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.
18 use syntax::{abi, ast, ptr, symbol};
19 use syntax::codemap::{self, 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::{format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs, ExprType};
27 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, ListItem, Separator};
28 use rewrite::{Rewrite, RewriteContext};
30 use shape::{Indent, Shape};
32 use types::join_bounds;
33 use utils::{colon_spaces, contains_skip, first_line_width, format_abi, format_constness,
34 format_defaultness, format_mutability, format_unsafety, format_visibility,
35 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, trimmed_last_line_width};
38 use vertical::rewrite_with_alignment;
39 use visitor::FmtVisitor;
41 const DEFAULT_VISIBILITY: ast::Visibility = codemap::Spanned {
42 node: ast::VisibilityKind::Inherited,
43 span: codemap::DUMMY_SP,
46 fn type_annotation_separator(config: &Config) -> &str {
47 colon_spaces(config.space_before_colon(), config.space_after_colon())
50 // Statements of the form
51 // let pat: ty = init;
52 impl Rewrite for ast::Local {
53 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
55 "Local::rewrite {:?} {} {:?}",
56 self, shape.width, shape.indent
59 skip_out_of_file_lines_range!(context, self.span);
61 if contains_skip(&self.attrs) {
65 let attrs_str = self.attrs.rewrite(context, shape)?;
66 let mut result = if attrs_str.is_empty() {
69 combine_strs_with_missing_comments(
74 self.attrs.last().map(|a| a.span.hi()).unwrap(),
83 let pat_shape = shape.offset_left(4)?;
85 let pat_shape = pat_shape.sub_width(1)?;
86 let pat_str = self.pat.rewrite(context, pat_shape)?;
87 result.push_str(&pat_str);
89 // String that is placed within the assignment pattern and expression.
91 let mut infix = String::with_capacity(32);
93 if let Some(ref ty) = self.ty {
94 let separator = type_annotation_separator(context.config);
95 let indent = shape.indent + last_line_width(&result) + separator.len();
97 let budget = shape.width.checked_sub(indent.width() + 1)?;
98 let rewrite = ty.rewrite(context, Shape::legacy(budget, indent))?;
100 infix.push_str(separator);
101 infix.push_str(&rewrite);
104 if self.init.is_some() {
105 infix.push_str(" =");
111 result.push_str(&infix);
113 if let Some(ref ex) = self.init {
114 // 1 = trailing semicolon;
115 let nested_shape = shape.sub_width(1)?;
117 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
125 // TODO convert to using rewrite style rather than visitor
126 // TODO format modules in this style
129 keyword: &'static str,
130 abi: Cow<'static, str>,
131 vis: Option<&'a ast::Visibility>,
132 body: Vec<BodyElement<'a>>,
137 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
140 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
144 .map(|i| BodyElement::ForeignItem(i))
151 enum BodyElement<'a> {
152 // Stmt(&'a ast::Stmt),
153 // Field(&'a ast::Field),
154 // Variant(&'a ast::Variant),
155 // Item(&'a ast::Item),
156 ForeignItem(&'a ast::ForeignItem),
159 /// Represents a fn's signature.
160 pub struct FnSig<'a> {
161 decl: &'a ast::FnDecl,
162 generics: &'a ast::Generics,
164 constness: ast::Constness,
165 defaultness: ast::Defaultness,
166 unsafety: ast::Unsafety,
167 visibility: ast::Visibility,
172 decl: &'a ast::FnDecl,
173 generics: &'a ast::Generics,
174 vis: ast::Visibility,
180 constness: ast::Constness::NotConst,
181 defaultness: ast::Defaultness::Final,
182 unsafety: ast::Unsafety::Normal,
187 pub fn from_method_sig(
188 method_sig: &'a ast::MethodSig,
189 generics: &'a ast::Generics,
192 unsafety: method_sig.unsafety,
193 constness: method_sig.constness.node,
194 defaultness: ast::Defaultness::Final,
196 decl: &*method_sig.decl,
198 visibility: DEFAULT_VISIBILITY,
203 fn_kind: &'a visit::FnKind,
204 generics: &'a ast::Generics,
205 decl: &'a ast::FnDecl,
206 defualtness: ast::Defaultness,
209 visit::FnKind::ItemFn(_, unsafety, constness, abi, visibility, _) => FnSig {
213 constness: constness.node,
214 defaultness: defualtness,
216 visibility: visibility.clone(),
218 visit::FnKind::Method(_, method_sig, vis, _) => {
219 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
220 fn_sig.defaultness = defualtness;
221 if let Some(vis) = vis {
222 fn_sig.visibility = vis.clone();
230 fn to_str(&self, context: &RewriteContext) -> String {
231 let mut result = String::with_capacity(128);
232 // Vis defaultness constness unsafety abi.
233 result.push_str(&*format_visibility(&self.visibility));
234 result.push_str(format_defaultness(self.defaultness));
235 result.push_str(format_constness(self.constness));
236 result.push_str(format_unsafety(self.unsafety));
237 result.push_str(&format_abi(
239 context.config.force_explicit_abi(),
246 impl<'a> FmtVisitor<'a> {
247 fn format_item(&mut self, item: &Item) {
248 self.buffer.push_str(&item.abi);
250 let snippet = self.snippet(item.span);
251 let brace_pos = snippet.find_uncommented("{").unwrap();
254 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
255 // FIXME: this skips comments between the extern keyword and the opening
257 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
258 self.block_indent = self.block_indent.block_indent(self.config);
260 if item.body.is_empty() {
261 self.format_missing_no_indent(item.span.hi() - BytePos(1));
262 self.block_indent = self.block_indent.block_unindent(self.config);
263 let indent_str = self.block_indent.to_string(self.config);
264 self.push_str(&indent_str);
266 for item in &item.body {
267 self.format_body_element(item);
270 self.block_indent = self.block_indent.block_unindent(self.config);
271 self.format_missing_with_indent(item.span.hi() - BytePos(1));
276 self.last_pos = item.span.hi();
279 fn format_body_element(&mut self, element: &BodyElement) {
281 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
285 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
286 let item = Item::from_foreign_mod(fm, span, self.config);
287 self.format_item(&item);
290 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
291 let rewrite = item.rewrite(&self.get_context(), self.shape());
292 self.push_rewrite(item.span(), rewrite);
293 self.last_pos = item.span.hi();
303 ) -> Option<String> {
304 let context = self.get_context();
306 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
308 let (mut result, force_newline_brace) =
309 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
312 if self.config.brace_style() == BraceStyle::AlwaysNextLine || force_newline_brace
313 || last_line_width(&result) + 2 > self.shape().width
315 newline_brace = true;
316 } else if !result.contains('\n') {
317 newline_brace = false;
320 // Prepare for the function body by possibly adding a newline and
322 // FIXME we'll miss anything between the end of the signature and the
323 // start of the body, but we need more spans from the compiler to solve
326 result.push_str(&indent.to_string_with_newline(self.config));
331 self.single_line_fn(&result, block).or_else(|| Some(result))
334 pub fn rewrite_required_fn(
338 sig: &ast::MethodSig,
339 generics: &ast::Generics,
341 ) -> Option<String> {
342 // Drop semicolon or it will be interpreted as comment.
