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::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(method_sig: &'a ast::MethodSig) -> FnSig {
189 unsafety: method_sig.unsafety,
190 constness: method_sig.constness.node,
191 defaultness: ast::Defaultness::Final,
193 decl: &*method_sig.decl,
194 generics: &method_sig.generics,
195 visibility: ast::Visibility::Inherited,
200 fn_kind: &'a visit::FnKind,
201 decl: &'a ast::FnDecl,
202 defualtness: ast::Defaultness,
205 visit::FnKind::ItemFn(_, generics, unsafety, constness, abi, visibility, _) => FnSig {
209 constness: constness.node,
210 defaultness: defualtness,
212 visibility: visibility.clone(),
214 visit::FnKind::Method(_, ref method_sig, vis, _) => {
215 let mut fn_sig = FnSig::from_method_sig(method_sig);
216 fn_sig.defaultness = defualtness;
217 if let Some(vis) = vis {
218 fn_sig.visibility = vis.clone();
226 fn to_str(&self, context: &RewriteContext) -> String {
227 let mut result = String::with_capacity(128);
228 // Vis defaultness constness unsafety abi.
229 result.push_str(&*format_visibility(&self.visibility));
230 result.push_str(format_defaultness(self.defaultness));
231 result.push_str(format_constness(self.constness));
232 result.push_str(format_unsafety(self.unsafety));
233 result.push_str(&format_abi(
235 context.config.force_explicit_abi(),
242 impl<'a> FmtVisitor<'a> {
243 fn format_item(&mut self, item: Item) {
244 self.buffer.push_str(&item.abi);
246 let snippet = self.snippet(item.span);
247 let brace_pos = snippet.find_uncommented("{").unwrap();
249 self.buffer.push_str("{");
250 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
251 // FIXME: this skips comments between the extern keyword and the opening
253 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
254 self.block_indent = self.block_indent.block_indent(self.config);
256 if item.body.is_empty() {
257 self.format_missing_no_indent(item.span.hi() - BytePos(1));
258 self.block_indent = self.block_indent.block_unindent(self.config);
261 .push_str(&self.block_indent.to_string(self.config));
263 for item in &item.body {
264 self.format_body_element(item);
267 self.block_indent = self.block_indent.block_unindent(self.config);
268 self.format_missing_with_indent(item.span.hi() - BytePos(1));
272 self.buffer.push_str("}");
273 self.last_pos = item.span.hi();
276 fn format_body_element(&mut self, element: &BodyElement) {
278 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
282 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
283 let item = Item::from_foreign_mod(fm, span, self.config);
284 self.format_item(item);
288 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
289 let rewrite = item.rewrite(&self.get_context(), self.shape());
290 self.push_rewrite(item.span(), rewrite);
291 self.last_pos = item.span.hi();
301 ) -> Option<String> {
302 let context = self.get_context();
305 !is_empty_block(block, self.codemap) || !context.config.fn_empty_single_line();
306 let mut newline_brace =
307 newline_for_brace(self.config, &fn_sig.generics.where_clause, has_body);
309 let (mut result, force_newline_brace) =
310 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
312 if self.config.fn_brace_style() == BraceStyle::AlwaysNextLine || force_newline_brace {
313 newline_brace = true;
314 } else if last_line_width(&result) + 2 > self.shape().width {
316 newline_brace = true;
317 } else if !result.contains('\n') {
318 newline_brace = false;
321 // Prepare for the function body by possibly adding a newline and
323 // FIXME we'll miss anything between the end of the signature and the
324 // start of the body, but we need more spans from the compiler to solve
328 result.push_str(&indent.to_string(self.config));
333 self.single_line_fn(&result, block).or_else(|| Some(result))
336 pub fn rewrite_required_fn(
340 sig: &ast::MethodSig,
342 ) -> Option<String> {
343 // Drop semicolon or it will be interpreted as comment.
344 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
345 let context = self.get_context();
347 let (mut result, _) = rewrite_fn_base(
351 &FnSig::from_method_sig(sig),
357 // Re-attach semicolon
363 fn single_line_fn(&self, fn_str: &str, block: &ast::Block) -> Option<String> {
364 if fn_str.contains('\n') {
368 let codemap = self.get_context().codemap;
370 if self.config.fn_empty_single_line() && is_empty_block(block, codemap)
371 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
373 return Some(format!("{}{{}}", fn_str));
376 if self.config.fn_single_line() && is_simple_block_stmt(block, codemap) {
378 if let Some(stmt) = block.stmts.first() {
379 match stmt_expr(stmt) {
381 let suffix = if semicolon_for_expr(&self.get_context(), e) {
387 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
389 .or_else(|| Some(self.snippet(e.span)))
391 None => stmt.rewrite(&self.get_context(), self.shape()),
398 if let Some(res) = rewrite {
399 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
400 if !res.contains('\n') && width <= self.config.max_width() {
401 return Some(format!("{}{{ {} }}", fn_str, res));
412 vis: &ast::Visibility,
413 enum_def: &ast::EnumDef,
414 generics: &ast::Generics,
417 let enum_header = format_header("enum ", ident, vis);
418 self.buffer.push_str(&enum_header);
420 let enum_snippet = self.snippet(span);
421 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
422 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
423 let generics_str = format_generics(
428 self.config.item_brace_style(),
429 enum_def.variants.is_empty(),
431 mk_sp(span.lo(), body_start),
432 last_line_width(&enum_header),
434 self.buffer.push_str(&generics_str);
436 self.last_pos = body_start;
438 self.block_indent = self.block_indent.block_indent(self.config);
439 let variant_list = self.format_variant_list(enum_def, body_start, span.hi() - BytePos(1));
441 Some(ref body_str) => self.buffer.push_str(body_str),
442 None => if contains_comment(&enum_snippet[brace_pos..]) {
443 self.format_missing_no_indent(span.hi() - BytePos(1))
446 self.block_indent = self.block_indent.block_unindent(self.config);
448 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
450 .push_str(&self.block_indent.to_string(self.config));
452 self.buffer.push_str("}");
453 self.last_pos = span.hi();
456 // Format the body of an enum definition
457 fn format_variant_list(
459 enum_def: &ast::EnumDef,
462 ) -> Option<String> {
463 if enum_def.variants.is_empty() {
466 let mut result = String::with_capacity(1024);
468 let indentation = self.block_indent.to_string(self.config);
469 result.push_str(&indentation);
471 let items = itemize_list(
473 enum_def.variants.iter(),
475 |f| if !f.node.attrs.is_empty() {
476 f.node.attrs[0].span.lo()
481 |f| self.format_variant(f),
487 let shape = self.shape().sub_width(2).unwrap();
488 let fmt = ListFormatting {
489 tactic: DefinitiveListTactic::Vertical,
491 trailing_separator: self.config.trailing_comma(),
492 separator_place: SeparatorPlace::Back,
494 ends_with_newline: true,
495 preserve_newline: true,
499 let list = write_list(&items.collect::<Vec<_>>(), &fmt)?;
500 result.push_str(&list);
505 // Variant of an enum.
