1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Formatting top-level items - functions, structs, enums, traits, impls.
16 use syntax::{abi, ast, ptr, symbol};
17 use syntax::ast::{CrateSugar, ImplItem};
18 use syntax::codemap::{BytePos, Span};
22 use codemap::{LineRangeUtils, SpanUtils};
23 use comment::{combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
24 recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented};
25 use config::{BraceStyle, Config, Density, IndentStyle, ReturnIndent};
26 use expr::{choose_rhs, format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs,
27 rewrite_call_inner, ExprType};
28 use lists::{definitive_tactic, itemize_list, write_list, DefinitiveListTactic, ListFormatting,
29 ListItem, ListTactic, Separator, SeparatorPlace, SeparatorTactic};
30 use rewrite::{Rewrite, RewriteContext};
31 use shape::{Indent, Shape};
32 use types::join_bounds;
33 use utils::{colon_spaces, contains_skip, end_typaram, first_line_width, format_abi,
34 format_constness, format_defaultness, format_mutability, format_unsafety,
35 format_visibility, is_attributes_extendable, last_line_contains_single_line_comment,
36 last_line_used_width, last_line_width, mk_sp, semicolon_for_expr, starts_with_newline,
37 stmt_expr, trim_newlines, trimmed_last_line_width};
38 use vertical::rewrite_with_alignment;
39 use visitor::FmtVisitor;
41 fn type_annotation_separator(config: &Config) -> &str {
42 colon_spaces(config.space_before_colon(), config.space_after_colon())
45 // Statements of the form
46 // let pat: ty = init;
47 impl Rewrite for ast::Local {
48 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
50 "Local::rewrite {:?} {} {:?}",
56 skip_out_of_file_lines_range!(context, self.span);
58 if contains_skip(&self.attrs) {
62 let attrs_str = self.attrs.rewrite(context, shape)?;
63 let mut result = if attrs_str.is_empty() {
66 combine_strs_with_missing_comments(
71 self.attrs.last().map(|a| a.span.hi()).unwrap(),
80 let pat_shape = shape.offset_left(4)?;
82 let pat_shape = pat_shape.sub_width(1)?;
83 let pat_str = self.pat.rewrite(context, pat_shape)?;
84 result.push_str(&pat_str);
86 // String that is placed within the assignment pattern and expression.
88 let mut infix = String::with_capacity(32);
90 if let Some(ref ty) = self.ty {
91 let separator = type_annotation_separator(context.config);
92 let indent = shape.indent + last_line_width(&result) + separator.len();
94 let budget = shape.width.checked_sub(indent.width() + 1)?;
95 let rewrite = ty.rewrite(context, Shape::legacy(budget, indent))?;
97 infix.push_str(separator);
98 infix.push_str(&rewrite);
101 if self.init.is_some() {
102 infix.push_str(" =");
108 result.push_str(&infix);
110 if let Some(ref ex) = self.init {
111 // 1 = trailing semicolon;
112 let nested_shape = shape.sub_width(1)?;
114 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
122 // TODO convert to using rewrite style rather than visitor
123 // TODO format modules in this style
126 keyword: &'static str,
127 abi: Cow<'static, str>,
128 vis: Option<&'a ast::Visibility>,
129 body: Vec<BodyElement<'a>>,
134 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
137 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
141 .map(|i| BodyElement::ForeignItem(i))
148 enum BodyElement<'a> {
149 // Stmt(&'a ast::Stmt),
150 // Field(&'a ast::Field),
151 // Variant(&'a ast::Variant),
152 // Item(&'a ast::Item),
153 ForeignItem(&'a ast::ForeignItem),
156 /// Represents a fn's signature.
157 pub struct FnSig<'a> {
158 decl: &'a ast::FnDecl,
159 generics: &'a ast::Generics,
161 constness: ast::Constness,
162 defaultness: ast::Defaultness,
163 unsafety: ast::Unsafety,
164 visibility: ast::Visibility,
169 decl: &'a ast::FnDecl,
170 generics: &'a ast::Generics,
171 vis: ast::Visibility,
177 constness: ast::Constness::NotConst,
178 defaultness: ast::Defaultness::Final,
179 unsafety: ast::Unsafety::Normal,
184 pub fn from_method_sig(
185 method_sig: &'a ast::MethodSig,
186 generics: &'a ast::Generics,
189 unsafety: method_sig.unsafety,
190 constness: method_sig.constness.node,
191 defaultness: ast::Defaultness::Final,
193 decl: &*method_sig.decl,
195 visibility: ast::Visibility::Inherited,
200 fn_kind: &'a visit::FnKind,
201 generics: &'a ast::Generics,
202 decl: &'a ast::FnDecl,
203 defualtness: ast::Defaultness,
206 visit::FnKind::ItemFn(_, unsafety, constness, abi, visibility, _) => FnSig {
210 constness: constness.node,
211 defaultness: defualtness,
213 visibility: visibility.clone(),
215 visit::FnKind::Method(_, method_sig, vis, _) => {
216 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
217 fn_sig.defaultness = defualtness;
218 if let Some(vis) = vis {
219 fn_sig.visibility = vis.clone();
227 fn to_str(&self, context: &RewriteContext) -> String {
228 let mut result = String::with_capacity(128);
229 // Vis defaultness constness unsafety abi.
230 result.push_str(&*format_visibility(&self.visibility));
231 result.push_str(format_defaultness(self.defaultness));
232 result.push_str(format_constness(self.constness));
233 result.push_str(format_unsafety(self.unsafety));
234 result.push_str(&format_abi(
236 context.config.force_explicit_abi(),
243 impl<'a> FmtVisitor<'a> {
244 fn format_item(&mut self, item: Item) {
245 self.buffer.push_str(&item.abi);
247 let snippet = self.snippet(item.span);
248 let brace_pos = snippet.find_uncommented("{").unwrap();
250 self.buffer.push_str("{");
251 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
252 // FIXME: this skips comments between the extern keyword and the opening
254 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
255 self.block_indent = self.block_indent.block_indent(self.config);
257 if item.body.is_empty() {
258 self.format_missing_no_indent(item.span.hi() - BytePos(1));
259 self.block_indent = self.block_indent.block_unindent(self.config);
262 .push_str(&self.block_indent.to_string(self.config));
264 for item in &item.body {
265 self.format_body_element(item);
268 self.block_indent = self.block_indent.block_unindent(self.config);
269 self.format_missing_with_indent(item.span.hi() - BytePos(1));
273 self.buffer.push_str("}");
274 self.last_pos = item.span.hi();
277 fn format_body_element(&mut self, element: &BodyElement) {
279 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
283 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
284 let item = Item::from_foreign_mod(fm, span, self.config);
285 self.format_item(item);
289 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
290 let rewrite = item.rewrite(&self.get_context(), self.shape());
291 self.push_rewrite(item.span(), rewrite);
292 self.last_pos = item.span.hi();
302 ) -> Option<String> {
303 let context = self.get_context();
306 !is_empty_block(block, self.codemap) || !context.config.fn_empty_single_line();
307 let mut newline_brace =
308 newline_for_brace(self.config, &fn_sig.generics.where_clause, has_body);
310 let (mut result, force_newline_brace) =
311 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
314 if self.config.brace_style() == BraceStyle::AlwaysNextLine || force_newline_brace
315 || last_line_width(&result) + 2 > self.shape().width
317 newline_brace = true;
318 } else if !result.contains('\n') {
319 newline_brace = false;
322 // Prepare for the function body by possibly adding a newline and
324 // FIXME we'll miss anything between the end of the signature and the
325 // start of the body, but we need more spans from the compiler to solve
329 result.push_str(&indent.to_string(self.config));
334 self.single_line_fn(&result, block).or_else(|| Some(result))
337 pub fn rewrite_required_fn(
341 sig: &ast::MethodSig,
342 generics: &ast::Generics,
344 ) -> Option<String> {
345 // Drop semicolon or it will be interpreted as comment.
