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 {:?} {} {:?}",
56 skip_out_of_file_lines_range!(context, self.span);
58 if contains_skip(&self.attrs) {
62 let attrs_str = self.attrs.rewrite(context, shape)?;
63 let mut result = if attrs_str.is_empty() {
66 combine_strs_with_missing_comments(
71 self.attrs.last().map(|a| a.span.hi()).unwrap(),
80 let pat_shape = shape.offset_left(4)?;
82 let pat_shape = pat_shape.sub_width(1)?;
83 let pat_str = self.pat.rewrite(context, pat_shape)?;
84 result.push_str(&pat_str);
86 // String that is placed within the assignment pattern and expression.
88 let mut infix = String::with_capacity(32);
90 if let Some(ref ty) = self.ty {
91 let separator = type_annotation_separator(context.config);
92 let indent = shape.indent + last_line_width(&result) + separator.len();
94 let budget = shape.width.checked_sub(indent.width() + 1)?;
95 let rewrite = ty.rewrite(context, Shape::legacy(budget, indent))?;
97 infix.push_str(separator);
98 infix.push_str(&rewrite);
101 if self.init.is_some() {
102 infix.push_str(" =");
108 result.push_str(&infix);
110 if let Some(ref ex) = self.init {
111 // 1 = trailing semicolon;
112 let nested_shape = shape.sub_width(1)?;
114 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
122 // TODO convert to using rewrite style rather than visitor
123 // TODO format modules in this style
126 keyword: &'static str,
127 abi: Cow<'static, str>,
128 vis: Option<&'a ast::Visibility>,
129 body: Vec<BodyElement<'a>>,
134 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
137 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
141 .map(|i| BodyElement::ForeignItem(i))
148 enum BodyElement<'a> {
149 // Stmt(&'a ast::Stmt),
150 // Field(&'a ast::Field),
151 // Variant(&'a ast::Variant),
152 // Item(&'a ast::Item),
153 ForeignItem(&'a ast::ForeignItem),
156 /// Represents a fn's signature.
157 pub struct FnSig<'a> {
158 decl: &'a ast::FnDecl,
159 generics: &'a ast::Generics,
161 constness: ast::Constness,
162 defaultness: ast::Defaultness,
163 unsafety: ast::Unsafety,
164 visibility: ast::Visibility,
169 decl: &'a ast::FnDecl,
170 generics: &'a ast::Generics,
171 vis: ast::Visibility,
177 constness: ast::Constness::NotConst,
178 defaultness: ast::Defaultness::Final,
179 unsafety: ast::Unsafety::Normal,
184 pub fn from_method_sig(
185 method_sig: &'a ast::MethodSig,
186 generics: &'a ast::Generics,
189 unsafety: method_sig.unsafety,
190 constness: method_sig.constness.node,
191 defaultness: ast::Defaultness::Final,
193 decl: &*method_sig.decl,
195 visibility: ast::Visibility::Inherited,
200 fn_kind: &'a visit::FnKind,
201 generics: &'a ast::Generics,
202 decl: &'a ast::FnDecl,
203 defualtness: ast::Defaultness,
206 visit::FnKind::ItemFn(_, unsafety, constness, abi, visibility, _) => FnSig {
210 constness: constness.node,
211 defaultness: defualtness,
213 visibility: visibility.clone(),
215 visit::FnKind::Method(_, method_sig, vis, _) => {
216 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
217 fn_sig.defaultness = defualtness;
218 if let Some(vis) = vis {
219 fn_sig.visibility = vis.clone();
227 fn to_str(&self, context: &RewriteContext) -> String {
228 let mut result = String::with_capacity(128);
229 // Vis defaultness constness unsafety abi.
230 result.push_str(&*format_visibility(&self.visibility));
231 result.push_str(format_defaultness(self.defaultness));
232 result.push_str(format_constness(self.constness));
233 result.push_str(format_unsafety(self.unsafety));
234 result.push_str(&format_abi(
236 context.config.force_explicit_abi(),
243 impl<'a> FmtVisitor<'a> {
244 fn format_item(&mut self, item: Item) {
245 self.buffer.push_str(&item.abi);
247 let snippet = self.snippet(item.span);
248 let brace_pos = snippet.find_uncommented("{").unwrap();
250 self.buffer.push_str("{");
251 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
252 // FIXME: this skips comments between the extern keyword and the opening
254 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
255 self.block_indent = self.block_indent.block_indent(self.config);
257 if item.body.is_empty() {
258 self.format_missing_no_indent(item.span.hi() - BytePos(1));
259 self.block_indent = self.block_indent.block_unindent(self.config);
262 .push_str(&self.block_indent.to_string(self.config));
264 for item in &item.body {
265 self.format_body_element(item);
268 self.block_indent = self.block_indent.block_unindent(self.config);
269 self.format_missing_with_indent(item.span.hi() - BytePos(1));
273 self.buffer.push_str("}");
274 self.last_pos = item.span.hi();
277 fn format_body_element(&mut self, element: &BodyElement) {
279 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
283 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
284 let item = Item::from_foreign_mod(fm, span, self.config);
285 self.format_item(item);
288 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
289 let rewrite = item.rewrite(&self.get_context(), self.shape());
290 self.push_rewrite(item.span(), rewrite);
291 self.last_pos = item.span.hi();
301 ) -> Option<String> {
302 let context = self.get_context();
304 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
306 let (mut result, force_newline_brace) =
307 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
310 if self.config.brace_style() == BraceStyle::AlwaysNextLine || force_newline_brace
311 || last_line_width(&result) + 2 > self.shape().width
313 newline_brace = true;
314 } else if !result.contains('\n') {
315 newline_brace = false;
318 // Prepare for the function body by possibly adding a newline and
320 // FIXME we'll miss anything between the end of the signature and the
321 // start of the body, but we need more spans from the compiler to solve
325 result.push_str(&indent.to_string(self.config));
330 self.single_line_fn(&result, block).or_else(|| Some(result))
333 pub fn rewrite_required_fn(
337 sig: &ast::MethodSig,
338 generics: &ast::Generics,
340 ) -> Option<String> {
341 // Drop semicolon or it will be interpreted as comment.
