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, ReturnIndent};
26 use expr::{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 items = itemize_list(
489 enum_def.variants.iter(),
491 |f| if !f.node.attrs.is_empty() {
492 f.node.attrs[0].span.lo()
497 |f| self.format_variant(f),
503 let shape = self.shape().sub_width(2).unwrap();
504 let fmt = ListFormatting {
505 tactic: DefinitiveListTactic::Vertical,
507 trailing_separator: self.config.trailing_comma(),
508 separator_place: SeparatorPlace::Back,
510 ends_with_newline: true,
511 preserve_newline: true,
515 let list = write_list(&items.collect::<Vec<_>>(), &fmt)?;
516 result.push_str(&list);
521 // Variant of an enum.
522 fn format_variant(&self, field: &ast::Variant) -> Option<String> {
523 if contains_skip(&field.node.attrs) {
524 let lo = field.node.attrs[0].span.lo();
525 let span = mk_sp(lo, field.span.hi());
526 return Some(self.snippet(span));
529 let context = self.get_context();
530 let indent = self.block_indent;
531 let shape = self.shape();
532 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
537 .map_or(field.span.lo(), |attr| attr.span.hi());
538 let span = mk_sp(lo, field.span.lo());
540 let variant_body = match field.node.data {
541 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => {
542 // FIXME: Should limit the width, as we have a trailing comma
545 &StructParts::from_variant(field),
547 Some(self.config.struct_variant_width()),
550 ast::VariantData::Unit(..) => if let Some(ref expr) = field.node.disr_expr {
551 let lhs = format!("{} =", field.node.name);
553 rewrite_assign_rhs(&context, lhs, &**expr, shape.sub_width(1)?)?
555 field.node.name.to_string()
559 let attrs_extendable = attrs_str.is_empty()
560 || (context.config.attributes_on_same_line_as_variant()
561 && is_attributes_extendable(&attrs_str));
562 combine_strs_with_missing_comments(
574 context: &RewriteContext,
577 where_span_end: Option<BytePos>,
578 ) -> Option<String> {
579 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
580 let mut result = String::with_capacity(128);
581 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
582 let indent_str = offset.to_string(context.config);
583 let sep = format!("\n{}", &indent_str);
584 result.push_str(&ref_and_type);
586 let where_budget = if result.contains('\n') {
587 context.config.max_width()
589 context.budget(last_line_width(&result))
591 let option = WhereClauseOption::snuggled(&ref_and_type);
592 let where_clause_str = rewrite_where_clause(
594 &generics.where_clause,
595 context.config.brace_style(),
596 Shape::legacy(where_budget, offset.block_only()),
597 context.config.where_density(),
605 // If there is no where clause, we may have missing comments between the trait name and
606 // the opening brace.
607 if generics.where_clause.predicates.is_empty() {
608 if let Some(hi) = where_span_end {
609 match recover_missing_comment_in_span(
610 mk_sp(self_ty.span.hi(), hi),
611 Shape::indented(offset, context.config),
613 last_line_width(&result),
615 Some(ref missing_comment) if !missing_comment.is_empty() => {
616 result.push_str(missing_comment);
623 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
624 result.push_str(&where_clause_str);
625 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
626 result.push_str(&format!("{}{{{}}}", &sep, &sep));
628 result.push_str(" {}");
633 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
635 let width = offset.block_indent + context.config.tab_spaces() - 1;
636 let where_indent = Indent::new(0, width);
637 result.push_str(&where_indent.to_string(context.config));
639 result.push_str(&where_clause_str);
641 match context.config.brace_style() {
642 _ if last_line_contains_single_line_comment(&result) => result.push_str(&sep),
643 BraceStyle::AlwaysNextLine => result.push_str(&sep),
644 BraceStyle::PreferSameLine => result.push(' '),
645 BraceStyle::SameLineWhere => if !where_clause_str.is_empty() {
646 result.push_str(&sep);
654 let snippet = context.snippet(item.span);
655 let open_pos = snippet.find_uncommented("{")? + 1;
657 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
658 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
659 visitor.block_indent = offset.block_only().block_indent(context.config);
660 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
662 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
664 visitor.visit_impl_item(item);
667 visitor.format_missing(item.span.hi() - BytePos(1));
669 let inner_indent_str = visitor.block_indent.to_string(context.config);
670 let outer_indent_str = offset.block_only().to_string(context.config);
673 result.push_str(&inner_indent_str);
674 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
676 result.push_str(&outer_indent_str);
679 if result.ends_with('{') {
680 result.push_str(&sep);
690 fn is_impl_single_line(
691 context: &RewriteContext,
694 where_clause_str: &str,
697 let snippet = context.snippet(item.span);
698 let open_pos = snippet.find_uncommented("{")? + 1;
701 context.config.impl_empty_single_line() && items.is_empty() && !result.contains('\n')
702 && result.len() + where_clause_str.len() <= context.config.max_width()
703 && !contains_comment(&snippet[open_pos..]),
707 fn format_impl_ref_and_type(
708 context: &RewriteContext,
711 ) -> Option<String> {
712 if let ast::ItemKind::Impl(
722 let mut result = String::with_capacity(128);
724 result.push_str(&format_visibility(&item.vis));
725 result.push_str(format_defaultness(defaultness));
726 result.push_str(format_unsafety(unsafety));
727 result.push_str("impl");
729 let lo = context.codemap.span_after(item.span, "impl");
730 let hi = match *trait_ref {
731 Some(ref tr) => tr.path.span.lo(),
732 None => self_ty.span.lo(),
734 let shape = generics_shape_from_config(
736 Shape::indented(offset + last_line_width(&result), context.config),
739 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
741 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
743 let polarity_str = if polarity == ast::ImplPolarity::Negative {
749 if let Some(ref trait_ref) = *trait_ref {
750 let result_len = result.len();
751 if let Some(trait_ref_str) = rewrite_trait_ref(
760 result.push_str(&trait_ref_str);
763 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
764 result.push_str(&rewrite_trait_ref(
775 result.push_str(&generics_str);
778 // Try to put the self type in a single line.
780 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
781 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
782 // If there is no where clause adapt budget for type formatting to take space and curly
783 // brace into account.
784 match context.config.brace_style() {
785 BraceStyle::AlwaysNextLine => 0,
791 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
792 // 1 = space before the type.
793 let budget = context.budget(used_space + 1);
794 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
795 if !self_ty_str.contains('\n') {
796 if trait_ref.is_some() {
797 result.push_str(" for ");
801 result.push_str(&self_ty_str);
806 // Couldn't fit the self type on a single line, put it on a new line.
808 // Add indentation of one additional tab.