506 fn format_variant(&self, field: &ast::Variant) -> Option<String> {
507 if contains_skip(&field.node.attrs) {
508 let lo = field.node.attrs[0].span.lo();
509 let span = mk_sp(lo, field.span.hi());
510 return Some(self.snippet(span));
513 let context = self.get_context();
514 let indent = self.block_indent;
515 let shape = self.shape();
516 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
521 .map_or(field.span.lo(), |attr| attr.span.hi());
522 let span = mk_sp(lo, field.span.lo());
524 let variant_body = match field.node.data {
525 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => {
526 // FIXME: Should limit the width, as we have a trailing comma
531 &ast::Visibility::Inherited,
536 Some(self.config.struct_variant_width()),
539 ast::VariantData::Unit(..) => if let Some(ref expr) = field.node.disr_expr {
540 let lhs = format!("{} =", field.node.name);
542 rewrite_assign_rhs(&context, lhs, expr, shape.sub_width(1)?)?
544 String::from(field.node.name.to_string())
548 let attrs_extendable = attrs_str.is_empty()
549 || (context.config.attributes_on_same_line_as_variant()
550 && is_attributes_extendable(&attrs_str));
551 combine_strs_with_missing_comments(
563 context: &RewriteContext,
566 where_span_end: Option<BytePos>,
567 ) -> Option<String> {
568 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
569 let mut result = String::with_capacity(128);
570 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
571 let indent_str = offset.to_string(context.config);
572 let sep = format!("\n{}", &indent_str);
573 result.push_str(&ref_and_type);
575 let where_budget = if result.contains('\n') {
576 context.config.max_width()
578 context.budget(last_line_width(&result))
580 let option = WhereClauseOption::snuggled(&ref_and_type);
581 let where_clause_str = rewrite_where_clause(
583 &generics.where_clause,
584 context.config.item_brace_style(),
585 Shape::legacy(where_budget, offset.block_only()),
586 context.config.where_density(),
593 // If there is no where clause, we may have missing comments between the trait name and
594 // the opening brace.
595 if generics.where_clause.predicates.is_empty() {
596 if let Some(hi) = where_span_end {
597 match recover_missing_comment_in_span(
598 mk_sp(self_ty.span.hi(), hi),
599 Shape::indented(offset, context.config),
601 last_line_width(&result),
603 Some(ref missing_comment) if !missing_comment.is_empty() => {
604 result.push_str(missing_comment);
611 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
612 result.push_str(&where_clause_str);
613 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
614 result.push_str(&format!("{}{{{}}}", &sep, &sep));
616 result.push_str(" {}");
621 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
623 let width = offset.block_indent + context.config.tab_spaces() - 1;
624 let where_indent = Indent::new(0, width);
625 result.push_str(&where_indent.to_string(context.config));
627 result.push_str(&where_clause_str);
629 match context.config.item_brace_style() {
630 _ if last_line_contains_single_line_comment(&result) => result.push_str(&sep),
631 BraceStyle::AlwaysNextLine => result.push_str(&sep),
632 BraceStyle::PreferSameLine => result.push(' '),
633 BraceStyle::SameLineWhere => if !where_clause_str.is_empty() {
634 result.push_str(&sep);
642 let snippet = context.snippet(item.span);
643 let open_pos = snippet.find_uncommented("{")? + 1;
645 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
646 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
647 visitor.block_indent = offset.block_only().block_indent(context.config);
648 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
650 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
652 visitor.visit_impl_item(item);
655 visitor.format_missing(item.span.hi() - BytePos(1));
657 let inner_indent_str = visitor.block_indent.to_string(context.config);
658 let outer_indent_str = offset.block_only().to_string(context.config);
661 result.push_str(&inner_indent_str);
662 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
664 result.push_str(&outer_indent_str);
667 if result.chars().last().unwrap() == '{' {
668 result.push_str(&sep);
678 fn is_impl_single_line(
679 context: &RewriteContext,
682 where_clause_str: &str,
685 let snippet = context.snippet(item.span);
686 let open_pos = snippet.find_uncommented("{")? + 1;
689 context.config.impl_empty_single_line() && items.is_empty() && !result.contains('\n')
690 && result.len() + where_clause_str.len() <= context.config.max_width()
691 && !contains_comment(&snippet[open_pos..]),
695 fn format_impl_ref_and_type(
696 context: &RewriteContext,
699 ) -> Option<String> {
700 if let ast::ItemKind::Impl(
710 let mut result = String::with_capacity(128);
712 result.push_str(&format_visibility(&item.vis));
713 result.push_str(format_defaultness(defaultness));
714 result.push_str(format_unsafety(unsafety));
715 result.push_str("impl");
717 let lo = context.codemap.span_after(item.span, "impl");
718 let hi = match *trait_ref {
719 Some(ref tr) => tr.path.span.lo(),
720 None => self_ty.span.lo(),
722 let shape = generics_shape_from_config(
724 Shape::indented(offset + last_line_width(&result), context.config),
727 let one_line_budget = shape.width.checked_sub(last_line_width(&result) + 2)?;
729 rewrite_generics_inner(context, generics, shape, one_line_budget, mk_sp(lo, hi))?;
731 let polarity_str = if polarity == ast::ImplPolarity::Negative {
737 if let Some(ref trait_ref) = *trait_ref {
738 let result_len = result.len();
739 if let Some(trait_ref_str) = rewrite_trait_ref(
748 result.push_str(&trait_ref_str);
751 rewrite_generics_inner(context, generics, shape, 0, mk_sp(lo, hi))?;
752 result.push_str(&rewrite_trait_ref(
763 result.push_str(&generics_str);
766 // Try to put the self type in a single line.
768 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
769 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
770 // If there is no where clause adapt budget for type formatting to take space and curly
771 // brace into account.
772 match context.config.item_brace_style() {
773 BraceStyle::AlwaysNextLine => 0,
779 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
780 // 1 = space before the type.
781 let budget = context.budget(used_space + 1);
782 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
783 if !self_ty_str.contains('\n') {
784 if trait_ref.is_some() {
785 result.push_str(" for ");
789 result.push_str(&self_ty_str);
794 // Couldn't fit the self type on a single line, put it on a new line.
796 // Add indentation of one additional tab.
797 let new_line_offset = offset.block_indent(context.config);
798 result.push_str(&new_line_offset.to_string(context.config));
799 if trait_ref.is_some() {
800 result.push_str("for ");
802 let budget = context.budget(last_line_width(&result));
803 let type_offset = match context.config.where_style() {
804 Style::Legacy => new_line_offset + trait_ref_overhead,
805 Style::Rfc => new_line_offset,
807 result.push_str(&*self_ty
808 .rewrite(context, Shape::legacy(budget, type_offset))?);
815 fn rewrite_trait_ref(
816 context: &RewriteContext,
817 trait_ref: &ast::TraitRef,
823 ) -> Option<String> {
824 // 1 = space between generics and trait_ref
825 let used_space = 1 + polarity_str.len() + last_line_used_width(generics_str, result_len);
826 let shape = Shape::indented(offset + used_space, context.config);
827 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
828 if !(retry && trait_ref_str.contains('\n')) {
837 // We could not make enough space for trait_ref, so put it on new line.
