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.
14 use std::cmp::{min, Ordering};
18 use rustc_target::spec::abi;
19 use syntax::codemap::{self, BytePos, Span};
21 use syntax::{ast, ptr, symbol};
23 use codemap::{LineRangeUtils, SpanUtils};
25 combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
26 recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented,
28 use config::{BraceStyle, Config, Density, IndentStyle};
30 format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs, rewrite_assign_rhs_with,
33 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, ListItem, Separator};
34 use macros::{rewrite_macro, MacroPosition};
36 use rewrite::{Rewrite, RewriteContext};
37 use shape::{Indent, Shape};
40 use vertical::rewrite_with_alignment;
41 use visitor::FmtVisitor;
43 const DEFAULT_VISIBILITY: ast::Visibility = codemap::Spanned {
44 node: ast::VisibilityKind::Inherited,
45 span: codemap::DUMMY_SP,
48 fn type_annotation_separator(config: &Config) -> &str {
49 colon_spaces(config.space_before_colon(), config.space_after_colon())
52 // Statements of the form
53 // let pat: ty = init;
54 impl Rewrite for ast::Local {
55 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
57 "Local::rewrite {:?} {} {:?}",
58 self, shape.width, shape.indent
61 skip_out_of_file_lines_range!(context, self.span);
63 if contains_skip(&self.attrs) {
67 let attrs_str = self.attrs.rewrite(context, shape)?;
68 let mut result = if attrs_str.is_empty() {
71 combine_strs_with_missing_comments(
76 self.attrs.last().map(|a| a.span.hi()).unwrap(),
85 let pat_shape = shape.offset_left(4)?;
87 let pat_shape = pat_shape.sub_width(1)?;
88 let pat_str = self.pat.rewrite(context, pat_shape)?;
89 result.push_str(&pat_str);
91 // String that is placed within the assignment pattern and expression.
93 let mut infix = String::with_capacity(32);
95 if let Some(ref ty) = self.ty {
96 let separator = type_annotation_separator(context.config);
97 let indent = shape.indent + last_line_width(&result) + separator.len();
99 let budget = shape.width.checked_sub(indent.width() + 1)?;
100 let rewrite = ty.rewrite(context, Shape::legacy(budget, indent))?;
102 infix.push_str(separator);
103 infix.push_str(&rewrite);
106 if self.init.is_some() {
107 infix.push_str(" =");
113 result.push_str(&infix);
115 if let Some(ref ex) = self.init {
116 // 1 = trailing semicolon;
117 let nested_shape = shape.sub_width(1)?;
119 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
127 // FIXME convert to using rewrite style rather than visitor
128 // FIXME format modules in this style
131 keyword: &'static str,
132 abi: Cow<'static, str>,
133 vis: Option<&'a ast::Visibility>,
134 body: Vec<BodyElement<'a>>,
139 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
142 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
147 .map(|i| BodyElement::ForeignItem(i))
154 enum BodyElement<'a> {
155 // Stmt(&'a ast::Stmt),
156 // Field(&'a ast::Field),
157 // Variant(&'a ast::Variant),
158 // Item(&'a ast::Item),
159 ForeignItem(&'a ast::ForeignItem),
162 /// Represents a fn's signature.
163 pub struct FnSig<'a> {
164 decl: &'a ast::FnDecl,
165 generics: &'a ast::Generics,
167 constness: ast::Constness,
168 defaultness: ast::Defaultness,
169 unsafety: ast::Unsafety,
170 visibility: ast::Visibility,
175 decl: &'a ast::FnDecl,
176 generics: &'a ast::Generics,
177 vis: ast::Visibility,
183 constness: ast::Constness::NotConst,
184 defaultness: ast::Defaultness::Final,
185 unsafety: ast::Unsafety::Normal,
190 pub fn from_method_sig(
191 method_sig: &'a ast::MethodSig,
192 generics: &'a ast::Generics,
195 unsafety: method_sig.header.unsafety,
196 constness: method_sig.header.constness.node,
197 defaultness: ast::Defaultness::Final,
198 abi: method_sig.header.abi,
199 decl: &*method_sig.decl,
201 visibility: DEFAULT_VISIBILITY,
206 fn_kind: &'a visit::FnKind,
207 generics: &'a ast::Generics,
208 decl: &'a ast::FnDecl,
209 defaultness: ast::Defaultness,
212 visit::FnKind::ItemFn(_, fn_header, visibility, _) => FnSig {
216 constness: fn_header.constness.node,
218 unsafety: fn_header.unsafety,
219 visibility: visibility.clone(),
221 visit::FnKind::Method(_, method_sig, vis, _) => {
222 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
223 fn_sig.defaultness = defaultness;
224 if let Some(vis) = vis {
225 fn_sig.visibility = vis.clone();
233 fn to_str(&self, context: &RewriteContext) -> String {
234 let mut result = String::with_capacity(128);
235 // Vis defaultness constness unsafety abi.
236 result.push_str(&*format_visibility(context, &self.visibility));
237 result.push_str(format_defaultness(self.defaultness));
238 result.push_str(format_constness(self.constness));
239 result.push_str(format_unsafety(self.unsafety));
240 result.push_str(&format_abi(
242 context.config.force_explicit_abi(),
249 impl<'a> FmtVisitor<'a> {
250 fn format_item(&mut self, item: &Item) {
251 self.buffer.push_str(&item.abi);
253 let snippet = self.snippet(item.span);
254 let brace_pos = snippet.find_uncommented("{").unwrap();
257 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
258 // FIXME: this skips comments between the extern keyword and the opening
260 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
261 self.block_indent = self.block_indent.block_indent(self.config);
263 if item.body.is_empty() {
264 self.format_missing_no_indent(item.span.hi() - BytePos(1));
265 self.block_indent = self.block_indent.block_unindent(self.config);
266 let indent_str = self.block_indent.to_string(self.config);
267 self.push_str(&indent_str);
269 for item in &item.body {
270 self.format_body_element(item);
273 self.block_indent = self.block_indent.block_unindent(self.config);
274 self.format_missing_with_indent(item.span.hi() - BytePos(1));
279 self.last_pos = item.span.hi();
282 fn format_body_element(&mut self, element: &BodyElement) {
284 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
288 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
289 let item = Item::from_foreign_mod(fm, span, self.config);
290 self.format_item(&item);
293 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
294 let rewrite = item.rewrite(&self.get_context(), self.shape());
295 self.push_rewrite(item.span(), rewrite);
296 self.last_pos = item.span.hi();
306 inner_attrs: Option<&[ast::Attribute]>,
307 ) -> Option<String> {
308 let context = self.get_context();
310 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
312 let (mut result, force_newline_brace) =
313 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
316 if self.config.brace_style() == BraceStyle::AlwaysNextLine
317 || force_newline_brace
318 || last_line_width(&result) + 2 > self.shape().width
320 newline_brace = true;
321 } else if !result.contains('\n') {
322 newline_brace = false;
325 // Prepare for the function body by possibly adding a newline and
327 // FIXME we'll miss anything between the end of the signature and the
328 // start of the body, but we need more spans from the compiler to solve
331 result.push_str(&indent.to_string_with_newline(self.config));
336 self.single_line_fn(&result, block, inner_attrs)
337 .or_else(|| Some(result))
340 pub fn rewrite_required_fn(
344 sig: &ast::MethodSig,
345 generics: &ast::Generics,
347 ) -> Option<String> {
348 // Drop semicolon or it will be interpreted as comment.
