1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Formatting top-level items - functions, structs, enums, traits, impls.
14 use std::cmp::{min, Ordering};
17 use rustc_target::spec::abi;
18 use syntax::source_map::{self, BytePos, Span};
20 use syntax::{ast, ptr, symbol};
23 combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
24 recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented,
26 use crate::config::lists::*;
27 use crate::config::{BraceStyle, Config, Density, IndentStyle, Version};
29 format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs, rewrite_assign_rhs_with,
33 definitive_tactic, itemize_list, write_list, ListFormatting, ListItem, Separator,
35 use crate::macros::{rewrite_macro, MacroPosition};
37 use crate::rewrite::{Rewrite, RewriteContext};
38 use crate::shape::{Indent, Shape};
39 use crate::source_map::{LineRangeUtils, SpanUtils};
40 use crate::spanned::Spanned;
42 use crate::vertical::rewrite_with_alignment;
43 use crate::visitor::FmtVisitor;
45 const DEFAULT_VISIBILITY: ast::Visibility = source_map::Spanned {
46 node: ast::VisibilityKind::Inherited,
47 span: source_map::DUMMY_SP,
50 fn type_annotation_separator(config: &Config) -> &str {
51 colon_spaces(config.space_before_colon(), config.space_after_colon())
54 // Statements of the form
55 // let pat: ty = init;
56 impl Rewrite for ast::Local {
57 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
59 "Local::rewrite {:?} {} {:?}",
60 self, shape.width, shape.indent
63 skip_out_of_file_lines_range!(context, self.span);
65 if contains_skip(&self.attrs) {
69 let attrs_str = self.attrs.rewrite(context, shape)?;
70 let mut result = if attrs_str.is_empty() {
73 combine_strs_with_missing_comments(
78 self.attrs.last().map(|a| a.span.hi()).unwrap(),
87 let pat_shape = shape.offset_left(4)?;
89 let pat_shape = pat_shape.sub_width(1)?;
90 let pat_str = self.pat.rewrite(context, pat_shape)?;
91 result.push_str(&pat_str);
93 // String that is placed within the assignment pattern and expression.
95 let mut infix = String::with_capacity(32);
97 if let Some(ref ty) = self.ty {
98 let separator = type_annotation_separator(context.config);
99 let ty_shape = if pat_str.contains('\n') {
100 shape.with_max_width(context.config)
104 .offset_left(last_line_width(&result) + separator.len())?
108 let rewrite = ty.rewrite(context, ty_shape)?;
110 infix.push_str(separator);
111 infix.push_str(&rewrite);
114 if self.init.is_some() {
115 infix.push_str(" =");
121 result.push_str(&infix);
123 if let Some(ref ex) = self.init {
124 // 1 = trailing semicolon;
125 let nested_shape = shape.sub_width(1)?;
127 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
135 // FIXME convert to using rewrite style rather than visitor
136 // FIXME format modules in this style
139 keyword: &'static str,
140 abi: Cow<'static, str>,
141 vis: Option<&'a ast::Visibility>,
142 body: Vec<BodyElement<'a>>,
147 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
150 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
155 .map(|i| BodyElement::ForeignItem(i))
162 enum BodyElement<'a> {
163 // Stmt(&'a ast::Stmt),
164 // Field(&'a ast::Field),
165 // Variant(&'a ast::Variant),
166 // Item(&'a ast::Item),
167 ForeignItem(&'a ast::ForeignItem),
170 /// Represents a fn's signature.
171 pub struct FnSig<'a> {
172 decl: &'a ast::FnDecl,
173 generics: &'a ast::Generics,
175 is_async: ast::IsAsync,
176 constness: ast::Constness,
177 defaultness: ast::Defaultness,
178 unsafety: ast::Unsafety,
179 visibility: ast::Visibility,
184 decl: &'a ast::FnDecl,
185 generics: &'a ast::Generics,
186 vis: ast::Visibility,
192 is_async: ast::IsAsync::NotAsync,
193 constness: ast::Constness::NotConst,
194 defaultness: ast::Defaultness::Final,
195 unsafety: ast::Unsafety::Normal,
200 pub fn from_method_sig(
201 method_sig: &'a ast::MethodSig,
202 generics: &'a ast::Generics,
205 unsafety: method_sig.header.unsafety,
206 is_async: method_sig.header.asyncness,
207 constness: method_sig.header.constness.node,
208 defaultness: ast::Defaultness::Final,
209 abi: method_sig.header.abi,
210 decl: &*method_sig.decl,
212 visibility: DEFAULT_VISIBILITY,
217 fn_kind: &'a visit::FnKind<'_>,
218 generics: &'a ast::Generics,
219 decl: &'a ast::FnDecl,
220 defaultness: ast::Defaultness,
223 visit::FnKind::ItemFn(_, fn_header, visibility, _) => FnSig {
227 constness: fn_header.constness.node,
228 is_async: fn_header.asyncness,
230 unsafety: fn_header.unsafety,
231 visibility: visibility.clone(),
233 visit::FnKind::Method(_, method_sig, vis, _) => {
234 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
235 fn_sig.defaultness = defaultness;
236 if let Some(vis) = vis {
237 fn_sig.visibility = vis.clone();
245 fn to_str(&self, context: &RewriteContext<'_>) -> String {
246 let mut result = String::with_capacity(128);
247 // Vis defaultness constness unsafety abi.
248 result.push_str(&*format_visibility(context, &self.visibility));
249 result.push_str(format_defaultness(self.defaultness));
250 result.push_str(format_constness(self.constness));
251 result.push_str(format_unsafety(self.unsafety));
252 result.push_str(format_async(self.is_async));
253 result.push_str(&format_abi(
255 context.config.force_explicit_abi(),
262 impl<'a> FmtVisitor<'a> {
263 fn format_item(&mut self, item: &Item<'_>) {
264 self.buffer.push_str(&item.abi);
266 let snippet = self.snippet(item.span);
267 let brace_pos = snippet.find_uncommented("{").unwrap();
270 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
271 // FIXME: this skips comments between the extern keyword and the opening
273 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
274 self.block_indent = self.block_indent.block_indent(self.config);
276 if item.body.is_empty() {
277 self.format_missing_no_indent(item.span.hi() - BytePos(1));
278 self.block_indent = self.block_indent.block_unindent(self.config);
279 let indent_str = self.block_indent.to_string(self.config);
280 self.push_str(&indent_str);
282 for item in &item.body {
283 self.format_body_element(item);
286 self.block_indent = self.block_indent.block_unindent(self.config);
287 self.format_missing_with_indent(item.span.hi() - BytePos(1));
292 self.last_pos = item.span.hi();
295 fn format_body_element(&mut self, element: &BodyElement<'_>) {
297 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
301 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
302 let item = Item::from_foreign_mod(fm, span, self.config);
303 self.format_item(&item);
306 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
307 let rewrite = item.rewrite(&self.get_context(), self.shape());
308 self.push_rewrite(item.span(), rewrite);
309 self.last_pos = item.span.hi();
319 inner_attrs: Option<&[ast::Attribute]>,
320 ) -> Option<String> {
321 let context = self.get_context();
323 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
325 let (mut result, force_newline_brace) =
326 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
329 if self.config.brace_style() == BraceStyle::AlwaysNextLine
330 || force_newline_brace
331 || last_line_width(&result) + 2 > self.shape().width
333 newline_brace = true;
334 } else if !result.contains('\n') {
335 newline_brace = false;
338 if let rw @ Some(..) = self.single_line_fn(&result, block, inner_attrs) {
341 // Prepare for the function body by possibly adding a newline and
343 // FIXME we'll miss anything between the end of the signature and the
344 // start of the body, but we need more spans from the compiler to solve
347 result.push_str(&indent.to_string_with_newline(self.config));
355 pub fn rewrite_required_fn(
359 sig: &ast::MethodSig,
360 generics: &ast::Generics,
362 ) -> Option<String> {
363 // Drop semicolon or it will be interpreted as comment.
364 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
365 let context = self.get_context();
367 let (mut result, _) = rewrite_fn_base(
371 &FnSig::from_method_sig(sig, generics),
377 // Re-attach semicolon
387 inner_attrs: Option<&[ast::Attribute]>,
388 ) -> Option<String> {
389 if fn_str.contains('\n') || inner_attrs.map_or(false, |a| !a.is_empty()) {
393 let source_map = self.get_context().source_map;
395 if self.config.empty_item_single_line()
396 && is_empty_block(block, None, source_map)
397 && self.block_indent.width() + fn_str.len() + 3 <= self.config.max_width()
398 && !last_line_contains_single_line_comment(fn_str)
400 return Some(format!("{} {{}}", fn_str));
403 if !self.config.fn_single_line() || !is_simple_block_stmt(block, None, source_map) {
407 let stmt = block.stmts.first()?;
408 let res = match stmt_expr(stmt) {
410 let suffix = if semicolon_for_expr(&self.get_context(), e) {
416 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
417 .map(|s| s + suffix)?
