1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Formatting top-level items - functions, structs, enums, traits, impls.
14 use std::cmp::{min, Ordering};
18 use rustc_target::spec::abi;
19 use syntax::source_map::{self, BytePos, Span};
21 use syntax::{ast, ptr, symbol};
24 combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
25 recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented,
27 use config::{BraceStyle, Config, Density, IndentStyle};
29 format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs, rewrite_assign_rhs_with,
32 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, ListItem, Separator};
33 use macros::{rewrite_macro, MacroPosition};
35 use rewrite::{Rewrite, RewriteContext};
36 use shape::{Indent, Shape};
37 use source_map::{LineRangeUtils, SpanUtils};
40 use vertical::rewrite_with_alignment;
41 use visitor::FmtVisitor;
43 const DEFAULT_VISIBILITY: ast::Visibility = source_map::Spanned {
44 node: ast::VisibilityKind::Inherited,
45 span: source_map::DUMMY_SP,
48 fn type_annotation_separator(config: &Config) -> &str {
49 colon_spaces(config.space_before_colon(), config.space_after_colon())
52 // Statements of the form
53 // let pat: ty = init;
54 impl Rewrite for ast::Local {
55 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
57 "Local::rewrite {:?} {} {:?}",
58 self, shape.width, shape.indent
61 skip_out_of_file_lines_range!(context, self.span);
63 if contains_skip(&self.attrs) {
67 let attrs_str = self.attrs.rewrite(context, shape)?;
68 let mut result = if attrs_str.is_empty() {
71 combine_strs_with_missing_comments(
76 self.attrs.last().map(|a| a.span.hi()).unwrap(),
85 let pat_shape = shape.offset_left(4)?;
87 let pat_shape = pat_shape.sub_width(1)?;
88 let pat_str = self.pat.rewrite(context, pat_shape)?;
89 result.push_str(&pat_str);
91 // String that is placed within the assignment pattern and expression.
93 let mut infix = String::with_capacity(32);
95 if let Some(ref ty) = self.ty {
96 let separator = type_annotation_separator(context.config);
97 let indent = shape.indent + last_line_width(&result) + separator.len();
99 let budget = shape.width.checked_sub(indent.width() + 1)?;
100 let rewrite = ty.rewrite(context, Shape::legacy(budget, indent))?;
102 infix.push_str(separator);
103 infix.push_str(&rewrite);
106 if self.init.is_some() {
107 infix.push_str(" =");
113 result.push_str(&infix);
115 if let Some(ref ex) = self.init {
116 // 1 = trailing semicolon;
117 let nested_shape = shape.sub_width(1)?;
119 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
127 // FIXME convert to using rewrite style rather than visitor
128 // FIXME format modules in this style
131 keyword: &'static str,
132 abi: Cow<'static, str>,
133 vis: Option<&'a ast::Visibility>,
134 body: Vec<BodyElement<'a>>,
139 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
142 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
147 .map(|i| BodyElement::ForeignItem(i))
154 enum BodyElement<'a> {
155 // Stmt(&'a ast::Stmt),
156 // Field(&'a ast::Field),
157 // Variant(&'a ast::Variant),
158 // Item(&'a ast::Item),
159 ForeignItem(&'a ast::ForeignItem),
162 /// Represents a fn's signature.
163 pub struct FnSig<'a> {
164 decl: &'a ast::FnDecl,
165 generics: &'a ast::Generics,
167 is_async: ast::IsAsync,
168 constness: ast::Constness,
169 defaultness: ast::Defaultness,
170 unsafety: ast::Unsafety,
171 visibility: ast::Visibility,
176 decl: &'a ast::FnDecl,
177 generics: &'a ast::Generics,
178 vis: ast::Visibility,
184 is_async: ast::IsAsync::NotAsync,
185 constness: ast::Constness::NotConst,
186 defaultness: ast::Defaultness::Final,
187 unsafety: ast::Unsafety::Normal,
192 pub fn from_method_sig(
193 method_sig: &'a ast::MethodSig,
194 generics: &'a ast::Generics,
197 unsafety: method_sig.header.unsafety,
198 is_async: method_sig.header.asyncness,
199 constness: method_sig.header.constness.node,
200 defaultness: ast::Defaultness::Final,
201 abi: method_sig.header.abi,
202 decl: &*method_sig.decl,
204 visibility: DEFAULT_VISIBILITY,
209 fn_kind: &'a visit::FnKind,
210 generics: &'a ast::Generics,
211 decl: &'a ast::FnDecl,
212 defaultness: ast::Defaultness,
215 visit::FnKind::ItemFn(_, fn_header, visibility, _) => FnSig {
219 constness: fn_header.constness.node,
220 is_async: fn_header.asyncness,
222 unsafety: fn_header.unsafety,
223 visibility: visibility.clone(),
225 visit::FnKind::Method(_, method_sig, vis, _) => {
226 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
227 fn_sig.defaultness = defaultness;
228 if let Some(vis) = vis {
229 fn_sig.visibility = vis.clone();
237 fn to_str(&self, context: &RewriteContext) -> String {
238 let mut result = String::with_capacity(128);
239 // Vis defaultness constness unsafety abi.
240 result.push_str(&*format_visibility(context, &self.visibility));
241 result.push_str(format_defaultness(self.defaultness));
242 result.push_str(format_constness(self.constness));
243 result.push_str(format_unsafety(self.unsafety));
244 result.push_str(format_async(self.is_async));
245 result.push_str(&format_abi(
247 context.config.force_explicit_abi(),
254 impl<'a> FmtVisitor<'a> {
255 fn format_item(&mut self, item: &Item) {
256 self.buffer.push_str(&item.abi);
258 let snippet = self.snippet(item.span);
259 let brace_pos = snippet.find_uncommented("{").unwrap();
262 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
263 // FIXME: this skips comments between the extern keyword and the opening
265 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
266 self.block_indent = self.block_indent.block_indent(self.config);
268 if item.body.is_empty() {
269 self.format_missing_no_indent(item.span.hi() - BytePos(1));
270 self.block_indent = self.block_indent.block_unindent(self.config);
271 let indent_str = self.block_indent.to_string(self.config);
272 self.push_str(&indent_str);
274 for item in &item.body {
275 self.format_body_element(item);
278 self.block_indent = self.block_indent.block_unindent(self.config);
279 self.format_missing_with_indent(item.span.hi() - BytePos(1));
284 self.last_pos = item.span.hi();
287 fn format_body_element(&mut self, element: &BodyElement) {
289 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
293 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
294 let item = Item::from_foreign_mod(fm, span, self.config);
295 self.format_item(&item);
298 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
299 let rewrite = item.rewrite(&self.get_context(), self.shape());
300 self.push_rewrite(item.span(), rewrite);
301 self.last_pos = item.span.hi();
311 inner_attrs: Option<&[ast::Attribute]>,
312 ) -> Option<String> {
313 let context = self.get_context();
315 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
317 let (mut result, force_newline_brace) =
318 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
321 if self.config.brace_style() == BraceStyle::AlwaysNextLine
322 || force_newline_brace
323 || last_line_width(&result) + 2 > self.shape().width
325 newline_brace = true;
326 } else if !result.contains('\n') {
327 newline_brace = false;
330 // Prepare for the function body by possibly adding a newline and
332 // FIXME we'll miss anything between the end of the signature and the
333 // start of the body, but we need more spans from the compiler to solve
336 result.push_str(&indent.to_string_with_newline(self.config));
341 self.single_line_fn(&result, block, inner_attrs)
342 .or_else(|| Some(result))
345 pub fn rewrite_required_fn(
349 sig: &ast::MethodSig,
350 generics: &ast::Generics,
352 ) -> Option<String> {
353 // Drop semicolon or it will be interpreted as comment.