349 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
350 let context = self.get_context();
352 let (mut result, _) = rewrite_fn_base(
356 &FnSig::from_method_sig(sig, generics),
362 // Re-attach semicolon
372 inner_attrs: Option<&[ast::Attribute]>,
373 ) -> Option<String> {
374 if fn_str.contains('\n') || inner_attrs.map_or(false, |a| !a.is_empty()) {
378 let codemap = self.get_context().codemap;
380 if self.config.empty_item_single_line()
381 && is_empty_block(block, None, codemap)
382 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
384 return Some(format!("{}{{}}", fn_str));
387 if self.config.fn_single_line() && is_simple_block_stmt(block, None, codemap) {
389 if let Some(stmt) = block.stmts.first() {
390 match stmt_expr(stmt) {
392 let suffix = if semicolon_for_expr(&self.get_context(), e) {
398 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
400 .or_else(|| Some(self.snippet(e.span).to_owned()))
402 None => stmt.rewrite(&self.get_context(), self.shape()),
409 if let Some(res) = rewrite {
410 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
411 if !res.contains('\n') && width <= self.config.max_width() {
412 return Some(format!("{}{{ {} }}", fn_str, res));
420 pub fn visit_static(&mut self, static_parts: &StaticParts) {
421 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
422 self.push_rewrite(static_parts.span, rewrite);
425 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
426 let is_tuple = struct_parts.def.is_tuple();
427 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
428 .map(|s| if is_tuple { s + ";" } else { s });
429 self.push_rewrite(struct_parts.span, rewrite);
435 vis: &ast::Visibility,
436 enum_def: &ast::EnumDef,
437 generics: &ast::Generics,
440 let enum_header = format_header(&self.get_context(), "enum ", ident, vis);
441 self.push_str(&enum_header);
443 let enum_snippet = self.snippet(span);
444 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
445 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
446 let generics_str = format_generics(
449 self.config.brace_style(),
450 if enum_def.variants.is_empty() {
451 BracePos::ForceSameLine
456 mk_sp(span.lo(), body_start),
457 last_line_width(&enum_header),
459 self.push_str(&generics_str);
461 self.last_pos = body_start;
463 match self.format_variant_list(enum_def, body_start, span.hi()) {
464 Some(ref s) if enum_def.variants.is_empty() => self.push_str(s),
466 self.push_rewrite(mk_sp(body_start, span.hi()), rw);
467 self.block_indent = self.block_indent.block_unindent(self.config);
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() {
480 let mut buffer = String::with_capacity(128);
482 let span = mk_sp(body_lo, body_hi - BytePos(1));
483 format_empty_struct_or_tuple(
493 let mut result = String::with_capacity(1024);
494 let original_offset = self.block_indent;
495 self.block_indent = self.block_indent.block_indent(self.config);
497 let itemize_list_with = |one_line_width: usize| {
499 self.snippet_provider,
500 enum_def.variants.iter(),
504 if !f.node.attrs.is_empty() {
505 f.node.attrs[0].span.lo()
511 |f| self.format_variant(f, one_line_width),
517 let mut items: Vec<_> =
518 itemize_list_with(self.config.width_heuristics().struct_variant_width);
519 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
520 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
521 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
522 if has_multiline_variant && has_single_line_variant {
523 items = itemize_list_with(0);
526 let shape = self.shape().sub_width(2)?;
527 let fmt = ListFormatting {
528 tactic: DefinitiveListTactic::Vertical,
530 trailing_separator: self.config.trailing_comma(),
531 separator_place: SeparatorPlace::Back,
533 ends_with_newline: true,
534 preserve_newline: true,
539 let list = write_list(&items, &fmt)?;
540 result.push_str(&list);
541 result.push_str(&original_offset.to_string_with_newline(self.config));
546 // Variant of an enum.
547 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
548 if contains_skip(&field.node.attrs) {
549 let lo = field.node.attrs[0].span.lo();
550 let span = mk_sp(lo, field.span.hi());
551 return Some(self.snippet(span).to_owned());
554 let context = self.get_context();
556 let shape = self.shape().sub_width(1)?;
557 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
562 .map_or(field.span.lo(), |attr| attr.span.hi());
563 let span = mk_sp(lo, field.span.lo());
565 let variant_body = match field.node.data {
566 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
568 &StructParts::from_variant(field),
570 Some(one_line_width),
572 ast::VariantData::Unit(..) => {
573 if let Some(ref expr) = field.node.disr_expr {
574 let lhs = format!("{} =", rewrite_ident(&context, field.node.ident));
575 rewrite_assign_rhs(&context, lhs, &*expr.value, shape)?
577 rewrite_ident(&context, field.node.ident).to_owned()
582 combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
585 fn visit_impl_items(&mut self, items: &[ast::ImplItem]) {
586 if self.get_context().config.reorder_impl_items() {
587 // Create visitor for each items, then reorder them.
588 let mut buffer = vec![];
590 self.visit_impl_item(item);
591 buffer.push((self.buffer.clone(), item.clone()));
594 // type -> const -> macro -> method
595 use ast::ImplItemKind::*;
596 fn need_empty_line(a: &ast::ImplItemKind, b: &ast::ImplItemKind) -> bool {
598 (Type(..), Type(..)) | (Const(..), Const(..)) => false,
603 buffer.sort_by(|(_, a), (_, b)| match (&a.node, &b.node) {
604 (Type(..), _) => Ordering::Less,
605 (_, Type(..)) => Ordering::Greater,
606 (Const(..), _) => Ordering::Less,
607 (_, Const(..)) => Ordering::Greater,
608 (Macro(..), _) => Ordering::Less,
609 (_, Macro(..)) => Ordering::Greater,
610 _ => a.span.lo().cmp(&b.span.lo()),
612 let mut prev_kind = None;
613 for (buf, item) in buffer {
614 // Make sure that there are at least a single empty line between
615 // different impl items.
618 .map_or(false, |prev_kind| need_empty_line(prev_kind, &item.node))
622 let indent_str = self.block_indent.to_string_with_newline(self.config);
623 self.push_str(&indent_str);
624 self.push_str(buf.trim());
625 prev_kind = Some(item.node.clone());
629 self.visit_impl_item(item);
636 context: &RewriteContext,
639 where_span_end: Option<BytePos>,
640 ) -> Option<String> {
641 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
642 let mut result = String::with_capacity(128);
643 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
644 let sep = offset.to_string_with_newline(context.config);
645 result.push_str(&ref_and_type);
647 let where_budget = if result.contains('\n') {
648 context.config.max_width()
650 context.budget(last_line_width(&result))
653 let mut option = WhereClauseOption::snuggled(&ref_and_type);
654 let snippet = context.snippet(item.span);
655 let open_pos = snippet.find_uncommented("{")? + 1;
656 if !contains_comment(&snippet[open_pos..])
658 && generics.where_clause.predicates.len() == 1
659 && !result.contains('\n')
661 option.suppress_comma();
663 option.compress_where();
666 let where_clause_str = rewrite_where_clause(
668 &generics.where_clause,
669 context.config.brace_style(),
670 Shape::legacy(where_budget, offset.block_only()),
679 // If there is no where clause, we may have missing comments between the trait name and
680 // the opening brace.
681 if generics.where_clause.predicates.is_empty() {
682 if let Some(hi) = where_span_end {
683 match recover_missing_comment_in_span(
684 mk_sp(self_ty.span.hi(), hi),
685 Shape::indented(offset, context.config),
687 last_line_width(&result),
689 Some(ref missing_comment) if !missing_comment.is_empty() => {
690 result.push_str(missing_comment);
697 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
698 result.push_str(&where_clause_str);
699 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
700 // if the where_clause contains extra comments AND
701 // there is only one where clause predicate
702 // recover the suppressed comma in single line where_clause formatting
703 if generics.where_clause.predicates.len() == 1 {
704 result.push_str(",");
706 result.push_str(&format!("{}{{{}}}", &sep, &sep));
708 result.push_str(" {}");
713 result.push_str(&where_clause_str);
715 let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
716 match context.config.brace_style() {
717 _ if need_newline => result.push_str(&sep),
718 BraceStyle::AlwaysNextLine => result.push_str(&sep),
719 BraceStyle::PreferSameLine => result.push(' '),
720 BraceStyle::SameLineWhere => {
721 if !where_clause_str.is_empty() {
722 result.push_str(&sep);
731 let snippet = context.snippet(item.span);
732 let open_pos = snippet.find_uncommented("{")? + 1;
734 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
735 let mut visitor = FmtVisitor::from_context(context);
736 let item_indent = offset.block_only().block_indent(context.config);
737 visitor.block_indent = item_indent;
738 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
740 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
741 visitor.visit_impl_items(items);
743 visitor.format_missing(item.span.hi() - BytePos(1));
745 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
746 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
748 result.push_str(&inner_indent_str);
749 result.push_str(visitor.buffer.to_string().trim());
750 result.push_str(&outer_indent_str);
753 if result.ends_with('{') && !context.config.empty_item_single_line() {
754 result.push_str(&sep);
764 fn is_impl_single_line(
765 context: &RewriteContext,
766 items: &[ast::ImplItem],
768 where_clause_str: &str,
771 let snippet = context.snippet(item.span);
772 let open_pos = snippet.find_uncommented("{")? + 1;
775 context.config.empty_item_single_line()
777 && !result.contains('\n')
778 && result.len() + where_clause_str.len() <= context.config.max_width()
779 && !contains_comment(&snippet[open_pos..]),
783 fn format_impl_ref_and_type(
784 context: &RewriteContext,
787 ) -> Option<String> {
788 if let ast::ItemKind::Impl(
798 let mut result = String::with_capacity(128);
800 result.push_str(&format_visibility(context, &item.vis));
801 result.push_str(format_defaultness(defaultness));
802 result.push_str(format_unsafety(unsafety));
804 let shape = generics_shape_from_config(
806 Shape::indented(offset + last_line_width(&result), context.config),
809 let generics_str = rewrite_generics(context, "impl", generics, shape)?;
810 result.push_str(&generics_str);
812 let polarity_str = if polarity == ast::ImplPolarity::Negative {
818 if let Some(ref trait_ref) = *trait_ref {
819 let result_len = last_line_width(&result);
820 result.push_str(&rewrite_trait_ref(
829 // Try to put the self type in a single line.
