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::ast::{CrateSugar, ImplItem};
20 use syntax::codemap::{BytePos, Span};
23 use codemap::{LineRangeUtils, SpanUtils};
24 use comment::{combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
25 recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented};
26 use config::{BraceStyle, Config, Density, IndentStyle};
27 use expr::{format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs,
28 rewrite_call_inner, ExprType};
29 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, ListItem, Separator};
30 use rewrite::{Rewrite, RewriteContext};
31 use shape::{Indent, Shape};
33 use types::join_bounds;
34 use utils::{colon_spaces, contains_skip, first_line_width, format_abi, format_constness,
35 format_defaultness, format_mutability, format_unsafety, format_visibility,
36 is_attributes_extendable, last_line_contains_single_line_comment,
37 last_line_extendable, last_line_used_width, last_line_width, mk_sp,
38 semicolon_for_expr, starts_with_newline, stmt_expr, trimmed_last_line_width};
39 use vertical::rewrite_with_alignment;
40 use visitor::FmtVisitor;
42 fn type_annotation_separator(config: &Config) -> &str {
43 colon_spaces(config.space_before_colon(), config.space_after_colon())
46 // Statements of the form
47 // let pat: ty = init;
48 impl Rewrite for ast::Local {
49 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
51 "Local::rewrite {:?} {} {:?}",
52 self, shape.width, shape.indent
55 skip_out_of_file_lines_range!(context, self.span);
57 if contains_skip(&self.attrs) {
61 let attrs_str = self.attrs.rewrite(context, shape)?;
62 let mut result = if attrs_str.is_empty() {
65 combine_strs_with_missing_comments(
70 self.attrs.last().map(|a| a.span.hi()).unwrap(),
79 let pat_shape = shape.offset_left(4)?;
81 let pat_shape = pat_shape.sub_width(1)?;
82 let pat_str = self.pat.rewrite(context, pat_shape)?;
83 result.push_str(&pat_str);
85 // String that is placed within the assignment pattern and expression.
87 let mut infix = String::with_capacity(32);
89 if let Some(ref ty) = self.ty {
90 let separator = type_annotation_separator(context.config);
91 let indent = shape.indent + last_line_width(&result) + separator.len();
93 let budget = shape.width.checked_sub(indent.width() + 1)?;
94 let rewrite = ty.rewrite(context, Shape::legacy(budget, indent))?;
96 infix.push_str(separator);
97 infix.push_str(&rewrite);
100 if self.init.is_some() {
101 infix.push_str(" =");
107 result.push_str(&infix);
109 if let Some(ref ex) = self.init {
110 // 1 = trailing semicolon;
111 let nested_shape = shape.sub_width(1)?;
113 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
121 // TODO convert to using rewrite style rather than visitor
122 // TODO format modules in this style
125 keyword: &'static str,
126 abi: Cow<'static, str>,
127 vis: Option<&'a ast::Visibility>,
128 body: Vec<BodyElement<'a>>,
133 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
136 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
140 .map(|i| BodyElement::ForeignItem(i))
147 enum BodyElement<'a> {
148 // Stmt(&'a ast::Stmt),
149 // Field(&'a ast::Field),
150 // Variant(&'a ast::Variant),
151 // Item(&'a ast::Item),
152 ForeignItem(&'a ast::ForeignItem),
155 /// Represents a fn's signature.
156 pub struct FnSig<'a> {
157 decl: &'a ast::FnDecl,
158 generics: &'a ast::Generics,
160 constness: ast::Constness,
161 defaultness: ast::Defaultness,
162 unsafety: ast::Unsafety,
163 visibility: ast::Visibility,
168 decl: &'a ast::FnDecl,
169 generics: &'a ast::Generics,
170 vis: ast::Visibility,
176 constness: ast::Constness::NotConst,
177 defaultness: ast::Defaultness::Final,
178 unsafety: ast::Unsafety::Normal,
183 pub fn from_method_sig(
184 method_sig: &'a ast::MethodSig,
185 generics: &'a ast::Generics,
188 unsafety: method_sig.unsafety,
189 constness: method_sig.constness.node,
190 defaultness: ast::Defaultness::Final,
192 decl: &*method_sig.decl,
194 visibility: ast::Visibility::Inherited,
199 fn_kind: &'a visit::FnKind,
200 generics: &'a ast::Generics,
201 decl: &'a ast::FnDecl,
202 defualtness: ast::Defaultness,
205 visit::FnKind::ItemFn(_, unsafety, constness, abi, visibility, _) => FnSig {
209 constness: constness.node,
210 defaultness: defualtness,
212 visibility: visibility.clone(),
214 visit::FnKind::Method(_, method_sig, vis, _) => {
215 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
216 fn_sig.defaultness = defualtness;
217 if let Some(vis) = vis {
218 fn_sig.visibility = vis.clone();
226 fn to_str(&self, context: &RewriteContext) -> String {
227 let mut result = String::with_capacity(128);
228 // Vis defaultness constness unsafety abi.
229 result.push_str(&*format_visibility(&self.visibility));
230 result.push_str(format_defaultness(self.defaultness));
231 result.push_str(format_constness(self.constness));
232 result.push_str(format_unsafety(self.unsafety));
233 result.push_str(&format_abi(
235 context.config.force_explicit_abi(),
242 impl<'a> FmtVisitor<'a> {
243 fn format_item(&mut self, item: &Item) {
244 self.buffer.push_str(&item.abi);
246 let snippet = self.snippet(item.span);
247 let brace_pos = snippet.find_uncommented("{").unwrap();
250 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
251 // FIXME: this skips comments between the extern keyword and the opening
253 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
254 self.block_indent = self.block_indent.block_indent(self.config);
256 if item.body.is_empty() {
257 self.format_missing_no_indent(item.span.hi() - BytePos(1));
258 self.block_indent = self.block_indent.block_unindent(self.config);
259 let indent_str = self.block_indent.to_string(self.config);
260 self.push_str(&indent_str);
262 for item in &item.body {
263 self.format_body_element(item);
266 self.block_indent = self.block_indent.block_unindent(self.config);
267 self.format_missing_with_indent(item.span.hi() - BytePos(1));
272 self.last_pos = item.span.hi();
275 fn format_body_element(&mut self, element: &BodyElement) {
277 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
281 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
282 let item = Item::from_foreign_mod(fm, span, self.config);
283 self.format_item(&item);
286 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
287 let rewrite = item.rewrite(&self.get_context(), self.shape());
288 self.push_rewrite(item.span(), rewrite);
289 self.last_pos = item.span.hi();
299 ) -> Option<String> {
300 let context = self.get_context();
302 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
304 let (mut result, force_newline_brace) =
305 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
308 if self.config.brace_style() == BraceStyle::AlwaysNextLine || force_newline_brace
309 || last_line_width(&result) + 2 > self.shape().width
311 newline_brace = true;
312 } else if !result.contains('\n') {
313 newline_brace = false;
316 // Prepare for the function body by possibly adding a newline and
318 // FIXME we'll miss anything between the end of the signature and the
319 // start of the body, but we need more spans from the compiler to solve
322 result.push_str(&indent.to_string_with_newline(self.config));
327 self.single_line_fn(&result, block).or_else(|| Some(result))
330 pub fn rewrite_required_fn(
334 sig: &ast::MethodSig,
335 generics: &ast::Generics,
337 ) -> Option<String> {
338 // Drop semicolon or it will be interpreted as comment.
