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, Style};
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 enum_def.variants.is_empty(),
446 mk_sp(span.lo(), body_start),
447 last_line_width(&enum_header),
449 self.buffer.push_str(&generics_str);
451 self.last_pos = body_start;
453 self.block_indent = self.block_indent.block_indent(self.config);
454 let variant_list = self.format_variant_list(enum_def, body_start, span.hi() - BytePos(1));
456 Some(ref body_str) => self.buffer.push_str(body_str),
457 None => if contains_comment(&enum_snippet[brace_pos..]) {
458 self.format_missing_no_indent(span.hi() - BytePos(1))
461 self.block_indent = self.block_indent.block_unindent(self.config);
463 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
465 .push_str(&self.block_indent.to_string(self.config));
467 self.buffer.push_str("}");
468 self.last_pos = span.hi();
471 // Format the body of an enum definition
472 fn format_variant_list(
474 enum_def: &ast::EnumDef,
477 ) -> Option<String> {
478 if enum_def.variants.is_empty() {
481 let mut result = String::with_capacity(1024);
483 let indentation = self.block_indent.to_string(self.config);
484 result.push_str(&indentation);
486 let items = itemize_list(
488 enum_def.variants.iter(),
490 |f| if !f.node.attrs.is_empty() {
491 f.node.attrs[0].span.lo()
496 |f| self.format_variant(f),
502 let shape = self.shape().sub_width(2).unwrap();
503 let fmt = ListFormatting {
504 tactic: DefinitiveListTactic::Vertical,
506 trailing_separator: self.config.trailing_comma(),
507 separator_place: SeparatorPlace::Back,
509 ends_with_newline: true,
510 preserve_newline: true,
514 let list = write_list(&items.collect::<Vec<_>>(), &fmt)?;
515 result.push_str(&list);
520 // Variant of an enum.
521 fn format_variant(&self, field: &ast::Variant) -> Option<String> {
522 if contains_skip(&field.node.attrs) {
523 let lo = field.node.attrs[0].span.lo();
524 let span = mk_sp(lo, field.span.hi());
525 return Some(self.snippet(span));
528 let context = self.get_context();
529 let indent = self.block_indent;
530 let shape = self.shape();
531 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
536 .map_or(field.span.lo(), |attr| attr.span.hi());
537 let span = mk_sp(lo, field.span.lo());
539 let variant_body = match field.node.data {
540 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => {
541 // FIXME: Should limit the width, as we have a trailing comma
544 &StructParts::from_variant(field),
546 Some(self.config.struct_variant_width()),
549 ast::VariantData::Unit(..) => if let Some(ref expr) = field.node.disr_expr {
550 let lhs = format!("{} =", field.node.name);
552 rewrite_assign_rhs(&context, lhs, expr, shape.sub_width(1)?)?
554 field.node.name.to_string()
558 let attrs_extendable = attrs_str.is_empty()
559 || (context.config.attributes_on_same_line_as_variant()
560 && is_attributes_extendable(&attrs_str));
561 combine_strs_with_missing_comments(
573 context: &RewriteContext,
576 where_span_end: Option<BytePos>,
577 ) -> Option<String> {
578 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
579 let mut result = String::with_capacity(128);
580 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
581 let indent_str = offset.to_string(context.config);
582 let sep = format!("\n{}", &indent_str);
583 result.push_str(&ref_and_type);
585 let where_budget = if result.contains('\n') {
586 context.config.max_width()
588 context.budget(last_line_width(&result))
590 let option = WhereClauseOption::snuggled(&ref_and_type);
591 let where_clause_str = rewrite_where_clause(
593 &generics.where_clause,
594 context.config.item_brace_style(),
595 Shape::legacy(where_budget, offset.block_only()),
596 context.config.where_density(),
604 // If there is no where clause, we may have missing comments between the trait name and
605 // the opening brace.
606 if generics.where_clause.predicates.is_empty() {
607 if let Some(hi) = where_span_end {
608 match recover_missing_comment_in_span(
609 mk_sp(self_ty.span.hi(), hi),
610 Shape::indented(offset, context.config),
612 last_line_width(&result),
614 Some(ref missing_comment) if !missing_comment.is_empty() => {
615 result.push_str(missing_comment);
622 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
623 result.push_str(&where_clause_str);
624 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
625 result.push_str(&format!("{}{{{}}}", &sep, &sep));
627 result.push_str(" {}");
632 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
634 let width = offset.block_indent + context.config.tab_spaces() - 1;
635 let where_indent = Indent::new(0, width);
636 result.push_str(&where_indent.to_string(context.config));
638 result.push_str(&where_clause_str);
640 match context.config.item_brace_style() {
641 _ if last_line_contains_single_line_comment(&result) => result.push_str(&sep),
642 BraceStyle::AlwaysNextLine => result.push_str(&sep),
643 BraceStyle::PreferSameLine => result.push(' '),
644 BraceStyle::SameLineWhere => if !where_clause_str.is_empty() {
645 result.push_str(&sep);
653 let snippet = context.snippet(item.span);
654 let open_pos = snippet.find_uncommented("{")? + 1;
656 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
657 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
658 visitor.block_indent = offset.block_only().block_indent(context.config);
659 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
661 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
663 visitor.visit_impl_item(item);
666 visitor.format_missing(item.span.hi() - BytePos(1));
668 let inner_indent_str = visitor.block_indent.to_string(context.config);
669 let outer_indent_str = offset.block_only().to_string(context.config);
672 result.push_str(&inner_indent_str);
673 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
675 result.push_str(&outer_indent_str);
678 if result.ends_with('{') {
679 result.push_str(&sep);
689 fn is_impl_single_line(
690 context: &RewriteContext,
693 where_clause_str: &str,
696 let snippet = context.snippet(item.span);
697 let open_pos = snippet.find_uncommented("{")? + 1;
700 context.config.impl_empty_single_line() && items.is_empty() && !result.contains('\n')
701 && result.len() + where_clause_str.len() <= context.config.max_width()
702 && !contains_comment(&snippet[open_pos..]),
706 fn format_impl_ref_and_type(
707 context: &RewriteContext,
710 ) -> Option<String> {
711 if let ast::ItemKind::Impl(
721 let mut result = String::with_capacity(128);
723 result.push_str(&format_visibility(&item.vis));
724 result.push_str(format_defaultness(defaultness));
725 result.push_str(format_unsafety(unsafety));
726 result.push_str("impl");
728 let lo = context.codemap.span_after(item.span, "impl");
729 let hi = match *trait_ref {
730 Some(ref tr) => tr.path.span.lo(),
731 None => self_ty.span.lo(),
733 let shape = generics_shape_from_config(
735 Shape::indented(offset + last_line_width(&result), context.config),
738 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
740 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
742 let polarity_str = if polarity == ast::ImplPolarity::Negative {
748 if let Some(ref trait_ref) = *trait_ref {
749 let result_len = result.len();
750 if let Some(trait_ref_str) = rewrite_trait_ref(
759 result.push_str(&trait_ref_str);
762 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
763 result.push_str(&rewrite_trait_ref(
774 result.push_str(&generics_str);
777 // Try to put the self type in a single line.
