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 {:?} {} {:?}",
51 self, shape.width, shape.indent
54 skip_out_of_file_lines_range!(context, self.span);
56 if contains_skip(&self.attrs) {
60 let attrs_str = self.attrs.rewrite(context, shape)?;
61 let mut result = if attrs_str.is_empty() {
64 combine_strs_with_missing_comments(
69 self.attrs.last().map(|a| a.span.hi()).unwrap(),
78 let pat_shape = shape.offset_left(4)?;
80 let pat_shape = pat_shape.sub_width(1)?;
81 let pat_str = self.pat.rewrite(context, pat_shape)?;
82 result.push_str(&pat_str);
84 // String that is placed within the assignment pattern and expression.
86 let mut infix = String::with_capacity(32);
88 if let Some(ref ty) = self.ty {
89 let separator = type_annotation_separator(context.config);
90 let indent = shape.indent + last_line_width(&result) + separator.len();
92 let budget = shape.width.checked_sub(indent.width() + 1)?;
93 let rewrite = ty.rewrite(context, Shape::legacy(budget, indent))?;
95 infix.push_str(separator);
96 infix.push_str(&rewrite);
99 if self.init.is_some() {
100 infix.push_str(" =");
106 result.push_str(&infix);
108 if let Some(ref ex) = self.init {
109 // 1 = trailing semicolon;
110 let nested_shape = shape.sub_width(1)?;
112 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
120 // TODO convert to using rewrite style rather than visitor
121 // TODO format modules in this style
124 keyword: &'static str,
125 abi: Cow<'static, str>,
126 vis: Option<&'a ast::Visibility>,
127 body: Vec<BodyElement<'a>>,
132 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
135 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
139 .map(|i| BodyElement::ForeignItem(i))
146 enum BodyElement<'a> {
147 // Stmt(&'a ast::Stmt),
148 // Field(&'a ast::Field),
149 // Variant(&'a ast::Variant),
150 // Item(&'a ast::Item),
151 ForeignItem(&'a ast::ForeignItem),
154 /// Represents a fn's signature.
155 pub struct FnSig<'a> {
156 decl: &'a ast::FnDecl,
157 generics: &'a ast::Generics,
159 constness: ast::Constness,
160 defaultness: ast::Defaultness,
161 unsafety: ast::Unsafety,
162 visibility: ast::Visibility,
167 decl: &'a ast::FnDecl,
168 generics: &'a ast::Generics,
169 vis: ast::Visibility,
175 constness: ast::Constness::NotConst,
176 defaultness: ast::Defaultness::Final,
177 unsafety: ast::Unsafety::Normal,
182 pub fn from_method_sig(
183 method_sig: &'a ast::MethodSig,
184 generics: &'a ast::Generics,
187 unsafety: method_sig.unsafety,
188 constness: method_sig.constness.node,
189 defaultness: ast::Defaultness::Final,
191 decl: &*method_sig.decl,
193 visibility: ast::Visibility::Inherited,
198 fn_kind: &'a visit::FnKind,
199 generics: &'a ast::Generics,
200 decl: &'a ast::FnDecl,
201 defualtness: ast::Defaultness,
204 visit::FnKind::ItemFn(_, unsafety, constness, abi, visibility, _) => FnSig {
208 constness: constness.node,
209 defaultness: defualtness,
211 visibility: visibility.clone(),
213 visit::FnKind::Method(_, method_sig, vis, _) => {
214 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
215 fn_sig.defaultness = defualtness;
216 if let Some(vis) = vis {
217 fn_sig.visibility = vis.clone();
225 fn to_str(&self, context: &RewriteContext) -> String {
226 let mut result = String::with_capacity(128);
227 // Vis defaultness constness unsafety abi.
228 result.push_str(&*format_visibility(&self.visibility));
229 result.push_str(format_defaultness(self.defaultness));
230 result.push_str(format_constness(self.constness));
231 result.push_str(format_unsafety(self.unsafety));
232 result.push_str(&format_abi(
234 context.config.force_explicit_abi(),
241 impl<'a> FmtVisitor<'a> {
242 fn format_item(&mut self, item: Item) {
243 self.push_str(&item.abi);
245 let snippet = self.snippet(item.span);
246 let brace_pos = snippet.find_uncommented("{").unwrap();
249 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
250 // FIXME: this skips comments between the extern keyword and the opening
252 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
253 self.block_indent = self.block_indent.block_indent(self.config);
255 if item.body.is_empty() {
256 self.format_missing_no_indent(item.span.hi() - BytePos(1));
257 self.block_indent = self.block_indent.block_unindent(self.config);
258 let indent_str = self.block_indent.to_string(self.config);
259 self.push_str(&indent_str);
261 for item in &item.body {
262 self.format_body_element(item);
265 self.block_indent = self.block_indent.block_unindent(self.config);
266 self.format_missing_with_indent(item.span.hi() - BytePos(1));
271 self.last_pos = item.span.hi();
274 fn format_body_element(&mut self, element: &BodyElement) {
276 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
280 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
281 let item = Item::from_foreign_mod(fm, span, self.config);
282 self.format_item(item);
285 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
286 let rewrite = item.rewrite(&self.get_context(), self.shape());
287 self.push_rewrite(item.span(), rewrite);
288 self.last_pos = item.span.hi();
298 ) -> Option<String> {
299 let context = self.get_context();
301 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
303 let (mut result, force_newline_brace) =
304 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
307 if self.config.brace_style() == BraceStyle::AlwaysNextLine || force_newline_brace
308 || last_line_width(&result) + 2 > self.shape().width
310 newline_brace = true;
311 } else if !result.contains('\n') {
312 newline_brace = false;
315 // Prepare for the function body by possibly adding a newline and
317 // FIXME we'll miss anything between the end of the signature and the
318 // start of the body, but we need more spans from the compiler to solve
322 result.push_str(&indent.to_string(self.config));
327 self.single_line_fn(&result, block).or_else(|| Some(result))
330 pub fn rewrite_required_fn(
334 sig: &ast::MethodSig,
335 generics: &ast::Generics,
337 ) -> Option<String> {
338 // Drop semicolon or it will be interpreted as comment.
