos(pos as u32)
1560 let span_hi = |item: &StructLitField| match *item {
1561 StructLitField::Regular(field) => field.span().hi(),
1562 StructLitField::Base(expr) => expr.span.hi(),
1564 let rewrite = |item: &StructLitField| match *item {
1565 StructLitField::Regular(field) => {
1566 // The 1 taken from the v_budget is for the comma.
1567 rewrite_field(context, field, v_shape.sub_width(1)?, 0)
1569 StructLitField::Base(expr) => {
1571 expr.rewrite(context, v_shape.offset_left(2)?)
1572 .map(|s| format!("..{}", s))
1576 let items = itemize_list(
1577 context.snippet_provider,
1588 let item_vec = items.collect::<Vec<_>>();
1590 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
1591 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
1593 let ends_with_comma = span_ends_with_comma(context, span);
1594 let force_no_trailing_comma = context.inside_macro() && !ends_with_comma;
1596 let fmt = struct_lit_formatting(
1600 force_no_trailing_comma || base.is_some(),
1603 write_list(&item_vec, &fmt)?
1606 let fields_str = wrap_struct_field(context, &fields_str, shape, v_shape, one_line_width);
1607 Some(format!("{} {{{}}}", path_str, fields_str))
1609 // FIXME if context.config.indent_style() == Visual, but we run out
1610 // of space, we should fall back to BlockIndent.
1613 pub fn wrap_struct_field(
1614 context: &RewriteContext,
1617 nested_shape: Shape,
1618 one_line_width: usize,
1620 if context.config.indent_style() == IndentStyle::Block
1621 && (fields_str.contains('\n')
1622 || !context.config.struct_lit_single_line()
1623 || fields_str.len() > one_line_width)
1627 nested_shape.indent.to_string_with_newline(context.config),
1629 shape.indent.to_string_with_newline(context.config)
1632 // One liner or visual indent.
1633 format!(" {} ", fields_str)
1637 pub fn struct_lit_field_separator(config: &Config) -> &str {
1638 colon_spaces(config.space_before_colon(), config.space_after_colon())
1641 pub fn rewrite_field(
1642 context: &RewriteContext,
1645 prefix_max_width: usize,
1646 ) -> Option<String> {
1647 if contains_skip(&field.attrs) {
1648 return Some(context.snippet(field.span()).to_owned());
1650 let mut attrs_str = field.attrs.rewrite(context, shape)?;
1651 if !attrs_str.is_empty() {
1652 attrs_str.push_str(&shape.indent.to_string_with_newline(context.config));
1654 let name = &field.ident.name.to_string();
1655 if field.is_shorthand {
1656 Some(attrs_str + &name)
1658 let mut separator = String::from(struct_lit_field_separator(context.config));
1659 for _ in 0..prefix_max_width.saturating_sub(name.len()) {
1660 separator.push(' ');
1662 let overhead = name.len() + separator.len();
1663 let expr_shape = shape.offset_left(overhead)?;
1664 let expr = field.expr.rewrite(context, expr_shape);
1667 Some(ref e) if e.as_str() == name && context.config.use_field_init_shorthand() => {
1668 Some(attrs_str + &name)
1670 Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)),
1672 let expr_offset = shape.indent.block_indent(context.config);
1675 .rewrite(context, Shape::indented(expr_offset, context.config));
1681 expr_offset.to_string(context.config),
1690 fn rewrite_tuple_in_visual_indent_style<'a, T>(
1691 context: &RewriteContext,
1697 T: Rewrite + Spanned + ToExpr + 'a,
1699 let mut items = items.iter();
1700 // In case of length 1, need a trailing comma
1701 debug!("rewrite_tuple_in_visual_indent_style {:?}", shape);
1702 if items.len() == 1 {
1704 let nested_shape = shape.sub_width(3)?.visual_indent(1);
1708 .rewrite(context, nested_shape)
1709 .map(|s| format!("({},)", s));
1712 let list_lo = context.snippet_provider.span_after(span, "(");
1713 let nested_shape = shape.sub_width(2)?.visual_indent(1);
1714 let items = itemize_list(
1715 context.snippet_provider,
1719 |item| item.span().lo(),
1720 |item| item.span().hi(),
1721 |item| item.rewrite(context, nested_shape),
1723 span.hi() - BytePos(1),
1726 let item_vec: Vec<_> = items.collect();
1727 let tactic = definitive_tactic(
1729 ListTactic::HorizontalVertical,
1733 let fmt = ListFormatting {
1736 trailing_separator: SeparatorTactic::Never,
1737 separator_place: SeparatorPlace::Back,
1739 ends_with_newline: false,
1740 preserve_newline: false,
1742 config: context.config,
1744 let list_str = write_list(&item_vec, &fmt)?;
1746 Some(format!("({})", list_str))
1749 pub fn rewrite_tuple<'a, T>(
1750 context: &RewriteContext,
1756 T: Rewrite + Spanned + ToExpr + 'a,
1758 debug!("rewrite_tuple {:?}", shape);
1759 if context.use_block_indent() {
1760 // We use the same rule as function calls for rewriting tuples.
