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.
16 use syntax::{abi, ast, ptr, symbol};
17 use syntax::ast::{CrateSugar, ImplItem};
18 use syntax::codemap::{BytePos, Span};
22 use codemap::{LineRangeUtils, SpanUtils};
23 use comment::{combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
24 recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented};
25 use config::{BraceStyle, Config, Density, IndentStyle};
26 use expr::{choose_rhs, format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs,
27 rewrite_call_inner, ExprType};
28 use lists::{definitive_tactic, itemize_list, write_list, DefinitiveListTactic, ListFormatting,
29 ListItem, ListTactic, Separator, SeparatorPlace, SeparatorTactic};
30 use rewrite::{Rewrite, RewriteContext};
31 use shape::{Indent, Shape};
32 use types::join_bounds;
33 use utils::{colon_spaces, contains_skip, end_typaram, first_line_width, format_abi,
34 format_constness, format_defaultness, format_mutability, format_unsafety,
35 format_visibility, is_attributes_extendable, last_line_contains_single_line_comment,
36 last_line_used_width, last_line_width, mk_sp, semicolon_for_expr, starts_with_newline,
37 stmt_expr, trim_newlines, trimmed_last_line_width};
38 use vertical::rewrite_with_alignment;
39 use visitor::FmtVisitor;
41 fn type_annotation_separator(config: &Config) -> &str {
42 colon_spaces(config.space_before_colon(), config.space_after_colon())
45 // Statements of the form
46 // let pat: ty = init;
47 impl Rewrite for ast::Local {
48 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
50 "Local::rewrite {:?} {} {:?}",
56 skip_out_of_file_lines_range!(context, self.span);
58 if contains_skip(&self.attrs) {
62 let attrs_str = self.attrs.rewrite(context, shape)?;
63 let mut result = if attrs_str.is_empty() {
66 combine_strs_with_missing_comments(
71 self.attrs.last().map(|a| a.span.hi()).unwrap(),
80 let pat_shape = shape.offset_left(4)?;
82 let pat_shape = pat_shape.sub_width(1)?;
83 let pat_str = self.pat.rewrite(context, pat_shape)?;
84 result.push_str(&pat_str);
86 // String that is placed within the assignment pattern and expression.
88 let mut infix = String::with_capacity(32);
90 if let Some(ref ty) = self.ty {
91 let separator = type_annotation_separator(context.config);
92 let indent = shape.indent + last_line_width(&result) + separator.len();
94 let budget = shape.width.checked_sub(indent.width() + 1)?;
95 let rewrite = ty.rewrite(context, Shape::legacy(budget, indent))?;
97 infix.push_str(separator);
98 infix.push_str(&rewrite);
101 if self.init.is_some() {
102 infix.push_str(" =");
108 result.push_str(&infix);
110 if let Some(ref ex) = self.init {
111 // 1 = trailing semicolon;
112 let nested_shape = shape.sub_width(1)?;
114 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
122 // TODO convert to using rewrite style rather than visitor
123 // TODO format modules in this style
126 keyword: &'static str,
127 abi: Cow<'static, str>,
128 vis: Option<&'a ast::Visibility>,
129 body: Vec<BodyElement<'a>>,
134 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
137 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
141 .map(|i| BodyElement::ForeignItem(i))
148 enum BodyElement<'a> {
149 // Stmt(&'a ast::Stmt),
150 // Field(&'a ast::Field),
151 // Variant(&'a ast::Variant),
152 // Item(&'a ast::Item),
153 ForeignItem(&'a ast::ForeignItem),
156 /// Represents a fn's signature.
157 pub struct FnSig<'a> {
158 decl: &'a ast::FnDecl,
159 generics: &'a ast::Generics,
161 constness: ast::Constness,
162 defaultness: ast::Defaultness,
163 unsafety: ast::Unsafety,
164 visibility: ast::Visibility,
169 decl: &'a ast::FnDecl,
170 generics: &'a ast::Generics,
171 vis: ast::Visibility,
177 constness: ast::Constness::NotConst,
178 defaultness: ast::Defaultness::Final,
179 unsafety: ast::Unsafety::Normal,
184 pub fn from_method_sig(
185 method_sig: &'a ast::MethodSig,
186 generics: &'a ast::Generics,
189 unsafety: method_sig.unsafety,
190 constness: method_sig.constness.node,
191 defaultness: ast::Defaultness::Final,
193 decl: &*method_sig.decl,
195 visibility: ast::Visibility::Inherited,
200 fn_kind: &'a visit::FnKind,
201 generics: &'a ast::Generics,
202 decl: &'a ast::FnDecl,
203 defualtness: ast::Defaultness,
206 visit::FnKind::ItemFn(_, unsafety, constness, abi, visibility, _) => FnSig {
210 constness: constness.node,
211 defaultness: defualtness,
213 visibility: visibility.clone(),
215 visit::FnKind::Method(_, method_sig, vis, _) => {
216 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
217 fn_sig.defaultness = defualtness;
218 if let Some(vis) = vis {
219 fn_sig.visibility = vis.clone();
227 fn to_str(&self, context: &RewriteContext) -> String {
228 let mut result = String::with_capacity(128);
229 // Vis defaultness constness unsafety abi.
230 result.push_str(&*format_visibility(&self.visibility));
231 result.push_str(format_defaultness(self.defaultness));
232 result.push_str(format_constness(self.constness));
233 result.push_str(format_unsafety(self.unsafety));
234 result.push_str(&format_abi(
236 context.config.force_explicit_abi(),
243 impl<'a> FmtVisitor<'a> {
244 fn format_item(&mut self, item: Item) {
245 self.buffer.push_str(&item.abi);
247 let snippet = self.snippet(item.span);
248 let brace_pos = snippet.find_uncommented("{").unwrap();
250 self.buffer.push_str("{");
251 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
252 // FIXME: this skips comments between the extern keyword and the opening
254 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
255 self.block_indent = self.block_indent.block_indent(self.config);
257 if item.body.is_empty() {
258 self.format_missing_no_indent(item.span.hi() - BytePos(1));
259 self.block_indent = self.block_indent.block_unindent(self.config);
262 .push_str(&self.block_indent.to_string(self.config));
264 for item in &item.body {
265 self.format_body_element(item);
268 self.block_indent = self.block_indent.block_unindent(self.config);
269 self.format_missing_with_indent(item.span.hi() - BytePos(1));
273 self.buffer.push_str("}");
274 self.last_pos = item.span.hi();
277 fn format_body_element(&mut self, element: &BodyElement) {
279 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
283 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
284 let item = Item::from_foreign_mod(fm, span, self.config);
285 self.format_item(item);
289 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
290 let rewrite = item.rewrite(&self.get_context(), self.shape());
291 self.push_rewrite(item.span(), rewrite);
292 self.last_pos = item.span.hi();
302 ) -> Option<String> {
303 let context = self.get_context();
306 !is_empty_block(block, self.codemap) || !context.config.fn_empty_single_line();
307 let mut newline_brace =
308 newline_for_brace(self.config, &fn_sig.generics.where_clause, has_body);
310 let (mut result, force_newline_brace) =
311 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
314 if self.config.brace_style() == BraceStyle::AlwaysNextLine || force_newline_brace
315 || last_line_width(&result) + 2 > self.shape().width
317 newline_brace = true;
318 } else if !result.contains('\n') {
319 newline_brace = false;
322 // Prepare for the function body by possibly adding a newline and
324 // FIXME we'll miss anything between the end of the signature and the
325 // start of the body, but we need more spans from the compiler to solve
329 result.push_str(&indent.to_string(self.config));
334 self.single_line_fn(&result, block).or_else(|| Some(result))
337 pub fn rewrite_required_fn(
341 sig: &ast::MethodSig,
342 generics: &ast::Generics,
344 ) -> Option<String> {
345 // Drop semicolon or it will be interpreted as comment.
