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.
11 // Formatting top-level items - functions, structs, enums, traits, impls.
14 use std::cmp::{min, Ordering};
18 use rustc_target::spec::abi;
19 use syntax::source_map::{self, BytePos, Span};
21 use syntax::{ast, ptr, symbol};
24 combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
25 recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented,
27 use config::{BraceStyle, Config, Density, IndentStyle};
29 format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs, rewrite_assign_rhs_with,
32 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, ListItem, Separator};
33 use macros::{rewrite_macro, MacroPosition};
35 use rewrite::{Rewrite, RewriteContext};
36 use shape::{Indent, Shape};
37 use source_map::{LineRangeUtils, SpanUtils};
40 use vertical::rewrite_with_alignment;
41 use visitor::FmtVisitor;
43 const DEFAULT_VISIBILITY: ast::Visibility = source_map::Spanned {
44 node: ast::VisibilityKind::Inherited,
45 span: source_map::DUMMY_SP,
48 fn type_annotation_separator(config: &Config) -> &str {
49 colon_spaces(config.space_before_colon(), config.space_after_colon())
52 // Statements of the form
53 // let pat: ty = init;
54 impl Rewrite for ast::Local {
55 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
57 "Local::rewrite {:?} {} {:?}",
58 self, shape.width, shape.indent
61 skip_out_of_file_lines_range!(context, self.span);
63 if contains_skip(&self.attrs) {
67 let attrs_str = self.attrs.rewrite(context, shape)?;
68 let mut result = if attrs_str.is_empty() {
71 combine_strs_with_missing_comments(
76 self.attrs.last().map(|a| a.span.hi()).unwrap(),
85 let pat_shape = shape.offset_left(4)?;
87 let pat_shape = pat_shape.sub_width(1)?;
88 let pat_str = self.pat.rewrite(context, pat_shape)?;
89 result.push_str(&pat_str);
91 // String that is placed within the assignment pattern and expression.
93 let mut infix = String::with_capacity(32);
95 if let Some(ref ty) = self.ty {
96 let separator = type_annotation_separator(context.config);
97 let indent = shape.indent + last_line_width(&result) + separator.len();
99 let budget = shape.width.checked_sub(indent.width() + 1)?;
100 let rewrite = ty.rewrite(context, Shape::legacy(budget, indent))?;
102 infix.push_str(separator);
103 infix.push_str(&rewrite);
106 if self.init.is_some() {
107 infix.push_str(" =");
113 result.push_str(&infix);
115 if let Some(ref ex) = self.init {
116 // 1 = trailing semicolon;
117 let nested_shape = shape.sub_width(1)?;
119 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
127 // FIXME convert to using rewrite style rather than visitor
128 // FIXME format modules in this style
131 keyword: &'static str,
132 abi: Cow<'static, str>,
133 vis: Option<&'a ast::Visibility>,
134 body: Vec<BodyElement<'a>>,
139 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
142 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
147 .map(|i| BodyElement::ForeignItem(i))
154 enum BodyElement<'a> {
155 // Stmt(&'a ast::Stmt),
156 // Field(&'a ast::Field),
157 // Variant(&'a ast::Variant),
158 // Item(&'a ast::Item),
159 ForeignItem(&'a ast::ForeignItem),
162 /// Represents a fn's signature.
163 pub struct FnSig<'a> {
164 decl: &'a ast::FnDecl,
165 generics: &'a ast::Generics,
167 is_async: ast::IsAsync,
168 constness: ast::Constness,
169 defaultness: ast::Defaultness,
170 unsafety: ast::Unsafety,
171 visibility: ast::Visibility,
176 decl: &'a ast::FnDecl,
177 generics: &'a ast::Generics,
178 vis: ast::Visibility,
184 is_async: ast::IsAsync::NotAsync,
185 constness: ast::Constness::NotConst,
186 defaultness: ast::Defaultness::Final,
187 unsafety: ast::Unsafety::Normal,
192 pub fn from_method_sig(
193 method_sig: &'a ast::MethodSig,
194 generics: &'a ast::Generics,
197 unsafety: method_sig.header.unsafety,
198 is_async: method_sig.header.asyncness,
199 constness: method_sig.header.constness.node,
200 defaultness: ast::Defaultness::Final,
201 abi: method_sig.header.abi,
202 decl: &*method_sig.decl,
204 visibility: DEFAULT_VISIBILITY,
209 fn_kind: &'a visit::FnKind,
210 generics: &'a ast::Generics,
211 decl: &'a ast::FnDecl,
212 defaultness: ast::Defaultness,
215 visit::FnKind::ItemFn(_, fn_header, visibility, _) => FnSig {
219 constness: fn_header.constness.node,
220 is_async: fn_header.asyncness,
222 unsafety: fn_header.unsafety,
223 visibility: visibility.clone(),
225 visit::FnKind::Method(_, method_sig, vis, _) => {
226 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
227 fn_sig.defaultness = defaultness;
228 if let Some(vis) = vis {
229 fn_sig.visibility = vis.clone();
237 fn to_str(&self, context: &RewriteContext) -> String {
238 let mut result = String::with_capacity(128);
239 // Vis defaultness constness unsafety abi.
240 result.push_str(&*format_visibility(context, &self.visibility));
241 result.push_str(format_defaultness(self.defaultness));
242 result.push_str(format_constness(self.constness));
243 result.push_str(format_unsafety(self.unsafety));
244 result.push_str(format_async(self.is_async));
245 result.push_str(&format_abi(
247 context.config.force_explicit_abi(),
254 impl<'a> FmtVisitor<'a> {
255 fn format_item(&mut self, item: &Item) {
256 self.buffer.push_str(&item.abi);
258 let snippet = self.snippet(item.span);
259 let brace_pos = snippet.find_uncommented("{").unwrap();
262 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
263 // FIXME: this skips comments between the extern keyword and the opening
265 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
266 self.block_indent = self.block_indent.block_indent(self.config);
268 if item.body.is_empty() {
269 self.format_missing_no_indent(item.span.hi() - BytePos(1));
270 self.block_indent = self.block_indent.block_unindent(self.config);
271 let indent_str = self.block_indent.to_string(self.config);
272 self.push_str(&indent_str);
274 for item in &item.body {
275 self.format_body_element(item);
278 self.block_indent = self.block_indent.block_unindent(self.config);
279 self.format_missing_with_indent(item.span.hi() - BytePos(1));
284 self.last_pos = item.span.hi();
287 fn format_body_element(&mut self, element: &BodyElement) {
289 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
293 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
294 let item = Item::from_foreign_mod(fm, span, self.config);
295 self.format_item(&item);
298 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
299 let rewrite = item.rewrite(&self.get_context(), self.shape());
300 self.push_rewrite(item.span(), rewrite);
301 self.last_pos = item.span.hi();
311 inner_attrs: Option<&[ast::Attribute]>,
312 ) -> Option<String> {
313 let context = self.get_context();
315 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
317 let (mut result, force_newline_brace) =
318 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
321 if self.config.brace_style() == BraceStyle::AlwaysNextLine
322 || force_newline_brace
323 || last_line_width(&result) + 2 > self.shape().width
325 newline_brace = true;
326 } else if !result.contains('\n') {
327 newline_brace = false;
330 // Prepare for the function body by possibly adding a newline and
332 // FIXME we'll miss anything between the end of the signature and the
333 // start of the body, but we need more spans from the compiler to solve
336 result.push_str(&indent.to_string_with_newline(self.config));
341 self.single_line_fn(&result, block, inner_attrs)
342 .or_else(|| Some(result))
345 pub fn rewrite_required_fn(
349 sig: &ast::MethodSig,
350 generics: &ast::Generics,
352 ) -> Option<String> {
353 // Drop semicolon or it will be interpreted as comment.
