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 mk_sp(span.lo(), body_start),
468 last_line_width(&enum_header),
471 self.push_str(&generics_str);
473 self.last_pos = body_start;
475 match self.format_variant_list(enum_def, body_start, span.hi()) {
476 Some(ref s) if enum_def.variants.is_empty() => self.push_str(s),
478 self.push_rewrite(mk_sp(body_start, span.hi()), rw);
479 self.block_indent = self.block_indent.block_unindent(self.config);
484 // Format the body of an enum definition
485 fn format_variant_list(
487 enum_def: &ast::EnumDef,
490 ) -> Option<String> {
491 if enum_def.variants.is_empty() {
492 let mut buffer = String::with_capacity(128);
494 let span = mk_sp(body_lo, body_hi - BytePos(1));
495 format_empty_struct_or_tuple(
505 let mut result = String::with_capacity(1024);
506 let original_offset = self.block_indent;
507 self.block_indent = self.block_indent.block_indent(self.config);
509 // If enum variants have discriminants, try to vertically align those,
510 // provided the discrims are not shifted too much to the right
511 let align_threshold: usize = self.config.enum_discrim_align_threshold();
512 let discr_ident_lens: Vec<usize> = enum_def
515 .filter(|var| var.node.disr_expr.is_some())
516 .map(|var| rewrite_ident(&self.get_context(), var.node.ident).len())
518 // cut the list at the point of longest discrim shorter than the threshold
519 // All of the discrims under the threshold will get padded, and all above - left as is.
520 let pad_discrim_ident_to = *discr_ident_lens
522 .filter(|&l| *l <= align_threshold)
526 let itemize_list_with = |one_line_width: usize| {
528 self.snippet_provider,
529 enum_def.variants.iter(),
533 if !f.node.attrs.is_empty() {
534 f.node.attrs[0].span.lo()
540 |f| self.format_variant(f, one_line_width, pad_discrim_ident_to),
547 let mut items: Vec<_> =
548 itemize_list_with(self.config.width_heuristics().struct_variant_width);
549 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
550 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
551 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
552 if has_multiline_variant && has_single_line_variant {
553 items = itemize_list_with(0);
556 let shape = self.shape().sub_width(2)?;
557 let fmt = ListFormatting::new(shape, self.config)
558 .trailing_separator(self.config.trailing_comma())
559 .preserve_newline(true);
561 let list = write_list(&items, &fmt)?;
562 result.push_str(&list);
563 result.push_str(&original_offset.to_string_with_newline(self.config));
568 // Variant of an enum.
571 field: &ast::Variant,
572 one_line_width: usize,
573 pad_discrim_ident_to: usize,
574 ) -> Option<String> {
575 if contains_skip(&field.node.attrs) {
576 let lo = field.node.attrs[0].span.lo();
577 let span = mk_sp(lo, field.span.hi());
578 return Some(self.snippet(span).to_owned());
581 let context = self.get_context();
583 let shape = self.shape().sub_width(1)?;
584 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
589 .map_or(field.span.lo(), |attr| attr.span.hi());
590 let span = mk_sp(lo, field.span.lo());
592 let variant_body = match field.node.data {
593 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
595 &StructParts::from_variant(field),
597 Some(one_line_width),
599 ast::VariantData::Unit(..) => {
600 if let Some(ref expr) = field.node.disr_expr {
603 rewrite_ident(&context, field.node.ident),
606 rewrite_assign_rhs(&context, lhs, &*expr.value, shape)?
608 rewrite_ident(&context, field.node.ident).to_owned()
613 combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
616 fn visit_impl_items(&mut self, items: &[ast::ImplItem]) {
617 if self.get_context().config.reorder_impl_items() {
618 // Create visitor for each items, then reorder them.
619 let mut buffer = vec![];
621 self.visit_impl_item(item);
622 buffer.push((self.buffer.clone(), item.clone()));
625 // type -> existential -> const -> macro -> method
626 use ast::ImplItemKind::*;
627 fn need_empty_line(a: &ast::ImplItemKind, b: &ast::ImplItemKind) -> bool {
630 | (Const(..), Const(..))
631 | (Existential(..), Existential(..)) => false,
636 buffer.sort_by(|(_, a), (_, b)| match (&a.node, &b.node) {
638 | (Const(..), Const(..))
639 | (Macro(..), Macro(..))
640 | (Existential(..), Existential(..)) => a.ident.as_str().cmp(&b.ident.as_str()),
641 (Method(..), Method(..)) => a.span.lo().cmp(&b.span.lo()),
642 (Type(..), _) => Ordering::Less,
643 (_, Type(..)) => Ordering::Greater,
644 (Existential(..), _) => Ordering::Less,
645 (_, Existential(..)) => Ordering::Greater,
646 (Const(..), _) => Ordering::Less,
647 (_, Const(..)) => Ordering::Greater,
648 (Macro(..), _) => Ordering::Less,
649 (_, Macro(..)) => Ordering::Greater,
651 let mut prev_kind = None;
652 for (buf, item) in buffer {
653 // Make sure that there are at least a single empty line between
654 // different impl items.
657 .map_or(false, |prev_kind| need_empty_line(prev_kind, &item.node))
661 let indent_str = self.block_indent.to_string_with_newline(self.config);
662 self.push_str(&indent_str);
663 self.push_str(buf.trim());
664 prev_kind = Some(item.node.clone());
668 self.visit_impl_item(item);
675 context: &RewriteContext,
678 where_span_end: Option<BytePos>,
679 ) -> Option<String> {
680 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
681 let mut result = String::with_capacity(128);
682 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
683 let sep = offset.to_string_with_newline(context.config);
684 result.push_str(&ref_and_type);
686 let where_budget = if result.contains('\n') {
687 context.config.max_width()
689 context.budget(last_line_width(&result))
692 let mut option = WhereClauseOption::snuggled(&ref_and_type);
693 let snippet = context.snippet(item.span);
694 let open_pos = snippet.find_uncommented("{")? + 1;
695 if !contains_comment(&snippet[open_pos..])
697 && generics.where_clause.predicates.len() == 1
698 && !result.contains('\n')
700 option.suppress_comma();
702 option.compress_where();
705 let where_clause_str = rewrite_where_clause(
707 &generics.where_clause,
708 context.config.brace_style(),
709 Shape::legacy(where_budget, offset.block_only()),
718 // If there is no where clause, we may have missing comments between the trait name and
719 // the opening brace.
