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 ty_shape = if pat_str.contains('\n') {
98 shape.with_max_width(context.config)
102 .offset_left(last_line_width(&result) + separator.len())?
106 let rewrite = ty.rewrite(context, ty_shape)?;
108 infix.push_str(separator);
109 infix.push_str(&rewrite);
112 if self.init.is_some() {
113 infix.push_str(" =");
119 result.push_str(&infix);
121 if let Some(ref ex) = self.init {
122 // 1 = trailing semicolon;
123 let nested_shape = shape.sub_width(1)?;
125 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
133 // FIXME convert to using rewrite style rather than visitor
134 // FIXME format modules in this style
137 keyword: &'static str,
138 abi: Cow<'static, str>,
139 vis: Option<&'a ast::Visibility>,
140 body: Vec<BodyElement<'a>>,
145 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
148 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
153 .map(|i| BodyElement::ForeignItem(i))
160 enum BodyElement<'a> {
161 // Stmt(&'a ast::Stmt),
162 // Field(&'a ast::Field),
163 // Variant(&'a ast::Variant),
164 // Item(&'a ast::Item),
165 ForeignItem(&'a ast::ForeignItem),
168 /// Represents a fn's signature.
169 pub struct FnSig<'a> {
170 decl: &'a ast::FnDecl,
171 generics: &'a ast::Generics,
173 is_async: ast::IsAsync,
174 constness: ast::Constness,
175 defaultness: ast::Defaultness,
176 unsafety: ast::Unsafety,
177 visibility: ast::Visibility,
182 decl: &'a ast::FnDecl,
183 generics: &'a ast::Generics,
184 vis: ast::Visibility,
190 is_async: ast::IsAsync::NotAsync,
191 constness: ast::Constness::NotConst,
192 defaultness: ast::Defaultness::Final,
193 unsafety: ast::Unsafety::Normal,
198 pub fn from_method_sig(
199 method_sig: &'a ast::MethodSig,
200 generics: &'a ast::Generics,
203 unsafety: method_sig.header.unsafety,
204 is_async: method_sig.header.asyncness,
205 constness: method_sig.header.constness.node,
206 defaultness: ast::Defaultness::Final,
207 abi: method_sig.header.abi,
208 decl: &*method_sig.decl,
210 visibility: DEFAULT_VISIBILITY,
215 fn_kind: &'a visit::FnKind,
216 generics: &'a ast::Generics,
217 decl: &'a ast::FnDecl,
218 defaultness: ast::Defaultness,
221 visit::FnKind::ItemFn(_, fn_header, visibility, _) => FnSig {
225 constness: fn_header.constness.node,
226 is_async: fn_header.asyncness,
228 unsafety: fn_header.unsafety,
229 visibility: visibility.clone(),
231 visit::FnKind::Method(_, method_sig, vis, _) => {
232 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
233 fn_sig.defaultness = defaultness;
234 if let Some(vis) = vis {
235 fn_sig.visibility = vis.clone();
243 fn to_str(&self, context: &RewriteContext) -> String {
244 let mut result = String::with_capacity(128);
245 // Vis defaultness constness unsafety abi.
246 result.push_str(&*format_visibility(context, &self.visibility));
247 result.push_str(format_defaultness(self.defaultness));
248 result.push_str(format_constness(self.constness));
249 result.push_str(format_unsafety(self.unsafety));
250 result.push_str(format_async(self.is_async));
251 result.push_str(&format_abi(
253 context.config.force_explicit_abi(),
260 impl<'a> FmtVisitor<'a> {
261 fn format_item(&mut self, item: &Item) {
262 self.buffer.push_str(&item.abi);
264 let snippet = self.snippet(item.span);
265 let brace_pos = snippet.find_uncommented("{").unwrap();
268 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
269 // FIXME: this skips comments between the extern keyword and the opening
271 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
272 self.block_indent = self.block_indent.block_indent(self.config);
274 if item.body.is_empty() {
275 self.format_missing_no_indent(item.span.hi() - BytePos(1));
276 self.block_indent = self.block_indent.block_unindent(self.config);
277 let indent_str = self.block_indent.to_string(self.config);
278 self.push_str(&indent_str);
280 for item in &item.body {
281 self.format_body_element(item);
284 self.block_indent = self.block_indent.block_unindent(self.config);
285 self.format_missing_with_indent(item.span.hi() - BytePos(1));
290 self.last_pos = item.span.hi();
293 fn format_body_element(&mut self, element: &BodyElement) {
295 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
299 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
300 let item = Item::from_foreign_mod(fm, span, self.config);
301 self.format_item(&item);
304 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
305 let rewrite = item.rewrite(&self.get_context(), self.shape());
306 self.push_rewrite(item.span(), rewrite);
307 self.last_pos = item.span.hi();
317 inner_attrs: Option<&[ast::Attribute]>,
318 ) -> Option<String> {
319 let context = self.get_context();
321 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
323 let (mut result, force_newline_brace) =
324 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
327 if self.config.brace_style() == BraceStyle::AlwaysNextLine
328 || force_newline_brace
329 || last_line_width(&result) + 2 > self.shape().width
331 newline_brace = true;
332 } else if !result.contains('\n') {
333 newline_brace = false;
336 // Prepare for the function body by possibly adding a newline and
338 // FIXME we'll miss anything between the end of the signature and the
339 // start of the body, but we need more spans from the compiler to solve
342 result.push_str(&indent.to_string_with_newline(self.config));
347 self.single_line_fn(&result, block, inner_attrs)
348 .or_else(|| Some(result))
351 pub fn rewrite_required_fn(
355 sig: &ast::MethodSig,
356 generics: &ast::Generics,
358 ) -> Option<String> {
359 // Drop semicolon or it will be interpreted as comment.
360 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
361 let context = self.get_context();
363 let (mut result, _) = rewrite_fn_base(
367 &FnSig::from_method_sig(sig, generics),
373 // Re-attach semicolon
383 inner_attrs: Option<&[ast::Attribute]>,
384 ) -> Option<String> {
385 if fn_str.contains('\n') || inner_attrs.map_or(false, |a| !a.is_empty()) {
389 let source_map = self.get_context().source_map;
391 if self.config.empty_item_single_line()
392 && is_empty_block(block, None, source_map)
393 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
395 return Some(format!("{}{{}}", fn_str));
398 if self.config.fn_single_line() && is_simple_block_stmt(block, None, source_map) {
400 if let Some(stmt) = block.stmts.first() {
401 match stmt_expr(stmt) {
403 let suffix = if semicolon_for_expr(&self.get_context(), e) {
409 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
411 .or_else(|| Some(self.snippet(e.span).to_owned()))
413 None => stmt.rewrite(&self.get_context(), self.shape()),
420 if let Some(res) = rewrite {
421 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
422 if !res.contains('\n') && width <= self.config.max_width() {
423 return Some(format!("{}{{ {} }}", fn_str, res));
431 pub fn visit_static(&mut self, static_parts: &StaticParts) {
432 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
433 self.push_rewrite(static_parts.span, rewrite);
436 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
437 let is_tuple = struct_parts.def.is_tuple();
438 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
439 .map(|s| if is_tuple { s + ";" } else { s });
440 self.push_rewrite(struct_parts.span, rewrite);
446 vis: &ast::Visibility,
447 enum_def: &ast::EnumDef,
448 generics: &ast::Generics,
451 let enum_header = format_header(&self.get_context(), "enum ", ident, vis);
452 self.push_str(&enum_header);
454 let enum_snippet = self.snippet(span);
455 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
456 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
457 let generics_str = format_generics(
460 self.config.brace_style(),
461 if enum_def.variants.is_empty() {
462 BracePos::ForceSameLine
467 // make a span that starts right after `enum Foo`
468 mk_sp(ident.span.hi(), body_start),
469 last_line_width(&enum_header),
472 self.push_str(&generics_str);
474 self.last_pos = body_start;
476 match self.format_variant_list(enum_def, body_start, span.hi()) {
477 Some(ref s) if enum_def.variants.is_empty() => self.push_str(s),
479 self.push_rewrite(mk_sp(body_start, span.hi()), rw);
480 self.block_indent = self.block_indent.block_unindent(self.config);
485 // Format the body of an enum definition
486 fn format_variant_list(
488 enum_def: &ast::EnumDef,
491 ) -> Option<String> {
492 if enum_def.variants.is_empty() {
493 let mut buffer = String::with_capacity(128);
495 let span = mk_sp(body_lo, body_hi - BytePos(1));
496 format_empty_struct_or_tuple(
506 let mut result = String::with_capacity(1024);
507 let original_offset = self.block_indent;
508 self.block_indent = self.block_indent.block_indent(self.config);
510 // If enum variants have discriminants, try to vertically align those,
511 // provided the discrims are not shifted too much to the right
512 let align_threshold: usize = self.config.enum_discrim_align_threshold();
513 let discr_ident_lens: Vec<usize> = enum_def
516 .filter(|var| var.node.disr_expr.is_some())
517 .map(|var| rewrite_ident(&self.get_context(), var.node.ident).len())
519 // cut the list at the point of longest discrim shorter than the threshold
520 // All of the discrims under the threshold will get padded, and all above - left as is.