354 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
355 let context = self.get_context();
357 let (mut result, _) = rewrite_fn_base(
361 &FnSig::from_method_sig(sig, generics),
367 // Re-attach semicolon
377 inner_attrs: Option<&[ast::Attribute]>,
378 ) -> Option<String> {
379 if fn_str.contains('\n') || inner_attrs.map_or(false, |a| !a.is_empty()) {
383 let source_map = self.get_context().source_map;
385 if self.config.empty_item_single_line()
386 && is_empty_block(block, None, source_map)
387 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
389 return Some(format!("{}{{}}", fn_str));
392 if self.config.fn_single_line() && is_simple_block_stmt(block, None, source_map) {
394 if let Some(stmt) = block.stmts.first() {
395 match stmt_expr(stmt) {
397 let suffix = if semicolon_for_expr(&self.get_context(), e) {
403 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
405 .or_else(|| Some(self.snippet(e.span).to_owned()))
407 None => stmt.rewrite(&self.get_context(), self.shape()),
414 if let Some(res) = rewrite {
415 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
416 if !res.contains('\n') && width <= self.config.max_width() {
417 return Some(format!("{}{{ {} }}", fn_str, res));
425 pub fn visit_static(&mut self, static_parts: &StaticParts) {
426 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
427 self.push_rewrite(static_parts.span, rewrite);
430 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
431 let is_tuple = struct_parts.def.is_tuple();
432 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
433 .map(|s| if is_tuple { s + ";" } else { s });
434 self.push_rewrite(struct_parts.span, rewrite);
440 vis: &ast::Visibility,
441 enum_def: &ast::EnumDef,
442 generics: &ast::Generics,
445 let enum_header = format_header(&self.get_context(), "enum ", ident, vis);
446 self.push_str(&enum_header);
448 let enum_snippet = self.snippet(span);
449 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
450 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
451 let generics_str = format_generics(
454 self.config.brace_style(),
455 if enum_def.variants.is_empty() {
456 BracePos::ForceSameLine
461 mk_sp(span.lo(), body_start),
462 last_line_width(&enum_header),
464 self.push_str(&generics_str);
466 self.last_pos = body_start;
468 match self.format_variant_list(enum_def, body_start, span.hi()) {
469 Some(ref s) if enum_def.variants.is_empty() => self.push_str(s),
471 self.push_rewrite(mk_sp(body_start, span.hi()), rw);
472 self.block_indent = self.block_indent.block_unindent(self.config);
477 // Format the body of an enum definition
478 fn format_variant_list(
480 enum_def: &ast::EnumDef,
483 ) -> Option<String> {
484 if enum_def.variants.is_empty() {
485 let mut buffer = String::with_capacity(128);
487 let span = mk_sp(body_lo, body_hi - BytePos(1));
488 format_empty_struct_or_tuple(
498 let mut result = String::with_capacity(1024);
499 let original_offset = self.block_indent;
500 self.block_indent = self.block_indent.block_indent(self.config);
502 let itemize_list_with = |one_line_width: usize| {
504 self.snippet_provider,
505 enum_def.variants.iter(),
509 if !f.node.attrs.is_empty() {
510 f.node.attrs[0].span.lo()
516 |f| self.format_variant(f, one_line_width),
522 let mut items: Vec<_> =
523 itemize_list_with(self.config.width_heuristics().struct_variant_width);
524 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
525 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
526 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
527 if has_multiline_variant && has_single_line_variant {
528 items = itemize_list_with(0);
531 let shape = self.shape().sub_width(2)?;
532 let fmt = ListFormatting::new(shape, self.config)
533 .trailing_separator(self.config.trailing_comma())
534 .preserve_newline(true);
536 let list = write_list(&items, &fmt)?;
537 result.push_str(&list);
538 result.push_str(&original_offset.to_string_with_newline(self.config));
543 // Variant of an enum.
544 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
545 if contains_skip(&field.node.attrs) {
546 let lo = field.node.attrs[0].span.lo();
547 let span = mk_sp(lo, field.span.hi());
548 return Some(self.snippet(span).to_owned());
551 let context = self.get_context();
553 let shape = self.shape().sub_width(1)?;
554 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
559 .map_or(field.span.lo(), |attr| attr.span.hi());
560 let span = mk_sp(lo, field.span.lo());
562 let variant_body = match field.node.data {
563 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
565 &StructParts::from_variant(field),
567 Some(one_line_width),
569 ast::VariantData::Unit(..) => {
570 if let Some(ref expr) = field.node.disr_expr {
571 let lhs = format!("{} =", rewrite_ident(&context, field.node.ident));
572 rewrite_assign_rhs(&context, lhs, &*expr.value, shape)?
574 rewrite_ident(&context, field.node.ident).to_owned()
579 combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
582 fn visit_impl_items(&mut self, items: &[ast::ImplItem]) {
583 if self.get_context().config.reorder_impl_items() {
584 // Create visitor for each items, then reorder them.
585 let mut buffer = vec![];
587 self.visit_impl_item(item);
588 buffer.push((self.buffer.clone(), item.clone()));
591 // type -> existential -> const -> macro -> method
592 use ast::ImplItemKind::*;
593 fn need_empty_line(a: &ast::ImplItemKind, b: &ast::ImplItemKind) -> bool {
596 | (Const(..), Const(..))
597 | (Existential(..), Existential(..)) => false,
602 buffer.sort_by(|(_, a), (_, b)| match (&a.node, &b.node) {
604 | (Const(..), Const(..))
605 | (Macro(..), Macro(..))
606 | (Existential(..), Existential(..)) => a.ident.as_str().cmp(&b.ident.as_str()),
607 (Method(..), Method(..)) => a.span.lo().cmp(&b.span.lo()),
608 (Type(..), _) => Ordering::Less,
609 (_, Type(..)) => Ordering::Greater,
610 (Existential(..), _) => Ordering::Less,
611 (_, Existential(..)) => Ordering::Greater,
612 (Const(..), _) => Ordering::Less,
613 (_, Const(..)) => Ordering::Greater,
614 (Macro(..), _) => Ordering::Less,
615 (_, Macro(..)) => Ordering::Greater,
617 let mut prev_kind = None;
618 for (buf, item) in buffer {
619 // Make sure that there are at least a single empty line between
620 // different impl items.
623 .map_or(false, |prev_kind| need_empty_line(prev_kind, &item.node))
627 let indent_str = self.block_indent.to_string_with_newline(self.config);
628 self.push_str(&indent_str);
629 self.push_str(buf.trim());
630 prev_kind = Some(item.node.clone());
634 self.visit_impl_item(item);
641 context: &RewriteContext,
644 where_span_end: Option<BytePos>,
645 ) -> Option<String> {
646 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
647 let mut result = String::with_capacity(128);
648 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
649 let sep = offset.to_string_with_newline(context.config);
650 result.push_str(&ref_and_type);
652 let where_budget = if result.contains('\n') {
653 context.config.max_width()
655 context.budget(last_line_width(&result))
658 let mut option = WhereClauseOption::snuggled(&ref_and_type);
659 let snippet = context.snippet(item.span);
660 let open_pos = snippet.find_uncommented("{")? + 1;
661 if !contains_comment(&snippet[open_pos..])
663 && generics.where_clause.predicates.len() == 1
664 && !result.contains('\n')
666 option.suppress_comma();
668 option.compress_where();
671 let where_clause_str = rewrite_where_clause(
673 &generics.where_clause,
674 context.config.brace_style(),
675 Shape::legacy(where_budget, offset.block_only()),
684 // If there is no where clause, we may have missing comments between the trait name and
685 // the opening brace.
