1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Formatting top-level items - functions, structs, enums, traits, impls.
16 use syntax::{abi, ast, ptr, symbol};
17 use syntax::ast::{CrateSugar, ImplItem};
18 use syntax::codemap::{BytePos, Span};
22 use codemap::{LineRangeUtils, SpanUtils};
23 use comment::{combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
24 recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented};
25 use config::{BraceStyle, Config, Density, IndentStyle};
26 use expr::{choose_rhs, format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs,
27 rewrite_call_inner, ExprType};
28 use lists::{definitive_tactic, itemize_list, write_list, DefinitiveListTactic, ListFormatting,
29 ListItem, ListTactic, Separator, SeparatorPlace, SeparatorTactic};
30 use rewrite::{Rewrite, RewriteContext};
31 use shape::{Indent, Shape};
32 use types::join_bounds;
33 use utils::{colon_spaces, contains_skip, end_typaram, first_line_width, format_abi,
34 format_constness, format_defaultness, format_mutability, format_unsafety,
35 format_visibility, is_attributes_extendable, last_line_contains_single_line_comment,
36 last_line_used_width, last_line_width, mk_sp, semicolon_for_expr, starts_with_newline,
37 stmt_expr, trim_newlines, trimmed_last_line_width};
38 use vertical::rewrite_with_alignment;
39 use visitor::FmtVisitor;
41 fn type_annotation_separator(config: &Config) -> &str {
42 colon_spaces(config.space_before_colon(), config.space_after_colon())
45 // Statements of the form
46 // let pat: ty = init;
47 impl Rewrite for ast::Local {
48 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
50 "Local::rewrite {:?} {} {:?}",
56 skip_out_of_file_lines_range!(context, self.span);
58 if contains_skip(&self.attrs) {
62 let attrs_str = self.attrs.rewrite(context, shape)?;
63 let mut result = if attrs_str.is_empty() {
66 combine_strs_with_missing_comments(
71 self.attrs.last().map(|a| a.span.hi()).unwrap(),
80 let pat_shape = shape.offset_left(4)?;
82 let pat_shape = pat_shape.sub_width(1)?;
83 let pat_str = self.pat.rewrite(context, pat_shape)?;
84 result.push_str(&pat_str);
86 // String that is placed within the assignment pattern and expression.
88 let mut infix = String::with_capacity(32);
90 if let Some(ref ty) = self.ty {
91 let separator = type_annotation_separator(context.config);
92 let indent = shape.indent + last_line_width(&result) + separator.len();
94 let budget = shape.width.checked_sub(indent.width() + 1)?;
95 let rewrite = ty.rewrite(context, Shape::legacy(budget, indent))?;
97 infix.push_str(separator);
98 infix.push_str(&rewrite);
101 if self.init.is_some() {
102 infix.push_str(" =");
108 result.push_str(&infix);
110 if let Some(ref ex) = self.init {
111 // 1 = trailing semicolon;
112 let nested_shape = shape.sub_width(1)?;
114 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
122 // TODO convert to using rewrite style rather than visitor
123 // TODO format modules in this style
126 keyword: &'static str,
127 abi: Cow<'static, str>,
128 vis: Option<&'a ast::Visibility>,
129 body: Vec<BodyElement<'a>>,
134 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
137 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
141 .map(|i| BodyElement::ForeignItem(i))
148 enum BodyElement<'a> {
149 // Stmt(&'a ast::Stmt),
150 // Field(&'a ast::Field),
151 // Variant(&'a ast::Variant),
152 // Item(&'a ast::Item),
153 ForeignItem(&'a ast::ForeignItem),
156 /// Represents a fn's signature.
157 pub struct FnSig<'a> {
158 decl: &'a ast::FnDecl,
159 generics: &'a ast::Generics,
161 constness: ast::Constness,
162 defaultness: ast::Defaultness,
163 unsafety: ast::Unsafety,
164 visibility: ast::Visibility,
169 decl: &'a ast::FnDecl,
170 generics: &'a ast::Generics,
171 vis: ast::Visibility,
177 constness: ast::Constness::NotConst,
178 defaultness: ast::Defaultness::Final,
179 unsafety: ast::Unsafety::Normal,
184 pub fn from_method_sig(
185 method_sig: &'a ast::MethodSig,
186 generics: &'a ast::Generics,
189 unsafety: method_sig.unsafety,
190 constness: method_sig.constness.node,
191 defaultness: ast::Defaultness::Final,
193 decl: &*method_sig.decl,
195 visibility: ast::Visibility::Inherited,
200 fn_kind: &'a visit::FnKind,
201 generics: &'a ast::Generics,
202 decl: &'a ast::FnDecl,
203 defualtness: ast::Defaultness,
206 visit::FnKind::ItemFn(_, unsafety, constness, abi, visibility, _) => FnSig {
210 constness: constness.node,
211 defaultness: defualtness,
213 visibility: visibility.clone(),
215 visit::FnKind::Method(_, method_sig, vis, _) => {
216 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
217 fn_sig.defaultness = defualtness;
218 if let Some(vis) = vis {
219 fn_sig.visibility = vis.clone();
227 fn to_str(&self, context: &RewriteContext) -> String {
228 let mut result = String::with_capacity(128);
229 // Vis defaultness constness unsafety abi.
230 result.push_str(&*format_visibility(&self.visibility));
231 result.push_str(format_defaultness(self.defaultness));
232 result.push_str(format_constness(self.constness));
233 result.push_str(format_unsafety(self.unsafety));
234 result.push_str(&format_abi(
236 context.config.force_explicit_abi(),
243 impl<'a> FmtVisitor<'a> {
244 fn format_item(&mut self, item: Item) {
245 self.buffer.push_str(&item.abi);
247 let snippet = self.snippet(item.span);
248 let brace_pos = snippet.find_uncommented("{").unwrap();
250 self.buffer.push_str("{");
251 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
252 // FIXME: this skips comments between the extern keyword and the opening
254 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
255 self.block_indent = self.block_indent.block_indent(self.config);
257 if item.body.is_empty() {
258 self.format_missing_no_indent(item.span.hi() - BytePos(1));
259 self.block_indent = self.block_indent.block_unindent(self.config);
262 .push_str(&self.block_indent.to_string(self.config));
264 for item in &item.body {
265 self.format_body_element(item);
268 self.block_indent = self.block_indent.block_unindent(self.config);
269 self.format_missing_with_indent(item.span.hi() - BytePos(1));
273 self.buffer.push_str("}");
274 self.last_pos = item.span.hi();
277 fn format_body_element(&mut self, element: &BodyElement) {
279 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
283 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
284 let item = Item::from_foreign_mod(fm, span, self.config);
285 self.format_item(item);
289 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
290 let rewrite = item.rewrite(&self.get_context(), self.shape());
291 self.push_rewrite(item.span(), rewrite);
292 self.last_pos = item.span.hi();
302 ) -> Option<String> {
303 let context = self.get_context();
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.same_line_attributes() && is_attributes_extendable(&attrs_str));
571 combine_strs_with_missing_comments(
583 context: &RewriteContext,
586 where_span_end: Option<BytePos>,
587 ) -> Option<String> {
588 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
589 let mut result = String::with_capacity(128);
590 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
591 let indent_str = offset.to_string(context.config);
592 let sep = format!("\n{}", &indent_str);
593 result.push_str(&ref_and_type);
595 let where_budget = if result.contains('\n') {
596 context.config.max_width()
598 context.budget(last_line_width(&result))
600 let option = WhereClauseOption::snuggled(&ref_and_type);
601 let where_clause_str = rewrite_where_clause(
603 &generics.where_clause,
604 context.config.brace_style(),
605 Shape::legacy(where_budget, offset.block_only()),
606 context.config.where_density(),
614 // If there is no where clause, we may have missing comments between the trait name and
615 // the opening brace.