839 let offset = offset.block_indent(context.config);
840 let shape = Shape::indented(offset, context.config);
841 let trait_ref_str = trait_ref.rewrite(context, shape)?;
845 &offset.to_string(context.config),
854 pub fn format_struct(
855 context: &RewriteContext,
858 vis: &ast::Visibility,
859 struct_def: &ast::VariantData,
860 generics: Option<&ast::Generics>,
863 one_line_width: Option<usize>,
864 ) -> Option<String> {
866 ast::VariantData::Unit(..) => Some(format_unit_struct(item_name, ident, vis)),
867 ast::VariantData::Tuple(ref fields, _) => format_tuple_struct(
877 ast::VariantData::Struct(ref fields, _) => format_struct_struct(
891 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
892 if let ast::ItemKind::Trait(unsafety, ref generics, ref type_param_bounds, ref trait_items) =
895 let mut result = String::with_capacity(128);
896 let header = format!(
898 format_visibility(&item.vis),
899 format_unsafety(unsafety),
903 result.push_str(&header);
905 let body_lo = context.codemap.span_after(item.span, "{");
907 let shape = Shape::indented(offset + last_line_width(&result), context.config);
909 rewrite_generics(context, generics, shape, mk_sp(item.span.lo(), body_lo))?;
910 result.push_str(&generics_str);
912 let trait_bound_str = rewrite_trait_bounds(
915 Shape::indented(offset, context.config),
917 // If the trait, generics, and trait bound cannot fit on the same line,
918 // put the trait bounds on an indented new line
919 if offset.width() + last_line_width(&result) + trait_bound_str.len()
920 > context.config.comment_width()
923 let trait_indent = offset.block_only().block_indent(context.config);
924 result.push_str(&trait_indent.to_string(context.config));
926 result.push_str(&trait_bound_str);
928 let has_body = !trait_items.is_empty();
930 let where_density = if (context.config.where_density() == Density::Compressed
931 && (!result.contains('\n') || context.config.fn_args_layout() == IndentStyle::Block))
932 || (context.config.fn_args_layout() == IndentStyle::Block && result.is_empty())
933 || (context.config.where_density() == Density::CompressedIfEmpty && !has_body
934 && !result.contains('\n'))
941 let where_budget = context.budget(last_line_width(&result));
942 let pos_before_where = if type_param_bounds.is_empty() {
943 generics.where_clause.span.lo()
945 type_param_bounds[type_param_bounds.len() - 1].span().hi()
947 let option = WhereClauseOption::snuggled(&generics_str);
948 let where_clause_str = rewrite_where_clause(
950 &generics.where_clause,
951 context.config.item_brace_style(),
952 Shape::legacy(where_budget, offset.block_only()),
959 // If the where clause cannot fit on the same line,
960 // put the where clause on a new line
961 if !where_clause_str.contains('\n')
962 && last_line_width(&result) + where_clause_str.len() + offset.width()
963 > context.config.comment_width()
966 let width = offset.block_indent + context.config.tab_spaces() - 1;
967 let where_indent = Indent::new(0, width);
968 result.push_str(&where_indent.to_string(context.config));
970 result.push_str(&where_clause_str);
972 if generics.where_clause.predicates.is_empty() {
973 let item_snippet = context.snippet(item.span);
974 if let Some(lo) = item_snippet.chars().position(|c| c == '/') {
976 let comment_hi = body_lo - BytePos(1);
977 let comment_lo = item.span.lo() + BytePos(lo as u32);
978 if comment_lo < comment_hi {
979 match recover_missing_comment_in_span(
980 mk_sp(comment_lo, comment_hi),
981 Shape::indented(offset, context.config),
983 last_line_width(&result),
985 Some(ref missing_comment) if !missing_comment.is_empty() => {
986 result.push_str(missing_comment);
994 match context.config.item_brace_style() {
995 _ if last_line_contains_single_line_comment(&result) => {
997 result.push_str(&offset.to_string(context.config));
999 BraceStyle::AlwaysNextLine => {
1001 result.push_str(&offset.to_string(context.config));
1003 BraceStyle::PreferSameLine => result.push(' '),
1004 BraceStyle::SameLineWhere => if !where_clause_str.is_empty()
1005 && (!trait_items.is_empty() || result.contains('\n'))
1008 result.push_str(&offset.to_string(context.config));
1015 let snippet = context.snippet(item.span);
1016 let open_pos = snippet.find_uncommented("{")? + 1;
1018 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1019 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
1020 visitor.block_indent = offset.block_only().block_indent(context.config);
1021 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1023 for item in trait_items {
1024 visitor.visit_trait_item(item);
1027 visitor.format_missing(item.span.hi() - BytePos(1));
1029 let inner_indent_str = visitor.block_indent.to_string(context.config);
1030 let outer_indent_str = offset.block_only().to_string(context.config);
1033 result.push_str(&inner_indent_str);
1034 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1036 result.push_str(&outer_indent_str);
1037 } else if result.contains('\n') {
1048 fn format_unit_struct(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
1049 format!("{};", format_header(item_name, ident, vis))
1052 pub fn format_struct_struct(
1053 context: &RewriteContext,
1056 vis: &ast::Visibility,
1057 fields: &[ast::StructField],
1058 generics: Option<&ast::Generics>,
1061 one_line_width: Option<usize>,
1062 ) -> Option<String> {
1063 let mut result = String::with_capacity(1024);
1065 let header_str = format_header(item_name, ident, vis);
1066 result.push_str(&header_str);
1068 let body_lo = context.codemap.span_after(span, "{");
1070 let generics_str = match generics {
1071 Some(g) => format_generics(
1076 context.config.item_brace_style(),
1079 mk_sp(span.lo(), body_lo),
1080 last_line_width(&result),
1083 // 3 = ` {}`, 2 = ` {`.
1084 let overhead = if fields.is_empty() { 3 } else { 2 };
1085 if (context.config.item_brace_style() == BraceStyle::AlwaysNextLine
1086 && !fields.is_empty())
1087 || context.config.max_width() < overhead + result.len()
1089 format!("\n{}{{", offset.block_only().to_string(context.config))
1096 let overhead = if fields.is_empty() { 1 } else { 0 };
1097 let total_width = result.len() + generics_str.len() + overhead;
1098 if !generics_str.is_empty() && !generics_str.contains('\n')
1099 && total_width > context.config.max_width()
1102 result.push_str(&offset.to_string(context.config));
1103 result.push_str(generics_str.trim_left());
1105 result.push_str(&generics_str);
1108 if fields.is_empty() {
1109 let snippet = context.snippet(mk_sp(body_lo, span.hi() - BytePos(1)));
1110 if snippet.trim().is_empty() {
1112 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1114 result.push_str(snippet.trim_right());
1116 result.push_str(&offset.to_string(context.config));
1118 result.push_str(&snippet);
1121 return Some(result);
1125 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1126 let one_line_budget =
1127 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1129 let items_str = rewrite_with_alignment(
1132 Shape::indented(offset, context.config),
1133 mk_sp(body_lo, span.hi()),
1137 if !items_str.contains('\n') && !result.contains('\n') && items_str.len() <= one_line_budget {
1138 Some(format!("{} {} }}", result, items_str))
1144 .block_indent(context.config)
1145 .to_string(context.config),
1147 offset.to_string(context.config)
1152 fn format_tuple_struct(
1153 context: &RewriteContext,
1156 vis: &ast::Visibility,
1157 fields: &[ast::StructField],
1158 generics: Option<&ast::Generics>,
1161 ) -> Option<String> {
1162 let mut result = String::with_capacity(1024);
1164 let header_str = format_header(item_name, ident, vis);
1165 result.push_str(&header_str);
1167 let body_lo = if fields.is_empty() {
1168 context.codemap.span_after(span, "(")
1172 let body_hi = if fields.is_empty() {
1173 context.codemap.span_after(span, ")")
1175 // This is a dirty hack to work around a missing `)` from the span of the last field.
