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::codemap::{self, BytePos, Span};
21 use syntax::{ast, ptr, symbol};
23 use codemap::{LineRangeUtils, SpanUtils};
25 combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
26 recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented,
28 use config::{BraceStyle, Config, Density, IndentStyle};
30 format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs, rewrite_assign_rhs_with,
33 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, ListItem, Separator};
34 use macros::{rewrite_macro, MacroPosition};
36 use rewrite::{Rewrite, RewriteContext};
37 use shape::{Indent, Shape};
40 use vertical::rewrite_with_alignment;
41 use visitor::FmtVisitor;
43 const DEFAULT_VISIBILITY: ast::Visibility = codemap::Spanned {
44 node: ast::VisibilityKind::Inherited,
45 span: codemap::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 codemap = self.get_context().codemap;
385 if self.config.empty_item_single_line()
386 && is_empty_block(block, None, codemap)
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, codemap) {
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 {
533 tactic: DefinitiveListTactic::Vertical,
535 trailing_separator: self.config.trailing_comma(),
536 separator_place: SeparatorPlace::Back,
538 ends_with_newline: true,
539 preserve_newline: true,
544 let list = write_list(&items, &fmt)?;
545 result.push_str(&list);
546 result.push_str(&original_offset.to_string_with_newline(self.config));
551 // Variant of an enum.
552 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
553 if contains_skip(&field.node.attrs) {
554 let lo = field.node.attrs[0].span.lo();
555 let span = mk_sp(lo, field.span.hi());
556 return Some(self.snippet(span).to_owned());
559 let context = self.get_context();
561 let shape = self.shape().sub_width(1)?;
562 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
567 .map_or(field.span.lo(), |attr| attr.span.hi());
568 let span = mk_sp(lo, field.span.lo());
570 let variant_body = match field.node.data {
571 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
573 &StructParts::from_variant(field),
575 Some(one_line_width),
577 ast::VariantData::Unit(..) => {
578 if let Some(ref expr) = field.node.disr_expr {
579 let lhs = format!("{} =", rewrite_ident(&context, field.node.ident));
580 rewrite_assign_rhs(&context, lhs, &*expr.value, shape)?
582 rewrite_ident(&context, field.node.ident).to_owned()
587 combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
590 fn visit_impl_items(&mut self, items: &[ast::ImplItem]) {
591 if self.get_context().config.reorder_impl_items() {
592 // Create visitor for each items, then reorder them.
593 let mut buffer = vec![];
595 self.visit_impl_item(item);
596 buffer.push((self.buffer.clone(), item.clone()));
599 // type -> existential -> const -> macro -> method
600 use ast::ImplItemKind::*;
601 fn need_empty_line(a: &ast::ImplItemKind, b: &ast::ImplItemKind) -> bool {
604 | (Const(..), Const(..))
605 | (Existential(..), Existential(..)) => false,
610 buffer.sort_by(|(_, a), (_, b)| match (&a.node, &b.node) {
612 | (Const(..), Const(..))
613 | (Macro(..), Macro(..))
614 | (Existential(..), Existential(..)) => a.ident.as_str().cmp(&b.ident.as_str()),
615 (Method(..), Method(..)) => a.span.lo().cmp(&b.span.lo()),
616 (Type(..), _) => Ordering::Less,
617 (_, Type(..)) => Ordering::Greater,
618 (Existential(..), _) => Ordering::Less,
619 (_, Existential(..)) => Ordering::Greater,
620 (Const(..), _) => Ordering::Less,
621 (_, Const(..)) => Ordering::Greater,
622 (Macro(..), _) => Ordering::Less,
623 (_, Macro(..)) => Ordering::Greater,
625 let mut prev_kind = None;
626 for (buf, item) in buffer {
627 // Make sure that there are at least a single empty line between
628 // different impl items.
631 .map_or(false, |prev_kind| need_empty_line(prev_kind, &item.node))
635 let indent_str = self.block_indent.to_string_with_newline(self.config);
636 self.push_str(&indent_str);
637 self.push_str(buf.trim());
638 prev_kind = Some(item.node.clone());
642 self.visit_impl_item(item);
649 context: &RewriteContext,
652 where_span_end: Option<BytePos>,
653 ) -> Option<String> {
654 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
655 let mut result = String::with_capacity(128);
656 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
657 let sep = offset.to_string_with_newline(context.config);
658 result.push_str(&ref_and_type);
660 let where_budget = if result.contains('\n') {
661 context.config.max_width()
663 context.budget(last_line_width(&result))
666 let mut option = WhereClauseOption::snuggled(&ref_and_type);
667 let snippet = context.snippet(item.span);
668 let open_pos = snippet.find_uncommented("{")? + 1;
669 if !contains_comment(&snippet[open_pos..])
671 && generics.where_clause.predicates.len() == 1
672 && !result.contains('\n')
674 option.suppress_comma();
676 option.compress_where();
679 let where_clause_str = rewrite_where_clause(
681 &generics.where_clause,
682 context.config.brace_style(),
683 Shape::legacy(where_budget, offset.block_only()),
692 // If there is no where clause, we may have missing comments between the trait name and
693 // the opening brace.
694 if generics.where_clause.predicates.is_empty() {
695 if let Some(hi) = where_span_end {
696 match recover_missing_comment_in_span(
697 mk_sp(self_ty.span.hi(), hi),
698 Shape::indented(offset, context.config),
700 last_line_width(&result),
702 Some(ref missing_comment) if !missing_comment.is_empty() => {
703 result.push_str(missing_comment);
710 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
711 result.push_str(&where_clause_str);
712 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
713 // if the where_clause contains extra comments AND
714 // there is only one where clause predicate
715 // recover the suppressed comma in single line where_clause formatting
716 if generics.where_clause.predicates.len() == 1 {
717 result.push_str(",");
719 result.push_str(&format!("{}{{{}}}", &sep, &sep));
721 result.push_str(" {}");
726 result.push_str(&where_clause_str);
728 let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
729 match context.config.brace_style() {
730 _ if need_newline => result.push_str(&sep),
731 BraceStyle::AlwaysNextLine => result.push_str(&sep),
732 BraceStyle::PreferSameLine => result.push(' '),
733 BraceStyle::SameLineWhere => {
734 if !where_clause_str.is_empty() {
735 result.push_str(&sep);
744 let snippet = context.snippet(item.span);
745 let open_pos = snippet.find_uncommented("{")? + 1;
747 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
748 let mut visitor = FmtVisitor::from_context(context);
749 let item_indent = offset.block_only().block_indent(context.config);
750 visitor.block_indent = item_indent;
751 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
753 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
754 visitor.visit_impl_items(items);
756 visitor.format_missing(item.span.hi() - BytePos(1));
758 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
759 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
761 result.push_str(&inner_indent_str);
762 result.push_str(visitor.buffer.to_string().trim());
763 result.push_str(&outer_indent_str);
766 if result.ends_with('{') && !context.config.empty_item_single_line() {
767 result.push_str(&sep);
777 fn is_impl_single_line(
778 context: &RewriteContext,
779 items: &[ast::ImplItem],
781 where_clause_str: &str,
784 let snippet = context.snippet(item.span);
785 let open_pos = snippet.find_uncommented("{")? + 1;
788 context.config.empty_item_single_line()
790 && !result.contains('\n')
791 && result.len() + where_clause_str.len() <= context.config.max_width()
792 && !contains_comment(&snippet[open_pos..]),
796 fn format_impl_ref_and_type(
797 context: &RewriteContext,
800 ) -> Option<String> {
801 if let ast::ItemKind::Impl(
811 let mut result = String::with_capacity(128);
813 result.push_str(&format_visibility(context, &item.vis));
814 result.push_str(format_defaultness(defaultness));
815 result.push_str(format_unsafety(unsafety));
817 let shape = generics_shape_from_config(
819 Shape::indented(offset + last_line_width(&result), context.config),
822 let generics_str = rewrite_generics(context, "impl", generics, shape)?;
823 result.push_str(&generics_str);
825 let polarity_str = if polarity == ast::ImplPolarity::Negative {
831 if let Some(ref trait_ref) = *trait_ref {
832 let result_len = last_line_width(&result);
833 result.push_str(&rewrite_trait_ref(
842 // Try to put the self type in a single line.
