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 => if contains_comment(&enum_snippet[brace_pos..]) {
456 self.format_missing_no_indent(span.hi() - BytePos(1))
459 self.block_indent = self.block_indent.block_unindent(self.config);
461 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
463 .push_str(&self.block_indent.to_string(self.config));
465 self.buffer.push_str("}");
466 self.last_pos = span.hi();
469 // Format the body of an enum definition
470 fn format_variant_list(
472 enum_def: &ast::EnumDef,
475 ) -> Option<String> {
476 if enum_def.variants.is_empty() {
479 let mut result = String::with_capacity(1024);
481 let indentation = self.block_indent.to_string(self.config);
482 result.push_str(&indentation);
484 let itemize_list_with = |one_line_width: usize| {
487 enum_def.variants.iter(),
490 |f| if !f.node.attrs.is_empty() {
491 f.node.attrs[0].span.lo()
496 |f| self.format_variant(f, one_line_width),
502 let mut items: Vec<_> =
503 itemize_list_with(self.config.width_heuristics().struct_variant_width);
504 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
505 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains("\n"));
506 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains("\n"));
507 if has_multiline_variant && has_single_line_variant {
508 items = itemize_list_with(0);
511 let shape = self.shape().sub_width(2).unwrap();
512 let fmt = ListFormatting {
513 tactic: DefinitiveListTactic::Vertical,
515 trailing_separator: self.config.trailing_comma(),
516 separator_place: SeparatorPlace::Back,
518 ends_with_newline: true,
519 preserve_newline: true,
523 let list = write_list(&items, &fmt)?;
524 result.push_str(&list);
529 // Variant of an enum.
530 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
531 if contains_skip(&field.node.attrs) {
532 let lo = field.node.attrs[0].span.lo();
533 let span = mk_sp(lo, field.span.hi());
534 return Some(self.snippet(span));
537 let context = self.get_context();
538 let indent = self.block_indent;
539 let shape = self.shape();
540 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
545 .map_or(field.span.lo(), |attr| attr.span.hi());
546 let span = mk_sp(lo, field.span.lo());
548 let variant_body = match field.node.data {
549 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => {
550 // FIXME: Should limit the width, as we have a trailing comma
553 &StructParts::from_variant(field),
555 Some(one_line_width),
558 ast::VariantData::Unit(..) => if let Some(ref expr) = field.node.disr_expr {
559 let lhs = format!("{} =", field.node.name);
561 rewrite_assign_rhs(&context, lhs, &**expr, shape.sub_width(1)?)?
563 field.node.name.to_string()
567 let attrs_extendable = attrs_str.is_empty()
568 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
569 combine_strs_with_missing_comments(
581 context: &RewriteContext,
584 where_span_end: Option<BytePos>,
585 ) -> Option<String> {
586 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
587 let mut result = String::with_capacity(128);
588 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
589 let indent_str = offset.to_string(context.config);
590 let sep = format!("\n{}", &indent_str);
591 result.push_str(&ref_and_type);
593 let where_budget = if result.contains('\n') {
594 context.config.max_width()
596 context.budget(last_line_width(&result))
598 let option = WhereClauseOption::snuggled(&ref_and_type);
599 let where_clause_str = rewrite_where_clause(
601 &generics.where_clause,
602 context.config.brace_style(),
603 Shape::legacy(where_budget, offset.block_only()),
612 // If there is no where clause, we may have missing comments between the trait name and
613 // the opening brace.
614 if generics.where_clause.predicates.is_empty() {
615 if let Some(hi) = where_span_end {
616 match recover_missing_comment_in_span(
617 mk_sp(self_ty.span.hi(), hi),
618 Shape::indented(offset, context.config),
620 last_line_width(&result),
622 Some(ref missing_comment) if !missing_comment.is_empty() => {
623 result.push_str(missing_comment);
630 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
631 result.push_str(&where_clause_str);
632 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
633 result.push_str(&format!("{}{{{}}}", &sep, &sep));
635 result.push_str(" {}");
640 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
642 let width = offset.block_indent + context.config.tab_spaces() - 1;
643 let where_indent = Indent::new(0, width);
644 result.push_str(&where_indent.to_string(context.config));
646 result.push_str(&where_clause_str);
648 match context.config.brace_style() {
649 _ if last_line_contains_single_line_comment(&result) => result.push_str(&sep),
650 BraceStyle::AlwaysNextLine => result.push_str(&sep),
651 BraceStyle::PreferSameLine => result.push(' '),
652 BraceStyle::SameLineWhere => if !where_clause_str.is_empty() {
653 result.push_str(&sep);
661 let snippet = context.snippet(item.span);
662 let open_pos = snippet.find_uncommented("{")? + 1;
664 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
665 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
666 visitor.block_indent = offset.block_only().block_indent(context.config);
667 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
669 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
671 visitor.visit_impl_item(item);
674 visitor.format_missing(item.span.hi() - BytePos(1));
676 let inner_indent_str = visitor.block_indent.to_string(context.config);
677 let outer_indent_str = offset.block_only().to_string(context.config);
680 result.push_str(&inner_indent_str);
681 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
683 result.push_str(&outer_indent_str);
686 if result.ends_with('{') {
687 result.push_str(&sep);
697 fn is_impl_single_line(
698 context: &RewriteContext,
701 where_clause_str: &str,
704 let snippet = context.snippet(item.span);
705 let open_pos = snippet.find_uncommented("{")? + 1;
708 context.config.empty_item_single_line() && items.is_empty() && !result.contains('\n')
709 && result.len() + where_clause_str.len() <= context.config.max_width()
710 && !contains_comment(&snippet[open_pos..]),
714 fn format_impl_ref_and_type(
715 context: &RewriteContext,
718 ) -> Option<String> {
719 if let ast::ItemKind::Impl(
729 let mut result = String::with_capacity(128);
731 result.push_str(&format_visibility(&item.vis));
732 result.push_str(format_defaultness(defaultness));
733 result.push_str(format_unsafety(unsafety));
734 result.push_str("impl");
736 let lo = context.codemap.span_after(item.span, "impl");
737 let hi = match *trait_ref {
738 Some(ref tr) => tr.path.span.lo(),
739 None => self_ty.span.lo(),
741 let shape = generics_shape_from_config(
743 Shape::indented(offset + last_line_width(&result), context.config),
746 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
748 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
750 let polarity_str = if polarity == ast::ImplPolarity::Negative {
756 if let Some(ref trait_ref) = *trait_ref {
757 let result_len = result.len();
758 if let Some(trait_ref_str) = rewrite_trait_ref(
767 result.push_str(&trait_ref_str);
770 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
771 result.push_str(&rewrite_trait_ref(
782 result.push_str(&generics_str);
785 // Try to put the self type in a single line.