346 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
347 let context = self.get_context();
349 let (mut result, _) = rewrite_fn_base(
353 &FnSig::from_method_sig(sig, generics),
359 // Re-attach semicolon
365 fn single_line_fn(&self, fn_str: &str, block: &ast::Block) -> Option<String> {
366 if fn_str.contains('\n') {
370 let codemap = self.get_context().codemap;
372 if self.config.fn_empty_single_line() && is_empty_block(block, codemap)
373 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
375 return Some(format!("{}{{}}", fn_str));
378 if self.config.fn_single_line() && is_simple_block_stmt(block, codemap) {
380 if let Some(stmt) = block.stmts.first() {
381 match stmt_expr(stmt) {
383 let suffix = if semicolon_for_expr(&self.get_context(), e) {
389 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
391 .or_else(|| Some(self.snippet(e.span)))
393 None => stmt.rewrite(&self.get_context(), self.shape()),
400 if let Some(res) = rewrite {
401 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
402 if !res.contains('\n') && width <= self.config.max_width() {
403 return Some(format!("{}{{ {} }}", fn_str, res));
411 pub fn visit_static(&mut self, static_parts: &StaticParts) {
412 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
413 self.push_rewrite(static_parts.span, rewrite);
416 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
417 let is_tuple = struct_parts.def.is_tuple();
418 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
419 .map(|s| if is_tuple { s + ";" } else { s });
420 self.push_rewrite(struct_parts.span, rewrite);
426 vis: &ast::Visibility,
427 enum_def: &ast::EnumDef,
428 generics: &ast::Generics,
431 let enum_header = format_header("enum ", ident, vis);
432 self.buffer.push_str(&enum_header);
434 let enum_snippet = self.snippet(span);
435 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
436 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
437 let generics_str = format_generics(
440 self.config.brace_style(),
441 if enum_def.variants.is_empty() {
442 BracePos::ForceSameLine
447 mk_sp(span.lo(), body_start),
448 last_line_width(&enum_header),
450 self.buffer.push_str(&generics_str);
452 self.last_pos = body_start;
454 self.block_indent = self.block_indent.block_indent(self.config);
455 let variant_list = self.format_variant_list(enum_def, body_start, span.hi() - BytePos(1));
457 Some(ref body_str) => self.buffer.push_str(body_str),
458 None => if contains_comment(&enum_snippet[brace_pos..]) {
459 self.format_missing_no_indent(span.hi() - BytePos(1))
462 self.block_indent = self.block_indent.block_unindent(self.config);
464 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
466 .push_str(&self.block_indent.to_string(self.config));
468 self.buffer.push_str("}");
469 self.last_pos = span.hi();
472 // Format the body of an enum definition
473 fn format_variant_list(
475 enum_def: &ast::EnumDef,
478 ) -> Option<String> {
479 if enum_def.variants.is_empty() {
482 let mut result = String::with_capacity(1024);
484 let indentation = self.block_indent.to_string(self.config);
485 result.push_str(&indentation);
487 let itemize_list_with = |one_line_width: usize| {
490 enum_def.variants.iter(),
493 |f| if !f.node.attrs.is_empty() {
494 f.node.attrs[0].span.lo()
499 |f| self.format_variant(f, one_line_width),
505 let mut items: Vec<_> = itemize_list_with(self.config.struct_variant_width());
506 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
507 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains("\n"));
508 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains("\n"));
509 if has_multiline_variant && has_single_line_variant {
510 items = itemize_list_with(0);
513 let shape = self.shape().sub_width(2).unwrap();
514 let fmt = ListFormatting {
515 tactic: DefinitiveListTactic::Vertical,
517 trailing_separator: self.config.trailing_comma(),
518 separator_place: SeparatorPlace::Back,
520 ends_with_newline: true,
521 preserve_newline: true,
525 let list = write_list(&items, &fmt)?;
526 result.push_str(&list);
531 // Variant of an enum.
532 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
533 if contains_skip(&field.node.attrs) {
534 let lo = field.node.attrs[0].span.lo();
535 let span = mk_sp(lo, field.span.hi());
536 return Some(self.snippet(span));
539 let context = self.get_context();
540 let indent = self.block_indent;
541 let shape = self.shape();
542 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
547 .map_or(field.span.lo(), |attr| attr.span.hi());
548 let span = mk_sp(lo, field.span.lo());
550 let variant_body = match field.node.data {
551 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => {
552 // FIXME: Should limit the width, as we have a trailing comma
555 &StructParts::from_variant(field),
557 Some(one_line_width),
560 ast::VariantData::Unit(..) => if let Some(ref expr) = field.node.disr_expr {
561 let lhs = format!("{} =", field.node.name);
563 rewrite_assign_rhs(&context, lhs, &**expr, shape.sub_width(1)?)?
565 field.node.name.to_string()
569 let attrs_extendable = attrs_str.is_empty()
570 || (context.config.attributes_on_same_line_as_variant()
571 && is_attributes_extendable(&attrs_str));
572 combine_strs_with_missing_comments(
584 context: &RewriteContext,
587 where_span_end: Option<BytePos>,
588 ) -> Option<String> {
589 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
590 let mut result = String::with_capacity(128);
591 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
592 let indent_str = offset.to_string(context.config);
593 let sep = format!("\n{}", &indent_str);
594 result.push_str(&ref_and_type);
596 let where_budget = if result.contains('\n') {
597 context.config.max_width()
599 context.budget(last_line_width(&result))
601 let option = WhereClauseOption::snuggled(&ref_and_type);
602 let where_clause_str = rewrite_where_clause(
604 &generics.where_clause,
605 context.config.brace_style(),
606 Shape::legacy(where_budget, offset.block_only()),
607 context.config.where_density(),
615 // If there is no where clause, we may have missing comments between the trait name and
616 // the opening brace.
617 if generics.where_clause.predicates.is_empty() {
618 if let Some(hi) = where_span_end {
619 match recover_missing_comment_in_span(
620 mk_sp(self_ty.span.hi(), hi),
621 Shape::indented(offset, context.config),
623 last_line_width(&result),
625 Some(ref missing_comment) if !missing_comment.is_empty() => {
626 result.push_str(missing_comment);
633 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
634 result.push_str(&where_clause_str);
635 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
636 result.push_str(&format!("{}{{{}}}", &sep, &sep));
638 result.push_str(" {}");
643 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
645 let width = offset.block_indent + context.config.tab_spaces() - 1;
646 let where_indent = Indent::new(0, width);
647 result.push_str(&where_indent.to_string(context.config));
649 result.push_str(&where_clause_str);
651 match context.config.brace_style() {
652 _ if last_line_contains_single_line_comment(&result) => result.push_str(&sep),
653 BraceStyle::AlwaysNextLine => result.push_str(&sep),
654 BraceStyle::PreferSameLine => result.push(' '),
655 BraceStyle::SameLineWhere => if !where_clause_str.is_empty() {
656 result.push_str(&sep);
664 let snippet = context.snippet(item.span);
665 let open_pos = snippet.find_uncommented("{")? + 1;
667 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
668 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
669 visitor.block_indent = offset.block_only().block_indent(context.config);
670 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
672 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
674 visitor.visit_impl_item(item);
677 visitor.format_missing(item.span.hi() - BytePos(1));
679 let inner_indent_str = visitor.block_indent.to_string(context.config);
680 let outer_indent_str = offset.block_only().to_string(context.config);
683 result.push_str(&inner_indent_str);
684 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
686 result.push_str(&outer_indent_str);
689 if result.ends_with('{') {
690 result.push_str(&sep);
700 fn is_impl_single_line(
701 context: &RewriteContext,
704 where_clause_str: &str,
707 let snippet = context.snippet(item.span);
708 let open_pos = snippet.find_uncommented("{")? + 1;
711 context.config.impl_empty_single_line() && items.is_empty() && !result.contains('\n')
712 && result.len() + where_clause_str.len() <= context.config.max_width()
713 && !contains_comment(&snippet[open_pos..]),
717 fn format_impl_ref_and_type(
718 context: &RewriteContext,
721 ) -> Option<String> {
722 if let ast::ItemKind::Impl(
732 let mut result = String::with_capacity(128);
734 result.push_str(&format_visibility(&item.vis));
735 result.push_str(format_defaultness(defaultness));
736 result.push_str(format_unsafety(unsafety));
737 result.push_str("impl");
739 let lo = context.codemap.span_after(item.span, "impl");
740 let hi = match *trait_ref {
741 Some(ref tr) => tr.path.span.lo(),
742 None => self_ty.span.lo(),
744 let shape = generics_shape_from_config(
746 Shape::indented(offset + last_line_width(&result), context.config),
749 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
751 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
753 let polarity_str = if polarity == ast::ImplPolarity::Negative {
759 if let Some(ref trait_ref) = *trait_ref {
760 let result_len = result.len();
761 if let Some(trait_ref_str) = rewrite_trait_ref(
770 result.push_str(&trait_ref_str);
773 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
774 result.push_str(&rewrite_trait_ref(
785 result.push_str(&generics_str);
788 // Try to put the self type in a single line.