844 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
845 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
846 // If there is no where clause adapt budget for type formatting to take space and curly
847 // brace into account.
848 match context.config.brace_style() {
849 BraceStyle::AlwaysNextLine => 0,
855 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
856 // 1 = space before the type.
857 let budget = context.budget(used_space + 1);
858 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
859 if !self_ty_str.contains('\n') {
860 if trait_ref.is_some() {
861 result.push_str(" for ");
865 result.push_str(&self_ty_str);
870 // Couldn't fit the self type on a single line, put it on a new line.
872 // Add indentation of one additional tab.
873 let new_line_offset = offset.block_indent(context.config);
874 result.push_str(&new_line_offset.to_string(context.config));
875 if trait_ref.is_some() {
876 result.push_str("for ");
878 let budget = context.budget(last_line_width(&result));
879 let type_offset = match context.config.indent_style() {
880 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
881 IndentStyle::Block => new_line_offset,
883 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
890 fn rewrite_trait_ref(
891 context: &RewriteContext,
892 trait_ref: &ast::TraitRef,
896 ) -> Option<String> {
897 // 1 = space between generics and trait_ref
898 let used_space = 1 + polarity_str.len() + result_len;
899 let shape = Shape::indented(offset + used_space, context.config);
900 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
901 if !trait_ref_str.contains('\n') {
902 return Some(format!(" {}{}", polarity_str, &trait_ref_str));
905 // We could not make enough space for trait_ref, so put it on new line.
906 let offset = offset.block_indent(context.config);
907 let shape = Shape::indented(offset, context.config);
908 let trait_ref_str = trait_ref.rewrite(context, shape)?;
911 &offset.to_string_with_newline(context.config),
917 pub struct StructParts<'a> {
920 vis: &'a ast::Visibility,
921 def: &'a ast::VariantData,
922 generics: Option<&'a ast::Generics>,
926 impl<'a> StructParts<'a> {
927 fn format_header(&self, context: &RewriteContext) -> String {
928 format_header(context, self.prefix, self.ident, self.vis)
931 fn from_variant(variant: &'a ast::Variant) -> Self {
934 ident: variant.node.ident,
935 vis: &DEFAULT_VISIBILITY,
936 def: &variant.node.data,
942 pub fn from_item(item: &'a ast::Item) -> Self {
943 let (prefix, def, generics) = match item.node {
944 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
945 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
953 generics: Some(generics),
960 context: &RewriteContext,
961 struct_parts: &StructParts,
963 one_line_width: Option<usize>,
964 ) -> Option<String> {
965 match *struct_parts.def {
966 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
967 ast::VariantData::Tuple(ref fields, _) => {
968 format_tuple_struct(context, struct_parts, fields, offset)
970 ast::VariantData::Struct(ref fields, _) => {
971 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
976 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
977 if let ast::ItemKind::Trait(
985 let mut result = String::with_capacity(128);
986 let header = format!(
988 format_visibility(context, &item.vis),
989 format_unsafety(unsafety),
990 format_auto(is_auto),
992 result.push_str(&header);
994 let body_lo = context.snippet_provider.span_after(item.span, "{");
996 let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
998 rewrite_generics(context, rewrite_ident(context, item.ident), generics, shape)?;
999 result.push_str(&generics_str);
1001 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
1002 if !generic_bounds.is_empty() {
1003 let ident_hi = context
1005 .span_after(item.span, &item.ident.as_str());
1006 let bound_hi = generic_bounds.last().unwrap().span().hi();
1007 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
1008 if contains_comment(snippet) {
1012 result = rewrite_assign_rhs_with(
1017 RhsTactics::ForceNextLineWithoutIndent,
1021 // Rewrite where clause.