831 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
832 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
833 // If there is no where clause adapt budget for type formatting to take space and curly
834 // brace into account.
835 match context.config.brace_style() {
836 BraceStyle::AlwaysNextLine => 0,
842 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
843 // 1 = space before the type.
844 let budget = context.budget(used_space + 1);
845 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
846 if !self_ty_str.contains('\n') {
847 if trait_ref.is_some() {
848 result.push_str(" for ");
852 result.push_str(&self_ty_str);
857 // Couldn't fit the self type on a single line, put it on a new line.
859 // Add indentation of one additional tab.
860 let new_line_offset = offset.block_indent(context.config);
861 result.push_str(&new_line_offset.to_string(context.config));
862 if trait_ref.is_some() {
863 result.push_str("for ");
865 let budget = context.budget(last_line_width(&result));
866 let type_offset = match context.config.indent_style() {
867 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
868 IndentStyle::Block => new_line_offset,
870 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
877 fn rewrite_trait_ref(
878 context: &RewriteContext,
879 trait_ref: &ast::TraitRef,
883 ) -> Option<String> {
884 // 1 = space between generics and trait_ref
885 let used_space = 1 + polarity_str.len() + result_len;
886 let shape = Shape::indented(offset + used_space, context.config);
887 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
888 if !trait_ref_str.contains('\n') {
889 return Some(format!(" {}{}", polarity_str, &trait_ref_str));
892 // We could not make enough space for trait_ref, so put it on new line.
893 let offset = offset.block_indent(context.config);
894 let shape = Shape::indented(offset, context.config);
895 let trait_ref_str = trait_ref.rewrite(context, shape)?;
898 &offset.to_string_with_newline(context.config),
904 pub struct StructParts<'a> {
907 vis: &'a ast::Visibility,
908 def: &'a ast::VariantData,
909 generics: Option<&'a ast::Generics>,
913 impl<'a> StructParts<'a> {
914 fn format_header(&self, context: &RewriteContext) -> String {
915 format_header(context, self.prefix, self.ident, self.vis)
918 fn from_variant(variant: &'a ast::Variant) -> Self {
921 ident: variant.node.ident,
922 vis: &DEFAULT_VISIBILITY,
923 def: &variant.node.data,
929 pub fn from_item(item: &'a ast::Item) -> Self {
930 let (prefix, def, generics) = match item.node {
931 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
932 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
940 generics: Some(generics),
947 context: &RewriteContext,
948 struct_parts: &StructParts,
950 one_line_width: Option<usize>,
951 ) -> Option<String> {
952 match *struct_parts.def {
953 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
954 ast::VariantData::Tuple(ref fields, _) => {
955 format_tuple_struct(context, struct_parts, fields, offset)
957 ast::VariantData::Struct(ref fields, _) => {
958 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
963 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
964 if let ast::ItemKind::Trait(
972 let mut result = String::with_capacity(128);
973 let header = format!(
975 format_visibility(context, &item.vis),
976 format_unsafety(unsafety),
977 format_auto(is_auto),
979 result.push_str(&header);
981 let body_lo = context.snippet_provider.span_after(item.span, "{");
983 let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
985 rewrite_generics(context, rewrite_ident(context, item.ident), generics, shape)?;
986 result.push_str(&generics_str);
988 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
989 if !generic_bounds.is_empty() {
990 let ident_hi = context
992 .span_after(item.span, &item.ident.as_str());
993 let bound_hi = generic_bounds.last().unwrap().span().hi();
994 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
995 if contains_comment(snippet) {
999 result = rewrite_assign_rhs_with(
1004 RhsTactics::ForceNextLineWithoutIndent,
1008 // Rewrite where clause.
1009 if !generics.where_clause.predicates.is_empty() {
1010 let where_density = if context.config.indent_style() == IndentStyle::Block {
1016 let where_budget = context.budget(last_line_width(&result));
1017 let pos_before_where = if generic_bounds.is_empty() {
1018 generics.where_clause.span.lo()
1020 generic_bounds[generic_bounds.len() - 1].span().hi()
1022 let option = WhereClauseOption::snuggled(&generics_str);
1023 let where_clause_str = rewrite_where_clause(
1025 &generics.where_clause,
1026 context.config.brace_style(),
1027 Shape::legacy(where_budget, offset.block_only()),
1035 // If the where clause cannot fit on the same line,
1036 // put the where clause on a new line
1037 if !where_clause_str.contains('\n')
1038 && last_line_width(&result) + where_clause_str.len() + offset.width()
1039 > context.config.comment_width()
1041 let width = offset.block_indent + context.config.tab_spaces() - 1;
1042 let where_indent = Indent::new(0, width);
1043 result.push_str(&where_indent.to_string_with_newline(context.config));
1045 result.push_str(&where_clause_str);
1047 let item_snippet = context.snippet(item.span);
1048 if let Some(lo) = item_snippet.find('/') {
1050 let comment_hi = body_lo - BytePos(1);
1051 let comment_lo = item.span.lo() + BytePos(lo as u32);
1052 if comment_lo < comment_hi {
1053 match recover_missing_comment_in_span(
1054 mk_sp(comment_lo, comment_hi),
1055 Shape::indented(offset, context.config),
1057 last_line_width(&result),
1059 Some(ref missing_comment) if !missing_comment.is_empty() => {
1060 result.push_str(missing_comment);
1068 match context.config.brace_style() {
1069 _ if last_line_contains_single_line_comment(&result)
1070 || last_line_width(&result) + 2 > context.budget(offset.width()) =>
1072 result.push_str(&offset.to_string_with_newline(context.config));
1074 BraceStyle::AlwaysNextLine => {
1075 result.push_str(&offset.to_string_with_newline(context.config));
1077 BraceStyle::PreferSameLine => result.push(' '),
1078 BraceStyle::SameLineWhere => {
1079 if result.contains('\n')
1080 || (!generics.where_clause.predicates.is_empty() && !trait_items.is_empty())
1082 result.push_str(&offset.to_string_with_newline(context.config));
1090 let snippet = context.snippet(item.span);
1091 let open_pos = snippet.find_uncommented("{")? + 1;
1093 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1094 let mut visitor = FmtVisitor::from_context(context);
1095 visitor.block_indent = offset.block_only().block_indent(context.config);
1096 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1098 for item in trait_items {
1099 visitor.visit_trait_item(item);
1102 visitor.format_missing(item.span.hi() - BytePos(1));
1104 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
1105 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
1107 result.push_str(&inner_indent_str);
1108 result.push_str(visitor.buffer.to_string().trim());
1109 result.push_str(&outer_indent_str);
1110 } else if result.contains('\n') {
1121 pub fn format_trait_alias(
1122 context: &RewriteContext,
1124 generics: &ast::Generics,
1125 generic_bounds: &ast::GenericBounds,
1127 ) -> Option<String> {
1128 let alias = rewrite_ident(context, ident);
1129 // 6 = "trait ", 2 = " ="
1130 let g_shape = shape.offset_left(6)?.sub_width(2)?;
1131 let generics_str = rewrite_generics(context, &alias, generics, g_shape)?;
1132 let lhs = format!("trait {} =", generics_str);
1134 rewrite_assign_rhs(context, lhs, generic_bounds, shape.sub_width(1)?).map(|s| s + ";")
1137 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1138 let header_str = format_header(context, p.prefix, p.ident, p.vis);
1139 let generics_str = if let Some(generics) = p.generics {
1140 let hi = if generics.where_clause.predicates.is_empty() {
1143 generics.where_clause.span.hi()
1148 context.config.brace_style(),
1151 mk_sp(generics.span.lo(), hi),
1152 last_line_width(&header_str),
1157 Some(format!("{}{};", header_str, generics_str))
1160 pub fn format_struct_struct(
1161 context: &RewriteContext,
1162 struct_parts: &StructParts,
1163 fields: &[ast::StructField],
1165 one_line_width: Option<usize>,
1166 ) -> Option<String> {
1167 let mut result = String::with_capacity(1024);
1168 let span = struct_parts.span;
1170 let header_str = struct_parts.format_header(context);
1171 result.push_str(&header_str);
1173 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1174 let body_lo = context.snippet_provider.span_after(span, "{");
1176 let generics_str = match struct_parts.generics {
1177 Some(g) => format_generics(
1180 context.config.brace_style(),
1181 if fields.is_empty() {
1182 BracePos::ForceSameLine
1187 mk_sp(header_hi, body_lo),
1188 last_line_width(&result),
1191 // 3 = ` {}`, 2 = ` {`.