790 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
791 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
792 // If there is no where clause adapt budget for type formatting to take space and curly
793 // brace into account.
794 match context.config.brace_style() {
795 BraceStyle::AlwaysNextLine => 0,
801 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
802 // 1 = space before the type.
803 let budget = context.budget(used_space + 1);
804 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
805 if !self_ty_str.contains('\n') {
806 if trait_ref.is_some() {
807 result.push_str(" for ");
811 result.push_str(&self_ty_str);
816 // Couldn't fit the self type on a single line, put it on a new line.
818 // Add indentation of one additional tab.
819 let new_line_offset = offset.block_indent(context.config);
820 result.push_str(&new_line_offset.to_string(context.config));
821 if trait_ref.is_some() {
822 result.push_str("for ");
824 let budget = context.budget(last_line_width(&result));
825 let type_offset = match context.config.indent_style() {
826 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
827 IndentStyle::Block => new_line_offset,
829 result.push_str(&*self_ty
830 .rewrite(context, Shape::legacy(budget, type_offset))?);
837 fn rewrite_trait_ref(
838 context: &RewriteContext,
839 trait_ref: &ast::TraitRef,
845 ) -> Option<String> {
846 // 1 = space between generics and trait_ref
847 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
848 let shape = Shape::indented(offset + used_space, context.config);
849 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
850 if !(retry && trait_ref_str.contains('\n')) {
859 // We could not make enough space for trait_ref, so put it on new line.
861 let offset = offset.block_indent(context.config);
862 let shape = Shape::indented(offset, context.config);
863 let trait_ref_str = trait_ref.rewrite(context, shape)?;
867 &offset.to_string(context.config),
876 pub struct StructParts<'a> {
879 vis: &'a ast::Visibility,
880 def: &'a ast::VariantData,
881 generics: Option<&'a ast::Generics>,
885 impl<'a> StructParts<'a> {
886 fn format_header(&self) -> String {
887 format_header(self.prefix, self.ident, self.vis)
890 fn from_variant(variant: &'a ast::Variant) -> Self {
893 ident: variant.node.name,
894 vis: &ast::Visibility::Inherited,
895 def: &variant.node.data,
901 pub fn from_item(item: &'a ast::Item) -> Self {
902 let (prefix, def, generics) = match item.node {
903 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
904 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
912 generics: Some(generics),
919 context: &RewriteContext,
920 struct_parts: &StructParts,
922 one_line_width: Option<usize>,
923 ) -> Option<String> {
924 match *struct_parts.def {
925 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
926 ast::VariantData::Tuple(ref fields, _) => {
927 format_tuple_struct(context, struct_parts, fields, offset)
929 ast::VariantData::Struct(ref fields, _) => {
930 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
935 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
936 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
939 let mut result = String::with_capacity(128);
940 let header = format!(
942 format_visibility(&item.vis),
943 format_unsafety(unsafety),
947 result.push_str(&header);
949 let body_lo = context.codemap.span_after(item.span, "{");
951 let shape = Shape::indented(offset, context.config);
953 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
954 result.push_str(&generics_str);
956 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
957 if !type_param_bounds.is_empty() {
958 let ident_hi = context
960 .span_after(item.span, &format!("{}", item.ident));
961 let bound_hi = type_param_bounds.last().unwrap().span().hi();
962 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
963 if contains_comment(&snippet) {
967 let trait_bound_str = rewrite_trait_bounds(
970 Shape::indented(offset, context.config),
972 // If the trait, generics, and trait bound cannot fit on the same line,
973 // put the trait bounds on an indented new line
974 if offset.width() + last_line_width(&result) + trait_bound_str.len()
975 > context.config.comment_width()
978 let trait_indent = offset.block_only().block_indent(context.config);
979 result.push_str(&trait_indent.to_string(context.config));
981 result.push_str(&trait_bound_str);
983 let has_body = !trait_items.is_empty();
985 let where_density = if (context.config.where_density() == Density::Compressed
986 && (!result.contains('\n') || context.config.indent_style() == IndentStyle::Block))
987 || (context.config.indent_style() == IndentStyle::Block && result.is_empty())
988 || (context.config.where_density() == Density::CompressedIfEmpty && !has_body
989 && !result.contains('\n'))
996 let where_budget = context.budget(last_line_width(&result));
997 let pos_before_where = if type_param_bounds.is_empty() {
998 generics.where_clause.span.lo()
1000 type_param_bounds[type_param_bounds.len() - 1].span().hi()
1002 let option = WhereClauseOption::snuggled(&generics_str);
1003 let where_clause_str = rewrite_where_clause(
1005 &generics.where_clause,
1006 context.config.brace_style(),
1007 Shape::legacy(where_budget, offset.block_only()),
1015 // If the where clause cannot fit on the same line,
1016 // put the where clause on a new line
1017 if !where_clause_str.contains('\n')
1018 && last_line_width(&result) + where_clause_str.len() + offset.width()
1019 > context.config.comment_width()
1022 let width = offset.block_indent + context.config.tab_spaces() - 1;
1023 let where_indent = Indent::new(0, width);
1024 result.push_str(&where_indent.to_string(context.config));
1026 result.push_str(&where_clause_str);
1028 if generics.where_clause.predicates.is_empty() {
1029 let item_snippet = context.snippet(item.span);
1030 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1032 let comment_hi = body_lo - BytePos(1);
1033 let comment_lo = item.span.lo() + BytePos(lo as u32);
1034 if comment_lo < comment_hi {
1035 match recover_missing_comment_in_span(
1036 mk_sp(comment_lo, comment_hi),
1037 Shape::indented(offset, context.config),
1039 last_line_width(&result),
1041 Some(ref missing_comment) if !missing_comment.is_empty() => {
1042 result.push_str(missing_comment);
1050 match context.config.brace_style() {
1051 _ if last_line_contains_single_line_comment(&result) => {
1053 result.push_str(&offset.to_string(context.config));
1055 BraceStyle::AlwaysNextLine => {
1057 result.push_str(&offset.to_string(context.config));
1059 BraceStyle::PreferSameLine => result.push(' '),
1060 BraceStyle::SameLineWhere => if !where_clause_str.is_empty()
1061 && (!trait_items.is_empty() || result.contains('\n'))
1064 result.push_str(&offset.to_string(context.config));
1071 let snippet = context.snippet(item.span);
1072 let open_pos = snippet.find_uncommented("{")? + 1;
1074 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1075 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
1076 visitor.block_indent = offset.block_only().block_indent(context.config);
1077 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1079 for item in trait_items {
1080 visitor.visit_trait_item(item);
1083 visitor.format_missing(item.span.hi() - BytePos(1));
1085 let inner_indent_str = visitor.block_indent.to_string(context.config);
1086 let outer_indent_str = offset.block_only().to_string(context.config);
1089 result.push_str(&inner_indent_str);
1090 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1092 result.push_str(&outer_indent_str);
1093 } else if result.contains('\n') {
1104 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1105 let header_str = format_header(p.prefix, p.ident, p.vis);
1106 let generics_str = if let Some(generics) = p.generics {
1107 let hi = if generics.where_clause.predicates.is_empty() {
1110 generics.where_clause.span.hi()
1115 context.config.brace_style(),
1118 mk_sp(generics.span.lo(), hi),
1119 last_line_width(&header_str),
1124 Some(format!("{}{};", header_str, generics_str))
1127 pub fn format_struct_struct(
1128 context: &RewriteContext,
1129 struct_parts: &StructParts,
1130 fields: &[ast::StructField],
1132 one_line_width: Option<usize>,
1133 ) -> Option<String> {
1134 let mut result = String::with_capacity(1024);
1135 let span = struct_parts.span;
1137 let header_str = struct_parts.format_header();
1138 result.push_str(&header_str);
1140 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1141 let body_lo = context.codemap.span_after(span, "{");
1143 let generics_str = match struct_parts.generics {
1144 Some(g) => format_generics(
1147 context.config.brace_style(),
1148 if fields.is_empty() {
1149 BracePos::ForceSameLine
1154 mk_sp(header_hi, body_lo),
1155 last_line_width(&result),
1158 // 3 = ` {}`, 2 = ` {`.