779 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
780 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
781 // If there is no where clause adapt budget for type formatting to take space and curly
782 // brace into account.
783 match context.config.item_brace_style() {
784 BraceStyle::AlwaysNextLine => 0,
790 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
791 // 1 = space before the type.
792 let budget = context.budget(used_space + 1);
793 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
794 if !self_ty_str.contains('\n') {
795 if trait_ref.is_some() {
796 result.push_str(" for ");
800 result.push_str(&self_ty_str);
805 // Couldn't fit the self type on a single line, put it on a new line.
807 // Add indentation of one additional tab.
808 let new_line_offset = offset.block_indent(context.config);
809 result.push_str(&new_line_offset.to_string(context.config));
810 if trait_ref.is_some() {
811 result.push_str("for ");
813 let budget = context.budget(last_line_width(&result));
814 let type_offset = match context.config.where_style() {
815 Style::Legacy => new_line_offset + trait_ref_overhead,
816 Style::Rfc => new_line_offset,
818 result.push_str(&*self_ty
819 .rewrite(context, Shape::legacy(budget, type_offset))?);
826 fn rewrite_trait_ref(
827 context: &RewriteContext,
828 trait_ref: &ast::TraitRef,
834 ) -> Option<String> {
835 // 1 = space between generics and trait_ref
836 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
837 let shape = Shape::indented(offset + used_space, context.config);
838 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
839 if !(retry && trait_ref_str.contains('\n')) {
848 // We could not make enough space for trait_ref, so put it on new line.
850 let offset = offset.block_indent(context.config);
851 let shape = Shape::indented(offset, context.config);
852 let trait_ref_str = trait_ref.rewrite(context, shape)?;
856 &offset.to_string(context.config),
865 pub struct StructParts<'a> {
868 vis: &'a ast::Visibility,
869 def: &'a ast::VariantData,
870 generics: Option<&'a ast::Generics>,
874 impl<'a> StructParts<'a> {
875 fn format_header(&self) -> String {
876 format_header(self.prefix, self.ident, self.vis)
879 fn from_variant(variant: &'a ast::Variant) -> Self {
882 ident: variant.node.name,
883 vis: &ast::Visibility::Inherited,
884 def: &variant.node.data,
890 pub fn from_item(item: &'a ast::Item) -> Self {
891 let (prefix, def, generics) = match item.node {
892 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
893 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
901 generics: Some(generics),
908 context: &RewriteContext,
909 struct_parts: &StructParts,
911 one_line_width: Option<usize>,
912 ) -> Option<String> {
913 match *struct_parts.def {
914 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
915 ast::VariantData::Tuple(ref fields, _) => {
916 format_tuple_struct(context, struct_parts, fields, offset)
918 ast::VariantData::Struct(ref fields, _) => {
919 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
924 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
925 if let ast::ItemKind::Trait(_, unsafety, ref generics, ref type_param_bounds, ref trait_items) =
928 let mut result = String::with_capacity(128);
929 let header = format!(
931 format_visibility(&item.vis),
932 format_unsafety(unsafety),
936 result.push_str(&header);
938 let body_lo = context.codemap.span_after(item.span, "{");
940 let shape = Shape::indented(offset, context.config);
942 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
943 result.push_str(&generics_str);
945 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
946 if !type_param_bounds.is_empty() {
947 let ident_hi = context.codemap.span_after(item.span, &format!("{}", item.ident));
948 let bound_hi = type_param_bounds.last().unwrap().span().hi();
949 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
950 if contains_comment(&snippet) {
954 let trait_bound_str = rewrite_trait_bounds(
957 Shape::indented(offset, context.config),
959 // If the trait, generics, and trait bound cannot fit on the same line,
960 // put the trait bounds on an indented new line
961 if offset.width() + last_line_width(&result) + trait_bound_str.len()
962 > context.config.comment_width()
965 let trait_indent = offset.block_only().block_indent(context.config);
966 result.push_str(&trait_indent.to_string(context.config));
968 result.push_str(&trait_bound_str);
970 let has_body = !trait_items.is_empty();
972 let where_density = if (context.config.where_density() == Density::Compressed
973 && (!result.contains('\n') || context.config.fn_args_indent() == IndentStyle::Block))
974 || (context.config.fn_args_indent() == IndentStyle::Block && result.is_empty())
975 || (context.config.where_density() == Density::CompressedIfEmpty && !has_body
976 && !result.contains('\n'))
983 let where_budget = context.budget(last_line_width(&result));
984 let pos_before_where = if type_param_bounds.is_empty() {
985 generics.where_clause.span.lo()
987 type_param_bounds[type_param_bounds.len() - 1].span().hi()
989 let option = WhereClauseOption::snuggled(&generics_str);
990 let where_clause_str = rewrite_where_clause(
992 &generics.where_clause,
993 context.config.item_brace_style(),
994 Shape::legacy(where_budget, offset.block_only()),
1002 // If the where clause cannot fit on the same line,
1003 // put the where clause on a new line
1004 if !where_clause_str.contains('\n')
1005 && last_line_width(&result) + where_clause_str.len() + offset.width()
1006 > context.config.comment_width()
1009 let width = offset.block_indent + context.config.tab_spaces() - 1;
1010 let where_indent = Indent::new(0, width);
1011 result.push_str(&where_indent.to_string(context.config));
1013 result.push_str(&where_clause_str);
1015 if generics.where_clause.predicates.is_empty() {
1016 let item_snippet = context.snippet(item.span);
1017 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
1019 let comment_hi = body_lo - BytePos(1);
1020 let comment_lo = item.span.lo() + BytePos(lo as u32);
1021 if comment_lo < comment_hi {
1022 match recover_missing_comment_in_span(
1023 mk_sp(comment_lo, comment_hi),
1024 Shape::indented(offset, context.config),
1026 last_line_width(&result),
1028 Some(ref missing_comment) if !missing_comment.is_empty() => {
1029 result.push_str(missing_comment);
1037 match context.config.item_brace_style() {
1038 _ if last_line_contains_single_line_comment(&result) => {
1040 result.push_str(&offset.to_string(context.config));
1042 BraceStyle::AlwaysNextLine => {
1044 result.push_str(&offset.to_string(context.config));
1046 BraceStyle::PreferSameLine => result.push(' '),
1047 BraceStyle::SameLineWhere => if !where_clause_str.is_empty()
1048 && (!trait_items.is_empty() || result.contains('\n'))
1051 result.push_str(&offset.to_string(context.config));
1058 let snippet = context.snippet(item.span);
1059 let open_pos = snippet.find_uncommented("{")? + 1;
1061 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1062 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
1063 visitor.block_indent = offset.block_only().block_indent(context.config);
1064 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1066 for item in trait_items {
1067 visitor.visit_trait_item(item);
1070 visitor.format_missing(item.span.hi() - BytePos(1));
1072 let inner_indent_str = visitor.block_indent.to_string(context.config);
1073 let outer_indent_str = offset.block_only().to_string(context.config);
1076 result.push_str(&inner_indent_str);
1077 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1079 result.push_str(&outer_indent_str);
1080 } else if result.contains('\n') {
1091 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1092 let header_str = format_header(p.prefix, p.ident, p.vis);
1093 let generics_str = if let Some(generics) = p.generics {
1094 let shape = Shape::indented(offset, context.config).offset_left(header_str.len())?;
1095 rewrite_generics(context, generics, shape, generics.span)?