1192 let overhead = if fields.is_empty() { 3 } else { 2 };
1193 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1194 || context.config.max_width() < overhead + result.len()
1196 format!("\n{}{{", offset.block_only().to_string(context.config))
1203 let overhead = if fields.is_empty() { 1 } else { 0 };
1204 let total_width = result.len() + generics_str.len() + overhead;
1205 if !generics_str.is_empty()
1206 && !generics_str.contains('\n')
1207 && total_width > context.config.max_width()
1210 result.push_str(&offset.to_string(context.config));
1211 result.push_str(generics_str.trim_left());
1213 result.push_str(&generics_str);
1216 if fields.is_empty() {
1217 let inner_span = mk_sp(body_lo, span.hi() - BytePos(1));
1218 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "", "}");
1219 return Some(result);
1223 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1224 let one_line_budget =
1225 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1227 let items_str = rewrite_with_alignment(
1230 Shape::indented(offset, context.config).sub_width(1)?,
1231 mk_sp(body_lo, span.hi()),
1235 if !items_str.contains('\n')
1236 && !result.contains('\n')
1237 && items_str.len() <= one_line_budget
1238 && !last_line_contains_single_line_comment(&items_str)
1240 Some(format!("{} {} }}", result, items_str))
1246 .block_indent(context.config)
1247 .to_string(context.config),
1249 offset.to_string(context.config)
1254 fn get_bytepos_after_visibility(vis: &ast::Visibility, default_span: Span) -> BytePos {
1256 ast::VisibilityKind::Crate(..) | ast::VisibilityKind::Restricted { .. } => vis.span.hi(),
1257 _ => default_span.lo(),
1261 // Format tuple or struct without any fields. We need to make sure that the comments
1262 // inside the delimiters are preserved.
1263 fn format_empty_struct_or_tuple(
1264 context: &RewriteContext,
1267 result: &mut String,
1271 // 3 = " {}" or "();"
1272 let used_width = last_line_used_width(&result, offset.width()) + 3;
1273 if used_width > context.config.max_width() {
1274 result.push_str(&offset.to_string_with_newline(context.config))
1276 result.push_str(opener);
1277 match rewrite_missing_comment(span, Shape::indented(offset, context.config), context) {
1278 Some(ref s) if s.is_empty() => (),
1280 if !is_single_line(s) || first_line_contains_single_line_comment(s) {
1281 let nested_indent_str = offset
1282 .block_indent(context.config)
1283 .to_string_with_newline(context.config);
1284 result.push_str(&nested_indent_str);
1287 if last_line_contains_single_line_comment(s) {
1288 result.push_str(&offset.to_string_with_newline(context.config));
1291 None => result.push_str(context.snippet(span)),
1293 result.push_str(closer);
1296 fn format_tuple_struct(
1297 context: &RewriteContext,
1298 struct_parts: &StructParts,
1299 fields: &[ast::StructField],
1301 ) -> Option<String> {
1302 let mut result = String::with_capacity(1024);
1303 let span = struct_parts.span;
1305 let header_str = struct_parts.format_header(context);
1306 result.push_str(&header_str);
1308 let body_lo = if fields.is_empty() {
1309 let lo = get_bytepos_after_visibility(struct_parts.vis, span);
1312 .span_after(mk_sp(lo, span.hi()), "(")
1316 let body_hi = if fields.is_empty() {
1319 .span_after(mk_sp(body_lo, span.hi()), ")")
1321 // This is a dirty hack to work around a missing `)` from the span of the last field.
1322 let last_arg_span = fields[fields.len() - 1].span;
1325 .opt_span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1326 .unwrap_or(last_arg_span.hi())
1329 let where_clause_str = match struct_parts.generics {
1331 let budget = context.budget(last_line_width(&header_str));
1332 let shape = Shape::legacy(budget, offset);
1333 let generics_str = rewrite_generics(context, "", generics, shape)?;
1334 result.push_str(&generics_str);
1336 let where_budget = context.budget(last_line_width(&result));
1337 let option = WhereClauseOption::new(true, false);
1338 rewrite_where_clause(
1340 &generics.where_clause,
1341 context.config.brace_style(),
1342 Shape::legacy(where_budget, offset.block_only()),
1343 Density::Compressed,
1351 None => "".to_owned(),
1354 if fields.is_empty() {
1355 let body_hi = context
1357 .span_before(mk_sp(body_lo, span.hi()), ")");
1358 let inner_span = mk_sp(body_lo, body_hi);
1359 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "(", ")");
1361 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1362 let fields = &fields.iter().collect::<Vec<_>>();
1363 result = overflow::rewrite_with_parens(
1369 context.config.width_heuristics().fn_call_width,
1374 if !where_clause_str.is_empty()
1375 && !where_clause_str.contains('\n')
1376 && (result.contains('\n')
1377 || offset.block_indent + result.len() + where_clause_str.len() + 1
1378 > context.config.max_width())
1380 // We need to put the where clause on a new line, but we didn't
1381 // know that earlier, so the where clause will not be indented properly.
1384 &(offset.block_only() + (context.config.tab_spaces() - 1)).to_string(context.config),
1387 result.push_str(&where_clause_str);
1392 fn rewrite_type_prefix(
1393 context: &RewriteContext,
1397 generics: &ast::Generics,
1398 ) -> Option<String> {
1399 let mut result = String::with_capacity(128);
1400 result.push_str(prefix);
1401 let ident_str = rewrite_ident(context, ident);
1404 if generics.params.is_empty() {
1405 result.push_str(ident_str)
1407 let g_shape = Shape::indented(indent, context.config)
1408 .offset_left(result.len())?