343 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
344 let context = self.get_context();
346 let (mut result, _) = rewrite_fn_base(
350 &FnSig::from_method_sig(sig, generics),
356 // Re-attach semicolon
362 fn single_line_fn(&self, fn_str: &str, block: &ast::Block) -> Option<String> {
363 if fn_str.contains('\n') {
367 let codemap = self.get_context().codemap;
369 if self.config.empty_item_single_line() && is_empty_block(block, codemap)
370 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
372 return Some(format!("{}{{}}", fn_str));
375 if self.config.fn_single_line() && is_simple_block_stmt(block, codemap) {
377 if let Some(stmt) = block.stmts.first() {
378 match stmt_expr(stmt) {
380 let suffix = if semicolon_for_expr(&self.get_context(), e) {
386 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
388 .or_else(|| Some(self.snippet(e.span).to_owned()))
390 None => stmt.rewrite(&self.get_context(), self.shape()),
397 if let Some(res) = rewrite {
398 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
399 if !res.contains('\n') && width <= self.config.max_width() {
400 return Some(format!("{}{{ {} }}", fn_str, res));
408 pub fn visit_static(&mut self, static_parts: &StaticParts) {
409 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
410 self.push_rewrite(static_parts.span, rewrite);
413 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
414 let is_tuple = struct_parts.def.is_tuple();
415 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
416 .map(|s| if is_tuple { s + ";" } else { s });
417 self.push_rewrite(struct_parts.span, rewrite);
423 vis: &ast::Visibility,
424 enum_def: &ast::EnumDef,
425 generics: &ast::Generics,
428 let enum_header = format_header("enum ", ident, vis);
429 self.push_str(&enum_header);
431 let enum_snippet = self.snippet(span);
432 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
433 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
434 let generics_str = format_generics(
437 self.config.brace_style(),
438 if enum_def.variants.is_empty() {
439 BracePos::ForceSameLine
444 mk_sp(span.lo(), body_start),
445 last_line_width(&enum_header),
447 self.push_str(&generics_str);
449 self.last_pos = body_start;
451 self.block_indent = self.block_indent.block_indent(self.config);
452 let variant_list = self.format_variant_list(enum_def, body_start, span.hi() - BytePos(1));
454 Some(ref body_str) => self.push_str(body_str),
455 None => self.format_missing_no_indent(span.hi() - BytePos(1)),
457 self.block_indent = self.block_indent.block_unindent(self.config);
459 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
460 let indent_str = self.block_indent.to_string(self.config);
461 self.push_str(&indent_str);
464 self.last_pos = span.hi();
467 // Format the body of an enum definition
468 fn format_variant_list(
470 enum_def: &ast::EnumDef,
473 ) -> Option<String> {
474 if enum_def.variants.is_empty() {
477 let mut result = String::with_capacity(1024);
478 let indentation = self.block_indent.to_string_with_newline(self.config);
479 result.push_str(&indentation);
481 let itemize_list_with = |one_line_width: usize| {
483 self.snippet_provider,
484 enum_def.variants.iter(),
488 if !f.node.attrs.is_empty() {
489 f.node.attrs[0].span.lo()
495 |f| self.format_variant(f, one_line_width),
501 let mut items: Vec<_> =
502 itemize_list_with(self.config.width_heuristics().struct_variant_width);
503 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
504 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
505 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
506 if has_multiline_variant && has_single_line_variant {
507 items = itemize_list_with(0);
510 let shape = self.shape().sub_width(2)?;
511 let fmt = ListFormatting {
512 tactic: DefinitiveListTactic::Vertical,
514 trailing_separator: self.config.trailing_comma(),
515 separator_place: SeparatorPlace::Back,
517 ends_with_newline: true,
518 preserve_newline: true,
522 let list = write_list(&items, &fmt)?;
523 result.push_str(&list);
528 // Variant of an enum.
529 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
530 if contains_skip(&field.node.attrs) {
531 let lo = field.node.attrs[0].span.lo();
532 let span = mk_sp(lo, field.span.hi());
533 return Some(self.snippet(span).to_owned());
536 let context = self.get_context();
538 let shape = self.shape().sub_width(1)?;
539 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
544 .map_or(field.span.lo(), |attr| attr.span.hi());
545 let span = mk_sp(lo, field.span.lo());
547 let variant_body = match field.node.data {
548 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
550 &StructParts::from_variant(field),
552 Some(one_line_width),
554 ast::VariantData::Unit(..) => {
555 if let Some(ref expr) = field.node.disr_expr {
556 let lhs = format!("{} =", field.node.name);
557 rewrite_assign_rhs(&context, lhs, &**expr, shape)?
559 field.node.name.to_string()
564 combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
569 context: &RewriteContext,
572 where_span_end: Option<BytePos>,
573 ) -> Option<String> {
574 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
575 let mut result = String::with_capacity(128);
576 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
577 let sep = offset.to_string_with_newline(context.config);
578 result.push_str(&ref_and_type);
580 let where_budget = if result.contains('\n') {
581 context.config.max_width()
583 context.budget(last_line_width(&result))
585 let option = WhereClauseOption::snuggled(&ref_and_type);
586 let where_clause_str = rewrite_where_clause(
588 &generics.where_clause,
589 context.config.brace_style(),
590 Shape::legacy(where_budget, offset.block_only()),
599 // If there is no where clause, we may have missing comments between the trait name and
600 // the opening brace.
601 if generics.where_clause.predicates.is_empty() {
602 if let Some(hi) = where_span_end {
603 match recover_missing_comment_in_span(
604 mk_sp(self_ty.span.hi(), hi),
605 Shape::indented(offset, context.config),
607 last_line_width(&result),
609 Some(ref missing_comment) if !missing_comment.is_empty() => {
610 result.push_str(missing_comment);
617 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
618 result.push_str(&where_clause_str);
619 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
620 result.push_str(&format!("{}{{{}}}", &sep, &sep));
622 result.push_str(" {}");
627 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
628 let width = offset.block_indent + context.config.tab_spaces() - 1;
629 let where_indent = Indent::new(0, width);
630 result.push_str(&where_indent.to_string_with_newline(context.config));
632 result.push_str(&where_clause_str);
634 let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
635 match context.config.brace_style() {
636 _ if need_newline => result.push_str(&sep),
637 BraceStyle::AlwaysNextLine => result.push_str(&sep),
638 BraceStyle::PreferSameLine => result.push(' '),
639 BraceStyle::SameLineWhere => {
640 if !where_clause_str.is_empty() {
641 result.push_str(&sep);
650 let snippet = context.snippet(item.span);
651 let open_pos = snippet.find_uncommented("{")? + 1;
653 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
654 let mut visitor = FmtVisitor::from_context(context);
655 visitor.block_indent = offset.block_only().block_indent(context.config);
656 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
658 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
660 visitor.visit_impl_item(item);
663 visitor.format_missing(item.span.hi() - BytePos(1));
665 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
666 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
668 result.push_str(&inner_indent_str);
669 result.push_str(visitor.buffer.to_string().trim());
670 result.push_str(&outer_indent_str);
673 if result.ends_with('{') {
674 result.push_str(&sep);
684 fn is_impl_single_line(
685 context: &RewriteContext,
686 items: &[ast::ImplItem],
688 where_clause_str: &str,
691 let snippet = context.snippet(item.span);
692 let open_pos = snippet.find_uncommented("{")? + 1;
695 context.config.empty_item_single_line() && items.is_empty() && !result.contains('\n')
696 && result.len() + where_clause_str.len() <= context.config.max_width()
697 && !contains_comment(&snippet[open_pos..]),
701 fn format_impl_ref_and_type(
702 context: &RewriteContext,
705 ) -> Option<String> {
706 if let ast::ItemKind::Impl(
716 let mut result = String::with_capacity(128);
718 result.push_str(&format_visibility(&item.vis));
719 result.push_str(format_defaultness(defaultness));
720 result.push_str(format_unsafety(unsafety));
721 result.push_str("impl");
723 let lo = context.snippet_provider.span_after(item.span, "impl");
724 let hi = match *trait_ref {
725 Some(ref tr) => tr.path.span.lo(),
726 None => self_ty.span.lo(),
728 let shape = generics_shape_from_config(
730 Shape::indented(offset + last_line_width(&result), context.config),
733 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
735 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
737 let polarity_str = if polarity == ast::ImplPolarity::Negative {
743 if let Some(ref trait_ref) = *trait_ref {
744 let result_len = result.len();
745 if let Some(trait_ref_str) = rewrite_trait_ref(
754 result.push_str(&trait_ref_str);
757 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
758 result.push_str(&rewrite_trait_ref(
769 result.push_str(&generics_str);
772 // Try to put the self type in a single line.