342 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
343 let context = self.get_context();
345 let (mut result, _) = rewrite_fn_base(
349 &FnSig::from_method_sig(sig, generics),
355 // Re-attach semicolon
361 fn single_line_fn(&self, fn_str: &str, block: &ast::Block) -> Option<String> {
362 if fn_str.contains('\n') {
366 let codemap = self.get_context().codemap;
368 if self.config.empty_item_single_line() && is_empty_block(block, codemap)
369 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
371 return Some(format!("{}{{}}", fn_str));
374 if self.config.fn_single_line() && is_simple_block_stmt(block, codemap) {
376 if let Some(stmt) = block.stmts.first() {
377 match stmt_expr(stmt) {
379 let suffix = if semicolon_for_expr(&self.get_context(), e) {
385 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
387 .or_else(|| Some(self.snippet(e.span)))
389 None => stmt.rewrite(&self.get_context(), self.shape()),
396 if let Some(res) = rewrite {
397 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
398 if !res.contains('\n') && width <= self.config.max_width() {
399 return Some(format!("{}{{ {} }}", fn_str, res));
407 pub fn visit_static(&mut self, static_parts: &StaticParts) {
408 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
409 self.push_rewrite(static_parts.span, rewrite);
412 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
413 let is_tuple = struct_parts.def.is_tuple();
414 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
415 .map(|s| if is_tuple { s + ";" } else { s });
416 self.push_rewrite(struct_parts.span, rewrite);
422 vis: &ast::Visibility,
423 enum_def: &ast::EnumDef,
424 generics: &ast::Generics,
427 let enum_header = format_header("enum ", ident, vis);
428 self.buffer.push_str(&enum_header);
430 let enum_snippet = self.snippet(span);
431 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
432 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
433 let generics_str = format_generics(
436 self.config.brace_style(),
437 if enum_def.variants.is_empty() {
438 BracePos::ForceSameLine
443 mk_sp(span.lo(), body_start),
444 last_line_width(&enum_header),
446 self.buffer.push_str(&generics_str);
448 self.last_pos = body_start;
450 self.block_indent = self.block_indent.block_indent(self.config);
451 let variant_list = self.format_variant_list(enum_def, body_start, span.hi() - BytePos(1));
453 Some(ref body_str) => self.buffer.push_str(body_str),
454 None => self.format_missing_no_indent(span.hi() - BytePos(1)),
456 self.block_indent = self.block_indent.block_unindent(self.config);
458 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
460 .push_str(&self.block_indent.to_string(self.config));
462 self.buffer.push_str("}");
463 self.last_pos = span.hi();
466 // Format the body of an enum definition
467 fn format_variant_list(
469 enum_def: &ast::EnumDef,
472 ) -> Option<String> {
473 if enum_def.variants.is_empty() {
476 let mut result = String::with_capacity(1024);
478 let indentation = self.block_indent.to_string(self.config);
479 result.push_str(&indentation);
481 let itemize_list_with = |one_line_width: usize| {
484 enum_def.variants.iter(),
487 |f| if !f.node.attrs.is_empty() {
488 f.node.attrs[0].span.lo()
493 |f| self.format_variant(f, one_line_width),
499 let mut items: Vec<_> =
500 itemize_list_with(self.config.width_heuristics().struct_variant_width);
501 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
502 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
503 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
504 if has_multiline_variant && has_single_line_variant {
505 items = itemize_list_with(0);
508 let shape = self.shape().sub_width(2).unwrap();
509 let fmt = ListFormatting {
510 tactic: DefinitiveListTactic::Vertical,
512 trailing_separator: self.config.trailing_comma(),
513 separator_place: SeparatorPlace::Back,
515 ends_with_newline: true,
516 preserve_newline: true,
520 let list = write_list(&items, &fmt)?;
521 result.push_str(&list);
526 // Variant of an enum.
527 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
528 if contains_skip(&field.node.attrs) {
529 let lo = field.node.attrs[0].span.lo();
530 let span = mk_sp(lo, field.span.hi());
531 return Some(self.snippet(span));
534 let context = self.get_context();
536 let shape = self.shape().sub_width(1)?;
537 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
542 .map_or(field.span.lo(), |attr| attr.span.hi());
543 let span = mk_sp(lo, field.span.lo());
545 let variant_body = match field.node.data {
546 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
548 &StructParts::from_variant(field),
550 Some(one_line_width),
552 ast::VariantData::Unit(..) => {
553 if let Some(ref expr) = field.node.disr_expr {
554 let lhs = format!("{} =", field.node.name);
555 rewrite_assign_rhs(&context, lhs, &**expr, shape)?
557 field.node.name.to_string()
562 let attrs_extendable = attrs_str.is_empty()
563 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
564 combine_strs_with_missing_comments(
576 context: &RewriteContext,
579 where_span_end: Option<BytePos>,
580 ) -> Option<String> {
581 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
582 let mut result = String::with_capacity(128);
583 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
584 let indent_str = offset.to_string(context.config);
585 let sep = format!("\n{}", &indent_str);
586 result.push_str(&ref_and_type);
588 let where_budget = if result.contains('\n') {
589 context.config.max_width()
591 context.budget(last_line_width(&result))
593 let option = WhereClauseOption::snuggled(&ref_and_type);
594 let where_clause_str = rewrite_where_clause(
596 &generics.where_clause,
597 context.config.brace_style(),
598 Shape::legacy(where_budget, offset.block_only()),
607 // If there is no where clause, we may have missing comments between the trait name and
608 // the opening brace.
609 if generics.where_clause.predicates.is_empty() {
610 if let Some(hi) = where_span_end {
611 match recover_missing_comment_in_span(
612 mk_sp(self_ty.span.hi(), hi),
613 Shape::indented(offset, context.config),
615 last_line_width(&result),
617 Some(ref missing_comment) if !missing_comment.is_empty() => {
618 result.push_str(missing_comment);
625 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
626 result.push_str(&where_clause_str);
627 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
628 result.push_str(&format!("{}{{{}}}", &sep, &sep));
630 result.push_str(" {}");
635 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
637 let width = offset.block_indent + context.config.tab_spaces() - 1;
638 let where_indent = Indent::new(0, width);
639 result.push_str(&where_indent.to_string(context.config));
641 result.push_str(&where_clause_str);
643 match context.config.brace_style() {
644 _ if last_line_contains_single_line_comment(&result) => result.push_str(&sep),
645 BraceStyle::AlwaysNextLine => result.push_str(&sep),
646 BraceStyle::PreferSameLine => result.push(' '),
647 BraceStyle::SameLineWhere => {
648 if !where_clause_str.is_empty() {
649 result.push_str(&sep);
658 let snippet = context.snippet(item.span);
659 let open_pos = snippet.find_uncommented("{")? + 1;
661 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
662 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
663 visitor.block_indent = offset.block_only().block_indent(context.config);
664 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
666 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
668 visitor.visit_impl_item(item);
671 visitor.format_missing(item.span.hi() - BytePos(1));
673 let inner_indent_str = visitor.block_indent.to_string(context.config);
674 let outer_indent_str = offset.block_only().to_string(context.config);
677 result.push_str(&inner_indent_str);
678 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
680 result.push_str(&outer_indent_str);
683 if result.ends_with('{') {
684 result.push_str(&sep);
694 fn is_impl_single_line(
695 context: &RewriteContext,
698 where_clause_str: &str,
701 let snippet = context.snippet(item.span);
702 let open_pos = snippet.find_uncommented("{")? + 1;
705 context.config.empty_item_single_line() && items.is_empty() && !result.contains('\n')
706 && result.len() + where_clause_str.len() <= context.config.max_width()
707 && !contains_comment(&snippet[open_pos..]),
711 fn format_impl_ref_and_type(
712 context: &RewriteContext,
715 ) -> Option<String> {
716 if let ast::ItemKind::Impl(
726 let mut result = String::with_capacity(128);
728 result.push_str(&format_visibility(&item.vis));
729 result.push_str(format_defaultness(defaultness));
730 result.push_str(format_unsafety(unsafety));
731 result.push_str("impl");
733 let lo = context.codemap.span_after(item.span, "impl");
734 let hi = match *trait_ref {
735 Some(ref tr) => tr.path.span.lo(),
736 None => self_ty.span.lo(),
738 let shape = generics_shape_from_config(
740 Shape::indented(offset + last_line_width(&result), context.config),
743 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
745 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
747 let polarity_str = if polarity == ast::ImplPolarity::Negative {
753 if let Some(ref trait_ref) = *trait_ref {
754 let result_len = result.len();
755 if let Some(trait_ref_str) = rewrite_trait_ref(
764 result.push_str(&trait_ref_str);
767 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
768 result.push_str(&rewrite_trait_ref(
779 result.push_str(&generics_str);
782 // Try to put the self type in a single line.
784 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
785 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
786 // If there is no where clause adapt budget for type formatting to take space and curly
787 // brace into account.
788 match context.config.brace_style() {
789 BraceStyle::AlwaysNextLine => 0,
795 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
796 // 1 = space before the type.
