1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Formatting top-level items - functions, structs, enums, traits, impls.
16 use syntax::{abi, ast, ptr, symbol};
17 use syntax::ast::{CrateSugar, ImplItem};
18 use syntax::codemap::{BytePos, Span};
22 use codemap::{LineRangeUtils, SpanUtils};
23 use comment::{combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
24 recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented};
25 use config::{BraceStyle, Config, Density, IndentStyle, ReturnIndent};
26 use expr::{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(),
492 |f| if !f.node.attrs.is_empty() {
493 f.node.attrs[0].span.lo()
498 |f| self.format_variant(f, one_line_width),
504 let mut items: Vec<_> = itemize_list_with(self.config.struct_variant_width());
505 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
506 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains("\n"));
507 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains("\n"));
508 if has_multiline_variant && has_single_line_variant {
509 items = itemize_list_with(0);
512 let shape = self.shape().sub_width(2).unwrap();
513 let fmt = ListFormatting {
514 tactic: DefinitiveListTactic::Vertical,
516 trailing_separator: self.config.trailing_comma(),
517 separator_place: SeparatorPlace::Back,
519 ends_with_newline: true,
520 preserve_newline: true,
524 let list = write_list(&items, &fmt)?;
525 result.push_str(&list);
530 // Variant of an enum.
531 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
532 if contains_skip(&field.node.attrs) {
533 let lo = field.node.attrs[0].span.lo();
534 let span = mk_sp(lo, field.span.hi());
535 return Some(self.snippet(span));
538 let context = self.get_context();
539 let indent = self.block_indent;
540 let shape = self.shape();
541 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
546 .map_or(field.span.lo(), |attr| attr.span.hi());
547 let span = mk_sp(lo, field.span.lo());
549 let variant_body = match field.node.data {
550 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => {
551 // FIXME: Should limit the width, as we have a trailing comma
554 &StructParts::from_variant(field),
556 Some(one_line_width),
559 ast::VariantData::Unit(..) => if let Some(ref expr) = field.node.disr_expr {
560 let lhs = format!("{} =", field.node.name);
562 rewrite_assign_rhs(&context, lhs, &**expr, shape.sub_width(1)?)?
564 field.node.name.to_string()
568 let attrs_extendable = attrs_str.is_empty()
569 || (context.config.attributes_on_same_line_as_variant()
570 && 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),
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.attributes_on_same_line_as_field()
1453 && is_attributes_extendable(&attrs_str));
1454 let missing_span = if field.attrs.is_empty() {
1455 mk_sp(field.span.lo(), field.span.lo())
1457 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1459 let mut spacing = String::from(if field.ident.is_some() {
1460 type_annotation_spacing.1
1464 // Try to put everything on a single line.
1465 let attr_prefix = combine_strs_with_missing_comments(
1473 let overhead = last_line_width(&attr_prefix);
1474 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1475 for _ in 0..lhs_offset {
1478 // In this extreme case we will be missing a space betweeen an attribute and a field.
1479 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1482 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1483 if let Some(ref ty) = field.ty.rewrite(context, ty_shape) {
1484 if !ty.contains('\n') {
1485 return Some(attr_prefix + &spacing + ty);
1489 // We must use multiline.