1176 let last_arg_span = fields[fields.len() - 1].span;
1177 if context.snippet(last_arg_span).ends_with(')') {
1182 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1186 let where_clause_str = match generics {
1188 let budget = context.budget(last_line_width(&header_str));
1189 let shape = Shape::legacy(budget, offset);
1190 let g_span = mk_sp(span.lo(), body_lo);
1191 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1192 result.push_str(&generics_str);
1194 let where_budget = context.budget(last_line_width(&result));
1195 let option = WhereClauseOption::new(true, false);
1196 rewrite_where_clause(
1198 &generics.where_clause,
1199 context.config.item_brace_style(),
1200 Shape::legacy(where_budget, offset.block_only()),
1201 Density::Compressed,
1208 None => "".to_owned(),
1211 if fields.is_empty() {
1213 let used_width = last_line_used_width(&result, offset.width()) + 3;
1214 if used_width > context.config.max_width() {
1216 result.push_str(&offset
1217 .block_indent(context.config)
1218 .to_string(context.config))
1221 let snippet = context.snippet(mk_sp(body_lo, context.codemap.span_before(span, ")")));
1222 if snippet.is_empty() {
1224 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1225 result.push_str(snippet.trim_right());
1227 result.push_str(&offset.to_string(context.config));
1229 result.push_str(&snippet);
1234 let body = rewrite_call_inner(
1237 &fields.iter().map(|field| field).collect::<Vec<_>>()[..],
1239 Shape::legacy(context.budget(last_line_width(&result) + 3), offset),
1240 context.config.fn_call_width(),
1243 result.push_str(&body);
1246 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1247 && (result.contains('\n')
1248 || offset.block_indent + result.len() + where_clause_str.len() + 1
1249 > context.config.max_width())
1251 // We need to put the where clause on a new line, but we didn't
1252 // know that earlier, so the where clause will not be indented properly.
1254 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1255 .to_string(context.config));
1257 result.push_str(&where_clause_str);
1262 pub fn rewrite_type_alias(
1263 context: &RewriteContext,
1267 generics: &ast::Generics,
1268 vis: &ast::Visibility,
1270 ) -> Option<String> {
1271 let mut result = String::with_capacity(128);
1273 result.push_str(&format_visibility(vis));
1274 result.push_str("type ");
1275 result.push_str(&ident.to_string());
1278 let shape = Shape::indented(indent + result.len(), context.config).sub_width(2)?;
1279 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo());
1280 let generics_str = rewrite_generics(context, generics, shape, g_span)?;
1281 result.push_str(&generics_str);
1283 let where_budget = context.budget(last_line_width(&result));
1284 let option = WhereClauseOption::snuggled(&result);
1285 let where_clause_str = rewrite_where_clause(
1287 &generics.where_clause,
1288 context.config.item_brace_style(),
1289 Shape::legacy(where_budget, indent),
1290 context.config.where_density(),
1296 result.push_str(&where_clause_str);
1297 if where_clause_str.is_empty() {
1298 result.push_str(" = ");
1300 result.push_str(&format!("\n{}= ", indent.to_string(context.config)));
1303 let line_width = last_line_width(&result);
1304 // This checked_sub may fail as the extra space after '=' is not taken into account
1305 // In that case the budget is set to 0 which will make ty.rewrite retry on a new line
1306 let budget = context.budget(indent.width() + line_width + ";".len());
1307 let type_indent = indent + line_width;
1308 // Try to fit the type on the same line
1309 let ty_str = ty.rewrite(context, Shape::legacy(budget, type_indent))
1311 // The line was too short, try to put the type on the next line
1313 // Remove the space after '='
1315 let type_indent = indent.block_indent(context.config);
1317 result.push_str(&type_indent.to_string(context.config));
1318 let budget = context.budget(type_indent.width() + ";".len());
1319 ty.rewrite(context, Shape::legacy(budget, type_indent))
1321 result.push_str(&ty_str);
1322 result.push_str(";");
1326 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1328 if config.space_before_type_annotation() {
1333 if config.space_after_type_annotation_colon() {
1341 pub fn rewrite_struct_field_prefix(
1342 context: &RewriteContext,
1343 field: &ast::StructField,
1344 ) -> Option<String> {
1345 let vis = format_visibility(&field.vis);
1346 let type_annotation_spacing = type_annotation_spacing(context.config);
1347 Some(match field.ident {
1348 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1349 None => format!("{}", vis),
1353 impl Rewrite for ast::StructField {
1354 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1355 rewrite_struct_field(context, self, shape, 0)
1359 pub fn rewrite_struct_field(
1360 context: &RewriteContext,
1361 field: &ast::StructField,
1363 lhs_max_width: usize,
1364 ) -> Option<String> {
1365 if contains_skip(&field.attrs) {
1366 return Some(context.snippet(mk_sp(field.attrs[0].span.lo(), field.span.hi())));
1369 let type_annotation_spacing = type_annotation_spacing(context.config);
1370 let prefix = rewrite_struct_field_prefix(context, field)?;
1372 let attrs_str = field.attrs.rewrite(context, shape)?;
1373 let attrs_extendable = attrs_str.is_empty()
1374 || (context.config.attributes_on_same_line_as_field()
1375 && is_attributes_extendable(&attrs_str));
1376 let missing_span = if field.attrs.is_empty() {
1377 mk_sp(field.span.lo(), field.span.lo())
1379 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1381 let mut spacing = String::from(if field.ident.is_some() {
1382 type_annotation_spacing.1
1386 // Try to put everything on a single line.
1387 let attr_prefix = combine_strs_with_missing_comments(
1395 let overhead = last_line_width(&attr_prefix);
1396 let lhs_offset = lhs_max_width.checked_sub(overhead).unwrap_or(0);
1397 for _ in 0..lhs_offset {
1400 // In this extreme case we will be missing a space betweeen an attribute and a field.
1401 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1404 let ty_shape = shape.offset_left(overhead + spacing.len())?;
1405 if let Some(ref ty) = field.ty.rewrite(context, ty_shape) {
1406 if !ty.contains('\n') {
1407 return Some(attr_prefix + &spacing + ty);
1411 // We must use multiline.