1761 let force_tactic = if context.inside_macro() {
1762 if span_ends_with_comma(context, span) {
1763 Some(SeparatorTactic::Always)
1765 Some(SeparatorTactic::Never)
1767 } else if items.len() == 1 {
1768 Some(SeparatorTactic::Always)
1772 overflow::rewrite_with_parens(
1778 context.config.width_heuristics().fn_call_width,
1782 rewrite_tuple_in_visual_indent_style(context, items, span, shape)
1786 pub fn rewrite_unary_prefix<R: Rewrite>(
1787 context: &RewriteContext,
1791 ) -> Option<String> {
1793 .rewrite(context, shape.offset_left(prefix.len())?)
1794 .map(|r| format!("{}{}", prefix, r))
1797 // FIXME: this is probably not correct for multi-line Rewrites. we should
1798 // subtract suffix.len() from the last line budget, not the first!
1799 pub fn rewrite_unary_suffix<R: Rewrite>(
1800 context: &RewriteContext,
1804 ) -> Option<String> {
1806 .rewrite(context, shape.sub_width(suffix.len())?)
1813 fn rewrite_unary_op(
1814 context: &RewriteContext,
1818 ) -> Option<String> {
1819 // For some reason, an UnOp is not spanned like BinOp!
1820 let operator_str = match *op {
1821 ast::UnOp::Deref => "*",
1822 ast::UnOp::Not => "!",
1823 ast::UnOp::Neg => "-",
1825 rewrite_unary_prefix(context, operator_str, expr, shape)
1828 fn rewrite_assignment(
1829 context: &RewriteContext,
1832 op: Option<&ast::BinOp>,
1834 ) -> Option<String> {
1835 let operator_str = match op {
1836 Some(op) => context.snippet(op.span),
1840 // 1 = space between lhs and operator.
1841 let lhs_shape = shape.sub_width(operator_str.len() + 1)?;
1842 let lhs_str = format!("{} {}", lhs.rewrite(context, lhs_shape)?, operator_str);
1844 rewrite_assign_rhs(context, lhs_str, rhs, shape)
1847 /// Controls where to put the rhs.
1848 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
1849 pub enum RhsTactics {
1852 /// Put the rhs on the next line if it uses multiple line, without extra indentation.
1853 ForceNextLineWithoutIndent,
1856 // The left hand side must contain everything up to, and including, the
1857 // assignment operator.
1858 pub fn rewrite_assign_rhs<S: Into<String>, R: Rewrite>(
1859 context: &RewriteContext,
1863 ) -> Option<String> {
1864 rewrite_assign_rhs_with(context, lhs, ex, shape, RhsTactics::Default)
1867 pub fn rewrite_assign_rhs_with<S: Into<String>, R: Rewrite>(
1868 context: &RewriteContext,
1872 rhs_tactics: RhsTactics,
1873 ) -> Option<String> {
1874 let lhs = lhs.into();
1875 let last_line_width = last_line_width(&lhs).saturating_sub(if lhs.contains('\n') {
1876 shape.indent.width()
1880 // 1 = space between operator and rhs.
1881 let orig_shape = shape.offset_left(last_line_width + 1).unwrap_or(Shape {
1883 offset: shape.offset + last_line_width + 1,
1886 let rhs = choose_rhs(
1890 ex.rewrite(context, orig_shape),
1896 fn choose_rhs<R: Rewrite>(
1897 context: &RewriteContext,
1900 orig_rhs: Option<String>,
1901 rhs_tactics: RhsTactics,
1902 ) -> Option<String> {
1904 Some(ref new_str) if !new_str.contains('\n') && new_str.len() <= shape.width => {
1905 Some(format!(" {}", new_str))
1908 // Expression did not fit on the same line as the identifier.
1909 // Try splitting the line and see if that works better.
