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')) {
847 generics_str, polarity_str, &trait_ref_str
851 // We could not make enough space for trait_ref, so put it on new line.
853 let offset = offset.block_indent(context.config);
854 let shape = Shape::indented(offset, context.config);
855 let trait_ref_str = trait_ref.rewrite(context, shape)?;
859 &offset.to_string(context.config),
868 pub struct StructParts<'a> {
871 vis: &'a ast::Visibility,
872 def: &'a ast::VariantData,
873 generics: Option<&'a ast::Generics>,
877 impl<'a> StructParts<'a> {
878 fn format_header(&self) -> String {
879 format_header(self.prefix, self.ident, self.vis)
882 fn from_variant(variant: &'a ast::Variant) -> Self {
885 ident: variant.node.name,
886 vis: &ast::Visibility::Inherited,
887 def: &variant.node.data,
893 pub fn from_item(item: &'a ast::Item) -> Self {
894 let (prefix, def, generics) = match item.node {
895 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
896 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
904 generics: Some(generics),
911 context: &RewriteContext,
912 struct_parts: &StructParts,
914 one_line_width: Option<usize>,
915 ) -> Option<String> {
916 match *struct_parts.def {
917 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
918 ast::VariantData::Tuple(ref fields, _) => {
919 format_tuple_struct(context, struct_parts, fields, offset)
921 ast::VariantData::Struct(ref fields, _) => {
922 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
927 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
928 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
931 let mut result = String::with_capacity(128);
932 let header = format!(
934 format_visibility(&item.vis),
935 format_unsafety(unsafety),
939 result.push_str(&header);
941 let body_lo = context.codemap.span_after(item.span, "{");
943 let shape = Shape::indented(offset, context.config);
945 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
946 result.push_str(&generics_str);
948 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
949 if !type_param_bounds.is_empty() {
950 let ident_hi = context.codemap.span_after(item.span, &format!("{}", item.ident));
951 let bound_hi = type_param_bounds.last().unwrap().span().hi();
952 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
953 if contains_comment(&snippet) {
957 let trait_bound_str = rewrite_trait_bounds(
960 Shape::indented(offset, context.config),
962 // If the trait, generics, and trait bound cannot fit on the same line,
963 // put the trait bounds on an indented new line
964 if offset.width() + last_line_width(&result) + trait_bound_str.len()
965 > context.config.comment_width()
968 let trait_indent = offset.block_only().block_indent(context.config);
969 result.push_str(&trait_indent.to_string(context.config));
971 result.push_str(&trait_bound_str);
974 if context.config.indent_style() == IndentStyle::Block && result.is_empty() {
980 let where_budget = context.budget(last_line_width(&result));
981 let pos_before_where = if type_param_bounds.is_empty() {
982 generics.where_clause.span.lo()
984 type_param_bounds[type_param_bounds.len() - 1].span().hi()
986 let option = WhereClauseOption::snuggled(&generics_str);
987 let where_clause_str = rewrite_where_clause(
989 &generics.where_clause,
990 context.config.brace_style(),
991 Shape::legacy(where_budget, offset.block_only()),
999 // If the where clause cannot fit on the same line,
1000 // put the where clause on a new line
1001 if !where_clause_str.contains('\n')
1002 && last_line_width(&result) + where_clause_str.len() + offset.width()
1003 > context.config.comment_width()
1006 let width = offset.block_indent + context.config.tab_spaces() - 1;
1007 let where_indent = Indent::new(0, width);
1008 result.push_str(&where_indent.to_string(context.config));
1010 result.push_str(&where_clause_str);
1012 if generics.where_clause.predicates.is_empty() {
1013 let item_snippet = context.snippet(item.span);
1014 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1016 let comment_hi = body_lo - BytePos(1);
1017 let comment_lo = item.span.lo() + BytePos(lo as u32);
1018 if comment_lo < comment_hi {
1019 match recover_missing_comment_in_span(
1020 mk_sp(comment_lo, comment_hi),
1021 Shape::indented(offset, context.config),
1023 last_line_width(&result),
1025 Some(ref missing_comment) if !missing_comment.is_empty() => {
1026 result.push_str(missing_comment);
1034 match context.config.brace_style() {
1035 _ if last_line_contains_single_line_comment(&result) => {
1037 result.push_str(&offset.to_string(context.config));
1039 BraceStyle::AlwaysNextLine => {
1041 result.push_str(&offset.to_string(context.config));
1043 BraceStyle::PreferSameLine => result.push(' '),
1044 BraceStyle::SameLineWhere => {
1045 if !where_clause_str.is_empty()
1046 && (!trait_items.is_empty() || result.contains('\n'))
1049 result.push_str(&offset.to_string(context.config));
1057 let snippet = context.snippet(item.span);
1058 let open_pos = snippet.find_uncommented("{")? + 1;
1060 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1061 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
1062 visitor.block_indent = offset.block_only().block_indent(context.config);
1063 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1065 for item in trait_items {
1066 visitor.visit_trait_item(item);
1069 visitor.format_missing(item.span.hi() - BytePos(1));
1071 let inner_indent_str = visitor.block_indent.to_string(context.config);
1072 let outer_indent_str = offset.block_only().to_string(context.config);
1075 result.push_str(&inner_indent_str);
1076 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1078 result.push_str(&outer_indent_str);
1079 } else if result.contains('\n') {
1090 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1091 let header_str = format_header(p.prefix, p.ident, p.vis);
1092 let generics_str = if let Some(generics) = p.generics {
1093 let hi = if generics.where_clause.predicates.is_empty() {
1096 generics.where_clause.span.hi()
1101 context.config.brace_style(),
1104 mk_sp(generics.span.lo(), hi),
1105 last_line_width(&header_str),
1110 Some(format!("{}{};", header_str, generics_str))
1113 pub fn format_struct_struct(
1114 context: &RewriteContext,
1115 struct_parts: &StructParts,
1116 fields: &[ast::StructField],
1118 one_line_width: Option<usize>,
1119 ) -> Option<String> {
1120 let mut result = String::with_capacity(1024);
1121 let span = struct_parts.span;
1123 let header_str = struct_parts.format_header();
1124 result.push_str(&header_str);
1126 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1127 let body_lo = context.codemap.span_after(span, "{");
1129 let generics_str = match struct_parts.generics {
1130 Some(g) => format_generics(
1133 context.config.brace_style(),
1134 if fields.is_empty() {
1135 BracePos::ForceSameLine
1140 mk_sp(header_hi, body_lo),
1141 last_line_width(&result),
1144 // 3 = ` {}`, 2 = ` {`.
