1 // Formatting top-level items - functions, structs, enums, traits, impls.
4 use std::cmp::{max, min, Ordering};
8 use rustc_ast::{ast, ptr};
9 use rustc_span::{symbol, BytePos, Span, DUMMY_SP};
11 use crate::attr::filter_inline_attrs;
13 combine_strs_with_missing_comments, contains_comment, is_last_comment_block,
14 recover_comment_removed, recover_missing_comment_in_span, rewrite_missing_comment,
17 use crate::config::lists::*;
18 use crate::config::{BraceStyle, Config, IndentStyle, Version};
20 is_empty_block, is_simple_block_stmt, rewrite_assign_rhs, rewrite_assign_rhs_with,
21 rewrite_assign_rhs_with_comments, RhsTactics,
23 use crate::lists::{definitive_tactic, itemize_list, write_list, ListFormatting, Separator};
24 use crate::macros::{rewrite_macro, MacroPosition};
26 use crate::rewrite::{Rewrite, RewriteContext};
27 use crate::shape::{Indent, Shape};
28 use crate::source_map::{LineRangeUtils, SpanUtils};
29 use crate::spanned::Spanned;
30 use crate::stmt::Stmt;
32 use crate::vertical::rewrite_with_alignment;
33 use crate::visitor::FmtVisitor;
35 const DEFAULT_VISIBILITY: ast::Visibility = ast::Visibility {
36 kind: ast::VisibilityKind::Inherited,
41 fn type_annotation_separator(config: &Config) -> &str {
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) || matches!(self.kind, ast::LocalKind::InitElse(..)) {
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 ty_shape = if pat_str.contains('\n') {
91 shape.with_max_width(context.config)
95 .offset_left(last_line_width(&result) + separator.len())?
99 let rewrite = ty.rewrite(context, ty_shape)?;
101 infix.push_str(separator);
102 infix.push_str(&rewrite);
105 if self.kind.init().is_some() {
106 infix.push_str(" =");
112 result.push_str(&infix);
114 if let Some((init, _els)) = self.kind.init_else_opt() {
115 // 1 = trailing semicolon;
116 let nested_shape = shape.sub_width(1)?;
118 result = rewrite_assign_rhs(context, result, init, nested_shape)?;
127 // FIXME convert to using rewrite style rather than visitor
128 // FIXME format modules in this style
132 unsafety: ast::Unsafe,
133 abi: Cow<'static, str>,
134 vis: Option<&'a ast::Visibility>,
135 body: Vec<BodyElement<'a>>,
140 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
142 unsafety: fm.unsafety,
144 ast::Extern::from_abi(fm.abi),
145 config.force_explicit_abi(),
152 .map(|i| BodyElement::ForeignItem(i))
160 enum BodyElement<'a> {
161 // Stmt(&'a ast::Stmt),
162 // Field(&'a ast::ExprField),
163 // Variant(&'a ast::Variant),
164 // Item(&'a ast::Item),
165 ForeignItem(&'a ast::ForeignItem),
168 /// Represents a fn's signature.
169 pub(crate) struct FnSig<'a> {
170 decl: &'a ast::FnDecl,
171 generics: &'a ast::Generics,
173 is_async: Cow<'a, ast::Async>,
174 constness: ast::Const,
175 defaultness: ast::Defaultness,
176 unsafety: ast::Unsafe,
177 visibility: &'a ast::Visibility,
181 pub(crate) fn from_method_sig(
182 method_sig: &'a ast::FnSig,
183 generics: &'a ast::Generics,
184 visibility: &'a ast::Visibility,
187 unsafety: method_sig.header.unsafety,
188 is_async: Cow::Borrowed(&method_sig.header.asyncness),
189 constness: method_sig.header.constness,
190 defaultness: ast::Defaultness::Final,
191 ext: method_sig.header.ext,
192 decl: &*method_sig.decl,
198 pub(crate) fn from_fn_kind(
199 fn_kind: &'a visit::FnKind<'_>,
200 generics: &'a ast::Generics,
201 decl: &'a ast::FnDecl,
202 defaultness: ast::Defaultness,
205 visit::FnKind::Fn(fn_ctxt, _, fn_sig, vis, _) => match fn_ctxt {
206 visit::FnCtxt::Assoc(..) => {
207 let mut fn_sig = FnSig::from_method_sig(fn_sig, generics, vis);
208 fn_sig.defaultness = defaultness;
214 ext: fn_sig.header.ext,
215 constness: fn_sig.header.constness,
216 is_async: Cow::Borrowed(&fn_sig.header.asyncness),
218 unsafety: fn_sig.header.unsafety,
226 fn to_str(&self, context: &RewriteContext<'_>) -> String {
227 let mut result = String::with_capacity(128);
228 // Vis defaultness constness unsafety abi.
229 result.push_str(&*format_visibility(context, &self.visibility));
230 result.push_str(format_defaultness(self.defaultness));
231 result.push_str(format_constness(self.constness));
232 result.push_str(format_async(&self.is_async));
233 result.push_str(format_unsafety(self.unsafety));
234 result.push_str(&format_extern(
236 context.config.force_explicit_abi(),
243 impl<'a> FmtVisitor<'a> {
244 fn format_item(&mut self, item: &Item<'_>) {
245 self.buffer.push_str(format_unsafety(item.unsafety));
246 self.buffer.push_str(&item.abi);
248 let snippet = self.snippet(item.span);
249 let brace_pos = snippet.find_uncommented("{").unwrap();
252 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
253 // FIXME: this skips comments between the extern keyword and the opening
255 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
256 self.block_indent = self.block_indent.block_indent(self.config);
258 if !item.body.is_empty() {
259 for item in &item.body {
260 self.format_body_element(item);
264 self.format_missing_no_indent(item.span.hi() - BytePos(1));
265 self.block_indent = self.block_indent.block_unindent(self.config);
266 let indent_str = self.block_indent.to_string(self.config);
267 self.push_str(&indent_str);
271 self.last_pos = item.span.hi();
274 fn format_body_element(&mut self, element: &BodyElement<'_>) {
276 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
280 pub(crate) fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
281 let item = Item::from_foreign_mod(fm, span, self.config);
282 self.format_item(&item);
285 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
286 let rewrite = item.rewrite(&self.get_context(), self.shape());
287 let hi = item.span.hi();
288 let span = if item.attrs.is_empty() {
291 mk_sp(item.attrs[0].span.lo(), hi)
293 self.push_rewrite(span, rewrite);
297 pub(crate) fn rewrite_fn_before_block(
300 ident: symbol::Ident,
303 ) -> Option<(String, FnBraceStyle)> {
304 let context = self.get_context();
306 let mut fn_brace_style = newline_for_brace(self.config, &fn_sig.generics.where_clause);
307 let (result, _, force_newline_brace) =
308 rewrite_fn_base(&context, indent, ident, fn_sig, span, fn_brace_style)?;
311 if self.config.brace_style() == BraceStyle::AlwaysNextLine
312 || force_newline_brace
313 || last_line_width(&result) + 2 > self.shape().width
315 fn_brace_style = FnBraceStyle::NextLine
318 Some((result, fn_brace_style))
321 pub(crate) fn rewrite_required_fn(
324 ident: symbol::Ident,
326 vis: &ast::Visibility,
327 generics: &ast::Generics,
329 ) -> Option<String> {
330 // Drop semicolon or it will be interpreted as comment.
331 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
332 let context = self.get_context();
334 let (mut result, ends_with_comment, _) = rewrite_fn_base(
338 &FnSig::from_method_sig(sig, generics, vis),
343 // If `result` ends with a comment, then remember to add a newline
344 if ends_with_comment {
345 result.push_str(&indent.to_string_with_newline(context.config));
348 // Re-attach semicolon
354 pub(crate) fn single_line_fn(
358 inner_attrs: Option<&[ast::Attribute]>,
359 ) -> Option<String> {
360 if fn_str.contains('\n') || inner_attrs.map_or(false, |a| !a.is_empty()) {
364 let context = self.get_context();
366 if self.config.empty_item_single_line()
367 && is_empty_block(&context, block, None)
368 && self.block_indent.width() + fn_str.len() + 3 <= self.config.max_width()
369 && !last_line_contains_single_line_comment(fn_str)
371 return Some(format!("{} {{}}", fn_str));
374 if !self.config.fn_single_line() || !is_simple_block_stmt(&context, block, None) {
378 let res = Stmt::from_ast_node(block.stmts.first()?, true)
379 .rewrite(&self.get_context(), self.shape())?;
381 let width = self.block_indent.width() + fn_str.len() + res.len() + 5;
382 if !res.contains('\n') && width <= self.config.max_width() {
383 Some(format!("{} {{ {} }}", fn_str, res))
389 pub(crate) fn visit_static(&mut self, static_parts: &StaticParts<'_>) {
390 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
391 self.push_rewrite(static_parts.span, rewrite);
394 pub(crate) fn visit_struct(&mut self, struct_parts: &StructParts<'_>) {
395 let is_tuple = match struct_parts.def {
396 ast::VariantData::Tuple(..) => true,
399 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
400 .map(|s| if is_tuple { s + ";" } else { s });
401 self.push_rewrite(struct_parts.span, rewrite);
404 pub(crate) fn visit_enum(
406 ident: symbol::Ident,
407 vis: &ast::Visibility,
408 enum_def: &ast::EnumDef,
409 generics: &ast::Generics,
413 format_header(&self.get_context(), "enum ", ident, vis, self.block_indent);
414 self.push_str(&enum_header);
416 let enum_snippet = self.snippet(span);
417 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
418 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
419 let generics_str = format_generics(
422 self.config.brace_style(),
423 if enum_def.variants.is_empty() {
424 BracePos::ForceSameLine
429 // make a span that starts right after `enum Foo`
430 mk_sp(ident.span.hi(), body_start),
431 last_line_width(&enum_header),
434 self.push_str(&generics_str);
436 self.last_pos = body_start;
438 match self.format_variant_list(enum_def, body_start, span.hi()) {
439 Some(ref s) if enum_def.variants.is_empty() => self.push_str(s),
441 self.push_rewrite(mk_sp(body_start, span.hi()), rw);
442 self.block_indent = self.block_indent.block_unindent(self.config);
447 // Format the body of an enum definition
448 fn format_variant_list(
450 enum_def: &ast::EnumDef,
453 ) -> Option<String> {
454 if enum_def.variants.is_empty() {
455 let mut buffer = String::with_capacity(128);
457 let span = mk_sp(body_lo, body_hi - BytePos(1));
458 format_empty_struct_or_tuple(
468 let mut result = String::with_capacity(1024);
469 let original_offset = self.block_indent;
470 self.block_indent = self.block_indent.block_indent(self.config);
472 // If enum variants have discriminants, try to vertically align those,
473 // provided the discrims are not shifted too much to the right
474 let align_threshold: usize = self.config.enum_discrim_align_threshold();
475 let discr_ident_lens: Vec<usize> = enum_def
478 .filter(|var| var.disr_expr.is_some())
479 .map(|var| rewrite_ident(&self.get_context(), var.ident).len())
481 // cut the list at the point of longest discrim shorter than the threshold
482 // All of the discrims under the threshold will get padded, and all above - left as is.
