1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Formatting top-level items - functions, structs, enums, traits, impls.
14 use codemap::SpanUtils;
15 use utils::{format_mutability, format_visibility, contains_skip, end_typaram, wrap_str,
16 last_line_width, format_unsafety, trim_newlines, stmt_expr, semicolon_for_expr,
17 trimmed_last_line_width, colon_spaces, mk_sp};
18 use lists::{write_list, itemize_list, ListItem, ListFormatting, SeparatorTactic, list_helper,
19 DefinitiveListTactic, ListTactic, definitive_tactic};
20 use expr::{format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs, ExprType};
21 use comment::{FindUncommented, contains_comment, rewrite_comment, recover_comment_removed};
22 use visitor::FmtVisitor;
23 use rewrite::{Rewrite, RewriteContext};
24 use config::{Config, IndentStyle, Density, ReturnIndent, BraceStyle, Style};
25 use types::join_bounds;
26 use vertical::rewrite_with_alignment;
28 use syntax::{ast, abi, ptr, symbol};
29 use syntax::codemap::{Span, BytePos};
30 use syntax::ast::ImplItem;
32 fn type_annotation_separator(config: &Config) -> &str {
34 config.space_before_type_annotation(),
35 config.space_after_type_annotation_colon(),
40 // Statements of the form
41 // let pat: ty = init;
42 impl Rewrite for ast::Local {
43 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
45 "Local::rewrite {:?} {} {:?}",
50 let mut result = "let ".to_owned();
53 let pat_shape = try_opt!(shape.offset_left(4));
55 let pat_shape = try_opt!(pat_shape.sub_width(1));
56 let pat_str = try_opt!(self.pat.rewrite(&context, pat_shape));
57 result.push_str(&pat_str);
59 // String that is placed within the assignment pattern and expression.
61 let mut infix = String::new();
63 if let Some(ref ty) = self.ty {
64 let separator = type_annotation_separator(context.config);
65 let indent = shape.indent + last_line_width(&result) + separator.len();
67 let budget = try_opt!(shape.width.checked_sub(indent.width() + 1));
68 let rewrite = try_opt!(ty.rewrite(context, Shape::legacy(budget, indent)));
70 infix.push_str(separator);
71 infix.push_str(&rewrite);
74 if self.init.is_some() {
81 result.push_str(&infix);
83 if let Some(ref ex) = self.init {
84 // 1 = trailing semicolon;
85 let nested_shape = try_opt!(shape.sub_width(1));
87 result = try_opt!(rewrite_assign_rhs(&context, result, ex, nested_shape));
95 // TODO convert to using rewrite style rather than visitor
96 // TODO format modules in this style
99 keyword: &'static str,
101 vis: Option<&'a ast::Visibility>,
102 body: Vec<BodyElement<'a>>,
107 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
108 let abi = if fm.abi == abi::Abi::C && !config.force_explicit_abi() {
111 format!("extern {}", fm.abi)
119 .map(|i| BodyElement::ForeignItem(i))
126 enum BodyElement<'a> {
127 // Stmt(&'a ast::Stmt),
128 // Field(&'a ast::Field),
129 // Variant(&'a ast::Variant),
130 // Item(&'a ast::Item),
131 ForeignItem(&'a ast::ForeignItem),
134 impl<'a> FmtVisitor<'a> {
135 fn format_item(&mut self, item: Item) {
136 self.buffer.push_str(&item.abi);
137 self.buffer.push_str(" ");
139 let snippet = self.snippet(item.span);
140 let brace_pos = snippet.find_uncommented("{").unwrap();
142 self.buffer.push_str("{");
143 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
144 // FIXME: this skips comments between the extern keyword and the opening
146 self.last_pos = item.span.lo + BytePos(brace_pos as u32 + 1);
147 self.block_indent = self.block_indent.block_indent(self.config);
149 if item.body.is_empty() {
150 self.format_missing_no_indent(item.span.hi - BytePos(1));
151 self.block_indent = self.block_indent.block_unindent(self.config);
154 .push_str(&self.block_indent.to_string(self.config));
156 for item in &item.body {
157 self.format_body_element(item);
160 self.block_indent = self.block_indent.block_unindent(self.config);
161 self.format_missing_with_indent(item.span.hi - BytePos(1));
165 self.buffer.push_str("}");
166 self.last_pos = item.span.hi;
169 fn format_body_element(&mut self, element: &BodyElement) {
171 BodyElement::ForeignItem(ref item) => self.format_foreign_item(item),
175 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
176 let item = Item::from_foreign_mod(fm, span, self.config);
177 self.format_item(item);
180 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
181 self.format_missing_with_indent(item.span.lo);
182 // Drop semicolon or it will be interpreted as comment.
183 // FIXME: this may be a faulty span from libsyntax.
184 let span = mk_sp(item.span.lo, item.span.hi - BytePos(1));
187 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
188 let indent = self.block_indent;
189 let rewrite = rewrite_fn_base(
195 ast::Unsafety::Normal,
196 ast::Constness::NotConst,
197 ast::Defaultness::Final,
198 // These are not actually rust functions,
199 // but we format them as such.
209 Some((new_fn, _)) => {
210 self.buffer.push_str(&new_fn);
211 self.buffer.push_str(";");
213 None => self.format_missing(item.span.hi),
216 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
217 // FIXME(#21): we're dropping potential comments in between the
218 // function keywords here.
219 let vis = format_visibility(&item.vis);
220 let mut_str = if is_mutable { "mut " } else { "" };
221 let prefix = format!("{}static {}{}: ", vis, mut_str, item.ident);
222 let offset = self.block_indent + prefix.len();
224 let shape = Shape::indented(offset, self.config).sub_width(1).unwrap();
225 let rewrite = ty.rewrite(&self.get_context(), shape);
229 self.buffer.push_str(&prefix);
230 self.buffer.push_str(&result);
231 self.buffer.push_str(";");
233 None => self.format_missing(item.span.hi),
238 self.last_pos = item.span.hi;
246 generics: &ast::Generics,
247 unsafety: ast::Unsafety,
248 constness: ast::Constness,
249 defaultness: ast::Defaultness,
251 vis: &ast::Visibility,
254 ) -> Option<String> {
255 let mut newline_brace = newline_for_brace(self.config, &generics.where_clause);
256 let context = self.get_context();
258 let block_snippet = self.snippet(mk_sp(block.span.lo, block.span.hi));
259 let has_body = !block_snippet[1..block_snippet.len() - 1].trim().is_empty() ||
260 !context.config.fn_empty_single_line();
262 let (mut result, force_newline_brace) = try_opt!(rewrite_fn_base(
279 if force_newline_brace {
280 newline_brace = true;
281 } else if self.config.fn_brace_style() != BraceStyle::AlwaysNextLine &&
282 !result.contains('\n')
284 newline_brace = false;
287 // Prepare for the function body by possibly adding a newline and
289 // FIXME we'll miss anything between the end of the signature and the
290 // start of the body, but we need more spans from the compiler to solve
294 result.push_str(&indent.to_string(self.config));
299 self.single_line_fn(&result, block).or_else(|| Some(result))
302 pub fn rewrite_required_fn(
306 sig: &ast::MethodSig,
308 ) -> Option<String> {
309 // Drop semicolon or it will be interpreted as comment.