339 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
340 let context = self.get_context();
342 let (mut result, _) = rewrite_fn_base(
346 &FnSig::from_method_sig(sig, generics),
352 // Re-attach semicolon
358 fn single_line_fn(&self, fn_str: &str, block: &ast::Block) -> Option<String> {
359 if fn_str.contains('\n') {
363 let codemap = self.get_context().codemap;
365 if self.config.empty_item_single_line() && is_empty_block(block, codemap)
366 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
368 return Some(format!("{}{{}}", fn_str));
371 if self.config.fn_single_line() && is_simple_block_stmt(block, codemap) {
373 if let Some(stmt) = block.stmts.first() {
374 match stmt_expr(stmt) {
376 let suffix = if semicolon_for_expr(&self.get_context(), e) {
382 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
384 .or_else(|| Some(self.snippet(e.span).to_owned()))
386 None => stmt.rewrite(&self.get_context(), self.shape()),
393 if let Some(res) = rewrite {
394 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
395 if !res.contains('\n') && width <= self.config.max_width() {
396 return Some(format!("{}{{ {} }}", fn_str, res));
404 pub fn visit_static(&mut self, static_parts: &StaticParts) {
405 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
406 self.push_rewrite(static_parts.span, rewrite);
409 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
410 let is_tuple = struct_parts.def.is_tuple();
411 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
412 .map(|s| if is_tuple { s + ";" } else { s });
413 self.push_rewrite(struct_parts.span, rewrite);
419 vis: &ast::Visibility,
420 enum_def: &ast::EnumDef,
421 generics: &ast::Generics,
424 let enum_header = format_header("enum ", ident, vis);
425 self.push_str(&enum_header);
427 let enum_snippet = self.snippet(span);
428 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
429 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
430 let generics_str = format_generics(
433 self.config.brace_style(),
434 if enum_def.variants.is_empty() {
435 BracePos::ForceSameLine
440 mk_sp(span.lo(), body_start),
441 last_line_width(&enum_header),
443 self.push_str(&generics_str);
445 self.last_pos = body_start;
447 self.block_indent = self.block_indent.block_indent(self.config);
448 let variant_list = self.format_variant_list(enum_def, body_start, span.hi() - BytePos(1));
450 Some(ref body_str) => self.push_str(body_str),
451 None => self.format_missing_no_indent(span.hi() - BytePos(1)),
453 self.block_indent = self.block_indent.block_unindent(self.config);
455 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
456 let indent_str = self.block_indent.to_string(self.config);
457 self.push_str(&indent_str);
460 self.last_pos = span.hi();
463 // Format the body of an enum definition
464 fn format_variant_list(
466 enum_def: &ast::EnumDef,
469 ) -> Option<String> {
470 if enum_def.variants.is_empty() {
473 let mut result = String::with_capacity(1024);
475 let indentation = self.block_indent.to_string(self.config);
476 result.push_str(&indentation);
478 let itemize_list_with = |one_line_width: usize| {
481 enum_def.variants.iter(),
485 if !f.node.attrs.is_empty() {
486 f.node.attrs[0].span.lo()
492 |f| self.format_variant(f, one_line_width),
498 let mut items: Vec<_> =
499 itemize_list_with(self.config.width_heuristics().struct_variant_width);
500 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
501 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
502 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
503 if has_multiline_variant && has_single_line_variant {
504 items = itemize_list_with(0);
507 let shape = self.shape().sub_width(2).unwrap();
508 let fmt = ListFormatting {
509 tactic: DefinitiveListTactic::Vertical,
511 trailing_separator: self.config.trailing_comma(),
512 separator_place: SeparatorPlace::Back,
514 ends_with_newline: true,
515 preserve_newline: true,
519 let list = write_list(&items, &fmt)?;
520 result.push_str(&list);
525 // Variant of an enum.
526 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
527 if contains_skip(&field.node.attrs) {
528 let lo = field.node.attrs[0].span.lo();
529 let span = mk_sp(lo, field.span.hi());
530 return Some(self.snippet(span).to_owned());
533 let context = self.get_context();
535 let shape = self.shape().sub_width(1)?;
536 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
541 .map_or(field.span.lo(), |attr| attr.span.hi());
542 let span = mk_sp(lo, field.span.lo());
544 let variant_body = match field.node.data {
545 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
547 &StructParts::from_variant(field),
549 Some(one_line_width),
551 ast::VariantData::Unit(..) => {
552 if let Some(ref expr) = field.node.disr_expr {
553 let lhs = format!("{} =", field.node.name);
554 rewrite_assign_rhs(&context, lhs, &**expr, shape)?
556 field.node.name.to_string()
561 let attrs_extendable = attrs_str.is_empty()
562 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
563 combine_strs_with_missing_comments(
575 context: &RewriteContext,
578 where_span_end: Option<BytePos>,
579 ) -> Option<String> {
580 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
581 let mut result = String::with_capacity(128);
582 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
583 let indent_str = offset.to_string(context.config);
584 let sep = format!("\n{}", &indent_str);
585 result.push_str(&ref_and_type);
587 let where_budget = if result.contains('\n') {
588 context.config.max_width()
590 context.budget(last_line_width(&result))
592 let option = WhereClauseOption::snuggled(&ref_and_type);
593 let where_clause_str = rewrite_where_clause(
595 &generics.where_clause,
596 context.config.brace_style(),
597 Shape::legacy(where_budget, offset.block_only()),
606 // If there is no where clause, we may have missing comments between the trait name and
607 // the opening brace.
608 if generics.where_clause.predicates.is_empty() {
609 if let Some(hi) = where_span_end {
610 match recover_missing_comment_in_span(
611 mk_sp(self_ty.span.hi(), hi),
612 Shape::indented(offset, context.config),
614 last_line_width(&result),
616 Some(ref missing_comment) if !missing_comment.is_empty() => {
617 result.push_str(missing_comment);
624 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
625 result.push_str(&where_clause_str);
626 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
627 result.push_str(&format!("{}{{{}}}", &sep, &sep));
629 result.push_str(" {}");
634 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
636 let width = offset.block_indent + context.config.tab_spaces() - 1;
637 let where_indent = Indent::new(0, width);
638 result.push_str(&where_indent.to_string(context.config));
640 result.push_str(&where_clause_str);
642 match context.config.brace_style() {
643 _ if last_line_contains_single_line_comment(&result) => result.push_str(&sep),
644 BraceStyle::AlwaysNextLine => result.push_str(&sep),
645 BraceStyle::PreferSameLine => result.push(' '),
646 BraceStyle::SameLineWhere => {
647 if !where_clause_str.is_empty() {
648 result.push_str(&sep);
657 let snippet = context.snippet(item.span);
658 let open_pos = snippet.find_uncommented("{")? + 1;
660 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
661 let mut visitor = FmtVisitor::from_context(context);
662 visitor.block_indent = offset.block_only().block_indent(context.config);
663 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
665 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
667 visitor.visit_impl_item(item);
670 visitor.format_missing(item.span.hi() - BytePos(1));
672 let inner_indent_str = visitor.block_indent.to_string(context.config);
673 let outer_indent_str = offset.block_only().to_string(context.config);
676 result.push_str(&inner_indent_str);
677 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
679 result.push_str(&outer_indent_str);
682 if result.ends_with('{') {
683 result.push_str(&sep);
693 fn is_impl_single_line(
694 context: &RewriteContext,
697 where_clause_str: &str,
700 let snippet = context.snippet(item.span);
701 let open_pos = snippet.find_uncommented("{")? + 1;
704 context.config.empty_item_single_line() && items.is_empty() && !result.contains('\n')
705 && result.len() + where_clause_str.len() <= context.config.max_width()
706 && !contains_comment(&snippet[open_pos..]),
710 fn format_impl_ref_and_type(
711 context: &RewriteContext,
714 ) -> Option<String> {
715 if let ast::ItemKind::Impl(
725 let mut result = String::with_capacity(128);
727 result.push_str(&format_visibility(&item.vis));
728 result.push_str(format_defaultness(defaultness));
729 result.push_str(format_unsafety(unsafety));
730 result.push_str("impl");
732 let lo = context.codemap.span_after(item.span, "impl");
733 let hi = match *trait_ref {
734 Some(ref tr) => tr.path.span.lo(),
735 None => self_ty.span.lo(),
737 let shape = generics_shape_from_config(
739 Shape::indented(offset + last_line_width(&result), context.config),
742 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
744 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
746 let polarity_str = if polarity == ast::ImplPolarity::Negative {
752 if let Some(ref trait_ref) = *trait_ref {
753 let result_len = result.len();
754 if let Some(trait_ref_str) = rewrite_trait_ref(
763 result.push_str(&trait_ref_str);
766 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
767 result.push_str(&rewrite_trait_ref(
778 result.push_str(&generics_str);
781 // Try to put the self type in a single line.
783 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
784 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
785 // If there is no where clause adapt budget for type formatting to take space and curly
786 // brace into account.
787 match context.config.brace_style() {
788 BraceStyle::AlwaysNextLine => 0,
794 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
795 // 1 = space before the type.