720 if generics.where_clause.predicates.is_empty() {
721 if let Some(hi) = where_span_end {
722 match recover_missing_comment_in_span(
723 mk_sp(self_ty.span.hi(), hi),
724 Shape::indented(offset, context.config),
726 last_line_width(&result),
728 Some(ref missing_comment) if !missing_comment.is_empty() => {
729 result.push_str(missing_comment);
736 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
737 result.push_str(&where_clause_str);
738 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
739 // if the where_clause contains extra comments AND
740 // there is only one where clause predicate
741 // recover the suppressed comma in single line where_clause formatting
742 if generics.where_clause.predicates.len() == 1 {
743 result.push_str(",");
745 result.push_str(&format!("{}{{{}}}", &sep, &sep));
747 result.push_str(" {}");
752 result.push_str(&where_clause_str);
754 let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
755 match context.config.brace_style() {
756 _ if need_newline => result.push_str(&sep),
757 BraceStyle::AlwaysNextLine => result.push_str(&sep),
758 BraceStyle::PreferSameLine => result.push(' '),
759 BraceStyle::SameLineWhere => {
760 if !where_clause_str.is_empty() {
761 result.push_str(&sep);
770 let snippet = context.snippet(item.span);
771 let open_pos = snippet.find_uncommented("{")? + 1;
773 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
774 let mut visitor = FmtVisitor::from_context(context);
775 let item_indent = offset.block_only().block_indent(context.config);
776 visitor.block_indent = item_indent;
777 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
779 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
780 visitor.visit_impl_items(items);
782 visitor.format_missing(item.span.hi() - BytePos(1));
784 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
785 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
787 result.push_str(&inner_indent_str);
788 result.push_str(visitor.buffer.trim());
789 result.push_str(&outer_indent_str);
790 } else if need_newline || !context.config.empty_item_single_line() {
791 result.push_str(&sep);
802 fn is_impl_single_line(
803 context: &RewriteContext,
804 items: &[ast::ImplItem],
806 where_clause_str: &str,
809 let snippet = context.snippet(item.span);
810 let open_pos = snippet.find_uncommented("{")? + 1;
813 context.config.empty_item_single_line()
815 && !result.contains('\n')
816 && result.len() + where_clause_str.len() <= context.config.max_width()
817 && !contains_comment(&snippet[open_pos..]),
821 fn format_impl_ref_and_type(
822 context: &RewriteContext,
825 ) -> Option<String> {
826 if let ast::ItemKind::Impl(
836 let mut result = String::with_capacity(128);
838 result.push_str(&format_visibility(context, &item.vis));
839 result.push_str(format_defaultness(defaultness));
840 result.push_str(format_unsafety(unsafety));
842 let shape = generics_shape_from_config(
844 Shape::indented(offset + last_line_width(&result), context.config),
847 let generics_str = rewrite_generics(context, "impl", generics, shape)?;
848 result.push_str(&generics_str);
850 let polarity_str = if polarity == ast::ImplPolarity::Negative {
856 if let Some(ref trait_ref) = *trait_ref {
857 let result_len = last_line_width(&result);
858 result.push_str(&rewrite_trait_ref(
867 // Try to put the self type in a single line.
869 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
870 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
871 // If there is no where clause adapt budget for type formatting to take space and curly
872 // brace into account.
873 match context.config.brace_style() {
874 BraceStyle::AlwaysNextLine => 0,
880 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
881 // 1 = space before the type.
882 let budget = context.budget(used_space + 1);
883 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
884 if !self_ty_str.contains('\n') {
885 if trait_ref.is_some() {
886 result.push_str(" for ");
890 result.push_str(&self_ty_str);
895 // Couldn't fit the self type on a single line, put it on a new line.
897 // Add indentation of one additional tab.
898 let new_line_offset = offset.block_indent(context.config);
899 result.push_str(&new_line_offset.to_string(context.config));
900 if trait_ref.is_some() {
901 result.push_str("for ");
903 let budget = context.budget(last_line_width(&result));
904 let type_offset = match context.config.indent_style() {
905 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
906 IndentStyle::Block => new_line_offset,
908 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
915 fn rewrite_trait_ref(
916 context: &RewriteContext,
917 trait_ref: &ast::TraitRef,
921 ) -> Option<String> {
922 // 1 = space between generics and trait_ref
923 let used_space = 1 + polarity_str.len() + result_len;
924 let shape = Shape::indented(offset + used_space, context.config);
925 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
926 if !trait_ref_str.contains('\n') {
927 return Some(format!(" {}{}", polarity_str, &trait_ref_str));
930 // We could not make enough space for trait_ref, so put it on new line.
931 let offset = offset.block_indent(context.config);
932 let shape = Shape::indented(offset, context.config);
933 let trait_ref_str = trait_ref.rewrite(context, shape)?;
936 &offset.to_string_with_newline(context.config),
942 pub struct StructParts<'a> {
945 vis: &'a ast::Visibility,
946 def: &'a ast::VariantData,
947 generics: Option<&'a ast::Generics>,
951 impl<'a> StructParts<'a> {
952 fn format_header(&self, context: &RewriteContext) -> String {
953 format_header(context, self.prefix, self.ident, self.vis)
956 fn from_variant(variant: &'a ast::Variant) -> Self {
959 ident: variant.node.ident,
960 vis: &DEFAULT_VISIBILITY,
961 def: &variant.node.data,
967 pub fn from_item(item: &'a ast::Item) -> Self {
968 let (prefix, def, generics) = match item.node {
969 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
970 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
978 generics: Some(generics),
985 context: &RewriteContext,
986 struct_parts: &StructParts,
988 one_line_width: Option<usize>,
989 ) -> Option<String> {
990 match *struct_parts.def {
991 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
992 ast::VariantData::Tuple(ref fields, _) => {
993 format_tuple_struct(context, struct_parts, fields, offset)
995 ast::VariantData::Struct(ref fields, _) => {
996 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
1001 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
1002 if let ast::ItemKind::Trait(
1010 let mut result = String::with_capacity(128);
1011 let header = format!(
1013 format_visibility(context, &item.vis),
1014 format_unsafety(unsafety),
1015 format_auto(is_auto),
1017 result.push_str(&header);
1019 let body_lo = context.snippet_provider.span_after(item.span, "{");
1021 let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
1023 rewrite_generics(context, rewrite_ident(context, item.ident), generics, shape)?;
1024 result.push_str(&generics_str);
1026 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
1027 if !generic_bounds.is_empty() {
1028 let ident_hi = context
1030 .span_after(item.span, &item.ident.as_str());
1031 let bound_hi = generic_bounds.last().unwrap().span().hi();
1032 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
1033 if contains_comment(snippet) {
1037 result = rewrite_assign_rhs_with(
1042 RhsTactics::ForceNextLineWithoutIndent,
1046 // Rewrite where clause.