1490 let new_shape = shape.with_max_width(context.config);
1491 let ty_rewritten = field.ty.rewrite(context, new_shape)?;
1493 let field_str = if prefix.is_empty() {
1495 } else if prefix.len() + first_line_width(&ty_rewritten) + 1 <= shape.width {
1496 prefix + " " + &ty_rewritten
1498 let type_offset = shape.indent.block_indent(context.config);
1499 let nested_shape = Shape::indented(type_offset, context.config);
1500 let nested_ty = field.ty.rewrite(context, nested_shape)?;
1501 prefix + "\n" + &type_offset.to_string(context.config) + &nested_ty
1503 combine_strs_with_missing_comments(
1513 pub struct StaticParts<'a> {
1515 vis: &'a ast::Visibility,
1518 mutability: ast::Mutability,
1519 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1523 impl<'a> StaticParts<'a> {
1524 pub fn from_item(item: &'a ast::Item) -> Self {
1525 let (prefix, ty, mutability, expr) = match item.node {
1526 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1527 ast::ItemKind::Const(ref ty, ref expr) => {
1528 ("const", ty, ast::Mutability::Immutable, expr)
1530 _ => unreachable!(),
1537 mutability: mutability,
1538 expr_opt: Some(expr),
1543 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1544 let (ty, expr_opt) = match ti.node {
1545 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1546 _ => unreachable!(),
1550 vis: &ast::Visibility::Inherited,
1553 mutability: ast::Mutability::Immutable,
1554 expr_opt: expr_opt.as_ref(),
1559 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1560 let (ty, expr) = match ii.node {
1561 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1562 _ => unreachable!(),
1569 mutability: ast::Mutability::Immutable,
1570 expr_opt: Some(expr),
1577 context: &RewriteContext,
1578 static_parts: &StaticParts,
1580 ) -> Option<String> {
1581 let colon = colon_spaces(
1582 context.config.space_before_colon(),
1583 context.config.space_after_colon(),
1585 let prefix = format!(
1587 format_visibility(static_parts.vis),
1588 static_parts.prefix,
1589 format_mutability(static_parts.mutability),
1595 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1596 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1598 if let Some(expr) = static_parts.expr_opt {
1599 let lhs = format!("{}{} =", prefix, ty_str);
1601 let remaining_width = context.budget(offset.block_indent + 1);
1606 Shape::legacy(remaining_width, offset.block_only()),
1608 recover_comment_removed(res, static_parts.span, context)
1610 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1612 Some(format!("{}{};", prefix, ty_str))
1616 pub fn rewrite_associated_type(
1618 ty_opt: Option<&ptr::P<ast::Ty>>,
1619 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1620 context: &RewriteContext,
1622 ) -> Option<String> {
1623 let prefix = format!("type {}", ident);
1625 let type_bounds_str = if let Some(ref bounds) = ty_param_bounds_opt {
1627 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1628 let bound_str = bounds
1630 .map(|ty_bound| ty_bound.rewrite(context, shape))
1631 .collect::<Option<Vec<_>>>()?;
1632 if !bounds.is_empty() {
1633 format!(": {}", join_bounds(context, shape, &bound_str))
1641 if let Some(ty) = ty_opt {
1643 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1644 let lhs = format!("{}{} =", prefix, type_bounds_str);
1645 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1647 Some(format!("{}{};", prefix, type_bounds_str))
1651 pub fn rewrite_associated_impl_type(
1653 defaultness: ast::Defaultness,
1654 ty_opt: Option<&ptr::P<ast::Ty>>,
1655 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1656 context: &RewriteContext,
1658 ) -> Option<String> {
1659 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1662 ast::Defaultness::Default => Some(format!("default {}", result)),
1667 impl Rewrite for ast::FunctionRetTy {
1668 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1670 ast::FunctionRetTy::Default(_) => Some(String::new()),
1671 ast::FunctionRetTy::Ty(ref ty) => {
1672 let inner_width = shape.width.checked_sub(3)?;
1673 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1674 .map(|r| format!("-> {}", r))
1680 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1682 ast::TyKind::Infer => {
1683 let original = context.snippet(ty.span);
1690 impl Rewrite for ast::Arg {
1691 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1692 if is_named_arg(self) {
1693 let mut result = self.pat
1694 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1696 if !is_empty_infer(context, &*self.ty) {
1697 if context.config.space_before_colon() {
1698 result.push_str(" ");
1700 result.push_str(":");
1701 if context.config.space_after_colon() {
1702 result.push_str(" ");
1704 let overhead = last_line_width(&result);
1705 let max_width = shape.width.checked_sub(overhead)?;
1706 let ty_str = self.ty
1707 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1708 result.push_str(&ty_str);
1713 self.ty.rewrite(context, shape)
1718 fn rewrite_explicit_self(
1719 explicit_self: &ast::ExplicitSelf,
1721 context: &RewriteContext,
1722 ) -> Option<String> {
1723 match explicit_self.node {
1724 ast::SelfKind::Region(lt, m) => {
1725 let mut_str = format_mutability(m);
1728 let lifetime_str = l.rewrite(
1730 Shape::legacy(context.config.max_width(), Indent::empty()),
1732 Some(format!("&{} {}self", lifetime_str, mut_str))
1734 None => Some(format!("&{}self", mut_str)),