419 None => stmt.rewrite(&self.get_context(), self.shape())?,
422 let width = self.block_indent.width() + fn_str.len() + res.len() + 5;
423 if !res.contains('\n') && width <= self.config.max_width() {
424 Some(format!("{} {{ {} }}", fn_str, res))
430 pub fn visit_static(&mut self, static_parts: &StaticParts<'_>) {
431 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
432 self.push_rewrite(static_parts.span, rewrite);
435 pub fn visit_struct(&mut self, struct_parts: &StructParts<'_>) {
436 let is_tuple = struct_parts.def.is_tuple();
437 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
438 .map(|s| if is_tuple { s + ";" } else { s });
439 self.push_rewrite(struct_parts.span, rewrite);
445 vis: &ast::Visibility,
446 enum_def: &ast::EnumDef,
447 generics: &ast::Generics,
450 let enum_header = format_header(&self.get_context(), "enum ", ident, vis);
451 self.push_str(&enum_header);
453 let enum_snippet = self.snippet(span);
454 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
455 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
456 let generics_str = format_generics(
459 self.config.brace_style(),
460 if enum_def.variants.is_empty() {
461 BracePos::ForceSameLine
466 // make a span that starts right after `enum Foo`
467 mk_sp(ident.span.hi(), body_start),
468 last_line_width(&enum_header),
471 self.push_str(&generics_str);
473 self.last_pos = body_start;
475 match self.format_variant_list(enum_def, body_start, span.hi()) {
476 Some(ref s) if enum_def.variants.is_empty() => self.push_str(s),
478 self.push_rewrite(mk_sp(body_start, span.hi()), rw);
479 self.block_indent = self.block_indent.block_unindent(self.config);
484 // Format the body of an enum definition
485 fn format_variant_list(
487 enum_def: &ast::EnumDef,
490 ) -> Option<String> {
491 if enum_def.variants.is_empty() {
492 let mut buffer = String::with_capacity(128);
494 let span = mk_sp(body_lo, body_hi - BytePos(1));
495 format_empty_struct_or_tuple(
505 let mut result = String::with_capacity(1024);
506 let original_offset = self.block_indent;
507 self.block_indent = self.block_indent.block_indent(self.config);
509 // If enum variants have discriminants, try to vertically align those,
510 // provided the discrims are not shifted too much to the right
511 let align_threshold: usize = self.config.enum_discrim_align_threshold();
512 let discr_ident_lens: Vec<usize> = enum_def
515 .filter(|var| var.node.disr_expr.is_some())
516 .map(|var| rewrite_ident(&self.get_context(), var.node.ident).len())
518 // cut the list at the point of longest discrim shorter than the threshold
519 // All of the discrims under the threshold will get padded, and all above - left as is.
520 let pad_discrim_ident_to = *discr_ident_lens
522 .filter(|&l| *l <= align_threshold)
526 let itemize_list_with = |one_line_width: usize| {
528 self.snippet_provider,
529 enum_def.variants.iter(),
533 if !f.node.attrs.is_empty() {
534 f.node.attrs[0].span.lo()
540 |f| self.format_variant(f, one_line_width, pad_discrim_ident_to),
547 let mut items: Vec<_> =
548 itemize_list_with(self.config.width_heuristics().struct_variant_width);
549 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
550 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
551 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
552 if has_multiline_variant && has_single_line_variant {
553 items = itemize_list_with(0);
556 let shape = self.shape().sub_width(2)?;
557 let fmt = ListFormatting::new(shape, self.config)
558 .trailing_separator(self.config.trailing_comma())
559 .preserve_newline(true);
561 let list = write_list(&items, &fmt)?;
562 result.push_str(&list);
563 result.push_str(&original_offset.to_string_with_newline(self.config));
568 // Variant of an enum.
571 field: &ast::Variant,
572 one_line_width: usize,
573 pad_discrim_ident_to: usize,
574 ) -> Option<String> {
575 if contains_skip(&field.node.attrs) {
576 let lo = field.node.attrs[0].span.lo();
577 let span = mk_sp(lo, field.span.hi());
578 return Some(self.snippet(span).to_owned());
581 let context = self.get_context();
583 let shape = self.shape().sub_width(1)?;
584 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
589 .map_or(field.span.lo(), |attr| attr.span.hi());
590 let span = mk_sp(lo, field.span.lo());
592 let variant_body = match field.node.data {
593 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
595 &StructParts::from_variant(field),
597 Some(one_line_width),
599 ast::VariantData::Unit(..) => {
600 if let Some(ref expr) = field.node.disr_expr {
603 rewrite_ident(&context, field.node.ident),
606 rewrite_assign_rhs(&context, lhs, &*expr.value, shape)?
608 rewrite_ident(&context, field.node.ident).to_owned()
613 combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
616 fn visit_impl_items(&mut self, items: &[ast::ImplItem]) {
617 if self.get_context().config.reorder_impl_items() {
618 // Create visitor for each items, then reorder them.
619 let mut buffer = vec![];
621 self.visit_impl_item(item);
622 buffer.push((self.buffer.clone(), item.clone()));
625 // type -> existential -> const -> macro -> method
626 use crate::ast::ImplItemKind::*;
627 fn need_empty_line(a: &ast::ImplItemKind, b: &ast::ImplItemKind) -> bool {
630 | (Const(..), Const(..))
631 | (Existential(..), Existential(..)) => false,
636 buffer.sort_by(|(_, a), (_, b)| match (&a.node, &b.node) {
638 | (Const(..), Const(..))
639 | (Macro(..), Macro(..))
640 | (Existential(..), Existential(..)) => a.ident.as_str().cmp(&b.ident.as_str()),
641 (Method(..), Method(..)) => a.span.lo().cmp(&b.span.lo()),
642 (Type(..), _) => Ordering::Less,
643 (_, Type(..)) => Ordering::Greater,
644 (Existential(..), _) => Ordering::Less,
645 (_, Existential(..)) => Ordering::Greater,
646 (Const(..), _) => Ordering::Less,
647 (_, Const(..)) => Ordering::Greater,
648 (Macro(..), _) => Ordering::Less,
649 (_, Macro(..)) => Ordering::Greater,
651 let mut prev_kind = None;
652 for (buf, item) in buffer {
653 // Make sure that there are at least a single empty line between
654 // different impl items.
657 .map_or(false, |prev_kind| need_empty_line(prev_kind, &item.node))
661 let indent_str = self.block_indent.to_string_with_newline(self.config);
662 self.push_str(&indent_str);
663 self.push_str(buf.trim());
664 prev_kind = Some(item.node.clone());
668 self.visit_impl_item(item);
675 context: &RewriteContext<'_>,
678 where_span_end: Option<BytePos>,
679 ) -> Option<String> {
680 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
681 let mut result = String::with_capacity(128);
682 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
683 let sep = offset.to_string_with_newline(context.config);
684 result.push_str(&ref_and_type);
686 let where_budget = if result.contains('\n') {
687 context.config.max_width()
689 context.budget(last_line_width(&result))
692 let mut option = WhereClauseOption::snuggled(&ref_and_type);
693 let snippet = context.snippet(item.span);
694 let open_pos = snippet.find_uncommented("{")? + 1;
695 if !contains_comment(&snippet[open_pos..])
697 && generics.where_clause.predicates.len() == 1
698 && !result.contains('\n')
700 option.suppress_comma();
702 option.compress_where();
705 let where_clause_str = rewrite_where_clause(
707 &generics.where_clause,
708 context.config.brace_style(),
709 Shape::legacy(where_budget, offset.block_only()),
718 // If there is no where clause, we may have missing comments between the trait name and
719 // the opening brace.