339 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
340 let context = self.get_context();
342 let (mut result, _) = rewrite_fn_base(
346 &FnSig::from_method_sig(sig, generics),
352 // Re-attach semicolon
358 fn single_line_fn(&self, fn_str: &str, block: &ast::Block) -> Option<String> {
359 if fn_str.contains('\n') {
363 let codemap = self.get_context().codemap;
365 if self.config.empty_item_single_line() && is_empty_block(block, codemap)
366 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
368 return Some(format!("{}{{}}", fn_str));
371 if self.config.fn_single_line() && is_simple_block_stmt(block, codemap) {
373 if let Some(stmt) = block.stmts.first() {
374 match stmt_expr(stmt) {
376 let suffix = if semicolon_for_expr(&self.get_context(), e) {
382 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
384 .or_else(|| Some(self.snippet(e.span).to_owned()))
386 None => stmt.rewrite(&self.get_context(), self.shape()),
393 if let Some(res) = rewrite {
394 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
395 if !res.contains('\n') && width <= self.config.max_width() {
396 return Some(format!("{}{{ {} }}", fn_str, res));
404 pub fn visit_static(&mut self, static_parts: &StaticParts) {
405 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
406 self.push_rewrite(static_parts.span, rewrite);
409 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
410 let is_tuple = struct_parts.def.is_tuple();
411 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
412 .map(|s| if is_tuple { s + ";" } else { s });
413 self.push_rewrite(struct_parts.span, rewrite);
419 vis: &ast::Visibility,
420 enum_def: &ast::EnumDef,
421 generics: &ast::Generics,
424 let enum_header = format_header("enum ", ident, vis);
425 self.push_str(&enum_header);
427 let enum_snippet = self.snippet(span);
428 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
429 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
430 let generics_str = format_generics(
433 self.config.brace_style(),
434 if enum_def.variants.is_empty() {
435 BracePos::ForceSameLine
440 mk_sp(span.lo(), body_start),
441 last_line_width(&enum_header),
443 self.push_str(&generics_str);
445 self.last_pos = body_start;
447 self.block_indent = self.block_indent.block_indent(self.config);
448 let variant_list = self.format_variant_list(enum_def, body_start, span.hi() - BytePos(1));
450 Some(ref body_str) => self.push_str(body_str),
451 None => self.format_missing_no_indent(span.hi() - BytePos(1)),
453 self.block_indent = self.block_indent.block_unindent(self.config);
455 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
456 let indent_str = self.block_indent.to_string(self.config);
457 self.push_str(&indent_str);
460 self.last_pos = span.hi();
463 // Format the body of an enum definition
464 fn format_variant_list(
466 enum_def: &ast::EnumDef,
469 ) -> Option<String> {
470 if enum_def.variants.is_empty() {
473 let mut result = String::with_capacity(1024);
474 let indentation = self.block_indent.to_string_with_newline(self.config);
475 result.push_str(&indentation);
477 let itemize_list_with = |one_line_width: usize| {
479 self.snippet_provider,
480 enum_def.variants.iter(),
484 if !f.node.attrs.is_empty() {
485 f.node.attrs[0].span.lo()
491 |f| self.format_variant(f, one_line_width),
497 let mut items: Vec<_> =
498 itemize_list_with(self.config.width_heuristics().struct_variant_width);
499 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
500 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
501 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
502 if has_multiline_variant && has_single_line_variant {
503 items = itemize_list_with(0);
506 let shape = self.shape().sub_width(2)?;
507 let fmt = ListFormatting {
508 tactic: DefinitiveListTactic::Vertical,
510 trailing_separator: self.config.trailing_comma(),
511 separator_place: SeparatorPlace::Back,
513 ends_with_newline: true,
514 preserve_newline: true,
518 let list = write_list(&items, &fmt)?;
519 result.push_str(&list);
524 // Variant of an enum.
525 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
526 if contains_skip(&field.node.attrs) {
527 let lo = field.node.attrs[0].span.lo();
528 let span = mk_sp(lo, field.span.hi());
529 return Some(self.snippet(span).to_owned());
532 let context = self.get_context();
534 let shape = self.shape().sub_width(1)?;
535 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
540 .map_or(field.span.lo(), |attr| attr.span.hi());
541 let span = mk_sp(lo, field.span.lo());
543 let variant_body = match field.node.data {
544 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
546 &StructParts::from_variant(field),
548 Some(one_line_width),
550 ast::VariantData::Unit(..) => {
551 if let Some(ref expr) = field.node.disr_expr {
552 let lhs = format!("{} =", field.node.name);
553 rewrite_assign_rhs(&context, lhs, &**expr, shape)?
555 field.node.name.to_string()
560 combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
565 context: &RewriteContext,
568 where_span_end: Option<BytePos>,
569 ) -> Option<String> {
570 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
571 let mut result = String::with_capacity(128);
572 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
573 let sep = offset.to_string_with_newline(context.config);
574 result.push_str(&ref_and_type);
576 let where_budget = if result.contains('\n') {
577 context.config.max_width()
579 context.budget(last_line_width(&result))
581 let option = WhereClauseOption::snuggled(&ref_and_type);
582 let where_clause_str = rewrite_where_clause(
584 &generics.where_clause,
585 context.config.brace_style(),
586 Shape::legacy(where_budget, offset.block_only()),
595 // If there is no where clause, we may have missing comments between the trait name and
596 // the opening brace.
597 if generics.where_clause.predicates.is_empty() {
598 if let Some(hi) = where_span_end {
599 match recover_missing_comment_in_span(
600 mk_sp(self_ty.span.hi(), hi),
601 Shape::indented(offset, context.config),
603 last_line_width(&result),
605 Some(ref missing_comment) if !missing_comment.is_empty() => {
606 result.push_str(missing_comment);
613 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
614 result.push_str(&where_clause_str);
615 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
616 result.push_str(&format!("{}{{{}}}", &sep, &sep));
618 result.push_str(" {}");
623 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
624 let width = offset.block_indent + context.config.tab_spaces() - 1;
625 let where_indent = Indent::new(0, width);
626 result.push_str(&where_indent.to_string_with_newline(context.config));
628 result.push_str(&where_clause_str);
630 let need_newline = !last_line_extendable(&result)
631 && (last_line_contains_single_line_comment(&result) || result.contains('\n'));
632 match context.config.brace_style() {
633 _ if need_newline => result.push_str(&sep),
634 BraceStyle::AlwaysNextLine => result.push_str(&sep),
635 BraceStyle::PreferSameLine => result.push(' '),
636 BraceStyle::SameLineWhere => {
637 if !where_clause_str.is_empty() {
638 result.push_str(&sep);
647 let snippet = context.snippet(item.span);
648 let open_pos = snippet.find_uncommented("{")? + 1;
650 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
651 let mut visitor = FmtVisitor::from_context(context);
652 visitor.block_indent = offset.block_only().block_indent(context.config);
653 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
655 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
657 visitor.visit_impl_item(item);
660 visitor.format_missing(item.span.hi() - BytePos(1));
662 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
663 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
665 result.push_str(&inner_indent_str);
666 result.push_str(visitor.buffer.to_string().trim());
667 result.push_str(&outer_indent_str);
670 if result.ends_with('{') {
671 result.push_str(&sep);
681 fn is_impl_single_line(
682 context: &RewriteContext,
685 where_clause_str: &str,
688 let snippet = context.snippet(item.span);
689 let open_pos = snippet.find_uncommented("{")? + 1;
692 context.config.empty_item_single_line() && items.is_empty() && !result.contains('\n')
693 && result.len() + where_clause_str.len() <= context.config.max_width()
694 && !contains_comment(&snippet[open_pos..]),
698 fn format_impl_ref_and_type(
699 context: &RewriteContext,
702 ) -> Option<String> {
703 if let ast::ItemKind::Impl(
713 let mut result = String::with_capacity(128);
715 result.push_str(&format_visibility(&item.vis));
716 result.push_str(format_defaultness(defaultness));
717 result.push_str(format_unsafety(unsafety));
718 result.push_str("impl");
720 let lo = context.snippet_provider.span_after(item.span, "impl");
721 let hi = match *trait_ref {
722 Some(ref tr) => tr.path.span.lo(),
723 None => self_ty.span.lo(),
725 let shape = generics_shape_from_config(
727 Shape::indented(offset + last_line_width(&result), context.config),
730 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
732 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
734 let polarity_str = if polarity == ast::ImplPolarity::Negative {
740 if let Some(ref trait_ref) = *trait_ref {
741 let result_len = result.len();
742 if let Some(trait_ref_str) = rewrite_trait_ref(
751 result.push_str(&trait_ref_str);
754 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
755 result.push_str(&rewrite_trait_ref(
766 result.push_str(&generics_str);
769 // Try to put the self type in a single line.