521 let pad_discrim_ident_to = *discr_ident_lens
523 .filter(|&l| *l <= align_threshold)
527 let itemize_list_with = |one_line_width: usize| {
529 self.snippet_provider,
530 enum_def.variants.iter(),
534 if !f.node.attrs.is_empty() {
535 f.node.attrs[0].span.lo()
541 |f| self.format_variant(f, one_line_width, pad_discrim_ident_to),
548 let mut items: Vec<_> =
549 itemize_list_with(self.config.width_heuristics().struct_variant_width);
550 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
551 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
552 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
553 if has_multiline_variant && has_single_line_variant {
554 items = itemize_list_with(0);
557 let shape = self.shape().sub_width(2)?;
558 let fmt = ListFormatting::new(shape, self.config)
559 .trailing_separator(self.config.trailing_comma())
560 .preserve_newline(true);
562 let list = write_list(&items, &fmt)?;
563 result.push_str(&list);
564 result.push_str(&original_offset.to_string_with_newline(self.config));
569 // Variant of an enum.
572 field: &ast::Variant,
573 one_line_width: usize,
574 pad_discrim_ident_to: usize,
575 ) -> Option<String> {
576 if contains_skip(&field.node.attrs) {
577 let lo = field.node.attrs[0].span.lo();
578 let span = mk_sp(lo, field.span.hi());
579 return Some(self.snippet(span).to_owned());
582 let context = self.get_context();
584 let shape = self.shape().sub_width(1)?;
585 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
590 .map_or(field.span.lo(), |attr| attr.span.hi());
591 let span = mk_sp(lo, field.span.lo());
593 let variant_body = match field.node.data {
594 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
596 &StructParts::from_variant(field),
598 Some(one_line_width),
600 ast::VariantData::Unit(..) => {
601 if let Some(ref expr) = field.node.disr_expr {
604 rewrite_ident(&context, field.node.ident),
607 rewrite_assign_rhs(&context, lhs, &*expr.value, shape)?
609 rewrite_ident(&context, field.node.ident).to_owned()
614 combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
617 fn visit_impl_items(&mut self, items: &[ast::ImplItem]) {
618 if self.get_context().config.reorder_impl_items() {
619 // Create visitor for each items, then reorder them.
620 let mut buffer = vec![];
622 self.visit_impl_item(item);
623 buffer.push((self.buffer.clone(), item.clone()));
626 // type -> existential -> const -> macro -> method
627 use ast::ImplItemKind::*;
628 fn need_empty_line(a: &ast::ImplItemKind, b: &ast::ImplItemKind) -> bool {
631 | (Const(..), Const(..))
632 | (Existential(..), Existential(..)) => false,
637 buffer.sort_by(|(_, a), (_, b)| match (&a.node, &b.node) {
639 | (Const(..), Const(..))
640 | (Macro(..), Macro(..))
641 | (Existential(..), Existential(..)) => a.ident.as_str().cmp(&b.ident.as_str()),
642 (Method(..), Method(..)) => a.span.lo().cmp(&b.span.lo()),
643 (Type(..), _) => Ordering::Less,
644 (_, Type(..)) => Ordering::Greater,
645 (Existential(..), _) => Ordering::Less,
646 (_, Existential(..)) => Ordering::Greater,
647 (Const(..), _) => Ordering::Less,
648 (_, Const(..)) => Ordering::Greater,
649 (Macro(..), _) => Ordering::Less,
650 (_, Macro(..)) => Ordering::Greater,
652 let mut prev_kind = None;
653 for (buf, item) in buffer {
654 // Make sure that there are at least a single empty line between
655 // different impl items.
658 .map_or(false, |prev_kind| need_empty_line(prev_kind, &item.node))
662 let indent_str = self.block_indent.to_string_with_newline(self.config);
663 self.push_str(&indent_str);
664 self.push_str(buf.trim());
665 prev_kind = Some(item.node.clone());
669 self.visit_impl_item(item);
676 context: &RewriteContext,
679 where_span_end: Option<BytePos>,
680 ) -> Option<String> {
681 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
682 let mut result = String::with_capacity(128);
683 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
684 let sep = offset.to_string_with_newline(context.config);
685 result.push_str(&ref_and_type);
687 let where_budget = if result.contains('\n') {
688 context.config.max_width()
690 context.budget(last_line_width(&result))
693 let mut option = WhereClauseOption::snuggled(&ref_and_type);
694 let snippet = context.snippet(item.span);
695 let open_pos = snippet.find_uncommented("{")? + 1;
696 if !contains_comment(&snippet[open_pos..])
698 && generics.where_clause.predicates.len() == 1
699 && !result.contains('\n')
701 option.suppress_comma();
703 option.compress_where();
706 let where_clause_str = rewrite_where_clause(
708 &generics.where_clause,
709 context.config.brace_style(),
710 Shape::legacy(where_budget, offset.block_only()),
719 // If there is no where clause, we may have missing comments between the trait name and
720 // the opening brace.
721 if generics.where_clause.predicates.is_empty() {
722 if let Some(hi) = where_span_end {
723 match recover_missing_comment_in_span(
724 mk_sp(self_ty.span.hi(), hi),
725 Shape::indented(offset, context.config),
727 last_line_width(&result),
729 Some(ref missing_comment) if !missing_comment.is_empty() => {
730 result.push_str(missing_comment);
737 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
738 result.push_str(&where_clause_str);
739 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
740 // if the where_clause contains extra comments AND
741 // there is only one where clause predicate
742 // recover the suppressed comma in single line where_clause formatting
743 if generics.where_clause.predicates.len() == 1 {
744 result.push_str(",");
746 result.push_str(&format!("{}{{{}}}", &sep, &sep));
748 result.push_str(" {}");
753 result.push_str(&where_clause_str);
755 let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
756 match context.config.brace_style() {
757 _ if need_newline => result.push_str(&sep),
758 BraceStyle::AlwaysNextLine => result.push_str(&sep),
759 BraceStyle::PreferSameLine => result.push(' '),
760 BraceStyle::SameLineWhere => {
761 if !where_clause_str.is_empty() {
762 result.push_str(&sep);
771 let snippet = context.snippet(item.span);
772 let open_pos = snippet.find_uncommented("{")? + 1;
774 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
775 let mut visitor = FmtVisitor::from_context(context);
776 let item_indent = offset.block_only().block_indent(context.config);
777 visitor.block_indent = item_indent;
778 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
780 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
781 visitor.visit_impl_items(items);
783 visitor.format_missing(item.span.hi() - BytePos(1));
785 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
786 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
788 result.push_str(&inner_indent_str);
789 result.push_str(visitor.buffer.trim());
790 result.push_str(&outer_indent_str);
791 } else if need_newline || !context.config.empty_item_single_line() {
792 result.push_str(&sep);
803 fn is_impl_single_line(
804 context: &RewriteContext,
805 items: &[ast::ImplItem],
807 where_clause_str: &str,
810 let snippet = context.snippet(item.span);
811 let open_pos = snippet.find_uncommented("{")? + 1;
814 context.config.empty_item_single_line()
816 && !result.contains('\n')
817 && result.len() + where_clause_str.len() <= context.config.max_width()
818 && !contains_comment(&snippet[open_pos..]),
822 fn format_impl_ref_and_type(
823 context: &RewriteContext,
826 ) -> Option<String> {
827 if let ast::ItemKind::Impl(
837 let mut result = String::with_capacity(128);
839 result.push_str(&format_visibility(context, &item.vis));
840 result.push_str(format_defaultness(defaultness));
841 result.push_str(format_unsafety(unsafety));
843 let shape = generics_shape_from_config(
845 Shape::indented(offset + last_line_width(&result), context.config),
848 let generics_str = rewrite_generics(context, "impl", generics, shape)?;
849 result.push_str(&generics_str);
851 let polarity_str = if polarity == ast::ImplPolarity::Negative {
857 if let Some(ref trait_ref) = *trait_ref {
858 let result_len = last_line_width(&result);
859 result.push_str(&rewrite_trait_ref(
868 // Try to put the self type in a single line.
