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::{source_map, 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, RhsTactics,
22 use crate::lists::{definitive_tactic, itemize_list, write_list, ListFormatting, Separator};
23 use crate::macros::{rewrite_macro, MacroPosition};
25 use crate::rewrite::{Rewrite, RewriteContext};
26 use crate::shape::{Indent, Shape};
27 use crate::source_map::{LineRangeUtils, SpanUtils};
28 use crate::spanned::Spanned;
29 use crate::stmt::Stmt;
31 use crate::vertical::rewrite_with_alignment;
32 use crate::visitor::FmtVisitor;
34 const DEFAULT_VISIBILITY: ast::Visibility = source_map::Spanned {
35 node: ast::VisibilityKind::Inherited,
39 fn type_annotation_separator(config: &Config) -> &str {
43 // Statements of the form
44 // let pat: ty = init;
45 impl Rewrite for ast::Local {
46 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
48 "Local::rewrite {:?} {} {:?}",
49 self, shape.width, shape.indent
52 skip_out_of_file_lines_range!(context, self.span);
54 if contains_skip(&self.attrs) {
58 let attrs_str = self.attrs.rewrite(context, shape)?;
59 let mut result = if attrs_str.is_empty() {
62 combine_strs_with_missing_comments(
67 self.attrs.last().map(|a| a.span.hi()).unwrap(),
76 let pat_shape = shape.offset_left(4)?;
78 let pat_shape = pat_shape.sub_width(1)?;
79 let pat_str = self.pat.rewrite(context, pat_shape)?;
80 result.push_str(&pat_str);
82 // String that is placed within the assignment pattern and expression.
84 let mut infix = String::with_capacity(32);
86 if let Some(ref ty) = self.ty {
87 let separator = type_annotation_separator(context.config);
88 let ty_shape = if pat_str.contains('\n') {
89 shape.with_max_width(context.config)
93 .offset_left(last_line_width(&result) + separator.len())?
97 let rewrite = ty.rewrite(context, ty_shape)?;
99 infix.push_str(separator);
100 infix.push_str(&rewrite);
103 if self.init.is_some() {
104 infix.push_str(" =");
110 result.push_str(&infix);
112 if let Some(ref ex) = self.init {
113 // 1 = trailing semicolon;
114 let nested_shape = shape.sub_width(1)?;
116 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
124 // FIXME convert to using rewrite style rather than visitor
125 // FIXME format modules in this style
128 keyword: &'static str,
129 abi: Cow<'static, str>,
130 vis: Option<&'a ast::Visibility>,
131 body: Vec<BodyElement<'a>>,
136 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
140 ast::Extern::from_abi(fm.abi),
141 config.force_explicit_abi(),
148 .map(|i| BodyElement::ForeignItem(i))
155 enum BodyElement<'a> {
156 // Stmt(&'a ast::Stmt),
157 // Field(&'a ast::Field),
158 // Variant(&'a ast::Variant),
159 // Item(&'a ast::Item),
160 ForeignItem(&'a ast::ForeignItem),
163 /// Represents a fn's signature.
164 pub(crate) struct FnSig<'a> {
165 decl: &'a ast::FnDecl,
166 generics: &'a ast::Generics,
168 is_async: Cow<'a, ast::Async>,
169 constness: ast::Const,
170 defaultness: ast::Defaultness,
171 unsafety: ast::Unsafe,
172 visibility: ast::Visibility,
177 decl: &'a ast::FnDecl,
178 generics: &'a ast::Generics,
179 vis: ast::Visibility,
184 ext: ast::Extern::None,
185 is_async: Cow::Owned(ast::Async::No),
186 constness: ast::Const::No,
187 defaultness: ast::Defaultness::Final,
188 unsafety: ast::Unsafe::No,
193 pub(crate) fn from_method_sig(
194 method_sig: &'a ast::FnSig,
195 generics: &'a ast::Generics,
198 unsafety: method_sig.header.unsafety,
199 is_async: Cow::Borrowed(&method_sig.header.asyncness),
200 constness: method_sig.header.constness,
201 defaultness: ast::Defaultness::Final,
202 ext: method_sig.header.ext,
203 decl: &*method_sig.decl,
205 visibility: DEFAULT_VISIBILITY,
209 pub(crate) fn from_fn_kind(
210 fn_kind: &'a visit::FnKind<'_>,
211 generics: &'a ast::Generics,
212 decl: &'a ast::FnDecl,
213 defaultness: ast::Defaultness,
216 visit::FnKind::Fn(fn_ctxt, _, fn_sig, vis, _) => match fn_ctxt {
217 visit::FnCtxt::Assoc(..) => {
218 let mut fn_sig = FnSig::from_method_sig(fn_sig, generics);
219 fn_sig.defaultness = defaultness;
220 fn_sig.visibility = vis.clone();
226 ext: fn_sig.header.ext,
227 constness: fn_sig.header.constness,
228 is_async: Cow::Borrowed(&fn_sig.header.asyncness),
230 unsafety: fn_sig.header.unsafety,
231 visibility: vis.clone(),
238 fn to_str(&self, context: &RewriteContext<'_>) -> String {
239 let mut result = String::with_capacity(128);
240 // Vis defaultness constness unsafety abi.
241 result.push_str(&*format_visibility(context, &self.visibility));
242 result.push_str(format_defaultness(self.defaultness));
243 result.push_str(format_constness(self.constness));
244 result.push_str(format_async(&self.is_async));
245 result.push_str(format_unsafety(self.unsafety));
246 result.push_str(&format_extern(
248 context.config.force_explicit_abi(),
255 impl<'a> FmtVisitor<'a> {
256 fn format_item(&mut self, item: &Item<'_>) {
257 self.buffer.push_str(&item.abi);
259 let snippet = self.snippet(item.span);
260 let brace_pos = snippet.find_uncommented("{").unwrap();
263 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
264 // FIXME: this skips comments between the extern keyword and the opening
266 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
267 self.block_indent = self.block_indent.block_indent(self.config);
269 if item.body.is_empty() {
270 self.format_missing_no_indent(item.span.hi() - BytePos(1));
271 self.block_indent = self.block_indent.block_unindent(self.config);
272 let indent_str = self.block_indent.to_string(self.config);
273 self.push_str(&indent_str);
275 for item in &item.body {
276 self.format_body_element(item);
279 self.block_indent = self.block_indent.block_unindent(self.config);
280 self.format_missing_with_indent(item.span.hi() - BytePos(1));
285 self.last_pos = item.span.hi();
288 fn format_body_element(&mut self, element: &BodyElement<'_>) {
290 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
294 pub(crate) fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
295 let item = Item::from_foreign_mod(fm, span, self.config);
296 self.format_item(&item);
299 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
300 let rewrite = item.rewrite(&self.get_context(), self.shape());
301 let hi = item.span.hi();
302 let span = if item.attrs.is_empty() {
305 mk_sp(item.attrs[0].span.lo(), hi)
307 self.push_rewrite(span, rewrite);
311 pub(crate) fn rewrite_fn_before_block(
317 ) -> Option<(String, FnBraceStyle)> {
318 let context = self.get_context();
320 let mut fn_brace_style = newline_for_brace(self.config, &fn_sig.generics.where_clause);
321 let (result, force_newline_brace) =
322 rewrite_fn_base(&context, indent, ident, fn_sig, span, fn_brace_style)?;
325 if self.config.brace_style() == BraceStyle::AlwaysNextLine
326 || force_newline_brace
327 || last_line_width(&result) + 2 > self.shape().width
329 fn_brace_style = FnBraceStyle::NextLine
332 Some((result, fn_brace_style))
335 pub(crate) fn rewrite_required_fn(
340 generics: &ast::Generics,
342 ) -> Option<String> {
343 // Drop semicolon or it will be interpreted as comment.
344 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
345 let context = self.get_context();
347 let (mut result, _) = rewrite_fn_base(
351 &FnSig::from_method_sig(sig, generics),
356 // Re-attach semicolon
362 pub(crate) fn single_line_fn(
366 inner_attrs: Option<&[ast::Attribute]>,
367 ) -> Option<String> {
368 if fn_str.contains('\n') || inner_attrs.map_or(false, |a| !a.is_empty()) {
372 let context = self.get_context();
374 if self.config.empty_item_single_line()
375 && is_empty_block(&context, block, None)
376 && self.block_indent.width() + fn_str.len() + 3 <= self.config.max_width()
377 && !last_line_contains_single_line_comment(fn_str)
379 return Some(format!("{} {{}}", fn_str));
382 if !self.config.fn_single_line() || !is_simple_block_stmt(&context, block, None) {
386 let res = Stmt::from_ast_node(block.stmts.first()?, true)
387 .rewrite(&self.get_context(), self.shape())?;
389 let width = self.block_indent.width() + fn_str.len() + res.len() + 5;
390 if !res.contains('\n') && width <= self.config.max_width() {
391 Some(format!("{} {{ {} }}", fn_str, res))
397 pub(crate) fn visit_static(&mut self, static_parts: &StaticParts<'_>) {
398 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
399 self.push_rewrite(static_parts.span, rewrite);
402 pub(crate) fn visit_struct(&mut self, struct_parts: &StructParts<'_>) {
403 let is_tuple = match struct_parts.def {
404 ast::VariantData::Tuple(..) => true,
407 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
408 .map(|s| if is_tuple { s + ";" } else { s });
409 self.push_rewrite(struct_parts.span, rewrite);
412 pub(crate) fn visit_enum(
415 vis: &ast::Visibility,
416 enum_def: &ast::EnumDef,
417 generics: &ast::Generics,
420 let enum_header = format_header(&self.get_context(), "enum ", ident, vis);
421 self.push_str(&enum_header);
423 let enum_snippet = self.snippet(span);
424 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
425 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
426 let generics_str = format_generics(
429 self.config.brace_style(),
430 if enum_def.variants.is_empty() {
431 BracePos::ForceSameLine
436 // make a span that starts right after `enum Foo`
437 mk_sp(ident.span.hi(), body_start),
438 last_line_width(&enum_header),
441 self.push_str(&generics_str);
443 self.last_pos = body_start;
445 match self.format_variant_list(enum_def, body_start, span.hi()) {
446 Some(ref s) if enum_def.variants.is_empty() => self.push_str(s),
448 self.push_rewrite(mk_sp(body_start, span.hi()), rw);
449 self.block_indent = self.block_indent.block_unindent(self.config);
454 // Format the body of an enum definition
455 fn format_variant_list(
457 enum_def: &ast::EnumDef,
460 ) -> Option<String> {
461 if enum_def.variants.is_empty() {
462 let mut buffer = String::with_capacity(128);
464 let span = mk_sp(body_lo, body_hi - BytePos(1));
465 format_empty_struct_or_tuple(
475 let mut result = String::with_capacity(1024);
476 let original_offset = self.block_indent;
477 self.block_indent = self.block_indent.block_indent(self.config);
479 // If enum variants have discriminants, try to vertically align those,
480 // provided the discrims are not shifted too much to the right
481 let align_threshold: usize = self.config.enum_discrim_align_threshold();
482 let discr_ident_lens: Vec<usize> = enum_def
485 .filter(|var| var.disr_expr.is_some())
486 .map(|var| rewrite_ident(&self.get_context(), var.ident).len())
488 // cut the list at the point of longest discrim shorter than the threshold
489 // All of the discrims under the threshold will get padded, and all above - left as is.
