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();
305 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
307 let (mut result, force_newline_brace) =
308 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
311 if self.config.brace_style() == BraceStyle::AlwaysNextLine || force_newline_brace
312 || last_line_width(&result) + 2 > self.shape().width
314 newline_brace = true;
315 } else if !result.contains('\n') {
316 newline_brace = false;
319 // Prepare for the function body by possibly adding a newline and
321 // FIXME we'll miss anything between the end of the signature and the
322 // start of the body, but we need more spans from the compiler to solve
326 result.push_str(&indent.to_string(self.config));
331 self.single_line_fn(&result, block).or_else(|| Some(result))
334 pub fn rewrite_required_fn(
338 sig: &ast::MethodSig,
339 generics: &ast::Generics,
341 ) -> Option<String> {
342 // Drop semicolon or it will be interpreted as comment.
343 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
344 let context = self.get_context();
346 let (mut result, _) = rewrite_fn_base(
350 &FnSig::from_method_sig(sig, generics),
356 // Re-attach semicolon
362 fn single_line_fn(&self, fn_str: &str, block: &ast::Block) -> Option<String> {
363 if fn_str.contains('\n') {
367 let codemap = self.get_context().codemap;
369 if self.config.empty_item_single_line() && is_empty_block(block, codemap)
370 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
372 return Some(format!("{}{{}}", fn_str));
375 if self.config.fn_single_line() && is_simple_block_stmt(block, codemap) {
377 if let Some(stmt) = block.stmts.first() {
378 match stmt_expr(stmt) {
380 let suffix = if semicolon_for_expr(&self.get_context(), e) {
386 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
388 .or_else(|| Some(self.snippet(e.span)))
390 None => stmt.rewrite(&self.get_context(), self.shape()),
397 if let Some(res) = rewrite {
398 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
399 if !res.contains('\n') && width <= self.config.max_width() {
400 return Some(format!("{}{{ {} }}", fn_str, res));
408 pub fn visit_static(&mut self, static_parts: &StaticParts) {
409 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
410 self.push_rewrite(static_parts.span, rewrite);
413 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
414 let is_tuple = struct_parts.def.is_tuple();
415 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
416 .map(|s| if is_tuple { s + ";" } else { s });
417 self.push_rewrite(struct_parts.span, rewrite);
423 vis: &ast::Visibility,
424 enum_def: &ast::EnumDef,
425 generics: &ast::Generics,
428 let enum_header = format_header("enum ", ident, vis);
429 self.buffer.push_str(&enum_header);
431 let enum_snippet = self.snippet(span);
432 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
433 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
434 let generics_str = format_generics(
437 self.config.brace_style(),
438 if enum_def.variants.is_empty() {
439 BracePos::ForceSameLine
444 mk_sp(span.lo(), body_start),
445 last_line_width(&enum_header),
447 self.buffer.push_str(&generics_str);
449 self.last_pos = body_start;
451 self.block_indent = self.block_indent.block_indent(self.config);
452 let variant_list = self.format_variant_list(enum_def, body_start, span.hi() - BytePos(1));
454 Some(ref body_str) => self.buffer.push_str(body_str),
455 None => self.format_missing_no_indent(span.hi() - BytePos(1)),
457 self.block_indent = self.block_indent.block_unindent(self.config);
459 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
461 .push_str(&self.block_indent.to_string(self.config));
463 self.buffer.push_str("}");
464 self.last_pos = span.hi();
467 // Format the body of an enum definition
468 fn format_variant_list(
470 enum_def: &ast::EnumDef,
473 ) -> Option<String> {
474 if enum_def.variants.is_empty() {
477 let mut result = String::with_capacity(1024);
479 let indentation = self.block_indent.to_string(self.config);
480 result.push_str(&indentation);
482 let itemize_list_with = |one_line_width: usize| {
485 enum_def.variants.iter(),
488 |f| if !f.node.attrs.is_empty() {
489 f.node.attrs[0].span.lo()
494 |f| self.format_variant(f, one_line_width),
500 let mut items: Vec<_> =
501 itemize_list_with(self.config.width_heuristics().struct_variant_width);
502 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
503 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
504 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
505 if has_multiline_variant && has_single_line_variant {
506 items = itemize_list_with(0);
509 let shape = self.shape().sub_width(2).unwrap();
510 let fmt = ListFormatting {
511 tactic: DefinitiveListTactic::Vertical,
513 trailing_separator: self.config.trailing_comma(),
514 separator_place: SeparatorPlace::Back,
516 ends_with_newline: true,
517 preserve_newline: true,
521 let list = write_list(&items, &fmt)?;
522 result.push_str(&list);
527 // Variant of an enum.
528 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
529 if contains_skip(&field.node.attrs) {
530 let lo = field.node.attrs[0].span.lo();
531 let span = mk_sp(lo, field.span.hi());
532 return Some(self.snippet(span));
535 let context = self.get_context();
537 let shape = self.shape().sub_width(1)?;
538 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
543 .map_or(field.span.lo(), |attr| attr.span.hi());
544 let span = mk_sp(lo, field.span.lo());
546 let variant_body = match field.node.data {
547 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
549 &StructParts::from_variant(field),
551 Some(one_line_width),
553 ast::VariantData::Unit(..) => {
554 if let Some(ref expr) = field.node.disr_expr {
555 let lhs = format!("{} =", field.node.name);
556 rewrite_assign_rhs(&context, lhs, &**expr, shape)?