720 if generics.where_clause.predicates.is_empty() {
721 if let Some(hi) = where_span_end {
722 match recover_missing_comment_in_span(
723 mk_sp(self_ty.span.hi(), hi),
724 Shape::indented(offset, context.config),
726 last_line_width(&result),
728 Some(ref missing_comment) if !missing_comment.is_empty() => {
729 result.push_str(missing_comment);
736 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
737 result.push_str(&where_clause_str);
738 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
739 // if the where_clause contains extra comments AND
740 // there is only one where clause predicate
741 // recover the suppressed comma in single line where_clause formatting
742 if generics.where_clause.predicates.len() == 1 {
743 result.push_str(",");
745 result.push_str(&format!("{}{{{}}}", &sep, &sep));
747 result.push_str(" {}");
752 result.push_str(&where_clause_str);
754 let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
755 match context.config.brace_style() {
756 _ if need_newline => result.push_str(&sep),
757 BraceStyle::AlwaysNextLine => result.push_str(&sep),
758 BraceStyle::PreferSameLine => result.push(' '),
759 BraceStyle::SameLineWhere => {
760 if !where_clause_str.is_empty() {
761 result.push_str(&sep);
770 let snippet = context.snippet(item.span);
771 let open_pos = snippet.find_uncommented("{")? + 1;
773 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
774 let mut visitor = FmtVisitor::from_context(context);
775 let item_indent = offset.block_only().block_indent(context.config);
776 visitor.block_indent = item_indent;
777 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
779 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
780 visitor.visit_impl_items(items);
782 visitor.format_missing(item.span.hi() - BytePos(1));
784 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
785 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
787 result.push_str(&inner_indent_str);
788 result.push_str(visitor.buffer.trim());
789 result.push_str(&outer_indent_str);
790 } else if need_newline || !context.config.empty_item_single_line() {
791 result.push_str(&sep);
802 fn is_impl_single_line(
803 context: &RewriteContext<'_>,
804 items: &[ast::ImplItem],
806 where_clause_str: &str,
809 let snippet = context.snippet(item.span);
810 let open_pos = snippet.find_uncommented("{")? + 1;
813 context.config.empty_item_single_line()
815 && !result.contains('\n')
816 && result.len() + where_clause_str.len() <= context.config.max_width()
817 && !contains_comment(&snippet[open_pos..]),
821 fn format_impl_ref_and_type(
822 context: &RewriteContext<'_>,
825 ) -> Option<String> {
826 if let ast::ItemKind::Impl(
836 let mut result = String::with_capacity(128);
838 result.push_str(&format_visibility(context, &item.vis));
839 result.push_str(format_defaultness(defaultness));
840 result.push_str(format_unsafety(unsafety));
842 let shape = generics_shape_from_config(
844 Shape::indented(offset + last_line_width(&result), context.config),
847 let generics_str = rewrite_generics(context, "impl", generics, shape)?;
848 result.push_str(&generics_str);
850 let polarity_str = if polarity == ast::ImplPolarity::Negative {
856 if let Some(ref trait_ref) = *trait_ref {
857 let result_len = last_line_width(&result);
858 result.push_str(&rewrite_trait_ref(
867 // Try to put the self type in a single line.
869 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
870 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
871 // If there is no where clause adapt budget for type formatting to take space and curly
872 // brace into account.
873 match context.config.brace_style() {
874 BraceStyle::AlwaysNextLine => 0,
880 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
881 // 1 = space before the type.
882 let budget = context.budget(used_space + 1);
883 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
884 if !self_ty_str.contains('\n') {
885 if trait_ref.is_some() {
886 result.push_str(" for ");
890 result.push_str(&self_ty_str);
895 // Couldn't fit the self type on a single line, put it on a new line.
897 // Add indentation of one additional tab.
898 let new_line_offset = offset.block_indent(context.config);
899 result.push_str(&new_line_offset.to_string(context.config));
900 if trait_ref.is_some() {
901 result.push_str("for ");
903 let budget = context.budget(last_line_width(&result));
904 let type_offset = match context.config.indent_style() {
905 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
906 IndentStyle::Block => new_line_offset,
908 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
915 fn rewrite_trait_ref(
916 context: &RewriteContext<'_>,
917 trait_ref: &ast::TraitRef,
921 ) -> Option<String> {
922 // 1 = space between generics and trait_ref
923 let used_space = 1 + polarity_str.len() + result_len;
924 let shape = Shape::indented(offset + used_space, context.config);
925 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
926 if !trait_ref_str.contains('\n') {
927 return Some(format!(" {}{}", polarity_str, &trait_ref_str));
930 // We could not make enough space for trait_ref, so put it on new line.
931 let offset = offset.block_indent(context.config);
932 let shape = Shape::indented(offset, context.config);
933 let trait_ref_str = trait_ref.rewrite(context, shape)?;
936 &offset.to_string_with_newline(context.config),
942 pub struct StructParts<'a> {
945 vis: &'a ast::Visibility,
946 def: &'a ast::VariantData,
947 generics: Option<&'a ast::Generics>,
951 impl<'a> StructParts<'a> {
952 fn format_header(&self, context: &RewriteContext<'_>) -> String {
953 format_header(context, self.prefix, self.ident, self.vis)
956 fn from_variant(variant: &'a ast::Variant) -> Self {
959 ident: variant.node.ident,
960 vis: &DEFAULT_VISIBILITY,
961 def: &variant.node.data,
967 pub fn from_item(item: &'a ast::Item) -> Self {
968 let (prefix, def, generics) = match item.node {
969 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
970 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
978 generics: Some(generics),
985 context: &RewriteContext<'_>,
986 struct_parts: &StructParts<'_>,
988 one_line_width: Option<usize>,
989 ) -> Option<String> {
990 match *struct_parts.def {
991 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
992 ast::VariantData::Tuple(ref fields, _) => {
993 format_tuple_struct(context, struct_parts, fields, offset)
995 ast::VariantData::Struct(ref fields, _) => {
996 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
1001 pub fn format_trait(
1002 context: &RewriteContext<'_>,
1005 ) -> Option<String> {
1006 if let ast::ItemKind::Trait(
1014 let mut result = String::with_capacity(128);
1015 let header = format!(
1017 format_visibility(context, &item.vis),
1018 format_unsafety(unsafety),
1019 format_auto(is_auto),
1021 result.push_str(&header);
1023 let body_lo = context.snippet_provider.span_after(item.span, "{");
1025 let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
1027 rewrite_generics(context, rewrite_ident(context, item.ident), generics, shape)?;
1028 result.push_str(&generics_str);
1030 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
1031 if !generic_bounds.is_empty() {
1032 let ident_hi = context
1034 .span_after(item.span, &item.ident.as_str());
1035 let bound_hi = generic_bounds.last().unwrap().span().hi();
1036 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
1037 if contains_comment(snippet) {
1041 result = rewrite_assign_rhs_with(
1046 RhsTactics::ForceNextLineWithoutIndent,
1050 // Rewrite where clause.