771 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
772 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
773 // If there is no where clause adapt budget for type formatting to take space and curly
774 // brace into account.
775 match context.config.brace_style() {
776 BraceStyle::AlwaysNextLine => 0,
782 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
783 // 1 = space before the type.
784 let budget = context.budget(used_space + 1);
785 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
786 if !self_ty_str.contains('\n') {
787 if trait_ref.is_some() {
788 result.push_str(" for ");
792 result.push_str(&self_ty_str);
797 // Couldn't fit the self type on a single line, put it on a new line.
799 // Add indentation of one additional tab.
800 let new_line_offset = offset.block_indent(context.config);
801 result.push_str(&new_line_offset.to_string(context.config));
802 if trait_ref.is_some() {
803 result.push_str("for ");
805 let budget = context.budget(last_line_width(&result));
806 let type_offset = match context.config.indent_style() {
807 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
808 IndentStyle::Block => new_line_offset,
810 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
817 fn rewrite_trait_ref(
818 context: &RewriteContext,
819 trait_ref: &ast::TraitRef,
825 ) -> Option<String> {
826 // 1 = space between generics and trait_ref
827 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
828 let shape = Shape::indented(offset + used_space, context.config);
829 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
830 if !(retry && trait_ref_str.contains('\n')) {
833 generics_str, polarity_str, &trait_ref_str
837 // We could not make enough space for trait_ref, so put it on new line.
839 let offset = offset.block_indent(context.config);
840 let shape = Shape::indented(offset, context.config);
841 let trait_ref_str = trait_ref.rewrite(context, shape)?;
845 &offset.to_string(context.config),
854 pub struct StructParts<'a> {
857 vis: &'a ast::Visibility,
858 def: &'a ast::VariantData,
859 generics: Option<&'a ast::Generics>,
863 impl<'a> StructParts<'a> {
864 fn format_header(&self) -> String {
865 format_header(self.prefix, self.ident, self.vis)
868 fn from_variant(variant: &'a ast::Variant) -> Self {
871 ident: variant.node.name,
872 vis: &ast::Visibility::Inherited,
873 def: &variant.node.data,
879 pub fn from_item(item: &'a ast::Item) -> Self {
880 let (prefix, def, generics) = match item.node {
881 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
882 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
890 generics: Some(generics),
897 context: &RewriteContext,
898 struct_parts: &StructParts,
900 one_line_width: Option<usize>,
901 ) -> Option<String> {
902 match *struct_parts.def {
903 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
904 ast::VariantData::Tuple(ref fields, _) => {
905 format_tuple_struct(context, struct_parts, fields, offset)
907 ast::VariantData::Struct(ref fields, _) => {
908 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
913 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
914 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
917 let mut result = String::with_capacity(128);
918 let header = format!(
920 format_visibility(&item.vis),
921 format_unsafety(unsafety),
925 result.push_str(&header);
927 let body_lo = context.snippet_provider.span_after(item.span, "{");
929 let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
931 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
932 result.push_str(&generics_str);
934 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
935 if !type_param_bounds.is_empty() {
936 let ident_hi = context
938 .span_after(item.span, &format!("{}", item.ident));
939 let bound_hi = type_param_bounds.last().unwrap().span().hi();
940 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
941 if contains_comment(snippet) {
945 let trait_bound_str = rewrite_trait_bounds(
948 Shape::indented(offset, context.config),
950 // If the trait, generics, and trait bound cannot fit on the same line,
951 // put the trait bounds on an indented new line
952 if offset.width() + last_line_width(&result) + trait_bound_str.len()
953 > context.config.comment_width()
955 let trait_indent = offset.block_only().block_indent(context.config);
956 result.push_str(&trait_indent.to_string_with_newline(context.config));
958 result.push_str(&trait_bound_str);
961 if context.config.indent_style() == IndentStyle::Block && result.is_empty() {
967 let where_budget = context.budget(last_line_width(&result));
968 let pos_before_where = if type_param_bounds.is_empty() {
969 generics.where_clause.span.lo()
971 type_param_bounds[type_param_bounds.len() - 1].span().hi()
973 let option = WhereClauseOption::snuggled(&generics_str);
974 let where_clause_str = rewrite_where_clause(
976 &generics.where_clause,
977 context.config.brace_style(),
978 Shape::legacy(where_budget, offset.block_only()),
986 // If the where clause cannot fit on the same line,
987 // put the where clause on a new line
988 if !where_clause_str.contains('\n')
989 && last_line_width(&result) + where_clause_str.len() + offset.width()
990 > context.config.comment_width()
992 let width = offset.block_indent + context.config.tab_spaces() - 1;
993 let where_indent = Indent::new(0, width);
994 result.push_str(&where_indent.to_string_with_newline(context.config));
996 result.push_str(&where_clause_str);
998 if generics.where_clause.predicates.is_empty() {
999 let item_snippet = context.snippet(item.span);
1000 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1002 let comment_hi = body_lo - BytePos(1);
1003 let comment_lo = item.span.lo() + BytePos(lo as u32);
1004 if comment_lo < comment_hi {
1005 match recover_missing_comment_in_span(
1006 mk_sp(comment_lo, comment_hi),
1007 Shape::indented(offset, context.config),
1009 last_line_width(&result),
1011 Some(ref missing_comment) if !missing_comment.is_empty() => {
1012 result.push_str(missing_comment);
1020 match context.config.brace_style() {
1021 _ if last_line_contains_single_line_comment(&result) => {
1022 result.push_str(&offset.to_string_with_newline(context.config));
1024 BraceStyle::AlwaysNextLine => {
1025 result.push_str(&offset.to_string_with_newline(context.config));
1027 BraceStyle::PreferSameLine => result.push(' '),
1028 BraceStyle::SameLineWhere => {
1029 if !where_clause_str.is_empty()
1030 && (!trait_items.is_empty() || result.contains('\n'))
1032 result.push_str(&offset.to_string_with_newline(context.config));
1040 let snippet = context.snippet(item.span);
1041 let open_pos = snippet.find_uncommented("{")? + 1;
1043 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1044 let mut visitor = FmtVisitor::from_context(context);
1045 visitor.block_indent = offset.block_only().block_indent(context.config);
1046 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1048 for item in trait_items {
1049 visitor.visit_trait_item(item);
1052 visitor.format_missing(item.span.hi() - BytePos(1));
1054 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
1055 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
1057 result.push_str(&inner_indent_str);
1058 result.push_str(visitor.buffer.to_string().trim());
1059 result.push_str(&outer_indent_str);
1060 } else if result.contains('\n') {
1071 pub fn format_trait_alias(
1072 context: &RewriteContext,
1074 generics: &ast::Generics,
1075 ty_param_bounds: &ast::TyParamBounds,
1077 ) -> Option<String> {
1078 let alias = ident.name.as_str();
1079 // 6 = "trait ", 2 = " ="
1080 let g_shape = shape.offset_left(6 + alias.len())?.sub_width(2)?;
1081 let generics_str = rewrite_generics(context, generics, g_shape, generics.span)?;
1082 let lhs = format!("trait {}{} =", alias, generics_str);
1084 rewrite_assign_rhs(context, lhs, ty_param_bounds, shape.sub_width(1)?).map(|s| s + ";")
1087 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1088 let header_str = format_header(p.prefix, p.ident, p.vis);
1089 let generics_str = if let Some(generics) = p.generics {
1090 let hi = if generics.where_clause.predicates.is_empty() {
1093 generics.where_clause.span.hi()
1098 context.config.brace_style(),
1101 mk_sp(generics.span.lo(), hi),
1102 last_line_width(&header_str),
1107 Some(format!("{}{};", header_str, generics_str))
1110 pub fn format_struct_struct(
1111 context: &RewriteContext,
1112 struct_parts: &StructParts,
1113 fields: &[ast::StructField],
1115 one_line_width: Option<usize>,
1116 ) -> Option<String> {
1117 let mut result = String::with_capacity(1024);
1118 let span = struct_parts.span;
1120 let header_str = struct_parts.format_header();
1121 result.push_str(&header_str);
1123 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1124 let body_lo = context.snippet_provider.span_after(span, "{");
1126 let generics_str = match struct_parts.generics {
1127 Some(g) => format_generics(
1130 context.config.brace_style(),
1131 if fields.is_empty() {
1132 BracePos::ForceSameLine
1137 mk_sp(header_hi, body_lo),
1138 last_line_width(&result),
1141 // 3 = ` {}`, 2 = ` {`.