1145 let overhead = if fields.is_empty() { 3 } else { 2 };
1146 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1147 || context.config.max_width() < overhead + result.len()
1149 format!("\n{}{{", offset.block_only().to_string(context.config))
1156 let overhead = if fields.is_empty() { 1 } else { 0 };
1157 let total_width = result.len() + generics_str.len() + overhead;
1158 if !generics_str.is_empty() && !generics_str.contains('\n')
1159 && total_width > context.config.max_width()
1162 result.push_str(&offset.to_string(context.config));
1163 result.push_str(generics_str.trim_left());
1165 result.push_str(&generics_str);
1168 if fields.is_empty() {
1169 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1170 if snippet.trim().is_empty() {
1172 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1174 result.push_str(snippet.trim_right());
1176 result.push_str(&offset.to_string(context.config));
1178 result.push_str(&snippet);
1181 return Some(result);
1185 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1186 let one_line_budget =
1187 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1189 let items_str = rewrite_with_alignment(
1192 Shape::indented(offset, context.config).sub_width(1)?,
1193 mk_sp(body_lo, span.hi()),
1197 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget {
1198 Some(format!("{} {} }}", result, items_str))
1204 .block_indent(context.config)
1205 .to_string(context.config),
1207 offset.to_string(context.config)
1212 /// Returns a bytepos that is after that of `(` in `pub(..)`. If the given visibility does not
1213 /// contain `pub(..)`, then return the `lo` of the `defualt_span`. Yeah, but for what? Well, we need
1214 /// to bypass the `(` in the visibility when creating a span of tuple's body or fn's args.
1215 fn get_bytepos_after_visibility(
1216 context: &RewriteContext,
1217 vis: &ast::Visibility,
1222 ast::Visibility::Crate(s, CrateSugar::PubCrate) => context
1224 .span_after(mk_sp(s.hi(), default_span.hi()), terminator),
1225 ast::Visibility::Crate(s, CrateSugar::JustCrate) => s.hi(),
1226 ast::Visibility::Restricted { ref path, .. } => path.span.hi(),
1227 _ => default_span.lo(),
1231 fn format_tuple_struct(
1232 context: &RewriteContext,
1233 struct_parts: &StructParts,
1234 fields: &[ast::StructField],
1236 ) -> Option<String> {
1237 let mut result = String::with_capacity(1024);
1238 let span = struct_parts.span;
1240 let header_str = struct_parts.format_header();
1241 result.push_str(&header_str);
1243 let body_lo = if fields.is_empty() {
1244 let lo = get_bytepos_after_visibility(context, struct_parts.vis, span, ")");
1245 context.codemap.span_after(mk_sp(lo, span.hi()), "(")
1249 let body_hi = if fields.is_empty() {
1250 context.codemap.span_after(mk_sp(body_lo, span.hi()), ")")
1252 // This is a dirty hack to work around a missing `)` from the span of the last field.
1253 let last_arg_span = fields[fields.len() - 1].span;
1254 if context.snippet(last_arg_span).ends_with(')') {
1259 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1263 let where_clause_str = match struct_parts.generics {
1265 let budget = context.budget(last_line_width(&header_str));
1266 let shape = Shape::legacy(budget, offset);
1267 let g_span = mk_sp(span.lo(), body_lo);
1268 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1269 result.push_str(&generics_str);
1271 let where_budget = context.budget(last_line_width(&result));
1272 let option = WhereClauseOption::new(true, false);
1273 rewrite_where_clause(
1275 &generics.where_clause,
1276 context.config.brace_style(),
1277 Shape::legacy(where_budget, offset.block_only()),
1278 Density::Compressed,
1286 None => "".to_owned(),
1289 if fields.is_empty() {
1291 let used_width = last_line_used_width(&result, offset.width()) + 3;
1292 if used_width > context.config.max_width() {
1294 result.push_str(&offset
1295 .block_indent(context.config)
1296 .to_string(context.config))
1299 let snippet = context.snippet(mk_sp(
1301 context.codemap.span_before(mk_sp(body_lo, span.hi()), ")"),
1303 if snippet.is_empty() {
1305 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1306 result.push_str(snippet.trim_right());
1308 result.push_str(&offset.to_string(context.config));
1310 result.push_str(&snippet);
1314 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1315 let fields = &fields.iter().collect::<Vec<_>>()[..];
1316 let one_line_width = context.config.width_heuristics().fn_call_width;
1317 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1320 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1321 && (result.contains('\n')
1322 || offset.block_indent + result.len() + where_clause_str.len() + 1
1323 > context.config.max_width())
1325 // We need to put the where clause on a new line, but we didn't
1326 // know that earlier, so the where clause will not be indented properly.