1410 let generics_str = rewrite_generics(context, ident_str, generics, g_shape)?;
1411 result.push_str(&generics_str);
1414 let where_budget = context.budget(last_line_width(&result));
1415 let option = WhereClauseOption::snuggled(&result);
1416 let where_clause_str = rewrite_where_clause(
1418 &generics.where_clause,
1419 context.config.brace_style(),
1420 Shape::legacy(where_budget, indent),
1428 result.push_str(&where_clause_str);
1433 fn rewrite_type_item<R: Rewrite>(
1434 context: &RewriteContext,
1440 generics: &ast::Generics,
1441 vis: &ast::Visibility,
1442 ) -> Option<String> {
1443 let mut result = String::with_capacity(128);
1444 result.push_str(&rewrite_type_prefix(
1447 &format!("{}{} ", format_visibility(context, vis), prefix),
1452 if generics.where_clause.predicates.is_empty() {
1453 result.push_str(suffix);
1455 result.push_str(&indent.to_string_with_newline(context.config));
1456 result.push_str(suffix.trim_left());
1460 let rhs_shape = Shape::indented(indent, context.config).sub_width(1)?;
1461 rewrite_assign_rhs(context, result, rhs, rhs_shape).map(|s| s + ";")
1464 pub fn rewrite_type_alias(
1465 context: &RewriteContext,
1469 generics: &ast::Generics,
1470 vis: &ast::Visibility,
1471 ) -> Option<String> {
1472 rewrite_type_item(context, indent, "type", " =", ident, ty, generics, vis)
1475 pub fn rewrite_existential_type(
1476 context: &RewriteContext,
1479 generic_bounds: &ast::GenericBounds,
1480 generics: &ast::Generics,
1481 vis: &ast::Visibility,
1482 ) -> Option<String> {
1495 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1497 if config.space_before_colon() { " " } else { "" },
1498 if config.space_after_colon() { " " } else { "" },
1502 pub fn rewrite_struct_field_prefix(
1503 context: &RewriteContext,
1504 field: &ast::StructField,
1505 ) -> Option<String> {
1506 let vis = format_visibility(context, &field.vis);
1507 let type_annotation_spacing = type_annotation_spacing(context.config);
1508 Some(match field.ident {
1509 Some(name) => format!(
1512 rewrite_ident(context, name),
1513 type_annotation_spacing.0
1515 None => format!("{}", vis),
1519 impl Rewrite for ast::StructField {
1520 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1521 rewrite_struct_field(context, self, shape, 0)
1525 pub fn rewrite_struct_field(
1526 context: &RewriteContext,
1527 field: &ast::StructField,
1529 lhs_max_width: usize,
1530 ) -> Option<String> {
1531 if contains_skip(&field.attrs) {
1532 return Some(context.snippet(field.span()).to_owned());
1535 let type_annotation_spacing = type_annotation_spacing(context.config);
1536 let prefix = rewrite_struct_field_prefix(context, field)?;
1538 let attrs_str = field.attrs.rewrite(context, shape)?;
1539 let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
1540 let missing_span = if field.attrs.is_empty() {
1541 mk_sp(field.span.lo(), field.span.lo())
1543 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1545 let mut spacing = String::from(if field.ident.is_some() {
1546 type_annotation_spacing.1
1550 // Try to put everything on a single line.
1551 let attr_prefix = combine_strs_with_missing_comments(
1559 let overhead = last_line_width(&attr_prefix);
1560 let lhs_offset = lhs_max_width.saturating_sub(overhead);
1561 for _ in 0..lhs_offset {
1564 // In this extreme case we will be missing a space betweeen an attribute and a field.
1565 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1569 .offset_left(overhead + spacing.len())
1570 .and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
1571 if let Some(ref ty) = orig_ty {
1572 if !ty.contains('\n') {
1573 return Some(attr_prefix + &spacing + ty);
1577 let is_prefix_empty = prefix.is_empty();
1578 // We must use multiline. We are going to put attributes and a field on different lines.
1579 let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, shape)?;
1580 // Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
1581 let field_str = if is_prefix_empty {
1582 field_str.trim_left()
1586 combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
1589 pub struct StaticParts<'a> {
1591 vis: &'a ast::Visibility,
1594 mutability: ast::Mutability,
1595 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1596 defaultness: Option<ast::Defaultness>,
1600 impl<'a> StaticParts<'a> {
1601 pub fn from_item(item: &'a ast::Item) -> Self {
1602 let (prefix, ty, mutability, expr) = match item.node {
1603 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1604 ast::ItemKind::Const(ref ty, ref expr) => {
1605 ("const", ty, ast::Mutability::Immutable, expr)
1607 _ => unreachable!(),
1615 expr_opt: Some(expr),
1621 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1622 let (ty, expr_opt) = match ti.node {
1623 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1624 _ => unreachable!(),
1628 vis: &DEFAULT_VISIBILITY,
1631 mutability: ast::Mutability::Immutable,
1632 expr_opt: expr_opt.as_ref(),
1638 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1639 let (ty, expr) = match ii.node {
1640 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1641 _ => unreachable!(),
1648 mutability: ast::Mutability::Immutable,
1649 expr_opt: Some(expr),
1650 defaultness: Some(ii.defaultness),
1657 context: &RewriteContext,
1658 static_parts: &StaticParts,
1660 ) -> Option<String> {
1661 let colon = colon_spaces(
1662 context.config.space_before_colon(),
1663 context.config.space_after_colon(),
1665 let mut prefix = format!(
1667 format_visibility(context, static_parts.vis),
1668 static_parts.defaultness.map_or("", format_defaultness),
1669 static_parts.prefix,
1670 format_mutability(static_parts.mutability),
1676 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1677 let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
1678 Some(ty_str) => ty_str,
1680 if prefix.ends_with(' ') {
1683 let nested_indent = offset.block_indent(context.config);
1684 let nested_shape = Shape::indented(nested_indent, context.config);
1685 let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
1688 nested_indent.to_string_with_newline(context.config),
1694 if let Some(expr) = static_parts.expr_opt {
1695 let lhs = format!("{}{} =", prefix, ty_str);
1697 let remaining_width = context.budget(offset.block_indent + 1);
1702 Shape::legacy(remaining_width, offset.block_only()),
1703 ).and_then(|res| recover_comment_removed(res, static_parts.span, context))
1704 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1706 Some(format!("{}{};", prefix, ty_str))
1710 pub fn rewrite_associated_type(
1712 ty_opt: Option<&ptr::P<ast::Ty>>,
1713 generic_bounds_opt: Option<&ast::GenericBounds>,
1714 context: &RewriteContext,
1716 ) -> Option<String> {
1717 let prefix = format!("type {}", rewrite_ident(context, ident));
1719 let type_bounds_str = if let Some(bounds) = generic_bounds_opt {
1720 if bounds.is_empty() {
1724 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1725 bounds.rewrite(context, shape).map(|s| format!(": {}", s))?