1142 let overhead = if fields.is_empty() { 3 } else { 2 };
1143 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1144 || context.config.max_width() < overhead + result.len()
1146 format!("\n{}{{", offset.block_only().to_string(context.config))
1153 let overhead = if fields.is_empty() { 1 } else { 0 };
1154 let total_width = result.len() + generics_str.len() + overhead;
1155 if !generics_str.is_empty() && !generics_str.contains('\n')
1156 && total_width > context.config.max_width()
1159 result.push_str(&offset.to_string(context.config));
1160 result.push_str(generics_str.trim_left());
1162 result.push_str(&generics_str);
1165 if fields.is_empty() {
1166 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1167 if snippet.trim().is_empty() {
1169 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1171 result.push_str(snippet.trim_right());
1173 result.push_str(&offset.to_string(context.config));
1175 result.push_str(snippet);
1178 return Some(result);
1182 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1183 let one_line_budget =
1184 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1186 let items_str = rewrite_with_alignment(
1189 Shape::indented(offset, context.config).sub_width(1)?,
1190 mk_sp(body_lo, span.hi()),
1194 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget
1195 && !last_line_contains_single_line_comment(&items_str)
1197 Some(format!("{} {} }}", result, items_str))
1203 .block_indent(context.config)
1204 .to_string(context.config),
1206 offset.to_string(context.config)
1211 /// Returns a bytepos that is after that of `(` in `pub(..)`. If the given visibility does not
1212 /// contain `pub(..)`, then return the `lo` of the `defualt_span`. Yeah, but for what? Well, we need
1213 /// to bypass the `(` in the visibility when creating a span of tuple's body or fn's args.
1214 fn get_bytepos_after_visibility(
1215 context: &RewriteContext,
1216 vis: &ast::Visibility,
1221 ast::Visibility::Crate(s, CrateSugar::PubCrate) => context
1223 .span_after(mk_sp(s.hi(), default_span.hi()), terminator),
1224 ast::Visibility::Crate(s, CrateSugar::JustCrate) => s.hi(),
1225 ast::Visibility::Restricted { ref path, .. } => path.span.hi(),
1226 _ => default_span.lo(),
1230 fn format_tuple_struct(
1231 context: &RewriteContext,
1232 struct_parts: &StructParts,
1233 fields: &[ast::StructField],
1235 ) -> Option<String> {
1236 let mut result = String::with_capacity(1024);
1237 let span = struct_parts.span;
1239 let header_str = struct_parts.format_header();
1240 result.push_str(&header_str);
1242 let body_lo = if fields.is_empty() {
1243 let lo = get_bytepos_after_visibility(context, struct_parts.vis, span, ")");
1246 .span_after(mk_sp(lo, span.hi()), "(")
1250 let body_hi = if fields.is_empty() {
1253 .span_after(mk_sp(body_lo, span.hi()), ")")
1255 // This is a dirty hack to work around a missing `)` from the span of the last field.
1256 let last_arg_span = fields[fields.len() - 1].span;
1257 if context.snippet(last_arg_span).ends_with(')') {
1262 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1266 let where_clause_str = match struct_parts.generics {
1268 let budget = context.budget(last_line_width(&header_str));
1269 let shape = Shape::legacy(budget, offset);
1270 let g_span = mk_sp(span.lo(), body_lo);
1271 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1272 result.push_str(&generics_str);
1274 let where_budget = context.budget(last_line_width(&result));
1275 let option = WhereClauseOption::new(true, false);
1276 rewrite_where_clause(
1278 &generics.where_clause,
1279 context.config.brace_style(),
1280 Shape::legacy(where_budget, offset.block_only()),
1281 Density::Compressed,
1289 None => "".to_owned(),
1292 if fields.is_empty() {
1294 let used_width = last_line_used_width(&result, offset.width()) + 3;
1295 if used_width > context.config.max_width() {
1297 result.push_str(&offset
1298 .block_indent(context.config)
1299 .to_string(context.config))
1302 let snippet = context.snippet(mk_sp(
1306 .span_before(mk_sp(body_lo, span.hi()), ")"),
1308 if snippet.is_empty() {
1310 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1311 result.push_str(snippet.trim_right());
1313 result.push_str(&offset.to_string(context.config));
1315 result.push_str(snippet);
1319 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1320 let fields = &fields.iter().collect::<Vec<_>>()[..];
1321 let one_line_width = context.config.width_heuristics().fn_call_width;
1322 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1325 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1326 && (result.contains('\n')
1327 || offset.block_indent + result.len() + where_clause_str.len() + 1
1328 > context.config.max_width())
1330 // We need to put the where clause on a new line, but we didn't
1331 // know that earlier, so the where clause will not be indented properly.
1334 .push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1335 .to_string(context.config));
1337 result.push_str(&where_clause_str);
1342 pub fn rewrite_type_alias(
1343 context: &RewriteContext,
1347 generics: &ast::Generics,
1348 vis: &ast::Visibility,
1350 ) -> Option<String> {
1351 let mut result = String::with_capacity(128);
1353 result.push_str(&format_visibility(vis));
1354 result.push_str("type ");
1355 result.push_str(&ident.to_string());
1358 let g_shape = Shape::indented(indent, context.config)
1359 .offset_left(result.len())?
1362 context.snippet_provider.span_after(span, "type"),
1365 let generics_str = rewrite_generics(context, generics, g_shape, g_span)?;
1366 result.push_str(&generics_str);
1368 let where_budget = context.budget(last_line_width(&result));
1369 let option = WhereClauseOption::snuggled(&result);
1370 let where_clause_str = rewrite_where_clause(
1372 &generics.where_clause,
1373 context.config.brace_style(),
1374 Shape::legacy(where_budget, indent),
1382 result.push_str(&where_clause_str);
1383 if where_clause_str.is_empty() {
1384 result.push_str(" =");
1386 result.push_str(&format!(
1388 indent.to_string_with_newline(context.config)
1393 let ty_shape = Shape::indented(indent, context.config).sub_width(1)?;
1394 rewrite_assign_rhs(context, result, ty, ty_shape).map(|s| s + ";")
1397 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1399 if config.space_before_colon() { " " } else { "" },
1400 if config.space_after_colon() { " " } else { "" },
1404 pub fn rewrite_struct_field_prefix(
1405 context: &RewriteContext,
1406 field: &ast::StructField,
1407 ) -> Option<String> {
1408 let vis = format_visibility(&field.vis);
1409 let type_annotation_spacing = type_annotation_spacing(context.config);
1410 Some(match field.ident {
1411 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1412 None => format!("{}", vis),
1416 impl Rewrite for ast::StructField {
1417 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1418 rewrite_struct_field(context, self, shape, 0)
1422 pub fn rewrite_struct_field(
1423 context: &RewriteContext,
1424 field: &ast::StructField,
1426 lhs_max_width: usize,
1427 ) -> Option<String> {
1428 if contains_skip(&field.attrs) {
1429 return Some(context.snippet(field.span()).to_owned());
1432 let type_annotation_spacing = type_annotation_spacing(context.config);
1433 let prefix = rewrite_struct_field_prefix(context, field)?;
1435 let attrs_str = field.attrs.rewrite(context, shape)?;
1436 let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
1437 let missing_span = if field.attrs.is_empty() {
1438 mk_sp(field.span.lo(), field.span.lo())
1440 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1442 let mut spacing = String::from(if field.ident.is_some() {
1443 type_annotation_spacing.1
1447 // Try to put everything on a single line.
