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.buffer.push_str(&item.abi);
245 let snippet = self.snippet(item.span);
246 let brace_pos = snippet.find_uncommented("{").unwrap();
248 self.buffer.push_str("{");
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);
260 .push_str(&self.block_indent.to_string(self.config));
262 for item in &item.body {
263 self.format_body_element(item);
266 self.block_indent = self.block_indent.block_unindent(self.config);
267 self.format_missing_with_indent(item.span.hi() - BytePos(1));
271 self.buffer.push_str("}");
272 self.last_pos = item.span.hi();
275 fn format_body_element(&mut self, element: &BodyElement) {
277 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
281 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
282 let item = Item::from_foreign_mod(fm, span, self.config);
283 self.format_item(item);
286 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
287 let rewrite = item.rewrite(&self.get_context(), self.shape());
288 self.push_rewrite(item.span(), rewrite);
289 self.last_pos = item.span.hi();
299 ) -> Option<String> {
300 let context = self.get_context();
302 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
304 let (mut result, force_newline_brace) =
305 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
308 if self.config.brace_style() == BraceStyle::AlwaysNextLine || force_newline_brace
309 || last_line_width(&result) + 2 > self.shape().width
311 newline_brace = true;
312 } else if !result.contains('\n') {
313 newline_brace = false;
316 // Prepare for the function body by possibly adding a newline and
318 // FIXME we'll miss anything between the end of the signature and the
319 // start of the body, but we need more spans from the compiler to solve
323 result.push_str(&indent.to_string(self.config));
328 self.single_line_fn(&result, block).or_else(|| Some(result))
331 pub fn rewrite_required_fn(
335 sig: &ast::MethodSig,
336 generics: &ast::Generics,
338 ) -> Option<String> {
339 // Drop semicolon or it will be interpreted as comment.
340 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
341 let context = self.get_context();
343 let (mut result, _) = rewrite_fn_base(
347 &FnSig::from_method_sig(sig, generics),
353 // Re-attach semicolon
359 fn single_line_fn(&self, fn_str: &str, block: &ast::Block) -> Option<String> {
360 if fn_str.contains('\n') {
364 let codemap = self.get_context().codemap;
366 if self.config.empty_item_single_line() && is_empty_block(block, codemap)
367 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
369 return Some(format!("{}{{}}", fn_str));
372 if self.config.fn_single_line() && is_simple_block_stmt(block, codemap) {
374 if let Some(stmt) = block.stmts.first() {
375 match stmt_expr(stmt) {
377 let suffix = if semicolon_for_expr(&self.get_context(), e) {
383 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
385 .or_else(|| Some(self.snippet(e.span).to_owned()))
387 None => stmt.rewrite(&self.get_context(), self.shape()),
394 if let Some(res) = rewrite {
395 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
396 if !res.contains('\n') && width <= self.config.max_width() {
397 return Some(format!("{}{{ {} }}", fn_str, res));
405 pub fn visit_static(&mut self, static_parts: &StaticParts) {
406 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
407 self.push_rewrite(static_parts.span, rewrite);
410 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
411 let is_tuple = struct_parts.def.is_tuple();
412 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
413 .map(|s| if is_tuple { s + ";" } else { s });
414 self.push_rewrite(struct_parts.span, rewrite);
420 vis: &ast::Visibility,
421 enum_def: &ast::EnumDef,
422 generics: &ast::Generics,
425 let enum_header = format_header("enum ", ident, vis);
426 self.buffer.push_str(&enum_header);
428 let enum_snippet = self.snippet(span);
429 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
430 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
431 let generics_str = format_generics(
434 self.config.brace_style(),
435 if enum_def.variants.is_empty() {
436 BracePos::ForceSameLine
441 mk_sp(span.lo(), body_start),
442 last_line_width(&enum_header),
444 self.buffer.push_str(&generics_str);
446 self.last_pos = body_start;
448 self.block_indent = self.block_indent.block_indent(self.config);
449 let variant_list = self.format_variant_list(enum_def, body_start, span.hi() - BytePos(1));
451 Some(ref body_str) => self.buffer.push_str(body_str),
452 None => self.format_missing_no_indent(span.hi() - BytePos(1)),
454 self.block_indent = self.block_indent.block_unindent(self.config);
456 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
458 .push_str(&self.block_indent.to_string(self.config));
460 self.buffer.push_str("}");
461 self.last_pos = span.hi();
464 // Format the body of an enum definition
465 fn format_variant_list(
467 enum_def: &ast::EnumDef,
470 ) -> Option<String> {
471 if enum_def.variants.is_empty() {
474 let mut result = String::with_capacity(1024);
476 let indentation = self.block_indent.to_string(self.config);
477 result.push_str(&indentation);
479 let itemize_list_with = |one_line_width: usize| {
482 enum_def.variants.iter(),
486 if !f.node.attrs.is_empty() {
487 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).to_owned());
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_context(context);
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')) {
846 generics_str, polarity_str, &trait_ref_str
850 // We could not make enough space for trait_ref, so put it on new line.