310 let span = mk_sp(span.lo, span.hi - BytePos(1));
311 let context = self.get_context();
313 let (mut result, _) = try_opt!(rewrite_fn_base(
321 ast::Defaultness::Final,
323 &ast::Visibility::Inherited,
330 // Re-attach semicolon
336 fn single_line_fn(&self, fn_str: &str, block: &ast::Block) -> Option<String> {
337 if fn_str.contains('\n') {
341 let codemap = self.get_context().codemap;
343 if self.config.fn_empty_single_line() && is_empty_block(block, codemap) &&
344 self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
346 return Some(format!("{}{{}}", fn_str));
349 if self.config.fn_single_line() && is_simple_block_stmt(block, codemap) {
351 if let Some(ref stmt) = block.stmts.first() {
352 match stmt_expr(stmt) {
354 let suffix = if semicolon_for_expr(e) { ";" } else { "" };
360 Shape::indented(self.block_indent, self.config),
361 ).map(|s| s + suffix)
362 .or_else(|| Some(self.snippet(e.span)))
367 Shape::indented(self.block_indent, self.config),
376 if let Some(res) = rewrite {
377 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
378 if !res.contains('\n') && width <= self.config.max_width() {
379 return Some(format!("{}{{ {} }}", fn_str, res));
390 vis: &ast::Visibility,
391 enum_def: &ast::EnumDef,
392 generics: &ast::Generics,
395 self.buffer.push_str(&format_header("enum ", ident, vis));
397 let enum_snippet = self.snippet(span);
398 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
399 let body_start = span.lo + BytePos(brace_pos as u32 + 1);
400 let generics_str = format_generics(
405 self.config.item_brace_style(),
406 enum_def.variants.is_empty(),
408 mk_sp(span.lo, body_start),
410 self.buffer.push_str(&generics_str);
412 self.last_pos = body_start;
414 self.block_indent = self.block_indent.block_indent(self.config);
415 let variant_list = self.format_variant_list(enum_def, body_start, span.hi - BytePos(1));
417 Some(ref body_str) => self.buffer.push_str(body_str),
419 if contains_comment(&enum_snippet[brace_pos..]) {
420 self.format_missing_no_indent(span.hi - BytePos(1))
422 self.format_missing(span.hi - BytePos(1))
426 self.block_indent = self.block_indent.block_unindent(self.config);
428 if variant_list.is_some() || contains_comment(&enum_snippet[brace_pos..]) {
430 .push_str(&self.block_indent.to_string(self.config));
432 self.buffer.push_str("}");
433 self.last_pos = span.hi;
436 // Format the body of an enum definition
437 fn format_variant_list(
439 enum_def: &ast::EnumDef,
442 ) -> Option<String> {
443 if enum_def.variants.is_empty() {
446 let mut result = String::with_capacity(1024);
448 let indentation = self.block_indent.to_string(self.config);
449 result.push_str(&indentation);
451 let items = itemize_list(
453 enum_def.variants.iter(),
455 |f| if !f.node.attrs.is_empty() {
456 f.node.attrs[0].span.lo
461 |f| self.format_variant(f),
466 let shape = Shape::indented(self.block_indent, self.config)
469 let fmt = ListFormatting {
470 tactic: DefinitiveListTactic::Vertical,
472 trailing_separator: self.config.trailing_comma(),
474 ends_with_newline: true,
478 let list = try_opt!(write_list(items, &fmt));
479 result.push_str(&list);
484 // Variant of an enum.
485 fn format_variant(&self, field: &ast::Variant) -> Option<String> {
486 if contains_skip(&field.node.attrs) {
487 let lo = field.node.attrs[0].span.lo;
488 let span = mk_sp(lo, field.span.hi);
489 return Some(self.snippet(span));
492 let context = self.get_context();
493 let indent = self.block_indent;
494 let mut result = try_opt!(
498 .rewrite(&context, Shape::indented(indent, self.config))
500 if !result.is_empty() {
502 width: context.config.max_width(),
503 indent: self.block_indent,
504 offset: self.block_indent.alignment,
506 let missing_comment = rewrite_missing_comment_on_field(
509 field.node.attrs[field.node.attrs.len() - 1].span.hi,
512 ).unwrap_or(String::new());
513 result.push_str(&missing_comment);
516 let variant_body = match field.node.data {
517 ast::VariantData::Tuple(..) |
518 ast::VariantData::Struct(..) => {
519 // FIXME: Should limit the width, as we have a trailing comma
524 &ast::Visibility::Inherited,
529 Some(self.config.struct_variant_width()),
532 ast::VariantData::Unit(..) => {
533 let tag = if let Some(ref expr) = field.node.disr_expr {
534 format!("{} = {}", field.node.name, self.snippet(expr.span))
536 field.node.name.to_string()
541 self.config.max_width(),
542 Shape::indented(indent, self.config),
547 if let Some(variant_str) = variant_body {
548 result.push_str(&variant_str);
557 context: &RewriteContext,
560 where_span_end: Option<BytePos>,
561 ) -> Option<String> {
562 if let ast::ItemKind::Impl(_, _, _, ref generics, _, _, ref items) = item.node {
563 let mut result = String::new();
564 let ref_and_type = try_opt!(format_impl_ref_and_type(context, item, offset));
565 result.push_str(&ref_and_type);
567 let where_budget = if result.contains('\n') {
568 context.config.max_width()
573 .checked_sub(last_line_width(&result))
576 let where_clause_str = try_opt!(rewrite_where_clause(
578 &generics.where_clause,
579 context.config.item_brace_style(),
580 Shape::legacy(where_budget, offset.block_only()),
581 context.config.where_density(),
584 last_line_width(&ref_and_type) == 1,
588 if try_opt!(is_impl_single_line(
595 result.push_str(&where_clause_str);
596 if where_clause_str.contains('\n') {
597 let white_space = offset.to_string(context.config);
598 result.push_str(&format!("\n{}{{\n{}}}", &white_space, &white_space));
600 result.push_str(" {}");
605 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') {
607 let width = offset.block_indent + context.config.tab_spaces() - 1;
608 let where_indent = Indent::new(0, width);
609 result.push_str(&where_indent.to_string(context.config));
611 result.push_str(&where_clause_str);
613 match context.config.item_brace_style() {
614 BraceStyle::AlwaysNextLine => {
616 result.push_str(&offset.to_string(context.config));
618 BraceStyle::PreferSameLine => result.push(' '),
619 BraceStyle::SameLineWhere => {
620 if !where_clause_str.is_empty() {
622 result.push_str(&offset.to_string(context.config));
631 let snippet = context.snippet(item.span);
632 let open_pos = try_opt!(snippet.find_uncommented("{")) + 1;
634 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
635 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
636 visitor.block_indent = offset.block_only().block_indent(context.config);