1022 if !generics.where_clause.predicates.is_empty() {
1023 let where_density = if context.config.indent_style() == IndentStyle::Block {
1029 let where_budget = context.budget(last_line_width(&result));
1030 let pos_before_where = if generic_bounds.is_empty() {
1031 generics.where_clause.span.lo()
1033 generic_bounds[generic_bounds.len() - 1].span().hi()
1035 let option = WhereClauseOption::snuggled(&generics_str);
1036 let where_clause_str = rewrite_where_clause(
1038 &generics.where_clause,
1039 context.config.brace_style(),
1040 Shape::legacy(where_budget, offset.block_only()),
1048 // If the where clause cannot fit on the same line,
1049 // put the where clause on a new line
1050 if !where_clause_str.contains('\n')
1051 && last_line_width(&result) + where_clause_str.len() + offset.width()
1052 > context.config.comment_width()
1054 let width = offset.block_indent + context.config.tab_spaces() - 1;
1055 let where_indent = Indent::new(0, width);
1056 result.push_str(&where_indent.to_string_with_newline(context.config));
1058 result.push_str(&where_clause_str);
1060 let item_snippet = context.snippet(item.span);
1061 if let Some(lo) = item_snippet.find('/') {
1063 let comment_hi = body_lo - BytePos(1);
1064 let comment_lo = item.span.lo() + BytePos(lo as u32);
1065 if comment_lo < comment_hi {
1066 match recover_missing_comment_in_span(
1067 mk_sp(comment_lo, comment_hi),
1068 Shape::indented(offset, context.config),
1070 last_line_width(&result),
1072 Some(ref missing_comment) if !missing_comment.is_empty() => {
1073 result.push_str(missing_comment);
1081 match context.config.brace_style() {
1082 _ if last_line_contains_single_line_comment(&result)
1083 || last_line_width(&result) + 2 > context.budget(offset.width()) =>
1085 result.push_str(&offset.to_string_with_newline(context.config));
1087 BraceStyle::AlwaysNextLine => {
1088 result.push_str(&offset.to_string_with_newline(context.config));
1090 BraceStyle::PreferSameLine => result.push(' '),
1091 BraceStyle::SameLineWhere => {
1092 if result.contains('\n')
1093 || (!generics.where_clause.predicates.is_empty() && !trait_items.is_empty())
1095 result.push_str(&offset.to_string_with_newline(context.config));
1103 let snippet = context.snippet(item.span);
1104 let open_pos = snippet.find_uncommented("{")? + 1;
1106 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1107 let mut visitor = FmtVisitor::from_context(context);
1108 visitor.block_indent = offset.block_only().block_indent(context.config);
1109 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1111 for item in trait_items {
1112 visitor.visit_trait_item(item);
1115 visitor.format_missing(item.span.hi() - BytePos(1));
1117 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
1118 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
1120 result.push_str(&inner_indent_str);
1121 result.push_str(visitor.buffer.to_string().trim());
1122 result.push_str(&outer_indent_str);
1123 } else if result.contains('\n') {
1134 pub fn format_trait_alias(
1135 context: &RewriteContext,
1137 generics: &ast::Generics,
1138 generic_bounds: &ast::GenericBounds,
1140 ) -> Option<String> {
1141 let alias = rewrite_ident(context, ident);
1142 // 6 = "trait ", 2 = " ="
1143 let g_shape = shape.offset_left(6)?.sub_width(2)?;
1144 let generics_str = rewrite_generics(context, &alias, generics, g_shape)?;
1145 let lhs = format!("trait {} =", generics_str);
1147 rewrite_assign_rhs(context, lhs, generic_bounds, shape.sub_width(1)?).map(|s| s + ";")
1150 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1151 let header_str = format_header(context, p.prefix, p.ident, p.vis);
1152 let generics_str = if let Some(generics) = p.generics {
1153 let hi = if generics.where_clause.predicates.is_empty() {
1156 generics.where_clause.span.hi()
1161 context.config.brace_style(),
1164 mk_sp(generics.span.lo(), hi),
1165 last_line_width(&header_str),
1170 Some(format!("{}{};", header_str, generics_str))
1173 pub fn format_struct_struct(
1174 context: &RewriteContext,
1175 struct_parts: &StructParts,
1176 fields: &[ast::StructField],
1178 one_line_width: Option<usize>,
1179 ) -> Option<String> {
1180 let mut result = String::with_capacity(1024);
1181 let span = struct_parts.span;
1183 let header_str = struct_parts.format_header(context);
1184 result.push_str(&header_str);
1186 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1187 let body_lo = context.snippet_provider.span_after(span, "{");
1189 let generics_str = match struct_parts.generics {
1190 Some(g) => format_generics(
1193 context.config.brace_style(),
1194 if fields.is_empty() {
1195 BracePos::ForceSameLine
1200 mk_sp(header_hi, body_lo),
1201 last_line_width(&result),
1204 // 3 = ` {}`, 2 = ` {`.
1205 let overhead = if fields.is_empty() { 3 } else { 2 };
1206 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1207 || context.config.max_width() < overhead + result.len()
1209 format!("\n{}{{", offset.block_only().to_string(context.config))
1216 let overhead = if fields.is_empty() { 1 } else { 0 };
1217 let total_width = result.len() + generics_str.len() + overhead;
1218 if !generics_str.is_empty()
1219 && !generics_str.contains('\n')
1220 && total_width > context.config.max_width()
1223 result.push_str(&offset.to_string(context.config));
1224 result.push_str(generics_str.trim_left());
1226 result.push_str(&generics_str);
1229 if fields.is_empty() {
1230 let inner_span = mk_sp(body_lo, span.hi() - BytePos(1));
1231 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "", "}");
1232 return Some(result);
1236 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1237 let one_line_budget =
1238 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1240 let items_str = rewrite_with_alignment(
1243 Shape::indented(offset, context.config).sub_width(1)?,
1244 mk_sp(body_lo, span.hi()),
1248 if !items_str.contains('\n')
1249 && !result.contains('\n')
1250 && items_str.len() <= one_line_budget
1251 && !last_line_contains_single_line_comment(&items_str)
1253 Some(format!("{} {} }}", result, items_str))
1259 .block_indent(context.config)
1260 .to_string(context.config),
1262 offset.to_string(context.config)
1267 fn get_bytepos_after_visibility(vis: &ast::Visibility, default_span: Span) -> BytePos {
1269 ast::VisibilityKind::Crate(..) | ast::VisibilityKind::Restricted { .. } => vis.span.hi(),
1270 _ => default_span.lo(),
1274 // Format tuple or struct without any fields. We need to make sure that the comments
1275 // inside the delimiters are preserved.
1276 fn format_empty_struct_or_tuple(
1277 context: &RewriteContext,
1280 result: &mut String,
1284 // 3 = " {}" or "();"
1285 let used_width = last_line_used_width(&result, offset.width()) + 3;
1286 if used_width > context.config.max_width() {
1287 result.push_str(&offset.to_string_with_newline(context.config))
1289 result.push_str(opener);
1290 match rewrite_missing_comment(span, Shape::indented(offset, context.config), context) {
1291 Some(ref s) if s.is_empty() => (),
1293 if !is_single_line(s) || first_line_contains_single_line_comment(s) {
1294 let nested_indent_str = offset
1295 .block_indent(context.config)
1296 .to_string_with_newline(context.config);
1297 result.push_str(&nested_indent_str);
1300 if last_line_contains_single_line_comment(s) {
1301 result.push_str(&offset.to_string_with_newline(context.config));
1304 None => result.push_str(context.snippet(span)),
1306 result.push_str(closer);
1309 fn format_tuple_struct(
1310 context: &RewriteContext,
1311 struct_parts: &StructParts,
1312 fields: &[ast::StructField],
1314 ) -> Option<String> {
1315 let mut result = String::with_capacity(1024);
1316 let span = struct_parts.span;
1318 let header_str = struct_parts.format_header(context);
1319 result.push_str(&header_str);
1321 let body_lo = if fields.is_empty() {
1322 let lo = get_bytepos_after_visibility(struct_parts.vis, span);
1325 .span_after(mk_sp(lo, span.hi()), "(")
1329 let body_hi = if fields.is_empty() {
1332 .span_after(mk_sp(body_lo, span.hi()), ")")
1334 // This is a dirty hack to work around a missing `)` from the span of the last field.
