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.
16 use syntax::{abi, ast, ptr, symbol};
17 use syntax::ast::{CrateSugar, ImplItem};
18 use syntax::codemap::{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, ReturnIndent};
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, DefinitiveListTactic, ListFormatting,
29 ListItem, ListTactic, Separator, SeparatorPlace, SeparatorTactic};
30 use rewrite::{Rewrite, RewriteContext};
31 use shape::{Indent, Shape};
32 use types::join_bounds;
33 use utils::{colon_spaces, contains_skip, end_typaram, first_line_width, format_abi,
34 format_constness, format_defaultness, format_mutability, format_unsafety,
35 format_visibility, 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, trim_newlines, trimmed_last_line_width};
38 use vertical::rewrite_with_alignment;
39 use visitor::FmtVisitor;
41 fn type_annotation_separator(config: &Config) -> &str {
43 config.space_before_type_annotation(),
44 config.space_after_type_annotation_colon(),
48 // Statements of the form
49 // let pat: ty = init;
50 impl Rewrite for ast::Local {
51 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
53 "Local::rewrite {:?} {} {:?}",
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: ast::Visibility::Inherited,
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();
253 self.buffer.push_str("{");
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);
265 .push_str(&self.block_indent.to_string(self.config));
267 for item in &item.body {
268 self.format_body_element(item);
271 self.block_indent = self.block_indent.block_unindent(self.config);
272 self.format_missing_with_indent(item.span.hi() - BytePos(1));
276 self.buffer.push_str("}");
277 self.last_pos = item.span.hi();
280 fn format_body_element(&mut self, element: &BodyElement) {
282 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
286 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
287 let item = Item::from_foreign_mod(fm, span, self.config);
288 self.format_item(item);
292 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
293 let rewrite = item.rewrite(&self.get_context(), self.shape());
294 self.push_rewrite(item.span(), rewrite);
295 self.last_pos = item.span.hi();
305 ) -> Option<String> {
306 let context = self.get_context();
309 !is_empty_block(block, self.codemap) || !context.config.fn_empty_single_line();
310 let mut newline_brace =
311 newline_for_brace(self.config, &fn_sig.generics.where_clause, has_body);
313 let (mut result, force_newline_brace) =
314 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
317 if self.config.fn_brace_style() == BraceStyle::AlwaysNextLine || force_newline_brace
318 || last_line_width(&result) + 2 > self.shape().width
320 newline_brace = true;
321 } else if !result.contains('\n') {
322 newline_brace = false;
325 // Prepare for the function body by possibly adding a newline and
327 // FIXME we'll miss anything between the end of the signature and the
328 // start of the body, but we need more spans from the compiler to solve
332 result.push_str(&indent.to_string(self.config));
337 self.single_line_fn(&result, block).or_else(|| Some(result))
340 pub fn rewrite_required_fn(
344 sig: &ast::MethodSig,
345 generics: &ast::Generics,
347 ) -> Option<String> {
348 // Drop semicolon or it will be interpreted as comment.
349 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
350 let context = self.get_context();
352 let (mut result, _) = rewrite_fn_base(
356 &FnSig::from_method_sig(sig, generics),
362 // Re-attach semicolon
368 fn single_line_fn(&self, fn_str: &str, block: &ast::Block) -> Option<String> {
369 if fn_str.contains('\n') {
373 let codemap = self.get_context().codemap;
375 if self.config.fn_empty_single_line() && is_empty_block(block, codemap)
376 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
378 return Some(format!("{}{{}}", fn_str));
381 if self.config.fn_single_line() && is_simple_block_stmt(block, codemap) {
383 if let Some(stmt) = block.stmts.first() {
384 match stmt_expr(stmt) {
386 let suffix = if semicolon_for_expr(&self.get_context(), e) {
392 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
394 .or_else(|| Some(self.snippet(e.span)))
396 None => stmt.rewrite(&self.get_context(), self.shape()),
403 if let Some(res) = rewrite {
404 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
405 if !res.contains('\n') && width <= self.config.max_width() {
406 return Some(format!("{}{{ {} }}", fn_str, res));
414 pub fn visit_static(&mut self, static_parts: &StaticParts) {
415 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
416 self.push_rewrite(static_parts.span, rewrite);
419 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
420 let is_tuple = struct_parts.def.is_tuple();
421 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
422 .map(|s| if is_tuple { s + ";" } else { s });
423 self.push_rewrite(struct_parts.span, rewrite);
429 vis: &ast::Visibility,
430 enum_def: &ast::EnumDef,
431 generics: &ast::Generics,
434 let enum_header = format_header("enum ", ident, vis);
435 self.buffer.push_str(&enum_header);
437 let enum_snippet = self.snippet(span);
438 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
439 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
440 let generics_str = format_generics(
443 self.config.item_brace_style(),
444 if enum_def.variants.is_empty() {
445 BracePos::ForceSameLine
450 mk_sp(span.lo(), body_start),
451 last_line_width(&enum_header),
453 self.buffer.push_str(&generics_str);
455 self.last_pos = body_start;
457 self.block_indent = self.block_indent.block_indent(self.config);
458 let variant_list = self.format_variant_list(enum_def, body_start, span.hi() - BytePos(1));
460 Some(ref body_str) => self.buffer.push_str(body_str),
461 None => if contains_comment(&enum_snippet[brace_pos..]) {
462 self.format_missing_no_indent(span.hi() - BytePos(1))
465 self.block_indent = self.block_indent.block_unindent(self.config);
467 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
469 .push_str(&self.block_indent.to_string(self.config));
471 self.buffer.push_str("}");
472 self.last_pos = span.hi();
475 // Format the body of an enum definition
476 fn format_variant_list(
478 enum_def: &ast::EnumDef,
481 ) -> Option<String> {
482 if enum_def.variants.is_empty() {
485 let mut result = String::with_capacity(1024);
487 let indentation = self.block_indent.to_string(self.config);
488 result.push_str(&indentation);
490 let items = itemize_list(
492 enum_def.variants.iter(),
494 |f| if !f.node.attrs.is_empty() {
495 f.node.attrs[0].span.lo()
500 |f| self.format_variant(f),
506 let shape = self.shape().sub_width(2).unwrap();
507 let fmt = ListFormatting {
508 tactic: DefinitiveListTactic::Vertical,
510 trailing_separator: self.config.trailing_comma(),
511 separator_place: SeparatorPlace::Back,
513 ends_with_newline: true,
514 preserve_newline: true,
518 let list = write_list(&items.collect::<Vec<_>>(), &fmt)?;
519 result.push_str(&list);
524 // Variant of an enum.
525 fn format_variant(&self, field: &ast::Variant) -> Option<String> {
526 if contains_skip(&field.node.attrs) {
527 let lo = field.node.attrs[0].span.lo();
528 let span = mk_sp(lo, field.span.hi());
529 return Some(self.snippet(span));
532 let context = self.get_context();
533 let indent = self.block_indent;
534 let shape = self.shape();
535 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
540 .map_or(field.span.lo(), |attr| attr.span.hi());
541 let span = mk_sp(lo, field.span.lo());
543 let variant_body = match field.node.data {
544 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => {
545 // FIXME: Should limit the width, as we have a trailing comma
548 &StructParts::from_variant(field),
550 Some(self.config.struct_variant_width()),
553 ast::VariantData::Unit(..) => if let Some(ref expr) = field.node.disr_expr {
554 let lhs = format!("{} =", field.node.name);
556 rewrite_assign_rhs(&context, lhs, expr, shape.sub_width(1)?)?