558 field.node.name.to_string()
563 let attrs_extendable = attrs_str.is_empty()
564 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
565 combine_strs_with_missing_comments(
577 context: &RewriteContext,
580 where_span_end: Option<BytePos>,
581 ) -> Option<String> {
582 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
583 let mut result = String::with_capacity(128);
584 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
585 let indent_str = offset.to_string(context.config);
586 let sep = format!("\n{}", &indent_str);
587 result.push_str(&ref_and_type);
589 let where_budget = if result.contains('\n') {
590 context.config.max_width()
592 context.budget(last_line_width(&result))
594 let option = WhereClauseOption::snuggled(&ref_and_type);
595 let where_clause_str = rewrite_where_clause(
597 &generics.where_clause,
598 context.config.brace_style(),
599 Shape::legacy(where_budget, offset.block_only()),
608 // If there is no where clause, we may have missing comments between the trait name and
609 // the opening brace.
610 if generics.where_clause.predicates.is_empty() {
611 if let Some(hi) = where_span_end {
612 match recover_missing_comment_in_span(
613 mk_sp(self_ty.span.hi(), hi),
614 Shape::indented(offset, context.config),
616 last_line_width(&result),
618 Some(ref missing_comment) if !missing_comment.is_empty() => {
619 result.push_str(missing_comment);
626 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
627 result.push_str(&where_clause_str);
628 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
629 result.push_str(&format!("{}{{{}}}", &sep, &sep));
631 result.push_str(" {}");
636 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
638 let width = offset.block_indent + context.config.tab_spaces() - 1;
639 let where_indent = Indent::new(0, width);
640 result.push_str(&where_indent.to_string(context.config));
642 result.push_str(&where_clause_str);
644 match context.config.brace_style() {
645 _ if last_line_contains_single_line_comment(&result) => result.push_str(&sep),
646 BraceStyle::AlwaysNextLine => result.push_str(&sep),
647 BraceStyle::PreferSameLine => result.push(' '),
648 BraceStyle::SameLineWhere => {
649 if !where_clause_str.is_empty() {
650 result.push_str(&sep);
659 let snippet = context.snippet(item.span);
660 let open_pos = snippet.find_uncommented("{")? + 1;
662 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
663 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
664 visitor.block_indent = offset.block_only().block_indent(context.config);
665 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
667 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
669 visitor.visit_impl_item(item);
672 visitor.format_missing(item.span.hi() - BytePos(1));
674 let inner_indent_str = visitor.block_indent.to_string(context.config);
675 let outer_indent_str = offset.block_only().to_string(context.config);
678 result.push_str(&inner_indent_str);
679 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
681 result.push_str(&outer_indent_str);
684 if result.ends_with('{') {
685 result.push_str(&sep);
695 fn is_impl_single_line(
696 context: &RewriteContext,
699 where_clause_str: &str,
702 let snippet = context.snippet(item.span);
703 let open_pos = snippet.find_uncommented("{")? + 1;
706 context.config.empty_item_single_line() && items.is_empty() && !result.contains('\n')
707 && result.len() + where_clause_str.len() <= context.config.max_width()
708 && !contains_comment(&snippet[open_pos..]),
712 fn format_impl_ref_and_type(
713 context: &RewriteContext,
716 ) -> Option<String> {
717 if let ast::ItemKind::Impl(
727 let mut result = String::with_capacity(128);
729 result.push_str(&format_visibility(&item.vis));
730 result.push_str(format_defaultness(defaultness));
731 result.push_str(format_unsafety(unsafety));
732 result.push_str("impl");
734 let lo = context.codemap.span_after(item.span, "impl");
735 let hi = match *trait_ref {
736 Some(ref tr) => tr.path.span.lo(),
737 None => self_ty.span.lo(),
739 let shape = generics_shape_from_config(
741 Shape::indented(offset + last_line_width(&result), context.config),
744 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
746 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
748 let polarity_str = if polarity == ast::ImplPolarity::Negative {
754 if let Some(ref trait_ref) = *trait_ref {
755 let result_len = result.len();
756 if let Some(trait_ref_str) = rewrite_trait_ref(
765 result.push_str(&trait_ref_str);
768 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
769 result.push_str(&rewrite_trait_ref(
780 result.push_str(&generics_str);
783 // Try to put the self type in a single line.
785 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
786 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
787 // If there is no where clause adapt budget for type formatting to take space and curly
788 // brace into account.
789 match context.config.brace_style() {
790 BraceStyle::AlwaysNextLine => 0,
796 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
797 // 1 = space before the type.
798 let budget = context.budget(used_space + 1);
799 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
800 if !self_ty_str.contains('\n') {
801 if trait_ref.is_some() {
802 result.push_str(" for ");
806 result.push_str(&self_ty_str);
811 // Couldn't fit the self type on a single line, put it on a new line.
813 // Add indentation of one additional tab.
814 let new_line_offset = offset.block_indent(context.config);
815 result.push_str(&new_line_offset.to_string(context.config));
816 if trait_ref.is_some() {
817 result.push_str("for ");
819 let budget = context.budget(last_line_width(&result));
820 let type_offset = match context.config.indent_style() {
821 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
822 IndentStyle::Block => new_line_offset,
824 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
831 fn rewrite_trait_ref(
832 context: &RewriteContext,
833 trait_ref: &ast::TraitRef,
839 ) -> Option<String> {
840 // 1 = space between generics and trait_ref
841 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
842 let shape = Shape::indented(offset + used_space, context.config);
843 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
844 if !(retry && trait_ref_str.contains('\n')) {
853 // We could not make enough space for trait_ref, so put it on new line.