354 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
355 let context = self.get_context();
357 let (mut result, _) = rewrite_fn_base(
361 &FnSig::from_method_sig(sig, generics),
367 // Re-attach semicolon
377 inner_attrs: Option<&[ast::Attribute]>,
378 ) -> Option<String> {
379 if fn_str.contains('\n') || inner_attrs.map_or(false, |a| !a.is_empty()) {
383 let source_map = self.get_context().source_map;
385 if self.config.empty_item_single_line()
386 && is_empty_block(block, None, source_map)
387 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
389 return Some(format!("{}{{}}", fn_str));
392 if self.config.fn_single_line() && is_simple_block_stmt(block, None, source_map) {
394 if let Some(stmt) = block.stmts.first() {
395 match stmt_expr(stmt) {
397 let suffix = if semicolon_for_expr(&self.get_context(), e) {
403 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
405 .or_else(|| Some(self.snippet(e.span).to_owned()))
407 None => stmt.rewrite(&self.get_context(), self.shape()),
414 if let Some(res) = rewrite {
415 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
416 if !res.contains('\n') && width <= self.config.max_width() {
417 return Some(format!("{}{{ {} }}", fn_str, res));
425 pub fn visit_static(&mut self, static_parts: &StaticParts) {
426 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
427 self.push_rewrite(static_parts.span, rewrite);
430 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
431 let is_tuple = struct_parts.def.is_tuple();
432 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
433 .map(|s| if is_tuple { s + ";" } else { s });
434 self.push_rewrite(struct_parts.span, rewrite);
440 vis: &ast::Visibility,
441 enum_def: &ast::EnumDef,
442 generics: &ast::Generics,
445 let enum_header = format_header(&self.get_context(), "enum ", ident, vis);
446 self.push_str(&enum_header);
448 let enum_snippet = self.snippet(span);
449 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
450 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
451 let generics_str = format_generics(
454 self.config.brace_style(),
455 if enum_def.variants.is_empty() {
456 BracePos::ForceSameLine
461 mk_sp(span.lo(), body_start),
462 last_line_width(&enum_header),
465 self.push_str(&generics_str);
467 self.last_pos = body_start;
469 match self.format_variant_list(enum_def, body_start, span.hi()) {
470 Some(ref s) if enum_def.variants.is_empty() => self.push_str(s),
472 self.push_rewrite(mk_sp(body_start, span.hi()), rw);
473 self.block_indent = self.block_indent.block_unindent(self.config);
478 // Format the body of an enum definition
479 fn format_variant_list(
481 enum_def: &ast::EnumDef,
484 ) -> Option<String> {
485 if enum_def.variants.is_empty() {
486 let mut buffer = String::with_capacity(128);
488 let span = mk_sp(body_lo, body_hi - BytePos(1));
489 format_empty_struct_or_tuple(
499 let mut result = String::with_capacity(1024);
500 let original_offset = self.block_indent;
501 self.block_indent = self.block_indent.block_indent(self.config);
503 // If enum variants have discriminants, try to vertically align those,
504 // provided the discrims are not shifted too much to the right
505 let align_threshold: usize = self.config.enum_discrim_align_threshold();
506 let discr_ident_lens: Vec<usize> = enum_def
509 .filter(|var| var.node.disr_expr.is_some())
510 .map(|var| rewrite_ident(&self.get_context(), var.node.ident).len())
512 // cut the list at the point of longest discrim shorter than the threshold
513 // All of the discrims under the threshold will get padded, and all above - left as is.
514 let pad_discrim_ident_to = *discr_ident_lens
516 .filter(|&l| *l <= align_threshold)
520 let itemize_list_with = |one_line_width: usize| {
522 self.snippet_provider,
523 enum_def.variants.iter(),
527 if !f.node.attrs.is_empty() {
528 f.node.attrs[0].span.lo()
534 |f| self.format_variant(f, one_line_width, pad_discrim_ident_to),
541 let mut items: Vec<_> =
542 itemize_list_with(self.config.width_heuristics().struct_variant_width);
543 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
544 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
545 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
546 if has_multiline_variant && has_single_line_variant {
547 items = itemize_list_with(0);
550 let shape = self.shape().sub_width(2)?;
551 let fmt = ListFormatting::new(shape, self.config)
552 .trailing_separator(self.config.trailing_comma())
553 .preserve_newline(true);
555 let list = write_list(&items, &fmt)?;
556 result.push_str(&list);
557 result.push_str(&original_offset.to_string_with_newline(self.config));
562 // Variant of an enum.
565 field: &ast::Variant,
566 one_line_width: usize,
567 pad_discrim_ident_to: usize,
568 ) -> Option<String> {
569 if contains_skip(&field.node.attrs) {
570 let lo = field.node.attrs[0].span.lo();
571 let span = mk_sp(lo, field.span.hi());
572 return Some(self.snippet(span).to_owned());
575 let context = self.get_context();
577 let shape = self.shape().sub_width(1)?;
578 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
583 .map_or(field.span.lo(), |attr| attr.span.hi());
584 let span = mk_sp(lo, field.span.lo());
586 let variant_body = match field.node.data {
587 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
589 &StructParts::from_variant(field),
591 Some(one_line_width),
593 ast::VariantData::Unit(..) => {
594 if let Some(ref expr) = field.node.disr_expr {
597 rewrite_ident(&context, field.node.ident),
600 rewrite_assign_rhs(&context, lhs, &*expr.value, shape)?
602 rewrite_ident(&context, field.node.ident).to_owned()
607 combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
610 fn visit_impl_items(&mut self, items: &[ast::ImplItem]) {
611 if self.get_context().config.reorder_impl_items() {
612 // Create visitor for each items, then reorder them.
613 let mut buffer = vec![];
615 self.visit_impl_item(item);
616 buffer.push((self.buffer.clone(), item.clone()));
619 // type -> existential -> const -> macro -> method
620 use ast::ImplItemKind::*;
621 fn need_empty_line(a: &ast::ImplItemKind, b: &ast::ImplItemKind) -> bool {
624 | (Const(..), Const(..))
625 | (Existential(..), Existential(..)) => false,
630 buffer.sort_by(|(_, a), (_, b)| match (&a.node, &b.node) {
632 | (Const(..), Const(..))
633 | (Macro(..), Macro(..))
634 | (Existential(..), Existential(..)) => a.ident.as_str().cmp(&b.ident.as_str()),
635 (Method(..), Method(..)) => a.span.lo().cmp(&b.span.lo()),
636 (Type(..), _) => Ordering::Less,
637 (_, Type(..)) => Ordering::Greater,
638 (Existential(..), _) => Ordering::Less,
639 (_, Existential(..)) => Ordering::Greater,
640 (Const(..), _) => Ordering::Less,
641 (_, Const(..)) => Ordering::Greater,
642 (Macro(..), _) => Ordering::Less,
643 (_, Macro(..)) => Ordering::Greater,
645 let mut prev_kind = None;
646 for (buf, item) in buffer {
647 // Make sure that there are at least a single empty line between
648 // different impl items.
651 .map_or(false, |prev_kind| need_empty_line(prev_kind, &item.node))
655 let indent_str = self.block_indent.to_string_with_newline(self.config);
656 self.push_str(&indent_str);
657 self.push_str(buf.trim());
658 prev_kind = Some(item.node.clone());
662 self.visit_impl_item(item);
669 context: &RewriteContext,
672 where_span_end: Option<BytePos>,
673 ) -> Option<String> {
674 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
675 let mut result = String::with_capacity(128);
676 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
677 let sep = offset.to_string_with_newline(context.config);
678 result.push_str(&ref_and_type);
680 let where_budget = if result.contains('\n') {
681 context.config.max_width()
683 context.budget(last_line_width(&result))
686 let mut option = WhereClauseOption::snuggled(&ref_and_type);
687 let snippet = context.snippet(item.span);
688 let open_pos = snippet.find_uncommented("{")? + 1;
689 if !contains_comment(&snippet[open_pos..])
691 && generics.where_clause.predicates.len() == 1
692 && !result.contains('\n')
694 option.suppress_comma();
696 option.compress_where();
699 let where_clause_str = rewrite_where_clause(
701 &generics.where_clause,
702 context.config.brace_style(),
703 Shape::legacy(where_budget, offset.block_only()),
712 // If there is no where clause, we may have missing comments between the trait name and
713 // the opening brace.