852 let offset = offset.block_indent(context.config);
853 let shape = Shape::indented(offset, context.config);
854 let trait_ref_str = trait_ref.rewrite(context, shape)?;
858 &offset.to_string(context.config),
867 pub struct StructParts<'a> {
870 vis: &'a ast::Visibility,
871 def: &'a ast::VariantData,
872 generics: Option<&'a ast::Generics>,
876 impl<'a> StructParts<'a> {
877 fn format_header(&self) -> String {
878 format_header(self.prefix, self.ident, self.vis)
881 fn from_variant(variant: &'a ast::Variant) -> Self {
884 ident: variant.node.name,
885 vis: &ast::Visibility::Inherited,
886 def: &variant.node.data,
892 pub fn from_item(item: &'a ast::Item) -> Self {
893 let (prefix, def, generics) = match item.node {
894 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
895 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
903 generics: Some(generics),
910 context: &RewriteContext,
911 struct_parts: &StructParts,
913 one_line_width: Option<usize>,
914 ) -> Option<String> {
915 match *struct_parts.def {
916 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
917 ast::VariantData::Tuple(ref fields, _) => {
918 format_tuple_struct(context, struct_parts, fields, offset)
920 ast::VariantData::Struct(ref fields, _) => {
921 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
926 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
927 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
930 let mut result = String::with_capacity(128);
931 let header = format!(
933 format_visibility(&item.vis),
934 format_unsafety(unsafety),
938 result.push_str(&header);
940 let body_lo = context.codemap.span_after(item.span, "{");
942 let shape = Shape::indented(offset, context.config);
944 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
945 result.push_str(&generics_str);
947 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
948 if !type_param_bounds.is_empty() {
949 let ident_hi = context.codemap.span_after(item.span, &format!("{}", item.ident));
950 let bound_hi = type_param_bounds.last().unwrap().span().hi();
951 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
952 if contains_comment(&snippet) {
956 let trait_bound_str = rewrite_trait_bounds(
959 Shape::indented(offset, context.config),
961 // If the trait, generics, and trait bound cannot fit on the same line,
962 // put the trait bounds on an indented new line
963 if offset.width() + last_line_width(&result) + trait_bound_str.len()
964 > context.config.comment_width()
967 let trait_indent = offset.block_only().block_indent(context.config);
968 result.push_str(&trait_indent.to_string(context.config));
970 result.push_str(&trait_bound_str);
973 if context.config.indent_style() == IndentStyle::Block && result.is_empty() {
979 let where_budget = context.budget(last_line_width(&result));
980 let pos_before_where = if type_param_bounds.is_empty() {
981 generics.where_clause.span.lo()
983 type_param_bounds[type_param_bounds.len() - 1].span().hi()
985 let option = WhereClauseOption::snuggled(&generics_str);
986 let where_clause_str = rewrite_where_clause(
988 &generics.where_clause,
989 context.config.brace_style(),
990 Shape::legacy(where_budget, offset.block_only()),
998 // If the where clause cannot fit on the same line,
999 // put the where clause on a new line
1000 if !where_clause_str.contains('\n')
1001 && last_line_width(&result) + where_clause_str.len() + offset.width()
1002 > context.config.comment_width()
1005 let width = offset.block_indent + context.config.tab_spaces() - 1;
1006 let where_indent = Indent::new(0, width);
1007 result.push_str(&where_indent.to_string(context.config));
1009 result.push_str(&where_clause_str);
1011 if generics.where_clause.predicates.is_empty() {
1012 let item_snippet = context.snippet(item.span);
1013 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1015 let comment_hi = body_lo - BytePos(1);
1016 let comment_lo = item.span.lo() + BytePos(lo as u32);
1017 if comment_lo < comment_hi {
1018 match recover_missing_comment_in_span(
1019 mk_sp(comment_lo, comment_hi),
1020 Shape::indented(offset, context.config),
1022 last_line_width(&result),
1024 Some(ref missing_comment) if !missing_comment.is_empty() => {
1025 result.push_str(missing_comment);
1033 match context.config.brace_style() {
1034 _ if last_line_contains_single_line_comment(&result) => {
1036 result.push_str(&offset.to_string(context.config));
1038 BraceStyle::AlwaysNextLine => {
1040 result.push_str(&offset.to_string(context.config));
1042 BraceStyle::PreferSameLine => result.push(' '),
1043 BraceStyle::SameLineWhere => {
1044 if !where_clause_str.is_empty()
1045 && (!trait_items.is_empty() || result.contains('\n'))
1048 result.push_str(&offset.to_string(context.config));
1056 let snippet = context.snippet(item.span);
1057 let open_pos = snippet.find_uncommented("{")? + 1;
1059 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1060 let mut visitor = FmtVisitor::from_context(context);
1061 visitor.block_indent = offset.block_only().block_indent(context.config);
1062 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1064 for item in trait_items {
1065 visitor.visit_trait_item(item);
1068 visitor.format_missing(item.span.hi() - BytePos(1));
1070 let inner_indent_str = visitor.block_indent.to_string(context.config);
1071 let outer_indent_str = offset.block_only().to_string(context.config);
1074 result.push_str(&inner_indent_str);
1075 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1077 result.push_str(&outer_indent_str);
1078 } else if result.contains('\n') {
1089 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1090 let header_str = format_header(p.prefix, p.ident, p.vis);
1091 let generics_str = if let Some(generics) = p.generics {
1092 let hi = if generics.where_clause.predicates.is_empty() {
1095 generics.where_clause.span.hi()
1100 context.config.brace_style(),
1103 mk_sp(generics.span.lo(), hi),
1104 last_line_width(&header_str),
1109 Some(format!("{}{};", header_str, generics_str))
1112 pub fn format_struct_struct(
1113 context: &RewriteContext,
1114 struct_parts: &StructParts,
1115 fields: &[ast::StructField],
1117 one_line_width: Option<usize>,
1118 ) -> Option<String> {
1119 let mut result = String::with_capacity(1024);
1120 let span = struct_parts.span;
1122 let header_str = struct_parts.format_header();
1123 result.push_str(&header_str);
1125 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1126 let body_lo = context.codemap.span_after(span, "{");
1128 let generics_str = match struct_parts.generics {
1129 Some(g) => format_generics(
1132 context.config.brace_style(),
1133 if fields.is_empty() {
1134 BracePos::ForceSameLine
1139 mk_sp(header_hi, body_lo),
1140 last_line_width(&result),
1143 // 3 = ` {}`, 2 = ` {`.
1144 let overhead = if fields.is_empty() { 3 } else { 2 };
1145 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1146 || context.config.max_width() < overhead + result.len()
1148 format!("\n{}{{", offset.block_only().to_string(context.config))
1155 let overhead = if fields.is_empty() { 1 } else { 0 };
1156 let total_width = result.len() + generics_str.len() + overhead;
1157 if !generics_str.is_empty() && !generics_str.contains('\n')
1158 && total_width > context.config.max_width()
1161 result.push_str(&offset.to_string(context.config));
1162 result.push_str(generics_str.trim_left());
1164 result.push_str(&generics_str);
1167 if fields.is_empty() {
1168 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1169 if snippet.trim().is_empty() {
1171 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1173 result.push_str(snippet.trim_right());
1175 result.push_str(&offset.to_string(context.config));
1177 result.push_str(&snippet);
1180 return Some(result);
1184 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1185 let one_line_budget =
1186 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1188 let items_str = rewrite_with_alignment(
1191 Shape::indented(offset, context.config).sub_width(1)?,
1192 mk_sp(body_lo, span.hi()),
1196 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget {
1197 Some(format!("{} {} }}", result, items_str))
1203 .block_indent(context.config)
1204 .to_string(context.config),
1206 offset.to_string(context.config)
1211 /// Returns a bytepos that is after that of `(` in `pub(..)`. If the given visibility does not
1212 /// contain `pub(..)`, then return the `lo` of the `defualt_span`. Yeah, but for what? Well, we need
1213 /// to bypass the `(` in the visibility when creating a span of tuple's body or fn's args.