855 let offset = offset.block_indent(context.config);
856 let shape = Shape::indented(offset, context.config);
857 let trait_ref_str = trait_ref.rewrite(context, shape)?;
861 &offset.to_string(context.config),
870 pub struct StructParts<'a> {
873 vis: &'a ast::Visibility,
874 def: &'a ast::VariantData,
875 generics: Option<&'a ast::Generics>,
879 impl<'a> StructParts<'a> {
880 fn format_header(&self) -> String {
881 format_header(self.prefix, self.ident, self.vis)
884 fn from_variant(variant: &'a ast::Variant) -> Self {
887 ident: variant.node.name,
888 vis: &ast::Visibility::Inherited,
889 def: &variant.node.data,
895 pub fn from_item(item: &'a ast::Item) -> Self {
896 let (prefix, def, generics) = match item.node {
897 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
898 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
906 generics: Some(generics),
913 context: &RewriteContext,
914 struct_parts: &StructParts,
916 one_line_width: Option<usize>,
917 ) -> Option<String> {
918 match *struct_parts.def {
919 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
920 ast::VariantData::Tuple(ref fields, _) => {
921 format_tuple_struct(context, struct_parts, fields, offset)
923 ast::VariantData::Struct(ref fields, _) => {
924 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
929 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
930 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
933 let mut result = String::with_capacity(128);
934 let header = format!(
936 format_visibility(&item.vis),
937 format_unsafety(unsafety),
941 result.push_str(&header);
943 let body_lo = context.codemap.span_after(item.span, "{");
945 let shape = Shape::indented(offset, context.config);
947 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
948 result.push_str(&generics_str);
950 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
951 if !type_param_bounds.is_empty() {
952 let ident_hi = context.codemap.span_after(item.span, &format!("{}", item.ident));
953 let bound_hi = type_param_bounds.last().unwrap().span().hi();
954 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
955 if contains_comment(&snippet) {
959 let trait_bound_str = rewrite_trait_bounds(
962 Shape::indented(offset, context.config),
964 // If the trait, generics, and trait bound cannot fit on the same line,
965 // put the trait bounds on an indented new line
966 if offset.width() + last_line_width(&result) + trait_bound_str.len()
967 > context.config.comment_width()
970 let trait_indent = offset.block_only().block_indent(context.config);
971 result.push_str(&trait_indent.to_string(context.config));
973 result.push_str(&trait_bound_str);
976 if context.config.indent_style() == IndentStyle::Block && result.is_empty() {
982 let where_budget = context.budget(last_line_width(&result));
983 let pos_before_where = if type_param_bounds.is_empty() {
984 generics.where_clause.span.lo()
986 type_param_bounds[type_param_bounds.len() - 1].span().hi()
988 let option = WhereClauseOption::snuggled(&generics_str);
989 let where_clause_str = rewrite_where_clause(
991 &generics.where_clause,
992 context.config.brace_style(),
993 Shape::legacy(where_budget, offset.block_only()),
1001 // If the where clause cannot fit on the same line,
1002 // put the where clause on a new line
1003 if !where_clause_str.contains('\n')
1004 && last_line_width(&result) + where_clause_str.len() + offset.width()
1005 > context.config.comment_width()
1008 let width = offset.block_indent + context.config.tab_spaces() - 1;
1009 let where_indent = Indent::new(0, width);
1010 result.push_str(&where_indent.to_string(context.config));
1012 result.push_str(&where_clause_str);
1014 if generics.where_clause.predicates.is_empty() {
1015 let item_snippet = context.snippet(item.span);
1016 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1018 let comment_hi = body_lo - BytePos(1);
1019 let comment_lo = item.span.lo() + BytePos(lo as u32);
1020 if comment_lo < comment_hi {
1021 match recover_missing_comment_in_span(
1022 mk_sp(comment_lo, comment_hi),
1023 Shape::indented(offset, context.config),
1025 last_line_width(&result),
1027 Some(ref missing_comment) if !missing_comment.is_empty() => {
1028 result.push_str(missing_comment);
1036 match context.config.brace_style() {
1037 _ if last_line_contains_single_line_comment(&result) => {
1039 result.push_str(&offset.to_string(context.config));
1041 BraceStyle::AlwaysNextLine => {
1043 result.push_str(&offset.to_string(context.config));
1045 BraceStyle::PreferSameLine => result.push(' '),
1046 BraceStyle::SameLineWhere => {
1047 if !where_clause_str.is_empty()
1048 && (!trait_items.is_empty() || result.contains('\n'))
1051 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).sub_width(1)?,
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).sub_width(1)?;
1317 let fields = &fields.iter().collect::<Vec<_>>()[..];
1318 let one_line_width = context.config.width_heuristics().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),
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.same_line_attributes() && is_attributes_extendable(&attrs_str));
1444 let missing_span = if field.attrs.is_empty() {
1445 mk_sp(field.span.lo(), field.span.lo())
1447 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1449 let mut spacing = String::from(if field.ident.is_some() {
1450 type_annotation_spacing.1
1454 // Try to put everything on a single line.
1455 let attr_prefix = combine_strs_with_missing_comments(
1463 let overhead = last_line_width(&attr_prefix);
1464 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1465 for _ in 0..lhs_offset {
1468 // In this extreme case we will be missing a space betweeen an attribute and a field.
1469 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1472 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1473 let mut orig_ty = field.ty.rewrite(context, ty_shape);
1474 if let Some(ref ty) = orig_ty {
1475 if !ty.contains('\n') {
1476 return Some(attr_prefix + &spacing + ty);
1480 // We must use multiline. We are going to put attributes and a field on different lines.
1482 let rhs_shape = shape.offset_left(last_line_width(&prefix) + 1)?;
1483 orig_ty = field.ty.rewrite(context, rhs_shape);
1484 let field_str = if prefix.is_empty() {
1487 prefix + &choose_rhs(context, &*field.ty, rhs_shape, orig_ty)?