558 field.node.name.to_string()
562 let attrs_extendable = attrs_str.is_empty()
563 || (context.config.attributes_on_same_line_as_variant()
564 && is_attributes_extendable(&attrs_str));
565 combine_strs_with_missing_comments(
577 context: &RewriteContext,
580 where_span_end: Option<BytePos>,
581 ) -> Option<String> {
582 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
583 let mut result = String::with_capacity(128);
584 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
585 let indent_str = offset.to_string(context.config);
586 let sep = format!("\n{}", &indent_str);
587 result.push_str(&ref_and_type);
589 let where_budget = if result.contains('\n') {
590 context.config.max_width()
592 context.budget(last_line_width(&result))
594 let option = WhereClauseOption::snuggled(&ref_and_type);
595 let where_clause_str = rewrite_where_clause(
597 &generics.where_clause,
598 context.config.item_brace_style(),
599 Shape::legacy(where_budget, offset.block_only()),
600 context.config.where_density(),
608 // If there is no where clause, we may have missing comments between the trait name and
609 // the opening brace.
610 if generics.where_clause.predicates.is_empty() {
611 if let Some(hi) = where_span_end {
612 match recover_missing_comment_in_span(
613 mk_sp(self_ty.span.hi(), hi),
614 Shape::indented(offset, context.config),
616 last_line_width(&result),
618 Some(ref missing_comment) if !missing_comment.is_empty() => {
619 result.push_str(missing_comment);
626 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
627 result.push_str(&where_clause_str);
628 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
629 result.push_str(&format!("{}{{{}}}", &sep, &sep));
631 result.push_str(" {}");
636 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
638 let width = offset.block_indent + context.config.tab_spaces() - 1;
639 let where_indent = Indent::new(0, width);
640 result.push_str(&where_indent.to_string(context.config));
642 result.push_str(&where_clause_str);
644 match context.config.item_brace_style() {
645 _ if last_line_contains_single_line_comment(&result) => result.push_str(&sep),
646 BraceStyle::AlwaysNextLine => result.push_str(&sep),
647 BraceStyle::PreferSameLine => result.push(' '),
648 BraceStyle::SameLineWhere => if !where_clause_str.is_empty() {
649 result.push_str(&sep);
657 let snippet = context.snippet(item.span);
658 let open_pos = snippet.find_uncommented("{")? + 1;
660 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
661 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
662 visitor.block_indent = offset.block_only().block_indent(context.config);
663 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
665 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
667 visitor.visit_impl_item(item);
670 visitor.format_missing(item.span.hi() - BytePos(1));
672 let inner_indent_str = visitor.block_indent.to_string(context.config);
673 let outer_indent_str = offset.block_only().to_string(context.config);
676 result.push_str(&inner_indent_str);
677 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
679 result.push_str(&outer_indent_str);
682 if result.ends_with('{') {
683 result.push_str(&sep);
693 fn is_impl_single_line(
694 context: &RewriteContext,
697 where_clause_str: &str,
700 let snippet = context.snippet(item.span);
701 let open_pos = snippet.find_uncommented("{")? + 1;
704 context.config.impl_empty_single_line() && items.is_empty() && !result.contains('\n')
705 && result.len() + where_clause_str.len() <= context.config.max_width()
706 && !contains_comment(&snippet[open_pos..]),
710 fn format_impl_ref_and_type(
711 context: &RewriteContext,
714 ) -> Option<String> {
715 if let ast::ItemKind::Impl(
725 let mut result = String::with_capacity(128);
727 result.push_str(&format_visibility(&item.vis));
728 result.push_str(format_defaultness(defaultness));
729 result.push_str(format_unsafety(unsafety));
730 result.push_str("impl");
732 let lo = context.codemap.span_after(item.span, "impl");
733 let hi = match *trait_ref {
734 Some(ref tr) => tr.path.span.lo(),
735 None => self_ty.span.lo(),
737 let shape = generics_shape_from_config(
739 Shape::indented(offset + last_line_width(&result), context.config),
742 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
744 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
746 let polarity_str = if polarity == ast::ImplPolarity::Negative {
752 if let Some(ref trait_ref) = *trait_ref {
753 let result_len = result.len();
754 if let Some(trait_ref_str) = rewrite_trait_ref(
763 result.push_str(&trait_ref_str);
766 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
767 result.push_str(&rewrite_trait_ref(
778 result.push_str(&generics_str);
781 // Try to put the self type in a single line.
783 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
784 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
785 // If there is no where clause adapt budget for type formatting to take space and curly
786 // brace into account.
787 match context.config.item_brace_style() {
788 BraceStyle::AlwaysNextLine => 0,
794 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
795 // 1 = space before the type.
796 let budget = context.budget(used_space + 1);
797 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
798 if !self_ty_str.contains('\n') {
799 if trait_ref.is_some() {
800 result.push_str(" for ");
804 result.push_str(&self_ty_str);
809 // Couldn't fit the self type on a single line, put it on a new line.
811 // Add indentation of one additional tab.
812 let new_line_offset = offset.block_indent(context.config);
813 result.push_str(&new_line_offset.to_string(context.config));
814 if trait_ref.is_some() {
815 result.push_str("for ");
817 let budget = context.budget(last_line_width(&result));
818 let type_offset = match context.config.indent_style() {
819 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
820 IndentStyle::Block => new_line_offset,
822 result.push_str(&*self_ty
823 .rewrite(context, Shape::legacy(budget, type_offset))?);
830 fn rewrite_trait_ref(
831 context: &RewriteContext,
832 trait_ref: &ast::TraitRef,
838 ) -> Option<String> {
839 // 1 = space between generics and trait_ref
840 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
841 let shape = Shape::indented(offset + used_space, context.config);
842 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
843 if !(retry && trait_ref_str.contains('\n')) {
852 // We could not make enough space for trait_ref, so put it on new line.
