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.
18 use syntax::{abi, ast, ptr, symbol};
19 use syntax::codemap::{self, BytePos, Span};
22 use codemap::{LineRangeUtils, SpanUtils};
23 use comment::{combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
24 recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented};
25 use config::{BraceStyle, Config, Density, IndentStyle};
26 use expr::{format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs,
27 rewrite_call_inner, ExprType};
28 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, ListItem, Separator};
29 use rewrite::{Rewrite, RewriteContext};
30 use shape::{Indent, Shape};
32 use types::join_bounds;
33 use utils::{colon_spaces, contains_skip, first_line_width, format_abi, format_constness,
34 format_defaultness, format_mutability, format_unsafety, format_visibility,
35 is_attributes_extendable, last_line_contains_single_line_comment,
36 last_line_used_width, last_line_width, mk_sp, semicolon_for_expr, starts_with_newline,
37 stmt_expr, trimmed_last_line_width};
38 use vertical::rewrite_with_alignment;
39 use visitor::FmtVisitor;
41 const DEFAULT_VISIBILITY: ast::Visibility = codemap::Spanned {
42 node: ast::VisibilityKind::Inherited,
43 span: codemap::DUMMY_SP,
46 fn type_annotation_separator(config: &Config) -> &str {
47 colon_spaces(config.space_before_colon(), config.space_after_colon())
50 // Statements of the form
51 // let pat: ty = init;
52 impl Rewrite for ast::Local {
53 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
55 "Local::rewrite {:?} {} {:?}",
56 self, shape.width, shape.indent
59 skip_out_of_file_lines_range!(context, self.span);
61 if contains_skip(&self.attrs) {
65 let attrs_str = self.attrs.rewrite(context, shape)?;
66 let mut result = if attrs_str.is_empty() {
69 combine_strs_with_missing_comments(
74 self.attrs.last().map(|a| a.span.hi()).unwrap(),
83 let pat_shape = shape.offset_left(4)?;
85 let pat_shape = pat_shape.sub_width(1)?;
86 let pat_str = self.pat.rewrite(context, pat_shape)?;
87 result.push_str(&pat_str);
89 // String that is placed within the assignment pattern and expression.
91 let mut infix = String::with_capacity(32);
93 if let Some(ref ty) = self.ty {
94 let separator = type_annotation_separator(context.config);
95 let indent = shape.indent + last_line_width(&result) + separator.len();
97 let budget = shape.width.checked_sub(indent.width() + 1)?;
98 let rewrite = ty.rewrite(context, Shape::legacy(budget, indent))?;
100 infix.push_str(separator);
101 infix.push_str(&rewrite);
104 if self.init.is_some() {
105 infix.push_str(" =");
111 result.push_str(&infix);
113 if let Some(ref ex) = self.init {
114 // 1 = trailing semicolon;
115 let nested_shape = shape.sub_width(1)?;
117 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
125 // TODO convert to using rewrite style rather than visitor
126 // TODO format modules in this style
129 keyword: &'static str,
130 abi: Cow<'static, str>,
131 vis: Option<&'a ast::Visibility>,
132 body: Vec<BodyElement<'a>>,
137 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
140 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
144 .map(|i| BodyElement::ForeignItem(i))
151 enum BodyElement<'a> {
152 // Stmt(&'a ast::Stmt),
153 // Field(&'a ast::Field),
154 // Variant(&'a ast::Variant),
155 // Item(&'a ast::Item),
156 ForeignItem(&'a ast::ForeignItem),
159 /// Represents a fn's signature.
160 pub struct FnSig<'a> {
161 decl: &'a ast::FnDecl,
162 generics: &'a ast::Generics,
164 constness: ast::Constness,
165 defaultness: ast::Defaultness,
166 unsafety: ast::Unsafety,
167 visibility: ast::Visibility,
172 decl: &'a ast::FnDecl,
173 generics: &'a ast::Generics,
174 vis: ast::Visibility,
180 constness: ast::Constness::NotConst,
181 defaultness: ast::Defaultness::Final,
182 unsafety: ast::Unsafety::Normal,
187 pub fn from_method_sig(
188 method_sig: &'a ast::MethodSig,
189 generics: &'a ast::Generics,
192 unsafety: method_sig.unsafety,
193 constness: method_sig.constness.node,
194 defaultness: ast::Defaultness::Final,
196 decl: &*method_sig.decl,
198 visibility: DEFAULT_VISIBILITY,
203 fn_kind: &'a visit::FnKind,
204 generics: &'a ast::Generics,
205 decl: &'a ast::FnDecl,
206 defualtness: ast::Defaultness,
209 visit::FnKind::ItemFn(_, unsafety, constness, abi, visibility, _) => FnSig {
213 constness: constness.node,
214 defaultness: defualtness,
216 visibility: visibility.clone(),
218 visit::FnKind::Method(_, method_sig, vis, _) => {
219 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
220 fn_sig.defaultness = defualtness;
221 if let Some(vis) = vis {
222 fn_sig.visibility = vis.clone();
230 fn to_str(&self, context: &RewriteContext) -> String {
231 let mut result = String::with_capacity(128);
232 // Vis defaultness constness unsafety abi.
233 result.push_str(&*format_visibility(&self.visibility));
234 result.push_str(format_defaultness(self.defaultness));
235 result.push_str(format_constness(self.constness));
236 result.push_str(format_unsafety(self.unsafety));
237 result.push_str(&format_abi(
239 context.config.force_explicit_abi(),
246 impl<'a> FmtVisitor<'a> {
247 fn format_item(&mut self, item: &Item) {
248 self.buffer.push_str(&item.abi);
250 let snippet = self.snippet(item.span);
251 let brace_pos = snippet.find_uncommented("{").unwrap();
254 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
255 // FIXME: this skips comments between the extern keyword and the opening
257 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
258 self.block_indent = self.block_indent.block_indent(self.config);
260 if item.body.is_empty() {
261 self.format_missing_no_indent(item.span.hi() - BytePos(1));
262 self.block_indent = self.block_indent.block_unindent(self.config);
263 let indent_str = self.block_indent.to_string(self.config);
264 self.push_str(&indent_str);
266 for item in &item.body {
267 self.format_body_element(item);
270 self.block_indent = self.block_indent.block_unindent(self.config);
271 self.format_missing_with_indent(item.span.hi() - BytePos(1));
276 self.last_pos = item.span.hi();
279 fn format_body_element(&mut self, element: &BodyElement) {
281 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
285 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
286 let item = Item::from_foreign_mod(fm, span, self.config);
287 self.format_item(&item);
290 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
291 let rewrite = item.rewrite(&self.get_context(), self.shape());
292 self.push_rewrite(item.span(), rewrite);
293 self.last_pos = item.span.hi();
303 ) -> Option<String> {
304 let context = self.get_context();
306 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
308 let (mut result, force_newline_brace) =
309 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
312 if self.config.brace_style() == BraceStyle::AlwaysNextLine || force_newline_brace
313 || last_line_width(&result) + 2 > self.shape().width
315 newline_brace = true;
316 } else if !result.contains('\n') {
317 newline_brace = false;
320 // Prepare for the function body by possibly adding a newline and
322 // FIXME we'll miss anything between the end of the signature and the
323 // start of the body, but we need more spans from the compiler to solve
326 result.push_str(&indent.to_string_with_newline(self.config));
331 self.single_line_fn(&result, block).or_else(|| Some(result))
334 pub fn rewrite_required_fn(
338 sig: &ast::MethodSig,
339 generics: &ast::Generics,
341 ) -> Option<String> {
342 // Drop semicolon or it will be interpreted as comment.