1737 ast::SelfKind::Explicit(ref ty, _) => {
1738 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1740 let mutability = explicit_self_mutability(&args[0]);
1741 let type_str = ty.rewrite(
1743 Shape::legacy(context.config.max_width(), Indent::empty()),
1748 format_mutability(mutability),
1752 ast::SelfKind::Value(_) => {
1753 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1755 let mutability = explicit_self_mutability(&args[0]);
1757 Some(format!("{}self", format_mutability(mutability)))
1762 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1763 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1764 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1765 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1772 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1773 if is_named_arg(arg) {
1780 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1782 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1783 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1784 _ => arg.ty.span.hi(),
1788 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1789 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1790 ident.node != symbol::keywords::Invalid.ident()
1796 // Return type is (result, force_new_line_for_brace)
1798 context: &RewriteContext,
1803 newline_brace: bool,
1805 ) -> Option<(String, bool)> {
1806 let mut force_new_line_for_brace = false;
1808 let where_clause = &fn_sig.generics.where_clause;
1810 let mut result = String::with_capacity(1024);
1811 result.push_str(&fn_sig.to_str(context));
1814 result.push_str("fn ");
1815 result.push_str(&ident.to_string());
1818 let overhead = if has_body && !newline_brace {
1825 let used_width = last_line_used_width(&result, indent.width());
1826 let one_line_budget = context.budget(used_width + overhead);
1828 width: one_line_budget,
1832 let fd = fn_sig.decl;
1833 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1834 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1835 result.push_str(&generics_str);
1837 let snuggle_angle_bracket = generics_str
1840 .map_or(false, |l| l.trim_left().len() == 1);
1842 // Note that the width and indent don't really matter, we'll re-layout the
1843 // return type later anyway.
1844 let ret_str = fd.output
1845 .rewrite(context, Shape::indented(indent, context.config))?;
1847 let multi_line_ret_str = ret_str.contains('\n');
1848 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1851 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1862 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1868 // Check if vertical layout was forced.
1869 if one_line_budget == 0 {
1870 if snuggle_angle_bracket {
1872 } else if context.config.fn_args_paren_newline() {
1874 result.push_str(&arg_indent.to_string(context.config));
1875 if context.config.indent_style() == IndentStyle::Visual {
1876 arg_indent = arg_indent + 1; // extra space for `(`
1880 result.push_str("(");
1881 if context.config.indent_style() == IndentStyle::Visual {
1883 result.push_str(&arg_indent.to_string(context.config));
1889 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1890 && result.ends_with('(')
1895 // Skip `pub(crate)`.
1896 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1897 // A conservative estimation, to goal is to be over all parens in generics
1898 let args_start = fn_sig
1902 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1903 let args_end = if fd.inputs.is_empty() {
1906 .span_after(mk_sp(args_start, span.hi()), ")")
1908 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1909 context.codemap.span_after(last_span, ")")
1911 let args_span = mk_sp(
1914 .span_after(mk_sp(args_start, span.hi()), "("),
1917 let arg_str = rewrite_args(
1920 fd.get_self().as_ref(),
1927 generics_str.contains('\n'),
1930 let put_args_in_block = match context.config.indent_style() {
1931 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1933 } && !fd.inputs.is_empty();
1935 let mut args_last_line_contains_comment = false;
1936 if put_args_in_block {
1937 arg_indent = indent.block_indent(context.config);
1939 result.push_str(&arg_indent.to_string(context.config));
1940 result.push_str(&arg_str);
1942 result.push_str(&indent.to_string(context.config));
1945 result.push_str(&arg_str);
1946 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1947 // Put the closing brace on the next line if it overflows the max width.
1949 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1952 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1955 // If the last line of args contains comment, we cannot put the closing paren
1956 // on the same line.
1960 .map_or(false, |last_line| last_line.contains("//"))
1962 args_last_line_contains_comment = true;
1964 result.push_str(&arg_indent.to_string(context.config));
1970 if let ast::FunctionRetTy::Ty(..) = fd.output {
1971 let ret_should_indent = match context.config.indent_style() {
1972 // If our args are block layout then we surely must have space.
1973 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1974 _ if args_last_line_contains_comment => false,
1975 _ if result.contains('\n') || multi_line_ret_str => true,
1977 // If the return type would push over the max width, then put the return type on
1978 // a new line. With the +1 for the signature length an additional space between
1979 // the closing parenthesis of the argument and the arrow '->' is considered.