490 let pad_discrim_ident_to = *discr_ident_lens
492 .filter(|&l| *l <= align_threshold)
496 let itemize_list_with = |one_line_width: usize| {
498 self.snippet_provider,
499 enum_def.variants.iter(),
503 if !f.attrs.is_empty() {
510 |f| self.format_variant(f, one_line_width, pad_discrim_ident_to),
517 let mut items: Vec<_> =
518 itemize_list_with(self.config.width_heuristics().struct_variant_width);
519 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
520 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
521 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
522 if has_multiline_variant && has_single_line_variant {
523 items = itemize_list_with(0);
526 let shape = self.shape().sub_width(2)?;
527 let fmt = ListFormatting::new(shape, self.config)
528 .trailing_separator(self.config.trailing_comma())
529 .preserve_newline(true);
531 let list = write_list(&items, &fmt)?;
532 result.push_str(&list);
533 result.push_str(&original_offset.to_string_with_newline(self.config));
538 // Variant of an enum.
541 field: &ast::Variant,
542 one_line_width: usize,
543 pad_discrim_ident_to: usize,
544 ) -> Option<String> {
545 if contains_skip(&field.attrs) {
546 let lo = field.attrs[0].span.lo();
547 let span = mk_sp(lo, field.span.hi());
548 return Some(self.snippet(span).to_owned());
551 let context = self.get_context();
553 let shape = self.shape().sub_width(1)?;
554 let attrs_str = field.attrs.rewrite(&context, shape)?;
558 .map_or(field.span.lo(), |attr| attr.span.hi());
559 let span = mk_sp(lo, field.span.lo());
561 let variant_body = match field.data {
562 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
564 &StructParts::from_variant(field),
566 Some(one_line_width),
568 ast::VariantData::Unit(..) => rewrite_ident(&context, field.ident).to_owned(),
571 let variant_body = if let Some(ref expr) = field.disr_expr {
572 let lhs = format!("{:1$} =", variant_body, pad_discrim_ident_to);
573 rewrite_assign_rhs_with(
578 RhsTactics::AllowOverflow,
584 combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
587 fn visit_impl_items(&mut self, items: &[ptr::P<ast::AssocItem>]) {
588 if self.get_context().config.reorder_impl_items() {
589 // Create visitor for each items, then reorder them.
590 let mut buffer = vec![];
592 self.visit_impl_item(item);
593 buffer.push((self.buffer.clone(), item.clone()));
597 fn is_type(ty: &Option<rustc_ast::ptr::P<ast::Ty>>) -> bool {
600 Some(lty) => match lty.kind.opaque_top_hack() {
607 fn is_opaque(ty: &Option<rustc_ast::ptr::P<ast::Ty>>) -> bool {
610 Some(lty) => match lty.kind.opaque_top_hack() {
618 a: &Option<rustc_ast::ptr::P<ast::Ty>>,
619 b: &Option<rustc_ast::ptr::P<ast::Ty>>,
621 is_type(a) && is_type(b)
625 a: &Option<rustc_ast::ptr::P<ast::Ty>>,
626 b: &Option<rustc_ast::ptr::P<ast::Ty>>,
628 is_opaque(a) && is_opaque(b)
631 // In rustc-ap-v638 the `OpaqueTy` AssocItemKind variant was removed but
632 // we still need to differentiate to maintain sorting order.
634 // type -> opaque -> const -> macro -> method
635 use crate::ast::AssocItemKind::*;
636 fn need_empty_line(a: &ast::AssocItemKind, b: &ast::AssocItemKind) -> bool {
638 (TyAlias(_, _, _, ref lty), TyAlias(_, _, _, ref rty))
639 if both_type(lty, rty) || both_opaque(lty, rty) =>
643 (Const(..), Const(..)) => false,
648 buffer.sort_by(|(_, a), (_, b)| match (&a.kind, &b.kind) {
649 (TyAlias(_, _, _, ref lty), TyAlias(_, _, _, ref rty))
650 if both_type(lty, rty) || both_opaque(lty, rty) =>
652 a.ident.as_str().cmp(&b.ident.as_str())
654 (Const(..), Const(..)) | (MacCall(..), MacCall(..)) => {
655 a.ident.as_str().cmp(&b.ident.as_str())
657 (Fn(..), Fn(..)) => a.span.lo().cmp(&b.span.lo()),
658 (TyAlias(_, _, _, ref ty), _) if is_type(ty) => Ordering::Less,
659 (_, TyAlias(_, _, _, ref ty)) if is_type(ty) => Ordering::Greater,
660 (TyAlias(..), _) => Ordering::Less,
661 (_, TyAlias(..)) => Ordering::Greater,
662 (Const(..), _) => Ordering::Less,
663 (_, Const(..)) => Ordering::Greater,
664 (MacCall(..), _) => Ordering::Less,
665 (_, MacCall(..)) => Ordering::Greater,
667 let mut prev_kind = None;
668 for (buf, item) in buffer {
669 // Make sure that there are at least a single empty line between
670 // different impl items.
673 .map_or(false, |prev_kind| need_empty_line(prev_kind, &item.kind))
677 let indent_str = self.block_indent.to_string_with_newline(self.config);
678 self.push_str(&indent_str);
679 self.push_str(buf.trim());
680 prev_kind = Some(item.kind.clone());
684 self.visit_impl_item(item);
690 pub(crate) fn format_impl(
691 context: &RewriteContext<'_>,
694 ) -> Option<String> {
695 if let ast::ItemKind::Impl {
702 let mut result = String::with_capacity(128);
703 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
704 let sep = offset.to_string_with_newline(context.config);
705 result.push_str(&ref_and_type);
707 let where_budget = if result.contains('\n') {
708 context.config.max_width()
710 context.budget(last_line_width(&result))
713 let mut option = WhereClauseOption::snuggled(&ref_and_type);
714 let snippet = context.snippet(item.span);
715 let open_pos = snippet.find_uncommented("{")? + 1;
716 if !contains_comment(&snippet[open_pos..])
718 && generics.where_clause.predicates.len() == 1
719 && !result.contains('\n')
721 option.suppress_comma();
723 option.allow_single_line();
726 let missing_span = mk_sp(self_ty.span.hi(), item.span.hi());
727 let where_span_end = context.snippet_provider.opt_span_before(missing_span, "{");
728 let where_clause_str = rewrite_where_clause(
730 &generics.where_clause,
731 context.config.brace_style(),
732 Shape::legacy(where_budget, offset.block_only()),
740 // If there is no where-clause, we may have missing comments between the trait name and
741 // the opening brace.
742 if generics.where_clause.predicates.is_empty() {
743 if let Some(hi) = where_span_end {
744 match recover_missing_comment_in_span(
745 mk_sp(self_ty.span.hi(), hi),
746 Shape::indented(offset, context.config),
748 last_line_width(&result),
750 Some(ref missing_comment) if !missing_comment.is_empty() => {
751 result.push_str(missing_comment);
758 if is_impl_single_line(context, items.as_slice(), &result, &where_clause_str, item)? {
759 result.push_str(&where_clause_str);
760 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
761 // if the where_clause contains extra comments AND
762 // there is only one where-clause predicate
763 // recover the suppressed comma in single line where_clause formatting
764 if generics.where_clause.predicates.len() == 1 {
765 result.push_str(",");
767 result.push_str(&format!("{}{{{}}}", sep, sep));
769 result.push_str(" {}");
774 result.push_str(&where_clause_str);
776 let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
777 match context.config.brace_style() {
778 _ if need_newline => result.push_str(&sep),
779 BraceStyle::AlwaysNextLine => result.push_str(&sep),
780 BraceStyle::PreferSameLine => result.push(' '),
781 BraceStyle::SameLineWhere => {
782 if !where_clause_str.is_empty() {
783 result.push_str(&sep);
791 // this is an impl body snippet(impl SampleImpl { /* here */ })
792 let lo = max(self_ty.span.hi(), generics.where_clause.span.hi());
793 let snippet = context.snippet(mk_sp(lo, item.span.hi()));
794 let open_pos = snippet.find_uncommented("{")? + 1;
796 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
797 let mut visitor = FmtVisitor::from_context(context);
798 let item_indent = offset.block_only().block_indent(context.config);
799 visitor.block_indent = item_indent;
800 visitor.last_pos = lo + BytePos(open_pos as u32);
802 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
803 visitor.visit_impl_items(items);
805 visitor.format_missing(item.span.hi() - BytePos(1));
807 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
808 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
810 result.push_str(&inner_indent_str);
811 result.push_str(visitor.buffer.trim());
812 result.push_str(&outer_indent_str);
813 } else if need_newline || !context.config.empty_item_single_line() {
814 result.push_str(&sep);
825 fn is_impl_single_line(
826 context: &RewriteContext<'_>,
827 items: &[ptr::P<ast::AssocItem>],
829 where_clause_str: &str,
832 let snippet = context.snippet(item.span);
833 let open_pos = snippet.find_uncommented("{")? + 1;
836 context.config.empty_item_single_line()
838 && !result.contains('\n')
839 && result.len() + where_clause_str.len() <= context.config.max_width()
840 && !contains_comment(&snippet[open_pos..]),
844 fn format_impl_ref_and_type(
845 context: &RewriteContext<'_>,
848 ) -> Option<String> {
849 if let ast::ItemKind::Impl {
854 of_trait: ref trait_ref,
859 let mut result = String::with_capacity(128);
861 result.push_str(&format_visibility(context, &item.vis));
862 result.push_str(format_defaultness(defaultness));
863 result.push_str(format_unsafety(unsafety));
865 let shape = if context.config.version() == Version::Two {
866 Shape::indented(offset + last_line_width(&result), context.config)
868 generics_shape_from_config(
870 Shape::indented(offset + last_line_width(&result), context.config),
874 let generics_str = rewrite_generics(context, "impl", generics, shape)?;
875 result.push_str(&generics_str);
877 let polarity_str = match polarity {
878 ast::ImplPolarity::Negative(_) => "!",
879 ast::ImplPolarity::Positive => "",
882 if let Some(ref trait_ref) = *trait_ref {
883 let result_len = last_line_width(&result);
884 result.push_str(&rewrite_trait_ref(
893 // Try to put the self type in a single line.