343 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
344 let context = self.get_context();
346 let (mut result, _) = rewrite_fn_base(
350 &FnSig::from_method_sig(sig, generics),
356 // Re-attach semicolon
362 fn single_line_fn(&self, fn_str: &str, block: &ast::Block) -> Option<String> {
363 if fn_str.contains('\n') {
367 let codemap = self.get_context().codemap;
369 if self.config.empty_item_single_line() && is_empty_block(block, codemap)
370 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
372 return Some(format!("{}{{}}", fn_str));
375 if self.config.fn_single_line() && is_simple_block_stmt(block, codemap) {
377 if let Some(stmt) = block.stmts.first() {
378 match stmt_expr(stmt) {
380 let suffix = if semicolon_for_expr(&self.get_context(), e) {
386 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
388 .or_else(|| Some(self.snippet(e.span).to_owned()))
390 None => stmt.rewrite(&self.get_context(), self.shape()),
397 if let Some(res) = rewrite {
398 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
399 if !res.contains('\n') && width <= self.config.max_width() {
400 return Some(format!("{}{{ {} }}", fn_str, res));
408 pub fn visit_static(&mut self, static_parts: &StaticParts) {
409 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
410 self.push_rewrite(static_parts.span, rewrite);
413 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
414 let is_tuple = struct_parts.def.is_tuple();
415 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
416 .map(|s| if is_tuple { s + ";" } else { s });
417 self.push_rewrite(struct_parts.span, rewrite);
423 vis: &ast::Visibility,
424 enum_def: &ast::EnumDef,
425 generics: &ast::Generics,
428 let enum_header = format_header("enum ", ident, vis);
429 self.push_str(&enum_header);
431 let enum_snippet = self.snippet(span);
432 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
433 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
434 let generics_str = format_generics(
437 self.config.brace_style(),
438 if enum_def.variants.is_empty() {
439 BracePos::ForceSameLine
444 mk_sp(span.lo(), body_start),
445 last_line_width(&enum_header),
447 self.push_str(&generics_str);
449 self.last_pos = body_start;
451 self.block_indent = self.block_indent.block_indent(self.config);
452 let variant_list = self.format_variant_list(enum_def, body_start, span.hi() - BytePos(1));
454 Some(ref body_str) => self.push_str(body_str),
455 None => self.format_missing_no_indent(span.hi() - BytePos(1)),
457 self.block_indent = self.block_indent.block_unindent(self.config);
459 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
460 let indent_str = self.block_indent.to_string(self.config);
461 self.push_str(&indent_str);
464 self.last_pos = span.hi();
467 // Format the body of an enum definition
468 fn format_variant_list(
470 enum_def: &ast::EnumDef,
473 ) -> Option<String> {
474 if enum_def.variants.is_empty() {
477 let mut result = String::with_capacity(1024);
478 let indentation = self.block_indent.to_string_with_newline(self.config);
479 result.push_str(&indentation);
481 let itemize_list_with = |one_line_width: usize| {
483 self.snippet_provider,
484 enum_def.variants.iter(),
488 if !f.node.attrs.is_empty() {
489 f.node.attrs[0].span.lo()
495 |f| self.format_variant(f, one_line_width),
501 let mut items: Vec<_> =
502 itemize_list_with(self.config.width_heuristics().struct_variant_width);
503 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
504 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
505 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
506 if has_multiline_variant && has_single_line_variant {
507 items = itemize_list_with(0);
510 let shape = self.shape().sub_width(2)?;
511 let fmt = ListFormatting {
512 tactic: DefinitiveListTactic::Vertical,
514 trailing_separator: self.config.trailing_comma(),
515 separator_place: SeparatorPlace::Back,
517 ends_with_newline: true,
518 preserve_newline: true,
522 let list = write_list(&items, &fmt)?;
523 result.push_str(&list);
528 // Variant of an enum.
529 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
530 if contains_skip(&field.node.attrs) {
531 let lo = field.node.attrs[0].span.lo();
532 let span = mk_sp(lo, field.span.hi());
533 return Some(self.snippet(span).to_owned());
536 let context = self.get_context();
538 let shape = self.shape().sub_width(1)?;
539 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
544 .map_or(field.span.lo(), |attr| attr.span.hi());
545 let span = mk_sp(lo, field.span.lo());
547 let variant_body = match field.node.data {
548 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
550 &StructParts::from_variant(field),
552 Some(one_line_width),
554 ast::VariantData::Unit(..) => {
555 if let Some(ref expr) = field.node.disr_expr {
556 let lhs = format!("{} =", field.node.name);
557 rewrite_assign_rhs(&context, lhs, &**expr, shape)?
559 field.node.name.to_string()
564 combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
569 context: &RewriteContext,
572 where_span_end: Option<BytePos>,
573 ) -> Option<String> {
574 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
575 let mut result = String::with_capacity(128);
576 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
577 let sep = offset.to_string_with_newline(context.config);
578 result.push_str(&ref_and_type);
580 let where_budget = if result.contains('\n') {
581 context.config.max_width()
583 context.budget(last_line_width(&result))
585 let option = WhereClauseOption::snuggled(&ref_and_type);
586 let where_clause_str = rewrite_where_clause(
588 &generics.where_clause,
589 context.config.brace_style(),
590 Shape::legacy(where_budget, offset.block_only()),
599 // If there is no where clause, we may have missing comments between the trait name and
600 // the opening brace.
601 if generics.where_clause.predicates.is_empty() {
602 if let Some(hi) = where_span_end {
603 match recover_missing_comment_in_span(
604 mk_sp(self_ty.span.hi(), hi),
605 Shape::indented(offset, context.config),
607 last_line_width(&result),
609 Some(ref missing_comment) if !missing_comment.is_empty() => {
610 result.push_str(missing_comment);
617 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
618 result.push_str(&where_clause_str);
619 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
620 result.push_str(&format!("{}{{{}}}", &sep, &sep));
622 result.push_str(" {}");
627 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
628 let width = offset.block_indent + context.config.tab_spaces() - 1;
629 let where_indent = Indent::new(0, width);
630 result.push_str(&where_indent.to_string_with_newline(context.config));
632 result.push_str(&where_clause_str);
634 let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
635 match context.config.brace_style() {
636 _ if need_newline => result.push_str(&sep),
637 BraceStyle::AlwaysNextLine => result.push_str(&sep),
638 BraceStyle::PreferSameLine => result.push(' '),
639 BraceStyle::SameLineWhere => {
640 if !where_clause_str.is_empty() {
641 result.push_str(&sep);
650 let snippet = context.snippet(item.span);
651 let open_pos = snippet.find_uncommented("{")? + 1;
653 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
654 let mut visitor = FmtVisitor::from_context(context);
655 visitor.block_indent = offset.block_only().block_indent(context.config);
656 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
658 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
660 visitor.visit_impl_item(item);
663 visitor.format_missing(item.span.hi() - BytePos(1));
665 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
666 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
668 result.push_str(&inner_indent_str);
669 result.push_str(visitor.buffer.to_string().trim());
670 result.push_str(&outer_indent_str);
673 if result.ends_with('{') {
674 result.push_str(&sep);
684 fn is_impl_single_line(
685 context: &RewriteContext,
686 items: &[ast::ImplItem],
688 where_clause_str: &str,
691 let snippet = context.snippet(item.span);
692 let open_pos = snippet.find_uncommented("{")? + 1;
695 context.config.empty_item_single_line() && items.is_empty() && !result.contains('\n')
696 && result.len() + where_clause_str.len() <= context.config.max_width()
697 && !contains_comment(&snippet[open_pos..]),
701 fn format_impl_ref_and_type(
702 context: &RewriteContext,
705 ) -> Option<String> {
706 if let ast::ItemKind::Impl(
716 let mut result = String::with_capacity(128);
718 result.push_str(&format_visibility(&item.vis));
719 result.push_str(format_defaultness(defaultness));
720 result.push_str(format_unsafety(unsafety));
721 result.push_str("impl");
723 let lo = context.snippet_provider.span_after(item.span, "impl");
724 let hi = match *trait_ref {
725 Some(ref tr) => tr.path.span.lo(),
726 None => self_ty.span.lo(),
728 let shape = generics_shape_from_config(
730 Shape::indented(offset + last_line_width(&result), context.config),
733 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
735 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
737 let polarity_str = if polarity == ast::ImplPolarity::Negative {
743 if let Some(ref trait_ref) = *trait_ref {
744 let result_len = result.len();
745 if let Some(trait_ref_str) = rewrite_trait_ref(
754 result.push_str(&trait_ref_str);
757 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
758 result.push_str(&rewrite_trait_ref(
769 result.push_str(&generics_str);
772 // Try to put the self type in a single line.