854 let offset = offset.block_indent(context.config);
855 let shape = Shape::indented(offset, context.config);
856 let trait_ref_str = trait_ref.rewrite(context, shape)?;
860 &offset.to_string(context.config),
869 pub struct StructParts<'a> {
872 vis: &'a ast::Visibility,
873 def: &'a ast::VariantData,
874 generics: Option<&'a ast::Generics>,
878 impl<'a> StructParts<'a> {
879 fn format_header(&self) -> String {
880 format_header(self.prefix, self.ident, self.vis)
883 fn from_variant(variant: &'a ast::Variant) -> Self {
886 ident: variant.node.name,
887 vis: &ast::Visibility::Inherited,
888 def: &variant.node.data,
894 pub fn from_item(item: &'a ast::Item) -> Self {
895 let (prefix, def, generics) = match item.node {
896 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
897 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
905 generics: Some(generics),
912 context: &RewriteContext,
913 struct_parts: &StructParts,
915 one_line_width: Option<usize>,
916 ) -> Option<String> {
917 match *struct_parts.def {
918 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
919 ast::VariantData::Tuple(ref fields, _) => {
920 format_tuple_struct(context, struct_parts, fields, offset)
922 ast::VariantData::Struct(ref fields, _) => {
923 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
928 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
929 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
932 let mut result = String::with_capacity(128);
933 let header = format!(
935 format_visibility(&item.vis),
936 format_unsafety(unsafety),
940 result.push_str(&header);
942 let body_lo = context.codemap.span_after(item.span, "{");
944 let shape = Shape::indented(offset, context.config);
946 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
947 result.push_str(&generics_str);
949 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
950 if !type_param_bounds.is_empty() {
951 let ident_hi = context.codemap.span_after(item.span, &format!("{}", item.ident));
952 let bound_hi = type_param_bounds.last().unwrap().span().hi();
953 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
954 if contains_comment(&snippet) {
958 let trait_bound_str = rewrite_trait_bounds(
961 Shape::indented(offset, context.config),
963 // If the trait, generics, and trait bound cannot fit on the same line,
964 // put the trait bounds on an indented new line
965 if offset.width() + last_line_width(&result) + trait_bound_str.len()
966 > context.config.comment_width()
969 let trait_indent = offset.block_only().block_indent(context.config);
970 result.push_str(&trait_indent.to_string(context.config));
972 result.push_str(&trait_bound_str);
974 let has_body = !trait_items.is_empty();
976 let where_density = if (context.config.where_density() == Density::Compressed
977 && (!result.contains('\n') || context.config.indent_style() == IndentStyle::Block))
978 || (context.config.indent_style() == IndentStyle::Block && result.is_empty())
979 || (context.config.where_density() == Density::CompressedIfEmpty && !has_body
980 && !result.contains('\n'))
987 let where_budget = context.budget(last_line_width(&result));
988 let pos_before_where = if type_param_bounds.is_empty() {
989 generics.where_clause.span.lo()
991 type_param_bounds[type_param_bounds.len() - 1].span().hi()
993 let option = WhereClauseOption::snuggled(&generics_str);
994 let where_clause_str = rewrite_where_clause(
996 &generics.where_clause,
997 context.config.item_brace_style(),
998 Shape::legacy(where_budget, offset.block_only()),
1006 // If the where clause cannot fit on the same line,
1007 // put the where clause on a new line
1008 if !where_clause_str.contains('\n')
1009 && last_line_width(&result) + where_clause_str.len() + offset.width()
1010 > context.config.comment_width()
1013 let width = offset.block_indent + context.config.tab_spaces() - 1;
1014 let where_indent = Indent::new(0, width);
1015 result.push_str(&where_indent.to_string(context.config));
1017 result.push_str(&where_clause_str);
1019 if generics.where_clause.predicates.is_empty() {
1020 let item_snippet = context.snippet(item.span);
1021 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1023 let comment_hi = body_lo - BytePos(1);
1024 let comment_lo = item.span.lo() + BytePos(lo as u32);
1025 if comment_lo < comment_hi {
1026 match recover_missing_comment_in_span(
1027 mk_sp(comment_lo, comment_hi),
1028 Shape::indented(offset, context.config),
1030 last_line_width(&result),
1032 Some(ref missing_comment) if !missing_comment.is_empty() => {
1033 result.push_str(missing_comment);
1041 match context.config.item_brace_style() {
1042 _ if last_line_contains_single_line_comment(&result) => {
1044 result.push_str(&offset.to_string(context.config));
1046 BraceStyle::AlwaysNextLine => {
1048 result.push_str(&offset.to_string(context.config));
1050 BraceStyle::PreferSameLine => result.push(' '),
1051 BraceStyle::SameLineWhere => if !where_clause_str.is_empty()
1052 && (!trait_items.is_empty() || result.contains('\n'))
1055 result.push_str(&offset.to_string(context.config));
1062 let snippet = context.snippet(item.span);
1063 let open_pos = snippet.find_uncommented("{")? + 1;
1065 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1066 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
1067 visitor.block_indent = offset.block_only().block_indent(context.config);
1068 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1070 for item in trait_items {
1071 visitor.visit_trait_item(item);
1074 visitor.format_missing(item.span.hi() - BytePos(1));
1076 let inner_indent_str = visitor.block_indent.to_string(context.config);
1077 let outer_indent_str = offset.block_only().to_string(context.config);
1080 result.push_str(&inner_indent_str);
1081 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1083 result.push_str(&outer_indent_str);
1084 } else if result.contains('\n') {
1095 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1096 let header_str = format_header(p.prefix, p.ident, p.vis);
1097 let generics_str = if let Some(generics) = p.generics {
1098 let hi = if generics.where_clause.predicates.is_empty() {
1101 generics.where_clause.span.hi()
1106 context.config.item_brace_style(),
1109 mk_sp(generics.span.lo(), hi),
1110 last_line_width(&header_str),
1115 Some(format!("{}{};", header_str, generics_str))
1118 pub fn format_struct_struct(
1119 context: &RewriteContext,
1120 struct_parts: &StructParts,
1121 fields: &[ast::StructField],
1123 one_line_width: Option<usize>,
1124 ) -> Option<String> {
1125 let mut result = String::with_capacity(1024);
1126 let span = struct_parts.span;
1128 let header_str = struct_parts.format_header();
1129 result.push_str(&header_str);
1131 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1132 let body_lo = context.codemap.span_after(span, "{");
1134 let generics_str = match struct_parts.generics {
1135 Some(g) => format_generics(
1138 context.config.item_brace_style(),
1139 if fields.is_empty() {
1140 BracePos::ForceSameLine
1145 mk_sp(header_hi, body_lo),
1146 last_line_width(&result),
1149 // 3 = ` {}`, 2 = ` {`.
1150 let overhead = if fields.is_empty() { 3 } else { 2 };
1151 if (context.config.item_brace_style() == BraceStyle::AlwaysNextLine
1152 && !fields.is_empty())
1153 || context.config.max_width() < overhead + result.len()
1155 format!("\n{}{{", offset.block_only().to_string(context.config))
1162 let overhead = if fields.is_empty() { 1 } else { 0 };
1163 let total_width = result.len() + generics_str.len() + overhead;
1164 if !generics_str.is_empty() && !generics_str.contains('\n')
1165 && total_width > context.config.max_width()
1168 result.push_str(&offset.to_string(context.config));
1169 result.push_str(generics_str.trim_left());
1171 result.push_str(&generics_str);
1174 if fields.is_empty() {
1175 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1176 if snippet.trim().is_empty() {
1178 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1180 result.push_str(snippet.trim_right());
1182 result.push_str(&offset.to_string(context.config));
1184 result.push_str(&snippet);
1187 return Some(result);
1191 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1192 let one_line_budget =
1193 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1195 let items_str = rewrite_with_alignment(
1198 Shape::indented(offset, context.config),
1199 mk_sp(body_lo, span.hi()),
1203 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget {
1204 Some(format!("{} {} }}", result, items_str))
1210 .block_indent(context.config)
1211 .to_string(context.config),
1213 offset.to_string(context.config)
1218 /// Returns a bytepos that is after that of `(` in `pub(..)`. If the given visibility does not
1219 /// contain `pub(..)`, then return the `lo` of the `defualt_span`. Yeah, but for what? Well, we need
1220 /// to bypass the `(` in the visibility when creating a span of tuple's body or fn's args.
1221 fn get_bytepos_after_visibility(
1222 context: &RewriteContext,
1223 vis: &ast::Visibility,
1228 ast::Visibility::Crate(s, CrateSugar::PubCrate) => context
1230 .span_after(mk_sp(s.hi(), default_span.hi()), terminator),
1231 ast::Visibility::Crate(s, CrateSugar::JustCrate) => s.hi(),
1232 ast::Visibility::Restricted { ref path, .. } => path.span.hi(),
1233 _ => default_span.lo(),
1237 fn format_tuple_struct(
1238 context: &RewriteContext,
1239 struct_parts: &StructParts,
1240 fields: &[ast::StructField],
1242 ) -> Option<String> {
1243 let mut result = String::with_capacity(1024);
1244 let span = struct_parts.span;
1246 let header_str = struct_parts.format_header();
1247 result.push_str(&header_str);
1249 let body_lo = if fields.is_empty() {
1250 let lo = get_bytepos_after_visibility(context, struct_parts.vis, span, ")");
1251 context.codemap.span_after(mk_sp(lo, span.hi()), "(")
1255 let body_hi = if fields.is_empty() {
1256 context.codemap.span_after(mk_sp(body_lo, span.hi()), ")")
1258 // This is a dirty hack to work around a missing `)` from the span of the last field.