895 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
896 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
897 // If there is no where-clause adapt budget for type formatting to take space and curly
898 // brace into account.
899 match context.config.brace_style() {
900 BraceStyle::AlwaysNextLine => 0,
906 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
907 // 1 = space before the type.
908 let budget = context.budget(used_space + 1);
909 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
910 if !self_ty_str.contains('\n') {
911 if trait_ref.is_some() {
912 result.push_str(" for ");
916 result.push_str(&self_ty_str);
921 // Couldn't fit the self type on a single line, put it on a new line.
923 // Add indentation of one additional tab.
924 let new_line_offset = offset.block_indent(context.config);
925 result.push_str(&new_line_offset.to_string(context.config));
926 if trait_ref.is_some() {
927 result.push_str("for ");
929 let budget = context.budget(last_line_width(&result));
930 let type_offset = match context.config.indent_style() {
931 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
932 IndentStyle::Block => new_line_offset,
934 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
941 fn rewrite_trait_ref(
942 context: &RewriteContext<'_>,
943 trait_ref: &ast::TraitRef,
947 ) -> Option<String> {
948 // 1 = space between generics and trait_ref
949 let used_space = 1 + polarity_str.len() + result_len;
950 let shape = Shape::indented(offset + used_space, context.config);
951 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
952 if !trait_ref_str.contains('\n') {
953 return Some(format!(" {}{}", polarity_str, trait_ref_str));
956 // We could not make enough space for trait_ref, so put it on new line.
957 let offset = offset.block_indent(context.config);
958 let shape = Shape::indented(offset, context.config);
959 let trait_ref_str = trait_ref.rewrite(context, shape)?;
962 offset.to_string_with_newline(context.config),
968 pub(crate) struct StructParts<'a> {
971 vis: &'a ast::Visibility,
972 def: &'a ast::VariantData,
973 generics: Option<&'a ast::Generics>,
977 impl<'a> StructParts<'a> {
978 fn format_header(&self, context: &RewriteContext<'_>) -> String {
979 format_header(context, self.prefix, self.ident, self.vis)
982 fn from_variant(variant: &'a ast::Variant) -> Self {
985 ident: variant.ident,
986 vis: &DEFAULT_VISIBILITY,
993 pub(crate) fn from_item(item: &'a ast::Item) -> Self {
994 let (prefix, def, generics) = match item.kind {
995 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
996 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
1004 generics: Some(generics),
1011 context: &RewriteContext<'_>,
1012 struct_parts: &StructParts<'_>,
1014 one_line_width: Option<usize>,
1015 ) -> Option<String> {
1016 match *struct_parts.def {
1017 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
1018 ast::VariantData::Tuple(ref fields, _) => {
1019 format_tuple_struct(context, struct_parts, fields, offset)
1021 ast::VariantData::Struct(ref fields, _) => {
1022 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
1027 pub(crate) fn format_trait(
1028 context: &RewriteContext<'_>,
1031 ) -> Option<String> {
1032 if let ast::ItemKind::Trait(
1040 let mut result = String::with_capacity(128);
1041 let header = format!(
1043 format_visibility(context, &item.vis),
1044 format_unsafety(unsafety),
1045 format_auto(is_auto),
1047 result.push_str(&header);
1049 let body_lo = context.snippet_provider.span_after(item.span, "{");
1051 let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
1053 rewrite_generics(context, rewrite_ident(context, item.ident), generics, shape)?;
1054 result.push_str(&generics_str);
1056 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
1057 if !generic_bounds.is_empty() {
1058 let ident_hi = context
1060 .span_after(item.span, &item.ident.as_str());
1061 let bound_hi = generic_bounds.last().unwrap().span().hi();
1062 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
1063 if contains_comment(snippet) {
1067 result = rewrite_assign_rhs_with(
1072 RhsTactics::ForceNextLineWithoutIndent,
1076 // Rewrite where-clause.
1077 if !generics.where_clause.predicates.is_empty() {
1078 let where_on_new_line = context.config.indent_style() != IndentStyle::Block;
1080 let where_budget = context.budget(last_line_width(&result));
1081 let pos_before_where = if generic_bounds.is_empty() {
1082 generics.where_clause.span.lo()
1084 generic_bounds[generic_bounds.len() - 1].span().hi()
1086 let option = WhereClauseOption::snuggled(&generics_str);
1087 let where_clause_str = rewrite_where_clause(
1089 &generics.where_clause,
1090 context.config.brace_style(),
1091 Shape::legacy(where_budget, offset.block_only()),
1098 // If the where-clause cannot fit on the same line,
1099 // put the where-clause on a new line
1100 if !where_clause_str.contains('\n')
1101 && last_line_width(&result) + where_clause_str.len() + offset.width()
1102 > context.config.comment_width()
1104 let width = offset.block_indent + context.config.tab_spaces() - 1;
1105 let where_indent = Indent::new(0, width);
1106 result.push_str(&where_indent.to_string_with_newline(context.config));
1108 result.push_str(&where_clause_str);
1110 let item_snippet = context.snippet(item.span);
1111 if let Some(lo) = item_snippet.find('/') {
1113 let comment_hi = body_lo - BytePos(1);
1114 let comment_lo = item.span.lo() + BytePos(lo as u32);
1115 if comment_lo < comment_hi {
1116 match recover_missing_comment_in_span(
1117 mk_sp(comment_lo, comment_hi),
1118 Shape::indented(offset, context.config),
1120 last_line_width(&result),
1122 Some(ref missing_comment) if !missing_comment.is_empty() => {
1123 result.push_str(missing_comment);
1131 match context.config.brace_style() {
1132 _ if last_line_contains_single_line_comment(&result)
1133 || last_line_width(&result) + 2 > context.budget(offset.width()) =>
1135 result.push_str(&offset.to_string_with_newline(context.config));
1137 BraceStyle::AlwaysNextLine => {
1138 result.push_str(&offset.to_string_with_newline(context.config));
1140 BraceStyle::PreferSameLine => result.push(' '),
1141 BraceStyle::SameLineWhere => {
1142 if result.contains('\n')
1143 || (!generics.where_clause.predicates.is_empty() && !trait_items.is_empty())
1145 result.push_str(&offset.to_string_with_newline(context.config));
1153 let snippet = context.snippet(item.span);
1154 let open_pos = snippet.find_uncommented("{")? + 1;
1155 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
1157 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1158 let mut visitor = FmtVisitor::from_context(context);
1159 visitor.block_indent = offset.block_only().block_indent(context.config);
1160 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1162 for item in trait_items {
1163 visitor.visit_trait_item(item);
1166 visitor.format_missing(item.span.hi() - BytePos(1));
1168 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
1170 result.push_str(&inner_indent_str);
1171 result.push_str(visitor.buffer.trim());
1172 result.push_str(&outer_indent_str);
1173 } else if result.contains('\n') {
1174 result.push_str(&outer_indent_str);
1184 struct OpaqueTypeBounds<'a> {
1185 generic_bounds: &'a ast::GenericBounds,
1188 impl<'a> Rewrite for OpaqueTypeBounds<'a> {
1189 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1191 .rewrite(context, shape)
1192 .map(|s| format!("impl {}", s))
1196 pub(crate) struct TraitAliasBounds<'a> {
1197 generic_bounds: &'a ast::GenericBounds,
1198 generics: &'a ast::Generics,
1201 impl<'a> Rewrite for TraitAliasBounds<'a> {
1202 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1203 let generic_bounds_str = self.generic_bounds.rewrite(context, shape)?;
1205 let mut option = WhereClauseOption::new(true, WhereClauseSpace::None);
1206 option.allow_single_line();
1208 let where_str = rewrite_where_clause(
1210 &self.generics.where_clause,
1211 context.config.brace_style(),
1216 self.generics.where_clause.span.lo(),
1220 let fits_single_line = !generic_bounds_str.contains('\n')
1221 && !where_str.contains('\n')
1222 && generic_bounds_str.len() + where_str.len() + 1 <= shape.width;
1223 let space = if generic_bounds_str.is_empty() || where_str.is_empty() {
1225 } else if fits_single_line {
1228 shape.indent.to_string_with_newline(&context.config)
1231 Some(format!("{}{}{}", generic_bounds_str, space, where_str))
1235 pub(crate) fn format_trait_alias(
1236 context: &RewriteContext<'_>,
1238 vis: &ast::Visibility,
1239 generics: &ast::Generics,
1240 generic_bounds: &ast::GenericBounds,
1242 ) -> Option<String> {
1243 let alias = rewrite_ident(context, ident);
1244 // 6 = "trait ", 2 = " ="
1245 let g_shape = shape.offset_left(6)?.sub_width(2)?;
1246 let generics_str = rewrite_generics(context, &alias, generics, g_shape)?;
1247 let vis_str = format_visibility(context, vis);
1248 let lhs = format!("{}trait {} =", vis_str, generics_str);
1250 let trait_alias_bounds = TraitAliasBounds {
1254 rewrite_assign_rhs(context, lhs, &trait_alias_bounds, shape.sub_width(1)?).map(|s| s + ";")
1257 fn format_unit_struct(
1258 context: &RewriteContext<'_>,
1259 p: &StructParts<'_>,
1261 ) -> Option<String> {
1262 let header_str = format_header(context, p.prefix, p.ident, p.vis);
1263 let generics_str = if let Some(generics) = p.generics {
1264 let hi = context.snippet_provider.span_before(p.span, ";");
1268 context.config.brace_style(),
1271 // make a span that starts right after `struct Foo`
1272 mk_sp(p.ident.span.hi(), hi),
1273 last_line_width(&header_str),
1278 Some(format!("{}{};", header_str, generics_str))
1281 pub(crate) fn format_struct_struct(
1282 context: &RewriteContext<'_>,
1283 struct_parts: &StructParts<'_>,
1284 fields: &[ast::StructField],
1286 one_line_width: Option<usize>,
1287 ) -> Option<String> {
1288 let mut result = String::with_capacity(1024);
1289 let span = struct_parts.span;
1291 let header_str = struct_parts.format_header(context);
1292 result.push_str(&header_str);
1294 let header_hi = struct_parts.ident.span.hi();
1295 let body_lo = context.snippet_provider.span_after(span, "{");
1297 let generics_str = match struct_parts.generics {
1298 Some(g) => format_generics(
1301 context.config.brace_style(),
1302 if fields.is_empty() {
1303 BracePos::ForceSameLine
1308 // make a span that starts right after `struct Foo`
1309 mk_sp(header_hi, body_lo),
1310 last_line_width(&result),
1313 // 3 = ` {}`, 2 = ` {`.