637 visitor.last_pos = item.span.lo + BytePos(open_pos as u32);
640 visitor.visit_impl_item(item);
643 visitor.format_missing(item.span.hi - BytePos(1));
645 let inner_indent_str = visitor.block_indent.to_string(context.config);
646 let outer_indent_str = offset.block_only().to_string(context.config);
649 result.push_str(&inner_indent_str);
650 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
652 result.push_str(&outer_indent_str);
655 if result.chars().last().unwrap() == '{' {
657 result.push_str(&offset.to_string(context.config));
667 fn is_impl_single_line(
668 context: &RewriteContext,
671 where_clause_str: &str,
674 let snippet = context.snippet(item.span);
675 let open_pos = try_opt!(snippet.find_uncommented("{")) + 1;
678 context.config.impl_empty_single_line() && items.is_empty() &&
679 result.len() + where_clause_str.len() <= context.config.max_width() &&
680 !contains_comment(&snippet[open_pos..]),
684 fn format_impl_ref_and_type(
685 context: &RewriteContext,
688 ) -> Option<String> {
689 if let ast::ItemKind::Impl(
699 let mut result = String::new();
701 result.push_str(&format_visibility(&item.vis));
702 result.push_str(format_unsafety(unsafety));
703 result.push_str("impl");
705 let lo = context.codemap.span_after(item.span, "impl");
706 let hi = match *trait_ref {
707 Some(ref tr) => tr.path.span.lo,
708 None => self_ty.span.lo,
710 let shape = try_opt!(generics_shape_from_config(
712 Shape::indented(offset + last_line_width(&result), context.config),
715 let one_line_budget = try_opt!(shape.width.checked_sub(last_line_width(&result) + 2));
716 let generics_str = try_opt!(rewrite_generics_inner(
724 let polarity_str = if polarity == ast::ImplPolarity::Negative {
730 if let Some(ref trait_ref) = *trait_ref {
731 let result_len = result.len();
732 if let Some(trait_ref_str) =
742 result.push_str(&trait_ref_str);
744 let generics_str = try_opt!(rewrite_generics_inner(
751 result.push_str(&try_opt!(rewrite_trait_ref(
762 result.push_str(&generics_str);
765 // Try to put the self type in a single line.
767 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
768 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
769 // If there is no where clause adapt budget for type formatting to take space and curly
770 // brace into account.
771 match context.config.item_brace_style() {
772 BraceStyle::AlwaysNextLine => 0,
778 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
779 // 1 = space before the type.
783 .checked_sub(used_space + 1)
785 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
786 if !self_ty_str.contains('\n') {
787 if trait_ref.is_some() {
788 result.push_str(" for ");
792 result.push_str(&self_ty_str);
797 // Couldn't fit the self type on a single line, put it on a new line.
799 // Add indentation of one additional tab.
800 let new_line_offset = offset.block_indent(context.config);
801 result.push_str(&new_line_offset.to_string(context.config));
802 if trait_ref.is_some() {
803 result.push_str("for ");
805 let budget = context.config.max_width() - last_line_width(&result);
806 let type_offset = match context.config.where_style() {
807 Style::Legacy => new_line_offset + trait_ref_overhead,
808 Style::Rfc => new_line_offset,
810 result.push_str(&*try_opt!(
811 self_ty.rewrite(context, Shape::legacy(budget, type_offset))
819 fn rewrite_trait_ref(
820 context: &RewriteContext,
821 trait_ref: &ast::TraitRef,
827 ) -> Option<String> {
828 // 1 = space between generics and trait_ref
829 let used_space = 1 + polarity_str.len() +
830 if generics_str.contains('\n') {
831 last_line_width(&generics_str)
833 result_len + generics_str.len()
835 let shape = Shape::indented(offset + used_space, context.config);
836 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
837 if !(retry && trait_ref_str.contains('\n')) {
846 // We could not make enough space for trait_ref, so put it on new line.
848 let offset = offset.block_indent(context.config);
849 let shape = Shape::indented(offset, context.config);
850 let trait_ref_str = try_opt!(trait_ref.rewrite(context, shape));
854 &offset.to_string(context.config),
863 pub fn format_struct(
864 context: &RewriteContext,
867 vis: &ast::Visibility,
868 struct_def: &ast::VariantData,
869 generics: Option<&ast::Generics>,
872 one_line_width: Option<usize>,
873 ) -> Option<String> {
875 ast::VariantData::Unit(..) => Some(format_unit_struct(item_name, ident, vis)),
876 ast::VariantData::Tuple(ref fields, _) => {
888 ast::VariantData::Struct(ref fields, _) => {
889 format_struct_struct(
904 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
905 if let ast::ItemKind::Trait(unsafety, ref generics, ref type_param_bounds, ref trait_items) =
908 let mut result = String::new();
909 let header = format!(
911 format_visibility(&item.vis),
912 format_unsafety(unsafety),
916 result.push_str(&header);
918 let body_lo = context.codemap.span_after(item.span, "{");
920 let shape = Shape::indented(offset + last_line_width(&result), context.config);
921 let generics_str = try_opt!(rewrite_generics(
925 mk_sp(item.span.lo, body_lo),
927 result.push_str(&generics_str);
929 let trait_bound_str = try_opt!(rewrite_trait_bounds(
932 Shape::indented(offset, context.config),
934 // If the trait, generics, and trait bound cannot fit on the same line,
935 // put the trait bounds on an indented new line
936 if offset.width() + last_line_width(&result) + trait_bound_str.len() >
937 context.config.comment_width()
940 let trait_indent = offset.block_only().block_indent(context.config);
941 result.push_str(&trait_indent.to_string(context.config));
943 result.push_str(&trait_bound_str);
945 let has_body = !trait_items.is_empty();
947 let where_density = if (context.config.where_density() == Density::Compressed &&
948 (!result.contains('\n') ||
949 context.config.fn_args_layout() == IndentStyle::Block)) ||
950 (context.config.fn_args_layout() == IndentStyle::Block && result.is_empty()) ||
951 (context.config.where_density() == Density::CompressedIfEmpty && !has_body &&
952 !result.contains('\n'))
959 let where_budget = try_opt!(
963 .checked_sub(last_line_width(&result))
965 let where_clause_str = try_opt!(rewrite_where_clause(
967 &generics.where_clause,
968 context.config.item_brace_style(),
969 Shape::legacy(where_budget, offset.block_only()),
973 trait_bound_str.is_empty() && last_line_width(&generics_str) == 1,