686 if generics.where_clause.predicates.is_empty() {
687 if let Some(hi) = where_span_end {
688 match recover_missing_comment_in_span(
689 mk_sp(self_ty.span.hi(), hi),
690 Shape::indented(offset, context.config),
692 last_line_width(&result),
694 Some(ref missing_comment) if !missing_comment.is_empty() => {
695 result.push_str(missing_comment);
702 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
703 result.push_str(&where_clause_str);
704 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
705 // if the where_clause contains extra comments AND
706 // there is only one where clause predicate
707 // recover the suppressed comma in single line where_clause formatting
708 if generics.where_clause.predicates.len() == 1 {
709 result.push_str(",");
711 result.push_str(&format!("{}{{{}}}", &sep, &sep));
713 result.push_str(" {}");
718 result.push_str(&where_clause_str);
720 let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
721 match context.config.brace_style() {
722 _ if need_newline => result.push_str(&sep),
723 BraceStyle::AlwaysNextLine => result.push_str(&sep),
724 BraceStyle::PreferSameLine => result.push(' '),
725 BraceStyle::SameLineWhere => {
726 if !where_clause_str.is_empty() {
727 result.push_str(&sep);
736 let snippet = context.snippet(item.span);
737 let open_pos = snippet.find_uncommented("{")? + 1;
739 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
740 let mut visitor = FmtVisitor::from_context(context);
741 let item_indent = offset.block_only().block_indent(context.config);
742 visitor.block_indent = item_indent;
743 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
745 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
746 visitor.visit_impl_items(items);
748 visitor.format_missing(item.span.hi() - BytePos(1));
750 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
751 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
753 result.push_str(&inner_indent_str);
754 result.push_str(visitor.buffer.to_string().trim());
755 result.push_str(&outer_indent_str);
758 if result.ends_with('{') && !context.config.empty_item_single_line() {
759 result.push_str(&sep);
769 fn is_impl_single_line(
770 context: &RewriteContext,
771 items: &[ast::ImplItem],
773 where_clause_str: &str,
776 let snippet = context.snippet(item.span);
777 let open_pos = snippet.find_uncommented("{")? + 1;
780 context.config.empty_item_single_line()
782 && !result.contains('\n')
783 && result.len() + where_clause_str.len() <= context.config.max_width()
784 && !contains_comment(&snippet[open_pos..]),
788 fn format_impl_ref_and_type(
789 context: &RewriteContext,
792 ) -> Option<String> {
793 if let ast::ItemKind::Impl(
803 let mut result = String::with_capacity(128);
805 result.push_str(&format_visibility(context, &item.vis));
806 result.push_str(format_defaultness(defaultness));
807 result.push_str(format_unsafety(unsafety));
809 let shape = generics_shape_from_config(
811 Shape::indented(offset + last_line_width(&result), context.config),
814 let generics_str = rewrite_generics(context, "impl", generics, shape)?;
815 result.push_str(&generics_str);
817 let polarity_str = if polarity == ast::ImplPolarity::Negative {
823 if let Some(ref trait_ref) = *trait_ref {
824 let result_len = last_line_width(&result);
825 result.push_str(&rewrite_trait_ref(
834 // Try to put the self type in a single line.
836 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
837 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
838 // If there is no where clause adapt budget for type formatting to take space and curly
839 // brace into account.
840 match context.config.brace_style() {
841 BraceStyle::AlwaysNextLine => 0,
847 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
848 // 1 = space before the type.
849 let budget = context.budget(used_space + 1);
850 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
851 if !self_ty_str.contains('\n') {
852 if trait_ref.is_some() {
853 result.push_str(" for ");
857 result.push_str(&self_ty_str);
862 // Couldn't fit the self type on a single line, put it on a new line.
864 // Add indentation of one additional tab.
865 let new_line_offset = offset.block_indent(context.config);
866 result.push_str(&new_line_offset.to_string(context.config));
867 if trait_ref.is_some() {
868 result.push_str("for ");
870 let budget = context.budget(last_line_width(&result));
871 let type_offset = match context.config.indent_style() {
872 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
873 IndentStyle::Block => new_line_offset,
875 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
882 fn rewrite_trait_ref(
883 context: &RewriteContext,
884 trait_ref: &ast::TraitRef,
888 ) -> Option<String> {
889 // 1 = space between generics and trait_ref
890 let used_space = 1 + polarity_str.len() + result_len;
891 let shape = Shape::indented(offset + used_space, context.config);
892 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
893 if !trait_ref_str.contains('\n') {
894 return Some(format!(" {}{}", polarity_str, &trait_ref_str));
897 // We could not make enough space for trait_ref, so put it on new line.
898 let offset = offset.block_indent(context.config);
899 let shape = Shape::indented(offset, context.config);
900 let trait_ref_str = trait_ref.rewrite(context, shape)?;
903 &offset.to_string_with_newline(context.config),
909 pub struct StructParts<'a> {
912 vis: &'a ast::Visibility,
913 def: &'a ast::VariantData,
914 generics: Option<&'a ast::Generics>,
918 impl<'a> StructParts<'a> {
919 fn format_header(&self, context: &RewriteContext) -> String {
920 format_header(context, self.prefix, self.ident, self.vis)
923 fn from_variant(variant: &'a ast::Variant) -> Self {
926 ident: variant.node.ident,
927 vis: &DEFAULT_VISIBILITY,
928 def: &variant.node.data,
934 pub fn from_item(item: &'a ast::Item) -> Self {
935 let (prefix, def, generics) = match item.node {
936 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
937 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
945 generics: Some(generics),
952 context: &RewriteContext,
953 struct_parts: &StructParts,
955 one_line_width: Option<usize>,
956 ) -> Option<String> {
957 match *struct_parts.def {
958 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
959 ast::VariantData::Tuple(ref fields, _) => {
960 format_tuple_struct(context, struct_parts, fields, offset)
962 ast::VariantData::Struct(ref fields, _) => {
963 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
968 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
969 if let ast::ItemKind::Trait(
977 let mut result = String::with_capacity(128);
978 let header = format!(
980 format_visibility(context, &item.vis),
981 format_unsafety(unsafety),
982 format_auto(is_auto),
984 result.push_str(&header);
986 let body_lo = context.snippet_provider.span_after(item.span, "{");
988 let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
990 rewrite_generics(context, rewrite_ident(context, item.ident), generics, shape)?;
991 result.push_str(&generics_str);
993 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
994 if !generic_bounds.is_empty() {
995 let ident_hi = context
997 .span_after(item.span, &item.ident.as_str());
998 let bound_hi = generic_bounds.last().unwrap().span().hi();
999 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
1000 if contains_comment(snippet) {
1004 result = rewrite_assign_rhs_with(
1009 RhsTactics::ForceNextLineWithoutIndent,
1013 // Rewrite where clause.
1014 if !generics.where_clause.predicates.is_empty() {
1015 let where_density = if context.config.indent_style() == IndentStyle::Block {
1021 let where_budget = context.budget(last_line_width(&result));
1022 let pos_before_where = if generic_bounds.is_empty() {
1023 generics.where_clause.span.lo()
1025 generic_bounds[generic_bounds.len() - 1].span().hi()
1027 let option = WhereClauseOption::snuggled(&generics_str);
1028 let where_clause_str = rewrite_where_clause(
1030 &generics.where_clause,
1031 context.config.brace_style(),
1032 Shape::legacy(where_budget, offset.block_only()),
1040 // If the where clause cannot fit on the same line,
1041 // put the where clause on a new line
1042 if !where_clause_str.contains('\n')
1043 && last_line_width(&result) + where_clause_str.len() + offset.width()
1044 > context.config.comment_width()
1046 let width = offset.block_indent + context.config.tab_spaces() - 1;
1047 let where_indent = Indent::new(0, width);
1048 result.push_str(&where_indent.to_string_with_newline(context.config));
1050 result.push_str(&where_clause_str);
1052 let item_snippet = context.snippet(item.span);
1053 if let Some(lo) = item_snippet.find('/') {
1055 let comment_hi = body_lo - BytePos(1);
1056 let comment_lo = item.span.lo() + BytePos(lo as u32);
1057 if comment_lo < comment_hi {
1058 match recover_missing_comment_in_span(
1059 mk_sp(comment_lo, comment_hi),
1060 Shape::indented(offset, context.config),
1062 last_line_width(&result),
1064 Some(ref missing_comment) if !missing_comment.is_empty() => {
1065 result.push_str(missing_comment);
1073 match context.config.brace_style() {
1074 _ if last_line_contains_single_line_comment(&result)
1075 || last_line_width(&result) + 2 > context.budget(offset.width()) =>
1077 result.push_str(&offset.to_string_with_newline(context.config));
1079 BraceStyle::AlwaysNextLine => {
1080 result.push_str(&offset.to_string_with_newline(context.config));
1082 BraceStyle::PreferSameLine => result.push(' '),
1083 BraceStyle::SameLineWhere => {
1084 if result.contains('\n')
1085 || (!generics.where_clause.predicates.is_empty() && !trait_items.is_empty())
1087 result.push_str(&offset.to_string_with_newline(context.config));
1095 let snippet = context.snippet(item.span);
1096 let open_pos = snippet.find_uncommented("{")? + 1;
1098 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1099 let mut visitor = FmtVisitor::from_context(context);
1100 visitor.block_indent = offset.block_only().block_indent(context.config);
1101 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1103 for item in trait_items {
1104 visitor.visit_trait_item(item);
1107 visitor.format_missing(item.span.hi() - BytePos(1));
1109 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
1110 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
1112 result.push_str(&inner_indent_str);
1113 result.push_str(visitor.buffer.to_string().trim());
1114 result.push_str(&outer_indent_str);
1115 } else if result.contains('\n') {
1126 pub fn format_trait_alias(
1127 context: &RewriteContext,
1129 generics: &ast::Generics,
1130 generic_bounds: &ast::GenericBounds,
1132 ) -> Option<String> {
1133 let alias = rewrite_ident(context, ident);
1134 // 6 = "trait ", 2 = " ="
1135 let g_shape = shape.offset_left(6)?.sub_width(2)?;
1136 let generics_str = rewrite_generics(context, &alias, generics, g_shape)?;
1137 let lhs = format!("trait {} =", generics_str);
1139 rewrite_assign_rhs(context, lhs, generic_bounds, shape.sub_width(1)?).map(|s| s + ";")
1142 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1143 let header_str = format_header(context, p.prefix, p.ident, p.vis);
1144 let generics_str = if let Some(generics) = p.generics {
1145 let hi = if generics.where_clause.predicates.is_empty() {
1148 generics.where_clause.span.hi()
1153 context.config.brace_style(),
1156 mk_sp(generics.span.lo(), hi),
1157 last_line_width(&header_str),
1162 Some(format!("{}{};", header_str, generics_str))
1165 pub fn format_struct_struct(
1166 context: &RewriteContext,
1167 struct_parts: &StructParts,
1168 fields: &[ast::StructField],
1170 one_line_width: Option<usize>,
1171 ) -> Option<String> {
1172 let mut result = String::with_capacity(1024);
1173 let span = struct_parts.span;
1175 let header_str = struct_parts.format_header(context);
1176 result.push_str(&header_str);
1178 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1179 let body_lo = context.snippet_provider.span_after(span, "{");
1181 let generics_str = match struct_parts.generics {
1182 Some(g) => format_generics(
1185 context.config.brace_style(),
1186 if fields.is_empty() {
1187 BracePos::ForceSameLine
1192 mk_sp(header_hi, body_lo),
1193 last_line_width(&result),
1196 // 3 = ` {}`, 2 = ` {`.