346 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
347 let context = self.get_context();
349 let (mut result, _) = rewrite_fn_base(
353 &FnSig::from_method_sig(sig, generics),
359 // Re-attach semicolon
365 fn single_line_fn(&self, fn_str: &str, block: &ast::Block) -> Option<String> {
366 if fn_str.contains('\n') {
370 let codemap = self.get_context().codemap;
372 if self.config.fn_empty_single_line() && is_empty_block(block, codemap)
373 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
375 return Some(format!("{}{{}}", fn_str));
378 if self.config.fn_single_line() && is_simple_block_stmt(block, codemap) {
380 if let Some(stmt) = block.stmts.first() {
381 match stmt_expr(stmt) {
383 let suffix = if semicolon_for_expr(&self.get_context(), e) {
389 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
391 .or_else(|| Some(self.snippet(e.span)))
393 None => stmt.rewrite(&self.get_context(), self.shape()),
400 if let Some(res) = rewrite {
401 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
402 if !res.contains('\n') && width <= self.config.max_width() {
403 return Some(format!("{}{{ {} }}", fn_str, res));
411 pub fn visit_static(&mut self, static_parts: &StaticParts) {
412 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
413 self.push_rewrite(static_parts.span, rewrite);
416 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
417 let is_tuple = struct_parts.def.is_tuple();
418 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
419 .map(|s| if is_tuple { s + ";" } else { s });
420 self.push_rewrite(struct_parts.span, rewrite);
426 vis: &ast::Visibility,
427 enum_def: &ast::EnumDef,
428 generics: &ast::Generics,
431 let enum_header = format_header("enum ", ident, vis);
432 self.buffer.push_str(&enum_header);
434 let enum_snippet = self.snippet(span);
435 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
436 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
437 let generics_str = format_generics(
440 self.config.brace_style(),
441 if enum_def.variants.is_empty() {
442 BracePos::ForceSameLine
447 mk_sp(span.lo(), body_start),
448 last_line_width(&enum_header),
450 self.buffer.push_str(&generics_str);
452 self.last_pos = body_start;
454 self.block_indent = self.block_indent.block_indent(self.config);
455 let variant_list = self.format_variant_list(enum_def, body_start, span.hi() - BytePos(1));
457 Some(ref body_str) => self.buffer.push_str(body_str),
458 None => if contains_comment(&enum_snippet[brace_pos..]) {
459 self.format_missing_no_indent(span.hi() - BytePos(1))
462 self.block_indent = self.block_indent.block_unindent(self.config);
464 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
466 .push_str(&self.block_indent.to_string(self.config));
468 self.buffer.push_str("}");
469 self.last_pos = span.hi();
472 // Format the body of an enum definition
473 fn format_variant_list(
475 enum_def: &ast::EnumDef,
478 ) -> Option<String> {
479 if enum_def.variants.is_empty() {
482 let mut result = String::with_capacity(1024);
484 let indentation = self.block_indent.to_string(self.config);
485 result.push_str(&indentation);
487 let itemize_list_with = |one_line_width: usize| {
490 enum_def.variants.iter(),
493 |f| if !f.node.attrs.is_empty() {
494 f.node.attrs[0].span.lo()
499 |f| self.format_variant(f, one_line_width),
505 let mut items: Vec<_> =
506 itemize_list_with(self.config.width_heuristics().struct_variant_width);
507 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
508 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains("\n"));
509 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains("\n"));
510 if has_multiline_variant && has_single_line_variant {
511 items = itemize_list_with(0);
514 let shape = self.shape().sub_width(2).unwrap();
515 let fmt = ListFormatting {
516 tactic: DefinitiveListTactic::Vertical,
518 trailing_separator: self.config.trailing_comma(),
519 separator_place: SeparatorPlace::Back,
521 ends_with_newline: true,
522 preserve_newline: true,
526 let list = write_list(&items, &fmt)?;
527 result.push_str(&list);
532 // Variant of an enum.
533 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
534 if contains_skip(&field.node.attrs) {
535 let lo = field.node.attrs[0].span.lo();
536 let span = mk_sp(lo, field.span.hi());
537 return Some(self.snippet(span));
540 let context = self.get_context();
541 let indent = self.block_indent;
542 let shape = self.shape();
543 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
548 .map_or(field.span.lo(), |attr| attr.span.hi());
549 let span = mk_sp(lo, field.span.lo());
551 let variant_body = match field.node.data {
552 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => {
553 // FIXME: Should limit the width, as we have a trailing comma
556 &StructParts::from_variant(field),
558 Some(one_line_width),
561 ast::VariantData::Unit(..) => if let Some(ref expr) = field.node.disr_expr {
562 let lhs = format!("{} =", field.node.name);
564 rewrite_assign_rhs(&context, lhs, &**expr, shape.sub_width(1)?)?
566 field.node.name.to_string()
570 let attrs_extendable = attrs_str.is_empty()
571 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
572 combine_strs_with_missing_comments(
584 context: &RewriteContext,
587 where_span_end: Option<BytePos>,
588 ) -> Option<String> {
589 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
590 let mut result = String::with_capacity(128);
591 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
592 let indent_str = offset.to_string(context.config);
593 let sep = format!("\n{}", &indent_str);
594 result.push_str(&ref_and_type);
596 let where_budget = if result.contains('\n') {
597 context.config.max_width()
599 context.budget(last_line_width(&result))
601 let option = WhereClauseOption::snuggled(&ref_and_type);
602 let where_clause_str = rewrite_where_clause(
604 &generics.where_clause,
605 context.config.brace_style(),
606 Shape::legacy(where_budget, offset.block_only()),
607 context.config.where_density(),
615 // If there is no where clause, we may have missing comments between the trait name and
616 // the opening brace.
617 if generics.where_clause.predicates.is_empty() {
618 if let Some(hi) = where_span_end {
619 match recover_missing_comment_in_span(
620 mk_sp(self_ty.span.hi(), hi),
621 Shape::indented(offset, context.config),
623 last_line_width(&result),
625 Some(ref missing_comment) if !missing_comment.is_empty() => {
626 result.push_str(missing_comment);
633 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
634 result.push_str(&where_clause_str);
635 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
636 result.push_str(&format!("{}{{{}}}", &sep, &sep));
638 result.push_str(" {}");
643 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
645 let width = offset.block_indent + context.config.tab_spaces() - 1;
646 let where_indent = Indent::new(0, width);
647 result.push_str(&where_indent.to_string(context.config));
649 result.push_str(&where_clause_str);
651 match context.config.brace_style() {
652 _ if last_line_contains_single_line_comment(&result) => result.push_str(&sep),
653 BraceStyle::AlwaysNextLine => result.push_str(&sep),
654 BraceStyle::PreferSameLine => result.push(' '),
655 BraceStyle::SameLineWhere => if !where_clause_str.is_empty() {
656 result.push_str(&sep);
664 let snippet = context.snippet(item.span);
665 let open_pos = snippet.find_uncommented("{")? + 1;
667 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
668 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
669 visitor.block_indent = offset.block_only().block_indent(context.config);
670 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
672 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
674 visitor.visit_impl_item(item);
677 visitor.format_missing(item.span.hi() - BytePos(1));
679 let inner_indent_str = visitor.block_indent.to_string(context.config);
680 let outer_indent_str = offset.block_only().to_string(context.config);
683 result.push_str(&inner_indent_str);
684 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
686 result.push_str(&outer_indent_str);
689 if result.ends_with('{') {
690 result.push_str(&sep);
700 fn is_impl_single_line(
701 context: &RewriteContext,
704 where_clause_str: &str,
707 let snippet = context.snippet(item.span);
708 let open_pos = snippet.find_uncommented("{")? + 1;
711 context.config.impl_empty_single_line() && items.is_empty() && !result.contains('\n')
712 && result.len() + where_clause_str.len() <= context.config.max_width()
713 && !contains_comment(&snippet[open_pos..]),
717 fn format_impl_ref_and_type(
718 context: &RewriteContext,
721 ) -> Option<String> {
722 if let ast::ItemKind::Impl(
732 let mut result = String::with_capacity(128);
734 result.push_str(&format_visibility(&item.vis));
735 result.push_str(format_defaultness(defaultness));
736 result.push_str(format_unsafety(unsafety));
737 result.push_str("impl");
739 let lo = context.codemap.span_after(item.span, "impl");
740 let hi = match *trait_ref {
741 Some(ref tr) => tr.path.span.lo(),
742 None => self_ty.span.lo(),
744 let shape = generics_shape_from_config(
746 Shape::indented(offset + last_line_width(&result), context.config),
749 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
751 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
753 let polarity_str = if polarity == ast::ImplPolarity::Negative {
759 if let Some(ref trait_ref) = *trait_ref {
760 let result_len = result.len();
761 if let Some(trait_ref_str) = rewrite_trait_ref(
770 result.push_str(&trait_ref_str);
773 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
774 result.push_str(&rewrite_trait_ref(
785 result.push_str(&generics_str);
788 // Try to put the self type in a single line.