714 if generics.where_clause.predicates.is_empty() {
715 if let Some(hi) = where_span_end {
716 match recover_missing_comment_in_span(
717 mk_sp(self_ty.span.hi(), hi),
718 Shape::indented(offset, context.config),
720 last_line_width(&result),
722 Some(ref missing_comment) if !missing_comment.is_empty() => {
723 result.push_str(missing_comment);
730 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
731 result.push_str(&where_clause_str);
732 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
733 // if the where_clause contains extra comments AND
734 // there is only one where clause predicate
735 // recover the suppressed comma in single line where_clause formatting
736 if generics.where_clause.predicates.len() == 1 {
737 result.push_str(",");
739 result.push_str(&format!("{}{{{}}}", &sep, &sep));
741 result.push_str(" {}");
746 result.push_str(&where_clause_str);
748 let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
749 match context.config.brace_style() {
750 _ if need_newline => result.push_str(&sep),
751 BraceStyle::AlwaysNextLine => result.push_str(&sep),
752 BraceStyle::PreferSameLine => result.push(' '),
753 BraceStyle::SameLineWhere => {
754 if !where_clause_str.is_empty() {
755 result.push_str(&sep);
764 let snippet = context.snippet(item.span);
765 let open_pos = snippet.find_uncommented("{")? + 1;
767 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
768 let mut visitor = FmtVisitor::from_context(context);
769 let item_indent = offset.block_only().block_indent(context.config);
770 visitor.block_indent = item_indent;
771 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
773 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
774 visitor.visit_impl_items(items);
776 visitor.format_missing(item.span.hi() - BytePos(1));
778 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
779 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
781 result.push_str(&inner_indent_str);
782 result.push_str(visitor.buffer.to_string().trim());
783 result.push_str(&outer_indent_str);
786 if result.ends_with('{') && !context.config.empty_item_single_line() {
787 result.push_str(&sep);
797 fn is_impl_single_line(
798 context: &RewriteContext,
799 items: &[ast::ImplItem],
801 where_clause_str: &str,
804 let snippet = context.snippet(item.span);
805 let open_pos = snippet.find_uncommented("{")? + 1;
808 context.config.empty_item_single_line()
810 && !result.contains('\n')
811 && result.len() + where_clause_str.len() <= context.config.max_width()
812 && !contains_comment(&snippet[open_pos..]),
816 fn format_impl_ref_and_type(
817 context: &RewriteContext,
820 ) -> Option<String> {
821 if let ast::ItemKind::Impl(
831 let mut result = String::with_capacity(128);
833 result.push_str(&format_visibility(context, &item.vis));
834 result.push_str(format_defaultness(defaultness));
835 result.push_str(format_unsafety(unsafety));
837 let shape = generics_shape_from_config(
839 Shape::indented(offset + last_line_width(&result), context.config),
842 let generics_str = rewrite_generics(context, "impl", generics, shape)?;
843 result.push_str(&generics_str);
845 let polarity_str = if polarity == ast::ImplPolarity::Negative {
851 if let Some(ref trait_ref) = *trait_ref {
852 let result_len = last_line_width(&result);
853 result.push_str(&rewrite_trait_ref(
862 // Try to put the self type in a single line.
864 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
865 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
866 // If there is no where clause adapt budget for type formatting to take space and curly
867 // brace into account.
868 match context.config.brace_style() {
869 BraceStyle::AlwaysNextLine => 0,
875 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
876 // 1 = space before the type.
877 let budget = context.budget(used_space + 1);
878 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
879 if !self_ty_str.contains('\n') {
880 if trait_ref.is_some() {
881 result.push_str(" for ");
885 result.push_str(&self_ty_str);
890 // Couldn't fit the self type on a single line, put it on a new line.
892 // Add indentation of one additional tab.
893 let new_line_offset = offset.block_indent(context.config);
894 result.push_str(&new_line_offset.to_string(context.config));
895 if trait_ref.is_some() {
896 result.push_str("for ");
898 let budget = context.budget(last_line_width(&result));
899 let type_offset = match context.config.indent_style() {
900 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
901 IndentStyle::Block => new_line_offset,
903 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
910 fn rewrite_trait_ref(
911 context: &RewriteContext,
912 trait_ref: &ast::TraitRef,
916 ) -> Option<String> {
917 // 1 = space between generics and trait_ref
918 let used_space = 1 + polarity_str.len() + result_len;
919 let shape = Shape::indented(offset + used_space, context.config);
920 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
921 if !trait_ref_str.contains('\n') {
922 return Some(format!(" {}{}", polarity_str, &trait_ref_str));
925 // We could not make enough space for trait_ref, so put it on new line.
926 let offset = offset.block_indent(context.config);
927 let shape = Shape::indented(offset, context.config);
928 let trait_ref_str = trait_ref.rewrite(context, shape)?;
931 &offset.to_string_with_newline(context.config),
937 pub struct StructParts<'a> {
940 vis: &'a ast::Visibility,
941 def: &'a ast::VariantData,
942 generics: Option<&'a ast::Generics>,
946 impl<'a> StructParts<'a> {
947 fn format_header(&self, context: &RewriteContext) -> String {
948 format_header(context, self.prefix, self.ident, self.vis)
951 fn from_variant(variant: &'a ast::Variant) -> Self {
954 ident: variant.node.ident,
955 vis: &DEFAULT_VISIBILITY,
956 def: &variant.node.data,
962 pub fn from_item(item: &'a ast::Item) -> Self {
963 let (prefix, def, generics) = match item.node {
964 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
965 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
973 generics: Some(generics),
980 context: &RewriteContext,
981 struct_parts: &StructParts,
983 one_line_width: Option<usize>,
984 ) -> Option<String> {
985 match *struct_parts.def {
986 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
987 ast::VariantData::Tuple(ref fields, _) => {
988 format_tuple_struct(context, struct_parts, fields, offset)
990 ast::VariantData::Struct(ref fields, _) => {
991 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
996 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
997 if let ast::ItemKind::Trait(
1005 let mut result = String::with_capacity(128);
1006 let header = format!(
1008 format_visibility(context, &item.vis),
1009 format_unsafety(unsafety),
1010 format_auto(is_auto),
1012 result.push_str(&header);
1014 let body_lo = context.snippet_provider.span_after(item.span, "{");
1016 let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
1018 rewrite_generics(context, rewrite_ident(context, item.ident), generics, shape)?;
1019 result.push_str(&generics_str);
1021 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
1022 if !generic_bounds.is_empty() {
1023 let ident_hi = context
1025 .span_after(item.span, &item.ident.as_str());
1026 let bound_hi = generic_bounds.last().unwrap().span().hi();
1027 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
1028 if contains_comment(snippet) {
1032 result = rewrite_assign_rhs_with(
1037 RhsTactics::ForceNextLineWithoutIndent,
1041 // Rewrite where clause.