1047 if !generics.where_clause.predicates.is_empty() {
1048 let where_density = if context.config.indent_style() == IndentStyle::Block {
1054 let where_budget = context.budget(last_line_width(&result));
1055 let pos_before_where = if generic_bounds.is_empty() {
1056 generics.where_clause.span.lo()
1058 generic_bounds[generic_bounds.len() - 1].span().hi()
1060 let option = WhereClauseOption::snuggled(&generics_str);
1061 let where_clause_str = rewrite_where_clause(
1063 &generics.where_clause,
1064 context.config.brace_style(),
1065 Shape::legacy(where_budget, offset.block_only()),
1073 // If the where clause cannot fit on the same line,
1074 // put the where clause on a new line
1075 if !where_clause_str.contains('\n')
1076 && last_line_width(&result) + where_clause_str.len() + offset.width()
1077 > context.config.comment_width()
1079 let width = offset.block_indent + context.config.tab_spaces() - 1;
1080 let where_indent = Indent::new(0, width);
1081 result.push_str(&where_indent.to_string_with_newline(context.config));
1083 result.push_str(&where_clause_str);
1085 let item_snippet = context.snippet(item.span);
1086 if let Some(lo) = item_snippet.find('/') {
1088 let comment_hi = body_lo - BytePos(1);
1089 let comment_lo = item.span.lo() + BytePos(lo as u32);
1090 if comment_lo < comment_hi {
1091 match recover_missing_comment_in_span(
1092 mk_sp(comment_lo, comment_hi),
1093 Shape::indented(offset, context.config),
1095 last_line_width(&result),
1097 Some(ref missing_comment) if !missing_comment.is_empty() => {
1098 result.push_str(missing_comment);
1106 match context.config.brace_style() {
1107 _ if last_line_contains_single_line_comment(&result)
1108 || last_line_width(&result) + 2 > context.budget(offset.width()) =>
1110 result.push_str(&offset.to_string_with_newline(context.config));
1112 BraceStyle::AlwaysNextLine => {
1113 result.push_str(&offset.to_string_with_newline(context.config));
1115 BraceStyle::PreferSameLine => result.push(' '),
1116 BraceStyle::SameLineWhere => {
1117 if result.contains('\n')
1118 || (!generics.where_clause.predicates.is_empty() && !trait_items.is_empty())
1120 result.push_str(&offset.to_string_with_newline(context.config));
1128 let snippet = context.snippet(item.span);
1129 let open_pos = snippet.find_uncommented("{")? + 1;
1130 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
1132 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1133 let mut visitor = FmtVisitor::from_context(context);
1134 visitor.block_indent = offset.block_only().block_indent(context.config);
1135 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1137 for item in trait_items {
1138 visitor.visit_trait_item(item);
1141 visitor.format_missing(item.span.hi() - BytePos(1));
1143 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
1145 result.push_str(&inner_indent_str);
1146 result.push_str(visitor.buffer.trim());
1147 result.push_str(&outer_indent_str);
1148 } else if result.contains('\n') {
1149 result.push_str(&outer_indent_str);
1159 pub fn format_trait_alias(
1160 context: &RewriteContext,
1162 generics: &ast::Generics,
1163 generic_bounds: &ast::GenericBounds,
1165 ) -> Option<String> {
1166 let alias = rewrite_ident(context, ident);
1167 // 6 = "trait ", 2 = " ="
1168 let g_shape = shape.offset_left(6)?.sub_width(2)?;
1169 let generics_str = rewrite_generics(context, &alias, generics, g_shape)?;
1170 let lhs = format!("trait {} =", generics_str);
1172 rewrite_assign_rhs(context, lhs, generic_bounds, shape.sub_width(1)?).map(|s| s + ";")
1175 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1176 let header_str = format_header(context, p.prefix, p.ident, p.vis);
1177 let generics_str = if let Some(generics) = p.generics {
1178 let hi = if generics.where_clause.predicates.is_empty() {
1181 generics.where_clause.span.hi()
1186 context.config.brace_style(),
1189 mk_sp(generics.span.lo(), hi),
1190 last_line_width(&header_str),
1195 Some(format!("{}{};", header_str, generics_str))
1198 pub fn format_struct_struct(
1199 context: &RewriteContext,
1200 struct_parts: &StructParts,
1201 fields: &[ast::StructField],
1203 one_line_width: Option<usize>,
1204 ) -> Option<String> {
1205 let mut result = String::with_capacity(1024);
1206 let span = struct_parts.span;
1208 let header_str = struct_parts.format_header(context);
1209 result.push_str(&header_str);
1211 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1212 let body_lo = context.snippet_provider.span_after(span, "{");
1214 let generics_str = match struct_parts.generics {
1215 Some(g) => format_generics(
1218 context.config.brace_style(),
1219 if fields.is_empty() {
1220 BracePos::ForceSameLine
1225 mk_sp(header_hi, body_lo),
1226 last_line_width(&result),
1229 // 3 = ` {}`, 2 = ` {`.
1230 let overhead = if fields.is_empty() { 3 } else { 2 };
1231 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1232 || context.config.max_width() < overhead + result.len()
1234 format!("\n{}{{", offset.block_only().to_string(context.config))
1241 let overhead = if fields.is_empty() { 1 } else { 0 };
1242 let total_width = result.len() + generics_str.len() + overhead;
1243 if !generics_str.is_empty()
1244 && !generics_str.contains('\n')
1245 && total_width > context.config.max_width()
1248 result.push_str(&offset.to_string(context.config));
1249 result.push_str(generics_str.trim_left());
1251 result.push_str(&generics_str);
1254 if fields.is_empty() {
1255 let inner_span = mk_sp(body_lo, span.hi() - BytePos(1));
1256 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "", "}");
1257 return Some(result);
1261 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1262 let one_line_budget =
1263 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1265 let items_str = rewrite_with_alignment(
1268 Shape::indented(offset, context.config).sub_width(1)?,
1269 mk_sp(body_lo, span.hi()),
1273 if !items_str.contains('\n')
1274 && !result.contains('\n')
1275 && items_str.len() <= one_line_budget
1276 && !last_line_contains_single_line_comment(&items_str)
1278 Some(format!("{} {} }}", result, items_str))
1284 .block_indent(context.config)
1285 .to_string(context.config),
1287 offset.to_string(context.config)
1292 fn get_bytepos_after_visibility(vis: &ast::Visibility, default_span: Span) -> BytePos {
1294 ast::VisibilityKind::Crate(..) | ast::VisibilityKind::Restricted { .. } => vis.span.hi(),
1295 _ => default_span.lo(),
1299 // Format tuple or struct without any fields. We need to make sure that the comments
1300 // inside the delimiters are preserved.
1301 fn format_empty_struct_or_tuple(
1302 context: &RewriteContext,
1305 result: &mut String,
1309 // 3 = " {}" or "();"
1310 let used_width = last_line_used_width(&result, offset.width()) + 3;
1311 if used_width > context.config.max_width() {
1312 result.push_str(&offset.to_string_with_newline(context.config))
1314 result.push_str(opener);
1315 match rewrite_missing_comment(span, Shape::indented(offset, context.config), context) {
1316 Some(ref s) if s.is_empty() => (),
1318 if !is_single_line(s) || first_line_contains_single_line_comment(s) {
1319 let nested_indent_str = offset
1320 .block_indent(context.config)
1321 .to_string_with_newline(context.config);
1322 result.push_str(&nested_indent_str);
1325 if last_line_contains_single_line_comment(s) {
1326 result.push_str(&offset.to_string_with_newline(context.config));
1329 None => result.push_str(context.snippet(span)),
1331 result.push_str(closer);
1334 fn format_tuple_struct(
1335 context: &RewriteContext,
1336 struct_parts: &StructParts,
1337 fields: &[ast::StructField],
1339 ) -> Option<String> {
1340 let mut result = String::with_capacity(1024);
1341 let span = struct_parts.span;
1343 let header_str = struct_parts.format_header(context);
1344 result.push_str(&header_str);
1346 let body_lo = if fields.is_empty() {
1347 let lo = get_bytepos_after_visibility(struct_parts.vis, span);
1350 .span_after(mk_sp(lo, span.hi()), "(")
1354 let body_hi = if fields.is_empty() {
1357 .span_after(mk_sp(body_lo, span.hi()), ")")
1359 // This is a dirty hack to work around a missing `)` from the span of the last field.