1214 fn get_bytepos_after_visibility(
1215 context: &RewriteContext,
1216 vis: &ast::Visibility,
1221 ast::Visibility::Crate(s, CrateSugar::PubCrate) => context
1223 .span_after(mk_sp(s.hi(), default_span.hi()), terminator),
1224 ast::Visibility::Crate(s, CrateSugar::JustCrate) => s.hi(),
1225 ast::Visibility::Restricted { ref path, .. } => path.span.hi(),
1226 _ => default_span.lo(),
1230 fn format_tuple_struct(
1231 context: &RewriteContext,
1232 struct_parts: &StructParts,
1233 fields: &[ast::StructField],
1235 ) -> Option<String> {
1236 let mut result = String::with_capacity(1024);
1237 let span = struct_parts.span;
1239 let header_str = struct_parts.format_header();
1240 result.push_str(&header_str);
1242 let body_lo = if fields.is_empty() {
1243 let lo = get_bytepos_after_visibility(context, struct_parts.vis, span, ")");
1244 context.codemap.span_after(mk_sp(lo, span.hi()), "(")
1248 let body_hi = if fields.is_empty() {
1249 context.codemap.span_after(mk_sp(body_lo, span.hi()), ")")
1251 // This is a dirty hack to work around a missing `)` from the span of the last field.
1252 let last_arg_span = fields[fields.len() - 1].span;
1253 if context.snippet(last_arg_span).ends_with(')') {
1258 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1262 let where_clause_str = match struct_parts.generics {
1264 let budget = context.budget(last_line_width(&header_str));
1265 let shape = Shape::legacy(budget, offset);
1266 let g_span = mk_sp(span.lo(), body_lo);
1267 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1268 result.push_str(&generics_str);
1270 let where_budget = context.budget(last_line_width(&result));
1271 let option = WhereClauseOption::new(true, false);
1272 rewrite_where_clause(
1274 &generics.where_clause,
1275 context.config.brace_style(),
1276 Shape::legacy(where_budget, offset.block_only()),
1277 Density::Compressed,
1285 None => "".to_owned(),
1288 if fields.is_empty() {
1290 let used_width = last_line_used_width(&result, offset.width()) + 3;
1291 if used_width > context.config.max_width() {
1293 result.push_str(&offset
1294 .block_indent(context.config)
1295 .to_string(context.config))
1298 let snippet = context.snippet(mk_sp(
1300 context.codemap.span_before(mk_sp(body_lo, span.hi()), ")"),
1302 if snippet.is_empty() {
1304 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1305 result.push_str(snippet.trim_right());
1307 result.push_str(&offset.to_string(context.config));
1309 result.push_str(&snippet);
1313 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1314 let fields = &fields.iter().collect::<Vec<_>>()[..];
1315 let one_line_width = context.config.width_heuristics().fn_call_width;
1316 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1319 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1320 && (result.contains('\n')
1321 || offset.block_indent + result.len() + where_clause_str.len() + 1
1322 > context.config.max_width())
1324 // We need to put the where clause on a new line, but we didn't
1325 // know that earlier, so the where clause will not be indented properly.
1327 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1328 .to_string(context.config));
1330 result.push_str(&where_clause_str);
1335 pub fn rewrite_type_alias(
1336 context: &RewriteContext,
1340 generics: &ast::Generics,
1341 vis: &ast::Visibility,
1343 ) -> Option<String> {
1344 let mut result = String::with_capacity(128);
1346 result.push_str(&format_visibility(vis));
1347 result.push_str("type ");
1348 result.push_str(&ident.to_string());
1351 let shape = Shape::indented(indent + result.len(), context.config).sub_width(2)?;
1352 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo());
1353 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1354 result.push_str(&generics_str);
1356 let where_budget = context.budget(last_line_width(&result));
1357 let option = WhereClauseOption::snuggled(&result);
1358 let where_clause_str = rewrite_where_clause(
1360 &generics.where_clause,
1361 context.config.brace_style(),
1362 Shape::legacy(where_budget, indent),
1370 result.push_str(&where_clause_str);
1371 if where_clause_str.is_empty() {
1372 result.push_str(" = ");
1374 result.push_str(&format!("\n{}= ", indent.to_string(context.config)));
1377 let line_width = last_line_width(&result);
1378 // This checked_sub may fail as the extra space after '=' is not taken into account
1379 // In that case the budget is set to 0 which will make ty.rewrite retry on a new line
1380 let budget = context.budget(indent.width() + line_width + ";".len());
1381 let type_indent = indent + line_width;
1382 // Try to fit the type on the same line
1383 let ty_str = ty.rewrite(context, Shape::legacy(budget, type_indent))
1385 // The line was too short, try to put the type on the next line
1387 // Remove the space after '='
1389 let type_indent = indent.block_indent(context.config);
1391 result.push_str(&type_indent.to_string(context.config));
1392 let budget = context.budget(type_indent.width() + ";".len());
1393 ty.rewrite(context, Shape::legacy(budget, type_indent))
1395 result.push_str(&ty_str);
1396 result.push_str(";");
1400 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1402 if config.space_before_colon() { " " } else { "" },
1403 if config.space_after_colon() { " " } else { "" },
1407 pub fn rewrite_struct_field_prefix(
1408 context: &RewriteContext,
1409 field: &ast::StructField,
1410 ) -> Option<String> {
1411 let vis = format_visibility(&field.vis);
1412 let type_annotation_spacing = type_annotation_spacing(context.config);
1413 Some(match field.ident {
1414 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1415 None => format!("{}", vis),
1419 impl Rewrite for ast::StructField {
1420 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1421 rewrite_struct_field(context, self, shape, 0)
1425 pub fn rewrite_struct_field(
1426 context: &RewriteContext,
1427 field: &ast::StructField,
1429 lhs_max_width: usize,
1430 ) -> Option<String> {
1431 if contains_skip(&field.attrs) {
1432 let snippet = context.snippet(mk_sp(field.attrs[0].span.lo(), field.span.hi()));
1433 return Some(snippet.to_owned());
1436 let type_annotation_spacing = type_annotation_spacing(context.config);
1437 let prefix = rewrite_struct_field_prefix(context, field)?;
1439 let attrs_str = field.attrs.rewrite(context, shape)?;
1440 let attrs_extendable = attrs_str.is_empty()
1441 || (context.config.same_line_attributes() && is_attributes_extendable(&attrs_str));
1442 let missing_span = if field.attrs.is_empty() {
1443 mk_sp(field.span.lo(), field.span.lo())
1445 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1447 let mut spacing = String::from(if field.ident.is_some() {
1448 type_annotation_spacing.1
1452 // Try to put everything on a single line.