1980 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1982 // If there is no where clause, take into account the space after the return type
1984 if where_clause.predicates.is_empty() {
1988 sig_length > context.config.max_width()
1991 let ret_indent = if ret_should_indent {
1992 let indent = match context.config.fn_return_indent() {
1993 ReturnIndent::WithWhereClause => indent + 4,
1994 // Aligning with non-existent args looks silly.
1995 _ if arg_str.is_empty() => {
1996 force_new_line_for_brace = true;
1999 // FIXME: we might want to check that using the arg indent
2000 // doesn't blow our budget, and if it does, then fallback to
2001 // the where clause indent.
2006 result.push_str(&indent.to_string(context.config));
2010 Indent::new(indent.block_indent, last_line_width(&result))
2013 if multi_line_ret_str || ret_should_indent {
2014 // Now that we know the proper indent and width, we need to
2015 // re-layout the return type.
2016 let ret_str = fd.output
2017 .rewrite(context, Shape::indented(ret_indent, context.config))?;
2018 result.push_str(&ret_str);
2020 result.push_str(&ret_str);
2023 // Comment between return type and the end of the decl.
2024 let snippet_lo = fd.output.span().hi();
2025 if where_clause.predicates.is_empty() {
2026 let snippet_hi = span.hi();
2027 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2028 // Try to preserve the layout of the original snippet.
2029 let original_starts_with_newline = snippet
2031 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2032 let original_ends_with_newline = snippet
2033 .rfind(|c| c != ' ')
2034 .map_or(false, |i| snippet[i..].ends_with('\n'));
2035 let snippet = snippet.trim();
2036 if !snippet.is_empty() {
2037 result.push(if original_starts_with_newline {
2042 result.push_str(snippet);
2043 if original_ends_with_newline {
2044 force_new_line_for_brace = true;
2050 let should_compress_where = match context.config.where_density() {
2051 Density::Compressed => !result.contains('\n'),
2052 Density::CompressedIfEmpty => !has_body && !result.contains('\n'),
2056 let pos_before_where = match fd.output {
2057 ast::FunctionRetTy::Default(..) => args_span.hi(),
2058 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2061 let is_args_multi_lined = arg_str.contains('\n');
2063 if where_clause.predicates.len() == 1 && should_compress_where {
2064 let budget = context.budget(last_line_used_width(&result, indent.width()));
2065 if let Some(where_clause_str) = rewrite_where_clause(
2068 context.config.brace_style(),
2069 Shape::legacy(budget, indent),
2070 Density::Compressed,
2074 WhereClauseOption::compressed(),
2075 is_args_multi_lined,
2077 result.push_str(&where_clause_str);
2078 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2079 return Some((result, force_new_line_for_brace));
2083 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2084 let where_clause_str = rewrite_where_clause(
2087 context.config.brace_style(),
2088 Shape::indented(indent, context.config),
2094 is_args_multi_lined,
2096 // If there are neither where clause nor return type, we may be missing comments between
2098 if where_clause_str.is_empty() {
2099 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2100 match recover_missing_comment_in_span(
2101 mk_sp(args_span.hi(), ret_span.hi()),
2104 last_line_width(&result),
2106 Some(ref missing_comment) if !missing_comment.is_empty() => {
2107 result.push_str(missing_comment);
2108 force_new_line_for_brace = true;
2115 result.push_str(&where_clause_str);
2117 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2118 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2119 Some((result, force_new_line_for_brace))
2122 #[derive(Copy, Clone)]
2123 struct WhereClauseOption {
2124 suppress_comma: bool, // Force no trailing comma
2125 snuggle: bool, // Do not insert newline before `where`
2126 compress_where: bool, // Try single line where clause instead of vertical layout
2129 impl WhereClauseOption {
2130 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2132 suppress_comma: suppress_comma,
2134 compress_where: false,
2138 pub fn compressed() -> WhereClauseOption {
2140 suppress_comma: true,
2142 compress_where: true,
2146 pub fn snuggled(current: &str) -> WhereClauseOption {
2148 suppress_comma: false,
2149 snuggle: trimmed_last_line_width(current) == 1,
2150 compress_where: false,
2156 context: &RewriteContext,
2158 explicit_self: Option<&ast::ExplicitSelf>,
2159 one_line_budget: usize,
2160 multi_line_budget: usize,
2165 generics_str_contains_newline: bool,
2166 ) -> Option<String> {
2167 let mut arg_item_strs = args.iter()
2169 arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent))
2171 .collect::<Option<Vec<_>>>()?;
2173 // Account for sugary self.