1159 let overhead = if fields.is_empty() { 3 } else { 2 };
1160 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1161 || context.config.max_width() < overhead + result.len()
1163 format!("\n{}{{", offset.block_only().to_string(context.config))
1170 let overhead = if fields.is_empty() { 1 } else { 0 };
1171 let total_width = result.len() + generics_str.len() + overhead;
1172 if !generics_str.is_empty() && !generics_str.contains('\n')
1173 && total_width > context.config.max_width()
1176 result.push_str(&offset.to_string(context.config));
1177 result.push_str(generics_str.trim_left());
1179 result.push_str(&generics_str);
1182 if fields.is_empty() {
1183 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1184 if snippet.trim().is_empty() {
1186 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1188 result.push_str(snippet.trim_right());
1190 result.push_str(&offset.to_string(context.config));
1192 result.push_str(&snippet);
1195 return Some(result);
1199 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1200 let one_line_budget =
1201 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1203 let items_str = rewrite_with_alignment(
1206 Shape::indented(offset, context.config).sub_width(1)?,
1207 mk_sp(body_lo, span.hi()),
1211 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget {
1212 Some(format!("{} {} }}", result, items_str))
1218 .block_indent(context.config)
1219 .to_string(context.config),
1221 offset.to_string(context.config)
1226 /// Returns a bytepos that is after that of `(` in `pub(..)`. If the given visibility does not
1227 /// contain `pub(..)`, then return the `lo` of the `defualt_span`. Yeah, but for what? Well, we need
1228 /// to bypass the `(` in the visibility when creating a span of tuple's body or fn's args.
1229 fn get_bytepos_after_visibility(
1230 context: &RewriteContext,
1231 vis: &ast::Visibility,
1236 ast::Visibility::Crate(s, CrateSugar::PubCrate) => context
1238 .span_after(mk_sp(s.hi(), default_span.hi()), terminator),
1239 ast::Visibility::Crate(s, CrateSugar::JustCrate) => s.hi(),
1240 ast::Visibility::Restricted { ref path, .. } => path.span.hi(),
1241 _ => default_span.lo(),
1245 fn format_tuple_struct(
1246 context: &RewriteContext,
1247 struct_parts: &StructParts,
1248 fields: &[ast::StructField],
1250 ) -> Option<String> {
1251 let mut result = String::with_capacity(1024);
1252 let span = struct_parts.span;
1254 let header_str = struct_parts.format_header();
1255 result.push_str(&header_str);
1257 let body_lo = if fields.is_empty() {
1258 let lo = get_bytepos_after_visibility(context, struct_parts.vis, span, ")");
1259 context.codemap.span_after(mk_sp(lo, span.hi()), "(")
1263 let body_hi = if fields.is_empty() {
1264 context.codemap.span_after(mk_sp(body_lo, span.hi()), ")")
1266 // This is a dirty hack to work around a missing `)` from the span of the last field.
1267 let last_arg_span = fields[fields.len() - 1].span;
1268 if context.snippet(last_arg_span).ends_with(')') {
1273 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1277 let where_clause_str = match struct_parts.generics {
1279 let budget = context.budget(last_line_width(&header_str));
1280 let shape = Shape::legacy(budget, offset);
1281 let g_span = mk_sp(span.lo(), body_lo);
1282 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1283 result.push_str(&generics_str);
1285 let where_budget = context.budget(last_line_width(&result));
1286 let option = WhereClauseOption::new(true, false);
1287 rewrite_where_clause(
1289 &generics.where_clause,
1290 context.config.brace_style(),
1291 Shape::legacy(where_budget, offset.block_only()),
1292 Density::Compressed,
1300 None => "".to_owned(),
1303 if fields.is_empty() {
1305 let used_width = last_line_used_width(&result, offset.width()) + 3;
1306 if used_width > context.config.max_width() {
1308 result.push_str(&offset
1309 .block_indent(context.config)
1310 .to_string(context.config))
1313 let snippet = context.snippet(mk_sp(
1315 context.codemap.span_before(mk_sp(body_lo, span.hi()), ")"),
1317 if snippet.is_empty() {
1319 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1320 result.push_str(snippet.trim_right());
1322 result.push_str(&offset.to_string(context.config));
1324 result.push_str(&snippet);
1328 let shape = Shape::indented(offset, context.config);
1329 let fields = &fields.iter().map(|field| field).collect::<Vec<_>>()[..];
1330 let one_line_width = context.config.fn_call_width();
1331 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1334 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1335 && (result.contains('\n')
1336 || offset.block_indent + result.len() + where_clause_str.len() + 1
1337 > context.config.max_width())
1339 // We need to put the where clause on a new line, but we didn't
1340 // know that earlier, so the where clause will not be indented properly.
1342 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1343 .to_string(context.config));
1345 result.push_str(&where_clause_str);
1350 pub fn rewrite_type_alias(
1351 context: &RewriteContext,
1355 generics: &ast::Generics,
1356 vis: &ast::Visibility,
1358 ) -> Option<String> {
1359 let mut result = String::with_capacity(128);
1361 result.push_str(&format_visibility(vis));
1362 result.push_str("type ");
1363 result.push_str(&ident.to_string());
1366 let shape = Shape::indented(indent + result.len(), context.config).sub_width(2)?;
1367 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo());
1368 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1369 result.push_str(&generics_str);
1371 let where_budget = context.budget(last_line_width(&result));
1372 let option = WhereClauseOption::snuggled(&result);
1373 let where_clause_str = rewrite_where_clause(
1375 &generics.where_clause,
1376 context.config.brace_style(),
1377 Shape::legacy(where_budget, indent),
1378 context.config.where_density(),
1385 result.push_str(&where_clause_str);
1386 if where_clause_str.is_empty() {
1387 result.push_str(" = ");
1389 result.push_str(&format!("\n{}= ", indent.to_string(context.config)));
1392 let line_width = last_line_width(&result);
1393 // This checked_sub may fail as the extra space after '=' is not taken into account
1394 // In that case the budget is set to 0 which will make ty.rewrite retry on a new line
1395 let budget = context.budget(indent.width() + line_width + ";".len());
1396 let type_indent = indent + line_width;
1397 // Try to fit the type on the same line
1398 let ty_str = ty.rewrite(context, Shape::legacy(budget, type_indent))
1400 // The line was too short, try to put the type on the next line
1402 // Remove the space after '='
1404 let type_indent = indent.block_indent(context.config);
1406 result.push_str(&type_indent.to_string(context.config));
1407 let budget = context.budget(type_indent.width() + ";".len());
1408 ty.rewrite(context, Shape::legacy(budget, type_indent))
1410 result.push_str(&ty_str);
1411 result.push_str(";");
1415 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1417 if config.space_before_colon() { " " } else { "" },
1418 if config.space_after_colon() { " " } else { "" },
1422 pub fn rewrite_struct_field_prefix(
1423 context: &RewriteContext,
1424 field: &ast::StructField,
1425 ) -> Option<String> {
1426 let vis = format_visibility(&field.vis);
1427 let type_annotation_spacing = type_annotation_spacing(context.config);
1428 Some(match field.ident {
1429 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1430 None => format!("{}", vis),
1434 impl Rewrite for ast::StructField {
1435 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1436 rewrite_struct_field(context, self, shape, 0)
1440 pub fn rewrite_struct_field(
1441 context: &RewriteContext,
1442 field: &ast::StructField,
1444 lhs_max_width: usize,
1445 ) -> Option<String> {
1446 if contains_skip(&field.attrs) {
1447 return Some(context.snippet(mk_sp(field.attrs[0].span.lo(), field.span.hi())));
1450 let type_annotation_spacing = type_annotation_spacing(context.config);
1451 let prefix = rewrite_struct_field_prefix(context, field)?;
1453 let attrs_str = field.attrs.rewrite(context, shape)?;
1454 let attrs_extendable = attrs_str.is_empty()
1455 || (context.config.attributes_on_same_line_as_field()
1456 && is_attributes_extendable(&attrs_str));
1457 let missing_span = if field.attrs.is_empty() {
1458 mk_sp(field.span.lo(), field.span.lo())
1460 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1462 let mut spacing = String::from(if field.ident.is_some() {
1463 type_annotation_spacing.1
1467 // Try to put everything on a single line.