1335 let last_arg_span = fields[fields.len() - 1].span;
1338 .opt_span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1339 .unwrap_or(last_arg_span.hi())
1342 let where_clause_str = match struct_parts.generics {
1344 let budget = context.budget(last_line_width(&header_str));
1345 let shape = Shape::legacy(budget, offset);
1346 let generics_str = rewrite_generics(context, "", generics, shape)?;
1347 result.push_str(&generics_str);
1349 let where_budget = context.budget(last_line_width(&result));
1350 let option = WhereClauseOption::new(true, false);
1351 rewrite_where_clause(
1353 &generics.where_clause,
1354 context.config.brace_style(),
1355 Shape::legacy(where_budget, offset.block_only()),
1356 Density::Compressed,
1364 None => "".to_owned(),
1367 if fields.is_empty() {
1368 let body_hi = context
1370 .span_before(mk_sp(body_lo, span.hi()), ")");
1371 let inner_span = mk_sp(body_lo, body_hi);
1372 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "(", ")");
1374 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1375 let fields = &fields.iter().collect::<Vec<_>>();
1376 result = overflow::rewrite_with_parens(
1382 context.config.width_heuristics().fn_call_width,
1387 if !where_clause_str.is_empty()
1388 && !where_clause_str.contains('\n')
1389 && (result.contains('\n')
1390 || offset.block_indent + result.len() + where_clause_str.len() + 1
1391 > context.config.max_width())
1393 // We need to put the where clause on a new line, but we didn't
1394 // know that earlier, so the where clause will not be indented properly.
1397 &(offset.block_only() + (context.config.tab_spaces() - 1)).to_string(context.config),
1400 result.push_str(&where_clause_str);
1405 fn rewrite_type_prefix(
1406 context: &RewriteContext,
1410 generics: &ast::Generics,
1411 ) -> Option<String> {
1412 let mut result = String::with_capacity(128);
1413 result.push_str(prefix);
1414 let ident_str = rewrite_ident(context, ident);
1417 if generics.params.is_empty() {
1418 result.push_str(ident_str)
1420 let g_shape = Shape::indented(indent, context.config)
1421 .offset_left(result.len())?
1423 let generics_str = rewrite_generics(context, ident_str, generics, g_shape)?;
1424 result.push_str(&generics_str);
1427 let where_budget = context.budget(last_line_width(&result));
1428 let option = WhereClauseOption::snuggled(&result);
1429 let where_clause_str = rewrite_where_clause(
1431 &generics.where_clause,
1432 context.config.brace_style(),
1433 Shape::legacy(where_budget, indent),
1441 result.push_str(&where_clause_str);
1446 fn rewrite_type_item<R: Rewrite>(
1447 context: &RewriteContext,
1453 generics: &ast::Generics,
1454 vis: &ast::Visibility,
1455 ) -> Option<String> {
1456 let mut result = String::with_capacity(128);
1457 result.push_str(&rewrite_type_prefix(
1460 &format!("{}{} ", format_visibility(context, vis), prefix),
1465 if generics.where_clause.predicates.is_empty() {
1466 result.push_str(suffix);
1468 result.push_str(&indent.to_string_with_newline(context.config));
1469 result.push_str(suffix.trim_left());
1473 let rhs_shape = Shape::indented(indent, context.config).sub_width(1)?;
1474 rewrite_assign_rhs(context, result, rhs, rhs_shape).map(|s| s + ";")
1477 pub fn rewrite_type_alias(
1478 context: &RewriteContext,
1482 generics: &ast::Generics,
1483 vis: &ast::Visibility,
1484 ) -> Option<String> {
1485 rewrite_type_item(context, indent, "type", " =", ident, ty, generics, vis)
1488 pub fn rewrite_existential_type(
1489 context: &RewriteContext,
1492 generic_bounds: &ast::GenericBounds,
1493 generics: &ast::Generics,
1494 vis: &ast::Visibility,
1495 ) -> Option<String> {
1508 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1510 if config.space_before_colon() { " " } else { "" },
1511 if config.space_after_colon() { " " } else { "" },
1515 pub fn rewrite_struct_field_prefix(
1516 context: &RewriteContext,
1517 field: &ast::StructField,
1518 ) -> Option<String> {
1519 let vis = format_visibility(context, &field.vis);
1520 let type_annotation_spacing = type_annotation_spacing(context.config);
1521 Some(match field.ident {
1522 Some(name) => format!(
1525 rewrite_ident(context, name),
1526 type_annotation_spacing.0
1528 None => format!("{}", vis),
1532 impl Rewrite for ast::StructField {
1533 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1534 rewrite_struct_field(context, self, shape, 0)
1538 pub fn rewrite_struct_field(
1539 context: &RewriteContext,
1540 field: &ast::StructField,
1542 lhs_max_width: usize,
1543 ) -> Option<String> {
1544 if contains_skip(&field.attrs) {
1545 return Some(context.snippet(field.span()).to_owned());
1548 let type_annotation_spacing = type_annotation_spacing(context.config);
1549 let prefix = rewrite_struct_field_prefix(context, field)?;
1551 let attrs_str = field.attrs.rewrite(context, shape)?;
1552 let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
1553 let missing_span = if field.attrs.is_empty() {
1554 mk_sp(field.span.lo(), field.span.lo())
1556 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1558 let mut spacing = String::from(if field.ident.is_some() {
1559 type_annotation_spacing.1
1563 // Try to put everything on a single line.
1564 let attr_prefix = combine_strs_with_missing_comments(
1572 let overhead = last_line_width(&attr_prefix);
1573 let lhs_offset = lhs_max_width.saturating_sub(overhead);
1574 for _ in 0..lhs_offset {
1577 // In this extreme case we will be missing a space betweeen an attribute and a field.
1578 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1582 .offset_left(overhead + spacing.len())
1583 .and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
1584 if let Some(ref ty) = orig_ty {
1585 if !ty.contains('\n') {
1586 return Some(attr_prefix + &spacing + ty);
1590 let is_prefix_empty = prefix.is_empty();
1591 // We must use multiline. We are going to put attributes and a field on different lines.
1592 let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, shape)?;
1593 // Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
1594 let field_str = if is_prefix_empty {
1595 field_str.trim_left()
1599 combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
1602 pub struct StaticParts<'a> {
1604 vis: &'a ast::Visibility,
1607 mutability: ast::Mutability,
1608 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1609 defaultness: Option<ast::Defaultness>,
1613 impl<'a> StaticParts<'a> {
1614 pub fn from_item(item: &'a ast::Item) -> Self {
1615 let (prefix, ty, mutability, expr) = match item.node {
1616 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1617 ast::ItemKind::Const(ref ty, ref expr) => {
1618 ("const", ty, ast::Mutability::Immutable, expr)
1620 _ => unreachable!(),
1628 expr_opt: Some(expr),
1634 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1635 let (ty, expr_opt) = match ti.node {
1636 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1637 _ => unreachable!(),
1641 vis: &DEFAULT_VISIBILITY,
1644 mutability: ast::Mutability::Immutable,
1645 expr_opt: expr_opt.as_ref(),
1651 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1652 let (ty, expr) = match ii.node {
1653 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1654 _ => unreachable!(),
1661 mutability: ast::Mutability::Immutable,
1662 expr_opt: Some(expr),
1663 defaultness: Some(ii.defaultness),
1670 context: &RewriteContext,
1671 static_parts: &StaticParts,
1673 ) -> Option<String> {
1674 let colon = colon_spaces(
1675 context.config.space_before_colon(),
1676 context.config.space_after_colon(),
1678 let mut prefix = format!(
1680 format_visibility(context, static_parts.vis),
1681 static_parts.defaultness.map_or("", format_defaultness),
1682 static_parts.prefix,
1683 format_mutability(static_parts.mutability),
1689 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1690 let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
1691 Some(ty_str) => ty_str,
1693 if prefix.ends_with(' ') {
1696 let nested_indent = offset.block_indent(context.config);
1697 let nested_shape = Shape::indented(nested_indent, context.config);
1698 let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
1701 nested_indent.to_string_with_newline(context.config),
1707 if let Some(expr) = static_parts.expr_opt {
1708 let lhs = format!("{}{} =", prefix, ty_str);
1710 let remaining_width = context.budget(offset.block_indent + 1);
1715 Shape::legacy(remaining_width, offset.block_only()),
1716 ).and_then(|res| recover_comment_removed(res, static_parts.span, context))
1717 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1719 Some(format!("{}{};", prefix, ty_str))
1723 pub fn rewrite_associated_type(
1725 ty_opt: Option<&ptr::P<ast::Ty>>,
1726 generic_bounds_opt: Option<&ast::GenericBounds>,
1727 context: &RewriteContext,
1729 ) -> Option<String> {
1730 let prefix = format!("type {}", rewrite_ident(context, ident));
1732 let type_bounds_str = if let Some(bounds) = generic_bounds_opt {
1733 if bounds.is_empty() {
1737 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1738 bounds.rewrite(context, shape).map(|s| format!(": {}", s))?