797 let budget = context.budget(used_space + 1);
798 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
799 if !self_ty_str.contains('\n') {
800 if trait_ref.is_some() {
801 result.push_str(" for ");
805 result.push_str(&self_ty_str);
810 // Couldn't fit the self type on a single line, put it on a new line.
812 // Add indentation of one additional tab.
813 let new_line_offset = offset.block_indent(context.config);
814 result.push_str(&new_line_offset.to_string(context.config));
815 if trait_ref.is_some() {
816 result.push_str("for ");
818 let budget = context.budget(last_line_width(&result));
819 let type_offset = match context.config.indent_style() {
820 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
821 IndentStyle::Block => new_line_offset,
823 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
830 fn rewrite_trait_ref(
831 context: &RewriteContext,
832 trait_ref: &ast::TraitRef,
838 ) -> Option<String> {
839 // 1 = space between generics and trait_ref
840 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
841 let shape = Shape::indented(offset + used_space, context.config);
842 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
843 if !(retry && trait_ref_str.contains('\n')) {
852 // We could not make enough space for trait_ref, so put it on new line.
854 let offset = offset.block_indent(context.config);
855 let shape = Shape::indented(offset, context.config);
856 let trait_ref_str = trait_ref.rewrite(context, shape)?;
860 &offset.to_string(context.config),
869 pub struct StructParts<'a> {
872 vis: &'a ast::Visibility,
873 def: &'a ast::VariantData,
874 generics: Option<&'a ast::Generics>,
878 impl<'a> StructParts<'a> {
879 fn format_header(&self) -> String {
880 format_header(self.prefix, self.ident, self.vis)
883 fn from_variant(variant: &'a ast::Variant) -> Self {
886 ident: variant.node.name,
887 vis: &ast::Visibility::Inherited,
888 def: &variant.node.data,
894 pub fn from_item(item: &'a ast::Item) -> Self {
895 let (prefix, def, generics) = match item.node {
896 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
897 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
905 generics: Some(generics),
912 context: &RewriteContext,
913 struct_parts: &StructParts,
915 one_line_width: Option<usize>,
916 ) -> Option<String> {
917 match *struct_parts.def {
918 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
919 ast::VariantData::Tuple(ref fields, _) => {
920 format_tuple_struct(context, struct_parts, fields, offset)
922 ast::VariantData::Struct(ref fields, _) => {
923 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
928 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
929 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
932 let mut result = String::with_capacity(128);
933 let header = format!(
935 format_visibility(&item.vis),
936 format_unsafety(unsafety),
940 result.push_str(&header);
942 let body_lo = context.codemap.span_after(item.span, "{");
944 let shape = Shape::indented(offset, context.config);
946 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
947 result.push_str(&generics_str);
949 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
950 if !type_param_bounds.is_empty() {
951 let ident_hi = context.codemap.span_after(item.span, &format!("{}", item.ident));
952 let bound_hi = type_param_bounds.last().unwrap().span().hi();
953 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
954 if contains_comment(&snippet) {
958 let trait_bound_str = rewrite_trait_bounds(
961 Shape::indented(offset, context.config),
963 // If the trait, generics, and trait bound cannot fit on the same line,
964 // put the trait bounds on an indented new line
965 if offset.width() + last_line_width(&result) + trait_bound_str.len()
966 > context.config.comment_width()
969 let trait_indent = offset.block_only().block_indent(context.config);
970 result.push_str(&trait_indent.to_string(context.config));
972 result.push_str(&trait_bound_str);
975 if context.config.indent_style() == IndentStyle::Block && result.is_empty() {
981 let where_budget = context.budget(last_line_width(&result));
982 let pos_before_where = if type_param_bounds.is_empty() {
983 generics.where_clause.span.lo()
985 type_param_bounds[type_param_bounds.len() - 1].span().hi()
987 let option = WhereClauseOption::snuggled(&generics_str);
988 let where_clause_str = rewrite_where_clause(
990 &generics.where_clause,
991 context.config.brace_style(),
992 Shape::legacy(where_budget, offset.block_only()),
1000 // If the where clause cannot fit on the same line,
1001 // put the where clause on a new line
1002 if !where_clause_str.contains('\n')
1003 && last_line_width(&result) + where_clause_str.len() + offset.width()
1004 > context.config.comment_width()
1007 let width = offset.block_indent + context.config.tab_spaces() - 1;
1008 let where_indent = Indent::new(0, width);
1009 result.push_str(&where_indent.to_string(context.config));
1011 result.push_str(&where_clause_str);
1013 if generics.where_clause.predicates.is_empty() {
1014 let item_snippet = context.snippet(item.span);
1015 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1017 let comment_hi = body_lo - BytePos(1);
1018 let comment_lo = item.span.lo() + BytePos(lo as u32);
1019 if comment_lo < comment_hi {
1020 match recover_missing_comment_in_span(
1021 mk_sp(comment_lo, comment_hi),
1022 Shape::indented(offset, context.config),
1024 last_line_width(&result),
1026 Some(ref missing_comment) if !missing_comment.is_empty() => {
1027 result.push_str(missing_comment);
1035 match context.config.brace_style() {
1036 _ if last_line_contains_single_line_comment(&result) => {
1038 result.push_str(&offset.to_string(context.config));
1040 BraceStyle::AlwaysNextLine => {
1042 result.push_str(&offset.to_string(context.config));
1044 BraceStyle::PreferSameLine => result.push(' '),
1045 BraceStyle::SameLineWhere => {
1046 if !where_clause_str.is_empty()
1047 && (!trait_items.is_empty() || result.contains('\n'))
1050 result.push_str(&offset.to_string(context.config));
1058 let snippet = context.snippet(item.span);
1059 let open_pos = snippet.find_uncommented("{")? + 1;
1061 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1062 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
1063 visitor.block_indent = offset.block_only().block_indent(context.config);
1064 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1066 for item in trait_items {
1067 visitor.visit_trait_item(item);
1070 visitor.format_missing(item.span.hi() - BytePos(1));
1072 let inner_indent_str = visitor.block_indent.to_string(context.config);
1073 let outer_indent_str = offset.block_only().to_string(context.config);
1076 result.push_str(&inner_indent_str);
1077 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1079 result.push_str(&outer_indent_str);
1080 } else if result.contains('\n') {
1091 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1092 let header_str = format_header(p.prefix, p.ident, p.vis);
1093 let generics_str = if let Some(generics) = p.generics {
1094 let hi = if generics.where_clause.predicates.is_empty() {
1097 generics.where_clause.span.hi()
1102 context.config.brace_style(),
1105 mk_sp(generics.span.lo(), hi),
1106 last_line_width(&header_str),
1111 Some(format!("{}{};", header_str, generics_str))
1114 pub fn format_struct_struct(
1115 context: &RewriteContext,
1116 struct_parts: &StructParts,
1117 fields: &[ast::StructField],
1119 one_line_width: Option<usize>,
1120 ) -> Option<String> {
1121 let mut result = String::with_capacity(1024);
1122 let span = struct_parts.span;
1124 let header_str = struct_parts.format_header();
1125 result.push_str(&header_str);
1127 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1128 let body_lo = context.codemap.span_after(span, "{");
1130 let generics_str = match struct_parts.generics {
1131 Some(g) => format_generics(
1134 context.config.brace_style(),
1135 if fields.is_empty() {
1136 BracePos::ForceSameLine
1141 mk_sp(header_hi, body_lo),
1142 last_line_width(&result),
1145 // 3 = ` {}`, 2 = ` {`.