1731 if let Some(ty) = ty_opt {
1733 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1734 let lhs = format!("{}{} =", prefix, type_bounds_str);
1735 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1737 Some(format!("{}{};", prefix, type_bounds_str))
1741 pub fn rewrite_existential_impl_type(
1742 context: &RewriteContext,
1744 generic_bounds: &ast::GenericBounds,
1746 ) -> Option<String> {
1747 rewrite_associated_type(ident, None, Some(generic_bounds), context, indent)
1748 .map(|s| format!("existential {}", s))
1751 pub fn rewrite_associated_impl_type(
1753 defaultness: ast::Defaultness,
1754 ty_opt: Option<&ptr::P<ast::Ty>>,
1755 context: &RewriteContext,
1757 ) -> Option<String> {
1758 let result = rewrite_associated_type(ident, ty_opt, None, context, indent)?;
1761 ast::Defaultness::Default => Some(format!("default {}", result)),
1766 impl Rewrite for ast::FunctionRetTy {
1767 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1769 ast::FunctionRetTy::Default(_) => Some(String::new()),
1770 ast::FunctionRetTy::Ty(ref ty) => {
1771 let inner_width = shape.width.checked_sub(3)?;
1772 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1773 .map(|r| format!("-> {}", r))
1779 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1781 ast::TyKind::Infer => {
1782 let original = context.snippet(ty.span);
1789 impl Rewrite for ast::Arg {
1790 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1791 if is_named_arg(self) {
1792 let mut result = self
1794 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1796 if !is_empty_infer(context, &*self.ty) {
1797 if context.config.space_before_colon() {
1798 result.push_str(" ");
1800 result.push_str(":");
1801 if context.config.space_after_colon() {
1802 result.push_str(" ");
1804 let overhead = last_line_width(&result);
1805 let max_width = shape.width.checked_sub(overhead)?;
1808 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1809 result.push_str(&ty_str);
1814 self.ty.rewrite(context, shape)
1819 fn rewrite_explicit_self(
1820 explicit_self: &ast::ExplicitSelf,
1822 context: &RewriteContext,
1823 ) -> Option<String> {
1824 match explicit_self.node {
1825 ast::SelfKind::Region(lt, m) => {
1826 let mut_str = format_mutability(m);
1829 let lifetime_str = l.rewrite(
1831 Shape::legacy(context.config.max_width(), Indent::empty()),
1833 Some(format!("&{} {}self", lifetime_str, mut_str))
1835 None => Some(format!("&{}self", mut_str)),
1838 ast::SelfKind::Explicit(ref ty, _) => {
1839 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1841 let mutability = explicit_self_mutability(&args[0]);
1842 let type_str = ty.rewrite(
1844 Shape::legacy(context.config.max_width(), Indent::empty()),
1849 format_mutability(mutability),
1853 ast::SelfKind::Value(_) => {
1854 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1856 let mutability = explicit_self_mutability(&args[0]);
1858 Some(format!("{}self", format_mutability(mutability)))
1863 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1864 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1865 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1866 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1873 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1874 if is_named_arg(arg) {
1881 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1883 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1884 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1885 _ => arg.ty.span.hi(),
1889 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1890 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1891 ident != symbol::keywords::Invalid.ident()
1897 // Return type is (result, force_new_line_for_brace)
1899 context: &RewriteContext,
1904 newline_brace: bool,
1906 ) -> Option<(String, bool)> {
1907 let mut force_new_line_for_brace = false;
1909 let where_clause = &fn_sig.generics.where_clause;
1911 let mut result = String::with_capacity(1024);
1912 result.push_str(&fn_sig.to_str(context));
1915 result.push_str("fn ");
1918 let overhead = if has_body && !newline_brace {
1925 let used_width = last_line_used_width(&result, indent.width());
1926 let one_line_budget = context.budget(used_width + overhead);
1928 width: one_line_budget,
1932 let fd = fn_sig.decl;
1933 let generics_str = rewrite_generics(
1935 rewrite_ident(context, ident),
1939 result.push_str(&generics_str);
1941 let snuggle_angle_bracket = generics_str
1944 .map_or(false, |l| l.trim_left().len() == 1);
1946 // Note that the width and indent don't really matter, we'll re-layout the
1947 // return type later anyway.
1950 .rewrite(context, Shape::indented(indent, context.config))?;
1952 let multi_line_ret_str = ret_str.contains('\n');
1953 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1956 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1967 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1968 one_line_budget, multi_line_budget, arg_indent
1971 // Check if vertical layout was forced.
1972 if one_line_budget == 0 {
1973 if snuggle_angle_bracket {
1976 result.push_str("(");
1977 if context.config.indent_style() == IndentStyle::Visual {
1978 result.push_str(&arg_indent.to_string_with_newline(context.config));
1985 // Skip `pub(crate)`.
1986 let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
1987 // A conservative estimation, to goal is to be over all parens in generics
1988 let args_start = fn_sig
1993 .map_or(lo_after_visibility, |param| param.span().hi());
1994 let args_end = if fd.inputs.is_empty() {
1997 .span_after(mk_sp(args_start, span.hi()), ")")
1999 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
2000 context.snippet_provider.span_after(last_span, ")")
2002 let args_span = mk_sp(
2005 .span_after(mk_sp(args_start, span.hi()), "("),
2008 let arg_str = rewrite_args(
2011 fd.get_self().as_ref(),
2018 generics_str.contains('\n'),
2021 let put_args_in_block = match context.config.indent_style() {
2022 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
2024 } && !fd.inputs.is_empty();
2026 let mut args_last_line_contains_comment = false;
2027 if put_args_in_block {
2028 arg_indent = indent.block_indent(context.config);
2029 result.push_str(&arg_indent.to_string_with_newline(context.config));
2030 result.push_str(&arg_str);
2031 result.push_str(&indent.to_string_with_newline(context.config));
2034 result.push_str(&arg_str);
2035 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
2036 // Put the closing brace on the next line if it overflows the max width.
2038 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
2041 // If the last line of args contains comment, we cannot put the closing paren
2042 // on the same line.
2046 .map_or(false, |last_line| last_line.contains("//"))
2048 args_last_line_contains_comment = true;
2049 result.push_str(&arg_indent.to_string_with_newline(context.config));
2055 if let ast::FunctionRetTy::Ty(..) = fd.output {
2056 let ret_should_indent = match context.config.indent_style() {
2057 // If our args are block layout then we surely must have space.
2058 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
2059 _ if args_last_line_contains_comment => false,
2060 _ if result.contains('\n') || multi_line_ret_str => true,
2062 // If the return type would push over the max width, then put the return type on
2063 // a new line. With the +1 for the signature length an additional space between
2064 // the closing parenthesis of the argument and the arrow '->' is considered.
2065 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
2067 // If there is no where clause, take into account the space after the return type
2069 if where_clause.predicates.is_empty() {
2073 sig_length > context.config.max_width()
2076 let ret_indent = if ret_should_indent {
2077 let indent = if arg_str.is_empty() {
2078 // Aligning with non-existent args looks silly.
2079 force_new_line_for_brace = true;
2082 // FIXME: we might want to check that using the arg indent
2083 // doesn't blow our budget, and if it does, then fallback to
2084 // the where clause indent.
2088 result.push_str(&indent.to_string_with_newline(context.config));
2092 Indent::new(indent.block_indent, last_line_width(&result))
2095 if multi_line_ret_str || ret_should_indent {
2096 // Now that we know the proper indent and width, we need to
2097 // re-layout the return type.
2100 .rewrite(context, Shape::indented(ret_indent, context.config))?;
2101 result.push_str(&ret_str);
2103 result.push_str(&ret_str);
2106 // Comment between return type and the end of the decl.
2107 let snippet_lo = fd.output.span().hi();
2108 if where_clause.predicates.is_empty() {
2109 let snippet_hi = span.hi();
2110 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2111 // Try to preserve the layout of the original snippet.
2112 let original_starts_with_newline = snippet
2114 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2115 let original_ends_with_newline = snippet
2116 .rfind(|c| c != ' ')
2117 .map_or(false, |i| snippet[i..].ends_with('\n'));
2118 let snippet = snippet.trim();
2119 if !snippet.is_empty() {
2120 result.push(if original_starts_with_newline {
2125 result.push_str(snippet);
2126 if original_ends_with_newline {
2127 force_new_line_for_brace = true;
2133 let pos_before_where = match fd.output {
2134 ast::FunctionRetTy::Default(..) => args_span.hi(),
2135 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2138 let is_args_multi_lined = arg_str.contains('\n');
2140 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2141 let where_clause_str = rewrite_where_clause(
2144 context.config.brace_style(),
2145 Shape::indented(indent, context.config),
2151 is_args_multi_lined,
2153 // If there are neither where clause nor return type, we may be missing comments between
2155 if where_clause_str.is_empty() {
2156 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2157 match recover_missing_comment_in_span(
2158 mk_sp(args_span.hi(), ret_span.hi()),
2161 last_line_width(&result),
2163 Some(ref missing_comment) if !missing_comment.is_empty() => {
2164 result.push_str(missing_comment);
2165 force_new_line_for_brace = true;
2172 result.push_str(&where_clause_str);
2174 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2175 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2176 Some((result, force_new_line_for_brace))
2179 #[derive(Copy, Clone)]
2180 struct WhereClauseOption {
2181 suppress_comma: bool, // Force no trailing comma
2182 snuggle: bool, // Do not insert newline before `where`
2183 compress_where: bool, // Try single line where clause instead of vertical layout
2186 impl WhereClauseOption {
2187 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2191 compress_where: false,
2195 pub fn snuggled(current: &str) -> WhereClauseOption {
2197 suppress_comma: false,
2198 snuggle: last_line_width(current) == 1,
2199 compress_where: false,
2203 pub fn suppress_comma(&mut self) {
2204 self.suppress_comma = true
2207 pub fn compress_where(&mut self) {
2208 self.compress_where = true
2211 pub fn snuggle(&mut self) {
2217 context: &RewriteContext,
2219 explicit_self: Option<&ast::ExplicitSelf>,
2220 one_line_budget: usize,
2221 multi_line_budget: usize,
2226 generics_str_contains_newline: bool,
2227 ) -> Option<String> {
2228 let mut arg_item_strs = args
2230 .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
2231 .collect::<Option<Vec<_>>>()?;
2233 // Account for sugary self.