870 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
871 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
872 // If there is no where clause adapt budget for type formatting to take space and curly
873 // brace into account.
874 match context.config.brace_style() {
875 BraceStyle::AlwaysNextLine => 0,
881 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
882 // 1 = space before the type.
883 let budget = context.budget(used_space + 1);
884 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
885 if !self_ty_str.contains('\n') {
886 if trait_ref.is_some() {
887 result.push_str(" for ");
891 result.push_str(&self_ty_str);
896 // Couldn't fit the self type on a single line, put it on a new line.
898 // Add indentation of one additional tab.
899 let new_line_offset = offset.block_indent(context.config);
900 result.push_str(&new_line_offset.to_string(context.config));
901 if trait_ref.is_some() {
902 result.push_str("for ");
904 let budget = context.budget(last_line_width(&result));
905 let type_offset = match context.config.indent_style() {
906 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
907 IndentStyle::Block => new_line_offset,
909 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
916 fn rewrite_trait_ref(
917 context: &RewriteContext,
918 trait_ref: &ast::TraitRef,
922 ) -> Option<String> {
923 // 1 = space between generics and trait_ref
924 let used_space = 1 + polarity_str.len() + result_len;
925 let shape = Shape::indented(offset + used_space, context.config);
926 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
927 if !trait_ref_str.contains('\n') {
928 return Some(format!(" {}{}", polarity_str, &trait_ref_str));
931 // We could not make enough space for trait_ref, so put it on new line.
932 let offset = offset.block_indent(context.config);
933 let shape = Shape::indented(offset, context.config);
934 let trait_ref_str = trait_ref.rewrite(context, shape)?;
937 &offset.to_string_with_newline(context.config),
943 pub struct StructParts<'a> {
946 vis: &'a ast::Visibility,
947 def: &'a ast::VariantData,
948 generics: Option<&'a ast::Generics>,
952 impl<'a> StructParts<'a> {
953 fn format_header(&self, context: &RewriteContext) -> String {
954 format_header(context, self.prefix, self.ident, self.vis)
957 fn from_variant(variant: &'a ast::Variant) -> Self {
960 ident: variant.node.ident,
961 vis: &DEFAULT_VISIBILITY,
962 def: &variant.node.data,
968 pub fn from_item(item: &'a ast::Item) -> Self {
969 let (prefix, def, generics) = match item.node {
970 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
971 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
979 generics: Some(generics),
986 context: &RewriteContext,
987 struct_parts: &StructParts,
989 one_line_width: Option<usize>,
990 ) -> Option<String> {
991 match *struct_parts.def {
992 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
993 ast::VariantData::Tuple(ref fields, _) => {
994 format_tuple_struct(context, struct_parts, fields, offset)
996 ast::VariantData::Struct(ref fields, _) => {
997 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
1002 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
1003 if let ast::ItemKind::Trait(
1011 let mut result = String::with_capacity(128);
1012 let header = format!(
1014 format_visibility(context, &item.vis),
1015 format_unsafety(unsafety),
1016 format_auto(is_auto),
1018 result.push_str(&header);
1020 let body_lo = context.snippet_provider.span_after(item.span, "{");
1022 let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
1024 rewrite_generics(context, rewrite_ident(context, item.ident), generics, shape)?;
1025 result.push_str(&generics_str);
1027 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
1028 if !generic_bounds.is_empty() {
1029 let ident_hi = context
1031 .span_after(item.span, &item.ident.as_str());
1032 let bound_hi = generic_bounds.last().unwrap().span().hi();
1033 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
1034 if contains_comment(snippet) {
1038 result = rewrite_assign_rhs_with(
1043 RhsTactics::ForceNextLineWithoutIndent,
1047 // Rewrite where clause.
1048 if !generics.where_clause.predicates.is_empty() {
1049 let where_density = if context.config.indent_style() == IndentStyle::Block {
1055 let where_budget = context.budget(last_line_width(&result));
1056 let pos_before_where = if generic_bounds.is_empty() {
1057 generics.where_clause.span.lo()
1059 generic_bounds[generic_bounds.len() - 1].span().hi()
1061 let option = WhereClauseOption::snuggled(&generics_str);
1062 let where_clause_str = rewrite_where_clause(
1064 &generics.where_clause,
1065 context.config.brace_style(),
1066 Shape::legacy(where_budget, offset.block_only()),
1074 // If the where clause cannot fit on the same line,
1075 // put the where clause on a new line
1076 if !where_clause_str.contains('\n')
1077 && last_line_width(&result) + where_clause_str.len() + offset.width()
1078 > context.config.comment_width()
1080 let width = offset.block_indent + context.config.tab_spaces() - 1;
1081 let where_indent = Indent::new(0, width);
1082 result.push_str(&where_indent.to_string_with_newline(context.config));
1084 result.push_str(&where_clause_str);
1086 let item_snippet = context.snippet(item.span);
1087 if let Some(lo) = item_snippet.find('/') {
1089 let comment_hi = body_lo - BytePos(1);
1090 let comment_lo = item.span.lo() + BytePos(lo as u32);
1091 if comment_lo < comment_hi {
1092 match recover_missing_comment_in_span(
1093 mk_sp(comment_lo, comment_hi),
1094 Shape::indented(offset, context.config),
1096 last_line_width(&result),
1098 Some(ref missing_comment) if !missing_comment.is_empty() => {
1099 result.push_str(missing_comment);
1107 match context.config.brace_style() {
1108 _ if last_line_contains_single_line_comment(&result)
1109 || last_line_width(&result) + 2 > context.budget(offset.width()) =>
1111 result.push_str(&offset.to_string_with_newline(context.config));
1113 BraceStyle::AlwaysNextLine => {
1114 result.push_str(&offset.to_string_with_newline(context.config));
1116 BraceStyle::PreferSameLine => result.push(' '),
1117 BraceStyle::SameLineWhere => {
1118 if result.contains('\n')
1119 || (!generics.where_clause.predicates.is_empty() && !trait_items.is_empty())
1121 result.push_str(&offset.to_string_with_newline(context.config));
1129 let snippet = context.snippet(item.span);
1130 let open_pos = snippet.find_uncommented("{")? + 1;
1131 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
1133 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1134 let mut visitor = FmtVisitor::from_context(context);
1135 visitor.block_indent = offset.block_only().block_indent(context.config);
1136 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1138 for item in trait_items {
1139 visitor.visit_trait_item(item);
1142 visitor.format_missing(item.span.hi() - BytePos(1));
1144 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
1146 result.push_str(&inner_indent_str);
1147 result.push_str(visitor.buffer.trim());
1148 result.push_str(&outer_indent_str);
1149 } else if result.contains('\n') {
1150 result.push_str(&outer_indent_str);
1160 pub fn format_trait_alias(
1161 context: &RewriteContext,
1163 generics: &ast::Generics,
1164 generic_bounds: &ast::GenericBounds,
1166 ) -> Option<String> {
1167 let alias = rewrite_ident(context, ident);
1168 // 6 = "trait ", 2 = " ="
1169 let g_shape = shape.offset_left(6)?.sub_width(2)?;
1170 let generics_str = rewrite_generics(context, &alias, generics, g_shape)?;
1171 let lhs = format!("trait {} =", generics_str);
1173 rewrite_assign_rhs(context, lhs, generic_bounds, shape.sub_width(1)?).map(|s| s + ";")
1176 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1177 let header_str = format_header(context, p.prefix, p.ident, p.vis);
1178 let generics_str = if let Some(generics) = p.generics {
1179 let hi = if generics.where_clause.predicates.is_empty() {
1182 generics.where_clause.span.hi()
1187 context.config.brace_style(),
1190 // make a span that starts right after `struct Foo`
1191 mk_sp(p.ident.span.hi(), hi),
1192 last_line_width(&header_str),
1197 Some(format!("{}{};", header_str, generics_str))
1200 pub fn format_struct_struct(
1201 context: &RewriteContext,
1202 struct_parts: &StructParts,
1203 fields: &[ast::StructField],
1205 one_line_width: Option<usize>,
1206 ) -> Option<String> {
1207 let mut result = String::with_capacity(1024);
1208 let span = struct_parts.span;
1210 let header_str = struct_parts.format_header(context);
1211 result.push_str(&header_str);
1213 let header_hi = struct_parts.ident.span.hi();
1214 let body_lo = context.snippet_provider.span_after(span, "{");
1216 let generics_str = match struct_parts.generics {
1217 Some(g) => format_generics(
1220 context.config.brace_style(),
1221 if fields.is_empty() {
1222 BracePos::ForceSameLine
1227 // make a span that starts right after `struct Foo`
1228 mk_sp(header_hi, body_lo),
1229 last_line_width(&result),
1232 // 3 = ` {}`, 2 = ` {`.