1146 let overhead = if fields.is_empty() { 3 } else { 2 };
1147 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1148 || context.config.max_width() < overhead + result.len()
1150 format!("\n{}{{", offset.block_only().to_string(context.config))
1157 let overhead = if fields.is_empty() { 1 } else { 0 };
1158 let total_width = result.len() + generics_str.len() + overhead;
1159 if !generics_str.is_empty() && !generics_str.contains('\n')
1160 && total_width > context.config.max_width()
1163 result.push_str(&offset.to_string(context.config));
1164 result.push_str(generics_str.trim_left());
1166 result.push_str(&generics_str);
1169 if fields.is_empty() {
1170 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1171 if snippet.trim().is_empty() {
1173 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1175 result.push_str(snippet.trim_right());
1177 result.push_str(&offset.to_string(context.config));
1179 result.push_str(&snippet);
1182 return Some(result);
1186 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1187 let one_line_budget =
1188 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1190 let items_str = rewrite_with_alignment(
1193 Shape::indented(offset, context.config).sub_width(1)?,
1194 mk_sp(body_lo, span.hi()),
1198 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget {
1199 Some(format!("{} {} }}", result, items_str))
1205 .block_indent(context.config)
1206 .to_string(context.config),
1208 offset.to_string(context.config)
1213 /// Returns a bytepos that is after that of `(` in `pub(..)`. If the given visibility does not
1214 /// contain `pub(..)`, then return the `lo` of the `defualt_span`. Yeah, but for what? Well, we need
1215 /// to bypass the `(` in the visibility when creating a span of tuple's body or fn's args.
1216 fn get_bytepos_after_visibility(
1217 context: &RewriteContext,
1218 vis: &ast::Visibility,
1223 ast::Visibility::Crate(s, CrateSugar::PubCrate) => context
1225 .span_after(mk_sp(s.hi(), default_span.hi()), terminator),
1226 ast::Visibility::Crate(s, CrateSugar::JustCrate) => s.hi(),
1227 ast::Visibility::Restricted { ref path, .. } => path.span.hi(),
1228 _ => default_span.lo(),
1232 fn format_tuple_struct(
1233 context: &RewriteContext,
1234 struct_parts: &StructParts,
1235 fields: &[ast::StructField],
1237 ) -> Option<String> {
1238 let mut result = String::with_capacity(1024);
1239 let span = struct_parts.span;
1241 let header_str = struct_parts.format_header();
1242 result.push_str(&header_str);
1244 let body_lo = if fields.is_empty() {
1245 let lo = get_bytepos_after_visibility(context, struct_parts.vis, span, ")");
1246 context.codemap.span_after(mk_sp(lo, span.hi()), "(")
1250 let body_hi = if fields.is_empty() {
1251 context.codemap.span_after(mk_sp(body_lo, span.hi()), ")")
1253 // This is a dirty hack to work around a missing `)` from the span of the last field.
1254 let last_arg_span = fields[fields.len() - 1].span;
1255 if context.snippet(last_arg_span).ends_with(')') {
1260 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1264 let where_clause_str = match struct_parts.generics {
1266 let budget = context.budget(last_line_width(&header_str));
1267 let shape = Shape::legacy(budget, offset);
1268 let g_span = mk_sp(span.lo(), body_lo);
1269 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1270 result.push_str(&generics_str);
1272 let where_budget = context.budget(last_line_width(&result));
1273 let option = WhereClauseOption::new(true, false);
1274 rewrite_where_clause(
1276 &generics.where_clause,
1277 context.config.brace_style(),
1278 Shape::legacy(where_budget, offset.block_only()),
1279 Density::Compressed,
1287 None => "".to_owned(),
1290 if fields.is_empty() {
1292 let used_width = last_line_used_width(&result, offset.width()) + 3;
1293 if used_width > context.config.max_width() {
1295 result.push_str(&offset
1296 .block_indent(context.config)
1297 .to_string(context.config))
1300 let snippet = context.snippet(mk_sp(
1302 context.codemap.span_before(mk_sp(body_lo, span.hi()), ")"),
1304 if snippet.is_empty() {
1306 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1307 result.push_str(snippet.trim_right());
1309 result.push_str(&offset.to_string(context.config));
1311 result.push_str(&snippet);
1315 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1316 let fields = &fields.iter().collect::<Vec<_>>()[..];
1317 let one_line_width = context.config.width_heuristics().fn_call_width;
1318 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1321 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1322 && (result.contains('\n')
1323 || offset.block_indent + result.len() + where_clause_str.len() + 1
1324 > context.config.max_width())
1326 // We need to put the where clause on a new line, but we didn't
1327 // know that earlier, so the where clause will not be indented properly.
1329 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1330 .to_string(context.config));
1332 result.push_str(&where_clause_str);
1337 pub fn rewrite_type_alias(
1338 context: &RewriteContext,
1342 generics: &ast::Generics,
1343 vis: &ast::Visibility,
1345 ) -> Option<String> {
1346 let mut result = String::with_capacity(128);
1348 result.push_str(&format_visibility(vis));
1349 result.push_str("type ");
1350 result.push_str(&ident.to_string());
1353 let shape = Shape::indented(indent + result.len(), context.config).sub_width(2)?;
1354 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo());
1355 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1356 result.push_str(&generics_str);
1358 let where_budget = context.budget(last_line_width(&result));
1359 let option = WhereClauseOption::snuggled(&result);
1360 let where_clause_str = rewrite_where_clause(
1362 &generics.where_clause,
1363 context.config.brace_style(),
1364 Shape::legacy(where_budget, indent),
1372 result.push_str(&where_clause_str);
1373 if where_clause_str.is_empty() {
1374 result.push_str(" = ");
1376 result.push_str(&format!("\n{}= ", indent.to_string(context.config)));
1379 let line_width = last_line_width(&result);
1380 // This checked_sub may fail as the extra space after '=' is not taken into account
1381 // In that case the budget is set to 0 which will make ty.rewrite retry on a new line
1382 let budget = context.budget(indent.width() + line_width + ";".len());
1383 let type_indent = indent + line_width;
1384 // Try to fit the type on the same line
1385 let ty_str = ty.rewrite(context, Shape::legacy(budget, type_indent))
1387 // The line was too short, try to put the type on the next line
1389 // Remove the space after '='
1391 let type_indent = indent.block_indent(context.config);
1393 result.push_str(&type_indent.to_string(context.config));
1394 let budget = context.budget(type_indent.width() + ";".len());
1395 ty.rewrite(context, Shape::legacy(budget, type_indent))
1397 result.push_str(&ty_str);
1398 result.push_str(";");
1402 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1404 if config.space_before_colon() { " " } else { "" },
1405 if config.space_after_colon() { " " } else { "" },
1409 pub fn rewrite_struct_field_prefix(
1410 context: &RewriteContext,
1411 field: &ast::StructField,
1412 ) -> Option<String> {
1413 let vis = format_visibility(&field.vis);
1414 let type_annotation_spacing = type_annotation_spacing(context.config);
1415 Some(match field.ident {
1416 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1417 None => format!("{}", vis),
1421 impl Rewrite for ast::StructField {
1422 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1423 rewrite_struct_field(context, self, shape, 0)
1427 pub fn rewrite_struct_field(
1428 context: &RewriteContext,
1429 field: &ast::StructField,
1431 lhs_max_width: usize,
1432 ) -> Option<String> {
1433 if contains_skip(&field.attrs) {
1434 return Some(context.snippet(mk_sp(field.attrs[0].span.lo(), field.span.hi())));
1437 let type_annotation_spacing = type_annotation_spacing(context.config);
1438 let prefix = rewrite_struct_field_prefix(context, field)?;
1440 let attrs_str = field.attrs.rewrite(context, shape)?;
1441 let attrs_extendable = attrs_str.is_empty()
1442 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
1443 let missing_span = if field.attrs.is_empty() {
1444 mk_sp(field.span.lo(), field.span.lo())
1446 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1448 let mut spacing = String::from(if field.ident.is_some() {
1449 type_annotation_spacing.1
1453 // Try to put everything on a single line.