1453 let attr_prefix = combine_strs_with_missing_comments(
1461 let overhead = last_line_width(&attr_prefix);
1462 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1463 for _ in 0..lhs_offset {
1466 // In this extreme case we will be missing a space betweeen an attribute and a field.
1467 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1470 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1471 let mut orig_ty = field.ty.rewrite(context, ty_shape);
1472 if let Some(ref ty) = orig_ty {
1473 if !ty.contains('\n') {
1474 return Some(attr_prefix + &spacing + ty);
1478 // We must use multiline. We are going to put attributes and a field on different lines.
1480 let rhs_shape = shape.offset_left(last_line_width(&prefix) + 1)?;
1481 orig_ty = field.ty.rewrite(context, rhs_shape);
1482 let field_str = if prefix.is_empty() {
1485 prefix + &choose_rhs(context, &*field.ty, rhs_shape, orig_ty)?
1487 combine_strs_with_missing_comments(context, &attrs_str, &field_str, missing_span, shape, false)
1490 pub struct StaticParts<'a> {
1492 vis: &'a ast::Visibility,
1495 mutability: ast::Mutability,
1496 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1497 defaultness: Option<ast::Defaultness>,
1501 impl<'a> StaticParts<'a> {
1502 pub fn from_item(item: &'a ast::Item) -> Self {
1503 let (prefix, ty, mutability, expr) = match item.node {
1504 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1505 ast::ItemKind::Const(ref ty, ref expr) => {
1506 ("const", ty, ast::Mutability::Immutable, expr)
1508 _ => unreachable!(),
1515 mutability: mutability,
1516 expr_opt: Some(expr),
1522 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1523 let (ty, expr_opt) = match ti.node {
1524 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1525 _ => unreachable!(),
1529 vis: &ast::Visibility::Inherited,
1532 mutability: ast::Mutability::Immutable,
1533 expr_opt: expr_opt.as_ref(),
1539 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1540 let (ty, expr) = match ii.node {
1541 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1542 _ => unreachable!(),
1549 mutability: ast::Mutability::Immutable,
1550 expr_opt: Some(expr),
1551 defaultness: Some(ii.defaultness),
1558 context: &RewriteContext,
1559 static_parts: &StaticParts,
1561 ) -> Option<String> {
1562 let colon = colon_spaces(
1563 context.config.space_before_colon(),
1564 context.config.space_after_colon(),
1566 let prefix = format!(
1568 format_visibility(static_parts.vis),
1569 static_parts.defaultness.map_or("", format_defaultness),
1570 static_parts.prefix,
1571 format_mutability(static_parts.mutability),
1577 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1578 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1580 if let Some(expr) = static_parts.expr_opt {
1581 let lhs = format!("{}{} =", prefix, ty_str);
1583 let remaining_width = context.budget(offset.block_indent + 1);
1588 Shape::legacy(remaining_width, offset.block_only()),
1589 ).and_then(|res| recover_comment_removed(res, static_parts.span, context))
1590 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1592 Some(format!("{}{};", prefix, ty_str))
1596 pub fn rewrite_associated_type(
1598 ty_opt: Option<&ptr::P<ast::Ty>>,
1599 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1600 context: &RewriteContext,
1602 ) -> Option<String> {
1603 let prefix = format!("type {}", ident);
1605 let type_bounds_str = if let Some(bounds) = ty_param_bounds_opt {
1607 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1608 let bound_str = bounds
1610 .map(|ty_bound| ty_bound.rewrite(context, shape))
1611 .collect::<Option<Vec<_>>>()?;
1612 if !bounds.is_empty() {
1613 format!(": {}", join_bounds(context, shape, &bound_str))
1621 if let Some(ty) = ty_opt {
1623 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1624 let lhs = format!("{}{} =", prefix, type_bounds_str);
1625 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1627 Some(format!("{}{};", prefix, type_bounds_str))
1631 pub fn rewrite_associated_impl_type(
1633 defaultness: ast::Defaultness,
1634 ty_opt: Option<&ptr::P<ast::Ty>>,
1635 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1636 context: &RewriteContext,
1638 ) -> Option<String> {
1639 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1642 ast::Defaultness::Default => Some(format!("default {}", result)),
1647 impl Rewrite for ast::FunctionRetTy {
1648 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1650 ast::FunctionRetTy::Default(_) => Some(String::new()),
1651 ast::FunctionRetTy::Ty(ref ty) => {
1652 let inner_width = shape.width.checked_sub(3)?;
1653 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1654 .map(|r| format!("-> {}", r))
1660 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1662 ast::TyKind::Infer => {
1663 let original = context.snippet(ty.span);
1670 impl Rewrite for ast::Arg {
1671 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1672 if is_named_arg(self) {
1673 let mut result = self.pat
1674 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1676 if !is_empty_infer(context, &*self.ty) {
1677 if context.config.space_before_colon() {
1678 result.push_str(" ");
1680 result.push_str(":");
1681 if context.config.space_after_colon() {
1682 result.push_str(" ");
1684 let overhead = last_line_width(&result);
1685 let max_width = shape.width.checked_sub(overhead)?;
1686 let ty_str = self.ty
1687 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1688 result.push_str(&ty_str);
1693 self.ty.rewrite(context, shape)
1698 fn rewrite_explicit_self(
1699 explicit_self: &ast::ExplicitSelf,
1701 context: &RewriteContext,
1702 ) -> Option<String> {
1703 match explicit_self.node {
1704 ast::SelfKind::Region(lt, m) => {
1705 let mut_str = format_mutability(m);
1708 let lifetime_str = l.rewrite(
1710 Shape::legacy(context.config.max_width(), Indent::empty()),
1712 Some(format!("&{} {}self", lifetime_str, mut_str))
1714 None => Some(format!("&{}self", mut_str)),
1717 ast::SelfKind::Explicit(ref ty, _) => {
1718 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1720 let mutability = explicit_self_mutability(&args[0]);
1721 let type_str = ty.rewrite(
1723 Shape::legacy(context.config.max_width(), Indent::empty()),
1728 format_mutability(mutability),