790 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
791 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
792 // If there is no where clause adapt budget for type formatting to take space and curly
793 // brace into account.
794 match context.config.brace_style() {
795 BraceStyle::AlwaysNextLine => 0,
801 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
802 // 1 = space before the type.
803 let budget = context.budget(used_space + 1);
804 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
805 if !self_ty_str.contains('\n') {
806 if trait_ref.is_some() {
807 result.push_str(" for ");
811 result.push_str(&self_ty_str);
816 // Couldn't fit the self type on a single line, put it on a new line.
818 // Add indentation of one additional tab.
819 let new_line_offset = offset.block_indent(context.config);
820 result.push_str(&new_line_offset.to_string(context.config));
821 if trait_ref.is_some() {
822 result.push_str("for ");
824 let budget = context.budget(last_line_width(&result));
825 let type_offset = match context.config.indent_style() {
826 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
827 IndentStyle::Block => new_line_offset,
829 result.push_str(&*self_ty
830 .rewrite(context, Shape::legacy(budget, type_offset))?);
837 fn rewrite_trait_ref(
838 context: &RewriteContext,
839 trait_ref: &ast::TraitRef,
845 ) -> Option<String> {
846 // 1 = space between generics and trait_ref
847 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
848 let shape = Shape::indented(offset + used_space, context.config);
849 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
850 if !(retry && trait_ref_str.contains('\n')) {
859 // We could not make enough space for trait_ref, so put it on new line.
861 let offset = offset.block_indent(context.config);
862 let shape = Shape::indented(offset, context.config);
863 let trait_ref_str = trait_ref.rewrite(context, shape)?;
867 &offset.to_string(context.config),
876 pub struct StructParts<'a> {
879 vis: &'a ast::Visibility,
880 def: &'a ast::VariantData,
881 generics: Option<&'a ast::Generics>,
885 impl<'a> StructParts<'a> {
886 fn format_header(&self) -> String {
887 format_header(self.prefix, self.ident, self.vis)
890 fn from_variant(variant: &'a ast::Variant) -> Self {
893 ident: variant.node.name,
894 vis: &ast::Visibility::Inherited,
895 def: &variant.node.data,
901 pub fn from_item(item: &'a ast::Item) -> Self {
902 let (prefix, def, generics) = match item.node {
903 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
904 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
912 generics: Some(generics),
919 context: &RewriteContext,
920 struct_parts: &StructParts,
922 one_line_width: Option<usize>,
923 ) -> Option<String> {
924 match *struct_parts.def {
925 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
926 ast::VariantData::Tuple(ref fields, _) => {
927 format_tuple_struct(context, struct_parts, fields, offset)
929 ast::VariantData::Struct(ref fields, _) => {
930 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
935 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
936 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
939 let mut result = String::with_capacity(128);
940 let header = format!(
942 format_visibility(&item.vis),
943 format_unsafety(unsafety),
947 result.push_str(&header);
949 let body_lo = context.codemap.span_after(item.span, "{");
951 let shape = Shape::indented(offset, context.config);
953 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
954 result.push_str(&generics_str);
956 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
957 if !type_param_bounds.is_empty() {
958 let ident_hi = context.codemap.span_after(item.span, &format!("{}", item.ident));
959 let bound_hi = type_param_bounds.last().unwrap().span().hi();
960 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
961 if contains_comment(&snippet) {
965 let trait_bound_str = rewrite_trait_bounds(
968 Shape::indented(offset, context.config),
970 // If the trait, generics, and trait bound cannot fit on the same line,
971 // put the trait bounds on an indented new line
972 if offset.width() + last_line_width(&result) + trait_bound_str.len()
973 > context.config.comment_width()
976 let trait_indent = offset.block_only().block_indent(context.config);
977 result.push_str(&trait_indent.to_string(context.config));
979 result.push_str(&trait_bound_str);
981 let has_body = !trait_items.is_empty();
983 let where_density = if (context.config.where_density() == Density::Compressed
984 && (!result.contains('\n') || context.config.indent_style() == IndentStyle::Block))
985 || (context.config.indent_style() == IndentStyle::Block && result.is_empty())
986 || (context.config.where_density() == Density::CompressedIfEmpty && !has_body
987 && !result.contains('\n'))
994 let where_budget = context.budget(last_line_width(&result));
995 let pos_before_where = if type_param_bounds.is_empty() {
996 generics.where_clause.span.lo()
998 type_param_bounds[type_param_bounds.len() - 1].span().hi()
1000 let option = WhereClauseOption::snuggled(&generics_str);
1001 let where_clause_str = rewrite_where_clause(
1003 &generics.where_clause,
1004 context.config.brace_style(),
1005 Shape::legacy(where_budget, offset.block_only()),
1013 // If the where clause cannot fit on the same line,
1014 // put the where clause on a new line
1015 if !where_clause_str.contains('\n')
1016 && last_line_width(&result) + where_clause_str.len() + offset.width()
1017 > context.config.comment_width()
1020 let width = offset.block_indent + context.config.tab_spaces() - 1;
1021 let where_indent = Indent::new(0, width);
1022 result.push_str(&where_indent.to_string(context.config));
1024 result.push_str(&where_clause_str);
1026 if generics.where_clause.predicates.is_empty() {
1027 let item_snippet = context.snippet(item.span);
1028 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1030 let comment_hi = body_lo - BytePos(1);
1031 let comment_lo = item.span.lo() + BytePos(lo as u32);
1032 if comment_lo < comment_hi {
1033 match recover_missing_comment_in_span(
1034 mk_sp(comment_lo, comment_hi),
1035 Shape::indented(offset, context.config),
1037 last_line_width(&result),
1039 Some(ref missing_comment) if !missing_comment.is_empty() => {
1040 result.push_str(missing_comment);
1048 match context.config.brace_style() {
1049 _ if last_line_contains_single_line_comment(&result) => {
1051 result.push_str(&offset.to_string(context.config));
1053 BraceStyle::AlwaysNextLine => {
1055 result.push_str(&offset.to_string(context.config));
1057 BraceStyle::PreferSameLine => result.push(' '),
1058 BraceStyle::SameLineWhere => if !where_clause_str.is_empty()
1059 && (!trait_items.is_empty() || result.contains('\n'))
1062 result.push_str(&offset.to_string(context.config));
1069 let snippet = context.snippet(item.span);
1070 let open_pos = snippet.find_uncommented("{")? + 1;
1072 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1073 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
1074 visitor.block_indent = offset.block_only().block_indent(context.config);
1075 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1077 for item in trait_items {
1078 visitor.visit_trait_item(item);
1081 visitor.format_missing(item.span.hi() - BytePos(1));
1083 let inner_indent_str = visitor.block_indent.to_string(context.config);
1084 let outer_indent_str = offset.block_only().to_string(context.config);
1087 result.push_str(&inner_indent_str);
1088 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1090 result.push_str(&outer_indent_str);
1091 } else if result.contains('\n') {
1102 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1103 let header_str = format_header(p.prefix, p.ident, p.vis);
1104 let generics_str = if let Some(generics) = p.generics {
1105 let hi = if generics.where_clause.predicates.is_empty() {
1108 generics.where_clause.span.hi()
1113 context.config.brace_style(),
1116 mk_sp(generics.span.lo(), hi),
1117 last_line_width(&header_str),
1122 Some(format!("{}{};", header_str, generics_str))
1125 pub fn format_struct_struct(
1126 context: &RewriteContext,
1127 struct_parts: &StructParts,
1128 fields: &[ast::StructField],
1130 one_line_width: Option<usize>,
1131 ) -> Option<String> {
1132 let mut result = String::with_capacity(1024);
1133 let span = struct_parts.span;
1135 let header_str = struct_parts.format_header();
1136 result.push_str(&header_str);
1138 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1139 let body_lo = context.codemap.span_after(span, "{");
1141 let generics_str = match struct_parts.generics {
1142 Some(g) => format_generics(
1145 context.config.brace_style(),
1146 if fields.is_empty() {
1147 BracePos::ForceSameLine
1152 mk_sp(header_hi, body_lo),
1153 last_line_width(&result),
1156 // 3 = ` {}`, 2 = ` {`.
