1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Formatting top-level items - functions, structs, enums, traits, impls.
16 use syntax::{abi, ast, ptr, symbol};
17 use syntax::ast::{CrateSugar, ImplItem};
18 use syntax::codemap::{BytePos, Span};
22 use codemap::{LineRangeUtils, SpanUtils};
23 use comment::{combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
24 recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented};
25 use config::{BraceStyle, Config, Density, IndentStyle};
26 use expr::{choose_rhs, format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs,
27 rewrite_call_inner, ExprType};
28 use lists::{definitive_tactic, itemize_list, write_list, DefinitiveListTactic, ListFormatting,
29 ListItem, ListTactic, Separator, SeparatorPlace, SeparatorTactic};
30 use rewrite::{Rewrite, RewriteContext};
31 use shape::{Indent, Shape};
32 use types::join_bounds;
33 use utils::{colon_spaces, contains_skip, end_typaram, first_line_width, format_abi,
34 format_constness, format_defaultness, format_mutability, format_unsafety,
35 format_visibility, is_attributes_extendable, last_line_contains_single_line_comment,
36 last_line_used_width, last_line_width, mk_sp, semicolon_for_expr, starts_with_newline,
37 stmt_expr, trim_newlines, trimmed_last_line_width};
38 use vertical::rewrite_with_alignment;
39 use visitor::FmtVisitor;
41 fn type_annotation_separator(config: &Config) -> &str {
42 colon_spaces(config.space_before_colon(), config.space_after_colon())
45 // Statements of the form
46 // let pat: ty = init;
47 impl Rewrite for ast::Local {
48 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
50 "Local::rewrite {:?} {} {:?}",
51 self, shape.width, shape.indent
54 skip_out_of_file_lines_range!(context, self.span);
56 if contains_skip(&self.attrs) {
60 let attrs_str = self.attrs.rewrite(context, shape)?;
61 let mut result = if attrs_str.is_empty() {
64 combine_strs_with_missing_comments(
69 self.attrs.last().map(|a| a.span.hi()).unwrap(),
78 let pat_shape = shape.offset_left(4)?;
80 let pat_shape = pat_shape.sub_width(1)?;
81 let pat_str = self.pat.rewrite(context, pat_shape)?;
82 result.push_str(&pat_str);
84 // String that is placed within the assignment pattern and expression.
86 let mut infix = String::with_capacity(32);
88 if let Some(ref ty) = self.ty {
89 let separator = type_annotation_separator(context.config);
90 let indent = shape.indent + last_line_width(&result) + separator.len();
92 let budget = shape.width.checked_sub(indent.width() + 1)?;
93 let rewrite = ty.rewrite(context, Shape::legacy(budget, indent))?;
95 infix.push_str(separator);
96 infix.push_str(&rewrite);
99 if self.init.is_some() {
100 infix.push_str(" =");
106 result.push_str(&infix);
108 if let Some(ref ex) = self.init {
109 // 1 = trailing semicolon;
110 let nested_shape = shape.sub_width(1)?;
112 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
120 // TODO convert to using rewrite style rather than visitor
121 // TODO format modules in this style
124 keyword: &'static str,
125 abi: Cow<'static, str>,
126 vis: Option<&'a ast::Visibility>,
127 body: Vec<BodyElement<'a>>,
132 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
135 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
139 .map(|i| BodyElement::ForeignItem(i))
146 enum BodyElement<'a> {
147 // Stmt(&'a ast::Stmt),
148 // Field(&'a ast::Field),
149 // Variant(&'a ast::Variant),
150 // Item(&'a ast::Item),
151 ForeignItem(&'a ast::ForeignItem),
154 /// Represents a fn's signature.
155 pub struct FnSig<'a> {
156 decl: &'a ast::FnDecl,
157 generics: &'a ast::Generics,
159 constness: ast::Constness,
160 defaultness: ast::Defaultness,
161 unsafety: ast::Unsafety,
162 visibility: ast::Visibility,
167 decl: &'a ast::FnDecl,
168 generics: &'a ast::Generics,
169 vis: ast::Visibility,
175 constness: ast::Constness::NotConst,
176 defaultness: ast::Defaultness::Final,
177 unsafety: ast::Unsafety::Normal,
182 pub fn from_method_sig(
183 method_sig: &'a ast::MethodSig,
184 generics: &'a ast::Generics,
187 unsafety: method_sig.unsafety,
188 constness: method_sig.constness.node,
189 defaultness: ast::Defaultness::Final,
191 decl: &*method_sig.decl,
193 visibility: ast::Visibility::Inherited,
198 fn_kind: &'a visit::FnKind,
199 generics: &'a ast::Generics,
200 decl: &'a ast::FnDecl,
201 defualtness: ast::Defaultness,
204 visit::FnKind::ItemFn(_, unsafety, constness, abi, visibility, _) => FnSig {
208 constness: constness.node,
209 defaultness: defualtness,
211 visibility: visibility.clone(),
213 visit::FnKind::Method(_, method_sig, vis, _) => {
214 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
215 fn_sig.defaultness = defualtness;
216 if let Some(vis) = vis {
217 fn_sig.visibility = vis.clone();
225 fn to_str(&self, context: &RewriteContext) -> String {
226 let mut result = String::with_capacity(128);
227 // Vis defaultness constness unsafety abi.
228 result.push_str(&*format_visibility(&self.visibility));
229 result.push_str(format_defaultness(self.defaultness));
230 result.push_str(format_constness(self.constness));
231 result.push_str(format_unsafety(self.unsafety));
232 result.push_str(&format_abi(
234 context.config.force_explicit_abi(),
241 impl<'a> FmtVisitor<'a> {
242 fn format_item(&mut self, item: Item) {
243 self.push_str(&item.abi);
245 let snippet = self.snippet(item.span);
246 let brace_pos = snippet.find_uncommented("{").unwrap();
249 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
250 // FIXME: this skips comments between the extern keyword and the opening
252 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
253 self.block_indent = self.block_indent.block_indent(self.config);
255 if item.body.is_empty() {
256 self.format_missing_no_indent(item.span.hi() - BytePos(1));
257 self.block_indent = self.block_indent.block_unindent(self.config);
258 let indent_str = self.block_indent.to_string(self.config);
259 self.push_str(&indent_str);
261 for item in &item.body {
262 self.format_body_element(item);
265 self.block_indent = self.block_indent.block_unindent(self.config);
266 self.format_missing_with_indent(item.span.hi() - BytePos(1));
271 self.last_pos = item.span.hi();
274 fn format_body_element(&mut self, element: &BodyElement) {
276 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
280 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
281 let item = Item::from_foreign_mod(fm, span, self.config);
282 self.format_item(item);
285 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
286 let rewrite = item.rewrite(&self.get_context(), self.shape());
287 self.push_rewrite(item.span(), rewrite);
288 self.last_pos = item.span.hi();
298 ) -> Option<String> {
299 let context = self.get_context();
301 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
303 let (mut result, force_newline_brace) =
304 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
307 if self.config.brace_style() == BraceStyle::AlwaysNextLine || force_newline_brace
308 || last_line_width(&result) + 2 > self.shape().width
310 newline_brace = true;
311 } else if !result.contains('\n') {
312 newline_brace = false;
315 // Prepare for the function body by possibly adding a newline and
317 // FIXME we'll miss anything between the end of the signature and the
318 // start of the body, but we need more spans from the compiler to solve
322 result.push_str(&indent.to_string(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);
475 let indentation = self.block_indent.to_string(self.config);
476 result.push_str(&indentation);
478 let itemize_list_with = |one_line_width: usize| {
481 enum_def.variants.iter(),
484 |f| if !f.node.attrs.is_empty() {
485 f.node.attrs[0].span.lo()
490 |f| self.format_variant(f, one_line_width),
496 let mut items: Vec<_> =
497 itemize_list_with(self.config.width_heuristics().struct_variant_width);
498 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
499 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
500 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
501 if has_multiline_variant && has_single_line_variant {
502 items = itemize_list_with(0);
505 let shape = self.shape().sub_width(2).unwrap();
506 let fmt = ListFormatting {
507 tactic: DefinitiveListTactic::Vertical,
509 trailing_separator: self.config.trailing_comma(),
510 separator_place: SeparatorPlace::Back,
512 ends_with_newline: true,
513 preserve_newline: true,
517 let list = write_list(&items, &fmt)?;
518 result.push_str(&list);
523 // Variant of an enum.