787 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
788 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
789 // If there is no where clause adapt budget for type formatting to take space and curly
790 // brace into account.
791 match context.config.brace_style() {
792 BraceStyle::AlwaysNextLine => 0,
798 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
799 // 1 = space before the type.
800 let budget = context.budget(used_space + 1);
801 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
802 if !self_ty_str.contains('\n') {
803 if trait_ref.is_some() {
804 result.push_str(" for ");
808 result.push_str(&self_ty_str);
813 // Couldn't fit the self type on a single line, put it on a new line.
815 // Add indentation of one additional tab.
816 let new_line_offset = offset.block_indent(context.config);
817 result.push_str(&new_line_offset.to_string(context.config));
818 if trait_ref.is_some() {
819 result.push_str("for ");
821 let budget = context.budget(last_line_width(&result));
822 let type_offset = match context.config.indent_style() {
823 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
824 IndentStyle::Block => new_line_offset,
826 result.push_str(&*self_ty
827 .rewrite(context, Shape::legacy(budget, type_offset))?);
834 fn rewrite_trait_ref(
835 context: &RewriteContext,
836 trait_ref: &ast::TraitRef,
842 ) -> Option<String> {
843 // 1 = space between generics and trait_ref
844 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
845 let shape = Shape::indented(offset + used_space, context.config);
846 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
847 if !(retry && trait_ref_str.contains('\n')) {
856 // We could not make enough space for trait_ref, so put it on new line.
858 let offset = offset.block_indent(context.config);
859 let shape = Shape::indented(offset, context.config);
860 let trait_ref_str = trait_ref.rewrite(context, shape)?;
864 &offset.to_string(context.config),
873 pub struct StructParts<'a> {
876 vis: &'a ast::Visibility,
877 def: &'a ast::VariantData,
878 generics: Option<&'a ast::Generics>,
882 impl<'a> StructParts<'a> {
883 fn format_header(&self) -> String {
884 format_header(self.prefix, self.ident, self.vis)
887 fn from_variant(variant: &'a ast::Variant) -> Self {
890 ident: variant.node.name,
891 vis: &ast::Visibility::Inherited,
892 def: &variant.node.data,
898 pub fn from_item(item: &'a ast::Item) -> Self {
899 let (prefix, def, generics) = match item.node {
900 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
901 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
909 generics: Some(generics),
916 context: &RewriteContext,
917 struct_parts: &StructParts,
919 one_line_width: Option<usize>,
920 ) -> Option<String> {
921 match *struct_parts.def {
922 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
923 ast::VariantData::Tuple(ref fields, _) => {
924 format_tuple_struct(context, struct_parts, fields, offset)
926 ast::VariantData::Struct(ref fields, _) => {
927 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
932 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
933 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
936 let mut result = String::with_capacity(128);
937 let header = format!(
939 format_visibility(&item.vis),
940 format_unsafety(unsafety),
944 result.push_str(&header);
946 let body_lo = context.codemap.span_after(item.span, "{");
948 let shape = Shape::indented(offset, context.config);
950 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
951 result.push_str(&generics_str);
953 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
954 if !type_param_bounds.is_empty() {
955 let ident_hi = context.codemap.span_after(item.span, &format!("{}", item.ident));
956 let bound_hi = type_param_bounds.last().unwrap().span().hi();
957 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
958 if contains_comment(&snippet) {
962 let trait_bound_str = rewrite_trait_bounds(
965 Shape::indented(offset, context.config),
967 // If the trait, generics, and trait bound cannot fit on the same line,
968 // put the trait bounds on an indented new line
969 if offset.width() + last_line_width(&result) + trait_bound_str.len()
970 > context.config.comment_width()
973 let trait_indent = offset.block_only().block_indent(context.config);
974 result.push_str(&trait_indent.to_string(context.config));
976 result.push_str(&trait_bound_str);
979 if context.config.indent_style() == IndentStyle::Block && result.is_empty() {
985 let where_budget = context.budget(last_line_width(&result));
986 let pos_before_where = if type_param_bounds.is_empty() {
987 generics.where_clause.span.lo()
989 type_param_bounds[type_param_bounds.len() - 1].span().hi()
991 let option = WhereClauseOption::snuggled(&generics_str);
992 let where_clause_str = rewrite_where_clause(
994 &generics.where_clause,
995 context.config.brace_style(),
996 Shape::legacy(where_budget, offset.block_only()),
1004 // If the where clause cannot fit on the same line,
1005 // put the where clause on a new line
1006 if !where_clause_str.contains('\n')
1007 && last_line_width(&result) + where_clause_str.len() + offset.width()