1732 ast::SelfKind::Value(_) => {
1733 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1735 let mutability = explicit_self_mutability(&args[0]);
1737 Some(format!("{}self", format_mutability(mutability)))
1742 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1743 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1744 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1745 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1752 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1753 if is_named_arg(arg) {
1760 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1762 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1763 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1764 _ => arg.ty.span.hi(),
1768 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1769 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1770 ident.node != symbol::keywords::Invalid.ident()
1776 // Return type is (result, force_new_line_for_brace)
1778 context: &RewriteContext,
1783 newline_brace: bool,
1785 ) -> Option<(String, bool)> {
1786 let mut force_new_line_for_brace = false;
1788 let where_clause = &fn_sig.generics.where_clause;
1790 let mut result = String::with_capacity(1024);
1791 result.push_str(&fn_sig.to_str(context));
1794 result.push_str("fn ");
1795 result.push_str(&ident.to_string());
1798 let overhead = if has_body && !newline_brace {
1805 let used_width = last_line_used_width(&result, indent.width());
1806 let one_line_budget = context.budget(used_width + overhead);
1808 width: one_line_budget,
1812 let fd = fn_sig.decl;
1813 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1814 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1815 result.push_str(&generics_str);
1817 let snuggle_angle_bracket = generics_str
1820 .map_or(false, |l| l.trim_left().len() == 1);
1822 // Note that the width and indent don't really matter, we'll re-layout the
1823 // return type later anyway.
1824 let ret_str = fd.output
1825 .rewrite(context, Shape::indented(indent, context.config))?;
1827 let multi_line_ret_str = ret_str.contains('\n');
1828 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1831 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1842 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1843 one_line_budget, multi_line_budget, arg_indent
1846 // Check if vertical layout was forced.
1847 if one_line_budget == 0 {
1848 if snuggle_angle_bracket {
1851 result.push_str("(");
1852 if context.config.indent_style() == IndentStyle::Visual {
1854 result.push_str(&arg_indent.to_string(context.config));
1860 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1861 && result.ends_with('(')
1866 // Skip `pub(crate)`.
1867 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1868 // A conservative estimation, to goal is to be over all parens in generics
1869 let args_start = fn_sig
1873 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1874 let args_end = if fd.inputs.is_empty() {
1877 .span_after(mk_sp(args_start, span.hi()), ")")
1879 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1880 context.codemap.span_after(last_span, ")")
1882 let args_span = mk_sp(
1885 .span_after(mk_sp(args_start, span.hi()), "("),
1888 let arg_str = rewrite_args(
1891 fd.get_self().as_ref(),
1898 generics_str.contains('\n'),
1901 let put_args_in_block = match context.config.indent_style() {
1902 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1904 } && !fd.inputs.is_empty();
1906 let mut args_last_line_contains_comment = false;
1907 if put_args_in_block {
1908 arg_indent = indent.block_indent(context.config);
1910 result.push_str(&arg_indent.to_string(context.config));
1911 result.push_str(&arg_str);
1913 result.push_str(&indent.to_string(context.config));
1916 result.push_str(&arg_str);
1917 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1918 // Put the closing brace on the next line if it overflows the max width.
1920 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1923 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1926 // If the last line of args contains comment, we cannot put the closing paren
1927 // on the same line.
1931 .map_or(false, |last_line| last_line.contains("//"))
1933 args_last_line_contains_comment = true;
1935 result.push_str(&arg_indent.to_string(context.config));
1941 if let ast::FunctionRetTy::Ty(..) = fd.output {
1942 let ret_should_indent = match context.config.indent_style() {
1943 // If our args are block layout then we surely must have space.
1944 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1945 _ if args_last_line_contains_comment => false,
1946 _ if result.contains('\n') || multi_line_ret_str => true,
1948 // If the return type would push over the max width, then put the return type on
1949 // a new line. With the +1 for the signature length an additional space between
1950 // the closing parenthesis of the argument and the arrow '->' is considered.
1951 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1953 // If there is no where clause, take into account the space after the return type
1955 if where_clause.predicates.is_empty() {
1959 sig_length > context.config.max_width()
1962 let ret_indent = if ret_should_indent {
1963 let indent = if arg_str.is_empty() {
1964 // Aligning with non-existent args looks silly.
1965 force_new_line_for_brace = true;
1968 // FIXME: we might want to check that using the arg indent
1969 // doesn't blow our budget, and if it does, then fallback to
1970 // the where clause indent.
1975 result.push_str(&indent.to_string(context.config));
1979 Indent::new(indent.block_indent, last_line_width(&result))
1982 if multi_line_ret_str || ret_should_indent {
1983 // Now that we know the proper indent and width, we need to
1984 // re-layout the return type.
1985 let ret_str = fd.output
1986 .rewrite(context, Shape::indented(ret_indent, context.config))?;
1987 result.push_str(&ret_str);
1989 result.push_str(&ret_str);
1992 // Comment between return type and the end of the decl.
1993 let snippet_lo = fd.output.span().hi();
1994 if where_clause.predicates.is_empty() {
1995 let snippet_hi = span.hi();
1996 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
1997 // Try to preserve the layout of the original snippet.