796 let budget = context.budget(used_space + 1);
797 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
798 if !self_ty_str.contains('\n') {
799 if trait_ref.is_some() {
800 result.push_str(" for ");
804 result.push_str(&self_ty_str);
809 // Couldn't fit the self type on a single line, put it on a new line.
811 // Add indentation of one additional tab.
812 let new_line_offset = offset.block_indent(context.config);
813 result.push_str(&new_line_offset.to_string(context.config));
814 if trait_ref.is_some() {
815 result.push_str("for ");
817 let budget = context.budget(last_line_width(&result));
818 let type_offset = match context.config.indent_style() {
819 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
820 IndentStyle::Block => new_line_offset,
822 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
829 fn rewrite_trait_ref(
830 context: &RewriteContext,
831 trait_ref: &ast::TraitRef,
837 ) -> Option<String> {
838 // 1 = space between generics and trait_ref
839 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
840 let shape = Shape::indented(offset + used_space, context.config);
841 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
842 if !(retry && trait_ref_str.contains('\n')) {
845 generics_str, polarity_str, &trait_ref_str
849 // We could not make enough space for trait_ref, so put it on new line.
851 let offset = offset.block_indent(context.config);
852 let shape = Shape::indented(offset, context.config);
853 let trait_ref_str = trait_ref.rewrite(context, shape)?;
857 &offset.to_string(context.config),
866 pub struct StructParts<'a> {
869 vis: &'a ast::Visibility,
870 def: &'a ast::VariantData,
871 generics: Option<&'a ast::Generics>,
875 impl<'a> StructParts<'a> {
876 fn format_header(&self) -> String {
877 format_header(self.prefix, self.ident, self.vis)
880 fn from_variant(variant: &'a ast::Variant) -> Self {
883 ident: variant.node.name,
884 vis: &ast::Visibility::Inherited,
885 def: &variant.node.data,
891 pub fn from_item(item: &'a ast::Item) -> Self {
892 let (prefix, def, generics) = match item.node {
893 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
894 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
902 generics: Some(generics),
909 context: &RewriteContext,
910 struct_parts: &StructParts,
912 one_line_width: Option<usize>,
913 ) -> Option<String> {
914 match *struct_parts.def {
915 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
916 ast::VariantData::Tuple(ref fields, _) => {
917 format_tuple_struct(context, struct_parts, fields, offset)
919 ast::VariantData::Struct(ref fields, _) => {
920 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
925 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
926 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
929 let mut result = String::with_capacity(128);
930 let header = format!(
932 format_visibility(&item.vis),
933 format_unsafety(unsafety),
937 result.push_str(&header);
939 let body_lo = context.codemap.span_after(item.span, "{");
941 let shape = Shape::indented(offset, context.config);
943 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
944 result.push_str(&generics_str);
946 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
947 if !type_param_bounds.is_empty() {
948 let ident_hi = context.codemap.span_after(item.span, &format!("{}", item.ident));
949 let bound_hi = type_param_bounds.last().unwrap().span().hi();
950 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
951 if contains_comment(&snippet) {
955 let trait_bound_str = rewrite_trait_bounds(
958 Shape::indented(offset, context.config),
960 // If the trait, generics, and trait bound cannot fit on the same line,
961 // put the trait bounds on an indented new line
962 if offset.width() + last_line_width(&result) + trait_bound_str.len()
963 > context.config.comment_width()
966 let trait_indent = offset.block_only().block_indent(context.config);
967 result.push_str(&trait_indent.to_string(context.config));
969 result.push_str(&trait_bound_str);
972 if context.config.indent_style() == IndentStyle::Block && result.is_empty() {
978 let where_budget = context.budget(last_line_width(&result));
979 let pos_before_where = if type_param_bounds.is_empty() {
980 generics.where_clause.span.lo()
982 type_param_bounds[type_param_bounds.len() - 1].span().hi()
984 let option = WhereClauseOption::snuggled(&generics_str);
985 let where_clause_str = rewrite_where_clause(
987 &generics.where_clause,
988 context.config.brace_style(),
989 Shape::legacy(where_budget, offset.block_only()),
997 // If the where clause cannot fit on the same line,
998 // put the where clause on a new line
999 if !where_clause_str.contains('\n')
1000 && last_line_width(&result) + where_clause_str.len() + offset.width()
1001 > context.config.comment_width()
1004 let width = offset.block_indent + context.config.tab_spaces() - 1;
1005 let where_indent = Indent::new(0, width);
1006 result.push_str(&where_indent.to_string(context.config));
1008 result.push_str(&where_clause_str);
1010 if generics.where_clause.predicates.is_empty() {
1011 let item_snippet = context.snippet(item.span);
1012 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1014 let comment_hi = body_lo - BytePos(1);
1015 let comment_lo = item.span.lo() + BytePos(lo as u32);
1016 if comment_lo < comment_hi {
1017 match recover_missing_comment_in_span(
1018 mk_sp(comment_lo, comment_hi),
1019 Shape::indented(offset, context.config),
1021 last_line_width(&result),
1023 Some(ref missing_comment) if !missing_comment.is_empty() => {
1024 result.push_str(missing_comment);
1032 match context.config.brace_style() {
1033 _ if last_line_contains_single_line_comment(&result) => {
1035 result.push_str(&offset.to_string(context.config));
1037 BraceStyle::AlwaysNextLine => {
1039 result.push_str(&offset.to_string(context.config));
1041 BraceStyle::PreferSameLine => result.push(' '),
1042 BraceStyle::SameLineWhere => {
1043 if !where_clause_str.is_empty()
1044 && (!trait_items.is_empty() || result.contains('\n'))
1047 result.push_str(&offset.to_string(context.config));
1055 let snippet = context.snippet(item.span);
1056 let open_pos = snippet.find_uncommented("{")? + 1;
1058 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1059 let mut visitor = FmtVisitor::from_context(context);
1060 visitor.block_indent = offset.block_only().block_indent(context.config);
1061 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1063 for item in trait_items {
1064 visitor.visit_trait_item(item);
1067 visitor.format_missing(item.span.hi() - BytePos(1));
1069 let inner_indent_str = visitor.block_indent.to_string(context.config);
1070 let outer_indent_str = offset.block_only().to_string(context.config);
1073 result.push_str(&inner_indent_str);
1074 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1076 result.push_str(&outer_indent_str);
1077 } else if result.contains('\n') {
1088 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1089 let header_str = format_header(p.prefix, p.ident, p.vis);
1090 let generics_str = if let Some(generics) = p.generics {
1091 let hi = if generics.where_clause.predicates.is_empty() {
1094 generics.where_clause.span.hi()
1099 context.config.brace_style(),
1102 mk_sp(generics.span.lo(), hi),
1103 last_line_width(&header_str),
1108 Some(format!("{}{};", header_str, generics_str))
1111 pub fn format_struct_struct(
1112 context: &RewriteContext,
1113 struct_parts: &StructParts,
1114 fields: &[ast::StructField],
1116 one_line_width: Option<usize>,
1117 ) -> Option<String> {
1118 let mut result = String::with_capacity(1024);
1119 let span = struct_parts.span;
1121 let header_str = struct_parts.format_header();
1122 result.push_str(&header_str);
1124 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1125 let body_lo = context.codemap.span_after(span, "{");
1127 let generics_str = match struct_parts.generics {
1128 Some(g) => format_generics(
1131 context.config.brace_style(),
1132 if fields.is_empty() {
1133 BracePos::ForceSameLine
1138 mk_sp(header_hi, body_lo),
1139 last_line_width(&result),
1142 // 3 = ` {}`, 2 = ` {`.