976 // If the where clause cannot fit on the same line,
977 // put the where clause on a new line
978 if !where_clause_str.contains('\n') &&
979 last_line_width(&result) + where_clause_str.len() + offset.width() >
980 context.config.comment_width()
983 let width = offset.block_indent + context.config.tab_spaces() - 1;
984 let where_indent = Indent::new(0, width);
985 result.push_str(&where_indent.to_string(context.config));
987 result.push_str(&where_clause_str);
989 match context.config.item_brace_style() {
990 BraceStyle::AlwaysNextLine => {
992 result.push_str(&offset.to_string(context.config));
994 BraceStyle::PreferSameLine => result.push(' '),
995 BraceStyle::SameLineWhere => {
996 if !where_clause_str.is_empty() &&
997 (!trait_items.is_empty() || result.contains('\n'))
1000 result.push_str(&offset.to_string(context.config));
1008 let snippet = context.snippet(item.span);
1009 let open_pos = try_opt!(snippet.find_uncommented("{")) + 1;
1011 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1012 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
1013 visitor.block_indent = offset.block_only().block_indent(context.config);
1014 visitor.last_pos = item.span.lo + BytePos(open_pos as u32);
1016 for item in trait_items {
1017 visitor.visit_trait_item(item);
1020 visitor.format_missing(item.span.hi - BytePos(1));
1022 let inner_indent_str = visitor.block_indent.to_string(context.config);
1023 let outer_indent_str = offset.block_only().to_string(context.config);
1026 result.push_str(&inner_indent_str);
1027 result.push_str(trim_newlines(visitor.buffer.to_string().trim()));
1029 result.push_str(&outer_indent_str);
1030 } else if result.contains('\n') {
1041 fn format_unit_struct(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
1042 format!("{};", format_header(item_name, ident, vis))
1045 fn format_struct_struct(
1046 context: &RewriteContext,
1049 vis: &ast::Visibility,
1050 fields: &[ast::StructField],
1051 generics: Option<&ast::Generics>,
1054 one_line_width: Option<usize>,
1055 ) -> Option<String> {
1056 let mut result = String::with_capacity(1024);
1058 let header_str = format_header(item_name, ident, vis);
1059 result.push_str(&header_str);
1061 let body_lo = context.codemap.span_after(span, "{");
1063 let generics_str = match generics {
1065 try_opt!(format_generics(
1070 context.config.item_brace_style(),
1073 mk_sp(span.lo, body_lo),
1077 if context.config.item_brace_style() == BraceStyle::AlwaysNextLine &&
1080 format!("\n{}{{", offset.block_only().to_string(context.config))
1086 result.push_str(&generics_str);
1088 if fields.is_empty() {
1089 let snippet = context.snippet(mk_sp(body_lo, span.hi - BytePos(1)));
1090 if snippet.trim().is_empty() {
1092 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1094 result.push_str(&snippet.trim_right());
1096 result.push_str(&offset.to_string(context.config));
1098 result.push_str(&snippet);
1101 return Some(result);
1104 let items_str = try_opt!(rewrite_with_alignment(
1107 Shape::indented(offset, context.config),
1108 mk_sp(body_lo, span.hi),
1109 one_line_width.unwrap_or(0),
1112 if one_line_width.is_some() && !items_str.contains('\n') {
1113 Some(format!("{} {} }}", result, items_str))
1119 .block_indent(context.config)
1120 .to_string(context.config),
1122 offset.to_string(context.config)
1127 fn format_tuple_struct(
1128 context: &RewriteContext,
1131 vis: &ast::Visibility,
1132 fields: &[ast::StructField],
1133 generics: Option<&ast::Generics>,
1136 ) -> Option<String> {
1137 let mut result = String::with_capacity(1024);
1139 let header_str = format_header(item_name, ident, vis);
1140 result.push_str(&header_str);
1142 let body_lo = if fields.is_empty() {
1143 context.codemap.span_after(span, "(")
1148 let where_clause_str = match generics {
1150 let shape = Shape::indented(offset + last_line_width(&header_str), context.config);
1151 let g_span = mk_sp(span.lo, body_lo);
1152 let generics_str = try_opt!(rewrite_generics(context, generics, shape, g_span));
1153 result.push_str(&generics_str);
1155 let where_budget = try_opt!(
1159 .checked_sub(last_line_width(&result))
1161 try_opt!(rewrite_where_clause(
1163 &generics.where_clause,
1164 context.config.item_brace_style(),
1165 Shape::legacy(where_budget, offset.block_only()),
1166 Density::Compressed,
1173 None => "".to_owned(),
1176 if fields.is_empty() {
1178 let snippet = context.snippet(mk_sp(body_lo, context.codemap.span_before(span, ")")));
1179 if snippet.is_empty() {
1181 } else if snippet.trim_right_matches(&[' ', '\t'][..]).ends_with('\n') {
1182 result.push_str(&snippet.trim_right());
1184 result.push_str(&offset.to_string(context.config));
1186 result.push_str(&snippet);
1190 let (tactic, item_indent) = match context.config.fn_args_layout() {
1191 IndentStyle::Visual => {
1194 ListTactic::HorizontalVertical,
1195 offset.block_only() + result.len() + 1,
1198 IndentStyle::Block => {
1200 ListTactic::HorizontalVertical,
1201 offset.block_only().block_indent(&context.config),
1206 let item_budget = try_opt!(
1210 .checked_sub(item_indent.width() + 3)
1213 let items = itemize_list(
1218 // Include attributes and doc comments, if present
1219 if !field.attrs.is_empty() {
1220 field.attrs[0].span.lo
1225 |field| field.ty.span.hi,
1227 rewrite_struct_field(context, field, Shape::legacy(item_budget, item_indent), 0)
1229 context.codemap.span_after(span, "("),
1232 let body_budget = try_opt!(
1236 .checked_sub(offset.block_only().width() + result.len() + 3)
1238 let body = try_opt!(list_helper(
1240 // TODO budget is wrong in block case
1241 Shape::legacy(body_budget, item_indent),
1246 if context.config.fn_args_layout() == IndentStyle::Visual || !body.contains('\n') {
1248 if context.config.spaces_within_parens() && body.len() > 0 {
1252 result.push_str(&body);
1254 if context.config.spaces_within_parens() && body.len() > 0 {
1259 result.push_str("(\n");
1260 result.push_str(&item_indent.to_string(&context.config));
1261 result.push_str(&body);
1263 result.push_str(&offset.block_only().to_string(&context.config));
1268 if !where_clause_str.is_empty() && !where_clause_str.contains('\n') &&
1269 (result.contains('\n') ||
1270 offset.block_indent + result.len() + where_clause_str.len() + 1 >
1271 context.config.max_width())
1273 // We need to put the where clause on a new line, but we didn't
1274 // know that earlier, so the where clause will not be indented properly.