809 let new_line_offset = offset.block_indent(context.config);
810 result.push_str(&new_line_offset.to_string(context.config));
811 if trait_ref.is_some() {
812 result.push_str("for ");
814 let budget = context.budget(last_line_width(&result));
815 let type_offset = match context.config.indent_style() {
816 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
817 IndentStyle::Block => new_line_offset,
819 result.push_str(&*self_ty
820 .rewrite(context, Shape::legacy(budget, type_offset))?);
827 fn rewrite_trait_ref(
828 context: &RewriteContext,
829 trait_ref: &ast::TraitRef,
835 ) -> Option<String> {
836 // 1 = space between generics and trait_ref
837 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
838 let shape = Shape::indented(offset + used_space, context.config);
839 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
840 if !(retry && trait_ref_str.contains('\n')) {
849 // We could not make enough space for trait_ref, so put it on new line.
851 let offset = offset.block_indent(context.config);
852 let shape = Shape::indented(offset, context.config);
853 let trait_ref_str = trait_ref.rewrite(context, shape)?;
857 &offset.to_string(context.config),
866 pub struct StructParts<'a> {
869 vis: &'a ast::Visibility,
870 def: &'a ast::VariantData,
871 generics: Option<&'a ast::Generics>,
875 impl<'a> StructParts<'a> {
876 fn format_header(&self) -> String {
877 format_header(self.prefix, self.ident, self.vis)
880 fn from_variant(variant: &'a ast::Variant) -> Self {
883 ident: variant.node.name,
884 vis: &ast::Visibility::Inherited,
885 def: &variant.node.data,
891 pub fn from_item(item: &'a ast::Item) -> Self {
892 let (prefix, def, generics) = match item.node {
893 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
894 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
902 generics: Some(generics),
909 context: &RewriteContext,
910 struct_parts: &StructParts,
912 one_line_width: Option<usize>,
913 ) -> Option<String> {
914 match *struct_parts.def {
915 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
916 ast::VariantData::Tuple(ref fields, _) => {
917 format_tuple_struct(context, struct_parts, fields, offset)
919 ast::VariantData::Struct(ref fields, _) => {
920 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
925 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
926 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
929 let mut result = String::with_capacity(128);
930 let header = format!(
932 format_visibility(&item.vis),
933 format_unsafety(unsafety),
937 result.push_str(&header);
939 let body_lo = context.codemap.span_after(item.span, "{");
941 let shape = Shape::indented(offset, context.config);
943 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
944 result.push_str(&generics_str);
946 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
947 if !type_param_bounds.is_empty() {
948 let ident_hi = context.codemap.span_after(item.span, &format!("{}", item.ident));
949 let bound_hi = type_param_bounds.last().unwrap().span().hi();
950 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
951 if contains_comment(&snippet) {
955 let trait_bound_str = rewrite_trait_bounds(
958 Shape::indented(offset, context.config),
960 // If the trait, generics, and trait bound cannot fit on the same line,
961 // put the trait bounds on an indented new line
962 if offset.width() + last_line_width(&result) + trait_bound_str.len()
963 > context.config.comment_width()
966 let trait_indent = offset.block_only().block_indent(context.config);
967 result.push_str(&trait_indent.to_string(context.config));
969 result.push_str(&trait_bound_str);
971 let has_body = !trait_items.is_empty();
973 let where_density = if (context.config.where_density() == Density::Compressed
974 && (!result.contains('\n') || context.config.indent_style() == IndentStyle::Block))
975 || (context.config.indent_style() == IndentStyle::Block && result.is_empty())
976 || (context.config.where_density() == Density::CompressedIfEmpty && !has_body
977 && !result.contains('\n'))
984 let where_budget = context.budget(last_line_width(&result));
985 let pos_before_where = if type_param_bounds.is_empty() {
986 generics.where_clause.span.lo()
988 type_param_bounds[type_param_bounds.len() - 1].span().hi()
990 let option = WhereClauseOption::snuggled(&generics_str);
991 let where_clause_str = rewrite_where_clause(
993 &generics.where_clause,
994 context.config.brace_style(),
995 Shape::legacy(where_budget, offset.block_only()),
1003 // If the where clause cannot fit on the same line,
1004 // put the where clause on a new line
1005 if !where_clause_str.contains('\n')
1006 && last_line_width(&result) + where_clause_str.len() + offset.width()
1007 > context.config.comment_width()
1010 let width = offset.block_indent + context.config.tab_spaces() - 1;
1011 let where_indent = Indent::new(0, width);
1012 result.push_str(&where_indent.to_string(context.config));
1014 result.push_str(&where_clause_str);
1016 if generics.where_clause.predicates.is_empty() {
1017 let item_snippet = context.snippet(item.span);
1018 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1020 let comment_hi = body_lo - BytePos(1);
1021 let comment_lo = item.span.lo() + BytePos(lo as u32);
1022 if comment_lo < comment_hi {
1023 match recover_missing_comment_in_span(
1024 mk_sp(comment_lo, comment_hi),
1025 Shape::indented(offset, context.config),
1027 last_line_width(&result),
1029 Some(ref missing_comment) if !missing_comment.is_empty() => {
1030 result.push_str(missing_comment);
1038 match context.config.brace_style() {
1039 _ if last_line_contains_single_line_comment(&result) => {
1041 result.push_str(&offset.to_string(context.config));
1043 BraceStyle::AlwaysNextLine => {
1045 result.push_str(&offset.to_string(context.config));
1047 BraceStyle::PreferSameLine => result.push(' '),
1048 BraceStyle::SameLineWhere => if !where_clause_str.is_empty()
1049 && (!trait_items.is_empty() || result.contains('\n'))
1052 result.push_str(&offset.to_string(context.config));
1059 let snippet = context.snippet(item.span);
1060 let open_pos = snippet.find_uncommented("{")? + 1;
1062 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1063 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
1064 visitor.block_indent = offset.block_only().block_indent(context.config);
1065 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1067 for item in trait_items {
1068 visitor.visit_trait_item(item);
1071 visitor.format_missing(item.span.hi() - BytePos(1));
1073 let inner_indent_str = visitor.block_indent.to_string(context.config);
1074 let outer_indent_str = offset.block_only().to_string(context.config);
1077 result.push_str(&inner_indent_str);
1078 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1080 result.push_str(&outer_indent_str);
1081 } else if result.contains('\n') {
1092 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1093 let header_str = format_header(p.prefix, p.ident, p.vis);
1094 let generics_str = if let Some(generics) = p.generics {
1095 let hi = if generics.where_clause.predicates.is_empty() {
1098 generics.where_clause.span.hi()
1103 context.config.brace_style(),
1106 mk_sp(generics.span.lo(), hi),
1107 last_line_width(&header_str),
1112 Some(format!("{}{};", header_str, generics_str))
1115 pub fn format_struct_struct(
1116 context: &RewriteContext,
1117 struct_parts: &StructParts,
1118 fields: &[ast::StructField],
1120 one_line_width: Option<usize>,
1121 ) -> Option<String> {
1122 let mut result = String::with_capacity(1024);
1123 let span = struct_parts.span;
1125 let header_str = struct_parts.format_header();
1126 result.push_str(&header_str);
1128 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1129 let body_lo = context.codemap.span_after(span, "{");
1131 let generics_str = match struct_parts.generics {
1132 Some(g) => format_generics(
1135 context.config.brace_style(),
1136 if fields.is_empty() {
1137 BracePos::ForceSameLine
1142 mk_sp(header_hi, body_lo),
1143 last_line_width(&result),
1146 // 3 = ` {}`, 2 = ` {`.