774 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
775 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
776 // If there is no where clause adapt budget for type formatting to take space and curly
777 // brace into account.
778 match context.config.brace_style() {
779 BraceStyle::AlwaysNextLine => 0,
785 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
786 // 1 = space before the type.
787 let budget = context.budget(used_space + 1);
788 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
789 if !self_ty_str.contains('\n') {
790 if trait_ref.is_some() {
791 result.push_str(" for ");
795 result.push_str(&self_ty_str);
800 // Couldn't fit the self type on a single line, put it on a new line.
802 // Add indentation of one additional tab.
803 let new_line_offset = offset.block_indent(context.config);
804 result.push_str(&new_line_offset.to_string(context.config));
805 if trait_ref.is_some() {
806 result.push_str("for ");
808 let budget = context.budget(last_line_width(&result));
809 let type_offset = match context.config.indent_style() {
810 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
811 IndentStyle::Block => new_line_offset,
813 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
820 fn rewrite_trait_ref(
821 context: &RewriteContext,
822 trait_ref: &ast::TraitRef,
828 ) -> Option<String> {
829 // 1 = space between generics and trait_ref
830 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
831 let shape = Shape::indented(offset + used_space, context.config);
832 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
833 if !(retry && trait_ref_str.contains('\n')) {
836 generics_str, polarity_str, &trait_ref_str
840 // We could not make enough space for trait_ref, so put it on new line.
842 let offset = offset.block_indent(context.config);
843 let shape = Shape::indented(offset, context.config);
844 let trait_ref_str = trait_ref.rewrite(context, shape)?;
848 &offset.to_string(context.config),
857 pub struct StructParts<'a> {
860 vis: &'a ast::Visibility,
861 def: &'a ast::VariantData,
862 generics: Option<&'a ast::Generics>,
866 impl<'a> StructParts<'a> {
867 fn format_header(&self) -> String {
868 format_header(self.prefix, self.ident, self.vis)
871 fn from_variant(variant: &'a ast::Variant) -> Self {
874 ident: variant.node.name,
875 vis: &DEFAULT_VISIBILITY,
876 def: &variant.node.data,
882 pub fn from_item(item: &'a ast::Item) -> Self {
883 let (prefix, def, generics) = match item.node {
884 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
885 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
893 generics: Some(generics),
900 context: &RewriteContext,
901 struct_parts: &StructParts,
903 one_line_width: Option<usize>,
904 ) -> Option<String> {
905 match *struct_parts.def {
906 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
907 ast::VariantData::Tuple(ref fields, _) => {
908 format_tuple_struct(context, struct_parts, fields, offset)
910 ast::VariantData::Struct(ref fields, _) => {
911 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
916 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
917 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
920 let mut result = String::with_capacity(128);
921 let header = format!(
923 format_visibility(&item.vis),
924 format_unsafety(unsafety),
928 result.push_str(&header);
930 let body_lo = context.snippet_provider.span_after(item.span, "{");
932 let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
934 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
935 result.push_str(&generics_str);
937 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
938 if !type_param_bounds.is_empty() {
939 let ident_hi = context
941 .span_after(item.span, &format!("{}", item.ident));
942 let bound_hi = type_param_bounds.last().unwrap().span().hi();
943 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
944 if contains_comment(snippet) {
948 let trait_bound_str = rewrite_trait_bounds(
951 Shape::indented(offset, context.config),
953 // If the trait, generics, and trait bound cannot fit on the same line,
954 // put the trait bounds on an indented new line
955 if offset.width() + last_line_width(&result) + trait_bound_str.len()
956 > context.config.comment_width()
958 let trait_indent = offset.block_only().block_indent(context.config);
959 result.push_str(&trait_indent.to_string_with_newline(context.config));
961 result.push_str(&trait_bound_str);
964 if context.config.indent_style() == IndentStyle::Block && result.is_empty() {
970 let where_budget = context.budget(last_line_width(&result));
971 let pos_before_where = if type_param_bounds.is_empty() {
972 generics.where_clause.span.lo()
974 type_param_bounds[type_param_bounds.len() - 1].span().hi()
976 let option = WhereClauseOption::snuggled(&generics_str);
977 let where_clause_str = rewrite_where_clause(
979 &generics.where_clause,
980 context.config.brace_style(),
981 Shape::legacy(where_budget, offset.block_only()),
989 // If the where clause cannot fit on the same line,
990 // put the where clause on a new line
991 if !where_clause_str.contains('\n')
992 && last_line_width(&result) + where_clause_str.len() + offset.width()
993 > context.config.comment_width()
995 let width = offset.block_indent + context.config.tab_spaces() - 1;
996 let where_indent = Indent::new(0, width);
997 result.push_str(&where_indent.to_string_with_newline(context.config));
999 result.push_str(&where_clause_str);
1001 if generics.where_clause.predicates.is_empty() {
1002 let item_snippet = context.snippet(item.span);
1003 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1005 let comment_hi = body_lo - BytePos(1);
1006 let comment_lo = item.span.lo() + BytePos(lo as u32);
1007 if comment_lo < comment_hi {
1008 match recover_missing_comment_in_span(
1009 mk_sp(comment_lo, comment_hi),
1010 Shape::indented(offset, context.config),
1012 last_line_width(&result),
1014 Some(ref missing_comment) if !missing_comment.is_empty() => {
1015 result.push_str(missing_comment);
1023 match context.config.brace_style() {
1024 _ if last_line_contains_single_line_comment(&result) => {
1025 result.push_str(&offset.to_string_with_newline(context.config));
1027 BraceStyle::AlwaysNextLine => {
1028 result.push_str(&offset.to_string_with_newline(context.config));
1030 BraceStyle::PreferSameLine => result.push(' '),
1031 BraceStyle::SameLineWhere => {
1032 if !where_clause_str.is_empty()
1033 && (!trait_items.is_empty() || result.contains('\n'))
1035 result.push_str(&offset.to_string_with_newline(context.config));
1043 let snippet = context.snippet(item.span);
1044 let open_pos = snippet.find_uncommented("{")? + 1;
1046 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1047 let mut visitor = FmtVisitor::from_context(context);
1048 visitor.block_indent = offset.block_only().block_indent(context.config);
1049 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1051 for item in trait_items {
1052 visitor.visit_trait_item(item);
1055 visitor.format_missing(item.span.hi() - BytePos(1));
1057 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
1058 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
1060 result.push_str(&inner_indent_str);
1061 result.push_str(visitor.buffer.to_string().trim());
1062 result.push_str(&outer_indent_str);
1063 } else if result.contains('\n') {
1074 pub fn format_trait_alias(
1075 context: &RewriteContext,
1077 generics: &ast::Generics,
1078 ty_param_bounds: &ast::TyParamBounds,
1080 ) -> Option<String> {
1081 let alias = ident.name.as_str();
1082 // 6 = "trait ", 2 = " ="
1083 let g_shape = shape.offset_left(6 + alias.len())?.sub_width(2)?;
1084 let generics_str = rewrite_generics(context, generics, g_shape, generics.span)?;
1085 let lhs = format!("trait {}{} =", alias, generics_str);
1087 rewrite_assign_rhs(context, lhs, ty_param_bounds, shape.sub_width(1)?).map(|s| s + ";")
1090 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1091 let header_str = format_header(p.prefix, p.ident, p.vis);
1092 let generics_str = if let Some(generics) = p.generics {
1093 let hi = if generics.where_clause.predicates.is_empty() {
1096 generics.where_clause.span.hi()
1101 context.config.brace_style(),
1104 mk_sp(generics.span.lo(), hi),
1105 last_line_width(&header_str),
1110 Some(format!("{}{};", header_str, generics_str))
1113 pub fn format_struct_struct(
1114 context: &RewriteContext,
1115 struct_parts: &StructParts,
1116 fields: &[ast::StructField],
1118 one_line_width: Option<usize>,
1119 ) -> Option<String> {
1120 let mut result = String::with_capacity(1024);
1121 let span = struct_parts.span;
1123 let header_str = struct_parts.format_header();
1124 result.push_str(&header_str);
1126 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1127 let body_lo = context.snippet_provider.span_after(span, "{");
1129 let generics_str = match struct_parts.generics {
1130 Some(g) => format_generics(
1133 context.config.brace_style(),
1134 if fields.is_empty() {
1135 BracePos::ForceSameLine
1140 mk_sp(header_hi, body_lo),
1141 last_line_width(&result),
1144 // 3 = ` {}`, 2 = ` {`.