1042 if !generics.where_clause.predicates.is_empty() {
1043 let where_density = if context.config.indent_style() == IndentStyle::Block {
1049 let where_budget = context.budget(last_line_width(&result));
1050 let pos_before_where = if generic_bounds.is_empty() {
1051 generics.where_clause.span.lo()
1053 generic_bounds[generic_bounds.len() - 1].span().hi()
1055 let option = WhereClauseOption::snuggled(&generics_str);
1056 let where_clause_str = rewrite_where_clause(
1058 &generics.where_clause,
1059 context.config.brace_style(),
1060 Shape::legacy(where_budget, offset.block_only()),
1068 // If the where clause cannot fit on the same line,
1069 // put the where clause on a new line
1070 if !where_clause_str.contains('\n')
1071 && last_line_width(&result) + where_clause_str.len() + offset.width()
1072 > context.config.comment_width()
1074 let width = offset.block_indent + context.config.tab_spaces() - 1;
1075 let where_indent = Indent::new(0, width);
1076 result.push_str(&where_indent.to_string_with_newline(context.config));
1078 result.push_str(&where_clause_str);
1080 let item_snippet = context.snippet(item.span);
1081 if let Some(lo) = item_snippet.find('/') {
1083 let comment_hi = body_lo - BytePos(1);
1084 let comment_lo = item.span.lo() + BytePos(lo as u32);
1085 if comment_lo < comment_hi {
1086 match recover_missing_comment_in_span(
1087 mk_sp(comment_lo, comment_hi),
1088 Shape::indented(offset, context.config),
1090 last_line_width(&result),
1092 Some(ref missing_comment) if !missing_comment.is_empty() => {
1093 result.push_str(missing_comment);
1101 match context.config.brace_style() {
1102 _ if last_line_contains_single_line_comment(&result)
1103 || last_line_width(&result) + 2 > context.budget(offset.width()) =>
1105 result.push_str(&offset.to_string_with_newline(context.config));
1107 BraceStyle::AlwaysNextLine => {
1108 result.push_str(&offset.to_string_with_newline(context.config));
1110 BraceStyle::PreferSameLine => result.push(' '),
1111 BraceStyle::SameLineWhere => {
1112 if result.contains('\n')
1113 || (!generics.where_clause.predicates.is_empty() && !trait_items.is_empty())
1115 result.push_str(&offset.to_string_with_newline(context.config));
1123 let snippet = context.snippet(item.span);
1124 let open_pos = snippet.find_uncommented("{")? + 1;
1126 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1127 let mut visitor = FmtVisitor::from_context(context);
1128 visitor.block_indent = offset.block_only().block_indent(context.config);
1129 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1131 for item in trait_items {
1132 visitor.visit_trait_item(item);
1135 visitor.format_missing(item.span.hi() - BytePos(1));
1137 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
1138 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
1140 result.push_str(&inner_indent_str);
1141 result.push_str(visitor.buffer.to_string().trim());
1142 result.push_str(&outer_indent_str);
1143 } else if result.contains('\n') {
1154 pub fn format_trait_alias(
1155 context: &RewriteContext,
1157 generics: &ast::Generics,
1158 generic_bounds: &ast::GenericBounds,
1160 ) -> Option<String> {
1161 let alias = rewrite_ident(context, ident);
1162 // 6 = "trait ", 2 = " ="
1163 let g_shape = shape.offset_left(6)?.sub_width(2)?;
1164 let generics_str = rewrite_generics(context, &alias, generics, g_shape)?;
1165 let lhs = format!("trait {} =", generics_str);
1167 rewrite_assign_rhs(context, lhs, generic_bounds, shape.sub_width(1)?).map(|s| s + ";")
1170 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1171 let header_str = format_header(context, p.prefix, p.ident, p.vis);
1172 let generics_str = if let Some(generics) = p.generics {
1173 let hi = if generics.where_clause.predicates.is_empty() {
1176 generics.where_clause.span.hi()
1181 context.config.brace_style(),
1184 mk_sp(generics.span.lo(), hi),
1185 last_line_width(&header_str),
1190 Some(format!("{}{};", header_str, generics_str))
1193 pub fn format_struct_struct(
1194 context: &RewriteContext,
1195 struct_parts: &StructParts,
1196 fields: &[ast::StructField],
1198 one_line_width: Option<usize>,
1199 ) -> Option<String> {
1200 let mut result = String::with_capacity(1024);
1201 let span = struct_parts.span;
1203 let header_str = struct_parts.format_header(context);
1204 result.push_str(&header_str);
1206 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1207 let body_lo = context.snippet_provider.span_after(span, "{");
1209 let generics_str = match struct_parts.generics {
1210 Some(g) => format_generics(
1213 context.config.brace_style(),
1214 if fields.is_empty() {
1215 BracePos::ForceSameLine
1220 mk_sp(header_hi, body_lo),
1221 last_line_width(&result),
1224 // 3 = ` {}`, 2 = ` {`.
1225 let overhead = if fields.is_empty() { 3 } else { 2 };
1226 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1227 || context.config.max_width() < overhead + result.len()
1229 format!("\n{}{{", offset.block_only().to_string(context.config))
1236 let overhead = if fields.is_empty() { 1 } else { 0 };
1237 let total_width = result.len() + generics_str.len() + overhead;
1238 if !generics_str.is_empty()
1239 && !generics_str.contains('\n')
1240 && total_width > context.config.max_width()
1243 result.push_str(&offset.to_string(context.config));
1244 result.push_str(generics_str.trim_left());
1246 result.push_str(&generics_str);
1249 if fields.is_empty() {
1250 let inner_span = mk_sp(body_lo, span.hi() - BytePos(1));
1251 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "", "}");
1252 return Some(result);
1256 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1257 let one_line_budget =
1258 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1260 let items_str = rewrite_with_alignment(
1263 Shape::indented(offset, context.config).sub_width(1)?,
1264 mk_sp(body_lo, span.hi()),
1268 if !items_str.contains('\n')
1269 && !result.contains('\n')
1270 && items_str.len() <= one_line_budget
1271 && !last_line_contains_single_line_comment(&items_str)
1273 Some(format!("{} {} }}", result, items_str))
1279 .block_indent(context.config)
1280 .to_string(context.config),
1282 offset.to_string(context.config)
1287 fn get_bytepos_after_visibility(vis: &ast::Visibility, default_span: Span) -> BytePos {
1289 ast::VisibilityKind::Crate(..) | ast::VisibilityKind::Restricted { .. } => vis.span.hi(),
1290 _ => default_span.lo(),
1294 // Format tuple or struct without any fields. We need to make sure that the comments
1295 // inside the delimiters are preserved.
1296 fn format_empty_struct_or_tuple(
1297 context: &RewriteContext,
1300 result: &mut String,
1304 // 3 = " {}" or "();"
1305 let used_width = last_line_used_width(&result, offset.width()) + 3;
1306 if used_width > context.config.max_width() {
1307 result.push_str(&offset.to_string_with_newline(context.config))
1309 result.push_str(opener);
1310 match rewrite_missing_comment(span, Shape::indented(offset, context.config), context) {
1311 Some(ref s) if s.is_empty() => (),
1313 if !is_single_line(s) || first_line_contains_single_line_comment(s) {
1314 let nested_indent_str = offset
1315 .block_indent(context.config)
1316 .to_string_with_newline(context.config);
1317 result.push_str(&nested_indent_str);
1320 if last_line_contains_single_line_comment(s) {
1321 result.push_str(&offset.to_string_with_newline(context.config));
1324 None => result.push_str(context.snippet(span)),
1326 result.push_str(closer);
1329 fn format_tuple_struct(
1330 context: &RewriteContext,
1331 struct_parts: &StructParts,
1332 fields: &[ast::StructField],
1334 ) -> Option<String> {
1335 let mut result = String::with_capacity(1024);
1336 let span = struct_parts.span;
1338 let header_str = struct_parts.format_header(context);
1339 result.push_str(&header_str);
1341 let body_lo = if fields.is_empty() {
1342 let lo = get_bytepos_after_visibility(struct_parts.vis, span);
1345 .span_after(mk_sp(lo, span.hi()), "(")
1349 let body_hi = if fields.is_empty() {
1352 .span_after(mk_sp(body_lo, span.hi()), ")")
1354 // This is a dirty hack to work around a missing `)` from the span of the last field.
1355 let last_arg_span = fields[fields.len() - 1].span;
1358 .opt_span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1359 .unwrap_or(last_arg_span.hi())
1362 let where_clause_str = match struct_parts.generics {
1364 let budget = context.budget(last_line_width(&header_str));
1365 let shape = Shape::legacy(budget, offset);
1366 let generics_str = rewrite_generics(context, "", generics, shape)?;
1367 result.push_str(&generics_str);
1369 let where_budget = context.budget(last_line_width(&result));
1370 let option = WhereClauseOption::new(true, false);
1371 rewrite_where_clause(
1373 &generics.where_clause,
1374 context.config.brace_style(),
1375 Shape::legacy(where_budget, offset.block_only()),
1376 Density::Compressed,
1384 None => "".to_owned(),
1387 if fields.is_empty() {
1388 let body_hi = context
1390 .span_before(mk_sp(body_lo, span.hi()), ")");
1391 let inner_span = mk_sp(body_lo, body_hi);
1392 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "(", ")");
1394 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1395 let fields = &fields.iter().collect::<Vec<_>>();
1396 result = overflow::rewrite_with_parens(
1402 context.config.width_heuristics().fn_call_width,
1407 if !where_clause_str.is_empty()
1408 && !where_clause_str.contains('\n')
1409 && (result.contains('\n')
1410 || offset.block_indent + result.len() + where_clause_str.len() + 1
1411 > context.config.max_width())
1413 // We need to put the where clause on a new line, but we didn't
1414 // know that earlier, so the where clause will not be indented properly.
1417 &(offset.block_only() + (context.config.tab_spaces() - 1)).to_string(context.config),
1420 result.push_str(&where_clause_str);
1425 fn rewrite_type_prefix(
1426 context: &RewriteContext,
1430 generics: &ast::Generics,
1431 ) -> Option<String> {
1432 let mut result = String::with_capacity(128);
1433 result.push_str(prefix);
1434 let ident_str = rewrite_ident(context, ident);
1437 if generics.params.is_empty() {
1438 result.push_str(ident_str)
1440 let g_shape = Shape::indented(indent, context.config)
1441 .offset_left(result.len())?