1233 let overhead = if fields.is_empty() { 3 } else { 2 };
1234 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1235 || context.config.max_width() < overhead + result.len()
1237 format!("\n{}{{", offset.block_only().to_string(context.config))
1244 let overhead = if fields.is_empty() { 1 } else { 0 };
1245 let total_width = result.len() + generics_str.len() + overhead;
1246 if !generics_str.is_empty()
1247 && !generics_str.contains('\n')
1248 && total_width > context.config.max_width()
1251 result.push_str(&offset.to_string(context.config));
1252 result.push_str(generics_str.trim_start());
1254 result.push_str(&generics_str);
1257 if fields.is_empty() {
1258 let inner_span = mk_sp(body_lo, span.hi() - BytePos(1));
1259 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "", "}");
1260 return Some(result);
1264 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1265 let one_line_budget =
1266 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1268 let items_str = rewrite_with_alignment(
1271 Shape::indented(offset.block_indent(context.config), context.config).sub_width(1)?,
1272 mk_sp(body_lo, span.hi()),
1276 if !items_str.contains('\n')
1277 && !result.contains('\n')
1278 && items_str.len() <= one_line_budget
1279 && !last_line_contains_single_line_comment(&items_str)
1281 Some(format!("{} {} }}", result, items_str))
1287 .block_indent(context.config)
1288 .to_string(context.config),
1290 offset.to_string(context.config)
1295 fn get_bytepos_after_visibility(vis: &ast::Visibility, default_span: Span) -> BytePos {
1297 ast::VisibilityKind::Crate(..) | ast::VisibilityKind::Restricted { .. } => vis.span.hi(),
1298 _ => default_span.lo(),
1302 // Format tuple or struct without any fields. We need to make sure that the comments
1303 // inside the delimiters are preserved.
1304 fn format_empty_struct_or_tuple(
1305 context: &RewriteContext,
1308 result: &mut String,
1312 // 3 = " {}" or "();"
1313 let used_width = last_line_used_width(&result, offset.width()) + 3;
1314 if used_width > context.config.max_width() {
1315 result.push_str(&offset.to_string_with_newline(context.config))
1317 result.push_str(opener);
1318 match rewrite_missing_comment(span, Shape::indented(offset, context.config), context) {
1319 Some(ref s) if s.is_empty() => (),
1321 if !is_single_line(s) || first_line_contains_single_line_comment(s) {
1322 let nested_indent_str = offset
1323 .block_indent(context.config)
1324 .to_string_with_newline(context.config);
1325 result.push_str(&nested_indent_str);
1328 if last_line_contains_single_line_comment(s) {
1329 result.push_str(&offset.to_string_with_newline(context.config));
1332 None => result.push_str(context.snippet(span)),
1334 result.push_str(closer);
1337 fn format_tuple_struct(
1338 context: &RewriteContext,
1339 struct_parts: &StructParts,
1340 fields: &[ast::StructField],
1342 ) -> Option<String> {
1343 let mut result = String::with_capacity(1024);
1344 let span = struct_parts.span;
1346 let header_str = struct_parts.format_header(context);
1347 result.push_str(&header_str);
1349 let body_lo = if fields.is_empty() {
1350 let lo = get_bytepos_after_visibility(struct_parts.vis, span);
1353 .span_after(mk_sp(lo, span.hi()), "(")
1357 let body_hi = if fields.is_empty() {
1360 .span_after(mk_sp(body_lo, span.hi()), ")")
1362 // This is a dirty hack to work around a missing `)` from the span of the last field.
1363 let last_arg_span = fields[fields.len() - 1].span;
1366 .opt_span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1367 .unwrap_or(last_arg_span.hi())
1370 let where_clause_str = match struct_parts.generics {
1372 let budget = context.budget(last_line_width(&header_str));
1373 let shape = Shape::legacy(budget, offset);
1374 let generics_str = rewrite_generics(context, "", generics, shape)?;
1375 result.push_str(&generics_str);
1377 let where_budget = context.budget(last_line_width(&result));
1378 let option = WhereClauseOption::new(true, false);
1379 rewrite_where_clause(
1381 &generics.where_clause,
1382 context.config.brace_style(),
1383 Shape::legacy(where_budget, offset.block_only()),
1384 Density::Compressed,
1392 None => "".to_owned(),
1395 if fields.is_empty() {
1396 let body_hi = context
1398 .span_before(mk_sp(body_lo, span.hi()), ")");
1399 let inner_span = mk_sp(body_lo, body_hi);
1400 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "(", ")");
1402 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1403 result = overflow::rewrite_with_parens(
1409 context.config.width_heuristics().fn_call_width,
1414 if !where_clause_str.is_empty()
1415 && !where_clause_str.contains('\n')
1416 && (result.contains('\n')
1417 || offset.block_indent + result.len() + where_clause_str.len() + 1
1418 > context.config.max_width())
1420 // We need to put the where clause on a new line, but we didn't
1421 // know that earlier, so the where clause will not be indented properly.
1424 &(offset.block_only() + (context.config.tab_spaces() - 1)).to_string(context.config),
1427 result.push_str(&where_clause_str);
1432 fn rewrite_type_prefix(
1433 context: &RewriteContext,
1437 generics: &ast::Generics,
1438 ) -> Option<String> {
1439 let mut result = String::with_capacity(128);
1440 result.push_str(prefix);
1441 let ident_str = rewrite_ident(context, ident);
1444 if generics.params.is_empty() {
1445 result.push_str(ident_str)
1447 let g_shape = Shape::indented(indent, context.config)
1448 .offset_left(result.len())?