1360 let last_arg_span = fields[fields.len() - 1].span;
1363 .opt_span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1364 .unwrap_or(last_arg_span.hi())
1367 let where_clause_str = match struct_parts.generics {
1369 let budget = context.budget(last_line_width(&header_str));
1370 let shape = Shape::legacy(budget, offset);
1371 let generics_str = rewrite_generics(context, "", generics, shape)?;
1372 result.push_str(&generics_str);
1374 let where_budget = context.budget(last_line_width(&result));
1375 let option = WhereClauseOption::new(true, false);
1376 rewrite_where_clause(
1378 &generics.where_clause,
1379 context.config.brace_style(),
1380 Shape::legacy(where_budget, offset.block_only()),
1381 Density::Compressed,
1389 None => "".to_owned(),
1392 if fields.is_empty() {
1393 let body_hi = context
1395 .span_before(mk_sp(body_lo, span.hi()), ")");
1396 let inner_span = mk_sp(body_lo, body_hi);
1397 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "(", ")");
1399 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1400 result = overflow::rewrite_with_parens(
1406 context.config.width_heuristics().fn_call_width,
1411 if !where_clause_str.is_empty()
1412 && !where_clause_str.contains('\n')
1413 && (result.contains('\n')
1414 || offset.block_indent + result.len() + where_clause_str.len() + 1
1415 > context.config.max_width())
1417 // We need to put the where clause on a new line, but we didn't
1418 // know that earlier, so the where clause will not be indented properly.
1421 &(offset.block_only() + (context.config.tab_spaces() - 1)).to_string(context.config),
1424 result.push_str(&where_clause_str);
1429 fn rewrite_type_prefix(
1430 context: &RewriteContext,
1434 generics: &ast::Generics,
1435 ) -> Option<String> {
1436 let mut result = String::with_capacity(128);
1437 result.push_str(prefix);
1438 let ident_str = rewrite_ident(context, ident);
1441 if generics.params.is_empty() {
1442 result.push_str(ident_str)
1444 let g_shape = Shape::indented(indent, context.config)
1445 .offset_left(result.len())?
1447 let generics_str = rewrite_generics(context, ident_str, generics, g_shape)?;
1448 result.push_str(&generics_str);
1451 let where_budget = context.budget(last_line_width(&result));
1452 let option = WhereClauseOption::snuggled(&result);
1453 let where_clause_str = rewrite_where_clause(
1455 &generics.where_clause,
1456 context.config.brace_style(),
1457 Shape::legacy(where_budget, indent),
1465 result.push_str(&where_clause_str);
1470 fn rewrite_type_item<R: Rewrite>(
1471 context: &RewriteContext,
1477 generics: &ast::Generics,
1478 vis: &ast::Visibility,
1479 ) -> Option<String> {
1480 let mut result = String::with_capacity(128);
1481 result.push_str(&rewrite_type_prefix(
1484 &format!("{}{} ", format_visibility(context, vis), prefix),
1489 if generics.where_clause.predicates.is_empty() {
1490 result.push_str(suffix);
1492 result.push_str(&indent.to_string_with_newline(context.config));
1493 result.push_str(suffix.trim_left());
1497 let rhs_shape = Shape::indented(indent, context.config).sub_width(1)?;
1498 rewrite_assign_rhs(context, result, rhs, rhs_shape).map(|s| s + ";")
1501 pub fn rewrite_type_alias(
1502 context: &RewriteContext,
1506 generics: &ast::Generics,
1507 vis: &ast::Visibility,
1508 ) -> Option<String> {
1509 rewrite_type_item(context, indent, "type", " =", ident, ty, generics, vis)
1512 pub fn rewrite_existential_type(
1513 context: &RewriteContext,
1516 generic_bounds: &ast::GenericBounds,
1517 generics: &ast::Generics,
1518 vis: &ast::Visibility,
1519 ) -> Option<String> {
1532 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1534 if config.space_before_colon() { " " } else { "" },
1535 if config.space_after_colon() { " " } else { "" },
1539 pub fn rewrite_struct_field_prefix(
1540 context: &RewriteContext,
1541 field: &ast::StructField,
1542 ) -> Option<String> {
1543 let vis = format_visibility(context, &field.vis);
1544 let type_annotation_spacing = type_annotation_spacing(context.config);
1545 Some(match field.ident {
1546 Some(name) => format!(
1549 rewrite_ident(context, name),
1550 type_annotation_spacing.0
1552 None => vis.to_string(),
1556 impl Rewrite for ast::StructField {
1557 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1558 rewrite_struct_field(context, self, shape, 0)
1562 pub fn rewrite_struct_field(
1563 context: &RewriteContext,
1564 field: &ast::StructField,
1566 lhs_max_width: usize,
1567 ) -> Option<String> {
1568 if contains_skip(&field.attrs) {
1569 return Some(context.snippet(field.span()).to_owned());
1572 let type_annotation_spacing = type_annotation_spacing(context.config);
1573 let prefix = rewrite_struct_field_prefix(context, field)?;
1575 let attrs_str = field.attrs.rewrite(context, shape)?;
1576 let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
1577 let missing_span = if field.attrs.is_empty() {
1578 mk_sp(field.span.lo(), field.span.lo())
1580 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1582 let mut spacing = String::from(if field.ident.is_some() {
1583 type_annotation_spacing.1
1587 // Try to put everything on a single line.
1588 let attr_prefix = combine_strs_with_missing_comments(
1596 let overhead = last_line_width(&attr_prefix);
1597 let lhs_offset = lhs_max_width.saturating_sub(overhead);
1598 for _ in 0..lhs_offset {
1601 // In this extreme case we will be missing a space between an attribute and a field.
1602 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1606 .offset_left(overhead + spacing.len())
1607 .and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
1608 if let Some(ref ty) = orig_ty {
1609 if !ty.contains('\n') {
1610 return Some(attr_prefix + &spacing + ty);
1614 let is_prefix_empty = prefix.is_empty();
1615 // We must use multiline. We are going to put attributes and a field on different lines.