524 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
525 if contains_skip(&field.node.attrs) {
526 let lo = field.node.attrs[0].span.lo();
527 let span = mk_sp(lo, field.span.hi());
528 return Some(self.snippet(span).to_owned());
531 let context = self.get_context();
533 let shape = self.shape().sub_width(1)?;
534 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
539 .map_or(field.span.lo(), |attr| attr.span.hi());
540 let span = mk_sp(lo, field.span.lo());
542 let variant_body = match field.node.data {
543 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
545 &StructParts::from_variant(field),
547 Some(one_line_width),
549 ast::VariantData::Unit(..) => {
550 if let Some(ref expr) = field.node.disr_expr {
551 let lhs = format!("{} =", field.node.name);
552 rewrite_assign_rhs(&context, lhs, &**expr, shape)?
554 field.node.name.to_string()
559 let attrs_extendable = attrs_str.is_empty()
560 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
561 combine_strs_with_missing_comments(
573 context: &RewriteContext,
576 where_span_end: Option<BytePos>,
577 ) -> Option<String> {
578 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
579 let mut result = String::with_capacity(128);
580 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
581 let indent_str = offset.to_string(context.config);
582 let sep = format!("\n{}", &indent_str);
583 result.push_str(&ref_and_type);
585 let where_budget = if result.contains('\n') {
586 context.config.max_width()
588 context.budget(last_line_width(&result))
590 let option = WhereClauseOption::snuggled(&ref_and_type);
591 let where_clause_str = rewrite_where_clause(
593 &generics.where_clause,
594 context.config.brace_style(),
595 Shape::legacy(where_budget, offset.block_only()),
604 // If there is no where clause, we may have missing comments between the trait name and
605 // the opening brace.
606 if generics.where_clause.predicates.is_empty() {
607 if let Some(hi) = where_span_end {
608 match recover_missing_comment_in_span(
609 mk_sp(self_ty.span.hi(), hi),
610 Shape::indented(offset, context.config),
612 last_line_width(&result),
614 Some(ref missing_comment) if !missing_comment.is_empty() => {
615 result.push_str(missing_comment);
622 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
623 result.push_str(&where_clause_str);
624 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
625 result.push_str(&format!("{}{{{}}}", &sep, &sep));
627 result.push_str(" {}");
632 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
634 let width = offset.block_indent + context.config.tab_spaces() - 1;
635 let where_indent = Indent::new(0, width);
636 result.push_str(&where_indent.to_string(context.config));
638 result.push_str(&where_clause_str);
640 match context.config.brace_style() {
641 _ if last_line_contains_single_line_comment(&result) => result.push_str(&sep),
642 BraceStyle::AlwaysNextLine => result.push_str(&sep),
643 BraceStyle::PreferSameLine => result.push(' '),
644 BraceStyle::SameLineWhere => {
645 if !where_clause_str.is_empty() {
646 result.push_str(&sep);
655 let snippet = context.snippet(item.span);
656 let open_pos = snippet.find_uncommented("{")? + 1;
658 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
659 let mut visitor = FmtVisitor::from_context(context);
660 visitor.block_indent = offset.block_only().block_indent(context.config);
661 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
663 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
665 visitor.visit_impl_item(item);
668 visitor.format_missing(item.span.hi() - BytePos(1));
670 let inner_indent_str = visitor.block_indent.to_string(context.config);
671 let outer_indent_str = offset.block_only().to_string(context.config);
674 result.push_str(&inner_indent_str);
675 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
677 result.push_str(&outer_indent_str);
680 if result.ends_with('{') {
681 result.push_str(&sep);
691 fn is_impl_single_line(
692 context: &RewriteContext,
695 where_clause_str: &str,
698 let snippet = context.snippet(item.span);
699 let open_pos = snippet.find_uncommented("{")? + 1;
702 context.config.empty_item_single_line() && items.is_empty() && !result.contains('\n')
703 && result.len() + where_clause_str.len() <= context.config.max_width()
704 && !contains_comment(&snippet[open_pos..]),
708 fn format_impl_ref_and_type(
709 context: &RewriteContext,
712 ) -> Option<String> {
713 if let ast::ItemKind::Impl(
723 let mut result = String::with_capacity(128);
725 result.push_str(&format_visibility(&item.vis));
726 result.push_str(format_defaultness(defaultness));
727 result.push_str(format_unsafety(unsafety));
728 result.push_str("impl");
730 let lo = context.codemap.span_after(item.span, "impl");
731 let hi = match *trait_ref {
732 Some(ref tr) => tr.path.span.lo(),
733 None => self_ty.span.lo(),
735 let shape = generics_shape_from_config(
737 Shape::indented(offset + last_line_width(&result), context.config),
740 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
742 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
744 let polarity_str = if polarity == ast::ImplPolarity::Negative {
750 if let Some(ref trait_ref) = *trait_ref {
751 let result_len = result.len();
752 if let Some(trait_ref_str) = rewrite_trait_ref(
761 result.push_str(&trait_ref_str);
764 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
765 result.push_str(&rewrite_trait_ref(
776 result.push_str(&generics_str);
779 // Try to put the self type in a single line.
781 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
782 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
783 // If there is no where clause adapt budget for type formatting to take space and curly
784 // brace into account.
785 match context.config.brace_style() {
786 BraceStyle::AlwaysNextLine => 0,
792 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
793 // 1 = space before the type.
794 let budget = context.budget(used_space + 1);
795 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
796 if !self_ty_str.contains('\n') {
797 if trait_ref.is_some() {
798 result.push_str(" for ");
802 result.push_str(&self_ty_str);
807 // Couldn't fit the self type on a single line, put it on a new line.
809 // Add indentation of one additional tab.
810 let new_line_offset = offset.block_indent(context.config);
811 result.push_str(&new_line_offset.to_string(context.config));
812 if trait_ref.is_some() {
813 result.push_str("for ");
815 let budget = context.budget(last_line_width(&result));
816 let type_offset = match context.config.indent_style() {
817 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
818 IndentStyle::Block => new_line_offset,
820 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
827 fn rewrite_trait_ref(
828 context: &RewriteContext,
829 trait_ref: &ast::TraitRef,
835 ) -> Option<String> {
836 // 1 = space between generics and trait_ref
837 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
838 let shape = Shape::indented(offset + used_space, context.config);
839 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
840 if !(retry && trait_ref_str.contains('\n')) {
843 generics_str, polarity_str, &trait_ref_str
847 // We could not make enough space for trait_ref, so put it on new line.