1450 let generics_str = rewrite_generics(context, ident_str, generics, g_shape)?;
1451 result.push_str(&generics_str);
1454 let where_budget = context.budget(last_line_width(&result));
1455 let option = WhereClauseOption::snuggled(&result);
1456 let where_clause_str = rewrite_where_clause(
1458 &generics.where_clause,
1459 context.config.brace_style(),
1460 Shape::legacy(where_budget, indent),
1468 result.push_str(&where_clause_str);
1473 fn rewrite_type_item<R: Rewrite>(
1474 context: &RewriteContext,
1480 generics: &ast::Generics,
1481 vis: &ast::Visibility,
1482 ) -> Option<String> {
1483 let mut result = String::with_capacity(128);
1484 result.push_str(&rewrite_type_prefix(
1487 &format!("{}{} ", format_visibility(context, vis), prefix),
1492 if generics.where_clause.predicates.is_empty() {
1493 result.push_str(suffix);
1495 result.push_str(&indent.to_string_with_newline(context.config));
1496 result.push_str(suffix.trim_start());
1500 let rhs_shape = Shape::indented(indent, context.config).sub_width(1)?;
1501 rewrite_assign_rhs(context, result, rhs, rhs_shape).map(|s| s + ";")
1504 pub fn rewrite_type_alias(
1505 context: &RewriteContext,
1509 generics: &ast::Generics,
1510 vis: &ast::Visibility,
1511 ) -> Option<String> {
1512 rewrite_type_item(context, indent, "type", " =", ident, ty, generics, vis)
1515 pub fn rewrite_existential_type(
1516 context: &RewriteContext,
1519 generic_bounds: &ast::GenericBounds,
1520 generics: &ast::Generics,
1521 vis: &ast::Visibility,
1522 ) -> Option<String> {
1535 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1537 if config.space_before_colon() { " " } else { "" },
1538 if config.space_after_colon() { " " } else { "" },
1542 pub fn rewrite_struct_field_prefix(
1543 context: &RewriteContext,
1544 field: &ast::StructField,
1545 ) -> Option<String> {
1546 let vis = format_visibility(context, &field.vis);
1547 let type_annotation_spacing = type_annotation_spacing(context.config);
1548 Some(match field.ident {
1549 Some(name) => format!(
1552 rewrite_ident(context, name),
1553 type_annotation_spacing.0
1555 None => vis.to_string(),
1559 impl Rewrite for ast::StructField {
1560 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1561 rewrite_struct_field(context, self, shape, 0)
1565 pub fn rewrite_struct_field(
1566 context: &RewriteContext,
1567 field: &ast::StructField,
1569 lhs_max_width: usize,
1570 ) -> Option<String> {
1571 if contains_skip(&field.attrs) {
1572 return Some(context.snippet(field.span()).to_owned());
1575 let type_annotation_spacing = type_annotation_spacing(context.config);
1576 let prefix = rewrite_struct_field_prefix(context, field)?;
1578 let attrs_str = field.attrs.rewrite(context, shape)?;
1579 let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
1580 let missing_span = if field.attrs.is_empty() {
1581 mk_sp(field.span.lo(), field.span.lo())
1583 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1585 let mut spacing = String::from(if field.ident.is_some() {
1586 type_annotation_spacing.1
1590 // Try to put everything on a single line.
1591 let attr_prefix = combine_strs_with_missing_comments(
1599 let overhead = last_line_width(&attr_prefix);
1600 let lhs_offset = lhs_max_width.saturating_sub(overhead);
1601 for _ in 0..lhs_offset {
1604 // In this extreme case we will be missing a space between an attribute and a field.
1605 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1609 .offset_left(overhead + spacing.len())
1610 .and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
1611 if let Some(ref ty) = orig_ty {
1612 if !ty.contains('\n') {
1613 return Some(attr_prefix + &spacing + ty);
1617 let is_prefix_empty = prefix.is_empty();
1618 // We must use multiline. We are going to put attributes and a field on different lines.
1619 let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, shape)?;
1620 // Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
1621 let field_str = if is_prefix_empty {
1622 field_str.trim_start()
1626 combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
1629 pub struct StaticParts<'a> {
1631 vis: &'a ast::Visibility,
1634 mutability: ast::Mutability,
1635 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1636 defaultness: Option<ast::Defaultness>,
1640 impl<'a> StaticParts<'a> {
1641 pub fn from_item(item: &'a ast::Item) -> Self {
1642 let (prefix, ty, mutability, expr) = match item.node {
1643 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1644 ast::ItemKind::Const(ref ty, ref expr) => {
1645 ("const", ty, ast::Mutability::Immutable, expr)
1647 _ => unreachable!(),
1655 expr_opt: Some(expr),
1661 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1662 let (ty, expr_opt) = match ti.node {
1663 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1664 _ => unreachable!(),
1668 vis: &DEFAULT_VISIBILITY,
1671 mutability: ast::Mutability::Immutable,
1672 expr_opt: expr_opt.as_ref(),
1678 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1679 let (ty, expr) = match ii.node {
1680 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1681 _ => unreachable!(),
1688 mutability: ast::Mutability::Immutable,
1689 expr_opt: Some(expr),
1690 defaultness: Some(ii.defaultness),
1697 context: &RewriteContext,
1698 static_parts: &StaticParts,
1700 ) -> Option<String> {
1701 let colon = colon_spaces(
1702 context.config.space_before_colon(),
1703 context.config.space_after_colon(),
1705 let mut prefix = format!(
1707 format_visibility(context, static_parts.vis),
1708 static_parts.defaultness.map_or("", format_defaultness),
1709 static_parts.prefix,
1710 format_mutability(static_parts.mutability),
1716 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1717 let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
1718 Some(ty_str) => ty_str,
1720 if prefix.ends_with(' ') {
1723 let nested_indent = offset.block_indent(context.config);
1724 let nested_shape = Shape::indented(nested_indent, context.config);
1725 let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
1728 nested_indent.to_string_with_newline(context.config),
1734 if let Some(expr) = static_parts.expr_opt {
1735 let lhs = format!("{}{} =", prefix, ty_str);
1737 let remaining_width = context.budget(offset.block_indent + 1);
1742 Shape::legacy(remaining_width, offset.block_only()),
1744 .and_then(|res| recover_comment_removed(res, static_parts.span, context))
1745 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1747 Some(format!("{}{};", prefix, ty_str))
1751 pub fn rewrite_associated_type(
1753 ty_opt: Option<&ptr::P<ast::Ty>>,
1754 generics: &ast::Generics,
1755 generic_bounds_opt: Option<&ast::GenericBounds>,
1756 context: &RewriteContext,
1758 ) -> Option<String> {
1759 let ident_str = rewrite_ident(context, ident);
1761 let generics_shape = Shape::indented(indent, context.config).offset_left(5)?;
1762 let generics_str = rewrite_generics(context, ident_str, generics, generics_shape)?;
1763 let prefix = format!("type {}", generics_str);
1765 let type_bounds_str = if let Some(bounds) = generic_bounds_opt {
1766 if bounds.is_empty() {
1770 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1771 bounds.rewrite(context, shape).map(|s| format!(": {}", s))?