1143 let overhead = if fields.is_empty() { 3 } else { 2 };
1144 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1145 || context.config.max_width() < overhead + result.len()
1147 format!("\n{}{{", offset.block_only().to_string(context.config))
1154 let overhead = if fields.is_empty() { 1 } else { 0 };
1155 let total_width = result.len() + generics_str.len() + overhead;
1156 if !generics_str.is_empty() && !generics_str.contains('\n')
1157 && total_width > context.config.max_width()
1160 result.push_str(&offset.to_string(context.config));
1161 result.push_str(generics_str.trim_left());
1163 result.push_str(&generics_str);
1166 if fields.is_empty() {
1167 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1168 if snippet.trim().is_empty() {
1170 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1172 result.push_str(snippet.trim_right());
1174 result.push_str(&offset.to_string(context.config));
1176 result.push_str(&snippet);
1179 return Some(result);
1183 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1184 let one_line_budget =
1185 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1187 let items_str = rewrite_with_alignment(
1190 Shape::indented(offset, context.config).sub_width(1)?,
1191 mk_sp(body_lo, span.hi()),
1195 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget {
1196 Some(format!("{} {} }}", result, items_str))
1202 .block_indent(context.config)
1203 .to_string(context.config),
1205 offset.to_string(context.config)
1210 /// Returns a bytepos that is after that of `(` in `pub(..)`. If the given visibility does not
1211 /// contain `pub(..)`, then return the `lo` of the `defualt_span`. Yeah, but for what? Well, we need
1212 /// to bypass the `(` in the visibility when creating a span of tuple's body or fn's args.
1213 fn get_bytepos_after_visibility(
1214 context: &RewriteContext,
1215 vis: &ast::Visibility,
1220 ast::Visibility::Crate(s, CrateSugar::PubCrate) => context
1222 .span_after(mk_sp(s.hi(), default_span.hi()), terminator),
1223 ast::Visibility::Crate(s, CrateSugar::JustCrate) => s.hi(),
1224 ast::Visibility::Restricted { ref path, .. } => path.span.hi(),
1225 _ => default_span.lo(),
1229 fn format_tuple_struct(
1230 context: &RewriteContext,
1231 struct_parts: &StructParts,
1232 fields: &[ast::StructField],
1234 ) -> Option<String> {
1235 let mut result = String::with_capacity(1024);
1236 let span = struct_parts.span;
1238 let header_str = struct_parts.format_header();
1239 result.push_str(&header_str);
1241 let body_lo = if fields.is_empty() {
1242 let lo = get_bytepos_after_visibility(context, struct_parts.vis, span, ")");
1243 context.codemap.span_after(mk_sp(lo, span.hi()), "(")
1247 let body_hi = if fields.is_empty() {
1248 context.codemap.span_after(mk_sp(body_lo, span.hi()), ")")
1250 // This is a dirty hack to work around a missing `)` from the span of the last field.
1251 let last_arg_span = fields[fields.len() - 1].span;
1252 if context.snippet(last_arg_span).ends_with(')') {
1257 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1261 let where_clause_str = match struct_parts.generics {
1263 let budget = context.budget(last_line_width(&header_str));
1264 let shape = Shape::legacy(budget, offset);
1265 let g_span = mk_sp(span.lo(), body_lo);
1266 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1267 result.push_str(&generics_str);
1269 let where_budget = context.budget(last_line_width(&result));
1270 let option = WhereClauseOption::new(true, false);
1271 rewrite_where_clause(
1273 &generics.where_clause,
1274 context.config.brace_style(),
1275 Shape::legacy(where_budget, offset.block_only()),
1276 Density::Compressed,
1284 None => "".to_owned(),
1287 if fields.is_empty() {
1289 let used_width = last_line_used_width(&result, offset.width()) + 3;
1290 if used_width > context.config.max_width() {
1292 result.push_str(&offset
1293 .block_indent(context.config)
1294 .to_string(context.config))
1297 let snippet = context.snippet(mk_sp(
1299 context.codemap.span_before(mk_sp(body_lo, span.hi()), ")"),
1301 if snippet.is_empty() {
1303 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1304 result.push_str(snippet.trim_right());
1306 result.push_str(&offset.to_string(context.config));
1308 result.push_str(&snippet);
1312 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1313 let fields = &fields.iter().collect::<Vec<_>>()[..];
1314 let one_line_width = context.config.width_heuristics().fn_call_width;
1315 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1318 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1319 && (result.contains('\n')
1320 || offset.block_indent + result.len() + where_clause_str.len() + 1
1321 > context.config.max_width())
1323 // We need to put the where clause on a new line, but we didn't
1324 // know that earlier, so the where clause will not be indented properly.
1326 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1327 .to_string(context.config));
1329 result.push_str(&where_clause_str);
1334 pub fn rewrite_type_alias(
1335 context: &RewriteContext,
1339 generics: &ast::Generics,
1340 vis: &ast::Visibility,
1342 ) -> Option<String> {
1343 let mut result = String::with_capacity(128);
1345 result.push_str(&format_visibility(vis));
1346 result.push_str("type ");
1347 result.push_str(&ident.to_string());
1350 let shape = Shape::indented(indent + result.len(), context.config).sub_width(2)?;
1351 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo());
1352 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1353 result.push_str(&generics_str);
1355 let where_budget = context.budget(last_line_width(&result));
1356 let option = WhereClauseOption::snuggled(&result);
1357 let where_clause_str = rewrite_where_clause(
1359 &generics.where_clause,
1360 context.config.brace_style(),
1361 Shape::legacy(where_budget, indent),
1369 result.push_str(&where_clause_str);
1370 if where_clause_str.is_empty() {
1371 result.push_str(" = ");
1373 result.push_str(&format!("\n{}= ", indent.to_string(context.config)));
1376 let line_width = last_line_width(&result);
1377 // This checked_sub may fail as the extra space after '=' is not taken into account
1378 // In that case the budget is set to 0 which will make ty.rewrite retry on a new line
1379 let budget = context.budget(indent.width() + line_width + ";".len());
1380 let type_indent = indent + line_width;
1381 // Try to fit the type on the same line
1382 let ty_str = ty.rewrite(context, Shape::legacy(budget, type_indent))
1384 // The line was too short, try to put the type on the next line
1386 // Remove the space after '='
1388 let type_indent = indent.block_indent(context.config);
1390 result.push_str(&type_indent.to_string(context.config));
1391 let budget = context.budget(type_indent.width() + ";".len());
1392 ty.rewrite(context, Shape::legacy(budget, type_indent))
1394 result.push_str(&ty_str);
1395 result.push_str(";");
1399 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1401 if config.space_before_colon() { " " } else { "" },
1402 if config.space_after_colon() { " " } else { "" },
1406 pub fn rewrite_struct_field_prefix(
1407 context: &RewriteContext,
1408 field: &ast::StructField,
1409 ) -> Option<String> {
1410 let vis = format_visibility(&field.vis);
1411 let type_annotation_spacing = type_annotation_spacing(context.config);
1412 Some(match field.ident {
1413 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1414 None => format!("{}", vis),
1418 impl Rewrite for ast::StructField {
1419 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1420 rewrite_struct_field(context, self, shape, 0)
1424 pub fn rewrite_struct_field(
1425 context: &RewriteContext,
1426 field: &ast::StructField,
1428 lhs_max_width: usize,
1429 ) -> Option<String> {
1430 if contains_skip(&field.attrs) {
1431 let snippet = context.snippet(mk_sp(field.attrs[0].span.lo(), field.span.hi()));
1432 return Some(snippet.to_owned());
1435 let type_annotation_spacing = type_annotation_spacing(context.config);
1436 let prefix = rewrite_struct_field_prefix(context, field)?;
1438 let attrs_str = field.attrs.rewrite(context, shape)?;
1439 let attrs_extendable = attrs_str.is_empty()
1440 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
1441 let missing_span = if field.attrs.is_empty() {
1442 mk_sp(field.span.lo(), field.span.lo())
1444 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1446 let mut spacing = String::from(if field.ident.is_some() {
1447 type_annotation_spacing.1
1451 // Try to put everything on a single line.