1328 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1329 .to_string(context.config));
1331 result.push_str(&where_clause_str);
1336 pub fn rewrite_type_alias(
1337 context: &RewriteContext,
1341 generics: &ast::Generics,
1342 vis: &ast::Visibility,
1344 ) -> Option<String> {
1345 let mut result = String::with_capacity(128);
1347 result.push_str(&format_visibility(vis));
1348 result.push_str("type ");
1349 result.push_str(&ident.to_string());
1352 let shape = Shape::indented(indent + result.len(), context.config).sub_width(2)?;
1353 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo());
1354 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1355 result.push_str(&generics_str);
1357 let where_budget = context.budget(last_line_width(&result));
1358 let option = WhereClauseOption::snuggled(&result);
1359 let where_clause_str = rewrite_where_clause(
1361 &generics.where_clause,
1362 context.config.brace_style(),
1363 Shape::legacy(where_budget, indent),
1371 result.push_str(&where_clause_str);
1372 if where_clause_str.is_empty() {
1373 result.push_str(" = ");
1375 result.push_str(&format!("\n{}= ", indent.to_string(context.config)));
1378 let line_width = last_line_width(&result);
1379 // This checked_sub may fail as the extra space after '=' is not taken into account
1380 // In that case the budget is set to 0 which will make ty.rewrite retry on a new line
1381 let budget = context.budget(indent.width() + line_width + ";".len());
1382 let type_indent = indent + line_width;
1383 // Try to fit the type on the same line
1384 let ty_str = ty.rewrite(context, Shape::legacy(budget, type_indent))
1386 // The line was too short, try to put the type on the next line
1388 // Remove the space after '='
1390 let type_indent = indent.block_indent(context.config);
1392 result.push_str(&type_indent.to_string(context.config));
1393 let budget = context.budget(type_indent.width() + ";".len());
1394 ty.rewrite(context, Shape::legacy(budget, type_indent))
1396 result.push_str(&ty_str);
1397 result.push_str(";");
1401 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1403 if config.space_before_colon() { " " } else { "" },
1404 if config.space_after_colon() { " " } else { "" },
1408 pub fn rewrite_struct_field_prefix(
1409 context: &RewriteContext,
1410 field: &ast::StructField,
1411 ) -> Option<String> {
1412 let vis = format_visibility(&field.vis);
1413 let type_annotation_spacing = type_annotation_spacing(context.config);
1414 Some(match field.ident {
1415 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1416 None => format!("{}", vis),
1420 impl Rewrite for ast::StructField {
1421 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1422 rewrite_struct_field(context, self, shape, 0)
1426 pub fn rewrite_struct_field(
1427 context: &RewriteContext,
1428 field: &ast::StructField,
1430 lhs_max_width: usize,
1431 ) -> Option<String> {
1432 if contains_skip(&field.attrs) {
1433 return Some(context.snippet(mk_sp(field.attrs[0].span.lo(), field.span.hi())));
1436 let type_annotation_spacing = type_annotation_spacing(context.config);
1437 let prefix = rewrite_struct_field_prefix(context, field)?;
1439 let attrs_str = field.attrs.rewrite(context, shape)?;
1440 let attrs_extendable = attrs_str.is_empty()
1441 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
1442 let missing_span = if field.attrs.is_empty() {
1443 mk_sp(field.span.lo(), field.span.lo())
1445 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1447 let mut spacing = String::from(if field.ident.is_some() {
1448 type_annotation_spacing.1
1452 // Try to put everything on a single line.
1453 let attr_prefix = combine_strs_with_missing_comments(
1461 let overhead = last_line_width(&attr_prefix);
1462 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1463 for _ in 0..lhs_offset {
1466 // In this extreme case we will be missing a space betweeen an attribute and a field.
1467 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1470 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1471 let mut orig_ty = field.ty.rewrite(context, ty_shape);
1472 if let Some(ref ty) = orig_ty {
1473 if !ty.contains('\n') {
1474 return Some(attr_prefix + &spacing + ty);
1478 // We must use multiline. We are going to put attributes and a field on different lines.
1480 let rhs_shape = shape.offset_left(last_line_width(&prefix) + 1)?;
1481 orig_ty = field.ty.rewrite(context, rhs_shape);
1482 let field_str = if prefix.is_empty() {
1485 prefix + &choose_rhs(context, &*field.ty, rhs_shape, orig_ty)?