1468 let attr_prefix = combine_strs_with_missing_comments(
1476 let overhead = last_line_width(&attr_prefix);
1477 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1478 for _ in 0..lhs_offset {
1481 // In this extreme case we will be missing a space betweeen an attribute and a field.
1482 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1485 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1486 let mut orig_ty = field.ty.rewrite(context, ty_shape);
1487 if let Some(ref ty) = orig_ty {
1488 if !ty.contains('\n') {
1489 return Some(attr_prefix + &spacing + ty);
1493 // We must use multiline. We are going to put attributes and a field on different lines.
1495 let rhs_shape = shape.offset_left(last_line_width(&prefix) + 1)?;
1496 orig_ty = field.ty.rewrite(context, rhs_shape);
1497 let field_str = if prefix.is_empty() {
1500 prefix + &choose_rhs(context, &*field.ty, rhs_shape, orig_ty)?
1502 combine_strs_with_missing_comments(context, &attrs_str, &field_str, missing_span, shape, false)
1505 pub struct StaticParts<'a> {
1507 vis: &'a ast::Visibility,
1510 mutability: ast::Mutability,
1511 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1515 impl<'a> StaticParts<'a> {
1516 pub fn from_item(item: &'a ast::Item) -> Self {
1517 let (prefix, ty, mutability, expr) = match item.node {
1518 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1519 ast::ItemKind::Const(ref ty, ref expr) => {
1520 ("const", ty, ast::Mutability::Immutable, expr)
1522 _ => unreachable!(),
1529 mutability: mutability,
1530 expr_opt: Some(expr),
1535 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1536 let (ty, expr_opt) = match ti.node {
1537 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1538 _ => unreachable!(),
1542 vis: &ast::Visibility::Inherited,
1545 mutability: ast::Mutability::Immutable,
1546 expr_opt: expr_opt.as_ref(),
1551 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1552 let (ty, expr) = match ii.node {
1553 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1554 _ => unreachable!(),
1561 mutability: ast::Mutability::Immutable,
1562 expr_opt: Some(expr),
1569 context: &RewriteContext,
1570 static_parts: &StaticParts,
1572 ) -> Option<String> {
1573 let colon = colon_spaces(
1574 context.config.space_before_colon(),
1575 context.config.space_after_colon(),
1577 let prefix = format!(
1579 format_visibility(static_parts.vis),
1580 static_parts.prefix,
1581 format_mutability(static_parts.mutability),
1587 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1588 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1590 if let Some(expr) = static_parts.expr_opt {
1591 let lhs = format!("{}{} =", prefix, ty_str);
1593 let remaining_width = context.budget(offset.block_indent + 1);
1598 Shape::legacy(remaining_width, offset.block_only()),
1600 recover_comment_removed(res, static_parts.span, context)
1602 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1604 Some(format!("{}{};", prefix, ty_str))
1608 pub fn rewrite_associated_type(
1610 ty_opt: Option<&ptr::P<ast::Ty>>,
1611 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1612 context: &RewriteContext,
1614 ) -> Option<String> {
1615 let prefix = format!("type {}", ident);
1617 let type_bounds_str = if let Some(ref bounds) = ty_param_bounds_opt {
1619 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1620 let bound_str = bounds
1622 .map(|ty_bound| ty_bound.rewrite(context, shape))
1623 .collect::<Option<Vec<_>>>()?;
1624 if !bounds.is_empty() {
1625 format!(": {}", join_bounds(context, shape, &bound_str))
1633 if let Some(ty) = ty_opt {
1635 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1636 let lhs = format!("{}{} =", prefix, type_bounds_str);
1637 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1639 Some(format!("{}{};", prefix, type_bounds_str))
1643 pub fn rewrite_associated_impl_type(
1645 defaultness: ast::Defaultness,
1646 ty_opt: Option<&ptr::P<ast::Ty>>,
1647 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1648 context: &RewriteContext,
1650 ) -> Option<String> {
1651 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1654 ast::Defaultness::Default => Some(format!("default {}", result)),
1659 impl Rewrite for ast::FunctionRetTy {
1660 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1662 ast::FunctionRetTy::Default(_) => Some(String::new()),
1663 ast::FunctionRetTy::Ty(ref ty) => {
1664 let inner_width = shape.width.checked_sub(3)?;
1665 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1666 .map(|r| format!("-> {}", r))
1672 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1674 ast::TyKind::Infer => {
1675 let original = context.snippet(ty.span);
1682 impl Rewrite for ast::Arg {
1683 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1684 if is_named_arg(self) {
1685 let mut result = self.pat
1686 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1688 if !is_empty_infer(context, &*self.ty) {
1689 if context.config.space_before_colon() {
1690 result.push_str(" ");
1692 result.push_str(":");
1693 if context.config.space_after_colon() {
1694 result.push_str(" ");
1696 let overhead = last_line_width(&result);
1697 let max_width = shape.width.checked_sub(overhead)?;
1698 let ty_str = self.ty
1699 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1700 result.push_str(&ty_str);
1705 self.ty.rewrite(context, shape)
1710 fn rewrite_explicit_self(
1711 explicit_self: &ast::ExplicitSelf,
1713 context: &RewriteContext,
1714 ) -> Option<String> {
1715 match explicit_self.node {
1716 ast::SelfKind::Region(lt, m) => {
1717 let mut_str = format_mutability(m);
1720 let lifetime_str = l.rewrite(
1722 Shape::legacy(context.config.max_width(), Indent::empty()),
1724 Some(format!("&{} {}self", lifetime_str, mut_str))
1726 None => Some(format!("&{}self", mut_str)),
1729 ast::SelfKind::Explicit(ref ty, _) => {
1730 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1732 let mutability = explicit_self_mutability(&args[0]);
1733 let type_str = ty.rewrite(
1735 Shape::legacy(context.config.max_width(), Indent::empty()),
1740 format_mutability(mutability),
1744 ast::SelfKind::Value(_) => {
1745 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1747 let mutability = explicit_self_mutability(&args[0]);
1749 Some(format!("{}self", format_mutability(mutability)))
1754 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1755 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1756 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1757 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1764 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1765 if is_named_arg(arg) {
1772 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1774 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1775 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1776 _ => arg.ty.span.hi(),
1780 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1781 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1782 ident.node != symbol::keywords::Invalid.ident()
1788 // Return type is (result, force_new_line_for_brace)
1790 context: &RewriteContext,
1795 newline_brace: bool,
1797 ) -> Option<(String, bool)> {
1798 let mut force_new_line_for_brace = false;
1800 let where_clause = &fn_sig.generics.where_clause;
1802 let mut result = String::with_capacity(1024);
1803 result.push_str(&fn_sig.to_str(context));
1806 result.push_str("fn ");
1807 result.push_str(&ident.to_string());
1810 let overhead = if has_body && !newline_brace {
1817 let used_width = last_line_used_width(&result, indent.width());
1818 let one_line_budget = context.budget(used_width + overhead);
1820 width: one_line_budget,
1824 let fd = fn_sig.decl;
1825 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1826 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1827 result.push_str(&generics_str);
1829 let snuggle_angle_bracket = generics_str
1832 .map_or(false, |l| l.trim_left().len() == 1);
1834 // Note that the width and indent don't really matter, we'll re-layout the
1835 // return type later anyway.