1452 let attr_prefix = combine_strs_with_missing_comments(
1460 let overhead = last_line_width(&attr_prefix);
1461 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1462 for _ in 0..lhs_offset {
1465 // In this extreme case we will be missing a space betweeen an attribute and a field.
1466 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1469 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1470 let mut orig_ty = field.ty.rewrite(context, ty_shape);
1471 if let Some(ref ty) = orig_ty {
1472 if !ty.contains('\n') {
1473 return Some(attr_prefix + &spacing + ty);
1477 // We must use multiline. We are going to put attributes and a field on different lines.
1479 let rhs_shape = shape.offset_left(last_line_width(&prefix) + 1)?;
1480 orig_ty = field.ty.rewrite(context, rhs_shape);
1481 let field_str = if prefix.is_empty() {
1484 prefix + &choose_rhs(context, &*field.ty, rhs_shape, orig_ty)?
1486 combine_strs_with_missing_comments(context, &attrs_str, &field_str, missing_span, shape, false)
1489 pub struct StaticParts<'a> {
1491 vis: &'a ast::Visibility,
1494 mutability: ast::Mutability,
1495 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1496 defaultness: Option<ast::Defaultness>,
1500 impl<'a> StaticParts<'a> {
1501 pub fn from_item(item: &'a ast::Item) -> Self {
1502 let (prefix, ty, mutability, expr) = match item.node {
1503 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1504 ast::ItemKind::Const(ref ty, ref expr) => {
1505 ("const", ty, ast::Mutability::Immutable, expr)
1507 _ => unreachable!(),
1514 mutability: mutability,
1515 expr_opt: Some(expr),
1521 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1522 let (ty, expr_opt) = match ti.node {
1523 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1524 _ => unreachable!(),
1528 vis: &ast::Visibility::Inherited,
1531 mutability: ast::Mutability::Immutable,
1532 expr_opt: expr_opt.as_ref(),
1538 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1539 let (ty, expr) = match ii.node {
1540 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1541 _ => unreachable!(),
1548 mutability: ast::Mutability::Immutable,
1549 expr_opt: Some(expr),
1550 defaultness: Some(ii.defaultness),
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.defaultness.map_or("", format_defaultness),
1569 static_parts.prefix,
1570 format_mutability(static_parts.mutability),
1576 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1577 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1579 if let Some(expr) = static_parts.expr_opt {
1580 let lhs = format!("{}{} =", prefix, ty_str);
1582 let remaining_width = context.budget(offset.block_indent + 1);
1587 Shape::legacy(remaining_width, offset.block_only()),
1588 ).and_then(|res| recover_comment_removed(res, static_parts.span, context))
1589 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1591 Some(format!("{}{};", prefix, ty_str))
1595 pub fn rewrite_associated_type(
1597 ty_opt: Option<&ptr::P<ast::Ty>>,
1598 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1599 context: &RewriteContext,
1601 ) -> Option<String> {
1602 let prefix = format!("type {}", ident);
1604 let type_bounds_str = if let Some(bounds) = ty_param_bounds_opt {
1606 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1607 let bound_str = bounds
1609 .map(|ty_bound| ty_bound.rewrite(context, shape))
1610 .collect::<Option<Vec<_>>>()?;
1611 if !bounds.is_empty() {
1612 format!(": {}", join_bounds(context, shape, &bound_str))
1620 if let Some(ty) = ty_opt {
1622 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1623 let lhs = format!("{}{} =", prefix, type_bounds_str);
1624 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1626 Some(format!("{}{};", prefix, type_bounds_str))
1630 pub fn rewrite_associated_impl_type(
1632 defaultness: ast::Defaultness,
1633 ty_opt: Option<&ptr::P<ast::Ty>>,
1634 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1635 context: &RewriteContext,
1637 ) -> Option<String> {
1638 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1641 ast::Defaultness::Default => Some(format!("default {}", result)),
1646 impl Rewrite for ast::FunctionRetTy {
1647 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1649 ast::FunctionRetTy::Default(_) => Some(String::new()),
1650 ast::FunctionRetTy::Ty(ref ty) => {
1651 let inner_width = shape.width.checked_sub(3)?;
1652 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1653 .map(|r| format!("-> {}", r))
1659 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1661 ast::TyKind::Infer => {
1662 let original = context.snippet(ty.span);
1669 impl Rewrite for ast::Arg {
1670 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1671 if is_named_arg(self) {
1672 let mut result = self.pat
1673 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1675 if !is_empty_infer(context, &*self.ty) {
1676 if context.config.space_before_colon() {
1677 result.push_str(" ");
1679 result.push_str(":");
1680 if context.config.space_after_colon() {
1681 result.push_str(" ");
1683 let overhead = last_line_width(&result);
1684 let max_width = shape.width.checked_sub(overhead)?;
1685 let ty_str = self.ty
1686 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1687 result.push_str(&ty_str);
1692 self.ty.rewrite(context, shape)
1697 fn rewrite_explicit_self(
1698 explicit_self: &ast::ExplicitSelf,
1700 context: &RewriteContext,
1701 ) -> Option<String> {
1702 match explicit_self.node {
1703 ast::SelfKind::Region(lt, m) => {
1704 let mut_str = format_mutability(m);
1707 let lifetime_str = l.rewrite(
1709 Shape::legacy(context.config.max_width(), Indent::empty()),
1711 Some(format!("&{} {}self", lifetime_str, mut_str))
1713 None => Some(format!("&{}self", mut_str)),
1716 ast::SelfKind::Explicit(ref ty, _) => {
1717 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1719 let mutability = explicit_self_mutability(&args[0]);
1720 let type_str = ty.rewrite(
1722 Shape::legacy(context.config.max_width(), Indent::empty()),
1727 format_mutability(mutability),
1731 ast::SelfKind::Value(_) => {
1732 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1734 let mutability = explicit_self_mutability(&args[0]);
1736 Some(format!("{}self", format_mutability(mutability)))
1741 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1742 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1743 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1744 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1751 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1752 if is_named_arg(arg) {
1759 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1761 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1762 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1763 _ => arg.ty.span.hi(),
1767 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1768 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1769 ident.node != symbol::keywords::Invalid.ident()
1775 // Return type is (result, force_new_line_for_brace)
1777 context: &RewriteContext,
1782 newline_brace: bool,
1784 ) -> Option<(String, bool)> {
1785 let mut force_new_line_for_brace = false;
1787 let where_clause = &fn_sig.generics.where_clause;
1789 let mut result = String::with_capacity(1024);
1790 result.push_str(&fn_sig.to_str(context));
1793 result.push_str("fn ");
1794 result.push_str(&ident.to_string());
1797 let overhead = if has_body && !newline_brace {
1804 let used_width = last_line_used_width(&result, indent.width());
1805 let one_line_budget = context.budget(used_width + overhead);
1807 width: one_line_budget,
1811 let fd = fn_sig.decl;
1812 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1813 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1814 result.push_str(&generics_str);
1816 let snuggle_angle_bracket = generics_str
1819 .map_or(false, |l| l.trim_left().len() == 1);
1821 // Note that the width and indent don't really matter, we'll re-layout the
1822 // return type later anyway.