1314 let overhead = if fields.is_empty() { 3 } else { 2 };
1315 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1316 || context.config.max_width() < overhead + result.len()
1318 format!("\n{}{{", offset.block_only().to_string(context.config))
1325 let overhead = if fields.is_empty() { 1 } else { 0 };
1326 let total_width = result.len() + generics_str.len() + overhead;
1327 if !generics_str.is_empty()
1328 && !generics_str.contains('\n')
1329 && total_width > context.config.max_width()
1332 result.push_str(&offset.to_string(context.config));
1333 result.push_str(generics_str.trim_start());
1335 result.push_str(&generics_str);
1338 if fields.is_empty() {
1339 let inner_span = mk_sp(body_lo, span.hi() - BytePos(1));
1340 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "", "}");
1341 return Some(result);
1345 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1346 let one_line_budget =
1347 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1349 let items_str = rewrite_with_alignment(
1352 Shape::indented(offset.block_indent(context.config), context.config).sub_width(1)?,
1353 mk_sp(body_lo, span.hi()),
1357 if !items_str.contains('\n')
1358 && !result.contains('\n')
1359 && items_str.len() <= one_line_budget
1360 && !last_line_contains_single_line_comment(&items_str)
1362 Some(format!("{} {} }}", result, items_str))
1368 .block_indent(context.config)
1369 .to_string(context.config),
1371 offset.to_string(context.config)
1376 fn get_bytepos_after_visibility(vis: &ast::Visibility, default_span: Span) -> BytePos {
1378 ast::VisibilityKind::Crate(..) | ast::VisibilityKind::Restricted { .. } => vis.span.hi(),
1379 _ => default_span.lo(),
1383 // Format tuple or struct without any fields. We need to make sure that the comments
1384 // inside the delimiters are preserved.
1385 fn format_empty_struct_or_tuple(
1386 context: &RewriteContext<'_>,
1389 result: &mut String,
1393 // 3 = " {}" or "();"
1394 let used_width = last_line_used_width(&result, offset.width()) + 3;
1395 if used_width > context.config.max_width() {
1396 result.push_str(&offset.to_string_with_newline(context.config))
1398 result.push_str(opener);
1399 match rewrite_missing_comment(span, Shape::indented(offset, context.config), context) {
1400 Some(ref s) if s.is_empty() => (),
1402 if !is_single_line(s) || first_line_contains_single_line_comment(s) {
1403 let nested_indent_str = offset
1404 .block_indent(context.config)
1405 .to_string_with_newline(context.config);
1406 result.push_str(&nested_indent_str);
1409 if last_line_contains_single_line_comment(s) {
1410 result.push_str(&offset.to_string_with_newline(context.config));
1413 None => result.push_str(context.snippet(span)),
1415 result.push_str(closer);
1418 fn format_tuple_struct(
1419 context: &RewriteContext<'_>,
1420 struct_parts: &StructParts<'_>,
1421 fields: &[ast::StructField],
1423 ) -> Option<String> {
1424 let mut result = String::with_capacity(1024);
1425 let span = struct_parts.span;
1427 let header_str = struct_parts.format_header(context);
1428 result.push_str(&header_str);
1430 let body_lo = if fields.is_empty() {
1431 let lo = get_bytepos_after_visibility(struct_parts.vis, span);
1434 .span_after(mk_sp(lo, span.hi()), "(")
1438 let body_hi = if fields.is_empty() {
1441 .span_after(mk_sp(body_lo, span.hi()), ")")
1443 // This is a dirty hack to work around a missing `)` from the span of the last field.
1444 let last_arg_span = fields[fields.len() - 1].span;
1447 .opt_span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1448 .unwrap_or_else(|| last_arg_span.hi())
1451 let where_clause_str = match struct_parts.generics {
1453 let budget = context.budget(last_line_width(&header_str));
1454 let shape = Shape::legacy(budget, offset);
1455 let generics_str = rewrite_generics(context, "", generics, shape)?;
1456 result.push_str(&generics_str);
1458 let where_budget = context.budget(last_line_width(&result));
1459 let option = WhereClauseOption::new(true, WhereClauseSpace::Newline);
1460 rewrite_where_clause(
1462 &generics.where_clause,
1463 context.config.brace_style(),
1464 Shape::legacy(where_budget, offset.block_only()),
1472 None => "".to_owned(),
1475 if fields.is_empty() {
1476 let body_hi = context
1478 .span_before(mk_sp(body_lo, span.hi()), ")");
1479 let inner_span = mk_sp(body_lo, body_hi);
1480 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "(", ")");
1482 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1483 result = overflow::rewrite_with_parens(
1489 context.config.width_heuristics().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 fn rewrite_type_prefix(
1513 context: &RewriteContext<'_>,
1517 generics: &ast::Generics,
1518 ) -> Option<String> {
1519 let mut result = String::with_capacity(128);
1520 result.push_str(prefix);
1521 let ident_str = rewrite_ident(context, ident);
1524 if generics.params.is_empty() {
1525 result.push_str(ident_str)
1527 let g_shape = Shape::indented(indent, context.config)
1528 .offset_left(result.len())?
1530 let generics_str = rewrite_generics(context, ident_str, generics, g_shape)?;
1531 result.push_str(&generics_str);
1534 let where_budget = context.budget(last_line_width(&result));
1535 let option = WhereClauseOption::snuggled(&result);
1536 let where_clause_str = rewrite_where_clause(
1538 &generics.where_clause,
1539 context.config.brace_style(),
1540 Shape::legacy(where_budget, indent),
1547 result.push_str(&where_clause_str);
1552 fn rewrite_type_item<R: Rewrite>(
1553 context: &RewriteContext<'_>,
1559 generics: &ast::Generics,
1560 vis: &ast::Visibility,
1561 ) -> Option<String> {
1562 let mut result = String::with_capacity(128);
1563 result.push_str(&rewrite_type_prefix(
1566 &format!("{}{} ", format_visibility(context, vis), prefix),
1571 if generics.where_clause.predicates.is_empty() {
1572 result.push_str(suffix);
1574 result.push_str(&indent.to_string_with_newline(context.config));
1575 result.push_str(suffix.trim_start());
1579 let rhs_shape = Shape::indented(indent, context.config).sub_width(1)?;
1580 rewrite_assign_rhs(context, result, rhs, rhs_shape).map(|s| s + ";")
1583 pub(crate) fn rewrite_type_alias(
1584 context: &RewriteContext<'_>,
1588 generics: &ast::Generics,
1589 vis: &ast::Visibility,
1590 ) -> Option<String> {
1591 rewrite_type_item(context, indent, "type", " =", ident, ty, generics, vis)
1594 pub(crate) fn rewrite_opaque_type(
1595 context: &RewriteContext<'_>,
1598 generic_bounds: &ast::GenericBounds,
1599 generics: &ast::Generics,
1600 vis: &ast::Visibility,
1601 ) -> Option<String> {
1602 let opaque_type_bounds = OpaqueTypeBounds { generic_bounds };
1609 &opaque_type_bounds,
1615 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1617 if config.space_before_colon() { " " } else { "" },
1618 if config.space_after_colon() { " " } else { "" },
1622 pub(crate) fn rewrite_struct_field_prefix(
1623 context: &RewriteContext<'_>,
1624 field: &ast::StructField,
1625 ) -> Option<String> {
1626 let vis = format_visibility(context, &field.vis);
1627 let type_annotation_spacing = type_annotation_spacing(context.config);
1628 Some(match field.ident {
1629 Some(name) => format!(
1632 rewrite_ident(context, name),
1633 type_annotation_spacing.0
1635 None => vis.to_string(),
1639 impl Rewrite for ast::StructField {
1640 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1641 rewrite_struct_field(context, self, shape, 0)
1645 pub(crate) fn rewrite_struct_field(
1646 context: &RewriteContext<'_>,
1647 field: &ast::StructField,
1649 lhs_max_width: usize,
1650 ) -> Option<String> {
1651 if contains_skip(&field.attrs) {
1652 return Some(context.snippet(field.span()).to_owned());
1655 let type_annotation_spacing = type_annotation_spacing(context.config);
1656 let prefix = rewrite_struct_field_prefix(context, field)?;
1658 let attrs_str = field.attrs.rewrite(context, shape)?;
1659 let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
1660 let missing_span = if field.attrs.is_empty() {
1661 mk_sp(field.span.lo(), field.span.lo())
1663 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1665 let mut spacing = String::from(if field.ident.is_some() {
1666 type_annotation_spacing.1
1670 // Try to put everything on a single line.