1487 combine_strs_with_missing_comments(context, &attrs_str, &field_str, missing_span, shape, false)
1490 pub struct StaticParts<'a> {
1492 vis: &'a ast::Visibility,
1495 mutability: ast::Mutability,
1496 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1497 defaultness: Option<ast::Defaultness>,
1501 impl<'a> StaticParts<'a> {
1502 pub fn from_item(item: &'a ast::Item) -> Self {
1503 let (prefix, ty, mutability, expr) = match item.node {
1504 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1505 ast::ItemKind::Const(ref ty, ref expr) => {
1506 ("const", ty, ast::Mutability::Immutable, expr)
1508 _ => unreachable!(),
1515 mutability: mutability,
1516 expr_opt: Some(expr),
1522 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1523 let (ty, expr_opt) = match ti.node {
1524 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1525 _ => unreachable!(),
1529 vis: &ast::Visibility::Inherited,
1532 mutability: ast::Mutability::Immutable,
1533 expr_opt: expr_opt.as_ref(),
1539 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1540 let (ty, expr) = match ii.node {
1541 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1542 _ => unreachable!(),
1549 mutability: ast::Mutability::Immutable,
1550 expr_opt: Some(expr),
1551 defaultness: Some(ii.defaultness),
1558 context: &RewriteContext,
1559 static_parts: &StaticParts,
1561 ) -> Option<String> {
1562 let colon = colon_spaces(
1563 context.config.space_before_colon(),
1564 context.config.space_after_colon(),
1566 let prefix = format!(
1568 format_visibility(static_parts.vis),
1569 static_parts.defaultness.map_or("", format_defaultness),
1570 static_parts.prefix,
1571 format_mutability(static_parts.mutability),
1577 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1578 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1580 if let Some(expr) = static_parts.expr_opt {
1581 let lhs = format!("{}{} =", prefix, ty_str);
1583 let remaining_width = context.budget(offset.block_indent + 1);
1588 Shape::legacy(remaining_width, offset.block_only()),
1589 ).and_then(|res| recover_comment_removed(res, static_parts.span, context))
1590 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1592 Some(format!("{}{};", prefix, ty_str))
1596 pub fn rewrite_associated_type(
1598 ty_opt: Option<&ptr::P<ast::Ty>>,
1599 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1600 context: &RewriteContext,
1602 ) -> Option<String> {
1603 let prefix = format!("type {}", ident);
1605 let type_bounds_str = if let Some(bounds) = ty_param_bounds_opt {
1607 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1608 let bound_str = bounds
1610 .map(|ty_bound| ty_bound.rewrite(context, shape))
1611 .collect::<Option<Vec<_>>>()?;
1612 if !bounds.is_empty() {
1613 format!(": {}", join_bounds(context, shape, &bound_str))
1621 if let Some(ty) = ty_opt {
1623 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1624 let lhs = format!("{}{} =", prefix, type_bounds_str);
1625 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1627 Some(format!("{}{};", prefix, type_bounds_str))
1631 pub fn rewrite_associated_impl_type(
1633 defaultness: ast::Defaultness,
1634 ty_opt: Option<&ptr::P<ast::Ty>>,
1635 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1636 context: &RewriteContext,
1638 ) -> Option<String> {
1639 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1642 ast::Defaultness::Default => Some(format!("default {}", result)),
1647 impl Rewrite for ast::FunctionRetTy {
1648 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1650 ast::FunctionRetTy::Default(_) => Some(String::new()),
1651 ast::FunctionRetTy::Ty(ref ty) => {
1652 let inner_width = shape.width.checked_sub(3)?;
1653 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1654 .map(|r| format!("-> {}", r))
1660 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1662 ast::TyKind::Infer => {
1663 let original = context.snippet(ty.span);
1670 impl Rewrite for ast::Arg {
1671 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1672 if is_named_arg(self) {
1673 let mut result = self.pat
1674 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1676 if !is_empty_infer(context, &*self.ty) {
1677 if context.config.space_before_colon() {
1678 result.push_str(" ");
1680 result.push_str(":");
1681 if context.config.space_after_colon() {
1682 result.push_str(" ");
1684 let overhead = last_line_width(&result);
1685 let max_width = shape.width.checked_sub(overhead)?;
1686 let ty_str = self.ty
1687 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1688 result.push_str(&ty_str);
1693 self.ty.rewrite(context, shape)
1698 fn rewrite_explicit_self(
1699 explicit_self: &ast::ExplicitSelf,
1701 context: &RewriteContext,
1702 ) -> Option<String> {
1703 match explicit_self.node {
1704 ast::SelfKind::Region(lt, m) => {
1705 let mut_str = format_mutability(m);
1708 let lifetime_str = l.rewrite(
1710 Shape::legacy(context.config.max_width(), Indent::empty()),
1712 Some(format!("&{} {}self", lifetime_str, mut_str))
1714 None => Some(format!("&{}self", mut_str)),
1717 ast::SelfKind::Explicit(ref ty, _) => {
1718 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1720 let mutability = explicit_self_mutability(&args[0]);
1721 let type_str = ty.rewrite(
1723 Shape::legacy(context.config.max_width(), Indent::empty()),
1728 format_mutability(mutability),
1732 ast::SelfKind::Value(_) => {
1733 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1735 let mutability = explicit_self_mutability(&args[0]);
1737 Some(format!("{}self", format_mutability(mutability)))
1742 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1743 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1744 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1745 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1752 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1753 if is_named_arg(arg) {
1760 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1762 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1763 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1764 _ => arg.ty.span.hi(),
1768 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1769 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1770 ident.node != symbol::keywords::Invalid.ident()
1776 // Return type is (result, force_new_line_for_brace)
1778 context: &RewriteContext,
1783 newline_brace: bool,
1785 ) -> Option<(String, bool)> {
1786 let mut force_new_line_for_brace = false;
1788 let where_clause = &fn_sig.generics.where_clause;
1790 let mut result = String::with_capacity(1024);
1791 result.push_str(&fn_sig.to_str(context));
1794 result.push_str("fn ");
1795 result.push_str(&ident.to_string());
1798 let overhead = if has_body && !newline_brace {
1805 let used_width = last_line_used_width(&result, indent.width());
1806 let one_line_budget = context.budget(used_width + overhead);
1808 width: one_line_budget,
1812 let fd = fn_sig.decl;
1813 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1814 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1815 result.push_str(&generics_str);
1817 let snuggle_angle_bracket = generics_str
1820 .map_or(false, |l| l.trim_left().len() == 1);
1822 // Note that the width and indent don't really matter, we'll re-layout the
1823 // return type later anyway.
1824 let ret_str = fd.output
1825 .rewrite(context, Shape::indented(indent, context.config))?;
1827 let multi_line_ret_str = ret_str.contains('\n');
1828 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1831 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1842 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1848 // Check if vertical layout was forced.