1157 let overhead = if fields.is_empty() { 3 } else { 2 };
1158 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1159 || context.config.max_width() < overhead + result.len()
1161 format!("\n{}{{", offset.block_only().to_string(context.config))
1168 let overhead = if fields.is_empty() { 1 } else { 0 };
1169 let total_width = result.len() + generics_str.len() + overhead;
1170 if !generics_str.is_empty() && !generics_str.contains('\n')
1171 && total_width > context.config.max_width()
1174 result.push_str(&offset.to_string(context.config));
1175 result.push_str(generics_str.trim_left());
1177 result.push_str(&generics_str);
1180 if fields.is_empty() {
1181 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1182 if snippet.trim().is_empty() {
1184 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1186 result.push_str(snippet.trim_right());
1188 result.push_str(&offset.to_string(context.config));
1190 result.push_str(&snippet);
1193 return Some(result);
1197 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1198 let one_line_budget =
1199 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1201 let items_str = rewrite_with_alignment(
1204 Shape::indented(offset, context.config).sub_width(1)?,
1205 mk_sp(body_lo, span.hi()),
1209 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget {
1210 Some(format!("{} {} }}", result, items_str))
1216 .block_indent(context.config)
1217 .to_string(context.config),
1219 offset.to_string(context.config)
1224 /// Returns a bytepos that is after that of `(` in `pub(..)`. If the given visibility does not
1225 /// contain `pub(..)`, then return the `lo` of the `defualt_span`. Yeah, but for what? Well, we need
1226 /// to bypass the `(` in the visibility when creating a span of tuple's body or fn's args.
1227 fn get_bytepos_after_visibility(
1228 context: &RewriteContext,
1229 vis: &ast::Visibility,
1234 ast::Visibility::Crate(s, CrateSugar::PubCrate) => context
1236 .span_after(mk_sp(s.hi(), default_span.hi()), terminator),
1237 ast::Visibility::Crate(s, CrateSugar::JustCrate) => s.hi(),
1238 ast::Visibility::Restricted { ref path, .. } => path.span.hi(),
1239 _ => default_span.lo(),
1243 fn format_tuple_struct(
1244 context: &RewriteContext,
1245 struct_parts: &StructParts,
1246 fields: &[ast::StructField],
1248 ) -> Option<String> {
1249 let mut result = String::with_capacity(1024);
1250 let span = struct_parts.span;
1252 let header_str = struct_parts.format_header();
1253 result.push_str(&header_str);
1255 let body_lo = if fields.is_empty() {
1256 let lo = get_bytepos_after_visibility(context, struct_parts.vis, span, ")");
1257 context.codemap.span_after(mk_sp(lo, span.hi()), "(")
1261 let body_hi = if fields.is_empty() {
1262 context.codemap.span_after(mk_sp(body_lo, span.hi()), ")")
1264 // This is a dirty hack to work around a missing `)` from the span of the last field.
1265 let last_arg_span = fields[fields.len() - 1].span;
1266 if context.snippet(last_arg_span).ends_with(')') {
1271 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1275 let where_clause_str = match struct_parts.generics {
1277 let budget = context.budget(last_line_width(&header_str));
1278 let shape = Shape::legacy(budget, offset);
1279 let g_span = mk_sp(span.lo(), body_lo);
1280 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1281 result.push_str(&generics_str);
1283 let where_budget = context.budget(last_line_width(&result));
1284 let option = WhereClauseOption::new(true, false);
1285 rewrite_where_clause(
1287 &generics.where_clause,
1288 context.config.brace_style(),
1289 Shape::legacy(where_budget, offset.block_only()),
1290 Density::Compressed,
1298 None => "".to_owned(),
1301 if fields.is_empty() {
1303 let used_width = last_line_used_width(&result, offset.width()) + 3;
1304 if used_width > context.config.max_width() {
1306 result.push_str(&offset
1307 .block_indent(context.config)
1308 .to_string(context.config))
1311 let snippet = context.snippet(mk_sp(
1313 context.codemap.span_before(mk_sp(body_lo, span.hi()), ")"),
1315 if snippet.is_empty() {
1317 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1318 result.push_str(snippet.trim_right());
1320 result.push_str(&offset.to_string(context.config));
1322 result.push_str(&snippet);
1326 let shape = Shape::indented(offset, context.config);
1327 let fields = &fields.iter().map(|field| field).collect::<Vec<_>>()[..];
1328 let one_line_width = context.config.width_heuristics().fn_call_width;
1329 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1332 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1333 && (result.contains('\n')
1334 || offset.block_indent + result.len() + where_clause_str.len() + 1
1335 > context.config.max_width())
1337 // We need to put the where clause on a new line, but we didn't
1338 // know that earlier, so the where clause will not be indented properly.
1340 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1341 .to_string(context.config));
1343 result.push_str(&where_clause_str);
1348 pub fn rewrite_type_alias(
1349 context: &RewriteContext,
1353 generics: &ast::Generics,
1354 vis: &ast::Visibility,
1356 ) -> Option<String> {
1357 let mut result = String::with_capacity(128);
1359 result.push_str(&format_visibility(vis));
1360 result.push_str("type ");
1361 result.push_str(&ident.to_string());
1364 let shape = Shape::indented(indent + result.len(), context.config).sub_width(2)?;
1365 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo());
1366 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1367 result.push_str(&generics_str);
1369 let where_budget = context.budget(last_line_width(&result));
1370 let option = WhereClauseOption::snuggled(&result);
1371 let where_clause_str = rewrite_where_clause(
1373 &generics.where_clause,
1374 context.config.brace_style(),
1375 Shape::legacy(where_budget, indent),
1376 context.config.where_density(),
1383 result.push_str(&where_clause_str);
1384 if where_clause_str.is_empty() {
1385 result.push_str(" = ");
1387 result.push_str(&format!("\n{}= ", indent.to_string(context.config)));
1390 let line_width = last_line_width(&result);
1391 // This checked_sub may fail as the extra space after '=' is not taken into account
1392 // In that case the budget is set to 0 which will make ty.rewrite retry on a new line
1393 let budget = context.budget(indent.width() + line_width + ";".len());
1394 let type_indent = indent + line_width;
1395 // Try to fit the type on the same line
1396 let ty_str = ty.rewrite(context, Shape::legacy(budget, type_indent))
1398 // The line was too short, try to put the type on the next line
1400 // Remove the space after '='
1402 let type_indent = indent.block_indent(context.config);
1404 result.push_str(&type_indent.to_string(context.config));
1405 let budget = context.budget(type_indent.width() + ";".len());
1406 ty.rewrite(context, Shape::legacy(budget, type_indent))
1408 result.push_str(&ty_str);
1409 result.push_str(";");
1413 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1415 if config.space_before_colon() { " " } else { "" },
1416 if config.space_after_colon() { " " } else { "" },
1420 pub fn rewrite_struct_field_prefix(
1421 context: &RewriteContext,
1422 field: &ast::StructField,
1423 ) -> Option<String> {
1424 let vis = format_visibility(&field.vis);
1425 let type_annotation_spacing = type_annotation_spacing(context.config);
1426 Some(match field.ident {
1427 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1428 None => format!("{}", vis),
1432 impl Rewrite for ast::StructField {
1433 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1434 rewrite_struct_field(context, self, shape, 0)
1438 pub fn rewrite_struct_field(
1439 context: &RewriteContext,
1440 field: &ast::StructField,
1442 lhs_max_width: usize,
1443 ) -> Option<String> {
1444 if contains_skip(&field.attrs) {
1445 return Some(context.snippet(mk_sp(field.attrs[0].span.lo(), field.span.hi())));
1448 let type_annotation_spacing = type_annotation_spacing(context.config);
1449 let prefix = rewrite_struct_field_prefix(context, field)?;
1451 let attrs_str = field.attrs.rewrite(context, shape)?;
1452 let attrs_extendable = attrs_str.is_empty()
1453 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
1454 let missing_span = if field.attrs.is_empty() {
1455 mk_sp(field.span.lo(), field.span.lo())
1457 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1459 let mut spacing = String::from(if field.ident.is_some() {
1460 type_annotation_spacing.1
1464 // Try to put everything on a single line.