1443 let generics_str = rewrite_generics(context, ident_str, generics, g_shape)?;
1444 result.push_str(&generics_str);
1447 let where_budget = context.budget(last_line_width(&result));
1448 let option = WhereClauseOption::snuggled(&result);
1449 let where_clause_str = rewrite_where_clause(
1451 &generics.where_clause,
1452 context.config.brace_style(),
1453 Shape::legacy(where_budget, indent),
1461 result.push_str(&where_clause_str);
1466 fn rewrite_type_item<R: Rewrite>(
1467 context: &RewriteContext,
1473 generics: &ast::Generics,
1474 vis: &ast::Visibility,
1475 ) -> Option<String> {
1476 let mut result = String::with_capacity(128);
1477 result.push_str(&rewrite_type_prefix(
1480 &format!("{}{} ", format_visibility(context, vis), prefix),
1485 if generics.where_clause.predicates.is_empty() {
1486 result.push_str(suffix);
1488 result.push_str(&indent.to_string_with_newline(context.config));
1489 result.push_str(suffix.trim_left());
1493 let rhs_shape = Shape::indented(indent, context.config).sub_width(1)?;
1494 rewrite_assign_rhs(context, result, rhs, rhs_shape).map(|s| s + ";")
1497 pub fn rewrite_type_alias(
1498 context: &RewriteContext,
1502 generics: &ast::Generics,
1503 vis: &ast::Visibility,
1504 ) -> Option<String> {
1505 rewrite_type_item(context, indent, "type", " =", ident, ty, generics, vis)
1508 pub fn rewrite_existential_type(
1509 context: &RewriteContext,
1512 generic_bounds: &ast::GenericBounds,
1513 generics: &ast::Generics,
1514 vis: &ast::Visibility,
1515 ) -> Option<String> {
1528 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1530 if config.space_before_colon() { " " } else { "" },
1531 if config.space_after_colon() { " " } else { "" },
1535 pub fn rewrite_struct_field_prefix(
1536 context: &RewriteContext,
1537 field: &ast::StructField,
1538 ) -> Option<String> {
1539 let vis = format_visibility(context, &field.vis);
1540 let type_annotation_spacing = type_annotation_spacing(context.config);
1541 Some(match field.ident {
1542 Some(name) => format!(
1545 rewrite_ident(context, name),
1546 type_annotation_spacing.0
1548 None => format!("{}", vis),
1552 impl Rewrite for ast::StructField {
1553 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1554 rewrite_struct_field(context, self, shape, 0)
1558 pub fn rewrite_struct_field(
1559 context: &RewriteContext,
1560 field: &ast::StructField,
1562 lhs_max_width: usize,
1563 ) -> Option<String> {
1564 if contains_skip(&field.attrs) {
1565 return Some(context.snippet(field.span()).to_owned());
1568 let type_annotation_spacing = type_annotation_spacing(context.config);
1569 let prefix = rewrite_struct_field_prefix(context, field)?;
1571 let attrs_str = field.attrs.rewrite(context, shape)?;
1572 let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
1573 let missing_span = if field.attrs.is_empty() {
1574 mk_sp(field.span.lo(), field.span.lo())
1576 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1578 let mut spacing = String::from(if field.ident.is_some() {
1579 type_annotation_spacing.1
1583 // Try to put everything on a single line.
1584 let attr_prefix = combine_strs_with_missing_comments(
1592 let overhead = last_line_width(&attr_prefix);
1593 let lhs_offset = lhs_max_width.saturating_sub(overhead);
1594 for _ in 0..lhs_offset {
1597 // In this extreme case we will be missing a space betweeen an attribute and a field.
1598 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1602 .offset_left(overhead + spacing.len())
1603 .and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
1604 if let Some(ref ty) = orig_ty {
1605 if !ty.contains('\n') {
1606 return Some(attr_prefix + &spacing + ty);
1610 let is_prefix_empty = prefix.is_empty();
1611 // We must use multiline. We are going to put attributes and a field on different lines.
1612 let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, shape)?;
1613 // Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
1614 let field_str = if is_prefix_empty {
1615 field_str.trim_left()
1619 combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
1622 pub struct StaticParts<'a> {
1624 vis: &'a ast::Visibility,
1627 mutability: ast::Mutability,
1628 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1629 defaultness: Option<ast::Defaultness>,
1633 impl<'a> StaticParts<'a> {
1634 pub fn from_item(item: &'a ast::Item) -> Self {
1635 let (prefix, ty, mutability, expr) = match item.node {
1636 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1637 ast::ItemKind::Const(ref ty, ref expr) => {
1638 ("const", ty, ast::Mutability::Immutable, expr)
1640 _ => unreachable!(),
1648 expr_opt: Some(expr),
1654 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1655 let (ty, expr_opt) = match ti.node {
1656 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1657 _ => unreachable!(),
1661 vis: &DEFAULT_VISIBILITY,
1664 mutability: ast::Mutability::Immutable,
1665 expr_opt: expr_opt.as_ref(),
1671 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1672 let (ty, expr) = match ii.node {
1673 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1674 _ => unreachable!(),
1681 mutability: ast::Mutability::Immutable,
1682 expr_opt: Some(expr),
1683 defaultness: Some(ii.defaultness),
1690 context: &RewriteContext,
1691 static_parts: &StaticParts,
1693 ) -> Option<String> {
1694 let colon = colon_spaces(
1695 context.config.space_before_colon(),
1696 context.config.space_after_colon(),
1698 let mut prefix = format!(
1700 format_visibility(context, static_parts.vis),
1701 static_parts.defaultness.map_or("", format_defaultness),
1702 static_parts.prefix,
1703 format_mutability(static_parts.mutability),
1709 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1710 let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
1711 Some(ty_str) => ty_str,
1713 if prefix.ends_with(' ') {
1716 let nested_indent = offset.block_indent(context.config);
1717 let nested_shape = Shape::indented(nested_indent, context.config);
1718 let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
1721 nested_indent.to_string_with_newline(context.config),
1727 if let Some(expr) = static_parts.expr_opt {
1728 let lhs = format!("{}{} =", prefix, ty_str);
1730 let remaining_width = context.budget(offset.block_indent + 1);
1735 Shape::legacy(remaining_width, offset.block_only()),
1737 .and_then(|res| recover_comment_removed(res, static_parts.span, context))
1738 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1740 Some(format!("{}{};", prefix, ty_str))
1744 pub fn rewrite_associated_type(
1746 ty_opt: Option<&ptr::P<ast::Ty>>,
1747 generics: &ast::Generics,
1748 generic_bounds_opt: Option<&ast::GenericBounds>,
1749 context: &RewriteContext,
1751 ) -> Option<String> {
1752 let ident_str = rewrite_ident(context, ident);
1754 let generics_shape = Shape::indented(indent, context.config).offset_left(5)?;
1755 let generics_str = rewrite_generics(context, ident_str, generics, generics_shape)?;
1756 let prefix = format!("type {}", generics_str);
1758 let type_bounds_str = if let Some(bounds) = generic_bounds_opt {
1759 if bounds.is_empty() {
1763 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1764 bounds.rewrite(context, shape).map(|s| format!(": {}", s))?