616 if generics.where_clause.predicates.is_empty() {
617 if let Some(hi) = where_span_end {
618 match recover_missing_comment_in_span(
619 mk_sp(self_ty.span.hi(), hi),
620 Shape::indented(offset, context.config),
622 last_line_width(&result),
624 Some(ref missing_comment) if !missing_comment.is_empty() => {
625 result.push_str(missing_comment);
632 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
633 result.push_str(&where_clause_str);
634 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
635 result.push_str(&format!("{}{{{}}}", &sep, &sep));
637 result.push_str(" {}");
642 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
644 let width = offset.block_indent + context.config.tab_spaces() - 1;
645 let where_indent = Indent::new(0, width);
646 result.push_str(&where_indent.to_string(context.config));
648 result.push_str(&where_clause_str);
650 match context.config.brace_style() {
651 _ if last_line_contains_single_line_comment(&result) => result.push_str(&sep),
652 BraceStyle::AlwaysNextLine => result.push_str(&sep),
653 BraceStyle::PreferSameLine => result.push(' '),
654 BraceStyle::SameLineWhere => if !where_clause_str.is_empty() {
655 result.push_str(&sep);
663 let snippet = context.snippet(item.span);
664 let open_pos = snippet.find_uncommented("{")? + 1;
666 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
667 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
668 visitor.block_indent = offset.block_only().block_indent(context.config);
669 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
671 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
673 visitor.visit_impl_item(item);
676 visitor.format_missing(item.span.hi() - BytePos(1));
678 let inner_indent_str = visitor.block_indent.to_string(context.config);
679 let outer_indent_str = offset.block_only().to_string(context.config);
682 result.push_str(&inner_indent_str);
683 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
685 result.push_str(&outer_indent_str);
688 if result.ends_with('{') {
689 result.push_str(&sep);
699 fn is_impl_single_line(
700 context: &RewriteContext,
703 where_clause_str: &str,
706 let snippet = context.snippet(item.span);
707 let open_pos = snippet.find_uncommented("{")? + 1;
710 context.config.impl_empty_single_line() && items.is_empty() && !result.contains('\n')
711 && result.len() + where_clause_str.len() <= context.config.max_width()
712 && !contains_comment(&snippet[open_pos..]),
716 fn format_impl_ref_and_type(
717 context: &RewriteContext,
720 ) -> Option<String> {
721 if let ast::ItemKind::Impl(
731 let mut result = String::with_capacity(128);
733 result.push_str(&format_visibility(&item.vis));
734 result.push_str(format_defaultness(defaultness));
735 result.push_str(format_unsafety(unsafety));
736 result.push_str("impl");
738 let lo = context.codemap.span_after(item.span, "impl");
739 let hi = match *trait_ref {
740 Some(ref tr) => tr.path.span.lo(),
741 None => self_ty.span.lo(),
743 let shape = generics_shape_from_config(
745 Shape::indented(offset + last_line_width(&result), context.config),
748 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
750 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
752 let polarity_str = if polarity == ast::ImplPolarity::Negative {
758 if let Some(ref trait_ref) = *trait_ref {
759 let result_len = result.len();
760 if let Some(trait_ref_str) = rewrite_trait_ref(
769 result.push_str(&trait_ref_str);
772 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
773 result.push_str(&rewrite_trait_ref(
784 result.push_str(&generics_str);
787 // Try to put the self type in a single line.
789 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
790 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
791 // If there is no where clause adapt budget for type formatting to take space and curly
792 // brace into account.
793 match context.config.brace_style() {
794 BraceStyle::AlwaysNextLine => 0,
800 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
801 // 1 = space before the type.
802 let budget = context.budget(used_space + 1);
803 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
804 if !self_ty_str.contains('\n') {
805 if trait_ref.is_some() {
806 result.push_str(" for ");
810 result.push_str(&self_ty_str);
815 // Couldn't fit the self type on a single line, put it on a new line.
817 // Add indentation of one additional tab.
818 let new_line_offset = offset.block_indent(context.config);
819 result.push_str(&new_line_offset.to_string(context.config));
820 if trait_ref.is_some() {
821 result.push_str("for ");
823 let budget = context.budget(last_line_width(&result));
824 let type_offset = match context.config.indent_style() {
825 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
826 IndentStyle::Block => new_line_offset,
828 result.push_str(&*self_ty
829 .rewrite(context, Shape::legacy(budget, type_offset))?);
836 fn rewrite_trait_ref(
837 context: &RewriteContext,
838 trait_ref: &ast::TraitRef,
844 ) -> Option<String> {
845 // 1 = space between generics and trait_ref
846 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
847 let shape = Shape::indented(offset + used_space, context.config);
848 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
849 if !(retry && trait_ref_str.contains('\n')) {
858 // We could not make enough space for trait_ref, so put it on new line.