1823 let ret_str = fd.output
1824 .rewrite(context, Shape::indented(indent, context.config))?;
1826 let multi_line_ret_str = ret_str.contains('\n');
1827 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1830 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1841 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1842 one_line_budget, multi_line_budget, arg_indent
1845 // Check if vertical layout was forced.
1846 if one_line_budget == 0 {
1847 if snuggle_angle_bracket {
1850 result.push_str("(");
1851 if context.config.indent_style() == IndentStyle::Visual {
1853 result.push_str(&arg_indent.to_string(context.config));
1859 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1860 && result.ends_with('(')
1865 // Skip `pub(crate)`.
1866 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1867 // A conservative estimation, to goal is to be over all parens in generics
1868 let args_start = fn_sig
1872 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1873 let args_end = if fd.inputs.is_empty() {
1876 .span_after(mk_sp(args_start, span.hi()), ")")
1878 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1879 context.codemap.span_after(last_span, ")")
1881 let args_span = mk_sp(
1884 .span_after(mk_sp(args_start, span.hi()), "("),
1887 let arg_str = rewrite_args(
1890 fd.get_self().as_ref(),
1897 generics_str.contains('\n'),
1900 let put_args_in_block = match context.config.indent_style() {
1901 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1903 } && !fd.inputs.is_empty();
1905 let mut args_last_line_contains_comment = false;
1906 if put_args_in_block {
1907 arg_indent = indent.block_indent(context.config);
1909 result.push_str(&arg_indent.to_string(context.config));
1910 result.push_str(&arg_str);
1912 result.push_str(&indent.to_string(context.config));
1915 result.push_str(&arg_str);
1916 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1917 // Put the closing brace on the next line if it overflows the max width.
1919 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1922 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1925 // If the last line of args contains comment, we cannot put the closing paren
1926 // on the same line.
1930 .map_or(false, |last_line| last_line.contains("//"))
1932 args_last_line_contains_comment = true;
1934 result.push_str(&arg_indent.to_string(context.config));
1940 if let ast::FunctionRetTy::Ty(..) = fd.output {
1941 let ret_should_indent = match context.config.indent_style() {
1942 // If our args are block layout then we surely must have space.
1943 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1944 _ if args_last_line_contains_comment => false,
1945 _ if result.contains('\n') || multi_line_ret_str => true,
1947 // If the return type would push over the max width, then put the return type on
1948 // a new line. With the +1 for the signature length an additional space between
1949 // the closing parenthesis of the argument and the arrow '->' is considered.
1950 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1952 // If there is no where clause, take into account the space after the return type
1954 if where_clause.predicates.is_empty() {
1958 sig_length > context.config.max_width()
1961 let ret_indent = if ret_should_indent {
1962 let indent = if arg_str.is_empty() {
1963 // Aligning with non-existent args looks silly.
1964 force_new_line_for_brace = true;
1967 // FIXME: we might want to check that using the arg indent
1968 // doesn't blow our budget, and if it does, then fallback to
1969 // the where clause indent.
1974 result.push_str(&indent.to_string(context.config));
1978 Indent::new(indent.block_indent, last_line_width(&result))
1981 if multi_line_ret_str || ret_should_indent {
1982 // Now that we know the proper indent and width, we need to
1983 // re-layout the return type.
1984 let ret_str = fd.output
1985 .rewrite(context, Shape::indented(ret_indent, context.config))?;
1986 result.push_str(&ret_str);
1988 result.push_str(&ret_str);
1991 // Comment between return type and the end of the decl.
1992 let snippet_lo = fd.output.span().hi();
1993 if where_clause.predicates.is_empty() {
1994 let snippet_hi = span.hi();
1995 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
1996 // Try to preserve the layout of the original snippet.
1997 let original_starts_with_newline = snippet
1999 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2000 let original_ends_with_newline = snippet
2001 .rfind(|c| c != ' ')
2002 .map_or(false, |i| snippet[i..].ends_with('\n'));
2003 let snippet = snippet.trim();
2004 if !snippet.is_empty() {
2005 result.push(if original_starts_with_newline {
2010 result.push_str(snippet);
2011 if original_ends_with_newline {
2012 force_new_line_for_brace = true;
2018 let pos_before_where = match fd.output {
2019 ast::FunctionRetTy::Default(..) => args_span.hi(),
2020 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2023 let is_args_multi_lined = arg_str.contains('\n');
2025 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2026 let where_clause_str = rewrite_where_clause(
2029 context.config.brace_style(),
2030 Shape::indented(indent, context.config),
2036 is_args_multi_lined,
2038 // If there are neither where clause nor return type, we may be missing comments between
2040 if where_clause_str.is_empty() {
2041 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2042 match recover_missing_comment_in_span(
2043 mk_sp(args_span.hi(), ret_span.hi()),
2046 last_line_width(&result),
2048 Some(ref missing_comment) if !missing_comment.is_empty() => {
2049 result.push_str(missing_comment);
2050 force_new_line_for_brace = true;
2057 result.push_str(&where_clause_str);
2059 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2060 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2061 Some((result, force_new_line_for_brace))
2064 #[derive(Copy, Clone)]
2065 struct WhereClauseOption {
2066 suppress_comma: bool, // Force no trailing comma
2067 snuggle: bool, // Do not insert newline before `where`
2068 compress_where: bool, // Try single line where clause instead of vertical layout
2071 impl WhereClauseOption {
2072 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2074 suppress_comma: suppress_comma,
2076 compress_where: false,
2080 pub fn snuggled(current: &str) -> WhereClauseOption {
2082 suppress_comma: false,
2083 snuggle: trimmed_last_line_width(current) == 1,
2084 compress_where: false,
2090 context: &RewriteContext,
2092 explicit_self: Option<&ast::ExplicitSelf>,
2093 one_line_budget: usize,
2094 multi_line_budget: usize,
2099 generics_str_contains_newline: bool,
2100 ) -> Option<String> {
2101 let mut arg_item_strs = args.iter()
2102 .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
2103 .collect::<Option<Vec<_>>>()?;
2105 // Account for sugary self.
2106 // FIXME: the comment for the self argument is dropped. This is blocked
2107 // on rust issue #27522.
2108 let min_args = explicit_self
2109 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2110 .map_or(1, |self_str| {
2111 arg_item_strs[0] = self_str;
2115 // Comments between args.
2116 let mut arg_items = Vec::new();
2118 arg_items.push(ListItem::from_str(""));
2121 // FIXME(#21): if there are no args, there might still be a comment, but
2122 // without spans for the comment or parens, there is no chance of
2123 // getting it right. You also don't get to put a comment on self, unless
2125 if args.len() >= min_args || variadic {
2126 let comment_span_start = if min_args == 2 {
2127 let second_arg_start = if arg_has_pattern(&args[1]) {
2128 args[1].pat.span.lo()
2130 args[1].ty.span.lo()
2132 let reduced_span = mk_sp(span.lo(), second_arg_start);
2134 context.codemap.span_after_last(reduced_span, ",")
2139 enum ArgumentKind<'a> {
2140 Regular(&'a ast::Arg),
2144 let variadic_arg = if variadic {
2145 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2146 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2147 Some(ArgumentKind::Variadic(variadic_start))
2152 let more_items = itemize_list(
2154 args[min_args - 1..]