2174 // FIXME: the comment for the self argument is dropped. This is blocked
2175 // on rust issue #27522.
2176 let min_args = explicit_self
2177 .and_then(|explicit_self| {
2178 rewrite_explicit_self(explicit_self, args, context)
2180 .map_or(1, |self_str| {
2181 arg_item_strs[0] = self_str;
2185 // Comments between args.
2186 let mut arg_items = Vec::new();
2188 arg_items.push(ListItem::from_str(""));
2191 // FIXME(#21): if there are no args, there might still be a comment, but
2192 // without spans for the comment or parens, there is no chance of
2193 // getting it right. You also don't get to put a comment on self, unless
2195 if args.len() >= min_args || variadic {
2196 let comment_span_start = if min_args == 2 {
2197 let second_arg_start = if arg_has_pattern(&args[1]) {
2198 args[1].pat.span.lo()
2200 args[1].ty.span.lo()
2202 let reduced_span = mk_sp(span.lo(), second_arg_start);
2204 context.codemap.span_after_last(reduced_span, ",")
2209 enum ArgumentKind<'a> {
2210 Regular(&'a ast::Arg),
2214 let variadic_arg = if variadic {
2215 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2216 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2217 Some(ArgumentKind::Variadic(variadic_start))
2222 let more_items = itemize_list(
2224 args[min_args - 1..]
2226 .map(ArgumentKind::Regular)
2227 .chain(variadic_arg),
2230 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2231 ArgumentKind::Variadic(start) => start,
2234 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2235 ArgumentKind::Variadic(start) => start + BytePos(3),
2238 ArgumentKind::Regular(..) => None,
2239 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2246 arg_items.extend(more_items);
2249 let fits_in_one_line = !generics_str_contains_newline
2250 && (arg_items.is_empty()
2251 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2253 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2254 item.item = Some(arg);
2257 let last_line_ends_with_comment = arg_items
2260 .and_then(|item| item.post_comment.as_ref())
2261 .map_or(false, |s| s.trim().starts_with("//"));
2263 let (indent, trailing_comma) = match context.config.indent_style() {
2264 IndentStyle::Block if fits_in_one_line => {
2265 (indent.block_indent(context.config), SeparatorTactic::Never)
2267 IndentStyle::Block => (
2268 indent.block_indent(context.config),
2269 context.config.trailing_comma(),
2271 IndentStyle::Visual if last_line_ends_with_comment => {
2272 (arg_indent, context.config.trailing_comma())
2274 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2277 let tactic = definitive_tactic(
2279 context.config.fn_args_density().to_list_tactic(),
2283 let budget = match tactic {
2284 DefinitiveListTactic::Horizontal => one_line_budget,
2285 _ => multi_line_budget,
2288 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2290 let fmt = ListFormatting {
2293 trailing_separator: if variadic {
2294 SeparatorTactic::Never
2298 separator_place: SeparatorPlace::Back,
2299 shape: Shape::legacy(budget, indent),
2300 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2301 preserve_newline: true,
2302 config: context.config,
2305 write_list(&arg_items, &fmt)
2308 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2309 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2310 ident.node != symbol::keywords::Invalid.ident()
2316 fn compute_budgets_for_args(
2317 context: &RewriteContext,
2321 newline_brace: bool,
2323 force_vertical_layout: bool,
2324 ) -> Option<((usize, usize, Indent))> {
2326 "compute_budgets_for_args {} {:?}, {}, {}",
2332 // Try keeping everything on the same line.
2333 if !result.contains('\n') && !force_vertical_layout {
2334 // 2 = `()`, 3 = `() `, space is before ret_string.
2335 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2336 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2346 let one_line_budget = context.budget(used_space);
2348 if one_line_budget > 0 {
2350 let (indent, multi_line_budget) = match context.config.indent_style() {
2351 IndentStyle::Block => {
2352 let indent = indent.block_indent(context.config);
2353 (indent, context.budget(indent.width() + 1))
2355 IndentStyle::Visual => {
2356 let indent = indent + result.len() + 1;
2357 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2358 (indent, context.budget(multi_line_overhead))
2362 return Some((one_line_budget, multi_line_budget, indent));
2366 // Didn't work. we must force vertical layout and put args on a newline.