860 let offset = offset.block_indent(context.config);
861 let shape = Shape::indented(offset, context.config);
862 let trait_ref_str = trait_ref.rewrite(context, shape)?;
866 &offset.to_string(context.config),
875 pub struct StructParts<'a> {
878 vis: &'a ast::Visibility,
879 def: &'a ast::VariantData,
880 generics: Option<&'a ast::Generics>,
884 impl<'a> StructParts<'a> {
885 fn format_header(&self) -> String {
886 format_header(self.prefix, self.ident, self.vis)
889 fn from_variant(variant: &'a ast::Variant) -> Self {
892 ident: variant.node.name,
893 vis: &ast::Visibility::Inherited,
894 def: &variant.node.data,
900 pub fn from_item(item: &'a ast::Item) -> Self {
901 let (prefix, def, generics) = match item.node {
902 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
903 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
911 generics: Some(generics),
918 context: &RewriteContext,
919 struct_parts: &StructParts,
921 one_line_width: Option<usize>,
922 ) -> Option<String> {
923 match *struct_parts.def {
924 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
925 ast::VariantData::Tuple(ref fields, _) => {
926 format_tuple_struct(context, struct_parts, fields, offset)
928 ast::VariantData::Struct(ref fields, _) => {
929 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
934 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
935 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
938 let mut result = String::with_capacity(128);
939 let header = format!(
941 format_visibility(&item.vis),
942 format_unsafety(unsafety),
946 result.push_str(&header);
948 let body_lo = context.codemap.span_after(item.span, "{");
950 let shape = Shape::indented(offset, context.config);
952 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
953 result.push_str(&generics_str);
955 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
956 if !type_param_bounds.is_empty() {
957 let ident_hi = context.codemap.span_after(item.span, &format!("{}", item.ident));
958 let bound_hi = type_param_bounds.last().unwrap().span().hi();
959 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
960 if contains_comment(&snippet) {
964 let trait_bound_str = rewrite_trait_bounds(
967 Shape::indented(offset, context.config),
969 // If the trait, generics, and trait bound cannot fit on the same line,
970 // put the trait bounds on an indented new line
971 if offset.width() + last_line_width(&result) + trait_bound_str.len()
972 > context.config.comment_width()
975 let trait_indent = offset.block_only().block_indent(context.config);
976 result.push_str(&trait_indent.to_string(context.config));
978 result.push_str(&trait_bound_str);
980 let has_body = !trait_items.is_empty();
982 let where_density = if (context.config.where_density() == Density::Compressed
983 && (!result.contains('\n') || context.config.indent_style() == IndentStyle::Block))
984 || (context.config.indent_style() == IndentStyle::Block && result.is_empty())
985 || (context.config.where_density() == Density::CompressedIfEmpty && !has_body
986 && !result.contains('\n'))
993 let where_budget = context.budget(last_line_width(&result));
994 let pos_before_where = if type_param_bounds.is_empty() {
995 generics.where_clause.span.lo()
997 type_param_bounds[type_param_bounds.len() - 1].span().hi()
999 let option = WhereClauseOption::snuggled(&generics_str);
1000 let where_clause_str = rewrite_where_clause(
1002 &generics.where_clause,
1003 context.config.brace_style(),
1004 Shape::legacy(where_budget, offset.block_only()),
1012 // If the where clause cannot fit on the same line,
1013 // put the where clause on a new line
1014 if !where_clause_str.contains('\n')
1015 && last_line_width(&result) + where_clause_str.len() + offset.width()
1016 > context.config.comment_width()
1019 let width = offset.block_indent + context.config.tab_spaces() - 1;
1020 let where_indent = Indent::new(0, width);
1021 result.push_str(&where_indent.to_string(context.config));
1023 result.push_str(&where_clause_str);
1025 if generics.where_clause.predicates.is_empty() {
1026 let item_snippet = context.snippet(item.span);
1027 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1029 let comment_hi = body_lo - BytePos(1);
1030 let comment_lo = item.span.lo() + BytePos(lo as u32);
1031 if comment_lo < comment_hi {
1032 match recover_missing_comment_in_span(
1033 mk_sp(comment_lo, comment_hi),
1034 Shape::indented(offset, context.config),
1036 last_line_width(&result),
1038 Some(ref missing_comment) if !missing_comment.is_empty() => {
1039 result.push_str(missing_comment);
1047 match context.config.brace_style() {
1048 _ if last_line_contains_single_line_comment(&result) => {
1050 result.push_str(&offset.to_string(context.config));
1052 BraceStyle::AlwaysNextLine => {
1054 result.push_str(&offset.to_string(context.config));
1056 BraceStyle::PreferSameLine => result.push(' '),
1057 BraceStyle::SameLineWhere => if !where_clause_str.is_empty()
1058 && (!trait_items.is_empty() || result.contains('\n'))
1061 result.push_str(&offset.to_string(context.config));
1068 let snippet = context.snippet(item.span);
1069 let open_pos = snippet.find_uncommented("{")? + 1;
1071 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1072 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
1073 visitor.block_indent = offset.block_only().block_indent(context.config);
1074 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1076 for item in trait_items {
1077 visitor.visit_trait_item(item);
1080 visitor.format_missing(item.span.hi() - BytePos(1));
1082 let inner_indent_str = visitor.block_indent.to_string(context.config);
1083 let outer_indent_str = offset.block_only().to_string(context.config);
1086 result.push_str(&inner_indent_str);
1087 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1089 result.push_str(&outer_indent_str);
1090 } else if result.contains('\n') {
1101 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1102 let header_str = format_header(p.prefix, p.ident, p.vis);
1103 let generics_str = if let Some(generics) = p.generics {
1104 let hi = if generics.where_clause.predicates.is_empty() {
1107 generics.where_clause.span.hi()
1112 context.config.brace_style(),
1115 mk_sp(generics.span.lo(), hi),
1116 last_line_width(&header_str),
1121 Some(format!("{}{};", header_str, generics_str))
1124 pub fn format_struct_struct(
1125 context: &RewriteContext,
1126 struct_parts: &StructParts,
1127 fields: &[ast::StructField],
1129 one_line_width: Option<usize>,
1130 ) -> Option<String> {
1131 let mut result = String::with_capacity(1024);
1132 let span = struct_parts.span;
1134 let header_str = struct_parts.format_header();
1135 result.push_str(&header_str);
1137 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1138 let body_lo = context.codemap.span_after(span, "{");
1140 let generics_str = match struct_parts.generics {
1141 Some(g) => format_generics(
1144 context.config.brace_style(),
1145 if fields.is_empty() {
1146 BracePos::ForceSameLine
1151 mk_sp(header_hi, body_lo),
1152 last_line_width(&result),
1155 // 3 = ` {}`, 2 = ` {`.
1156 let overhead = if fields.is_empty() { 3 } else { 2 };
1157 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1158 || context.config.max_width() < overhead + result.len()
1160 format!("\n{}{{", offset.block_only().to_string(context.config))
1167 let overhead = if fields.is_empty() { 1 } else { 0 };
1168 let total_width = result.len() + generics_str.len() + overhead;
1169 if !generics_str.is_empty() && !generics_str.contains('\n')
1170 && total_width > context.config.max_width()
1173 result.push_str(&offset.to_string(context.config));
1174 result.push_str(generics_str.trim_left());
1176 result.push_str(&generics_str);
1179 if fields.is_empty() {
1180 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1181 if snippet.trim().is_empty() {
1183 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1185 result.push_str(snippet.trim_right());
1187 result.push_str(&offset.to_string(context.config));
1189 result.push_str(&snippet);
1192 return Some(result);
1196 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1197 let one_line_budget =
1198 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1200 let items_str = rewrite_with_alignment(
1203 Shape::indented(offset, context.config).sub_width(1)?,
1204 mk_sp(body_lo, span.hi()),
1208 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget {
1209 Some(format!("{} {} }}", result, items_str))
1215 .block_indent(context.config)
1216 .to_string(context.config),
1218 offset.to_string(context.config)
1223 /// Returns a bytepos that is after that of `(` in `pub(..)`. If the given visibility does not
1224 /// contain `pub(..)`, then return the `lo` of the `defualt_span`. Yeah, but for what? Well, we need
1225 /// to bypass the `(` in the visibility when creating a span of tuple's body or fn's args.
1226 fn get_bytepos_after_visibility(
1227 context: &RewriteContext,
1228 vis: &ast::Visibility,
1233 ast::Visibility::Crate(s, CrateSugar::PubCrate) => context
1235 .span_after(mk_sp(s.hi(), default_span.hi()), terminator),
1236 ast::Visibility::Crate(s, CrateSugar::JustCrate) => s.hi(),
1237 ast::Visibility::Restricted { ref path, .. } => path.span.hi(),
1238 _ => default_span.lo(),
1242 fn format_tuple_struct(
1243 context: &RewriteContext,
1244 struct_parts: &StructParts,
1245 fields: &[ast::StructField],
1247 ) -> Option<String> {
1248 let mut result = String::with_capacity(1024);
1249 let span = struct_parts.span;
1251 let header_str = struct_parts.format_header();
1252 result.push_str(&header_str);
1254 let body_lo = if fields.is_empty() {
1255 let lo = get_bytepos_after_visibility(context, struct_parts.vis, span, ")");
1256 context.codemap.span_after(mk_sp(lo, span.hi()), "(")
1260 let body_hi = if fields.is_empty() {
1261 context.codemap.span_after(mk_sp(body_lo, span.hi()), ")")
1263 // This is a dirty hack to work around a missing `)` from the span of the last field.