1998 let original_starts_with_newline = snippet
2000 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2001 let original_ends_with_newline = snippet
2002 .rfind(|c| c != ' ')
2003 .map_or(false, |i| snippet[i..].ends_with('\n'));
2004 let snippet = snippet.trim();
2005 if !snippet.is_empty() {
2006 result.push(if original_starts_with_newline {
2011 result.push_str(snippet);
2012 if original_ends_with_newline {
2013 force_new_line_for_brace = true;
2019 let pos_before_where = match fd.output {
2020 ast::FunctionRetTy::Default(..) => args_span.hi(),
2021 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2024 let is_args_multi_lined = arg_str.contains('\n');
2026 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2027 let where_clause_str = rewrite_where_clause(
2030 context.config.brace_style(),
2031 Shape::indented(indent, context.config),
2037 is_args_multi_lined,
2039 // If there are neither where clause nor return type, we may be missing comments between
2041 if where_clause_str.is_empty() {
2042 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2043 match recover_missing_comment_in_span(
2044 mk_sp(args_span.hi(), ret_span.hi()),
2047 last_line_width(&result),
2049 Some(ref missing_comment) if !missing_comment.is_empty() => {
2050 result.push_str(missing_comment);
2051 force_new_line_for_brace = true;
2058 result.push_str(&where_clause_str);
2060 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2061 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2062 Some((result, force_new_line_for_brace))
2065 #[derive(Copy, Clone)]
2066 struct WhereClauseOption {
2067 suppress_comma: bool, // Force no trailing comma
2068 snuggle: bool, // Do not insert newline before `where`
2069 compress_where: bool, // Try single line where clause instead of vertical layout
2072 impl WhereClauseOption {
2073 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2075 suppress_comma: suppress_comma,
2077 compress_where: false,
2081 pub fn snuggled(current: &str) -> WhereClauseOption {
2083 suppress_comma: false,
2084 snuggle: trimmed_last_line_width(current) == 1,
2085 compress_where: false,
2091 context: &RewriteContext,
2093 explicit_self: Option<&ast::ExplicitSelf>,
2094 one_line_budget: usize,
2095 multi_line_budget: usize,
2100 generics_str_contains_newline: bool,
2101 ) -> Option<String> {
2102 let mut arg_item_strs = args.iter()
2103 .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
2104 .collect::<Option<Vec<_>>>()?;
2106 // Account for sugary self.
2107 // FIXME: the comment for the self argument is dropped. This is blocked
2108 // on rust issue #27522.
2109 let min_args = explicit_self
2110 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2111 .map_or(1, |self_str| {
2112 arg_item_strs[0] = self_str;
2116 // Comments between args.
2117 let mut arg_items = Vec::new();
2119 arg_items.push(ListItem::from_str(""));
2122 // FIXME(#21): if there are no args, there might still be a comment, but
2123 // without spans for the comment or parens, there is no chance of
2124 // getting it right. You also don't get to put a comment on self, unless
2126 if args.len() >= min_args || variadic {
2127 let comment_span_start = if min_args == 2 {
2128 let second_arg_start = if arg_has_pattern(&args[1]) {
2129 args[1].pat.span.lo()
2131 args[1].ty.span.lo()
2133 let reduced_span = mk_sp(span.lo(), second_arg_start);
2135 context.codemap.span_after_last(reduced_span, ",")
2140 enum ArgumentKind<'a> {
2141 Regular(&'a ast::Arg),
2145 let variadic_arg = if variadic {
2146 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2147 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2148 Some(ArgumentKind::Variadic(variadic_start))
2153 let more_items = itemize_list(
2155 args[min_args - 1..]
2157 .map(ArgumentKind::Regular)
2158 .chain(variadic_arg),
2162 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2163 ArgumentKind::Variadic(start) => start,
2166 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2167 ArgumentKind::Variadic(start) => start + BytePos(3),
2170 ArgumentKind::Regular(..) => None,
2171 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2178 arg_items.extend(more_items);
2181 let fits_in_one_line = !generics_str_contains_newline
2182 && (arg_items.is_empty()
2183 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2185 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2186 item.item = Some(arg);
2189 let last_line_ends_with_comment = arg_items
2192 .and_then(|item| item.post_comment.as_ref())
2193 .map_or(false, |s| s.trim().starts_with("//"));
2195 let (indent, trailing_comma) = match context.config.indent_style() {
2196 IndentStyle::Block if fits_in_one_line => {
2197 (indent.block_indent(context.config), SeparatorTactic::Never)
2199 IndentStyle::Block => (
2200 indent.block_indent(context.config),
2201 context.config.trailing_comma(),
2203 IndentStyle::Visual if last_line_ends_with_comment => {
2204 (arg_indent, context.config.trailing_comma())
2206 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2209 let tactic = definitive_tactic(
2211 context.config.fn_args_density().to_list_tactic(),
2215 let budget = match tactic {
2216 DefinitiveListTactic::Horizontal => one_line_budget,
2217 _ => multi_line_budget,
2220 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2222 let fmt = ListFormatting {
2225 trailing_separator: if variadic {
2226 SeparatorTactic::Never
2230 separator_place: SeparatorPlace::Back,
2231 shape: Shape::legacy(budget, indent),
2232 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2233 preserve_newline: true,
2234 config: context.config,
2237 write_list(&arg_items, &fmt)
2240 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2241 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2242 ident.node != symbol::keywords::Invalid.ident()
2248 fn compute_budgets_for_args(
2249 context: &RewriteContext,
2253 newline_brace: bool,
2255 force_vertical_layout: bool,
2256 ) -> Option<((usize, usize, Indent))> {
2258 "compute_budgets_for_args {} {:?}, {}, {}",
2264 // Try keeping everything on the same line.
2265 if !result.contains('\n') && !force_vertical_layout {
2266 // 2 = `()`, 3 = `() `, space is before ret_string.
2267 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2268 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2278 let one_line_budget = context.budget(used_space);
2280 if one_line_budget > 0 {
2282 let (indent, multi_line_budget) = match context.config.indent_style() {
2283 IndentStyle::Block => {
2284 let indent = indent.block_indent(context.config);
2285 (indent, context.budget(indent.width() + 1))
2287 IndentStyle::Visual => {
2288 let indent = indent + result.len() + 1;
2289 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2290 (indent, context.budget(multi_line_overhead))
2294 return Some((one_line_budget, multi_line_budget, indent));
2298 // Didn't work. we must force vertical layout and put args on a newline.
2299 let new_indent = indent.block_indent(context.config);
2300 let used_space = match context.config.indent_style() {
2302 IndentStyle::Block => new_indent.width() + 1,
2303 // Account for `)` and possibly ` {`.