1276 result.push_str(&(offset.block_only() + (context.config.tab_spaces() - 1))
1277 .to_string(context.config));
1279 result.push_str(&where_clause_str);
1284 pub fn rewrite_type_alias(
1285 context: &RewriteContext,
1289 generics: &ast::Generics,
1290 vis: &ast::Visibility,
1292 ) -> Option<String> {
1293 let mut result = String::new();
1295 result.push_str(&format_visibility(vis));
1296 result.push_str("type ");
1297 result.push_str(&ident.to_string());
1300 let shape = try_opt!(Shape::indented(indent + result.len(), context.config).sub_width(2));
1301 let g_span = mk_sp(context.codemap.span_after(span, "type"), ty.span.lo);
1302 let generics_str = try_opt!(rewrite_generics(context, generics, shape, g_span));
1303 result.push_str(&generics_str);
1305 let where_budget = try_opt!(
1309 .checked_sub(last_line_width(&result))
1311 let where_clause_str = try_opt!(rewrite_where_clause(
1313 &generics.where_clause,
1314 context.config.item_brace_style(),
1315 Shape::legacy(where_budget, indent),
1316 context.config.where_density(),
1322 result.push_str(&where_clause_str);
1323 result.push_str(" = ");
1325 let line_width = last_line_width(&result);
1326 // This checked_sub may fail as the extra space after '=' is not taken into account
1327 // In that case the budget is set to 0 which will make ty.rewrite retry on a new line
1328 let budget = context
1331 .checked_sub(indent.width() + line_width + ";".len())
1333 let type_indent = indent + line_width;
1334 // Try to fit the type on the same line
1335 let ty_str = try_opt!(
1336 ty.rewrite(context, Shape::legacy(budget, type_indent))
1338 // The line was too short, try to put the type on the next line
1340 // Remove the space after '='
1342 let type_indent = indent.block_indent(context.config);
1344 result.push_str(&type_indent.to_string(context.config));
1345 let budget = try_opt!(
1349 .checked_sub(type_indent.width() + ";".len())
1351 ty.rewrite(context, Shape::legacy(budget, type_indent))
1354 result.push_str(&ty_str);
1355 result.push_str(";");
1359 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1361 if config.space_before_type_annotation() {
1366 if config.space_after_type_annotation_colon() {
1374 fn rewrite_missing_comment_on_field(
1375 context: &RewriteContext,
1379 result: &mut String,
1380 ) -> Option<String> {
1381 let possibly_comment_snippet = context.snippet(mk_sp(lo, hi));
1382 let newline_index = possibly_comment_snippet.find('\n');
1383 let comment_index = possibly_comment_snippet.find('/');
1384 match (newline_index, comment_index) {
1385 (Some(i), Some(j)) if i > j => result.push(' '),
1388 result.push_str(&shape.indent.to_string(context.config));
1391 let trimmed = possibly_comment_snippet.trim();
1392 if trimmed.is_empty() {
1395 rewrite_comment(trimmed, false, shape, context.config).map(|s| {
1396 format!("{}\n{}", s, shape.indent.to_string(context.config))
1401 pub fn rewrite_struct_field_prefix(
1402 context: &RewriteContext,
1403 field: &ast::StructField,
1405 ) -> Option<String> {
1406 let vis = format_visibility(&field.vis);
1407 let mut attr_str = try_opt!(
1410 .rewrite(context, Shape::indented(shape.indent, context.config))
1412 // Try format missing comments after attributes
1413 let missing_comment = if !field.attrs.is_empty() {
1414 rewrite_missing_comment_on_field(
1417 field.attrs[field.attrs.len() - 1].span.hi,
1420 ).unwrap_or(String::new())
1425 let type_annotation_spacing = type_annotation_spacing(context.config);
1426 Some(match field.ident {
1434 type_annotation_spacing.0
1437 None => format!("{}{}{}", attr_str, missing_comment, vis),
1441 fn rewrite_struct_field_type(
1442 context: &RewriteContext,
1443 last_line_width: usize,
1444 field: &ast::StructField,
1447 ) -> Option<String> {
1448 let ty_shape = try_opt!(shape.offset_left(last_line_width + spacing.len()));
1451 .rewrite(context, ty_shape)
1452 .map(|ty| format!("{}{}", spacing, ty))
1456 pub fn rewrite_struct_field(
1457 context: &RewriteContext,
1458 field: &ast::StructField,
1460 lhs_max_width: usize,
1461 ) -> Option<String> {
1462 if contains_skip(&field.attrs) {
1463 let span = context.snippet(mk_sp(field.attrs[0].span.lo, field.span.hi));
1464 return wrap_str(span, context.config.max_width(), shape);
1467 let type_annotation_spacing = type_annotation_spacing(context.config);
1468 let prefix = try_opt!(rewrite_struct_field_prefix(context, field, shape));
1470 // Try to put everything on a single line.
1471 let last_line_width = last_line_width(&prefix);
1472 let mut spacing = String::from(if field.ident.is_some() {
1473 type_annotation_spacing.1
1477 let lhs_offset = lhs_max_width.checked_sub(last_line_width).unwrap_or(0);
1478 for _ in 0..lhs_offset {
1481 let ty_rewritten = rewrite_struct_field_type(context, last_line_width, field, &spacing, shape);
1482 if let Some(ref ty) = ty_rewritten {
1483 if !ty.contains('\n') {
1484 return Some(prefix + &ty);
1488 // We must use multiline.
1489 let type_offset = shape.indent.block_indent(context.config);
1490 let rewrite_type_in_next_line = || {
1493 .rewrite(context, Shape::indented(type_offset, context.config))
1496 match ty_rewritten {
1497 // If we start from the next line and type fits in a single line, then do so.