1489 combine_strs_with_missing_comments(context, &attrs_str, &field_str, missing_span, shape, false)
1492 pub struct StaticParts<'a> {
1494 vis: &'a ast::Visibility,
1497 mutability: ast::Mutability,
1498 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1499 defaultness: Option<ast::Defaultness>,
1503 impl<'a> StaticParts<'a> {
1504 pub fn from_item(item: &'a ast::Item) -> Self {
1505 let (prefix, ty, mutability, expr) = match item.node {
1506 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1507 ast::ItemKind::Const(ref ty, ref expr) => {
1508 ("const", ty, ast::Mutability::Immutable, expr)
1510 _ => unreachable!(),
1517 mutability: mutability,
1518 expr_opt: Some(expr),
1524 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1525 let (ty, expr_opt) = match ti.node {
1526 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1527 _ => unreachable!(),
1531 vis: &ast::Visibility::Inherited,
1534 mutability: ast::Mutability::Immutable,
1535 expr_opt: expr_opt.as_ref(),
1541 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1542 let (ty, expr) = match ii.node {
1543 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1544 _ => unreachable!(),
1551 mutability: ast::Mutability::Immutable,
1552 expr_opt: Some(expr),
1553 defaultness: Some(ii.defaultness),
1560 context: &RewriteContext,
1561 static_parts: &StaticParts,
1563 ) -> Option<String> {
1564 let colon = colon_spaces(
1565 context.config.space_before_colon(),
1566 context.config.space_after_colon(),
1568 let prefix = format!(
1570 format_visibility(static_parts.vis),
1571 static_parts.defaultness.map_or("", format_defaultness),
1572 static_parts.prefix,
1573 format_mutability(static_parts.mutability),
1579 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1580 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1582 if let Some(expr) = static_parts.expr_opt {
1583 let lhs = format!("{}{} =", prefix, ty_str);
1585 let remaining_width = context.budget(offset.block_indent + 1);
1590 Shape::legacy(remaining_width, offset.block_only()),
1591 ).and_then(|res| recover_comment_removed(res, static_parts.span, context))
1592 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1594 Some(format!("{}{};", prefix, ty_str))
1598 pub fn rewrite_associated_type(
1600 ty_opt: Option<&ptr::P<ast::Ty>>,
1601 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1602 context: &RewriteContext,
1604 ) -> Option<String> {
1605 let prefix = format!("type {}", ident);
1607 let type_bounds_str = if let Some(bounds) = ty_param_bounds_opt {
1609 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1610 let bound_str = bounds
1612 .map(|ty_bound| ty_bound.rewrite(context, shape))
1613 .collect::<Option<Vec<_>>>()?;
1614 if !bounds.is_empty() {
1615 format!(": {}", join_bounds(context, shape, &bound_str))
1623 if let Some(ty) = ty_opt {
1625 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1626 let lhs = format!("{}{} =", prefix, type_bounds_str);
1627 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1629 Some(format!("{}{};", prefix, type_bounds_str))
1633 pub fn rewrite_associated_impl_type(
1635 defaultness: ast::Defaultness,
1636 ty_opt: Option<&ptr::P<ast::Ty>>,
1637 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1638 context: &RewriteContext,
1640 ) -> Option<String> {
1641 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1644 ast::Defaultness::Default => Some(format!("default {}", result)),
1649 impl Rewrite for ast::FunctionRetTy {
1650 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1652 ast::FunctionRetTy::Default(_) => Some(String::new()),
1653 ast::FunctionRetTy::Ty(ref ty) => {
1654 let inner_width = shape.width.checked_sub(3)?;
1655 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1656 .map(|r| format!("-> {}", r))
1662 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1664 ast::TyKind::Infer => {
1665 let original = context.snippet(ty.span);
1672 impl Rewrite for ast::Arg {
1673 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1674 if is_named_arg(self) {
1675 let mut result = self.pat
1676 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1678 if !is_empty_infer(context, &*self.ty) {
1679 if context.config.space_before_colon() {
1680 result.push_str(" ");
1682 result.push_str(":");
1683 if context.config.space_after_colon() {
1684 result.push_str(" ");
1686 let overhead = last_line_width(&result);
1687 let max_width = shape.width.checked_sub(overhead)?;
1688 let ty_str = self.ty
1689 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1690 result.push_str(&ty_str);
1695 self.ty.rewrite(context, shape)
1700 fn rewrite_explicit_self(
1701 explicit_self: &ast::ExplicitSelf,
1703 context: &RewriteContext,
1704 ) -> Option<String> {
1705 match explicit_self.node {
1706 ast::SelfKind::Region(lt, m) => {
1707 let mut_str = format_mutability(m);
1710 let lifetime_str = l.rewrite(
1712 Shape::legacy(context.config.max_width(), Indent::empty()),
1714 Some(format!("&{} {}self", lifetime_str, mut_str))
1716 None => Some(format!("&{}self", mut_str)),
1719 ast::SelfKind::Explicit(ref ty, _) => {
1720 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1722 let mutability = explicit_self_mutability(&args[0]);
1723 let type_str = ty.rewrite(
1725 Shape::legacy(context.config.max_width(), Indent::empty()),
1730 format_mutability(mutability),
1734 ast::SelfKind::Value(_) => {
1735 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1737 let mutability = explicit_self_mutability(&args[0]);
1739 Some(format!("{}self", format_mutability(mutability)))
1744 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1745 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1746 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1747 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1754 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1755 if is_named_arg(arg) {
1762 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1764 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1765 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1766 _ => arg.ty.span.hi(),
1770 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1771 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1772 ident.node != symbol::keywords::Invalid.ident()
1778 // Return type is (result, force_new_line_for_brace)
1780 context: &RewriteContext,
1785 newline_brace: bool,
1787 ) -> Option<(String, bool)> {
1788 let mut force_new_line_for_brace = false;
1790 let where_clause = &fn_sig.generics.where_clause;
1792 let mut result = String::with_capacity(1024);
1793 result.push_str(&fn_sig.to_str(context));
1796 result.push_str("fn ");
1797 result.push_str(&ident.to_string());
1800 let overhead = if has_body && !newline_brace {
1807 let used_width = last_line_used_width(&result, indent.width());
1808 let one_line_budget = context.budget(used_width + overhead);
1810 width: one_line_budget,
1814 let fd = fn_sig.decl;
1815 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1816 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1817 result.push_str(&generics_str);
1819 let snuggle_angle_bracket = generics_str
1822 .map_or(false, |l| l.trim_left().len() == 1);
1824 // Note that the width and indent don't really matter, we'll re-layout the
1825 // return type later anyway.