1147 let overhead = if fields.is_empty() { 3 } else { 2 };
1148 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1149 || context.config.max_width() < overhead + result.len()
1151 format!("\n{}{{", offset.block_only().to_string(context.config))
1158 let overhead = if fields.is_empty() { 1 } else { 0 };
1159 let total_width = result.len() + generics_str.len() + overhead;
1160 if !generics_str.is_empty() && !generics_str.contains('\n')
1161 && total_width > context.config.max_width()
1164 result.push_str(&offset.to_string(context.config));
1165 result.push_str(generics_str.trim_left());
1167 result.push_str(&generics_str);
1170 if fields.is_empty() {
1171 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1172 if snippet.trim().is_empty() {
1174 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1176 result.push_str(snippet.trim_right());
1178 result.push_str(&offset.to_string(context.config));
1180 result.push_str(&snippet);
1183 return Some(result);
1187 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1188 let one_line_budget =
1189 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1191 let items_str = rewrite_with_alignment(
1194 Shape::indented(offset, context.config),
1195 mk_sp(body_lo, span.hi()),
1199 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget {
1200 Some(format!("{} {} }}", result, items_str))
1206 .block_indent(context.config)
1207 .to_string(context.config),
1209 offset.to_string(context.config)
1214 /// Returns a bytepos that is after that of `(` in `pub(..)`. If the given visibility does not
1215 /// contain `pub(..)`, then return the `lo` of the `defualt_span`. Yeah, but for what? Well, we need
1216 /// to bypass the `(` in the visibility when creating a span of tuple's body or fn's args.
1217 fn get_bytepos_after_visibility(
1218 context: &RewriteContext,
1219 vis: &ast::Visibility,
1224 ast::Visibility::Crate(s, CrateSugar::PubCrate) => context
1226 .span_after(mk_sp(s.hi(), default_span.hi()), terminator),
1227 ast::Visibility::Crate(s, CrateSugar::JustCrate) => s.hi(),
1228 ast::Visibility::Restricted { ref path, .. } => path.span.hi(),
1229 _ => default_span.lo(),
1233 fn format_tuple_struct(
1234 context: &RewriteContext,
1235 struct_parts: &StructParts,
1236 fields: &[ast::StructField],
1238 ) -> Option<String> {
1239 let mut result = String::with_capacity(1024);
1240 let span = struct_parts.span;
1242 let header_str = struct_parts.format_header();
1243 result.push_str(&header_str);
1245 let body_lo = if fields.is_empty() {
1246 let lo = get_bytepos_after_visibility(context, struct_parts.vis, span, ")");
1247 context.codemap.span_after(mk_sp(lo, span.hi()), "(")
1251 let body_hi = if fields.is_empty() {
1252 context.codemap.span_after(mk_sp(body_lo, span.hi()), ")")
1254 // This is a dirty hack to work around a missing `)` from the span of the last field.
1255 let last_arg_span = fields[fields.len() - 1].span;
1256 if context.snippet(last_arg_span).ends_with(')') {
1261 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1265 let where_clause_str = match struct_parts.generics {
1267 let budget = context.budget(last_line_width(&header_str));
1268 let shape = Shape::legacy(budget, offset);
1269 let g_span = mk_sp(span.lo(), body_lo);
1270 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1271 result.push_str(&generics_str);
1273 let where_budget = context.budget(last_line_width(&result));
1274 let option = WhereClauseOption::new(true, false);
1275 rewrite_where_clause(
1277 &generics.where_clause,
1278 context.config.brace_style(),
1279 Shape::legacy(where_budget, offset.block_only()),
1280 Density::Compressed,
1288 None => "".to_owned(),
1291 if fields.is_empty() {
1293 let used_width = last_line_used_width(&result, offset.width()) + 3;
1294 if used_width > context.config.max_width() {
1296 result.push_str(&offset
1297 .block_indent(context.config)
1298 .to_string(context.config))
1301 let snippet = context.snippet(mk_sp(
1303 context.codemap.span_before(mk_sp(body_lo, span.hi()), ")"),
1305 if snippet.is_empty() {
1307 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1308 result.push_str(snippet.trim_right());
1310 result.push_str(&offset.to_string(context.config));
1312 result.push_str(&snippet);
1316 let shape = Shape::indented(offset, context.config);
1317 let fields = &fields.iter().map(|field| field).collect::<Vec<_>>()[..];
1318 let one_line_width = context.config.fn_call_width();
1319 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1322 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1323 && (result.contains('\n')
1324 || offset.block_indent + result.len() + where_clause_str.len() + 1
1325 > context.config.max_width())
1327 // We need to put the where clause on a new line, but we didn't
1328 // know that earlier, so the where clause will not be indented properly.