1671 let attr_prefix = combine_strs_with_missing_comments(
1679 let overhead = trimmed_last_line_width(&attr_prefix);
1680 let lhs_offset = lhs_max_width.saturating_sub(overhead);
1681 for _ in 0..lhs_offset {
1684 // In this extreme case we will be missing a space between an attribute and a field.
1685 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1689 .offset_left(overhead + spacing.len())
1690 .and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
1691 if let Some(ref ty) = orig_ty {
1692 if !ty.contains('\n') {
1693 return Some(attr_prefix + &spacing + ty);
1697 let is_prefix_empty = prefix.is_empty();
1698 // We must use multiline. We are going to put attributes and a field on different lines.
1699 let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, shape)?;
1700 // Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
1701 let field_str = if is_prefix_empty {
1702 field_str.trim_start()
1706 combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
1709 pub(crate) struct StaticParts<'a> {
1711 vis: &'a ast::Visibility,
1714 mutability: ast::Mutability,
1715 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1716 defaultness: Option<ast::Defaultness>,
1720 impl<'a> StaticParts<'a> {
1721 pub(crate) fn from_item(item: &'a ast::Item) -> Self {
1722 let (defaultness, prefix, ty, mutability, expr) = match item.kind {
1723 ast::ItemKind::Static(ref ty, mutability, ref expr) => {
1724 (None, "static", ty, mutability, expr)
1726 ast::ItemKind::Const(defaultness, ref ty, ref expr) => {
1727 (Some(defaultness), "const", ty, ast::Mutability::Not, expr)
1729 _ => unreachable!(),
1737 expr_opt: expr.as_ref(),
1743 pub(crate) fn from_trait_item(ti: &'a ast::AssocItem) -> Self {
1744 let (defaultness, ty, expr_opt) = match ti.kind {
1745 ast::AssocItemKind::Const(defaultness, ref ty, ref expr_opt) => {
1746 (defaultness, ty, expr_opt)
1748 _ => unreachable!(),
1752 vis: &DEFAULT_VISIBILITY,
1755 mutability: ast::Mutability::Not,
1756 expr_opt: expr_opt.as_ref(),
1757 defaultness: Some(defaultness),
1762 pub(crate) fn from_impl_item(ii: &'a ast::AssocItem) -> Self {
1763 let (defaultness, ty, expr) = match ii.kind {
1764 ast::AssocItemKind::Const(defaultness, ref ty, ref expr) => (defaultness, ty, expr),
1765 _ => unreachable!(),
1772 mutability: ast::Mutability::Not,
1773 expr_opt: expr.as_ref(),
1774 defaultness: Some(defaultness),
1781 context: &RewriteContext<'_>,
1782 static_parts: &StaticParts<'_>,
1784 ) -> Option<String> {
1785 let colon = colon_spaces(context.config);
1786 let mut prefix = format!(
1788 format_visibility(context, static_parts.vis),
1789 static_parts.defaultness.map_or("", format_defaultness),
1790 static_parts.prefix,
1791 format_mutability(static_parts.mutability),
1792 rewrite_ident(context, static_parts.ident),
1797 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1798 let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
1799 Some(ty_str) => ty_str,
1801 if prefix.ends_with(' ') {
1804 let nested_indent = offset.block_indent(context.config);
1805 let nested_shape = Shape::indented(nested_indent, context.config);
1806 let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
1809 nested_indent.to_string_with_newline(context.config),
1815 if let Some(expr) = static_parts.expr_opt {
1816 let lhs = format!("{}{} =", prefix, ty_str);
1818 let remaining_width = context.budget(offset.block_indent + 1);
1823 Shape::legacy(remaining_width, offset.block_only()),
1825 .and_then(|res| recover_comment_removed(res, static_parts.span, context))
1826 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1828 Some(format!("{}{};", prefix, ty_str))
1832 pub(crate) fn rewrite_associated_type(
1834 ty_opt: Option<&ptr::P<ast::Ty>>,
1835 generics: &ast::Generics,
1836 generic_bounds_opt: Option<&ast::GenericBounds>,
1837 context: &RewriteContext<'_>,
1839 ) -> Option<String> {
1840 let ident_str = rewrite_ident(context, ident);
1842 let generics_shape = Shape::indented(indent, context.config).offset_left(5)?;
1843 let generics_str = rewrite_generics(context, ident_str, generics, generics_shape)?;
1844 let prefix = format!("type {}", generics_str);
1846 let type_bounds_str = if let Some(bounds) = generic_bounds_opt {
1847 if bounds.is_empty() {
1851 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1852 bounds.rewrite(context, shape).map(|s| format!(": {}", s))?
1858 if let Some(ty) = ty_opt {
1860 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1861 let lhs = format!("{}{} =", prefix, type_bounds_str);
1862 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1864 Some(format!("{}{};", prefix, type_bounds_str))
1868 struct OpaqueType<'a> {
1869 bounds: &'a ast::GenericBounds,
1872 impl<'a> Rewrite for OpaqueType<'a> {
1873 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1874 let shape = shape.offset_left(5)?; // `impl `
1876 .rewrite(context, shape)
1877 .map(|s| format!("impl {}", s))
1881 pub(crate) fn rewrite_opaque_impl_type(
1882 context: &RewriteContext<'_>,
1884 generics: &ast::Generics,
1885 generic_bounds: &ast::GenericBounds,
1887 ) -> Option<String> {
1888 let ident_str = rewrite_ident(context, ident);
1890 let generics_shape = Shape::indented(indent, context.config).offset_left(5)?;
1891 let generics_str = rewrite_generics(context, ident_str, generics, generics_shape)?;
1892 let prefix = format!("type {} =", generics_str);
1893 let rhs = OpaqueType {
1894 bounds: generic_bounds,
1901 Shape::indented(indent, context.config).sub_width(1)?,
1906 pub(crate) fn rewrite_associated_impl_type(
1908 defaultness: ast::Defaultness,
1909 ty_opt: Option<&ptr::P<ast::Ty>>,
1910 generics: &ast::Generics,
1911 context: &RewriteContext<'_>,
1913 ) -> Option<String> {
1914 let result = rewrite_associated_type(ident, ty_opt, generics, None, context, indent)?;
1917 ast::Defaultness::Default(..) => Some(format!("default {}", result)),
1922 impl Rewrite for ast::FnRetTy {
1923 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1925 ast::FnRetTy::Default(_) => Some(String::new()),
1926 ast::FnRetTy::Ty(ref ty) => {
1927 if context.config.version() == Version::One
1928 || context.config.indent_style() == IndentStyle::Visual
1930 let inner_width = shape.width.checked_sub(3)?;
1932 .rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1933 .map(|r| format!("-> {}", r));
1936 ty.rewrite(context, shape.offset_left(3)?)
1937 .map(|s| format!("-> {}", s))
1943 fn is_empty_infer(ty: &ast::Ty, pat_span: Span) -> bool {
1945 ast::TyKind::Infer => ty.span.hi() == pat_span.hi(),
1950 /// Recover any missing comments between the param and the type.
1954 /// A 2-len tuple with the comment before the colon in first position, and the comment after the
1955 /// colon in second position.