1465 let attr_prefix = combine_strs_with_missing_comments(
1473 let overhead = last_line_width(&attr_prefix);
1474 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1475 for _ in 0..lhs_offset {
1478 // In this extreme case we will be missing a space betweeen an attribute and a field.
1479 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1482 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1483 let mut orig_ty = field.ty.rewrite(context, ty_shape);
1484 if let Some(ref ty) = orig_ty {
1485 if !ty.contains('\n') {
1486 return Some(attr_prefix + &spacing + ty);
1490 // We must use multiline. We are going to put attributes and a field on different lines.
1492 let rhs_shape = shape.offset_left(last_line_width(&prefix) + 1)?;
1493 orig_ty = field.ty.rewrite(context, rhs_shape);
1494 let field_str = if prefix.is_empty() {
1497 prefix + &choose_rhs(context, &*field.ty, rhs_shape, orig_ty)?
1499 combine_strs_with_missing_comments(context, &attrs_str, &field_str, missing_span, shape, false)
1502 pub struct StaticParts<'a> {
1504 vis: &'a ast::Visibility,
1507 mutability: ast::Mutability,
1508 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1512 impl<'a> StaticParts<'a> {
1513 pub fn from_item(item: &'a ast::Item) -> Self {
1514 let (prefix, ty, mutability, expr) = match item.node {
1515 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1516 ast::ItemKind::Const(ref ty, ref expr) => {
1517 ("const", ty, ast::Mutability::Immutable, expr)
1519 _ => unreachable!(),
1526 mutability: mutability,
1527 expr_opt: Some(expr),
1532 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1533 let (ty, expr_opt) = match ti.node {
1534 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1535 _ => unreachable!(),
1539 vis: &ast::Visibility::Inherited,
1542 mutability: ast::Mutability::Immutable,
1543 expr_opt: expr_opt.as_ref(),
1548 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1549 let (ty, expr) = match ii.node {
1550 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1551 _ => unreachable!(),
1558 mutability: ast::Mutability::Immutable,
1559 expr_opt: Some(expr),
1566 context: &RewriteContext,
1567 static_parts: &StaticParts,
1569 ) -> Option<String> {
1570 let colon = colon_spaces(
1571 context.config.space_before_colon(),
1572 context.config.space_after_colon(),
1574 let prefix = format!(
1576 format_visibility(static_parts.vis),
1577 static_parts.prefix,
1578 format_mutability(static_parts.mutability),
1584 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1585 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1587 if let Some(expr) = static_parts.expr_opt {
1588 let lhs = format!("{}{} =", prefix, ty_str);
1590 let remaining_width = context.budget(offset.block_indent + 1);
1595 Shape::legacy(remaining_width, offset.block_only()),
1597 recover_comment_removed(res, static_parts.span, context)
1599 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1601 Some(format!("{}{};", prefix, ty_str))
1605 pub fn rewrite_associated_type(
1607 ty_opt: Option<&ptr::P<ast::Ty>>,
1608 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1609 context: &RewriteContext,
1611 ) -> Option<String> {
1612 let prefix = format!("type {}", ident);
1614 let type_bounds_str = if let Some(ref bounds) = ty_param_bounds_opt {
1616 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1617 let bound_str = bounds
1619 .map(|ty_bound| ty_bound.rewrite(context, shape))
1620 .collect::<Option<Vec<_>>>()?;
1621 if !bounds.is_empty() {
1622 format!(": {}", join_bounds(context, shape, &bound_str))
1630 if let Some(ty) = ty_opt {
1632 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1633 let lhs = format!("{}{} =", prefix, type_bounds_str);
1634 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1636 Some(format!("{}{};", prefix, type_bounds_str))
1640 pub fn rewrite_associated_impl_type(
1642 defaultness: ast::Defaultness,
1643 ty_opt: Option<&ptr::P<ast::Ty>>,
1644 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1645 context: &RewriteContext,
1647 ) -> Option<String> {
1648 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1651 ast::Defaultness::Default => Some(format!("default {}", result)),
1656 impl Rewrite for ast::FunctionRetTy {
1657 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1659 ast::FunctionRetTy::Default(_) => Some(String::new()),
1660 ast::FunctionRetTy::Ty(ref ty) => {
1661 let inner_width = shape.width.checked_sub(3)?;
1662 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1663 .map(|r| format!("-> {}", r))
1669 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1671 ast::TyKind::Infer => {
1672 let original = context.snippet(ty.span);
1679 impl Rewrite for ast::Arg {
1680 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1681 if is_named_arg(self) {
1682 let mut result = self.pat
1683 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1685 if !is_empty_infer(context, &*self.ty) {
1686 if context.config.space_before_colon() {
1687 result.push_str(" ");
1689 result.push_str(":");
1690 if context.config.space_after_colon() {
1691 result.push_str(" ");
1693 let overhead = last_line_width(&result);
1694 let max_width = shape.width.checked_sub(overhead)?;
1695 let ty_str = self.ty
1696 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1697 result.push_str(&ty_str);
1702 self.ty.rewrite(context, shape)
1707 fn rewrite_explicit_self(
1708 explicit_self: &ast::ExplicitSelf,
1710 context: &RewriteContext,
1711 ) -> Option<String> {
1712 match explicit_self.node {
1713 ast::SelfKind::Region(lt, m) => {
1714 let mut_str = format_mutability(m);
1717 let lifetime_str = l.rewrite(
1719 Shape::legacy(context.config.max_width(), Indent::empty()),
1721 Some(format!("&{} {}self", lifetime_str, mut_str))
1723 None => Some(format!("&{}self", mut_str)),
1726 ast::SelfKind::Explicit(ref ty, _) => {
1727 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1729 let mutability = explicit_self_mutability(&args[0]);
1730 let type_str = ty.rewrite(
1732 Shape::legacy(context.config.max_width(), Indent::empty()),
1737 format_mutability(mutability),
1741 ast::SelfKind::Value(_) => {
1742 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1744 let mutability = explicit_self_mutability(&args[0]);
1746 Some(format!("{}self", format_mutability(mutability)))
1751 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1752 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1753 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1754 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1761 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1762 if is_named_arg(arg) {
1769 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1771 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1772 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1773 _ => arg.ty.span.hi(),
1777 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1778 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1779 ident.node != symbol::keywords::Invalid.ident()
1785 // Return type is (result, force_new_line_for_brace)
1787 context: &RewriteContext,
1792 newline_brace: bool,
1794 ) -> Option<(String, bool)> {
1795 let mut force_new_line_for_brace = false;
1797 let where_clause = &fn_sig.generics.where_clause;
1799 let mut result = String::with_capacity(1024);
1800 result.push_str(&fn_sig.to_str(context));
1803 result.push_str("fn ");
1804 result.push_str(&ident.to_string());
1807 let overhead = if has_body && !newline_brace {
1814 let used_width = last_line_used_width(&result, indent.width());
1815 let one_line_budget = context.budget(used_width + overhead);
1817 width: one_line_budget,
1821 let fd = fn_sig.decl;
1822 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1823 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1824 result.push_str(&generics_str);
1826 let snuggle_angle_bracket = generics_str
1829 .map_or(false, |l| l.trim_left().len() == 1);
1831 // Note that the width and indent don't really matter, we'll re-layout the
1832 // return type later anyway.