1145 let overhead = if fields.is_empty() { 3 } else { 2 };
1146 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1147 || context.config.max_width() < overhead + result.len()
1149 format!("\n{}{{", offset.block_only().to_string(context.config))
1156 let overhead = if fields.is_empty() { 1 } else { 0 };
1157 let total_width = result.len() + generics_str.len() + overhead;
1158 if !generics_str.is_empty() && !generics_str.contains('\n')
1159 && total_width > context.config.max_width()
1162 result.push_str(&offset.to_string(context.config));
1163 result.push_str(generics_str.trim_left());
1165 result.push_str(&generics_str);
1168 if fields.is_empty() {
1169 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1170 if snippet.trim().is_empty() {
1172 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1174 result.push_str(snippet.trim_right());
1176 result.push_str(&offset.to_string(context.config));
1178 result.push_str(snippet);
1181 return Some(result);
1185 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1186 let one_line_budget =
1187 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1189 let items_str = rewrite_with_alignment(
1192 Shape::indented(offset, context.config).sub_width(1)?,
1193 mk_sp(body_lo, span.hi()),
1197 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget
1198 && !last_line_contains_single_line_comment(&items_str)
1200 Some(format!("{} {} }}", result, items_str))
1206 .block_indent(context.config)
1207 .to_string(context.config),
1209 offset.to_string(context.config)
1214 fn get_bytepos_after_visibility(vis: &ast::Visibility, default_span: Span) -> BytePos {
1216 ast::VisibilityKind::Crate(..) | ast::VisibilityKind::Restricted { .. } => vis.span.hi(),
1217 _ => default_span.lo(),
1221 fn format_tuple_struct(
1222 context: &RewriteContext,
1223 struct_parts: &StructParts,
1224 fields: &[ast::StructField],
1226 ) -> Option<String> {
1227 let mut result = String::with_capacity(1024);
1228 let span = struct_parts.span;
1230 let header_str = struct_parts.format_header();
1231 result.push_str(&header_str);
1233 let body_lo = if fields.is_empty() {
1234 let lo = get_bytepos_after_visibility(struct_parts.vis, span);
1237 .span_after(mk_sp(lo, span.hi()), "(")
1241 let body_hi = if fields.is_empty() {
1244 .span_after(mk_sp(body_lo, span.hi()), ")")
1246 // This is a dirty hack to work around a missing `)` from the span of the last field.
1247 let last_arg_span = fields[fields.len() - 1].span;
1248 if context.snippet(last_arg_span).ends_with(')') {
1253 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1257 let where_clause_str = match struct_parts.generics {
1259 let budget = context.budget(last_line_width(&header_str));
1260 let shape = Shape::legacy(budget, offset);
1261 let g_span = mk_sp(span.lo(), body_lo);
1262 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1263 result.push_str(&generics_str);
1265 let where_budget = context.budget(last_line_width(&result));
1266 let option = WhereClauseOption::new(true, false);
1267 rewrite_where_clause(
1269 &generics.where_clause,
1270 context.config.brace_style(),
1271 Shape::legacy(where_budget, offset.block_only()),
1272 Density::Compressed,
1280 None => "".to_owned(),
1283 if fields.is_empty() {
1285 let used_width = last_line_used_width(&result, offset.width()) + 3;
1286 if used_width > context.config.max_width() {
1288 result.push_str(&offset
1289 .block_indent(context.config)
1290 .to_string(context.config))
1293 let snippet = context.snippet(mk_sp(
1297 .span_before(mk_sp(body_lo, span.hi()), ")"),
1299 if snippet.is_empty() {
1301 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1302 result.push_str(snippet.trim_right());
1304 result.push_str(&offset.to_string(context.config));
1306 result.push_str(snippet);
1310 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1311 let fields = &fields.iter().collect::<Vec<_>>()[..];
1312 result = overflow::rewrite_with_parens(
1318 context.config.width_heuristics().fn_call_width,
1323 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1324 && (result.contains('\n')
1325 || offset.block_indent + result.len() + where_clause_str.len() + 1
1326 > context.config.max_width())
1328 // We need to put the where clause on a new line, but we didn't
1329 // know that earlier, so the where clause will not be indented properly.
1332 .push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1333 .to_string(context.config));
1335 result.push_str(&where_clause_str);
1340 pub fn rewrite_type_alias(
1341 context: &RewriteContext,
1345 generics: &ast::Generics,
1346 vis: &ast::Visibility,
1348 ) -> Option<String> {
1349 let mut result = String::with_capacity(128);
1351 result.push_str(&format_visibility(vis));
1352 result.push_str("type ");
1353 result.push_str(&ident.to_string());
1356 let g_shape = Shape::indented(indent, context.config)
1357 .offset_left(result.len())?
1360 context.snippet_provider.span_after(span, "type"),
1363 let generics_str = rewrite_generics(context, generics, g_shape, g_span)?;
1364 result.push_str(&generics_str);
1366 let where_budget = context.budget(last_line_width(&result));
1367 let option = WhereClauseOption::snuggled(&result);
1368 let where_clause_str = rewrite_where_clause(
1370 &generics.where_clause,
1371 context.config.brace_style(),
1372 Shape::legacy(where_budget, indent),
1380 result.push_str(&where_clause_str);
1381 if where_clause_str.is_empty() {
1382 result.push_str(" =");
1384 result.push_str(&format!(
1386 indent.to_string_with_newline(context.config)
1391 let ty_shape = Shape::indented(indent, context.config).sub_width(1)?;
1392 rewrite_assign_rhs(context, result, ty, ty_shape).map(|s| s + ";")
1395 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1397 if config.space_before_colon() { " " } else { "" },
1398 if config.space_after_colon() { " " } else { "" },
1402 pub fn rewrite_struct_field_prefix(
1403 context: &RewriteContext,
1404 field: &ast::StructField,
1405 ) -> Option<String> {
1406 let vis = format_visibility(&field.vis);
1407 let type_annotation_spacing = type_annotation_spacing(context.config);
1408 Some(match field.ident {
1409 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1410 None => format!("{}", vis),
1414 impl Rewrite for ast::StructField {
1415 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1416 rewrite_struct_field(context, self, shape, 0)
1420 pub fn rewrite_struct_field(
1421 context: &RewriteContext,
1422 field: &ast::StructField,
1424 lhs_max_width: usize,
1425 ) -> Option<String> {
1426 if contains_skip(&field.attrs) {
1427 return Some(context.snippet(field.span()).to_owned());
1430 let type_annotation_spacing = type_annotation_spacing(context.config);
1431 let prefix = rewrite_struct_field_prefix(context, field)?;
1433 let attrs_str = field.attrs.rewrite(context, shape)?;
1434 let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
1435 let missing_span = if field.attrs.is_empty() {
1436 mk_sp(field.span.lo(), field.span.lo())
1438 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1440 let mut spacing = String::from(if field.ident.is_some() {
1441 type_annotation_spacing.1
1445 // Try to put everything on a single line.