1099 Some(format!("{}{};", header_str, generics_str))
1102 pub fn format_struct_struct(
1103 context: &RewriteContext,
1104 struct_parts: &StructParts,
1105 fields: &[ast::StructField],
1107 one_line_width: Option<usize>,
1108 ) -> Option<String> {
1109 let mut result = String::with_capacity(1024);
1110 let span = struct_parts.span;
1112 let header_str = struct_parts.format_header();
1113 result.push_str(&header_str);
1115 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1116 let body_lo = context.codemap.span_after(span, "{");
1118 let generics_str = match struct_parts.generics {
1119 Some(g) => format_generics(
1122 context.config.item_brace_style(),
1125 mk_sp(header_hi, body_lo),
1126 last_line_width(&result),
1129 // 3 = ` {}`, 2 = ` {`.
1130 let overhead = if fields.is_empty() { 3 } else { 2 };
1131 if (context.config.item_brace_style() == BraceStyle::AlwaysNextLine
1132 && !fields.is_empty())
1133 || context.config.max_width() < overhead + result.len()
1135 format!("\n{}{{", offset.block_only().to_string(context.config))
1142 let overhead = if fields.is_empty() { 1 } else { 0 };
1143 let total_width = result.len() + generics_str.len() + overhead;
1144 if !generics_str.is_empty() && !generics_str.contains('\n')
1145 && total_width > context.config.max_width()
1148 result.push_str(&offset.to_string(context.config));
1149 result.push_str(generics_str.trim_left());
1151 result.push_str(&generics_str);
1154 if fields.is_empty() {
1155 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1156 if snippet.trim().is_empty() {
1158 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1160 result.push_str(snippet.trim_right());
1162 result.push_str(&offset.to_string(context.config));
1164 result.push_str(&snippet);
1167 return Some(result);
1171 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1172 let one_line_budget =
1173 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1175 let items_str = rewrite_with_alignment(
1178 Shape::indented(offset, context.config),
1179 mk_sp(body_lo, span.hi()),
1183 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget {
1184 Some(format!("{} {} }}", result, items_str))
1190 .block_indent(context.config)
1191 .to_string(context.config),
1193 offset.to_string(context.config)
1198 /// Returns a bytepos that is after that of `(` in `pub(..)`. If the given visibility does not
1199 /// contain `pub(..)`, then return the `lo` of the `defualt_span`. Yeah, but for what? Well, we need
1200 /// to bypass the `(` in the visibility when creating a span of tuple's body or fn's args.
1201 fn get_bytepos_after_visibility(
1202 context: &RewriteContext,
1203 vis: &ast::Visibility,
1208 ast::Visibility::Crate(s, CrateSugar::PubCrate) => context
1210 .span_after(mk_sp(s.hi(), default_span.hi()), terminator),
1211 ast::Visibility::Crate(s, CrateSugar::JustCrate) => s.hi(),
1212 ast::Visibility::Restricted { ref path, .. } => path.span.hi(),
1213 _ => default_span.lo(),
1217 fn format_tuple_struct(
1218 context: &RewriteContext,
1219 struct_parts: &StructParts,
1220 fields: &[ast::StructField],
1222 ) -> Option<String> {
1223 let mut result = String::with_capacity(1024);
1224 let span = struct_parts.span;
1226 let header_str = struct_parts.format_header();
1227 result.push_str(&header_str);
1229 let body_lo = if fields.is_empty() {
1230 let lo = get_bytepos_after_visibility(context, struct_parts.vis, span, ")");
1231 context.codemap.span_after(mk_sp(lo, span.hi()), "(")
1235 let body_hi = if fields.is_empty() {
1236 context.codemap.span_after(mk_sp(body_lo, span.hi()), ")")
1238 // This is a dirty hack to work around a missing `)` from the span of the last field.
1239 let last_arg_span = fields[fields.len() - 1].span;
1240 if context.snippet(last_arg_span).ends_with(')') {
1245 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1249 let where_clause_str = match struct_parts.generics {
1251 let budget = context.budget(last_line_width(&header_str));
1252 let shape = Shape::legacy(budget, offset);
1253 let g_span = mk_sp(span.lo(), body_lo);
1254 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1255 result.push_str(&generics_str);
1257 let where_budget = context.budget(last_line_width(&result));
1258 let option = WhereClauseOption::new(true, false);
1259 rewrite_where_clause(
1261 &generics.where_clause,
1262 context.config.item_brace_style(),
1263 Shape::legacy(where_budget, offset.block_only()),
1264 Density::Compressed,
1272 None => "".to_owned(),
1275 if fields.is_empty() {
1277 let used_width = last_line_used_width(&result, offset.width()) + 3;
1278 if used_width > context.config.max_width() {
1280 result.push_str(&offset
1281 .block_indent(context.config)
1282 .to_string(context.config))
1285 let snippet = context.snippet(mk_sp(
1287 context.codemap.span_before(mk_sp(body_lo, span.hi()), ")"),
1289 if snippet.is_empty() {
1291 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1292 result.push_str(snippet.trim_right());
1294 result.push_str(&offset.to_string(context.config));
1296 result.push_str(&snippet);
1300 let shape = Shape::indented(offset, context.config);
1301 let fields = &fields.iter().map(|field| field).collect::<Vec<_>>()[..];
1302 let one_line_width = context.config.fn_call_width();
1303 result = rewrite_call_inner(context, &result, fields, span, shape, one_line_width, false)?;
1306 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1307 && (result.contains('\n')
1308 || offset.block_indent + result.len() + where_clause_str.len() + 1
1309 > context.config.max_width())
1311 // We need to put the where clause on a new line, but we didn't
1312 // know that earlier, so the where clause will not be indented properly.