1833 let ret_str = fd.output
1834 .rewrite(context, Shape::indented(indent, context.config))?;
1836 let multi_line_ret_str = ret_str.contains('\n');
1837 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1840 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1851 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1857 // Check if vertical layout was forced.
1858 if one_line_budget == 0 {
1859 if snuggle_angle_bracket {
1862 result.push_str("(");
1863 if context.config.indent_style() == IndentStyle::Visual {
1865 result.push_str(&arg_indent.to_string(context.config));
1871 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1872 && result.ends_with('(')
1877 // Skip `pub(crate)`.
1878 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1879 // A conservative estimation, to goal is to be over all parens in generics
1880 let args_start = fn_sig
1884 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1885 let args_end = if fd.inputs.is_empty() {
1888 .span_after(mk_sp(args_start, span.hi()), ")")
1890 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1891 context.codemap.span_after(last_span, ")")
1893 let args_span = mk_sp(
1896 .span_after(mk_sp(args_start, span.hi()), "("),
1899 let arg_str = rewrite_args(
1902 fd.get_self().as_ref(),
1909 generics_str.contains('\n'),
1912 let put_args_in_block = match context.config.indent_style() {
1913 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1915 } && !fd.inputs.is_empty();
1917 let mut args_last_line_contains_comment = false;
1918 if put_args_in_block {
1919 arg_indent = indent.block_indent(context.config);
1921 result.push_str(&arg_indent.to_string(context.config));
1922 result.push_str(&arg_str);
1924 result.push_str(&indent.to_string(context.config));
1927 result.push_str(&arg_str);
1928 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1929 // Put the closing brace on the next line if it overflows the max width.
1931 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1934 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1937 // If the last line of args contains comment, we cannot put the closing paren
1938 // on the same line.
1942 .map_or(false, |last_line| last_line.contains("//"))
1944 args_last_line_contains_comment = true;
1946 result.push_str(&arg_indent.to_string(context.config));
1952 if let ast::FunctionRetTy::Ty(..) = fd.output {
1953 let ret_should_indent = match context.config.indent_style() {
1954 // If our args are block layout then we surely must have space.
1955 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1956 _ if args_last_line_contains_comment => false,
1957 _ if result.contains('\n') || multi_line_ret_str => true,
1959 // If the return type would push over the max width, then put the return type on
1960 // a new line. With the +1 for the signature length an additional space between
1961 // the closing parenthesis of the argument and the arrow '->' is considered.
1962 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1964 // If there is no where clause, take into account the space after the return type
1966 if where_clause.predicates.is_empty() {
1970 sig_length > context.config.max_width()
1973 let ret_indent = if ret_should_indent {
1974 let indent = if arg_str.is_empty() {
1975 // Aligning with non-existent args looks silly.
1976 force_new_line_for_brace = true;
1979 // FIXME: we might want to check that using the arg indent
1980 // doesn't blow our budget, and if it does, then fallback to
1981 // the where clause indent.
1986 result.push_str(&indent.to_string(context.config));
1990 Indent::new(indent.block_indent, last_line_width(&result))
1993 if multi_line_ret_str || ret_should_indent {
1994 // Now that we know the proper indent and width, we need to
1995 // re-layout the return type.
1996 let ret_str = fd.output
1997 .rewrite(context, Shape::indented(ret_indent, context.config))?;
1998 result.push_str(&ret_str);
2000 result.push_str(&ret_str);
2003 // Comment between return type and the end of the decl.
2004 let snippet_lo = fd.output.span().hi();
2005 if where_clause.predicates.is_empty() {
2006 let snippet_hi = span.hi();
2007 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2008 // Try to preserve the layout of the original snippet.
2009 let original_starts_with_newline = snippet
2011 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2012 let original_ends_with_newline = snippet
2013 .rfind(|c| c != ' ')
2014 .map_or(false, |i| snippet[i..].ends_with('\n'));
2015 let snippet = snippet.trim();
2016 if !snippet.is_empty() {
2017 result.push(if original_starts_with_newline {
2022 result.push_str(snippet);
2023 if original_ends_with_newline {
2024 force_new_line_for_brace = true;
2030 let should_compress_where = match context.config.where_density() {
2031 Density::Compressed => !result.contains('\n'),
2032 Density::CompressedIfEmpty => !has_body && !result.contains('\n'),
2036 let pos_before_where = match fd.output {
2037 ast::FunctionRetTy::Default(..) => args_span.hi(),
2038 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2041 let is_args_multi_lined = arg_str.contains('\n');
2043 if where_clause.predicates.len() == 1 && should_compress_where {
2044 let budget = context.budget(last_line_used_width(&result, indent.width()));
2045 if let Some(where_clause_str) = rewrite_where_clause(
2048 context.config.brace_style(),
2049 Shape::legacy(budget, indent),
2050 Density::Compressed,
2054 WhereClauseOption::compressed(),
2055 is_args_multi_lined,
2057 result.push_str(&where_clause_str);
2058 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2059 return Some((result, force_new_line_for_brace));
2063 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2064 let where_clause_str = rewrite_where_clause(
2067 context.config.brace_style(),
2068 Shape::indented(indent, context.config),
2074 is_args_multi_lined,
2076 // If there are neither where clause nor return type, we may be missing comments between
2078 if where_clause_str.is_empty() {
2079 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2080 match recover_missing_comment_in_span(
2081 mk_sp(args_span.hi(), ret_span.hi()),
2084 last_line_width(&result),
2086 Some(ref missing_comment) if !missing_comment.is_empty() => {
2087 result.push_str(missing_comment);
2088 force_new_line_for_brace = true;
2095 result.push_str(&where_clause_str);
2097 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2098 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2099 Some((result, force_new_line_for_brace))
2102 #[derive(Copy, Clone)]
2103 struct WhereClauseOption {
2104 suppress_comma: bool, // Force no trailing comma
2105 snuggle: bool, // Do not insert newline before `where`
2106 compress_where: bool, // Try single line where clause instead of vertical layout
2109 impl WhereClauseOption {
2110 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2112 suppress_comma: suppress_comma,
2114 compress_where: false,
2118 pub fn compressed() -> WhereClauseOption {
2120 suppress_comma: true,
2122 compress_where: true,
2126 pub fn snuggled(current: &str) -> WhereClauseOption {
2128 suppress_comma: false,
2129 snuggle: trimmed_last_line_width(current) == 1,
2130 compress_where: false,
2136 context: &RewriteContext,
2138 explicit_self: Option<&ast::ExplicitSelf>,
2139 one_line_budget: usize,
2140 multi_line_budget: usize,
2145 generics_str_contains_newline: bool,
2146 ) -> Option<String> {
2147 let mut arg_item_strs = args.iter()
2149 arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent))
2151 .collect::<Option<Vec<_>>>()?;
2153 // Account for sugary self.
2154 // FIXME: the comment for the self argument is dropped. This is blocked
2155 // on rust issue #27522.
2156 let min_args = explicit_self
2157 .and_then(|explicit_self| {
2158 rewrite_explicit_self(explicit_self, args, context)
2160 .map_or(1, |self_str| {
2161 arg_item_strs[0] = self_str;
2165 // Comments between args.
2166 let mut arg_items = Vec::new();
2168 arg_items.push(ListItem::from_str(""));
2171 // FIXME(#21): if there are no args, there might still be a comment, but
2172 // without spans for the comment or parens, there is no chance of
2173 // getting it right. You also don't get to put a comment on self, unless
2175 if args.len() >= min_args || variadic {
2176 let comment_span_start = if min_args == 2 {
2177 let second_arg_start = if arg_has_pattern(&args[1]) {
2178 args[1].pat.span.lo()
2180 args[1].ty.span.lo()
2182 let reduced_span = mk_sp(span.lo(), second_arg_start);
2184 context.codemap.span_after_last(reduced_span, ",")
2189 enum ArgumentKind<'a> {
2190 Regular(&'a ast::Arg),
2194 let variadic_arg = if variadic {
2195 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2196 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2197 Some(ArgumentKind::Variadic(variadic_start))
2202 let more_items = itemize_list(
2204 args[min_args - 1..]