1826 let ret_str = fd.output
1827 .rewrite(context, Shape::indented(indent, context.config))?;
1829 let multi_line_ret_str = ret_str.contains('\n');
1830 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1833 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1844 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1850 // Check if vertical layout was forced.
1851 if one_line_budget == 0 {
1852 if snuggle_angle_bracket {
1855 result.push_str("(");
1856 if context.config.indent_style() == IndentStyle::Visual {
1858 result.push_str(&arg_indent.to_string(context.config));
1864 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1865 && result.ends_with('(')
1870 // Skip `pub(crate)`.
1871 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1872 // A conservative estimation, to goal is to be over all parens in generics
1873 let args_start = fn_sig
1877 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1878 let args_end = if fd.inputs.is_empty() {
1881 .span_after(mk_sp(args_start, span.hi()), ")")
1883 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1884 context.codemap.span_after(last_span, ")")
1886 let args_span = mk_sp(
1889 .span_after(mk_sp(args_start, span.hi()), "("),
1892 let arg_str = rewrite_args(
1895 fd.get_self().as_ref(),
1902 generics_str.contains('\n'),
1905 let put_args_in_block = match context.config.indent_style() {
1906 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1908 } && !fd.inputs.is_empty();
1910 let mut args_last_line_contains_comment = false;
1911 if put_args_in_block {
1912 arg_indent = indent.block_indent(context.config);
1914 result.push_str(&arg_indent.to_string(context.config));
1915 result.push_str(&arg_str);
1917 result.push_str(&indent.to_string(context.config));
1920 result.push_str(&arg_str);
1921 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1922 // Put the closing brace on the next line if it overflows the max width.
1924 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1927 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1930 // If the last line of args contains comment, we cannot put the closing paren
1931 // on the same line.
1935 .map_or(false, |last_line| last_line.contains("//"))
1937 args_last_line_contains_comment = true;
1939 result.push_str(&arg_indent.to_string(context.config));
1945 if let ast::FunctionRetTy::Ty(..) = fd.output {
1946 let ret_should_indent = match context.config.indent_style() {
1947 // If our args are block layout then we surely must have space.
1948 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1949 _ if args_last_line_contains_comment => false,
1950 _ if result.contains('\n') || multi_line_ret_str => true,
1952 // If the return type would push over the max width, then put the return type on
1953 // a new line. With the +1 for the signature length an additional space between
1954 // the closing parenthesis of the argument and the arrow '->' is considered.
1955 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1957 // If there is no where clause, take into account the space after the return type
1959 if where_clause.predicates.is_empty() {
1963 sig_length > context.config.max_width()
1966 let ret_indent = if ret_should_indent {
1967 let indent = if arg_str.is_empty() {
1968 // Aligning with non-existent args looks silly.
1969 force_new_line_for_brace = true;
1972 // FIXME: we might want to check that using the arg indent
1973 // doesn't blow our budget, and if it does, then fallback to
1974 // the where clause indent.
1979 result.push_str(&indent.to_string(context.config));
1983 Indent::new(indent.block_indent, last_line_width(&result))
1986 if multi_line_ret_str || ret_should_indent {
1987 // Now that we know the proper indent and width, we need to
1988 // re-layout the return type.
1989 let ret_str = fd.output
1990 .rewrite(context, Shape::indented(ret_indent, context.config))?;
1991 result.push_str(&ret_str);
1993 result.push_str(&ret_str);
1996 // Comment between return type and the end of the decl.
1997 let snippet_lo = fd.output.span().hi();
1998 if where_clause.predicates.is_empty() {
1999 let snippet_hi = span.hi();
2000 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2001 // Try to preserve the layout of the original snippet.
2002 let original_starts_with_newline = snippet
2004 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2005 let original_ends_with_newline = snippet
2006 .rfind(|c| c != ' ')
2007 .map_or(false, |i| snippet[i..].ends_with('\n'));
2008 let snippet = snippet.trim();
2009 if !snippet.is_empty() {
2010 result.push(if original_starts_with_newline {
2015 result.push_str(snippet);
2016 if original_ends_with_newline {
2017 force_new_line_for_brace = true;
2023 let pos_before_where = match fd.output {
2024 ast::FunctionRetTy::Default(..) => args_span.hi(),
2025 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2028 let is_args_multi_lined = arg_str.contains('\n');
2030 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2031 let where_clause_str = rewrite_where_clause(
2034 context.config.brace_style(),
2035 Shape::indented(indent, context.config),
2041 is_args_multi_lined,
2043 // If there are neither where clause nor return type, we may be missing comments between
2045 if where_clause_str.is_empty() {
2046 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2047 match recover_missing_comment_in_span(
2048 mk_sp(args_span.hi(), ret_span.hi()),
2051 last_line_width(&result),
2053 Some(ref missing_comment) if !missing_comment.is_empty() => {
2054 result.push_str(missing_comment);
2055 force_new_line_for_brace = true;
2062 result.push_str(&where_clause_str);
2064 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2065 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2066 Some((result, force_new_line_for_brace))
2069 #[derive(Copy, Clone)]
2070 struct WhereClauseOption {
2071 suppress_comma: bool, // Force no trailing comma
2072 snuggle: bool, // Do not insert newline before `where`
2073 compress_where: bool, // Try single line where clause instead of vertical layout
2076 impl WhereClauseOption {
2077 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2079 suppress_comma: suppress_comma,
2081 compress_where: false,
2085 pub fn snuggled(current: &str) -> WhereClauseOption {
2087 suppress_comma: false,
2088 snuggle: trimmed_last_line_width(current) == 1,
2089 compress_where: false,
2095 context: &RewriteContext,
2097 explicit_self: Option<&ast::ExplicitSelf>,
2098 one_line_budget: usize,
2099 multi_line_budget: usize,
2104 generics_str_contains_newline: bool,
2105 ) -> Option<String> {
2106 let mut arg_item_strs = args.iter()
2107 .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
2108 .collect::<Option<Vec<_>>>()?;
2110 // Account for sugary self.