1448 let attr_prefix = combine_strs_with_missing_comments(
1456 let overhead = last_line_width(&attr_prefix);
1457 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1458 for _ in 0..lhs_offset {
1461 // In this extreme case we will be missing a space betweeen an attribute and a field.
1462 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1466 .offset_left(overhead + spacing.len())
1467 .and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
1468 if let Some(ref ty) = orig_ty {
1469 if !ty.contains('\n') {
1470 return Some(attr_prefix + &spacing + ty);
1474 let is_prefix_empty = prefix.is_empty();
1475 // We must use multiline. We are going to put attributes and a field on different lines.
1476 let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, shape)?;
1477 // Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
1478 let field_str = if is_prefix_empty {
1479 field_str.trim_left()
1483 combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
1486 pub struct StaticParts<'a> {
1488 vis: &'a ast::Visibility,
1491 mutability: ast::Mutability,
1492 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1493 defaultness: Option<ast::Defaultness>,
1497 impl<'a> StaticParts<'a> {
1498 pub fn from_item(item: &'a ast::Item) -> Self {
1499 let (prefix, ty, mutability, expr) = match item.node {
1500 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1501 ast::ItemKind::Const(ref ty, ref expr) => {
1502 ("const", ty, ast::Mutability::Immutable, expr)
1504 _ => unreachable!(),
1512 expr_opt: Some(expr),
1518 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1519 let (ty, expr_opt) = match ti.node {
1520 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1521 _ => unreachable!(),
1525 vis: &ast::Visibility::Inherited,
1528 mutability: ast::Mutability::Immutable,
1529 expr_opt: expr_opt.as_ref(),
1535 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1536 let (ty, expr) = match ii.node {
1537 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1538 _ => unreachable!(),
1545 mutability: ast::Mutability::Immutable,
1546 expr_opt: Some(expr),
1547 defaultness: Some(ii.defaultness),
1554 context: &RewriteContext,
1555 static_parts: &StaticParts,
1557 ) -> Option<String> {
1558 let colon = colon_spaces(
1559 context.config.space_before_colon(),
1560 context.config.space_after_colon(),
1562 let mut prefix = format!(
1564 format_visibility(static_parts.vis),
1565 static_parts.defaultness.map_or("", format_defaultness),
1566 static_parts.prefix,
1567 format_mutability(static_parts.mutability),
1573 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1574 let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
1575 Some(ty_str) => ty_str,
1577 if prefix.ends_with(' ') {
1580 let nested_indent = offset.block_indent(context.config);
1581 let nested_shape = Shape::indented(nested_indent, context.config);
1582 let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
1585 nested_indent.to_string_with_newline(context.config),
1591 if let Some(expr) = static_parts.expr_opt {
1592 let lhs = format!("{}{} =", prefix, ty_str);
1594 let remaining_width = context.budget(offset.block_indent + 1);
1599 Shape::legacy(remaining_width, offset.block_only()),
1600 ).and_then(|res| recover_comment_removed(res, static_parts.span, context))
1601 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1603 Some(format!("{}{};", prefix, ty_str))
1607 pub fn rewrite_associated_type(
1609 ty_opt: Option<&ptr::P<ast::Ty>>,
1610 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1611 context: &RewriteContext,
1613 ) -> Option<String> {
1614 let prefix = format!("type {}", ident);
1616 let type_bounds_str = if let Some(bounds) = ty_param_bounds_opt {
1618 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1619 let bound_str = bounds
1621 .map(|ty_bound| ty_bound.rewrite(context, shape))
1622 .collect::<Option<Vec<_>>>()?;
1623 if !bounds.is_empty() {
1624 format!(": {}", join_bounds(context, shape, &bound_str))
1632 if let Some(ty) = ty_opt {
1634 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1635 let lhs = format!("{}{} =", prefix, type_bounds_str);
1636 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1638 Some(format!("{}{};", prefix, type_bounds_str))
1642 pub fn rewrite_associated_impl_type(
1644 defaultness: ast::Defaultness,
1645 ty_opt: Option<&ptr::P<ast::Ty>>,
1646 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1647 context: &RewriteContext,
1649 ) -> Option<String> {
1650 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1653 ast::Defaultness::Default => Some(format!("default {}", result)),
1658 impl Rewrite for ast::FunctionRetTy {
1659 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1661 ast::FunctionRetTy::Default(_) => Some(String::new()),
1662 ast::FunctionRetTy::Ty(ref ty) => {
1663 let inner_width = shape.width.checked_sub(3)?;
1664 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1665 .map(|r| format!("-> {}", r))
1671 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1673 ast::TyKind::Infer => {
1674 let original = context.snippet(ty.span);
1681 impl Rewrite for ast::Arg {
1682 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1683 if is_named_arg(self) {
1684 let mut result = self.pat
1685 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1687 if !is_empty_infer(context, &*self.ty) {
1688 if context.config.space_before_colon() {
1689 result.push_str(" ");
1691 result.push_str(":");
1692 if context.config.space_after_colon() {
1693 result.push_str(" ");
1695 let overhead = last_line_width(&result);
1696 let max_width = shape.width.checked_sub(overhead)?;
1697 let ty_str = self.ty
1698 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1699 result.push_str(&ty_str);
1704 self.ty.rewrite(context, shape)
1709 fn rewrite_explicit_self(
1710 explicit_self: &ast::ExplicitSelf,
1712 context: &RewriteContext,
1713 ) -> Option<String> {
1714 match explicit_self.node {
1715 ast::SelfKind::Region(lt, m) => {
1716 let mut_str = format_mutability(m);
1719 let lifetime_str = l.rewrite(
1721 Shape::legacy(context.config.max_width(), Indent::empty()),
1723 Some(format!("&{} {}self", lifetime_str, mut_str))
1725 None => Some(format!("&{}self", mut_str)),
1728 ast::SelfKind::Explicit(ref ty, _) => {
1729 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1731 let mutability = explicit_self_mutability(&args[0]);
1732 let type_str = ty.rewrite(
1734 Shape::legacy(context.config.max_width(), Indent::empty()),
1739 format_mutability(mutability),
1743 ast::SelfKind::Value(_) => {
1744 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1746 let mutability = explicit_self_mutability(&args[0]);
1748 Some(format!("{}self", format_mutability(mutability)))
1753 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1754 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1755 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1756 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1763 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1764 if is_named_arg(arg) {
1771 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1773 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1774 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1775 _ => arg.ty.span.hi(),
1779 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1780 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1781 ident.node != symbol::keywords::Invalid.ident()
1787 // Return type is (result, force_new_line_for_brace)
1789 context: &RewriteContext,
1794 newline_brace: bool,
1796 ) -> Option<(String, bool)> {
1797 let mut force_new_line_for_brace = false;
1799 let where_clause = &fn_sig.generics.where_clause;
1801 let mut result = String::with_capacity(1024);
1802 result.push_str(&fn_sig.to_str(context));
1805 result.push_str("fn ");
1806 result.push_str(&ident.to_string());
1809 let overhead = if has_body && !newline_brace {
1816 let used_width = last_line_used_width(&result, indent.width());
1817 let one_line_budget = context.budget(used_width + overhead);
1819 width: one_line_budget,
1823 let fd = fn_sig.decl;
1824 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1825 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1826 result.push_str(&generics_str);
1828 let snuggle_angle_bracket = generics_str
1831 .map_or(false, |l| l.trim_left().len() == 1);
1833 // Note that the width and indent don't really matter, we'll re-layout the
1834 // return type later anyway.