483 let pad_discrim_ident_to = *discr_ident_lens
485 .filter(|&l| *l <= align_threshold)
489 let itemize_list_with = |one_line_width: usize| {
491 self.snippet_provider,
492 enum_def.variants.iter(),
496 if !f.attrs.is_empty() {
503 |f| self.format_variant(f, one_line_width, pad_discrim_ident_to),
510 let mut items: Vec<_> = itemize_list_with(self.config.struct_variant_width());
512 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
513 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
514 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
515 if has_multiline_variant && has_single_line_variant {
516 items = itemize_list_with(0);
519 let shape = self.shape().sub_width(2)?;
520 let fmt = ListFormatting::new(shape, self.config)
521 .trailing_separator(self.config.trailing_comma())
522 .preserve_newline(true);
524 let list = write_list(&items, &fmt)?;
525 result.push_str(&list);
526 result.push_str(&original_offset.to_string_with_newline(self.config));
531 // Variant of an enum.
534 field: &ast::Variant,
535 one_line_width: usize,
536 pad_discrim_ident_to: usize,
537 ) -> Option<String> {
538 if contains_skip(&field.attrs) {
539 let lo = field.attrs[0].span.lo();
540 let span = mk_sp(lo, field.span.hi());
541 return Some(self.snippet(span).to_owned());
544 let context = self.get_context();
546 let shape = self.shape().sub_width(1)?;
547 let attrs_str = field.attrs.rewrite(&context, shape)?;
551 .map_or(field.span.lo(), |attr| attr.span.hi());
552 let span = mk_sp(lo, field.span.lo());
554 let variant_body = match field.data {
555 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
557 &StructParts::from_variant(field),
559 Some(one_line_width),
561 ast::VariantData::Unit(..) => rewrite_ident(&context, field.ident).to_owned(),
564 let variant_body = if let Some(ref expr) = field.disr_expr {
565 let lhs = format!("{:1$} =", variant_body, pad_discrim_ident_to);
566 rewrite_assign_rhs_with(
571 RhsTactics::AllowOverflow,
577 combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
580 fn visit_impl_items(&mut self, items: &[ptr::P<ast::AssocItem>]) {
581 if self.get_context().config.reorder_impl_items() {
582 // Create visitor for each items, then reorder them.
583 let mut buffer = vec![];
585 self.visit_impl_item(item);
586 buffer.push((self.buffer.clone(), item.clone()));
590 fn is_type(ty: &Option<rustc_ast::ptr::P<ast::Ty>>) -> bool {
591 if let Some(lty) = ty {
592 if let ast::TyKind::ImplTrait(..) = lty.kind {
599 fn is_opaque(ty: &Option<rustc_ast::ptr::P<ast::Ty>>) -> bool {
604 a: &Option<rustc_ast::ptr::P<ast::Ty>>,
605 b: &Option<rustc_ast::ptr::P<ast::Ty>>,
607 is_type(a) && is_type(b)
611 a: &Option<rustc_ast::ptr::P<ast::Ty>>,
612 b: &Option<rustc_ast::ptr::P<ast::Ty>>,
614 is_opaque(a) && is_opaque(b)
617 // In rustc-ap-v638 the `OpaqueTy` AssocItemKind variant was removed but
618 // we still need to differentiate to maintain sorting order.
620 // type -> opaque -> const -> macro -> method
621 use crate::ast::AssocItemKind::*;
622 fn need_empty_line(a: &ast::AssocItemKind, b: &ast::AssocItemKind) -> bool {
624 (TyAlias(lty), TyAlias(rty))
625 if both_type(<y.3, &rty.3) || both_opaque(<y.3, &rty.3) =>
629 (Const(..), Const(..)) => false,
634 buffer.sort_by(|(_, a), (_, b)| match (&a.kind, &b.kind) {
635 (TyAlias(lty), TyAlias(rty))
636 if both_type(<y.3, &rty.3) || both_opaque(<y.3, &rty.3) =>
638 a.ident.as_str().cmp(&b.ident.as_str())
640 (Const(..), Const(..)) | (MacCall(..), MacCall(..)) => {
641 a.ident.as_str().cmp(&b.ident.as_str())
643 (Fn(..), Fn(..)) => a.span.lo().cmp(&b.span.lo()),
644 (TyAlias(ty), _) if is_type(&ty.3) => Ordering::Less,
645 (_, TyAlias(ty)) if is_type(&ty.3) => Ordering::Greater,
646 (TyAlias(..), _) => Ordering::Less,
647 (_, TyAlias(..)) => Ordering::Greater,
648 (Const(..), _) => Ordering::Less,
649 (_, Const(..)) => Ordering::Greater,
650 (MacCall(..), _) => Ordering::Less,
651 (_, MacCall(..)) => Ordering::Greater,
653 let mut prev_kind = None;
654 for (buf, item) in buffer {
655 // Make sure that there are at least a single empty line between
656 // different impl items.
659 .map_or(false, |prev_kind| need_empty_line(prev_kind, &item.kind))
663 let indent_str = self.block_indent.to_string_with_newline(self.config);
664 self.push_str(&indent_str);
665 self.push_str(buf.trim());
666 prev_kind = Some(item.kind.clone());
670 self.visit_impl_item(item);
676 pub(crate) fn format_impl(
677 context: &RewriteContext<'_>,
680 ) -> Option<String> {
681 if let ast::ItemKind::Impl(impl_kind) = &item.kind {
688 let mut result = String::with_capacity(128);
689 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
690 let sep = offset.to_string_with_newline(context.config);
691 result.push_str(&ref_and_type);
693 let where_budget = if result.contains('\n') {
694 context.config.max_width()
696 context.budget(last_line_width(&result))
699 let mut option = WhereClauseOption::snuggled(&ref_and_type);
700 let snippet = context.snippet(item.span);
701 let open_pos = snippet.find_uncommented("{")? + 1;
702 if !contains_comment(&snippet[open_pos..])
704 && generics.where_clause.predicates.len() == 1
705 && !result.contains('\n')
707 option.suppress_comma();
709 option.allow_single_line();
712 let missing_span = mk_sp(self_ty.span.hi(), item.span.hi());
713 let where_span_end = context.snippet_provider.opt_span_before(missing_span, "{");
714 let where_clause_str = rewrite_where_clause(
716 &generics.where_clause,
717 context.config.brace_style(),
718 Shape::legacy(where_budget, offset.block_only()),
726 // If there is no where-clause, we may have missing comments between the trait name and
727 // the opening brace.
728 if generics.where_clause.predicates.is_empty() {
729 if let Some(hi) = where_span_end {
730 match recover_missing_comment_in_span(
731 mk_sp(self_ty.span.hi(), hi),
732 Shape::indented(offset, context.config),
734 last_line_width(&result),
736 Some(ref missing_comment) if !missing_comment.is_empty() => {
737 result.push_str(missing_comment);
744 if is_impl_single_line(context, items.as_slice(), &result, &where_clause_str, item)? {
745 result.push_str(&where_clause_str);
746 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
747 // if the where_clause contains extra comments AND
748 // there is only one where-clause predicate
749 // recover the suppressed comma in single line where_clause formatting
750 if generics.where_clause.predicates.len() == 1 {
753 result.push_str(&format!("{}{{{}}}", sep, sep));
755 result.push_str(" {}");
760 result.push_str(&where_clause_str);
762 let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
763 match context.config.brace_style() {
764 _ if need_newline => result.push_str(&sep),
765 BraceStyle::AlwaysNextLine => result.push_str(&sep),
766 BraceStyle::PreferSameLine => result.push(' '),
767 BraceStyle::SameLineWhere => {
768 if !where_clause_str.is_empty() {
769 result.push_str(&sep);
777 // this is an impl body snippet(impl SampleImpl { /* here */ })
778 let lo = max(self_ty.span.hi(), generics.where_clause.span.hi());
779 let snippet = context.snippet(mk_sp(lo, item.span.hi()));
780 let open_pos = snippet.find_uncommented("{")? + 1;
782 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
783 let mut visitor = FmtVisitor::from_context(context);
784 let item_indent = offset.block_only().block_indent(context.config);
785 visitor.block_indent = item_indent;
786 visitor.last_pos = lo + BytePos(open_pos as u32);
788 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
789 visitor.visit_impl_items(items);
791 visitor.format_missing(item.span.hi() - BytePos(1));
793 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
794 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
796 result.push_str(&inner_indent_str);
797 result.push_str(visitor.buffer.trim());
798 result.push_str(&outer_indent_str);
799 } else if need_newline || !context.config.empty_item_single_line() {
800 result.push_str(&sep);
811 fn is_impl_single_line(
812 context: &RewriteContext<'_>,
813 items: &[ptr::P<ast::AssocItem>],
815 where_clause_str: &str,
818 let snippet = context.snippet(item.span);
819 let open_pos = snippet.find_uncommented("{")? + 1;
822 context.config.empty_item_single_line()
824 && !result.contains('\n')
825 && result.len() + where_clause_str.len() <= context.config.max_width()
826 && !contains_comment(&snippet[open_pos..]),
830 fn format_impl_ref_and_type(
831 context: &RewriteContext<'_>,
834 ) -> Option<String> {
835 if let ast::ItemKind::Impl(impl_kind) = &item.kind {
842 of_trait: ref trait_ref,
846 let mut result = String::with_capacity(128);
848 result.push_str(&format_visibility(context, &item.vis));
849 result.push_str(format_defaultness(defaultness));
850 result.push_str(format_unsafety(unsafety));
852 let shape = if context.config.version() == Version::Two {
853 Shape::indented(offset + last_line_width(&result), context.config)
855 generics_shape_from_config(
857 Shape::indented(offset + last_line_width(&result), context.config),
861 let generics_str = rewrite_generics(context, "impl", generics, shape)?;
862 result.push_str(&generics_str);
863 result.push_str(format_constness_right(constness));
865 let polarity_str = match polarity {
866 ast::ImplPolarity::Negative(_) => "!",
867 ast::ImplPolarity::Positive => "",
870 let polarity_overhead;
871 let trait_ref_overhead;
872 if let Some(ref trait_ref) = *trait_ref {
873 let result_len = last_line_width(&result);
874 result.push_str(&rewrite_trait_ref(
881 polarity_overhead = 0; // already written
882 trait_ref_overhead = " for".len();
884 polarity_overhead = polarity_str.len();
885 trait_ref_overhead = 0;
888 // Try to put the self type in a single line.