1264 let last_arg_span = fields[fields.len() - 1].span;
1265 if context.snippet(last_arg_span).ends_with(')') {
1270 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1274 let where_clause_str = match struct_parts.generics {
1276 let budget = context.budget(last_line_width(&header_str));
1277 let shape = Shape::legacy(budget, offset);
1278 let g_span = mk_sp(span.lo(), body_lo);
1279 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1280 result.push_str(&generics_str);
1282 let where_budget = context.budget(last_line_width(&result));
1283 let option = WhereClauseOption::new(true, false);
1284 rewrite_where_clause(
1286 &generics.where_clause,
1287 context.config.brace_style(),
1288 Shape::legacy(where_budget, offset.block_only()),
1289 Density::Compressed,
1297 None => "".to_owned(),
1300 if fields.is_empty() {
1302 let used_width = last_line_used_width(&result, offset.width()) + 3;
1303 if used_width > context.config.max_width() {
1305 result.push_str(&offset
1306 .block_indent(context.config)
1307 .to_string(context.config))
1310 let snippet = context.snippet(mk_sp(
1312 context.codemap.span_before(mk_sp(body_lo, span.hi()), ")"),
1314 if snippet.is_empty() {
1316 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1317 result.push_str(snippet.trim_right());
1319 result.push_str(&offset.to_string(context.config));
1321 result.push_str(&snippet);
1325 let shape = Shape::indented(offset, context.config);
1326 let fields = &fields.iter().map(|field| field).collect::<Vec<_>>()[..];
1327 let one_line_width = context.config.fn_call_width();
1328 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1331 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1332 && (result.contains('\n')
1333 || offset.block_indent + result.len() + where_clause_str.len() + 1
1334 > context.config.max_width())
1336 // We need to put the where clause on a new line, but we didn't
1337 // know that earlier, so the where clause will not be indented properly.
1339 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1340 .to_string(context.config));
1342 result.push_str(&where_clause_str);
1347 pub fn rewrite_type_alias(
1348 context: &RewriteContext,
1352 generics: &ast::Generics,
1353 vis: &ast::Visibility,
1355 ) -> Option<String> {
1356 let mut result = String::with_capacity(128);
1358 result.push_str(&format_visibility(vis));
1359 result.push_str("type ");
1360 result.push_str(&ident.to_string());
1363 let shape = Shape::indented(indent + result.len(), context.config).sub_width(2)?;
1364 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo());
1365 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1366 result.push_str(&generics_str);
1368 let where_budget = context.budget(last_line_width(&result));
1369 let option = WhereClauseOption::snuggled(&result);
1370 let where_clause_str = rewrite_where_clause(
1372 &generics.where_clause,
1373 context.config.brace_style(),
1374 Shape::legacy(where_budget, indent),
1375 context.config.where_density(),
1382 result.push_str(&where_clause_str);
1383 if where_clause_str.is_empty() {
1384 result.push_str(" = ");
1386 result.push_str(&format!("\n{}= ", indent.to_string(context.config)));
1389 let line_width = last_line_width(&result);
1390 // This checked_sub may fail as the extra space after '=' is not taken into account
1391 // In that case the budget is set to 0 which will make ty.rewrite retry on a new line
1392 let budget = context.budget(indent.width() + line_width + ";".len());
1393 let type_indent = indent + line_width;
1394 // Try to fit the type on the same line
1395 let ty_str = ty.rewrite(context, Shape::legacy(budget, type_indent))
1397 // The line was too short, try to put the type on the next line
1399 // Remove the space after '='
1401 let type_indent = indent.block_indent(context.config);
1403 result.push_str(&type_indent.to_string(context.config));
1404 let budget = context.budget(type_indent.width() + ";".len());
1405 ty.rewrite(context, Shape::legacy(budget, type_indent))
1407 result.push_str(&ty_str);
1408 result.push_str(";");
1412 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1414 if config.space_before_colon() { " " } else { "" },
1415 if config.space_after_colon() { " " } else { "" },
1419 pub fn rewrite_struct_field_prefix(
1420 context: &RewriteContext,
1421 field: &ast::StructField,
1422 ) -> Option<String> {
1423 let vis = format_visibility(&field.vis);
1424 let type_annotation_spacing = type_annotation_spacing(context.config);
1425 Some(match field.ident {
1426 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1427 None => format!("{}", vis),
1431 impl Rewrite for ast::StructField {
1432 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1433 rewrite_struct_field(context, self, shape, 0)
1437 pub fn rewrite_struct_field(
1438 context: &RewriteContext,
1439 field: &ast::StructField,
1441 lhs_max_width: usize,
1442 ) -> Option<String> {
1443 if contains_skip(&field.attrs) {
1444 return Some(context.snippet(mk_sp(field.attrs[0].span.lo(), field.span.hi())));
1447 let type_annotation_spacing = type_annotation_spacing(context.config);
1448 let prefix = rewrite_struct_field_prefix(context, field)?;
1450 let attrs_str = field.attrs.rewrite(context, shape)?;
1451 let attrs_extendable = attrs_str.is_empty()
1452 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
1453 let missing_span = if field.attrs.is_empty() {
1454 mk_sp(field.span.lo(), field.span.lo())
1456 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1458 let mut spacing = String::from(if field.ident.is_some() {
1459 type_annotation_spacing.1
1463 // Try to put everything on a single line.
1464 let attr_prefix = combine_strs_with_missing_comments(
1472 let overhead = last_line_width(&attr_prefix);
1473 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1474 for _ in 0..lhs_offset {
1477 // In this extreme case we will be missing a space betweeen an attribute and a field.
1478 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1481 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1482 let mut orig_ty = field.ty.rewrite(context, ty_shape);
1483 if let Some(ref ty) = orig_ty {
1484 if !ty.contains('\n') {
1485 return Some(attr_prefix + &spacing + ty);
1489 // We must use multiline. We are going to put attributes and a field on different lines.
1491 let rhs_shape = shape.offset_left(last_line_width(&prefix) + 1)?;
1492 orig_ty = field.ty.rewrite(context, rhs_shape);
1493 let field_str = if prefix.is_empty() {
1496 prefix + &choose_rhs(context, &*field.ty, rhs_shape, orig_ty)?