1197 let overhead = if fields.is_empty() { 3 } else { 2 };
1198 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1199 || context.config.max_width() < overhead + result.len()
1201 format!("\n{}{{", offset.block_only().to_string(context.config))
1208 let overhead = if fields.is_empty() { 1 } else { 0 };
1209 let total_width = result.len() + generics_str.len() + overhead;
1210 if !generics_str.is_empty()
1211 && !generics_str.contains('\n')
1212 && total_width > context.config.max_width()
1215 result.push_str(&offset.to_string(context.config));
1216 result.push_str(generics_str.trim_left());
1218 result.push_str(&generics_str);
1221 if fields.is_empty() {
1222 let inner_span = mk_sp(body_lo, span.hi() - BytePos(1));
1223 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "", "}");
1224 return Some(result);
1228 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1229 let one_line_budget =
1230 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1232 let items_str = rewrite_with_alignment(
1235 Shape::indented(offset, context.config).sub_width(1)?,
1236 mk_sp(body_lo, span.hi()),
1240 if !items_str.contains('\n')
1241 && !result.contains('\n')
1242 && items_str.len() <= one_line_budget
1243 && !last_line_contains_single_line_comment(&items_str)
1245 Some(format!("{} {} }}", result, items_str))
1251 .block_indent(context.config)
1252 .to_string(context.config),
1254 offset.to_string(context.config)
1259 fn get_bytepos_after_visibility(vis: &ast::Visibility, default_span: Span) -> BytePos {
1261 ast::VisibilityKind::Crate(..) | ast::VisibilityKind::Restricted { .. } => vis.span.hi(),
1262 _ => default_span.lo(),
1266 // Format tuple or struct without any fields. We need to make sure that the comments
1267 // inside the delimiters are preserved.
1268 fn format_empty_struct_or_tuple(
1269 context: &RewriteContext,
1272 result: &mut String,
1276 // 3 = " {}" or "();"
1277 let used_width = last_line_used_width(&result, offset.width()) + 3;
1278 if used_width > context.config.max_width() {
1279 result.push_str(&offset.to_string_with_newline(context.config))
1281 result.push_str(opener);
1282 match rewrite_missing_comment(span, Shape::indented(offset, context.config), context) {
1283 Some(ref s) if s.is_empty() => (),
1285 if !is_single_line(s) || first_line_contains_single_line_comment(s) {
1286 let nested_indent_str = offset
1287 .block_indent(context.config)
1288 .to_string_with_newline(context.config);
1289 result.push_str(&nested_indent_str);
1292 if last_line_contains_single_line_comment(s) {
1293 result.push_str(&offset.to_string_with_newline(context.config));
1296 None => result.push_str(context.snippet(span)),
1298 result.push_str(closer);
1301 fn format_tuple_struct(
1302 context: &RewriteContext,
1303 struct_parts: &StructParts,
1304 fields: &[ast::StructField],
1306 ) -> Option<String> {
1307 let mut result = String::with_capacity(1024);
1308 let span = struct_parts.span;
1310 let header_str = struct_parts.format_header(context);
1311 result.push_str(&header_str);
1313 let body_lo = if fields.is_empty() {
1314 let lo = get_bytepos_after_visibility(struct_parts.vis, span);
1317 .span_after(mk_sp(lo, span.hi()), "(")
1321 let body_hi = if fields.is_empty() {
1324 .span_after(mk_sp(body_lo, span.hi()), ")")
1326 // This is a dirty hack to work around a missing `)` from the span of the last field.
1327 let last_arg_span = fields[fields.len() - 1].span;
1330 .opt_span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1331 .unwrap_or(last_arg_span.hi())
1334 let where_clause_str = match struct_parts.generics {
1336 let budget = context.budget(last_line_width(&header_str));
1337 let shape = Shape::legacy(budget, offset);
1338 let generics_str = rewrite_generics(context, "", generics, shape)?;
1339 result.push_str(&generics_str);
1341 let where_budget = context.budget(last_line_width(&result));
1342 let option = WhereClauseOption::new(true, false);
1343 rewrite_where_clause(
1345 &generics.where_clause,
1346 context.config.brace_style(),
1347 Shape::legacy(where_budget, offset.block_only()),
1348 Density::Compressed,
1356 None => "".to_owned(),
1359 if fields.is_empty() {
1360 let body_hi = context
1362 .span_before(mk_sp(body_lo, span.hi()), ")");
1363 let inner_span = mk_sp(body_lo, body_hi);
1364 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "(", ")");
1366 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1367 let fields = &fields.iter().collect::<Vec<_>>();
1368 result = overflow::rewrite_with_parens(
1374 context.config.width_heuristics().fn_call_width,
1379 if !where_clause_str.is_empty()
1380 && !where_clause_str.contains('\n')
1381 && (result.contains('\n')
1382 || offset.block_indent + result.len() + where_clause_str.len() + 1
1383 > context.config.max_width())
1385 // We need to put the where clause on a new line, but we didn't
1386 // know that earlier, so the where clause will not be indented properly.
1389 &(offset.block_only() + (context.config.tab_spaces() - 1)).to_string(context.config),
1392 result.push_str(&where_clause_str);
1397 fn rewrite_type_prefix(
1398 context: &RewriteContext,
1402 generics: &ast::Generics,
1403 ) -> Option<String> {
1404 let mut result = String::with_capacity(128);
1405 result.push_str(prefix);
1406 let ident_str = rewrite_ident(context, ident);
1409 if generics.params.is_empty() {
1410 result.push_str(ident_str)
1412 let g_shape = Shape::indented(indent, context.config)
1413 .offset_left(result.len())?