889 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
890 // If there is no where-clause adapt budget for type formatting to take space and curly
891 // brace into account.
892 match context.config.brace_style() {
893 BraceStyle::AlwaysNextLine => 0,
899 let used_space = last_line_width(&result)
902 + curly_brace_overhead;
903 // 1 = space before the type.
904 let budget = context.budget(used_space + 1);
905 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
906 if !self_ty_str.contains('\n') {
907 if trait_ref.is_some() {
908 result.push_str(" for ");
911 result.push_str(polarity_str);
913 result.push_str(&self_ty_str);
918 // Couldn't fit the self type on a single line, put it on a new line.
920 // Add indentation of one additional tab.
921 let new_line_offset = offset.block_indent(context.config);
922 result.push_str(&new_line_offset.to_string(context.config));
923 if trait_ref.is_some() {
924 result.push_str("for ");
926 result.push_str(polarity_str);
928 let budget = context.budget(last_line_width(&result) + polarity_overhead);
929 let type_offset = match context.config.indent_style() {
930 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
931 IndentStyle::Block => new_line_offset,
933 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
940 fn rewrite_trait_ref(
941 context: &RewriteContext<'_>,
942 trait_ref: &ast::TraitRef,
946 ) -> Option<String> {
947 // 1 = space between generics and trait_ref
948 let used_space = 1 + polarity_str.len() + result_len;
949 let shape = Shape::indented(offset + used_space, context.config);
950 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
951 if !trait_ref_str.contains('\n') {
952 return Some(format!(" {}{}", polarity_str, trait_ref_str));
955 // We could not make enough space for trait_ref, so put it on new line.
956 let offset = offset.block_indent(context.config);
957 let shape = Shape::indented(offset, context.config);
958 let trait_ref_str = trait_ref.rewrite(context, shape)?;
961 offset.to_string_with_newline(context.config),
967 pub(crate) struct StructParts<'a> {
969 ident: symbol::Ident,
970 vis: &'a ast::Visibility,
971 def: &'a ast::VariantData,
972 generics: Option<&'a ast::Generics>,
976 impl<'a> StructParts<'a> {
977 fn format_header(&self, context: &RewriteContext<'_>, offset: Indent) -> String {
978 format_header(context, self.prefix, self.ident, self.vis, offset)
981 fn from_variant(variant: &'a ast::Variant) -> Self {
984 ident: variant.ident,
985 vis: &DEFAULT_VISIBILITY,
992 pub(crate) fn from_item(item: &'a ast::Item) -> Self {
993 let (prefix, def, generics) = match item.kind {
994 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
995 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
1003 generics: Some(generics),
1010 context: &RewriteContext<'_>,
1011 struct_parts: &StructParts<'_>,
1013 one_line_width: Option<usize>,
1014 ) -> Option<String> {
1015 match *struct_parts.def {
1016 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
1017 ast::VariantData::Tuple(ref fields, _) => {
1018 format_tuple_struct(context, struct_parts, fields, offset)
1020 ast::VariantData::Struct(ref fields, _) => {
1021 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
1026 pub(crate) fn format_trait(
1027 context: &RewriteContext<'_>,
1030 ) -> Option<String> {
1031 if let ast::ItemKind::Trait(trait_kind) = &item.kind {
1032 let ast::TraitKind(is_auto, unsafety, ref generics, ref generic_bounds, ref trait_items) =
1034 let mut result = String::with_capacity(128);
1035 let header = format!(
1037 format_visibility(context, &item.vis),
1038 format_unsafety(unsafety),
1039 format_auto(is_auto),
1041 result.push_str(&header);
1043 let body_lo = context.snippet_provider.span_after(item.span, "{");
1045 let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
1047 rewrite_generics(context, rewrite_ident(context, item.ident), generics, shape)?;
1048 result.push_str(&generics_str);
1050 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
1051 if !generic_bounds.is_empty() {
1052 let ident_hi = context
1054 .span_after(item.span, &item.ident.as_str());
1055 let bound_hi = generic_bounds.last().unwrap().span().hi();
1056 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
1057 if contains_comment(snippet) {
1061 result = rewrite_assign_rhs_with(
1066 RhsTactics::ForceNextLineWithoutIndent,
1070 // Rewrite where-clause.
1071 if !generics.where_clause.predicates.is_empty() {
1072 let where_on_new_line = context.config.indent_style() != IndentStyle::Block;
1074 let where_budget = context.budget(last_line_width(&result));
1075 let pos_before_where = if generic_bounds.is_empty() {
1076 generics.where_clause.span.lo()
1078 generic_bounds[generic_bounds.len() - 1].span().hi()
1080 let option = WhereClauseOption::snuggled(&generics_str);
1081 let where_clause_str = rewrite_where_clause(
1083 &generics.where_clause,
1084 context.config.brace_style(),
1085 Shape::legacy(where_budget, offset.block_only()),
1092 // If the where-clause cannot fit on the same line,
1093 // put the where-clause on a new line
1094 if !where_clause_str.contains('\n')
1095 && last_line_width(&result) + where_clause_str.len() + offset.width()
1096 > context.config.comment_width()
1098 let width = offset.block_indent + context.config.tab_spaces() - 1;
1099 let where_indent = Indent::new(0, width);
1100 result.push_str(&where_indent.to_string_with_newline(context.config));
1102 result.push_str(&where_clause_str);
1104 let item_snippet = context.snippet(item.span);
1105 if let Some(lo) = item_snippet.find('/') {
1107 let comment_hi = body_lo - BytePos(1);
1108 let comment_lo = item.span.lo() + BytePos(lo as u32);
1109 if comment_lo < comment_hi {
1110 match recover_missing_comment_in_span(
1111 mk_sp(comment_lo, comment_hi),
1112 Shape::indented(offset, context.config),
1114 last_line_width(&result),
1116 Some(ref missing_comment) if !missing_comment.is_empty() => {
1117 result.push_str(missing_comment);
1125 match context.config.brace_style() {
1126 _ if last_line_contains_single_line_comment(&result)
1127 || last_line_width(&result) + 2 > context.budget(offset.width()) =>
1129 result.push_str(&offset.to_string_with_newline(context.config));
1131 BraceStyle::AlwaysNextLine => {
1132 result.push_str(&offset.to_string_with_newline(context.config));
1134 BraceStyle::PreferSameLine => result.push(' '),
1135 BraceStyle::SameLineWhere => {
1136 if result.contains('\n')
1137 || (!generics.where_clause.predicates.is_empty() && !trait_items.is_empty())
1139 result.push_str(&offset.to_string_with_newline(context.config));
1147 let block_span = mk_sp(generics.where_clause.span.hi(), item.span.hi());
1148 let snippet = context.snippet(block_span);
1149 let open_pos = snippet.find_uncommented("{")? + 1;
1150 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
1152 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1153 let mut visitor = FmtVisitor::from_context(context);
1154 visitor.block_indent = offset.block_only().block_indent(context.config);
1155 visitor.last_pos = block_span.lo() + BytePos(open_pos as u32);
1157 for item in trait_items {
1158 visitor.visit_trait_item(item);
1161 visitor.format_missing(item.span.hi() - BytePos(1));
1163 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
1165 result.push_str(&inner_indent_str);
1166 result.push_str(visitor.buffer.trim());
1167 result.push_str(&outer_indent_str);
1168 } else if result.contains('\n') {
1169 result.push_str(&outer_indent_str);
1179 struct OpaqueTypeBounds<'a> {
1180 generic_bounds: &'a ast::GenericBounds,
1183 impl<'a> Rewrite for OpaqueTypeBounds<'a> {
1184 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1186 .rewrite(context, shape)
1187 .map(|s| format!("impl {}", s))
1191 pub(crate) struct TraitAliasBounds<'a> {
1192 generic_bounds: &'a ast::GenericBounds,
1193 generics: &'a ast::Generics,
1196 impl<'a> Rewrite for TraitAliasBounds<'a> {
1197 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1198 let generic_bounds_str = self.generic_bounds.rewrite(context, shape)?;
1200 let mut option = WhereClauseOption::new(true, WhereClauseSpace::None);
1201 option.allow_single_line();
1203 let where_str = rewrite_where_clause(
1205 &self.generics.where_clause,
1206 context.config.brace_style(),
1211 self.generics.where_clause.span.lo(),
1215 let fits_single_line = !generic_bounds_str.contains('\n')
1216 && !where_str.contains('\n')
1217 && generic_bounds_str.len() + where_str.len() < shape.width;
1218 let space = if generic_bounds_str.is_empty() || where_str.is_empty() {
1220 } else if fits_single_line {
1223 shape.indent.to_string_with_newline(&context.config)
1226 Some(format!("{}{}{}", generic_bounds_str, space, where_str))
1230 pub(crate) fn format_trait_alias(
1231 context: &RewriteContext<'_>,
1232 ident: symbol::Ident,
1233 vis: &ast::Visibility,
1234 generics: &ast::Generics,
1235 generic_bounds: &ast::GenericBounds,
1237 ) -> Option<String> {
1238 let alias = rewrite_ident(context, ident);
1239 // 6 = "trait ", 2 = " ="
1240 let g_shape = shape.offset_left(6)?.sub_width(2)?;
1241 let generics_str = rewrite_generics(context, &alias, generics, g_shape)?;
1242 let vis_str = format_visibility(context, vis);
1243 let lhs = format!("{}trait {} =", vis_str, generics_str);
1245 let trait_alias_bounds = TraitAliasBounds {
1249 rewrite_assign_rhs(context, lhs, &trait_alias_bounds, shape.sub_width(1)?).map(|s| s + ";")
1252 fn format_unit_struct(
1253 context: &RewriteContext<'_>,
1254 p: &StructParts<'_>,
1256 ) -> Option<String> {
1257 let header_str = format_header(context, p.prefix, p.ident, p.vis, offset);
1258 let generics_str = if let Some(generics) = p.generics {
1259 let hi = context.snippet_provider.span_before(p.span, ";");
1263 context.config.brace_style(),
1266 // make a span that starts right after `struct Foo`
1267 mk_sp(p.ident.span.hi(), hi),
1268 last_line_width(&header_str),
1273 Some(format!("{}{};", header_str, generics_str))
1276 pub(crate) fn format_struct_struct(
1277 context: &RewriteContext<'_>,
1278 struct_parts: &StructParts<'_>,
1279 fields: &[ast::FieldDef],
1281 one_line_width: Option<usize>,
1282 ) -> Option<String> {
1283 let mut result = String::with_capacity(1024);
1284 let span = struct_parts.span;
1286 let header_str = struct_parts.format_header(context, offset);
1287 result.push_str(&header_str);
1289 let header_hi = struct_parts.ident.span.hi();
1290 let body_lo = context.snippet_provider.span_after(span, "{");
1292 let generics_str = match struct_parts.generics {
1293 Some(g) => format_generics(
1296 context.config.brace_style(),
1297 if fields.is_empty() {
1298 BracePos::ForceSameLine
1303 // make a span that starts right after `struct Foo`
1304 mk_sp(header_hi, body_lo),
1305 last_line_width(&result),
1308 // 3 = ` {}`, 2 = ` {`.