1412 let new_shape = shape.with_max_width(context.config);
1413 let ty_rewritten = field.ty.rewrite(context, new_shape)?;
1415 let field_str = if prefix.is_empty() {
1417 } else if prefix.len() + first_line_width(&ty_rewritten) + 1 <= shape.width {
1418 prefix + " " + &ty_rewritten
1420 let type_offset = shape.indent.block_indent(context.config);
1421 let nested_shape = Shape::indented(type_offset, context.config);
1422 let nested_ty = field.ty.rewrite(context, nested_shape)?;
1423 prefix + "\n" + &type_offset.to_string(context.config) + &nested_ty
1425 combine_strs_with_missing_comments(
1435 pub fn rewrite_static(
1437 vis: &ast::Visibility,
1440 mutability: ast::Mutability,
1441 expr_opt: Option<&ptr::P<ast::Expr>>,
1444 context: &RewriteContext,
1445 ) -> Option<String> {
1446 let colon = colon_spaces(
1447 context.config.space_before_type_annotation(),
1448 context.config.space_after_type_annotation_colon(),
1450 let prefix = format!(
1452 format_visibility(vis),
1454 format_mutability(mutability),
1459 let ty_str = ty.rewrite(
1461 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?,
1464 if let Some(expr) = expr_opt {
1465 let lhs = format!("{}{} =", prefix, ty_str);
1467 let remaining_width = context.budget(offset.block_indent + 1);
1472 Shape::legacy(remaining_width, offset.block_only()),
1473 ).and_then(|res| recover_comment_removed(res, span, context))
1474 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1476 Some(format!("{}{};", prefix, ty_str))
1480 pub fn rewrite_associated_type(
1482 ty_opt: Option<&ptr::P<ast::Ty>>,
1483 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1484 context: &RewriteContext,
1486 ) -> Option<String> {
1487 let prefix = format!("type {}", ident);
1489 let type_bounds_str = if let Some(ty_param_bounds) = ty_param_bounds_opt {
1491 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1492 let bounds: &[_] = ty_param_bounds;
1493 let bound_str = bounds
1495 .map(|ty_bound| ty_bound.rewrite(context, shape))
1496 .collect::<Option<Vec<_>>>()?;
1497 if !bounds.is_empty() {
1498 format!(": {}", join_bounds(context, shape, &bound_str))
1506 if let Some(ty) = ty_opt {
1507 let ty_str = ty.rewrite(
1510 context.budget(indent.block_indent + prefix.len() + 2),
1511 indent.block_only(),
1514 Some(format!("{}{} = {};", prefix, type_bounds_str, ty_str))
1516 Some(format!("{}{};", prefix, type_bounds_str))
1520 pub fn rewrite_associated_impl_type(
1522 defaultness: ast::Defaultness,
1523 ty_opt: Option<&ptr::P<ast::Ty>>,
1524 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1525 context: &RewriteContext,
1527 ) -> Option<String> {
1528 let result = rewrite_associated_type(ident, ty_opt, ty_param_bounds_opt, context, indent)?;
1531 ast::Defaultness::Default => Some(format!("default {}", result)),
1536 impl Rewrite for ast::FunctionRetTy {
1537 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1539 ast::FunctionRetTy::Default(_) => Some(String::new()),
1540 ast::FunctionRetTy::Ty(ref ty) => {
1541 let inner_width = shape.width.checked_sub(3)?;
1542 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1543 .map(|r| format!("-> {}", r))
1549 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1551 ast::TyKind::Infer => {
1552 let original = context.snippet(ty.span);
1559 impl Rewrite for ast::Arg {
1560 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1561 if is_named_arg(self) {
1562 let mut result = self.pat
1563 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1565 if !is_empty_infer(context, &*self.ty) {
1566 if context.config.space_before_type_annotation() {
1567 result.push_str(" ");
1569 result.push_str(":");
1570 if context.config.space_after_type_annotation_colon() {
1571 result.push_str(" ");
1573 let overhead = last_line_width(&result);
1574 let max_width = shape.width.checked_sub(overhead)?;
1575 let ty_str = self.ty
1576 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1577 result.push_str(&ty_str);
1582 self.ty.rewrite(context, shape)
1587 fn rewrite_explicit_self(
1588 explicit_self: &ast::ExplicitSelf,
1590 context: &RewriteContext,
1591 ) -> Option<String> {
1592 match explicit_self.node {
1593 ast::SelfKind::Region(lt, m) => {
1594 let mut_str = format_mutability(m);
1597 let lifetime_str = l.rewrite(
1599 Shape::legacy(context.config.max_width(), Indent::empty()),
1601 Some(format!("&{} {}self", lifetime_str, mut_str))
1603 None => Some(format!("&{}self", mut_str)),
1606 ast::SelfKind::Explicit(ref ty, _) => {
1607 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1609 let mutability = explicit_self_mutability(&args[0]);
1610 let type_str = ty.rewrite(
1612 Shape::legacy(context.config.max_width(), Indent::empty()),
1617 format_mutability(mutability),
1621 ast::SelfKind::Value(_) => {
1622 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1624 let mutability = explicit_self_mutability(&args[0]);
1626 Some(format!("{}self", format_mutability(mutability)))
1631 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1632 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1633 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1634 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1641 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1642 if is_named_arg(arg) {
1649 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1651 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1652 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1653 _ => arg.ty.span.hi(),
1657 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1658 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1659 ident.node != symbol::keywords::Invalid.ident()
1665 // Return type is (result, force_new_line_for_brace)
1667 context: &RewriteContext,
1672 newline_brace: bool,
1674 ) -> Option<(String, bool)> {
1675 let mut force_new_line_for_brace = false;
1677 let where_clause = &fn_sig.generics.where_clause;
1679 let mut result = String::with_capacity(1024);
1680 result.push_str(&fn_sig.to_str(context));
1683 result.push_str("fn ");
1684 result.push_str(&ident.to_string());
1687 let overhead = if has_body && !newline_brace {
1694 let used_width = last_line_used_width(&result, indent.width());
1695 let one_line_budget = context.budget(used_width + overhead);
1697 width: one_line_budget,
1701 let fd = fn_sig.decl;
1702 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1703 let generics_str = rewrite_generics(context, fn_sig.generics, shape, g_span)?;
1704 result.push_str(&generics_str);
1706 let snuggle_angle_bracket = generics_str
1709 .map_or(false, |l| l.trim_left().len() == 1);
1711 // Note that the width and indent don't really matter, we'll re-layout the
1712 // return type later anyway.
1713 let ret_str = fd.output
1714 .rewrite(context, Shape::indented(indent, context.config))?;
1716 let multi_line_ret_str = ret_str.contains('\n');
1717 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1720 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1731 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1737 // Check if vertical layout was forced.
1738 if one_line_budget == 0 {
1739 if snuggle_angle_bracket {
1741 } else if context.config.fn_args_paren_newline() {
1743 result.push_str(&arg_indent.to_string(context.config));
1744 if context.config.fn_args_layout() == IndentStyle::Visual {
1745 arg_indent = arg_indent + 1; // extra space for `(`
1749 result.push_str("(");
1750 if context.config.fn_args_layout() == IndentStyle::Visual {
1752 result.push_str(&arg_indent.to_string(context.config));
1758 if context.config.spaces_within_parens() && !fd.inputs.is_empty() && result.ends_with('(') {
1762 // Skip `pub(crate)`.
1763 let lo_after_visibility = if let ast::Visibility::Crate(s) = fn_sig.visibility {
1764 context.codemap.span_after(mk_sp(s.hi(), span.hi()), ")")
1768 // A conservative estimation, to goal is to be over all parens in generics
1769 let args_start = fn_sig
1773 .map_or(lo_after_visibility, |tp| end_typaram(tp));
1774 let args_end = if fd.inputs.is_empty() {
1777 .span_after(mk_sp(args_start, span.hi()), ")")
1779 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1780 context.codemap.span_after(last_span, ")")
1782 let args_span = mk_sp(
1785 .span_after(mk_sp(args_start, span.hi()), "("),
1788 let arg_str = rewrite_args(
1791 fd.get_self().as_ref(),
1798 generics_str.contains('\n'),
1801 let put_args_in_block = match context.config.fn_args_layout() {
1802 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1804 } && !fd.inputs.is_empty();
1806 let mut args_last_line_contains_comment = false;
1807 if put_args_in_block {
1808 arg_indent = indent.block_indent(context.config);
1810 result.push_str(&arg_indent.to_string(context.config));
1811 result.push_str(&arg_str);
1813 result.push_str(&indent.to_string(context.config));
1816 result.push_str(&arg_str);
1817 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1818 // Put the closing brace on the next line if it overflows the max width.
1820 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1823 if context.config.spaces_within_parens() && !fd.inputs.is_empty() {
1826 // If the last line of args contains comment, we cannot put the closing paren
1827 // on the same line.
1831 .map_or(false, |last_line| last_line.contains("//"))
1833 args_last_line_contains_comment = true;
1835 result.push_str(&arg_indent.to_string(context.config));
1841 if let ast::FunctionRetTy::Ty(..) = fd.output {
1842 let ret_should_indent = match context.config.fn_args_layout() {
1843 // If our args are block layout then we surely must have space.