1330 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1331 .to_string(context.config));
1333 result.push_str(&where_clause_str);
1338 pub fn rewrite_type_alias(
1339 context: &RewriteContext,
1343 generics: &ast::Generics,
1344 vis: &ast::Visibility,
1346 ) -> Option<String> {
1347 let mut result = String::with_capacity(128);
1349 result.push_str(&format_visibility(vis));
1350 result.push_str("type ");
1351 result.push_str(&ident.to_string());
1354 let shape = Shape::indented(indent + result.len(), context.config).sub_width(2)?;
1355 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo());
1356 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1357 result.push_str(&generics_str);
1359 let where_budget = context.budget(last_line_width(&result));
1360 let option = WhereClauseOption::snuggled(&result);
1361 let where_clause_str = rewrite_where_clause(
1363 &generics.where_clause,
1364 context.config.brace_style(),
1365 Shape::legacy(where_budget, indent),
1366 context.config.where_density(),
1373 result.push_str(&where_clause_str);
1374 if where_clause_str.is_empty() {
1375 result.push_str(" = ");
1377 result.push_str(&format!("\n{}= ", indent.to_string(context.config)));
1380 let line_width = last_line_width(&result);
1381 // This checked_sub may fail as the extra space after '=' is not taken into account
1382 // In that case the budget is set to 0 which will make ty.rewrite retry on a new line
1383 let budget = context.budget(indent.width() + line_width + ";".len());
1384 let type_indent = indent + line_width;
1385 // Try to fit the type on the same line
1386 let ty_str = ty.rewrite(context, Shape::legacy(budget, type_indent))
1388 // The line was too short, try to put the type on the next line
1390 // Remove the space after '='
1392 let type_indent = indent.block_indent(context.config);
1394 result.push_str(&type_indent.to_string(context.config));
1395 let budget = context.budget(type_indent.width() + ";".len());
1396 ty.rewrite(context, Shape::legacy(budget, type_indent))
1398 result.push_str(&ty_str);
1399 result.push_str(";");
1403 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1405 if config.space_before_colon() { " " } else { "" },
1406 if config.space_after_colon() { " " } else { "" },
1410 pub fn rewrite_struct_field_prefix(
1411 context: &RewriteContext,
1412 field: &ast::StructField,
1413 ) -> Option<String> {
1414 let vis = format_visibility(&field.vis);
1415 let type_annotation_spacing = type_annotation_spacing(context.config);
1416 Some(match field.ident {
1417 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1418 None => format!("{}", vis),
1422 impl Rewrite for ast::StructField {
1423 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1424 rewrite_struct_field(context, self, shape, 0)
1428 pub fn rewrite_struct_field(
1429 context: &RewriteContext,
1430 field: &ast::StructField,
1432 lhs_max_width: usize,
1433 ) -> Option<String> {
1434 if contains_skip(&field.attrs) {
1435 return Some(context.snippet(mk_sp(field.attrs[0].span.lo(), field.span.hi())));
1438 let type_annotation_spacing = type_annotation_spacing(context.config);
1439 let prefix = rewrite_struct_field_prefix(context, field)?;
1441 let attrs_str = field.attrs.rewrite(context, shape)?;
1442 let attrs_extendable = attrs_str.is_empty()
1443 || (context.config.attributes_on_same_line_as_field()
1444 && is_attributes_extendable(&attrs_str));
1445 let missing_span = if field.attrs.is_empty() {
1446 mk_sp(field.span.lo(), field.span.lo())
1448 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1450 let mut spacing = String::from(if field.ident.is_some() {
1451 type_annotation_spacing.1
1455 // Try to put everything on a single line.
1456 let attr_prefix = combine_strs_with_missing_comments(
1464 let overhead = last_line_width(&attr_prefix);
1465 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1466 for _ in 0..lhs_offset {
1469 // In this extreme case we will be missing a space betweeen an attribute and a field.
1470 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1473 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1474 if let Some(ref ty) = field.ty.rewrite(context, ty_shape) {
1475 if !ty.contains('\n') {
1476 return Some(attr_prefix + &spacing + ty);
1480 // We must use multiline.
1481 let new_shape = shape.with_max_width(context.config);
1482 let ty_rewritten = field.ty.rewrite(context, new_shape)?;
1484 let field_str = if prefix.is_empty() {
1486 } else if prefix.len() + first_line_width(&ty_rewritten) + 1 <= shape.width {
1487 prefix + " " + &ty_rewritten
1489 let type_offset = shape.indent.block_indent(context.config);
1490 let nested_shape = Shape::indented(type_offset, context.config);
1491 let nested_ty = field.ty.rewrite(context, nested_shape)?;
1492 prefix + "\n" + &type_offset.to_string(context.config) + &nested_ty
1494 combine_strs_with_missing_comments(
1504 pub struct StaticParts<'a> {
1506 vis: &'a ast::Visibility,
1509 mutability: ast::Mutability,
1510 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1514 impl<'a> StaticParts<'a> {
1515 pub fn from_item(item: &'a ast::Item) -> Self {
1516 let (prefix, ty, mutability, expr) = match item.node {
1517 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1518 ast::ItemKind::Const(ref ty, ref expr) => {
1519 ("const", ty, ast::Mutability::Immutable, expr)
1521 _ => unreachable!(),
1528 mutability: mutability,
1529 expr_opt: Some(expr),
1534 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1535 let (ty, expr_opt) = match ti.node {
1536 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1537 _ => unreachable!(),
1541 vis: &ast::Visibility::Inherited,
1544 mutability: ast::Mutability::Immutable,
1545 expr_opt: expr_opt.as_ref(),
1550 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1551 let (ty, expr) = match ii.node {
1552 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1553 _ => unreachable!(),
1560 mutability: ast::Mutability::Immutable,
1561 expr_opt: Some(expr),
1568 context: &RewriteContext,
1569 static_parts: &StaticParts,
1571 ) -> Option<String> {
1572 let colon = colon_spaces(
1573 context.config.space_before_colon(),
1574 context.config.space_after_colon(),
1576 let prefix = format!(
1578 format_visibility(static_parts.vis),
1579 static_parts.prefix,
1580 format_mutability(static_parts.mutability),
1586 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1587 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1589 if let Some(expr) = static_parts.expr_opt {
1590 let lhs = format!("{}{} =", prefix, ty_str);
1592 let remaining_width = context.budget(offset.block_indent + 1);
1597 Shape::legacy(remaining_width, offset.block_only()),
1599 recover_comment_removed(res, static_parts.span, context)
1601 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1603 Some(format!("{}{};", prefix, ty_str))
1607 pub fn rewrite_associated_type(
1609 ty_opt: Option<&ptr::P<ast::Ty>>,
1610 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1611 context: &RewriteContext,
1613 ) -> Option<String> {
1614 let prefix = format!("type {}", ident);
1616 let type_bounds_str = if let Some(ty_param_bounds) = ty_param_bounds_opt {
1618 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1619 let bounds: &[_] = ty_param_bounds;
1620 let bound_str = bounds
1622 .map(|ty_bound| ty_bound.rewrite(context, shape))
1623 .collect::<Option<Vec<_>>>()?;
1624 if !bounds.is_empty() {
1625 format!(": {}", join_bounds(context, shape, &bound_str))
1633 if let Some(ty) = ty_opt {
1634 let ty_str = ty.rewrite(
1637 context.budget(indent.block_indent + prefix.len() + 2),
1638 indent.block_only(),
1641 Some(format!("{}{} = {};", prefix, type_bounds_str, ty_str))
1643 Some(format!("{}{};", prefix, type_bounds_str))
1647 pub fn rewrite_associated_impl_type(
1649 defaultness: ast::Defaultness,
1650 ty_opt: Option<&ptr::P<ast::Ty>>,
1651 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1652 context: &RewriteContext,
1654 ) -> Option<String> {
1655 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1658 ast::Defaultness::Default => Some(format!("default {}", result)),
1663 impl Rewrite for ast::FunctionRetTy {
1664 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1666 ast::FunctionRetTy::Default(_) => Some(String::new()),