1309 let overhead = if fields.is_empty() { 3 } else { 2 };
1310 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1311 || context.config.max_width() < overhead + result.len()
1313 format!("\n{}{{", offset.block_only().to_string(context.config))
1320 let overhead = if fields.is_empty() { 1 } else { 0 };
1321 let total_width = result.len() + generics_str.len() + overhead;
1322 if !generics_str.is_empty()
1323 && !generics_str.contains('\n')
1324 && total_width > context.config.max_width()
1327 result.push_str(&offset.to_string(context.config));
1328 result.push_str(generics_str.trim_start());
1330 result.push_str(&generics_str);
1333 if fields.is_empty() {
1334 let inner_span = mk_sp(body_lo, span.hi() - BytePos(1));
1335 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "", "}");
1336 return Some(result);
1340 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1341 let one_line_budget =
1342 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1344 let items_str = rewrite_with_alignment(
1347 Shape::indented(offset.block_indent(context.config), context.config).sub_width(1)?,
1348 mk_sp(body_lo, span.hi()),
1352 if !items_str.contains('\n')
1353 && !result.contains('\n')
1354 && items_str.len() <= one_line_budget
1355 && !last_line_contains_single_line_comment(&items_str)
1357 Some(format!("{} {} }}", result, items_str))
1363 .block_indent(context.config)
1364 .to_string(context.config),
1366 offset.to_string(context.config)
1371 fn get_bytepos_after_visibility(vis: &ast::Visibility, default_span: Span) -> BytePos {
1373 ast::VisibilityKind::Crate(..) | ast::VisibilityKind::Restricted { .. } => vis.span.hi(),
1374 _ => default_span.lo(),
1378 // Format tuple or struct without any fields. We need to make sure that the comments
1379 // inside the delimiters are preserved.
1380 fn format_empty_struct_or_tuple(
1381 context: &RewriteContext<'_>,
1384 result: &mut String,
1388 // 3 = " {}" or "();"
1389 let used_width = last_line_used_width(&result, offset.width()) + 3;
1390 if used_width > context.config.max_width() {
1391 result.push_str(&offset.to_string_with_newline(context.config))
1393 result.push_str(opener);
1394 match rewrite_missing_comment(span, Shape::indented(offset, context.config), context) {
1395 Some(ref s) if s.is_empty() => (),
1397 if !is_single_line(s) || first_line_contains_single_line_comment(s) {
1398 let nested_indent_str = offset
1399 .block_indent(context.config)
1400 .to_string_with_newline(context.config);
1401 result.push_str(&nested_indent_str);
1404 if last_line_contains_single_line_comment(s) {
1405 result.push_str(&offset.to_string_with_newline(context.config));
1408 None => result.push_str(context.snippet(span)),
1410 result.push_str(closer);
1413 fn format_tuple_struct(
1414 context: &RewriteContext<'_>,
1415 struct_parts: &StructParts<'_>,
1416 fields: &[ast::FieldDef],
1418 ) -> Option<String> {
1419 let mut result = String::with_capacity(1024);
1420 let span = struct_parts.span;
1422 let header_str = struct_parts.format_header(context, offset);
1423 result.push_str(&header_str);
1425 let body_lo = if fields.is_empty() {
1426 let lo = get_bytepos_after_visibility(struct_parts.vis, span);
1429 .span_after(mk_sp(lo, span.hi()), "(")
1433 let body_hi = if fields.is_empty() {
1436 .span_after(mk_sp(body_lo, span.hi()), ")")
1438 // This is a dirty hack to work around a missing `)` from the span of the last field.
1439 let last_arg_span = fields[fields.len() - 1].span;
1442 .opt_span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1443 .unwrap_or_else(|| last_arg_span.hi())
1446 let where_clause_str = match struct_parts.generics {
1448 let budget = context.budget(last_line_width(&header_str));
1449 let shape = Shape::legacy(budget, offset);
1450 let generics_str = rewrite_generics(context, "", generics, shape)?;
1451 result.push_str(&generics_str);
1453 let where_budget = context.budget(last_line_width(&result));
1454 let option = WhereClauseOption::new(true, WhereClauseSpace::Newline);
1455 rewrite_where_clause(
1457 &generics.where_clause,
1458 context.config.brace_style(),
1459 Shape::legacy(where_budget, offset.block_only()),
1467 None => "".to_owned(),
1470 if fields.is_empty() {
1471 let body_hi = context
1473 .span_before(mk_sp(body_lo, span.hi()), ")");
1474 let inner_span = mk_sp(body_lo, body_hi);
1475 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "(", ")");
1477 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1478 let lo = if let Some(generics) = struct_parts.generics {
1481 struct_parts.ident.span.hi()
1483 result = overflow::rewrite_with_parens(
1488 mk_sp(lo, span.hi()),
1489 context.config.fn_call_width(),
1494 if !where_clause_str.is_empty()
1495 && !where_clause_str.contains('\n')
1496 && (result.contains('\n')
1497 || offset.block_indent + result.len() + where_clause_str.len() + 1
1498 > context.config.max_width())
1500 // We need to put the where-clause on a new line, but we didn't
1501 // know that earlier, so the where-clause will not be indented properly.
1504 &(offset.block_only() + (context.config.tab_spaces() - 1)).to_string(context.config),
1507 result.push_str(&where_clause_str);
1512 pub(crate) fn rewrite_type<R: Rewrite>(
1513 context: &RewriteContext<'_>,
1515 ident: symbol::Ident,
1516 vis: &ast::Visibility,
1517 generics: &ast::Generics,
1518 generic_bounds_opt: Option<&ast::GenericBounds>,
1521 ) -> Option<String> {
1522 let mut result = String::with_capacity(128);
1523 result.push_str(&format!("{}type ", format_visibility(context, vis)));
1524 let ident_str = rewrite_ident(context, ident);
1526 if generics.params.is_empty() {
1527 result.push_str(ident_str)
1530 let g_shape = Shape::indented(indent, context.config)
1531 .offset_left(result.len())?
1533 let generics_str = rewrite_generics(context, ident_str, generics, g_shape)?;
1534 result.push_str(&generics_str);
1537 if let Some(bounds) = generic_bounds_opt {
1538 if !bounds.is_empty() {
1540 let shape = Shape::indented(indent, context.config).offset_left(result.len() + 2)?;
1541 let type_bounds = bounds.rewrite(context, shape).map(|s| format!(": {}", s))?;
1542 result.push_str(&type_bounds);
1546 let where_budget = context.budget(last_line_width(&result));
1547 let mut option = WhereClauseOption::snuggled(&result);
1549 option.suppress_comma();
1551 let where_clause_str = rewrite_where_clause(
1553 &generics.where_clause,
1554 context.config.brace_style(),
1555 Shape::legacy(where_budget, indent),
1562 result.push_str(&where_clause_str);
1564 if let Some(ty) = rhs {
1565 // If there's a where clause, add a newline before the assignment. Otherwise just add a
1567 let has_where = !generics.where_clause.predicates.is_empty();
1569 result.push_str(&indent.to_string_with_newline(context.config));
1574 let comment_span = context
1576 .opt_span_before(span, "=")
1577 .map(|op_lo| mk_sp(generics.where_clause.span.hi(), op_lo));
1579 let lhs = match comment_span {
1581 if contains_comment(context.snippet_provider.span_to_snippet(comment_span)?) =>
1583 let comment_shape = if has_where {
1584 Shape::indented(indent, context.config)
1586 Shape::indented(indent, context.config)
1587 .block_left(context.config.tab_spaces())?
1590 combine_strs_with_missing_comments(
1599 _ => format!("{}=", result),
1603 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1604 rewrite_assign_rhs(context, lhs, &*ty, shape).map(|s| s + ";")
1606 Some(format!("{};", result))
1610 pub(crate) fn rewrite_opaque_type(
1611 context: &RewriteContext<'_>,
1613 ident: symbol::Ident,
1614 generic_bounds: &ast::GenericBounds,
1615 generics: &ast::Generics,
1616 vis: &ast::Visibility,
1618 ) -> Option<String> {
1619 let opaque_type_bounds = OpaqueTypeBounds { generic_bounds };
1626 Some(generic_bounds),
1627 Some(&opaque_type_bounds),
1632 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1634 if config.space_before_colon() { " " } else { "" },
1635 if config.space_after_colon() { " " } else { "" },
1639 pub(crate) fn rewrite_struct_field_prefix(
1640 context: &RewriteContext<'_>,
1641 field: &ast::FieldDef,
1642 ) -> Option<String> {
1643 let vis = format_visibility(context, &field.vis);
1644 let type_annotation_spacing = type_annotation_spacing(context.config);
1645 Some(match field.ident {
1646 Some(name) => format!(
1649 rewrite_ident(context, name),
1650 type_annotation_spacing.0
1652 None => vis.to_string(),
1656 impl Rewrite for ast::FieldDef {
1657 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1658 rewrite_struct_field(context, self, shape, 0)
1662 pub(crate) fn rewrite_struct_field(
1663 context: &RewriteContext<'_>,
1664 field: &ast::FieldDef,
1666 lhs_max_width: usize,
1667 ) -> Option<String> {
1668 if contains_skip(&field.attrs) {
1669 return Some(context.snippet(field.span()).to_owned());
1672 let type_annotation_spacing = type_annotation_spacing(context.config);
1673 let prefix = rewrite_struct_field_prefix(context, field)?;
1675 let attrs_str = field.attrs.rewrite(context, shape)?;
1676 let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
1677 let missing_span = if field.attrs.is_empty() {
1678 mk_sp(field.span.lo(), field.span.lo())
1680 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1682 let mut spacing = String::from(if field.ident.is_some() {
1683 type_annotation_spacing.1
1687 // Try to put everything on a single line.