1777 if let Some(ty) = ty_opt {
1779 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1780 let lhs = format!("{}{} =", prefix, type_bounds_str);
1781 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1783 Some(format!("{}{};", prefix, type_bounds_str))
1787 pub fn rewrite_existential_impl_type(
1788 context: &RewriteContext,
1790 generics: &ast::Generics,
1791 generic_bounds: &ast::GenericBounds,
1793 ) -> Option<String> {
1794 rewrite_associated_type(ident, None, generics, Some(generic_bounds), context, indent)
1795 .map(|s| format!("existential {}", s))
1798 pub fn rewrite_associated_impl_type(
1800 defaultness: ast::Defaultness,
1801 ty_opt: Option<&ptr::P<ast::Ty>>,
1802 generics: &ast::Generics,
1803 context: &RewriteContext,
1805 ) -> Option<String> {
1806 let result = rewrite_associated_type(ident, ty_opt, generics, None, context, indent)?;
1809 ast::Defaultness::Default => Some(format!("default {}", result)),
1814 impl Rewrite for ast::FunctionRetTy {
1815 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1817 ast::FunctionRetTy::Default(_) => Some(String::new()),
1818 ast::FunctionRetTy::Ty(ref ty) => {
1819 let inner_width = shape.width.checked_sub(3)?;
1820 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1821 .map(|r| format!("-> {}", r))
1827 fn is_empty_infer(ty: &ast::Ty, pat_span: Span) -> bool {
1829 ast::TyKind::Infer => ty.span.hi() == pat_span.hi(),
1834 impl Rewrite for ast::Arg {
1835 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1836 if is_named_arg(self) {
1837 let mut result = self
1839 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1841 if !is_empty_infer(&*self.ty, self.pat.span) {
1842 if context.config.space_before_colon() {
1843 result.push_str(" ");
1845 result.push_str(":");
1846 if context.config.space_after_colon() {
1847 result.push_str(" ");
1849 let overhead = last_line_width(&result);
1850 let max_width = shape.width.checked_sub(overhead)?;
1853 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1854 result.push_str(&ty_str);
1859 self.ty.rewrite(context, shape)
1864 fn rewrite_explicit_self(
1865 explicit_self: &ast::ExplicitSelf,
1867 context: &RewriteContext,
1868 ) -> Option<String> {
1869 match explicit_self.node {
1870 ast::SelfKind::Region(lt, m) => {
1871 let mut_str = format_mutability(m);
1874 let lifetime_str = l.rewrite(
1876 Shape::legacy(context.config.max_width(), Indent::empty()),
1878 Some(format!("&{} {}self", lifetime_str, mut_str))
1880 None => Some(format!("&{}self", mut_str)),
1883 ast::SelfKind::Explicit(ref ty, _) => {
1884 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1886 let mutability = explicit_self_mutability(&args[0]);
1887 let type_str = ty.rewrite(
1889 Shape::legacy(context.config.max_width(), Indent::empty()),
1894 format_mutability(mutability),
1898 ast::SelfKind::Value(_) => {
1899 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1901 let mutability = explicit_self_mutability(&args[0]);
1903 Some(format!("{}self", format_mutability(mutability)))
1908 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1909 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1910 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1911 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1918 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1919 if is_named_arg(arg) {
1926 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1928 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1929 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1930 _ => arg.ty.span.hi(),
1934 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1935 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1936 ident != symbol::keywords::Invalid.ident()
1942 // Return type is (result, force_new_line_for_brace)
1944 context: &RewriteContext,
1949 newline_brace: bool,
1951 ) -> Option<(String, bool)> {
1952 let mut force_new_line_for_brace = false;
1954 let where_clause = &fn_sig.generics.where_clause;
1956 let mut result = String::with_capacity(1024);
1957 result.push_str(&fn_sig.to_str(context));
1960 result.push_str("fn ");
1963 let overhead = if has_body && !newline_brace {
1970 let used_width = last_line_used_width(&result, indent.width());
1971 let one_line_budget = context.budget(used_width + overhead);
1973 width: one_line_budget,
1977 let fd = fn_sig.decl;
1978 let generics_str = rewrite_generics(
1980 rewrite_ident(context, ident),
1984 result.push_str(&generics_str);
1986 let snuggle_angle_bracket = generics_str
1989 .map_or(false, |l| l.trim_start().len() == 1);
1991 // Note that the width and indent don't really matter, we'll re-layout the
1992 // return type later anyway.
1995 .rewrite(context, Shape::indented(indent, context.config))?;
1997 let multi_line_ret_str = ret_str.contains('\n');
1998 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
2001 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
2012 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
2013 one_line_budget, multi_line_budget, arg_indent
2017 // Check if vertical layout was forced.
2018 if one_line_budget == 0
2019 && !snuggle_angle_bracket
2020 && context.config.indent_style() == IndentStyle::Visual
2022 result.push_str(&arg_indent.to_string_with_newline(context.config));
2025 // Skip `pub(crate)`.
2026 let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
2027 // A conservative estimation, to goal is to be over all parens in generics
2028 let args_start = fn_sig
2033 .map_or(lo_after_visibility, |param| param.span().hi());
2034 let args_end = if fd.inputs.is_empty() {
2037 .span_after(mk_sp(args_start, span.hi()), ")")
2039 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
2040 context.snippet_provider.span_after(last_span, ")")
2042 let args_span = mk_sp(
2045 .span_after(mk_sp(args_start, span.hi()), "("),
2048 let arg_str = rewrite_args(
2051 fd.get_self().as_ref(),
2058 generics_str.contains('\n'),
2061 let put_args_in_block = match context.config.indent_style() {
2062 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
2064 } && !fd.inputs.is_empty();
2066 let mut args_last_line_contains_comment = false;
2067 if put_args_in_block {
2068 arg_indent = indent.block_indent(context.config);
2069 result.push_str(&arg_indent.to_string_with_newline(context.config));
2070 result.push_str(&arg_str);
2071 result.push_str(&indent.to_string_with_newline(context.config));
2074 result.push_str(&arg_str);
2075 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
2076 // Put the closing brace on the next line if it overflows the max width.
2078 let closing_paren_overflow_max_width =
2079 fd.inputs.is_empty() && used_width + 1 > context.config.max_width();
2080 // If the last line of args contains comment, we cannot put the closing paren
2081 // on the same line.
2082 args_last_line_contains_comment = arg_str
2085 .map_or(false, |last_line| last_line.contains("//"));
2086 if closing_paren_overflow_max_width || args_last_line_contains_comment {
2087 result.push_str(&indent.to_string_with_newline(context.config));
2093 if let ast::FunctionRetTy::Ty(..) = fd.output {
2094 let ret_should_indent = match context.config.indent_style() {
2095 // If our args are block layout then we surely must have space.
2096 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
2097 _ if args_last_line_contains_comment => false,
2098 _ if result.contains('\n') || multi_line_ret_str => true,
2100 // If the return type would push over the max width, then put the return type on
2101 // a new line. With the +1 for the signature length an additional space between
2102 // the closing parenthesis of the argument and the arrow '->' is considered.
2103 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
2105 // If there is no where clause, take into account the space after the return type
2107 if where_clause.predicates.is_empty() {
2111 sig_length > context.config.max_width()
2114 let ret_indent = if ret_should_indent {
2115 let indent = if arg_str.is_empty() {
2116 // Aligning with non-existent args looks silly.
2117 force_new_line_for_brace = true;
2120 // FIXME: we might want to check that using the arg indent
2121 // doesn't blow our budget, and if it does, then fallback to
2122 // the where clause indent.
2126 result.push_str(&indent.to_string_with_newline(context.config));
2130 Indent::new(indent.block_indent, last_line_width(&result))
2133 if multi_line_ret_str || ret_should_indent {
2134 // Now that we know the proper indent and width, we need to
2135 // re-layout the return type.
2138 .rewrite(context, Shape::indented(ret_indent, context.config))?;
2139 result.push_str(&ret_str);
2141 result.push_str(&ret_str);
2144 // Comment between return type and the end of the decl.
2145 let snippet_lo = fd.output.span().hi();
2146 if where_clause.predicates.is_empty() {
2147 let snippet_hi = span.hi();
2148 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2149 // Try to preserve the layout of the original snippet.
2150 let original_starts_with_newline = snippet
2152 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2153 let original_ends_with_newline = snippet
2154 .rfind(|c| c != ' ')
2155 .map_or(false, |i| snippet[i..].ends_with('\n'));
2156 let snippet = snippet.trim();
2157 if !snippet.is_empty() {
2158 result.push(if original_starts_with_newline {
2163 result.push_str(snippet);
2164 if original_ends_with_newline {
2165 force_new_line_for_brace = true;
2171 let pos_before_where = match fd.output {
2172 ast::FunctionRetTy::Default(..) => args_span.hi(),
2173 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2176 let is_args_multi_lined = arg_str.contains('\n');
2178 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2179 let where_clause_str = rewrite_where_clause(
2182 context.config.brace_style(),
2183 Shape::indented(indent, context.config),
2189 is_args_multi_lined,
2191 // If there are neither where clause nor return type, we may be missing comments between
2193 if where_clause_str.is_empty() {
2194 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2195 match recover_missing_comment_in_span(
2196 mk_sp(args_span.hi(), ret_span.hi()),
2199 last_line_width(&result),
2201 Some(ref missing_comment) if !missing_comment.is_empty() => {
2202 result.push_str(missing_comment);
2203 force_new_line_for_brace = true;
2210 result.push_str(&where_clause_str);
2212 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2213 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2214 Some((result, force_new_line_for_brace))
2217 #[derive(Copy, Clone)]
2218 struct WhereClauseOption {
2219 suppress_comma: bool, // Force no trailing comma
2220 snuggle: bool, // Do not insert newline before `where`
2221 compress_where: bool, // Try single line where clause instead of vertical layout
2224 impl WhereClauseOption {
2225 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2229 compress_where: false,
2233 pub fn snuggled(current: &str) -> WhereClauseOption {
2235 suppress_comma: false,
2236 snuggle: last_line_width(current) == 1,
2237 compress_where: false,
2241 pub fn suppress_comma(&mut self) {
2242 self.suppress_comma = true
2245 pub fn compress_where(&mut self) {
2246 self.compress_where = true
2249 pub fn snuggle(&mut self) {
2255 context: &RewriteContext,
2257 explicit_self: Option<&ast::ExplicitSelf>,
2258 one_line_budget: usize,
2259 multi_line_budget: usize,
2264 generics_str_contains_newline: bool,
2265 ) -> Option<String> {
2266 let mut arg_item_strs = args
2269 arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent))
2270 .unwrap_or_else(|| context.snippet(arg.span()).to_owned())
2272 .collect::<Vec<_>>();
2274 // Account for sugary self.