1499 match rewrite_type_in_next_line() {
1500 Some(ref new_ty) if !new_ty.contains('\n') => {
1504 type_offset.to_string(&context.config),
1508 _ => Some(prefix + &ty),
1512 let ty = try_opt!(rewrite_type_in_next_line());
1516 type_offset.to_string(&context.config),
1523 pub fn rewrite_static(
1525 vis: &ast::Visibility,
1528 mutability: ast::Mutability,
1529 expr_opt: Option<&ptr::P<ast::Expr>>,
1532 context: &RewriteContext,
1533 ) -> Option<String> {
1534 let colon = colon_spaces(
1535 context.config.space_before_type_annotation(),
1536 context.config.space_after_type_annotation_colon(),
1538 let prefix = format!(
1540 format_visibility(vis),
1542 format_mutability(mutability),
1547 let ty_str = try_opt!(ty.rewrite(
1550 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)
1554 if let Some(expr) = expr_opt {
1555 let lhs = format!("{}{} =", prefix, ty_str);
1557 let remaining_width = context.config.max_width() - offset.block_indent - 1;
1562 Shape::legacy(remaining_width, offset.block_only()),
1564 recover_comment_removed(res, span, context, Shape::indented(offset, context.config))
1566 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1568 Some(format!("{}{};", prefix, ty_str))
1572 pub fn rewrite_associated_type(
1574 ty_opt: Option<&ptr::P<ast::Ty>>,
1575 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1576 context: &RewriteContext,
1578 ) -> Option<String> {
1579 let prefix = format!("type {}", ident);
1581 let type_bounds_str = if let Some(ty_param_bounds) = ty_param_bounds_opt {
1582 let shape = Shape::indented(indent, context.config);
1583 let bounds: &[_] = ty_param_bounds;
1584 let bound_str = try_opt!(
1587 .map(|ty_bound| ty_bound.rewrite(context, shape))
1588 .collect::<Option<Vec<_>>>()
1590 if bounds.len() > 0 {
1591 format!(": {}", join_bounds(context, shape, &bound_str))
1599 if let Some(ty) = ty_opt {
1600 let ty_str = try_opt!(ty.rewrite(
1603 context.config.max_width() - indent.block_indent - prefix.len() - 2,
1604 indent.block_only(),
1607 Some(format!("{} = {};", prefix, ty_str))
1609 Some(format!("{}{};", prefix, type_bounds_str))
1613 pub fn rewrite_associated_impl_type(
1615 defaultness: ast::Defaultness,
1616 ty_opt: Option<&ptr::P<ast::Ty>>,
1617 ty_param_bounds_opt: Option<&ast::TyParamBounds>,
1618 context: &RewriteContext,
1620 ) -> Option<String> {
1621 let result = try_opt!(rewrite_associated_type(
1624 ty_param_bounds_opt,
1630 ast::Defaultness::Default => Some(format!("default {}", result)),
1635 impl Rewrite for ast::FunctionRetTy {
1636 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1638 ast::FunctionRetTy::Default(_) => Some(String::new()),
1639 ast::FunctionRetTy::Ty(ref ty) => {
1640 let inner_width = try_opt!(shape.width.checked_sub(3));
1641 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1642 .map(|r| format!("-> {}", r))
1648 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1650 ast::TyKind::Infer => {
1651 let original = context.snippet(ty.span);
1658 impl Rewrite for ast::Arg {
1659 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1660 if is_named_arg(self) {
1661 let mut result = try_opt!(
1663 .rewrite(context, Shape::legacy(shape.width, shape.indent))
1666 if !is_empty_infer(context, &*self.ty) {
1667 if context.config.space_before_type_annotation() {
1668 result.push_str(" ");
1670 result.push_str(":");
1671 if context.config.space_after_type_annotation_colon() {
1672 result.push_str(" ");
1674 let max_width = try_opt!(shape.width.checked_sub(result.len()));
1675 let ty_str = try_opt!(self.ty.rewrite(
1677 Shape::legacy(max_width, shape.indent + result.len()),
1679 result.push_str(&ty_str);
1684 self.ty.rewrite(context, shape)
1689 fn rewrite_explicit_self(
1690 explicit_self: &ast::ExplicitSelf,
1692 context: &RewriteContext,
1693 ) -> Option<String> {
1694 match explicit_self.node {
1695 ast::SelfKind::Region(lt, m) => {
1696 let mut_str = format_mutability(m);
1699 let lifetime_str = try_opt!(l.rewrite(
1701 Shape::legacy(context.config.max_width(), Indent::empty()),
1703 Some(format!("&{} {}self", lifetime_str, mut_str))
1705 None => Some(format!("&{}self", mut_str)),
1708 ast::SelfKind::Explicit(ref ty, _) => {
1709 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1711 let mutability = explicit_self_mutability(&args[0]);
1712 let type_str = try_opt!(ty.rewrite(
1714 Shape::legacy(context.config.max_width(), Indent::empty()),
1719 format_mutability(mutability),
1723 ast::SelfKind::Value(_) => {
1724 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1726 let mutability = explicit_self_mutability(&args[0]);
1728 Some(format!("{}self", format_mutability(mutability)))
1733 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1734 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1735 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1736 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1743 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1744 if is_named_arg(arg) {
1751 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1753 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi,
1754 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi,
1755 _ => arg.ty.span.hi,
1759 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1760 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1761 ident.node != symbol::keywords::Invalid.ident()
1767 fn span_for_return(ret: &ast::FunctionRetTy) -> Span {
1769 ast::FunctionRetTy::Default(ref span) => span.clone(),
1770 ast::FunctionRetTy::Ty(ref ty) => ty.span,
1774 fn span_for_ty_param(ty: &ast::TyParam) -> Span {
1775 // Note that ty.span is the span for ty.ident, not the whole item.
1776 let lo = if ty.attrs.is_empty() {
1781 if let Some(ref def) = ty.default {
1782 return mk_sp(lo, def.span.hi);
1784 if ty.bounds.is_empty() {
1785 return mk_sp(lo, ty.span.hi);
1787 let hi = match ty.bounds[ty.bounds.len() - 1] {
1788 ast::TyParamBound::TraitTyParamBound(ref ptr, _) => ptr.span.hi,
1789 ast::TyParamBound::RegionTyParamBound(ref l) => l.span.hi,
1794 fn span_for_where_pred(pred: &ast::WherePredicate) -> Span {
1796 ast::WherePredicate::BoundPredicate(ref p) => p.span,
1797 ast::WherePredicate::RegionPredicate(ref p) => p.span,
1798 ast::WherePredicate::EqPredicate(ref p) => p.span,
1802 // Return type is (result, force_new_line_for_brace)
1804 context: &RewriteContext,
1808 generics: &ast::Generics,
1809 unsafety: ast::Unsafety,
1810 constness: ast::Constness,
1811 defaultness: ast::Defaultness,
1813 vis: &ast::Visibility,
1815 newline_brace: bool,
1818 ) -> Option<(String, bool)> {
1819 let mut force_new_line_for_brace = false;
1821 let where_clause = &generics.where_clause;
1823 let mut result = String::with_capacity(1024);
1824 // Vis unsafety abi.
1825 result.push_str(&*format_visibility(vis));
1827 if let ast::Defaultness::Default = defaultness {
1828 result.push_str("default ");
1831 if let ast::Constness::Const = constness {
1832 result.push_str("const ");
1835 result.push_str(::utils::format_unsafety(unsafety));
1837 if abi != abi::Abi::Rust {
1838 result.push_str(&::utils::format_abi(
1840 context.config.force_explicit_abi(),
1845 result.push_str("fn ");
1846 result.push_str(&ident.to_string());
1849 let overhead = if has_braces && !newline_brace {
1856 let shape = try_opt!(
1857 Shape::indented(indent + last_line_width(&result), context.config).sub_width(overhead)
1859 let g_span = mk_sp(span.lo, span_for_return(&fd.output).lo);
1860 let generics_str = try_opt!(rewrite_generics(context, generics, shape, g_span));
1861 result.push_str(&generics_str);
1863 let snuggle_angle_bracket = generics_str
1866 .map_or(false, |l| l.trim_left().len() == 1);
1868 // Note that the width and indent don't really matter, we'll re-layout the
1869 // return type later anyway.