1688 let attr_prefix = combine_strs_with_missing_comments(
1696 let overhead = trimmed_last_line_width(&attr_prefix);
1697 let lhs_offset = lhs_max_width.saturating_sub(overhead);
1698 for _ in 0..lhs_offset {
1701 // In this extreme case we will be missing a space between an attribute and a field.
1702 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1706 .offset_left(overhead + spacing.len())
1707 .and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
1708 if let Some(ref ty) = orig_ty {
1709 if !ty.contains('\n') {
1710 return Some(attr_prefix + &spacing + ty);
1714 let is_prefix_empty = prefix.is_empty();
1715 // We must use multiline. We are going to put attributes and a field on different lines.
1716 let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, shape)?;
1717 // Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
1718 let field_str = if is_prefix_empty {
1719 field_str.trim_start()
1723 combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
1726 pub(crate) struct StaticParts<'a> {
1728 vis: &'a ast::Visibility,
1729 ident: symbol::Ident,
1731 mutability: ast::Mutability,
1732 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1733 defaultness: Option<ast::Defaultness>,
1737 impl<'a> StaticParts<'a> {
1738 pub(crate) fn from_item(item: &'a ast::Item) -> Self {
1739 let (defaultness, prefix, ty, mutability, expr) = match item.kind {
1740 ast::ItemKind::Static(ref ty, mutability, ref expr) => {
1741 (None, "static", ty, mutability, expr)
1743 ast::ItemKind::Const(defaultness, ref ty, ref expr) => {
1744 (Some(defaultness), "const", ty, ast::Mutability::Not, expr)
1746 _ => unreachable!(),
1754 expr_opt: expr.as_ref(),
1760 pub(crate) fn from_trait_item(ti: &'a ast::AssocItem) -> Self {
1761 let (defaultness, ty, expr_opt) = match ti.kind {
1762 ast::AssocItemKind::Const(defaultness, ref ty, ref expr_opt) => {
1763 (defaultness, ty, expr_opt)
1765 _ => unreachable!(),
1772 mutability: ast::Mutability::Not,
1773 expr_opt: expr_opt.as_ref(),
1774 defaultness: Some(defaultness),
1779 pub(crate) fn from_impl_item(ii: &'a ast::AssocItem) -> Self {
1780 let (defaultness, ty, expr) = match ii.kind {
1781 ast::AssocItemKind::Const(defaultness, ref ty, ref expr) => (defaultness, ty, expr),
1782 _ => unreachable!(),
1789 mutability: ast::Mutability::Not,
1790 expr_opt: expr.as_ref(),
1791 defaultness: Some(defaultness),
1798 context: &RewriteContext<'_>,
1799 static_parts: &StaticParts<'_>,
1801 ) -> Option<String> {
1802 let colon = colon_spaces(context.config);
1803 let mut prefix = format!(
1805 format_visibility(context, static_parts.vis),
1806 static_parts.defaultness.map_or("", format_defaultness),
1807 static_parts.prefix,
1808 format_mutability(static_parts.mutability),
1809 rewrite_ident(context, static_parts.ident),
1814 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1815 let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
1816 Some(ty_str) => ty_str,
1818 if prefix.ends_with(' ') {
1821 let nested_indent = offset.block_indent(context.config);
1822 let nested_shape = Shape::indented(nested_indent, context.config);
1823 let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
1826 nested_indent.to_string_with_newline(context.config),
1832 if let Some(expr) = static_parts.expr_opt {
1833 let comments_lo = context.snippet_provider.span_after(static_parts.span, "=");
1834 let expr_lo = expr.span.lo();
1835 let comments_span = mk_sp(comments_lo, expr_lo);
1837 let lhs = format!("{}{} =", prefix, ty_str);
1840 let remaining_width = context.budget(offset.block_indent + 1);
1841 rewrite_assign_rhs_with_comments(
1845 Shape::legacy(remaining_width, offset.block_only()),
1846 RhsTactics::Default,
1850 .and_then(|res| recover_comment_removed(res, static_parts.span, context))
1851 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1853 Some(format!("{}{};", prefix, ty_str))
1856 struct OpaqueType<'a> {
1857 bounds: &'a ast::GenericBounds,
1860 impl<'a> Rewrite for OpaqueType<'a> {
1861 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1862 let shape = shape.offset_left(5)?; // `impl `
1864 .rewrite(context, shape)
1865 .map(|s| format!("impl {}", s))
1869 pub(crate) fn rewrite_impl_type(
1870 ident: symbol::Ident,
1871 vis: &ast::Visibility,
1872 defaultness: ast::Defaultness,
1873 ty_opt: Option<&ptr::P<ast::Ty>>,
1874 generics: &ast::Generics,
1875 context: &RewriteContext<'_>,
1878 ) -> Option<String> {
1880 let result = if let Some(rustc_ast::ast::Ty {
1881 kind: ast::TyKind::ImplTrait(_, ref bounds),
1883 }) = ty_opt.map(|t| &**t)
1889 &DEFAULT_VISIBILITY,
1892 Some(&OpaqueType { bounds }),
1896 rewrite_type(context, indent, ident, vis, generics, None, ty_opt, span)
1900 ast::Defaultness::Default(..) => Some(format!("default {}", result)),
1905 impl Rewrite for ast::FnRetTy {
1906 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1908 ast::FnRetTy::Default(_) => Some(String::new()),
1909 ast::FnRetTy::Ty(ref ty) => {
1910 if context.config.version() == Version::One
1911 || context.config.indent_style() == IndentStyle::Visual
1913 let inner_width = shape.width.checked_sub(3)?;
1915 .rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1916 .map(|r| format!("-> {}", r));
1919 ty.rewrite(context, shape.offset_left(3)?)
1920 .map(|s| format!("-> {}", s))
1926 fn is_empty_infer(ty: &ast::Ty, pat_span: Span) -> bool {
1928 ast::TyKind::Infer => ty.span.hi() == pat_span.hi(),
1933 /// Recover any missing comments between the param and the type.
1937 /// A 2-len tuple with the comment before the colon in first position, and the comment after the
1938 /// colon in second position.
1939 fn get_missing_param_comments(
1940 context: &RewriteContext<'_>,
1944 ) -> (String, String) {
1945 let missing_comment_span = mk_sp(pat_span.hi(), ty_span.lo());
1947 let span_before_colon = {
1948 let missing_comment_span_hi = context
1950 .span_before(missing_comment_span, ":");
1951 mk_sp(pat_span.hi(), missing_comment_span_hi)
1953 let span_after_colon = {
1954 let missing_comment_span_lo = context
1956 .span_after(missing_comment_span, ":");
1957 mk_sp(missing_comment_span_lo, ty_span.lo())
1960 let comment_before_colon = rewrite_missing_comment(span_before_colon, shape, context)
1961 .filter(|comment| !comment.is_empty())
1962 .map_or(String::new(), |comment| format!(" {}", comment));
1963 let comment_after_colon = rewrite_missing_comment(span_after_colon, shape, context)
1964 .filter(|comment| !comment.is_empty())
1965 .map_or(String::new(), |comment| format!("{} ", comment));
1966 (comment_before_colon, comment_after_colon)
1969 impl Rewrite for ast::Param {
1970 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1971 let param_attrs_result = self
1973 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1974 // N.B. Doc comments aren't typically valid syntax, but could appear
1975 // in the presence of certain macros - https://github.com/rust-lang/rustfmt/issues/4936
1976 let (span, has_multiple_attr_lines, has_doc_comments) = if !self.attrs.is_empty() {
1977 let num_attrs = self.attrs.len();
1979 mk_sp(self.attrs[num_attrs - 1].span.hi(), self.pat.span.lo()),
1980 param_attrs_result.contains('\n'),
1981 self.attrs.iter().any(|a| a.is_doc_comment()),
1984 (mk_sp(self.span.lo(), self.span.lo()), false, false)
1987 if let Some(ref explicit_self) = self.to_self() {
1988 rewrite_explicit_self(
1991 ¶m_attrs_result,
1994 has_multiple_attr_lines,
1996 } else if is_named_param(self) {
1997 let param_name = &self
1999 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
2000 let mut result = combine_strs_with_missing_comments(
2002 ¶m_attrs_result,
2006 !has_multiple_attr_lines && !has_doc_comments,
2009 if !is_empty_infer(&*self.ty, self.pat.span) {
2010 let (before_comment, after_comment) =
2011 get_missing_param_comments(context, self.pat.span, self.ty.span, shape);
2012 result.push_str(&before_comment);
2013 result.push_str(colon_spaces(context.config));
2014 result.push_str(&after_comment);
2015 let overhead = last_line_width(&result);
2016 let max_width = shape.width.checked_sub(overhead)?;
2017 if let Some(ty_str) = self
2019 .rewrite(context, Shape::legacy(max_width, shape.indent))
2021 result.push_str(&ty_str);
2023 result = combine_strs_with_missing_comments(
2025 &(param_attrs_result + &shape.to_string_with_newline(context.config)),
2029 !has_multiple_attr_lines,
2031 result.push_str(&before_comment);
2032 result.push_str(colon_spaces(context.config));
2033 result.push_str(&after_comment);
2034 let overhead = last_line_width(&result);
2035 let max_width = shape.width.checked_sub(overhead)?;
2038 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
2039 result.push_str(&ty_str);
2045 self.ty.rewrite(context, shape)
2050 fn rewrite_explicit_self(
2051 context: &RewriteContext<'_>,
2052 explicit_self: &ast::ExplicitSelf,
2056 has_multiple_attr_lines: bool,
2057 ) -> Option<String> {
2058 match explicit_self.node {
2059 ast::SelfKind::Region(lt, m) => {
2060 let mut_str = format_mutability(m);
2063 let lifetime_str = l.rewrite(
2065 Shape::legacy(context.config.max_width(), Indent::empty()),
2067 Some(combine_strs_with_missing_comments(
2070 &format!("&{} {}self", lifetime_str, mut_str),
2073 !has_multiple_attr_lines,
2076 None => Some(combine_strs_with_missing_comments(
2079 &format!("&{}self", mut_str),
2082 !has_multiple_attr_lines,
2086 ast::SelfKind::Explicit(ref ty, mutability) => {
2087 let type_str = ty.rewrite(
2089 Shape::legacy(context.config.max_width(), Indent::empty()),