1008 > context.config.comment_width()
1011 let width = offset.block_indent + context.config.tab_spaces() - 1;
1012 let where_indent = Indent::new(0, width);
1013 result.push_str(&where_indent.to_string(context.config));
1015 result.push_str(&where_clause_str);
1017 if generics.where_clause.predicates.is_empty() {
1018 let item_snippet = context.snippet(item.span);
1019 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1021 let comment_hi = body_lo - BytePos(1);
1022 let comment_lo = item.span.lo() + BytePos(lo as u32);
1023 if comment_lo < comment_hi {
1024 match recover_missing_comment_in_span(
1025 mk_sp(comment_lo, comment_hi),
1026 Shape::indented(offset, context.config),
1028 last_line_width(&result),
1030 Some(ref missing_comment) if !missing_comment.is_empty() => {
1031 result.push_str(missing_comment);
1039 match context.config.brace_style() {
1040 _ if last_line_contains_single_line_comment(&result) => {
1042 result.push_str(&offset.to_string(context.config));
1044 BraceStyle::AlwaysNextLine => {
1046 result.push_str(&offset.to_string(context.config));
1048 BraceStyle::PreferSameLine => result.push(' '),
1049 BraceStyle::SameLineWhere => if !where_clause_str.is_empty()
1050 && (!trait_items.is_empty() || result.contains('\n'))
1053 result.push_str(&offset.to_string(context.config));
1060 let snippet = context.snippet(item.span);
1061 let open_pos = snippet.find_uncommented("{")? + 1;
1063 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1064 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
1065 visitor.block_indent = offset.block_only().block_indent(context.config);
1066 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1068 for item in trait_items {
1069 visitor.visit_trait_item(item);
1072 visitor.format_missing(item.span.hi() - BytePos(1));
1074 let inner_indent_str = visitor.block_indent.to_string(context.config);
1075 let outer_indent_str = offset.block_only().to_string(context.config);
1078 result.push_str(&inner_indent_str);
1079 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1081 result.push_str(&outer_indent_str);
1082 } else if result.contains('\n') {
1093 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1094 let header_str = format_header(p.prefix, p.ident, p.vis);
1095 let generics_str = if let Some(generics) = p.generics {
1096 let hi = if generics.where_clause.predicates.is_empty() {
1099 generics.where_clause.span.hi()
1104 context.config.brace_style(),
1107 mk_sp(generics.span.lo(), hi),
1108 last_line_width(&header_str),
1113 Some(format!("{}{};", header_str, generics_str))
1116 pub fn format_struct_struct(
1117 context: &RewriteContext,
1118 struct_parts: &StructParts,
1119 fields: &[ast::StructField],
1121 one_line_width: Option<usize>,
1122 ) -> Option<String> {
1123 let mut result = String::with_capacity(1024);
1124 let span = struct_parts.span;
1126 let header_str = struct_parts.format_header();
1127 result.push_str(&header_str);
1129 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1130 let body_lo = context.codemap.span_after(span, "{");
1132 let generics_str = match struct_parts.generics {
1133 Some(g) => format_generics(
1136 context.config.brace_style(),
1137 if fields.is_empty() {
1138 BracePos::ForceSameLine
1143 mk_sp(header_hi, body_lo),
1144 last_line_width(&result),
1147 // 3 = ` {}`, 2 = ` {`.
1148 let overhead = if fields.is_empty() { 3 } else { 2 };
1149 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1150 || context.config.max_width() < overhead + result.len()
1152 format!("\n{}{{", offset.block_only().to_string(context.config))
1159 let overhead = if fields.is_empty() { 1 } else { 0 };
1160 let total_width = result.len() + generics_str.len() + overhead;
1161 if !generics_str.is_empty() && !generics_str.contains('\n')
1162 && total_width > context.config.max_width()
1165 result.push_str(&offset.to_string(context.config));
1166 result.push_str(generics_str.trim_left());
1168 result.push_str(&generics_str);
1171 if fields.is_empty() {
1172 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1173 if snippet.trim().is_empty() {
1175 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1177 result.push_str(snippet.trim_right());
1179 result.push_str(&offset.to_string(context.config));
1181 result.push_str(&snippet);
1184 return Some(result);
1188 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1189 let one_line_budget =
1190 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1192 let items_str = rewrite_with_alignment(
1195 Shape::indented(offset, context.config).sub_width(1)?,
1196 mk_sp(body_lo, span.hi()),
1200 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget {
1201 Some(format!("{} {} }}", result, items_str))
1207 .block_indent(context.config)
1208 .to_string(context.config),
1210 offset.to_string(context.config)
1215 /// Returns a bytepos that is after that of `(` in `pub(..)`. If the given visibility does not
1216 /// contain `pub(..)`, then return the `lo` of the `defualt_span`. Yeah, but for what? Well, we need
1217 /// to bypass the `(` in the visibility when creating a span of tuple's body or fn's args.