1849 if one_line_budget == 0 {
1850 if snuggle_angle_bracket {
1853 result.push_str("(");
1854 if context.config.indent_style() == IndentStyle::Visual {
1856 result.push_str(&arg_indent.to_string(context.config));
1862 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1863 && result.ends_with('(')
1868 // Skip `pub(crate)`.
1869 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1870 // A conservative estimation, to goal is to be over all parens in generics
1871 let args_start = fn_sig
1875 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1876 let args_end = if fd.inputs.is_empty() {
1879 .span_after(mk_sp(args_start, span.hi()), ")")
1881 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1882 context.codemap.span_after(last_span, ")")
1884 let args_span = mk_sp(
1887 .span_after(mk_sp(args_start, span.hi()), "("),
1890 let arg_str = rewrite_args(
1893 fd.get_self().as_ref(),
1900 generics_str.contains('\n'),
1903 let put_args_in_block = match context.config.indent_style() {
1904 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1906 } && !fd.inputs.is_empty();
1908 let mut args_last_line_contains_comment = false;
1909 if put_args_in_block {
1910 arg_indent = indent.block_indent(context.config);
1912 result.push_str(&arg_indent.to_string(context.config));
1913 result.push_str(&arg_str);
1915 result.push_str(&indent.to_string(context.config));
1918 result.push_str(&arg_str);
1919 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1920 // Put the closing brace on the next line if it overflows the max width.
1922 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1925 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1928 // If the last line of args contains comment, we cannot put the closing paren
1929 // on the same line.
1933 .map_or(false, |last_line| last_line.contains("//"))
1935 args_last_line_contains_comment = true;
1937 result.push_str(&arg_indent.to_string(context.config));
1943 if let ast::FunctionRetTy::Ty(..) = fd.output {
1944 let ret_should_indent = match context.config.indent_style() {
1945 // If our args are block layout then we surely must have space.
1946 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1947 _ if args_last_line_contains_comment => false,
1948 _ if result.contains('\n') || multi_line_ret_str => true,
1950 // If the return type would push over the max width, then put the return type on
1951 // a new line. With the +1 for the signature length an additional space between
1952 // the closing parenthesis of the argument and the arrow '->' is considered.
1953 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1955 // If there is no where clause, take into account the space after the return type
1957 if where_clause.predicates.is_empty() {
1961 sig_length > context.config.max_width()
1964 let ret_indent = if ret_should_indent {
1965 let indent = if arg_str.is_empty() {
1966 // Aligning with non-existent args looks silly.
1967 force_new_line_for_brace = true;
1970 // FIXME: we might want to check that using the arg indent
1971 // doesn't blow our budget, and if it does, then fallback to
1972 // the where clause indent.
1977 result.push_str(&indent.to_string(context.config));
1981 Indent::new(indent.block_indent, last_line_width(&result))
1984 if multi_line_ret_str || ret_should_indent {
1985 // Now that we know the proper indent and width, we need to
1986 // re-layout the return type.
1987 let ret_str = fd.output
1988 .rewrite(context, Shape::indented(ret_indent, context.config))?;
1989 result.push_str(&ret_str);
1991 result.push_str(&ret_str);
1994 // Comment between return type and the end of the decl.
1995 let snippet_lo = fd.output.span().hi();
1996 if where_clause.predicates.is_empty() {
1997 let snippet_hi = span.hi();
1998 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
1999 // Try to preserve the layout of the original snippet.
2000 let original_starts_with_newline = snippet
2002 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2003 let original_ends_with_newline = snippet
2004 .rfind(|c| c != ' ')
2005 .map_or(false, |i| snippet[i..].ends_with('\n'));
2006 let snippet = snippet.trim();
2007 if !snippet.is_empty() {
2008 result.push(if original_starts_with_newline {
2013 result.push_str(snippet);
2014 if original_ends_with_newline {
2015 force_new_line_for_brace = true;
2021 let pos_before_where = match fd.output {
2022 ast::FunctionRetTy::Default(..) => args_span.hi(),
2023 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2026 let is_args_multi_lined = arg_str.contains('\n');
2028 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2029 let where_clause_str = rewrite_where_clause(
2032 context.config.brace_style(),
2033 Shape::indented(indent, context.config),
2039 is_args_multi_lined,
2041 // If there are neither where clause nor return type, we may be missing comments between
2043 if where_clause_str.is_empty() {
2044 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2045 match recover_missing_comment_in_span(
2046 mk_sp(args_span.hi(), ret_span.hi()),
2049 last_line_width(&result),
2051 Some(ref missing_comment) if !missing_comment.is_empty() => {
2052 result.push_str(missing_comment);
2053 force_new_line_for_brace = true;
2060 result.push_str(&where_clause_str);
2062 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2063 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2064 Some((result, force_new_line_for_brace))
2067 #[derive(Copy, Clone)]
2068 struct WhereClauseOption {
2069 suppress_comma: bool, // Force no trailing comma
2070 snuggle: bool, // Do not insert newline before `where`
2071 compress_where: bool, // Try single line where clause instead of vertical layout
2074 impl WhereClauseOption {
2075 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2077 suppress_comma: suppress_comma,
2079 compress_where: false,
2083 pub fn snuggled(current: &str) -> WhereClauseOption {
2085 suppress_comma: false,
2086 snuggle: trimmed_last_line_width(current) == 1,
2087 compress_where: false,
2093 context: &RewriteContext,
2095 explicit_self: Option<&ast::ExplicitSelf>,
2096 one_line_budget: usize,
2097 multi_line_budget: usize,
2102 generics_str_contains_newline: bool,
2103 ) -> Option<String> {
2104 let mut arg_item_strs = args.iter()
2105 .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
2106 .collect::<Option<Vec<_>>>()?;
2108 // Account for sugary self.