849 let offset = offset.block_indent(context.config);
850 let shape = Shape::indented(offset, context.config);
851 let trait_ref_str = trait_ref.rewrite(context, shape)?;
855 &offset.to_string(context.config),
864 pub struct StructParts<'a> {
867 vis: &'a ast::Visibility,
868 def: &'a ast::VariantData,
869 generics: Option<&'a ast::Generics>,
873 impl<'a> StructParts<'a> {
874 fn format_header(&self) -> String {
875 format_header(self.prefix, self.ident, self.vis)
878 fn from_variant(variant: &'a ast::Variant) -> Self {
881 ident: variant.node.name,
882 vis: &ast::Visibility::Inherited,
883 def: &variant.node.data,
889 pub fn from_item(item: &'a ast::Item) -> Self {
890 let (prefix, def, generics) = match item.node {
891 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
892 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
900 generics: Some(generics),
907 context: &RewriteContext,
908 struct_parts: &StructParts,
910 one_line_width: Option<usize>,
911 ) -> Option<String> {
912 match *struct_parts.def {
913 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
914 ast::VariantData::Tuple(ref fields, _) => {
915 format_tuple_struct(context, struct_parts, fields, offset)
917 ast::VariantData::Struct(ref fields, _) => {
918 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
923 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
924 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
927 let mut result = String::with_capacity(128);
928 let header = format!(
930 format_visibility(&item.vis),
931 format_unsafety(unsafety),
935 result.push_str(&header);
937 let body_lo = context.codemap.span_after(item.span, "{");
939 let shape = Shape::indented(offset, context.config);
941 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
942 result.push_str(&generics_str);
944 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
945 if !type_param_bounds.is_empty() {
946 let ident_hi = context.codemap.span_after(item.span, &format!("{}", item.ident));
947 let bound_hi = type_param_bounds.last().unwrap().span().hi();
948 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
949 if contains_comment(&snippet) {
953 let trait_bound_str = rewrite_trait_bounds(
956 Shape::indented(offset, context.config),
958 // If the trait, generics, and trait bound cannot fit on the same line,
959 // put the trait bounds on an indented new line
960 if offset.width() + last_line_width(&result) + trait_bound_str.len()
961 > context.config.comment_width()
964 let trait_indent = offset.block_only().block_indent(context.config);
965 result.push_str(&trait_indent.to_string(context.config));
967 result.push_str(&trait_bound_str);
970 if context.config.indent_style() == IndentStyle::Block && result.is_empty() {
976 let where_budget = context.budget(last_line_width(&result));
977 let pos_before_where = if type_param_bounds.is_empty() {
978 generics.where_clause.span.lo()
980 type_param_bounds[type_param_bounds.len() - 1].span().hi()
982 let option = WhereClauseOption::snuggled(&generics_str);
983 let where_clause_str = rewrite_where_clause(
985 &generics.where_clause,
986 context.config.brace_style(),
987 Shape::legacy(where_budget, offset.block_only()),
995 // If the where clause cannot fit on the same line,
996 // put the where clause on a new line
997 if !where_clause_str.contains('\n')
998 && last_line_width(&result) + where_clause_str.len() + offset.width()
999 > context.config.comment_width()
1002 let width = offset.block_indent + context.config.tab_spaces() - 1;
1003 let where_indent = Indent::new(0, width);
1004 result.push_str(&where_indent.to_string(context.config));
1006 result.push_str(&where_clause_str);
1008 if generics.where_clause.predicates.is_empty() {
1009 let item_snippet = context.snippet(item.span);
1010 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1012 let comment_hi = body_lo - BytePos(1);
1013 let comment_lo = item.span.lo() + BytePos(lo as u32);
1014 if comment_lo < comment_hi {
1015 match recover_missing_comment_in_span(
1016 mk_sp(comment_lo, comment_hi),
1017 Shape::indented(offset, context.config),
1019 last_line_width(&result),
1021 Some(ref missing_comment) if !missing_comment.is_empty() => {
1022 result.push_str(missing_comment);
1030 match context.config.brace_style() {
1031 _ if last_line_contains_single_line_comment(&result) => {
1033 result.push_str(&offset.to_string(context.config));
1035 BraceStyle::AlwaysNextLine => {
1037 result.push_str(&offset.to_string(context.config));
1039 BraceStyle::PreferSameLine => result.push(' '),
1040 BraceStyle::SameLineWhere => {
1041 if !where_clause_str.is_empty()
1042 && (!trait_items.is_empty() || result.contains('\n'))
1045 result.push_str(&offset.to_string(context.config));
1053 let snippet = context.snippet(item.span);
1054 let open_pos = snippet.find_uncommented("{")? + 1;
1056 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1057 let mut visitor = FmtVisitor::from_context(context);
1058 visitor.block_indent = offset.block_only().block_indent(context.config);
1059 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1061 for item in trait_items {
1062 visitor.visit_trait_item(item);
1065 visitor.format_missing(item.span.hi() - BytePos(1));
1067 let inner_indent_str = visitor.block_indent.to_string(context.config);
1068 let outer_indent_str = offset.block_only().to_string(context.config);
1071 result.push_str(&inner_indent_str);
1072 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1074 result.push_str(&outer_indent_str);
1075 } else if result.contains('\n') {
1086 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1087 let header_str = format_header(p.prefix, p.ident, p.vis);
1088 let generics_str = if let Some(generics) = p.generics {
1089 let hi = if generics.where_clause.predicates.is_empty() {
1092 generics.where_clause.span.hi()
1097 context.config.brace_style(),
1100 mk_sp(generics.span.lo(), hi),
1101 last_line_width(&header_str),
1106 Some(format!("{}{};", header_str, generics_str))
1109 pub fn format_struct_struct(
1110 context: &RewriteContext,
1111 struct_parts: &StructParts,
1112 fields: &[ast::StructField],
1114 one_line_width: Option<usize>,
1115 ) -> Option<String> {
1116 let mut result = String::with_capacity(1024);
1117 let span = struct_parts.span;
1119 let header_str = struct_parts.format_header();
1120 result.push_str(&header_str);
1122 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1123 let body_lo = context.codemap.span_after(span, "{");
1125 let generics_str = match struct_parts.generics {
1126 Some(g) => format_generics(
1129 context.config.brace_style(),
1130 if fields.is_empty() {
1131 BracePos::ForceSameLine
1136 mk_sp(header_hi, body_lo),
1137 last_line_width(&result),
1140 // 3 = ` {}`, 2 = ` {`.