1415 let generics_str = rewrite_generics(context, ident_str, generics, g_shape)?;
1416 result.push_str(&generics_str);
1419 let where_budget = context.budget(last_line_width(&result));
1420 let option = WhereClauseOption::snuggled(&result);
1421 let where_clause_str = rewrite_where_clause(
1423 &generics.where_clause,
1424 context.config.brace_style(),
1425 Shape::legacy(where_budget, indent),
1433 result.push_str(&where_clause_str);
1438 fn rewrite_type_item<R: Rewrite>(
1439 context: &RewriteContext,
1445 generics: &ast::Generics,
1446 vis: &ast::Visibility,
1447 ) -> Option<String> {
1448 let mut result = String::with_capacity(128);
1449 result.push_str(&rewrite_type_prefix(
1452 &format!("{}{} ", format_visibility(context, vis), prefix),
1457 if generics.where_clause.predicates.is_empty() {
1458 result.push_str(suffix);
1460 result.push_str(&indent.to_string_with_newline(context.config));
1461 result.push_str(suffix.trim_left());
1465 let rhs_shape = Shape::indented(indent, context.config).sub_width(1)?;
1466 rewrite_assign_rhs(context, result, rhs, rhs_shape).map(|s| s + ";")
1469 pub fn rewrite_type_alias(
1470 context: &RewriteContext,
1474 generics: &ast::Generics,
1475 vis: &ast::Visibility,
1476 ) -> Option<String> {
1477 rewrite_type_item(context, indent, "type", " =", ident, ty, generics, vis)
1480 pub fn rewrite_existential_type(
1481 context: &RewriteContext,
1484 generic_bounds: &ast::GenericBounds,
1485 generics: &ast::Generics,
1486 vis: &ast::Visibility,
1487 ) -> Option<String> {
1500 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1502 if config.space_before_colon() { " " } else { "" },
1503 if config.space_after_colon() { " " } else { "" },
1507 pub fn rewrite_struct_field_prefix(
1508 context: &RewriteContext,
1509 field: &ast::StructField,
1510 ) -> Option<String> {
1511 let vis = format_visibility(context, &field.vis);
1512 let type_annotation_spacing = type_annotation_spacing(context.config);
1513 Some(match field.ident {
1514 Some(name) => format!(
1517 rewrite_ident(context, name),
1518 type_annotation_spacing.0
1520 None => format!("{}", vis),
1524 impl Rewrite for ast::StructField {
1525 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1526 rewrite_struct_field(context, self, shape, 0)
1530 pub fn rewrite_struct_field(
1531 context: &RewriteContext,
1532 field: &ast::StructField,
1534 lhs_max_width: usize,
1535 ) -> Option<String> {
1536 if contains_skip(&field.attrs) {
1537 return Some(context.snippet(field.span()).to_owned());
1540 let type_annotation_spacing = type_annotation_spacing(context.config);
1541 let prefix = rewrite_struct_field_prefix(context, field)?;
1543 let attrs_str = field.attrs.rewrite(context, shape)?;
1544 let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
1545 let missing_span = if field.attrs.is_empty() {
1546 mk_sp(field.span.lo(), field.span.lo())
1548 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1550 let mut spacing = String::from(if field.ident.is_some() {
1551 type_annotation_spacing.1
1555 // Try to put everything on a single line.
1556 let attr_prefix = combine_strs_with_missing_comments(
1564 let overhead = last_line_width(&attr_prefix);
1565 let lhs_offset = lhs_max_width.saturating_sub(overhead);
1566 for _ in 0..lhs_offset {
1569 // In this extreme case we will be missing a space betweeen an attribute and a field.
1570 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1574 .offset_left(overhead + spacing.len())
1575 .and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
1576 if let Some(ref ty) = orig_ty {
1577 if !ty.contains('\n') {
1578 return Some(attr_prefix + &spacing + ty);
1582 let is_prefix_empty = prefix.is_empty();
1583 // We must use multiline. We are going to put attributes and a field on different lines.
1584 let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, shape)?;
1585 // Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
1586 let field_str = if is_prefix_empty {
1587 field_str.trim_left()
1591 combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
1594 pub struct StaticParts<'a> {
1596 vis: &'a ast::Visibility,
1599 mutability: ast::Mutability,
1600 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1601 defaultness: Option<ast::Defaultness>,
1605 impl<'a> StaticParts<'a> {
1606 pub fn from_item(item: &'a ast::Item) -> Self {
1607 let (prefix, ty, mutability, expr) = match item.node {
1608 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1609 ast::ItemKind::Const(ref ty, ref expr) => {
1610 ("const", ty, ast::Mutability::Immutable, expr)
1612 _ => unreachable!(),
1620 expr_opt: Some(expr),
1626 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1627 let (ty, expr_opt) = match ti.node {
1628 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1629 _ => unreachable!(),
1633 vis: &DEFAULT_VISIBILITY,
1636 mutability: ast::Mutability::Immutable,
1637 expr_opt: expr_opt.as_ref(),
1643 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1644 let (ty, expr) = match ii.node {
1645 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1646 _ => unreachable!(),
1653 mutability: ast::Mutability::Immutable,
1654 expr_opt: Some(expr),
1655 defaultness: Some(ii.defaultness),
1662 context: &RewriteContext,
1663 static_parts: &StaticParts,
1665 ) -> Option<String> {
1666 let colon = colon_spaces(
1667 context.config.space_before_colon(),
1668 context.config.space_after_colon(),
1670 let mut prefix = format!(
1672 format_visibility(context, static_parts.vis),
1673 static_parts.defaultness.map_or("", format_defaultness),
1674 static_parts.prefix,
1675 format_mutability(static_parts.mutability),
1681 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1682 let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
1683 Some(ty_str) => ty_str,
1685 if prefix.ends_with(' ') {
1688 let nested_indent = offset.block_indent(context.config);
1689 let nested_shape = Shape::indented(nested_indent, context.config);
1690 let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
1693 nested_indent.to_string_with_newline(context.config),
1699 if let Some(expr) = static_parts.expr_opt {
1700 let lhs = format!("{}{} =", prefix, ty_str);
1702 let remaining_width = context.budget(offset.block_indent + 1);
1707 Shape::legacy(remaining_width, offset.block_only()),
1708 ).and_then(|res| recover_comment_removed(res, static_parts.span, context))
1709 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1711 Some(format!("{}{};", prefix, ty_str))
1715 pub fn rewrite_associated_type(
1717 ty_opt: Option<&ptr::P<ast::Ty>>,
1718 generic_bounds_opt: Option<&ast::GenericBounds>,
1719 context: &RewriteContext,
1721 ) -> Option<String> {
1722 let prefix = format!("type {}", rewrite_ident(context, ident));
1724 let type_bounds_str = if let Some(bounds) = generic_bounds_opt {
1725 if bounds.is_empty() {
1729 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1730 bounds.rewrite(context, shape).map(|s| format!(": {}", s))?