1259 let last_arg_span = fields[fields.len() - 1].span;
1260 if context.snippet(last_arg_span).ends_with(')') {
1265 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1269 let where_clause_str = match struct_parts.generics {
1271 let budget = context.budget(last_line_width(&header_str));
1272 let shape = Shape::legacy(budget, offset);
1273 let g_span = mk_sp(span.lo(), body_lo);
1274 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1275 result.push_str(&generics_str);
1277 let where_budget = context.budget(last_line_width(&result));
1278 let option = WhereClauseOption::new(true, false);
1279 rewrite_where_clause(
1281 &generics.where_clause,
1282 context.config.item_brace_style(),
1283 Shape::legacy(where_budget, offset.block_only()),
1284 Density::Compressed,
1292 None => "".to_owned(),
1295 if fields.is_empty() {
1297 let used_width = last_line_used_width(&result, offset.width()) + 3;
1298 if used_width > context.config.max_width() {
1300 result.push_str(&offset
1301 .block_indent(context.config)
1302 .to_string(context.config))
1305 let snippet = context.snippet(mk_sp(
1307 context.codemap.span_before(mk_sp(body_lo, span.hi()), ")"),
1309 if snippet.is_empty() {
1311 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1312 result.push_str(snippet.trim_right());
1314 result.push_str(&offset.to_string(context.config));
1316 result.push_str(&snippet);
1320 let shape = Shape::indented(offset, context.config);
1321 let fields = &fields.iter().map(|field| field).collect::<Vec<_>>()[..];
1322 let one_line_width = context.config.fn_call_width();
1323 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1326 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1327 && (result.contains('\n')
1328 || offset.block_indent + result.len() + where_clause_str.len() + 1
1329 > context.config.max_width())
1331 // We need to put the where clause on a new line, but we didn't
1332 // know that earlier, so the where clause will not be indented properly.
1334 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1335 .to_string(context.config));
1337 result.push_str(&where_clause_str);
1342 pub fn rewrite_type_alias(
1343 context: &RewriteContext,
1347 generics: &ast::Generics,
1348 vis: &ast::Visibility,
1350 ) -> Option<String> {
1351 let mut result = String::with_capacity(128);
1353 result.push_str(&format_visibility(vis));
1354 result.push_str("type ");
1355 result.push_str(&ident.to_string());
1358 let shape = Shape::indented(indent + result.len(), context.config).sub_width(2)?;
1359 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo());
1360 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1361 result.push_str(&generics_str);
1363 let where_budget = context.budget(last_line_width(&result));
1364 let option = WhereClauseOption::snuggled(&result);
1365 let where_clause_str = rewrite_where_clause(
1367 &generics.where_clause,
1368 context.config.item_brace_style(),
1369 Shape::legacy(where_budget, indent),
1370 context.config.where_density(),
1377 result.push_str(&where_clause_str);
1378 if where_clause_str.is_empty() {
1379 result.push_str(" = ");
1381 result.push_str(&format!("\n{}= ", indent.to_string(context.config)));
1384 let line_width = last_line_width(&result);
1385 // This checked_sub may fail as the extra space after '=' is not taken into account
1386 // In that case the budget is set to 0 which will make ty.rewrite retry on a new line
1387 let budget = context.budget(indent.width() + line_width + ";".len());
1388 let type_indent = indent + line_width;
1389 // Try to fit the type on the same line
1390 let ty_str = ty.rewrite(context, Shape::legacy(budget, type_indent))
1392 // The line was too short, try to put the type on the next line
1394 // Remove the space after '='
1396 let type_indent = indent.block_indent(context.config);
1398 result.push_str(&type_indent.to_string(context.config));
1399 let budget = context.budget(type_indent.width() + ";".len());
1400 ty.rewrite(context, Shape::legacy(budget, type_indent))
1402 result.push_str(&ty_str);
1403 result.push_str(";");
1407 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1409 if config.space_before_type_annotation() {
1414 if config.space_after_type_annotation_colon() {
1422 pub fn rewrite_struct_field_prefix(
1423 context: &RewriteContext,
1424 field: &ast::StructField,
1425 ) -> Option<String> {
1426 let vis = format_visibility(&field.vis);
1427 let type_annotation_spacing = type_annotation_spacing(context.config);
1428 Some(match field.ident {
1429 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1430 None => format!("{}", vis),
1434 impl Rewrite for ast::StructField {
1435 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1436 rewrite_struct_field(context, self, shape, 0)
1440 pub fn rewrite_struct_field(
1441 context: &RewriteContext,
1442 field: &ast::StructField,
1444 lhs_max_width: usize,
1445 ) -> Option<String> {
1446 if contains_skip(&field.attrs) {
1447 return Some(context.snippet(mk_sp(field.attrs[0].span.lo(), field.span.hi())));
1450 let type_annotation_spacing = type_annotation_spacing(context.config);
1451 let prefix = rewrite_struct_field_prefix(context, field)?;
1453 let attrs_str = field.attrs.rewrite(context, shape)?;
1454 let attrs_extendable = attrs_str.is_empty()
1455 || (context.config.attributes_on_same_line_as_field()
1456 && is_attributes_extendable(&attrs_str));
1457 let missing_span = if field.attrs.is_empty() {
1458 mk_sp(field.span.lo(), field.span.lo())
1460 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1462 let mut spacing = String::from(if field.ident.is_some() {
1463 type_annotation_spacing.1
1467 // Try to put everything on a single line.
1468 let attr_prefix = combine_strs_with_missing_comments(
1476 let overhead = last_line_width(&attr_prefix);
1477 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1478 for _ in 0..lhs_offset {
1481 // In this extreme case we will be missing a space betweeen an attribute and a field.
1482 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1485 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1486 if let Some(ref ty) = field.ty.rewrite(context, ty_shape) {
1487 if !ty.contains('\n') {
1488 return Some(attr_prefix + &spacing + ty);
1492 // We must use multiline.