1141 let overhead = if fields.is_empty() { 3 } else { 2 };
1142 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1143 || context.config.max_width() < overhead + result.len()
1145 format!("\n{}{{", offset.block_only().to_string(context.config))
1152 let overhead = if fields.is_empty() { 1 } else { 0 };
1153 let total_width = result.len() + generics_str.len() + overhead;
1154 if !generics_str.is_empty() && !generics_str.contains('\n')
1155 && total_width > context.config.max_width()
1158 result.push_str(&offset.to_string(context.config));
1159 result.push_str(generics_str.trim_left());
1161 result.push_str(&generics_str);
1164 if fields.is_empty() {
1165 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1166 if snippet.trim().is_empty() {
1168 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1170 result.push_str(snippet.trim_right());
1172 result.push_str(&offset.to_string(context.config));
1174 result.push_str(&snippet);
1177 return Some(result);
1181 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1182 let one_line_budget =
1183 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1185 let items_str = rewrite_with_alignment(
1188 Shape::indented(offset, context.config).sub_width(1)?,
1189 mk_sp(body_lo, span.hi()),
1193 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget {
1194 Some(format!("{} {} }}", result, items_str))
1200 .block_indent(context.config)
1201 .to_string(context.config),
1203 offset.to_string(context.config)
1208 /// Returns a bytepos that is after that of `(` in `pub(..)`. If the given visibility does not
1209 /// contain `pub(..)`, then return the `lo` of the `defualt_span`. Yeah, but for what? Well, we need
1210 /// to bypass the `(` in the visibility when creating a span of tuple's body or fn's args.
1211 fn get_bytepos_after_visibility(
1212 context: &RewriteContext,
1213 vis: &ast::Visibility,
1218 ast::Visibility::Crate(s, CrateSugar::PubCrate) => context
1220 .span_after(mk_sp(s.hi(), default_span.hi()), terminator),
1221 ast::Visibility::Crate(s, CrateSugar::JustCrate) => s.hi(),
1222 ast::Visibility::Restricted { ref path, .. } => path.span.hi(),
1223 _ => default_span.lo(),
1227 fn format_tuple_struct(
1228 context: &RewriteContext,
1229 struct_parts: &StructParts,
1230 fields: &[ast::StructField],
1232 ) -> Option<String> {
1233 let mut result = String::with_capacity(1024);
1234 let span = struct_parts.span;
1236 let header_str = struct_parts.format_header();
1237 result.push_str(&header_str);
1239 let body_lo = if fields.is_empty() {
1240 let lo = get_bytepos_after_visibility(context, struct_parts.vis, span, ")");
1241 context.codemap.span_after(mk_sp(lo, span.hi()), "(")
1245 let body_hi = if fields.is_empty() {
1246 context.codemap.span_after(mk_sp(body_lo, span.hi()), ")")
1248 // This is a dirty hack to work around a missing `)` from the span of the last field.
1249 let last_arg_span = fields[fields.len() - 1].span;
1250 if context.snippet(last_arg_span).ends_with(')') {
1255 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1259 let where_clause_str = match struct_parts.generics {
1261 let budget = context.budget(last_line_width(&header_str));
1262 let shape = Shape::legacy(budget, offset);
1263 let g_span = mk_sp(span.lo(), body_lo);
1264 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1265 result.push_str(&generics_str);
1267 let where_budget = context.budget(last_line_width(&result));
1268 let option = WhereClauseOption::new(true, false);
1269 rewrite_where_clause(
1271 &generics.where_clause,
1272 context.config.brace_style(),
1273 Shape::legacy(where_budget, offset.block_only()),
1274 Density::Compressed,
1282 None => "".to_owned(),
1285 if fields.is_empty() {
1287 let used_width = last_line_used_width(&result, offset.width()) + 3;
1288 if used_width > context.config.max_width() {
1290 result.push_str(&offset
1291 .block_indent(context.config)
1292 .to_string(context.config))
1295 let snippet = context.snippet(mk_sp(
1297 context.codemap.span_before(mk_sp(body_lo, span.hi()), ")"),
1299 if snippet.is_empty() {
1301 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1302 result.push_str(snippet.trim_right());
1304 result.push_str(&offset.to_string(context.config));
1306 result.push_str(&snippet);
1310 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1311 let fields = &fields.iter().collect::<Vec<_>>()[..];
1312 let one_line_width = context.config.width_heuristics().fn_call_width;
1313 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1316 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1317 && (result.contains('\n')
1318 || offset.block_indent + result.len() + where_clause_str.len() + 1
1319 > context.config.max_width())
1321 // We need to put the where clause on a new line, but we didn't
1322 // know that earlier, so the where clause will not be indented properly.
1324 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1325 .to_string(context.config));
1327 result.push_str(&where_clause_str);
1332 pub fn rewrite_type_alias(
1333 context: &RewriteContext,
1337 generics: &ast::Generics,
1338 vis: &ast::Visibility,
1340 ) -> Option<String> {
1341 let mut result = String::with_capacity(128);
1343 result.push_str(&format_visibility(vis));
1344 result.push_str("type ");
1345 result.push_str(&ident.to_string());
1348 let shape = Shape::indented(indent + result.len(), context.config).sub_width(2)?;
1349 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo());
1350 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1351 result.push_str(&generics_str);
1353 let where_budget = context.budget(last_line_width(&result));
1354 let option = WhereClauseOption::snuggled(&result);
1355 let where_clause_str = rewrite_where_clause(
1357 &generics.where_clause,
1358 context.config.brace_style(),
1359 Shape::legacy(where_budget, indent),
1367 result.push_str(&where_clause_str);
1368 if where_clause_str.is_empty() {
1369 result.push_str(" = ");
1371 result.push_str(&format!("\n{}= ", indent.to_string(context.config)));
1374 let line_width = last_line_width(&result);
1375 // This checked_sub may fail as the extra space after '=' is not taken into account
1376 // In that case the budget is set to 0 which will make ty.rewrite retry on a new line
1377 let budget = context.budget(indent.width() + line_width + ";".len());
1378 let type_indent = indent + line_width;
1379 // Try to fit the type on the same line
1380 let ty_str = ty.rewrite(context, Shape::legacy(budget, type_indent))
1382 // The line was too short, try to put the type on the next line
1384 // Remove the space after '='
1386 let type_indent = indent.block_indent(context.config);
1388 result.push_str(&type_indent.to_string(context.config));
1389 let budget = context.budget(type_indent.width() + ";".len());
1390 ty.rewrite(context, Shape::legacy(budget, type_indent))
1392 result.push_str(&ty_str);
1393 result.push_str(";");
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 let snippet = context.snippet(mk_sp(field.attrs[0].span.lo(), field.span.hi()));
1430 return Some(snippet.to_owned());
1433 let type_annotation_spacing = type_annotation_spacing(context.config);
1434 let prefix = rewrite_struct_field_prefix(context, field)?;
1436 let attrs_str = field.attrs.rewrite(context, shape)?;
1437 let attrs_extendable = attrs_str.is_empty()
1438 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
1439 let missing_span = if field.attrs.is_empty() {
1440 mk_sp(field.span.lo(), field.span.lo())
1442 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1444 let mut spacing = String::from(if field.ident.is_some() {
1445 type_annotation_spacing.1
1449 // Try to put everything on a single line.
1450 let attr_prefix = combine_strs_with_missing_comments(
1458 let overhead = last_line_width(&attr_prefix);
1459 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1460 for _ in 0..lhs_offset {
1463 // In this extreme case we will be missing a space betweeen an attribute and a field.
1464 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1467 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1468 let mut orig_ty = field.ty.rewrite(context, ty_shape);
1469 if let Some(ref ty) = orig_ty {
1470 if !ty.contains('\n') {
1471 return Some(attr_prefix + &spacing + ty);
1475 // We must use multiline. We are going to put attributes and a field on different lines.
1477 let rhs_shape = shape.offset_left(last_line_width(&prefix) + 1)?;
1478 orig_ty = field.ty.rewrite(context, rhs_shape);
1479 let field_str = if prefix.is_empty() {
1482 prefix + &choose_rhs(context, &*field.ty, rhs_shape, orig_ty)?