1736 if let Some(ty) = ty_opt {
1738 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1739 let lhs = format!("{}{} =", prefix, type_bounds_str);
1740 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1742 Some(format!("{}{};", prefix, type_bounds_str))
1746 pub fn rewrite_existential_impl_type(
1747 context: &RewriteContext,
1749 generic_bounds: &ast::GenericBounds,
1751 ) -> Option<String> {
1752 rewrite_associated_type(ident, None, Some(generic_bounds), context, indent)
1753 .map(|s| format!("existential {}", s))
1756 pub fn rewrite_associated_impl_type(
1758 defaultness: ast::Defaultness,
1759 ty_opt: Option<&ptr::P<ast::Ty>>,
1760 context: &RewriteContext,
1762 ) -> Option<String> {
1763 let result = rewrite_associated_type(ident, ty_opt, None, context, indent)?;
1766 ast::Defaultness::Default => Some(format!("default {}", result)),
1771 impl Rewrite for ast::FunctionRetTy {
1772 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1774 ast::FunctionRetTy::Default(_) => Some(String::new()),
1775 ast::FunctionRetTy::Ty(ref ty) => {
1776 let inner_width = shape.width.checked_sub(3)?;
1777 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1778 .map(|r| format!("-> {}", r))
1784 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1786 ast::TyKind::Infer => {
1787 let original = context.snippet(ty.span);
1794 impl Rewrite for ast::Arg {
1795 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1796 if is_named_arg(self) {
1797 let mut result = self
1799 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1801 if !is_empty_infer(context, &*self.ty) {
1802 if context.config.space_before_colon() {
1803 result.push_str(" ");
1805 result.push_str(":");
1806 if context.config.space_after_colon() {
1807 result.push_str(" ");
1809 let overhead = last_line_width(&result);
1810 let max_width = shape.width.checked_sub(overhead)?;
1813 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1814 result.push_str(&ty_str);
1819 self.ty.rewrite(context, shape)
1824 fn rewrite_explicit_self(
1825 explicit_self: &ast::ExplicitSelf,
1827 context: &RewriteContext,
1828 ) -> Option<String> {
1829 match explicit_self.node {
1830 ast::SelfKind::Region(lt, m) => {
1831 let mut_str = format_mutability(m);
1834 let lifetime_str = l.rewrite(
1836 Shape::legacy(context.config.max_width(), Indent::empty()),
1838 Some(format!("&{} {}self", lifetime_str, mut_str))
1840 None => Some(format!("&{}self", mut_str)),
1843 ast::SelfKind::Explicit(ref ty, _) => {
1844 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1846 let mutability = explicit_self_mutability(&args[0]);
1847 let type_str = ty.rewrite(
1849 Shape::legacy(context.config.max_width(), Indent::empty()),
1854 format_mutability(mutability),
1858 ast::SelfKind::Value(_) => {
1859 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1861 let mutability = explicit_self_mutability(&args[0]);
1863 Some(format!("{}self", format_mutability(mutability)))
1868 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1869 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1870 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1871 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1878 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1879 if is_named_arg(arg) {
1886 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1888 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1889 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1890 _ => arg.ty.span.hi(),
1894 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1895 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1896 ident != symbol::keywords::Invalid.ident()
1902 // Return type is (result, force_new_line_for_brace)
1904 context: &RewriteContext,
1909 newline_brace: bool,
1911 ) -> Option<(String, bool)> {
1912 let mut force_new_line_for_brace = false;
1914 let where_clause = &fn_sig.generics.where_clause;
1916 let mut result = String::with_capacity(1024);
1917 result.push_str(&fn_sig.to_str(context));
1920 result.push_str("fn ");
1923 let overhead = if has_body && !newline_brace {
1930 let used_width = last_line_used_width(&result, indent.width());
1931 let one_line_budget = context.budget(used_width + overhead);
1933 width: one_line_budget,
1937 let fd = fn_sig.decl;
1938 let generics_str = rewrite_generics(
1940 rewrite_ident(context, ident),
1944 result.push_str(&generics_str);
1946 let snuggle_angle_bracket = generics_str
1949 .map_or(false, |l| l.trim_left().len() == 1);
1951 // Note that the width and indent don't really matter, we'll re-layout the
1952 // return type later anyway.
1955 .rewrite(context, Shape::indented(indent, context.config))?;
1957 let multi_line_ret_str = ret_str.contains('\n');
1958 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1961 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1972 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1973 one_line_budget, multi_line_budget, arg_indent
1976 // Check if vertical layout was forced.
1977 if one_line_budget == 0 {
1978 if snuggle_angle_bracket {
1981 result.push_str("(");
1982 if context.config.indent_style() == IndentStyle::Visual {
1983 result.push_str(&arg_indent.to_string_with_newline(context.config));
1990 // Skip `pub(crate)`.
1991 let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
1992 // A conservative estimation, to goal is to be over all parens in generics
1993 let args_start = fn_sig
1998 .map_or(lo_after_visibility, |param| param.span().hi());
1999 let args_end = if fd.inputs.is_empty() {
2002 .span_after(mk_sp(args_start, span.hi()), ")")
2004 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
2005 context.snippet_provider.span_after(last_span, ")")
2007 let args_span = mk_sp(
2010 .span_after(mk_sp(args_start, span.hi()), "("),
2013 let arg_str = rewrite_args(
2016 fd.get_self().as_ref(),
2023 generics_str.contains('\n'),
2026 let put_args_in_block = match context.config.indent_style() {
2027 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
2029 } && !fd.inputs.is_empty();
2031 let mut args_last_line_contains_comment = false;
2032 if put_args_in_block {
2033 arg_indent = indent.block_indent(context.config);
2034 result.push_str(&arg_indent.to_string_with_newline(context.config));
2035 result.push_str(&arg_str);
2036 result.push_str(&indent.to_string_with_newline(context.config));
2039 result.push_str(&arg_str);
2040 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
2041 // Put the closing brace on the next line if it overflows the max width.
2043 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
2046 // If the last line of args contains comment, we cannot put the closing paren
2047 // on the same line.
2051 .map_or(false, |last_line| last_line.contains("//"))
2053 args_last_line_contains_comment = true;
2054 result.push_str(&arg_indent.to_string_with_newline(context.config));
2060 if let ast::FunctionRetTy::Ty(..) = fd.output {
2061 let ret_should_indent = match context.config.indent_style() {
2062 // If our args are block layout then we surely must have space.
2063 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
2064 _ if args_last_line_contains_comment => false,
2065 _ if result.contains('\n') || multi_line_ret_str => true,
2067 // If the return type would push over the max width, then put the return type on
2068 // a new line. With the +1 for the signature length an additional space between
2069 // the closing parenthesis of the argument and the arrow '->' is considered.
2070 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
2072 // If there is no where clause, take into account the space after the return type
2074 if where_clause.predicates.is_empty() {
2078 sig_length > context.config.max_width()
2081 let ret_indent = if ret_should_indent {
2082 let indent = if arg_str.is_empty() {
2083 // Aligning with non-existent args looks silly.
2084 force_new_line_for_brace = true;
2087 // FIXME: we might want to check that using the arg indent
2088 // doesn't blow our budget, and if it does, then fallback to
2089 // the where clause indent.
2093 result.push_str(&indent.to_string_with_newline(context.config));
2097 Indent::new(indent.block_indent, last_line_width(&result))
2100 if multi_line_ret_str || ret_should_indent {
2101 // Now that we know the proper indent and width, we need to
2102 // re-layout the return type.
2105 .rewrite(context, Shape::indented(ret_indent, context.config))?;
2106 result.push_str(&ret_str);
2108 result.push_str(&ret_str);
2111 // Comment between return type and the end of the decl.
2112 let snippet_lo = fd.output.span().hi();
2113 if where_clause.predicates.is_empty() {
2114 let snippet_hi = span.hi();
2115 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2116 // Try to preserve the layout of the original snippet.
2117 let original_starts_with_newline = snippet
2119 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2120 let original_ends_with_newline = snippet
2121 .rfind(|c| c != ' ')
2122 .map_or(false, |i| snippet[i..].ends_with('\n'));
2123 let snippet = snippet.trim();
2124 if !snippet.is_empty() {
2125 result.push(if original_starts_with_newline {
2130 result.push_str(snippet);
2131 if original_ends_with_newline {
2132 force_new_line_for_brace = true;
2138 let pos_before_where = match fd.output {
2139 ast::FunctionRetTy::Default(..) => args_span.hi(),
2140 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2143 let is_args_multi_lined = arg_str.contains('\n');
2145 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2146 let where_clause_str = rewrite_where_clause(
2149 context.config.brace_style(),
2150 Shape::indented(indent, context.config),
2156 is_args_multi_lined,
2158 // If there are neither where clause nor return type, we may be missing comments between
2160 if where_clause_str.is_empty() {
2161 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2162 match recover_missing_comment_in_span(
2163 mk_sp(args_span.hi(), ret_span.hi()),
2166 last_line_width(&result),
2168 Some(ref missing_comment) if !missing_comment.is_empty() => {
2169 result.push_str(missing_comment);
2170 force_new_line_for_brace = true;
2177 result.push_str(&where_clause_str);
2179 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2180 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2181 Some((result, force_new_line_for_brace))
2184 #[derive(Copy, Clone)]
2185 struct WhereClauseOption {
2186 suppress_comma: bool, // Force no trailing comma
2187 snuggle: bool, // Do not insert newline before `where`
2188 compress_where: bool, // Try single line where clause instead of vertical layout
2191 impl WhereClauseOption {
2192 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2196 compress_where: false,
2200 pub fn snuggled(current: &str) -> WhereClauseOption {
2202 suppress_comma: false,
2203 snuggle: last_line_width(current) == 1,
2204 compress_where: false,
2208 pub fn suppress_comma(&mut self) {
2209 self.suppress_comma = true
2212 pub fn compress_where(&mut self) {
2213 self.compress_where = true
2216 pub fn snuggle(&mut self) {
2222 context: &RewriteContext,
2224 explicit_self: Option<&ast::ExplicitSelf>,
2225 one_line_budget: usize,
2226 multi_line_budget: usize,
2231 generics_str_contains_newline: bool,
2232 ) -> Option<String> {
2233 let mut arg_item_strs = args
2236 arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent))
2237 .unwrap_or_else(|| context.snippet(arg.span()).to_owned())
2238 }).collect::<Vec<_>>();
2240 // Account for sugary self.