2275 // FIXME: the comment for the self argument is dropped. This is blocked
2276 // on rust issue #27522.
2277 let min_args = explicit_self
2278 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2279 .map_or(1, |self_str| {
2280 arg_item_strs[0] = self_str;
2284 // Comments between args.
2285 let mut arg_items = Vec::new();
2287 arg_items.push(ListItem::from_str(""));
2290 // FIXME(#21): if there are no args, there might still be a comment, but
2291 // without spans for the comment or parens, there is no chance of
2292 // getting it right. You also don't get to put a comment on self, unless
2294 if args.len() >= min_args || variadic {
2295 let comment_span_start = if min_args == 2 {
2296 let second_arg_start = if arg_has_pattern(&args[1]) {
2297 args[1].pat.span.lo()
2299 args[1].ty.span.lo()
2301 let reduced_span = mk_sp(span.lo(), second_arg_start);
2303 context.snippet_provider.span_after_last(reduced_span, ",")
2308 enum ArgumentKind<'a> {
2309 Regular(&'a ast::Arg),
2313 let variadic_arg = if variadic {
2314 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2315 let variadic_start =
2316 context.snippet_provider.span_after(variadic_span, "...") - BytePos(3);
2317 Some(ArgumentKind::Variadic(variadic_start))
2322 let more_items = itemize_list(
2323 context.snippet_provider,
2324 args[min_args - 1..]
2326 .map(ArgumentKind::Regular)
2327 .chain(variadic_arg),
2331 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2332 ArgumentKind::Variadic(start) => start,
2335 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2336 ArgumentKind::Variadic(start) => start + BytePos(3),
2339 ArgumentKind::Regular(..) => None,
2340 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2347 arg_items.extend(more_items);
2350 let fits_in_one_line = !generics_str_contains_newline
2351 && (arg_items.is_empty()
2352 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2354 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2355 item.item = Some(arg);
2358 let last_line_ends_with_comment = arg_items
2361 .and_then(|item| item.post_comment.as_ref())
2362 .map_or(false, |s| s.trim().starts_with("//"));
2364 let (indent, trailing_comma) = match context.config.indent_style() {
2365 IndentStyle::Block if fits_in_one_line => {
2366 (indent.block_indent(context.config), SeparatorTactic::Never)
2368 IndentStyle::Block => (
2369 indent.block_indent(context.config),
2370 context.config.trailing_comma(),
2372 IndentStyle::Visual if last_line_ends_with_comment => {
2373 (arg_indent, context.config.trailing_comma())
2375 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2378 let tactic = definitive_tactic(
2380 context.config.fn_args_density().to_list_tactic(),
2384 let budget = match tactic {
2385 DefinitiveListTactic::Horizontal => one_line_budget,
2386 _ => multi_line_budget,
2389 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2391 let trailing_separator = if variadic {
2392 SeparatorTactic::Never
2396 let fmt = ListFormatting::new(Shape::legacy(budget, indent), context.config)
2398 .trailing_separator(trailing_separator)
2399 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2400 .preserve_newline(true);
2401 write_list(&arg_items, &fmt)
2404 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2405 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2406 ident != symbol::keywords::Invalid.ident()
2412 fn compute_budgets_for_args(
2413 context: &RewriteContext,
2417 newline_brace: bool,
2419 force_vertical_layout: bool,
2420 ) -> Option<((usize, usize, Indent))> {
2422 "compute_budgets_for_args {} {:?}, {}, {}",
2428 // Try keeping everything on the same line.
2429 if !result.contains('\n') && !force_vertical_layout {
2430 // 2 = `()`, 3 = `() `, space is before ret_string.
2431 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2432 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2442 let one_line_budget = context.budget(used_space);
2444 if one_line_budget > 0 {
2446 let (indent, multi_line_budget) = match context.config.indent_style() {
2447 IndentStyle::Block => {
2448 let indent = indent.block_indent(context.config);
2449 (indent, context.budget(indent.width() + 1))
2451 IndentStyle::Visual => {
2452 let indent = indent + result.len() + 1;
2453 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2454 (indent, context.budget(multi_line_overhead))
2458 return Some((one_line_budget, multi_line_budget, indent));
2462 // Didn't work. we must force vertical layout and put args on a newline.
2463 let new_indent = indent.block_indent(context.config);
2464 let used_space = match context.config.indent_style() {
2466 IndentStyle::Block => new_indent.width() + 1,
2467 // Account for `)` and possibly ` {`.
2468 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2470 Some((0, context.budget(used_space), new_indent))
2473 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2474 let predicate_count = where_clause.predicates.len();
2476 if config.where_single_line() && predicate_count == 1 {
2479 let brace_style = config.brace_style();
2481 brace_style == BraceStyle::AlwaysNextLine
2482 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2485 fn rewrite_generics(
2486 context: &RewriteContext,
2488 generics: &ast::Generics,
2490 ) -> Option<String> {
2491 // FIXME: convert bounds to where clauses where they get too big or if
2492 // there is a where clause at all.
2494 if generics.params.is_empty() {
2495 return Some(ident.to_owned());
2498 let params = generics.params.iter();
2499 overflow::rewrite_with_angle_brackets(context, ident, params, shape, generics.span)
2502 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2503 match config.indent_style() {
2504 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2505 IndentStyle::Block => {
2509 .block_indent(config.tab_spaces())
2510 .with_max_width(config)
2516 fn rewrite_where_clause_rfc_style(
2517 context: &RewriteContext,
2518 where_clause: &ast::WhereClause,
2521 span_end: Option<BytePos>,
2522 span_end_before_where: BytePos,
2523 where_clause_option: WhereClauseOption,
2524 is_args_multi_line: bool,
2525 ) -> Option<String> {
2526 let block_shape = shape.block().with_max_width(context.config);
2528 let (span_before, span_after) =
2529 missing_span_before_after_where(span_end_before_where, where_clause);
2530 let (comment_before, comment_after) =
2531 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2533 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2536 block_shape.indent.to_string_with_newline(context.config)
2539 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2541 let clause_shape = clause_shape.sub_width(1)?;
2542 // each clause on one line, trailing comma (except if suppress_comma)
2543 let span_start = where_clause.predicates[0].span().lo();
2544 // If we don't have the start of the next span, then use the end of the
2545 // predicates, but that means we miss comments.