2304 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2306 Some((0, context.budget(used_space), new_indent))
2309 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2310 let predicate_count = where_clause.predicates.len();
2312 if config.where_single_line() && predicate_count == 1 {
2315 let brace_style = config.brace_style();
2317 brace_style == BraceStyle::AlwaysNextLine
2318 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2321 fn rewrite_generics(
2322 context: &RewriteContext,
2323 generics: &ast::Generics,
2326 ) -> Option<String> {
2327 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2328 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2329 rewrite_generics_inner(context, generics, g_shape, one_line_width, span)
2330 .or_else(|| rewrite_generics_inner(context, generics, g_shape, 0, span))
2333 fn rewrite_generics_inner(
2334 context: &RewriteContext,
2335 generics: &ast::Generics,
2337 one_line_width: usize,
2339 ) -> Option<String> {
2340 // FIXME: convert bounds to where clauses where they get too big or if
2341 // there is a where clause at all.
2344 enum GenericsArg<'a> {
2345 Lifetime(&'a ast::LifetimeDef),
2346 TyParam(&'a ast::TyParam),
2348 impl<'a> Rewrite for GenericsArg<'a> {
2349 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2351 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2352 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2356 impl<'a> Spanned for GenericsArg<'a> {
2357 fn span(&self) -> Span {
2359 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2360 GenericsArg::TyParam(ty) => ty.span(),
2365 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2366 return Some(String::new());
2369 let generics_args = generics
2372 .map(|lt| GenericsArg::Lifetime(lt))
2373 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2374 let items = itemize_list(
2379 |arg| arg.span().lo(),
2380 |arg| arg.span().hi(),
2381 |arg| arg.rewrite(context, shape),
2382 context.codemap.span_after(span, "<"),
2386 format_generics_item_list(context, items, shape, one_line_width)
2389 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2390 match config.indent_style() {
2391 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2392 IndentStyle::Block => {
2396 .block_indent(config.tab_spaces())
2397 .with_max_width(config)
2403 pub fn format_generics_item_list<I>(
2404 context: &RewriteContext,
2407 one_line_budget: usize,
2410 I: Iterator<Item = ListItem>,
2412 let item_vec = items.collect::<Vec<_>>();
2414 let tactic = definitive_tactic(
2416 ListTactic::HorizontalVertical,
2420 let fmt = ListFormatting {
2423 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2424 SeparatorTactic::Never
2426 context.config.trailing_comma()
2428 separator_place: SeparatorPlace::Back,
2430 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2431 preserve_newline: true,
2432 config: context.config,
2435 let list_str = write_list(&item_vec, &fmt)?;
2437 Some(wrap_generics_with_angle_brackets(
2444 pub fn wrap_generics_with_angle_brackets(
2445 context: &RewriteContext,
2447 list_offset: Indent,
2449 if context.config.indent_style() == IndentStyle::Block
2450 && (list_str.contains('\n') || list_str.ends_with(','))
2454 list_offset.to_string(context.config),
2457 .block_unindent(context.config)
2458 .to_string(context.config)
2460 } else if context.config.spaces_within_parens_and_brackets() {
2461 format!("< {} >", list_str)
2463 format!("<{}>", list_str)
2467 fn rewrite_trait_bounds(
2468 context: &RewriteContext,
2469 bounds: &[ast::TyParamBound],
2471 ) -> Option<String> {
2472 if bounds.is_empty() {
2473 return Some(String::new());
2475 let bound_str = bounds
2477 .map(|ty_bound| ty_bound.rewrite(context, shape))
2478 .collect::<Option<Vec<_>>>()?;
2479 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2482 fn rewrite_where_clause_rfc_style(
2483 context: &RewriteContext,
2484 where_clause: &ast::WhereClause,
2487 span_end: Option<BytePos>,
2488 span_end_before_where: BytePos,
2489 where_clause_option: WhereClauseOption,
2490 is_args_multi_line: bool,
2491 ) -> Option<String> {
2492 let block_shape = shape.block().with_max_width(context.config);
2494 let (span_before, span_after) =
2495 missing_span_before_after_where(span_end_before_where, where_clause);
2496 let (comment_before, comment_after) =
2497 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2499 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2502 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2505 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2507 let clause_shape = clause_shape.sub_width(1)?;
2508 // each clause on one line, trailing comma (except if suppress_comma)
2509 let span_start = where_clause.predicates[0].span().lo();
2510 // If we don't have the start of the next span, then use the end of the
2511 // predicates, but that means we miss comments.
2512 let len = where_clause.predicates.len();
2513 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2514 let span_end = span_end.unwrap_or(end_of_preds);
2515 let items = itemize_list(
2517 where_clause.predicates.iter(),
2520 |pred| pred.span().lo(),
2521 |pred| pred.span().hi(),
2522 |pred| pred.rewrite(context, clause_shape),
2527 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2528 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2529 SeparatorTactic::Never
2531 context.config.trailing_comma()
2534 // shape should be vertical only and only if we have `where_single_line` option enabled
2535 // and the number of items of the where clause is equal to 1
2536 let shape_tactic = if where_single_line {
2537 DefinitiveListTactic::Horizontal
2539 DefinitiveListTactic::Vertical
2542 let fmt = ListFormatting {
2543 tactic: shape_tactic,
2545 trailing_separator: comma_tactic,
2546 separator_place: SeparatorPlace::Back,
2547 shape: clause_shape,
2548 ends_with_newline: true,
2549 preserve_newline: true,
2550 config: context.config,
2552 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2554 let comment_separator = |comment: &str, shape: Shape| {
2555 if comment.is_empty() {
2558 format!("\n{}", shape.indent.to_string(context.config))
2561 let newline_before_where = comment_separator(&comment_before, shape);
2562 let newline_after_where = comment_separator(&comment_after, clause_shape);
2565 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2566 && comment_after.is_empty() && !preds_str.contains('\n')
2567 && 6 + preds_str.len() <= shape.width || where_single_line
2571 format!("\n{}", clause_shape.indent.to_string(context.config))
2574 "{}{}{}where{}{}{}{}",
2577 newline_before_where,
2578 newline_after_where,
2585 fn rewrite_where_clause(
2586 context: &RewriteContext,
2587 where_clause: &ast::WhereClause,
2588 brace_style: BraceStyle,
2592 span_end: Option<BytePos>,
2593 span_end_before_where: BytePos,
2594 where_clause_option: WhereClauseOption,
2595 is_args_multi_line: bool,
2596 ) -> Option<String> {
2597 if where_clause.predicates.is_empty() {
2598 return Some(String::new());
2601 if context.config.indent_style() == IndentStyle::Block {
2602 return rewrite_where_clause_rfc_style(
2608 span_end_before_where,
2609 where_clause_option,
2614 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2616 let offset = match context.config.indent_style() {
2617 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2618 // 6 = "where ".len()
2619 IndentStyle::Visual => shape.indent + extra_indent + 6,
2621 // FIXME: if indent_style != Visual, then the budgets below might
2622 // be out by a char or two.