2111 // FIXME: the comment for the self argument is dropped. This is blocked
2112 // on rust issue #27522.
2113 let min_args = explicit_self
2114 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2115 .map_or(1, |self_str| {
2116 arg_item_strs[0] = self_str;
2120 // Comments between args.
2121 let mut arg_items = Vec::new();
2123 arg_items.push(ListItem::from_str(""));
2126 // FIXME(#21): if there are no args, there might still be a comment, but
2127 // without spans for the comment or parens, there is no chance of
2128 // getting it right. You also don't get to put a comment on self, unless
2130 if args.len() >= min_args || variadic {
2131 let comment_span_start = if min_args == 2 {
2132 let second_arg_start = if arg_has_pattern(&args[1]) {
2133 args[1].pat.span.lo()
2135 args[1].ty.span.lo()
2137 let reduced_span = mk_sp(span.lo(), second_arg_start);
2139 context.codemap.span_after_last(reduced_span, ",")
2144 enum ArgumentKind<'a> {
2145 Regular(&'a ast::Arg),
2149 let variadic_arg = if variadic {
2150 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2151 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2152 Some(ArgumentKind::Variadic(variadic_start))
2157 let more_items = itemize_list(
2159 args[min_args - 1..]
2161 .map(ArgumentKind::Regular)
2162 .chain(variadic_arg),
2166 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2167 ArgumentKind::Variadic(start) => start,
2170 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2171 ArgumentKind::Variadic(start) => start + BytePos(3),
2174 ArgumentKind::Regular(..) => None,
2175 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2182 arg_items.extend(more_items);
2185 let fits_in_one_line = !generics_str_contains_newline
2186 && (arg_items.is_empty()
2187 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2189 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2190 item.item = Some(arg);
2193 let last_line_ends_with_comment = arg_items
2196 .and_then(|item| item.post_comment.as_ref())
2197 .map_or(false, |s| s.trim().starts_with("//"));
2199 let (indent, trailing_comma) = match context.config.indent_style() {
2200 IndentStyle::Block if fits_in_one_line => {
2201 (indent.block_indent(context.config), SeparatorTactic::Never)
2203 IndentStyle::Block => (
2204 indent.block_indent(context.config),
2205 context.config.trailing_comma(),
2207 IndentStyle::Visual if last_line_ends_with_comment => {
2208 (arg_indent, context.config.trailing_comma())
2210 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2213 let tactic = definitive_tactic(
2215 context.config.fn_args_density().to_list_tactic(),
2219 let budget = match tactic {
2220 DefinitiveListTactic::Horizontal => one_line_budget,
2221 _ => multi_line_budget,
2224 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2226 let fmt = ListFormatting {
2229 trailing_separator: if variadic {
2230 SeparatorTactic::Never
2234 separator_place: SeparatorPlace::Back,
2235 shape: Shape::legacy(budget, indent),
2236 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2237 preserve_newline: true,
2238 config: context.config,
2241 write_list(&arg_items, &fmt)
2244 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2245 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2246 ident.node != symbol::keywords::Invalid.ident()
2252 fn compute_budgets_for_args(
2253 context: &RewriteContext,
2257 newline_brace: bool,
2259 force_vertical_layout: bool,
2260 ) -> Option<((usize, usize, Indent))> {
2262 "compute_budgets_for_args {} {:?}, {}, {}",
2268 // Try keeping everything on the same line.
2269 if !result.contains('\n') && !force_vertical_layout {
2270 // 2 = `()`, 3 = `() `, space is before ret_string.
2271 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2272 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2282 let one_line_budget = context.budget(used_space);
2284 if one_line_budget > 0 {
2286 let (indent, multi_line_budget) = match context.config.indent_style() {
2287 IndentStyle::Block => {
2288 let indent = indent.block_indent(context.config);
2289 (indent, context.budget(indent.width() + 1))
2291 IndentStyle::Visual => {
2292 let indent = indent + result.len() + 1;
2293 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2294 (indent, context.budget(multi_line_overhead))
2298 return Some((one_line_budget, multi_line_budget, indent));
2302 // Didn't work. we must force vertical layout and put args on a newline.
2303 let new_indent = indent.block_indent(context.config);
2304 let used_space = match context.config.indent_style() {
2306 IndentStyle::Block => new_indent.width() + 1,
2307 // Account for `)` and possibly ` {`.
2308 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2310 Some((0, context.budget(used_space), new_indent))
2313 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2314 let predicate_count = where_clause.predicates.len();
2316 if config.where_single_line() && predicate_count == 1 {
2319 let brace_style = config.brace_style();
2321 brace_style == BraceStyle::AlwaysNextLine
2322 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2325 fn rewrite_generics(
2326 context: &RewriteContext,
2327 generics: &ast::Generics,
2330 ) -> Option<String> {
2331 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2332 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2333 rewrite_generics_inner(context, generics, g_shape, one_line_width, span)
2334 .or_else(|| rewrite_generics_inner(context, generics, g_shape, 0, span))
2337 fn rewrite_generics_inner(
2338 context: &RewriteContext,
2339 generics: &ast::Generics,
2341 one_line_width: usize,
2343 ) -> Option<String> {
2344 // FIXME: convert bounds to where clauses where they get too big or if
2345 // there is a where clause at all.