1910 let new_shape = shape_from_rhs_tactic(context, shape, rhs_tactics)?;
1911 let new_rhs = expr.rewrite(context, new_shape);
1912 let new_indent_str = &shape
1914 .block_indent(context.config)
1915 .to_string_with_newline(context.config);
1917 match (orig_rhs, new_rhs) {
1918 (Some(ref orig_rhs), Some(ref new_rhs))
1919 if wrap_str(new_rhs.clone(), context.config.max_width(), new_shape)
1922 Some(format!(" {}", orig_rhs))
1924 (Some(ref orig_rhs), Some(ref new_rhs))
1925 if prefer_next_line(orig_rhs, new_rhs, rhs_tactics) =>
1927 Some(format!("{}{}", new_indent_str, new_rhs))
1929 (None, Some(ref new_rhs)) => Some(format!("{}{}", new_indent_str, new_rhs)),
1930 (None, None) => None,
1931 (Some(orig_rhs), _) => Some(format!(" {}", orig_rhs)),
1937 fn shape_from_rhs_tactic(
1938 context: &RewriteContext,
1940 rhs_tactic: RhsTactics,
1941 ) -> Option<Shape> {
1943 RhsTactics::ForceNextLineWithoutIndent => Some(shape.with_max_width(context.config)),
1944 RhsTactics::Default => {
1945 Shape::indented(shape.indent.block_indent(context.config), context.config)
1946 .sub_width(shape.rhs_overhead(context.config))
1951 pub fn prefer_next_line(orig_rhs: &str, next_line_rhs: &str, rhs_tactics: RhsTactics) -> bool {
1952 rhs_tactics == RhsTactics::ForceNextLineWithoutIndent
1953 || !next_line_rhs.contains('\n')
1954 || count_newlines(orig_rhs) > count_newlines(next_line_rhs) + 1
1955 || first_line_ends_with(orig_rhs, '(') && !first_line_ends_with(next_line_rhs, '(')
1956 || first_line_ends_with(orig_rhs, '{') && !first_line_ends_with(next_line_rhs, '{')
1957 || first_line_ends_with(orig_rhs, '[') && !first_line_ends_with(next_line_rhs, '[')
1960 fn rewrite_expr_addrof(
1961 context: &RewriteContext,
1962 mutability: ast::Mutability,
1965 ) -> Option<String> {
1966 let operator_str = match mutability {
1967 ast::Mutability::Immutable => "&",
1968 ast::Mutability::Mutable => "&mut ",
1970 rewrite_unary_prefix(context, operator_str, expr, shape)
1974 fn to_expr(&self) -> Option<&ast::Expr>;
1975 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool;
1978 impl ToExpr for ast::Expr {
1979 fn to_expr(&self) -> Option<&ast::Expr> {
1983 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
1984 can_be_overflowed_expr(context, self, len)
1988 impl ToExpr for ast::Ty {
1989 fn to_expr(&self) -> Option<&ast::Expr> {
1993 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
1994 can_be_overflowed_type(context, self, len)
1998 impl<'a> ToExpr for TuplePatField<'a> {
1999 fn to_expr(&self) -> Option<&ast::Expr> {
2003 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2004 can_be_overflowed_pat(context, self, len)
2008 impl<'a> ToExpr for ast::StructField {
2009 fn to_expr(&self) -> Option<&ast::Expr> {
2013 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {
2018 impl<'a> ToExpr for MacroArg {
2019 fn to_expr(&self) -> Option<&ast::Expr> {
2021 MacroArg::Expr(ref expr) => Some(expr),
2026 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2028 MacroArg::Expr(ref expr) => can_be_overflowed_expr(context, expr, len),
2029 MacroArg::Ty(ref ty) => can_be_overflowed_type(context, ty, len),
2030 MacroArg::Pat(..) => false,
2031 MacroArg::Item(..) => len == 1,
2036 impl ToExpr for ast::GenericParam {
2037 fn to_expr(&self) -> Option<&ast::Expr> {
2041 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {
2046 pub fn is_method_call(expr: &ast::Expr) -> bool {
2048 ast::ExprKind::MethodCall(..) => true,
2049 ast::ExprKind::AddrOf(_, ref expr)
2050 | ast::ExprKind::Box(ref expr)
2051 | ast::ExprKind::Cast(ref expr, _)
2052 | ast::ExprKind::Try(ref expr)
2053 | ast::ExprKind::Unary(_, ref expr) => is_method_call(expr),