1314 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1315 .to_string(context.config));
1317 result.push_str(&where_clause_str);
1322 pub fn rewrite_type_alias(
1323 context: &RewriteContext,
1327 generics: &ast::Generics,
1328 vis: &ast::Visibility,
1330 ) -> Option<String> {
1331 let mut result = String::with_capacity(128);
1333 result.push_str(&format_visibility(vis));
1334 result.push_str("type ");
1335 result.push_str(&ident.to_string());
1338 let shape = Shape::indented(indent + result.len(), context.config).sub_width(2)?;
1339 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo());
1340 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1341 result.push_str(&generics_str);
1343 let where_budget = context.budget(last_line_width(&result));
1344 let option = WhereClauseOption::snuggled(&result);
1345 let where_clause_str = rewrite_where_clause(
1347 &generics.where_clause,
1348 context.config.item_brace_style(),
1349 Shape::legacy(where_budget, indent),
1350 context.config.where_density(),
1357 result.push_str(&where_clause_str);
1358 if where_clause_str.is_empty() {
1359 result.push_str(" = ");
1361 result.push_str(&format!("\n{}= ", indent.to_string(context.config)));
1364 let line_width = last_line_width(&result);
1365 // This checked_sub may fail as the extra space after '=' is not taken into account
1366 // In that case the budget is set to 0 which will make ty.rewrite retry on a new line
1367 let budget = context.budget(indent.width() + line_width + ";".len());
1368 let type_indent = indent + line_width;
1369 // Try to fit the type on the same line
1370 let ty_str = ty.rewrite(context, Shape::legacy(budget, type_indent))
1372 // The line was too short, try to put the type on the next line
1374 // Remove the space after '='
1376 let type_indent = indent.block_indent(context.config);
1378 result.push_str(&type_indent.to_string(context.config));
1379 let budget = context.budget(type_indent.width() + ";".len());
1380 ty.rewrite(context, Shape::legacy(budget, type_indent))
1382 result.push_str(&ty_str);
1383 result.push_str(";");
1387 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1389 if config.space_before_type_annotation() {
1394 if config.space_after_type_annotation_colon() {
1402 pub fn rewrite_struct_field_prefix(
1403 context: &RewriteContext,
1404 field: &ast::StructField,
1405 ) -> Option<String> {
1406 let vis = format_visibility(&field.vis);
1407 let type_annotation_spacing = type_annotation_spacing(context.config);
1408 Some(match field.ident {
1409 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1410 None => format!("{}", vis),
1414 impl Rewrite for ast::StructField {
1415 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1416 rewrite_struct_field(context, self, shape, 0)
1420 pub fn rewrite_struct_field(
1421 context: &RewriteContext,
1422 field: &ast::StructField,
1424 lhs_max_width: usize,
1425 ) -> Option<String> {
1426 if contains_skip(&field.attrs) {
1427 return Some(context.snippet(mk_sp(field.attrs[0].span.lo(), field.span.hi())));
1430 let type_annotation_spacing = type_annotation_spacing(context.config);
1431 let prefix = rewrite_struct_field_prefix(context, field)?;
1433 let attrs_str = field.attrs.rewrite(context, shape)?;
1434 let attrs_extendable = attrs_str.is_empty()
1435 || (context.config.attributes_on_same_line_as_field()
1436 && is_attributes_extendable(&attrs_str));
1437 let missing_span = if field.attrs.is_empty() {
1438 mk_sp(field.span.lo(), field.span.lo())
1440 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1442 let mut spacing = String::from(if field.ident.is_some() {
1443 type_annotation_spacing.1
1447 // Try to put everything on a single line.
1448 let attr_prefix = combine_strs_with_missing_comments(
1456 let overhead = last_line_width(&attr_prefix);
1457 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1458 for _ in 0..lhs_offset {
1461 // In this extreme case we will be missing a space betweeen an attribute and a field.
1462 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1465 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1466 if let Some(ref ty) = field.ty.rewrite(context, ty_shape) {
1467 if !ty.contains('\n') {
1468 return Some(attr_prefix + &spacing + ty);
1472 // We must use multiline.
1473 let new_shape = shape.with_max_width(context.config);
1474 let ty_rewritten = field.ty.rewrite(context, new_shape)?;
1476 let field_str = if prefix.is_empty() {
1478 } else if prefix.len() + first_line_width(&ty_rewritten) + 1 <= shape.width {
1479 prefix + " " + &ty_rewritten
1481 let type_offset = shape.indent.block_indent(context.config);
1482 let nested_shape = Shape::indented(type_offset, context.config);
1483 let nested_ty = field.ty.rewrite(context, nested_shape)?;
1484 prefix + "\n" + &type_offset.to_string(context.config) + &nested_ty
1486 combine_strs_with_missing_comments(
1496 pub struct StaticParts<'a> {
1498 vis: &'a ast::Visibility,
1501 mutability: ast::Mutability,
1502 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1506 impl<'a> StaticParts<'a> {
1507 pub fn from_item(item: &'a ast::Item) -> Self {
1508 let (prefix, ty, mutability, expr) = match item.node {
1509 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1510 ast::ItemKind::Const(ref ty, ref expr) => {
1511 ("const", ty, ast::Mutability::Immutable, expr)
1513 _ => unreachable!(),
1520 mutability: mutability,
1521 expr_opt: Some(expr),
1526 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1527 let (ty, expr_opt) = match ti.node {
1528 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1529 _ => unreachable!(),
1533 vis: &ast::Visibility::Inherited,
1536 mutability: ast::Mutability::Immutable,
1537 expr_opt: expr_opt.as_ref(),
1542 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1543 let (ty, expr) = match ii.node {
1544 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1545 _ => unreachable!(),
1552 mutability: ast::Mutability::Immutable,
1553 expr_opt: Some(expr),
1560 context: &RewriteContext,
1561 static_parts: &StaticParts,
1563 ) -> Option<String> {
1564 let colon = colon_spaces(
1565 context.config.space_before_type_annotation(),
1566 context.config.space_after_type_annotation_colon(),
1568 let prefix = format!(
1570 format_visibility(static_parts.vis),
1571 static_parts.prefix,
1572 format_mutability(static_parts.mutability),
1578 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1579 let ty_str = static_parts.ty.rewrite(context, ty_shape)?;
1581 if let Some(expr) = static_parts.expr_opt {
1582 let lhs = format!("{}{} =", prefix, ty_str);
1584 let remaining_width = context.budget(offset.block_indent + 1);
1589 Shape::legacy(remaining_width, offset.block_only()),
1591 recover_comment_removed(res, static_parts.span, context)
1593 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1595 Some(format!("{}{};", prefix, ty_str))
1599 pub fn rewrite_associated_type(
1601 ty_opt: Option<&ptr::P<ast::Ty>>,
1602 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1603 context: &RewriteContext,
1605 ) -> Option<String> {
1606 let prefix = format!("type {}", ident);
1608 let type_bounds_str = if let Some(ty_param_bounds) = ty_param_bounds_opt {
1610 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1611 let bounds: &[_] = ty_param_bounds;
1612 let bound_str = bounds
1614 .map(|ty_bound| ty_bound.rewrite(context, shape))
1615 .collect::<Option<Vec<_>>>()?;
1616 if !bounds.is_empty() {
1617 format!(": {}", join_bounds(context, shape, &bound_str))
1625 if let Some(ty) = ty_opt {
1626 let ty_str = ty.rewrite(
1629 context.budget(indent.block_indent + prefix.len() + 2),
1630 indent.block_only(),
1633 Some(format!("{}{} = {};", prefix, type_bounds_str, ty_str))
1635 Some(format!("{}{};", prefix, type_bounds_str))
1639 pub fn rewrite_associated_impl_type(
1641 defaultness: ast::Defaultness,
1642 ty_opt: Option<&ptr::P<ast::Ty>>,
1643 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1644 context: &RewriteContext,
1646 ) -> Option<String> {
1647 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1650 ast::Defaultness::Default => Some(format!("default {}", result)),