1493 let new_shape = shape.with_max_width(context.config);
1494 let ty_rewritten = field.ty.rewrite(context, new_shape)?;
1496 let field_str = if prefix.is_empty() {
1498 } else if prefix.len() + first_line_width(&ty_rewritten) + 1 <= shape.width {
1499 prefix + " " + &ty_rewritten
1501 let type_offset = shape.indent.block_indent(context.config);
1502 let nested_shape = Shape::indented(type_offset, context.config);
1503 let nested_ty = field.ty.rewrite(context, nested_shape)?;
1504 prefix + "\n" + &type_offset.to_string(context.config) + &nested_ty
1506 combine_strs_with_missing_comments(
1516 pub struct StaticParts<'a> {
1518 vis: &'a ast::Visibility,
1521 mutability: ast::Mutability,
1522 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1526 impl<'a> StaticParts<'a> {
1527 pub fn from_item(item: &'a ast::Item) -> Self {
1528 let (prefix, ty, mutability, expr) = match item.node {
1529 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1530 ast::ItemKind::Const(ref ty, ref expr) => {
1531 ("const", ty, ast::Mutability::Immutable, expr)
1533 _ => unreachable!(),
1540 mutability: mutability,
1541 expr_opt: Some(expr),
1546 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1547 let (ty, expr_opt) = match ti.node {
1548 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1549 _ => unreachable!(),
1553 vis: &ast::Visibility::Inherited,
1556 mutability: ast::Mutability::Immutable,
1557 expr_opt: expr_opt.as_ref(),
1562 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1563 let (ty, expr) = match ii.node {
1564 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1565 _ => unreachable!(),
1572 mutability: ast::Mutability::Immutable,
1573 expr_opt: Some(expr),
1580 context: &RewriteContext,
1581 static_parts: &StaticParts,
1583 ) -> Option<String> {
1584 let colon = colon_spaces(
1585 context.config.space_before_type_annotation(),
1586 context.config.space_after_type_annotation_colon(),
1588 let prefix = format!(
1590 format_visibility(static_parts.vis),
1591 static_parts.prefix,
1592 format_mutability(static_parts.mutability),
1598 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1599 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1601 if let Some(expr) = static_parts.expr_opt {
1602 let lhs = format!("{}{} =", prefix, ty_str);
1604 let remaining_width = context.budget(offset.block_indent + 1);
1609 Shape::legacy(remaining_width, offset.block_only()),
1611 recover_comment_removed(res, static_parts.span, context)
1613 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1615 Some(format!("{}{};", prefix, ty_str))
1619 pub fn rewrite_associated_type(
1621 ty_opt: Option<&ptr::P<ast::Ty>>,
1622 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1623 context: &RewriteContext,
1625 ) -> Option<String> {
1626 let prefix = format!("type {}", ident);
1628 let type_bounds_str = if let Some(ty_param_bounds) = ty_param_bounds_opt {
1630 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1631 let bounds: &[_] = ty_param_bounds;
1632 let bound_str = bounds
1634 .map(|ty_bound| ty_bound.rewrite(context, shape))
1635 .collect::<Option<Vec<_>>>()?;
1636 if !bounds.is_empty() {
1637 format!(": {}", join_bounds(context, shape, &bound_str))
1645 if let Some(ty) = ty_opt {
1646 let ty_str = ty.rewrite(
1649 context.budget(indent.block_indent + prefix.len() + 2),
1650 indent.block_only(),
1653 Some(format!("{}{} = {};", prefix, type_bounds_str, ty_str))
1655 Some(format!("{}{};", prefix, type_bounds_str))
1659 pub fn rewrite_associated_impl_type(
1661 defaultness: ast::Defaultness,
1662 ty_opt: Option<&ptr::P<ast::Ty>>,
1663 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1664 context: &RewriteContext,
1666 ) -> Option<String> {
1667 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1670 ast::Defaultness::Default => Some(format!("default {}", result)),
1675 impl Rewrite for ast::FunctionRetTy {
1676 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1678 ast::FunctionRetTy::Default(_) => Some(String::new()),
1679 ast::FunctionRetTy::Ty(ref ty) => {
1680 let inner_width = shape.width.checked_sub(3)?;
1681 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1682 .map(|r| format!("-> {}", r))
1688 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1690 ast::TyKind::Infer => {
1691 let original = context.snippet(ty.span);
1698 impl Rewrite for ast::Arg {
1699 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1700 if is_named_arg(self) {
1701 let mut result = self.pat
1702 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1704 if !is_empty_infer(context, &*self.ty) {
1705 if context.config.space_before_type_annotation() {
1706 result.push_str(" ");
1708 result.push_str(":");
1709 if context.config.space_after_type_annotation_colon() {
1710 result.push_str(" ");
1712 let overhead = last_line_width(&result);
1713 let max_width = shape.width.checked_sub(overhead)?;
1714 let ty_str = self.ty
1715 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1716 result.push_str(&ty_str);
1721 self.ty.rewrite(context, shape)
1726 fn rewrite_explicit_self(
1727 explicit_self: &ast::ExplicitSelf,
1729 context: &RewriteContext,
1730 ) -> Option<String> {
1731 match explicit_self.node {
1732 ast::SelfKind::Region(lt, m) => {
1733 let mut_str = format_mutability(m);
1736 let lifetime_str = l.rewrite(
1738 Shape::legacy(context.config.max_width(), Indent::empty()),
1740 Some(format!("&{} {}self", lifetime_str, mut_str))
1742 None => Some(format!("&{}self", mut_str)),
1745 ast::SelfKind::Explicit(ref ty, _) => {
1746 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1748 let mutability = explicit_self_mutability(&args[0]);
1749 let type_str = ty.rewrite(
1751 Shape::legacy(context.config.max_width(), Indent::empty()),
1756 format_mutability(mutability),
1760 ast::SelfKind::Value(_) => {
1761 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1763 let mutability = explicit_self_mutability(&args[0]);
1765 Some(format!("{}self", format_mutability(mutability)))
1770 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1771 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1772 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1773 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1780 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1781 if is_named_arg(arg) {
1788 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1790 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1791 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1792 _ => arg.ty.span.hi(),
1796 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1797 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1798 ident.node != symbol::keywords::Invalid.ident()
1804 // Return type is (result, force_new_line_for_brace)
1806 context: &RewriteContext,
1811 newline_brace: bool,
1813 ) -> Option<(String, bool)> {
1814 let mut force_new_line_for_brace = false;
1816 let where_clause = &fn_sig.generics.where_clause;
1818 let mut result = String::with_capacity(1024);
1819 result.push_str(&fn_sig.to_str(context));
1822 result.push_str("fn ");
1823 result.push_str(&ident.to_string());
1826 let overhead = if has_body && !newline_brace {
1833 let used_width = last_line_used_width(&result, indent.width());
1834 let one_line_budget = context.budget(used_width + overhead);
1836 width: one_line_budget,
1840 let fd = fn_sig.decl;
1841 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1842 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1843 result.push_str(&generics_str);
1845 let snuggle_angle_bracket = generics_str
1848 .map_or(false, |l| l.trim_left().len() == 1);
1850 // Note that the width and indent don't really matter, we'll re-layout the
1851 // return type later anyway.
1852 let ret_str = fd.output
1853 .rewrite(context, Shape::indented(indent, context.config))?;
1855 let multi_line_ret_str = ret_str.contains('\n');
1856 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1859 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1870 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1876 // Check if vertical layout was forced.
1877 if one_line_budget == 0 {
1878 if snuggle_angle_bracket {
1880 } else if context.config.fn_args_paren_newline() {
1882 result.push_str(&arg_indent.to_string(context.config));
1883 if context.config.indent_style() == IndentStyle::Visual {
1884 arg_indent = arg_indent + 1; // extra space for `(`
1888 result.push_str("(");
1889 if context.config.indent_style() == IndentStyle::Visual {
1891 result.push_str(&arg_indent.to_string(context.config));
1897 if context.config.spaces_within_parens() && !fd.inputs.is_empty() && result.ends_with('(') {
1901 // Skip `pub(crate)`.
1902 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1903 // A conservative estimation, to goal is to be over all parens in generics
1904 let args_start = fn_sig
1908 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1909 let args_end = if fd.inputs.is_empty() {
1912 .span_after(mk_sp(args_start, span.hi()), ")")
1914 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1915 context.codemap.span_after(last_span, ")")
1917 let args_span = mk_sp(
1920 .span_after(mk_sp(args_start, span.hi()), "("),
1923 let arg_str = rewrite_args(
1926 fd.get_self().as_ref(),
1933 generics_str.contains('\n'),
1936 let put_args_in_block = match context.config.indent_style() {
1937 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1939 } && !fd.inputs.is_empty();
1941 let mut args_last_line_contains_comment = false;
1942 if put_args_in_block {
1943 arg_indent = indent.block_indent(context.config);
1945 result.push_str(&arg_indent.to_string(context.config));
1946 result.push_str(&arg_str);
1948 result.push_str(&indent.to_string(context.config));
1951 result.push_str(&arg_str);
1952 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1953 // Put the closing brace on the next line if it overflows the max width.