1484 combine_strs_with_missing_comments(context, &attrs_str, &field_str, missing_span, shape, false)
1487 pub struct StaticParts<'a> {
1489 vis: &'a ast::Visibility,
1492 mutability: ast::Mutability,
1493 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1494 defaultness: Option<ast::Defaultness>,
1498 impl<'a> StaticParts<'a> {
1499 pub fn from_item(item: &'a ast::Item) -> Self {
1500 let (prefix, ty, mutability, expr) = match item.node {
1501 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1502 ast::ItemKind::Const(ref ty, ref expr) => {
1503 ("const", ty, ast::Mutability::Immutable, expr)
1505 _ => unreachable!(),
1512 mutability: mutability,
1513 expr_opt: Some(expr),
1519 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1520 let (ty, expr_opt) = match ti.node {
1521 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1522 _ => unreachable!(),
1526 vis: &ast::Visibility::Inherited,
1529 mutability: ast::Mutability::Immutable,
1530 expr_opt: expr_opt.as_ref(),
1536 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1537 let (ty, expr) = match ii.node {
1538 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1539 _ => unreachable!(),
1546 mutability: ast::Mutability::Immutable,
1547 expr_opt: Some(expr),
1548 defaultness: Some(ii.defaultness),
1555 context: &RewriteContext,
1556 static_parts: &StaticParts,
1558 ) -> Option<String> {
1559 let colon = colon_spaces(
1560 context.config.space_before_colon(),
1561 context.config.space_after_colon(),
1563 let prefix = format!(
1565 format_visibility(static_parts.vis),
1566 static_parts.defaultness.map_or("", format_defaultness),
1567 static_parts.prefix,
1568 format_mutability(static_parts.mutability),
1574 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1575 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1577 if let Some(expr) = static_parts.expr_opt {
1578 let lhs = format!("{}{} =", prefix, ty_str);
1580 let remaining_width = context.budget(offset.block_indent + 1);
1585 Shape::legacy(remaining_width, offset.block_only()),
1586 ).and_then(|res| recover_comment_removed(res, static_parts.span, context))
1587 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1589 Some(format!("{}{};", prefix, ty_str))
1593 pub fn rewrite_associated_type(
1595 ty_opt: Option<&ptr::P<ast::Ty>>,
1596 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1597 context: &RewriteContext,
1599 ) -> Option<String> {
1600 let prefix = format!("type {}", ident);
1602 let type_bounds_str = if let Some(bounds) = ty_param_bounds_opt {
1604 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1605 let bound_str = bounds
1607 .map(|ty_bound| ty_bound.rewrite(context, shape))
1608 .collect::<Option<Vec<_>>>()?;
1609 if !bounds.is_empty() {
1610 format!(": {}", join_bounds(context, shape, &bound_str))
1618 if let Some(ty) = ty_opt {
1620 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1621 let lhs = format!("{}{} =", prefix, type_bounds_str);
1622 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1624 Some(format!("{}{};", prefix, type_bounds_str))
1628 pub fn rewrite_associated_impl_type(
1630 defaultness: ast::Defaultness,
1631 ty_opt: Option<&ptr::P<ast::Ty>>,
1632 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1633 context: &RewriteContext,
1635 ) -> Option<String> {
1636 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1639 ast::Defaultness::Default => Some(format!("default {}", result)),
1644 impl Rewrite for ast::FunctionRetTy {
1645 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1647 ast::FunctionRetTy::Default(_) => Some(String::new()),
1648 ast::FunctionRetTy::Ty(ref ty) => {
1649 let inner_width = shape.width.checked_sub(3)?;
1650 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1651 .map(|r| format!("-> {}", r))
1657 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1659 ast::TyKind::Infer => {
1660 let original = context.snippet(ty.span);
1667 impl Rewrite for ast::Arg {
1668 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1669 if is_named_arg(self) {
1670 let mut result = self.pat
1671 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1673 if !is_empty_infer(context, &*self.ty) {
1674 if context.config.space_before_colon() {
1675 result.push_str(" ");
1677 result.push_str(":");
1678 if context.config.space_after_colon() {
1679 result.push_str(" ");
1681 let overhead = last_line_width(&result);
1682 let max_width = shape.width.checked_sub(overhead)?;
1683 let ty_str = self.ty
1684 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1685 result.push_str(&ty_str);
1690 self.ty.rewrite(context, shape)
1695 fn rewrite_explicit_self(
1696 explicit_self: &ast::ExplicitSelf,
1698 context: &RewriteContext,
1699 ) -> Option<String> {
1700 match explicit_self.node {
1701 ast::SelfKind::Region(lt, m) => {
1702 let mut_str = format_mutability(m);
1705 let lifetime_str = l.rewrite(
1707 Shape::legacy(context.config.max_width(), Indent::empty()),
1709 Some(format!("&{} {}self", lifetime_str, mut_str))
1711 None => Some(format!("&{}self", mut_str)),
1714 ast::SelfKind::Explicit(ref ty, _) => {
1715 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1717 let mutability = explicit_self_mutability(&args[0]);
1718 let type_str = ty.rewrite(
1720 Shape::legacy(context.config.max_width(), Indent::empty()),
1725 format_mutability(mutability),
1729 ast::SelfKind::Value(_) => {
1730 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1732 let mutability = explicit_self_mutability(&args[0]);
1734 Some(format!("{}self", format_mutability(mutability)))
1739 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1740 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1741 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1742 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1749 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1750 if is_named_arg(arg) {
1757 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1759 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1760 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1761 _ => arg.ty.span.hi(),
1765 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1766 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1767 ident.node != symbol::keywords::Invalid.ident()
1773 // Return type is (result, force_new_line_for_brace)
1775 context: &RewriteContext,
1780 newline_brace: bool,
1782 ) -> Option<(String, bool)> {
1783 let mut force_new_line_for_brace = false;
1785 let where_clause = &fn_sig.generics.where_clause;
1787 let mut result = String::with_capacity(1024);
1788 result.push_str(&fn_sig.to_str(context));
1791 result.push_str("fn ");
1792 result.push_str(&ident.to_string());
1795 let overhead = if has_body && !newline_brace {
1802 let used_width = last_line_used_width(&result, indent.width());
1803 let one_line_budget = context.budget(used_width + overhead);
1805 width: one_line_budget,
1809 let fd = fn_sig.decl;
1810 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1811 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1812 result.push_str(&generics_str);
1814 let snuggle_angle_bracket = generics_str
1817 .map_or(false, |l| l.trim_left().len() == 1);
1819 // Note that the width and indent don't really matter, we'll re-layout the
1820 // return type later anyway.
1821 let ret_str = fd.output
1822 .rewrite(context, Shape::indented(indent, context.config))?;
1824 let multi_line_ret_str = ret_str.contains('\n');
1825 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1828 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1839 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1840 one_line_budget, multi_line_budget, arg_indent
1843 // Check if vertical layout was forced.
1844 if one_line_budget == 0 {
1845 if snuggle_angle_bracket {
1848 result.push_str("(");
1849 if context.config.indent_style() == IndentStyle::Visual {
1851 result.push_str(&arg_indent.to_string(context.config));
1857 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1858 && result.ends_with('(')
1863 // Skip `pub(crate)`.