1051 if !generics.where_clause.predicates.is_empty() {
1052 let where_density = if context.config.indent_style() == IndentStyle::Block {
1058 let where_budget = context.budget(last_line_width(&result));
1059 let pos_before_where = if generic_bounds.is_empty() {
1060 generics.where_clause.span.lo()
1062 generic_bounds[generic_bounds.len() - 1].span().hi()
1064 let option = WhereClauseOption::snuggled(&generics_str);
1065 let where_clause_str = rewrite_where_clause(
1067 &generics.where_clause,
1068 context.config.brace_style(),
1069 Shape::legacy(where_budget, offset.block_only()),
1077 // If the where clause cannot fit on the same line,
1078 // put the where clause on a new line
1079 if !where_clause_str.contains('\n')
1080 && last_line_width(&result) + where_clause_str.len() + offset.width()
1081 > context.config.comment_width()
1083 let width = offset.block_indent + context.config.tab_spaces() - 1;
1084 let where_indent = Indent::new(0, width);
1085 result.push_str(&where_indent.to_string_with_newline(context.config));
1087 result.push_str(&where_clause_str);
1089 let item_snippet = context.snippet(item.span);
1090 if let Some(lo) = item_snippet.find('/') {
1092 let comment_hi = body_lo - BytePos(1);
1093 let comment_lo = item.span.lo() + BytePos(lo as u32);
1094 if comment_lo < comment_hi {
1095 match recover_missing_comment_in_span(
1096 mk_sp(comment_lo, comment_hi),
1097 Shape::indented(offset, context.config),
1099 last_line_width(&result),
1101 Some(ref missing_comment) if !missing_comment.is_empty() => {
1102 result.push_str(missing_comment);
1110 match context.config.brace_style() {
1111 _ if last_line_contains_single_line_comment(&result)
1112 || last_line_width(&result) + 2 > context.budget(offset.width()) =>
1114 result.push_str(&offset.to_string_with_newline(context.config));
1116 BraceStyle::AlwaysNextLine => {
1117 result.push_str(&offset.to_string_with_newline(context.config));
1119 BraceStyle::PreferSameLine => result.push(' '),
1120 BraceStyle::SameLineWhere => {
1121 if result.contains('\n')
1122 || (!generics.where_clause.predicates.is_empty() && !trait_items.is_empty())
1124 result.push_str(&offset.to_string_with_newline(context.config));
1132 let snippet = context.snippet(item.span);
1133 let open_pos = snippet.find_uncommented("{")? + 1;
1134 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
1136 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1137 let mut visitor = FmtVisitor::from_context(context);
1138 visitor.block_indent = offset.block_only().block_indent(context.config);
1139 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1141 for item in trait_items {
1142 visitor.visit_trait_item(item);
1145 visitor.format_missing(item.span.hi() - BytePos(1));
1147 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
1149 result.push_str(&inner_indent_str);
1150 result.push_str(visitor.buffer.trim());
1151 result.push_str(&outer_indent_str);
1152 } else if result.contains('\n') {
1153 result.push_str(&outer_indent_str);
1163 pub fn format_trait_alias(
1164 context: &RewriteContext<'_>,
1166 generics: &ast::Generics,
1167 generic_bounds: &ast::GenericBounds,
1169 ) -> Option<String> {
1170 let alias = rewrite_ident(context, ident);
1171 // 6 = "trait ", 2 = " ="
1172 let g_shape = shape.offset_left(6)?.sub_width(2)?;
1173 let generics_str = rewrite_generics(context, &alias, generics, g_shape)?;
1174 let lhs = format!("trait {} =", generics_str);
1176 rewrite_assign_rhs(context, lhs, generic_bounds, shape.sub_width(1)?).map(|s| s + ";")
1179 fn format_unit_struct(
1180 context: &RewriteContext<'_>,
1181 p: &StructParts<'_>,
1183 ) -> Option<String> {
1184 let header_str = format_header(context, p.prefix, p.ident, p.vis);
1185 let generics_str = if let Some(generics) = p.generics {
1186 let hi = if generics.where_clause.predicates.is_empty() {
1189 generics.where_clause.span.hi()
1194 context.config.brace_style(),
1197 // make a span that starts right after `struct Foo`
1198 mk_sp(p.ident.span.hi(), hi),
1199 last_line_width(&header_str),
1204 Some(format!("{}{};", header_str, generics_str))
1207 pub fn format_struct_struct(
1208 context: &RewriteContext<'_>,
1209 struct_parts: &StructParts<'_>,
1210 fields: &[ast::StructField],
1212 one_line_width: Option<usize>,
1213 ) -> Option<String> {
1214 let mut result = String::with_capacity(1024);
1215 let span = struct_parts.span;
1217 let header_str = struct_parts.format_header(context);
1218 result.push_str(&header_str);
1220 let header_hi = struct_parts.ident.span.hi();
1221 let body_lo = context.snippet_provider.span_after(span, "{");
1223 let generics_str = match struct_parts.generics {
1224 Some(g) => format_generics(
1227 context.config.brace_style(),
1228 if fields.is_empty() {
1229 BracePos::ForceSameLine
1234 // make a span that starts right after `struct Foo`
1235 mk_sp(header_hi, body_lo),
1236 last_line_width(&result),
1239 // 3 = ` {}`, 2 = ` {`.
1240 let overhead = if fields.is_empty() { 3 } else { 2 };
1241 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1242 || context.config.max_width() < overhead + result.len()
1244 format!("\n{}{{", offset.block_only().to_string(context.config))
1251 let overhead = if fields.is_empty() { 1 } else { 0 };
1252 let total_width = result.len() + generics_str.len() + overhead;
1253 if !generics_str.is_empty()
1254 && !generics_str.contains('\n')
1255 && total_width > context.config.max_width()
1258 result.push_str(&offset.to_string(context.config));
1259 result.push_str(generics_str.trim_start());
1261 result.push_str(&generics_str);
1264 if fields.is_empty() {
1265 let inner_span = mk_sp(body_lo, span.hi() - BytePos(1));
1266 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "", "}");
1267 return Some(result);
1271 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1272 let one_line_budget =
1273 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1275 let items_str = rewrite_with_alignment(
1278 Shape::indented(offset.block_indent(context.config), context.config).sub_width(1)?,
1279 mk_sp(body_lo, span.hi()),
1283 if !items_str.contains('\n')
1284 && !result.contains('\n')
1285 && items_str.len() <= one_line_budget
1286 && !last_line_contains_single_line_comment(&items_str)
1288 Some(format!("{} {} }}", result, items_str))
1294 .block_indent(context.config)
1295 .to_string(context.config),
1297 offset.to_string(context.config)
1302 fn get_bytepos_after_visibility(vis: &ast::Visibility, default_span: Span) -> BytePos {
1304 ast::VisibilityKind::Crate(..) | ast::VisibilityKind::Restricted { .. } => vis.span.hi(),
1305 _ => default_span.lo(),
1309 // Format tuple or struct without any fields. We need to make sure that the comments
1310 // inside the delimiters are preserved.
1311 fn format_empty_struct_or_tuple(
1312 context: &RewriteContext<'_>,
1315 result: &mut String,
1319 // 3 = " {}" or "();"
1320 let used_width = last_line_used_width(&result, offset.width()) + 3;
1321 if used_width > context.config.max_width() {
1322 result.push_str(&offset.to_string_with_newline(context.config))
1324 result.push_str(opener);
1325 match rewrite_missing_comment(span, Shape::indented(offset, context.config), context) {
1326 Some(ref s) if s.is_empty() => (),
1328 if !is_single_line(s) || first_line_contains_single_line_comment(s) {
1329 let nested_indent_str = offset
1330 .block_indent(context.config)
1331 .to_string_with_newline(context.config);
1332 result.push_str(&nested_indent_str);
1335 if last_line_contains_single_line_comment(s) {
1336 result.push_str(&offset.to_string_with_newline(context.config));
1339 None => result.push_str(context.snippet(span)),
1341 result.push_str(closer);
1344 fn format_tuple_struct(
1345 context: &RewriteContext<'_>,
1346 struct_parts: &StructParts<'_>,
1347 fields: &[ast::StructField],
1349 ) -> Option<String> {
1350 let mut result = String::with_capacity(1024);
1351 let span = struct_parts.span;
1353 let header_str = struct_parts.format_header(context);
1354 result.push_str(&header_str);
1356 let body_lo = if fields.is_empty() {
1357 let lo = get_bytepos_after_visibility(struct_parts.vis, span);
1360 .span_after(mk_sp(lo, span.hi()), "(")
1364 let body_hi = if fields.is_empty() {
1367 .span_after(mk_sp(body_lo, span.hi()), ")")
1369 // This is a dirty hack to work around a missing `)` from the span of the last field.
1370 let last_arg_span = fields[fields.len() - 1].span;
1373 .opt_span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1374 .unwrap_or(last_arg_span.hi())
1377 let where_clause_str = match struct_parts.generics {
1379 let budget = context.budget(last_line_width(&header_str));
1380 let shape = Shape::legacy(budget, offset);
1381 let generics_str = rewrite_generics(context, "", generics, shape)?;
1382 result.push_str(&generics_str);
1384 let where_budget = context.budget(last_line_width(&result));
1385 let option = WhereClauseOption::new(true, false);
1386 rewrite_where_clause(
1388 &generics.where_clause,
1389 context.config.brace_style(),
1390 Shape::legacy(where_budget, offset.block_only()),
1391 Density::Compressed,
1399 None => "".to_owned(),
1402 if fields.is_empty() {
1403 let body_hi = context
1405 .span_before(mk_sp(body_lo, span.hi()), ")");
1406 let inner_span = mk_sp(body_lo, body_hi);
1407 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "(", ")");
1409 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1410 result = overflow::rewrite_with_parens(
1416 context.config.width_heuristics().fn_call_width,
1421 if !where_clause_str.is_empty()
1422 && !where_clause_str.contains('\n')
1423 && (result.contains('\n')
1424 || offset.block_indent + result.len() + where_clause_str.len() + 1
1425 > context.config.max_width())
1427 // We need to put the where clause on a new line, but we didn't
1428 // know that earlier, so the where clause will not be indented properly.
1431 &(offset.block_only() + (context.config.tab_spaces() - 1)).to_string(context.config),
1434 result.push_str(&where_clause_str);
1439 fn rewrite_type_prefix(
1440 context: &RewriteContext<'_>,
1444 generics: &ast::Generics,
1445 ) -> Option<String> {
1446 let mut result = String::with_capacity(128);
1447 result.push_str(prefix);
1448 let ident_str = rewrite_ident(context, ident);
1451 if generics.params.is_empty() {
1452 result.push_str(ident_str)
1454 let g_shape = Shape::indented(indent, context.config)
1455 .offset_left(result.len())?