2348 enum GenericsArg<'a> {
2349 Lifetime(&'a ast::LifetimeDef),
2350 TyParam(&'a ast::TyParam),
2352 impl<'a> Rewrite for GenericsArg<'a> {
2353 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2355 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2356 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2360 impl<'a> Spanned for GenericsArg<'a> {
2361 fn span(&self) -> Span {
2363 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2364 GenericsArg::TyParam(ty) => ty.span(),
2369 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2370 return Some(String::new());
2373 let generics_args = generics
2376 .map(|lt| GenericsArg::Lifetime(lt))
2377 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2378 let items = itemize_list(
2383 |arg| arg.span().lo(),
2384 |arg| arg.span().hi(),
2385 |arg| arg.rewrite(context, shape),
2386 context.codemap.span_after(span, "<"),
2390 format_generics_item_list(context, items, shape, one_line_width)
2393 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2394 match config.indent_style() {
2395 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2396 IndentStyle::Block => {
2400 .block_indent(config.tab_spaces())
2401 .with_max_width(config)
2407 pub fn format_generics_item_list<I>(
2408 context: &RewriteContext,
2411 one_line_budget: usize,
2414 I: Iterator<Item = ListItem>,
2416 let item_vec = items.collect::<Vec<_>>();
2418 let tactic = definitive_tactic(
2420 ListTactic::HorizontalVertical,
2424 let fmt = ListFormatting {
2427 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2428 SeparatorTactic::Never
2430 context.config.trailing_comma()
2432 separator_place: SeparatorPlace::Back,
2434 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2435 preserve_newline: true,
2436 config: context.config,
2439 let list_str = write_list(&item_vec, &fmt)?;
2441 Some(wrap_generics_with_angle_brackets(
2448 pub fn wrap_generics_with_angle_brackets(
2449 context: &RewriteContext,
2451 list_offset: Indent,
2453 if context.config.indent_style() == IndentStyle::Block
2454 && (list_str.contains('\n') || list_str.ends_with(','))
2458 list_offset.to_string(context.config),
2461 .block_unindent(context.config)
2462 .to_string(context.config)
2464 } else if context.config.spaces_within_parens_and_brackets() {
2465 format!("< {} >", list_str)
2467 format!("<{}>", list_str)
2471 fn rewrite_trait_bounds(
2472 context: &RewriteContext,
2473 bounds: &[ast::TyParamBound],
2475 ) -> Option<String> {
2476 if bounds.is_empty() {
2477 return Some(String::new());
2479 let bound_str = bounds
2481 .map(|ty_bound| ty_bound.rewrite(context, shape))
2482 .collect::<Option<Vec<_>>>()?;
2483 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2486 fn rewrite_where_clause_rfc_style(
2487 context: &RewriteContext,
2488 where_clause: &ast::WhereClause,
2491 span_end: Option<BytePos>,
2492 span_end_before_where: BytePos,
2493 where_clause_option: WhereClauseOption,
2494 is_args_multi_line: bool,
2495 ) -> Option<String> {
2496 let block_shape = shape.block().with_max_width(context.config);
2498 let (span_before, span_after) =
2499 missing_span_before_after_where(span_end_before_where, where_clause);
2500 let (comment_before, comment_after) =
2501 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2503 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2506 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2509 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2511 let clause_shape = clause_shape.sub_width(1)?;
2512 // each clause on one line, trailing comma (except if suppress_comma)
2513 let span_start = where_clause.predicates[0].span().lo();
2514 // If we don't have the start of the next span, then use the end of the
2515 // predicates, but that means we miss comments.
2516 let len = where_clause.predicates.len();
2517 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2518 let span_end = span_end.unwrap_or(end_of_preds);
2519 let items = itemize_list(
2521 where_clause.predicates.iter(),
2524 |pred| pred.span().lo(),
2525 |pred| pred.span().hi(),
2526 |pred| pred.rewrite(context, clause_shape),
2531 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2532 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2533 SeparatorTactic::Never
2535 context.config.trailing_comma()
2538 // shape should be vertical only and only if we have `where_single_line` option enabled
2539 // and the number of items of the where clause is equal to 1
2540 let shape_tactic = if where_single_line {
2541 DefinitiveListTactic::Horizontal
2543 DefinitiveListTactic::Vertical
2546 let fmt = ListFormatting {
2547 tactic: shape_tactic,
2549 trailing_separator: comma_tactic,
2550 separator_place: SeparatorPlace::Back,
2551 shape: clause_shape,
2552 ends_with_newline: true,
2553 preserve_newline: true,
2554 config: context.config,
2556 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2558 let comment_separator = |comment: &str, shape: Shape| if comment.is_empty() {
2561 format!("\n{}", shape.indent.to_string(context.config))
2563 let newline_before_where = comment_separator(&comment_before, shape);
2564 let newline_after_where = comment_separator(&comment_after, clause_shape);
2567 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2568 && comment_after.is_empty() && !preds_str.contains('\n')
2569 && 6 + preds_str.len() <= shape.width || where_single_line
2573 format!("\n{}", clause_shape.indent.to_string(context.config))
2576 "{}{}{}where{}{}{}{}",
2579 newline_before_where,
2580 newline_after_where,
2587 fn rewrite_where_clause(
2588 context: &RewriteContext,
2589 where_clause: &ast::WhereClause,
2590 brace_style: BraceStyle,
2594 span_end: Option<BytePos>,
2595 span_end_before_where: BytePos,
2596 where_clause_option: WhereClauseOption,
2597 is_args_multi_line: bool,
2598 ) -> Option<String> {
2599 if where_clause.predicates.is_empty() {
2600 return Some(String::new());
2603 if context.config.indent_style() == IndentStyle::Block {
2604 return rewrite_where_clause_rfc_style(
2610 span_end_before_where,
2611 where_clause_option,
2616 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2618 let offset = match context.config.indent_style() {
2619 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2620 // 6 = "where ".len()
2621 IndentStyle::Visual => shape.indent + extra_indent + 6,
2623 // FIXME: if indent_style != Visual, then the budgets below might
2624 // be out by a char or two.