1616 let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, shape)?;
1617 // Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
1618 let field_str = if is_prefix_empty {
1619 field_str.trim_left()
1623 combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
1626 pub struct StaticParts<'a> {
1628 vis: &'a ast::Visibility,
1631 mutability: ast::Mutability,
1632 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1633 defaultness: Option<ast::Defaultness>,
1637 impl<'a> StaticParts<'a> {
1638 pub fn from_item(item: &'a ast::Item) -> Self {
1639 let (prefix, ty, mutability, expr) = match item.node {
1640 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1641 ast::ItemKind::Const(ref ty, ref expr) => {
1642 ("const", ty, ast::Mutability::Immutable, expr)
1644 _ => unreachable!(),
1652 expr_opt: Some(expr),
1658 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1659 let (ty, expr_opt) = match ti.node {
1660 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1661 _ => unreachable!(),
1665 vis: &DEFAULT_VISIBILITY,
1668 mutability: ast::Mutability::Immutable,
1669 expr_opt: expr_opt.as_ref(),
1675 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1676 let (ty, expr) = match ii.node {
1677 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1678 _ => unreachable!(),
1685 mutability: ast::Mutability::Immutable,
1686 expr_opt: Some(expr),
1687 defaultness: Some(ii.defaultness),
1694 context: &RewriteContext,
1695 static_parts: &StaticParts,
1697 ) -> Option<String> {
1698 let colon = colon_spaces(
1699 context.config.space_before_colon(),
1700 context.config.space_after_colon(),
1702 let mut prefix = format!(
1704 format_visibility(context, static_parts.vis),
1705 static_parts.defaultness.map_or("", format_defaultness),
1706 static_parts.prefix,
1707 format_mutability(static_parts.mutability),
1713 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1714 let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
1715 Some(ty_str) => ty_str,
1717 if prefix.ends_with(' ') {
1720 let nested_indent = offset.block_indent(context.config);
1721 let nested_shape = Shape::indented(nested_indent, context.config);
1722 let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
1725 nested_indent.to_string_with_newline(context.config),
1731 if let Some(expr) = static_parts.expr_opt {
1732 let lhs = format!("{}{} =", prefix, ty_str);
1734 let remaining_width = context.budget(offset.block_indent + 1);
1739 Shape::legacy(remaining_width, offset.block_only()),
1741 .and_then(|res| recover_comment_removed(res, static_parts.span, context))
1742 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1744 Some(format!("{}{};", prefix, ty_str))
1748 pub fn rewrite_associated_type(
1750 ty_opt: Option<&ptr::P<ast::Ty>>,
1751 generics: &ast::Generics,
1752 generic_bounds_opt: Option<&ast::GenericBounds>,
1753 context: &RewriteContext,
1755 ) -> Option<String> {
1756 let ident_str = rewrite_ident(context, ident);
1758 let generics_shape = Shape::indented(indent, context.config).offset_left(5)?;
1759 let generics_str = rewrite_generics(context, ident_str, generics, generics_shape)?;
1760 let prefix = format!("type {}", generics_str);
1762 let type_bounds_str = if let Some(bounds) = generic_bounds_opt {
1763 if bounds.is_empty() {
1767 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1768 bounds.rewrite(context, shape).map(|s| format!(": {}", s))?
1774 if let Some(ty) = ty_opt {
1776 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1777 let lhs = format!("{}{} =", prefix, type_bounds_str);
1778 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1780 Some(format!("{}{};", prefix, type_bounds_str))
1784 pub fn rewrite_existential_impl_type(
1785 context: &RewriteContext,
1787 generics: &ast::Generics,
1788 generic_bounds: &ast::GenericBounds,
1790 ) -> Option<String> {
1791 rewrite_associated_type(ident, None, generics, Some(generic_bounds), context, indent)
1792 .map(|s| format!("existential {}", s))
1795 pub fn rewrite_associated_impl_type(
1797 defaultness: ast::Defaultness,
1798 ty_opt: Option<&ptr::P<ast::Ty>>,
1799 generics: &ast::Generics,
1800 context: &RewriteContext,
1802 ) -> Option<String> {
1803 let result = rewrite_associated_type(ident, ty_opt, generics, None, context, indent)?;
1806 ast::Defaultness::Default => Some(format!("default {}", result)),
1811 impl Rewrite for ast::FunctionRetTy {
1812 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1814 ast::FunctionRetTy::Default(_) => Some(String::new()),
1815 ast::FunctionRetTy::Ty(ref ty) => {
1816 let inner_width = shape.width.checked_sub(3)?;
1817 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1818 .map(|r| format!("-> {}", r))
1824 fn is_empty_infer(ty: &ast::Ty, pat_span: Span) -> bool {
1826 ast::TyKind::Infer => ty.span.hi() == pat_span.hi(),
1831 impl Rewrite for ast::Arg {
1832 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1833 if is_named_arg(self) {
1834 let mut result = self
1836 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1838 if !is_empty_infer(&*self.ty, self.pat.span) {
1839 if context.config.space_before_colon() {
1840 result.push_str(" ");
1842 result.push_str(":");
1843 if context.config.space_after_colon() {
1844 result.push_str(" ");
1846 let overhead = last_line_width(&result);
1847 let max_width = shape.width.checked_sub(overhead)?;
1850 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1851 result.push_str(&ty_str);
1856 self.ty.rewrite(context, shape)
1861 fn rewrite_explicit_self(
1862 explicit_self: &ast::ExplicitSelf,
1864 context: &RewriteContext,
1865 ) -> Option<String> {
1866 match explicit_self.node {
1867 ast::SelfKind::Region(lt, m) => {
1868 let mut_str = format_mutability(m);
1871 let lifetime_str = l.rewrite(
1873 Shape::legacy(context.config.max_width(), Indent::empty()),
1875 Some(format!("&{} {}self", lifetime_str, mut_str))
1877 None => Some(format!("&{}self", mut_str)),
1880 ast::SelfKind::Explicit(ref ty, _) => {
1881 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1883 let mutability = explicit_self_mutability(&args[0]);
1884 let type_str = ty.rewrite(
1886 Shape::legacy(context.config.max_width(), Indent::empty()),
1891 format_mutability(mutability),
1895 ast::SelfKind::Value(_) => {
1896 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1898 let mutability = explicit_self_mutability(&args[0]);
1900 Some(format!("{}self", format_mutability(mutability)))
1905 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1906 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1907 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1908 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1915 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1916 if is_named_arg(arg) {
1923 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1925 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1926 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1927 _ => arg.ty.span.hi(),
1931 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1932 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1933 ident != symbol::keywords::Invalid.ident()
1939 // Return type is (result, force_new_line_for_brace)
1941 context: &RewriteContext,
1946 newline_brace: bool,
1948 ) -> Option<(String, bool)> {
1949 let mut force_new_line_for_brace = false;
1951 let where_clause = &fn_sig.generics.where_clause;
1953 let mut result = String::with_capacity(1024);
1954 result.push_str(&fn_sig.to_str(context));
1957 result.push_str("fn ");
1960 let overhead = if has_body && !newline_brace {
1967 let used_width = last_line_used_width(&result, indent.width());
1968 let one_line_budget = context.budget(used_width + overhead);
1970 width: one_line_budget,
1974 let fd = fn_sig.decl;
1975 let generics_str = rewrite_generics(
1977 rewrite_ident(context, ident),
1981 result.push_str(&generics_str);
1983 let snuggle_angle_bracket = generics_str
1986 .map_or(false, |l| l.trim_left().len() == 1);
1988 // Note that the width and indent don't really matter, we'll re-layout the
1989 // return type later anyway.
1992 .rewrite(context, Shape::indented(indent, context.config))?;
1994 let multi_line_ret_str = ret_str.contains('\n');
1995 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1998 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
2009 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
2010 one_line_budget, multi_line_budget, arg_indent
2014 // Check if vertical layout was forced.
2015 if one_line_budget == 0
2016 && !snuggle_angle_bracket
2017 && context.config.indent_style() == IndentStyle::Visual
2019 result.push_str(&arg_indent.to_string_with_newline(context.config));
2022 // Skip `pub(crate)`.