774 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
775 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
776 // If there is no where clause adapt budget for type formatting to take space and curly
777 // brace into account.
778 match context.config.brace_style() {
779 BraceStyle::AlwaysNextLine => 0,
785 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
786 // 1 = space before the type.
787 let budget = context.budget(used_space + 1);
788 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
789 if !self_ty_str.contains('\n') {
790 if trait_ref.is_some() {
791 result.push_str(" for ");
795 result.push_str(&self_ty_str);
800 // Couldn't fit the self type on a single line, put it on a new line.
802 // Add indentation of one additional tab.
803 let new_line_offset = offset.block_indent(context.config);
804 result.push_str(&new_line_offset.to_string(context.config));
805 if trait_ref.is_some() {
806 result.push_str("for ");
808 let budget = context.budget(last_line_width(&result));
809 let type_offset = match context.config.indent_style() {
810 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
811 IndentStyle::Block => new_line_offset,
813 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
820 fn rewrite_trait_ref(
821 context: &RewriteContext,
822 trait_ref: &ast::TraitRef,
828 ) -> Option<String> {
829 // 1 = space between generics and trait_ref
830 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
831 let shape = Shape::indented(offset + used_space, context.config);
832 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
833 if !(retry && trait_ref_str.contains('\n')) {
836 generics_str, polarity_str, &trait_ref_str
840 // We could not make enough space for trait_ref, so put it on new line.
842 let offset = offset.block_indent(context.config);
843 let shape = Shape::indented(offset, context.config);
844 let trait_ref_str = trait_ref.rewrite(context, shape)?;
848 &offset.to_string(context.config),
857 pub struct StructParts<'a> {
860 vis: &'a ast::Visibility,
861 def: &'a ast::VariantData,
862 generics: Option<&'a ast::Generics>,
866 impl<'a> StructParts<'a> {
867 fn format_header(&self) -> String {
868 format_header(self.prefix, self.ident, self.vis)
871 fn from_variant(variant: &'a ast::Variant) -> Self {
874 ident: variant.node.name,
875 vis: &DEFAULT_VISIBILITY,
876 def: &variant.node.data,
882 pub fn from_item(item: &'a ast::Item) -> Self {
883 let (prefix, def, generics) = match item.node {
884 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
885 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
893 generics: Some(generics),
900 context: &RewriteContext,
901 struct_parts: &StructParts,
903 one_line_width: Option<usize>,
904 ) -> Option<String> {
905 match *struct_parts.def {
906 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
907 ast::VariantData::Tuple(ref fields, _) => {
908 format_tuple_struct(context, struct_parts, fields, offset)
910 ast::VariantData::Struct(ref fields, _) => {
911 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
916 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
917 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
920 let mut result = String::with_capacity(128);
921 let header = format!(
923 format_visibility(&item.vis),
924 format_unsafety(unsafety),
928 result.push_str(&header);
930 let body_lo = context.snippet_provider.span_after(item.span, "{");
932 let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
934 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
935 result.push_str(&generics_str);
937 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
938 if !type_param_bounds.is_empty() {
939 let ident_hi = context
941 .span_after(item.span, &format!("{}", item.ident));
942 let bound_hi = type_param_bounds.last().unwrap().span().hi();
943 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
944 if contains_comment(snippet) {
948 let trait_bound_str = rewrite_trait_bounds(
951 Shape::indented(offset, context.config),
953 // If the trait, generics, and trait bound cannot fit on the same line,
954 // put the trait bounds on an indented new line
955 if offset.width() + last_line_width(&result) + trait_bound_str.len()
956 > context.config.comment_width()
958 let trait_indent = offset.block_only().block_indent(context.config);
959 result.push_str(&trait_indent.to_string_with_newline(context.config));
961 result.push_str(&trait_bound_str);
964 if context.config.indent_style() == IndentStyle::Block && result.is_empty() {
970 let where_budget = context.budget(last_line_width(&result));
971 let pos_before_where = if type_param_bounds.is_empty() {
972 generics.where_clause.span.lo()
974 type_param_bounds[type_param_bounds.len() - 1].span().hi()
976 let option = WhereClauseOption::snuggled(&generics_str);
977 let where_clause_str = rewrite_where_clause(
979 &generics.where_clause,
980 context.config.brace_style(),
981 Shape::legacy(where_budget, offset.block_only()),
989 // If the where clause cannot fit on the same line,
990 // put the where clause on a new line
991 if !where_clause_str.contains('\n')
992 && last_line_width(&result) + where_clause_str.len() + offset.width()
993 > context.config.comment_width()
995 let width = offset.block_indent + context.config.tab_spaces() - 1;
996 let where_indent = Indent::new(0, width);
997 result.push_str(&where_indent.to_string_with_newline(context.config));
999 result.push_str(&where_clause_str);
1001 if generics.where_clause.predicates.is_empty() {
1002 let item_snippet = context.snippet(item.span);
1003 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1005 let comment_hi = body_lo - BytePos(1);
1006 let comment_lo = item.span.lo() + BytePos(lo as u32);
1007 if comment_lo < comment_hi {
1008 match recover_missing_comment_in_span(
1009 mk_sp(comment_lo, comment_hi),
1010 Shape::indented(offset, context.config),
1012 last_line_width(&result),
1014 Some(ref missing_comment) if !missing_comment.is_empty() => {
1015 result.push_str(missing_comment);
1023 match context.config.brace_style() {
1024 _ if last_line_contains_single_line_comment(&result) => {
1025 result.push_str(&offset.to_string_with_newline(context.config));
1027 BraceStyle::AlwaysNextLine => {
1028 result.push_str(&offset.to_string_with_newline(context.config));
1030 BraceStyle::PreferSameLine => result.push(' '),
1031 BraceStyle::SameLineWhere => {
1032 if !where_clause_str.is_empty()
1033 && (!trait_items.is_empty() || result.contains('\n'))
1035 result.push_str(&offset.to_string_with_newline(context.config));
1043 let snippet = context.snippet(item.span);
1044 let open_pos = snippet.find_uncommented("{")? + 1;
1046 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1047 let mut visitor = FmtVisitor::from_context(context);
1048 visitor.block_indent = offset.block_only().block_indent(context.config);
1049 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1051 for item in trait_items {
1052 visitor.visit_trait_item(item);
1055 visitor.format_missing(item.span.hi() - BytePos(1));
1057 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
1058 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
1060 result.push_str(&inner_indent_str);
1061 result.push_str(visitor.buffer.to_string().trim());
1062 result.push_str(&outer_indent_str);
1063 } else if result.contains('\n') {
1074 pub fn format_trait_alias(
1075 context: &RewriteContext,
1077 generics: &ast::Generics,
1078 ty_param_bounds: &ast::TyParamBounds,
1080 ) -> Option<String> {
1081 let alias = ident.name.as_str();
1082 // 6 = "trait ", 2 = " ="
1083 let g_shape = shape.offset_left(6 + alias.len())?.sub_width(2)?;
1084 let generics_str = rewrite_generics(context, generics, g_shape, generics.span)?;
1085 let lhs = format!("trait {}{} =", alias, generics_str);
1087 rewrite_assign_rhs(context, lhs, ty_param_bounds, shape.sub_width(1)?).map(|s| s + ";")
1090 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1091 let header_str = format_header(p.prefix, p.ident, p.vis);
1092 let generics_str = if let Some(generics) = p.generics {
1093 let hi = if generics.where_clause.predicates.is_empty() {
1096 generics.where_clause.span.hi()
1101 context.config.brace_style(),
1104 mk_sp(generics.span.lo(), hi),
1105 last_line_width(&header_str),
1110 Some(format!("{}{};", header_str, generics_str))
1113 pub fn format_struct_struct(
1114 context: &RewriteContext,
1115 struct_parts: &StructParts,
1116 fields: &[ast::StructField],
1118 one_line_width: Option<usize>,
1119 ) -> Option<String> {
1120 let mut result = String::with_capacity(1024);
1121 let span = struct_parts.span;
1123 let header_str = struct_parts.format_header();
1124 result.push_str(&header_str);
1126 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1127 let body_lo = context.snippet_provider.span_after(span, "{");
1129 let generics_str = match struct_parts.generics {
1130 Some(g) => format_generics(
1133 context.config.brace_style(),
1134 if fields.is_empty() {
1135 BracePos::ForceSameLine
1140 mk_sp(header_hi, body_lo),
1141 last_line_width(&result),
1144 // 3 = ` {}`, 2 = ` {`.