1218 fn get_bytepos_after_visibility(
1219 context: &RewriteContext,
1220 vis: &ast::Visibility,
1225 ast::Visibility::Crate(s, CrateSugar::PubCrate) => context
1227 .span_after(mk_sp(s.hi(), default_span.hi()), terminator),
1228 ast::Visibility::Crate(s, CrateSugar::JustCrate) => s.hi(),
1229 ast::Visibility::Restricted { ref path, .. } => path.span.hi(),
1230 _ => default_span.lo(),
1234 fn format_tuple_struct(
1235 context: &RewriteContext,
1236 struct_parts: &StructParts,
1237 fields: &[ast::StructField],
1239 ) -> Option<String> {
1240 let mut result = String::with_capacity(1024);
1241 let span = struct_parts.span;
1243 let header_str = struct_parts.format_header();
1244 result.push_str(&header_str);
1246 let body_lo = if fields.is_empty() {
1247 let lo = get_bytepos_after_visibility(context, struct_parts.vis, span, ")");
1248 context.codemap.span_after(mk_sp(lo, span.hi()), "(")
1252 let body_hi = if fields.is_empty() {
1253 context.codemap.span_after(mk_sp(body_lo, span.hi()), ")")
1255 // This is a dirty hack to work around a missing `)` from the span of the last field.
1256 let last_arg_span = fields[fields.len() - 1].span;
1257 if context.snippet(last_arg_span).ends_with(')') {
1262 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1266 let where_clause_str = match struct_parts.generics {
1268 let budget = context.budget(last_line_width(&header_str));
1269 let shape = Shape::legacy(budget, offset);
1270 let g_span = mk_sp(span.lo(), body_lo);
1271 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1272 result.push_str(&generics_str);
1274 let where_budget = context.budget(last_line_width(&result));
1275 let option = WhereClauseOption::new(true, false);
1276 rewrite_where_clause(
1278 &generics.where_clause,
1279 context.config.brace_style(),
1280 Shape::legacy(where_budget, offset.block_only()),
1281 Density::Compressed,
1289 None => "".to_owned(),
1292 if fields.is_empty() {
1294 let used_width = last_line_used_width(&result, offset.width()) + 3;
1295 if used_width > context.config.max_width() {
1297 result.push_str(&offset
1298 .block_indent(context.config)
1299 .to_string(context.config))
1302 let snippet = context.snippet(mk_sp(
1304 context.codemap.span_before(mk_sp(body_lo, span.hi()), ")"),
1306 if snippet.is_empty() {
1308 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1309 result.push_str(snippet.trim_right());
1311 result.push_str(&offset.to_string(context.config));
1313 result.push_str(&snippet);
1317 let shape = Shape::indented(offset, context.config);
1318 let fields = &fields.iter().map(|field| field).collect::<Vec<_>>()[..];
1319 let one_line_width = context.config.width_heuristics().fn_call_width;
1320 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1323 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1324 && (result.contains('\n')
1325 || offset.block_indent + result.len() + where_clause_str.len() + 1
1326 > context.config.max_width())
1328 // We need to put the where clause on a new line, but we didn't
1329 // know that earlier, so the where clause will not be indented properly.