2206 .map(ArgumentKind::Regular)
2207 .chain(variadic_arg),
2211 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2212 ArgumentKind::Variadic(start) => start,
2215 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2216 ArgumentKind::Variadic(start) => start + BytePos(3),
2219 ArgumentKind::Regular(..) => None,
2220 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2227 arg_items.extend(more_items);
2230 let fits_in_one_line = !generics_str_contains_newline
2231 && (arg_items.is_empty()
2232 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2234 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2235 item.item = Some(arg);
2238 let last_line_ends_with_comment = arg_items
2241 .and_then(|item| item.post_comment.as_ref())
2242 .map_or(false, |s| s.trim().starts_with("//"));
2244 let (indent, trailing_comma) = match context.config.indent_style() {
2245 IndentStyle::Block if fits_in_one_line => {
2246 (indent.block_indent(context.config), SeparatorTactic::Never)
2248 IndentStyle::Block => (
2249 indent.block_indent(context.config),
2250 context.config.trailing_comma(),
2252 IndentStyle::Visual if last_line_ends_with_comment => {
2253 (arg_indent, context.config.trailing_comma())
2255 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2258 let tactic = definitive_tactic(
2260 context.config.fn_args_density().to_list_tactic(),
2264 let budget = match tactic {
2265 DefinitiveListTactic::Horizontal => one_line_budget,
2266 _ => multi_line_budget,
2269 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2271 let fmt = ListFormatting {
2274 trailing_separator: if variadic {
2275 SeparatorTactic::Never
2279 separator_place: SeparatorPlace::Back,
2280 shape: Shape::legacy(budget, indent),
2281 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2282 preserve_newline: true,
2283 config: context.config,
2286 write_list(&arg_items, &fmt)
2289 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2290 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2291 ident.node != symbol::keywords::Invalid.ident()
2297 fn compute_budgets_for_args(
2298 context: &RewriteContext,
2302 newline_brace: bool,
2304 force_vertical_layout: bool,
2305 ) -> Option<((usize, usize, Indent))> {
2307 "compute_budgets_for_args {} {:?}, {}, {}",
2313 // Try keeping everything on the same line.
2314 if !result.contains('\n') && !force_vertical_layout {
2315 // 2 = `()`, 3 = `() `, space is before ret_string.
2316 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2317 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2327 let one_line_budget = context.budget(used_space);
2329 if one_line_budget > 0 {
2331 let (indent, multi_line_budget) = match context.config.indent_style() {
2332 IndentStyle::Block => {
2333 let indent = indent.block_indent(context.config);
2334 (indent, context.budget(indent.width() + 1))
2336 IndentStyle::Visual => {
2337 let indent = indent + result.len() + 1;
2338 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2339 (indent, context.budget(multi_line_overhead))
2343 return Some((one_line_budget, multi_line_budget, indent));
2347 // Didn't work. we must force vertical layout and put args on a newline.
2348 let new_indent = indent.block_indent(context.config);
2349 let used_space = match context.config.indent_style() {
2351 IndentStyle::Block => new_indent.width() + 1,
2352 // Account for `)` and possibly ` {`.
2353 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2355 Some((0, context.budget(used_space), new_indent))
2358 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause, has_body: bool) -> bool {
2359 let predicate_count = where_clause.predicates.len();
2361 if config.where_single_line() && predicate_count == 1 {
2364 match (config.brace_style(), config.where_density()) {
2365 (BraceStyle::AlwaysNextLine, _) => true,
2366 (_, Density::Compressed) if predicate_count == 1 => false,
2367 (_, Density::CompressedIfEmpty) if predicate_count == 1 && !has_body => false,
2368 (BraceStyle::SameLineWhere, _) if predicate_count > 0 => true,
2373 fn rewrite_generics(
2374 context: &RewriteContext,
2375 generics: &ast::Generics,
2378 ) -> Option<String> {
2379 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2380 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2381 rewrite_generics_inner(context, generics, g_shape, one_line_width, span).or_else(|| {
2382 rewrite_generics_inner(context, generics, g_shape, 0, span)
2386 fn rewrite_generics_inner(
2387 context: &RewriteContext,
2388 generics: &ast::Generics,
2390 one_line_width: usize,
2392 ) -> Option<String> {
2393 // FIXME: convert bounds to where clauses where they get too big or if
2394 // there is a where clause at all.
2397 enum GenericsArg<'a> {
2398 Lifetime(&'a ast::LifetimeDef),
2399 TyParam(&'a ast::TyParam),
2401 impl<'a> Rewrite for GenericsArg<'a> {
2402 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2404 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2405 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2409 impl<'a> Spanned for GenericsArg<'a> {
2410 fn span(&self) -> Span {
2412 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2413 GenericsArg::TyParam(ty) => ty.span(),
2418 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2419 return Some(String::new());
2422 let generics_args = generics
2425 .map(|lt| GenericsArg::Lifetime(lt))
2426 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2427 let items = itemize_list(
2432 |arg| arg.span().lo(),
2433 |arg| arg.span().hi(),
2434 |arg| arg.rewrite(context, shape),
2435 context.codemap.span_after(span, "<"),
2439 format_generics_item_list(context, items, shape, one_line_width)
2442 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2443 match config.indent_style() {
2444 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2445 IndentStyle::Block => {
2449 .block_indent(config.tab_spaces())
2450 .with_max_width(config)
2456 pub fn format_generics_item_list<I>(
2457 context: &RewriteContext,
2460 one_line_budget: usize,
2463 I: Iterator<Item = ListItem>,
2465 let item_vec = items.collect::<Vec<_>>();
2467 let tactic = definitive_tactic(
2469 ListTactic::HorizontalVertical,
2473 let fmt = ListFormatting {
2476 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2477 SeparatorTactic::Never
2479 context.config.trailing_comma()
2481 separator_place: SeparatorPlace::Back,
2483 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2484 preserve_newline: true,
2485 config: context.config,
2488 let list_str = write_list(&item_vec, &fmt)?;
2490 Some(wrap_generics_with_angle_brackets(
2497 pub fn wrap_generics_with_angle_brackets(
2498 context: &RewriteContext,
2500 list_offset: Indent,
2502 if context.config.indent_style() == IndentStyle::Block
2503 && (list_str.contains('\n') || list_str.ends_with(','))
2507 list_offset.to_string(context.config),
2510 .block_unindent(context.config)
2511 .to_string(context.config)
2513 } else if context.config.spaces_within_parens_and_brackets() {
2514 format!("< {} >", list_str)
2516 format!("<{}>", list_str)
2520 fn rewrite_trait_bounds(
2521 context: &RewriteContext,
2522 type_param_bounds: &ast::TyParamBounds,
2524 ) -> Option<String> {
2525 let bounds: &[_] = type_param_bounds;
2527 if bounds.is_empty() {
2528 return Some(String::new());
2530 let bound_str = bounds
2532 .map(|ty_bound| ty_bound.rewrite(context, shape))
2533 .collect::<Option<Vec<_>>>()?;
2534 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2537 fn rewrite_where_clause_rfc_style(
2538 context: &RewriteContext,
2539 where_clause: &ast::WhereClause,
2542 span_end: Option<BytePos>,
2543 span_end_before_where: BytePos,
2544 where_clause_option: WhereClauseOption,
2545 is_args_multi_line: bool,
2546 ) -> Option<String> {
2547 let block_shape = shape.block().with_max_width(context.config);
2549 let (span_before, span_after) =
2550 missing_span_before_after_where(span_end_before_where, where_clause);
2551 let (comment_before, comment_after) =
2552 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2554 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2557 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2560 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2562 let clause_shape = clause_shape.sub_width(1)?;
2563 // each clause on one line, trailing comma (except if suppress_comma)
2564 let span_start = where_clause.predicates[0].span().lo();
2565 // If we don't have the start of the next span, then use the end of the
2566 // predicates, but that means we miss comments.