1145 let overhead = if fields.is_empty() { 3 } else { 2 };
1146 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1147 || context.config.max_width() < overhead + result.len()
1149 format!("\n{}{{", offset.block_only().to_string(context.config))
1156 let overhead = if fields.is_empty() { 1 } else { 0 };
1157 let total_width = result.len() + generics_str.len() + overhead;
1158 if !generics_str.is_empty() && !generics_str.contains('\n')
1159 && total_width > context.config.max_width()
1162 result.push_str(&offset.to_string(context.config));
1163 result.push_str(generics_str.trim_left());
1165 result.push_str(&generics_str);
1168 if fields.is_empty() {
1169 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1170 if snippet.trim().is_empty() {
1172 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1174 result.push_str(snippet.trim_right());
1176 result.push_str(&offset.to_string(context.config));
1178 result.push_str(snippet);
1181 return Some(result);
1185 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1186 let one_line_budget =
1187 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1189 let items_str = rewrite_with_alignment(
1192 Shape::indented(offset, context.config).sub_width(1)?,
1193 mk_sp(body_lo, span.hi()),
1197 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget
1198 && !last_line_contains_single_line_comment(&items_str)
1200 Some(format!("{} {} }}", result, items_str))
1206 .block_indent(context.config)
1207 .to_string(context.config),
1209 offset.to_string(context.config)
1214 fn get_bytepos_after_visibility(vis: &ast::Visibility, default_span: Span) -> BytePos {
1216 ast::VisibilityKind::Crate(..) | ast::VisibilityKind::Restricted { .. } => vis.span.hi(),
1217 _ => default_span.lo(),
1221 fn format_tuple_struct(
1222 context: &RewriteContext,
1223 struct_parts: &StructParts,
1224 fields: &[ast::StructField],
1226 ) -> Option<String> {
1227 let mut result = String::with_capacity(1024);
1228 let span = struct_parts.span;
1230 let header_str = struct_parts.format_header();
1231 result.push_str(&header_str);
1233 let body_lo = if fields.is_empty() {
1234 let lo = get_bytepos_after_visibility(struct_parts.vis, span);
1237 .span_after(mk_sp(lo, span.hi()), "(")
1241 let body_hi = if fields.is_empty() {
1244 .span_after(mk_sp(body_lo, span.hi()), ")")
1246 // This is a dirty hack to work around a missing `)` from the span of the last field.
1247 let last_arg_span = fields[fields.len() - 1].span;
1248 if context.snippet(last_arg_span).ends_with(')') {
1253 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1257 let where_clause_str = match struct_parts.generics {
1259 let budget = context.budget(last_line_width(&header_str));
1260 let shape = Shape::legacy(budget, offset);
1261 let g_span = mk_sp(span.lo(), body_lo);
1262 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1263 result.push_str(&generics_str);
1265 let where_budget = context.budget(last_line_width(&result));
1266 let option = WhereClauseOption::new(true, false);
1267 rewrite_where_clause(
1269 &generics.where_clause,
1270 context.config.brace_style(),
1271 Shape::legacy(where_budget, offset.block_only()),
1272 Density::Compressed,
1280 None => "".to_owned(),
1283 if fields.is_empty() {
1285 let used_width = last_line_used_width(&result, offset.width()) + 3;
1286 if used_width > context.config.max_width() {
1288 result.push_str(&offset
1289 .block_indent(context.config)
1290 .to_string(context.config))
1293 let snippet = context.snippet(mk_sp(
1297 .span_before(mk_sp(body_lo, span.hi()), ")"),
1299 if snippet.is_empty() {
1301 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1302 result.push_str(snippet.trim_right());
1304 result.push_str(&offset.to_string(context.config));
1306 result.push_str(snippet);
1310 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1311 let fields = &fields.iter().collect::<Vec<_>>()[..];
1312 let one_line_width = context.config.width_heuristics().fn_call_width;
1313 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1316 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1317 && (result.contains('\n')
1318 || offset.block_indent + result.len() + where_clause_str.len() + 1
1319 > context.config.max_width())
1321 // We need to put the where clause on a new line, but we didn't
1322 // know that earlier, so the where clause will not be indented properly.
1325 .push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1326 .to_string(context.config));
1328 result.push_str(&where_clause_str);
1333 pub fn rewrite_type_alias(
1334 context: &RewriteContext,
1338 generics: &ast::Generics,
1339 vis: &ast::Visibility,
1341 ) -> Option<String> {
1342 let mut result = String::with_capacity(128);
1344 result.push_str(&format_visibility(vis));
1345 result.push_str("type ");
1346 result.push_str(&ident.to_string());
1349 let g_shape = Shape::indented(indent, context.config)
1350 .offset_left(result.len())?
1353 context.snippet_provider.span_after(span, "type"),
1356 let generics_str = rewrite_generics(context, generics, g_shape, g_span)?;
1357 result.push_str(&generics_str);
1359 let where_budget = context.budget(last_line_width(&result));
1360 let option = WhereClauseOption::snuggled(&result);
1361 let where_clause_str = rewrite_where_clause(
1363 &generics.where_clause,
1364 context.config.brace_style(),
1365 Shape::legacy(where_budget, indent),
1373 result.push_str(&where_clause_str);
1374 if where_clause_str.is_empty() {
1375 result.push_str(" =");
1377 result.push_str(&format!(
1379 indent.to_string_with_newline(context.config)
1384 let ty_shape = Shape::indented(indent, context.config).sub_width(1)?;
1385 rewrite_assign_rhs(context, result, ty, ty_shape).map(|s| s + ";")
1388 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1390 if config.space_before_colon() { " " } else { "" },
1391 if config.space_after_colon() { " " } else { "" },
1395 pub fn rewrite_struct_field_prefix(
1396 context: &RewriteContext,
1397 field: &ast::StructField,
1398 ) -> Option<String> {
1399 let vis = format_visibility(&field.vis);
1400 let type_annotation_spacing = type_annotation_spacing(context.config);
1401 Some(match field.ident {
1402 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1403 None => format!("{}", vis),
1407 impl Rewrite for ast::StructField {
1408 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1409 rewrite_struct_field(context, self, shape, 0)
1413 pub fn rewrite_struct_field(
1414 context: &RewriteContext,
1415 field: &ast::StructField,
1417 lhs_max_width: usize,
1418 ) -> Option<String> {
1419 if contains_skip(&field.attrs) {
1420 return Some(context.snippet(field.span()).to_owned());
1423 let type_annotation_spacing = type_annotation_spacing(context.config);
1424 let prefix = rewrite_struct_field_prefix(context, field)?;
1426 let attrs_str = field.attrs.rewrite(context, shape)?;
1427 let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
1428 let missing_span = if field.attrs.is_empty() {
1429 mk_sp(field.span.lo(), field.span.lo())
1431 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1433 let mut spacing = String::from(if field.ident.is_some() {
1434 type_annotation_spacing.1
1438 // Try to put everything on a single line.