1864 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1865 // A conservative estimation, to goal is to be over all parens in generics
1866 let args_start = fn_sig
1870 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1871 let args_end = if fd.inputs.is_empty() {
1874 .span_after(mk_sp(args_start, span.hi()), ")")
1876 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1877 context.codemap.span_after(last_span, ")")
1879 let args_span = mk_sp(
1882 .span_after(mk_sp(args_start, span.hi()), "("),
1885 let arg_str = rewrite_args(
1888 fd.get_self().as_ref(),
1895 generics_str.contains('\n'),
1898 let put_args_in_block = match context.config.indent_style() {
1899 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1901 } && !fd.inputs.is_empty();
1903 let mut args_last_line_contains_comment = false;
1904 if put_args_in_block {
1905 arg_indent = indent.block_indent(context.config);
1907 result.push_str(&arg_indent.to_string(context.config));
1908 result.push_str(&arg_str);
1910 result.push_str(&indent.to_string(context.config));
1913 result.push_str(&arg_str);
1914 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1915 // Put the closing brace on the next line if it overflows the max width.
1917 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1920 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1923 // If the last line of args contains comment, we cannot put the closing paren
1924 // on the same line.
1928 .map_or(false, |last_line| last_line.contains("//"))
1930 args_last_line_contains_comment = true;
1932 result.push_str(&arg_indent.to_string(context.config));
1938 if let ast::FunctionRetTy::Ty(..) = fd.output {
1939 let ret_should_indent = match context.config.indent_style() {
1940 // If our args are block layout then we surely must have space.
1941 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1942 _ if args_last_line_contains_comment => false,
1943 _ if result.contains('\n') || multi_line_ret_str => true,
1945 // If the return type would push over the max width, then put the return type on
1946 // a new line. With the +1 for the signature length an additional space between
1947 // the closing parenthesis of the argument and the arrow '->' is considered.
1948 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1950 // If there is no where clause, take into account the space after the return type
1952 if where_clause.predicates.is_empty() {
1956 sig_length > context.config.max_width()
1959 let ret_indent = if ret_should_indent {
1960 let indent = if arg_str.is_empty() {
1961 // Aligning with non-existent args looks silly.
1962 force_new_line_for_brace = true;
1965 // FIXME: we might want to check that using the arg indent
1966 // doesn't blow our budget, and if it does, then fallback to
1967 // the where clause indent.
1972 result.push_str(&indent.to_string(context.config));
1976 Indent::new(indent.block_indent, last_line_width(&result))
1979 if multi_line_ret_str || ret_should_indent {
1980 // Now that we know the proper indent and width, we need to
1981 // re-layout the return type.
1982 let ret_str = fd.output
1983 .rewrite(context, Shape::indented(ret_indent, context.config))?;
1984 result.push_str(&ret_str);
1986 result.push_str(&ret_str);
1989 // Comment between return type and the end of the decl.
1990 let snippet_lo = fd.output.span().hi();
1991 if where_clause.predicates.is_empty() {
1992 let snippet_hi = span.hi();
1993 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
1994 // Try to preserve the layout of the original snippet.
1995 let original_starts_with_newline = snippet
1997 .map_or(false, |i| starts_with_newline(&snippet[i..]));
1998 let original_ends_with_newline = snippet
1999 .rfind(|c| c != ' ')
2000 .map_or(false, |i| snippet[i..].ends_with('\n'));
2001 let snippet = snippet.trim();
2002 if !snippet.is_empty() {
2003 result.push(if original_starts_with_newline {
2008 result.push_str(snippet);
2009 if original_ends_with_newline {
2010 force_new_line_for_brace = true;
2016 let pos_before_where = match fd.output {
2017 ast::FunctionRetTy::Default(..) => args_span.hi(),
2018 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2021 let is_args_multi_lined = arg_str.contains('\n');
2023 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2024 let where_clause_str = rewrite_where_clause(
2027 context.config.brace_style(),
2028 Shape::indented(indent, context.config),
2034 is_args_multi_lined,
2036 // If there are neither where clause nor return type, we may be missing comments between
2038 if where_clause_str.is_empty() {
2039 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2040 match recover_missing_comment_in_span(
2041 mk_sp(args_span.hi(), ret_span.hi()),
2044 last_line_width(&result),
2046 Some(ref missing_comment) if !missing_comment.is_empty() => {
2047 result.push_str(missing_comment);
2048 force_new_line_for_brace = true;
2055 result.push_str(&where_clause_str);
2057 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2058 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2059 Some((result, force_new_line_for_brace))
2062 #[derive(Copy, Clone)]
2063 struct WhereClauseOption {
2064 suppress_comma: bool, // Force no trailing comma
2065 snuggle: bool, // Do not insert newline before `where`
2066 compress_where: bool, // Try single line where clause instead of vertical layout
2069 impl WhereClauseOption {
2070 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2072 suppress_comma: suppress_comma,
2074 compress_where: false,
2078 pub fn snuggled(current: &str) -> WhereClauseOption {
2080 suppress_comma: false,
2081 snuggle: trimmed_last_line_width(current) == 1,
2082 compress_where: false,
2088 context: &RewriteContext,
2090 explicit_self: Option<&ast::ExplicitSelf>,
2091 one_line_budget: usize,
2092 multi_line_budget: usize,
2097 generics_str_contains_newline: bool,
2098 ) -> Option<String> {
2099 let mut arg_item_strs = args.iter()
2100 .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
2101 .collect::<Option<Vec<_>>>()?;
2103 // Account for sugary self.
2104 // FIXME: the comment for the self argument is dropped. This is blocked
2105 // on rust issue #27522.
2106 let min_args = explicit_self
2107 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2108 .map_or(1, |self_str| {
2109 arg_item_strs[0] = self_str;
2113 // Comments between args.
2114 let mut arg_items = Vec::new();
2116 arg_items.push(ListItem::from_str(""));
2119 // FIXME(#21): if there are no args, there might still be a comment, but
2120 // without spans for the comment or parens, there is no chance of
2121 // getting it right. You also don't get to put a comment on self, unless
2123 if args.len() >= min_args || variadic {
2124 let comment_span_start = if min_args == 2 {
2125 let second_arg_start = if arg_has_pattern(&args[1]) {
2126 args[1].pat.span.lo()
2128 args[1].ty.span.lo()
2130 let reduced_span = mk_sp(span.lo(), second_arg_start);
2132 context.codemap.span_after_last(reduced_span, ",")
2137 enum ArgumentKind<'a> {
2138 Regular(&'a ast::Arg),
2142 let variadic_arg = if variadic {
2143 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2144 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2145 Some(ArgumentKind::Variadic(variadic_start))
2150 let more_items = itemize_list(
2152 args[min_args - 1..]