2023 let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
2024 // A conservative estimation, to goal is to be over all parens in generics
2025 let args_start = fn_sig
2030 .map_or(lo_after_visibility, |param| param.span().hi());
2031 let args_end = if fd.inputs.is_empty() {
2034 .span_after(mk_sp(args_start, span.hi()), ")")
2036 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
2037 context.snippet_provider.span_after(last_span, ")")
2039 let args_span = mk_sp(
2042 .span_after(mk_sp(args_start, span.hi()), "("),
2045 let arg_str = rewrite_args(
2048 fd.get_self().as_ref(),
2055 generics_str.contains('\n'),
2058 let put_args_in_block = match context.config.indent_style() {
2059 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
2061 } && !fd.inputs.is_empty();
2063 let mut args_last_line_contains_comment = false;
2064 if put_args_in_block {
2065 arg_indent = indent.block_indent(context.config);
2066 result.push_str(&arg_indent.to_string_with_newline(context.config));
2067 result.push_str(&arg_str);
2068 result.push_str(&indent.to_string_with_newline(context.config));
2071 result.push_str(&arg_str);
2072 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
2073 // Put the closing brace on the next line if it overflows the max width.
2075 let closing_paren_overflow_max_width =
2076 fd.inputs.is_empty() && used_width + 1 > context.config.max_width();
2077 // If the last line of args contains comment, we cannot put the closing paren
2078 // on the same line.
2079 args_last_line_contains_comment = arg_str
2082 .map_or(false, |last_line| last_line.contains("//"));
2083 if closing_paren_overflow_max_width || args_last_line_contains_comment {
2084 result.push_str(&indent.to_string_with_newline(context.config));
2090 if let ast::FunctionRetTy::Ty(..) = fd.output {
2091 let ret_should_indent = match context.config.indent_style() {
2092 // If our args are block layout then we surely must have space.
2093 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
2094 _ if args_last_line_contains_comment => false,
2095 _ if result.contains('\n') || multi_line_ret_str => true,
2097 // If the return type would push over the max width, then put the return type on
2098 // a new line. With the +1 for the signature length an additional space between
2099 // the closing parenthesis of the argument and the arrow '->' is considered.
2100 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
2102 // If there is no where clause, take into account the space after the return type
2104 if where_clause.predicates.is_empty() {
2108 sig_length > context.config.max_width()
2111 let ret_indent = if ret_should_indent {
2112 let indent = if arg_str.is_empty() {
2113 // Aligning with non-existent args looks silly.
2114 force_new_line_for_brace = true;
2117 // FIXME: we might want to check that using the arg indent
2118 // doesn't blow our budget, and if it does, then fallback to
2119 // the where clause indent.
2123 result.push_str(&indent.to_string_with_newline(context.config));
2127 Indent::new(indent.block_indent, last_line_width(&result))
2130 if multi_line_ret_str || ret_should_indent {
2131 // Now that we know the proper indent and width, we need to
2132 // re-layout the return type.
2135 .rewrite(context, Shape::indented(ret_indent, context.config))?;
2136 result.push_str(&ret_str);
2138 result.push_str(&ret_str);
2141 // Comment between return type and the end of the decl.
2142 let snippet_lo = fd.output.span().hi();
2143 if where_clause.predicates.is_empty() {
2144 let snippet_hi = span.hi();
2145 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2146 // Try to preserve the layout of the original snippet.
2147 let original_starts_with_newline = snippet
2149 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2150 let original_ends_with_newline = snippet
2151 .rfind(|c| c != ' ')
2152 .map_or(false, |i| snippet[i..].ends_with('\n'));
2153 let snippet = snippet.trim();
2154 if !snippet.is_empty() {
2155 result.push(if original_starts_with_newline {
2160 result.push_str(snippet);
2161 if original_ends_with_newline {
2162 force_new_line_for_brace = true;
2168 let pos_before_where = match fd.output {
2169 ast::FunctionRetTy::Default(..) => args_span.hi(),
2170 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2173 let is_args_multi_lined = arg_str.contains('\n');
2175 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2176 let where_clause_str = rewrite_where_clause(
2179 context.config.brace_style(),
2180 Shape::indented(indent, context.config),
2186 is_args_multi_lined,
2188 // If there are neither where clause nor return type, we may be missing comments between
2190 if where_clause_str.is_empty() {
2191 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2192 match recover_missing_comment_in_span(
2193 mk_sp(args_span.hi(), ret_span.hi()),
2196 last_line_width(&result),
2198 Some(ref missing_comment) if !missing_comment.is_empty() => {
2199 result.push_str(missing_comment);
2200 force_new_line_for_brace = true;
2207 result.push_str(&where_clause_str);
2209 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2210 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2211 Some((result, force_new_line_for_brace))
2214 #[derive(Copy, Clone)]
2215 struct WhereClauseOption {
2216 suppress_comma: bool, // Force no trailing comma
2217 snuggle: bool, // Do not insert newline before `where`
2218 compress_where: bool, // Try single line where clause instead of vertical layout
2221 impl WhereClauseOption {
2222 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2226 compress_where: false,
2230 pub fn snuggled(current: &str) -> WhereClauseOption {
2232 suppress_comma: false,
2233 snuggle: last_line_width(current) == 1,
2234 compress_where: false,
2238 pub fn suppress_comma(&mut self) {
2239 self.suppress_comma = true
2242 pub fn compress_where(&mut self) {
2243 self.compress_where = true
2246 pub fn snuggle(&mut self) {
2252 context: &RewriteContext,
2254 explicit_self: Option<&ast::ExplicitSelf>,
2255 one_line_budget: usize,
2256 multi_line_budget: usize,
2261 generics_str_contains_newline: bool,
2262 ) -> Option<String> {
2263 let mut arg_item_strs = args
2266 arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent))
2267 .unwrap_or_else(|| context.snippet(arg.span()).to_owned())
2269 .collect::<Vec<_>>();
2271 // Account for sugary self.
2272 // FIXME: the comment for the self argument is dropped. This is blocked
2273 // on rust issue #27522.
2274 let min_args = explicit_self
2275 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2276 .map_or(1, |self_str| {
2277 arg_item_strs[0] = self_str;
2281 // Comments between args.
2282 let mut arg_items = Vec::new();
2284 arg_items.push(ListItem::from_str(""));
2287 // FIXME(#21): if there are no args, there might still be a comment, but
2288 // without spans for the comment or parens, there is no chance of
2289 // getting it right. You also don't get to put a comment on self, unless
2291 if args.len() >= min_args || variadic {
2292 let comment_span_start = if min_args == 2 {
2293 let second_arg_start = if arg_has_pattern(&args[1]) {
2294 args[1].pat.span.lo()
2296 args[1].ty.span.lo()
2298 let reduced_span = mk_sp(span.lo(), second_arg_start);
2300 context.snippet_provider.span_after_last(reduced_span, ",")
2305 enum ArgumentKind<'a> {
2306 Regular(&'a ast::Arg),
2310 let variadic_arg = if variadic {
2311 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2312 let variadic_start =
2313 context.snippet_provider.span_after(variadic_span, "...") - BytePos(3);
2314 Some(ArgumentKind::Variadic(variadic_start))
2319 let more_items = itemize_list(
2320 context.snippet_provider,
2321 args[min_args - 1..]