1446 let attr_prefix = combine_strs_with_missing_comments(
1454 let overhead = last_line_width(&attr_prefix);
1455 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1456 for _ in 0..lhs_offset {
1459 // In this extreme case we will be missing a space betweeen an attribute and a field.
1460 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1464 .offset_left(overhead + spacing.len())
1465 .and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
1466 if let Some(ref ty) = orig_ty {
1467 if !ty.contains('\n') {
1468 return Some(attr_prefix + &spacing + ty);
1472 let is_prefix_empty = prefix.is_empty();
1473 // We must use multiline. We are going to put attributes and a field on different lines.
1474 let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, shape)?;
1475 // Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
1476 let field_str = if is_prefix_empty {
1477 field_str.trim_left()
1481 combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
1484 pub struct StaticParts<'a> {
1486 vis: &'a ast::Visibility,
1489 mutability: ast::Mutability,
1490 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1491 defaultness: Option<ast::Defaultness>,
1495 impl<'a> StaticParts<'a> {
1496 pub fn from_item(item: &'a ast::Item) -> Self {
1497 let (prefix, ty, mutability, expr) = match item.node {
1498 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1499 ast::ItemKind::Const(ref ty, ref expr) => {
1500 ("const", ty, ast::Mutability::Immutable, expr)
1502 _ => unreachable!(),
1510 expr_opt: Some(expr),
1516 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1517 let (ty, expr_opt) = match ti.node {
1518 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1519 _ => unreachable!(),
1523 vis: &DEFAULT_VISIBILITY,
1526 mutability: ast::Mutability::Immutable,
1527 expr_opt: expr_opt.as_ref(),
1533 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1534 let (ty, expr) = match ii.node {
1535 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1536 _ => unreachable!(),
1543 mutability: ast::Mutability::Immutable,
1544 expr_opt: Some(expr),
1545 defaultness: Some(ii.defaultness),
1552 context: &RewriteContext,
1553 static_parts: &StaticParts,
1555 ) -> Option<String> {
1556 let colon = colon_spaces(
1557 context.config.space_before_colon(),
1558 context.config.space_after_colon(),
1560 let mut prefix = format!(
1562 format_visibility(static_parts.vis),
1563 static_parts.defaultness.map_or("", format_defaultness),
1564 static_parts.prefix,
1565 format_mutability(static_parts.mutability),
1571 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1572 let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
1573 Some(ty_str) => ty_str,
1575 if prefix.ends_with(' ') {
1578 let nested_indent = offset.block_indent(context.config);
1579 let nested_shape = Shape::indented(nested_indent, context.config);
1580 let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
1583 nested_indent.to_string_with_newline(context.config),
1589 if let Some(expr) = static_parts.expr_opt {
1590 let lhs = format!("{}{} =", prefix, ty_str);
1592 let remaining_width = context.budget(offset.block_indent + 1);
1597 Shape::legacy(remaining_width, offset.block_only()),
1598 ).and_then(|res| recover_comment_removed(res, static_parts.span, context))
1599 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1601 Some(format!("{}{};", prefix, ty_str))
1605 pub fn rewrite_associated_type(
1607 ty_opt: Option<&ptr::P<ast::Ty>>,
1608 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1609 context: &RewriteContext,
1611 ) -> Option<String> {
1612 let prefix = format!("type {}", ident);
1614 let type_bounds_str = if let Some(bounds) = ty_param_bounds_opt {
1616 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1617 let bound_str = bounds
1619 .map(|ty_bound| ty_bound.rewrite(context, shape))
1620 .collect::<Option<Vec<_>>>()?;
1621 if !bounds.is_empty() {
1622 format!(": {}", join_bounds(context, shape, &bound_str))
1630 if let Some(ty) = ty_opt {
1632 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1633 let lhs = format!("{}{} =", prefix, type_bounds_str);
1634 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1636 Some(format!("{}{};", prefix, type_bounds_str))
1640 pub fn rewrite_associated_impl_type(
1642 defaultness: ast::Defaultness,
1643 ty_opt: Option<&ptr::P<ast::Ty>>,
1644 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1645 context: &RewriteContext,
1647 ) -> Option<String> {
1648 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1651 ast::Defaultness::Default => Some(format!("default {}", result)),
1656 impl Rewrite for ast::FunctionRetTy {
1657 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1659 ast::FunctionRetTy::Default(_) => Some(String::new()),
1660 ast::FunctionRetTy::Ty(ref ty) => {
1661 let inner_width = shape.width.checked_sub(3)?;
1662 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1663 .map(|r| format!("-> {}", r))
1669 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1671 ast::TyKind::Infer => {
1672 let original = context.snippet(ty.span);
1679 impl Rewrite for ast::Arg {
1680 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1681 if is_named_arg(self) {
1682 let mut result = self.pat
1683 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1685 if !is_empty_infer(context, &*self.ty) {
1686 if context.config.space_before_colon() {
1687 result.push_str(" ");
1689 result.push_str(":");
1690 if context.config.space_after_colon() {
1691 result.push_str(" ");
1693 let overhead = last_line_width(&result);
1694 let max_width = shape.width.checked_sub(overhead)?;
1695 let ty_str = self.ty
1696 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1697 result.push_str(&ty_str);
1702 self.ty.rewrite(context, shape)
1707 fn rewrite_explicit_self(
1708 explicit_self: &ast::ExplicitSelf,
1710 context: &RewriteContext,
1711 ) -> Option<String> {
1712 match explicit_self.node {
1713 ast::SelfKind::Region(lt, m) => {
1714 let mut_str = format_mutability(m);
1717 let lifetime_str = l.rewrite(
1719 Shape::legacy(context.config.max_width(), Indent::empty()),
1721 Some(format!("&{} {}self", lifetime_str, mut_str))
1723 None => Some(format!("&{}self", mut_str)),
1726 ast::SelfKind::Explicit(ref ty, _) => {
1727 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1729 let mutability = explicit_self_mutability(&args[0]);
1730 let type_str = ty.rewrite(
1732 Shape::legacy(context.config.max_width(), Indent::empty()),
1737 format_mutability(mutability),
1741 ast::SelfKind::Value(_) => {
1742 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1744 let mutability = explicit_self_mutability(&args[0]);
1746 Some(format!("{}self", format_mutability(mutability)))
1751 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1752 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1753 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1754 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1761 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1762 if is_named_arg(arg) {
1769 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1771 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1772 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1773 _ => arg.ty.span.hi(),
1777 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1778 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1779 ident.node != symbol::keywords::Invalid.ident()
1785 // Return type is (result, force_new_line_for_brace)
1787 context: &RewriteContext,
1792 newline_brace: bool,
1794 ) -> Option<(String, bool)> {
1795 let mut force_new_line_for_brace = false;
1797 let where_clause = &fn_sig.generics.where_clause;
1799 let mut result = String::with_capacity(1024);
1800 result.push_str(&fn_sig.to_str(context));
1803 result.push_str("fn ");
1804 result.push_str(&ident.to_string());
1807 let overhead = if has_body && !newline_brace {
1814 let used_width = last_line_used_width(&result, indent.width());
1815 let one_line_budget = context.budget(used_width + overhead);
1817 width: one_line_budget,
1821 let fd = fn_sig.decl;
1822 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1823 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1824 result.push_str(&generics_str);
1826 let snuggle_angle_bracket = generics_str
1829 .map_or(false, |l| l.trim_left().len() == 1);
1831 // Note that the width and indent don't really matter, we'll re-layout the
1832 // return type later anyway.
1833 let ret_str = fd.output
1834 .rewrite(context, Shape::indented(indent, context.config))?;
1836 let multi_line_ret_str = ret_str.contains('\n');
1837 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1840 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1851 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1852 one_line_budget, multi_line_budget, arg_indent
1855 // Check if vertical layout was forced.