1836 let ret_str = fd.output
1837 .rewrite(context, Shape::indented(indent, context.config))?;
1839 let multi_line_ret_str = ret_str.contains('\n');
1840 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1843 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1854 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1860 // Check if vertical layout was forced.
1861 if one_line_budget == 0 {
1862 if snuggle_angle_bracket {
1864 } else if context.config.fn_args_paren_newline() {
1866 result.push_str(&arg_indent.to_string(context.config));
1867 if context.config.indent_style() == IndentStyle::Visual {
1868 arg_indent = arg_indent + 1; // extra space for `(`
1872 result.push_str("(");
1873 if context.config.indent_style() == IndentStyle::Visual {
1875 result.push_str(&arg_indent.to_string(context.config));
1881 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1882 && result.ends_with('(')
1887 // Skip `pub(crate)`.
1888 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1889 // A conservative estimation, to goal is to be over all parens in generics
1890 let args_start = fn_sig
1894 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1895 let args_end = if fd.inputs.is_empty() {
1898 .span_after(mk_sp(args_start, span.hi()), ")")
1900 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1901 context.codemap.span_after(last_span, ")")
1903 let args_span = mk_sp(
1906 .span_after(mk_sp(args_start, span.hi()), "("),
1909 let arg_str = rewrite_args(
1912 fd.get_self().as_ref(),
1919 generics_str.contains('\n'),
1922 let put_args_in_block = match context.config.indent_style() {
1923 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1925 } && !fd.inputs.is_empty();
1927 let mut args_last_line_contains_comment = false;
1928 if put_args_in_block {
1929 arg_indent = indent.block_indent(context.config);
1931 result.push_str(&arg_indent.to_string(context.config));
1932 result.push_str(&arg_str);
1934 result.push_str(&indent.to_string(context.config));
1937 result.push_str(&arg_str);
1938 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1939 // Put the closing brace on the next line if it overflows the max width.
1941 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1944 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1947 // If the last line of args contains comment, we cannot put the closing paren
1948 // on the same line.
1952 .map_or(false, |last_line| last_line.contains("//"))
1954 args_last_line_contains_comment = true;
1956 result.push_str(&arg_indent.to_string(context.config));
1962 if let ast::FunctionRetTy::Ty(..) = fd.output {
1963 let ret_should_indent = match context.config.indent_style() {
1964 // If our args are block layout then we surely must have space.
1965 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1966 _ if args_last_line_contains_comment => false,
1967 _ if result.contains('\n') || multi_line_ret_str => true,
1969 // If the return type would push over the max width, then put the return type on
1970 // a new line. With the +1 for the signature length an additional space between
1971 // the closing parenthesis of the argument and the arrow '->' is considered.
1972 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1974 // If there is no where clause, take into account the space after the return type
1976 if where_clause.predicates.is_empty() {
1980 sig_length > context.config.max_width()
1983 let ret_indent = if ret_should_indent {
1984 let indent = match context.config.fn_return_indent() {
1985 ReturnIndent::WithWhereClause => indent + 4,
1986 // Aligning with non-existent args looks silly.
1987 _ if arg_str.is_empty() => {
1988 force_new_line_for_brace = true;
1991 // FIXME: we might want to check that using the arg indent
1992 // doesn't blow our budget, and if it does, then fallback to
1993 // the where clause indent.
1998 result.push_str(&indent.to_string(context.config));
2002 Indent::new(indent.block_indent, last_line_width(&result))
2005 if multi_line_ret_str || ret_should_indent {
2006 // Now that we know the proper indent and width, we need to
2007 // re-layout the return type.
2008 let ret_str = fd.output
2009 .rewrite(context, Shape::indented(ret_indent, context.config))?;
2010 result.push_str(&ret_str);
2012 result.push_str(&ret_str);
2015 // Comment between return type and the end of the decl.
2016 let snippet_lo = fd.output.span().hi();
2017 if where_clause.predicates.is_empty() {
2018 let snippet_hi = span.hi();
2019 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2020 // Try to preserve the layout of the original snippet.
2021 let original_starts_with_newline = snippet
2023 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2024 let original_ends_with_newline = snippet
2025 .rfind(|c| c != ' ')
2026 .map_or(false, |i| snippet[i..].ends_with('\n'));
2027 let snippet = snippet.trim();
2028 if !snippet.is_empty() {
2029 result.push(if original_starts_with_newline {
2034 result.push_str(snippet);
2035 if original_ends_with_newline {
2036 force_new_line_for_brace = true;
2042 let should_compress_where = match context.config.where_density() {
2043 Density::Compressed => !result.contains('\n'),
2044 Density::CompressedIfEmpty => !has_body && !result.contains('\n'),
2048 let pos_before_where = match fd.output {
2049 ast::FunctionRetTy::Default(..) => args_span.hi(),
2050 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2053 let is_args_multi_lined = arg_str.contains('\n');
2055 if where_clause.predicates.len() == 1 && should_compress_where {
2056 let budget = context.budget(last_line_used_width(&result, indent.width()));
2057 if let Some(where_clause_str) = rewrite_where_clause(
2060 context.config.brace_style(),
2061 Shape::legacy(budget, indent),
2062 Density::Compressed,
2066 WhereClauseOption::compressed(),
2067 is_args_multi_lined,
2069 result.push_str(&where_clause_str);
2070 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2071 return Some((result, force_new_line_for_brace));
2075 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2076 let where_clause_str = rewrite_where_clause(
2079 context.config.brace_style(),
2080 Shape::indented(indent, context.config),
2086 is_args_multi_lined,
2088 // If there are neither where clause nor return type, we may be missing comments between
2090 if where_clause_str.is_empty() {
2091 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2092 match recover_missing_comment_in_span(
2093 mk_sp(args_span.hi(), ret_span.hi()),
2096 last_line_width(&result),
2098 Some(ref missing_comment) if !missing_comment.is_empty() => {
2099 result.push_str(missing_comment);
2100 force_new_line_for_brace = true;
2107 result.push_str(&where_clause_str);
2109 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2110 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2111 Some((result, force_new_line_for_brace))
2114 #[derive(Copy, Clone)]
2115 struct WhereClauseOption {
2116 suppress_comma: bool, // Force no trailing comma
2117 snuggle: bool, // Do not insert newline before `where`
2118 compress_where: bool, // Try single line where clause instead of vertical layout
2121 impl WhereClauseOption {
2122 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2124 suppress_comma: suppress_comma,
2126 compress_where: false,
2130 pub fn compressed() -> WhereClauseOption {
2132 suppress_comma: true,
2134 compress_where: true,
2138 pub fn snuggled(current: &str) -> WhereClauseOption {
2140 suppress_comma: false,
2141 snuggle: trimmed_last_line_width(current) == 1,
2142 compress_where: false,
2148 context: &RewriteContext,
2150 explicit_self: Option<&ast::ExplicitSelf>,
2151 one_line_budget: usize,
2152 multi_line_budget: usize,
2157 generics_str_contains_newline: bool,
2158 ) -> Option<String> {
2159 let mut arg_item_strs = args.iter()
2161 arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent))
2163 .collect::<Option<Vec<_>>>()?;
2165 // Account for sugary self.
2166 // FIXME: the comment for the self argument is dropped. This is blocked
2167 // on rust issue #27522.
2168 let min_args = explicit_self
2169 .and_then(|explicit_self| {
2170 rewrite_explicit_self(explicit_self, args, context)
2172 .map_or(1, |self_str| {
2173 arg_item_strs[0] = self_str;
2177 // Comments between args.
2178 let mut arg_items = Vec::new();
2180 arg_items.push(ListItem::from_str(""));
2183 // FIXME(#21): if there are no args, there might still be a comment, but
2184 // without spans for the comment or parens, there is no chance of
2185 // getting it right. You also don't get to put a comment on self, unless
2187 if args.len() >= min_args || variadic {
2188 let comment_span_start = if min_args == 2 {
2189 let second_arg_start = if arg_has_pattern(&args[1]) {
2190 args[1].pat.span.lo()
2192 args[1].ty.span.lo()
2194 let reduced_span = mk_sp(span.lo(), second_arg_start);
2196 context.codemap.span_after_last(reduced_span, ",")
2201 enum ArgumentKind<'a> {
2202 Regular(&'a ast::Arg),
2206 let variadic_arg = if variadic {
2207 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2208 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2209 Some(ArgumentKind::Variadic(variadic_start))
2214 let more_items = itemize_list(
2216 args[min_args - 1..]