2323 .map(ArgumentKind::Regular)
2324 .chain(variadic_arg),
2328 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2329 ArgumentKind::Variadic(start) => start,
2332 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2333 ArgumentKind::Variadic(start) => start + BytePos(3),
2336 ArgumentKind::Regular(..) => None,
2337 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2344 arg_items.extend(more_items);
2347 let fits_in_one_line = !generics_str_contains_newline
2348 && (arg_items.is_empty()
2349 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2351 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2352 item.item = Some(arg);
2355 let last_line_ends_with_comment = arg_items
2358 .and_then(|item| item.post_comment.as_ref())
2359 .map_or(false, |s| s.trim().starts_with("//"));
2361 let (indent, trailing_comma) = match context.config.indent_style() {
2362 IndentStyle::Block if fits_in_one_line => {
2363 (indent.block_indent(context.config), SeparatorTactic::Never)
2365 IndentStyle::Block => (
2366 indent.block_indent(context.config),
2367 context.config.trailing_comma(),
2369 IndentStyle::Visual if last_line_ends_with_comment => {
2370 (arg_indent, context.config.trailing_comma())
2372 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2375 let tactic = definitive_tactic(
2377 context.config.fn_args_density().to_list_tactic(),
2381 let budget = match tactic {
2382 DefinitiveListTactic::Horizontal => one_line_budget,
2383 _ => multi_line_budget,
2386 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2388 let trailing_separator = if variadic {
2389 SeparatorTactic::Never
2393 let fmt = ListFormatting::new(Shape::legacy(budget, indent), context.config)
2395 .trailing_separator(trailing_separator)
2396 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2397 .preserve_newline(true);
2398 write_list(&arg_items, &fmt)
2401 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2402 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2403 ident != symbol::keywords::Invalid.ident()
2409 fn compute_budgets_for_args(
2410 context: &RewriteContext,
2414 newline_brace: bool,
2416 force_vertical_layout: bool,
2417 ) -> Option<((usize, usize, Indent))> {
2419 "compute_budgets_for_args {} {:?}, {}, {}",
2425 // Try keeping everything on the same line.
2426 if !result.contains('\n') && !force_vertical_layout {
2427 // 2 = `()`, 3 = `() `, space is before ret_string.
2428 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2429 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2439 let one_line_budget = context.budget(used_space);
2441 if one_line_budget > 0 {
2443 let (indent, multi_line_budget) = match context.config.indent_style() {
2444 IndentStyle::Block => {
2445 let indent = indent.block_indent(context.config);
2446 (indent, context.budget(indent.width() + 1))
2448 IndentStyle::Visual => {
2449 let indent = indent + result.len() + 1;
2450 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2451 (indent, context.budget(multi_line_overhead))
2455 return Some((one_line_budget, multi_line_budget, indent));
2459 // Didn't work. we must force vertical layout and put args on a newline.
2460 let new_indent = indent.block_indent(context.config);
2461 let used_space = match context.config.indent_style() {
2463 IndentStyle::Block => new_indent.width() + 1,
2464 // Account for `)` and possibly ` {`.
2465 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2467 Some((0, context.budget(used_space), new_indent))
2470 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2471 let predicate_count = where_clause.predicates.len();
2473 if config.where_single_line() && predicate_count == 1 {
2476 let brace_style = config.brace_style();
2478 brace_style == BraceStyle::AlwaysNextLine
2479 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2482 fn rewrite_generics(
2483 context: &RewriteContext,
2485 generics: &ast::Generics,
2487 ) -> Option<String> {
2488 // FIXME: convert bounds to where clauses where they get too big or if
2489 // there is a where clause at all.
2491 if generics.params.is_empty() {
2492 return Some(ident.to_owned());
2495 let params = generics.params.iter();
2496 overflow::rewrite_with_angle_brackets(context, ident, params, shape, generics.span)
2499 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2500 match config.indent_style() {
2501 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2502 IndentStyle::Block => {
2506 .block_indent(config.tab_spaces())
2507 .with_max_width(config)
2513 fn rewrite_where_clause_rfc_style(
2514 context: &RewriteContext,
2515 where_clause: &ast::WhereClause,
2518 span_end: Option<BytePos>,
2519 span_end_before_where: BytePos,
2520 where_clause_option: WhereClauseOption,
2521 is_args_multi_line: bool,
2522 ) -> Option<String> {
2523 let block_shape = shape.block().with_max_width(context.config);
2525 let (span_before, span_after) =
2526 missing_span_before_after_where(span_end_before_where, where_clause);
2527 let (comment_before, comment_after) =
2528 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2530 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2533 block_shape.indent.to_string_with_newline(context.config)
2536 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2538 let clause_shape = clause_shape.sub_width(1)?;
2539 // each clause on one line, trailing comma (except if suppress_comma)
2540 let span_start = where_clause.predicates[0].span().lo();
2541 // If we don't have the start of the next span, then use the end of the
2542 // predicates, but that means we miss comments.
2543 let len = where_clause.predicates.len();
2544 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2545 let span_end = span_end.unwrap_or(end_of_preds);
2546 let items = itemize_list(
2547 context.snippet_provider,
2548 where_clause.predicates.iter(),
2551 |pred| pred.span().lo(),
2552 |pred| pred.span().hi(),
2553 |pred| pred.rewrite(context, clause_shape),
2558 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2559 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2560 SeparatorTactic::Never
2562 context.config.trailing_comma()
2565 // shape should be vertical only and only if we have `where_single_line` option enabled
2566 // and the number of items of the where clause is equal to 1
2567 let shape_tactic = if where_single_line {
2568 DefinitiveListTactic::Horizontal
2570 DefinitiveListTactic::Vertical
2573 let fmt = ListFormatting::new(clause_shape, context.config)
2574 .tactic(shape_tactic)
2575 .trailing_separator(comma_tactic)
2576 .preserve_newline(true);
2577 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2579 let comment_separator = |comment: &str, shape: Shape| {
2580 if comment.is_empty() {
2583 shape.indent.to_string_with_newline(context.config)
2586 let newline_before_where = comment_separator(&comment_before, shape);
2587 let newline_after_where = comment_separator(&comment_after, clause_shape);
2590 let clause_sep = if where_clause_option.compress_where
2591 && comment_before.is_empty()
2592 && comment_after.is_empty()
2593 && !preds_str.contains('\n')
2594 && 6 + preds_str.len() <= shape.width
2595 || where_single_line
2599 clause_shape.indent.to_string_with_newline(context.config)
2602 "{}{}{}where{}{}{}{}",
2605 newline_before_where,
2606 newline_after_where,
2613 fn rewrite_where_clause(
2614 context: &RewriteContext,
2615 where_clause: &ast::WhereClause,
2616 brace_style: BraceStyle,
2620 span_end: Option<BytePos>,
2621 span_end_before_where: BytePos,
2622 where_clause_option: WhereClauseOption,
2623 is_args_multi_line: bool,
2624 ) -> Option<String> {
2625 if where_clause.predicates.is_empty() {
2626 return Some(String::new());
2629 if context.config.indent_style() == IndentStyle::Block {
2630 return rewrite_where_clause_rfc_style(
2636 span_end_before_where,
2637 where_clause_option,
2642 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2644 let offset = match context.config.indent_style() {
2645 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2646 // 6 = "where ".len()
2647 IndentStyle::Visual => shape.indent + extra_indent + 6,
2649 // FIXME: if indent_style != Visual, then the budgets below might
2650 // be out by a char or two.