1457 let generics_str = rewrite_generics(context, ident_str, generics, g_shape)?;
1458 result.push_str(&generics_str);
1461 let where_budget = context.budget(last_line_width(&result));
1462 let option = WhereClauseOption::snuggled(&result);
1463 let where_clause_str = rewrite_where_clause(
1465 &generics.where_clause,
1466 context.config.brace_style(),
1467 Shape::legacy(where_budget, indent),
1475 result.push_str(&where_clause_str);
1480 fn rewrite_type_item<R: Rewrite>(
1481 context: &RewriteContext<'_>,
1487 generics: &ast::Generics,
1488 vis: &ast::Visibility,
1489 ) -> Option<String> {
1490 let mut result = String::with_capacity(128);
1491 result.push_str(&rewrite_type_prefix(
1494 &format!("{}{} ", format_visibility(context, vis), prefix),
1499 if generics.where_clause.predicates.is_empty() {
1500 result.push_str(suffix);
1502 result.push_str(&indent.to_string_with_newline(context.config));
1503 result.push_str(suffix.trim_start());
1507 let rhs_shape = Shape::indented(indent, context.config).sub_width(1)?;
1508 rewrite_assign_rhs(context, result, rhs, rhs_shape).map(|s| s + ";")
1511 pub fn rewrite_type_alias(
1512 context: &RewriteContext<'_>,
1516 generics: &ast::Generics,
1517 vis: &ast::Visibility,
1518 ) -> Option<String> {
1519 rewrite_type_item(context, indent, "type", " =", ident, ty, generics, vis)
1522 pub fn rewrite_existential_type(
1523 context: &RewriteContext<'_>,
1526 generic_bounds: &ast::GenericBounds,
1527 generics: &ast::Generics,
1528 vis: &ast::Visibility,
1529 ) -> Option<String> {
1542 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1544 if config.space_before_colon() { " " } else { "" },
1545 if config.space_after_colon() { " " } else { "" },
1549 pub fn rewrite_struct_field_prefix(
1550 context: &RewriteContext<'_>,
1551 field: &ast::StructField,
1552 ) -> Option<String> {
1553 let vis = format_visibility(context, &field.vis);
1554 let type_annotation_spacing = type_annotation_spacing(context.config);
1555 Some(match field.ident {
1556 Some(name) => format!(
1559 rewrite_ident(context, name),
1560 type_annotation_spacing.0
1562 None => vis.to_string(),
1566 impl Rewrite for ast::StructField {
1567 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1568 rewrite_struct_field(context, self, shape, 0)
1572 pub fn rewrite_struct_field(
1573 context: &RewriteContext<'_>,
1574 field: &ast::StructField,
1576 lhs_max_width: usize,
1577 ) -> Option<String> {
1578 if contains_skip(&field.attrs) {
1579 return Some(context.snippet(field.span()).to_owned());
1582 let type_annotation_spacing = type_annotation_spacing(context.config);
1583 let prefix = rewrite_struct_field_prefix(context, field)?;
1585 let attrs_str = field.attrs.rewrite(context, shape)?;
1586 let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
1587 let missing_span = if field.attrs.is_empty() {
1588 mk_sp(field.span.lo(), field.span.lo())
1590 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1592 let mut spacing = String::from(if field.ident.is_some() {
1593 type_annotation_spacing.1
1597 // Try to put everything on a single line.
1598 let attr_prefix = combine_strs_with_missing_comments(
1606 let overhead = last_line_width(&attr_prefix);
1607 let lhs_offset = lhs_max_width.saturating_sub(overhead);
1608 for _ in 0..lhs_offset {
1611 // In this extreme case we will be missing a space between an attribute and a field.
1612 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1616 .offset_left(overhead + spacing.len())
1617 .and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
1618 if let Some(ref ty) = orig_ty {
1619 if !ty.contains('\n') {
1620 return Some(attr_prefix + &spacing + ty);
1624 let is_prefix_empty = prefix.is_empty();
1625 // We must use multiline. We are going to put attributes and a field on different lines.
1626 let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, shape)?;
1627 // Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
1628 let field_str = if is_prefix_empty {
1629 field_str.trim_start()
1633 combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
1636 pub struct StaticParts<'a> {
1638 vis: &'a ast::Visibility,
1641 mutability: ast::Mutability,
1642 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1643 defaultness: Option<ast::Defaultness>,
1647 impl<'a> StaticParts<'a> {
1648 pub fn from_item(item: &'a ast::Item) -> Self {
1649 let (prefix, ty, mutability, expr) = match item.node {
1650 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1651 ast::ItemKind::Const(ref ty, ref expr) => {
1652 ("const", ty, ast::Mutability::Immutable, expr)
1654 _ => unreachable!(),
1662 expr_opt: Some(expr),
1668 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1669 let (ty, expr_opt) = match ti.node {
1670 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1671 _ => unreachable!(),
1675 vis: &DEFAULT_VISIBILITY,
1678 mutability: ast::Mutability::Immutable,
1679 expr_opt: expr_opt.as_ref(),
1685 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1686 let (ty, expr) = match ii.node {
1687 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1688 _ => unreachable!(),
1695 mutability: ast::Mutability::Immutable,
1696 expr_opt: Some(expr),
1697 defaultness: Some(ii.defaultness),
1704 context: &RewriteContext<'_>,
1705 static_parts: &StaticParts<'_>,
1707 ) -> Option<String> {
1708 let colon = colon_spaces(
1709 context.config.space_before_colon(),
1710 context.config.space_after_colon(),
1712 let mut prefix = format!(
1714 format_visibility(context, static_parts.vis),
1715 static_parts.defaultness.map_or("", format_defaultness),
1716 static_parts.prefix,
1717 format_mutability(static_parts.mutability),
1723 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1724 let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
1725 Some(ty_str) => ty_str,
1727 if prefix.ends_with(' ') {
1730 let nested_indent = offset.block_indent(context.config);
1731 let nested_shape = Shape::indented(nested_indent, context.config);
1732 let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
1735 nested_indent.to_string_with_newline(context.config),
1741 if let Some(expr) = static_parts.expr_opt {
1742 let lhs = format!("{}{} =", prefix, ty_str);
1744 let remaining_width = context.budget(offset.block_indent + 1);
1749 Shape::legacy(remaining_width, offset.block_only()),
1751 .and_then(|res| recover_comment_removed(res, static_parts.span, context))
1752 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1754 Some(format!("{}{};", prefix, ty_str))
1758 pub fn rewrite_associated_type(
1760 ty_opt: Option<&ptr::P<ast::Ty>>,
1761 generics: &ast::Generics,
1762 generic_bounds_opt: Option<&ast::GenericBounds>,
1763 context: &RewriteContext<'_>,
1765 ) -> Option<String> {
1766 let ident_str = rewrite_ident(context, ident);
1768 let generics_shape = Shape::indented(indent, context.config).offset_left(5)?;
1769 let generics_str = rewrite_generics(context, ident_str, generics, generics_shape)?;
1770 let prefix = format!("type {}", generics_str);
1772 let type_bounds_str = if let Some(bounds) = generic_bounds_opt {
1773 if bounds.is_empty() {
1777 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1778 bounds.rewrite(context, shape).map(|s| format!(": {}", s))?