1439 let attr_prefix = combine_strs_with_missing_comments(
1447 let overhead = last_line_width(&attr_prefix);
1448 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1449 for _ in 0..lhs_offset {
1452 // In this extreme case we will be missing a space betweeen an attribute and a field.
1453 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1457 .offset_left(overhead + spacing.len())
1458 .and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
1459 if let Some(ref ty) = orig_ty {
1460 if !ty.contains('\n') {
1461 return Some(attr_prefix + &spacing + ty);
1465 let is_prefix_empty = prefix.is_empty();
1466 // We must use multiline. We are going to put attributes and a field on different lines.
1467 let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, shape)?;
1468 // Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
1469 let field_str = if is_prefix_empty {
1470 field_str.trim_left()
1474 combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
1477 pub struct StaticParts<'a> {
1479 vis: &'a ast::Visibility,
1482 mutability: ast::Mutability,
1483 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1484 defaultness: Option<ast::Defaultness>,
1488 impl<'a> StaticParts<'a> {
1489 pub fn from_item(item: &'a ast::Item) -> Self {
1490 let (prefix, ty, mutability, expr) = match item.node {
1491 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1492 ast::ItemKind::Const(ref ty, ref expr) => {
1493 ("const", ty, ast::Mutability::Immutable, expr)
1495 _ => unreachable!(),
1503 expr_opt: Some(expr),
1509 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1510 let (ty, expr_opt) = match ti.node {
1511 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1512 _ => unreachable!(),
1516 vis: &DEFAULT_VISIBILITY,
1519 mutability: ast::Mutability::Immutable,
1520 expr_opt: expr_opt.as_ref(),
1526 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1527 let (ty, expr) = match ii.node {
1528 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1529 _ => unreachable!(),
1536 mutability: ast::Mutability::Immutable,
1537 expr_opt: Some(expr),
1538 defaultness: Some(ii.defaultness),
1545 context: &RewriteContext,
1546 static_parts: &StaticParts,
1548 ) -> Option<String> {
1549 let colon = colon_spaces(
1550 context.config.space_before_colon(),
1551 context.config.space_after_colon(),
1553 let mut prefix = format!(
1555 format_visibility(static_parts.vis),
1556 static_parts.defaultness.map_or("", format_defaultness),
1557 static_parts.prefix,
1558 format_mutability(static_parts.mutability),
1564 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1565 let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
1566 Some(ty_str) => ty_str,
1568 if prefix.ends_with(' ') {
1571 let nested_indent = offset.block_indent(context.config);
1572 let nested_shape = Shape::indented(nested_indent, context.config);
1573 let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
1576 nested_indent.to_string_with_newline(context.config),
1582 if let Some(expr) = static_parts.expr_opt {
1583 let lhs = format!("{}{} =", prefix, ty_str);
1585 let remaining_width = context.budget(offset.block_indent + 1);
1590 Shape::legacy(remaining_width, offset.block_only()),
1591 ).and_then(|res| recover_comment_removed(res, static_parts.span, context))
1592 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1594 Some(format!("{}{};", prefix, ty_str))
1598 pub fn rewrite_associated_type(
1600 ty_opt: Option<&ptr::P<ast::Ty>>,
1601 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1602 context: &RewriteContext,
1604 ) -> Option<String> {
1605 let prefix = format!("type {}", ident);
1607 let type_bounds_str = if let Some(bounds) = ty_param_bounds_opt {
1609 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1610 let bound_str = bounds
1612 .map(|ty_bound| ty_bound.rewrite(context, shape))
1613 .collect::<Option<Vec<_>>>()?;
1614 if !bounds.is_empty() {
1615 format!(": {}", join_bounds(context, shape, &bound_str))
1623 if let Some(ty) = ty_opt {
1625 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1626 let lhs = format!("{}{} =", prefix, type_bounds_str);
1627 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1629 Some(format!("{}{};", prefix, type_bounds_str))
1633 pub fn rewrite_associated_impl_type(
1635 defaultness: ast::Defaultness,
1636 ty_opt: Option<&ptr::P<ast::Ty>>,
1637 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1638 context: &RewriteContext,
1640 ) -> Option<String> {
1641 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1644 ast::Defaultness::Default => Some(format!("default {}", result)),
1649 impl Rewrite for ast::FunctionRetTy {
1650 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1652 ast::FunctionRetTy::Default(_) => Some(String::new()),
1653 ast::FunctionRetTy::Ty(ref ty) => {
1654 let inner_width = shape.width.checked_sub(3)?;
1655 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1656 .map(|r| format!("-> {}", r))
1662 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1664 ast::TyKind::Infer => {
1665 let original = context.snippet(ty.span);
1672 impl Rewrite for ast::Arg {
1673 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1674 if is_named_arg(self) {
1675 let mut result = self.pat
1676 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1678 if !is_empty_infer(context, &*self.ty) {
1679 if context.config.space_before_colon() {
1680 result.push_str(" ");
1682 result.push_str(":");
1683 if context.config.space_after_colon() {
1684 result.push_str(" ");
1686 let overhead = last_line_width(&result);
1687 let max_width = shape.width.checked_sub(overhead)?;
1688 let ty_str = self.ty
1689 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1690 result.push_str(&ty_str);
1695 self.ty.rewrite(context, shape)
1700 fn rewrite_explicit_self(
1701 explicit_self: &ast::ExplicitSelf,
1703 context: &RewriteContext,
1704 ) -> Option<String> {
1705 match explicit_self.node {
1706 ast::SelfKind::Region(lt, m) => {
1707 let mut_str = format_mutability(m);
1710 let lifetime_str = l.rewrite(
1712 Shape::legacy(context.config.max_width(), Indent::empty()),
1714 Some(format!("&{} {}self", lifetime_str, mut_str))
1716 None => Some(format!("&{}self", mut_str)),
1719 ast::SelfKind::Explicit(ref ty, _) => {
1720 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1722 let mutability = explicit_self_mutability(&args[0]);
1723 let type_str = ty.rewrite(
1725 Shape::legacy(context.config.max_width(), Indent::empty()),
1730 format_mutability(mutability),
1734 ast::SelfKind::Value(_) => {
1735 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1737 let mutability = explicit_self_mutability(&args[0]);
1739 Some(format!("{}self", format_mutability(mutability)))
1744 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1745 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1746 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1747 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1754 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1755 if is_named_arg(arg) {
1762 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1764 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1765 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1766 _ => arg.ty.span.hi(),
1770 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1771 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1772 ident.node != symbol::keywords::Invalid.ident()
1778 // Return type is (result, force_new_line_for_brace)
1780 context: &RewriteContext,
1785 newline_brace: bool,
1787 ) -> Option<(String, bool)> {
1788 let mut force_new_line_for_brace = false;
1790 let where_clause = &fn_sig.generics.where_clause;
1792 let mut result = String::with_capacity(1024);
1793 result.push_str(&fn_sig.to_str(context));
1796 result.push_str("fn ");
1797 result.push_str(&ident.to_string());
1800 let overhead = if has_body && !newline_brace {
1807 let used_width = last_line_used_width(&result, indent.width());
1808 let one_line_budget = context.budget(used_width + overhead);
1810 width: one_line_budget,
1814 let fd = fn_sig.decl;
1815 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1816 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1817 result.push_str(&generics_str);
1819 let snuggle_angle_bracket = generics_str
1822 .map_or(false, |l| l.trim_left().len() == 1);
1824 // Note that the width and indent don't really matter, we'll re-layout the
1825 // return type later anyway.
1826 let ret_str = fd.output
1827 .rewrite(context, Shape::indented(indent, context.config))?;
1829 let multi_line_ret_str = ret_str.contains('\n');
1830 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1833 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1844 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1845 one_line_budget, multi_line_budget, arg_indent
1848 // Check if vertical layout was forced.