1770 if let Some(ty) = ty_opt {
1772 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1773 let lhs = format!("{}{} =", prefix, type_bounds_str);
1774 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1776 Some(format!("{}{};", prefix, type_bounds_str))
1780 pub fn rewrite_existential_impl_type(
1781 context: &RewriteContext,
1783 generics: &ast::Generics,
1784 generic_bounds: &ast::GenericBounds,
1786 ) -> Option<String> {
1787 rewrite_associated_type(ident, None, generics, Some(generic_bounds), context, indent)
1788 .map(|s| format!("existential {}", s))
1791 pub fn rewrite_associated_impl_type(
1793 defaultness: ast::Defaultness,
1794 ty_opt: Option<&ptr::P<ast::Ty>>,
1795 generics: &ast::Generics,
1796 context: &RewriteContext,
1798 ) -> Option<String> {
1799 let result = rewrite_associated_type(ident, ty_opt, generics, None, context, indent)?;
1802 ast::Defaultness::Default => Some(format!("default {}", result)),
1807 impl Rewrite for ast::FunctionRetTy {
1808 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1810 ast::FunctionRetTy::Default(_) => Some(String::new()),
1811 ast::FunctionRetTy::Ty(ref ty) => {
1812 let inner_width = shape.width.checked_sub(3)?;
1813 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1814 .map(|r| format!("-> {}", r))
1820 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1822 ast::TyKind::Infer => {
1823 let original = context.snippet(ty.span);
1830 impl Rewrite for ast::Arg {
1831 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1832 if is_named_arg(self) {
1833 let mut result = self
1835 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1837 if !is_empty_infer(context, &*self.ty) {
1838 if context.config.space_before_colon() {
1839 result.push_str(" ");
1841 result.push_str(":");
1842 if context.config.space_after_colon() {
1843 result.push_str(" ");
1845 let overhead = last_line_width(&result);
1846 let max_width = shape.width.checked_sub(overhead)?;
1849 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1850 result.push_str(&ty_str);
1855 self.ty.rewrite(context, shape)
1860 fn rewrite_explicit_self(
1861 explicit_self: &ast::ExplicitSelf,
1863 context: &RewriteContext,
1864 ) -> Option<String> {
1865 match explicit_self.node {
1866 ast::SelfKind::Region(lt, m) => {
1867 let mut_str = format_mutability(m);
1870 let lifetime_str = l.rewrite(
1872 Shape::legacy(context.config.max_width(), Indent::empty()),
1874 Some(format!("&{} {}self", lifetime_str, mut_str))
1876 None => Some(format!("&{}self", mut_str)),
1879 ast::SelfKind::Explicit(ref ty, _) => {
1880 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1882 let mutability = explicit_self_mutability(&args[0]);
1883 let type_str = ty.rewrite(
1885 Shape::legacy(context.config.max_width(), Indent::empty()),
1890 format_mutability(mutability),
1894 ast::SelfKind::Value(_) => {
1895 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1897 let mutability = explicit_self_mutability(&args[0]);
1899 Some(format!("{}self", format_mutability(mutability)))
1904 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1905 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1906 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1907 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1914 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1915 if is_named_arg(arg) {
1922 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1924 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1925 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1926 _ => arg.ty.span.hi(),
1930 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1931 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1932 ident != symbol::keywords::Invalid.ident()
1938 // Return type is (result, force_new_line_for_brace)
1940 context: &RewriteContext,
1945 newline_brace: bool,
1947 ) -> Option<(String, bool)> {
1948 let mut force_new_line_for_brace = false;
1950 let where_clause = &fn_sig.generics.where_clause;
1952 let mut result = String::with_capacity(1024);
1953 result.push_str(&fn_sig.to_str(context));
1956 result.push_str("fn ");
1959 let overhead = if has_body && !newline_brace {
1966 let used_width = last_line_used_width(&result, indent.width());
1967 let one_line_budget = context.budget(used_width + overhead);
1969 width: one_line_budget,
1973 let fd = fn_sig.decl;
1974 let generics_str = rewrite_generics(
1976 rewrite_ident(context, ident),
1980 result.push_str(&generics_str);
1982 let snuggle_angle_bracket = generics_str
1985 .map_or(false, |l| l.trim_left().len() == 1);
1987 // Note that the width and indent don't really matter, we'll re-layout the
1988 // return type later anyway.
1991 .rewrite(context, Shape::indented(indent, context.config))?;
1993 let multi_line_ret_str = ret_str.contains('\n');
1994 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1997 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
2008 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
2009 one_line_budget, multi_line_budget, arg_indent
2012 // Check if vertical layout was forced.
2013 if one_line_budget == 0 {
2014 if snuggle_angle_bracket {
2017 result.push_str("(");
2018 if context.config.indent_style() == IndentStyle::Visual {
2019 result.push_str(&arg_indent.to_string_with_newline(context.config));
2026 // Skip `pub(crate)`.
2027 let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
2028 // A conservative estimation, to goal is to be over all parens in generics
2029 let args_start = fn_sig
2034 .map_or(lo_after_visibility, |param| param.span().hi());
2035 let args_end = if fd.inputs.is_empty() {
2038 .span_after(mk_sp(args_start, span.hi()), ")")
2040 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
2041 context.snippet_provider.span_after(last_span, ")")
2043 let args_span = mk_sp(
2046 .span_after(mk_sp(args_start, span.hi()), "("),
2049 let arg_str = rewrite_args(
2052 fd.get_self().as_ref(),
2059 generics_str.contains('\n'),
2062 let put_args_in_block = match context.config.indent_style() {
2063 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
2065 } && !fd.inputs.is_empty();
2067 let mut args_last_line_contains_comment = false;
2068 if put_args_in_block {
2069 arg_indent = indent.block_indent(context.config);
2070 result.push_str(&arg_indent.to_string_with_newline(context.config));
2071 result.push_str(&arg_str);
2072 result.push_str(&indent.to_string_with_newline(context.config));
2075 result.push_str(&arg_str);
2076 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
2077 // Put the closing brace on the next line if it overflows the max width.
2079 let closing_paren_overflow_max_width =
2080 fd.inputs.is_empty() && used_width + 1 > context.config.max_width();
2081 // If the last line of args contains comment, we cannot put the closing paren
2082 // on the same line.
2083 args_last_line_contains_comment = arg_str
2086 .map_or(false, |last_line| last_line.contains("//"));
2087 if closing_paren_overflow_max_width || args_last_line_contains_comment {
2088 result.push_str(&indent.to_string_with_newline(context.config));
2094 if let ast::FunctionRetTy::Ty(..) = fd.output {
2095 let ret_should_indent = match context.config.indent_style() {
2096 // If our args are block layout then we surely must have space.
2097 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
2098 _ if args_last_line_contains_comment => false,
2099 _ if result.contains('\n') || multi_line_ret_str => true,
2101 // If the return type would push over the max width, then put the return type on
2102 // a new line. With the +1 for the signature length an additional space between
2103 // the closing parenthesis of the argument and the arrow '->' is considered.
2104 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
2106 // If there is no where clause, take into account the space after the return type
2108 if where_clause.predicates.is_empty() {
2112 sig_length > context.config.max_width()
2115 let ret_indent = if ret_should_indent {
2116 let indent = if arg_str.is_empty() {
2117 // Aligning with non-existent args looks silly.
2118 force_new_line_for_brace = true;
2121 // FIXME: we might want to check that using the arg indent
2122 // doesn't blow our budget, and if it does, then fallback to
2123 // the where clause indent.
2127 result.push_str(&indent.to_string_with_newline(context.config));
2131 Indent::new(indent.block_indent, last_line_width(&result))
2134 if multi_line_ret_str || ret_should_indent {
2135 // Now that we know the proper indent and width, we need to
2136 // re-layout the return type.
2139 .rewrite(context, Shape::indented(ret_indent, context.config))?;
2140 result.push_str(&ret_str);
2142 result.push_str(&ret_str);
2145 // Comment between return type and the end of the decl.
2146 let snippet_lo = fd.output.span().hi();
2147 if where_clause.predicates.is_empty() {
2148 let snippet_hi = span.hi();
2149 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2150 // Try to preserve the layout of the original snippet.
2151 let original_starts_with_newline = snippet
2153 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2154 let original_ends_with_newline = snippet
2155 .rfind(|c| c != ' ')
2156 .map_or(false, |i| snippet[i..].ends_with('\n'));
2157 let snippet = snippet.trim();
2158 if !snippet.is_empty() {
2159 result.push(if original_starts_with_newline {
2164 result.push_str(snippet);
2165 if original_ends_with_newline {
2166 force_new_line_for_brace = true;
2172 let pos_before_where = match fd.output {
2173 ast::FunctionRetTy::Default(..) => args_span.hi(),
2174 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2177 let is_args_multi_lined = arg_str.contains('\n');
2179 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2180 let where_clause_str = rewrite_where_clause(
2183 context.config.brace_style(),
2184 Shape::indented(indent, context.config),
2190 is_args_multi_lined,
2192 // If there are neither where clause nor return type, we may be missing comments between
2194 if where_clause_str.is_empty() {
2195 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2196 match recover_missing_comment_in_span(
2197 mk_sp(args_span.hi(), ret_span.hi()),
2200 last_line_width(&result),
2202 Some(ref missing_comment) if !missing_comment.is_empty() => {
2203 result.push_str(missing_comment);
2204 force_new_line_for_brace = true;
2211 result.push_str(&where_clause_str);
2213 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2214 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2215 Some((result, force_new_line_for_brace))
2218 #[derive(Copy, Clone)]
2219 struct WhereClauseOption {
2220 suppress_comma: bool, // Force no trailing comma
2221 snuggle: bool, // Do not insert newline before `where`
2222 compress_where: bool, // Try single line where clause instead of vertical layout
2225 impl WhereClauseOption {
2226 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2230 compress_where: false,
2234 pub fn snuggled(current: &str) -> WhereClauseOption {
2236 suppress_comma: false,
2237 snuggle: last_line_width(current) == 1,
2238 compress_where: false,
2242 pub fn suppress_comma(&mut self) {
2243 self.suppress_comma = true
2246 pub fn compress_where(&mut self) {
2247 self.compress_where = true
2250 pub fn snuggle(&mut self) {
2256 context: &RewriteContext,
2258 explicit_self: Option<&ast::ExplicitSelf>,
2259 one_line_budget: usize,
2260 multi_line_budget: usize,
2265 generics_str_contains_newline: bool,
2266 ) -> Option<String> {
2267 let mut arg_item_strs = args
2270 arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent))
2271 .unwrap_or_else(|| context.snippet(arg.span()).to_owned())
2273 .collect::<Vec<_>>();
2275 // Account for sugary self.