1667 ast::FunctionRetTy::Ty(ref ty) => {
1668 let inner_width = shape.width.checked_sub(3)?;
1669 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1670 .map(|r| format!("-> {}", r))
1676 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1678 ast::TyKind::Infer => {
1679 let original = context.snippet(ty.span);
1686 impl Rewrite for ast::Arg {
1687 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1688 if is_named_arg(self) {
1689 let mut result = self.pat
1690 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1692 if !is_empty_infer(context, &*self.ty) {
1693 if context.config.space_before_colon() {
1694 result.push_str(" ");
1696 result.push_str(":");
1697 if context.config.space_after_colon() {
1698 result.push_str(" ");
1700 let overhead = last_line_width(&result);
1701 let max_width = shape.width.checked_sub(overhead)?;
1702 let ty_str = self.ty
1703 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1704 result.push_str(&ty_str);
1709 self.ty.rewrite(context, shape)
1714 fn rewrite_explicit_self(
1715 explicit_self: &ast::ExplicitSelf,
1717 context: &RewriteContext,
1718 ) -> Option<String> {
1719 match explicit_self.node {
1720 ast::SelfKind::Region(lt, m) => {
1721 let mut_str = format_mutability(m);
1724 let lifetime_str = l.rewrite(
1726 Shape::legacy(context.config.max_width(), Indent::empty()),
1728 Some(format!("&{} {}self", lifetime_str, mut_str))
1730 None => Some(format!("&{}self", mut_str)),
1733 ast::SelfKind::Explicit(ref ty, _) => {
1734 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1736 let mutability = explicit_self_mutability(&args[0]);
1737 let type_str = ty.rewrite(
1739 Shape::legacy(context.config.max_width(), Indent::empty()),
1744 format_mutability(mutability),
1748 ast::SelfKind::Value(_) => {
1749 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1751 let mutability = explicit_self_mutability(&args[0]);
1753 Some(format!("{}self", format_mutability(mutability)))
1758 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1759 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1760 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1761 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1768 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1769 if is_named_arg(arg) {
1776 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1778 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1779 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1780 _ => arg.ty.span.hi(),
1784 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1785 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1786 ident.node != symbol::keywords::Invalid.ident()
1792 // Return type is (result, force_new_line_for_brace)
1794 context: &RewriteContext,
1799 newline_brace: bool,
1801 ) -> Option<(String, bool)> {
1802 let mut force_new_line_for_brace = false;
1804 let where_clause = &fn_sig.generics.where_clause;
1806 let mut result = String::with_capacity(1024);
1807 result.push_str(&fn_sig.to_str(context));
1810 result.push_str("fn ");
1811 result.push_str(&ident.to_string());
1814 let overhead = if has_body && !newline_brace {
1821 let used_width = last_line_used_width(&result, indent.width());
1822 let one_line_budget = context.budget(used_width + overhead);
1824 width: one_line_budget,
1828 let fd = fn_sig.decl;
1829 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1830 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1831 result.push_str(&generics_str);
1833 let snuggle_angle_bracket = generics_str
1836 .map_or(false, |l| l.trim_left().len() == 1);
1838 // Note that the width and indent don't really matter, we'll re-layout the
1839 // return type later anyway.
1840 let ret_str = fd.output
1841 .rewrite(context, Shape::indented(indent, context.config))?;
1843 let multi_line_ret_str = ret_str.contains('\n');
1844 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1847 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1858 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1864 // Check if vertical layout was forced.
1865 if one_line_budget == 0 {
1866 if snuggle_angle_bracket {
1868 } else if context.config.fn_args_paren_newline() {
1870 result.push_str(&arg_indent.to_string(context.config));
1871 if context.config.indent_style() == IndentStyle::Visual {
1872 arg_indent = arg_indent + 1; // extra space for `(`
1876 result.push_str("(");
1877 if context.config.indent_style() == IndentStyle::Visual {
1879 result.push_str(&arg_indent.to_string(context.config));
1885 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1886 && result.ends_with('(')
1891 // Skip `pub(crate)`.
1892 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1893 // A conservative estimation, to goal is to be over all parens in generics
1894 let args_start = fn_sig
1898 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1899 let args_end = if fd.inputs.is_empty() {
1902 .span_after(mk_sp(args_start, span.hi()), ")")
1904 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1905 context.codemap.span_after(last_span, ")")
1907 let args_span = mk_sp(
1910 .span_after(mk_sp(args_start, span.hi()), "("),
1913 let arg_str = rewrite_args(
1916 fd.get_self().as_ref(),
1923 generics_str.contains('\n'),
1926 let put_args_in_block = match context.config.indent_style() {
1927 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1929 } && !fd.inputs.is_empty();
1931 let mut args_last_line_contains_comment = false;
1932 if put_args_in_block {
1933 arg_indent = indent.block_indent(context.config);
1935 result.push_str(&arg_indent.to_string(context.config));
1936 result.push_str(&arg_str);
1938 result.push_str(&indent.to_string(context.config));
1941 result.push_str(&arg_str);
1942 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1943 // Put the closing brace on the next line if it overflows the max width.
1945 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1948 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1951 // If the last line of args contains comment, we cannot put the closing paren
1952 // on the same line.
1956 .map_or(false, |last_line| last_line.contains("//"))
1958 args_last_line_contains_comment = true;
1960 result.push_str(&arg_indent.to_string(context.config));
1966 if let ast::FunctionRetTy::Ty(..) = fd.output {
1967 let ret_should_indent = match context.config.indent_style() {
1968 // If our args are block layout then we surely must have space.
1969 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1970 _ if args_last_line_contains_comment => false,
1971 _ if result.contains('\n') || multi_line_ret_str => true,
1973 // If the return type would push over the max width, then put the return type on
1974 // a new line. With the +1 for the signature length an additional space between
1975 // the closing parenthesis of the argument and the arrow '->' is considered.
1976 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1978 // If there is no where clause, take into account the space after the return type
1980 if where_clause.predicates.is_empty() {
1984 sig_length > context.config.max_width()
1987 let ret_indent = if ret_should_indent {
1988 let indent = match context.config.fn_return_indent() {
1989 ReturnIndent::WithWhereClause => indent + 4,
1990 // Aligning with non-existent args looks silly.
1991 _ if arg_str.is_empty() => {
1992 force_new_line_for_brace = true;
1995 // FIXME: we might want to check that using the arg indent
1996 // doesn't blow our budget, and if it does, then fallback to
1997 // the where clause indent.
2002 result.push_str(&indent.to_string(context.config));
2006 Indent::new(indent.block_indent, last_line_width(&result))
2009 if multi_line_ret_str || ret_should_indent {
2010 // Now that we know the proper indent and width, we need to
2011 // re-layout the return type.
2012 let ret_str = fd.output
2013 .rewrite(context, Shape::indented(ret_indent, context.config))?;
2014 result.push_str(&ret_str);
2016 result.push_str(&ret_str);
2019 // Comment between return type and the end of the decl.
2020 let snippet_lo = fd.output.span().hi();
2021 if where_clause.predicates.is_empty() {
2022 let snippet_hi = span.hi();
2023 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2024 // Try to preserve the layout of the original snippet.