1498 combine_strs_with_missing_comments(context, &attrs_str, &field_str, missing_span, shape, false)
1501 pub struct StaticParts<'a> {
1503 vis: &'a ast::Visibility,
1506 mutability: ast::Mutability,
1507 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1511 impl<'a> StaticParts<'a> {
1512 pub fn from_item(item: &'a ast::Item) -> Self {
1513 let (prefix, ty, mutability, expr) = match item.node {
1514 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1515 ast::ItemKind::Const(ref ty, ref expr) => {
1516 ("const", ty, ast::Mutability::Immutable, expr)
1518 _ => unreachable!(),
1525 mutability: mutability,
1526 expr_opt: Some(expr),
1531 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1532 let (ty, expr_opt) = match ti.node {
1533 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1534 _ => unreachable!(),
1538 vis: &ast::Visibility::Inherited,
1541 mutability: ast::Mutability::Immutable,
1542 expr_opt: expr_opt.as_ref(),
1547 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1548 let (ty, expr) = match ii.node {
1549 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1550 _ => unreachable!(),
1557 mutability: ast::Mutability::Immutable,
1558 expr_opt: Some(expr),
1565 context: &RewriteContext,
1566 static_parts: &StaticParts,
1568 ) -> Option<String> {
1569 let colon = colon_spaces(
1570 context.config.space_before_colon(),
1571 context.config.space_after_colon(),
1573 let prefix = format!(
1575 format_visibility(static_parts.vis),
1576 static_parts.prefix,
1577 format_mutability(static_parts.mutability),
1583 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1584 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1586 if let Some(expr) = static_parts.expr_opt {
1587 let lhs = format!("{}{} =", prefix, ty_str);
1589 let remaining_width = context.budget(offset.block_indent + 1);
1594 Shape::legacy(remaining_width, offset.block_only()),
1596 recover_comment_removed(res, static_parts.span, context)
1598 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1600 Some(format!("{}{};", prefix, ty_str))
1604 pub fn rewrite_associated_type(
1606 ty_opt: Option<&ptr::P<ast::Ty>>,
1607 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1608 context: &RewriteContext,
1610 ) -> Option<String> {
1611 let prefix = format!("type {}", ident);
1613 let type_bounds_str = if let Some(ref bounds) = ty_param_bounds_opt {
1615 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1616 let bound_str = bounds
1618 .map(|ty_bound| ty_bound.rewrite(context, shape))
1619 .collect::<Option<Vec<_>>>()?;
1620 if !bounds.is_empty() {
1621 format!(": {}", join_bounds(context, shape, &bound_str))
1629 if let Some(ty) = ty_opt {
1631 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1632 let lhs = format!("{}{} =", prefix, type_bounds_str);
1633 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1635 Some(format!("{}{};", prefix, type_bounds_str))
1639 pub fn rewrite_associated_impl_type(
1641 defaultness: ast::Defaultness,
1642 ty_opt: Option<&ptr::P<ast::Ty>>,
1643 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1644 context: &RewriteContext,
1646 ) -> Option<String> {
1647 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1650 ast::Defaultness::Default => Some(format!("default {}", result)),
1655 impl Rewrite for ast::FunctionRetTy {
1656 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1658 ast::FunctionRetTy::Default(_) => Some(String::new()),
1659 ast::FunctionRetTy::Ty(ref ty) => {
1660 let inner_width = shape.width.checked_sub(3)?;
1661 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1662 .map(|r| format!("-> {}", r))
1668 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1670 ast::TyKind::Infer => {
1671 let original = context.snippet(ty.span);
1678 impl Rewrite for ast::Arg {
1679 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1680 if is_named_arg(self) {
1681 let mut result = self.pat
1682 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1684 if !is_empty_infer(context, &*self.ty) {
1685 if context.config.space_before_colon() {
1686 result.push_str(" ");
1688 result.push_str(":");
1689 if context.config.space_after_colon() {
1690 result.push_str(" ");
1692 let overhead = last_line_width(&result);
1693 let max_width = shape.width.checked_sub(overhead)?;
1694 let ty_str = self.ty
1695 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1696 result.push_str(&ty_str);
1701 self.ty.rewrite(context, shape)
1706 fn rewrite_explicit_self(
1707 explicit_self: &ast::ExplicitSelf,
1709 context: &RewriteContext,
1710 ) -> Option<String> {
1711 match explicit_self.node {
1712 ast::SelfKind::Region(lt, m) => {
1713 let mut_str = format_mutability(m);
1716 let lifetime_str = l.rewrite(
1718 Shape::legacy(context.config.max_width(), Indent::empty()),
1720 Some(format!("&{} {}self", lifetime_str, mut_str))
1722 None => Some(format!("&{}self", mut_str)),
1725 ast::SelfKind::Explicit(ref ty, _) => {
1726 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1728 let mutability = explicit_self_mutability(&args[0]);
1729 let type_str = ty.rewrite(
1731 Shape::legacy(context.config.max_width(), Indent::empty()),
1736 format_mutability(mutability),
1740 ast::SelfKind::Value(_) => {
1741 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1743 let mutability = explicit_self_mutability(&args[0]);
1745 Some(format!("{}self", format_mutability(mutability)))
1750 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1751 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1752 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1753 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1760 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1761 if is_named_arg(arg) {
1768 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1770 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1771 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1772 _ => arg.ty.span.hi(),
1776 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1777 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1778 ident.node != symbol::keywords::Invalid.ident()
1784 // Return type is (result, force_new_line_for_brace)
1786 context: &RewriteContext,
1791 newline_brace: bool,
1793 ) -> Option<(String, bool)> {
1794 let mut force_new_line_for_brace = false;
1796 let where_clause = &fn_sig.generics.where_clause;
1798 let mut result = String::with_capacity(1024);
1799 result.push_str(&fn_sig.to_str(context));
1802 result.push_str("fn ");
1803 result.push_str(&ident.to_string());
1806 let overhead = if has_body && !newline_brace {
1813 let used_width = last_line_used_width(&result, indent.width());
1814 let one_line_budget = context.budget(used_width + overhead);
1816 width: one_line_budget,
1820 let fd = fn_sig.decl;
1821 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1822 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1823 result.push_str(&generics_str);
1825 let snuggle_angle_bracket = generics_str
1828 .map_or(false, |l| l.trim_left().len() == 1);
1830 // Note that the width and indent don't really matter, we'll re-layout the
1831 // return type later anyway.
1832 let ret_str = fd.output
1833 .rewrite(context, Shape::indented(indent, context.config))?;
1835 let multi_line_ret_str = ret_str.contains('\n');
1836 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1839 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1850 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1856 // Check if vertical layout was forced.
1857 if one_line_budget == 0 {
1858 if snuggle_angle_bracket {
1861 result.push_str("(");
1862 if context.config.indent_style() == IndentStyle::Visual {
1864 result.push_str(&arg_indent.to_string(context.config));
1870 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1871 && result.ends_with('(')
1876 // Skip `pub(crate)`.
1877 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1878 // A conservative estimation, to goal is to be over all parens in generics
1879 let args_start = fn_sig
1883 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1884 let args_end = if fd.inputs.is_empty() {
1887 .span_after(mk_sp(args_start, span.hi()), ")")
1889 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1890 context.codemap.span_after(last_span, ")")
1892 let args_span = mk_sp(
1895 .span_after(mk_sp(args_start, span.hi()), "("),
1898 let arg_str = rewrite_args(
1901 fd.get_self().as_ref(),
1908 generics_str.contains('\n'),
1911 let put_args_in_block = match context.config.indent_style() {
1912 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1914 } && !fd.inputs.is_empty();
1916 let mut args_last_line_contains_comment = false;
1917 if put_args_in_block {
1918 arg_indent = indent.block_indent(context.config);
1920 result.push_str(&arg_indent.to_string(context.config));
1921 result.push_str(&arg_str);
1923 result.push_str(&indent.to_string(context.config));
1926 result.push_str(&arg_str);
1927 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1928 // Put the closing brace on the next line if it overflows the max width.
1930 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1933 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1936 // If the last line of args contains comment, we cannot put the closing paren
1937 // on the same line.
1941 .map_or(false, |last_line| last_line.contains("//"))
1943 args_last_line_contains_comment = true;
1945 result.push_str(&arg_indent.to_string(context.config));
1951 if let ast::FunctionRetTy::Ty(..) = fd.output {
1952 let ret_should_indent = match context.config.indent_style() {
1953 // If our args are block layout then we surely must have space.