1870 let ret_str = try_opt!(
1872 .rewrite(&context, Shape::indented(indent, context.config))
1875 let multi_line_ret_str = ret_str.contains('\n');
1876 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1879 let (mut one_line_budget, mut multi_line_budget, mut arg_indent) =
1880 try_opt!(compute_budgets_for_args(
1889 if context.config.fn_args_layout() == IndentStyle::Block {
1890 arg_indent = indent.block_indent(context.config);
1892 multi_line_budget = context.config.max_width() - (arg_indent.width() + 1);
1896 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1902 // Check if vertical layout was forced.
1903 if one_line_budget == 0 {
1904 if snuggle_angle_bracket {
1907 if context.config.fn_args_paren_newline() {
1909 result.push_str(&arg_indent.to_string(context.config));
1910 if context.config.fn_args_layout() == IndentStyle::Visual {
1911 arg_indent = arg_indent + 1; // extra space for `(`
1915 result.push_str("(");
1916 if context.config.fn_args_layout() == IndentStyle::Visual {
1918 result.push_str(&arg_indent.to_string(context.config));
1925 if context.config.spaces_within_parens() && fd.inputs.len() > 0 && result.ends_with('(') {
1929 if multi_line_ret_str {
1930 one_line_budget = 0;
1933 // A conservative estimation, to goal is to be over all parens in generics
1934 let args_start = generics
1937 .map_or(span.lo, |tp| end_typaram(tp));
1938 let args_span = mk_sp(
1939 context.codemap.span_after(mk_sp(args_start, span.hi), "("),
1940 span_for_return(&fd.output).lo,
1942 let arg_str = try_opt!(rewrite_args(
1945 fd.get_self().as_ref(),
1952 generics_str.contains('\n'),
1955 let multi_line_arg_str =
1956 arg_str.contains('\n') || arg_str.chars().last().map_or(false, |c| c == ',');
1958 let put_args_in_block = match context.config.fn_args_layout() {
1959 IndentStyle::Block => multi_line_arg_str || generics_str.contains('\n'),
1961 } && !fd.inputs.is_empty();
1963 let mut args_last_line_contains_comment = false;
1964 if put_args_in_block {
1965 arg_indent = indent.block_indent(context.config);
1967 result.push_str(&arg_indent.to_string(context.config));
1968 result.push_str(&arg_str);
1970 result.push_str(&indent.to_string(context.config));
1973 result.push_str(&arg_str);
1974 if context.config.spaces_within_parens() && fd.inputs.len() > 0 {
1977 // If the last line of args contains comment, we cannot put the closing paren
1978 // on the same line.
1982 .map_or(false, |last_line| last_line.contains("//"))
1984 args_last_line_contains_comment = true;
1986 result.push_str(&arg_indent.to_string(context.config));
1992 if !ret_str.is_empty() {
1993 let ret_should_indent = match context.config.fn_args_layout() {
1994 // If our args are block layout then we surely must have space.
1995 IndentStyle::Block if put_args_in_block => false,
1997 // If we've already gone multi-line, or the return type would push over the max
1998 // width, then put the return type on a new line. With the +1 for the signature
1999 // length an additional space between the closing parenthesis of the argument and
2000 // the arrow '->' is considered.
2001 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
2003 // If there is no where clause, take into account the space after the return type
2005 if where_clause.predicates.is_empty() {
2009 let overlong_sig = sig_length > context.config.max_width();
2011 (!args_last_line_contains_comment) &&
2012 (result.contains('\n') || multi_line_ret_str || overlong_sig)
2015 let ret_indent = if ret_should_indent {
2016 let indent = match context.config.fn_return_indent() {
2017 ReturnIndent::WithWhereClause => indent + 4,
2018 // Aligning with non-existent args looks silly.
2019 _ if arg_str.is_empty() => {
2020 force_new_line_for_brace = true;
2023 // FIXME: we might want to check that using the arg indent
2024 // doesn't blow our budget, and if it does, then fallback to
2025 // the where clause indent.
2030 result.push_str(&indent.to_string(context.config));
2034 Indent::new(indent.block_indent, last_line_width(&result))
2037 if multi_line_ret_str || ret_should_indent {
2038 // Now that we know the proper indent and width, we need to
2039 // re-layout the return type.
2040 let ret_str = try_opt!(
2042 .rewrite(context, Shape::indented(ret_indent, context.config))
2044 result.push_str(&ret_str);
2046 result.push_str(&ret_str);
2049 // Comment between return type and the end of the decl.
2050 let snippet_lo = fd.output.span().hi;
2051 if where_clause.predicates.is_empty() {
2052 let snippet_hi = span.hi;
2053 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2054 // Try to preserve the layout of the original snippet.
2055 let original_starts_with_newline = snippet
2057 .map_or(false, |i| snippet[i..].starts_with('\n'));
2058 let original_ends_with_newline = snippet
2059 .rfind(|c| c != ' ')
2060 .map_or(false, |i| snippet[i..].ends_with('\n'));
2061 let snippet = snippet.trim();
2062 if !snippet.is_empty() {
2063 result.push(if original_starts_with_newline {
2068 result.push_str(snippet);
2069 if original_ends_with_newline {
2070 force_new_line_for_brace = true;
2074 // FIXME it would be nice to catch comments between the return type
2075 // and the where clause, but we don't have a span for the where
2080 let should_compress_where = match context.config.where_density() {
2081 Density::Compressed => !result.contains('\n') || put_args_in_block,
2082 Density::CompressedIfEmpty => !has_body && !result.contains('\n'),
2084 } || (put_args_in_block && ret_str.is_empty());
2086 if where_clause.predicates.len() == 1 && should_compress_where {
2087 let budget = try_opt!(
2091 .checked_sub(last_line_width(&result))
2093 if let Some(where_clause_str) =
2094 rewrite_where_clause(
2097 context.config.fn_brace_style(),
2098 Shape::legacy(budget, indent),
2099 Density::Compressed,
2102 put_args_in_block && ret_str.is_empty(),
2105 if !where_clause_str.contains('\n') {
2106 if last_line_width(&result) + where_clause_str.len() > context.config.max_width() {
2110 result.push_str(&where_clause_str);
2112 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2113 return Some((result, force_new_line_for_brace));
2118 let where_clause_str = try_opt!(rewrite_where_clause(
2121 context.config.fn_brace_style(),
2122 Shape::indented(indent, context.config),
2126 put_args_in_block && ret_str.is_empty(),
2130 result.push_str(&where_clause_str);
2132 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2133 return Some((result, force_new_line_for_brace));
2136 fn last_line_contains_single_line_comment(s: &str) -> bool {
2137 s.lines().last().map_or(false, |l| l.contains("//"))
2141 context: &RewriteContext,
2143 explicit_self: Option<&ast::ExplicitSelf>,
2144 one_line_budget: usize,
2145 multi_line_budget: usize,
2150 generics_str_contains_newline: bool,
2151 ) -> Option<String> {
2152 let mut arg_item_strs = try_opt!(
2155 arg.rewrite(&context, Shape::legacy(multi_line_budget, arg_indent))
2157 .collect::<Option<Vec<_>>>()
2160 // Account for sugary self.