1331 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1332 .to_string(context.config));
1334 result.push_str(&where_clause_str);
1339 pub fn rewrite_type_alias(
1340 context: &RewriteContext,
1344 generics: &ast::Generics,
1345 vis: &ast::Visibility,
1347 ) -> Option<String> {
1348 let mut result = String::with_capacity(128);
1350 result.push_str(&format_visibility(vis));
1351 result.push_str("type ");
1352 result.push_str(&ident.to_string());
1355 let shape = Shape::indented(indent + result.len(), context.config).sub_width(2)?;
1356 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo());
1357 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1358 result.push_str(&generics_str);
1360 let where_budget = context.budget(last_line_width(&result));
1361 let option = WhereClauseOption::snuggled(&result);
1362 let where_clause_str = rewrite_where_clause(
1364 &generics.where_clause,
1365 context.config.brace_style(),
1366 Shape::legacy(where_budget, indent),
1374 result.push_str(&where_clause_str);
1375 if where_clause_str.is_empty() {
1376 result.push_str(" = ");
1378 result.push_str(&format!("\n{}= ", indent.to_string(context.config)));
1381 let line_width = last_line_width(&result);
1382 // This checked_sub may fail as the extra space after '=' is not taken into account
1383 // In that case the budget is set to 0 which will make ty.rewrite retry on a new line
1384 let budget = context.budget(indent.width() + line_width + ";".len());
1385 let type_indent = indent + line_width;
1386 // Try to fit the type on the same line
1387 let ty_str = ty.rewrite(context, Shape::legacy(budget, type_indent))
1389 // The line was too short, try to put the type on the next line
1391 // Remove the space after '='
1393 let type_indent = indent.block_indent(context.config);
1395 result.push_str(&type_indent.to_string(context.config));
1396 let budget = context.budget(type_indent.width() + ";".len());
1397 ty.rewrite(context, Shape::legacy(budget, type_indent))
1399 result.push_str(&ty_str);
1400 result.push_str(";");
1404 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1406 if config.space_before_colon() { " " } else { "" },
1407 if config.space_after_colon() { " " } else { "" },
1411 pub fn rewrite_struct_field_prefix(
1412 context: &RewriteContext,
1413 field: &ast::StructField,
1414 ) -> Option<String> {
1415 let vis = format_visibility(&field.vis);
1416 let type_annotation_spacing = type_annotation_spacing(context.config);
1417 Some(match field.ident {
1418 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1419 None => format!("{}", vis),
1423 impl Rewrite for ast::StructField {
1424 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1425 rewrite_struct_field(context, self, shape, 0)
1429 pub fn rewrite_struct_field(
1430 context: &RewriteContext,
1431 field: &ast::StructField,
1433 lhs_max_width: usize,
1434 ) -> Option<String> {
1435 if contains_skip(&field.attrs) {
1436 return Some(context.snippet(mk_sp(field.attrs[0].span.lo(), field.span.hi())));
1439 let type_annotation_spacing = type_annotation_spacing(context.config);
1440 let prefix = rewrite_struct_field_prefix(context, field)?;
1442 let attrs_str = field.attrs.rewrite(context, shape)?;
1443 let attrs_extendable = attrs_str.is_empty()
1444 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
1445 let missing_span = if field.attrs.is_empty() {
1446 mk_sp(field.span.lo(), field.span.lo())
1448 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1450 let mut spacing = String::from(if field.ident.is_some() {
1451 type_annotation_spacing.1
1455 // Try to put everything on a single line.
1456 let attr_prefix = combine_strs_with_missing_comments(
1464 let overhead = last_line_width(&attr_prefix);
1465 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1466 for _ in 0..lhs_offset {
1469 // In this extreme case we will be missing a space betweeen an attribute and a field.
1470 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1473 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1474 let mut orig_ty = field.ty.rewrite(context, ty_shape);
1475 if let Some(ref ty) = orig_ty {
1476 if !ty.contains('\n') {
1477 return Some(attr_prefix + &spacing + ty);
1481 // We must use multiline. We are going to put attributes and a field on different lines.
1483 let rhs_shape = shape.offset_left(last_line_width(&prefix) + 1)?;
1484 orig_ty = field.ty.rewrite(context, rhs_shape);
1485 let field_str = if prefix.is_empty() {
1488 prefix + &choose_rhs(context, &*field.ty, rhs_shape, orig_ty)?
1490 combine_strs_with_missing_comments(context, &attrs_str, &field_str, missing_span, shape, false)
1493 pub struct StaticParts<'a> {
1495 vis: &'a ast::Visibility,
1498 mutability: ast::Mutability,
1499 expr_opt: Option<&'a ptr::P<ast::Expr>>,
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),
1523 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1524 let (ty, expr_opt) = match ti.node {
1525 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1526 _ => unreachable!(),
1530 vis: &ast::Visibility::Inherited,
1533 mutability: ast::Mutability::Immutable,
1534 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),
1557 context: &RewriteContext,
1558 static_parts: &StaticParts,
1560 ) -> Option<String> {
1561 let colon = colon_spaces(
1562 context.config.space_before_colon(),
1563 context.config.space_after_colon(),
1565 let prefix = format!(
1567 format_visibility(static_parts.vis),
1568 static_parts.prefix,
1569 format_mutability(static_parts.mutability),
1575 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1576 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1578 if let Some(expr) = static_parts.expr_opt {
1579 let lhs = format!("{}{} =", prefix, ty_str);
1581 let remaining_width = context.budget(offset.block_indent + 1);
1586 Shape::legacy(remaining_width, offset.block_only()),
1588 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(ref 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()
2106 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| {
2115 rewrite_explicit_self(explicit_self, args, context)
2117 .map_or(1, |self_str| {
2118 arg_item_strs[0] = self_str;
2122 // Comments between args.
2123 let mut arg_items = Vec::new();
2125 arg_items.push(ListItem::from_str(""));
2128 // FIXME(#21): if there are no args, there might still be a comment, but
2129 // without spans for the comment or parens, there is no chance of
2130 // getting it right. You also don't get to put a comment on self, unless
2132 if args.len() >= min_args || variadic {
2133 let comment_span_start = if min_args == 2 {
2134 let second_arg_start = if arg_has_pattern(&args[1]) {
2135 args[1].pat.span.lo()
2137 args[1].ty.span.lo()
2139 let reduced_span = mk_sp(span.lo(), second_arg_start);
2141 context.codemap.span_after_last(reduced_span, ",")
2146 enum ArgumentKind<'a> {
2147 Regular(&'a ast::Arg),
2151 let variadic_arg = if variadic {
2152 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2153 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2154 Some(ArgumentKind::Variadic(variadic_start))
2159 let more_items = itemize_list(
2161 args[min_args - 1..]