1954 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1955 _ if args_last_line_contains_comment => false,
1956 _ if result.contains('\n') || multi_line_ret_str => true,
1958 // If the return type would push over the max width, then put the return type on
1959 // a new line. With the +1 for the signature length an additional space between
1960 // the closing parenthesis of the argument and the arrow '->' is considered.
1961 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1963 // If there is no where clause, take into account the space after the return type
1965 if where_clause.predicates.is_empty() {
1969 sig_length > context.config.max_width()
1972 let ret_indent = if ret_should_indent {
1973 let indent = if arg_str.is_empty() {
1974 // Aligning with non-existent args looks silly.
1975 force_new_line_for_brace = true;
1978 // FIXME: we might want to check that using the arg indent
1979 // doesn't blow our budget, and if it does, then fallback to
1980 // the where clause indent.
1985 result.push_str(&indent.to_string(context.config));
1989 Indent::new(indent.block_indent, last_line_width(&result))
1992 if multi_line_ret_str || ret_should_indent {
1993 // Now that we know the proper indent and width, we need to
1994 // re-layout the return type.
1995 let ret_str = fd.output
1996 .rewrite(context, Shape::indented(ret_indent, context.config))?;
1997 result.push_str(&ret_str);
1999 result.push_str(&ret_str);
2002 // Comment between return type and the end of the decl.
2003 let snippet_lo = fd.output.span().hi();
2004 if where_clause.predicates.is_empty() {
2005 let snippet_hi = span.hi();
2006 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2007 // Try to preserve the layout of the original snippet.
2008 let original_starts_with_newline = snippet
2010 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2011 let original_ends_with_newline = snippet
2012 .rfind(|c| c != ' ')
2013 .map_or(false, |i| snippet[i..].ends_with('\n'));
2014 let snippet = snippet.trim();
2015 if !snippet.is_empty() {
2016 result.push(if original_starts_with_newline {
2021 result.push_str(snippet);
2022 if original_ends_with_newline {
2023 force_new_line_for_brace = true;
2029 let should_compress_where = match context.config.where_density() {
2030 Density::Compressed => !result.contains('\n'),
2031 Density::CompressedIfEmpty => !has_body && !result.contains('\n'),
2035 let pos_before_where = match fd.output {
2036 ast::FunctionRetTy::Default(..) => args_span.hi(),
2037 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2040 let is_args_multi_lined = arg_str.contains('\n');
2042 if where_clause.predicates.len() == 1 && should_compress_where {
2043 let budget = context.budget(last_line_used_width(&result, indent.width()));
2044 if let Some(where_clause_str) = rewrite_where_clause(
2047 context.config.brace_style(),
2048 Shape::legacy(budget, indent),
2049 Density::Compressed,
2053 WhereClauseOption::compressed(),
2054 is_args_multi_lined,
2056 result.push_str(&where_clause_str);
2057 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2058 return Some((result, force_new_line_for_brace));
2062 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2063 let where_clause_str = rewrite_where_clause(
2066 context.config.brace_style(),
2067 Shape::indented(indent, context.config),
2073 is_args_multi_lined,
2075 // If there are neither where clause nor return type, we may be missing comments between
2077 if where_clause_str.is_empty() {
2078 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2079 match recover_missing_comment_in_span(
2080 mk_sp(args_span.hi(), ret_span.hi()),
2083 last_line_width(&result),
2085 Some(ref missing_comment) if !missing_comment.is_empty() => {
2086 result.push_str(missing_comment);
2087 force_new_line_for_brace = true;
2094 result.push_str(&where_clause_str);
2096 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2097 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2098 Some((result, force_new_line_for_brace))
2101 #[derive(Copy, Clone)]
2102 struct WhereClauseOption {
2103 suppress_comma: bool, // Force no trailing comma
2104 snuggle: bool, // Do not insert newline before `where`
2105 compress_where: bool, // Try single line where clause instead of vertical layout
2108 impl WhereClauseOption {
2109 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2111 suppress_comma: suppress_comma,
2113 compress_where: false,
2117 pub fn compressed() -> WhereClauseOption {
2119 suppress_comma: true,
2121 compress_where: true,
2125 pub fn snuggled(current: &str) -> WhereClauseOption {
2127 suppress_comma: false,
2128 snuggle: trimmed_last_line_width(current) == 1,
2129 compress_where: false,
2135 context: &RewriteContext,
2137 explicit_self: Option<&ast::ExplicitSelf>,
2138 one_line_budget: usize,
2139 multi_line_budget: usize,
2144 generics_str_contains_newline: bool,
2145 ) -> Option<String> {
2146 let mut arg_item_strs = args.iter()
2148 arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent))
2150 .collect::<Option<Vec<_>>>()?;
2152 // Account for sugary self.
2153 // FIXME: the comment for the self argument is dropped. This is blocked
2154 // on rust issue #27522.
2155 let min_args = explicit_self
2156 .and_then(|explicit_self| {
2157 rewrite_explicit_self(explicit_self, args, context)
2159 .map_or(1, |self_str| {
2160 arg_item_strs[0] = self_str;
2164 // Comments between args.
2165 let mut arg_items = Vec::new();
2167 arg_items.push(ListItem::from_str(""));
2170 // FIXME(#21): if there are no args, there might still be a comment, but
2171 // without spans for the comment or parens, there is no chance of
2172 // getting it right. You also don't get to put a comment on self, unless
2174 if args.len() >= min_args || variadic {
2175 let comment_span_start = if min_args == 2 {
2176 let second_arg_start = if arg_has_pattern(&args[1]) {
2177 args[1].pat.span.lo()
2179 args[1].ty.span.lo()
2181 let reduced_span = mk_sp(span.lo(), second_arg_start);
2183 context.codemap.span_after_last(reduced_span, ",")
2188 enum ArgumentKind<'a> {
2189 Regular(&'a ast::Arg),
2193 let variadic_arg = if variadic {
2194 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2195 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2196 Some(ArgumentKind::Variadic(variadic_start))
2201 let more_items = itemize_list(
2203 args[min_args - 1..]
2205 .map(ArgumentKind::Regular)
2206 .chain(variadic_arg),
2210 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2211 ArgumentKind::Variadic(start) => start,
2214 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2215 ArgumentKind::Variadic(start) => start + BytePos(3),
2218 ArgumentKind::Regular(..) => None,
2219 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2226 arg_items.extend(more_items);
2229 let fits_in_one_line = !generics_str_contains_newline
2230 && (arg_items.is_empty()
2231 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2233 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2234 item.item = Some(arg);
2237 let last_line_ends_with_comment = arg_items
2240 .and_then(|item| item.post_comment.as_ref())
2241 .map_or(false, |s| s.trim().starts_with("//"));
2243 let (indent, trailing_comma) = match context.config.indent_style() {
2244 IndentStyle::Block if fits_in_one_line => {
2245 (indent.block_indent(context.config), SeparatorTactic::Never)
2247 IndentStyle::Block => (
2248 indent.block_indent(context.config),
2249 context.config.trailing_comma(),
2251 IndentStyle::Visual if last_line_ends_with_comment => {
2252 (arg_indent, context.config.trailing_comma())
2254 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2257 let tactic = definitive_tactic(
2259 context.config.fn_args_density().to_list_tactic(),
2263 let budget = match tactic {
2264 DefinitiveListTactic::Horizontal => one_line_budget,
2265 _ => multi_line_budget,
2268 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2270 let fmt = ListFormatting {
2273 trailing_separator: if variadic {
2274 SeparatorTactic::Never
2278 separator_place: SeparatorPlace::Back,
2279 shape: Shape::legacy(budget, indent),
2280 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2281 preserve_newline: true,
2282 config: context.config,
2285 write_list(&arg_items, &fmt)
2288 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2289 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2290 ident.node != symbol::keywords::Invalid.ident()
2296 fn compute_budgets_for_args(
2297 context: &RewriteContext,
2301 newline_brace: bool,
2303 force_vertical_layout: bool,
2304 ) -> Option<((usize, usize, Indent))> {
2306 "compute_budgets_for_args {} {:?}, {}, {}",
2312 // Try keeping everything on the same line.