2546 let len = where_clause.predicates.len();
2547 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2548 let span_end = span_end.unwrap_or(end_of_preds);
2549 let items = itemize_list(
2550 context.snippet_provider,
2551 where_clause.predicates.iter(),
2554 |pred| pred.span().lo(),
2555 |pred| pred.span().hi(),
2556 |pred| pred.rewrite(context, clause_shape),
2561 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2562 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2563 SeparatorTactic::Never
2565 context.config.trailing_comma()
2568 // shape should be vertical only and only if we have `where_single_line` option enabled
2569 // and the number of items of the where clause is equal to 1
2570 let shape_tactic = if where_single_line {
2571 DefinitiveListTactic::Horizontal
2573 DefinitiveListTactic::Vertical
2576 let fmt = ListFormatting::new(clause_shape, context.config)
2577 .tactic(shape_tactic)
2578 .trailing_separator(comma_tactic)
2579 .preserve_newline(true);
2580 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2582 let comment_separator = |comment: &str, shape: Shape| {
2583 if comment.is_empty() {
2586 shape.indent.to_string_with_newline(context.config)
2589 let newline_before_where = comment_separator(&comment_before, shape);
2590 let newline_after_where = comment_separator(&comment_after, clause_shape);
2593 let clause_sep = if where_clause_option.compress_where
2594 && comment_before.is_empty()
2595 && comment_after.is_empty()
2596 && !preds_str.contains('\n')
2597 && 6 + preds_str.len() <= shape.width
2598 || where_single_line
2602 clause_shape.indent.to_string_with_newline(context.config)
2605 "{}{}{}where{}{}{}{}",
2608 newline_before_where,
2609 newline_after_where,
2616 fn rewrite_where_clause(
2617 context: &RewriteContext,
2618 where_clause: &ast::WhereClause,
2619 brace_style: BraceStyle,
2623 span_end: Option<BytePos>,
2624 span_end_before_where: BytePos,
2625 where_clause_option: WhereClauseOption,
2626 is_args_multi_line: bool,
2627 ) -> Option<String> {
2628 if where_clause.predicates.is_empty() {
2629 return Some(String::new());
2632 if context.config.indent_style() == IndentStyle::Block {
2633 return rewrite_where_clause_rfc_style(
2639 span_end_before_where,
2640 where_clause_option,
2645 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2647 let offset = match context.config.indent_style() {
2648 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2649 // 6 = "where ".len()
2650 IndentStyle::Visual => shape.indent + extra_indent + 6,
2652 // FIXME: if indent_style != Visual, then the budgets below might
2653 // be out by a char or two.
2655 let budget = context.config.max_width() - offset.width();
2656 let span_start = where_clause.predicates[0].span().lo();
2657 // If we don't have the start of the next span, then use the end of the
2658 // predicates, but that means we miss comments.
2659 let len = where_clause.predicates.len();
2660 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2661 let span_end = span_end.unwrap_or(end_of_preds);
2662 let items = itemize_list(
2663 context.snippet_provider,
2664 where_clause.predicates.iter(),
2667 |pred| pred.span().lo(),
2668 |pred| pred.span().hi(),
2669 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2674 let item_vec = items.collect::<Vec<_>>();
2675 // FIXME: we don't need to collect here
2676 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2678 let mut comma_tactic = context.config.trailing_comma();
2679 // Kind of a hack because we don't usually have trailing commas in where clauses.
2680 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2681 comma_tactic = SeparatorTactic::Never;
2684 let fmt = ListFormatting::new(Shape::legacy(budget, offset), context.config)
2686 .trailing_separator(comma_tactic)
2687 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2688 .preserve_newline(true);
2689 let preds_str = write_list(&item_vec, &fmt)?;
2691 let end_length = if terminator == "{" {
2692 // If the brace is on the next line we don't need to count it otherwise it needs two
2695 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2696 BraceStyle::PreferSameLine => 2,
2698 } else if terminator == "=" {
2703 if density == Density::Tall
2704 || preds_str.contains('\n')
2705 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2709 (shape.indent + extra_indent).to_string(context.config),
2713 Some(format!(" where {}", preds_str))
2717 fn missing_span_before_after_where(
2718 before_item_span_end: BytePos,
2719 where_clause: &ast::WhereClause,
2721 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2723 let pos_after_where = where_clause.span.lo() + BytePos(5);
2724 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2725 (missing_span_before, missing_span_after)
2728 fn rewrite_comments_before_after_where(
2729 context: &RewriteContext,
2730 span_before_where: Span,
2731 span_after_where: Span,
2733 ) -> Option<(String, String)> {
2734 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2735 let after_comment = rewrite_missing_comment(
2737 shape.block_indent(context.config.tab_spaces()),
2740 Some((before_comment, after_comment))
2744 context: &RewriteContext,
2747 vis: &ast::Visibility,
2751 format_visibility(context, vis),
2753 rewrite_ident(context, ident)
2757 #[derive(PartialEq, Eq, Clone, Copy)]
2765 context: &RewriteContext,
2766 generics: &ast::Generics,
2767 brace_style: BraceStyle,
2768 brace_pos: BracePos,
2772 ) -> Option<String> {
2773 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2774 let mut result = rewrite_generics(context, "", generics, shape)?;
2776 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2777 let budget = context.budget(last_line_used_width(&result, offset.width()));
2778 let mut option = WhereClauseOption::snuggled(&result);
2779 if brace_pos == BracePos::None {
2780 option.suppress_comma = true;
2782 // If the generics are not parameterized then generics.span.hi() == 0,
2783 // so we use span.lo(), which is the position after `struct Foo`.
2784 let span_end_before_where = if !generics.params.is_empty() {
2789 let where_clause_str = rewrite_where_clause(
2791 &generics.where_clause,
2793 Shape::legacy(budget, offset.block_only()),
2797 span_end_before_where,
2801 result.push_str(&where_clause_str);
2802 brace_pos == BracePos::ForceSameLine
2803 || brace_style == BraceStyle::PreferSameLine
2804 || (generics.where_clause.predicates.is_empty()
2805 && trimmed_last_line_width(&result) == 1)
2807 brace_pos == BracePos::ForceSameLine
2808 || trimmed_last_line_width(&result) == 1
2809 || brace_style != BraceStyle::AlwaysNextLine
2811 if brace_pos == BracePos::None {
2812 return Some(result);
2814 let total_used_width = last_line_used_width(&result, used_width);
2815 let remaining_budget = context.budget(total_used_width);
2816 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2817 // and hence we take the closer into account as well for one line budget.
2818 // We assume that the closer has the same length as the opener.
2819 let overhead = if brace_pos == BracePos::ForceSameLine {
2826 let forbid_same_line_brace = overhead > remaining_budget;
2827 if !forbid_same_line_brace && same_line_brace {
2831 result.push_str(&offset.block_only().to_string(context.config));
2838 impl Rewrite for ast::ForeignItem {
2839 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2840 let attrs_str = self.attrs.rewrite(context, shape)?;
2841 // Drop semicolon or it will be interpreted as comment.
2842 // FIXME: this may be a faulty span from libsyntax.
2843 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2845 let item_str = match self.node {
2846 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => rewrite_fn_base(
2850 &FnSig::new(fn_decl, generics, self.vis.clone()),
2855 .map(|(s, _)| format!("{};", s)),
2856 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2857 // FIXME(#21): we're dropping potential comments in between the
2858 // function keywords here.
2859 let vis = format_visibility(context, &self.vis);
2860 let mut_str = if is_mutable { "mut " } else { "" };
2861 let prefix = format!(
2865 rewrite_ident(context, self.ident)
2868 rewrite_assign_rhs(context, prefix, &**ty, shape.sub_width(1)?).map(|s| s + ";")
2870 ast::ForeignItemKind::Ty => {
2871 let vis = format_visibility(context, &self.vis);
2875 rewrite_ident(context, self.ident)
2878 ast::ForeignItemKind::Macro(ref mac) => {
2879 rewrite_macro(mac, None, context, shape, MacroPosition::Item)
2883 let missing_span = if self.attrs.is_empty() {
2884 mk_sp(self.span.lo(), self.span.lo())
2886 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2888 combine_strs_with_missing_comments(
2899 /// Rewrite an inline mod.
2900 pub fn rewrite_mod(context: &RewriteContext, item: &ast::Item) -> String {
2901 let mut result = String::with_capacity(32);
2902 result.push_str(&*format_visibility(context, &item.vis));
2903 result.push_str("mod ");
2904 result.push_str(rewrite_ident(context, item.ident));
2909 /// Rewrite `extern crate foo;` WITHOUT attributes.
2910 pub fn rewrite_extern_crate(context: &RewriteContext, item: &ast::Item) -> Option<String> {
2911 assert!(is_extern_crate(item));
2912 let new_str = context.snippet(item.span);
2913 Some(if contains_comment(new_str) {
2916 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
2917 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
2921 /// Returns true for `mod foo;`, false for `mod foo { .. }`.
2922 pub fn is_mod_decl(item: &ast::Item) -> bool {
2924 ast::ItemKind::Mod(ref m) => m.inner.hi() != item.span.hi(),
2929 pub fn is_use_item(item: &ast::Item) -> bool {
2931 ast::ItemKind::Use(_) => true,
2936 pub fn is_extern_crate(item: &ast::Item) -> bool {
2938 ast::ItemKind::ExternCrate(..) => true,