2025 let original_starts_with_newline = snippet
2027 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2028 let original_ends_with_newline = snippet
2029 .rfind(|c| c != ' ')
2030 .map_or(false, |i| snippet[i..].ends_with('\n'));
2031 let snippet = snippet.trim();
2032 if !snippet.is_empty() {
2033 result.push(if original_starts_with_newline {
2038 result.push_str(snippet);
2039 if original_ends_with_newline {
2040 force_new_line_for_brace = true;
2046 let should_compress_where = match context.config.where_density() {
2047 Density::Compressed => !result.contains('\n'),
2048 Density::CompressedIfEmpty => !has_body && !result.contains('\n'),
2052 let pos_before_where = match fd.output {
2053 ast::FunctionRetTy::Default(..) => args_span.hi(),
2054 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2057 let is_args_multi_lined = arg_str.contains('\n');
2059 if where_clause.predicates.len() == 1 && should_compress_where {
2060 let budget = context.budget(last_line_used_width(&result, indent.width()));
2061 if let Some(where_clause_str) = rewrite_where_clause(
2064 context.config.brace_style(),
2065 Shape::legacy(budget, indent),
2066 Density::Compressed,
2070 WhereClauseOption::compressed(),
2071 is_args_multi_lined,
2073 result.push_str(&where_clause_str);
2074 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2075 return Some((result, force_new_line_for_brace));
2079 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2080 let where_clause_str = rewrite_where_clause(
2083 context.config.brace_style(),
2084 Shape::indented(indent, context.config),
2090 is_args_multi_lined,
2092 // If there are neither where clause nor return type, we may be missing comments between
2094 if where_clause_str.is_empty() {
2095 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2096 match recover_missing_comment_in_span(
2097 mk_sp(args_span.hi(), ret_span.hi()),
2100 last_line_width(&result),
2102 Some(ref missing_comment) if !missing_comment.is_empty() => {
2103 result.push_str(missing_comment);
2104 force_new_line_for_brace = true;
2111 result.push_str(&where_clause_str);
2113 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2114 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2115 Some((result, force_new_line_for_brace))
2118 #[derive(Copy, Clone)]
2119 struct WhereClauseOption {
2120 suppress_comma: bool, // Force no trailing comma
2121 snuggle: bool, // Do not insert newline before `where`
2122 compress_where: bool, // Try single line where clause instead of vertical layout
2125 impl WhereClauseOption {
2126 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2128 suppress_comma: suppress_comma,
2130 compress_where: false,
2134 pub fn compressed() -> WhereClauseOption {
2136 suppress_comma: true,
2138 compress_where: true,
2142 pub fn snuggled(current: &str) -> WhereClauseOption {
2144 suppress_comma: false,
2145 snuggle: trimmed_last_line_width(current) == 1,
2146 compress_where: false,
2152 context: &RewriteContext,
2154 explicit_self: Option<&ast::ExplicitSelf>,
2155 one_line_budget: usize,
2156 multi_line_budget: usize,
2161 generics_str_contains_newline: bool,
2162 ) -> Option<String> {
2163 let mut arg_item_strs = args.iter()
2165 arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent))
2167 .collect::<Option<Vec<_>>>()?;
2169 // Account for sugary self.
2170 // FIXME: the comment for the self argument is dropped. This is blocked
2171 // on rust issue #27522.
2172 let min_args = explicit_self
2173 .and_then(|explicit_self| {
2174 rewrite_explicit_self(explicit_self, args, context)
2176 .map_or(1, |self_str| {
2177 arg_item_strs[0] = self_str;
2181 // Comments between args.
2182 let mut arg_items = Vec::new();
2184 arg_items.push(ListItem::from_str(""));
2187 // FIXME(#21): if there are no args, there might still be a comment, but
2188 // without spans for the comment or parens, there is no chance of
2189 // getting it right. You also don't get to put a comment on self, unless
2191 if args.len() >= min_args || variadic {
2192 let comment_span_start = if min_args == 2 {
2193 let second_arg_start = if arg_has_pattern(&args[1]) {
2194 args[1].pat.span.lo()
2196 args[1].ty.span.lo()
2198 let reduced_span = mk_sp(span.lo(), second_arg_start);
2200 context.codemap.span_after_last(reduced_span, ",")
2205 enum ArgumentKind<'a> {
2206 Regular(&'a ast::Arg),
2210 let variadic_arg = if variadic {
2211 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2212 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2213 Some(ArgumentKind::Variadic(variadic_start))
2218 let more_items = itemize_list(
2220 args[min_args - 1..]
2222 .map(ArgumentKind::Regular)
2223 .chain(variadic_arg),
2226 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2227 ArgumentKind::Variadic(start) => start,
2230 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2231 ArgumentKind::Variadic(start) => start + BytePos(3),
2234 ArgumentKind::Regular(..) => None,
2235 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2242 arg_items.extend(more_items);
2245 let fits_in_one_line = !generics_str_contains_newline
2246 && (arg_items.is_empty()
2247 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2249 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2250 item.item = Some(arg);
2253 let last_line_ends_with_comment = arg_items
2256 .and_then(|item| item.post_comment.as_ref())
2257 .map_or(false, |s| s.trim().starts_with("//"));
2259 let (indent, trailing_comma) = match context.config.indent_style() {
2260 IndentStyle::Block if fits_in_one_line => {
2261 (indent.block_indent(context.config), SeparatorTactic::Never)
2263 IndentStyle::Block => (
2264 indent.block_indent(context.config),
2265 context.config.trailing_comma(),
2267 IndentStyle::Visual if last_line_ends_with_comment => {
2268 (arg_indent, context.config.trailing_comma())
2270 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2273 let tactic = definitive_tactic(
2275 context.config.fn_args_density().to_list_tactic(),
2279 let budget = match tactic {
2280 DefinitiveListTactic::Horizontal => one_line_budget,
2281 _ => multi_line_budget,
2284 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2286 let fmt = ListFormatting {
2289 trailing_separator: if variadic {
2290 SeparatorTactic::Never
2294 separator_place: SeparatorPlace::Back,
2295 shape: Shape::legacy(budget, indent),
2296 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2297 preserve_newline: true,
2298 config: context.config,
2301 write_list(&arg_items, &fmt)
2304 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2305 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2306 ident.node != symbol::keywords::Invalid.ident()
2312 fn compute_budgets_for_args(
2313 context: &RewriteContext,
2317 newline_brace: bool,
2319 force_vertical_layout: bool,
2320 ) -> Option<((usize, usize, Indent))> {
2322 "compute_budgets_for_args {} {:?}, {}, {}",
2328 // Try keeping everything on the same line.
2329 if !result.contains('\n') && !force_vertical_layout {
2330 // 2 = `()`, 3 = `() `, space is before ret_string.