2313 if !result.contains('\n') && !force_vertical_layout {
2314 // 2 = `()`, 3 = `() `, space is before ret_string.
2315 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2316 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2326 let one_line_budget = context.budget(used_space);
2328 if one_line_budget > 0 {
2330 let (indent, multi_line_budget) = match context.config.indent_style() {
2331 IndentStyle::Block => {
2332 let indent = indent.block_indent(context.config);
2333 (indent, context.budget(indent.width() + 1))
2335 IndentStyle::Visual => {
2336 let indent = indent + result.len() + 1;
2337 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2338 (indent, context.budget(multi_line_overhead))
2342 return Some((one_line_budget, multi_line_budget, indent));
2346 // Didn't work. we must force vertical layout and put args on a newline.
2347 let new_indent = indent.block_indent(context.config);
2348 let used_space = match context.config.indent_style() {
2350 IndentStyle::Block => new_indent.width() + 1,
2351 // Account for `)` and possibly ` {`.
2352 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2354 Some((0, context.budget(used_space), new_indent))
2357 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause, has_body: bool) -> bool {
2358 let predicate_count = where_clause.predicates.len();
2360 if config.where_single_line() && predicate_count == 1 {
2363 match (config.brace_style(), config.where_density()) {
2364 (BraceStyle::AlwaysNextLine, _) => true,
2365 (_, Density::Compressed) if predicate_count == 1 => false,
2366 (_, Density::CompressedIfEmpty) if predicate_count == 1 && !has_body => false,
2367 (BraceStyle::SameLineWhere, _) if predicate_count > 0 => true,
2372 fn rewrite_generics(
2373 context: &RewriteContext,
2374 generics: &ast::Generics,
2377 ) -> Option<String> {
2378 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2379 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2380 rewrite_generics_inner(context, generics, g_shape, one_line_width, span).or_else(|| {
2381 rewrite_generics_inner(context, generics, g_shape, 0, span)
2385 fn rewrite_generics_inner(
2386 context: &RewriteContext,
2387 generics: &ast::Generics,
2389 one_line_width: usize,
2391 ) -> Option<String> {
2392 // FIXME: convert bounds to where clauses where they get too big or if
2393 // there is a where clause at all.
2396 enum GenericsArg<'a> {
2397 Lifetime(&'a ast::LifetimeDef),
2398 TyParam(&'a ast::TyParam),
2400 impl<'a> Rewrite for GenericsArg<'a> {
2401 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2403 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2404 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2408 impl<'a> Spanned for GenericsArg<'a> {
2409 fn span(&self) -> Span {
2411 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2412 GenericsArg::TyParam(ty) => ty.span(),
2417 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2418 return Some(String::new());
2421 let generics_args = generics
2424 .map(|lt| GenericsArg::Lifetime(lt))
2425 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2426 let items = itemize_list(
2431 |arg| arg.span().lo(),
2432 |arg| arg.span().hi(),
2433 |arg| arg.rewrite(context, shape),
2434 context.codemap.span_after(span, "<"),
2438 format_generics_item_list(context, items, shape, one_line_width)
2441 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2442 match config.indent_style() {
2443 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2444 IndentStyle::Block => {
2448 .block_indent(config.tab_spaces())
2449 .with_max_width(config)
2455 pub fn format_generics_item_list<I>(
2456 context: &RewriteContext,
2459 one_line_budget: usize,
2462 I: Iterator<Item = ListItem>,
2464 let item_vec = items.collect::<Vec<_>>();
2466 let tactic = definitive_tactic(
2468 ListTactic::HorizontalVertical,
2472 let fmt = ListFormatting {
2475 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2476 SeparatorTactic::Never
2478 context.config.trailing_comma()
2480 separator_place: SeparatorPlace::Back,
2482 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2483 preserve_newline: true,
2484 config: context.config,
2487 let list_str = write_list(&item_vec, &fmt)?;
2489 Some(wrap_generics_with_angle_brackets(
2496 pub fn wrap_generics_with_angle_brackets(
2497 context: &RewriteContext,
2499 list_offset: Indent,
2501 if context.config.indent_style() == IndentStyle::Block
2502 && (list_str.contains('\n') || list_str.ends_with(','))
2506 list_offset.to_string(context.config),
2509 .block_unindent(context.config)
2510 .to_string(context.config)
2512 } else if context.config.spaces_within_parens_and_brackets() {
2513 format!("< {} >", list_str)
2515 format!("<{}>", list_str)
2519 fn rewrite_trait_bounds(
2520 context: &RewriteContext,
2521 type_param_bounds: &ast::TyParamBounds,
2523 ) -> Option<String> {
2524 let bounds: &[_] = type_param_bounds;
2526 if bounds.is_empty() {
2527 return Some(String::new());
2529 let bound_str = bounds
2531 .map(|ty_bound| ty_bound.rewrite(context, shape))
2532 .collect::<Option<Vec<_>>>()?;
2533 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2536 fn rewrite_where_clause_rfc_style(
2537 context: &RewriteContext,
2538 where_clause: &ast::WhereClause,
2541 span_end: Option<BytePos>,
2542 span_end_before_where: BytePos,
2543 where_clause_option: WhereClauseOption,
2544 is_args_multi_line: bool,
2545 ) -> Option<String> {
2546 let block_shape = shape.block().with_max_width(context.config);
2548 let (span_before, span_after) =
2549 missing_span_before_after_where(span_end_before_where, where_clause);
2550 let (comment_before, comment_after) =
2551 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2553 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2556 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2559 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2561 let clause_shape = clause_shape.sub_width(1)?;
2562 // each clause on one line, trailing comma (except if suppress_comma)
2563 let span_start = where_clause.predicates[0].span().lo();
2564 // If we don't have the start of the next span, then use the end of the
2565 // predicates, but that means we miss comments.