1844 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
1845 _ if args_last_line_contains_comment => false,
1846 _ if result.contains('\n') || multi_line_ret_str => true,
1848 // If the return type would push over the max width, then put the return type on
1849 // a new line. With the +1 for the signature length an additional space between
1850 // the closing parenthesis of the argument and the arrow '->' is considered.
1851 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
1853 // If there is no where clause, take into account the space after the return type
1855 if where_clause.predicates.is_empty() {
1859 sig_length > context.config.max_width()
1862 let ret_indent = if ret_should_indent {
1863 let indent = match context.config.fn_return_indent() {
1864 ReturnIndent::WithWhereClause => indent + 4,
1865 // Aligning with non-existent args looks silly.
1866 _ if arg_str.is_empty() => {
1867 force_new_line_for_brace = true;
1870 // FIXME: we might want to check that using the arg indent
1871 // doesn't blow our budget, and if it does, then fallback to
1872 // the where clause indent.
1877 result.push_str(&indent.to_string(context.config));
1881 Indent::new(indent.block_indent, last_line_width(&result))
1884 if multi_line_ret_str || ret_should_indent {
1885 // Now that we know the proper indent and width, we need to
1886 // re-layout the return type.
1887 let ret_str = fd.output
1888 .rewrite(context, Shape::indented(ret_indent, context.config))?;
1889 result.push_str(&ret_str);
1891 result.push_str(&ret_str);
1894 // Comment between return type and the end of the decl.
1895 let snippet_lo = fd.output.span().hi();
1896 if where_clause.predicates.is_empty() {
1897 let snippet_hi = span.hi();
1898 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
1899 // Try to preserve the layout of the original snippet.
1900 let original_starts_with_newline = snippet
1902 .map_or(false, |i| starts_with_newline(&snippet[i..]));
1903 let original_ends_with_newline = snippet
1904 .rfind(|c| c != ' ')
1905 .map_or(false, |i| snippet[i..].ends_with('\n'));
1906 let snippet = snippet.trim();
1907 if !snippet.is_empty() {
1908 result.push(if original_starts_with_newline {
1913 result.push_str(snippet);
1914 if original_ends_with_newline {
1915 force_new_line_for_brace = true;
1921 let should_compress_where = match context.config.where_density() {
1922 Density::Compressed => !result.contains('\n'),
1923 Density::CompressedIfEmpty => !has_body && !result.contains('\n'),
1927 let pos_before_where = match fd.output {
1928 ast::FunctionRetTy::Default(..) => args_span.hi(),
1929 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
1932 if where_clause.predicates.len() == 1 && should_compress_where {
1933 let budget = context.budget(last_line_used_width(&result, indent.width()));
1934 if let Some(where_clause_str) = rewrite_where_clause(
1937 context.config.fn_brace_style(),
1938 Shape::legacy(budget, indent),
1939 Density::Compressed,
1943 WhereClauseOption::compressed(),
1945 result.push_str(&where_clause_str);
1946 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
1947 return Some((result, force_new_line_for_brace));
1951 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
1952 let where_clause_str = rewrite_where_clause(
1955 context.config.fn_brace_style(),
1956 Shape::indented(indent, context.config),
1963 // If there are neither where clause nor return type, we may be missing comments between
1965 if where_clause_str.is_empty() {
1966 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
1967 match recover_missing_comment_in_span(
1968 mk_sp(args_span.hi(), ret_span.hi()),
1971 last_line_width(&result),
1973 Some(ref missing_comment) if !missing_comment.is_empty() => {
1974 result.push_str(missing_comment);
1975 force_new_line_for_brace = true;
1982 result.push_str(&where_clause_str);
1984 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
1985 Some((result, force_new_line_for_brace))
1988 #[derive(Copy, Clone)]
1989 struct WhereClauseOption {
1990 suppress_comma: bool, // Force no trailing comma
1991 snuggle: bool, // Do not insert newline before `where`
1992 compress_where: bool, // Try single line where clause instead of vertical layout
1995 impl WhereClauseOption {
1996 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
1998 suppress_comma: suppress_comma,
2000 compress_where: false,
2004 pub fn compressed() -> WhereClauseOption {
2006 suppress_comma: true,
2008 compress_where: true,
2012 pub fn snuggled(current: &str) -> WhereClauseOption {
2014 suppress_comma: false,
2015 snuggle: trimmed_last_line_width(current) == 1,
2016 compress_where: false,
2022 context: &RewriteContext,
2024 explicit_self: Option<&ast::ExplicitSelf>,
2025 one_line_budget: usize,
2026 multi_line_budget: usize,
2031 generics_str_contains_newline: bool,
2032 ) -> Option<String> {
2033 let mut arg_item_strs = args.iter()
2034 .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
2035 .collect::<Option<Vec<_>>>()?;
2037 // Account for sugary self.
2038 // FIXME: the comment for the self argument is dropped. This is blocked
2039 // on rust issue #27522.
2040 let min_args = explicit_self
2041 .and_then(|explicit_self| {
2042 rewrite_explicit_self(explicit_self, args, context)
2044 .map_or(1, |self_str| {
2045 arg_item_strs[0] = self_str;
2049 // Comments between args.
2050 let mut arg_items = Vec::new();
2052 arg_items.push(ListItem::from_str(""));
2055 // FIXME(#21): if there are no args, there might still be a comment, but
2056 // without spans for the comment or parens, there is no chance of
2057 // getting it right. You also don't get to put a comment on self, unless
2059 if args.len() >= min_args || variadic {
2060 let comment_span_start = if min_args == 2 {
2061 let second_arg_start = if arg_has_pattern(&args[1]) {
2062 args[1].pat.span.lo()
2064 args[1].ty.span.lo()
2066 let reduced_span = mk_sp(span.lo(), second_arg_start);
2068 context.codemap.span_after_last(reduced_span, ",")
2073 enum ArgumentKind<'a> {
2074 Regular(&'a ast::Arg),
2078 let variadic_arg = if variadic {
2079 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2080 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2081 Some(ArgumentKind::Variadic(variadic_start))
2086 let more_items = itemize_list(
2088 args[min_args - 1..]
2090 .map(ArgumentKind::Regular)
2091 .chain(variadic_arg),
2094 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2095 ArgumentKind::Variadic(start) => start,
2098 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2099 ArgumentKind::Variadic(start) => start + BytePos(3),
2102 ArgumentKind::Regular(..) => None,
2103 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2110 arg_items.extend(more_items);
2113 let fits_in_one_line = !generics_str_contains_newline
2114 && (arg_items.is_empty()
2115 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2117 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2118 item.item = Some(arg);
2121 let last_line_ends_with_comment = arg_items
2124 .and_then(|item| item.post_comment.as_ref())
2125 .map_or(false, |s| s.trim().starts_with("//"));
2127 let (indent, trailing_comma) = match context.config.fn_args_layout() {
2128 IndentStyle::Block if fits_in_one_line => {
2129 (indent.block_indent(context.config), SeparatorTactic::Never)
2131 IndentStyle::Block => (
2132 indent.block_indent(context.config),
2133 context.config.trailing_comma(),
2135 IndentStyle::Visual if last_line_ends_with_comment => {
2136 (arg_indent, context.config.trailing_comma())
2138 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2141 let tactic = definitive_tactic(
2143 context.config.fn_args_density().to_list_tactic(),
2147 let budget = match tactic {
2148 DefinitiveListTactic::Horizontal => one_line_budget,
2149 _ => multi_line_budget,
2152 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2154 let fmt = ListFormatting {
2157 trailing_separator: if variadic {
2158 SeparatorTactic::Never
2162 separator_place: SeparatorPlace::Back,
2163 shape: Shape::legacy(budget, indent),
2164 ends_with_newline: tactic.ends_with_newline(context.config.fn_args_layout()),
2165 preserve_newline: true,
2166 config: context.config,
2169 write_list(&arg_items, &fmt)
2172 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2173 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2174 ident.node != symbol::keywords::Invalid.ident()
2180 fn compute_budgets_for_args(
2181 context: &RewriteContext,
2185 newline_brace: bool,
2187 force_vertical_layout: bool,
2188 ) -> Option<((usize, usize, Indent))> {
2190 "compute_budgets_for_args {} {:?}, {}, {}",
2196 // Try keeping everything on the same line.