2092 Some(combine_strs_with_missing_comments(
2095 &format!("{}self: {}", format_mutability(mutability), type_str),
2098 !has_multiple_attr_lines,
2101 ast::SelfKind::Value(mutability) => Some(combine_strs_with_missing_comments(
2104 &format!("{}self", format_mutability(mutability)),
2107 !has_multiple_attr_lines,
2112 pub(crate) fn span_lo_for_param(param: &ast::Param) -> BytePos {
2113 if param.attrs.is_empty() {
2114 if is_named_param(param) {
2120 param.attrs[0].span.lo()
2124 pub(crate) fn span_hi_for_param(context: &RewriteContext<'_>, param: &ast::Param) -> BytePos {
2125 match param.ty.kind {
2126 ast::TyKind::Infer if context.snippet(param.ty.span) == "_" => param.ty.span.hi(),
2127 ast::TyKind::Infer if is_named_param(param) => param.pat.span.hi(),
2128 _ => param.ty.span.hi(),
2132 pub(crate) fn is_named_param(param: &ast::Param) -> bool {
2133 if let ast::PatKind::Ident(_, ident, _) = param.pat.kind {
2134 ident.name != symbol::kw::Empty
2140 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
2141 pub(crate) enum FnBraceStyle {
2147 // Return type is (result, force_new_line_for_brace)
2149 context: &RewriteContext<'_>,
2151 ident: symbol::Ident,
2154 fn_brace_style: FnBraceStyle,
2155 ) -> Option<(String, bool, bool)> {
2156 let mut force_new_line_for_brace = false;
2158 let where_clause = &fn_sig.generics.where_clause;
2160 let mut result = String::with_capacity(1024);
2161 result.push_str(&fn_sig.to_str(context));
2164 result.push_str("fn ");
2167 let overhead = if let FnBraceStyle::SameLine = fn_brace_style {
2174 let used_width = last_line_used_width(&result, indent.width());
2175 let one_line_budget = context.budget(used_width + overhead);
2177 width: one_line_budget,
2181 let fd = fn_sig.decl;
2182 let generics_str = rewrite_generics(
2184 rewrite_ident(context, ident),
2188 result.push_str(&generics_str);
2190 let snuggle_angle_bracket = generics_str
2193 .map_or(false, |l| l.trim_start().len() == 1);
2195 // Note that the width and indent don't really matter, we'll re-layout the
2196 // return type later anyway.
2199 .rewrite(context, Shape::indented(indent, context.config))?;
2201 let multi_line_ret_str = ret_str.contains('\n');
2202 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
2205 let (one_line_budget, multi_line_budget, mut param_indent) = compute_budgets_for_params(
2215 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, param_indent: {:?}",
2216 one_line_budget, multi_line_budget, param_indent
2220 // Check if vertical layout was forced.
2221 if one_line_budget == 0
2222 && !snuggle_angle_bracket
2223 && context.config.indent_style() == IndentStyle::Visual
2225 result.push_str(¶m_indent.to_string_with_newline(context.config));
2228 // Skip `pub(crate)`.
2229 let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
2230 // A conservative estimation, the goal is to be over all parens in generics
2231 let params_start = fn_sig
2235 .map_or(lo_after_visibility, |param| param.span().hi());
2236 let params_end = if fd.inputs.is_empty() {
2239 .span_after(mk_sp(params_start, span.hi()), ")")
2241 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
2242 context.snippet_provider.span_after(last_span, ")")
2244 let params_span = mk_sp(
2247 .span_after(mk_sp(params_start, span.hi()), "("),
2250 let param_str = rewrite_params(
2261 let put_params_in_block = match context.config.indent_style() {
2262 IndentStyle::Block => param_str.contains('\n') || param_str.len() > one_line_budget,
2264 } && !fd.inputs.is_empty();
2266 let mut params_last_line_contains_comment = false;
2267 let mut no_params_and_over_max_width = false;
2269 if put_params_in_block {
2270 param_indent = indent.block_indent(context.config);
2271 result.push_str(¶m_indent.to_string_with_newline(context.config));
2272 result.push_str(¶m_str);
2273 result.push_str(&indent.to_string_with_newline(context.config));
2276 result.push_str(¶m_str);
2277 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
2278 // Put the closing brace on the next line if it overflows the max width.
2280 let closing_paren_overflow_max_width =
2281 fd.inputs.is_empty() && used_width + 1 > context.config.max_width();
2282 // If the last line of params contains comment, we cannot put the closing paren
2283 // on the same line.
2284 params_last_line_contains_comment = param_str
2287 .map_or(false, |last_line| last_line.contains("//"));
2289 if context.config.version() == Version::Two {
2290 if closing_paren_overflow_max_width {
2292 result.push_str(&indent.to_string_with_newline(context.config));
2293 no_params_and_over_max_width = true;
2294 } else if params_last_line_contains_comment {
2295 result.push_str(&indent.to_string_with_newline(context.config));
2297 no_params_and_over_max_width = true;
2302 if closing_paren_overflow_max_width || params_last_line_contains_comment {
2303 result.push_str(&indent.to_string_with_newline(context.config));
2310 if let ast::FnRetTy::Ty(..) = fd.output {
2311 let ret_should_indent = match context.config.indent_style() {
2312 // If our params are block layout then we surely must have space.
2313 IndentStyle::Block if put_params_in_block || fd.inputs.is_empty() => false,
2314 _ if params_last_line_contains_comment => false,
2315 _ if result.contains('\n') || multi_line_ret_str => true,
2317 // If the return type would push over the max width, then put the return type on
2318 // a new line. With the +1 for the signature length an additional space between
2319 // the closing parenthesis of the param and the arrow '->' is considered.
2320 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
2322 // If there is no where-clause, take into account the space after the return type
2324 if where_clause.predicates.is_empty() {
2328 sig_length > context.config.max_width()
2331 let ret_shape = if ret_should_indent {
2332 if context.config.version() == Version::One
2333 || context.config.indent_style() == IndentStyle::Visual
2335 let indent = if param_str.is_empty() {
2336 // Aligning with non-existent params looks silly.
2337 force_new_line_for_brace = true;
2340 // FIXME: we might want to check that using the param indent
2341 // doesn't blow our budget, and if it does, then fallback to
2342 // the where-clause indent.
2346 result.push_str(&indent.to_string_with_newline(context.config));
2347 Shape::indented(indent, context.config)
2349 let mut ret_shape = Shape::indented(indent, context.config);
2350 if param_str.is_empty() {
2351 // Aligning with non-existent params looks silly.
2352 force_new_line_for_brace = true;
2353 ret_shape = if context.use_block_indent() {
2354 ret_shape.offset_left(4).unwrap_or(ret_shape)
2356 ret_shape.indent = ret_shape.indent + 4;
2361 result.push_str(&ret_shape.indent.to_string_with_newline(context.config));
2365 if context.config.version() == Version::Two {
2366 if !param_str.is_empty() || !no_params_and_over_max_width {
2373 let ret_shape = Shape::indented(indent, context.config);
2375 .offset_left(last_line_width(&result))
2376 .unwrap_or(ret_shape)
2379 if multi_line_ret_str || ret_should_indent {
2380 // Now that we know the proper indent and width, we need to
2381 // re-layout the return type.
2382 let ret_str = fd.output.rewrite(context, ret_shape)?;
2383 result.push_str(&ret_str);
2385 result.push_str(&ret_str);
2388 // Comment between return type and the end of the decl.
2389 let snippet_lo = fd.output.span().hi();
2390 if where_clause.predicates.is_empty() {
2391 let snippet_hi = span.hi();
2392 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2393 // Try to preserve the layout of the original snippet.
2394 let original_starts_with_newline = snippet
2396 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2397 let original_ends_with_newline = snippet
2398 .rfind(|c| c != ' ')
2399 .map_or(false, |i| snippet[i..].ends_with('\n'));
2400 let snippet = snippet.trim();
2401 if !snippet.is_empty() {
2402 result.push(if original_starts_with_newline {
2407 result.push_str(snippet);
2408 if original_ends_with_newline {
2409 force_new_line_for_brace = true;
2415 let pos_before_where = match fd.output {
2416 ast::FnRetTy::Default(..) => params_span.hi(),
2417 ast::FnRetTy::Ty(ref ty) => ty.span.hi(),
2420 let is_params_multi_lined = param_str.contains('\n');
2422 let space = if put_params_in_block && ret_str.is_empty() {
2423 WhereClauseSpace::Space
2425 WhereClauseSpace::Newline
2427 let mut option = WhereClauseOption::new(fn_brace_style == FnBraceStyle::None, space);
2428 if is_params_multi_lined {
2429 option.veto_single_line();
2431 let where_clause_str = rewrite_where_clause(
2434 context.config.brace_style(),
2435 Shape::indented(indent, context.config),
2442 // If there are neither where-clause nor return type, we may be missing comments between
2444 if where_clause_str.is_empty() {
2445 if let ast::FnRetTy::Default(ret_span) = fd.output {
2446 match recover_missing_comment_in_span(
2447 mk_sp(params_span.hi(), ret_span.hi()),
2450 last_line_width(&result),
2452 Some(ref missing_comment) if !missing_comment.is_empty() => {
2453 result.push_str(missing_comment);
2454 force_new_line_for_brace = true;
2461 result.push_str(&where_clause_str);
2463 let ends_with_comment = last_line_contains_single_line_comment(&result);
2464 force_new_line_for_brace |= ends_with_comment;
2465 force_new_line_for_brace |=
2466 is_params_multi_lined && context.config.where_single_line() && !where_clause_str.is_empty();
2467 Some((result, ends_with_comment, force_new_line_for_brace))
2470 /// Kind of spaces to put before `where`.