2218 .map(ArgumentKind::Regular)
2219 .chain(variadic_arg),
2223 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2224 ArgumentKind::Variadic(start) => start,
2227 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2228 ArgumentKind::Variadic(start) => start + BytePos(3),
2231 ArgumentKind::Regular(..) => None,
2232 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2239 arg_items.extend(more_items);
2242 let fits_in_one_line = !generics_str_contains_newline
2243 && (arg_items.is_empty()
2244 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2246 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2247 item.item = Some(arg);
2250 let last_line_ends_with_comment = arg_items
2253 .and_then(|item| item.post_comment.as_ref())
2254 .map_or(false, |s| s.trim().starts_with("//"));
2256 let (indent, trailing_comma) = match context.config.indent_style() {
2257 IndentStyle::Block if fits_in_one_line => {
2258 (indent.block_indent(context.config), SeparatorTactic::Never)
2260 IndentStyle::Block => (
2261 indent.block_indent(context.config),
2262 context.config.trailing_comma(),
2264 IndentStyle::Visual if last_line_ends_with_comment => {
2265 (arg_indent, context.config.trailing_comma())
2267 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2270 let tactic = definitive_tactic(
2272 context.config.fn_args_density().to_list_tactic(),
2276 let budget = match tactic {
2277 DefinitiveListTactic::Horizontal => one_line_budget,
2278 _ => multi_line_budget,
2281 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2283 let fmt = ListFormatting {
2286 trailing_separator: if variadic {
2287 SeparatorTactic::Never
2291 separator_place: SeparatorPlace::Back,
2292 shape: Shape::legacy(budget, indent),
2293 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2294 preserve_newline: true,
2295 config: context.config,
2298 write_list(&arg_items, &fmt)
2301 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2302 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2303 ident.node != symbol::keywords::Invalid.ident()
2309 fn compute_budgets_for_args(
2310 context: &RewriteContext,
2314 newline_brace: bool,
2316 force_vertical_layout: bool,
2317 ) -> Option<((usize, usize, Indent))> {
2319 "compute_budgets_for_args {} {:?}, {}, {}",
2325 // Try keeping everything on the same line.
2326 if !result.contains('\n') && !force_vertical_layout {
2327 // 2 = `()`, 3 = `() `, space is before ret_string.
2328 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2329 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2339 let one_line_budget = context.budget(used_space);
2341 if one_line_budget > 0 {
2343 let (indent, multi_line_budget) = match context.config.indent_style() {
2344 IndentStyle::Block => {
2345 let indent = indent.block_indent(context.config);
2346 (indent, context.budget(indent.width() + 1))
2348 IndentStyle::Visual => {
2349 let indent = indent + result.len() + 1;
2350 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2351 (indent, context.budget(multi_line_overhead))
2355 return Some((one_line_budget, multi_line_budget, indent));
2359 // Didn't work. we must force vertical layout and put args on a newline.
2360 let new_indent = indent.block_indent(context.config);
2361 let used_space = match context.config.indent_style() {
2363 IndentStyle::Block => new_indent.width() + 1,
2364 // Account for `)` and possibly ` {`.
2365 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2367 Some((0, context.budget(used_space), new_indent))
2370 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause, has_body: bool) -> bool {
2371 let predicate_count = where_clause.predicates.len();
2373 if config.where_single_line() && predicate_count == 1 {
2376 match (config.brace_style(), config.where_density()) {
2377 (BraceStyle::AlwaysNextLine, _) => true,
2378 (_, Density::Compressed) if predicate_count == 1 => false,
2379 (_, Density::CompressedIfEmpty) if predicate_count == 1 && !has_body => false,
2380 (BraceStyle::SameLineWhere, _) if predicate_count > 0 => true,
2385 fn rewrite_generics(
2386 context: &RewriteContext,
2387 generics: &ast::Generics,
2390 ) -> Option<String> {
2391 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2392 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2393 rewrite_generics_inner(context, generics, g_shape, one_line_width, span).or_else(|| {
2394 rewrite_generics_inner(context, generics, g_shape, 0, span)
2398 fn rewrite_generics_inner(
2399 context: &RewriteContext,
2400 generics: &ast::Generics,
2402 one_line_width: usize,
2404 ) -> Option<String> {
2405 // FIXME: convert bounds to where clauses where they get too big or if
2406 // there is a where clause at all.
2409 enum GenericsArg<'a> {
2410 Lifetime(&'a ast::LifetimeDef),
2411 TyParam(&'a ast::TyParam),
2413 impl<'a> Rewrite for GenericsArg<'a> {
2414 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2416 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2417 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2421 impl<'a> Spanned for GenericsArg<'a> {
2422 fn span(&self) -> Span {
2424 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2425 GenericsArg::TyParam(ty) => ty.span(),
2430 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2431 return Some(String::new());
2434 let generics_args = generics
2437 .map(|lt| GenericsArg::Lifetime(lt))
2438 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2439 let items = itemize_list(
2444 |arg| arg.span().lo(),
2445 |arg| arg.span().hi(),
2446 |arg| arg.rewrite(context, shape),
2447 context.codemap.span_after(span, "<"),
2451 format_generics_item_list(context, items, shape, one_line_width)
2454 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2455 match config.indent_style() {
2456 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2457 IndentStyle::Block => {
2461 .block_indent(config.tab_spaces())
2462 .with_max_width(config)
2468 pub fn format_generics_item_list<I>(
2469 context: &RewriteContext,
2472 one_line_budget: usize,
2475 I: Iterator<Item = ListItem>,
2477 let item_vec = items.collect::<Vec<_>>();
2479 let tactic = definitive_tactic(
2481 ListTactic::HorizontalVertical,
2485 let fmt = ListFormatting {
2488 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2489 SeparatorTactic::Never
2491 context.config.trailing_comma()
2493 separator_place: SeparatorPlace::Back,
2495 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2496 preserve_newline: true,
2497 config: context.config,
2500 let list_str = write_list(&item_vec, &fmt)?;
2502 Some(wrap_generics_with_angle_brackets(
2509 pub fn wrap_generics_with_angle_brackets(
2510 context: &RewriteContext,
2512 list_offset: Indent,
2514 if context.config.indent_style() == IndentStyle::Block
2515 && (list_str.contains('\n') || list_str.ends_with(','))
2519 list_offset.to_string(context.config),
2522 .block_unindent(context.config)
2523 .to_string(context.config)
2525 } else if context.config.spaces_within_parens_and_brackets() {
2526 format!("< {} >", list_str)
2528 format!("<{}>", list_str)
2532 fn rewrite_trait_bounds(
2533 context: &RewriteContext,
2534 type_param_bounds: &ast::TyParamBounds,
2536 ) -> Option<String> {
2537 let bounds: &[_] = type_param_bounds;
2539 if bounds.is_empty() {
2540 return Some(String::new());
2542 let bound_str = bounds
2544 .map(|ty_bound| ty_bound.rewrite(context, shape))
2545 .collect::<Option<Vec<_>>>()?;
2546 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2549 fn rewrite_where_clause_rfc_style(
2550 context: &RewriteContext,
2551 where_clause: &ast::WhereClause,
2554 span_end: Option<BytePos>,
2555 span_end_before_where: BytePos,
2556 where_clause_option: WhereClauseOption,
2557 is_args_multi_line: bool,
2558 ) -> Option<String> {
2559 let block_shape = shape.block().with_max_width(context.config);
2561 let (span_before, span_after) =
2562 missing_span_before_after_where(span_end_before_where, where_clause);
2563 let (comment_before, comment_after) =
2564 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2566 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2569 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2572 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2574 let clause_shape = clause_shape.sub_width(1)?;
2575 // each clause on one line, trailing comma (except if suppress_comma)
2576 let span_start = where_clause.predicates[0].span().lo();
2577 // If we don't have the start of the next span, then use the end of the
2578 // predicates, but that means we miss comments.