2109 // FIXME: the comment for the self argument is dropped. This is blocked
2110 // on rust issue #27522.
2111 let min_args = explicit_self
2112 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2113 .map_or(1, |self_str| {
2114 arg_item_strs[0] = self_str;
2118 // Comments between args.
2119 let mut arg_items = Vec::new();
2121 arg_items.push(ListItem::from_str(""));
2124 // FIXME(#21): if there are no args, there might still be a comment, but
2125 // without spans for the comment or parens, there is no chance of
2126 // getting it right. You also don't get to put a comment on self, unless
2128 if args.len() >= min_args || variadic {
2129 let comment_span_start = if min_args == 2 {
2130 let second_arg_start = if arg_has_pattern(&args[1]) {
2131 args[1].pat.span.lo()
2133 args[1].ty.span.lo()
2135 let reduced_span = mk_sp(span.lo(), second_arg_start);
2137 context.codemap.span_after_last(reduced_span, ",")
2142 enum ArgumentKind<'a> {
2143 Regular(&'a ast::Arg),
2147 let variadic_arg = if variadic {
2148 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2149 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2150 Some(ArgumentKind::Variadic(variadic_start))
2155 let more_items = itemize_list(
2157 args[min_args - 1..]
2159 .map(ArgumentKind::Regular)
2160 .chain(variadic_arg),
2164 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2165 ArgumentKind::Variadic(start) => start,
2168 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2169 ArgumentKind::Variadic(start) => start + BytePos(3),
2172 ArgumentKind::Regular(..) => None,
2173 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2180 arg_items.extend(more_items);
2183 let fits_in_one_line = !generics_str_contains_newline
2184 && (arg_items.is_empty()
2185 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2187 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2188 item.item = Some(arg);
2191 let last_line_ends_with_comment = arg_items
2194 .and_then(|item| item.post_comment.as_ref())
2195 .map_or(false, |s| s.trim().starts_with("//"));
2197 let (indent, trailing_comma) = match context.config.indent_style() {
2198 IndentStyle::Block if fits_in_one_line => {
2199 (indent.block_indent(context.config), SeparatorTactic::Never)
2201 IndentStyle::Block => (
2202 indent.block_indent(context.config),
2203 context.config.trailing_comma(),
2205 IndentStyle::Visual if last_line_ends_with_comment => {
2206 (arg_indent, context.config.trailing_comma())
2208 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2211 let tactic = definitive_tactic(
2213 context.config.fn_args_density().to_list_tactic(),
2217 let budget = match tactic {
2218 DefinitiveListTactic::Horizontal => one_line_budget,
2219 _ => multi_line_budget,
2222 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2224 let fmt = ListFormatting {
2227 trailing_separator: if variadic {
2228 SeparatorTactic::Never
2232 separator_place: SeparatorPlace::Back,
2233 shape: Shape::legacy(budget, indent),
2234 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2235 preserve_newline: true,
2236 config: context.config,
2239 write_list(&arg_items, &fmt)
2242 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2243 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2244 ident.node != symbol::keywords::Invalid.ident()
2250 fn compute_budgets_for_args(
2251 context: &RewriteContext,
2255 newline_brace: bool,
2257 force_vertical_layout: bool,
2258 ) -> Option<((usize, usize, Indent))> {
2260 "compute_budgets_for_args {} {:?}, {}, {}",
2266 // Try keeping everything on the same line.
2267 if !result.contains('\n') && !force_vertical_layout {
2268 // 2 = `()`, 3 = `() `, space is before ret_string.
2269 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2270 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2280 let one_line_budget = context.budget(used_space);
2282 if one_line_budget > 0 {
2284 let (indent, multi_line_budget) = match context.config.indent_style() {
2285 IndentStyle::Block => {
2286 let indent = indent.block_indent(context.config);
2287 (indent, context.budget(indent.width() + 1))
2289 IndentStyle::Visual => {
2290 let indent = indent + result.len() + 1;
2291 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2292 (indent, context.budget(multi_line_overhead))
2296 return Some((one_line_budget, multi_line_budget, indent));
2300 // Didn't work. we must force vertical layout and put args on a newline.
2301 let new_indent = indent.block_indent(context.config);
2302 let used_space = match context.config.indent_style() {
2304 IndentStyle::Block => new_indent.width() + 1,
2305 // Account for `)` and possibly ` {`.
2306 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2308 Some((0, context.budget(used_space), new_indent))
2311 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2312 let predicate_count = where_clause.predicates.len();
2314 if config.where_single_line() && predicate_count == 1 {
2317 let brace_style = config.brace_style();
2319 brace_style == BraceStyle::AlwaysNextLine
2320 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2323 fn rewrite_generics(
2324 context: &RewriteContext,
2325 generics: &ast::Generics,
2328 ) -> Option<String> {
2329 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2330 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2331 rewrite_generics_inner(context, generics, g_shape, one_line_width, span)
2332 .or_else(|| rewrite_generics_inner(context, generics, g_shape, 0, span))
2335 fn rewrite_generics_inner(
2336 context: &RewriteContext,
2337 generics: &ast::Generics,
2339 one_line_width: usize,
2341 ) -> Option<String> {
2342 // FIXME: convert bounds to where clauses where they get too big or if
2343 // there is a where clause at all.