2471 #[derive(Copy, Clone)]
2472 enum WhereClauseSpace {
2481 #[derive(Copy, Clone)]
2482 struct WhereClauseOption {
2483 suppress_comma: bool, // Force no trailing comma
2484 snuggle: WhereClauseSpace,
2485 allow_single_line: bool, // Try single line where-clause instead of vertical layout
2486 veto_single_line: bool, // Disallow a single-line where-clause.
2489 impl WhereClauseOption {
2490 fn new(suppress_comma: bool, snuggle: WhereClauseSpace) -> WhereClauseOption {
2494 allow_single_line: false,
2495 veto_single_line: false,
2499 fn snuggled(current: &str) -> WhereClauseOption {
2501 suppress_comma: false,
2502 snuggle: if last_line_width(current) == 1 {
2503 WhereClauseSpace::Space
2505 WhereClauseSpace::Newline
2507 allow_single_line: false,
2508 veto_single_line: false,
2512 fn suppress_comma(&mut self) {
2513 self.suppress_comma = true
2516 fn allow_single_line(&mut self) {
2517 self.allow_single_line = true
2520 fn snuggle(&mut self) {
2521 self.snuggle = WhereClauseSpace::Space
2524 fn veto_single_line(&mut self) {
2525 self.veto_single_line = true;
2530 context: &RewriteContext<'_>,
2531 params: &[ast::Param],
2532 one_line_budget: usize,
2533 multi_line_budget: usize,
2535 param_indent: Indent,
2538 ) -> Option<String> {
2539 if params.is_empty() {
2540 let comment = context
2544 span.hi() - BytePos(1),
2547 return Some(comment.to_owned());
2549 let param_items: Vec<_> = itemize_list(
2550 context.snippet_provider,
2554 |param| span_lo_for_param(param),
2555 |param| param.ty.span.hi(),
2558 .rewrite(context, Shape::legacy(multi_line_budget, param_indent))
2559 .or_else(|| Some(context.snippet(param.span()).to_owned()))
2567 let tactic = definitive_tactic(
2572 .to_list_tactic(param_items.len()),
2576 let budget = match tactic {
2577 DefinitiveListTactic::Horizontal => one_line_budget,
2578 _ => multi_line_budget,
2580 let indent = match context.config.indent_style() {
2581 IndentStyle::Block => indent.block_indent(context.config),
2582 IndentStyle::Visual => param_indent,
2584 let trailing_separator = if variadic {
2585 SeparatorTactic::Never
2587 match context.config.indent_style() {
2588 IndentStyle::Block => context.config.trailing_comma(),
2589 IndentStyle::Visual => SeparatorTactic::Never,
2592 let fmt = ListFormatting::new(Shape::legacy(budget, indent), context.config)
2594 .trailing_separator(trailing_separator)
2595 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2596 .preserve_newline(true);
2597 write_list(¶m_items, &fmt)
2600 fn compute_budgets_for_params(
2601 context: &RewriteContext<'_>,
2605 fn_brace_style: FnBraceStyle,
2606 force_vertical_layout: bool,
2607 ) -> Option<(usize, usize, Indent)> {
2609 "compute_budgets_for_params {} {:?}, {}, {:?}",
2615 // Try keeping everything on the same line.
2616 if !result.contains('\n') && !force_vertical_layout {
2617 // 2 = `()`, 3 = `() `, space is before ret_string.
2618 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2619 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2620 match fn_brace_style {
2621 FnBraceStyle::None => used_space += 1, // 1 = `;`
2622 FnBraceStyle::SameLine => used_space += 2, // 2 = `{}`
2623 FnBraceStyle::NextLine => (),
2625 let one_line_budget = context.budget(used_space);
2627 if one_line_budget > 0 {
2629 let (indent, multi_line_budget) = match context.config.indent_style() {
2630 IndentStyle::Block => {
2631 let indent = indent.block_indent(context.config);
2632 (indent, context.budget(indent.width() + 1))
2634 IndentStyle::Visual => {
2635 let indent = indent + result.len() + 1;
2636 let multi_line_overhead = match fn_brace_style {
2637 FnBraceStyle::SameLine => 4,
2640 (indent, context.budget(multi_line_overhead))
2644 return Some((one_line_budget, multi_line_budget, indent));
2648 // Didn't work. we must force vertical layout and put params on a newline.
2649 let new_indent = indent.block_indent(context.config);
2650 let used_space = match context.config.indent_style() {
2652 IndentStyle::Block => new_indent.width() + 1,
2653 // Account for `)` and possibly ` {`.
2654 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2656 Some((0, context.budget(used_space), new_indent))
2659 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> FnBraceStyle {
2660 let predicate_count = where_clause.predicates.len();
2662 if config.where_single_line() && predicate_count == 1 {
2663 return FnBraceStyle::SameLine;
2665 let brace_style = config.brace_style();
2667 let use_next_line = brace_style == BraceStyle::AlwaysNextLine
2668 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0);
2670 FnBraceStyle::NextLine
2672 FnBraceStyle::SameLine
2676 fn rewrite_generics(
2677 context: &RewriteContext<'_>,
2679 generics: &ast::Generics,
2681 ) -> Option<String> {
2682 // FIXME: convert bounds to where-clauses where they get too big or if
2683 // there is a where-clause at all.
2685 if generics.params.is_empty() {
2686 return Some(ident.to_owned());
2689 let params = generics.params.iter();
2690 overflow::rewrite_with_angle_brackets(context, ident, params, shape, generics.span)
2693 fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2694 match config.indent_style() {
2695 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2696 IndentStyle::Block => {
2700 .block_indent(config.tab_spaces())
2701 .with_max_width(config)
2707 fn rewrite_where_clause_rfc_style(
2708 context: &RewriteContext<'_>,
2709 where_clause: &ast::WhereClause,
2712 span_end: Option<BytePos>,
2713 span_end_before_where: BytePos,
2714 where_clause_option: WhereClauseOption,
2715 ) -> Option<String> {
2716 let (where_keyword, allow_single_line) = rewrite_where_keyword(
2720 span_end_before_where,
2721 where_clause_option,
2725 let clause_shape = shape
2727 .with_max_width(context.config)
2728 .block_left(context.config.tab_spaces())?
2730 let force_single_line = context.config.where_single_line()
2731 && where_clause.predicates.len() == 1
2732 && !where_clause_option.veto_single_line;
2734 let preds_str = rewrite_bounds_on_where_clause(
2740 where_clause_option,
2746 if allow_single_line && !preds_str.contains('\n') && 6 + preds_str.len() <= shape.width
2747 || force_single_line
2751 clause_shape.indent.to_string_with_newline(context.config)
2754 Some(format!("{}{}{}", where_keyword, clause_sep, preds_str))
2757 /// Rewrite `where` and comment around it.
2758 fn rewrite_where_keyword(
2759 context: &RewriteContext<'_>,
2760 where_clause: &ast::WhereClause,
2762 span_end_before_where: BytePos,
2763 where_clause_option: WhereClauseOption,
2764 ) -> Option<(String, bool)> {
2765 let block_shape = shape.block().with_max_width(context.config);
2767 let clause_shape = block_shape
2768 .block_left(context.config.tab_spaces())?
2771 let comment_separator = |comment: &str, shape: Shape| {
2772 if comment.is_empty() {
2775 shape.indent.to_string_with_newline(context.config)
2779 let (span_before, span_after) =
2780 missing_span_before_after_where(span_end_before_where, where_clause);
2781 let (comment_before, comment_after) =
2782 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2784 let starting_newline = match where_clause_option.snuggle {
2785 WhereClauseSpace::Space if comment_before.is_empty() => Cow::from(" "),
2786 WhereClauseSpace::None => Cow::from(""),
2787 _ => block_shape.indent.to_string_with_newline(context.config),
2790 let newline_before_where = comment_separator(&comment_before, shape);
2791 let newline_after_where = comment_separator(&comment_after, clause_shape);
2792 let result = format!(
2794 starting_newline, comment_before, newline_before_where, newline_after_where, comment_after
2796 let allow_single_line = where_clause_option.allow_single_line
2797 && comment_before.is_empty()
2798 && comment_after.is_empty();
2800 Some((result, allow_single_line))
2803 /// Rewrite bounds on a where clause.
2804 fn rewrite_bounds_on_where_clause(
2805 context: &RewriteContext<'_>,
2806 where_clause: &ast::WhereClause,
2809 span_end: Option<BytePos>,
2810 where_clause_option: WhereClauseOption,
2811 force_single_line: bool,
2812 ) -> Option<String> {
2813 let span_start = where_clause.predicates[0].span().lo();
2814 // If we don't have the start of the next span, then use the end of the
2815 // predicates, but that means we miss comments.
2816 let len = where_clause.predicates.len();
2817 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2818 let span_end = span_end.unwrap_or(end_of_preds);
2819 let items = itemize_list(
2820 context.snippet_provider,
2821 where_clause.predicates.iter(),
2824 |pred| pred.span().lo(),
2825 |pred| pred.span().hi(),
2826 |pred| pred.rewrite(context, shape),
2831 let comma_tactic = if where_clause_option.suppress_comma || force_single_line {
2832 SeparatorTactic::Never
2834 context.config.trailing_comma()
2837 // shape should be vertical only and only if we have `force_single_line` option enabled
2838 // and the number of items of the where-clause is equal to 1
2839 let shape_tactic = if force_single_line {
2840 DefinitiveListTactic::Horizontal
2842 DefinitiveListTactic::Vertical
2845 let fmt = ListFormatting::new(shape, context.config)
2846 .tactic(shape_tactic)
2847 .trailing_separator(comma_tactic)
2848 .preserve_newline(true);
2849 write_list(&items.collect::<Vec<_>>(), &fmt)
2852 fn rewrite_where_clause(
2853 context: &RewriteContext<'_>,
2854 where_clause: &ast::WhereClause,
2855 brace_style: BraceStyle,
2859 span_end: Option<BytePos>,
2860 span_end_before_where: BytePos,
2861 where_clause_option: WhereClauseOption,
2862 ) -> Option<String> {
2863 if where_clause.predicates.is_empty() {
2864 return Some(String::new());
2867 if context.config.indent_style() == IndentStyle::Block {
2868 return rewrite_where_clause_rfc_style(
2874 span_end_before_where,
2875 where_clause_option,
2879 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2881 let offset = match context.config.indent_style() {
2882 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2883 // 6 = "where ".len()
2884 IndentStyle::Visual => shape.indent + extra_indent + 6,
2886 // FIXME: if indent_style != Visual, then the budgets below might
2887 // be out by a char or two.