2154 .map(ArgumentKind::Regular)
2155 .chain(variadic_arg),
2159 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2160 ArgumentKind::Variadic(start) => start,
2163 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2164 ArgumentKind::Variadic(start) => start + BytePos(3),
2167 ArgumentKind::Regular(..) => None,
2168 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2175 arg_items.extend(more_items);
2178 let fits_in_one_line = !generics_str_contains_newline
2179 && (arg_items.is_empty()
2180 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2182 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2183 item.item = Some(arg);
2186 let last_line_ends_with_comment = arg_items
2189 .and_then(|item| item.post_comment.as_ref())
2190 .map_or(false, |s| s.trim().starts_with("//"));
2192 let (indent, trailing_comma) = match context.config.indent_style() {
2193 IndentStyle::Block if fits_in_one_line => {
2194 (indent.block_indent(context.config), SeparatorTactic::Never)
2196 IndentStyle::Block => (
2197 indent.block_indent(context.config),
2198 context.config.trailing_comma(),
2200 IndentStyle::Visual if last_line_ends_with_comment => {
2201 (arg_indent, context.config.trailing_comma())
2203 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2206 let tactic = definitive_tactic(
2208 context.config.fn_args_density().to_list_tactic(),
2212 let budget = match tactic {
2213 DefinitiveListTactic::Horizontal => one_line_budget,
2214 _ => multi_line_budget,
2217 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2219 let fmt = ListFormatting {
2222 trailing_separator: if variadic {
2223 SeparatorTactic::Never
2227 separator_place: SeparatorPlace::Back,
2228 shape: Shape::legacy(budget, indent),
2229 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2230 preserve_newline: true,
2231 config: context.config,
2234 write_list(&arg_items, &fmt)
2237 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2238 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2239 ident.node != symbol::keywords::Invalid.ident()
2245 fn compute_budgets_for_args(
2246 context: &RewriteContext,
2250 newline_brace: bool,
2252 force_vertical_layout: bool,
2253 ) -> Option<((usize, usize, Indent))> {
2255 "compute_budgets_for_args {} {:?}, {}, {}",
2261 // Try keeping everything on the same line.
2262 if !result.contains('\n') && !force_vertical_layout {
2263 // 2 = `()`, 3 = `() `, space is before ret_string.
2264 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2265 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2275 let one_line_budget = context.budget(used_space);
2277 if one_line_budget > 0 {
2279 let (indent, multi_line_budget) = match context.config.indent_style() {
2280 IndentStyle::Block => {
2281 let indent = indent.block_indent(context.config);
2282 (indent, context.budget(indent.width() + 1))
2284 IndentStyle::Visual => {
2285 let indent = indent + result.len() + 1;
2286 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2287 (indent, context.budget(multi_line_overhead))
2291 return Some((one_line_budget, multi_line_budget, indent));
2295 // Didn't work. we must force vertical layout and put args on a newline.
2296 let new_indent = indent.block_indent(context.config);
2297 let used_space = match context.config.indent_style() {
2299 IndentStyle::Block => new_indent.width() + 1,
2300 // Account for `)` and possibly ` {`.
2301 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2303 Some((0, context.budget(used_space), new_indent))
2306 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2307 let predicate_count = where_clause.predicates.len();
2309 if config.where_single_line() && predicate_count == 1 {
2312 let brace_style = config.brace_style();
2314 brace_style == BraceStyle::AlwaysNextLine
2315 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2318 fn rewrite_generics(
2319 context: &RewriteContext,
2320 generics: &ast::Generics,
2323 ) -> Option<String> {
2324 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2325 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2326 rewrite_generics_inner(context, generics, g_shape, one_line_width, span)
2327 .or_else(|| rewrite_generics_inner(context, generics, g_shape, 0, span))
2330 fn rewrite_generics_inner(
2331 context: &RewriteContext,
2332 generics: &ast::Generics,
2334 one_line_width: usize,
2336 ) -> Option<String> {
2337 // FIXME: convert bounds to where clauses where they get too big or if
2338 // there is a where clause at all.
2341 enum GenericsArg<'a> {
2342 Lifetime(&'a ast::LifetimeDef),
2343 TyParam(&'a ast::TyParam),
2345 impl<'a> Rewrite for GenericsArg<'a> {
2346 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2348 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2349 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2353 impl<'a> Spanned for GenericsArg<'a> {
2354 fn span(&self) -> Span {
2356 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2357 GenericsArg::TyParam(ty) => ty.span(),
2362 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2363 return Some(String::new());
2366 let generics_args = generics
2369 .map(|lt| GenericsArg::Lifetime(lt))
2370 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2371 let items = itemize_list(
2376 |arg| arg.span().lo(),
2377 |arg| arg.span().hi(),
2378 |arg| arg.rewrite(context, shape),
2379 context.codemap.span_after(span, "<"),
2383 format_generics_item_list(context, items, shape, one_line_width)
2386 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2387 match config.indent_style() {
2388 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2389 IndentStyle::Block => {
2393 .block_indent(config.tab_spaces())
2394 .with_max_width(config)
2400 pub fn format_generics_item_list<I>(
2401 context: &RewriteContext,
2404 one_line_budget: usize,
2407 I: Iterator<Item = ListItem>,
2409 let item_vec = items.collect::<Vec<_>>();
2411 let tactic = definitive_tactic(
2413 ListTactic::HorizontalVertical,
2417 let fmt = ListFormatting {
2420 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2421 SeparatorTactic::Never
2423 context.config.trailing_comma()
2425 separator_place: SeparatorPlace::Back,
2427 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2428 preserve_newline: true,
2429 config: context.config,
2432 let list_str = write_list(&item_vec, &fmt)?;
2434 Some(wrap_generics_with_angle_brackets(
2441 pub fn wrap_generics_with_angle_brackets(
2442 context: &RewriteContext,
2444 list_offset: Indent,
2446 if context.config.indent_style() == IndentStyle::Block
2447 && (list_str.contains('\n') || list_str.ends_with(','))
2451 list_offset.to_string(context.config),
2454 .block_unindent(context.config)
2455 .to_string(context.config)
2457 } else if context.config.spaces_within_parens_and_brackets() {
2458 format!("< {} >", list_str)
2460 format!("<{}>", list_str)
2464 fn rewrite_trait_bounds(
2465 context: &RewriteContext,
2466 bounds: &[ast::TyParamBound],
2468 ) -> Option<String> {
2469 if bounds.is_empty() {
2470 return Some(String::new());
2472 let bound_str = bounds
2474 .map(|ty_bound| ty_bound.rewrite(context, shape))
2475 .collect::<Option<Vec<_>>>()?;
2476 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2479 fn rewrite_where_clause_rfc_style(
2480 context: &RewriteContext,
2481 where_clause: &ast::WhereClause,
2484 span_end: Option<BytePos>,
2485 span_end_before_where: BytePos,
2486 where_clause_option: WhereClauseOption,
2487 is_args_multi_line: bool,
2488 ) -> Option<String> {
2489 let block_shape = shape.block().with_max_width(context.config);
2491 let (span_before, span_after) =
2492 missing_span_before_after_where(span_end_before_where, where_clause);
2493 let (comment_before, comment_after) =
2494 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2496 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2499 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2502 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2504 let clause_shape = clause_shape.sub_width(1)?;
2505 // each clause on one line, trailing comma (except if suppress_comma)
2506 let span_start = where_clause.predicates[0].span().lo();
2507 // If we don't have the start of the next span, then use the end of the
2508 // predicates, but that means we miss comments.