2163 .map(ArgumentKind::Regular)
2164 .chain(variadic_arg),
2168 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2169 ArgumentKind::Variadic(start) => start,
2172 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2173 ArgumentKind::Variadic(start) => start + BytePos(3),
2176 ArgumentKind::Regular(..) => None,
2177 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2184 arg_items.extend(more_items);
2187 let fits_in_one_line = !generics_str_contains_newline
2188 && (arg_items.is_empty()
2189 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2191 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2192 item.item = Some(arg);
2195 let last_line_ends_with_comment = arg_items
2198 .and_then(|item| item.post_comment.as_ref())
2199 .map_or(false, |s| s.trim().starts_with("//"));
2201 let (indent, trailing_comma) = match context.config.indent_style() {
2202 IndentStyle::Block if fits_in_one_line => {
2203 (indent.block_indent(context.config), SeparatorTactic::Never)
2205 IndentStyle::Block => (
2206 indent.block_indent(context.config),
2207 context.config.trailing_comma(),
2209 IndentStyle::Visual if last_line_ends_with_comment => {
2210 (arg_indent, context.config.trailing_comma())
2212 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2215 let tactic = definitive_tactic(
2217 context.config.fn_args_density().to_list_tactic(),
2221 let budget = match tactic {
2222 DefinitiveListTactic::Horizontal => one_line_budget,
2223 _ => multi_line_budget,
2226 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2228 let fmt = ListFormatting {
2231 trailing_separator: if variadic {
2232 SeparatorTactic::Never
2236 separator_place: SeparatorPlace::Back,
2237 shape: Shape::legacy(budget, indent),
2238 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2239 preserve_newline: true,
2240 config: context.config,
2243 write_list(&arg_items, &fmt)
2246 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2247 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2248 ident.node != symbol::keywords::Invalid.ident()
2254 fn compute_budgets_for_args(
2255 context: &RewriteContext,
2259 newline_brace: bool,
2261 force_vertical_layout: bool,
2262 ) -> Option<((usize, usize, Indent))> {
2264 "compute_budgets_for_args {} {:?}, {}, {}",
2270 // Try keeping everything on the same line.
2271 if !result.contains('\n') && !force_vertical_layout {
2272 // 2 = `()`, 3 = `() `, space is before ret_string.
2273 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2274 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2284 let one_line_budget = context.budget(used_space);
2286 if one_line_budget > 0 {
2288 let (indent, multi_line_budget) = match context.config.indent_style() {
2289 IndentStyle::Block => {
2290 let indent = indent.block_indent(context.config);
2291 (indent, context.budget(indent.width() + 1))
2293 IndentStyle::Visual => {
2294 let indent = indent + result.len() + 1;
2295 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2296 (indent, context.budget(multi_line_overhead))
2300 return Some((one_line_budget, multi_line_budget, indent));
2304 // Didn't work. we must force vertical layout and put args on a newline.
2305 let new_indent = indent.block_indent(context.config);
2306 let used_space = match context.config.indent_style() {
2308 IndentStyle::Block => new_indent.width() + 1,
2309 // Account for `)` and possibly ` {`.
2310 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2312 Some((0, context.budget(used_space), new_indent))
2315 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2316 let predicate_count = where_clause.predicates.len();
2318 if config.where_single_line() && predicate_count == 1 {
2321 let brace_style = config.brace_style();
2323 brace_style == BraceStyle::AlwaysNextLine
2324 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2327 fn rewrite_generics(
2328 context: &RewriteContext,
2329 generics: &ast::Generics,
2332 ) -> Option<String> {
2333 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2334 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2335 rewrite_generics_inner(context, generics, g_shape, one_line_width, span).or_else(|| {
2336 rewrite_generics_inner(context, generics, g_shape, 0, span)
2340 fn rewrite_generics_inner(
2341 context: &RewriteContext,
2342 generics: &ast::Generics,
2344 one_line_width: usize,
2346 ) -> Option<String> {
2347 // FIXME: convert bounds to where clauses where they get too big or if
2348 // there is a where clause at all.