1856 if one_line_budget == 0 {
1857 if snuggle_angle_bracket {
1860 result.push_str("(");
1861 if context.config.indent_style() == IndentStyle::Visual {
1862 result.push_str(&arg_indent.to_string_with_newline(context.config));
1868 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1869 && result.ends_with('(')
1874 // Skip `pub(crate)`.
1875 let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
1876 // A conservative estimation, to goal is to be over all parens in generics
1877 let args_start = fn_sig
1882 .map_or(lo_after_visibility, |param| param.span().hi());
1883 let args_end = if fd.inputs.is_empty() {
1886 .span_after(mk_sp(args_start, span.hi()), ")")
1888 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1889 context.snippet_provider.span_after(last_span, ")")
1891 let args_span = mk_sp(
1894 .span_after(mk_sp(args_start, span.hi()), "("),
1897 let arg_str = rewrite_args(
1900 fd.get_self().as_ref(),
1907 generics_str.contains('\n'),
1910 let put_args_in_block = match context.config.indent_style() {
1911 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1913 } && !fd.inputs.is_empty();
1915 let mut args_last_line_contains_comment = false;
1916 if put_args_in_block {
1917 arg_indent = indent.block_indent(context.config);
1918 result.push_str(&arg_indent.to_string_with_newline(context.config));
1919 result.push_str(&arg_str);
1920 result.push_str(&indent.to_string_with_newline(context.config));
1923 result.push_str(&arg_str);
1924 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1925 // Put the closing brace on the next line if it overflows the max width.
1927 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1930 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1933 // If the last line of args contains comment, we cannot put the closing paren
1934 // on the same line.
1938 .map_or(false, |last_line| last_line.contains("//"))
1940 args_last_line_contains_comment = true;
1941 result.push_str(&arg_indent.to_string_with_newline(context.config));
1947 if let ast::FunctionRetTy::Ty(..) = fd.output {
1948 let ret_should_indent = match context.config.indent_style() {
1949 // If our args are block layout then we surely must have space.
1950 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1951 _ if args_last_line_contains_comment => false,
1952 _ if result.contains('\n') || multi_line_ret_str => true,
1954 // If the return type would push over the max width, then put the return type on
1955 // a new line. With the +1 for the signature length an additional space between
1956 // the closing parenthesis of the argument and the arrow '->' is considered.
1957 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1959 // If there is no where clause, take into account the space after the return type
1961 if where_clause.predicates.is_empty() {
1965 sig_length > context.config.max_width()
1968 let ret_indent = if ret_should_indent {
1969 let indent = if arg_str.is_empty() {
1970 // Aligning with non-existent args looks silly.
1971 force_new_line_for_brace = true;
1974 // FIXME: we might want to check that using the arg indent
1975 // doesn't blow our budget, and if it does, then fallback to
1976 // the where clause indent.
1980 result.push_str(&indent.to_string_with_newline(context.config));
1984 Indent::new(indent.block_indent, last_line_width(&result))
1987 if multi_line_ret_str || ret_should_indent {
1988 // Now that we know the proper indent and width, we need to
1989 // re-layout the return type.
1990 let ret_str = fd.output
1991 .rewrite(context, Shape::indented(ret_indent, context.config))?;
1992 result.push_str(&ret_str);
1994 result.push_str(&ret_str);
1997 // Comment between return type and the end of the decl.
1998 let snippet_lo = fd.output.span().hi();
1999 if where_clause.predicates.is_empty() {
2000 let snippet_hi = span.hi();
2001 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2002 // Try to preserve the layout of the original snippet.
2003 let original_starts_with_newline = snippet
2005 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2006 let original_ends_with_newline = snippet
2007 .rfind(|c| c != ' ')
2008 .map_or(false, |i| snippet[i..].ends_with('\n'));
2009 let snippet = snippet.trim();
2010 if !snippet.is_empty() {
2011 result.push(if original_starts_with_newline {
2016 result.push_str(snippet);
2017 if original_ends_with_newline {
2018 force_new_line_for_brace = true;
2024 let pos_before_where = match fd.output {
2025 ast::FunctionRetTy::Default(..) => args_span.hi(),
2026 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2029 let is_args_multi_lined = arg_str.contains('\n');
2031 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2032 let where_clause_str = rewrite_where_clause(
2035 context.config.brace_style(),
2036 Shape::indented(indent, context.config),
2042 is_args_multi_lined,
2044 // If there are neither where clause nor return type, we may be missing comments between
2046 if where_clause_str.is_empty() {
2047 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2048 match recover_missing_comment_in_span(
2049 mk_sp(args_span.hi(), ret_span.hi()),
2052 last_line_width(&result),
2054 Some(ref missing_comment) if !missing_comment.is_empty() => {
2055 result.push_str(missing_comment);
2056 force_new_line_for_brace = true;
2063 result.push_str(&where_clause_str);
2065 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2066 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2067 Some((result, force_new_line_for_brace))
2070 #[derive(Copy, Clone)]
2071 struct WhereClauseOption {
2072 suppress_comma: bool, // Force no trailing comma
2073 snuggle: bool, // Do not insert newline before `where`
2074 compress_where: bool, // Try single line where clause instead of vertical layout
2077 impl WhereClauseOption {
2078 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2082 compress_where: false,
2086 pub fn snuggled(current: &str) -> WhereClauseOption {
2088 suppress_comma: false,
2089 snuggle: trimmed_last_line_width(current) == 1,
2090 compress_where: false,
2096 context: &RewriteContext,
2098 explicit_self: Option<&ast::ExplicitSelf>,
2099 one_line_budget: usize,
2100 multi_line_budget: usize,
2105 generics_str_contains_newline: bool,
2106 ) -> Option<String> {
2107 let mut arg_item_strs = args.iter()
2108 .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
2109 .collect::<Option<Vec<_>>>()?;
2111 // Account for sugary self.
2112 // FIXME: the comment for the self argument is dropped. This is blocked
2113 // on rust issue #27522.
2114 let min_args = explicit_self
2115 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2116 .map_or(1, |self_str| {
2117 arg_item_strs[0] = self_str;
2121 // Comments between args.
2122 let mut arg_items = Vec::new();
2124 arg_items.push(ListItem::from_str(""));
2127 // FIXME(#21): if there are no args, there might still be a comment, but
2128 // without spans for the comment or parens, there is no chance of
2129 // getting it right. You also don't get to put a comment on self, unless
2131 if args.len() >= min_args || variadic {
2132 let comment_span_start = if min_args == 2 {
2133 let second_arg_start = if arg_has_pattern(&args[1]) {
2134 args[1].pat.span.lo()
2136 args[1].ty.span.lo()
2138 let reduced_span = mk_sp(span.lo(), second_arg_start);
2140 context.snippet_provider.span_after_last(reduced_span, ",")
2145 enum ArgumentKind<'a> {
2146 Regular(&'a ast::Arg),
2150 let variadic_arg = if variadic {
2151 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2152 let variadic_start =
2153 context.snippet_provider.span_after(variadic_span, "...") - BytePos(3);
2154 Some(ArgumentKind::Variadic(variadic_start))
2159 let more_items = itemize_list(
2160 context.snippet_provider,
2161 args[min_args - 1..]