2276 // FIXME: the comment for the self argument is dropped. This is blocked
2277 // on rust issue #27522.
2278 let min_args = explicit_self
2279 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2280 .map_or(1, |self_str| {
2281 arg_item_strs[0] = self_str;
2285 // Comments between args.
2286 let mut arg_items = Vec::new();
2288 arg_items.push(ListItem::from_str(""));
2291 // FIXME(#21): if there are no args, there might still be a comment, but
2292 // without spans for the comment or parens, there is no chance of
2293 // getting it right. You also don't get to put a comment on self, unless
2295 if args.len() >= min_args || variadic {
2296 let comment_span_start = if min_args == 2 {
2297 let second_arg_start = if arg_has_pattern(&args[1]) {
2298 args[1].pat.span.lo()
2300 args[1].ty.span.lo()
2302 let reduced_span = mk_sp(span.lo(), second_arg_start);
2304 context.snippet_provider.span_after_last(reduced_span, ",")
2309 enum ArgumentKind<'a> {
2310 Regular(&'a ast::Arg),
2314 let variadic_arg = if variadic {
2315 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2316 let variadic_start =
2317 context.snippet_provider.span_after(variadic_span, "...") - BytePos(3);
2318 Some(ArgumentKind::Variadic(variadic_start))
2323 let more_items = itemize_list(
2324 context.snippet_provider,
2325 args[min_args - 1..]
2327 .map(ArgumentKind::Regular)
2328 .chain(variadic_arg),
2332 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2333 ArgumentKind::Variadic(start) => start,
2336 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2337 ArgumentKind::Variadic(start) => start + BytePos(3),
2340 ArgumentKind::Regular(..) => None,
2341 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2348 arg_items.extend(more_items);
2351 let fits_in_one_line = !generics_str_contains_newline
2352 && (arg_items.is_empty()
2353 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2355 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2356 item.item = Some(arg);
2359 let last_line_ends_with_comment = arg_items
2362 .and_then(|item| item.post_comment.as_ref())
2363 .map_or(false, |s| s.trim().starts_with("//"));
2365 let (indent, trailing_comma) = match context.config.indent_style() {
2366 IndentStyle::Block if fits_in_one_line => {
2367 (indent.block_indent(context.config), SeparatorTactic::Never)
2369 IndentStyle::Block => (
2370 indent.block_indent(context.config),
2371 context.config.trailing_comma(),
2373 IndentStyle::Visual if last_line_ends_with_comment => {
2374 (arg_indent, context.config.trailing_comma())
2376 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2379 let tactic = definitive_tactic(
2381 context.config.fn_args_density().to_list_tactic(),
2385 let budget = match tactic {
2386 DefinitiveListTactic::Horizontal => one_line_budget,
2387 _ => multi_line_budget,
2390 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2392 let trailing_separator = if variadic {
2393 SeparatorTactic::Never
2397 let fmt = ListFormatting::new(Shape::legacy(budget, indent), context.config)
2399 .trailing_separator(trailing_separator)
2400 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2401 .preserve_newline(true);
2402 write_list(&arg_items, &fmt)
2405 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2406 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2407 ident != symbol::keywords::Invalid.ident()
2413 fn compute_budgets_for_args(
2414 context: &RewriteContext,
2418 newline_brace: bool,
2420 force_vertical_layout: bool,
2421 ) -> Option<((usize, usize, Indent))> {
2423 "compute_budgets_for_args {} {:?}, {}, {}",
2429 // Try keeping everything on the same line.
2430 if !result.contains('\n') && !force_vertical_layout {
2431 // 2 = `()`, 3 = `() `, space is before ret_string.
2432 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2433 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2443 let one_line_budget = context.budget(used_space);
2445 if one_line_budget > 0 {
2447 let (indent, multi_line_budget) = match context.config.indent_style() {
2448 IndentStyle::Block => {
2449 let indent = indent.block_indent(context.config);
2450 (indent, context.budget(indent.width() + 1))
2452 IndentStyle::Visual => {
2453 let indent = indent + result.len() + 1;
2454 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2455 (indent, context.budget(multi_line_overhead))
2459 return Some((one_line_budget, multi_line_budget, indent));
2463 // Didn't work. we must force vertical layout and put args on a newline.
2464 let new_indent = indent.block_indent(context.config);
2465 let used_space = match context.config.indent_style() {
2467 IndentStyle::Block => new_indent.width() + 1,
2468 // Account for `)` and possibly ` {`.
2469 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2471 Some((0, context.budget(used_space), new_indent))
2474 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2475 let predicate_count = where_clause.predicates.len();
2477 if config.where_single_line() && predicate_count == 1 {
2480 let brace_style = config.brace_style();
2482 brace_style == BraceStyle::AlwaysNextLine
2483 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2486 fn rewrite_generics(
2487 context: &RewriteContext,
2489 generics: &ast::Generics,
2491 ) -> Option<String> {
2492 // FIXME: convert bounds to where clauses where they get too big or if
2493 // there is a where clause at all.
2495 if generics.params.is_empty() {
2496 return Some(ident.to_owned());
2499 let params = &generics.params.iter().map(|e| &*e).collect::<Vec<_>>();
2500 overflow::rewrite_with_angle_brackets(context, ident, params, shape, generics.span)
2503 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2504 match config.indent_style() {
2505 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2506 IndentStyle::Block => {
2510 .block_indent(config.tab_spaces())
2511 .with_max_width(config)
2517 fn rewrite_where_clause_rfc_style(
2518 context: &RewriteContext,
2519 where_clause: &ast::WhereClause,
2522 span_end: Option<BytePos>,
2523 span_end_before_where: BytePos,
2524 where_clause_option: WhereClauseOption,
2525 is_args_multi_line: bool,
2526 ) -> Option<String> {
2527 let block_shape = shape.block().with_max_width(context.config);
2529 let (span_before, span_after) =
2530 missing_span_before_after_where(span_end_before_where, where_clause);
2531 let (comment_before, comment_after) =
2532 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2534 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2537 block_shape.indent.to_string_with_newline(context.config)
2540 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2542 let clause_shape = clause_shape.sub_width(1)?;
2543 // each clause on one line, trailing comma (except if suppress_comma)
2544 let span_start = where_clause.predicates[0].span().lo();
2545 // If we don't have the start of the next span, then use the end of the
2546 // predicates, but that means we miss comments.