1956 fn get_missing_param_comments(
1957 context: &RewriteContext<'_>,
1961 ) -> (String, String) {
1962 let missing_comment_span = mk_sp(pat_span.hi(), ty_span.lo());
1964 let span_before_colon = {
1965 let missing_comment_span_hi = context
1967 .span_before(missing_comment_span, ":");
1968 mk_sp(pat_span.hi(), missing_comment_span_hi)
1970 let span_after_colon = {
1971 let missing_comment_span_lo = context
1973 .span_after(missing_comment_span, ":");
1974 mk_sp(missing_comment_span_lo, ty_span.lo())
1977 let comment_before_colon = rewrite_missing_comment(span_before_colon, shape, context)
1978 .filter(|comment| !comment.is_empty())
1979 .map_or(String::new(), |comment| format!(" {}", comment));
1980 let comment_after_colon = rewrite_missing_comment(span_after_colon, shape, context)
1981 .filter(|comment| !comment.is_empty())
1982 .map_or(String::new(), |comment| format!("{} ", comment));
1983 (comment_before_colon, comment_after_colon)
1986 impl Rewrite for ast::Param {
1987 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1988 let param_attrs_result = self
1990 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1991 let (span, has_multiple_attr_lines) = if !self.attrs.is_empty() {
1992 let num_attrs = self.attrs.len();
1994 mk_sp(self.attrs[num_attrs - 1].span.hi(), self.pat.span.lo()),
1995 param_attrs_result.contains("\n"),
1998 (mk_sp(self.span.lo(), self.span.lo()), false)
2001 if let Some(ref explicit_self) = self.to_self() {
2002 rewrite_explicit_self(
2005 ¶m_attrs_result,
2008 has_multiple_attr_lines,
2010 } else if is_named_param(self) {
2011 let mut result = combine_strs_with_missing_comments(
2013 ¶m_attrs_result,
2016 .rewrite(context, Shape::legacy(shape.width, shape.indent))?,
2019 !has_multiple_attr_lines,
2022 if !is_empty_infer(&*self.ty, self.pat.span) {
2023 let (before_comment, after_comment) =
2024 get_missing_param_comments(context, self.pat.span, self.ty.span, shape);
2025 result.push_str(&before_comment);
2026 result.push_str(colon_spaces(context.config));
2027 result.push_str(&after_comment);
2028 let overhead = last_line_width(&result);
2029 let max_width = shape.width.checked_sub(overhead)?;
2032 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
2033 result.push_str(&ty_str);
2038 self.ty.rewrite(context, shape)
2043 fn rewrite_explicit_self(
2044 context: &RewriteContext<'_>,
2045 explicit_self: &ast::ExplicitSelf,
2049 has_multiple_attr_lines: bool,
2050 ) -> Option<String> {
2051 match explicit_self.node {
2052 ast::SelfKind::Region(lt, m) => {
2053 let mut_str = format_mutability(m);
2056 let lifetime_str = l.rewrite(
2058 Shape::legacy(context.config.max_width(), Indent::empty()),
2060 Some(combine_strs_with_missing_comments(
2063 &format!("&{} {}self", lifetime_str, mut_str),
2066 !has_multiple_attr_lines,
2069 None => Some(combine_strs_with_missing_comments(
2072 &format!("&{}self", mut_str),
2075 !has_multiple_attr_lines,
2079 ast::SelfKind::Explicit(ref ty, mutability) => {
2080 let type_str = ty.rewrite(
2082 Shape::legacy(context.config.max_width(), Indent::empty()),
2085 Some(combine_strs_with_missing_comments(
2088 &format!("{}self: {}", format_mutability(mutability), type_str),
2091 !has_multiple_attr_lines,
2094 ast::SelfKind::Value(mutability) => Some(combine_strs_with_missing_comments(
2097 &format!("{}self", format_mutability(mutability)),
2100 !has_multiple_attr_lines,
2105 pub(crate) fn span_lo_for_param(param: &ast::Param) -> BytePos {
2106 if param.attrs.is_empty() {
2107 if is_named_param(param) {
2113 param.attrs[0].span.lo()
2117 pub(crate) fn span_hi_for_param(context: &RewriteContext<'_>, param: &ast::Param) -> BytePos {
2118 match param.ty.kind {
2119 ast::TyKind::Infer if context.snippet(param.ty.span) == "_" => param.ty.span.hi(),
2120 ast::TyKind::Infer if is_named_param(param) => param.pat.span.hi(),
2121 _ => param.ty.span.hi(),
2125 pub(crate) fn is_named_param(param: &ast::Param) -> bool {
2126 if let ast::PatKind::Ident(_, ident, _) = param.pat.kind {
2127 ident.name != symbol::kw::Invalid
2133 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
2134 pub(crate) enum FnBraceStyle {
2140 // Return type is (result, force_new_line_for_brace)
2142 context: &RewriteContext<'_>,
2147 fn_brace_style: FnBraceStyle,
2148 ) -> Option<(String, bool)> {
2149 let mut force_new_line_for_brace = false;
2151 let where_clause = &fn_sig.generics.where_clause;
2153 let mut result = String::with_capacity(1024);
2154 result.push_str(&fn_sig.to_str(context));
2157 result.push_str("fn ");
2160 let overhead = if let FnBraceStyle::SameLine = fn_brace_style {
2167 let used_width = last_line_used_width(&result, indent.width());
2168 let one_line_budget = context.budget(used_width + overhead);
2170 width: one_line_budget,
2174 let fd = fn_sig.decl;
2175 let generics_str = rewrite_generics(
2177 rewrite_ident(context, ident),
2181 result.push_str(&generics_str);
2183 let snuggle_angle_bracket = generics_str
2186 .map_or(false, |l| l.trim_start().len() == 1);
2188 // Note that the width and indent don't really matter, we'll re-layout the
2189 // return type later anyway.
2192 .rewrite(context, Shape::indented(indent, context.config))?;
2194 let multi_line_ret_str = ret_str.contains('\n');
2195 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
2198 let (one_line_budget, multi_line_budget, mut param_indent) = compute_budgets_for_params(
2208 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, param_indent: {:?}",
2209 one_line_budget, multi_line_budget, param_indent
2213 // Check if vertical layout was forced.
2214 if one_line_budget == 0
2215 && !snuggle_angle_bracket
2216 && context.config.indent_style() == IndentStyle::Visual
2218 result.push_str(¶m_indent.to_string_with_newline(context.config));
2221 // Skip `pub(crate)`.
2222 let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
2223 // A conservative estimation, to goal is to be over all parens in generics
2224 let params_start = fn_sig
2229 .map_or(lo_after_visibility, |param| param.span().hi());
2230 let params_end = if fd.inputs.is_empty() {
2233 .span_after(mk_sp(params_start, span.hi()), ")")
2235 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
2236 context.snippet_provider.span_after(last_span, ")")
2238 let params_span = mk_sp(
2241 .span_after(mk_sp(params_start, span.hi()), "("),
2244 let param_str = rewrite_params(
2255 let put_params_in_block = match context.config.indent_style() {
2256 IndentStyle::Block => param_str.contains('\n') || param_str.len() > one_line_budget,
2258 } && !fd.inputs.is_empty();
2260 let mut params_last_line_contains_comment = false;
2261 let mut no_params_and_over_max_width = false;
2263 if put_params_in_block {
2264 param_indent = indent.block_indent(context.config);
2265 result.push_str(¶m_indent.to_string_with_newline(context.config));
2266 result.push_str(¶m_str);
2267 result.push_str(&indent.to_string_with_newline(context.config));
2270 result.push_str(¶m_str);
2271 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
2272 // Put the closing brace on the next line if it overflows the max width.
2274 let closing_paren_overflow_max_width =
2275 fd.inputs.is_empty() && used_width + 1 > context.config.max_width();
2276 // If the last line of params contains comment, we cannot put the closing paren
2277 // on the same line.
2278 params_last_line_contains_comment = param_str
2281 .map_or(false, |last_line| last_line.contains("//"));
2283 if context.config.version() == Version::Two {
2284 if closing_paren_overflow_max_width {
2286 result.push_str(&indent.to_string_with_newline(context.config));
2287 no_params_and_over_max_width = true;
2288 } else if params_last_line_contains_comment {
2289 result.push_str(&indent.to_string_with_newline(context.config));
2291 no_params_and_over_max_width = true;
2296 if closing_paren_overflow_max_width || params_last_line_contains_comment {
2297 result.push_str(&indent.to_string_with_newline(context.config));
2304 if let ast::FnRetTy::Ty(..) = fd.output {
2305 let ret_should_indent = match context.config.indent_style() {
2306 // If our params are block layout then we surely must have space.
2307 IndentStyle::Block if put_params_in_block || fd.inputs.is_empty() => false,
2308 _ if params_last_line_contains_comment => false,
2309 _ if result.contains('\n') || multi_line_ret_str => true,
2311 // If the return type would push over the max width, then put the return type on
2312 // a new line. With the +1 for the signature length an additional space between
2313 // the closing parenthesis of the param and the arrow '->' is considered.
2314 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
2316 // If there is no where-clause, take into account the space after the return type
2318 if where_clause.predicates.is_empty() {
2322 sig_length > context.config.max_width()
2325 let ret_shape = if ret_should_indent {
2326 if context.config.version() == Version::One
2327 || context.config.indent_style() == IndentStyle::Visual
2329 let indent = if param_str.is_empty() {
2330 // Aligning with non-existent params looks silly.
2331 force_new_line_for_brace = true;
2334 // FIXME: we might want to check that using the param indent
2335 // doesn't blow our budget, and if it does, then fallback to
2336 // the where-clause indent.
2340 result.push_str(&indent.to_string_with_newline(context.config));
2341 Shape::indented(indent, context.config)
2343 let mut ret_shape = Shape::indented(indent, context.config);
2344 if param_str.is_empty() {
2345 // Aligning with non-existent params looks silly.
2346 force_new_line_for_brace = true;
2347 ret_shape = if context.use_block_indent() {
2348 ret_shape.offset_left(4).unwrap_or(ret_shape)
2350 ret_shape.indent = ret_shape.indent + 4;
2355 result.push_str(&ret_shape.indent.to_string_with_newline(context.config));
2359 if context.config.version() == Version::Two {
2360 if !param_str.is_empty() || !no_params_and_over_max_width {
2367 let ret_shape = Shape::indented(indent, context.config);
2369 .offset_left(last_line_width(&result))
2370 .unwrap_or(ret_shape)
2373 if multi_line_ret_str || ret_should_indent {
2374 // Now that we know the proper indent and width, we need to
2375 // re-layout the return type.
2376 let ret_str = fd.output.rewrite(context, ret_shape)?;
2377 result.push_str(&ret_str);
2379 result.push_str(&ret_str);
2382 // Comment between return type and the end of the decl.
2383 let snippet_lo = fd.output.span().hi();
2384 if where_clause.predicates.is_empty() {
2385 let snippet_hi = span.hi();
2386 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2387 // Try to preserve the layout of the original snippet.
2388 let original_starts_with_newline = snippet
2390 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2391 let original_ends_with_newline = snippet
2392 .rfind(|c| c != ' ')
2393 .map_or(false, |i| snippet[i..].ends_with('\n'));
2394 let snippet = snippet.trim();
2395 if !snippet.is_empty() {
2396 result.push(if original_starts_with_newline {
2401 result.push_str(snippet);
2402 if original_ends_with_newline {
2403 force_new_line_for_brace = true;
2409 let pos_before_where = match fd.output {
2410 ast::FnRetTy::Default(..) => params_span.hi(),
2411 ast::FnRetTy::Ty(ref ty) => ty.span.hi(),
2414 let is_params_multi_lined = param_str.contains('\n');
2416 let space = if put_params_in_block && ret_str.is_empty() {
2417 WhereClauseSpace::Space
2419 WhereClauseSpace::Newline
2421 let mut option = WhereClauseOption::new(fn_brace_style == FnBraceStyle::None, space);
2422 if is_params_multi_lined {
2423 option.veto_single_line();
2425 let where_clause_str = rewrite_where_clause(
2428 context.config.brace_style(),
2429 Shape::indented(indent, context.config),
2436 // If there are neither where-clause nor return type, we may be missing comments between
2438 if where_clause_str.is_empty() {
2439 if let ast::FnRetTy::Default(ret_span) = fd.output {
2440 match recover_missing_comment_in_span(
2441 mk_sp(params_span.hi(), ret_span.hi()),
2444 last_line_width(&result),
2446 Some(ref missing_comment) if !missing_comment.is_empty() => {
2447 result.push_str(missing_comment);
2448 force_new_line_for_brace = true;
2455 result.push_str(&where_clause_str);
2457 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2458 force_new_line_for_brace |= is_params_multi_lined && context.config.where_single_line();
2459 Some((result, force_new_line_for_brace))
2462 /// Kind of spaces to put before `where`.