1784 if let Some(ty) = ty_opt {
1786 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1787 let lhs = format!("{}{} =", prefix, type_bounds_str);
1788 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1790 Some(format!("{}{};", prefix, type_bounds_str))
1794 pub fn rewrite_existential_impl_type(
1795 context: &RewriteContext<'_>,
1797 generics: &ast::Generics,
1798 generic_bounds: &ast::GenericBounds,
1800 ) -> Option<String> {
1801 rewrite_associated_type(ident, None, generics, Some(generic_bounds), context, indent)
1802 .map(|s| format!("existential {}", s))
1805 pub fn rewrite_associated_impl_type(
1807 defaultness: ast::Defaultness,
1808 ty_opt: Option<&ptr::P<ast::Ty>>,
1809 generics: &ast::Generics,
1810 context: &RewriteContext<'_>,
1812 ) -> Option<String> {
1813 let result = rewrite_associated_type(ident, ty_opt, generics, None, context, indent)?;
1816 ast::Defaultness::Default => Some(format!("default {}", result)),
1821 impl Rewrite for ast::FunctionRetTy {
1822 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1824 ast::FunctionRetTy::Default(_) => Some(String::new()),
1825 ast::FunctionRetTy::Ty(ref ty) => {
1826 let inner_width = shape.width.checked_sub(3)?;
1827 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1828 .map(|r| format!("-> {}", r))
1834 fn is_empty_infer(ty: &ast::Ty, pat_span: Span) -> bool {
1836 ast::TyKind::Infer => ty.span.hi() == pat_span.hi(),
1841 impl Rewrite for ast::Arg {
1842 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1843 if is_named_arg(self) {
1844 let mut result = self
1846 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1848 if !is_empty_infer(&*self.ty, self.pat.span) {
1849 if context.config.space_before_colon() {
1850 result.push_str(" ");
1852 result.push_str(":");
1853 if context.config.space_after_colon() {
1854 result.push_str(" ");
1856 let overhead = last_line_width(&result);
1857 let max_width = shape.width.checked_sub(overhead)?;
1860 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1861 result.push_str(&ty_str);
1866 self.ty.rewrite(context, shape)
1871 fn rewrite_explicit_self(
1872 explicit_self: &ast::ExplicitSelf,
1874 context: &RewriteContext<'_>,
1875 ) -> Option<String> {
1876 match explicit_self.node {
1877 ast::SelfKind::Region(lt, m) => {
1878 let mut_str = format_mutability(m);
1881 let lifetime_str = l.rewrite(
1883 Shape::legacy(context.config.max_width(), Indent::empty()),
1885 Some(format!("&{} {}self", lifetime_str, mut_str))
1887 None => Some(format!("&{}self", mut_str)),
1890 ast::SelfKind::Explicit(ref ty, _) => {
1891 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1893 let mutability = explicit_self_mutability(&args[0]);
1894 let type_str = ty.rewrite(
1896 Shape::legacy(context.config.max_width(), Indent::empty()),
1901 format_mutability(mutability),
1905 ast::SelfKind::Value(_) => {
1906 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1908 let mutability = explicit_self_mutability(&args[0]);
1910 Some(format!("{}self", format_mutability(mutability)))
1915 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1916 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1917 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1918 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1925 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1926 if is_named_arg(arg) {
1933 pub fn span_hi_for_arg(context: &RewriteContext<'_>, arg: &ast::Arg) -> BytePos {
1935 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1936 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1937 _ => arg.ty.span.hi(),
1941 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1942 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1943 ident != symbol::keywords::Invalid.ident()
1949 // Return type is (result, force_new_line_for_brace)
1951 context: &RewriteContext<'_>,
1956 newline_brace: bool,
1958 ) -> Option<(String, bool)> {
1959 let mut force_new_line_for_brace = false;
1961 let where_clause = &fn_sig.generics.where_clause;
1963 let mut result = String::with_capacity(1024);
1964 result.push_str(&fn_sig.to_str(context));
1967 result.push_str("fn ");
1970 let overhead = if has_body && !newline_brace {
1977 let used_width = last_line_used_width(&result, indent.width());
1978 let one_line_budget = context.budget(used_width + overhead);
1980 width: one_line_budget,
1984 let fd = fn_sig.decl;
1985 let generics_str = rewrite_generics(
1987 rewrite_ident(context, ident),
1991 result.push_str(&generics_str);
1993 let snuggle_angle_bracket = generics_str
1996 .map_or(false, |l| l.trim_start().len() == 1);
1998 // Note that the width and indent don't really matter, we'll re-layout the
1999 // return type later anyway.
2002 .rewrite(context, Shape::indented(indent, context.config))?;
2004 let multi_line_ret_str = ret_str.contains('\n');
2005 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
2008 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
2019 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
2020 one_line_budget, multi_line_budget, arg_indent
2024 // Check if vertical layout was forced.
2025 if one_line_budget == 0
2026 && !snuggle_angle_bracket
2027 && context.config.indent_style() == IndentStyle::Visual
2029 result.push_str(&arg_indent.to_string_with_newline(context.config));
2032 // Skip `pub(crate)`.
2033 let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
2034 // A conservative estimation, to goal is to be over all parens in generics
2035 let args_start = fn_sig
2040 .map_or(lo_after_visibility, |param| param.span().hi());
2041 let args_end = if fd.inputs.is_empty() {
2044 .span_after(mk_sp(args_start, span.hi()), ")")
2046 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
2047 context.snippet_provider.span_after(last_span, ")")
2049 let args_span = mk_sp(
2052 .span_after(mk_sp(args_start, span.hi()), "("),
2055 let arg_str = rewrite_args(
2058 fd.get_self().as_ref(),
2065 generics_str.contains('\n'),
2068 let put_args_in_block = match context.config.indent_style() {
2069 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
2071 } && !fd.inputs.is_empty();
2073 let mut args_last_line_contains_comment = false;
2074 let mut no_args_and_over_max_width = false;
2076 if put_args_in_block {
2077 arg_indent = indent.block_indent(context.config);
2078 result.push_str(&arg_indent.to_string_with_newline(context.config));
2079 result.push_str(&arg_str);
2080 result.push_str(&indent.to_string_with_newline(context.config));
2083 result.push_str(&arg_str);
2084 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
2085 // Put the closing brace on the next line if it overflows the max width.
2087 let closing_paren_overflow_max_width =
2088 fd.inputs.is_empty() && used_width + 1 > context.config.max_width();
2089 // If the last line of args contains comment, we cannot put the closing paren
2090 // on the same line.
2091 args_last_line_contains_comment = arg_str
2094 .map_or(false, |last_line| last_line.contains("//"));
2096 if context.config.version() == Version::Two {
2098 if closing_paren_overflow_max_width || args_last_line_contains_comment {
2099 result.push_str(&indent.to_string_with_newline(context.config));
2100 no_args_and_over_max_width = true;
2103 if closing_paren_overflow_max_width || args_last_line_contains_comment {
2104 result.push_str(&indent.to_string_with_newline(context.config));
2111 if let ast::FunctionRetTy::Ty(..) = fd.output {
2112 let ret_should_indent = match context.config.indent_style() {
2113 // If our args are block layout then we surely must have space.
2114 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
2115 _ if args_last_line_contains_comment => false,
2116 _ if result.contains('\n') || multi_line_ret_str => true,
2118 // If the return type would push over the max width, then put the return type on
2119 // a new line. With the +1 for the signature length an additional space between
2120 // the closing parenthesis of the argument and the arrow '->' is considered.
2121 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
2123 // If there is no where clause, take into account the space after the return type
2125 if where_clause.predicates.is_empty() {
2129 sig_length > context.config.max_width()
2132 let ret_indent = if ret_should_indent {
2133 let indent = if arg_str.is_empty() {
2134 // Aligning with non-existent args looks silly.
2135 force_new_line_for_brace = true;
2138 // FIXME: we might want to check that using the arg indent
2139 // doesn't blow our budget, and if it does, then fallback to
2140 // the where clause indent.
2144 result.push_str(&indent.to_string_with_newline(context.config));
2147 if context.config.version() == Version::Two {
2148 if arg_str.len() != 0 || !no_args_and_over_max_width {
2155 Indent::new(indent.block_indent, last_line_width(&result))
2158 if multi_line_ret_str || ret_should_indent {
2159 // Now that we know the proper indent and width, we need to
2160 // re-layout the return type.
2163 .rewrite(context, Shape::indented(ret_indent, context.config))?;
2164 result.push_str(&ret_str);
2166 result.push_str(&ret_str);
2169 // Comment between return type and the end of the decl.
2170 let snippet_lo = fd.output.span().hi();
2171 if where_clause.predicates.is_empty() {
2172 let snippet_hi = span.hi();
2173 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2174 // Try to preserve the layout of the original snippet.