2346 enum GenericsArg<'a> {
2347 Lifetime(&'a ast::LifetimeDef),
2348 TyParam(&'a ast::TyParam),
2350 impl<'a> Rewrite for GenericsArg<'a> {
2351 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2353 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2354 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2358 impl<'a> Spanned for GenericsArg<'a> {
2359 fn span(&self) -> Span {
2361 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2362 GenericsArg::TyParam(ty) => ty.span(),
2367 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2368 return Some(String::new());
2371 let generics_args = generics
2374 .map(|lt| GenericsArg::Lifetime(lt))
2375 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2376 let items = itemize_list(
2381 |arg| arg.span().lo(),
2382 |arg| arg.span().hi(),
2383 |arg| arg.rewrite(context, shape),
2384 context.codemap.span_after(span, "<"),
2388 format_generics_item_list(context, items, shape, one_line_width)
2391 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2392 match config.indent_style() {
2393 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2394 IndentStyle::Block => {
2398 .block_indent(config.tab_spaces())
2399 .with_max_width(config)
2405 pub fn format_generics_item_list<I>(
2406 context: &RewriteContext,
2409 one_line_budget: usize,
2412 I: Iterator<Item = ListItem>,
2414 let item_vec = items.collect::<Vec<_>>();
2416 let tactic = definitive_tactic(
2418 ListTactic::HorizontalVertical,
2422 let fmt = ListFormatting {
2425 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2426 SeparatorTactic::Never
2428 context.config.trailing_comma()
2430 separator_place: SeparatorPlace::Back,
2432 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2433 preserve_newline: true,
2434 config: context.config,
2437 let list_str = write_list(&item_vec, &fmt)?;
2439 Some(wrap_generics_with_angle_brackets(
2446 pub fn wrap_generics_with_angle_brackets(
2447 context: &RewriteContext,
2449 list_offset: Indent,
2451 if context.config.indent_style() == IndentStyle::Block
2452 && (list_str.contains('\n') || list_str.ends_with(','))
2456 list_offset.to_string(context.config),
2459 .block_unindent(context.config)
2460 .to_string(context.config)
2462 } else if context.config.spaces_within_parens_and_brackets() {
2463 format!("< {} >", list_str)
2465 format!("<{}>", list_str)
2469 fn rewrite_trait_bounds(
2470 context: &RewriteContext,
2471 bounds: &[ast::TyParamBound],
2473 ) -> Option<String> {
2474 if bounds.is_empty() {
2475 return Some(String::new());
2477 let bound_str = bounds
2479 .map(|ty_bound| ty_bound.rewrite(context, shape))
2480 .collect::<Option<Vec<_>>>()?;
2481 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2484 fn rewrite_where_clause_rfc_style(
2485 context: &RewriteContext,
2486 where_clause: &ast::WhereClause,
2489 span_end: Option<BytePos>,
2490 span_end_before_where: BytePos,
2491 where_clause_option: WhereClauseOption,
2492 is_args_multi_line: bool,
2493 ) -> Option<String> {
2494 let block_shape = shape.block().with_max_width(context.config);
2496 let (span_before, span_after) =
2497 missing_span_before_after_where(span_end_before_where, where_clause);
2498 let (comment_before, comment_after) =
2499 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2501 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2504 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2507 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2509 let clause_shape = clause_shape.sub_width(1)?;
2510 // each clause on one line, trailing comma (except if suppress_comma)
2511 let span_start = where_clause.predicates[0].span().lo();
2512 // If we don't have the start of the next span, then use the end of the
2513 // predicates, but that means we miss comments.
2514 let len = where_clause.predicates.len();
2515 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2516 let span_end = span_end.unwrap_or(end_of_preds);
2517 let items = itemize_list(
2519 where_clause.predicates.iter(),
2522 |pred| pred.span().lo(),
2523 |pred| pred.span().hi(),
2524 |pred| pred.rewrite(context, clause_shape),
2529 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2530 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2531 SeparatorTactic::Never
2533 context.config.trailing_comma()
2536 // shape should be vertical only and only if we have `where_single_line` option enabled
2537 // and the number of items of the where clause is equal to 1
2538 let shape_tactic = if where_single_line {
2539 DefinitiveListTactic::Horizontal
2541 DefinitiveListTactic::Vertical
2544 let fmt = ListFormatting {
2545 tactic: shape_tactic,
2547 trailing_separator: comma_tactic,
2548 separator_place: SeparatorPlace::Back,
2549 shape: clause_shape,
2550 ends_with_newline: true,
2551 preserve_newline: true,
2552 config: context.config,
2554 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2556 let comment_separator = |comment: &str, shape: Shape| if comment.is_empty() {
2559 format!("\n{}", shape.indent.to_string(context.config))
2561 let newline_before_where = comment_separator(&comment_before, shape);
2562 let newline_after_where = comment_separator(&comment_after, clause_shape);
2565 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2566 && comment_after.is_empty() && !preds_str.contains('\n')
2567 && 6 + preds_str.len() <= shape.width || where_single_line
2571 format!("\n{}", clause_shape.indent.to_string(context.config))
2574 "{}{}{}where{}{}{}{}",
2577 newline_before_where,
2578 newline_after_where,
2585 fn rewrite_where_clause(
2586 context: &RewriteContext,
2587 where_clause: &ast::WhereClause,
2588 brace_style: BraceStyle,
2592 span_end: Option<BytePos>,
2593 span_end_before_where: BytePos,
2594 where_clause_option: WhereClauseOption,
2595 is_args_multi_line: bool,
2596 ) -> Option<String> {
2597 if where_clause.predicates.is_empty() {
2598 return Some(String::new());
2601 if context.config.indent_style() == IndentStyle::Block {
2602 return rewrite_where_clause_rfc_style(
2608 span_end_before_where,
2609 where_clause_option,
2614 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2616 let offset = match context.config.indent_style() {
2617 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2618 // 6 = "where ".len()
2619 IndentStyle::Visual => shape.indent + extra_indent + 6,
2621 // FIXME: if indent_style != Visual, then the budgets below might
2622 // be out by a char or two.