1655 impl Rewrite for ast::FunctionRetTy {
1656 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1658 ast::FunctionRetTy::Default(_) => Some(String::new()),
1659 ast::FunctionRetTy::Ty(ref ty) => {
1660 let inner_width = shape.width.checked_sub(3)?;
1661 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1662 .map(|r| format!("-> {}", r))
1668 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1670 ast::TyKind::Infer => {
1671 let original = context.snippet(ty.span);
1678 impl Rewrite for ast::Arg {
1679 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1680 if is_named_arg(self) {
1681 let mut result = self.pat
1682 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1684 if !is_empty_infer(context, &*self.ty) {
1685 if context.config.space_before_type_annotation() {
1686 result.push_str(" ");
1688 result.push_str(":");
1689 if context.config.space_after_type_annotation_colon() {
1690 result.push_str(" ");
1692 let overhead = last_line_width(&result);
1693 let max_width = shape.width.checked_sub(overhead)?;
1694 let ty_str = self.ty
1695 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1696 result.push_str(&ty_str);
1701 self.ty.rewrite(context, shape)
1706 fn rewrite_explicit_self(
1707 explicit_self: &ast::ExplicitSelf,
1709 context: &RewriteContext,
1710 ) -> Option<String> {
1711 match explicit_self.node {
1712 ast::SelfKind::Region(lt, m) => {
1713 let mut_str = format_mutability(m);
1716 let lifetime_str = l.rewrite(
1718 Shape::legacy(context.config.max_width(), Indent::empty()),
1720 Some(format!("&{} {}self", lifetime_str, mut_str))
1722 None => Some(format!("&{}self", mut_str)),
1725 ast::SelfKind::Explicit(ref ty, _) => {
1726 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1728 let mutability = explicit_self_mutability(&args[0]);
1729 let type_str = ty.rewrite(
1731 Shape::legacy(context.config.max_width(), Indent::empty()),
1736 format_mutability(mutability),
1740 ast::SelfKind::Value(_) => {
1741 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1743 let mutability = explicit_self_mutability(&args[0]);
1745 Some(format!("{}self", format_mutability(mutability)))
1750 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1751 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1752 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1753 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1760 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1761 if is_named_arg(arg) {
1768 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1770 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1771 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1772 _ => arg.ty.span.hi(),
1776 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1777 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1778 ident.node != symbol::keywords::Invalid.ident()
1784 // Return type is (result, force_new_line_for_brace)
1786 context: &RewriteContext,
1791 newline_brace: bool,
1793 ) -> Option<(String, bool)> {
1794 let mut force_new_line_for_brace = false;
1796 let where_clause = &fn_sig.generics.where_clause;
1798 let mut result = String::with_capacity(1024);
1799 result.push_str(&fn_sig.to_str(context));
1802 result.push_str("fn ");
1803 result.push_str(&ident.to_string());
1806 let overhead = if has_body && !newline_brace {
1813 let used_width = last_line_used_width(&result, indent.width());
1814 let one_line_budget = context.budget(used_width + overhead);
1816 width: one_line_budget,
1820 let fd = fn_sig.decl;
1821 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1822 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1823 result.push_str(&generics_str);
1825 let snuggle_angle_bracket = generics_str
1828 .map_or(false, |l| l.trim_left().len() == 1);
1830 // Note that the width and indent don't really matter, we'll re-layout the
1831 // return type later anyway.
1832 let ret_str = fd.output
1833 .rewrite(context, Shape::indented(indent, context.config))?;
1835 let multi_line_ret_str = ret_str.contains('\n');
1836 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1839 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1850 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1856 // Check if vertical layout was forced.
1857 if one_line_budget == 0 {
1858 if snuggle_angle_bracket {
1860 } else if context.config.fn_args_paren_newline() {
1862 result.push_str(&arg_indent.to_string(context.config));
1863 if context.config.fn_args_indent() == IndentStyle::Visual {
1864 arg_indent = arg_indent + 1; // extra space for `(`
1868 result.push_str("(");
1869 if context.config.fn_args_indent() == IndentStyle::Visual {
1871 result.push_str(&arg_indent.to_string(context.config));
1877 if context.config.spaces_within_parens() && !fd.inputs.is_empty() && result.ends_with('(') {
1881 // Skip `pub(crate)`.
1882 let lo_after_visibility = get_bytepos_after_visibility(context, &fn_sig.visibility, span, ")");
1883 // A conservative estimation, to goal is to be over all parens in generics
1884 let args_start = fn_sig
1888 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1889 let args_end = if fd.inputs.is_empty() {
1892 .span_after(mk_sp(args_start, span.hi()), ")")
1894 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1895 context.codemap.span_after(last_span, ")")
1897 let args_span = mk_sp(
1900 .span_after(mk_sp(args_start, span.hi()), "("),
1903 let arg_str = rewrite_args(
1906 fd.get_self().as_ref(),
1913 generics_str.contains('\n'),
1916 let put_args_in_block = match context.config.fn_args_indent() {
1917 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1919 } && !fd.inputs.is_empty();
1921 let mut args_last_line_contains_comment = false;
1922 if put_args_in_block {
1923 arg_indent = indent.block_indent(context.config);
1925 result.push_str(&arg_indent.to_string(context.config));
1926 result.push_str(&arg_str);
1928 result.push_str(&indent.to_string(context.config));
1931 result.push_str(&arg_str);
1932 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1933 // Put the closing brace on the next line if it overflows the max width.
1935 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1938 if context.config.spaces_within_parens() && !fd.inputs.is_empty() {
1941 // If the last line of args contains comment, we cannot put the closing paren
1942 // on the same line.
1946 .map_or(false, |last_line| last_line.contains("//"))
1948 args_last_line_contains_comment = true;
1950 result.push_str(&arg_indent.to_string(context.config));
1956 if let ast::FunctionRetTy::Ty(..) = fd.output {
1957 let ret_should_indent = match context.config.fn_args_indent() {
1958 // If our args are block layout then we surely must have space.
1959 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1960 _ if args_last_line_contains_comment => false,
1961 _ if result.contains('\n') || multi_line_ret_str => true,
1963 // If the return type would push over the max width, then put the return type on
1964 // a new line. With the +1 for the signature length an additional space between
1965 // the closing parenthesis of the argument and the arrow '->' is considered.
1966 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1968 // If there is no where clause, take into account the space after the return type
1970 if where_clause.predicates.is_empty() {
1974 sig_length > context.config.max_width()
1977 let ret_indent = if ret_should_indent {
1978 let indent = match context.config.fn_return_indent() {
1979 ReturnIndent::WithWhereClause => indent + 4,
1980 // Aligning with non-existent args looks silly.
1981 _ if arg_str.is_empty() => {
1982 force_new_line_for_brace = true;
1985 // FIXME: we might want to check that using the arg indent
1986 // doesn't blow our budget, and if it does, then fallback to
1987 // the where clause indent.
1992 result.push_str(&indent.to_string(context.config));
1996 Indent::new(indent.block_indent, last_line_width(&result))
1999 if multi_line_ret_str || ret_should_indent {
2000 // Now that we know the proper indent and width, we need to
2001 // re-layout the return type.