2351 enum GenericsArg<'a> {
2352 Lifetime(&'a ast::LifetimeDef),
2353 TyParam(&'a ast::TyParam),
2355 impl<'a> Rewrite for GenericsArg<'a> {
2356 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2358 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2359 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2363 impl<'a> Spanned for GenericsArg<'a> {
2364 fn span(&self) -> Span {
2366 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2367 GenericsArg::TyParam(ty) => ty.span(),
2372 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2373 return Some(String::new());
2376 let generics_args = generics
2379 .map(|lt| GenericsArg::Lifetime(lt))
2380 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2381 let items = itemize_list(
2386 |arg| arg.span().lo(),
2387 |arg| arg.span().hi(),
2388 |arg| arg.rewrite(context, shape),
2389 context.codemap.span_after(span, "<"),
2393 format_generics_item_list(context, items, shape, one_line_width)
2396 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2397 match config.indent_style() {
2398 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2399 IndentStyle::Block => {
2403 .block_indent(config.tab_spaces())
2404 .with_max_width(config)
2410 pub fn format_generics_item_list<I>(
2411 context: &RewriteContext,
2414 one_line_budget: usize,
2417 I: Iterator<Item = ListItem>,
2419 let item_vec = items.collect::<Vec<_>>();
2421 let tactic = definitive_tactic(
2423 ListTactic::HorizontalVertical,
2427 let fmt = ListFormatting {
2430 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2431 SeparatorTactic::Never
2433 context.config.trailing_comma()
2435 separator_place: SeparatorPlace::Back,
2437 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2438 preserve_newline: true,
2439 config: context.config,
2442 let list_str = write_list(&item_vec, &fmt)?;
2444 Some(wrap_generics_with_angle_brackets(
2451 pub fn wrap_generics_with_angle_brackets(
2452 context: &RewriteContext,
2454 list_offset: Indent,
2456 if context.config.indent_style() == IndentStyle::Block
2457 && (list_str.contains('\n') || list_str.ends_with(','))
2461 list_offset.to_string(context.config),
2464 .block_unindent(context.config)
2465 .to_string(context.config)
2467 } else if context.config.spaces_within_parens_and_brackets() {
2468 format!("< {} >", list_str)
2470 format!("<{}>", list_str)
2474 fn rewrite_trait_bounds(
2475 context: &RewriteContext,
2476 type_param_bounds: &ast::TyParamBounds,
2478 ) -> Option<String> {
2479 let bounds: &[_] = type_param_bounds;
2481 if bounds.is_empty() {
2482 return Some(String::new());
2484 let bound_str = bounds
2486 .map(|ty_bound| ty_bound.rewrite(context, shape))
2487 .collect::<Option<Vec<_>>>()?;
2488 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2491 fn rewrite_where_clause_rfc_style(
2492 context: &RewriteContext,
2493 where_clause: &ast::WhereClause,
2496 span_end: Option<BytePos>,
2497 span_end_before_where: BytePos,
2498 where_clause_option: WhereClauseOption,
2499 is_args_multi_line: bool,
2500 ) -> Option<String> {
2501 let block_shape = shape.block().with_max_width(context.config);
2503 let (span_before, span_after) =
2504 missing_span_before_after_where(span_end_before_where, where_clause);
2505 let (comment_before, comment_after) =
2506 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2508 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2511 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2514 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2516 let clause_shape = clause_shape.sub_width(1)?;
2517 // each clause on one line, trailing comma (except if suppress_comma)
2518 let span_start = where_clause.predicates[0].span().lo();
2519 // If we don't have the start of the next span, then use the end of the
2520 // predicates, but that means we miss comments.
2521 let len = where_clause.predicates.len();
2522 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2523 let span_end = span_end.unwrap_or(end_of_preds);
2524 let items = itemize_list(
2526 where_clause.predicates.iter(),
2529 |pred| pred.span().lo(),
2530 |pred| pred.span().hi(),
2531 |pred| pred.rewrite(context, clause_shape),
2536 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2537 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2538 SeparatorTactic::Never
2540 context.config.trailing_comma()
2543 // shape should be vertical only and only if we have `where_single_line` option enabled
2544 // and the number of items of the where clause is equal to 1
2545 let shape_tactic = if where_single_line {
2546 DefinitiveListTactic::Horizontal
2548 DefinitiveListTactic::Vertical
2551 let fmt = ListFormatting {
2552 tactic: shape_tactic,
2554 trailing_separator: comma_tactic,
2555 separator_place: SeparatorPlace::Back,
2556 shape: clause_shape,
2557 ends_with_newline: true,
2558 preserve_newline: true,
2559 config: context.config,
2561 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2563 let comment_separator = |comment: &str, shape: Shape| if comment.is_empty() {
2566 format!("\n{}", shape.indent.to_string(context.config))
2568 let newline_before_where = comment_separator(&comment_before, shape);
2569 let newline_after_where = comment_separator(&comment_after, clause_shape);
2572 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2573 && comment_after.is_empty() && !preds_str.contains('\n')
2574 && 6 + preds_str.len() <= shape.width || where_single_line
2578 format!("\n{}", clause_shape.indent.to_string(context.config))
2581 "{}{}{}where{}{}{}{}",
2584 newline_before_where,
2585 newline_after_where,
2592 fn rewrite_where_clause(
2593 context: &RewriteContext,
2594 where_clause: &ast::WhereClause,
2595 brace_style: BraceStyle,
2599 span_end: Option<BytePos>,
2600 span_end_before_where: BytePos,
2601 where_clause_option: WhereClauseOption,
2602 is_args_multi_line: bool,
2603 ) -> Option<String> {
2604 if where_clause.predicates.is_empty() {
2605 return Some(String::new());
2608 if context.config.indent_style() == IndentStyle::Block {
2609 return rewrite_where_clause_rfc_style(
2615 span_end_before_where,
2616 where_clause_option,
2621 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2623 let offset = match context.config.indent_style() {
2624 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2625 // 6 = "where ".len()
2626 IndentStyle::Visual => shape.indent + extra_indent + 6,
2628 // FIXME: if indent_style != Visual, then the budgets below might
2629 // be out by a char or two.
2631 let budget = context.config.max_width() - offset.width();
2632 let span_start = where_clause.predicates[0].span().lo();
2633 // If we don't have the start of the next span, then use the end of the
2634 // predicates, but that means we miss comments.