2626 let budget = context.config.max_width() - offset.width();
2627 let span_start = where_clause.predicates[0].span().lo();
2628 // If we don't have the start of the next span, then use the end of the
2629 // predicates, but that means we miss comments.
2630 let len = where_clause.predicates.len();
2631 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2632 let span_end = span_end.unwrap_or(end_of_preds);
2633 let items = itemize_list(
2635 where_clause.predicates.iter(),
2638 |pred| pred.span().lo(),
2639 |pred| pred.span().hi(),
2640 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2645 let item_vec = items.collect::<Vec<_>>();
2646 // FIXME: we don't need to collect here
2647 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2649 let mut comma_tactic = context.config.trailing_comma();
2650 // Kind of a hack because we don't usually have trailing commas in where clauses.
2651 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2652 comma_tactic = SeparatorTactic::Never;
2655 let fmt = ListFormatting {
2658 trailing_separator: comma_tactic,
2659 separator_place: SeparatorPlace::Back,
2660 shape: Shape::legacy(budget, offset),
2661 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2662 preserve_newline: true,
2663 config: context.config,
2665 let preds_str = write_list(&item_vec, &fmt)?;
2667 let end_length = if terminator == "{" {
2668 // If the brace is on the next line we don't need to count it otherwise it needs two
2671 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2672 BraceStyle::PreferSameLine => 2,
2674 } else if terminator == "=" {
2679 if density == Density::Tall || preds_str.contains('\n')
2680 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2684 (shape.indent + extra_indent).to_string(context.config),
2688 Some(format!(" where {}", preds_str))
2692 fn missing_span_before_after_where(
2693 before_item_span_end: BytePos,
2694 where_clause: &ast::WhereClause,
2696 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2698 let pos_after_where = where_clause.span.lo() + BytePos(5);
2699 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2700 (missing_span_before, missing_span_after)
2703 fn rewrite_comments_before_after_where(
2704 context: &RewriteContext,
2705 span_before_where: Span,
2706 span_after_where: Span,
2708 ) -> Option<(String, String)> {
2709 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2710 let after_comment = rewrite_missing_comment(
2712 shape.block_indent(context.config.tab_spaces()),
2715 Some((before_comment, after_comment))
2718 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2719 format!("{}{}{}", format_visibility(vis), item_name, ident)
2722 #[derive(PartialEq, Eq)]
2730 context: &RewriteContext,
2731 generics: &ast::Generics,
2732 brace_style: BraceStyle,
2733 brace_pos: BracePos,
2737 ) -> Option<String> {
2738 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2739 let mut result = rewrite_generics(context, generics, shape, span)?;
2741 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2742 let budget = context.budget(last_line_used_width(&result, offset.width()));
2743 let mut option = WhereClauseOption::snuggled(&result);
2744 if brace_pos == BracePos::None {
2745 option.suppress_comma = true;
2747 // If the generics are not parameterized then generics.span.hi() == 0,
2748 // so we use span.lo(), which is the position after `struct Foo`.
2749 let span_end_before_where = if generics.is_parameterized() {
2754 let where_clause_str = rewrite_where_clause(
2756 &generics.where_clause,
2758 Shape::legacy(budget, offset.block_only()),
2762 span_end_before_where,
2766 result.push_str(&where_clause_str);
2767 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2768 || (generics.where_clause.predicates.is_empty()
2769 && trimmed_last_line_width(&result) == 1)
2771 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2772 || brace_style != BraceStyle::AlwaysNextLine
2774 if brace_pos == BracePos::None {
2775 return Some(result);
2777 let total_used_width = last_line_used_width(&result, used_width);
2778 let remaining_budget = context.budget(total_used_width);
2779 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2780 // and hence we take the closer into account as well for one line budget.
2781 // We assume that the closer has the same length as the opener.
2782 let overhead = if brace_pos == BracePos::ForceSameLine {
2789 let forbid_same_line_brace = overhead > remaining_budget;
2790 if !forbid_same_line_brace && same_line_brace {
2794 result.push_str(&offset.block_only().to_string(context.config));
2801 impl Rewrite for ast::ForeignItem {
2802 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2803 let attrs_str = self.attrs.rewrite(context, shape)?;
2804 // Drop semicolon or it will be interpreted as comment.
2805 // FIXME: this may be a faulty span from libsyntax.
2806 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2808 let item_str = match self.node {
2809 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2814 &FnSig::new(fn_decl, generics, self.vis.clone()),
2818 ).map(|(s, _)| format!("{};", s))
2820 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2821 // FIXME(#21): we're dropping potential comments in between the
2822 // function keywords here.
2823 let vis = format_visibility(&self.vis);
2824 let mut_str = if is_mutable { "mut " } else { "" };
2825 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2827 let shape = shape.sub_width(1)?;
2828 ty.rewrite(context, shape).map(|ty_str| {
2829 // 1 = space between prefix and type.
2830 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2833 let nested_indent = shape.indent.block_indent(context.config);
2834 format!("\n{}", nested_indent.to_string(context.config))
2836 format!("{}{}{};", prefix, sep, ty_str)
2839 ast::ForeignItemKind::Ty => {
2840 let vis = format_visibility(&self.vis);
2841 Some(format!("{}type {};", vis, self.ident))
2845 let missing_span = if self.attrs.is_empty() {
2846 mk_sp(self.span.lo(), self.span.lo())
2848 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2850 combine_strs_with_missing_comments(