1454 let attr_prefix = combine_strs_with_missing_comments(
1462 let overhead = last_line_width(&attr_prefix);
1463 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1464 for _ in 0..lhs_offset {
1467 // In this extreme case we will be missing a space betweeen an attribute and a field.
1468 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1471 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1472 let mut orig_ty = field.ty.rewrite(context, ty_shape);
1473 if let Some(ref ty) = orig_ty {
1474 if !ty.contains('\n') {
1475 return Some(attr_prefix + &spacing + ty);
1479 // We must use multiline. We are going to put attributes and a field on different lines.
1481 let rhs_shape = shape.offset_left(last_line_width(&prefix) + 1)?;
1482 orig_ty = field.ty.rewrite(context, rhs_shape);
1483 let field_str = if prefix.is_empty() {
1486 prefix + &choose_rhs(context, &*field.ty, rhs_shape, orig_ty)?
1488 combine_strs_with_missing_comments(context, &attrs_str, &field_str, missing_span, shape, false)
1491 pub struct StaticParts<'a> {
1493 vis: &'a ast::Visibility,
1496 mutability: ast::Mutability,
1497 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1498 defaultness: Option<ast::Defaultness>,
1502 impl<'a> StaticParts<'a> {
1503 pub fn from_item(item: &'a ast::Item) -> Self {
1504 let (prefix, ty, mutability, expr) = match item.node {
1505 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1506 ast::ItemKind::Const(ref ty, ref expr) => {
1507 ("const", ty, ast::Mutability::Immutable, expr)
1509 _ => unreachable!(),
1516 mutability: mutability,
1517 expr_opt: Some(expr),
1523 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1524 let (ty, expr_opt) = match ti.node {
1525 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1526 _ => unreachable!(),
1530 vis: &ast::Visibility::Inherited,
1533 mutability: ast::Mutability::Immutable,
1534 expr_opt: expr_opt.as_ref(),
1540 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1541 let (ty, expr) = match ii.node {
1542 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1543 _ => unreachable!(),
1550 mutability: ast::Mutability::Immutable,
1551 expr_opt: Some(expr),
1552 defaultness: Some(ii.defaultness),
1559 context: &RewriteContext,
1560 static_parts: &StaticParts,
1562 ) -> Option<String> {
1563 let colon = colon_spaces(
1564 context.config.space_before_colon(),
1565 context.config.space_after_colon(),
1567 let prefix = format!(
1569 format_visibility(static_parts.vis),
1570 static_parts.defaultness.map_or("", format_defaultness),
1571 static_parts.prefix,
1572 format_mutability(static_parts.mutability),
1578 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1579 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1581 if let Some(expr) = static_parts.expr_opt {
1582 let lhs = format!("{}{} =", prefix, ty_str);
1584 let remaining_width = context.budget(offset.block_indent + 1);
1589 Shape::legacy(remaining_width, offset.block_only()),
1590 ).and_then(|res| recover_comment_removed(res, static_parts.span, context))
1591 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1593 Some(format!("{}{};", prefix, ty_str))
1597 pub fn rewrite_associated_type(
1599 ty_opt: Option<&ptr::P<ast::Ty>>,
1600 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1601 context: &RewriteContext,
1603 ) -> Option<String> {
1604 let prefix = format!("type {}", ident);
1606 let type_bounds_str = if let Some(bounds) = ty_param_bounds_opt {
1608 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1609 let bound_str = bounds
1611 .map(|ty_bound| ty_bound.rewrite(context, shape))
1612 .collect::<Option<Vec<_>>>()?;
1613 if !bounds.is_empty() {
1614 format!(": {}", join_bounds(context, shape, &bound_str))
1622 if let Some(ty) = ty_opt {
1624 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1625 let lhs = format!("{}{} =", prefix, type_bounds_str);
1626 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1628 Some(format!("{}{};", prefix, type_bounds_str))
1632 pub fn rewrite_associated_impl_type(
1634 defaultness: ast::Defaultness,
1635 ty_opt: Option<&ptr::P<ast::Ty>>,
1636 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1637 context: &RewriteContext,
1639 ) -> Option<String> {
1640 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1643 ast::Defaultness::Default => Some(format!("default {}", result)),
1648 impl Rewrite for ast::FunctionRetTy {
1649 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1651 ast::FunctionRetTy::Default(_) => Some(String::new()),
1652 ast::FunctionRetTy::Ty(ref ty) => {
1653 let inner_width = shape.width.checked_sub(3)?;
1654 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1655 .map(|r| format!("-> {}", r))
1661 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1663 ast::TyKind::Infer => {
1664 let original = context.snippet(ty.span);
1671 impl Rewrite for ast::Arg {
1672 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1673 if is_named_arg(self) {
1674 let mut result = self.pat
1675 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1677 if !is_empty_infer(context, &*self.ty) {
1678 if context.config.space_before_colon() {
1679 result.push_str(" ");
1681 result.push_str(":");
1682 if context.config.space_after_colon() {
1683 result.push_str(" ");
1685 let overhead = last_line_width(&result);
1686 let max_width = shape.width.checked_sub(overhead)?;
1687 let ty_str = self.ty
1688 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1689 result.push_str(&ty_str);
1694 self.ty.rewrite(context, shape)
1699 fn rewrite_explicit_self(
1700 explicit_self: &ast::ExplicitSelf,
1702 context: &RewriteContext,
1703 ) -> Option<String> {
1704 match explicit_self.node {
1705 ast::SelfKind::Region(lt, m) => {
1706 let mut_str = format_mutability(m);
1709 let lifetime_str = l.rewrite(
1711 Shape::legacy(context.config.max_width(), Indent::empty()),
1713 Some(format!("&{} {}self", lifetime_str, mut_str))
1715 None => Some(format!("&{}self", mut_str)),
1718 ast::SelfKind::Explicit(ref ty, _) => {
1719 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1721 let mutability = explicit_self_mutability(&args[0]);
1722 let type_str = ty.rewrite(
1724 Shape::legacy(context.config.max_width(), Indent::empty()),
1729 format_mutability(mutability),
1733 ast::SelfKind::Value(_) => {
1734 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1736 let mutability = explicit_self_mutability(&args[0]);
1738 Some(format!("{}self", format_mutability(mutability)))
1743 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1744 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1745 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1746 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1753 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1754 if is_named_arg(arg) {
1761 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1763 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1764 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1765 _ => arg.ty.span.hi(),
1769 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1770 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1771 ident.node != symbol::keywords::Invalid.ident()
1777 // Return type is (result, force_new_line_for_brace)
1779 context: &RewriteContext,
1784 newline_brace: bool,
1786 ) -> Option<(String, bool)> {
1787 let mut force_new_line_for_brace = false;
1789 let where_clause = &fn_sig.generics.where_clause;
1791 let mut result = String::with_capacity(1024);
1792 result.push_str(&fn_sig.to_str(context));
1795 result.push_str("fn ");
1796 result.push_str(&ident.to_string());
1799 let overhead = if has_body && !newline_brace {
1806 let used_width = last_line_used_width(&result, indent.width());
1807 let one_line_budget = context.budget(used_width + overhead);
1809 width: one_line_budget,
1813 let fd = fn_sig.decl;
1814 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1815 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1816 result.push_str(&generics_str);
1818 let snuggle_angle_bracket = generics_str
1821 .map_or(false, |l| l.trim_left().len() == 1);
1823 // Note that the width and indent don't really matter, we'll re-layout the
1824 // return type later anyway.