1955 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1958 if context.config.spaces_within_parens() && !fd.inputs.is_empty() {
1961 // If the last line of args contains comment, we cannot put the closing paren
1962 // on the same line.
1966 .map_or(false, |last_line| last_line.contains("//"))
1968 args_last_line_contains_comment = true;
1970 result.push_str(&arg_indent.to_string(context.config));
1976 if let ast::FunctionRetTy::Ty(..) = fd.output {
1977 let ret_should_indent = match context.config.indent_style() {
1978 // If our args are block layout then we surely must have space.
1979 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1980 _ if args_last_line_contains_comment => false,
1981 _ if result.contains('\n') || multi_line_ret_str => true,
1983 // If the return type would push over the max width, then put the return type on
1984 // a new line. With the +1 for the signature length an additional space between
1985 // the closing parenthesis of the argument and the arrow '->' is considered.
1986 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1988 // If there is no where clause, take into account the space after the return type
1990 if where_clause.predicates.is_empty() {
1994 sig_length > context.config.max_width()
1997 let ret_indent = if ret_should_indent {
1998 let indent = match context.config.fn_return_indent() {
1999 ReturnIndent::WithWhereClause => indent + 4,
2000 // Aligning with non-existent args looks silly.
2001 _ if arg_str.is_empty() => {
2002 force_new_line_for_brace = true;
2005 // FIXME: we might want to check that using the arg indent
2006 // doesn't blow our budget, and if it does, then fallback to
2007 // the where clause indent.
2012 result.push_str(&indent.to_string(context.config));
2016 Indent::new(indent.block_indent, last_line_width(&result))
2019 if multi_line_ret_str || ret_should_indent {
2020 // Now that we know the proper indent and width, we need to
2021 // re-layout the return type.
2022 let ret_str = fd.output
2023 .rewrite(context, Shape::indented(ret_indent, context.config))?;
2024 result.push_str(&ret_str);
2026 result.push_str(&ret_str);
2029 // Comment between return type and the end of the decl.
2030 let snippet_lo = fd.output.span().hi();
2031 if where_clause.predicates.is_empty() {
2032 let snippet_hi = span.hi();
2033 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2034 // Try to preserve the layout of the original snippet.
2035 let original_starts_with_newline = snippet
2037 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2038 let original_ends_with_newline = snippet
2039 .rfind(|c| c != ' ')
2040 .map_or(false, |i| snippet[i..].ends_with('\n'));
2041 let snippet = snippet.trim();
2042 if !snippet.is_empty() {
2043 result.push(if original_starts_with_newline {
2048 result.push_str(snippet);
2049 if original_ends_with_newline {
2050 force_new_line_for_brace = true;
2056 let should_compress_where = match context.config.where_density() {
2057 Density::Compressed => !result.contains('\n'),
2058 Density::CompressedIfEmpty => !has_body && !result.contains('\n'),
2062 let pos_before_where = match fd.output {
2063 ast::FunctionRetTy::Default(..) => args_span.hi(),
2064 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2067 let is_args_multi_lined = arg_str.contains('\n');
2069 if where_clause.predicates.len() == 1 && should_compress_where {
2070 let budget = context.budget(last_line_used_width(&result, indent.width()));
2071 if let Some(where_clause_str) = rewrite_where_clause(
2074 context.config.fn_brace_style(),
2075 Shape::legacy(budget, indent),
2076 Density::Compressed,
2080 WhereClauseOption::compressed(),
2081 is_args_multi_lined,
2083 result.push_str(&where_clause_str);
2084 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2085 return Some((result, force_new_line_for_brace));
2089 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2090 let where_clause_str = rewrite_where_clause(
2093 context.config.fn_brace_style(),
2094 Shape::indented(indent, context.config),
2100 is_args_multi_lined,
2102 // If there are neither where clause nor return type, we may be missing comments between
2104 if where_clause_str.is_empty() {
2105 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2106 match recover_missing_comment_in_span(
2107 mk_sp(args_span.hi(), ret_span.hi()),
2110 last_line_width(&result),
2112 Some(ref missing_comment) if !missing_comment.is_empty() => {
2113 result.push_str(missing_comment);
2114 force_new_line_for_brace = true;
2121 result.push_str(&where_clause_str);
2123 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2124 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2125 Some((result, force_new_line_for_brace))
2128 #[derive(Copy, Clone)]
2129 struct WhereClauseOption {
2130 suppress_comma: bool, // Force no trailing comma
2131 snuggle: bool, // Do not insert newline before `where`
2132 compress_where: bool, // Try single line where clause instead of vertical layout
2135 impl WhereClauseOption {
2136 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2138 suppress_comma: suppress_comma,
2140 compress_where: false,
2144 pub fn compressed() -> WhereClauseOption {
2146 suppress_comma: true,
2148 compress_where: true,
2152 pub fn snuggled(current: &str) -> WhereClauseOption {
2154 suppress_comma: false,
2155 snuggle: trimmed_last_line_width(current) == 1,
2156 compress_where: false,
2162 context: &RewriteContext,
2164 explicit_self: Option<&ast::ExplicitSelf>,
2165 one_line_budget: usize,
2166 multi_line_budget: usize,
2171 generics_str_contains_newline: bool,
2172 ) -> Option<String> {
2173 let mut arg_item_strs = args.iter()
2175 arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent))
2177 .collect::<Option<Vec<_>>>()?;
2179 // Account for sugary self.
2180 // FIXME: the comment for the self argument is dropped. This is blocked
2181 // on rust issue #27522.
2182 let min_args = explicit_self
2183 .and_then(|explicit_self| {
2184 rewrite_explicit_self(explicit_self, args, context)
2186 .map_or(1, |self_str| {
2187 arg_item_strs[0] = self_str;
2191 // Comments between args.
2192 let mut arg_items = Vec::new();
2194 arg_items.push(ListItem::from_str(""));
2197 // FIXME(#21): if there are no args, there might still be a comment, but
2198 // without spans for the comment or parens, there is no chance of
2199 // getting it right. You also don't get to put a comment on self, unless
2201 if args.len() >= min_args || variadic {
2202 let comment_span_start = if min_args == 2 {
2203 let second_arg_start = if arg_has_pattern(&args[1]) {
2204 args[1].pat.span.lo()
2206 args[1].ty.span.lo()
2208 let reduced_span = mk_sp(span.lo(), second_arg_start);
2210 context.codemap.span_after_last(reduced_span, ",")
2215 enum ArgumentKind<'a> {
2216 Regular(&'a ast::Arg),
2220 let variadic_arg = if variadic {
2221 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2222 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2223 Some(ArgumentKind::Variadic(variadic_start))
2228 let more_items = itemize_list(
2230 args[min_args - 1..]