1835 let ret_str = fd.output
1836 .rewrite(context, Shape::indented(indent, context.config))?;
1838 let multi_line_ret_str = ret_str.contains('\n');
1839 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1842 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1853 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1854 one_line_budget, multi_line_budget, arg_indent
1857 // Check if vertical layout was forced.
1858 if one_line_budget == 0 {
1859 if snuggle_angle_bracket {
1862 result.push_str("(");
1863 if context.config.indent_style() == IndentStyle::Visual {
1864 result.push_str(&arg_indent.to_string_with_newline(context.config));
1870 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1871 && result.ends_with('(')
1876 // Skip `pub(crate)`.
1877 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1878 // A conservative estimation, to goal is to be over all parens in generics
1879 let args_start = fn_sig
1884 .map_or(lo_after_visibility, |param| param.span().hi());
1885 let args_end = if fd.inputs.is_empty() {
1888 .span_after(mk_sp(args_start, span.hi()), ")")
1890 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1891 context.snippet_provider.span_after(last_span, ")")
1893 let args_span = mk_sp(
1896 .span_after(mk_sp(args_start, span.hi()), "("),
1899 let arg_str = rewrite_args(
1902 fd.get_self().as_ref(),
1909 generics_str.contains('\n'),
1912 let put_args_in_block = match context.config.indent_style() {
1913 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1915 } && !fd.inputs.is_empty();
1917 let mut args_last_line_contains_comment = false;
1918 if put_args_in_block {
1919 arg_indent = indent.block_indent(context.config);
1920 result.push_str(&arg_indent.to_string_with_newline(context.config));
1921 result.push_str(&arg_str);
1922 result.push_str(&indent.to_string_with_newline(context.config));
1925 result.push_str(&arg_str);
1926 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1927 // Put the closing brace on the next line if it overflows the max width.
1929 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1932 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1935 // If the last line of args contains comment, we cannot put the closing paren
1936 // on the same line.
1940 .map_or(false, |last_line| last_line.contains("//"))
1942 args_last_line_contains_comment = true;
1943 result.push_str(&arg_indent.to_string_with_newline(context.config));
1949 if let ast::FunctionRetTy::Ty(..) = fd.output {
1950 let ret_should_indent = match context.config.indent_style() {
1951 // If our args are block layout then we surely must have space.
1952 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1953 _ if args_last_line_contains_comment => false,
1954 _ if result.contains('\n') || multi_line_ret_str => true,
1956 // If the return type would push over the max width, then put the return type on
1957 // a new line. With the +1 for the signature length an additional space between
1958 // the closing parenthesis of the argument and the arrow '->' is considered.
1959 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1961 // If there is no where clause, take into account the space after the return type
1963 if where_clause.predicates.is_empty() {
1967 sig_length > context.config.max_width()
1970 let ret_indent = if ret_should_indent {
1971 let indent = if arg_str.is_empty() {
1972 // Aligning with non-existent args looks silly.
1973 force_new_line_for_brace = true;
1976 // FIXME: we might want to check that using the arg indent
1977 // doesn't blow our budget, and if it does, then fallback to
1978 // the where clause indent.
1982 result.push_str(&indent.to_string_with_newline(context.config));
1986 Indent::new(indent.block_indent, last_line_width(&result))
1989 if multi_line_ret_str || ret_should_indent {
1990 // Now that we know the proper indent and width, we need to
1991 // re-layout the return type.
1992 let ret_str = fd.output
1993 .rewrite(context, Shape::indented(ret_indent, context.config))?;
1994 result.push_str(&ret_str);
1996 result.push_str(&ret_str);
1999 // Comment between return type and the end of the decl.
2000 let snippet_lo = fd.output.span().hi();
2001 if where_clause.predicates.is_empty() {
2002 let snippet_hi = span.hi();
2003 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2004 // Try to preserve the layout of the original snippet.
2005 let original_starts_with_newline = snippet
2007 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2008 let original_ends_with_newline = snippet
2009 .rfind(|c| c != ' ')
2010 .map_or(false, |i| snippet[i..].ends_with('\n'));
2011 let snippet = snippet.trim();
2012 if !snippet.is_empty() {
2013 result.push(if original_starts_with_newline {
2018 result.push_str(snippet);
2019 if original_ends_with_newline {
2020 force_new_line_for_brace = true;
2026 let pos_before_where = match fd.output {
2027 ast::FunctionRetTy::Default(..) => args_span.hi(),
2028 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2031 let is_args_multi_lined = arg_str.contains('\n');
2033 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2034 let where_clause_str = rewrite_where_clause(
2037 context.config.brace_style(),
2038 Shape::indented(indent, context.config),
2044 is_args_multi_lined,
2046 // If there are neither where clause nor return type, we may be missing comments between
2048 if where_clause_str.is_empty() {
2049 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2050 match recover_missing_comment_in_span(
2051 mk_sp(args_span.hi(), ret_span.hi()),
2054 last_line_width(&result),
2056 Some(ref missing_comment) if !missing_comment.is_empty() => {
2057 result.push_str(missing_comment);
2058 force_new_line_for_brace = true;
2065 result.push_str(&where_clause_str);
2067 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2068 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2069 Some((result, force_new_line_for_brace))
2072 #[derive(Copy, Clone)]
2073 struct WhereClauseOption {
2074 suppress_comma: bool, // Force no trailing comma
2075 snuggle: bool, // Do not insert newline before `where`
2076 compress_where: bool, // Try single line where clause instead of vertical layout
2079 impl WhereClauseOption {
2080 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2084 compress_where: false,
2088 pub fn snuggled(current: &str) -> WhereClauseOption {
2090 suppress_comma: false,
2091 snuggle: trimmed_last_line_width(current) == 1,
2092 compress_where: false,
2098 context: &RewriteContext,
2100 explicit_self: Option<&ast::ExplicitSelf>,
2101 one_line_budget: usize,
2102 multi_line_budget: usize,
2107 generics_str_contains_newline: bool,
2108 ) -> Option<String> {
2109 let mut arg_item_strs = args.iter()
2110 .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
2111 .collect::<Option<Vec<_>>>()?;
2113 // Account for sugary self.
2114 // FIXME: the comment for the self argument is dropped. This is blocked
2115 // on rust issue #27522.
2116 let min_args = explicit_self
2117 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2118 .map_or(1, |self_str| {
2119 arg_item_strs[0] = self_str;
2123 // Comments between args.
2124 let mut arg_items = Vec::new();
2126 arg_items.push(ListItem::from_str(""));
2129 // FIXME(#21): if there are no args, there might still be a comment, but
2130 // without spans for the comment or parens, there is no chance of
2131 // getting it right. You also don't get to put a comment on self, unless
2133 if args.len() >= min_args || variadic {
2134 let comment_span_start = if min_args == 2 {
2135 let second_arg_start = if arg_has_pattern(&args[1]) {
2136 args[1].pat.span.lo()
2138 args[1].ty.span.lo()
2140 let reduced_span = mk_sp(span.lo(), second_arg_start);
2142 context.snippet_provider.span_after_last(reduced_span, ",")
2147 enum ArgumentKind<'a> {
2148 Regular(&'a ast::Arg),
2152 let variadic_arg = if variadic {
2153 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2154 let variadic_start =
2155 context.snippet_provider.span_after(variadic_span, "...") - BytePos(3);
2156 Some(ArgumentKind::Variadic(variadic_start))
2161 let more_items = itemize_list(
2162 context.snippet_provider,
2163 args[min_args - 1..]