2579 let len = where_clause.predicates.len();
2580 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2581 let span_end = span_end.unwrap_or(end_of_preds);
2582 let items = itemize_list(
2584 where_clause.predicates.iter(),
2587 |pred| pred.span().lo(),
2588 |pred| pred.span().hi(),
2589 |pred| pred.rewrite(context, clause_shape),
2594 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2595 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2596 SeparatorTactic::Never
2598 context.config.trailing_comma()
2601 // shape should be vertical only and only if we have `where_single_line` option enabled
2602 // and the number of items of the where clause is equal to 1
2603 let shape_tactic = if where_single_line {
2604 DefinitiveListTactic::Horizontal
2606 DefinitiveListTactic::Vertical
2609 let fmt = ListFormatting {
2610 tactic: shape_tactic,
2612 trailing_separator: comma_tactic,
2613 separator_place: SeparatorPlace::Back,
2614 shape: clause_shape,
2615 ends_with_newline: true,
2616 preserve_newline: true,
2617 config: context.config,
2619 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2621 let comment_separator = |comment: &str, shape: Shape| if comment.is_empty() {
2624 format!("\n{}", shape.indent.to_string(context.config))
2626 let newline_before_where = comment_separator(&comment_before, shape);
2627 let newline_after_where = comment_separator(&comment_after, clause_shape);
2630 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2631 && comment_after.is_empty() && !preds_str.contains('\n')
2632 && 6 + preds_str.len() <= shape.width || where_single_line
2636 format!("\n{}", clause_shape.indent.to_string(context.config))
2639 "{}{}{}where{}{}{}{}",
2642 newline_before_where,
2643 newline_after_where,
2650 fn rewrite_where_clause(
2651 context: &RewriteContext,
2652 where_clause: &ast::WhereClause,
2653 brace_style: BraceStyle,
2657 span_end: Option<BytePos>,
2658 span_end_before_where: BytePos,
2659 where_clause_option: WhereClauseOption,
2660 is_args_multi_line: bool,
2661 ) -> Option<String> {
2662 if where_clause.predicates.is_empty() {
2663 return Some(String::new());
2666 if context.config.indent_style() == IndentStyle::Block {
2667 return rewrite_where_clause_rfc_style(
2673 span_end_before_where,
2674 where_clause_option,
2679 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2681 let offset = match context.config.indent_style() {
2682 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2683 // 6 = "where ".len()
2684 IndentStyle::Visual => shape.indent + extra_indent + 6,
2686 // FIXME: if indent_style != Visual, then the budgets below might
2687 // be out by a char or two.
2689 let budget = context.config.max_width() - offset.width();
2690 let span_start = where_clause.predicates[0].span().lo();
2691 // If we don't have the start of the next span, then use the end of the
2692 // predicates, but that means we miss comments.
2693 let len = where_clause.predicates.len();
2694 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2695 let span_end = span_end.unwrap_or(end_of_preds);
2696 let items = itemize_list(
2698 where_clause.predicates.iter(),
2701 |pred| pred.span().lo(),
2702 |pred| pred.span().hi(),
2703 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2708 let item_vec = items.collect::<Vec<_>>();
2709 // FIXME: we don't need to collect here if the where_layout isn't
2710 // HorizontalVertical.
2711 let tactic = definitive_tactic(
2713 context.config.where_layout(),
2718 let mut comma_tactic = context.config.trailing_comma();
2719 // Kind of a hack because we don't usually have trailing commas in where clauses.
2720 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2721 comma_tactic = SeparatorTactic::Never;
2724 let fmt = ListFormatting {
2727 trailing_separator: comma_tactic,
2728 separator_place: SeparatorPlace::Back,
2729 shape: Shape::legacy(budget, offset),
2730 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2731 preserve_newline: true,
2732 config: context.config,
2734 let preds_str = write_list(&item_vec, &fmt)?;
2736 let end_length = if terminator == "{" {
2737 // If the brace is on the next line we don't need to count it otherwise it needs two
2740 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2741 BraceStyle::PreferSameLine => 2,
2743 } else if terminator == "=" {
2748 if density == Density::Tall || preds_str.contains('\n')
2749 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2753 (shape.indent + extra_indent).to_string(context.config),
2757 Some(format!(" where {}", preds_str))
2761 fn missing_span_before_after_where(
2762 before_item_span_end: BytePos,
2763 where_clause: &ast::WhereClause,
2765 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2767 let pos_after_where = where_clause.span.lo() + BytePos(5);
2768 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2769 (missing_span_before, missing_span_after)
2772 fn rewrite_comments_before_after_where(
2773 context: &RewriteContext,
2774 span_before_where: Span,
2775 span_after_where: Span,
2777 ) -> Option<(String, String)> {
2778 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2779 let after_comment = rewrite_missing_comment(
2781 shape.block_indent(context.config.tab_spaces()),
2784 Some((before_comment, after_comment))
2787 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2788 format!("{}{}{}", format_visibility(vis), item_name, ident)
2791 #[derive(PartialEq, Eq)]
2799 context: &RewriteContext,
2800 generics: &ast::Generics,
2801 brace_style: BraceStyle,
2802 brace_pos: BracePos,
2806 ) -> Option<String> {
2807 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2808 let mut result = rewrite_generics(context, generics, shape, span)?;
2810 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2811 let budget = context.budget(last_line_used_width(&result, offset.width()));
2812 let mut option = WhereClauseOption::snuggled(&result);
2813 if brace_pos == BracePos::None {
2814 option.suppress_comma = true;
2816 // If the generics are not parameterized then generics.span.hi() == 0,
2817 // so we use span.lo(), which is the position after `struct Foo`.
2818 let span_end_before_where = if generics.is_parameterized() {
2823 let where_clause_str = rewrite_where_clause(
2825 &generics.where_clause,
2827 Shape::legacy(budget, offset.block_only()),
2831 span_end_before_where,
2835 result.push_str(&where_clause_str);
2836 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2837 || (generics.where_clause.predicates.is_empty()
2838 && trimmed_last_line_width(&result) == 1)
2840 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2841 || brace_style != BraceStyle::AlwaysNextLine
2843 if brace_pos == BracePos::None {
2844 return Some(result);
2846 let total_used_width = last_line_used_width(&result, used_width);
2847 let remaining_budget = context.budget(total_used_width);
2848 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2849 // and hence we take the closer into account as well for one line budget.
2850 // We assume that the closer has the same length as the opener.
2851 let overhead = if brace_pos == BracePos::ForceSameLine {
2858 let forbid_same_line_brace = overhead > remaining_budget;
2859 if !forbid_same_line_brace && same_line_brace {
2863 result.push_str(&offset.block_only().to_string(context.config));
2870 impl Rewrite for ast::ForeignItem {
2871 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2872 let attrs_str = self.attrs.rewrite(context, shape)?;
2873 // Drop semicolon or it will be interpreted as comment.
2874 // FIXME: this may be a faulty span from libsyntax.
2875 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2877 let item_str = match self.node {
2878 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2883 &FnSig::new(fn_decl, generics, self.vis.clone()),
2887 ).map(|(s, _)| format!("{};", s))
2889 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2890 // FIXME(#21): we're dropping potential comments in between the
2891 // function keywords here.
2892 let vis = format_visibility(&self.vis);
2893 let mut_str = if is_mutable { "mut " } else { "" };
2894 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2896 let shape = shape.sub_width(1)?;
2897 ty.rewrite(context, shape).map(|ty_str| {
2898 // 1 = space between prefix and type.
2899 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2902 let nested_indent = shape.indent.block_indent(context.config);
2903 format!("\n{}", nested_indent.to_string(context.config))
2905 format!("{}{}{};", prefix, sep, ty_str)
2908 ast::ForeignItemKind::Ty => {
2909 let vis = format_visibility(&self.vis);
2910 Some(format!("{}type {};", vis, self.ident))
2914 let missing_span = if self.attrs.is_empty() {
2915 mk_sp(self.span.lo(), self.span.lo())
2917 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2919 combine_strs_with_missing_comments(