2234 // FIXME: the comment for the self argument is dropped. This is blocked
2235 // on rust issue #27522.
2236 let min_args = explicit_self
2237 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2238 .map_or(1, |self_str| {
2239 arg_item_strs[0] = self_str;
2243 // Comments between args.
2244 let mut arg_items = Vec::new();
2246 arg_items.push(ListItem::from_str(""));
2249 // FIXME(#21): if there are no args, there might still be a comment, but
2250 // without spans for the comment or parens, there is no chance of
2251 // getting it right. You also don't get to put a comment on self, unless
2253 if args.len() >= min_args || variadic {
2254 let comment_span_start = if min_args == 2 {
2255 let second_arg_start = if arg_has_pattern(&args[1]) {
2256 args[1].pat.span.lo()
2258 args[1].ty.span.lo()
2260 let reduced_span = mk_sp(span.lo(), second_arg_start);
2262 context.snippet_provider.span_after_last(reduced_span, ",")
2267 enum ArgumentKind<'a> {
2268 Regular(&'a ast::Arg),
2272 let variadic_arg = if variadic {
2273 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2274 let variadic_start =
2275 context.snippet_provider.span_after(variadic_span, "...") - BytePos(3);
2276 Some(ArgumentKind::Variadic(variadic_start))
2281 let more_items = itemize_list(
2282 context.snippet_provider,
2283 args[min_args - 1..]
2285 .map(ArgumentKind::Regular)
2286 .chain(variadic_arg),
2290 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2291 ArgumentKind::Variadic(start) => start,
2294 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2295 ArgumentKind::Variadic(start) => start + BytePos(3),
2298 ArgumentKind::Regular(..) => None,
2299 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2306 arg_items.extend(more_items);
2309 let fits_in_one_line = !generics_str_contains_newline
2310 && (arg_items.is_empty()
2311 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2313 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2314 item.item = Some(arg);
2317 let last_line_ends_with_comment = arg_items
2320 .and_then(|item| item.post_comment.as_ref())
2321 .map_or(false, |s| s.trim().starts_with("//"));
2323 let (indent, trailing_comma) = match context.config.indent_style() {
2324 IndentStyle::Block if fits_in_one_line => {
2325 (indent.block_indent(context.config), SeparatorTactic::Never)
2327 IndentStyle::Block => (
2328 indent.block_indent(context.config),
2329 context.config.trailing_comma(),
2331 IndentStyle::Visual if last_line_ends_with_comment => {
2332 (arg_indent, context.config.trailing_comma())
2334 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2337 let tactic = definitive_tactic(
2339 context.config.fn_args_density().to_list_tactic(),
2343 let budget = match tactic {
2344 DefinitiveListTactic::Horizontal => one_line_budget,
2345 _ => multi_line_budget,
2348 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2350 let fmt = ListFormatting {
2353 trailing_separator: if variadic {
2354 SeparatorTactic::Never
2358 separator_place: SeparatorPlace::Back,
2359 shape: Shape::legacy(budget, indent),
2360 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2361 preserve_newline: true,
2363 config: context.config,
2366 write_list(&arg_items, &fmt)
2369 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2370 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2371 ident != symbol::keywords::Invalid.ident()
2377 fn compute_budgets_for_args(
2378 context: &RewriteContext,
2382 newline_brace: bool,
2384 force_vertical_layout: bool,
2385 ) -> Option<((usize, usize, Indent))> {
2387 "compute_budgets_for_args {} {:?}, {}, {}",
2393 // Try keeping everything on the same line.
2394 if !result.contains('\n') && !force_vertical_layout {
2395 // 2 = `()`, 3 = `() `, space is before ret_string.
2396 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2397 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2407 let one_line_budget = context.budget(used_space);
2409 if one_line_budget > 0 {
2411 let (indent, multi_line_budget) = match context.config.indent_style() {
2412 IndentStyle::Block => {
2413 let indent = indent.block_indent(context.config);
2414 (indent, context.budget(indent.width() + 1))
2416 IndentStyle::Visual => {
2417 let indent = indent + result.len() + 1;
2418 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2419 (indent, context.budget(multi_line_overhead))
2423 return Some((one_line_budget, multi_line_budget, indent));
2427 // Didn't work. we must force vertical layout and put args on a newline.
2428 let new_indent = indent.block_indent(context.config);
2429 let used_space = match context.config.indent_style() {
2431 IndentStyle::Block => new_indent.width() + 1,
2432 // Account for `)` and possibly ` {`.
2433 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2435 Some((0, context.budget(used_space), new_indent))
2438 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2439 let predicate_count = where_clause.predicates.len();
2441 if config.where_single_line() && predicate_count == 1 {
2444 let brace_style = config.brace_style();
2446 brace_style == BraceStyle::AlwaysNextLine
2447 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2450 fn rewrite_generics(
2451 context: &RewriteContext,
2453 generics: &ast::Generics,
2455 ) -> Option<String> {
2456 // FIXME: convert bounds to where clauses where they get too big or if
2457 // there is a where clause at all.
2459 if generics.params.is_empty() {
2460 return Some(ident.to_owned());
2463 let params = &generics.params.iter().map(|e| &*e).collect::<Vec<_>>();
2464 overflow::rewrite_with_angle_brackets(context, ident, params, shape, generics.span)
2467 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2468 match config.indent_style() {
2469 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2470 IndentStyle::Block => {
2474 .block_indent(config.tab_spaces())
2475 .with_max_width(config)
2481 fn rewrite_where_clause_rfc_style(
2482 context: &RewriteContext,
2483 where_clause: &ast::WhereClause,
2486 span_end: Option<BytePos>,
2487 span_end_before_where: BytePos,
2488 where_clause_option: WhereClauseOption,
2489 is_args_multi_line: bool,
2490 ) -> Option<String> {
2491 let block_shape = shape.block().with_max_width(context.config);
2493 let (span_before, span_after) =
2494 missing_span_before_after_where(span_end_before_where, where_clause);
2495 let (comment_before, comment_after) =
2496 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2498 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2501 block_shape.indent.to_string_with_newline(context.config)
2504 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2506 let clause_shape = clause_shape.sub_width(1)?;
2507 // each clause on one line, trailing comma (except if suppress_comma)
2508 let span_start = where_clause.predicates[0].span().lo();
2509 // If we don't have the start of the next span, then use the end of the
2510 // predicates, but that means we miss comments.
2511 let len = where_clause.predicates.len();
2512 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2513 let span_end = span_end.unwrap_or(end_of_preds);
2514 let items = itemize_list(
2515 context.snippet_provider,
2516 where_clause.predicates.iter(),
2519 |pred| pred.span().lo(),
2520 |pred| pred.span().hi(),
2521 |pred| pred.rewrite(context, clause_shape),
2526 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2527 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2528 SeparatorTactic::Never
2530 context.config.trailing_comma()
2533 // shape should be vertical only and only if we have `where_single_line` option enabled
2534 // and the number of items of the where clause is equal to 1
2535 let shape_tactic = if where_single_line {
2536 DefinitiveListTactic::Horizontal
2538 DefinitiveListTactic::Vertical
2541 let fmt = ListFormatting {
2542 tactic: shape_tactic,
2544 trailing_separator: comma_tactic,
2545 separator_place: SeparatorPlace::Back,
2546 shape: clause_shape,
2547 ends_with_newline: true,
2548 preserve_newline: true,
2550 config: context.config,
2552 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2554 let comment_separator = |comment: &str, shape: Shape| {
2555 if comment.is_empty() {
2558 shape.indent.to_string_with_newline(context.config)
2561 let newline_before_where = comment_separator(&comment_before, shape);
2562 let newline_after_where = comment_separator(&comment_after, clause_shape);
2565 let clause_sep = if where_clause_option.compress_where
2566 && comment_before.is_empty()
2567 && comment_after.is_empty()
2568 && !preds_str.contains('\n')
2569 && 6 + preds_str.len() <= shape.width
2570 || where_single_line
2574 clause_shape.indent.to_string_with_newline(context.config)
2577 "{}{}{}where{}{}{}{}",
2580 newline_before_where,
2581 newline_after_where,
2588 fn rewrite_where_clause(
2589 context: &RewriteContext,
2590 where_clause: &ast::WhereClause,
2591 brace_style: BraceStyle,
2595 span_end: Option<BytePos>,
2596 span_end_before_where: BytePos,
2597 where_clause_option: WhereClauseOption,
2598 is_args_multi_line: bool,
2599 ) -> Option<String> {
2600 if where_clause.predicates.is_empty() {
2601 return Some(String::new());
2604 if context.config.indent_style() == IndentStyle::Block {
2605 return rewrite_where_clause_rfc_style(
2611 span_end_before_where,
2612 where_clause_option,
2617 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2619 let offset = match context.config.indent_style() {
2620 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2621 // 6 = "where ".len()
2622 IndentStyle::Visual => shape.indent + extra_indent + 6,
2624 // FIXME: if indent_style != Visual, then the budgets below might
2625 // be out by a char or two.