2331 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2332 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2342 let one_line_budget = context.budget(used_space);
2344 if one_line_budget > 0 {
2346 let (indent, multi_line_budget) = match context.config.indent_style() {
2347 IndentStyle::Block => {
2348 let indent = indent.block_indent(context.config);
2349 (indent, context.budget(indent.width() + 1))
2351 IndentStyle::Visual => {
2352 let indent = indent + result.len() + 1;
2353 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2354 (indent, context.budget(multi_line_overhead))
2358 return Some((one_line_budget, multi_line_budget, indent));
2362 // Didn't work. we must force vertical layout and put args on a newline.
2363 let new_indent = indent.block_indent(context.config);
2364 let used_space = match context.config.indent_style() {
2366 IndentStyle::Block => new_indent.width() + 1,
2367 // Account for `)` and possibly ` {`.
2368 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2370 Some((0, context.budget(used_space), new_indent))
2373 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause, has_body: bool) -> bool {
2374 let predicate_count = where_clause.predicates.len();
2376 if config.where_single_line() && predicate_count == 1 {
2379 match (config.brace_style(), config.where_density()) {
2380 (BraceStyle::AlwaysNextLine, _) => true,
2381 (_, Density::Compressed) if predicate_count == 1 => false,
2382 (_, Density::CompressedIfEmpty) if predicate_count == 1 && !has_body => false,
2383 (BraceStyle::SameLineWhere, _) if predicate_count > 0 => true,
2388 fn rewrite_generics(
2389 context: &RewriteContext,
2390 generics: &ast::Generics,
2393 ) -> Option<String> {
2394 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2395 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2396 rewrite_generics_inner(context, generics, g_shape, one_line_width, span).or_else(|| {
2397 rewrite_generics_inner(context, generics, g_shape, 0, span)
2401 fn rewrite_generics_inner(
2402 context: &RewriteContext,
2403 generics: &ast::Generics,
2405 one_line_width: usize,
2407 ) -> Option<String> {
2408 // FIXME: convert bounds to where clauses where they get too big or if
2409 // there is a where clause at all.
2412 enum GenericsArg<'a> {
2413 Lifetime(&'a ast::LifetimeDef),
2414 TyParam(&'a ast::TyParam),
2416 impl<'a> Rewrite for GenericsArg<'a> {
2417 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2419 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2420 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2424 impl<'a> Spanned for GenericsArg<'a> {
2425 fn span(&self) -> Span {
2427 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2428 GenericsArg::TyParam(ty) => ty.span(),
2433 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2434 return Some(String::new());
2437 let generics_args = generics
2440 .map(|lt| GenericsArg::Lifetime(lt))
2441 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2442 let items = itemize_list(
2446 |arg| arg.span().lo(),
2447 |arg| arg.span().hi(),
2448 |arg| arg.rewrite(context, shape),
2449 context.codemap.span_after(span, "<"),
2453 format_generics_item_list(context, items, shape, one_line_width)
2456 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2457 match config.indent_style() {
2458 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2459 IndentStyle::Block => {
2463 .block_indent(config.tab_spaces())
2464 .with_max_width(config)
2470 pub fn format_generics_item_list<I>(
2471 context: &RewriteContext,
2474 one_line_budget: usize,
2477 I: Iterator<Item = ListItem>,
2479 let item_vec = items.collect::<Vec<_>>();
2481 let tactic = definitive_tactic(
2483 ListTactic::HorizontalVertical,
2487 let fmt = ListFormatting {
2490 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2491 SeparatorTactic::Never
2493 context.config.trailing_comma()
2495 separator_place: SeparatorPlace::Back,
2497 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2498 preserve_newline: true,
2499 config: context.config,
2502 let list_str = write_list(&item_vec, &fmt)?;
2504 Some(wrap_generics_with_angle_brackets(
2511 pub fn wrap_generics_with_angle_brackets(
2512 context: &RewriteContext,
2514 list_offset: Indent,
2516 if context.config.indent_style() == IndentStyle::Block
2517 && (list_str.contains('\n') || list_str.ends_with(','))
2521 list_offset.to_string(context.config),
2524 .block_unindent(context.config)
2525 .to_string(context.config)
2527 } else if context.config.spaces_within_parens_and_brackets() {
2528 format!("< {} >", list_str)
2530 format!("<{}>", list_str)
2534 fn rewrite_trait_bounds(
2535 context: &RewriteContext,
2536 type_param_bounds: &ast::TyParamBounds,
2538 ) -> Option<String> {
2539 let bounds: &[_] = type_param_bounds;
2541 if bounds.is_empty() {
2542 return Some(String::new());
2544 let bound_str = bounds
2546 .map(|ty_bound| ty_bound.rewrite(context, shape))
2547 .collect::<Option<Vec<_>>>()?;
2548 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2551 fn rewrite_where_clause_rfc_style(
2552 context: &RewriteContext,
2553 where_clause: &ast::WhereClause,
2556 span_end: Option<BytePos>,
2557 span_end_before_where: BytePos,
2558 where_clause_option: WhereClauseOption,
2559 is_args_multi_line: bool,
2560 ) -> Option<String> {
2561 let block_shape = shape.block().with_max_width(context.config);
2563 let (span_before, span_after) =
2564 missing_span_before_after_where(span_end_before_where, where_clause);
2565 let (comment_before, comment_after) =
2566 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2568 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2571 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2574 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2576 let clause_shape = clause_shape.sub_width(1)?;
2577 // each clause on one line, trailing comma (except if suppress_comma)
2578 let span_start = where_clause.predicates[0].span().lo();
2579 // If we don't have the start of the next span, then use the end of the
2580 // predicates, but that means we miss comments.