1744 if let Some(ty) = ty_opt {
1746 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1747 let lhs = format!("{}{} =", prefix, type_bounds_str);
1748 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1750 Some(format!("{}{};", prefix, type_bounds_str))
1754 pub fn rewrite_existential_impl_type(
1755 context: &RewriteContext,
1757 generic_bounds: &ast::GenericBounds,
1759 ) -> Option<String> {
1760 rewrite_associated_type(ident, None, Some(generic_bounds), context, indent)
1761 .map(|s| format!("existential {}", s))
1764 pub fn rewrite_associated_impl_type(
1766 defaultness: ast::Defaultness,
1767 ty_opt: Option<&ptr::P<ast::Ty>>,
1768 context: &RewriteContext,
1770 ) -> Option<String> {
1771 let result = rewrite_associated_type(ident, ty_opt, None, context, indent)?;
1774 ast::Defaultness::Default => Some(format!("default {}", result)),
1779 impl Rewrite for ast::FunctionRetTy {
1780 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1782 ast::FunctionRetTy::Default(_) => Some(String::new()),
1783 ast::FunctionRetTy::Ty(ref ty) => {
1784 let inner_width = shape.width.checked_sub(3)?;
1785 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1786 .map(|r| format!("-> {}", r))
1792 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1794 ast::TyKind::Infer => {
1795 let original = context.snippet(ty.span);
1802 impl Rewrite for ast::Arg {
1803 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1804 if is_named_arg(self) {
1805 let mut result = self
1807 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1809 if !is_empty_infer(context, &*self.ty) {
1810 if context.config.space_before_colon() {
1811 result.push_str(" ");
1813 result.push_str(":");
1814 if context.config.space_after_colon() {
1815 result.push_str(" ");
1817 let overhead = last_line_width(&result);
1818 let max_width = shape.width.checked_sub(overhead)?;
1821 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1822 result.push_str(&ty_str);
1827 self.ty.rewrite(context, shape)
1832 fn rewrite_explicit_self(
1833 explicit_self: &ast::ExplicitSelf,
1835 context: &RewriteContext,
1836 ) -> Option<String> {
1837 match explicit_self.node {
1838 ast::SelfKind::Region(lt, m) => {
1839 let mut_str = format_mutability(m);
1842 let lifetime_str = l.rewrite(
1844 Shape::legacy(context.config.max_width(), Indent::empty()),
1846 Some(format!("&{} {}self", lifetime_str, mut_str))
1848 None => Some(format!("&{}self", mut_str)),
1851 ast::SelfKind::Explicit(ref ty, _) => {
1852 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1854 let mutability = explicit_self_mutability(&args[0]);
1855 let type_str = ty.rewrite(
1857 Shape::legacy(context.config.max_width(), Indent::empty()),
1862 format_mutability(mutability),
1866 ast::SelfKind::Value(_) => {
1867 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1869 let mutability = explicit_self_mutability(&args[0]);
1871 Some(format!("{}self", format_mutability(mutability)))
1876 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1877 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1878 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1879 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1886 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1887 if is_named_arg(arg) {
1894 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1896 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1897 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1898 _ => arg.ty.span.hi(),
1902 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1903 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1904 ident != symbol::keywords::Invalid.ident()
1910 // Return type is (result, force_new_line_for_brace)
1912 context: &RewriteContext,
1917 newline_brace: bool,
1919 ) -> Option<(String, bool)> {
1920 let mut force_new_line_for_brace = false;
1922 let where_clause = &fn_sig.generics.where_clause;
1924 let mut result = String::with_capacity(1024);
1925 result.push_str(&fn_sig.to_str(context));
1928 result.push_str("fn ");
1931 let overhead = if has_body && !newline_brace {
1938 let used_width = last_line_used_width(&result, indent.width());
1939 let one_line_budget = context.budget(used_width + overhead);
1941 width: one_line_budget,
1945 let fd = fn_sig.decl;
1946 let generics_str = rewrite_generics(
1948 rewrite_ident(context, ident),
1952 result.push_str(&generics_str);
1954 let snuggle_angle_bracket = generics_str
1957 .map_or(false, |l| l.trim_left().len() == 1);
1959 // Note that the width and indent don't really matter, we'll re-layout the
1960 // return type later anyway.
1963 .rewrite(context, Shape::indented(indent, context.config))?;
1965 let multi_line_ret_str = ret_str.contains('\n');
1966 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1969 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1980 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1981 one_line_budget, multi_line_budget, arg_indent
1984 // Check if vertical layout was forced.
1985 if one_line_budget == 0 {
1986 if snuggle_angle_bracket {
1989 result.push_str("(");
1990 if context.config.indent_style() == IndentStyle::Visual {
1991 result.push_str(&arg_indent.to_string_with_newline(context.config));
1998 // Skip `pub(crate)`.
1999 let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
2000 // A conservative estimation, to goal is to be over all parens in generics
2001 let args_start = fn_sig
2006 .map_or(lo_after_visibility, |param| param.span().hi());
2007 let args_end = if fd.inputs.is_empty() {
2010 .span_after(mk_sp(args_start, span.hi()), ")")
2012 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
2013 context.snippet_provider.span_after(last_span, ")")
2015 let args_span = mk_sp(
2018 .span_after(mk_sp(args_start, span.hi()), "("),
2021 let arg_str = rewrite_args(
2024 fd.get_self().as_ref(),
2031 generics_str.contains('\n'),
2034 let put_args_in_block = match context.config.indent_style() {
2035 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
2037 } && !fd.inputs.is_empty();
2039 let mut args_last_line_contains_comment = false;
2040 if put_args_in_block {
2041 arg_indent = indent.block_indent(context.config);
2042 result.push_str(&arg_indent.to_string_with_newline(context.config));
2043 result.push_str(&arg_str);
2044 result.push_str(&indent.to_string_with_newline(context.config));
2047 result.push_str(&arg_str);
2048 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
2049 // Put the closing brace on the next line if it overflows the max width.