1825 let ret_str = fd.output
1826 .rewrite(context, Shape::indented(indent, context.config))?;
1828 let multi_line_ret_str = ret_str.contains('\n');
1829 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1832 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1843 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1849 // Check if vertical layout was forced.
1850 if one_line_budget == 0 {
1851 if snuggle_angle_bracket {
1854 result.push_str("(");
1855 if context.config.indent_style() == IndentStyle::Visual {
1857 result.push_str(&arg_indent.to_string(context.config));
1863 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1864 && result.ends_with('(')
1869 // Skip `pub(crate)`.
1870 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1871 // A conservative estimation, to goal is to be over all parens in generics
1872 let args_start = fn_sig
1876 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1877 let args_end = if fd.inputs.is_empty() {
1880 .span_after(mk_sp(args_start, span.hi()), ")")
1882 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1883 context.codemap.span_after(last_span, ")")
1885 let args_span = mk_sp(
1888 .span_after(mk_sp(args_start, span.hi()), "("),
1891 let arg_str = rewrite_args(
1894 fd.get_self().as_ref(),
1901 generics_str.contains('\n'),
1904 let put_args_in_block = match context.config.indent_style() {
1905 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1907 } && !fd.inputs.is_empty();
1909 let mut args_last_line_contains_comment = false;
1910 if put_args_in_block {
1911 arg_indent = indent.block_indent(context.config);
1913 result.push_str(&arg_indent.to_string(context.config));
1914 result.push_str(&arg_str);
1916 result.push_str(&indent.to_string(context.config));
1919 result.push_str(&arg_str);
1920 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1921 // Put the closing brace on the next line if it overflows the max width.
1923 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1926 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1929 // If the last line of args contains comment, we cannot put the closing paren
1930 // on the same line.
1934 .map_or(false, |last_line| last_line.contains("//"))
1936 args_last_line_contains_comment = true;
1938 result.push_str(&arg_indent.to_string(context.config));
1944 if let ast::FunctionRetTy::Ty(..) = fd.output {
1945 let ret_should_indent = match context.config.indent_style() {
1946 // If our args are block layout then we surely must have space.
1947 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1948 _ if args_last_line_contains_comment => false,
1949 _ if result.contains('\n') || multi_line_ret_str => true,
1951 // If the return type would push over the max width, then put the return type on
1952 // a new line. With the +1 for the signature length an additional space between
1953 // the closing parenthesis of the argument and the arrow '->' is considered.
1954 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1956 // If there is no where clause, take into account the space after the return type
1958 if where_clause.predicates.is_empty() {
1962 sig_length > context.config.max_width()
1965 let ret_indent = if ret_should_indent {
1966 let indent = if arg_str.is_empty() {
1967 // Aligning with non-existent args looks silly.
1968 force_new_line_for_brace = true;
1971 // FIXME: we might want to check that using the arg indent
1972 // doesn't blow our budget, and if it does, then fallback to
1973 // the where clause indent.
1978 result.push_str(&indent.to_string(context.config));
1982 Indent::new(indent.block_indent, last_line_width(&result))
1985 if multi_line_ret_str || ret_should_indent {
1986 // Now that we know the proper indent and width, we need to
1987 // re-layout the return type.
1988 let ret_str = fd.output
1989 .rewrite(context, Shape::indented(ret_indent, context.config))?;
1990 result.push_str(&ret_str);
1992 result.push_str(&ret_str);
1995 // Comment between return type and the end of the decl.
1996 let snippet_lo = fd.output.span().hi();
1997 if where_clause.predicates.is_empty() {
1998 let snippet_hi = span.hi();
1999 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2000 // Try to preserve the layout of the original snippet.
2001 let original_starts_with_newline = snippet
2003 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2004 let original_ends_with_newline = snippet
2005 .rfind(|c| c != ' ')
2006 .map_or(false, |i| snippet[i..].ends_with('\n'));
2007 let snippet = snippet.trim();
2008 if !snippet.is_empty() {
2009 result.push(if original_starts_with_newline {
2014 result.push_str(snippet);
2015 if original_ends_with_newline {
2016 force_new_line_for_brace = true;
2022 let pos_before_where = match fd.output {
2023 ast::FunctionRetTy::Default(..) => args_span.hi(),
2024 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2027 let is_args_multi_lined = arg_str.contains('\n');
2029 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2030 let where_clause_str = rewrite_where_clause(
2033 context.config.brace_style(),
2034 Shape::indented(indent, context.config),
2040 is_args_multi_lined,
2042 // If there are neither where clause nor return type, we may be missing comments between
2044 if where_clause_str.is_empty() {
2045 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2046 match recover_missing_comment_in_span(
2047 mk_sp(args_span.hi(), ret_span.hi()),
2050 last_line_width(&result),
2052 Some(ref missing_comment) if !missing_comment.is_empty() => {
2053 result.push_str(missing_comment);
2054 force_new_line_for_brace = true;
2061 result.push_str(&where_clause_str);
2063 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2064 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2065 Some((result, force_new_line_for_brace))
2068 #[derive(Copy, Clone)]
2069 struct WhereClauseOption {
2070 suppress_comma: bool, // Force no trailing comma
2071 snuggle: bool, // Do not insert newline before `where`
2072 compress_where: bool, // Try single line where clause instead of vertical layout
2075 impl WhereClauseOption {
2076 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2078 suppress_comma: suppress_comma,
2080 compress_where: false,
2084 pub fn snuggled(current: &str) -> WhereClauseOption {
2086 suppress_comma: false,
2087 snuggle: trimmed_last_line_width(current) == 1,
2088 compress_where: false,
2094 context: &RewriteContext,
2096 explicit_self: Option<&ast::ExplicitSelf>,
2097 one_line_budget: usize,
2098 multi_line_budget: usize,
2103 generics_str_contains_newline: bool,
2104 ) -> Option<String> {
2105 let mut arg_item_strs = args.iter()
2106 .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
2107 .collect::<Option<Vec<_>>>()?;
2109 // Account for sugary self.
2110 // FIXME: the comment for the self argument is dropped. This is blocked
2111 // on rust issue #27522.
2112 let min_args = explicit_self
2113 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2114 .map_or(1, |self_str| {
2115 arg_item_strs[0] = self_str;
2119 // Comments between args.
2120 let mut arg_items = Vec::new();
2122 arg_items.push(ListItem::from_str(""));
2125 // FIXME(#21): if there are no args, there might still be a comment, but
2126 // without spans for the comment or parens, there is no chance of
2127 // getting it right. You also don't get to put a comment on self, unless
2129 if args.len() >= min_args || variadic {
2130 let comment_span_start = if min_args == 2 {
2131 let second_arg_start = if arg_has_pattern(&args[1]) {
2132 args[1].pat.span.lo()
2134 args[1].ty.span.lo()
2136 let reduced_span = mk_sp(span.lo(), second_arg_start);
2138 context.codemap.span_after_last(reduced_span, ",")
2143 enum ArgumentKind<'a> {
2144 Regular(&'a ast::Arg),
2148 let variadic_arg = if variadic {
2149 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2150 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2151 Some(ArgumentKind::Variadic(variadic_start))
2156 let more_items = itemize_list(
2158 args[min_args - 1..]