2002 let ret_str = fd.output
2003 .rewrite(context, Shape::indented(ret_indent, context.config))?;
2004 result.push_str(&ret_str);
2006 result.push_str(&ret_str);
2009 // Comment between return type and the end of the decl.
2010 let snippet_lo = fd.output.span().hi();
2011 if where_clause.predicates.is_empty() {
2012 let snippet_hi = span.hi();
2013 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2014 // Try to preserve the layout of the original snippet.
2015 let original_starts_with_newline = snippet
2017 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2018 let original_ends_with_newline = snippet
2019 .rfind(|c| c != ' ')
2020 .map_or(false, |i| snippet[i..].ends_with('\n'));
2021 let snippet = snippet.trim();
2022 if !snippet.is_empty() {
2023 result.push(if original_starts_with_newline {
2028 result.push_str(snippet);
2029 if original_ends_with_newline {
2030 force_new_line_for_brace = true;
2036 let should_compress_where = match context.config.where_density() {
2037 Density::Compressed => !result.contains('\n'),
2038 Density::CompressedIfEmpty => !has_body && !result.contains('\n'),
2042 let pos_before_where = match fd.output {
2043 ast::FunctionRetTy::Default(..) => args_span.hi(),
2044 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2047 let is_args_multi_lined = arg_str.contains('\n');
2049 if where_clause.predicates.len() == 1 && should_compress_where {
2050 let budget = context.budget(last_line_used_width(&result, indent.width()));
2051 if let Some(where_clause_str) = rewrite_where_clause(
2054 context.config.fn_brace_style(),
2055 Shape::legacy(budget, indent),
2056 Density::Compressed,
2060 WhereClauseOption::compressed(),
2061 is_args_multi_lined,
2063 result.push_str(&where_clause_str);
2064 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2065 return Some((result, force_new_line_for_brace));
2069 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2070 let where_clause_str = rewrite_where_clause(
2073 context.config.fn_brace_style(),
2074 Shape::indented(indent, context.config),
2080 is_args_multi_lined,
2082 // If there are neither where clause nor return type, we may be missing comments between
2084 if where_clause_str.is_empty() {
2085 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2086 match recover_missing_comment_in_span(
2087 mk_sp(args_span.hi(), ret_span.hi()),
2090 last_line_width(&result),
2092 Some(ref missing_comment) if !missing_comment.is_empty() => {
2093 result.push_str(missing_comment);
2094 force_new_line_for_brace = true;
2101 result.push_str(&where_clause_str);
2103 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2104 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2105 Some((result, force_new_line_for_brace))
2108 #[derive(Copy, Clone)]
2109 struct WhereClauseOption {
2110 suppress_comma: bool, // Force no trailing comma
2111 snuggle: bool, // Do not insert newline before `where`
2112 compress_where: bool, // Try single line where clause instead of vertical layout
2115 impl WhereClauseOption {
2116 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2118 suppress_comma: suppress_comma,
2120 compress_where: false,
2124 pub fn compressed() -> WhereClauseOption {
2126 suppress_comma: true,
2128 compress_where: true,
2132 pub fn snuggled(current: &str) -> WhereClauseOption {
2134 suppress_comma: false,
2135 snuggle: trimmed_last_line_width(current) == 1,
2136 compress_where: false,
2142 context: &RewriteContext,
2144 explicit_self: Option<&ast::ExplicitSelf>,
2145 one_line_budget: usize,
2146 multi_line_budget: usize,
2151 generics_str_contains_newline: bool,
2152 ) -> Option<String> {
2153 let mut arg_item_strs = args.iter()
2155 arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent))
2157 .collect::<Option<Vec<_>>>()?;
2159 // Account for sugary self.
2160 // FIXME: the comment for the self argument is dropped. This is blocked
2161 // on rust issue #27522.
2162 let min_args = explicit_self
2163 .and_then(|explicit_self| {
2164 rewrite_explicit_self(explicit_self, args, context)
2166 .map_or(1, |self_str| {
2167 arg_item_strs[0] = self_str;
2171 // Comments between args.
2172 let mut arg_items = Vec::new();
2174 arg_items.push(ListItem::from_str(""));
2177 // FIXME(#21): if there are no args, there might still be a comment, but
2178 // without spans for the comment or parens, there is no chance of
2179 // getting it right. You also don't get to put a comment on self, unless
2181 if args.len() >= min_args || variadic {
2182 let comment_span_start = if min_args == 2 {
2183 let second_arg_start = if arg_has_pattern(&args[1]) {
2184 args[1].pat.span.lo()
2186 args[1].ty.span.lo()
2188 let reduced_span = mk_sp(span.lo(), second_arg_start);
2190 context.codemap.span_after_last(reduced_span, ",")
2195 enum ArgumentKind<'a> {
2196 Regular(&'a ast::Arg),
2200 let variadic_arg = if variadic {
2201 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2202 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2203 Some(ArgumentKind::Variadic(variadic_start))
2208 let more_items = itemize_list(
2210 args[min_args - 1..]
2212 .map(ArgumentKind::Regular)
2213 .chain(variadic_arg),
2216 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2217 ArgumentKind::Variadic(start) => start,
2220 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2221 ArgumentKind::Variadic(start) => start + BytePos(3),
2224 ArgumentKind::Regular(..) => None,
2225 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2232 arg_items.extend(more_items);
2235 let fits_in_one_line = !generics_str_contains_newline
2236 && (arg_items.is_empty()
2237 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2239 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2240 item.item = Some(arg);
2243 let last_line_ends_with_comment = arg_items
2246 .and_then(|item| item.post_comment.as_ref())
2247 .map_or(false, |s| s.trim().starts_with("//"));
2249 let (indent, trailing_comma) = match context.config.fn_args_indent() {
2250 IndentStyle::Block if fits_in_one_line => {
2251 (indent.block_indent(context.config), SeparatorTactic::Never)
2253 IndentStyle::Block => (
2254 indent.block_indent(context.config),
2255 context.config.trailing_comma(),
2257 IndentStyle::Visual if last_line_ends_with_comment => {
2258 (arg_indent, context.config.trailing_comma())
2260 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2263 let tactic = definitive_tactic(
2265 context.config.fn_args_density().to_list_tactic(),
2269 let budget = match tactic {
2270 DefinitiveListTactic::Horizontal => one_line_budget,
2271 _ => multi_line_budget,
2274 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2276 let fmt = ListFormatting {
2279 trailing_separator: if variadic {
2280 SeparatorTactic::Never
2284 separator_place: SeparatorPlace::Back,
2285 shape: Shape::legacy(budget, indent),
2286 ends_with_newline: tactic.ends_with_newline(context.config.fn_args_indent()),
2287 preserve_newline: true,
2288 config: context.config,
2291 write_list(&arg_items, &fmt)
2294 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2295 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2296 ident.node != symbol::keywords::Invalid.ident()
2302 fn compute_budgets_for_args(
2303 context: &RewriteContext,
2307 newline_brace: bool,
2309 force_vertical_layout: bool,
2310 ) -> Option<((usize, usize, Indent))> {
2312 "compute_budgets_for_args {} {:?}, {}, {}",
2318 // Try keeping everything on the same line.