2547 let len = where_clause.predicates.len();
2548 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2549 let span_end = span_end.unwrap_or(end_of_preds);
2550 let items = itemize_list(
2551 context.snippet_provider,
2552 where_clause.predicates.iter(),
2555 |pred| pred.span().lo(),
2556 |pred| pred.span().hi(),
2557 |pred| pred.rewrite(context, clause_shape),
2562 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2563 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2564 SeparatorTactic::Never
2566 context.config.trailing_comma()
2569 // shape should be vertical only and only if we have `where_single_line` option enabled
2570 // and the number of items of the where clause is equal to 1
2571 let shape_tactic = if where_single_line {
2572 DefinitiveListTactic::Horizontal
2574 DefinitiveListTactic::Vertical
2577 let fmt = ListFormatting::new(clause_shape, context.config)
2578 .tactic(shape_tactic)
2579 .trailing_separator(comma_tactic)
2580 .preserve_newline(true);
2581 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2583 let comment_separator = |comment: &str, shape: Shape| {
2584 if comment.is_empty() {
2587 shape.indent.to_string_with_newline(context.config)
2590 let newline_before_where = comment_separator(&comment_before, shape);
2591 let newline_after_where = comment_separator(&comment_after, clause_shape);
2594 let clause_sep = if where_clause_option.compress_where
2595 && comment_before.is_empty()
2596 && comment_after.is_empty()
2597 && !preds_str.contains('\n')
2598 && 6 + preds_str.len() <= shape.width
2599 || where_single_line
2603 clause_shape.indent.to_string_with_newline(context.config)
2606 "{}{}{}where{}{}{}{}",
2609 newline_before_where,
2610 newline_after_where,
2617 fn rewrite_where_clause(
2618 context: &RewriteContext,
2619 where_clause: &ast::WhereClause,
2620 brace_style: BraceStyle,
2624 span_end: Option<BytePos>,
2625 span_end_before_where: BytePos,
2626 where_clause_option: WhereClauseOption,
2627 is_args_multi_line: bool,
2628 ) -> Option<String> {
2629 if where_clause.predicates.is_empty() {
2630 return Some(String::new());
2633 if context.config.indent_style() == IndentStyle::Block {
2634 return rewrite_where_clause_rfc_style(
2640 span_end_before_where,
2641 where_clause_option,
2646 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2648 let offset = match context.config.indent_style() {
2649 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2650 // 6 = "where ".len()
2651 IndentStyle::Visual => shape.indent + extra_indent + 6,
2653 // FIXME: if indent_style != Visual, then the budgets below might
2654 // be out by a char or two.
2656 let budget = context.config.max_width() - offset.width();
2657 let span_start = where_clause.predicates[0].span().lo();
2658 // If we don't have the start of the next span, then use the end of the
2659 // predicates, but that means we miss comments.
2660 let len = where_clause.predicates.len();
2661 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2662 let span_end = span_end.unwrap_or(end_of_preds);
2663 let items = itemize_list(
2664 context.snippet_provider,
2665 where_clause.predicates.iter(),
2668 |pred| pred.span().lo(),
2669 |pred| pred.span().hi(),
2670 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2675 let item_vec = items.collect::<Vec<_>>();
2676 // FIXME: we don't need to collect here
2677 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2679 let mut comma_tactic = context.config.trailing_comma();
2680 // Kind of a hack because we don't usually have trailing commas in where clauses.
2681 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2682 comma_tactic = SeparatorTactic::Never;
2685 let fmt = ListFormatting::new(Shape::legacy(budget, offset), context.config)
2687 .trailing_separator(comma_tactic)
2688 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2689 .preserve_newline(true);
2690 let preds_str = write_list(&item_vec, &fmt)?;
2692 let end_length = if terminator == "{" {
2693 // If the brace is on the next line we don't need to count it otherwise it needs two
2696 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2697 BraceStyle::PreferSameLine => 2,
2699 } else if terminator == "=" {
2704 if density == Density::Tall
2705 || preds_str.contains('\n')
2706 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2710 (shape.indent + extra_indent).to_string(context.config),
2714 Some(format!(" where {}", preds_str))
2718 fn missing_span_before_after_where(
2719 before_item_span_end: BytePos,
2720 where_clause: &ast::WhereClause,
2722 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2724 let pos_after_where = where_clause.span.lo() + BytePos(5);
2725 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2726 (missing_span_before, missing_span_after)
2729 fn rewrite_comments_before_after_where(
2730 context: &RewriteContext,
2731 span_before_where: Span,
2732 span_after_where: Span,
2734 ) -> Option<(String, String)> {
2735 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2736 let after_comment = rewrite_missing_comment(
2738 shape.block_indent(context.config.tab_spaces()),
2741 Some((before_comment, after_comment))
2745 context: &RewriteContext,
2748 vis: &ast::Visibility,
2752 format_visibility(context, vis),
2754 rewrite_ident(context, ident)
2758 #[derive(PartialEq, Eq, Clone, Copy)]
2766 context: &RewriteContext,
2767 generics: &ast::Generics,
2768 brace_style: BraceStyle,
2769 brace_pos: BracePos,
2773 ) -> Option<String> {
2774 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2775 let mut result = rewrite_generics(context, "", generics, shape)?;
2777 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2778 let budget = context.budget(last_line_used_width(&result, offset.width()));
2779 let mut option = WhereClauseOption::snuggled(&result);
2780 if brace_pos == BracePos::None {
2781 option.suppress_comma = true;
2783 // If the generics are not parameterized then generics.span.hi() == 0,
2784 // so we use span.lo(), which is the position after `struct Foo`.
2785 let span_end_before_where = if !generics.params.is_empty() {
2790 let where_clause_str = rewrite_where_clause(
2792 &generics.where_clause,
2794 Shape::legacy(budget, offset.block_only()),
2798 span_end_before_where,
2802 result.push_str(&where_clause_str);
2803 brace_pos == BracePos::ForceSameLine
2804 || brace_style == BraceStyle::PreferSameLine
2805 || (generics.where_clause.predicates.is_empty()
2806 && trimmed_last_line_width(&result) == 1)
2808 brace_pos == BracePos::ForceSameLine
2809 || trimmed_last_line_width(&result) == 1
2810 || brace_style != BraceStyle::AlwaysNextLine
2812 if brace_pos == BracePos::None {
2813 return Some(result);
2815 let total_used_width = last_line_used_width(&result, used_width);
2816 let remaining_budget = context.budget(total_used_width);
2817 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2818 // and hence we take the closer into account as well for one line budget.
2819 // We assume that the closer has the same length as the opener.
2820 let overhead = if brace_pos == BracePos::ForceSameLine {
2827 let forbid_same_line_brace = overhead > remaining_budget;
2828 if !forbid_same_line_brace && same_line_brace {
2832 result.push_str(&offset.block_only().to_string(context.config));
2839 impl Rewrite for ast::ForeignItem {
2840 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2841 let attrs_str = self.attrs.rewrite(context, shape)?;
2842 // Drop semicolon or it will be interpreted as comment.
2843 // FIXME: this may be a faulty span from libsyntax.
2844 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2846 let item_str = match self.node {
2847 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => rewrite_fn_base(
2851 &FnSig::new(fn_decl, generics, self.vis.clone()),
2856 .map(|(s, _)| format!("{};", s)),
2857 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2858 // FIXME(#21): we're dropping potential comments in between the
2859 // function keywords here.
2860 let vis = format_visibility(context, &self.vis);
2861 let mut_str = if is_mutable { "mut " } else { "" };
2862 let prefix = format!(
2866 rewrite_ident(context, self.ident)
2869 rewrite_assign_rhs(context, prefix, &**ty, shape.sub_width(1)?).map(|s| s + ";")
2871 ast::ForeignItemKind::Ty => {
2872 let vis = format_visibility(context, &self.vis);
2876 rewrite_ident(context, self.ident)
2879 ast::ForeignItemKind::Macro(ref mac) => {
2880 rewrite_macro(mac, None, context, shape, MacroPosition::Item)
2884 let missing_span = if self.attrs.is_empty() {
2885 mk_sp(self.span.lo(), self.span.lo())
2887 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2889 combine_strs_with_missing_comments(
2900 /// Rewrite an inline mod.
2901 pub fn rewrite_mod(context: &RewriteContext, item: &ast::Item) -> String {
2902 let mut result = String::with_capacity(32);
2903 result.push_str(&*format_visibility(context, &item.vis));
2904 result.push_str("mod ");
2905 result.push_str(rewrite_ident(context, item.ident));
2910 /// Rewrite `extern crate foo;` WITHOUT attributes.
2911 pub fn rewrite_extern_crate(context: &RewriteContext, item: &ast::Item) -> Option<String> {
2912 assert!(is_extern_crate(item));
2913 let new_str = context.snippet(item.span);
2914 Some(if contains_comment(new_str) {
2917 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
2918 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
2922 /// Returns true for `mod foo;`, false for `mod foo { .. }`.
2923 pub fn is_mod_decl(item: &ast::Item) -> bool {
2925 ast::ItemKind::Mod(ref m) => m.inner.hi() != item.span.hi(),
2930 pub fn is_use_item(item: &ast::Item) -> bool {
2932 ast::ItemKind::Use(_) => true,
2937 pub fn is_extern_crate(item: &ast::Item) -> bool {
2939 ast::ItemKind::ExternCrate(..) => true,