2156 .map(ArgumentKind::Regular)
2157 .chain(variadic_arg),
2161 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2162 ArgumentKind::Variadic(start) => start,
2165 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2166 ArgumentKind::Variadic(start) => start + BytePos(3),
2169 ArgumentKind::Regular(..) => None,
2170 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2177 arg_items.extend(more_items);
2180 let fits_in_one_line = !generics_str_contains_newline
2181 && (arg_items.is_empty()
2182 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2184 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2185 item.item = Some(arg);
2188 let last_line_ends_with_comment = arg_items
2191 .and_then(|item| item.post_comment.as_ref())
2192 .map_or(false, |s| s.trim().starts_with("//"));
2194 let (indent, trailing_comma) = match context.config.indent_style() {
2195 IndentStyle::Block if fits_in_one_line => {
2196 (indent.block_indent(context.config), SeparatorTactic::Never)
2198 IndentStyle::Block => (
2199 indent.block_indent(context.config),
2200 context.config.trailing_comma(),
2202 IndentStyle::Visual if last_line_ends_with_comment => {
2203 (arg_indent, context.config.trailing_comma())
2205 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2208 let tactic = definitive_tactic(
2210 context.config.fn_args_density().to_list_tactic(),
2214 let budget = match tactic {
2215 DefinitiveListTactic::Horizontal => one_line_budget,
2216 _ => multi_line_budget,
2219 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2221 let fmt = ListFormatting {
2224 trailing_separator: if variadic {
2225 SeparatorTactic::Never
2229 separator_place: SeparatorPlace::Back,
2230 shape: Shape::legacy(budget, indent),
2231 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2232 preserve_newline: true,
2233 config: context.config,
2236 write_list(&arg_items, &fmt)
2239 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2240 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2241 ident.node != symbol::keywords::Invalid.ident()
2247 fn compute_budgets_for_args(
2248 context: &RewriteContext,
2252 newline_brace: bool,
2254 force_vertical_layout: bool,
2255 ) -> Option<((usize, usize, Indent))> {
2257 "compute_budgets_for_args {} {:?}, {}, {}",
2263 // Try keeping everything on the same line.
2264 if !result.contains('\n') && !force_vertical_layout {
2265 // 2 = `()`, 3 = `() `, space is before ret_string.
2266 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2267 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2277 let one_line_budget = context.budget(used_space);
2279 if one_line_budget > 0 {
2281 let (indent, multi_line_budget) = match context.config.indent_style() {
2282 IndentStyle::Block => {
2283 let indent = indent.block_indent(context.config);
2284 (indent, context.budget(indent.width() + 1))
2286 IndentStyle::Visual => {
2287 let indent = indent + result.len() + 1;
2288 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2289 (indent, context.budget(multi_line_overhead))
2293 return Some((one_line_budget, multi_line_budget, indent));
2297 // Didn't work. we must force vertical layout and put args on a newline.
2298 let new_indent = indent.block_indent(context.config);
2299 let used_space = match context.config.indent_style() {
2301 IndentStyle::Block => new_indent.width() + 1,
2302 // Account for `)` and possibly ` {`.
2303 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2305 Some((0, context.budget(used_space), new_indent))
2308 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2309 let predicate_count = where_clause.predicates.len();
2311 if config.where_single_line() && predicate_count == 1 {
2314 let brace_style = config.brace_style();
2316 brace_style == BraceStyle::AlwaysNextLine
2317 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2320 fn rewrite_generics(
2321 context: &RewriteContext,
2322 generics: &ast::Generics,
2325 ) -> Option<String> {
2326 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2327 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2328 rewrite_generics_inner(context, generics, g_shape, one_line_width, span)
2329 .or_else(|| rewrite_generics_inner(context, generics, g_shape, 0, span))
2332 fn rewrite_generics_inner(
2333 context: &RewriteContext,
2334 generics: &ast::Generics,
2336 one_line_width: usize,
2338 ) -> Option<String> {
2339 // FIXME: convert bounds to where clauses where they get too big or if
2340 // there is a where clause at all.
2343 enum GenericsArg<'a> {
2344 Lifetime(&'a ast::LifetimeDef),
2345 TyParam(&'a ast::TyParam),
2347 impl<'a> Rewrite for GenericsArg<'a> {
2348 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2350 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2351 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2355 impl<'a> Spanned for GenericsArg<'a> {
2356 fn span(&self) -> Span {
2358 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2359 GenericsArg::TyParam(ty) => ty.span(),
2364 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2365 return Some(String::new());
2368 let generics_args = generics
2371 .map(|lt| GenericsArg::Lifetime(lt))
2372 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2373 let items = itemize_list(
2378 |arg| arg.span().lo(),
2379 |arg| arg.span().hi(),
2380 |arg| arg.rewrite(context, shape),
2381 context.codemap.span_after(span, "<"),
2385 format_generics_item_list(context, items, shape, one_line_width)
2388 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2389 match config.indent_style() {
2390 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2391 IndentStyle::Block => {
2395 .block_indent(config.tab_spaces())
2396 .with_max_width(config)
2402 pub fn format_generics_item_list<I>(
2403 context: &RewriteContext,
2406 one_line_budget: usize,
2409 I: Iterator<Item = ListItem>,
2411 let item_vec = items.collect::<Vec<_>>();
2413 let tactic = definitive_tactic(
2415 ListTactic::HorizontalVertical,
2419 let fmt = ListFormatting {
2422 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2423 SeparatorTactic::Never
2425 context.config.trailing_comma()
2427 separator_place: SeparatorPlace::Back,
2429 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2430 preserve_newline: true,
2431 config: context.config,
2434 let list_str = write_list(&item_vec, &fmt)?;
2436 Some(wrap_generics_with_angle_brackets(
2443 pub fn wrap_generics_with_angle_brackets(
2444 context: &RewriteContext,
2446 list_offset: Indent,
2448 if context.config.indent_style() == IndentStyle::Block
2449 && (list_str.contains('\n') || list_str.ends_with(','))
2453 list_offset.to_string(context.config),
2456 .block_unindent(context.config)
2457 .to_string(context.config)
2459 } else if context.config.spaces_within_parens_and_brackets() {
2460 format!("< {} >", list_str)
2462 format!("<{}>", list_str)
2466 fn rewrite_trait_bounds(
2467 context: &RewriteContext,
2468 bounds: &[ast::TyParamBound],
2470 ) -> Option<String> {
2471 if bounds.is_empty() {
2472 return Some(String::new());
2474 let bound_str = bounds
2476 .map(|ty_bound| ty_bound.rewrite(context, shape))
2477 .collect::<Option<Vec<_>>>()?;
2478 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2481 fn rewrite_where_clause_rfc_style(
2482 context: &RewriteContext,
2483 where_clause: &ast::WhereClause,
2486 span_end: Option<BytePos>,
2487 span_end_before_where: BytePos,
2488 where_clause_option: WhereClauseOption,
2489 is_args_multi_line: bool,
2490 ) -> Option<String> {
2491 let block_shape = shape.block().with_max_width(context.config);
2493 let (span_before, span_after) =
2494 missing_span_before_after_where(span_end_before_where, where_clause);
2495 let (comment_before, comment_after) =
2496 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2498 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2501 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2504 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2506 let clause_shape = clause_shape.sub_width(1)?;
2507 // each clause on one line, trailing comma (except if suppress_comma)
2508 let span_start = where_clause.predicates[0].span().lo();
2509 // If we don't have the start of the next span, then use the end of the
2510 // predicates, but that means we miss comments.