2509 let len = where_clause.predicates.len();
2510 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2511 let span_end = span_end.unwrap_or(end_of_preds);
2512 let items = itemize_list(
2514 where_clause.predicates.iter(),
2517 |pred| pred.span().lo(),
2518 |pred| pred.span().hi(),
2519 |pred| pred.rewrite(context, clause_shape),
2524 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2525 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2526 SeparatorTactic::Never
2528 context.config.trailing_comma()
2531 // shape should be vertical only and only if we have `where_single_line` option enabled
2532 // and the number of items of the where clause is equal to 1
2533 let shape_tactic = if where_single_line {
2534 DefinitiveListTactic::Horizontal
2536 DefinitiveListTactic::Vertical
2539 let fmt = ListFormatting {
2540 tactic: shape_tactic,
2542 trailing_separator: comma_tactic,
2543 separator_place: SeparatorPlace::Back,
2544 shape: clause_shape,
2545 ends_with_newline: true,
2546 preserve_newline: true,
2547 config: context.config,
2549 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2551 let comment_separator = |comment: &str, shape: Shape| if comment.is_empty() {
2554 format!("\n{}", shape.indent.to_string(context.config))
2556 let newline_before_where = comment_separator(&comment_before, shape);
2557 let newline_after_where = comment_separator(&comment_after, clause_shape);
2560 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2561 && comment_after.is_empty() && !preds_str.contains('\n')
2562 && 6 + preds_str.len() <= shape.width || where_single_line
2566 format!("\n{}", clause_shape.indent.to_string(context.config))
2569 "{}{}{}where{}{}{}{}",
2572 newline_before_where,
2573 newline_after_where,
2580 fn rewrite_where_clause(
2581 context: &RewriteContext,
2582 where_clause: &ast::WhereClause,
2583 brace_style: BraceStyle,
2587 span_end: Option<BytePos>,
2588 span_end_before_where: BytePos,
2589 where_clause_option: WhereClauseOption,
2590 is_args_multi_line: bool,
2591 ) -> Option<String> {
2592 if where_clause.predicates.is_empty() {
2593 return Some(String::new());
2596 if context.config.indent_style() == IndentStyle::Block {
2597 return rewrite_where_clause_rfc_style(
2603 span_end_before_where,
2604 where_clause_option,
2609 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2611 let offset = match context.config.indent_style() {
2612 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2613 // 6 = "where ".len()
2614 IndentStyle::Visual => shape.indent + extra_indent + 6,
2616 // FIXME: if indent_style != Visual, then the budgets below might
2617 // be out by a char or two.
2619 let budget = context.config.max_width() - offset.width();
2620 let span_start = where_clause.predicates[0].span().lo();
2621 // If we don't have the start of the next span, then use the end of the
2622 // predicates, but that means we miss comments.
2623 let len = where_clause.predicates.len();
2624 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2625 let span_end = span_end.unwrap_or(end_of_preds);
2626 let items = itemize_list(
2628 where_clause.predicates.iter(),
2631 |pred| pred.span().lo(),
2632 |pred| pred.span().hi(),
2633 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2638 let item_vec = items.collect::<Vec<_>>();
2639 // FIXME: we don't need to collect here
2640 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2642 let mut comma_tactic = context.config.trailing_comma();
2643 // Kind of a hack because we don't usually have trailing commas in where clauses.
2644 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2645 comma_tactic = SeparatorTactic::Never;
2648 let fmt = ListFormatting {
2651 trailing_separator: comma_tactic,
2652 separator_place: SeparatorPlace::Back,
2653 shape: Shape::legacy(budget, offset),
2654 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2655 preserve_newline: true,
2656 config: context.config,
2658 let preds_str = write_list(&item_vec, &fmt)?;
2660 let end_length = if terminator == "{" {
2661 // If the brace is on the next line we don't need to count it otherwise it needs two
2664 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2665 BraceStyle::PreferSameLine => 2,
2667 } else if terminator == "=" {
2672 if density == Density::Tall || preds_str.contains('\n')
2673 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2677 (shape.indent + extra_indent).to_string(context.config),
2681 Some(format!(" where {}", preds_str))
2685 fn missing_span_before_after_where(
2686 before_item_span_end: BytePos,
2687 where_clause: &ast::WhereClause,
2689 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2691 let pos_after_where = where_clause.span.lo() + BytePos(5);
2692 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2693 (missing_span_before, missing_span_after)
2696 fn rewrite_comments_before_after_where(
2697 context: &RewriteContext,
2698 span_before_where: Span,
2699 span_after_where: Span,
2701 ) -> Option<(String, String)> {
2702 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2703 let after_comment = rewrite_missing_comment(
2705 shape.block_indent(context.config.tab_spaces()),
2708 Some((before_comment, after_comment))
2711 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2712 format!("{}{}{}", format_visibility(vis), item_name, ident)
2715 #[derive(PartialEq, Eq)]
2723 context: &RewriteContext,
2724 generics: &ast::Generics,
2725 brace_style: BraceStyle,
2726 brace_pos: BracePos,
2730 ) -> Option<String> {
2731 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2732 let mut result = rewrite_generics(context, generics, shape, span)?;
2734 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2735 let budget = context.budget(last_line_used_width(&result, offset.width()));
2736 let mut option = WhereClauseOption::snuggled(&result);
2737 if brace_pos == BracePos::None {
2738 option.suppress_comma = true;
2740 // If the generics are not parameterized then generics.span.hi() == 0,
2741 // so we use span.lo(), which is the position after `struct Foo`.
2742 let span_end_before_where = if generics.is_parameterized() {
2747 let where_clause_str = rewrite_where_clause(
2749 &generics.where_clause,
2751 Shape::legacy(budget, offset.block_only()),
2755 span_end_before_where,
2759 result.push_str(&where_clause_str);
2760 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2761 || (generics.where_clause.predicates.is_empty()
2762 && trimmed_last_line_width(&result) == 1)
2764 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2765 || brace_style != BraceStyle::AlwaysNextLine
2767 if brace_pos == BracePos::None {
2768 return Some(result);
2770 let total_used_width = last_line_used_width(&result, used_width);
2771 let remaining_budget = context.budget(total_used_width);
2772 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2773 // and hence we take the closer into account as well for one line budget.
2774 // We assume that the closer has the same length as the opener.
2775 let overhead = if brace_pos == BracePos::ForceSameLine {
2782 let forbid_same_line_brace = overhead > remaining_budget;
2783 if !forbid_same_line_brace && same_line_brace {
2787 result.push_str(&offset.block_only().to_string(context.config));
2794 impl Rewrite for ast::ForeignItem {
2795 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2796 let attrs_str = self.attrs.rewrite(context, shape)?;
2797 // Drop semicolon or it will be interpreted as comment.
2798 // FIXME: this may be a faulty span from libsyntax.
2799 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2801 let item_str = match self.node {
2802 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2807 &FnSig::new(fn_decl, generics, self.vis.clone()),
2811 ).map(|(s, _)| format!("{};", s))
2813 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2814 // FIXME(#21): we're dropping potential comments in between the
2815 // function keywords here.
2816 let vis = format_visibility(&self.vis);
2817 let mut_str = if is_mutable { "mut " } else { "" };
2818 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2820 let shape = shape.sub_width(1)?;
2821 ty.rewrite(context, shape).map(|ty_str| {
2822 // 1 = space between prefix and type.
2823 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2826 let nested_indent = shape.indent.block_indent(context.config);
2827 format!("\n{}", nested_indent.to_string(context.config))
2829 format!("{}{}{};", prefix, sep, ty_str)
2832 ast::ForeignItemKind::Ty => {
2833 let vis = format_visibility(&self.vis);
2834 Some(format!("{}type {};", vis, self.ident))
2838 let missing_span = if self.attrs.is_empty() {
2839 mk_sp(self.span.lo(), self.span.lo())
2841 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2843 combine_strs_with_missing_comments(