2197 if !result.contains('\n') && !force_vertical_layout {
2198 // 2 = `()`, 3 = `() `, space is before ret_string.
2199 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2200 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2210 let one_line_budget = context.budget(used_space);
2212 if one_line_budget > 0 {
2214 let (indent, multi_line_budget) = match context.config.fn_args_layout() {
2215 IndentStyle::Block => {
2216 let indent = indent.block_indent(context.config);
2217 (indent, context.budget(indent.width() + 1))
2219 IndentStyle::Visual => {
2220 let indent = indent + result.len() + 1;
2221 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2222 (indent, context.budget(multi_line_overhead))
2226 return Some((one_line_budget, multi_line_budget, indent));
2230 // Didn't work. we must force vertical layout and put args on a newline.
2231 let new_indent = indent.block_indent(context.config);
2232 let used_space = match context.config.fn_args_layout() {
2234 IndentStyle::Block => new_indent.width() + 1,
2235 // Account for `)` and possibly ` {`.
2236 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2238 Some((0, context.budget(used_space), new_indent))
2241 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause, has_body: bool) -> bool {
2242 match (config.fn_brace_style(), config.where_density()) {
2243 (BraceStyle::AlwaysNextLine, _) => true,
2244 (_, Density::Compressed) if where_clause.predicates.len() == 1 => false,
2245 (_, Density::CompressedIfEmpty) if where_clause.predicates.len() == 1 && !has_body => false,
2246 (BraceStyle::SameLineWhere, _) if !where_clause.predicates.is_empty() => true,
2251 fn rewrite_generics(
2252 context: &RewriteContext,
2253 generics: &ast::Generics,
2256 ) -> Option<String> {
2257 let g_shape = generics_shape_from_config(context.config, shape, 0)?;
2258 let one_line_width = shape.width.checked_sub(2).unwrap_or(0);
2259 rewrite_generics_inner(context, generics, g_shape, one_line_width, span).or_else(|| {
2260 rewrite_generics_inner(context, generics, g_shape, 0, span)
2264 fn rewrite_generics_inner(
2265 context: &RewriteContext,
2266 generics: &ast::Generics,
2268 one_line_width: usize,
2270 ) -> Option<String> {
2271 // FIXME: convert bounds to where clauses where they get too big or if
2272 // there is a where clause at all.
2275 enum GenericsArg<'a> {
2276 Lifetime(&'a ast::LifetimeDef),
2277 TyParam(&'a ast::TyParam),
2279 impl<'a> Rewrite for GenericsArg<'a> {
2280 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2282 GenericsArg::Lifetime(ref lifetime) => lifetime.rewrite(context, shape),
2283 GenericsArg::TyParam(ref ty) => ty.rewrite(context, shape),
2287 impl<'a> Spanned for GenericsArg<'a> {
2288 fn span(&self) -> Span {
2290 GenericsArg::Lifetime(ref lifetime) => lifetime.span(),
2291 GenericsArg::TyParam(ref ty) => ty.span(),
2296 if generics.lifetimes.is_empty() && generics.ty_params.is_empty() {
2297 return Some(String::new());
2300 let generics_args = generics
2303 .map(|lt| GenericsArg::Lifetime(lt))
2304 .chain(generics.ty_params.iter().map(|ty| GenericsArg::TyParam(ty)));
2305 let items = itemize_list(
2309 |arg| arg.span().lo(),
2310 |arg| arg.span().hi(),
2311 |arg| arg.rewrite(context, shape),
2312 context.codemap.span_after(span, "<"),
2316 format_generics_item_list(context, items, shape, one_line_width)
2319 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2320 match config.generics_indent() {
2321 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2322 IndentStyle::Block => {
2326 .block_indent(config.tab_spaces())
2327 .with_max_width(config)
2333 pub fn format_generics_item_list<I>(
2334 context: &RewriteContext,
2337 one_line_budget: usize,
2340 I: Iterator<Item = ListItem>,
2342 let item_vec = items.collect::<Vec<_>>();
2344 let tactic = definitive_tactic(
2346 ListTactic::HorizontalVertical,
2350 let fmt = ListFormatting {
2353 trailing_separator: if context.config.generics_indent() == IndentStyle::Visual {
2354 SeparatorTactic::Never
2356 context.config.trailing_comma()
2358 separator_place: SeparatorPlace::Back,
2360 ends_with_newline: tactic.ends_with_newline(context.config.generics_indent()),
2361 preserve_newline: true,
2362 config: context.config,
2365 let list_str = write_list(&item_vec, &fmt)?;
2367 Some(wrap_generics_with_angle_brackets(
2374 pub fn wrap_generics_with_angle_brackets(
2375 context: &RewriteContext,
2377 list_offset: Indent,
2379 if context.config.generics_indent() == IndentStyle::Block
2380 && (list_str.contains('\n') || list_str.ends_with(','))
2384 list_offset.to_string(context.config),
2387 .block_unindent(context.config)
2388 .to_string(context.config)
2390 } else if context.config.spaces_within_angle_brackets() {
2391 format!("< {} >", list_str)
2393 format!("<{}>", list_str)
2397 fn rewrite_trait_bounds(
2398 context: &RewriteContext,
2399 type_param_bounds: &ast::TyParamBounds,
2401 ) -> Option<String> {
2402 let bounds: &[_] = type_param_bounds;
2404 if bounds.is_empty() {
2405 return Some(String::new());
2407 let bound_str = bounds
2409 .map(|ty_bound| ty_bound.rewrite(context, shape))
2410 .collect::<Option<Vec<_>>>()?;
2411 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2414 fn rewrite_where_clause_rfc_style(
2415 context: &RewriteContext,
2416 where_clause: &ast::WhereClause,
2419 span_end: Option<BytePos>,
2420 span_end_before_where: BytePos,
2421 where_clause_option: WhereClauseOption,
2422 ) -> Option<String> {
2423 let block_shape = shape.block().with_max_width(context.config);
2425 let (span_before, span_after) =
2426 missing_span_before_after_where(span_end_before_where, where_clause);
2427 let (comment_before, comment_after) =
2428 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2430 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2433 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2436 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2438 let clause_shape = clause_shape.sub_width(1)?;
2439 // each clause on one line, trailing comma (except if suppress_comma)
2440 let span_start = where_clause.predicates[0].span().lo();
2441 // If we don't have the start of the next span, then use the end of the
2442 // predicates, but that means we miss comments.