2511 let len = where_clause.predicates.len();
2512 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2513 let span_end = span_end.unwrap_or(end_of_preds);
2514 let items = itemize_list(
2516 where_clause.predicates.iter(),
2519 |pred| pred.span().lo(),
2520 |pred| pred.span().hi(),
2521 |pred| pred.rewrite(context, clause_shape),
2526 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2527 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2528 SeparatorTactic::Never
2530 context.config.trailing_comma()
2533 // shape should be vertical only and only if we have `where_single_line` option enabled
2534 // and the number of items of the where clause is equal to 1
2535 let shape_tactic = if where_single_line {
2536 DefinitiveListTactic::Horizontal
2538 DefinitiveListTactic::Vertical
2541 let fmt = ListFormatting {
2542 tactic: shape_tactic,
2544 trailing_separator: comma_tactic,
2545 separator_place: SeparatorPlace::Back,
2546 shape: clause_shape,
2547 ends_with_newline: true,
2548 preserve_newline: true,
2549 config: context.config,
2551 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2553 let comment_separator = |comment: &str, shape: Shape| {
2554 if comment.is_empty() {
2557 format!("\n{}", shape.indent.to_string(context.config))
2560 let newline_before_where = comment_separator(&comment_before, shape);
2561 let newline_after_where = comment_separator(&comment_after, clause_shape);
2564 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2565 && comment_after.is_empty() && !preds_str.contains('\n')
2566 && 6 + preds_str.len() <= shape.width || where_single_line
2570 format!("\n{}", clause_shape.indent.to_string(context.config))
2573 "{}{}{}where{}{}{}{}",
2576 newline_before_where,
2577 newline_after_where,
2584 fn rewrite_where_clause(
2585 context: &RewriteContext,
2586 where_clause: &ast::WhereClause,
2587 brace_style: BraceStyle,
2591 span_end: Option<BytePos>,
2592 span_end_before_where: BytePos,
2593 where_clause_option: WhereClauseOption,
2594 is_args_multi_line: bool,
2595 ) -> Option<String> {
2596 if where_clause.predicates.is_empty() {
2597 return Some(String::new());
2600 if context.config.indent_style() == IndentStyle::Block {
2601 return rewrite_where_clause_rfc_style(
2607 span_end_before_where,
2608 where_clause_option,
2613 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2615 let offset = match context.config.indent_style() {
2616 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2617 // 6 = "where ".len()
2618 IndentStyle::Visual => shape.indent + extra_indent + 6,
2620 // FIXME: if indent_style != Visual, then the budgets below might
2621 // be out by a char or two.
2623 let budget = context.config.max_width() - offset.width();
2624 let span_start = where_clause.predicates[0].span().lo();
2625 // If we don't have the start of the next span, then use the end of the
2626 // predicates, but that means we miss comments.
2627 let len = where_clause.predicates.len();
2628 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2629 let span_end = span_end.unwrap_or(end_of_preds);
2630 let items = itemize_list(
2632 where_clause.predicates.iter(),
2635 |pred| pred.span().lo(),
2636 |pred| pred.span().hi(),
2637 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2642 let item_vec = items.collect::<Vec<_>>();
2643 // FIXME: we don't need to collect here
2644 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2646 let mut comma_tactic = context.config.trailing_comma();
2647 // Kind of a hack because we don't usually have trailing commas in where clauses.
2648 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2649 comma_tactic = SeparatorTactic::Never;
2652 let fmt = ListFormatting {
2655 trailing_separator: comma_tactic,
2656 separator_place: SeparatorPlace::Back,
2657 shape: Shape::legacy(budget, offset),
2658 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2659 preserve_newline: true,
2660 config: context.config,
2662 let preds_str = write_list(&item_vec, &fmt)?;
2664 let end_length = if terminator == "{" {
2665 // If the brace is on the next line we don't need to count it otherwise it needs two
2668 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2669 BraceStyle::PreferSameLine => 2,
2671 } else if terminator == "=" {
2676 if density == Density::Tall || preds_str.contains('\n')
2677 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2681 (shape.indent + extra_indent).to_string(context.config),
2685 Some(format!(" where {}", preds_str))
2689 fn missing_span_before_after_where(
2690 before_item_span_end: BytePos,
2691 where_clause: &ast::WhereClause,
2693 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2695 let pos_after_where = where_clause.span.lo() + BytePos(5);
2696 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2697 (missing_span_before, missing_span_after)
2700 fn rewrite_comments_before_after_where(
2701 context: &RewriteContext,
2702 span_before_where: Span,
2703 span_after_where: Span,
2705 ) -> Option<(String, String)> {
2706 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2707 let after_comment = rewrite_missing_comment(
2709 shape.block_indent(context.config.tab_spaces()),
2712 Some((before_comment, after_comment))
2715 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2716 format!("{}{}{}", format_visibility(vis), item_name, ident)
2719 #[derive(PartialEq, Eq)]
2727 context: &RewriteContext,
2728 generics: &ast::Generics,
2729 brace_style: BraceStyle,
2730 brace_pos: BracePos,
2734 ) -> Option<String> {
2735 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2736 let mut result = rewrite_generics(context, generics, shape, span)?;
2738 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2739 let budget = context.budget(last_line_used_width(&result, offset.width()));
2740 let mut option = WhereClauseOption::snuggled(&result);
2741 if brace_pos == BracePos::None {
2742 option.suppress_comma = true;
2744 // If the generics are not parameterized then generics.span.hi() == 0,
2745 // so we use span.lo(), which is the position after `struct Foo`.
2746 let span_end_before_where = if generics.is_parameterized() {
2751 let where_clause_str = rewrite_where_clause(
2753 &generics.where_clause,
2755 Shape::legacy(budget, offset.block_only()),
2759 span_end_before_where,
2763 result.push_str(&where_clause_str);
2764 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2765 || (generics.where_clause.predicates.is_empty()
2766 && trimmed_last_line_width(&result) == 1)
2768 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2769 || brace_style != BraceStyle::AlwaysNextLine
2771 if brace_pos == BracePos::None {
2772 return Some(result);
2774 let total_used_width = last_line_used_width(&result, used_width);
2775 let remaining_budget = context.budget(total_used_width);
2776 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2777 // and hence we take the closer into account as well for one line budget.
2778 // We assume that the closer has the same length as the opener.
2779 let overhead = if brace_pos == BracePos::ForceSameLine {
2786 let forbid_same_line_brace = overhead > remaining_budget;
2787 if !forbid_same_line_brace && same_line_brace {
2791 result.push_str(&offset.block_only().to_string(context.config));
2798 impl Rewrite for ast::ForeignItem {
2799 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2800 let attrs_str = self.attrs.rewrite(context, shape)?;
2801 // Drop semicolon or it will be interpreted as comment.
2802 // FIXME: this may be a faulty span from libsyntax.
2803 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2805 let item_str = match self.node {
2806 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2811 &FnSig::new(fn_decl, generics, self.vis.clone()),
2815 ).map(|(s, _)| format!("{};", s))
2817 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2818 // FIXME(#21): we're dropping potential comments in between the
2819 // function keywords here.
2820 let vis = format_visibility(&self.vis);
2821 let mut_str = if is_mutable { "mut " } else { "" };
2822 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2824 let shape = shape.sub_width(1)?;
2825 ty.rewrite(context, shape).map(|ty_str| {
2826 // 1 = space between prefix and type.
2827 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2830 let nested_indent = shape.indent.block_indent(context.config);
2831 format!("\n{}", nested_indent.to_string(context.config))
2833 format!("{}{}{};", prefix, sep, ty_str)
2836 ast::ForeignItemKind::Ty => {
2837 let vis = format_visibility(&self.vis);
2838 Some(format!("{}type {};", vis, self.ident))
2842 let missing_span = if self.attrs.is_empty() {
2843 mk_sp(self.span.lo(), self.span.lo())
2845 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2847 combine_strs_with_missing_comments(