2367 let new_indent = indent.block_indent(context.config);
2368 let used_space = match context.config.indent_style() {
2370 IndentStyle::Block => new_indent.width() + 1,
2371 // Account for `)` and possibly ` {`.
2372 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2374 Some((0, context.budget(used_space), new_indent))
2377 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause, has_body: bool) -> bool {
2378 let predicate_count = where_clause.predicates.len();
2380 if config.where_single_line() && predicate_count == 1 {
2383 match (config.brace_style(), config.where_density()) {
2384 (BraceStyle::AlwaysNextLine, _) => true,
2385 (_, Density::Compressed) if predicate_count == 1 => false,
2386 (_, Density::CompressedIfEmpty) if predicate_count == 1 && !has_body => false,
2387 (BraceStyle::SameLineWhere, _) if predicate_count > 0 => true,
2392 fn rewrite_generics(
2393 context: &RewriteContext,
2394 generics: &ast::Generics,
2397 ) -> Option<String> {
2398 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2399 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2400 rewrite_generics_inner(context, generics, g_shape, one_line_width, span).or_else(|| {
2401 rewrite_generics_inner(context, generics, g_shape, 0, span)
2405 fn rewrite_generics_inner(
2406 context: &RewriteContext,
2407 generics: &ast::Generics,
2409 one_line_width: usize,
2411 ) -> Option<String> {
2412 // FIXME: convert bounds to where clauses where they get too big or if
2413 // there is a where clause at all.
2416 enum GenericsArg<'a> {
2417 Lifetime(&'a ast::LifetimeDef),
2418 TyParam(&'a ast::TyParam),
2420 impl<'a> Rewrite for GenericsArg<'a> {
2421 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2423 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2424 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2428 impl<'a> Spanned for GenericsArg<'a> {
2429 fn span(&self) -> Span {
2431 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2432 GenericsArg::TyParam(ty) => ty.span(),
2437 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2438 return Some(String::new());
2441 let generics_args = generics
2444 .map(|lt| GenericsArg::Lifetime(lt))
2445 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2446 let items = itemize_list(
2450 |arg| arg.span().lo(),
2451 |arg| arg.span().hi(),
2452 |arg| arg.rewrite(context, shape),
2453 context.codemap.span_after(span, "<"),
2457 format_generics_item_list(context, items, shape, one_line_width)
2460 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2461 match config.indent_style() {
2462 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2463 IndentStyle::Block => {
2467 .block_indent(config.tab_spaces())
2468 .with_max_width(config)
2474 pub fn format_generics_item_list<I>(
2475 context: &RewriteContext,
2478 one_line_budget: usize,
2481 I: Iterator<Item = ListItem>,
2483 let item_vec = items.collect::<Vec<_>>();
2485 let tactic = definitive_tactic(
2487 ListTactic::HorizontalVertical,
2491 let fmt = ListFormatting {
2494 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2495 SeparatorTactic::Never
2497 context.config.trailing_comma()
2499 separator_place: SeparatorPlace::Back,
2501 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2502 preserve_newline: true,
2503 config: context.config,
2506 let list_str = write_list(&item_vec, &fmt)?;
2508 Some(wrap_generics_with_angle_brackets(
2515 pub fn wrap_generics_with_angle_brackets(
2516 context: &RewriteContext,
2518 list_offset: Indent,
2520 if context.config.indent_style() == IndentStyle::Block
2521 && (list_str.contains('\n') || list_str.ends_with(','))
2525 list_offset.to_string(context.config),
2528 .block_unindent(context.config)
2529 .to_string(context.config)
2531 } else if context.config.spaces_within_parens_and_brackets() {
2532 format!("< {} >", list_str)
2534 format!("<{}>", list_str)
2538 fn rewrite_trait_bounds(
2539 context: &RewriteContext,
2540 type_param_bounds: &ast::TyParamBounds,
2542 ) -> Option<String> {
2543 let bounds: &[_] = type_param_bounds;
2545 if bounds.is_empty() {
2546 return Some(String::new());
2548 let bound_str = bounds
2550 .map(|ty_bound| ty_bound.rewrite(context, shape))
2551 .collect::<Option<Vec<_>>>()?;
2552 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2555 fn rewrite_where_clause_rfc_style(
2556 context: &RewriteContext,
2557 where_clause: &ast::WhereClause,
2560 span_end: Option<BytePos>,
2561 span_end_before_where: BytePos,
2562 where_clause_option: WhereClauseOption,
2563 is_args_multi_line: bool,
2564 ) -> Option<String> {
2565 let block_shape = shape.block().with_max_width(context.config);
2567 let (span_before, span_after) =
2568 missing_span_before_after_where(span_end_before_where, where_clause);
2569 let (comment_before, comment_after) =
2570 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2572 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2575 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2578 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2580 let clause_shape = clause_shape.sub_width(1)?;
2581 // each clause on one line, trailing comma (except if suppress_comma)
2582 let span_start = where_clause.predicates[0].span().lo();
2583 // If we don't have the start of the next span, then use the end of the
2584 // predicates, but that means we miss comments.