2163 .map(ArgumentKind::Regular)
2164 .chain(variadic_arg),
2168 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2169 ArgumentKind::Variadic(start) => start,
2172 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2173 ArgumentKind::Variadic(start) => start + BytePos(3),
2176 ArgumentKind::Regular(..) => None,
2177 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2184 arg_items.extend(more_items);
2187 let fits_in_one_line = !generics_str_contains_newline
2188 && (arg_items.is_empty()
2189 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2191 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2192 item.item = Some(arg);
2195 let last_line_ends_with_comment = arg_items
2198 .and_then(|item| item.post_comment.as_ref())
2199 .map_or(false, |s| s.trim().starts_with("//"));
2201 let (indent, trailing_comma) = match context.config.indent_style() {
2202 IndentStyle::Block if fits_in_one_line => {
2203 (indent.block_indent(context.config), SeparatorTactic::Never)
2205 IndentStyle::Block => (
2206 indent.block_indent(context.config),
2207 context.config.trailing_comma(),
2209 IndentStyle::Visual if last_line_ends_with_comment => {
2210 (arg_indent, context.config.trailing_comma())
2212 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2215 let tactic = definitive_tactic(
2217 context.config.fn_args_density().to_list_tactic(),
2221 let budget = match tactic {
2222 DefinitiveListTactic::Horizontal => one_line_budget,
2223 _ => multi_line_budget,
2226 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2228 let fmt = ListFormatting {
2231 trailing_separator: if variadic {
2232 SeparatorTactic::Never
2236 separator_place: SeparatorPlace::Back,
2237 shape: Shape::legacy(budget, indent),
2238 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2239 preserve_newline: true,
2240 config: context.config,
2243 write_list(&arg_items, &fmt)
2246 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2247 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2248 ident.node != symbol::keywords::Invalid.ident()
2254 fn compute_budgets_for_args(
2255 context: &RewriteContext,
2259 newline_brace: bool,
2261 force_vertical_layout: bool,
2262 ) -> Option<((usize, usize, Indent))> {
2264 "compute_budgets_for_args {} {:?}, {}, {}",
2270 // Try keeping everything on the same line.
2271 if !result.contains('\n') && !force_vertical_layout {
2272 // 2 = `()`, 3 = `() `, space is before ret_string.
2273 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2274 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2284 let one_line_budget = context.budget(used_space);
2286 if one_line_budget > 0 {
2288 let (indent, multi_line_budget) = match context.config.indent_style() {
2289 IndentStyle::Block => {
2290 let indent = indent.block_indent(context.config);
2291 (indent, context.budget(indent.width() + 1))
2293 IndentStyle::Visual => {
2294 let indent = indent + result.len() + 1;
2295 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2296 (indent, context.budget(multi_line_overhead))
2300 return Some((one_line_budget, multi_line_budget, indent));
2304 // Didn't work. we must force vertical layout and put args on a newline.
2305 let new_indent = indent.block_indent(context.config);
2306 let used_space = match context.config.indent_style() {
2308 IndentStyle::Block => new_indent.width() + 1,
2309 // Account for `)` and possibly ` {`.
2310 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2312 Some((0, context.budget(used_space), new_indent))
2315 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2316 let predicate_count = where_clause.predicates.len();
2318 if config.where_single_line() && predicate_count == 1 {
2321 let brace_style = config.brace_style();
2323 brace_style == BraceStyle::AlwaysNextLine
2324 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2327 fn rewrite_generics(
2328 context: &RewriteContext,
2329 generics: &ast::Generics,
2332 ) -> Option<String> {
2333 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2334 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2335 rewrite_generics_inner(context, generics, g_shape, one_line_width, span)
2336 .or_else(|| rewrite_generics_inner(context, generics, g_shape, 0, span))
2339 fn rewrite_generics_inner(
2340 context: &RewriteContext,
2341 generics: &ast::Generics,
2343 one_line_width: usize,
2345 ) -> Option<String> {
2346 // FIXME: convert bounds to where clauses where they get too big or if
2347 // there is a where clause at all.
2349 if generics.params.is_empty() {
2350 return Some(String::new());
2353 let items = itemize_list(
2354 context.snippet_provider,
2355 generics.params.iter(),
2358 |arg| arg.span().lo(),
2359 |arg| arg.span().hi(),
2360 |arg| arg.rewrite(context, shape),
2361 context.snippet_provider.span_after(span, "<"),
2365 format_generics_item_list(context, items, shape, one_line_width)
2368 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2369 match config.indent_style() {
2370 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2371 IndentStyle::Block => {
2375 .block_indent(config.tab_spaces())
2376 .with_max_width(config)
2382 pub fn format_generics_item_list<I>(
2383 context: &RewriteContext,
2386 one_line_budget: usize,
2389 I: Iterator<Item = ListItem>,
2391 let item_vec = items.collect::<Vec<_>>();
2393 let tactic = definitive_tactic(
2395 ListTactic::HorizontalVertical,
2399 let fmt = ListFormatting {
2402 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2403 SeparatorTactic::Never
2405 context.config.trailing_comma()
2407 separator_place: SeparatorPlace::Back,
2409 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2410 preserve_newline: true,
2411 config: context.config,
2414 let list_str = write_list(&item_vec, &fmt)?;
2416 Some(wrap_generics_with_angle_brackets(
2423 pub fn wrap_generics_with_angle_brackets(
2424 context: &RewriteContext,
2426 list_offset: Indent,
2428 if context.config.indent_style() == IndentStyle::Block
2429 && (list_str.contains('\n') || list_str.ends_with(','))
2433 list_offset.to_string(context.config),
2436 .block_unindent(context.config)
2437 .to_string(context.config)
2439 } else if context.config.spaces_within_parens_and_brackets() {
2440 format!("< {} >", list_str)
2442 format!("<{}>", list_str)
2446 fn rewrite_trait_bounds(
2447 context: &RewriteContext,
2448 bounds: &[ast::TyParamBound],
2450 ) -> Option<String> {
2451 if bounds.is_empty() {
2452 return Some(String::new());
2454 let bound_str = bounds
2456 .map(|ty_bound| ty_bound.rewrite(context, shape))
2457 .collect::<Option<Vec<_>>>()?;
2458 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2461 fn rewrite_where_clause_rfc_style(
2462 context: &RewriteContext,
2463 where_clause: &ast::WhereClause,
2466 span_end: Option<BytePos>,
2467 span_end_before_where: BytePos,
2468 where_clause_option: WhereClauseOption,
2469 is_args_multi_line: bool,
2470 ) -> Option<String> {
2471 let block_shape = shape.block().with_max_width(context.config);
2473 let (span_before, span_after) =
2474 missing_span_before_after_where(span_end_before_where, where_clause);
2475 let (comment_before, comment_after) =
2476 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2478 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2481 block_shape.indent.to_string_with_newline(context.config)
2484 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2486 let clause_shape = clause_shape.sub_width(1)?;
2487 // each clause on one line, trailing comma (except if suppress_comma)
2488 let span_start = where_clause.predicates[0].span().lo();
2489 // If we don't have the start of the next span, then use the end of the
2490 // predicates, but that means we miss comments.
2491 let len = where_clause.predicates.len();
2492 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2493 let span_end = span_end.unwrap_or(end_of_preds);
2494 let items = itemize_list(
2495 context.snippet_provider,
2496 where_clause.predicates.iter(),
2499 |pred| pred.span().lo(),
2500 |pred| pred.span().hi(),
2501 |pred| pred.rewrite(context, clause_shape),
2506 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2507 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2508 SeparatorTactic::Never
2510 context.config.trailing_comma()
2513 // shape should be vertical only and only if we have `where_single_line` option enabled
2514 // and the number of items of the where clause is equal to 1
2515 let shape_tactic = if where_single_line {
2516 DefinitiveListTactic::Horizontal
2518 DefinitiveListTactic::Vertical
2521 let fmt = ListFormatting {
2522 tactic: shape_tactic,
2524 trailing_separator: comma_tactic,
2525 separator_place: SeparatorPlace::Back,
2526 shape: clause_shape,
2527 ends_with_newline: true,
2528 preserve_newline: true,
2529 config: context.config,
2531 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2533 let comment_separator = |comment: &str, shape: Shape| {
2534 if comment.is_empty() {
2537 shape.indent.to_string_with_newline(context.config)
2540 let newline_before_where = comment_separator(&comment_before, shape);
2541 let newline_after_where = comment_separator(&comment_after, clause_shape);
2544 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2545 && comment_after.is_empty() && !preds_str.contains('\n')
2546 && 6 + preds_str.len() <= shape.width || where_single_line
2550 clause_shape.indent.to_string_with_newline(context.config)
2553 "{}{}{}where{}{}{}{}",
2556 newline_before_where,
2557 newline_after_where,
2564 fn rewrite_where_clause(
2565 context: &RewriteContext,
2566 where_clause: &ast::WhereClause,
2567 brace_style: BraceStyle,
2571 span_end: Option<BytePos>,
2572 span_end_before_where: BytePos,
2573 where_clause_option: WhereClauseOption,
2574 is_args_multi_line: bool,
2575 ) -> Option<String> {
2576 if where_clause.predicates.is_empty() {
2577 return Some(String::new());
2580 if context.config.indent_style() == IndentStyle::Block {
2581 return rewrite_where_clause_rfc_style(
2587 span_end_before_where,
2588 where_clause_option,
2593 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2595 let offset = match context.config.indent_style() {
2596 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2597 // 6 = "where ".len()
2598 IndentStyle::Visual => shape.indent + extra_indent + 6,
2600 // FIXME: if indent_style != Visual, then the budgets below might
2601 // be out by a char or two.