1849 if one_line_budget == 0 {
1850 if snuggle_angle_bracket {
1853 result.push_str("(");
1854 if context.config.indent_style() == IndentStyle::Visual {
1855 result.push_str(&arg_indent.to_string_with_newline(context.config));
1861 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty()
1862 && result.ends_with('(')
1867 // Skip `pub(crate)`.
1868 let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
1869 // A conservative estimation, to goal is to be over all parens in generics
1870 let args_start = fn_sig
1875 .map_or(lo_after_visibility, |param| param.span().hi());
1876 let args_end = if fd.inputs.is_empty() {
1879 .span_after(mk_sp(args_start, span.hi()), ")")
1881 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1882 context.snippet_provider.span_after(last_span, ")")
1884 let args_span = mk_sp(
1887 .span_after(mk_sp(args_start, span.hi()), "("),
1890 let arg_str = rewrite_args(
1893 fd.get_self().as_ref(),
1900 generics_str.contains('\n'),
1903 let put_args_in_block = match context.config.indent_style() {
1904 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1906 } && !fd.inputs.is_empty();
1908 let mut args_last_line_contains_comment = false;
1909 if put_args_in_block {
1910 arg_indent = indent.block_indent(context.config);
1911 result.push_str(&arg_indent.to_string_with_newline(context.config));
1912 result.push_str(&arg_str);
1913 result.push_str(&indent.to_string_with_newline(context.config));
1916 result.push_str(&arg_str);
1917 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1918 // Put the closing brace on the next line if it overflows the max width.
1920 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1923 if context.config.spaces_within_parens_and_brackets() && !fd.inputs.is_empty() {
1926 // If the last line of args contains comment, we cannot put the closing paren
1927 // on the same line.
1931 .map_or(false, |last_line| last_line.contains("//"))
1933 args_last_line_contains_comment = true;
1934 result.push_str(&arg_indent.to_string_with_newline(context.config));
1940 if let ast::FunctionRetTy::Ty(..) = fd.output {
1941 let ret_should_indent = match context.config.indent_style() {
1942 // If our args are block layout then we surely must have space.
1943 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1944 _ if args_last_line_contains_comment => false,
1945 _ if result.contains('\n') || multi_line_ret_str => true,
1947 // If the return type would push over the max width, then put the return type on
1948 // a new line. With the +1 for the signature length an additional space between
1949 // the closing parenthesis of the argument and the arrow '->' is considered.
1950 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1952 // If there is no where clause, take into account the space after the return type
1954 if where_clause.predicates.is_empty() {
1958 sig_length > context.config.max_width()
1961 let ret_indent = if ret_should_indent {
1962 let indent = if arg_str.is_empty() {
1963 // Aligning with non-existent args looks silly.
1964 force_new_line_for_brace = true;
1967 // FIXME: we might want to check that using the arg indent
1968 // doesn't blow our budget, and if it does, then fallback to
1969 // the where clause indent.
1973 result.push_str(&indent.to_string_with_newline(context.config));
1977 Indent::new(indent.block_indent, last_line_width(&result))
1980 if multi_line_ret_str || ret_should_indent {
1981 // Now that we know the proper indent and width, we need to
1982 // re-layout the return type.
1983 let ret_str = fd.output
1984 .rewrite(context, Shape::indented(ret_indent, context.config))?;
1985 result.push_str(&ret_str);
1987 result.push_str(&ret_str);
1990 // Comment between return type and the end of the decl.
1991 let snippet_lo = fd.output.span().hi();
1992 if where_clause.predicates.is_empty() {
1993 let snippet_hi = span.hi();
1994 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
1995 // Try to preserve the layout of the original snippet.
1996 let original_starts_with_newline = snippet
1998 .map_or(false, |i| starts_with_newline(&snippet[i..]));
1999 let original_ends_with_newline = snippet
2000 .rfind(|c| c != ' ')
2001 .map_or(false, |i| snippet[i..].ends_with('\n'));
2002 let snippet = snippet.trim();
2003 if !snippet.is_empty() {
2004 result.push(if original_starts_with_newline {
2009 result.push_str(snippet);
2010 if original_ends_with_newline {
2011 force_new_line_for_brace = true;
2017 let pos_before_where = match fd.output {
2018 ast::FunctionRetTy::Default(..) => args_span.hi(),
2019 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2022 let is_args_multi_lined = arg_str.contains('\n');
2024 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2025 let where_clause_str = rewrite_where_clause(
2028 context.config.brace_style(),
2029 Shape::indented(indent, context.config),
2035 is_args_multi_lined,
2037 // If there are neither where clause nor return type, we may be missing comments between
2039 if where_clause_str.is_empty() {
2040 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2041 match recover_missing_comment_in_span(
2042 mk_sp(args_span.hi(), ret_span.hi()),
2045 last_line_width(&result),
2047 Some(ref missing_comment) if !missing_comment.is_empty() => {
2048 result.push_str(missing_comment);
2049 force_new_line_for_brace = true;
2056 result.push_str(&where_clause_str);
2058 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2059 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2060 Some((result, force_new_line_for_brace))
2063 #[derive(Copy, Clone)]
2064 struct WhereClauseOption {
2065 suppress_comma: bool, // Force no trailing comma
2066 snuggle: bool, // Do not insert newline before `where`
2067 compress_where: bool, // Try single line where clause instead of vertical layout
2070 impl WhereClauseOption {
2071 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2075 compress_where: false,
2079 pub fn snuggled(current: &str) -> WhereClauseOption {
2081 suppress_comma: false,
2082 snuggle: trimmed_last_line_width(current) == 1,
2083 compress_where: false,
2089 context: &RewriteContext,
2091 explicit_self: Option<&ast::ExplicitSelf>,
2092 one_line_budget: usize,
2093 multi_line_budget: usize,
2098 generics_str_contains_newline: bool,
2099 ) -> Option<String> {
2100 let mut arg_item_strs = args.iter()
2101 .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
2102 .collect::<Option<Vec<_>>>()?;
2104 // Account for sugary self.
2105 // FIXME: the comment for the self argument is dropped. This is blocked
2106 // on rust issue #27522.
2107 let min_args = explicit_self
2108 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2109 .map_or(1, |self_str| {
2110 arg_item_strs[0] = self_str;
2114 // Comments between args.
2115 let mut arg_items = Vec::new();
2117 arg_items.push(ListItem::from_str(""));
2120 // FIXME(#21): if there are no args, there might still be a comment, but
2121 // without spans for the comment or parens, there is no chance of
2122 // getting it right. You also don't get to put a comment on self, unless
2124 if args.len() >= min_args || variadic {
2125 let comment_span_start = if min_args == 2 {
2126 let second_arg_start = if arg_has_pattern(&args[1]) {
2127 args[1].pat.span.lo()
2129 args[1].ty.span.lo()
2131 let reduced_span = mk_sp(span.lo(), second_arg_start);
2133 context.snippet_provider.span_after_last(reduced_span, ",")
2138 enum ArgumentKind<'a> {
2139 Regular(&'a ast::Arg),
2143 let variadic_arg = if variadic {
2144 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2145 let variadic_start =
2146 context.snippet_provider.span_after(variadic_span, "...") - BytePos(3);
2147 Some(ArgumentKind::Variadic(variadic_start))
2152 let more_items = itemize_list(
2153 context.snippet_provider,
2154 args[min_args - 1..]