2160 .map(ArgumentKind::Regular)
2161 .chain(variadic_arg),
2165 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2166 ArgumentKind::Variadic(start) => start,
2169 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2170 ArgumentKind::Variadic(start) => start + BytePos(3),
2173 ArgumentKind::Regular(..) => None,
2174 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2181 arg_items.extend(more_items);
2184 let fits_in_one_line = !generics_str_contains_newline
2185 && (arg_items.is_empty()
2186 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2188 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2189 item.item = Some(arg);
2192 let last_line_ends_with_comment = arg_items
2195 .and_then(|item| item.post_comment.as_ref())
2196 .map_or(false, |s| s.trim().starts_with("//"));
2198 let (indent, trailing_comma) = match context.config.indent_style() {
2199 IndentStyle::Block if fits_in_one_line => {
2200 (indent.block_indent(context.config), SeparatorTactic::Never)
2202 IndentStyle::Block => (
2203 indent.block_indent(context.config),
2204 context.config.trailing_comma(),
2206 IndentStyle::Visual if last_line_ends_with_comment => {
2207 (arg_indent, context.config.trailing_comma())
2209 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2212 let tactic = definitive_tactic(
2214 context.config.fn_args_density().to_list_tactic(),
2218 let budget = match tactic {
2219 DefinitiveListTactic::Horizontal => one_line_budget,
2220 _ => multi_line_budget,
2223 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2225 let fmt = ListFormatting {
2228 trailing_separator: if variadic {
2229 SeparatorTactic::Never
2233 separator_place: SeparatorPlace::Back,
2234 shape: Shape::legacy(budget, indent),
2235 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2236 preserve_newline: true,
2237 config: context.config,
2240 write_list(&arg_items, &fmt)
2243 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2244 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2245 ident.node != symbol::keywords::Invalid.ident()
2251 fn compute_budgets_for_args(
2252 context: &RewriteContext,
2256 newline_brace: bool,
2258 force_vertical_layout: bool,
2259 ) -> Option<((usize, usize, Indent))> {
2261 "compute_budgets_for_args {} {:?}, {}, {}",
2267 // Try keeping everything on the same line.
2268 if !result.contains('\n') && !force_vertical_layout {
2269 // 2 = `()`, 3 = `() `, space is before ret_string.
2270 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2271 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2281 let one_line_budget = context.budget(used_space);
2283 if one_line_budget > 0 {
2285 let (indent, multi_line_budget) = match context.config.indent_style() {
2286 IndentStyle::Block => {
2287 let indent = indent.block_indent(context.config);
2288 (indent, context.budget(indent.width() + 1))
2290 IndentStyle::Visual => {
2291 let indent = indent + result.len() + 1;
2292 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2293 (indent, context.budget(multi_line_overhead))
2297 return Some((one_line_budget, multi_line_budget, indent));
2301 // Didn't work. we must force vertical layout and put args on a newline.
2302 let new_indent = indent.block_indent(context.config);
2303 let used_space = match context.config.indent_style() {
2305 IndentStyle::Block => new_indent.width() + 1,
2306 // Account for `)` and possibly ` {`.
2307 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2309 Some((0, context.budget(used_space), new_indent))
2312 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2313 let predicate_count = where_clause.predicates.len();
2315 if config.where_single_line() && predicate_count == 1 {
2318 let brace_style = config.brace_style();
2320 brace_style == BraceStyle::AlwaysNextLine
2321 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2324 fn rewrite_generics(
2325 context: &RewriteContext,
2326 generics: &ast::Generics,
2329 ) -> Option<String> {
2330 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2331 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2332 rewrite_generics_inner(context, generics, g_shape, one_line_width, span)
2333 .or_else(|| rewrite_generics_inner(context, generics, g_shape, 0, span))
2336 fn rewrite_generics_inner(
2337 context: &RewriteContext,
2338 generics: &ast::Generics,
2340 one_line_width: usize,
2342 ) -> Option<String> {
2343 // FIXME: convert bounds to where clauses where they get too big or if
2344 // there is a where clause at all.
2347 enum GenericsArg<'a> {
2348 Lifetime(&'a ast::LifetimeDef),
2349 TyParam(&'a ast::TyParam),
2351 impl<'a> Rewrite for GenericsArg<'a> {
2352 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2354 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2355 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2359 impl<'a> Spanned for GenericsArg<'a> {
2360 fn span(&self) -> Span {
2362 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2363 GenericsArg::TyParam(ty) => ty.span(),
2368 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2369 return Some(String::new());
2372 let generics_args = generics
2375 .map(|lt| GenericsArg::Lifetime(lt))
2376 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2377 let items = itemize_list(
2382 |arg| arg.span().lo(),
2383 |arg| arg.span().hi(),
2384 |arg| arg.rewrite(context, shape),
2385 context.codemap.span_after(span, "<"),
2389 format_generics_item_list(context, items, shape, one_line_width)
2392 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2393 match config.indent_style() {
2394 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2395 IndentStyle::Block => {
2399 .block_indent(config.tab_spaces())
2400 .with_max_width(config)
2406 pub fn format_generics_item_list<I>(
2407 context: &RewriteContext,
2410 one_line_budget: usize,
2413 I: Iterator<Item = ListItem>,
2415 let item_vec = items.collect::<Vec<_>>();
2417 let tactic = definitive_tactic(
2419 ListTactic::HorizontalVertical,
2423 let fmt = ListFormatting {
2426 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2427 SeparatorTactic::Never
2429 context.config.trailing_comma()
2431 separator_place: SeparatorPlace::Back,
2433 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2434 preserve_newline: true,
2435 config: context.config,
2438 let list_str = write_list(&item_vec, &fmt)?;
2440 Some(wrap_generics_with_angle_brackets(
2447 pub fn wrap_generics_with_angle_brackets(
2448 context: &RewriteContext,
2450 list_offset: Indent,
2452 if context.config.indent_style() == IndentStyle::Block
2453 && (list_str.contains('\n') || list_str.ends_with(','))
2457 list_offset.to_string(context.config),
2460 .block_unindent(context.config)
2461 .to_string(context.config)
2463 } else if context.config.spaces_within_parens_and_brackets() {
2464 format!("< {} >", list_str)
2466 format!("<{}>", list_str)
2470 fn rewrite_trait_bounds(
2471 context: &RewriteContext,
2472 bounds: &[ast::TyParamBound],
2474 ) -> Option<String> {
2475 if bounds.is_empty() {
2476 return Some(String::new());
2478 let bound_str = bounds
2480 .map(|ty_bound| ty_bound.rewrite(context, shape))
2481 .collect::<Option<Vec<_>>>()?;
2482 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2485 fn rewrite_where_clause_rfc_style(
2486 context: &RewriteContext,
2487 where_clause: &ast::WhereClause,
2490 span_end: Option<BytePos>,
2491 span_end_before_where: BytePos,
2492 where_clause_option: WhereClauseOption,
2493 is_args_multi_line: bool,
2494 ) -> Option<String> {
2495 let block_shape = shape.block().with_max_width(context.config);
2497 let (span_before, span_after) =
2498 missing_span_before_after_where(span_end_before_where, where_clause);
2499 let (comment_before, comment_after) =
2500 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2502 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2505 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2508 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2510 let clause_shape = clause_shape.sub_width(1)?;
2511 // each clause on one line, trailing comma (except if suppress_comma)
2512 let span_start = where_clause.predicates[0].span().lo();
2513 // If we don't have the start of the next span, then use the end of the
2514 // predicates, but that means we miss comments.