2652 let budget = context.config.max_width() - offset.width();
2653 let span_start = where_clause.predicates[0].span().lo();
2654 // If we don't have the start of the next span, then use the end of the
2655 // predicates, but that means we miss comments.
2656 let len = where_clause.predicates.len();
2657 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2658 let span_end = span_end.unwrap_or(end_of_preds);
2659 let items = itemize_list(
2660 context.snippet_provider,
2661 where_clause.predicates.iter(),
2664 |pred| pred.span().lo(),
2665 |pred| pred.span().hi(),
2666 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2671 let item_vec = items.collect::<Vec<_>>();
2672 // FIXME: we don't need to collect here
2673 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2675 let mut comma_tactic = context.config.trailing_comma();
2676 // Kind of a hack because we don't usually have trailing commas in where clauses.
2677 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2678 comma_tactic = SeparatorTactic::Never;
2681 let fmt = ListFormatting::new(Shape::legacy(budget, offset), context.config)
2683 .trailing_separator(comma_tactic)
2684 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2685 .preserve_newline(true);
2686 let preds_str = write_list(&item_vec, &fmt)?;
2688 let end_length = if terminator == "{" {
2689 // If the brace is on the next line we don't need to count it otherwise it needs two
2692 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2693 BraceStyle::PreferSameLine => 2,
2695 } else if terminator == "=" {
2700 if density == Density::Tall
2701 || preds_str.contains('\n')
2702 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2706 (shape.indent + extra_indent).to_string(context.config),
2710 Some(format!(" where {}", preds_str))
2714 fn missing_span_before_after_where(
2715 before_item_span_end: BytePos,
2716 where_clause: &ast::WhereClause,
2718 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2720 let pos_after_where = where_clause.span.lo() + BytePos(5);
2721 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2722 (missing_span_before, missing_span_after)
2725 fn rewrite_comments_before_after_where(
2726 context: &RewriteContext,
2727 span_before_where: Span,
2728 span_after_where: Span,
2730 ) -> Option<(String, String)> {
2731 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2732 let after_comment = rewrite_missing_comment(
2734 shape.block_indent(context.config.tab_spaces()),
2737 Some((before_comment, after_comment))
2741 context: &RewriteContext,
2744 vis: &ast::Visibility,
2748 format_visibility(context, vis),
2750 rewrite_ident(context, ident)
2754 #[derive(PartialEq, Eq, Clone, Copy)]
2762 context: &RewriteContext,
2763 generics: &ast::Generics,
2764 brace_style: BraceStyle,
2765 brace_pos: BracePos,
2769 ) -> Option<String> {
2770 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2771 let mut result = rewrite_generics(context, "", generics, shape)?;
2773 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2774 let budget = context.budget(last_line_used_width(&result, offset.width()));
2775 let mut option = WhereClauseOption::snuggled(&result);
2776 if brace_pos == BracePos::None {
2777 option.suppress_comma = true;
2779 // If the generics are not parameterized then generics.span.hi() == 0,
2780 // so we use span.lo(), which is the position after `struct Foo`.
2781 let span_end_before_where = if !generics.params.is_empty() {
2786 let where_clause_str = rewrite_where_clause(
2788 &generics.where_clause,
2790 Shape::legacy(budget, offset.block_only()),
2794 span_end_before_where,
2798 result.push_str(&where_clause_str);
2799 brace_pos == BracePos::ForceSameLine
2800 || brace_style == BraceStyle::PreferSameLine
2801 || (generics.where_clause.predicates.is_empty()
2802 && trimmed_last_line_width(&result) == 1)
2804 brace_pos == BracePos::ForceSameLine
2805 || trimmed_last_line_width(&result) == 1
2806 || brace_style != BraceStyle::AlwaysNextLine
2808 if brace_pos == BracePos::None {
2809 return Some(result);
2811 let total_used_width = last_line_used_width(&result, used_width);
2812 let remaining_budget = context.budget(total_used_width);
2813 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2814 // and hence we take the closer into account as well for one line budget.
2815 // We assume that the closer has the same length as the opener.
2816 let overhead = if brace_pos == BracePos::ForceSameLine {
2823 let forbid_same_line_brace = overhead > remaining_budget;
2824 if !forbid_same_line_brace && same_line_brace {
2828 result.push_str(&offset.block_only().to_string(context.config));
2835 impl Rewrite for ast::ForeignItem {
2836 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2837 let attrs_str = self.attrs.rewrite(context, shape)?;
2838 // Drop semicolon or it will be interpreted as comment.
2839 // FIXME: this may be a faulty span from libsyntax.
2840 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2842 let item_str = match self.node {
2843 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => rewrite_fn_base(
2847 &FnSig::new(fn_decl, generics, self.vis.clone()),
2852 .map(|(s, _)| format!("{};", s)),
2853 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2854 // FIXME(#21): we're dropping potential comments in between the
2855 // function keywords here.
2856 let vis = format_visibility(context, &self.vis);
2857 let mut_str = if is_mutable { "mut " } else { "" };
2858 let prefix = format!(
2862 rewrite_ident(context, self.ident)
2865 rewrite_assign_rhs(context, prefix, &**ty, shape.sub_width(1)?).map(|s| s + ";")
2867 ast::ForeignItemKind::Ty => {
2868 let vis = format_visibility(context, &self.vis);
2872 rewrite_ident(context, self.ident)
2875 ast::ForeignItemKind::Macro(ref mac) => {
2876 rewrite_macro(mac, None, context, shape, MacroPosition::Item)
2880 let missing_span = if self.attrs.is_empty() {
2881 mk_sp(self.span.lo(), self.span.lo())
2883 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2885 combine_strs_with_missing_comments(
2896 /// Rewrite an inline mod.
2897 pub fn rewrite_mod(context: &RewriteContext, item: &ast::Item) -> String {
2898 let mut result = String::with_capacity(32);
2899 result.push_str(&*format_visibility(context, &item.vis));
2900 result.push_str("mod ");
2901 result.push_str(rewrite_ident(context, item.ident));
2906 /// Rewrite `extern crate foo;` WITHOUT attributes.
2907 pub fn rewrite_extern_crate(context: &RewriteContext, item: &ast::Item) -> Option<String> {
2908 assert!(is_extern_crate(item));
2909 let new_str = context.snippet(item.span);
2910 Some(if contains_comment(new_str) {
2913 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
2914 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
2918 /// Returns true for `mod foo;`, false for `mod foo { .. }`.
2919 pub fn is_mod_decl(item: &ast::Item) -> bool {
2921 ast::ItemKind::Mod(ref m) => m.inner.hi() != item.span.hi(),
2926 pub fn is_use_item(item: &ast::Item) -> bool {
2928 ast::ItemKind::Use(_) => true,
2933 pub fn is_extern_crate(item: &ast::Item) -> bool {
2935 ast::ItemKind::ExternCrate(..) => true,