2889 let budget = context.config.max_width() - offset.width();
2890 let span_start = where_clause.predicates[0].span().lo();
2891 // If we don't have the start of the next span, then use the end of the
2892 // predicates, but that means we miss comments.
2893 let len = where_clause.predicates.len();
2894 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2895 let span_end = span_end.unwrap_or(end_of_preds);
2896 let items = itemize_list(
2897 context.snippet_provider,
2898 where_clause.predicates.iter(),
2901 |pred| pred.span().lo(),
2902 |pred| pred.span().hi(),
2903 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2908 let item_vec = items.collect::<Vec<_>>();
2909 // FIXME: we don't need to collect here
2910 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2912 let mut comma_tactic = context.config.trailing_comma();
2913 // Kind of a hack because we don't usually have trailing commas in where-clauses.
2914 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2915 comma_tactic = SeparatorTactic::Never;
2918 let fmt = ListFormatting::new(Shape::legacy(budget, offset), context.config)
2920 .trailing_separator(comma_tactic)
2921 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2922 .preserve_newline(true);
2923 let preds_str = write_list(&item_vec, &fmt)?;
2925 let end_length = if terminator == "{" {
2926 // If the brace is on the next line we don't need to count it otherwise it needs two
2929 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2930 BraceStyle::PreferSameLine => 2,
2932 } else if terminator == "=" {
2938 || preds_str.contains('\n')
2939 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2943 (shape.indent + extra_indent).to_string(context.config),
2947 Some(format!(" where {}", preds_str))
2951 fn missing_span_before_after_where(
2952 before_item_span_end: BytePos,
2953 where_clause: &ast::WhereClause,
2955 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2957 let pos_after_where = where_clause.span.lo() + BytePos(5);
2958 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2959 (missing_span_before, missing_span_after)
2962 fn rewrite_comments_before_after_where(
2963 context: &RewriteContext<'_>,
2964 span_before_where: Span,
2965 span_after_where: Span,
2967 ) -> Option<(String, String)> {
2968 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2969 let after_comment = rewrite_missing_comment(
2971 shape.block_indent(context.config.tab_spaces()),
2974 Some((before_comment, after_comment))
2978 context: &RewriteContext<'_>,
2980 ident: symbol::Ident,
2981 vis: &ast::Visibility,
2984 let mut result = String::with_capacity(128);
2985 let shape = Shape::indented(offset, context.config);
2987 result.push_str(&format_visibility(context, vis).trim());
2989 // Check for a missing comment between the visibility and the item name.
2990 let after_vis = vis.span.hi();
2991 if let Some(before_item_name) = context
2993 .opt_span_before(mk_sp(vis.span.lo(), ident.span.hi()), item_name.trim())
2995 let missing_span = mk_sp(after_vis, before_item_name);
2996 if let Some(result_with_comment) = combine_strs_with_missing_comments(
3002 /* allow_extend */ true,
3004 result = result_with_comment;
3008 result.push_str(&rewrite_ident(context, ident));
3013 #[derive(PartialEq, Eq, Clone, Copy)]
3021 context: &RewriteContext<'_>,
3022 generics: &ast::Generics,
3023 brace_style: BraceStyle,
3024 brace_pos: BracePos,
3028 ) -> Option<String> {
3029 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
3030 let mut result = rewrite_generics(context, "", generics, shape)?;
3032 // If the generics are not parameterized then generics.span.hi() == 0,
3033 // so we use span.lo(), which is the position after `struct Foo`.
3034 let span_end_before_where = if !generics.params.is_empty() {
3039 let (same_line_brace, missed_comments) = if !generics.where_clause.predicates.is_empty() {
3040 let budget = context.budget(last_line_used_width(&result, offset.width()));
3041 let mut option = WhereClauseOption::snuggled(&result);
3042 if brace_pos == BracePos::None {
3043 option.suppress_comma = true;
3045 let where_clause_str = rewrite_where_clause(
3047 &generics.where_clause,
3049 Shape::legacy(budget, offset.block_only()),
3053 span_end_before_where,
3056 result.push_str(&where_clause_str);
3058 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine,
3059 // missed comments are taken care of in #rewrite_where_clause
3064 brace_pos == BracePos::ForceSameLine
3065 || (result.contains('\n') && brace_style == BraceStyle::PreferSameLine
3066 || brace_style != BraceStyle::AlwaysNextLine)
3067 || trimmed_last_line_width(&result) == 1,
3068 rewrite_missing_comment(
3070 span_end_before_where,
3071 if brace_pos == BracePos::None {
3074 context.snippet_provider.span_before(span, "{")
3082 // add missing comments
3083 let missed_line_comments = missed_comments
3084 .filter(|missed_comments| !missed_comments.is_empty())
3085 .map_or(false, |missed_comments| {
3086 let is_block = is_last_comment_block(&missed_comments);
3087 let sep = if is_block { " " } else { "\n" };
3088 result.push_str(sep);
3089 result.push_str(&missed_comments);
3092 if brace_pos == BracePos::None {
3093 return Some(result);
3095 let total_used_width = last_line_used_width(&result, used_width);
3096 let remaining_budget = context.budget(total_used_width);
3097 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
3098 // and hence we take the closer into account as well for one line budget.
3099 // We assume that the closer has the same length as the opener.
3100 let overhead = if brace_pos == BracePos::ForceSameLine {
3107 let forbid_same_line_brace = missed_line_comments || overhead > remaining_budget;
3108 if !forbid_same_line_brace && same_line_brace {
3112 result.push_str(&offset.block_only().to_string(context.config));
3119 impl Rewrite for ast::ForeignItem {
3120 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
3121 let attrs_str = self.attrs.rewrite(context, shape)?;
3122 // Drop semicolon or it will be interpreted as comment.
3123 // FIXME: this may be a faulty span from libsyntax.
3124 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
3126 let item_str = match self.kind {
3127 ast::ForeignItemKind::Fn(ref fn_kind) => {
3128 let ast::FnKind(defaultness, ref fn_sig, ref generics, ref block) = **fn_kind;
3129 if let Some(ref body) = block {
3130 let mut visitor = FmtVisitor::from_context(context);
3131 visitor.block_indent = shape.indent;
3132 visitor.last_pos = self.span.lo();
3133 let inner_attrs = inner_attributes(&self.attrs);
3134 let fn_ctxt = visit::FnCtxt::Foreign;
3136 visit::FnKind::Fn(fn_ctxt, self.ident, &fn_sig, &self.vis, Some(body)),
3143 Some(visitor.buffer.to_owned())
3149 &FnSig::from_method_sig(&fn_sig, generics, &self.vis),
3153 .map(|(s, _, _)| format!("{};", s))
3156 ast::ForeignItemKind::Static(ref ty, mutability, _) => {
3157 // FIXME(#21): we're dropping potential comments in between the
3158 // function kw here.
3159 let vis = format_visibility(context, &self.vis);
3160 let mut_str = format_mutability(mutability);
3161 let prefix = format!(
3165 rewrite_ident(context, self.ident)
3168 rewrite_assign_rhs(context, prefix, &**ty, shape.sub_width(1)?).map(|s| s + ";")
3170 ast::ForeignItemKind::TyAlias(ref ty_alias_kind) => {
3171 let ast::TyAliasKind(_, ref generics, ref generic_bounds, ref type_default) =
3179 Some(generic_bounds),
3180 type_default.as_ref(),
3184 ast::ForeignItemKind::MacCall(ref mac) => {
3185 rewrite_macro(mac, None, context, shape, MacroPosition::Item)
3189 let missing_span = if self.attrs.is_empty() {
3190 mk_sp(self.span.lo(), self.span.lo())
3192 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
3194 combine_strs_with_missing_comments(
3205 /// Rewrite the attributes of an item.
3207 context: &RewriteContext<'_>,
3211 ) -> Option<String> {
3212 let attrs = filter_inline_attrs(&item.attrs, item.span());
3213 let attrs_str = attrs.rewrite(context, shape)?;
3215 let missed_span = if attrs.is_empty() {
3216 mk_sp(item.span.lo(), item.span.lo())
3218 mk_sp(attrs[attrs.len() - 1].span.hi(), item.span.lo())
3221 let allow_extend = if attrs.len() == 1 {
3222 let line_len = attrs_str.len() + 1 + item_str.len();
3223 !attrs.first().unwrap().is_doc_comment()
3224 && context.config.inline_attribute_width() >= line_len
3229 combine_strs_with_missing_comments(
3239 /// Rewrite an inline mod.
3240 /// The given shape is used to format the mod's attributes.
3241 pub(crate) fn rewrite_mod(
3242 context: &RewriteContext<'_>,
3245 ) -> Option<String> {
3246 let mut result = String::with_capacity(32);
3247 result.push_str(&*format_visibility(context, &item.vis));
3248 result.push_str("mod ");
3249 result.push_str(rewrite_ident(context, item.ident));
3251 rewrite_attrs(context, item, &result, attrs_shape)
3254 /// Rewrite `extern crate foo;`.
3255 /// The given shape is used to format the extern crate's attributes.
3256 pub(crate) fn rewrite_extern_crate(
3257 context: &RewriteContext<'_>,
3260 ) -> Option<String> {
3261 assert!(is_extern_crate(item));
3262 let new_str = context.snippet(item.span);
3263 let item_str = if contains_comment(new_str) {
3266 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
3267 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
3269 rewrite_attrs(context, item, &item_str, attrs_shape)
3272 /// Returns `true` for `mod foo;`, false for `mod foo { .. }`.
3273 pub(crate) fn is_mod_decl(item: &ast::Item) -> bool {
3276 ast::ItemKind::Mod(_, ast::ModKind::Loaded(_, ast::Inline::Yes, _))
3280 pub(crate) fn is_use_item(item: &ast::Item) -> bool {
3281 matches!(item.kind, ast::ItemKind::Use(_))
3284 pub(crate) fn is_extern_crate(item: &ast::Item) -> bool {
3285 matches!(item.kind, ast::ItemKind::ExternCrate(..))