2319 if !result.contains('\n') && !force_vertical_layout {
2320 // 2 = `()`, 3 = `() `, space is before ret_string.
2321 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2322 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2332 let one_line_budget = context.budget(used_space);
2334 if one_line_budget > 0 {
2336 let (indent, multi_line_budget) = match context.config.fn_args_indent() {
2337 IndentStyle::Block => {
2338 let indent = indent.block_indent(context.config);
2339 (indent, context.budget(indent.width() + 1))
2341 IndentStyle::Visual => {
2342 let indent = indent + result.len() + 1;
2343 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2344 (indent, context.budget(multi_line_overhead))
2348 return Some((one_line_budget, multi_line_budget, indent));
2352 // Didn't work. we must force vertical layout and put args on a newline.
2353 let new_indent = indent.block_indent(context.config);
2354 let used_space = match context.config.fn_args_indent() {
2356 IndentStyle::Block => new_indent.width() + 1,
2357 // Account for `)` and possibly ` {`.
2358 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2360 Some((0, context.budget(used_space), new_indent))
2363 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause, has_body: bool) -> bool {
2364 let predicate_count = where_clause.predicates.len();
2366 if config.where_single_line() && predicate_count == 1 {
2369 match (config.fn_brace_style(), config.where_density()) {
2370 (BraceStyle::AlwaysNextLine, _) => true,
2371 (_, Density::Compressed) if predicate_count == 1 => false,
2372 (_, Density::CompressedIfEmpty) if predicate_count == 1 && !has_body => false,
2373 (BraceStyle::SameLineWhere, _) if predicate_count > 0 => true,
2378 fn rewrite_generics(
2379 context: &RewriteContext,
2380 generics: &ast::Generics,
2383 ) -> Option<String> {
2384 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2385 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2386 rewrite_generics_inner(context, generics, g_shape, one_line_width, span).or_else(|| {
2387 rewrite_generics_inner(context, generics, g_shape, 0, span)
2391 fn rewrite_generics_inner(
2392 context: &RewriteContext,
2393 generics: &ast::Generics,
2395 one_line_width: usize,
2397 ) -> Option<String> {
2398 // FIXME: convert bounds to where clauses where they get too big or if
2399 // there is a where clause at all.
2402 enum GenericsArg<'a> {
2403 Lifetime(&'a ast::LifetimeDef),
2404 TyParam(&'a ast::TyParam),
2406 impl<'a> Rewrite for GenericsArg<'a> {
2407 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2409 GenericsArg::Lifetime(lifetime) => lifetime.rewrite(context, shape),
2410 GenericsArg::TyParam(ty) => ty.rewrite(context, shape),
2414 impl<'a> Spanned for GenericsArg<'a> {
2415 fn span(&self) -> Span {
2417 GenericsArg::Lifetime(lifetime) => lifetime.span(),
2418 GenericsArg::TyParam(ty) => ty.span(),
2423 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2424 return Some(String::new());
2427 let generics_args = generics
2430 .map(|lt| GenericsArg::Lifetime(lt))
2431 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2432 let items = itemize_list(
2436 |arg| arg.span().lo(),
2437 |arg| arg.span().hi(),
2438 |arg| arg.rewrite(context, shape),
2439 context.codemap.span_after(span, "<"),
2443 format_generics_item_list(context, items, shape, one_line_width)
2446 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2447 match config.generics_indent() {
2448 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2449 IndentStyle::Block => {
2453 .block_indent(config.tab_spaces())
2454 .with_max_width(config)
2460 pub fn format_generics_item_list<I>(
2461 context: &RewriteContext,
2464 one_line_budget: usize,
2467 I: Iterator<Item = ListItem>,
2469 let item_vec = items.collect::<Vec<_>>();
2471 let tactic = definitive_tactic(
2473 ListTactic::HorizontalVertical,
2477 let fmt = ListFormatting {
2480 trailing_separator: if context.config.generics_indent() == IndentStyle::Visual {
2481 SeparatorTactic::Never
2483 context.config.trailing_comma()
2485 separator_place: SeparatorPlace::Back,
2487 ends_with_newline: tactic.ends_with_newline(context.config.generics_indent()),
2488 preserve_newline: true,
2489 config: context.config,
2492 let list_str = write_list(&item_vec, &fmt)?;
2494 Some(wrap_generics_with_angle_brackets(
2501 pub fn wrap_generics_with_angle_brackets(
2502 context: &RewriteContext,
2504 list_offset: Indent,
2506 if context.config.generics_indent() == IndentStyle::Block
2507 && (list_str.contains('\n') || list_str.ends_with(','))
2511 list_offset.to_string(context.config),
2514 .block_unindent(context.config)
2515 .to_string(context.config)
2517 } else if context.config.spaces_within_angle_brackets() {
2518 format!("< {} >", list_str)
2520 format!("<{}>", list_str)
2524 fn rewrite_trait_bounds(
2525 context: &RewriteContext,
2526 type_param_bounds: &ast::TyParamBounds,
2528 ) -> Option<String> {
2529 let bounds: &[_] = type_param_bounds;
2531 if bounds.is_empty() {
2532 return Some(String::new());
2534 let bound_str = bounds
2536 .map(|ty_bound| ty_bound.rewrite(context, shape))
2537 .collect::<Option<Vec<_>>>()?;
2538 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2541 fn rewrite_where_clause_rfc_style(
2542 context: &RewriteContext,
2543 where_clause: &ast::WhereClause,
2546 span_end: Option<BytePos>,
2547 span_end_before_where: BytePos,
2548 where_clause_option: WhereClauseOption,
2549 is_args_multi_line: bool,
2550 ) -> Option<String> {
2551 let block_shape = shape.block().with_max_width(context.config);
2553 let (span_before, span_after) =
2554 missing_span_before_after_where(span_end_before_where, where_clause);
2555 let (comment_before, comment_after) =
2556 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2558 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2561 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2564 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2566 let clause_shape = clause_shape.sub_width(1)?;
2567 // each clause on one line, trailing comma (except if suppress_comma)
2568 let span_start = where_clause.predicates[0].span().lo();
2569 // If we don't have the start of the next span, then use the end of the
2570 // predicates, but that means we miss comments.