2566 let len = where_clause.predicates.len();
2567 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2568 let span_end = span_end.unwrap_or(end_of_preds);
2569 let items = itemize_list(
2571 where_clause.predicates.iter(),
2574 |pred| pred.span().lo(),
2575 |pred| pred.span().hi(),
2576 |pred| pred.rewrite(context, clause_shape),
2581 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2582 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2583 SeparatorTactic::Never
2585 context.config.trailing_comma()
2588 // shape should be vertical only and only if we have `where_single_line` option enabled
2589 // and the number of items of the where clause is equal to 1
2590 let shape_tactic = if where_single_line {
2591 DefinitiveListTactic::Horizontal
2593 DefinitiveListTactic::Vertical
2596 let fmt = ListFormatting {
2597 tactic: shape_tactic,
2599 trailing_separator: comma_tactic,
2600 separator_place: SeparatorPlace::Back,
2601 shape: clause_shape,
2602 ends_with_newline: true,
2603 preserve_newline: true,
2604 config: context.config,
2606 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2608 let comment_separator = |comment: &str, shape: Shape| if comment.is_empty() {
2611 format!("\n{}", shape.indent.to_string(context.config))
2613 let newline_before_where = comment_separator(&comment_before, shape);
2614 let newline_after_where = comment_separator(&comment_after, clause_shape);
2617 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2618 && comment_after.is_empty() && !preds_str.contains('\n')
2619 && 6 + preds_str.len() <= shape.width || where_single_line
2623 format!("\n{}", clause_shape.indent.to_string(context.config))
2626 "{}{}{}where{}{}{}{}",
2629 newline_before_where,
2630 newline_after_where,
2637 fn rewrite_where_clause(
2638 context: &RewriteContext,
2639 where_clause: &ast::WhereClause,
2640 brace_style: BraceStyle,
2644 span_end: Option<BytePos>,
2645 span_end_before_where: BytePos,
2646 where_clause_option: WhereClauseOption,
2647 is_args_multi_line: bool,
2648 ) -> Option<String> {
2649 if where_clause.predicates.is_empty() {
2650 return Some(String::new());
2653 if context.config.indent_style() == IndentStyle::Block {
2654 return rewrite_where_clause_rfc_style(
2660 span_end_before_where,
2661 where_clause_option,
2666 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2668 let offset = match context.config.indent_style() {
2669 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2670 // 6 = "where ".len()
2671 IndentStyle::Visual => shape.indent + extra_indent + 6,
2673 // FIXME: if indent_style != Visual, then the budgets below might
2674 // be out by a char or two.
2676 let budget = context.config.max_width() - offset.width();
2677 let span_start = where_clause.predicates[0].span().lo();
2678 // If we don't have the start of the next span, then use the end of the
2679 // predicates, but that means we miss comments.
2680 let len = where_clause.predicates.len();
2681 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2682 let span_end = span_end.unwrap_or(end_of_preds);
2683 let items = itemize_list(
2685 where_clause.predicates.iter(),
2688 |pred| pred.span().lo(),
2689 |pred| pred.span().hi(),
2690 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2695 let item_vec = items.collect::<Vec<_>>();
2696 // FIXME: we don't need to collect here if the where_layout isn't
2697 // HorizontalVertical.
2698 let tactic = definitive_tactic(
2700 context.config.where_layout(),
2705 let mut comma_tactic = context.config.trailing_comma();
2706 // Kind of a hack because we don't usually have trailing commas in where clauses.
2707 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2708 comma_tactic = SeparatorTactic::Never;
2711 let fmt = ListFormatting {
2714 trailing_separator: comma_tactic,
2715 separator_place: SeparatorPlace::Back,
2716 shape: Shape::legacy(budget, offset),
2717 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2718 preserve_newline: true,
2719 config: context.config,
2721 let preds_str = write_list(&item_vec, &fmt)?;
2723 let end_length = if terminator == "{" {
2724 // If the brace is on the next line we don't need to count it otherwise it needs two
2727 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2728 BraceStyle::PreferSameLine => 2,
2730 } else if terminator == "=" {
2735 if density == Density::Tall || preds_str.contains('\n')
2736 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2740 (shape.indent + extra_indent).to_string(context.config),
2744 Some(format!(" where {}", preds_str))
2748 fn missing_span_before_after_where(
2749 before_item_span_end: BytePos,
2750 where_clause: &ast::WhereClause,
2752 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2754 let pos_after_where = where_clause.span.lo() + BytePos(5);
2755 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2756 (missing_span_before, missing_span_after)
2759 fn rewrite_comments_before_after_where(
2760 context: &RewriteContext,
2761 span_before_where: Span,
2762 span_after_where: Span,
2764 ) -> Option<(String, String)> {
2765 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2766 let after_comment = rewrite_missing_comment(
2768 shape.block_indent(context.config.tab_spaces()),
2771 Some((before_comment, after_comment))
2774 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2775 format!("{}{}{}", format_visibility(vis), item_name, ident)
2778 #[derive(PartialEq, Eq)]
2786 context: &RewriteContext,
2787 generics: &ast::Generics,
2788 brace_style: BraceStyle,
2789 brace_pos: BracePos,
2793 ) -> Option<String> {
2794 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2795 let mut result = rewrite_generics(context, generics, shape, span)?;
2797 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2798 let budget = context.budget(last_line_used_width(&result, offset.width()));
2799 let mut option = WhereClauseOption::snuggled(&result);
2800 if brace_pos == BracePos::None {
2801 option.suppress_comma = true;
2803 // If the generics are not parameterized then generics.span.hi() == 0,
2804 // so we use span.lo(), which is the position after `struct Foo`.
2805 let span_end_before_where = if generics.is_parameterized() {
2810 let where_clause_str = rewrite_where_clause(
2812 &generics.where_clause,
2814 Shape::legacy(budget, offset.block_only()),
2818 span_end_before_where,
2822 result.push_str(&where_clause_str);
2823 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2824 || (generics.where_clause.predicates.is_empty()
2825 && trimmed_last_line_width(&result) == 1)
2827 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2828 || brace_style != BraceStyle::AlwaysNextLine
2830 if brace_pos == BracePos::None {
2831 return Some(result);
2833 let total_used_width = last_line_used_width(&result, used_width);
2834 let remaining_budget = context.budget(total_used_width);
2835 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2836 // and hence we take the closer into account as well for one line budget.
2837 // We assume that the closer has the same length as the opener.
2838 let overhead = if brace_pos == BracePos::ForceSameLine {
2845 let forbid_same_line_brace = overhead > remaining_budget;
2846 if !forbid_same_line_brace && same_line_brace {
2850 result.push_str(&offset.block_only().to_string(context.config));
2857 impl Rewrite for ast::ForeignItem {
2858 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2859 let attrs_str = self.attrs.rewrite(context, shape)?;
2860 // Drop semicolon or it will be interpreted as comment.
2861 // FIXME: this may be a faulty span from libsyntax.
2862 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2864 let item_str = match self.node {
2865 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2870 &FnSig::new(fn_decl, generics, self.vis.clone()),
2874 ).map(|(s, _)| format!("{};", s))
2876 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2877 // FIXME(#21): we're dropping potential comments in between the
2878 // function keywords here.
2879 let vis = format_visibility(&self.vis);
2880 let mut_str = if is_mutable { "mut " } else { "" };
2881 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2883 let shape = shape.sub_width(1)?;
2884 ty.rewrite(context, shape).map(|ty_str| {
2885 // 1 = space between prefix and type.
2886 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2889 let nested_indent = shape.indent.block_indent(context.config);
2890 format!("\n{}", nested_indent.to_string(context.config))
2892 format!("{}{}{};", prefix, sep, ty_str)
2895 ast::ForeignItemKind::Ty => {
2896 let vis = format_visibility(&self.vis);
2897 Some(format!("{}type {};", vis, self.ident))
2901 let missing_span = if self.attrs.is_empty() {
2902 mk_sp(self.span.lo(), self.span.lo())
2904 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2906 combine_strs_with_missing_comments(