2156 .map(ArgumentKind::Regular)
2157 .chain(variadic_arg),
2161 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2162 ArgumentKind::Variadic(start) => start,
2165 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2166 ArgumentKind::Variadic(start) => start + BytePos(3),
2169 ArgumentKind::Regular(..) => None,
2170 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2177 arg_items.extend(more_items);
2180 let fits_in_one_line = !generics_str_contains_newline
2181 && (arg_items.is_empty()
2182 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2184 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2185 item.item = Some(arg);
2188 let last_line_ends_with_comment = arg_items
2191 .and_then(|item| item.post_comment.as_ref())
2192 .map_or(false, |s| s.trim().starts_with("//"));
2194 let (indent, trailing_comma) = match context.config.indent_style() {
2195 IndentStyle::Block if fits_in_one_line => {
2196 (indent.block_indent(context.config), SeparatorTactic::Never)
2198 IndentStyle::Block => (
2199 indent.block_indent(context.config),
2200 context.config.trailing_comma(),
2202 IndentStyle::Visual if last_line_ends_with_comment => {
2203 (arg_indent, context.config.trailing_comma())
2205 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2208 let tactic = definitive_tactic(
2210 context.config.fn_args_density().to_list_tactic(),
2214 let budget = match tactic {
2215 DefinitiveListTactic::Horizontal => one_line_budget,
2216 _ => multi_line_budget,
2219 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2221 let fmt = ListFormatting {
2224 trailing_separator: if variadic {
2225 SeparatorTactic::Never
2229 separator_place: SeparatorPlace::Back,
2230 shape: Shape::legacy(budget, indent),
2231 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2232 preserve_newline: true,
2233 config: context.config,
2236 write_list(&arg_items, &fmt)
2239 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2240 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2241 ident.node != symbol::keywords::Invalid.ident()
2247 fn compute_budgets_for_args(
2248 context: &RewriteContext,
2252 newline_brace: bool,
2254 force_vertical_layout: bool,
2255 ) -> Option<((usize, usize, Indent))> {
2257 "compute_budgets_for_args {} {:?}, {}, {}",
2263 // Try keeping everything on the same line.
2264 if !result.contains('\n') && !force_vertical_layout {
2265 // 2 = `()`, 3 = `() `, space is before ret_string.
2266 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2267 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2277 let one_line_budget = context.budget(used_space);
2279 if one_line_budget > 0 {
2281 let (indent, multi_line_budget) = match context.config.indent_style() {
2282 IndentStyle::Block => {
2283 let indent = indent.block_indent(context.config);
2284 (indent, context.budget(indent.width() + 1))
2286 IndentStyle::Visual => {
2287 let indent = indent + result.len() + 1;
2288 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2289 (indent, context.budget(multi_line_overhead))
2293 return Some((one_line_budget, multi_line_budget, indent));
2297 // Didn't work. we must force vertical layout and put args on a newline.
2298 let new_indent = indent.block_indent(context.config);
2299 let used_space = match context.config.indent_style() {
2301 IndentStyle::Block => new_indent.width() + 1,
2302 // Account for `)` and possibly ` {`.
2303 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2305 Some((0, context.budget(used_space), new_indent))
2308 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2309 let predicate_count = where_clause.predicates.len();
2311 if config.where_single_line() && predicate_count == 1 {
2314 let brace_style = config.brace_style();
2316 brace_style == BraceStyle::AlwaysNextLine
2317 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2320 fn rewrite_generics(
2321 context: &RewriteContext,
2322 generics: &ast::Generics,
2325 ) -> Option<String> {
2326 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2327 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2328 rewrite_generics_inner(context, generics, g_shape, one_line_width, span)
2329 .or_else(|| rewrite_generics_inner(context, generics, g_shape, 0, span))
2332 fn rewrite_generics_inner(
2333 context: &RewriteContext,
2334 generics: &ast::Generics,
2336 one_line_width: usize,
2338 ) -> Option<String> {
2339 // FIXME: convert bounds to where clauses where they get too big or if
2340 // there is a where clause at all.
2342 if generics.params.is_empty() {
2343 return Some(String::new());
2346 let items = itemize_list(
2347 context.snippet_provider,
2348 generics.params.iter(),
2351 |arg| arg.span().lo(),
2352 |arg| arg.span().hi(),
2353 |arg| arg.rewrite(context, shape),
2354 context.snippet_provider.span_after(span, "<"),
2358 format_generics_item_list(context, items, shape, one_line_width)
2361 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2362 match config.indent_style() {
2363 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2364 IndentStyle::Block => {
2368 .block_indent(config.tab_spaces())
2369 .with_max_width(config)
2375 pub fn format_generics_item_list<I>(
2376 context: &RewriteContext,
2379 one_line_budget: usize,
2382 I: Iterator<Item = ListItem>,
2384 let item_vec = items.collect::<Vec<_>>();
2386 let tactic = definitive_tactic(
2388 ListTactic::HorizontalVertical,
2392 let fmt = ListFormatting {
2395 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2396 SeparatorTactic::Never
2398 context.config.trailing_comma()
2400 separator_place: SeparatorPlace::Back,
2402 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2403 preserve_newline: true,
2404 config: context.config,
2407 let list_str = write_list(&item_vec, &fmt)?;
2409 Some(wrap_generics_with_angle_brackets(
2416 pub fn wrap_generics_with_angle_brackets(
2417 context: &RewriteContext,
2419 list_offset: Indent,
2421 if context.config.indent_style() == IndentStyle::Block
2422 && (list_str.contains('\n') || list_str.ends_with(','))
2426 list_offset.to_string(context.config),
2429 .block_unindent(context.config)
2430 .to_string(context.config)
2432 } else if context.config.spaces_within_parens_and_brackets() {
2433 format!("< {} >", list_str)
2435 format!("<{}>", list_str)
2439 fn rewrite_trait_bounds(
2440 context: &RewriteContext,
2441 bounds: &[ast::TyParamBound],
2443 ) -> Option<String> {
2444 if bounds.is_empty() {
2445 return Some(String::new());
2447 let bound_str = bounds
2449 .map(|ty_bound| ty_bound.rewrite(context, shape))
2450 .collect::<Option<Vec<_>>>()?;
2451 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2454 fn rewrite_where_clause_rfc_style(
2455 context: &RewriteContext,
2456 where_clause: &ast::WhereClause,
2459 span_end: Option<BytePos>,
2460 span_end_before_where: BytePos,
2461 where_clause_option: WhereClauseOption,
2462 is_args_multi_line: bool,
2463 ) -> Option<String> {
2464 let block_shape = shape.block().with_max_width(context.config);
2466 let (span_before, span_after) =
2467 missing_span_before_after_where(span_end_before_where, where_clause);
2468 let (comment_before, comment_after) =
2469 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2471 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2474 block_shape.indent.to_string_with_newline(context.config)
2477 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2479 let clause_shape = clause_shape.sub_width(1)?;
2480 // each clause on one line, trailing comma (except if suppress_comma)
2481 let span_start = where_clause.predicates[0].span().lo();
2482 // If we don't have the start of the next span, then use the end of the
2483 // predicates, but that means we miss comments.
2484 let len = where_clause.predicates.len();
2485 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2486 let span_end = span_end.unwrap_or(end_of_preds);
2487 let items = itemize_list(
2488 context.snippet_provider,
2489 where_clause.predicates.iter(),
2492 |pred| pred.span().lo(),
2493 |pred| pred.span().hi(),
2494 |pred| pred.rewrite(context, clause_shape),
2499 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2500 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2501 SeparatorTactic::Never
2503 context.config.trailing_comma()
2506 // shape should be vertical only and only if we have `where_single_line` option enabled
2507 // and the number of items of the where clause is equal to 1
2508 let shape_tactic = if where_single_line {
2509 DefinitiveListTactic::Horizontal
2511 DefinitiveListTactic::Vertical
2514 let fmt = ListFormatting {
2515 tactic: shape_tactic,
2517 trailing_separator: comma_tactic,
2518 separator_place: SeparatorPlace::Back,
2519 shape: clause_shape,
2520 ends_with_newline: true,
2521 preserve_newline: true,
2522 config: context.config,
2524 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2526 let comment_separator = |comment: &str, shape: Shape| {
2527 if comment.is_empty() {
2530 shape.indent.to_string_with_newline(context.config)
2533 let newline_before_where = comment_separator(&comment_before, shape);
2534 let newline_after_where = comment_separator(&comment_after, clause_shape);
2537 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2538 && comment_after.is_empty() && !preds_str.contains('\n')
2539 && 6 + preds_str.len() <= shape.width || where_single_line
2543 clause_shape.indent.to_string_with_newline(context.config)
2546 "{}{}{}where{}{}{}{}",
2549 newline_before_where,
2550 newline_after_where,
2557 fn rewrite_where_clause(
2558 context: &RewriteContext,
2559 where_clause: &ast::WhereClause,
2560 brace_style: BraceStyle,
2564 span_end: Option<BytePos>,
2565 span_end_before_where: BytePos,
2566 where_clause_option: WhereClauseOption,
2567 is_args_multi_line: bool,
2568 ) -> Option<String> {
2569 if where_clause.predicates.is_empty() {
2570 return Some(String::new());
2573 if context.config.indent_style() == IndentStyle::Block {
2574 return rewrite_where_clause_rfc_style(
2580 span_end_before_where,
2581 where_clause_option,
2586 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2588 let offset = match context.config.indent_style() {
2589 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2590 // 6 = "where ".len()
2591 IndentStyle::Visual => shape.indent + extra_indent + 6,
2593 // FIXME: if indent_style != Visual, then the budgets below might
2594 // be out by a char or two.