2175 let original_starts_with_newline = snippet
2177 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2178 let original_ends_with_newline = snippet
2179 .rfind(|c| c != ' ')
2180 .map_or(false, |i| snippet[i..].ends_with('\n'));
2181 let snippet = snippet.trim();
2182 if !snippet.is_empty() {
2183 result.push(if original_starts_with_newline {
2188 result.push_str(snippet);
2189 if original_ends_with_newline {
2190 force_new_line_for_brace = true;
2196 let pos_before_where = match fd.output {
2197 ast::FunctionRetTy::Default(..) => args_span.hi(),
2198 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2201 let is_args_multi_lined = arg_str.contains('\n');
2203 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2204 let where_clause_str = rewrite_where_clause(
2207 context.config.brace_style(),
2208 Shape::indented(indent, context.config),
2214 is_args_multi_lined,
2216 // If there are neither where clause nor return type, we may be missing comments between
2218 if where_clause_str.is_empty() {
2219 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2220 match recover_missing_comment_in_span(
2221 mk_sp(args_span.hi(), ret_span.hi()),
2224 last_line_width(&result),
2226 Some(ref missing_comment) if !missing_comment.is_empty() => {
2227 result.push_str(missing_comment);
2228 force_new_line_for_brace = true;
2235 result.push_str(&where_clause_str);
2237 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2238 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2239 Some((result, force_new_line_for_brace))
2242 #[derive(Copy, Clone)]
2243 struct WhereClauseOption {
2244 suppress_comma: bool, // Force no trailing comma
2245 snuggle: bool, // Do not insert newline before `where`
2246 compress_where: bool, // Try single line where clause instead of vertical layout
2249 impl WhereClauseOption {
2250 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2254 compress_where: false,
2258 pub fn snuggled(current: &str) -> WhereClauseOption {
2260 suppress_comma: false,
2261 snuggle: last_line_width(current) == 1,
2262 compress_where: false,
2266 pub fn suppress_comma(&mut self) {
2267 self.suppress_comma = true
2270 pub fn compress_where(&mut self) {
2271 self.compress_where = true
2274 pub fn snuggle(&mut self) {
2280 context: &RewriteContext<'_>,
2282 explicit_self: Option<&ast::ExplicitSelf>,
2283 one_line_budget: usize,
2284 multi_line_budget: usize,
2289 generics_str_contains_newline: bool,
2290 ) -> Option<String> {
2291 let mut arg_item_strs = args
2294 arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent))
2295 .unwrap_or_else(|| context.snippet(arg.span()).to_owned())
2297 .collect::<Vec<_>>();
2299 // Account for sugary self.
2300 // FIXME: the comment for the self argument is dropped. This is blocked
2301 // on rust issue #27522.
2302 let min_args = explicit_self
2303 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2304 .map_or(1, |self_str| {
2305 arg_item_strs[0] = self_str;
2309 // Comments between args.
2310 let mut arg_items = Vec::new();
2312 arg_items.push(ListItem::from_str(""));
2315 // FIXME(#21): if there are no args, there might still be a comment, but
2316 // without spans for the comment or parens, there is no chance of
2317 // getting it right. You also don't get to put a comment on self, unless
2319 if args.len() >= min_args || variadic {
2320 let comment_span_start = if min_args == 2 {
2321 let second_arg_start = if arg_has_pattern(&args[1]) {
2322 args[1].pat.span.lo()
2324 args[1].ty.span.lo()
2326 let reduced_span = mk_sp(span.lo(), second_arg_start);
2328 context.snippet_provider.span_after_last(reduced_span, ",")
2333 enum ArgumentKind<'a> {
2334 Regular(&'a ast::Arg),
2338 let variadic_arg = if variadic {
2339 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2340 let variadic_start =
2341 context.snippet_provider.span_after(variadic_span, "...") - BytePos(3);
2342 Some(ArgumentKind::Variadic(variadic_start))
2347 let more_items = itemize_list(
2348 context.snippet_provider,
2349 args[min_args - 1..]
2351 .map(ArgumentKind::Regular)
2352 .chain(variadic_arg),
2356 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2357 ArgumentKind::Variadic(start) => start,
2360 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2361 ArgumentKind::Variadic(start) => start + BytePos(3),
2364 ArgumentKind::Regular(..) => None,
2365 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2372 arg_items.extend(more_items);
2375 let fits_in_one_line = !generics_str_contains_newline
2376 && (arg_items.is_empty()
2377 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2379 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2380 item.item = Some(arg);
2383 let last_line_ends_with_comment = arg_items
2386 .and_then(|item| item.post_comment.as_ref())
2387 .map_or(false, |s| s.trim().starts_with("//"));
2389 let (indent, trailing_comma) = match context.config.indent_style() {
2390 IndentStyle::Block if fits_in_one_line => {
2391 (indent.block_indent(context.config), SeparatorTactic::Never)
2393 IndentStyle::Block => (
2394 indent.block_indent(context.config),
2395 context.config.trailing_comma(),
2397 IndentStyle::Visual if last_line_ends_with_comment => {
2398 (arg_indent, context.config.trailing_comma())
2400 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2403 let tactic = definitive_tactic(
2405 context.config.fn_args_density().to_list_tactic(),
2409 let budget = match tactic {
2410 DefinitiveListTactic::Horizontal => one_line_budget,
2411 _ => multi_line_budget,
2414 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2416 let trailing_separator = if variadic {
2417 SeparatorTactic::Never
2421 let fmt = ListFormatting::new(Shape::legacy(budget, indent), context.config)
2423 .trailing_separator(trailing_separator)
2424 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2425 .preserve_newline(true);
2426 write_list(&arg_items, &fmt)
2429 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2430 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2431 ident != symbol::keywords::Invalid.ident()
2437 fn compute_budgets_for_args(
2438 context: &RewriteContext<'_>,
2442 newline_brace: bool,
2444 force_vertical_layout: bool,
2445 ) -> Option<((usize, usize, Indent))> {
2447 "compute_budgets_for_args {} {:?}, {}, {}",
2453 // Try keeping everything on the same line.
2454 if !result.contains('\n') && !force_vertical_layout {
2455 // 2 = `()`, 3 = `() `, space is before ret_string.
2456 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2457 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2467 let one_line_budget = context.budget(used_space);
2469 if one_line_budget > 0 {
2471 let (indent, multi_line_budget) = match context.config.indent_style() {
2472 IndentStyle::Block => {
2473 let indent = indent.block_indent(context.config);
2474 (indent, context.budget(indent.width() + 1))
2476 IndentStyle::Visual => {
2477 let indent = indent + result.len() + 1;
2478 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2479 (indent, context.budget(multi_line_overhead))
2483 return Some((one_line_budget, multi_line_budget, indent));
2487 // Didn't work. we must force vertical layout and put args on a newline.
2488 let new_indent = indent.block_indent(context.config);
2489 let used_space = match context.config.indent_style() {
2491 IndentStyle::Block => new_indent.width() + 1,
2492 // Account for `)` and possibly ` {`.
2493 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2495 Some((0, context.budget(used_space), new_indent))
2498 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2499 let predicate_count = where_clause.predicates.len();
2501 if config.where_single_line() && predicate_count == 1 {
2504 let brace_style = config.brace_style();
2506 brace_style == BraceStyle::AlwaysNextLine
2507 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2510 fn rewrite_generics(
2511 context: &RewriteContext<'_>,
2513 generics: &ast::Generics,
2515 ) -> Option<String> {
2516 // FIXME: convert bounds to where clauses where they get too big or if
2517 // there is a where clause at all.
2519 if generics.params.is_empty() {
2520 return Some(ident.to_owned());
2523 let params = generics.params.iter();
2524 overflow::rewrite_with_angle_brackets(context, ident, params, shape, generics.span)
2527 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2528 match config.indent_style() {
2529 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2530 IndentStyle::Block => {
2534 .block_indent(config.tab_spaces())
2535 .with_max_width(config)
2541 fn rewrite_where_clause_rfc_style(
2542 context: &RewriteContext<'_>,
2543 where_clause: &ast::WhereClause,
2546 span_end: Option<BytePos>,
2547 span_end_before_where: BytePos,
2548 where_clause_option: WhereClauseOption,
2549 is_args_multi_line: bool,
2550 ) -> Option<String> {
2551 let block_shape = shape.block().with_max_width(context.config);
2553 let (span_before, span_after) =
2554 missing_span_before_after_where(span_end_before_where, where_clause);
2555 let (comment_before, comment_after) =
2556 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2558 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2561 block_shape.indent.to_string_with_newline(context.config)
2564 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2566 let clause_shape = clause_shape.sub_width(1)?;
2567 // each clause on one line, trailing comma (except if suppress_comma)
2568 let span_start = where_clause.predicates[0].span().lo();
2569 // If we don't have the start of the next span, then use the end of the
2570 // predicates, but that means we miss comments.