2624 let budget = context.config.max_width() - offset.width();
2625 let span_start = where_clause.predicates[0].span().lo();
2626 // If we don't have the start of the next span, then use the end of the
2627 // predicates, but that means we miss comments.
2628 let len = where_clause.predicates.len();
2629 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2630 let span_end = span_end.unwrap_or(end_of_preds);
2631 let items = itemize_list(
2633 where_clause.predicates.iter(),
2636 |pred| pred.span().lo(),
2637 |pred| pred.span().hi(),
2638 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2643 let item_vec = items.collect::<Vec<_>>();
2644 // FIXME: we don't need to collect here
2645 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2647 let mut comma_tactic = context.config.trailing_comma();
2648 // Kind of a hack because we don't usually have trailing commas in where clauses.
2649 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2650 comma_tactic = SeparatorTactic::Never;
2653 let fmt = ListFormatting {
2656 trailing_separator: comma_tactic,
2657 separator_place: SeparatorPlace::Back,
2658 shape: Shape::legacy(budget, offset),
2659 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2660 preserve_newline: true,
2661 config: context.config,
2663 let preds_str = write_list(&item_vec, &fmt)?;
2665 let end_length = if terminator == "{" {
2666 // If the brace is on the next line we don't need to count it otherwise it needs two
2669 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2670 BraceStyle::PreferSameLine => 2,
2672 } else if terminator == "=" {
2677 if density == Density::Tall || preds_str.contains('\n')
2678 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2682 (shape.indent + extra_indent).to_string(context.config),
2686 Some(format!(" where {}", preds_str))
2690 fn missing_span_before_after_where(
2691 before_item_span_end: BytePos,
2692 where_clause: &ast::WhereClause,
2694 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2696 let pos_after_where = where_clause.span.lo() + BytePos(5);
2697 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2698 (missing_span_before, missing_span_after)
2701 fn rewrite_comments_before_after_where(
2702 context: &RewriteContext,
2703 span_before_where: Span,
2704 span_after_where: Span,
2706 ) -> Option<(String, String)> {
2707 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2708 let after_comment = rewrite_missing_comment(
2710 shape.block_indent(context.config.tab_spaces()),
2713 Some((before_comment, after_comment))
2716 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2717 format!("{}{}{}", format_visibility(vis), item_name, ident)
2720 #[derive(PartialEq, Eq)]
2728 context: &RewriteContext,
2729 generics: &ast::Generics,
2730 brace_style: BraceStyle,
2731 brace_pos: BracePos,
2735 ) -> Option<String> {
2736 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2737 let mut result = rewrite_generics(context, generics, shape, span)?;
2739 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2740 let budget = context.budget(last_line_used_width(&result, offset.width()));
2741 let mut option = WhereClauseOption::snuggled(&result);
2742 if brace_pos == BracePos::None {
2743 option.suppress_comma = true;
2745 // If the generics are not parameterized then generics.span.hi() == 0,
2746 // so we use span.lo(), which is the position after `struct Foo`.
2747 let span_end_before_where = if generics.is_parameterized() {
2752 let where_clause_str = rewrite_where_clause(
2754 &generics.where_clause,
2756 Shape::legacy(budget, offset.block_only()),
2760 span_end_before_where,
2764 result.push_str(&where_clause_str);
2765 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2766 || (generics.where_clause.predicates.is_empty()
2767 && trimmed_last_line_width(&result) == 1)
2769 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2770 || brace_style != BraceStyle::AlwaysNextLine
2772 if brace_pos == BracePos::None {
2773 return Some(result);
2775 let total_used_width = last_line_used_width(&result, used_width);
2776 let remaining_budget = context.budget(total_used_width);
2777 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2778 // and hence we take the closer into account as well for one line budget.
2779 // We assume that the closer has the same length as the opener.
2780 let overhead = if brace_pos == BracePos::ForceSameLine {
2787 let forbid_same_line_brace = overhead > remaining_budget;
2788 if !forbid_same_line_brace && same_line_brace {
2792 result.push_str(&offset.block_only().to_string(context.config));
2799 impl Rewrite for ast::ForeignItem {
2800 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2801 let attrs_str = self.attrs.rewrite(context, shape)?;
2802 // Drop semicolon or it will be interpreted as comment.
2803 // FIXME: this may be a faulty span from libsyntax.
2804 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2806 let item_str = match self.node {
2807 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2812 &FnSig::new(fn_decl, generics, self.vis.clone()),
2816 ).map(|(s, _)| format!("{};", s))
2818 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2819 // FIXME(#21): we're dropping potential comments in between the
2820 // function keywords here.
2821 let vis = format_visibility(&self.vis);
2822 let mut_str = if is_mutable { "mut " } else { "" };
2823 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2825 let shape = shape.sub_width(1)?;
2826 ty.rewrite(context, shape).map(|ty_str| {
2827 // 1 = space between prefix and type.
2828 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2831 let nested_indent = shape.indent.block_indent(context.config);
2832 format!("\n{}", nested_indent.to_string(context.config))
2834 format!("{}{}{};", prefix, sep, ty_str)
2837 ast::ForeignItemKind::Ty => {
2838 let vis = format_visibility(&self.vis);
2839 Some(format!("{}type {};", vis, self.ident))
2843 let missing_span = if self.attrs.is_empty() {
2844 mk_sp(self.span.lo(), self.span.lo())
2846 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2848 combine_strs_with_missing_comments(