2232 .map(ArgumentKind::Regular)
2233 .chain(variadic_arg),
2236 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2237 ArgumentKind::Variadic(start) => start,
2240 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2241 ArgumentKind::Variadic(start) => start + BytePos(3),
2244 ArgumentKind::Regular(..) => None,
2245 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2252 arg_items.extend(more_items);
2255 let fits_in_one_line = !generics_str_contains_newline
2256 && (arg_items.is_empty()
2257 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2259 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2260 item.item = Some(arg);
2263 let last_line_ends_with_comment = arg_items
2266 .and_then(|item| item.post_comment.as_ref())
2267 .map_or(false, |s| s.trim().starts_with("//"));
2269 let (indent, trailing_comma) = match context.config.indent_style() {
2270 IndentStyle::Block if fits_in_one_line => {
2271 (indent.block_indent(context.config), SeparatorTactic::Never)
2273 IndentStyle::Block => (
2274 indent.block_indent(context.config),
2275 context.config.trailing_comma(),
2277 IndentStyle::Visual if last_line_ends_with_comment => {
2278 (arg_indent, context.config.trailing_comma())
2280 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2283 let tactic = definitive_tactic(
2285 context.config.fn_args_density().to_list_tactic(),
2289 let budget = match tactic {
2290 DefinitiveListTactic::Horizontal => one_line_budget,
2291 _ => multi_line_budget,
2294 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2296 let fmt = ListFormatting {
2299 trailing_separator: if variadic {
2300 SeparatorTactic::Never
2304 separator_place: SeparatorPlace::Back,
2305 shape: Shape::legacy(budget, indent),
2306 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2307 preserve_newline: true,
2308 config: context.config,
2311 write_list(&arg_items, &fmt)
2314 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2315 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2316 ident.node != symbol::keywords::Invalid.ident()
2322 fn compute_budgets_for_args(
2323 context: &RewriteContext,
2327 newline_brace: bool,
2329 force_vertical_layout: bool,
2330 ) -> Option<((usize, usize, Indent))> {
2332 "compute_budgets_for_args {} {:?}, {}, {}",
2338 // Try keeping everything on the same line.
2339 if !result.contains('\n') && !force_vertical_layout {
2340 // 2 = `()`, 3 = `() `, space is before ret_string.
2341 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2342 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2352 let one_line_budget = context.budget(used_space);
2354 if one_line_budget > 0 {
2356 let (indent, multi_line_budget) = match context.config.indent_style() {
2357 IndentStyle::Block => {
2358 let indent = indent.block_indent(context.config);
2359 (indent, context.budget(indent.width() + 1))
2361 IndentStyle::Visual => {
2362 let indent = indent + result.len() + 1;
2363 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2364 (indent, context.budget(multi_line_overhead))
2368 return Some((one_line_budget, multi_line_budget, indent));
2372 // Didn't work. we must force vertical layout and put args on a newline.
2373 let new_indent = indent.block_indent(context.config);
2374 let used_space = match context.config.indent_style() {
2376 IndentStyle::Block => new_indent.width() + 1,
2377 // Account for `)` and possibly ` {`.
2378 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2380 Some((0, context.budget(used_space), new_indent))
2383 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause, has_body: bool) -> bool {
2384 let predicate_count = where_clause.predicates.len();
2386 if config.where_single_line() && predicate_count == 1 {
2389 match (config.fn_brace_style(), config.where_density()) {
2390 (BraceStyle::AlwaysNextLine, _) => true,
2391 (_, Density::Compressed) if predicate_count == 1 => false,
2392 (_, Density::CompressedIfEmpty) if predicate_count == 1 && !has_body => false,
2393 (BraceStyle::SameLineWhere, _) if predicate_count > 0 => true,
2398 fn rewrite_generics(
2399 context: &RewriteContext,
2400 generics: &ast::Generics,
2403 ) -> Option<String> {
2404 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2405 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2406 rewrite_generics_inner(context, generics, g_shape, one_line_width, span).or_else(|| {
2407 rewrite_generics_inner(context, generics, g_shape, 0, span)
2411 fn rewrite_generics_inner(
2412 context: &RewriteContext,
2413 generics: &ast::Generics,
2415 one_line_width: usize,
2417 ) -> Option<String> {
2418 // FIXME: convert bounds to where clauses where they get too big or if
2419 // there is a where clause at all.
2422 enum GenericsArg<'a> {
2423 Lifetime(&'a ast::LifetimeDef),
2424 TyParam(&'a ast::TyParam),
2426 impl<'a> Rewrite for GenericsArg<'a> {
2427 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2429 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2430 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2434 impl<'a> Spanned for GenericsArg<'a> {
2435 fn span(&self) -> Span {
2437 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2438 GenericsArg::TyParam(ty) => ty.span(),
2443 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2444 return Some(String::new());
2447 let generics_args = generics
2450 .map(|lt| GenericsArg::Lifetime(lt))
2451 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2452 let items = itemize_list(
2456 |arg| arg.span().lo(),
2457 |arg| arg.span().hi(),
2458 |arg| arg.rewrite(context, shape),
2459 context.codemap.span_after(span, "<"),
2463 format_generics_item_list(context, items, shape, one_line_width)
2466 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2467 match config.indent_style() {
2468 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2469 IndentStyle::Block => {
2473 .block_indent(config.tab_spaces())
2474 .with_max_width(config)
2480 pub fn format_generics_item_list<I>(
2481 context: &RewriteContext,
2484 one_line_budget: usize,
2487 I: Iterator<Item = ListItem>,
2489 let item_vec = items.collect::<Vec<_>>();
2491 let tactic = definitive_tactic(
2493 ListTactic::HorizontalVertical,
2497 let fmt = ListFormatting {
2500 trailing_separator: if context.config.indent_style() == IndentStyle::Visual {
2501 SeparatorTactic::Never
2503 context.config.trailing_comma()
2505 separator_place: SeparatorPlace::Back,
2507 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2508 preserve_newline: true,
2509 config: context.config,
2512 let list_str = write_list(&item_vec, &fmt)?;
2514 Some(wrap_generics_with_angle_brackets(
2521 pub fn wrap_generics_with_angle_brackets(
2522 context: &RewriteContext,
2524 list_offset: Indent,
2526 if context.config.indent_style() == IndentStyle::Block
2527 && (list_str.contains('\n') || list_str.ends_with(','))
2531 list_offset.to_string(context.config),
2534 .block_unindent(context.config)
2535 .to_string(context.config)
2537 } else if context.config.spaces_within_angle_brackets() {
2538 format!("< {} >", list_str)
2540 format!("<{}>", list_str)
2544 fn rewrite_trait_bounds(
2545 context: &RewriteContext,
2546 type_param_bounds: &ast::TyParamBounds,
2548 ) -> Option<String> {
2549 let bounds: &[_] = type_param_bounds;
2551 if bounds.is_empty() {
2552 return Some(String::new());
2554 let bound_str = bounds
2556 .map(|ty_bound| ty_bound.rewrite(context, shape))
2557 .collect::<Option<Vec<_>>>()?;
2558 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2561 fn rewrite_where_clause_rfc_style(
2562 context: &RewriteContext,
2563 where_clause: &ast::WhereClause,
2566 span_end: Option<BytePos>,
2567 span_end_before_where: BytePos,
2568 where_clause_option: WhereClauseOption,
2569 is_args_multi_line: bool,
2570 ) -> Option<String> {
2571 let block_shape = shape.block().with_max_width(context.config);
2573 let (span_before, span_after) =
2574 missing_span_before_after_where(span_end_before_where, where_clause);
2575 let (comment_before, comment_after) =
2576 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2578 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2581 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2584 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2586 let clause_shape = clause_shape.sub_width(1)?;
2587 // each clause on one line, trailing comma (except if suppress_comma)
2588 let span_start = where_clause.predicates[0].span().lo();
2589 // If we don't have the start of the next span, then use the end of the
2590 // predicates, but that means we miss comments.