2624 let budget = context.config.max_width() - offset.width();
2625 let span_start = where_clause.predicates[0].span().lo();
2626 // If we don't have the start of the next span, then use the end of the
2627 // predicates, but that means we miss comments.
2628 let len = where_clause.predicates.len();
2629 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2630 let span_end = span_end.unwrap_or(end_of_preds);
2631 let items = itemize_list(
2633 where_clause.predicates.iter(),
2636 |pred| pred.span().lo(),
2637 |pred| pred.span().hi(),
2638 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2643 let item_vec = items.collect::<Vec<_>>();
2644 // FIXME: we don't need to collect here
2645 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2647 let mut comma_tactic = context.config.trailing_comma();
2648 // Kind of a hack because we don't usually have trailing commas in where clauses.
2649 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2650 comma_tactic = SeparatorTactic::Never;
2653 let fmt = ListFormatting {
2656 trailing_separator: comma_tactic,
2657 separator_place: SeparatorPlace::Back,
2658 shape: Shape::legacy(budget, offset),
2659 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2660 preserve_newline: true,
2661 config: context.config,
2663 let preds_str = write_list(&item_vec, &fmt)?;
2665 let end_length = if terminator == "{" {
2666 // If the brace is on the next line we don't need to count it otherwise it needs two
2669 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2670 BraceStyle::PreferSameLine => 2,
2672 } else if terminator == "=" {
2677 if density == Density::Tall || preds_str.contains('\n')
2678 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2682 (shape.indent + extra_indent).to_string(context.config),
2686 Some(format!(" where {}", preds_str))
2690 fn missing_span_before_after_where(
2691 before_item_span_end: BytePos,
2692 where_clause: &ast::WhereClause,
2694 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2696 let pos_after_where = where_clause.span.lo() + BytePos(5);
2697 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2698 (missing_span_before, missing_span_after)
2701 fn rewrite_comments_before_after_where(
2702 context: &RewriteContext,
2703 span_before_where: Span,
2704 span_after_where: Span,
2706 ) -> Option<(String, String)> {
2707 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2708 let after_comment = rewrite_missing_comment(
2710 shape.block_indent(context.config.tab_spaces()),
2713 Some((before_comment, after_comment))
2716 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2717 format!("{}{}{}", format_visibility(vis), item_name, ident)
2720 #[derive(PartialEq, Eq)]
2728 context: &RewriteContext,
2729 generics: &ast::Generics,
2730 brace_style: BraceStyle,
2731 brace_pos: BracePos,
2735 ) -> Option<String> {
2736 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2737 let mut result = rewrite_generics(context, generics, shape, span)?;
2739 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2740 let budget = context.budget(last_line_used_width(&result, offset.width()));
2741 let mut option = WhereClauseOption::snuggled(&result);
2742 if brace_pos == BracePos::None {
2743 option.suppress_comma = true;
2745 // If the generics are not parameterized then generics.span.hi() == 0,
2746 // so we use span.lo(), which is the position after `struct Foo`.
2747 let span_end_before_where = if generics.is_parameterized() {
2752 let where_clause_str = rewrite_where_clause(
2754 &generics.where_clause,
2756 Shape::legacy(budget, offset.block_only()),
2760 span_end_before_where,
2764 result.push_str(&where_clause_str);
2765 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2766 || (generics.where_clause.predicates.is_empty()
2767 && trimmed_last_line_width(&result) == 1)
2769 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2770 || brace_style != BraceStyle::AlwaysNextLine
2772 if brace_pos == BracePos::None {
2773 return Some(result);
2775 let total_used_width = last_line_used_width(&result, used_width);
2776 let remaining_budget = context.budget(total_used_width);
2777 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2778 // and hence we take the closer into account as well for one line budget.
2779 // We assume that the closer has the same length as the opener.
2780 let overhead = if brace_pos == BracePos::ForceSameLine {
2787 let forbid_same_line_brace = overhead > remaining_budget;
2788 if !forbid_same_line_brace && same_line_brace {
2792 result.push_str(&offset.block_only().to_string(context.config));
2799 impl Rewrite for ast::ForeignItem {
2800 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2801 let attrs_str = self.attrs.rewrite(context, shape)?;
2802 // Drop semicolon or it will be interpreted as comment.
2803 // FIXME: this may be a faulty span from libsyntax.
2804 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2806 let item_str = match self.node {
2807 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2812 &FnSig::new(fn_decl, generics, self.vis.clone()),
2816 ).map(|(s, _)| format!("{};", s))
2818 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2819 // FIXME(#21): we're dropping potential comments in between the
2820 // function keywords here.
2821 let vis = format_visibility(&self.vis);
2822 let mut_str = if is_mutable { "mut " } else { "" };
2823 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2825 let shape = shape.sub_width(1)?;
2826 ty.rewrite(context, shape).map(|ty_str| {
2827 // 1 = space between prefix and type.
2828 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2831 let nested_indent = shape.indent.block_indent(context.config);
2832 format!("\n{}", nested_indent.to_string(context.config))
2834 format!("{}{}{};", prefix, sep, ty_str)
2837 ast::ForeignItemKind::Ty => {
2838 let vis = format_visibility(&self.vis);
2839 Some(format!("{}type {};", vis, self.ident))
2843 let missing_span = if self.attrs.is_empty() {
2844 mk_sp(self.span.lo(), self.span.lo())
2846 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2848 combine_strs_with_missing_comments(