2051 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
2054 // If the last line of args contains comment, we cannot put the closing paren
2055 // on the same line.
2059 .map_or(false, |last_line| last_line.contains("//"))
2061 args_last_line_contains_comment = true;
2062 result.push_str(&arg_indent.to_string_with_newline(context.config));
2068 if let ast::FunctionRetTy::Ty(..) = fd.output {
2069 let ret_should_indent = match context.config.indent_style() {
2070 // If our args are block layout then we surely must have space.
2071 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
2072 _ if args_last_line_contains_comment => false,
2073 _ if result.contains('\n') || multi_line_ret_str => true,
2075 // If the return type would push over the max width, then put the return type on
2076 // a new line. With the +1 for the signature length an additional space between
2077 // the closing parenthesis of the argument and the arrow '->' is considered.
2078 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
2080 // If there is no where clause, take into account the space after the return type
2082 if where_clause.predicates.is_empty() {
2086 sig_length > context.config.max_width()
2089 let ret_indent = if ret_should_indent {
2090 let indent = if arg_str.is_empty() {
2091 // Aligning with non-existent args looks silly.
2092 force_new_line_for_brace = true;
2095 // FIXME: we might want to check that using the arg indent
2096 // doesn't blow our budget, and if it does, then fallback to
2097 // the where clause indent.
2101 result.push_str(&indent.to_string_with_newline(context.config));
2105 Indent::new(indent.block_indent, last_line_width(&result))
2108 if multi_line_ret_str || ret_should_indent {
2109 // Now that we know the proper indent and width, we need to
2110 // re-layout the return type.
2113 .rewrite(context, Shape::indented(ret_indent, context.config))?;
2114 result.push_str(&ret_str);
2116 result.push_str(&ret_str);
2119 // Comment between return type and the end of the decl.
2120 let snippet_lo = fd.output.span().hi();
2121 if where_clause.predicates.is_empty() {
2122 let snippet_hi = span.hi();
2123 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2124 // Try to preserve the layout of the original snippet.
2125 let original_starts_with_newline = snippet
2127 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2128 let original_ends_with_newline = snippet
2129 .rfind(|c| c != ' ')
2130 .map_or(false, |i| snippet[i..].ends_with('\n'));
2131 let snippet = snippet.trim();
2132 if !snippet.is_empty() {
2133 result.push(if original_starts_with_newline {
2138 result.push_str(snippet);
2139 if original_ends_with_newline {
2140 force_new_line_for_brace = true;
2146 let pos_before_where = match fd.output {
2147 ast::FunctionRetTy::Default(..) => args_span.hi(),
2148 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2151 let is_args_multi_lined = arg_str.contains('\n');
2153 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2154 let where_clause_str = rewrite_where_clause(
2157 context.config.brace_style(),
2158 Shape::indented(indent, context.config),
2164 is_args_multi_lined,
2166 // If there are neither where clause nor return type, we may be missing comments between
2168 if where_clause_str.is_empty() {
2169 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2170 match recover_missing_comment_in_span(
2171 mk_sp(args_span.hi(), ret_span.hi()),
2174 last_line_width(&result),
2176 Some(ref missing_comment) if !missing_comment.is_empty() => {
2177 result.push_str(missing_comment);
2178 force_new_line_for_brace = true;
2185 result.push_str(&where_clause_str);
2187 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2188 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2189 Some((result, force_new_line_for_brace))
2192 #[derive(Copy, Clone)]
2193 struct WhereClauseOption {
2194 suppress_comma: bool, // Force no trailing comma
2195 snuggle: bool, // Do not insert newline before `where`
2196 compress_where: bool, // Try single line where clause instead of vertical layout
2199 impl WhereClauseOption {
2200 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2204 compress_where: false,
2208 pub fn snuggled(current: &str) -> WhereClauseOption {
2210 suppress_comma: false,
2211 snuggle: last_line_width(current) == 1,
2212 compress_where: false,
2216 pub fn suppress_comma(&mut self) {
2217 self.suppress_comma = true
2220 pub fn compress_where(&mut self) {
2221 self.compress_where = true
2224 pub fn snuggle(&mut self) {
2230 context: &RewriteContext,
2232 explicit_self: Option<&ast::ExplicitSelf>,
2233 one_line_budget: usize,
2234 multi_line_budget: usize,
2239 generics_str_contains_newline: bool,
2240 ) -> Option<String> {
2241 let mut arg_item_strs = args
2243 .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
2244 .collect::<Option<Vec<_>>>()?;
2246 // Account for sugary self.
2247 // FIXME: the comment for the self argument is dropped. This is blocked
2248 // on rust issue #27522.
2249 let min_args = explicit_self
2250 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2251 .map_or(1, |self_str| {
2252 arg_item_strs[0] = self_str;
2256 // Comments between args.
2257 let mut arg_items = Vec::new();
2259 arg_items.push(ListItem::from_str(""));
2262 // FIXME(#21): if there are no args, there might still be a comment, but
2263 // without spans for the comment or parens, there is no chance of
2264 // getting it right. You also don't get to put a comment on self, unless
2266 if args.len() >= min_args || variadic {
2267 let comment_span_start = if min_args == 2 {
2268 let second_arg_start = if arg_has_pattern(&args[1]) {
2269 args[1].pat.span.lo()
2271 args[1].ty.span.lo()
2273 let reduced_span = mk_sp(span.lo(), second_arg_start);
2275 context.snippet_provider.span_after_last(reduced_span, ",")
2280 enum ArgumentKind<'a> {
2281 Regular(&'a ast::Arg),
2285 let variadic_arg = if variadic {
2286 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2287 let variadic_start =
2288 context.snippet_provider.span_after(variadic_span, "...") - BytePos(3);
2289 Some(ArgumentKind::Variadic(variadic_start))
2294 let more_items = itemize_list(
2295 context.snippet_provider,
2296 args[min_args - 1..]