2581 let len = where_clause.predicates.len();
2582 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2583 let span_end = span_end.unwrap_or(end_of_preds);
2584 let items = itemize_list(
2586 where_clause.predicates.iter(),
2588 |pred| pred.span().lo(),
2589 |pred| pred.span().hi(),
2590 |pred| pred.rewrite(context, clause_shape),
2595 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2596 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2597 SeparatorTactic::Never
2599 context.config.trailing_comma()
2602 // shape should be vertical only and only if we have `where_single_line` option enabled
2603 // and the number of items of the where clause is equal to 1
2604 let shape_tactic = if where_single_line {
2605 DefinitiveListTactic::Horizontal
2607 DefinitiveListTactic::Vertical
2610 let fmt = ListFormatting {
2611 tactic: shape_tactic,
2613 trailing_separator: comma_tactic,
2614 separator_place: SeparatorPlace::Back,
2615 shape: clause_shape,
2616 ends_with_newline: true,
2617 preserve_newline: true,
2618 config: context.config,
2620 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2622 let comment_separator = |comment: &str, shape: Shape| if comment.is_empty() {
2625 format!("\n{}", shape.indent.to_string(context.config))
2627 let newline_before_where = comment_separator(&comment_before, shape);
2628 let newline_after_where = comment_separator(&comment_after, clause_shape);
2631 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2632 && comment_after.is_empty() && !preds_str.contains('\n')
2633 && 6 + preds_str.len() <= shape.width || where_single_line
2637 format!("\n{}", clause_shape.indent.to_string(context.config))
2640 "{}{}{}where{}{}{}{}",
2643 newline_before_where,
2644 newline_after_where,
2651 fn rewrite_where_clause(
2652 context: &RewriteContext,
2653 where_clause: &ast::WhereClause,
2654 brace_style: BraceStyle,
2658 span_end: Option<BytePos>,
2659 span_end_before_where: BytePos,
2660 where_clause_option: WhereClauseOption,
2661 is_args_multi_line: bool,
2662 ) -> Option<String> {
2663 if where_clause.predicates.is_empty() {
2664 return Some(String::new());
2667 if context.config.indent_style() == IndentStyle::Block {
2668 return rewrite_where_clause_rfc_style(
2674 span_end_before_where,
2675 where_clause_option,
2680 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2682 let offset = match context.config.indent_style() {
2683 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2684 // 6 = "where ".len()
2685 IndentStyle::Visual => shape.indent + extra_indent + 6,
2687 // FIXME: if indent_style != Visual, then the budgets below might
2688 // be out by a char or two.
2690 let budget = context.config.max_width() - offset.width();
2691 let span_start = where_clause.predicates[0].span().lo();
2692 // If we don't have the start of the next span, then use the end of the
2693 // predicates, but that means we miss comments.
2694 let len = where_clause.predicates.len();
2695 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2696 let span_end = span_end.unwrap_or(end_of_preds);
2697 let items = itemize_list(
2699 where_clause.predicates.iter(),
2701 |pred| pred.span().lo(),
2702 |pred| pred.span().hi(),
2703 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2708 let item_vec = items.collect::<Vec<_>>();
2709 // FIXME: we don't need to collect here if the where_layout isn't
2710 // HorizontalVertical.
2711 let tactic = definitive_tactic(
2713 context.config.where_layout(),
2718 let mut comma_tactic = context.config.trailing_comma();
2719 // Kind of a hack because we don't usually have trailing commas in where clauses.
2720 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2721 comma_tactic = SeparatorTactic::Never;
2724 let fmt = ListFormatting {
2727 trailing_separator: comma_tactic,
2728 separator_place: SeparatorPlace::Back,
2729 shape: Shape::legacy(budget, offset),
2730 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2731 preserve_newline: true,
2732 config: context.config,
2734 let preds_str = write_list(&item_vec, &fmt)?;
2736 let end_length = if terminator == "{" {
2737 // If the brace is on the next line we don't need to count it otherwise it needs two
2740 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2741 BraceStyle::PreferSameLine => 2,
2743 } else if terminator == "=" {
2748 if density == Density::Tall || preds_str.contains('\n')
2749 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2753 (shape.indent + extra_indent).to_string(context.config),
2757 Some(format!(" where {}", preds_str))
2761 fn missing_span_before_after_where(
2762 before_item_span_end: BytePos,
2763 where_clause: &ast::WhereClause,
2765 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2767 let pos_after_where = where_clause.span.lo() + BytePos(5);
2768 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2769 (missing_span_before, missing_span_after)
2772 fn rewrite_comments_before_after_where(
2773 context: &RewriteContext,
2774 span_before_where: Span,
2775 span_after_where: Span,
2777 ) -> Option<(String, String)> {
2778 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2779 let after_comment = rewrite_missing_comment(
2781 shape.block_indent(context.config.tab_spaces()),
2784 Some((before_comment, after_comment))
2787 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2788 format!("{}{}{}", format_visibility(vis), item_name, ident)
2791 #[derive(PartialEq, Eq)]
2799 context: &RewriteContext,
2800 generics: &ast::Generics,
2801 brace_style: BraceStyle,
2802 brace_pos: BracePos,
2806 ) -> Option<String> {
2807 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2808 let mut result = rewrite_generics(context, generics, shape, span)?;
2810 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2811 let budget = context.budget(last_line_used_width(&result, offset.width()));
2812 let mut option = WhereClauseOption::snuggled(&result);
2813 if brace_pos == BracePos::None {
2814 option.suppress_comma = true;
2816 // If the generics are not parameterized then generics.span.hi() == 0,
2817 // so we use span.lo(), which is the position after `struct Foo`.
2818 let span_end_before_where = if generics.is_parameterized() {
2823 let where_clause_str = rewrite_where_clause(
2825 &generics.where_clause,
2827 Shape::legacy(budget, offset.block_only()),
2831 span_end_before_where,
2835 result.push_str(&where_clause_str);
2836 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2837 || (generics.where_clause.predicates.is_empty()
2838 && trimmed_last_line_width(&result) == 1)
2840 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2841 || brace_style != BraceStyle::AlwaysNextLine
2843 if brace_pos == BracePos::None {
2844 return Some(result);
2846 let total_used_width = last_line_used_width(&result, used_width);
2847 let remaining_budget = context.budget(total_used_width);
2848 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2849 // and hence we take the closer into account as well for one line budget.
2850 // We assume that the closer has the same length as the opener.
2851 let overhead = if brace_pos == BracePos::ForceSameLine {
2858 let forbid_same_line_brace = overhead > remaining_budget;
2859 if !forbid_same_line_brace && same_line_brace {
2863 result.push_str(&offset.block_only().to_string(context.config));
2870 impl Rewrite for ast::ForeignItem {
2871 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2872 let attrs_str = self.attrs.rewrite(context, shape)?;
2873 // Drop semicolon or it will be interpreted as comment.
2874 // FIXME: this may be a faulty span from libsyntax.
2875 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2877 let item_str = match self.node {
2878 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2883 &FnSig::new(fn_decl, generics, self.vis.clone()),
2887 ).map(|(s, _)| format!("{};", s))
2889 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2890 // FIXME(#21): we're dropping potential comments in between the
2891 // function keywords here.
2892 let vis = format_visibility(&self.vis);
2893 let mut_str = if is_mutable { "mut " } else { "" };
2894 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2896 let shape = shape.sub_width(1)?;
2897 ty.rewrite(context, shape).map(|ty_str| {
2898 // 1 = space between prefix and type.
2899 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2902 let nested_indent = shape.indent.block_indent(context.config);
2903 format!("\n{}", nested_indent.to_string(context.config))
2905 format!("{}{}{};", prefix, sep, ty_str)
2908 ast::ForeignItemKind::Ty => {
2909 let vis = format_visibility(&self.vis);
2910 Some(format!("{}type {};", vis, self.ident))
2914 let missing_span = if self.attrs.is_empty() {
2915 mk_sp(self.span.lo(), self.span.lo())
2917 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2919 combine_strs_with_missing_comments(