2463 #[derive(Copy, Clone)]
2464 enum WhereClauseSpace {
2473 #[derive(Copy, Clone)]
2474 struct WhereClauseOption {
2475 suppress_comma: bool, // Force no trailing comma
2476 snuggle: WhereClauseSpace,
2477 allow_single_line: bool, // Try single line where-clause instead of vertical layout
2478 veto_single_line: bool, // Disallow a single-line where-clause.
2481 impl WhereClauseOption {
2482 fn new(suppress_comma: bool, snuggle: WhereClauseSpace) -> WhereClauseOption {
2486 allow_single_line: false,
2487 veto_single_line: false,
2491 fn snuggled(current: &str) -> WhereClauseOption {
2493 suppress_comma: false,
2494 snuggle: if last_line_width(current) == 1 {
2495 WhereClauseSpace::Space
2497 WhereClauseSpace::Newline
2499 allow_single_line: false,
2500 veto_single_line: false,
2504 fn suppress_comma(&mut self) {
2505 self.suppress_comma = true
2508 fn allow_single_line(&mut self) {
2509 self.allow_single_line = true
2512 fn snuggle(&mut self) {
2513 self.snuggle = WhereClauseSpace::Space
2516 fn veto_single_line(&mut self) {
2517 self.veto_single_line = true;
2522 context: &RewriteContext<'_>,
2523 params: &[ast::Param],
2524 one_line_budget: usize,
2525 multi_line_budget: usize,
2527 param_indent: Indent,
2530 ) -> Option<String> {
2531 if params.is_empty() {
2532 let comment = context
2536 span.hi() - BytePos(1),
2539 return Some(comment.to_owned());
2541 let param_items: Vec<_> = itemize_list(
2542 context.snippet_provider,
2546 |param| span_lo_for_param(param),
2547 |param| param.ty.span.hi(),
2550 .rewrite(context, Shape::legacy(multi_line_budget, param_indent))
2551 .or_else(|| Some(context.snippet(param.span()).to_owned()))
2559 let tactic = definitive_tactic(
2564 .to_list_tactic(param_items.len()),
2568 let budget = match tactic {
2569 DefinitiveListTactic::Horizontal => one_line_budget,
2570 _ => multi_line_budget,
2572 let indent = match context.config.indent_style() {
2573 IndentStyle::Block => indent.block_indent(context.config),
2574 IndentStyle::Visual => param_indent,
2576 let trailing_separator = if variadic {
2577 SeparatorTactic::Never
2579 match context.config.indent_style() {
2580 IndentStyle::Block => context.config.trailing_comma(),
2581 IndentStyle::Visual => SeparatorTactic::Never,
2584 let fmt = ListFormatting::new(Shape::legacy(budget, indent), context.config)
2586 .trailing_separator(trailing_separator)
2587 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2588 .preserve_newline(true);
2589 write_list(¶m_items, &fmt)
2592 fn compute_budgets_for_params(
2593 context: &RewriteContext<'_>,
2597 fn_brace_style: FnBraceStyle,
2598 force_vertical_layout: bool,
2599 ) -> Option<(usize, usize, Indent)> {
2601 "compute_budgets_for_params {} {:?}, {}, {:?}",
2607 // Try keeping everything on the same line.
2608 if !result.contains('\n') && !force_vertical_layout {
2609 // 2 = `()`, 3 = `() `, space is before ret_string.
2610 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2611 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2612 match fn_brace_style {
2613 FnBraceStyle::None => used_space += 1, // 1 = `;`
2614 FnBraceStyle::SameLine => used_space += 2, // 2 = `{}`
2615 FnBraceStyle::NextLine => (),
2617 let one_line_budget = context.budget(used_space);
2619 if one_line_budget > 0 {
2621 let (indent, multi_line_budget) = match context.config.indent_style() {
2622 IndentStyle::Block => {
2623 let indent = indent.block_indent(context.config);
2624 (indent, context.budget(indent.width() + 1))
2626 IndentStyle::Visual => {
2627 let indent = indent + result.len() + 1;
2628 let multi_line_overhead = match fn_brace_style {
2629 FnBraceStyle::SameLine => 4,
2632 (indent, context.budget(multi_line_overhead))
2636 return Some((one_line_budget, multi_line_budget, indent));
2640 // Didn't work. we must force vertical layout and put params on a newline.
2641 let new_indent = indent.block_indent(context.config);
2642 let used_space = match context.config.indent_style() {
2644 IndentStyle::Block => new_indent.width() + 1,
2645 // Account for `)` and possibly ` {`.
2646 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2648 Some((0, context.budget(used_space), new_indent))
2651 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> FnBraceStyle {
2652 let predicate_count = where_clause.predicates.len();
2654 if config.where_single_line() && predicate_count == 1 {
2655 return FnBraceStyle::SameLine;
2657 let brace_style = config.brace_style();
2659 let use_next_line = brace_style == BraceStyle::AlwaysNextLine
2660 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0);
2662 FnBraceStyle::NextLine
2664 FnBraceStyle::SameLine
2668 fn rewrite_generics(
2669 context: &RewriteContext<'_>,
2671 generics: &ast::Generics,
2673 ) -> Option<String> {
2674 // FIXME: convert bounds to where-clauses where they get too big or if
2675 // there is a where-clause at all.
2677 if generics.params.is_empty() {
2678 return Some(ident.to_owned());
2681 let params = generics.params.iter();
2682 overflow::rewrite_with_angle_brackets(context, ident, params, shape, generics.span)
2685 fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2686 match config.indent_style() {
2687 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2688 IndentStyle::Block => {
2692 .block_indent(config.tab_spaces())
2693 .with_max_width(config)
2699 fn rewrite_where_clause_rfc_style(
2700 context: &RewriteContext<'_>,
2701 where_clause: &ast::WhereClause,
2704 span_end: Option<BytePos>,
2705 span_end_before_where: BytePos,
2706 where_clause_option: WhereClauseOption,
2707 ) -> Option<String> {
2708 let (where_keyword, allow_single_line) = rewrite_where_keyword(
2712 span_end_before_where,
2713 where_clause_option,
2717 let clause_shape = shape
2719 .with_max_width(context.config)
2720 .block_left(context.config.tab_spaces())?
2722 let force_single_line = context.config.where_single_line()
2723 && where_clause.predicates.len() == 1
2724 && !where_clause_option.veto_single_line;
2726 let preds_str = rewrite_bounds_on_where_clause(
2732 where_clause_option,
2738 if allow_single_line && !preds_str.contains('\n') && 6 + preds_str.len() <= shape.width
2739 || force_single_line
2743 clause_shape.indent.to_string_with_newline(context.config)
2746 Some(format!("{}{}{}", where_keyword, clause_sep, preds_str))
2749 /// Rewrite `where` and comment around it.
2750 fn rewrite_where_keyword(
2751 context: &RewriteContext<'_>,
2752 where_clause: &ast::WhereClause,
2754 span_end_before_where: BytePos,
2755 where_clause_option: WhereClauseOption,
2756 ) -> Option<(String, bool)> {
2757 let block_shape = shape.block().with_max_width(context.config);
2759 let clause_shape = block_shape
2760 .block_left(context.config.tab_spaces())?
2763 let comment_separator = |comment: &str, shape: Shape| {
2764 if comment.is_empty() {
2767 shape.indent.to_string_with_newline(context.config)
2771 let (span_before, span_after) =
2772 missing_span_before_after_where(span_end_before_where, where_clause);
2773 let (comment_before, comment_after) =
2774 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2776 let starting_newline = match where_clause_option.snuggle {
2777 WhereClauseSpace::Space if comment_before.is_empty() => Cow::from(" "),
2778 WhereClauseSpace::None => Cow::from(""),
2779 _ => block_shape.indent.to_string_with_newline(context.config),
2782 let newline_before_where = comment_separator(&comment_before, shape);
2783 let newline_after_where = comment_separator(&comment_after, clause_shape);
2784 let result = format!(
2786 starting_newline, comment_before, newline_before_where, newline_after_where, comment_after
2788 let allow_single_line = where_clause_option.allow_single_line
2789 && comment_before.is_empty()
2790 && comment_after.is_empty();
2792 Some((result, allow_single_line))
2795 /// Rewrite bounds on a where clause.
2796 fn rewrite_bounds_on_where_clause(
2797 context: &RewriteContext<'_>,
2798 where_clause: &ast::WhereClause,
2801 span_end: Option<BytePos>,
2802 where_clause_option: WhereClauseOption,
2803 force_single_line: bool,
2804 ) -> Option<String> {
2805 let span_start = where_clause.predicates[0].span().lo();
2806 // If we don't have the start of the next span, then use the end of the
2807 // predicates, but that means we miss comments.