2298 .map(ArgumentKind::Regular)
2299 .chain(variadic_arg),
2303 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2304 ArgumentKind::Variadic(start) => start,
2307 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2308 ArgumentKind::Variadic(start) => start + BytePos(3),
2311 ArgumentKind::Regular(..) => None,
2312 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2319 arg_items.extend(more_items);
2322 let fits_in_one_line = !generics_str_contains_newline
2323 && (arg_items.is_empty()
2324 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2326 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2327 item.item = Some(arg);
2330 let last_line_ends_with_comment = arg_items
2333 .and_then(|item| item.post_comment.as_ref())
2334 .map_or(false, |s| s.trim().starts_with("//"));
2336 let (indent, trailing_comma) = match context.config.indent_style() {
2337 IndentStyle::Block if fits_in_one_line => {
2338 (indent.block_indent(context.config), SeparatorTactic::Never)
2340 IndentStyle::Block => (
2341 indent.block_indent(context.config),
2342 context.config.trailing_comma(),
2344 IndentStyle::Visual if last_line_ends_with_comment => {
2345 (arg_indent, context.config.trailing_comma())
2347 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2350 let tactic = definitive_tactic(
2352 context.config.fn_args_density().to_list_tactic(),
2356 let budget = match tactic {
2357 DefinitiveListTactic::Horizontal => one_line_budget,
2358 _ => multi_line_budget,
2361 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2363 let fmt = ListFormatting {
2366 trailing_separator: if variadic {
2367 SeparatorTactic::Never
2371 separator_place: SeparatorPlace::Back,
2372 shape: Shape::legacy(budget, indent),
2373 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2374 preserve_newline: true,
2376 config: context.config,
2379 write_list(&arg_items, &fmt)
2382 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2383 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2384 ident != symbol::keywords::Invalid.ident()
2390 fn compute_budgets_for_args(
2391 context: &RewriteContext,
2395 newline_brace: bool,
2397 force_vertical_layout: bool,
2398 ) -> Option<((usize, usize, Indent))> {
2400 "compute_budgets_for_args {} {:?}, {}, {}",
2406 // Try keeping everything on the same line.
2407 if !result.contains('\n') && !force_vertical_layout {
2408 // 2 = `()`, 3 = `() `, space is before ret_string.
2409 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2410 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2420 let one_line_budget = context.budget(used_space);
2422 if one_line_budget > 0 {
2424 let (indent, multi_line_budget) = match context.config.indent_style() {
2425 IndentStyle::Block => {
2426 let indent = indent.block_indent(context.config);
2427 (indent, context.budget(indent.width() + 1))
2429 IndentStyle::Visual => {
2430 let indent = indent + result.len() + 1;
2431 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2432 (indent, context.budget(multi_line_overhead))
2436 return Some((one_line_budget, multi_line_budget, indent));
2440 // Didn't work. we must force vertical layout and put args on a newline.
2441 let new_indent = indent.block_indent(context.config);
2442 let used_space = match context.config.indent_style() {
2444 IndentStyle::Block => new_indent.width() + 1,
2445 // Account for `)` and possibly ` {`.
2446 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2448 Some((0, context.budget(used_space), new_indent))
2451 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2452 let predicate_count = where_clause.predicates.len();
2454 if config.where_single_line() && predicate_count == 1 {
2457 let brace_style = config.brace_style();
2459 brace_style == BraceStyle::AlwaysNextLine
2460 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2463 fn rewrite_generics(
2464 context: &RewriteContext,
2466 generics: &ast::Generics,
2468 ) -> Option<String> {
2469 // FIXME: convert bounds to where clauses where they get too big or if
2470 // there is a where clause at all.
2472 if generics.params.is_empty() {
2473 return Some(ident.to_owned());
2476 let params = &generics.params.iter().map(|e| &*e).collect::<Vec<_>>();
2477 overflow::rewrite_with_angle_brackets(context, ident, params, shape, generics.span)
2480 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2481 match config.indent_style() {
2482 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2483 IndentStyle::Block => {
2487 .block_indent(config.tab_spaces())
2488 .with_max_width(config)
2494 fn rewrite_where_clause_rfc_style(
2495 context: &RewriteContext,
2496 where_clause: &ast::WhereClause,
2499 span_end: Option<BytePos>,
2500 span_end_before_where: BytePos,
2501 where_clause_option: WhereClauseOption,
2502 is_args_multi_line: bool,
2503 ) -> Option<String> {
2504 let block_shape = shape.block().with_max_width(context.config);
2506 let (span_before, span_after) =
2507 missing_span_before_after_where(span_end_before_where, where_clause);
2508 let (comment_before, comment_after) =
2509 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2511 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2514 block_shape.indent.to_string_with_newline(context.config)
2517 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2519 let clause_shape = clause_shape.sub_width(1)?;
2520 // each clause on one line, trailing comma (except if suppress_comma)
2521 let span_start = where_clause.predicates[0].span().lo();
2522 // If we don't have the start of the next span, then use the end of the
2523 // predicates, but that means we miss comments.
2524 let len = where_clause.predicates.len();
2525 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2526 let span_end = span_end.unwrap_or(end_of_preds);
2527 let items = itemize_list(
2528 context.snippet_provider,
2529 where_clause.predicates.iter(),
2532 |pred| pred.span().lo(),
2533 |pred| pred.span().hi(),
2534 |pred| pred.rewrite(context, clause_shape),
2539 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2540 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2541 SeparatorTactic::Never
2543 context.config.trailing_comma()
2546 // shape should be vertical only and only if we have `where_single_line` option enabled
2547 // and the number of items of the where clause is equal to 1
2548 let shape_tactic = if where_single_line {
2549 DefinitiveListTactic::Horizontal
2551 DefinitiveListTactic::Vertical
2554 let fmt = ListFormatting {
2555 tactic: shape_tactic,
2557 trailing_separator: comma_tactic,
2558 separator_place: SeparatorPlace::Back,
2559 shape: clause_shape,
2560 ends_with_newline: true,
2561 preserve_newline: true,
2563 config: context.config,
2565 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2567 let comment_separator = |comment: &str, shape: Shape| {
2568 if comment.is_empty() {
2571 shape.indent.to_string_with_newline(context.config)
2574 let newline_before_where = comment_separator(&comment_before, shape);
2575 let newline_after_where = comment_separator(&comment_after, clause_shape);
2578 let clause_sep = if where_clause_option.compress_where
2579 && comment_before.is_empty()
2580 && comment_after.is_empty()
2581 && !preds_str.contains('\n')
2582 && 6 + preds_str.len() <= shape.width
2583 || where_single_line
2587 clause_shape.indent.to_string_with_newline(context.config)
2590 "{}{}{}where{}{}{}{}",
2593 newline_before_where,
2594 newline_after_where,
2601 fn rewrite_where_clause(
2602 context: &RewriteContext,
2603 where_clause: &ast::WhereClause,
2604 brace_style: BraceStyle,
2608 span_end: Option<BytePos>,
2609 span_end_before_where: BytePos,
2610 where_clause_option: WhereClauseOption,
2611 is_args_multi_line: bool,
2612 ) -> Option<String> {
2613 if where_clause.predicates.is_empty() {
2614 return Some(String::new());
2617 if context.config.indent_style() == IndentStyle::Block {
2618 return rewrite_where_clause_rfc_style(
2624 span_end_before_where,
2625 where_clause_option,
2630 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2632 let offset = match context.config.indent_style() {
2633 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2634 // 6 = "where ".len()
2635 IndentStyle::Visual => shape.indent + extra_indent + 6,
2637 // FIXME: if indent_style != Visual, then the budgets below might
2638 // be out by a char or two.