2241 // FIXME: the comment for the self argument is dropped. This is blocked
2242 // on rust issue #27522.
2243 let min_args = explicit_self
2244 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2245 .map_or(1, |self_str| {
2246 arg_item_strs[0] = self_str;
2250 // Comments between args.
2251 let mut arg_items = Vec::new();
2253 arg_items.push(ListItem::from_str(""));
2256 // FIXME(#21): if there are no args, there might still be a comment, but
2257 // without spans for the comment or parens, there is no chance of
2258 // getting it right. You also don't get to put a comment on self, unless
2260 if args.len() >= min_args || variadic {
2261 let comment_span_start = if min_args == 2 {
2262 let second_arg_start = if arg_has_pattern(&args[1]) {
2263 args[1].pat.span.lo()
2265 args[1].ty.span.lo()
2267 let reduced_span = mk_sp(span.lo(), second_arg_start);
2269 context.snippet_provider.span_after_last(reduced_span, ",")
2274 enum ArgumentKind<'a> {
2275 Regular(&'a ast::Arg),
2279 let variadic_arg = if variadic {
2280 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2281 let variadic_start =
2282 context.snippet_provider.span_after(variadic_span, "...") - BytePos(3);
2283 Some(ArgumentKind::Variadic(variadic_start))
2288 let more_items = itemize_list(
2289 context.snippet_provider,
2290 args[min_args - 1..]
2292 .map(ArgumentKind::Regular)
2293 .chain(variadic_arg),
2297 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2298 ArgumentKind::Variadic(start) => start,
2301 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2302 ArgumentKind::Variadic(start) => start + BytePos(3),
2305 ArgumentKind::Regular(..) => None,
2306 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2313 arg_items.extend(more_items);
2316 let fits_in_one_line = !generics_str_contains_newline
2317 && (arg_items.is_empty()
2318 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2320 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2321 item.item = Some(arg);
2324 let last_line_ends_with_comment = arg_items
2327 .and_then(|item| item.post_comment.as_ref())
2328 .map_or(false, |s| s.trim().starts_with("//"));
2330 let (indent, trailing_comma) = match context.config.indent_style() {
2331 IndentStyle::Block if fits_in_one_line => {
2332 (indent.block_indent(context.config), SeparatorTactic::Never)
2334 IndentStyle::Block => (
2335 indent.block_indent(context.config),
2336 context.config.trailing_comma(),
2338 IndentStyle::Visual if last_line_ends_with_comment => {
2339 (arg_indent, context.config.trailing_comma())
2341 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2344 let tactic = definitive_tactic(
2346 context.config.fn_args_density().to_list_tactic(),
2350 let budget = match tactic {
2351 DefinitiveListTactic::Horizontal => one_line_budget,
2352 _ => multi_line_budget,
2355 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2357 let trailing_separator = if variadic {
2358 SeparatorTactic::Never
2362 let fmt = ListFormatting::new(Shape::legacy(budget, indent), context.config)
2364 .trailing_separator(trailing_separator)
2365 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2366 .preserve_newline(true);
2367 write_list(&arg_items, &fmt)
2370 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2371 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2372 ident != symbol::keywords::Invalid.ident()
2378 fn compute_budgets_for_args(
2379 context: &RewriteContext,
2383 newline_brace: bool,
2385 force_vertical_layout: bool,
2386 ) -> Option<((usize, usize, Indent))> {
2388 "compute_budgets_for_args {} {:?}, {}, {}",
2394 // Try keeping everything on the same line.
2395 if !result.contains('\n') && !force_vertical_layout {
2396 // 2 = `()`, 3 = `() `, space is before ret_string.
2397 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2398 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2408 let one_line_budget = context.budget(used_space);
2410 if one_line_budget > 0 {
2412 let (indent, multi_line_budget) = match context.config.indent_style() {
2413 IndentStyle::Block => {
2414 let indent = indent.block_indent(context.config);
2415 (indent, context.budget(indent.width() + 1))
2417 IndentStyle::Visual => {
2418 let indent = indent + result.len() + 1;
2419 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2420 (indent, context.budget(multi_line_overhead))
2424 return Some((one_line_budget, multi_line_budget, indent));
2428 // Didn't work. we must force vertical layout and put args on a newline.
2429 let new_indent = indent.block_indent(context.config);
2430 let used_space = match context.config.indent_style() {
2432 IndentStyle::Block => new_indent.width() + 1,
2433 // Account for `)` and possibly ` {`.
2434 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2436 Some((0, context.budget(used_space), new_indent))
2439 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2440 let predicate_count = where_clause.predicates.len();
2442 if config.where_single_line() && predicate_count == 1 {
2445 let brace_style = config.brace_style();
2447 brace_style == BraceStyle::AlwaysNextLine
2448 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2451 fn rewrite_generics(
2452 context: &RewriteContext,
2454 generics: &ast::Generics,
2456 ) -> Option<String> {
2457 // FIXME: convert bounds to where clauses where they get too big or if
2458 // there is a where clause at all.
2460 if generics.params.is_empty() {
2461 return Some(ident.to_owned());
2464 let params = &generics.params.iter().map(|e| &*e).collect::<Vec<_>>();
2465 overflow::rewrite_with_angle_brackets(context, ident, params, shape, generics.span)
2468 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2469 match config.indent_style() {
2470 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2471 IndentStyle::Block => {
2475 .block_indent(config.tab_spaces())
2476 .with_max_width(config)
2482 fn rewrite_where_clause_rfc_style(
2483 context: &RewriteContext,
2484 where_clause: &ast::WhereClause,
2487 span_end: Option<BytePos>,
2488 span_end_before_where: BytePos,
2489 where_clause_option: WhereClauseOption,
2490 is_args_multi_line: bool,
2491 ) -> Option<String> {
2492 let block_shape = shape.block().with_max_width(context.config);
2494 let (span_before, span_after) =
2495 missing_span_before_after_where(span_end_before_where, where_clause);
2496 let (comment_before, comment_after) =
2497 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2499 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2502 block_shape.indent.to_string_with_newline(context.config)
2505 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2507 let clause_shape = clause_shape.sub_width(1)?;
2508 // each clause on one line, trailing comma (except if suppress_comma)
2509 let span_start = where_clause.predicates[0].span().lo();
2510 // If we don't have the start of the next span, then use the end of the
2511 // predicates, but that means we miss comments.