2585 let len = where_clause.predicates.len();
2586 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2587 let span_end = span_end.unwrap_or(end_of_preds);
2588 let items = itemize_list(
2590 where_clause.predicates.iter(),
2592 |pred| pred.span().lo(),
2593 |pred| pred.span().hi(),
2594 |pred| pred.rewrite(context, clause_shape),
2599 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2600 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2601 SeparatorTactic::Never
2603 context.config.trailing_comma()
2606 // shape should be vertical only and only if we have `where_single_line` option enabled
2607 // and the number of items of the where clause is equal to 1
2608 let shape_tactic = if where_single_line {
2609 DefinitiveListTactic::Horizontal
2611 DefinitiveListTactic::Vertical
2614 let fmt = ListFormatting {
2615 tactic: shape_tactic,
2617 trailing_separator: comma_tactic,
2618 separator_place: SeparatorPlace::Back,
2619 shape: clause_shape,
2620 ends_with_newline: true,
2621 preserve_newline: true,
2622 config: context.config,
2624 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2626 let comment_separator = |comment: &str, shape: Shape| if comment.is_empty() {
2629 format!("\n{}", shape.indent.to_string(context.config))
2631 let newline_before_where = comment_separator(&comment_before, shape);
2632 let newline_after_where = comment_separator(&comment_after, clause_shape);
2635 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2636 && comment_after.is_empty() && !preds_str.contains('\n')
2637 && 6 + preds_str.len() <= shape.width || where_single_line
2641 format!("\n{}", clause_shape.indent.to_string(context.config))
2644 "{}{}{}where{}{}{}{}",
2647 newline_before_where,
2648 newline_after_where,
2655 fn rewrite_where_clause(
2656 context: &RewriteContext,
2657 where_clause: &ast::WhereClause,
2658 brace_style: BraceStyle,
2662 span_end: Option<BytePos>,
2663 span_end_before_where: BytePos,
2664 where_clause_option: WhereClauseOption,
2665 is_args_multi_line: bool,
2666 ) -> Option<String> {
2667 if where_clause.predicates.is_empty() {
2668 return Some(String::new());
2671 if context.config.indent_style() == IndentStyle::Block {
2672 return rewrite_where_clause_rfc_style(
2678 span_end_before_where,
2679 where_clause_option,
2684 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2686 let offset = match context.config.indent_style() {
2687 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2688 // 6 = "where ".len()
2689 IndentStyle::Visual => shape.indent + extra_indent + 6,
2691 // FIXME: if indent_style != Visual, then the budgets below might
2692 // be out by a char or two.
2694 let budget = context.config.max_width() - offset.width();
2695 let span_start = where_clause.predicates[0].span().lo();
2696 // If we don't have the start of the next span, then use the end of the
2697 // predicates, but that means we miss comments.
2698 let len = where_clause.predicates.len();
2699 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2700 let span_end = span_end.unwrap_or(end_of_preds);
2701 let items = itemize_list(
2703 where_clause.predicates.iter(),
2705 |pred| pred.span().lo(),
2706 |pred| pred.span().hi(),
2707 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2712 let item_vec = items.collect::<Vec<_>>();
2713 // FIXME: we don't need to collect here if the where_layout isn't
2714 // HorizontalVertical.
2715 let tactic = definitive_tactic(
2717 context.config.where_layout(),
2722 let mut comma_tactic = context.config.trailing_comma();
2723 // Kind of a hack because we don't usually have trailing commas in where clauses.