2596 let budget = context.config.max_width() - offset.width();
2597 let span_start = where_clause.predicates[0].span().lo();
2598 // If we don't have the start of the next span, then use the end of the
2599 // predicates, but that means we miss comments.
2600 let len = where_clause.predicates.len();
2601 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2602 let span_end = span_end.unwrap_or(end_of_preds);
2603 let items = itemize_list(
2604 context.snippet_provider,
2605 where_clause.predicates.iter(),
2608 |pred| pred.span().lo(),
2609 |pred| pred.span().hi(),
2610 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2615 let item_vec = items.collect::<Vec<_>>();
2616 // FIXME: we don't need to collect here
2617 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2619 let mut comma_tactic = context.config.trailing_comma();
2620 // Kind of a hack because we don't usually have trailing commas in where clauses.
2621 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2622 comma_tactic = SeparatorTactic::Never;
2625 let fmt = ListFormatting {
2628 trailing_separator: comma_tactic,
2629 separator_place: SeparatorPlace::Back,
2630 shape: Shape::legacy(budget, offset),
2631 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2632 preserve_newline: true,
2633 config: context.config,
2635 let preds_str = write_list(&item_vec, &fmt)?;
2637 let end_length = if terminator == "{" {
2638 // If the brace is on the next line we don't need to count it otherwise it needs two
2641 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2642 BraceStyle::PreferSameLine => 2,
2644 } else if terminator == "=" {
2649 if density == Density::Tall || preds_str.contains('\n')
2650 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2654 (shape.indent + extra_indent).to_string(context.config),
2658 Some(format!(" where {}", preds_str))
2662 fn missing_span_before_after_where(
2663 before_item_span_end: BytePos,
2664 where_clause: &ast::WhereClause,
2666 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2668 let pos_after_where = where_clause.span.lo() + BytePos(5);
2669 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2670 (missing_span_before, missing_span_after)
2673 fn rewrite_comments_before_after_where(
2674 context: &RewriteContext,
2675 span_before_where: Span,
2676 span_after_where: Span,
2678 ) -> Option<(String, String)> {
2679 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2680 let after_comment = rewrite_missing_comment(
2682 shape.block_indent(context.config.tab_spaces()),
2685 Some((before_comment, after_comment))
2688 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2689 format!("{}{}{}", format_visibility(vis), item_name, ident)
2692 #[derive(PartialEq, Eq, Clone, Copy)]
2700 context: &RewriteContext,
2701 generics: &ast::Generics,
2702 brace_style: BraceStyle,
2703 brace_pos: BracePos,
2707 ) -> Option<String> {
2708 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2709 let mut result = rewrite_generics(context, generics, shape, span)?;
2711 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2712 let budget = context.budget(last_line_used_width(&result, offset.width()));
2713 let mut option = WhereClauseOption::snuggled(&result);
2714 if brace_pos == BracePos::None {
2715 option.suppress_comma = true;
2717 // If the generics are not parameterized then generics.span.hi() == 0,
2718 // so we use span.lo(), which is the position after `struct Foo`.
2719 let span_end_before_where = if generics.is_parameterized() {
2724 let where_clause_str = rewrite_where_clause(
2726 &generics.where_clause,
2728 Shape::legacy(budget, offset.block_only()),
2732 span_end_before_where,
2736 result.push_str(&where_clause_str);
2737 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2738 || (generics.where_clause.predicates.is_empty()
2739 && trimmed_last_line_width(&result) == 1)
2741 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2742 || brace_style != BraceStyle::AlwaysNextLine
2744 if brace_pos == BracePos::None {
2745 return Some(result);
2747 let total_used_width = last_line_used_width(&result, used_width);
2748 let remaining_budget = context.budget(total_used_width);
2749 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2750 // and hence we take the closer into account as well for one line budget.
2751 // We assume that the closer has the same length as the opener.
2752 let overhead = if brace_pos == BracePos::ForceSameLine {
2759 let forbid_same_line_brace = overhead > remaining_budget;
2760 if !forbid_same_line_brace && same_line_brace {
2764 result.push_str(&offset.block_only().to_string(context.config));
2771 impl Rewrite for ast::ForeignItem {
2772 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2773 let attrs_str = self.attrs.rewrite(context, shape)?;
2774 // Drop semicolon or it will be interpreted as comment.
2775 // FIXME: this may be a faulty span from libsyntax.
2776 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2778 let item_str = match self.node {
2779 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2784 &FnSig::new(fn_decl, generics, self.vis.clone()),
2788 ).map(|(s, _)| format!("{};", s))
2790 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2791 // FIXME(#21): we're dropping potential comments in between the
2792 // function keywords here.
2793 let vis = format_visibility(&self.vis);
2794 let mut_str = if is_mutable { "mut " } else { "" };
2795 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2797 let shape = shape.sub_width(1)?;
2798 ty.rewrite(context, shape).map(|ty_str| {
2799 // 1 = space between prefix and type.
2800 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2803 let nested_indent = shape.indent.block_indent(context.config);
2804 nested_indent.to_string_with_newline(context.config)
2806 format!("{}{}{};", prefix, sep, ty_str)
2809 ast::ForeignItemKind::Ty => {
2810 let vis = format_visibility(&self.vis);
2811 Some(format!("{}type {};", vis, self.ident))
2815 let missing_span = if self.attrs.is_empty() {
2816 mk_sp(self.span.lo(), self.span.lo())
2818 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2820 combine_strs_with_missing_comments(
2831 impl Rewrite for ast::GenericParam {
2832 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2834 ast::GenericParam::Lifetime(ref lifetime_def) => lifetime_def.rewrite(context, shape),
2835 ast::GenericParam::Type(ref ty) => ty.rewrite(context, shape),
2840 /// Rewrite an inline mod.
2841 pub fn rewrite_mod(item: &ast::Item) -> String {
2842 let mut result = String::with_capacity(32);
2843 result.push_str(&*format_visibility(&item.vis));
2844 result.push_str("mod ");
2845 result.push_str(&item.ident.to_string());
2850 /// Rewrite `extern crate foo;` WITHOUT attributes.
2851 pub fn rewrite_extern_crate(context: &RewriteContext, item: &ast::Item) -> Option<String> {
2852 assert!(is_extern_crate(item));
2853 let new_str = context.snippet(item.span);
2854 Some(if contains_comment(new_str) {
2857 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
2858 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
2862 /// Returns true for `mod foo;`, false for `mod foo { .. }`.
2863 pub fn is_mod_decl(item: &ast::Item) -> bool {
2865 ast::ItemKind::Mod(ref m) => m.inner.hi() != item.span.hi(),
2870 pub fn is_use_item(item: &ast::Item) -> bool {
2872 ast::ItemKind::Use(_) => true,
2877 pub fn is_extern_crate(item: &ast::Item) -> bool {
2879 ast::ItemKind::ExternCrate(..) => true,