2512 let len = where_clause.predicates.len();
2513 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2514 let span_end = span_end.unwrap_or(end_of_preds);
2515 let items = itemize_list(
2516 context.snippet_provider,
2517 where_clause.predicates.iter(),
2520 |pred| pred.span().lo(),
2521 |pred| pred.span().hi(),
2522 |pred| pred.rewrite(context, clause_shape),
2527 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2528 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2529 SeparatorTactic::Never
2531 context.config.trailing_comma()
2534 // shape should be vertical only and only if we have `where_single_line` option enabled
2535 // and the number of items of the where clause is equal to 1
2536 let shape_tactic = if where_single_line {
2537 DefinitiveListTactic::Horizontal
2539 DefinitiveListTactic::Vertical
2542 let fmt = ListFormatting::new(clause_shape, context.config)
2543 .tactic(shape_tactic)
2544 .trailing_separator(comma_tactic)
2545 .preserve_newline(true);
2546 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2548 let comment_separator = |comment: &str, shape: Shape| {
2549 if comment.is_empty() {
2552 shape.indent.to_string_with_newline(context.config)
2555 let newline_before_where = comment_separator(&comment_before, shape);
2556 let newline_after_where = comment_separator(&comment_after, clause_shape);
2559 let clause_sep = if where_clause_option.compress_where
2560 && comment_before.is_empty()
2561 && comment_after.is_empty()
2562 && !preds_str.contains('\n')
2563 && 6 + preds_str.len() <= shape.width
2564 || where_single_line
2568 clause_shape.indent.to_string_with_newline(context.config)
2571 "{}{}{}where{}{}{}{}",
2574 newline_before_where,
2575 newline_after_where,
2582 fn rewrite_where_clause(
2583 context: &RewriteContext,
2584 where_clause: &ast::WhereClause,
2585 brace_style: BraceStyle,
2589 span_end: Option<BytePos>,
2590 span_end_before_where: BytePos,
2591 where_clause_option: WhereClauseOption,
2592 is_args_multi_line: bool,
2593 ) -> Option<String> {
2594 if where_clause.predicates.is_empty() {
2595 return Some(String::new());
2598 if context.config.indent_style() == IndentStyle::Block {
2599 return rewrite_where_clause_rfc_style(
2605 span_end_before_where,
2606 where_clause_option,
2611 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2613 let offset = match context.config.indent_style() {
2614 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2615 // 6 = "where ".len()
2616 IndentStyle::Visual => shape.indent + extra_indent + 6,
2618 // FIXME: if indent_style != Visual, then the budgets below might
2619 // be out by a char or two.
2621 let budget = context.config.max_width() - offset.width();
2622 let span_start = where_clause.predicates[0].span().lo();
2623 // If we don't have the start of the next span, then use the end of the
2624 // predicates, but that means we miss comments.
2625 let len = where_clause.predicates.len();
2626 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2627 let span_end = span_end.unwrap_or(end_of_preds);
2628 let items = itemize_list(
2629 context.snippet_provider,
2630 where_clause.predicates.iter(),
2633 |pred| pred.span().lo(),
2634 |pred| pred.span().hi(),
2635 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2640 let item_vec = items.collect::<Vec<_>>();
2641 // FIXME: we don't need to collect here
2642 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2644 let mut comma_tactic = context.config.trailing_comma();
2645 // Kind of a hack because we don't usually have trailing commas in where clauses.
2646 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2647 comma_tactic = SeparatorTactic::Never;
2650 let fmt = ListFormatting::new(Shape::legacy(budget, offset), context.config)
2652 .trailing_separator(comma_tactic)
2653 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2654 .preserve_newline(true);
2655 let preds_str = write_list(&item_vec, &fmt)?;
2657 let end_length = if terminator == "{" {
2658 // If the brace is on the next line we don't need to count it otherwise it needs two
2661 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2662 BraceStyle::PreferSameLine => 2,
2664 } else if terminator == "=" {
2669 if density == Density::Tall
2670 || preds_str.contains('\n')
2671 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2675 (shape.indent + extra_indent).to_string(context.config),
2679 Some(format!(" where {}", preds_str))
2683 fn missing_span_before_after_where(
2684 before_item_span_end: BytePos,
2685 where_clause: &ast::WhereClause,
2687 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2689 let pos_after_where = where_clause.span.lo() + BytePos(5);
2690 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2691 (missing_span_before, missing_span_after)
2694 fn rewrite_comments_before_after_where(
2695 context: &RewriteContext,
2696 span_before_where: Span,
2697 span_after_where: Span,
2699 ) -> Option<(String, String)> {
2700 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2701 let after_comment = rewrite_missing_comment(
2703 shape.block_indent(context.config.tab_spaces()),
2706 Some((before_comment, after_comment))
2710 context: &RewriteContext,
2713 vis: &ast::Visibility,
2717 format_visibility(context, vis),
2719 rewrite_ident(context, ident)
2723 #[derive(PartialEq, Eq, Clone, Copy)]
2731 context: &RewriteContext,
2732 generics: &ast::Generics,
2733 brace_style: BraceStyle,
2734 brace_pos: BracePos,
2738 ) -> Option<String> {
2739 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2740 let mut result = rewrite_generics(context, "", generics, shape)?;
2742 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2743 let budget = context.budget(last_line_used_width(&result, offset.width()));
2744 let mut option = WhereClauseOption::snuggled(&result);
2745 if brace_pos == BracePos::None {
2746 option.suppress_comma = true;
2748 // If the generics are not parameterized then generics.span.hi() == 0,
2749 // so we use span.lo(), which is the position after `struct Foo`.
2750 let span_end_before_where = if !generics.params.is_empty() {
2755 let where_clause_str = rewrite_where_clause(
2757 &generics.where_clause,
2759 Shape::legacy(budget, offset.block_only()),
2763 span_end_before_where,
2767 result.push_str(&where_clause_str);
2768 brace_pos == BracePos::ForceSameLine
2769 || brace_style == BraceStyle::PreferSameLine
2770 || (generics.where_clause.predicates.is_empty()
2771 && trimmed_last_line_width(&result) == 1)
2773 brace_pos == BracePos::ForceSameLine
2774 || trimmed_last_line_width(&result) == 1
2775 || brace_style != BraceStyle::AlwaysNextLine
2777 if brace_pos == BracePos::None {
2778 return Some(result);
2780 let total_used_width = last_line_used_width(&result, used_width);
2781 let remaining_budget = context.budget(total_used_width);
2782 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2783 // and hence we take the closer into account as well for one line budget.
2784 // We assume that the closer has the same length as the opener.
2785 let overhead = if brace_pos == BracePos::ForceSameLine {
2792 let forbid_same_line_brace = overhead > remaining_budget;
2793 if !forbid_same_line_brace && same_line_brace {
2797 result.push_str(&offset.block_only().to_string(context.config));
2804 impl Rewrite for ast::ForeignItem {
2805 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2806 let attrs_str = self.attrs.rewrite(context, shape)?;
2807 // Drop semicolon or it will be interpreted as comment.
2808 // FIXME: this may be a faulty span from libsyntax.
2809 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2811 let item_str = match self.node {
2812 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => rewrite_fn_base(
2816 &FnSig::new(fn_decl, generics, self.vis.clone()),
2820 ).map(|(s, _)| format!("{};", s)),
2821 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2822 // FIXME(#21): we're dropping potential comments in between the
2823 // function keywords here.
2824 let vis = format_visibility(context, &self.vis);
2825 let mut_str = if is_mutable { "mut " } else { "" };
2826 let prefix = format!(
2830 rewrite_ident(context, self.ident)
2833 rewrite_assign_rhs(context, prefix, &**ty, shape.sub_width(1)?).map(|s| s + ";")
2835 ast::ForeignItemKind::Ty => {
2836 let vis = format_visibility(context, &self.vis);
2840 rewrite_ident(context, self.ident)
2843 ast::ForeignItemKind::Macro(ref mac) => {
2844 rewrite_macro(mac, None, context, shape, MacroPosition::Item)
2848 let missing_span = if self.attrs.is_empty() {
2849 mk_sp(self.span.lo(), self.span.lo())
2851 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2853 combine_strs_with_missing_comments(
2864 /// Rewrite an inline mod.
2865 pub fn rewrite_mod(context: &RewriteContext, item: &ast::Item) -> String {
2866 let mut result = String::with_capacity(32);
2867 result.push_str(&*format_visibility(context, &item.vis));
2868 result.push_str("mod ");
2869 result.push_str(rewrite_ident(context, item.ident));
2874 /// Rewrite `extern crate foo;` WITHOUT attributes.
2875 pub fn rewrite_extern_crate(context: &RewriteContext, item: &ast::Item) -> Option<String> {
2876 assert!(is_extern_crate(item));
2877 let new_str = context.snippet(item.span);
2878 Some(if contains_comment(new_str) {
2881 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
2882 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
2886 /// Returns true for `mod foo;`, false for `mod foo { .. }`.
2887 pub fn is_mod_decl(item: &ast::Item) -> bool {
2889 ast::ItemKind::Mod(ref m) => m.inner.hi() != item.span.hi(),
2894 pub fn is_use_item(item: &ast::Item) -> bool {
2896 ast::ItemKind::Use(_) => true,
2901 pub fn is_extern_crate(item: &ast::Item) -> bool {
2903 ast::ItemKind::ExternCrate(..) => true,