2635 let len = where_clause.predicates.len();
2636 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2637 let span_end = span_end.unwrap_or(end_of_preds);
2638 let items = itemize_list(
2640 where_clause.predicates.iter(),
2643 |pred| pred.span().lo(),
2644 |pred| pred.span().hi(),
2645 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2650 let item_vec = items.collect::<Vec<_>>();
2651 // FIXME: we don't need to collect here
2652 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2654 let mut comma_tactic = context.config.trailing_comma();
2655 // Kind of a hack because we don't usually have trailing commas in where clauses.
2656 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2657 comma_tactic = SeparatorTactic::Never;
2660 let fmt = ListFormatting {
2663 trailing_separator: comma_tactic,
2664 separator_place: SeparatorPlace::Back,
2665 shape: Shape::legacy(budget, offset),
2666 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2667 preserve_newline: true,
2668 config: context.config,
2670 let preds_str = write_list(&item_vec, &fmt)?;
2672 let end_length = if terminator == "{" {
2673 // If the brace is on the next line we don't need to count it otherwise it needs two
2676 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2677 BraceStyle::PreferSameLine => 2,
2679 } else if terminator == "=" {
2684 if density == Density::Tall || preds_str.contains('\n')
2685 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2689 (shape.indent + extra_indent).to_string(context.config),
2693 Some(format!(" where {}", preds_str))
2697 fn missing_span_before_after_where(
2698 before_item_span_end: BytePos,
2699 where_clause: &ast::WhereClause,
2701 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2703 let pos_after_where = where_clause.span.lo() + BytePos(5);
2704 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2705 (missing_span_before, missing_span_after)
2708 fn rewrite_comments_before_after_where(
2709 context: &RewriteContext,
2710 span_before_where: Span,
2711 span_after_where: Span,
2713 ) -> Option<(String, String)> {
2714 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2715 let after_comment = rewrite_missing_comment(
2717 shape.block_indent(context.config.tab_spaces()),
2720 Some((before_comment, after_comment))
2723 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2724 format!("{}{}{}", format_visibility(vis), item_name, ident)
2727 #[derive(PartialEq, Eq)]
2735 context: &RewriteContext,
2736 generics: &ast::Generics,
2737 brace_style: BraceStyle,
2738 brace_pos: BracePos,
2742 ) -> Option<String> {
2743 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2744 let mut result = rewrite_generics(context, generics, shape, span)?;
2746 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2747 let budget = context.budget(last_line_used_width(&result, offset.width()));
2748 let mut option = WhereClauseOption::snuggled(&result);
2749 if brace_pos == BracePos::None {
2750 option.suppress_comma = true;
2752 // If the generics are not parameterized then generics.span.hi() == 0,
2753 // so we use span.lo(), which is the position after `struct Foo`.
2754 let span_end_before_where = if generics.is_parameterized() {
2759 let where_clause_str = rewrite_where_clause(
2761 &generics.where_clause,
2763 Shape::legacy(budget, offset.block_only()),
2767 span_end_before_where,
2771 result.push_str(&where_clause_str);
2772 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2773 || (generics.where_clause.predicates.is_empty()
2774 && trimmed_last_line_width(&result) == 1)
2776 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2777 || brace_style != BraceStyle::AlwaysNextLine
2779 if brace_pos == BracePos::None {
2780 return Some(result);
2782 let total_used_width = last_line_used_width(&result, used_width);
2783 let remaining_budget = context.budget(total_used_width);
2784 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2785 // and hence we take the closer into account as well for one line budget.
2786 // We assume that the closer has the same length as the opener.
2787 let overhead = if brace_pos == BracePos::ForceSameLine {
2794 let forbid_same_line_brace = overhead > remaining_budget;
2795 if !forbid_same_line_brace && same_line_brace {
2799 result.push_str(&offset.block_only().to_string(context.config));
2806 impl Rewrite for ast::ForeignItem {
2807 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2808 let attrs_str = self.attrs.rewrite(context, shape)?;
2809 // Drop semicolon or it will be interpreted as comment.
2810 // FIXME: this may be a faulty span from libsyntax.
2811 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2813 let item_str = match self.node {
2814 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2819 &FnSig::new(fn_decl, generics, self.vis.clone()),
2823 ).map(|(s, _)| format!("{};", s))
2825 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2826 // FIXME(#21): we're dropping potential comments in between the
2827 // function keywords here.
2828 let vis = format_visibility(&self.vis);
2829 let mut_str = if is_mutable { "mut " } else { "" };
2830 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2832 let shape = shape.sub_width(1)?;
2833 ty.rewrite(context, shape).map(|ty_str| {
2834 // 1 = space between prefix and type.
2835 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2838 let nested_indent = shape.indent.block_indent(context.config);
2839 format!("\n{}", nested_indent.to_string(context.config))
2841 format!("{}{}{};", prefix, sep, ty_str)
2844 ast::ForeignItemKind::Ty => {
2845 let vis = format_visibility(&self.vis);
2846 Some(format!("{}type {};", vis, self.ident))
2850 let missing_span = if self.attrs.is_empty() {
2851 mk_sp(self.span.lo(), self.span.lo())
2853 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2855 combine_strs_with_missing_comments(