2165 .map(ArgumentKind::Regular)
2166 .chain(variadic_arg),
2170 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2171 ArgumentKind::Variadic(start) => start,
2174 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2175 ArgumentKind::Variadic(start) => start + BytePos(3),
2178 ArgumentKind::Regular(..) => None,
2179 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2186 arg_items.extend(more_items);
2189 let fits_in_one_line = !generics_str_contains_newline
2190 && (arg_items.is_empty()
2191 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2193 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2194 item.item = Some(arg);
2197 let last_line_ends_with_comment = arg_items
2200 .and_then(|item| item.post_comment.as_ref())
2201 .map_or(false, |s| s.trim().starts_with("//"));
2203 let (indent, trailing_comma) = match context.config.indent_style() {
2204 IndentStyle::Block if fits_in_one_line => {
2205 (indent.block_indent(context.config), SeparatorTactic::Never)
2207 IndentStyle::Block => (
2208 indent.block_indent(context.config),
2209 context.config.trailing_comma(),
2211 IndentStyle::Visual if last_line_ends_with_comment => {
2212 (arg_indent, context.config.trailing_comma())
2214 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2217 let tactic = definitive_tactic(
2219 context.config.fn_args_density().to_list_tactic(),
2223 let budget = match tactic {
2224 DefinitiveListTactic::Horizontal => one_line_budget,
2225 _ => multi_line_budget,
2228 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2230 let fmt = ListFormatting {
2233 trailing_separator: if variadic {
2234 SeparatorTactic::Never
2238 separator_place: SeparatorPlace::Back,
2239 shape: Shape::legacy(budget, indent),
2240 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2241 preserve_newline: true,
2242 config: context.config,
2245 write_list(&arg_items, &fmt)
2248 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2249 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2250 ident.node != symbol::keywords::Invalid.ident()
2256 fn compute_budgets_for_args(
2257 context: &RewriteContext,
2261 newline_brace: bool,
2263 force_vertical_layout: bool,
2264 ) -> Option<((usize, usize, Indent))> {
2266 "compute_budgets_for_args {} {:?}, {}, {}",
2272 // Try keeping everything on the same line.
2273 if !result.contains('\n') && !force_vertical_layout {
2274 // 2 = `()`, 3 = `() `, space is before ret_string.
2275 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2276 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2286 let one_line_budget = context.budget(used_space);
2288 if one_line_budget > 0 {
2290 let (indent, multi_line_budget) = match context.config.indent_style() {
2291 IndentStyle::Block => {
2292 let indent = indent.block_indent(context.config);
2293 (indent, context.budget(indent.width() + 1))
2295 IndentStyle::Visual => {
2296 let indent = indent + result.len() + 1;
2297 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2298 (indent, context.budget(multi_line_overhead))
2302 return Some((one_line_budget, multi_line_budget, indent));
2306 // Didn't work. we must force vertical layout and put args on a newline.
2307 let new_indent = indent.block_indent(context.config);
2308 let used_space = match context.config.indent_style() {
2310 IndentStyle::Block => new_indent.width() + 1,
2311 // Account for `)` and possibly ` {`.
2312 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2314 Some((0, context.budget(used_space), new_indent))
2317 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2318 let predicate_count = where_clause.predicates.len();
2320 if config.where_single_line() && predicate_count == 1 {
2323 let brace_style = config.brace_style();
2325 brace_style == BraceStyle::AlwaysNextLine
2326 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2329 fn rewrite_generics(
2330 context: &RewriteContext,
2331 generics: &ast::Generics,
2334 ) -> Option<String> {
2335 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2336 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2337 rewrite_generics_inner(context, generics, g_shape, one_line_width, span)
2338 .or_else(|| rewrite_generics_inner(context, generics, g_shape, 0, span))
2341 fn rewrite_generics_inner(
2342 context: &RewriteContext,
2343 generics: &ast::Generics,
2345 one_line_width: usize,
2347 ) -> Option<String> {
2348 // FIXME: convert bounds to where clauses where they get too big or if
2349 // there is a where clause at all.
2351 if generics.params.is_empty() {
2352 return Some(String::new());
2355 let items = itemize_list(
2356 context.snippet_provider,
2357 generics.params.iter(),
2360 |arg| arg.span().lo(),
2361 |arg| arg.span().hi(),
2362 |arg| arg.rewrite(context, shape),
2363 context.snippet_provider.span_after(span, "<"),
2367 format_generics_item_list(context, items, shape, one_line_width)
2370 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2371 match config.indent_style() {
2372 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2373 IndentStyle::Block => {
2377 .block_indent(config.tab_spaces())
2378 .with_max_width(config)
2384 pub fn format_generics_item_list<I>(
2385 context: &RewriteContext,
2388 one_line_budget: usize,
2391 I: Iterator<Item = ListItem>,
2393 let item_vec = items.collect::<Vec<_>>();
2395 let tactic = definitive_tactic(
2397 ListTactic::HorizontalVertical,
2401 let fmt = ListFormatting {
2404 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2405 SeparatorTactic::Never
2407 context.config.trailing_comma()
2409 separator_place: SeparatorPlace::Back,
2411 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2412 preserve_newline: true,
2413 config: context.config,
2416 let list_str = write_list(&item_vec, &fmt)?;
2418 Some(wrap_generics_with_angle_brackets(
2425 pub fn wrap_generics_with_angle_brackets(
2426 context: &RewriteContext,
2428 list_offset: Indent,
2430 if context.config.indent_style() == IndentStyle::Block
2431 && (list_str.contains('\n') || list_str.ends_with(','))
2435 list_offset.to_string(context.config),
2438 .block_unindent(context.config)
2439 .to_string(context.config)
2441 } else if context.config.spaces_within_parens_and_brackets() {
2442 format!("< {} >", list_str)
2444 format!("<{}>", list_str)
2448 fn rewrite_trait_bounds(
2449 context: &RewriteContext,
2450 bounds: &[ast::TyParamBound],
2452 ) -> Option<String> {
2453 if bounds.is_empty() {
2454 return Some(String::new());
2456 let bound_str = bounds
2458 .map(|ty_bound| ty_bound.rewrite(context, shape))
2459 .collect::<Option<Vec<_>>>()?;
2460 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2463 fn rewrite_where_clause_rfc_style(
2464 context: &RewriteContext,
2465 where_clause: &ast::WhereClause,
2468 span_end: Option<BytePos>,
2469 span_end_before_where: BytePos,
2470 where_clause_option: WhereClauseOption,
2471 is_args_multi_line: bool,
2472 ) -> Option<String> {
2473 let block_shape = shape.block().with_max_width(context.config);
2475 let (span_before, span_after) =
2476 missing_span_before_after_where(span_end_before_where, where_clause);
2477 let (comment_before, comment_after) =
2478 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2480 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2483 block_shape.indent.to_string_with_newline(context.config)
2486 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2488 let clause_shape = clause_shape.sub_width(1)?;
2489 // each clause on one line, trailing comma (except if suppress_comma)
2490 let span_start = where_clause.predicates[0].span().lo();
2491 // If we don't have the start of the next span, then use the end of the
2492 // predicates, but that means we miss comments.
2493 let len = where_clause.predicates.len();
2494 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2495 let span_end = span_end.unwrap_or(end_of_preds);
2496 let items = itemize_list(
2497 context.snippet_provider,
2498 where_clause.predicates.iter(),
2501 |pred| pred.span().lo(),
2502 |pred| pred.span().hi(),
2503 |pred| pred.rewrite(context, clause_shape),
2508 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2509 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2510 SeparatorTactic::Never
2512 context.config.trailing_comma()
2515 // shape should be vertical only and only if we have `where_single_line` option enabled
2516 // and the number of items of the where clause is equal to 1
2517 let shape_tactic = if where_single_line {
2518 DefinitiveListTactic::Horizontal
2520 DefinitiveListTactic::Vertical
2523 let fmt = ListFormatting {
2524 tactic: shape_tactic,
2526 trailing_separator: comma_tactic,
2527 separator_place: SeparatorPlace::Back,
2528 shape: clause_shape,
2529 ends_with_newline: true,
2530 preserve_newline: true,
2531 config: context.config,
2533 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2535 let comment_separator = |comment: &str, shape: Shape| {
2536 if comment.is_empty() {
2539 shape.indent.to_string_with_newline(context.config)
2542 let newline_before_where = comment_separator(&comment_before, shape);
2543 let newline_after_where = comment_separator(&comment_after, clause_shape);
2546 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2547 && comment_after.is_empty() && !preds_str.contains('\n')
2548 && 6 + preds_str.len() <= shape.width || where_single_line
2552 clause_shape.indent.to_string_with_newline(context.config)
2555 "{}{}{}where{}{}{}{}",
2558 newline_before_where,
2559 newline_after_where,
2566 fn rewrite_where_clause(
2567 context: &RewriteContext,
2568 where_clause: &ast::WhereClause,
2569 brace_style: BraceStyle,
2573 span_end: Option<BytePos>,
2574 span_end_before_where: BytePos,
2575 where_clause_option: WhereClauseOption,
2576 is_args_multi_line: bool,
2577 ) -> Option<String> {
2578 if where_clause.predicates.is_empty() {
2579 return Some(String::new());
2582 if context.config.indent_style() == IndentStyle::Block {
2583 return rewrite_where_clause_rfc_style(
2589 span_end_before_where,
2590 where_clause_option,
2595 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2597 let offset = match context.config.indent_style() {
2598 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2599 // 6 = "where ".len()
2600 IndentStyle::Visual => shape.indent + extra_indent + 6,
2602 // FIXME: if indent_style != Visual, then the budgets below might
2603 // be out by a char or two.