2571 let len = where_clause.predicates.len();
2572 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2573 let span_end = span_end.unwrap_or(end_of_preds);
2574 let items = itemize_list(
2575 context.snippet_provider,
2576 where_clause.predicates.iter(),
2579 |pred| pred.span().lo(),
2580 |pred| pred.span().hi(),
2581 |pred| pred.rewrite(context, clause_shape),
2586 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2587 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2588 SeparatorTactic::Never
2590 context.config.trailing_comma()
2593 // shape should be vertical only and only if we have `where_single_line` option enabled
2594 // and the number of items of the where clause is equal to 1
2595 let shape_tactic = if where_single_line {
2596 DefinitiveListTactic::Horizontal
2598 DefinitiveListTactic::Vertical
2601 let fmt = ListFormatting::new(clause_shape, context.config)
2602 .tactic(shape_tactic)
2603 .trailing_separator(comma_tactic)
2604 .preserve_newline(true);
2605 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2607 let comment_separator = |comment: &str, shape: Shape| {
2608 if comment.is_empty() {
2611 shape.indent.to_string_with_newline(context.config)
2614 let newline_before_where = comment_separator(&comment_before, shape);
2615 let newline_after_where = comment_separator(&comment_after, clause_shape);
2618 let clause_sep = if where_clause_option.compress_where
2619 && comment_before.is_empty()
2620 && comment_after.is_empty()
2621 && !preds_str.contains('\n')
2622 && 6 + preds_str.len() <= shape.width
2623 || where_single_line
2627 clause_shape.indent.to_string_with_newline(context.config)
2630 "{}{}{}where{}{}{}{}",
2633 newline_before_where,
2634 newline_after_where,
2641 fn rewrite_where_clause(
2642 context: &RewriteContext<'_>,
2643 where_clause: &ast::WhereClause,
2644 brace_style: BraceStyle,
2648 span_end: Option<BytePos>,
2649 span_end_before_where: BytePos,
2650 where_clause_option: WhereClauseOption,
2651 is_args_multi_line: bool,
2652 ) -> Option<String> {
2653 if where_clause.predicates.is_empty() {
2654 return Some(String::new());
2657 if context.config.indent_style() == IndentStyle::Block {
2658 return rewrite_where_clause_rfc_style(
2664 span_end_before_where,
2665 where_clause_option,
2670 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2672 let offset = match context.config.indent_style() {
2673 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2674 // 6 = "where ".len()
2675 IndentStyle::Visual => shape.indent + extra_indent + 6,
2677 // FIXME: if indent_style != Visual, then the budgets below might
2678 // be out by a char or two.
2680 let budget = context.config.max_width() - offset.width();
2681 let span_start = where_clause.predicates[0].span().lo();
2682 // If we don't have the start of the next span, then use the end of the
2683 // predicates, but that means we miss comments.
2684 let len = where_clause.predicates.len();
2685 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2686 let span_end = span_end.unwrap_or(end_of_preds);
2687 let items = itemize_list(
2688 context.snippet_provider,
2689 where_clause.predicates.iter(),
2692 |pred| pred.span().lo(),
2693 |pred| pred.span().hi(),
2694 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2699 let item_vec = items.collect::<Vec<_>>();
2700 // FIXME: we don't need to collect here
2701 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2703 let mut comma_tactic = context.config.trailing_comma();
2704 // Kind of a hack because we don't usually have trailing commas in where clauses.
2705 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2706 comma_tactic = SeparatorTactic::Never;
2709 let fmt = ListFormatting::new(Shape::legacy(budget, offset), context.config)
2711 .trailing_separator(comma_tactic)
2712 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2713 .preserve_newline(true);
2714 let preds_str = write_list(&item_vec, &fmt)?;
2716 let end_length = if terminator == "{" {
2717 // If the brace is on the next line we don't need to count it otherwise it needs two
2720 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2721 BraceStyle::PreferSameLine => 2,
2723 } else if terminator == "=" {
2728 if density == Density::Tall
2729 || preds_str.contains('\n')
2730 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2734 (shape.indent + extra_indent).to_string(context.config),
2738 Some(format!(" where {}", preds_str))
2742 fn missing_span_before_after_where(
2743 before_item_span_end: BytePos,
2744 where_clause: &ast::WhereClause,
2746 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2748 let pos_after_where = where_clause.span.lo() + BytePos(5);
2749 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2750 (missing_span_before, missing_span_after)
2753 fn rewrite_comments_before_after_where(
2754 context: &RewriteContext<'_>,
2755 span_before_where: Span,
2756 span_after_where: Span,
2758 ) -> Option<(String, String)> {
2759 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2760 let after_comment = rewrite_missing_comment(
2762 shape.block_indent(context.config.tab_spaces()),
2765 Some((before_comment, after_comment))
2769 context: &RewriteContext<'_>,
2772 vis: &ast::Visibility,
2776 format_visibility(context, vis),
2778 rewrite_ident(context, ident)
2782 #[derive(PartialEq, Eq, Clone, Copy)]
2790 context: &RewriteContext<'_>,
2791 generics: &ast::Generics,
2792 brace_style: BraceStyle,
2793 brace_pos: BracePos,
2797 ) -> Option<String> {
2798 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2799 let mut result = rewrite_generics(context, "", generics, shape)?;
2801 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2802 let budget = context.budget(last_line_used_width(&result, offset.width()));
2803 let mut option = WhereClauseOption::snuggled(&result);
2804 if brace_pos == BracePos::None {
2805 option.suppress_comma = true;
2807 // If the generics are not parameterized then generics.span.hi() == 0,
2808 // so we use span.lo(), which is the position after `struct Foo`.
2809 let span_end_before_where = if !generics.params.is_empty() {
2814 let where_clause_str = rewrite_where_clause(
2816 &generics.where_clause,
2818 Shape::legacy(budget, offset.block_only()),
2822 span_end_before_where,
2826 result.push_str(&where_clause_str);
2827 brace_pos == BracePos::ForceSameLine
2828 || brace_style == BraceStyle::PreferSameLine
2829 || (generics.where_clause.predicates.is_empty()
2830 && trimmed_last_line_width(&result) == 1)
2832 brace_pos == BracePos::ForceSameLine
2833 || trimmed_last_line_width(&result) == 1
2834 || brace_style != BraceStyle::AlwaysNextLine
2836 if brace_pos == BracePos::None {
2837 return Some(result);
2839 let total_used_width = last_line_used_width(&result, used_width);
2840 let remaining_budget = context.budget(total_used_width);
2841 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2842 // and hence we take the closer into account as well for one line budget.
2843 // We assume that the closer has the same length as the opener.
2844 let overhead = if brace_pos == BracePos::ForceSameLine {
2851 let forbid_same_line_brace = overhead > remaining_budget;
2852 if !forbid_same_line_brace && same_line_brace {
2856 result.push_str(&offset.block_only().to_string(context.config));
2863 impl Rewrite for ast::ForeignItem {
2864 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
2865 let attrs_str = self.attrs.rewrite(context, shape)?;
2866 // Drop semicolon or it will be interpreted as comment.
2867 // FIXME: this may be a faulty span from libsyntax.
2868 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2870 let item_str = match self.node {
2871 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => rewrite_fn_base(
2875 &FnSig::new(fn_decl, generics, self.vis.clone()),
2880 .map(|(s, _)| format!("{};", s)),
2881 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2882 // FIXME(#21): we're dropping potential comments in between the
2883 // function keywords here.
2884 let vis = format_visibility(context, &self.vis);
2885 let mut_str = if is_mutable { "mut " } else { "" };
2886 let prefix = format!(
2890 rewrite_ident(context, self.ident)
2893 rewrite_assign_rhs(context, prefix, &**ty, shape.sub_width(1)?).map(|s| s + ";")
2895 ast::ForeignItemKind::Ty => {
2896 let vis = format_visibility(context, &self.vis);
2900 rewrite_ident(context, self.ident)
2903 ast::ForeignItemKind::Macro(ref mac) => {
2904 rewrite_macro(mac, None, context, shape, MacroPosition::Item)
2908 let missing_span = if self.attrs.is_empty() {
2909 mk_sp(self.span.lo(), self.span.lo())
2911 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2913 combine_strs_with_missing_comments(
2924 /// Rewrite an inline mod.
2925 pub fn rewrite_mod(context: &RewriteContext<'_>, item: &ast::Item) -> String {
2926 let mut result = String::with_capacity(32);
2927 result.push_str(&*format_visibility(context, &item.vis));
2928 result.push_str("mod ");
2929 result.push_str(rewrite_ident(context, item.ident));
2934 /// Rewrite `extern crate foo;` WITHOUT attributes.
2935 pub fn rewrite_extern_crate(context: &RewriteContext<'_>, item: &ast::Item) -> Option<String> {
2936 assert!(is_extern_crate(item));
2937 let new_str = context.snippet(item.span);
2938 Some(if contains_comment(new_str) {
2941 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
2942 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
2946 /// Returns true for `mod foo;`, false for `mod foo { .. }`.
2947 pub fn is_mod_decl(item: &ast::Item) -> bool {
2949 ast::ItemKind::Mod(ref m) => m.inner.hi() != item.span.hi(),
2954 pub fn is_use_item(item: &ast::Item) -> bool {
2956 ast::ItemKind::Use(_) => true,
2961 pub fn is_extern_crate(item: &ast::Item) -> bool {
2963 ast::ItemKind::ExternCrate(..) => true,