2724 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2725 comma_tactic = SeparatorTactic::Never;
2728 let fmt = ListFormatting {
2731 trailing_separator: comma_tactic,
2732 separator_place: SeparatorPlace::Back,
2733 shape: Shape::legacy(budget, offset),
2734 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2735 preserve_newline: true,
2736 config: context.config,
2738 let preds_str = write_list(&item_vec, &fmt)?;
2740 let end_length = if terminator == "{" {
2741 // If the brace is on the next line we don't need to count it otherwise it needs two
2744 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2745 BraceStyle::PreferSameLine => 2,
2747 } else if terminator == "=" {
2752 if density == Density::Tall || preds_str.contains('\n')
2753 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2757 (shape.indent + extra_indent).to_string(context.config),
2761 Some(format!(" where {}", preds_str))
2765 fn missing_span_before_after_where(
2766 before_item_span_end: BytePos,
2767 where_clause: &ast::WhereClause,
2769 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2771 let pos_after_where = where_clause.span.lo() + BytePos(5);
2772 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2773 (missing_span_before, missing_span_after)
2776 fn rewrite_comments_before_after_where(
2777 context: &RewriteContext,
2778 span_before_where: Span,
2779 span_after_where: Span,
2781 ) -> Option<(String, String)> {
2782 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2783 let after_comment = rewrite_missing_comment(
2785 shape.block_indent(context.config.tab_spaces()),
2788 Some((before_comment, after_comment))
2791 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2792 format!("{}{}{}", format_visibility(vis), item_name, ident)
2795 #[derive(PartialEq, Eq)]
2803 context: &RewriteContext,
2804 generics: &ast::Generics,
2805 brace_style: BraceStyle,
2806 brace_pos: BracePos,
2810 ) -> Option<String> {
2811 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2812 let mut result = rewrite_generics(context, generics, shape, span)?;
2814 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2815 let budget = context.budget(last_line_used_width(&result, offset.width()));
2816 let mut option = WhereClauseOption::snuggled(&result);
2817 if brace_pos == BracePos::None {
2818 option.suppress_comma = true;
2820 // If the generics are not parameterized then generics.span.hi() == 0,
2821 // so we use span.lo(), which is the position after `struct Foo`.
2822 let span_end_before_where = if generics.is_parameterized() {
2827 let where_clause_str = rewrite_where_clause(
2829 &generics.where_clause,
2831 Shape::legacy(budget, offset.block_only()),
2835 span_end_before_where,
2839 result.push_str(&where_clause_str);
2840 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2841 || (generics.where_clause.predicates.is_empty()
2842 && trimmed_last_line_width(&result) == 1)
2844 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2845 || brace_style != BraceStyle::AlwaysNextLine
2847 if brace_pos == BracePos::None {
2848 return Some(result);
2850 let total_used_width = last_line_used_width(&result, used_width);
2851 let remaining_budget = context.budget(total_used_width);
2852 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2853 // and hence we take the closer into account as well for one line budget.
2854 // We assume that the closer has the same length as the opener.
2855 let overhead = if brace_pos == BracePos::ForceSameLine {
2862 let forbid_same_line_brace = overhead > remaining_budget;
2863 if !forbid_same_line_brace && same_line_brace {
2867 result.push_str(&offset.block_only().to_string(context.config));
2874 impl Rewrite for ast::ForeignItem {
2875 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2876 let attrs_str = self.attrs.rewrite(context, shape)?;
2877 // Drop semicolon or it will be interpreted as comment.
2878 // FIXME: this may be a faulty span from libsyntax.
2879 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2881 let item_str = match self.node {
2882 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2887 &FnSig::new(fn_decl, generics, self.vis.clone()),
2891 ).map(|(s, _)| format!("{};", s))
2893 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2894 // FIXME(#21): we're dropping potential comments in between the
2895 // function keywords here.
2896 let vis = format_visibility(&self.vis);
2897 let mut_str = if is_mutable { "mut " } else { "" };
2898 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2900 let shape = shape.sub_width(1)?;
2901 ty.rewrite(context, shape).map(|ty_str| {
2902 // 1 = space between prefix and type.
2903 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2906 let nested_indent = shape.indent.block_indent(context.config);
2907 format!("\n{}", nested_indent.to_string(context.config))
2909 format!("{}{}{};", prefix, sep, ty_str)
2912 ast::ForeignItemKind::Ty => {
2913 let vis = format_visibility(&self.vis);
2914 Some(format!("{}type {};", vis, self.ident))
2918 let missing_span = if self.attrs.is_empty() {
2919 mk_sp(self.span.lo(), self.span.lo())
2921 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2923 combine_strs_with_missing_comments(