2603 let budget = context.config.max_width() - offset.width();
2604 let span_start = where_clause.predicates[0].span().lo();
2605 // If we don't have the start of the next span, then use the end of the
2606 // predicates, but that means we miss comments.
2607 let len = where_clause.predicates.len();
2608 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2609 let span_end = span_end.unwrap_or(end_of_preds);
2610 let items = itemize_list(
2611 context.snippet_provider,
2612 where_clause.predicates.iter(),
2615 |pred| pred.span().lo(),
2616 |pred| pred.span().hi(),
2617 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2622 let item_vec = items.collect::<Vec<_>>();
2623 // FIXME: we don't need to collect here
2624 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2626 let mut comma_tactic = context.config.trailing_comma();
2627 // Kind of a hack because we don't usually have trailing commas in where clauses.
2628 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2629 comma_tactic = SeparatorTactic::Never;
2632 let fmt = ListFormatting {
2635 trailing_separator: comma_tactic,
2636 separator_place: SeparatorPlace::Back,
2637 shape: Shape::legacy(budget, offset),
2638 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2639 preserve_newline: true,
2640 config: context.config,
2642 let preds_str = write_list(&item_vec, &fmt)?;
2644 let end_length = if terminator == "{" {
2645 // If the brace is on the next line we don't need to count it otherwise it needs two
2648 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2649 BraceStyle::PreferSameLine => 2,
2651 } else if terminator == "=" {
2656 if density == Density::Tall || preds_str.contains('\n')
2657 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2661 (shape.indent + extra_indent).to_string(context.config),
2665 Some(format!(" where {}", preds_str))
2669 fn missing_span_before_after_where(
2670 before_item_span_end: BytePos,
2671 where_clause: &ast::WhereClause,
2673 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2675 let pos_after_where = where_clause.span.lo() + BytePos(5);
2676 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2677 (missing_span_before, missing_span_after)
2680 fn rewrite_comments_before_after_where(
2681 context: &RewriteContext,
2682 span_before_where: Span,
2683 span_after_where: Span,
2685 ) -> Option<(String, String)> {
2686 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2687 let after_comment = rewrite_missing_comment(
2689 shape.block_indent(context.config.tab_spaces()),
2692 Some((before_comment, after_comment))
2695 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2696 format!("{}{}{}", format_visibility(vis), item_name, ident)
2699 #[derive(PartialEq, Eq, Clone, Copy)]
2707 context: &RewriteContext,
2708 generics: &ast::Generics,
2709 brace_style: BraceStyle,
2710 brace_pos: BracePos,
2714 ) -> Option<String> {
2715 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2716 let mut result = rewrite_generics(context, generics, shape, span)?;
2718 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2719 let budget = context.budget(last_line_used_width(&result, offset.width()));
2720 let mut option = WhereClauseOption::snuggled(&result);
2721 if brace_pos == BracePos::None {
2722 option.suppress_comma = true;
2724 // If the generics are not parameterized then generics.span.hi() == 0,
2725 // so we use span.lo(), which is the position after `struct Foo`.
2726 let span_end_before_where = if generics.is_parameterized() {
2731 let where_clause_str = rewrite_where_clause(
2733 &generics.where_clause,
2735 Shape::legacy(budget, offset.block_only()),
2739 span_end_before_where,
2743 result.push_str(&where_clause_str);
2744 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2745 || (generics.where_clause.predicates.is_empty()
2746 && trimmed_last_line_width(&result) == 1)
2748 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2749 || brace_style != BraceStyle::AlwaysNextLine
2751 if brace_pos == BracePos::None {
2752 return Some(result);
2754 let total_used_width = last_line_used_width(&result, used_width);
2755 let remaining_budget = context.budget(total_used_width);
2756 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2757 // and hence we take the closer into account as well for one line budget.
2758 // We assume that the closer has the same length as the opener.
2759 let overhead = if brace_pos == BracePos::ForceSameLine {
2766 let forbid_same_line_brace = overhead > remaining_budget;
2767 if !forbid_same_line_brace && same_line_brace {
2771 result.push_str(&offset.block_only().to_string(context.config));
2778 impl Rewrite for ast::ForeignItem {
2779 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2780 let attrs_str = self.attrs.rewrite(context, shape)?;
2781 // Drop semicolon or it will be interpreted as comment.
2782 // FIXME: this may be a faulty span from libsyntax.
2783 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2785 let item_str = match self.node {
2786 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2791 &FnSig::new(fn_decl, generics, self.vis.clone()),
2795 ).map(|(s, _)| format!("{};", s))
2797 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2798 // FIXME(#21): we're dropping potential comments in between the
2799 // function keywords here.
2800 let vis = format_visibility(&self.vis);
2801 let mut_str = if is_mutable { "mut " } else { "" };
2802 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2804 let shape = shape.sub_width(1)?;
2805 ty.rewrite(context, shape).map(|ty_str| {
2806 // 1 = space between prefix and type.
2807 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2810 let nested_indent = shape.indent.block_indent(context.config);
2811 nested_indent.to_string_with_newline(context.config)
2813 format!("{}{}{};", prefix, sep, ty_str)
2816 ast::ForeignItemKind::Ty => {
2817 let vis = format_visibility(&self.vis);
2818 Some(format!("{}type {};", vis, self.ident))
2822 let missing_span = if self.attrs.is_empty() {
2823 mk_sp(self.span.lo(), self.span.lo())
2825 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2827 combine_strs_with_missing_comments(
2838 impl Rewrite for ast::GenericParam {
2839 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2841 ast::GenericParam::Lifetime(ref lifetime_def) => lifetime_def.rewrite(context, shape),
2842 ast::GenericParam::Type(ref ty) => ty.rewrite(context, shape),
2847 /// Rewrite an inline mod.
2848 pub fn rewrite_mod(item: &ast::Item) -> String {
2849 let mut result = String::with_capacity(32);
2850 result.push_str(&*format_visibility(&item.vis));
2851 result.push_str("mod ");
2852 result.push_str(&item.ident.to_string());
2857 /// Rewrite `extern crate foo;` WITHOUT attributes.
2858 pub fn rewrite_extern_crate(context: &RewriteContext, item: &ast::Item) -> Option<String> {
2859 assert!(is_extern_crate(item));
2860 let new_str = context.snippet(item.span);
2861 Some(if contains_comment(new_str) {
2864 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
2865 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
2869 /// Returns true for `mod foo;`, false for `mod foo { .. }`.
2870 pub fn is_mod_decl(item: &ast::Item) -> bool {
2872 ast::ItemKind::Mod(ref m) => m.inner.hi() != item.span.hi(),
2877 pub fn is_use_item(item: &ast::Item) -> bool {
2879 ast::ItemKind::Use(_) => true,
2884 pub fn is_extern_crate(item: &ast::Item) -> bool {
2886 ast::ItemKind::ExternCrate(..) => true,