2571 let len = where_clause.predicates.len();
2572 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2573 let span_end = span_end.unwrap_or(end_of_preds);
2574 let items = itemize_list(
2576 where_clause.predicates.iter(),
2578 |pred| pred.span().lo(),
2579 |pred| pred.span().hi(),
2580 |pred| pred.rewrite(context, clause_shape),
2585 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2586 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2587 SeparatorTactic::Never
2589 context.config.trailing_comma()
2592 // shape should be vertical only and only if we have `where_single_line` option enabled
2593 // and the number of items of the where clause is equal to 1
2594 let shape_tactic = if where_single_line {
2595 DefinitiveListTactic::Horizontal
2597 DefinitiveListTactic::Vertical
2600 let fmt = ListFormatting {
2601 tactic: shape_tactic,
2603 trailing_separator: comma_tactic,
2604 separator_place: SeparatorPlace::Back,
2605 shape: clause_shape,
2606 ends_with_newline: true,
2607 preserve_newline: true,
2608 config: context.config,
2610 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2612 let comment_separator = |comment: &str, shape: Shape| if comment.is_empty() {
2615 format!("\n{}", shape.indent.to_string(context.config))
2617 let newline_before_where = comment_separator(&comment_before, shape);
2618 let newline_after_where = comment_separator(&comment_after, clause_shape);
2621 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2622 && comment_after.is_empty() && !preds_str.contains('\n')
2623 && 6 + preds_str.len() <= shape.width || where_single_line
2627 format!("\n{}", clause_shape.indent.to_string(context.config))
2630 "{}{}{}where{}{}{}{}",
2633 newline_before_where,
2634 newline_after_where,
2641 fn rewrite_where_clause(
2642 context: &RewriteContext,
2643 where_clause: &ast::WhereClause,
2644 brace_style: BraceStyle,
2648 span_end: Option<BytePos>,
2649 span_end_before_where: BytePos,
2650 where_clause_option: WhereClauseOption,
2651 is_args_multi_line: bool,
2652 ) -> Option<String> {
2653 if where_clause.predicates.is_empty() {
2654 return Some(String::new());
2657 if context.config.where_style() == Style::Rfc {
2658 return rewrite_where_clause_rfc_style(
2664 span_end_before_where,
2665 where_clause_option,
2670 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2672 let offset = match context.config.where_pred_indent() {
2673 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2674 // 6 = "where ".len()
2675 IndentStyle::Visual => shape.indent + extra_indent + 6,
2677 // FIXME: if where_pred_indent != Visual, then the budgets below might
2678 // be out by a char or two.
2680 let budget = context.config.max_width() - offset.width();
2681 let span_start = where_clause.predicates[0].span().lo();
2682 // If we don't have the start of the next span, then use the end of the
2683 // predicates, but that means we miss comments.
2684 let len = where_clause.predicates.len();
2685 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2686 let span_end = span_end.unwrap_or(end_of_preds);
2687 let items = itemize_list(
2689 where_clause.predicates.iter(),
2691 |pred| pred.span().lo(),
2692 |pred| pred.span().hi(),
2693 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2698 let item_vec = items.collect::<Vec<_>>();
2699 // FIXME: we don't need to collect here if the where_layout isn't
2700 // HorizontalVertical.
2701 let tactic = definitive_tactic(
2703 context.config.where_layout(),
2708 let mut comma_tactic = context.config.trailing_comma();
2709 // Kind of a hack because we don't usually have trailing commas in where clauses.
2710 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2711 comma_tactic = SeparatorTactic::Never;
2714 let fmt = ListFormatting {
2717 trailing_separator: comma_tactic,
2718 separator_place: SeparatorPlace::Back,
2719 shape: Shape::legacy(budget, offset),
2720 ends_with_newline: tactic.ends_with_newline(context.config.where_pred_indent()),
2721 preserve_newline: true,
2722 config: context.config,
2724 let preds_str = write_list(&item_vec, &fmt)?;
2726 let end_length = if terminator == "{" {
2727 // If the brace is on the next line we don't need to count it otherwise it needs two
2730 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2731 BraceStyle::PreferSameLine => 2,
2733 } else if terminator == "=" {
2738 if density == Density::Tall || preds_str.contains('\n')
2739 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2743 (shape.indent + extra_indent).to_string(context.config),
2747 Some(format!(" where {}", preds_str))
2751 fn missing_span_before_after_where(
2752 before_item_span_end: BytePos,
2753 where_clause: &ast::WhereClause,
2755 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2757 let pos_after_where = where_clause.span.lo() + BytePos(5);
2758 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2759 (missing_span_before, missing_span_after)
2762 fn rewrite_comments_before_after_where(
2763 context: &RewriteContext,
2764 span_before_where: Span,
2765 span_after_where: Span,
2767 ) -> Option<(String, String)> {
2768 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2769 let after_comment = rewrite_missing_comment(
2771 shape.block_indent(context.config.tab_spaces()),
2774 Some((before_comment, after_comment))
2777 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2778 format!("{}{}{}", format_visibility(vis), item_name, ident)
2782 context: &RewriteContext,
2783 generics: &ast::Generics,
2784 brace_style: BraceStyle,
2785 force_same_line_brace: bool,
2789 ) -> Option<String> {
2790 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2791 let mut result = rewrite_generics(context, generics, shape, span)?;
2793 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2794 let budget = context.budget(last_line_used_width(&result, offset.width()));
2795 let option = WhereClauseOption::snuggled(&result);
2796 // If the generics are not parameterized then generics.span.hi() == 0,
2797 // so we use span.lo(), which is the position after `struct Foo`.
2798 let span_end_before_where = if generics.is_parameterized() {
2803 let where_clause_str = rewrite_where_clause(
2805 &generics.where_clause,
2807 Shape::legacy(budget, offset.block_only()),
2811 span_end_before_where,
2815 result.push_str(&where_clause_str);
2816 force_same_line_brace || brace_style == BraceStyle::PreferSameLine
2817 || (generics.where_clause.predicates.is_empty()
2818 && trimmed_last_line_width(&result) == 1)
2820 force_same_line_brace || trimmed_last_line_width(&result) == 1
2821 || brace_style != BraceStyle::AlwaysNextLine
2823 let total_used_width = last_line_used_width(&result, used_width);
2824 let remaining_budget = context.budget(total_used_width);
2825 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2826 // and hence we take the closer into account as well for one line budget.
2827 // We assume that the closer has the same length as the opener.
2828 let overhead = if force_same_line_brace {
2835 let forbid_same_line_brace = overhead > remaining_budget;
2836 if !forbid_same_line_brace && same_line_brace {
2840 result.push_str(&offset.block_only().to_string(context.config));
2847 impl Rewrite for ast::ForeignItem {
2848 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2849 let attrs_str = self.attrs.rewrite(context, shape)?;
2850 // Drop semicolon or it will be interpreted as comment.
2851 // FIXME: this may be a faulty span from libsyntax.
2852 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2854 let item_str = match self.node {
2855 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2860 &FnSig::new(fn_decl, generics, self.vis.clone()),
2864 ).map(|(s, _)| format!("{};", s))
2866 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2867 // FIXME(#21): we're dropping potential comments in between the
2868 // function keywords here.
2869 let vis = format_visibility(&self.vis);
2870 let mut_str = if is_mutable { "mut " } else { "" };
2871 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2873 let shape = shape.sub_width(1)?;
2874 ty.rewrite(context, shape).map(|ty_str| {
2875 // 1 = space between prefix and type.
2876 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2879 let nested_indent = shape.indent.block_indent(context.config);
2880 format!("\n{}", nested_indent.to_string(context.config))
2882 format!("{}{}{};", prefix, sep, ty_str)
2885 ast::ForeignItemKind::Ty => {
2886 let vis = format_visibility(&self.vis);
2887 Some(format!("{}type {};", vis, self.ident))
2891 let missing_span = if self.attrs.is_empty() {
2892 mk_sp(self.span.lo(), self.span.lo())
2894 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2896 combine_strs_with_missing_comments(