2515 let len = where_clause.predicates.len();
2516 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2517 let span_end = span_end.unwrap_or(end_of_preds);
2518 let items = itemize_list(
2520 where_clause.predicates.iter(),
2523 |pred| pred.span().lo(),
2524 |pred| pred.span().hi(),
2525 |pred| pred.rewrite(context, clause_shape),
2530 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2531 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2532 SeparatorTactic::Never
2534 context.config.trailing_comma()
2537 // shape should be vertical only and only if we have `where_single_line` option enabled
2538 // and the number of items of the where clause is equal to 1
2539 let shape_tactic = if where_single_line {
2540 DefinitiveListTactic::Horizontal
2542 DefinitiveListTactic::Vertical
2545 let fmt = ListFormatting {
2546 tactic: shape_tactic,
2548 trailing_separator: comma_tactic,
2549 separator_place: SeparatorPlace::Back,
2550 shape: clause_shape,
2551 ends_with_newline: true,
2552 preserve_newline: true,
2553 config: context.config,
2555 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2557 let comment_separator = |comment: &str, shape: Shape| if comment.is_empty() {
2560 format!("\n{}", shape.indent.to_string(context.config))
2562 let newline_before_where = comment_separator(&comment_before, shape);
2563 let newline_after_where = comment_separator(&comment_after, clause_shape);
2566 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2567 && comment_after.is_empty() && !preds_str.contains('\n')
2568 && 6 + preds_str.len() <= shape.width || where_single_line
2572 format!("\n{}", clause_shape.indent.to_string(context.config))
2575 "{}{}{}where{}{}{}{}",
2578 newline_before_where,
2579 newline_after_where,
2586 fn rewrite_where_clause(
2587 context: &RewriteContext,
2588 where_clause: &ast::WhereClause,
2589 brace_style: BraceStyle,
2593 span_end: Option<BytePos>,
2594 span_end_before_where: BytePos,
2595 where_clause_option: WhereClauseOption,
2596 is_args_multi_line: bool,
2597 ) -> Option<String> {
2598 if where_clause.predicates.is_empty() {
2599 return Some(String::new());
2602 if context.config.indent_style() == IndentStyle::Block {
2603 return rewrite_where_clause_rfc_style(
2609 span_end_before_where,
2610 where_clause_option,
2615 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2617 let offset = match context.config.indent_style() {
2618 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2619 // 6 = "where ".len()
2620 IndentStyle::Visual => shape.indent + extra_indent + 6,
2622 // FIXME: if indent_style != Visual, then the budgets below might
2623 // be out by a char or two.
2625 let budget = context.config.max_width() - offset.width();
2626 let span_start = where_clause.predicates[0].span().lo();
2627 // If we don't have the start of the next span, then use the end of the
2628 // predicates, but that means we miss comments.
2629 let len = where_clause.predicates.len();
2630 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2631 let span_end = span_end.unwrap_or(end_of_preds);
2632 let items = itemize_list(
2634 where_clause.predicates.iter(),
2637 |pred| pred.span().lo(),
2638 |pred| pred.span().hi(),
2639 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2644 let item_vec = items.collect::<Vec<_>>();
2645 // FIXME: we don't need to collect here
2646 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2648 let mut comma_tactic = context.config.trailing_comma();
2649 // Kind of a hack because we don't usually have trailing commas in where clauses.
2650 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2651 comma_tactic = SeparatorTactic::Never;
2654 let fmt = ListFormatting {
2657 trailing_separator: comma_tactic,
2658 separator_place: SeparatorPlace::Back,
2659 shape: Shape::legacy(budget, offset),
2660 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2661 preserve_newline: true,
2662 config: context.config,
2664 let preds_str = write_list(&item_vec, &fmt)?;
2666 let end_length = if terminator == "{" {
2667 // If the brace is on the next line we don't need to count it otherwise it needs two
2670 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2671 BraceStyle::PreferSameLine => 2,
2673 } else if terminator == "=" {
2678 if density == Density::Tall || preds_str.contains('\n')
2679 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2683 (shape.indent + extra_indent).to_string(context.config),
2687 Some(format!(" where {}", preds_str))
2691 fn missing_span_before_after_where(
2692 before_item_span_end: BytePos,
2693 where_clause: &ast::WhereClause,
2695 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2697 let pos_after_where = where_clause.span.lo() + BytePos(5);
2698 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2699 (missing_span_before, missing_span_after)
2702 fn rewrite_comments_before_after_where(
2703 context: &RewriteContext,
2704 span_before_where: Span,
2705 span_after_where: Span,
2707 ) -> Option<(String, String)> {
2708 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2709 let after_comment = rewrite_missing_comment(
2711 shape.block_indent(context.config.tab_spaces()),
2714 Some((before_comment, after_comment))
2717 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2718 format!("{}{}{}", format_visibility(vis), item_name, ident)
2721 #[derive(PartialEq, Eq)]
2729 context: &RewriteContext,
2730 generics: &ast::Generics,
2731 brace_style: BraceStyle,
2732 brace_pos: BracePos,
2736 ) -> Option<String> {
2737 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2738 let mut result = rewrite_generics(context, generics, shape, span)?;
2740 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2741 let budget = context.budget(last_line_used_width(&result, offset.width()));
2742 let mut option = WhereClauseOption::snuggled(&result);
2743 if brace_pos == BracePos::None {
2744 option.suppress_comma = true;
2746 // If the generics are not parameterized then generics.span.hi() == 0,
2747 // so we use span.lo(), which is the position after `struct Foo`.
2748 let span_end_before_where = if generics.is_parameterized() {
2753 let where_clause_str = rewrite_where_clause(
2755 &generics.where_clause,
2757 Shape::legacy(budget, offset.block_only()),
2761 span_end_before_where,
2765 result.push_str(&where_clause_str);
2766 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2767 || (generics.where_clause.predicates.is_empty()
2768 && trimmed_last_line_width(&result) == 1)
2770 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2771 || brace_style != BraceStyle::AlwaysNextLine
2773 if brace_pos == BracePos::None {
2774 return Some(result);
2776 let total_used_width = last_line_used_width(&result, used_width);
2777 let remaining_budget = context.budget(total_used_width);
2778 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2779 // and hence we take the closer into account as well for one line budget.
2780 // We assume that the closer has the same length as the opener.
2781 let overhead = if brace_pos == BracePos::ForceSameLine {
2788 let forbid_same_line_brace = overhead > remaining_budget;
2789 if !forbid_same_line_brace && same_line_brace {
2793 result.push_str(&offset.block_only().to_string(context.config));
2800 impl Rewrite for ast::ForeignItem {
2801 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2802 let attrs_str = self.attrs.rewrite(context, shape)?;
2803 // Drop semicolon or it will be interpreted as comment.
2804 // FIXME: this may be a faulty span from libsyntax.
2805 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2807 let item_str = match self.node {
2808 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2813 &FnSig::new(fn_decl, generics, self.vis.clone()),
2817 ).map(|(s, _)| format!("{};", s))
2819 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2820 // FIXME(#21): we're dropping potential comments in between the
2821 // function keywords here.
2822 let vis = format_visibility(&self.vis);
2823 let mut_str = if is_mutable { "mut " } else { "" };
2824 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2826 let shape = shape.sub_width(1)?;
2827 ty.rewrite(context, shape).map(|ty_str| {
2828 // 1 = space between prefix and type.
2829 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2832 let nested_indent = shape.indent.block_indent(context.config);
2833 format!("\n{}", nested_indent.to_string(context.config))
2835 format!("{}{}{};", prefix, sep, ty_str)
2838 ast::ForeignItemKind::Ty => {
2839 let vis = format_visibility(&self.vis);
2840 Some(format!("{}type {};", vis, self.ident))
2844 let missing_span = if self.attrs.is_empty() {
2845 mk_sp(self.span.lo(), self.span.lo())
2847 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2849 combine_strs_with_missing_comments(