2605 let budget = context.config.max_width() - offset.width();
2606 let span_start = where_clause.predicates[0].span().lo();
2607 // If we don't have the start of the next span, then use the end of the
2608 // predicates, but that means we miss comments.
2609 let len = where_clause.predicates.len();
2610 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2611 let span_end = span_end.unwrap_or(end_of_preds);
2612 let items = itemize_list(
2613 context.snippet_provider,
2614 where_clause.predicates.iter(),
2617 |pred| pred.span().lo(),
2618 |pred| pred.span().hi(),
2619 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2624 let item_vec = items.collect::<Vec<_>>();
2625 // FIXME: we don't need to collect here
2626 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2628 let mut comma_tactic = context.config.trailing_comma();
2629 // Kind of a hack because we don't usually have trailing commas in where clauses.
2630 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2631 comma_tactic = SeparatorTactic::Never;
2634 let fmt = ListFormatting {
2637 trailing_separator: comma_tactic,
2638 separator_place: SeparatorPlace::Back,
2639 shape: Shape::legacy(budget, offset),
2640 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2641 preserve_newline: true,
2642 config: context.config,
2644 let preds_str = write_list(&item_vec, &fmt)?;
2646 let end_length = if terminator == "{" {
2647 // If the brace is on the next line we don't need to count it otherwise it needs two
2650 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2651 BraceStyle::PreferSameLine => 2,
2653 } else if terminator == "=" {
2658 if density == Density::Tall || preds_str.contains('\n')
2659 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2663 (shape.indent + extra_indent).to_string(context.config),
2667 Some(format!(" where {}", preds_str))
2671 fn missing_span_before_after_where(
2672 before_item_span_end: BytePos,
2673 where_clause: &ast::WhereClause,
2675 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2677 let pos_after_where = where_clause.span.lo() + BytePos(5);
2678 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2679 (missing_span_before, missing_span_after)
2682 fn rewrite_comments_before_after_where(
2683 context: &RewriteContext,
2684 span_before_where: Span,
2685 span_after_where: Span,
2687 ) -> Option<(String, String)> {
2688 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2689 let after_comment = rewrite_missing_comment(
2691 shape.block_indent(context.config.tab_spaces()),
2694 Some((before_comment, after_comment))
2697 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2698 format!("{}{}{}", format_visibility(vis), item_name, ident)
2701 #[derive(PartialEq, Eq, Clone, Copy)]
2709 context: &RewriteContext,
2710 generics: &ast::Generics,
2711 brace_style: BraceStyle,
2712 brace_pos: BracePos,
2716 ) -> Option<String> {
2717 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2718 let mut result = rewrite_generics(context, generics, shape, span)?;
2720 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2721 let budget = context.budget(last_line_used_width(&result, offset.width()));
2722 let mut option = WhereClauseOption::snuggled(&result);
2723 if brace_pos == BracePos::None {
2724 option.suppress_comma = true;
2726 // If the generics are not parameterized then generics.span.hi() == 0,
2727 // so we use span.lo(), which is the position after `struct Foo`.
2728 let span_end_before_where = if generics.is_parameterized() {
2733 let where_clause_str = rewrite_where_clause(
2735 &generics.where_clause,
2737 Shape::legacy(budget, offset.block_only()),
2741 span_end_before_where,
2745 result.push_str(&where_clause_str);
2746 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2747 || (generics.where_clause.predicates.is_empty()
2748 && trimmed_last_line_width(&result) == 1)
2750 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2751 || brace_style != BraceStyle::AlwaysNextLine
2753 if brace_pos == BracePos::None {
2754 return Some(result);
2756 let total_used_width = last_line_used_width(&result, used_width);
2757 let remaining_budget = context.budget(total_used_width);
2758 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2759 // and hence we take the closer into account as well for one line budget.
2760 // We assume that the closer has the same length as the opener.
2761 let overhead = if brace_pos == BracePos::ForceSameLine {
2768 let forbid_same_line_brace = overhead > remaining_budget;
2769 if !forbid_same_line_brace && same_line_brace {
2773 result.push_str(&offset.block_only().to_string(context.config));
2780 impl Rewrite for ast::ForeignItem {
2781 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2782 let attrs_str = self.attrs.rewrite(context, shape)?;
2783 // Drop semicolon or it will be interpreted as comment.
2784 // FIXME: this may be a faulty span from libsyntax.
2785 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2787 let item_str = match self.node {
2788 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2793 &FnSig::new(fn_decl, generics, self.vis.clone()),
2797 ).map(|(s, _)| format!("{};", s))
2799 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2800 // FIXME(#21): we're dropping potential comments in between the
2801 // function keywords here.
2802 let vis = format_visibility(&self.vis);
2803 let mut_str = if is_mutable { "mut " } else { "" };
2804 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2806 let shape = shape.sub_width(1)?;
2807 ty.rewrite(context, shape).map(|ty_str| {
2808 // 1 = space between prefix and type.
2809 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2812 let nested_indent = shape.indent.block_indent(context.config);
2813 nested_indent.to_string_with_newline(context.config)
2815 format!("{}{}{};", prefix, sep, ty_str)
2818 ast::ForeignItemKind::Ty => {
2819 let vis = format_visibility(&self.vis);
2820 Some(format!("{}type {};", vis, self.ident))
2824 let missing_span = if self.attrs.is_empty() {
2825 mk_sp(self.span.lo(), self.span.lo())
2827 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2829 combine_strs_with_missing_comments(
2840 impl Rewrite for ast::GenericParam {
2841 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2843 ast::GenericParam::Lifetime(ref lifetime_def) => lifetime_def.rewrite(context, shape),
2844 ast::GenericParam::Type(ref ty) => ty.rewrite(context, shape),
2849 /// Rewrite an inline mod.
2850 pub fn rewrite_mod(item: &ast::Item) -> String {
2851 let mut result = String::with_capacity(32);
2852 result.push_str(&*format_visibility(&item.vis));
2853 result.push_str("mod ");
2854 result.push_str(&item.ident.to_string());
2859 /// Rewrite `extern crate foo;` WITHOUT attributes.
2860 pub fn rewrite_extern_crate(context: &RewriteContext, item: &ast::Item) -> Option<String> {
2861 assert!(is_extern_crate(item));
2862 let new_str = context.snippet(item.span);
2863 Some(if contains_comment(new_str) {
2866 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
2867 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
2871 /// Returns true for `mod foo;`, false for `mod foo { .. }`.
2872 pub fn is_mod_decl(item: &ast::Item) -> bool {
2874 ast::ItemKind::Mod(ref m) => m.inner.hi() != item.span.hi(),
2879 pub fn is_use_item(item: &ast::Item) -> bool {
2881 ast::ItemKind::Use(_) => true,
2886 pub fn is_extern_crate(item: &ast::Item) -> bool {
2888 ast::ItemKind::ExternCrate(..) => true,