2808 let len = where_clause.predicates.len();
2809 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2810 let span_end = span_end.unwrap_or(end_of_preds);
2811 let items = itemize_list(
2812 context.snippet_provider,
2813 where_clause.predicates.iter(),
2816 |pred| pred.span().lo(),
2817 |pred| pred.span().hi(),
2818 |pred| pred.rewrite(context, shape),
2823 let comma_tactic = if where_clause_option.suppress_comma || force_single_line {
2824 SeparatorTactic::Never
2826 context.config.trailing_comma()
2829 // shape should be vertical only and only if we have `force_single_line` option enabled
2830 // and the number of items of the where-clause is equal to 1
2831 let shape_tactic = if force_single_line {
2832 DefinitiveListTactic::Horizontal
2834 DefinitiveListTactic::Vertical
2837 let fmt = ListFormatting::new(shape, context.config)
2838 .tactic(shape_tactic)
2839 .trailing_separator(comma_tactic)
2840 .preserve_newline(true);
2841 write_list(&items.collect::<Vec<_>>(), &fmt)
2844 fn rewrite_where_clause(
2845 context: &RewriteContext<'_>,
2846 where_clause: &ast::WhereClause,
2847 brace_style: BraceStyle,
2851 span_end: Option<BytePos>,
2852 span_end_before_where: BytePos,
2853 where_clause_option: WhereClauseOption,
2854 ) -> Option<String> {
2855 if where_clause.predicates.is_empty() {
2856 return Some(String::new());
2859 if context.config.indent_style() == IndentStyle::Block {
2860 return rewrite_where_clause_rfc_style(
2866 span_end_before_where,
2867 where_clause_option,
2871 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2873 let offset = match context.config.indent_style() {
2874 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2875 // 6 = "where ".len()
2876 IndentStyle::Visual => shape.indent + extra_indent + 6,
2878 // FIXME: if indent_style != Visual, then the budgets below might
2879 // be out by a char or two.
2881 let budget = context.config.max_width() - offset.width();
2882 let span_start = where_clause.predicates[0].span().lo();
2883 // If we don't have the start of the next span, then use the end of the
2884 // predicates, but that means we miss comments.
2885 let len = where_clause.predicates.len();
2886 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2887 let span_end = span_end.unwrap_or(end_of_preds);
2888 let items = itemize_list(
2889 context.snippet_provider,
2890 where_clause.predicates.iter(),
2893 |pred| pred.span().lo(),
2894 |pred| pred.span().hi(),
2895 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2900 let item_vec = items.collect::<Vec<_>>();
2901 // FIXME: we don't need to collect here
2902 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2904 let mut comma_tactic = context.config.trailing_comma();
2905 // Kind of a hack because we don't usually have trailing commas in where-clauses.
2906 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2907 comma_tactic = SeparatorTactic::Never;
2910 let fmt = ListFormatting::new(Shape::legacy(budget, offset), context.config)
2912 .trailing_separator(comma_tactic)
2913 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2914 .preserve_newline(true);
2915 let preds_str = write_list(&item_vec, &fmt)?;
2917 let end_length = if terminator == "{" {
2918 // If the brace is on the next line we don't need to count it otherwise it needs two
2921 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2922 BraceStyle::PreferSameLine => 2,
2924 } else if terminator == "=" {
2930 || preds_str.contains('\n')
2931 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2935 (shape.indent + extra_indent).to_string(context.config),
2939 Some(format!(" where {}", preds_str))
2943 fn missing_span_before_after_where(
2944 before_item_span_end: BytePos,
2945 where_clause: &ast::WhereClause,
2947 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2949 let pos_after_where = where_clause.span.lo() + BytePos(5);
2950 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2951 (missing_span_before, missing_span_after)
2954 fn rewrite_comments_before_after_where(
2955 context: &RewriteContext<'_>,
2956 span_before_where: Span,
2957 span_after_where: Span,
2959 ) -> Option<(String, String)> {
2960 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2961 let after_comment = rewrite_missing_comment(
2963 shape.block_indent(context.config.tab_spaces()),
2966 Some((before_comment, after_comment))
2970 context: &RewriteContext<'_>,
2973 vis: &ast::Visibility,
2977 format_visibility(context, vis),
2979 rewrite_ident(context, ident)
2983 #[derive(PartialEq, Eq, Clone, Copy)]
2991 context: &RewriteContext<'_>,
2992 generics: &ast::Generics,
2993 brace_style: BraceStyle,
2994 brace_pos: BracePos,
2998 ) -> Option<String> {
2999 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
3000 let mut result = rewrite_generics(context, "", generics, shape)?;
3002 // If the generics are not parameterized then generics.span.hi() == 0,
3003 // so we use span.lo(), which is the position after `struct Foo`.
3004 let span_end_before_where = if !generics.params.is_empty() {
3009 let (same_line_brace, missed_comments) = if !generics.where_clause.predicates.is_empty() {
3010 let budget = context.budget(last_line_used_width(&result, offset.width()));
3011 let mut option = WhereClauseOption::snuggled(&result);
3012 if brace_pos == BracePos::None {
3013 option.suppress_comma = true;
3015 let where_clause_str = rewrite_where_clause(
3017 &generics.where_clause,
3019 Shape::legacy(budget, offset.block_only()),
3023 span_end_before_where,
3026 result.push_str(&where_clause_str);
3028 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine,
3029 // missed comments are taken care of in #rewrite_where_clause
3034 brace_pos == BracePos::ForceSameLine
3035 || (result.contains('\n') && brace_style == BraceStyle::PreferSameLine
3036 || brace_style != BraceStyle::AlwaysNextLine)
3037 || trimmed_last_line_width(&result) == 1,
3038 rewrite_missing_comment(
3040 span_end_before_where,
3041 if brace_pos == BracePos::None {
3044 context.snippet_provider.span_before(span, "{")
3052 // add missing comments
3053 let missed_line_comments = missed_comments
3054 .filter(|missed_comments| !missed_comments.is_empty())
3055 .map_or(false, |missed_comments| {
3056 let is_block = is_last_comment_block(&missed_comments);
3057 let sep = if is_block { " " } else { "\n" };
3058 result.push_str(sep);
3059 result.push_str(&missed_comments);
3062 if brace_pos == BracePos::None {
3063 return Some(result);
3065 let total_used_width = last_line_used_width(&result, used_width);
3066 let remaining_budget = context.budget(total_used_width);
3067 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
3068 // and hence we take the closer into account as well for one line budget.
3069 // We assume that the closer has the same length as the opener.
3070 let overhead = if brace_pos == BracePos::ForceSameLine {
3077 let forbid_same_line_brace = missed_line_comments || overhead > remaining_budget;
3078 if !forbid_same_line_brace && same_line_brace {
3082 result.push_str(&offset.block_only().to_string(context.config));
3089 impl Rewrite for ast::ForeignItem {
3090 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
3091 let attrs_str = self.attrs.rewrite(context, shape)?;
3092 // Drop semicolon or it will be interpreted as comment.
3093 // FIXME: this may be a faulty span from libsyntax.
3094 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
3096 let item_str = match self.kind {
3097 ast::ForeignItemKind::Fn(_, ref fn_sig, ref generics, _) => rewrite_fn_base(
3101 &FnSig::new(&fn_sig.decl, generics, self.vis.clone()),
3105 .map(|(s, _)| format!("{};", s)),
3106 ast::ForeignItemKind::Static(ref ty, mutability, _) => {
3107 // FIXME(#21): we're dropping potential comments in between the
3108 // function kw here.
3109 let vis = format_visibility(context, &self.vis);
3110 let mut_str = format_mutability(mutability);
3111 let prefix = format!(
3115 rewrite_ident(context, self.ident)
3118 rewrite_assign_rhs(context, prefix, &**ty, shape.sub_width(1)?).map(|s| s + ";")
3120 ast::ForeignItemKind::TyAlias(..) => {
3121 let vis = format_visibility(context, &self.vis);
3125 rewrite_ident(context, self.ident)
3128 ast::ForeignItemKind::MacCall(ref mac) => {
3129 rewrite_macro(mac, None, context, shape, MacroPosition::Item)
3133 let missing_span = if self.attrs.is_empty() {
3134 mk_sp(self.span.lo(), self.span.lo())
3136 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
3138 combine_strs_with_missing_comments(
3149 /// Rewrite the attributes of an item.
3151 context: &RewriteContext<'_>,
3155 ) -> Option<String> {
3156 let attrs = filter_inline_attrs(&item.attrs, item.span());
3157 let attrs_str = attrs.rewrite(context, shape)?;
3159 let missed_span = if attrs.is_empty() {
3160 mk_sp(item.span.lo(), item.span.lo())
3162 mk_sp(attrs[attrs.len() - 1].span.hi(), item.span.lo())
3165 let allow_extend = if attrs.len() == 1 {
3166 let line_len = attrs_str.len() + 1 + item_str.len();
3167 !attrs.first().unwrap().is_doc_comment()
3168 && context.config.inline_attribute_width() >= line_len
3173 combine_strs_with_missing_comments(
3183 /// Rewrite an inline mod.
3184 /// The given shape is used to format the mod's attributes.
3185 pub(crate) fn rewrite_mod(
3186 context: &RewriteContext<'_>,
3189 ) -> Option<String> {
3190 let mut result = String::with_capacity(32);
3191 result.push_str(&*format_visibility(context, &item.vis));
3192 result.push_str("mod ");
3193 result.push_str(rewrite_ident(context, item.ident));
3195 rewrite_attrs(context, item, &result, attrs_shape)
3198 /// Rewrite `extern crate foo;`.
3199 /// The given shape is used to format the extern crate's attributes.
3200 pub(crate) fn rewrite_extern_crate(
3201 context: &RewriteContext<'_>,
3204 ) -> Option<String> {
3205 assert!(is_extern_crate(item));
3206 let new_str = context.snippet(item.span);
3207 let item_str = if contains_comment(new_str) {
3210 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
3211 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
3213 rewrite_attrs(context, item, &item_str, attrs_shape)
3216 /// Returns `true` for `mod foo;`, false for `mod foo { .. }`.
3217 pub(crate) fn is_mod_decl(item: &ast::Item) -> bool {
3219 ast::ItemKind::Mod(ref m) => m.inner.hi() != item.span.hi(),
3224 pub(crate) fn is_use_item(item: &ast::Item) -> bool {
3226 ast::ItemKind::Use(_) => true,
3231 pub(crate) fn is_extern_crate(item: &ast::Item) -> bool {
3233 ast::ItemKind::ExternCrate(..) => true,