2627 let budget = context.config.max_width() - offset.width();
2628 let span_start = where_clause.predicates[0].span().lo();
2629 // If we don't have the start of the next span, then use the end of the
2630 // predicates, but that means we miss comments.
2631 let len = where_clause.predicates.len();
2632 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2633 let span_end = span_end.unwrap_or(end_of_preds);
2634 let items = itemize_list(
2635 context.snippet_provider,
2636 where_clause.predicates.iter(),
2639 |pred| pred.span().lo(),
2640 |pred| pred.span().hi(),
2641 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2646 let item_vec = items.collect::<Vec<_>>();
2647 // FIXME: we don't need to collect here
2648 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2650 let mut comma_tactic = context.config.trailing_comma();
2651 // Kind of a hack because we don't usually have trailing commas in where clauses.
2652 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2653 comma_tactic = SeparatorTactic::Never;
2656 let fmt = ListFormatting {
2659 trailing_separator: comma_tactic,
2660 separator_place: SeparatorPlace::Back,
2661 shape: Shape::legacy(budget, offset),
2662 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2663 preserve_newline: true,
2665 config: context.config,
2667 let preds_str = write_list(&item_vec, &fmt)?;
2669 let end_length = if terminator == "{" {
2670 // If the brace is on the next line we don't need to count it otherwise it needs two
2673 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2674 BraceStyle::PreferSameLine => 2,
2676 } else if terminator == "=" {
2681 if density == Density::Tall
2682 || preds_str.contains('\n')
2683 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2687 (shape.indent + extra_indent).to_string(context.config),
2691 Some(format!(" where {}", preds_str))
2695 fn missing_span_before_after_where(
2696 before_item_span_end: BytePos,
2697 where_clause: &ast::WhereClause,
2699 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2701 let pos_after_where = where_clause.span.lo() + BytePos(5);
2702 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2703 (missing_span_before, missing_span_after)
2706 fn rewrite_comments_before_after_where(
2707 context: &RewriteContext,
2708 span_before_where: Span,
2709 span_after_where: Span,
2711 ) -> Option<(String, String)> {
2712 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2713 let after_comment = rewrite_missing_comment(
2715 shape.block_indent(context.config.tab_spaces()),
2718 Some((before_comment, after_comment))
2722 context: &RewriteContext,
2725 vis: &ast::Visibility,
2729 format_visibility(context, vis),
2731 rewrite_ident(context, ident)
2735 #[derive(PartialEq, Eq, Clone, Copy)]
2743 context: &RewriteContext,
2744 generics: &ast::Generics,
2745 brace_style: BraceStyle,
2746 brace_pos: BracePos,
2750 ) -> Option<String> {
2751 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2752 let mut result = rewrite_generics(context, "", generics, shape)?;
2754 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2755 let budget = context.budget(last_line_used_width(&result, offset.width()));
2756 let mut option = WhereClauseOption::snuggled(&result);
2757 if brace_pos == BracePos::None {
2758 option.suppress_comma = true;
2760 // If the generics are not parameterized then generics.span.hi() == 0,
2761 // so we use span.lo(), which is the position after `struct Foo`.
2762 let span_end_before_where = if !generics.params.is_empty() {
2767 let where_clause_str = rewrite_where_clause(
2769 &generics.where_clause,
2771 Shape::legacy(budget, offset.block_only()),
2775 span_end_before_where,
2779 result.push_str(&where_clause_str);
2780 brace_pos == BracePos::ForceSameLine
2781 || brace_style == BraceStyle::PreferSameLine
2782 || (generics.where_clause.predicates.is_empty()
2783 && trimmed_last_line_width(&result) == 1)
2785 brace_pos == BracePos::ForceSameLine
2786 || trimmed_last_line_width(&result) == 1
2787 || brace_style != BraceStyle::AlwaysNextLine
2789 if brace_pos == BracePos::None {
2790 return Some(result);
2792 let total_used_width = last_line_used_width(&result, used_width);
2793 let remaining_budget = context.budget(total_used_width);
2794 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2795 // and hence we take the closer into account as well for one line budget.
2796 // We assume that the closer has the same length as the opener.
2797 let overhead = if brace_pos == BracePos::ForceSameLine {
2804 let forbid_same_line_brace = overhead > remaining_budget;
2805 if !forbid_same_line_brace && same_line_brace {
2809 result.push_str(&offset.block_only().to_string(context.config));
2816 impl Rewrite for ast::ForeignItem {
2817 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2818 let attrs_str = self.attrs.rewrite(context, shape)?;
2819 // Drop semicolon or it will be interpreted as comment.
2820 // FIXME: this may be a faulty span from libsyntax.
2821 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2823 let item_str = match self.node {
2824 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => rewrite_fn_base(
2828 &FnSig::new(fn_decl, generics, self.vis.clone()),
2832 ).map(|(s, _)| format!("{};", s)),
2833 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2834 // FIXME(#21): we're dropping potential comments in between the
2835 // function keywords here.
2836 let vis = format_visibility(context, &self.vis);
2837 let mut_str = if is_mutable { "mut " } else { "" };
2838 let prefix = format!(
2842 rewrite_ident(context, self.ident)
2845 rewrite_assign_rhs(context, prefix, &**ty, shape.sub_width(1)?).map(|s| s + ";")
2847 ast::ForeignItemKind::Ty => {
2848 let vis = format_visibility(context, &self.vis);
2852 rewrite_ident(context, self.ident)
2855 ast::ForeignItemKind::Macro(ref mac) => {
2856 rewrite_macro(mac, None, context, shape, MacroPosition::Item)
2860 let missing_span = if self.attrs.is_empty() {
2861 mk_sp(self.span.lo(), self.span.lo())
2863 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2865 combine_strs_with_missing_comments(
2876 /// Rewrite an inline mod.
2877 pub fn rewrite_mod(context: &RewriteContext, item: &ast::Item) -> String {
2878 let mut result = String::with_capacity(32);
2879 result.push_str(&*format_visibility(context, &item.vis));
2880 result.push_str("mod ");
2881 result.push_str(rewrite_ident(context, item.ident));
2886 /// Rewrite `extern crate foo;` WITHOUT attributes.
2887 pub fn rewrite_extern_crate(context: &RewriteContext, item: &ast::Item) -> Option<String> {
2888 assert!(is_extern_crate(item));
2889 let new_str = context.snippet(item.span);
2890 Some(if contains_comment(new_str) {
2893 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
2894 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
2898 /// Returns true for `mod foo;`, false for `mod foo { .. }`.
2899 pub fn is_mod_decl(item: &ast::Item) -> bool {
2901 ast::ItemKind::Mod(ref m) => m.inner.hi() != item.span.hi(),
2906 pub fn is_use_item(item: &ast::Item) -> bool {
2908 ast::ItemKind::Use(_) => true,
2913 pub fn is_extern_crate(item: &ast::Item) -> bool {
2915 ast::ItemKind::ExternCrate(..) => true,