2591 let len = where_clause.predicates.len();
2592 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2593 let span_end = span_end.unwrap_or(end_of_preds);
2594 let items = itemize_list(
2596 where_clause.predicates.iter(),
2598 |pred| pred.span().lo(),
2599 |pred| pred.span().hi(),
2600 |pred| pred.rewrite(context, clause_shape),
2605 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2606 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2607 SeparatorTactic::Never
2609 context.config.trailing_comma()
2612 // shape should be vertical only and only if we have `where_single_line` option enabled
2613 // and the number of items of the where clause is equal to 1
2614 let shape_tactic = if where_single_line {
2615 DefinitiveListTactic::Horizontal
2617 DefinitiveListTactic::Vertical
2620 let fmt = ListFormatting {
2621 tactic: shape_tactic,
2623 trailing_separator: comma_tactic,
2624 separator_place: SeparatorPlace::Back,
2625 shape: clause_shape,
2626 ends_with_newline: true,
2627 preserve_newline: true,
2628 config: context.config,
2630 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2632 let comment_separator = |comment: &str, shape: Shape| if comment.is_empty() {
2635 format!("\n{}", shape.indent.to_string(context.config))
2637 let newline_before_where = comment_separator(&comment_before, shape);
2638 let newline_after_where = comment_separator(&comment_after, clause_shape);
2641 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2642 && comment_after.is_empty() && !preds_str.contains('\n')
2643 && 6 + preds_str.len() <= shape.width || where_single_line
2647 format!("\n{}", clause_shape.indent.to_string(context.config))
2650 "{}{}{}where{}{}{}{}",
2653 newline_before_where,
2654 newline_after_where,
2661 fn rewrite_where_clause(
2662 context: &RewriteContext,
2663 where_clause: &ast::WhereClause,
2664 brace_style: BraceStyle,
2668 span_end: Option<BytePos>,
2669 span_end_before_where: BytePos,
2670 where_clause_option: WhereClauseOption,
2671 is_args_multi_line: bool,
2672 ) -> Option<String> {
2673 if where_clause.predicates.is_empty() {
2674 return Some(String::new());
2677 if context.config.indent_style() == IndentStyle::Block {
2678 return rewrite_where_clause_rfc_style(
2684 span_end_before_where,
2685 where_clause_option,
2690 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2692 let offset = match context.config.indent_style() {
2693 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2694 // 6 = "where ".len()
2695 IndentStyle::Visual => shape.indent + extra_indent + 6,
2697 // FIXME: if indent_style != Visual, then the budgets below might
2698 // be out by a char or two.
2700 let budget = context.config.max_width() - offset.width();
2701 let span_start = where_clause.predicates[0].span().lo();
2702 // If we don't have the start of the next span, then use the end of the
2703 // predicates, but that means we miss comments.
2704 let len = where_clause.predicates.len();
2705 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2706 let span_end = span_end.unwrap_or(end_of_preds);
2707 let items = itemize_list(
2709 where_clause.predicates.iter(),
2711 |pred| pred.span().lo(),
2712 |pred| pred.span().hi(),
2713 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2718 let item_vec = items.collect::<Vec<_>>();
2719 // FIXME: we don't need to collect here if the where_layout isn't
2720 // HorizontalVertical.
2721 let tactic = definitive_tactic(
2723 context.config.where_layout(),
2728 let mut comma_tactic = context.config.trailing_comma();
2729 // Kind of a hack because we don't usually have trailing commas in where clauses.
2730 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2731 comma_tactic = SeparatorTactic::Never;
2734 let fmt = ListFormatting {
2737 trailing_separator: comma_tactic,
2738 separator_place: SeparatorPlace::Back,
2739 shape: Shape::legacy(budget, offset),
2740 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2741 preserve_newline: true,
2742 config: context.config,
2744 let preds_str = write_list(&item_vec, &fmt)?;
2746 let end_length = if terminator == "{" {
2747 // If the brace is on the next line we don't need to count it otherwise it needs two
2750 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2751 BraceStyle::PreferSameLine => 2,
2753 } else if terminator == "=" {
2758 if density == Density::Tall || preds_str.contains('\n')
2759 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2763 (shape.indent + extra_indent).to_string(context.config),
2767 Some(format!(" where {}", preds_str))
2771 fn missing_span_before_after_where(
2772 before_item_span_end: BytePos,
2773 where_clause: &ast::WhereClause,
2775 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2777 let pos_after_where = where_clause.span.lo() + BytePos(5);
2778 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2779 (missing_span_before, missing_span_after)
2782 fn rewrite_comments_before_after_where(
2783 context: &RewriteContext,
2784 span_before_where: Span,
2785 span_after_where: Span,
2787 ) -> Option<(String, String)> {
2788 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2789 let after_comment = rewrite_missing_comment(
2791 shape.block_indent(context.config.tab_spaces()),
2794 Some((before_comment, after_comment))
2797 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2798 format!("{}{}{}", format_visibility(vis), item_name, ident)
2801 #[derive(PartialEq, Eq)]
2809 context: &RewriteContext,
2810 generics: &ast::Generics,
2811 brace_style: BraceStyle,
2812 brace_pos: BracePos,
2816 ) -> Option<String> {
2817 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2818 let mut result = rewrite_generics(context, generics, shape, span)?;
2820 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2821 let budget = context.budget(last_line_used_width(&result, offset.width()));
2822 let mut option = WhereClauseOption::snuggled(&result);
2823 if brace_pos == BracePos::None {
2824 option.suppress_comma = true;
2826 // If the generics are not parameterized then generics.span.hi() == 0,
2827 // so we use span.lo(), which is the position after `struct Foo`.
2828 let span_end_before_where = if generics.is_parameterized() {
2833 let where_clause_str = rewrite_where_clause(
2835 &generics.where_clause,
2837 Shape::legacy(budget, offset.block_only()),
2841 span_end_before_where,
2845 result.push_str(&where_clause_str);
2846 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2847 || (generics.where_clause.predicates.is_empty()
2848 && trimmed_last_line_width(&result) == 1)
2850 brace_pos == BracePos::ForceSameLine || trimmed_last_line_width(&result) == 1
2851 || brace_style != BraceStyle::AlwaysNextLine
2853 if brace_pos == BracePos::None {
2854 return Some(result);
2856 let total_used_width = last_line_used_width(&result, used_width);
2857 let remaining_budget = context.budget(total_used_width);
2858 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2859 // and hence we take the closer into account as well for one line budget.
2860 // We assume that the closer has the same length as the opener.
2861 let overhead = if brace_pos == BracePos::ForceSameLine {
2868 let forbid_same_line_brace = overhead > remaining_budget;
2869 if !forbid_same_line_brace && same_line_brace {
2873 result.push_str(&offset.block_only().to_string(context.config));
2880 impl Rewrite for ast::ForeignItem {
2881 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2882 let attrs_str = self.attrs.rewrite(context, shape)?;
2883 // Drop semicolon or it will be interpreted as comment.
2884 // FIXME: this may be a faulty span from libsyntax.
2885 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2887 let item_str = match self.node {
2888 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2893 &FnSig::new(fn_decl, generics, self.vis.clone()),
2897 ).map(|(s, _)| format!("{};", s))
2899 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2900 // FIXME(#21): we're dropping potential comments in between the
2901 // function keywords here.
2902 let vis = format_visibility(&self.vis);
2903 let mut_str = if is_mutable { "mut " } else { "" };
2904 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2906 let shape = shape.sub_width(1)?;
2907 ty.rewrite(context, shape).map(|ty_str| {
2908 // 1 = space between prefix and type.
2909 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2912 let nested_indent = shape.indent.block_indent(context.config);
2913 format!("\n{}", nested_indent.to_string(context.config))
2915 format!("{}{}{};", prefix, sep, ty_str)
2918 ast::ForeignItemKind::Ty => {
2919 let vis = format_visibility(&self.vis);
2920 Some(format!("{}type {};", vis, self.ident))
2924 let missing_span = if self.attrs.is_empty() {
2925 mk_sp(self.span.lo(), self.span.lo())
2927 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2929 combine_strs_with_missing_comments(