2443 let len = where_clause.predicates.len();
2444 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2445 let span_end = span_end.unwrap_or(end_of_preds);
2446 let items = itemize_list(
2448 where_clause.predicates.iter(),
2450 |pred| pred.span().lo(),
2451 |pred| pred.span().hi(),
2452 |pred| pred.rewrite(context, clause_shape),
2457 let comma_tactic = if where_clause_option.suppress_comma {
2458 SeparatorTactic::Never
2460 context.config.trailing_comma()
2463 let fmt = ListFormatting {
2464 tactic: DefinitiveListTactic::Vertical,
2466 trailing_separator: comma_tactic,
2467 separator_place: SeparatorPlace::Back,
2468 shape: clause_shape,
2469 ends_with_newline: true,
2470 preserve_newline: true,
2471 config: context.config,
2473 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2475 let comment_separator = |comment: &str, shape: Shape| if comment.is_empty() {
2478 format!("\n{}", shape.indent.to_string(context.config))
2480 let newline_before_where = comment_separator(&comment_before, shape);
2481 let newline_after_where = comment_separator(&comment_after, clause_shape);
2484 let clause_sep = if where_clause_option.compress_where && comment_before.is_empty()
2485 && comment_after.is_empty() && !preds_str.contains('\n')
2486 && 6 + preds_str.len() <= shape.width
2490 format!("\n{}", clause_shape.indent.to_string(context.config))
2493 "{}{}{}where{}{}{}{}",
2496 newline_before_where,
2497 newline_after_where,
2504 fn rewrite_where_clause(
2505 context: &RewriteContext,
2506 where_clause: &ast::WhereClause,
2507 brace_style: BraceStyle,
2511 span_end: Option<BytePos>,
2512 span_end_before_where: BytePos,
2513 where_clause_option: WhereClauseOption,
2514 ) -> Option<String> {
2515 if where_clause.predicates.is_empty() {
2516 return Some(String::new());
2519 if context.config.where_style() == Style::Rfc {
2520 return rewrite_where_clause_rfc_style(
2526 span_end_before_where,
2527 where_clause_option,
2531 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2533 let offset = match context.config.where_pred_indent() {
2534 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2535 // 6 = "where ".len()
2536 IndentStyle::Visual => shape.indent + extra_indent + 6,
2538 // FIXME: if where_pred_indent != Visual, then the budgets below might
2539 // be out by a char or two.
2541 let budget = context.config.max_width() - offset.width();
2542 let span_start = where_clause.predicates[0].span().lo();
2543 // If we don't have the start of the next span, then use the end of the
2544 // predicates, but that means we miss comments.
2545 let len = where_clause.predicates.len();
2546 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2547 let span_end = span_end.unwrap_or(end_of_preds);
2548 let items = itemize_list(
2550 where_clause.predicates.iter(),
2552 |pred| pred.span().lo(),
2553 |pred| pred.span().hi(),
2554 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2559 let item_vec = items.collect::<Vec<_>>();
2560 // FIXME: we don't need to collect here if the where_layout isn't
2561 // HorizontalVertical.
2562 let tactic = definitive_tactic(
2564 context.config.where_layout(),
2569 let mut comma_tactic = context.config.trailing_comma();
2570 // Kind of a hack because we don't usually have trailing commas in where clauses.
2571 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2572 comma_tactic = SeparatorTactic::Never;
2575 let fmt = ListFormatting {
2578 trailing_separator: comma_tactic,
2579 separator_place: SeparatorPlace::Back,
2580 shape: Shape::legacy(budget, offset),
2581 ends_with_newline: tactic.ends_with_newline(context.config.where_pred_indent()),
2582 preserve_newline: true,
2583 config: context.config,
2585 let preds_str = write_list(&item_vec, &fmt)?;
2587 let end_length = if terminator == "{" {
2588 // If the brace is on the next line we don't need to count it otherwise it needs two
2591 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2592 BraceStyle::PreferSameLine => 2,
2594 } else if terminator == "=" {
2599 if density == Density::Tall || preds_str.contains('\n')
2600 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2604 (shape.indent + extra_indent).to_string(context.config),
2608 Some(format!(" where {}", preds_str))
2612 fn missing_span_before_after_where(
2613 before_item_span_end: BytePos,
2614 where_clause: &ast::WhereClause,
2616 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2618 let pos_after_where = where_clause.span.lo() + BytePos(5);
2619 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2620 (missing_span_before, missing_span_after)
2623 fn rewrite_comments_before_after_where(
2624 context: &RewriteContext,
2625 span_before_where: Span,
2626 span_after_where: Span,
2628 ) -> Option<(String, String)> {
2629 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2630 let after_comment = rewrite_missing_comment(
2632 shape.block_indent(context.config.tab_spaces()),
2635 Some((before_comment, after_comment))
2638 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2639 format!("{}{}{}", format_visibility(vis), item_name, ident)
2643 context: &RewriteContext,
2644 generics: &ast::Generics,
2647 brace_style: BraceStyle,
2648 force_same_line_brace: bool,
2652 ) -> Option<String> {
2653 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2654 let mut result = rewrite_generics(context, generics, shape, span)?;
2656 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2657 let budget = context.budget(last_line_used_width(&result, offset.width()));
2658 let option = WhereClauseOption::snuggled(&result);
2659 let where_clause_str = rewrite_where_clause(
2661 &generics.where_clause,
2663 Shape::legacy(budget, offset.block_only()),
2670 result.push_str(&where_clause_str);
2671 force_same_line_brace || brace_style == BraceStyle::PreferSameLine
2672 || (generics.where_clause.predicates.is_empty()
2673 && trimmed_last_line_width(&result) == 1)
2675 force_same_line_brace || trimmed_last_line_width(&result) == 1
2676 || brace_style != BraceStyle::AlwaysNextLine
2678 let total_used_width = last_line_used_width(&result, used_width);
2679 let remaining_budget = context.budget(total_used_width);
2680 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2681 // and hence we take the closer into account as well for one line budget.
2682 // We assume that the closer has the same length as the opener.
2683 let overhead = if force_same_line_brace {
2684 1 + opener.len() + opener.len()
2688 let forbid_same_line_brace = overhead > remaining_budget;
2689 if !forbid_same_line_brace && same_line_brace {
2693 result.push_str(&offset.block_only().to_string(context.config));
2695 result.push_str(opener);
2700 impl Rewrite for ast::ForeignItem {
2701 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2702 let attrs_str = self.attrs.rewrite(context, shape)?;
2703 // Drop semicolon or it will be interpreted as comment.
2704 // FIXME: this may be a faulty span from libsyntax.
2705 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2707 let item_str = match self.node {
2708 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => rewrite_fn_base(
2712 &FnSig::new(fn_decl, generics, self.vis.clone()),
2716 ).map(|(s, _)| format!("{};", s)),
2717 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2718 // FIXME(#21): we're dropping potential comments in between the
2719 // function keywords here.
2720 let vis = format_visibility(&self.vis);
2721 let mut_str = if is_mutable { "mut " } else { "" };
2722 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2724 let shape = shape.sub_width(1)?;
2725 ty.rewrite(context, shape).map(|ty_str| {
2726 // 1 = space between prefix and type.
2727 let sep = if prefix.len() + ty_str.len() + 1 <= shape.width {
2730 let nested_indent = shape.indent.block_indent(context.config);
2731 format!("\n{}", nested_indent.to_string(context.config))
2733 format!("{}{}{};", prefix, sep, ty_str)
2738 let missing_span = if self.attrs.is_empty() {
2739 mk_sp(self.span.lo(), self.span.lo())
2741 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2743 combine_strs_with_missing_comments(