2567 let len = where_clause.predicates.len();
2568 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2569 let span_end = span_end.unwrap_or(end_of_preds);
2570 let items = itemize_list(
2572 where_clause.predicates.iter(),
2575 |pred| pred.span().lo(),
2576 |pred| pred.span().hi(),
2577 |pred| pred.rewrite(context, clause_shape),
2582 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2583 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2584 SeparatorTactic::Never
2586 context.config.trailing_comma()
2589 // shape should be vertical only and only if we have `where_single_line` option enabled
2590 // and the number of items of the where clause is equal to 1
2591 let shape_tactic = if where_single_line {
2592 DefinitiveListTactic::Horizontal
2594 DefinitiveListTactic::Vertical
2597 let fmt = ListFormatting {
2598 tactic: shape_tactic,
2600 trailing_separator: comma_tactic,
2601 separator_place: SeparatorPlace::Back,
2602 shape: clause_shape,
2603 ends_with_newline: true,
2604 preserve_newline: true,
2605 config: context.config,
2607 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2609 let comment_separator = |comment: &str, shape: Shape| if comment.is_empty() {
2612 format!("\n{}", shape.indent.to_string(context.config))
2614 let newline_before_where = comment_separator(&comment_before, shape);
2615 let newline_after_where = comment_separator(&comment_after, clause_shape);
2618 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2619 && comment_after.is_empty() && !preds_str.contains('\n')
2620 && 6 + preds_str.len() <= shape.width || where_single_line
2624 format!("\n{}", clause_shape.indent.to_string(context.config))
2627 "{}{}{}where{}{}{}{}",
2630 newline_before_where,
2631 newline_after_where,
2638 fn rewrite_where_clause(
2639 context: &RewriteContext,
2640 where_clause: &ast::WhereClause,
2641 brace_style: BraceStyle,
2645 span_end: Option<BytePos>,
2646 span_end_before_where: BytePos,
2647 where_clause_option: WhereClauseOption,
2648 is_args_multi_line: bool,
2649 ) -> Option<String> {
2650 if where_clause.predicates.is_empty() {
2651 return Some(String::new());
2654 if context.config.indent_style() == IndentStyle::Block {
2655 return rewrite_where_clause_rfc_style(
2661 span_end_before_where,
2662 where_clause_option,
2667 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2669 let offset = match context.config.indent_style() {
2670 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2671 // 6 = "where ".len()
2672 IndentStyle::Visual => shape.indent + extra_indent + 6,
2674 // FIXME: if indent_style != Visual, then the budgets below might
2675 // be out by a char or two.
2677 let budget = context.config.max_width() - offset.width();
2678 let span_start = where_clause.predicates[0].span().lo();
2679 // If we don't have the start of the next span, then use the end of the
2680 // predicates, but that means we miss comments.
2681 let len = where_clause.predicates.len();
2682 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2683 let span_end = span_end.unwrap_or(end_of_preds);
2684 let items = itemize_list(
2686 where_clause.predicates.iter(),
2689 |pred| pred.span().lo(),
2690 |pred| pred.span().hi(),
2691 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2696 let item_vec = items.collect::<Vec<_>>();
2697 // FIXME: we don't need to collect here if the where_layout isn't
2698 // HorizontalVertical.
2699 let tactic = definitive_tactic(
2701 context.config.where_layout(),
2706 let mut comma_tactic = context.config.trailing_comma();
2707 // Kind of a hack because we don't usually have trailing commas in where clauses.
2708 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2709 comma_tactic = SeparatorTactic::Never;
2712 let fmt = ListFormatting {
2715 trailing_separator: comma_tactic,
2716 separator_place: SeparatorPlace::Back,
2717 shape: Shape::legacy(budget, offset),
2718 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2719 preserve_newline: true,
2720 config: context.config,
2722 let preds_str = write_list(&item_vec, &fmt)?;
2724 let end_length = if terminator == "{" {
2725 // If the brace is on the next line we don't need to count it otherwise it needs two
2728 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2729 BraceStyle::PreferSameLine => 2,
2731 } else if terminator == "=" {
2736 if density == Density::Tall || preds_str.contains('\n')
2737 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2741 (shape.indent + extra_indent).to_string(context.config),
2745 Some(format!(" where {}", preds_str))
2749 fn missing_span_before_after_where(
2750 before_item_span_end: BytePos,
2751 where_clause: &ast::WhereClause,
2753 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2755 let pos_after_where = where_clause.span.lo() + BytePos(5);
2756 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2757 (missing_span_before, missing_span_after)
2760 fn rewrite_comments_before_after_where(
2761 context: &RewriteContext,
2762 span_before_where: Span,
2763 span_after_where: Span,
2765 ) -> Option<(String, String)> {
2766 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2767 let after_comment = rewrite_missing_comment(
2769 shape.block_indent(context.config.tab_spaces()),
2772 Some((before_comment, after_comment))
2775 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2776 format!("{}{}{}", format_visibility(vis), item_name, ident)
2779 #[derive(PartialEq, Eq)]
2787 context: &RewriteContext,
2788 generics: &ast::Generics,
2789 brace_style: BraceStyle,
2790 brace_pos: BracePos,
2794 ) -> Option<String> {
2795 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2796 let mut result = rewrite_generics(context, generics, shape, span)?;
2798 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2799 let budget = context.budget(last_line_used_width(&result, offset.width()));
2800 let mut option = WhereClauseOption::snuggled(&result);
2801 if brace_pos == BracePos::None {
2802 option.suppress_comma = true;
2804 // If the generics are not parameterized then generics.span.hi() == 0,
2805 // so we use span.lo(), which is the position after `struct Foo`.
2806 let span_end_before_where = if generics.is_parameterized() {
2811 let where_clause_str = rewrite_where_clause(
2813 &generics.where_clause,
2815 Shape::legacy(budget, offset.block_only()),
2819 span_end_before_where,
2823 result.push_str(&where_clause_str);
2824 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2825 || (generics.where_clause.predicates.is_empty()
2826 && trimmed_last_line_width(&result) == 1)
2828 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2829 || brace_style != BraceStyle::AlwaysNextLine
2831 if brace_pos == BracePos::None {
2832 return Some(result);
2834 let total_used_width = last_line_used_width(&result, used_width);
2835 let remaining_budget = context.budget(total_used_width);
2836 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2837 // and hence we take the closer into account as well for one line budget.
2838 // We assume that the closer has the same length as the opener.
2839 let overhead = if brace_pos == BracePos::ForceSameLine {
2846 let forbid_same_line_brace = overhead > remaining_budget;
2847 if !forbid_same_line_brace && same_line_brace {
2851 result.push_str(&offset.block_only().to_string(context.config));
2858 impl Rewrite for ast::ForeignItem {
2859 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2860 let attrs_str = self.attrs.rewrite(context, shape)?;
2861 // Drop semicolon or it will be interpreted as comment.
2862 // FIXME: this may be a faulty span from libsyntax.
2863 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2865 let item_str = match self.node {
2866 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2871 &FnSig::new(fn_decl, generics, self.vis.clone()),
2875 ).map(|(s, _)| format!("{};", s))
2877 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2878 // FIXME(#21): we're dropping potential comments in between the
2879 // function keywords here.
2880 let vis = format_visibility(&self.vis);
2881 let mut_str = if is_mutable { "mut " } else { "" };
2882 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2884 let shape = shape.sub_width(1)?;
2885 ty.rewrite(context, shape).map(|ty_str| {
2886 // 1 = space between prefix and type.
2887 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2890 let nested_indent = shape.indent.block_indent(context.config);
2891 format!("\n{}", nested_indent.to_string(context.config))
2893 format!("{}{}{};", prefix, sep, ty_str)
2896 ast::ForeignItemKind::Ty => {
2897 let vis = format_visibility(&self.vis);
2898 Some(format!("{}type {};", vis, self.ident))
2902 let missing_span = if self.attrs.is_empty() {
2903 mk_sp(self.span.lo(), self.span.lo())
2905 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2907 combine_strs_with_missing_comments(