2640 let budget = context.config.max_width() - offset.width();
2641 let span_start = where_clause.predicates[0].span().lo();
2642 // If we don't have the start of the next span, then use the end of the
2643 // predicates, but that means we miss comments.
2644 let len = where_clause.predicates.len();
2645 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2646 let span_end = span_end.unwrap_or(end_of_preds);
2647 let items = itemize_list(
2648 context.snippet_provider,
2649 where_clause.predicates.iter(),
2652 |pred| pred.span().lo(),
2653 |pred| pred.span().hi(),
2654 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2659 let item_vec = items.collect::<Vec<_>>();
2660 // FIXME: we don't need to collect here
2661 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2663 let mut comma_tactic = context.config.trailing_comma();
2664 // Kind of a hack because we don't usually have trailing commas in where clauses.
2665 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2666 comma_tactic = SeparatorTactic::Never;
2669 let fmt = ListFormatting {
2672 trailing_separator: comma_tactic,
2673 separator_place: SeparatorPlace::Back,
2674 shape: Shape::legacy(budget, offset),
2675 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2676 preserve_newline: true,
2678 config: context.config,
2680 let preds_str = write_list(&item_vec, &fmt)?;
2682 let end_length = if terminator == "{" {
2683 // If the brace is on the next line we don't need to count it otherwise it needs two
2686 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2687 BraceStyle::PreferSameLine => 2,
2689 } else if terminator == "=" {
2694 if density == Density::Tall
2695 || preds_str.contains('\n')
2696 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2700 (shape.indent + extra_indent).to_string(context.config),
2704 Some(format!(" where {}", preds_str))
2708 fn missing_span_before_after_where(
2709 before_item_span_end: BytePos,
2710 where_clause: &ast::WhereClause,
2712 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2714 let pos_after_where = where_clause.span.lo() + BytePos(5);
2715 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2716 (missing_span_before, missing_span_after)
2719 fn rewrite_comments_before_after_where(
2720 context: &RewriteContext,
2721 span_before_where: Span,
2722 span_after_where: Span,
2724 ) -> Option<(String, String)> {
2725 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2726 let after_comment = rewrite_missing_comment(
2728 shape.block_indent(context.config.tab_spaces()),
2731 Some((before_comment, after_comment))
2735 context: &RewriteContext,
2738 vis: &ast::Visibility,
2742 format_visibility(context, vis),
2744 rewrite_ident(context, ident)
2748 #[derive(PartialEq, Eq, Clone, Copy)]
2756 context: &RewriteContext,
2757 generics: &ast::Generics,
2758 brace_style: BraceStyle,
2759 brace_pos: BracePos,
2763 ) -> Option<String> {
2764 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2765 let mut result = rewrite_generics(context, "", generics, shape)?;
2767 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2768 let budget = context.budget(last_line_used_width(&result, offset.width()));
2769 let mut option = WhereClauseOption::snuggled(&result);
2770 if brace_pos == BracePos::None {
2771 option.suppress_comma = true;
2773 // If the generics are not parameterized then generics.span.hi() == 0,
2774 // so we use span.lo(), which is the position after `struct Foo`.
2775 let span_end_before_where = if !generics.params.is_empty() {
2780 let where_clause_str = rewrite_where_clause(
2782 &generics.where_clause,
2784 Shape::legacy(budget, offset.block_only()),
2788 span_end_before_where,
2792 result.push_str(&where_clause_str);
2793 brace_pos == BracePos::ForceSameLine
2794 || brace_style == BraceStyle::PreferSameLine
2795 || (generics.where_clause.predicates.is_empty()
2796 && trimmed_last_line_width(&result) == 1)
2798 brace_pos == BracePos::ForceSameLine
2799 || trimmed_last_line_width(&result) == 1
2800 || brace_style != BraceStyle::AlwaysNextLine
2802 if brace_pos == BracePos::None {
2803 return Some(result);
2805 let total_used_width = last_line_used_width(&result, used_width);
2806 let remaining_budget = context.budget(total_used_width);
2807 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2808 // and hence we take the closer into account as well for one line budget.
2809 // We assume that the closer has the same length as the opener.
2810 let overhead = if brace_pos == BracePos::ForceSameLine {
2817 let forbid_same_line_brace = overhead > remaining_budget;
2818 if !forbid_same_line_brace && same_line_brace {
2822 result.push_str(&offset.block_only().to_string(context.config));
2829 impl Rewrite for ast::ForeignItem {
2830 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2831 let attrs_str = self.attrs.rewrite(context, shape)?;
2832 // Drop semicolon or it will be interpreted as comment.
2833 // FIXME: this may be a faulty span from libsyntax.
2834 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2836 let item_str = match self.node {
2837 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => rewrite_fn_base(
2841 &FnSig::new(fn_decl, generics, self.vis.clone()),
2845 ).map(|(s, _)| format!("{};", s)),
2846 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2847 // FIXME(#21): we're dropping potential comments in between the
2848 // function keywords here.
2849 let vis = format_visibility(context, &self.vis);
2850 let mut_str = if is_mutable { "mut " } else { "" };
2851 let prefix = format!(
2855 rewrite_ident(context, self.ident)
2858 rewrite_assign_rhs(context, prefix, &**ty, shape.sub_width(1)?).map(|s| s + ";")
2860 ast::ForeignItemKind::Ty => {
2861 let vis = format_visibility(context, &self.vis);
2865 rewrite_ident(context, self.ident)
2868 ast::ForeignItemKind::Macro(ref mac) => {
2869 rewrite_macro(mac, None, context, shape, MacroPosition::Item)
2873 let missing_span = if self.attrs.is_empty() {
2874 mk_sp(self.span.lo(), self.span.lo())
2876 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2878 combine_strs_with_missing_comments(
2889 /// Rewrite an inline mod.
2890 pub fn rewrite_mod(context: &RewriteContext, item: &ast::Item) -> String {
2891 let mut result = String::with_capacity(32);
2892 result.push_str(&*format_visibility(context, &item.vis));
2893 result.push_str("mod ");
2894 result.push_str(rewrite_ident(context, item.ident));
2899 /// Rewrite `extern crate foo;` WITHOUT attributes.
2900 pub fn rewrite_extern_crate(context: &RewriteContext, item: &ast::Item) -> Option<String> {
2901 assert!(is_extern_crate(item));
2902 let new_str = context.snippet(item.span);
2903 Some(if contains_comment(new_str) {
2906 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
2907 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
2911 /// Returns true for `mod foo;`, false for `mod foo { .. }`.
2912 pub fn is_mod_decl(item: &ast::Item) -> bool {
2914 ast::ItemKind::Mod(ref m) => m.inner.hi() != item.span.hi(),
2919 pub fn is_use_item(item: &ast::Item) -> bool {
2921 ast::ItemKind::Use(_) => true,
2926 pub fn is_extern_crate(item: &ast::Item) -> bool {
2928 ast::ItemKind::ExternCrate(..) => true,