2161 // FIXME: the comment for the self argument is dropped. This is blocked
2162 // on rust issue #27522.
2163 let min_args = explicit_self
2164 .and_then(|explicit_self| {
2165 rewrite_explicit_self(explicit_self, args, context)
2167 .map_or(1, |self_str| {
2168 arg_item_strs[0] = self_str;
2172 // Comments between args.
2173 let mut arg_items = Vec::new();
2175 arg_items.push(ListItem::from_str(""));
2178 // FIXME(#21): if there are no args, there might still be a comment, but
2179 // without spans for the comment or parens, there is no chance of
2180 // getting it right. You also don't get to put a comment on self, unless
2182 if args.len() >= min_args || variadic {
2183 let comment_span_start = if min_args == 2 {
2184 let second_arg_start = if arg_has_pattern(&args[1]) {
2189 let reduced_span = mk_sp(span.lo, second_arg_start);
2191 context.codemap.span_after_last(reduced_span, ",")
2196 enum ArgumentKind<'a> {
2197 Regular(&'a ast::Arg),
2201 let variadic_arg = if variadic {
2202 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi, span.hi);
2203 let variadic_start = context.codemap.span_after(variadic_span, "...") - BytePos(3);
2204 Some(ArgumentKind::Variadic(variadic_start))
2209 let more_items = itemize_list(
2211 args[min_args - 1..]
2213 .map(ArgumentKind::Regular)
2214 .chain(variadic_arg),
2217 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2218 ArgumentKind::Variadic(start) => start,
2221 ArgumentKind::Regular(arg) => arg.ty.span.hi,
2222 ArgumentKind::Variadic(start) => start + BytePos(3),
2225 ArgumentKind::Regular(..) => None,
2226 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2232 arg_items.extend(more_items);
2235 let fits_in_one_line = !generics_str_contains_newline &&
2236 (arg_items.len() == 0 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2238 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2239 item.item = Some(arg);
2242 let last_line_ends_with_comment = arg_items
2245 .and_then(|item| item.post_comment.as_ref())
2246 .map_or(false, |s| s.trim().starts_with("//"));
2248 let (indent, trailing_comma, end_with_newline) = match context.config.fn_args_layout() {
2249 IndentStyle::Block if fits_in_one_line => {
2251 indent.block_indent(context.config),
2252 SeparatorTactic::Never,
2256 IndentStyle::Block => {
2258 indent.block_indent(context.config),
2259 context.config.trailing_comma(),
2263 IndentStyle::Visual if last_line_ends_with_comment => {
2264 (arg_indent, context.config.trailing_comma(), true)
2266 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never, false),
2269 let tactic = definitive_tactic(
2271 context.config.fn_args_density().to_list_tactic(),
2274 let budget = match tactic {
2275 DefinitiveListTactic::Horizontal => one_line_budget,
2276 _ => multi_line_budget,
2279 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2281 let fmt = ListFormatting {
2284 trailing_separator: if variadic {
2285 SeparatorTactic::Never
2289 shape: Shape::legacy(budget, indent),
2290 ends_with_newline: end_with_newline,
2291 config: context.config,
2294 write_list(&arg_items, &fmt)
2297 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2298 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2299 ident.node != symbol::keywords::Invalid.ident()
2305 fn compute_budgets_for_args(
2306 context: &RewriteContext,
2310 newline_brace: bool,
2312 ) -> Option<((usize, usize, Indent))> {
2314 "compute_budgets_for_args {} {:?}, {}, {}",
2320 // Try keeping everything on the same line.
2321 if !result.contains('\n') {
2322 // 2 = `()`, 3 = `() `, space is before ret_string.
2323 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2324 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2334 let one_line_budget = context
2337 .checked_sub(used_space)
2340 if one_line_budget > 0 {
2342 let multi_line_overhead =
2343 indent.width() + result.len() + if newline_brace { 2 } else { 4 };
2344 let multi_line_budget =
2345 try_opt!(context.config.max_width().checked_sub(multi_line_overhead));
2350 indent + result.len() + 1,
2355 // Didn't work. we must force vertical layout and put args on a newline.
2356 let new_indent = indent.block_indent(context.config);
2357 // Account for `)` and possibly ` {`.
2358 let used_space = new_indent.width() + if ret_str_len == 0 { 1 } else { 3 };
2359 let max_space = try_opt!(context.config.max_width().checked_sub(used_space));
2360 Some((0, max_space, new_indent))
2363 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2364 match config.fn_brace_style() {
2365 BraceStyle::AlwaysNextLine => true,
2366 BraceStyle::SameLineWhere if !where_clause.predicates.is_empty() => true,
2371 fn rewrite_generics(
2372 context: &RewriteContext,
2373 generics: &ast::Generics,
2376 ) -> Option<String> {
2377 let g_shape = try_opt!(generics_shape_from_config(context.config, shape, 0));
2378 let one_line_width = try_opt!(shape.width.checked_sub(2));
2379 rewrite_generics_inner(context, generics, g_shape, one_line_width, span).or_else(|| {
2380 rewrite_generics_inner(context, generics, g_shape, 0, span)
2384 fn rewrite_generics_inner(
2385 context: &RewriteContext,
2386 generics: &ast::Generics,
2388 one_line_width: usize,
2390 ) -> Option<String> {
2391 // FIXME: convert bounds to where clauses where they get too big or if
2392 // there is a where clause at all.
2393 let lifetimes: &[_] = &generics.lifetimes;
2394 let tys: &[_] = &generics.ty_params;
2395 if lifetimes.is_empty() && tys.is_empty() {
2396 return Some(String::new());
2399 // Strings for the generics.
2400 let lt_strs = lifetimes.iter().map(|lt| lt.rewrite(context, shape));
2401 let ty_strs = tys.iter().map(|ty_param| ty_param.rewrite(context, shape));
2403 // Extract comments between generics.
2404 let lt_spans = lifetimes.iter().map(|l| {
2405 let hi = if l.bounds.is_empty() {
2408 l.bounds[l.bounds.len() - 1].span.hi
2410 mk_sp(l.lifetime.span.lo, hi)
2412 let ty_spans = tys.iter().map(span_for_ty_param);
2414 let items = itemize_list(
2416 lt_spans.chain(ty_spans).zip(lt_strs.chain(ty_strs)),
2420 // FIXME: don't clone
2421 |&(_, ref str)| str.clone(),
2422 context.codemap.span_after(span, "<"),
2425 format_generics_item_list(context, items, shape, one_line_width)
2428 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2429 match config.generics_indent() {
2430 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2431 IndentStyle::Block => {
2435 .block_indent(config.tab_spaces())
2436 .with_max_width(config)
2442 pub fn format_generics_item_list<I>(
2443 context: &RewriteContext,
2446 one_line_budget: usize,
2449 I: Iterator<Item = ListItem>,
2451 let item_vec = items.collect::<Vec<_>>();
2453 let fmt = ListFormatting {
2454 tactic: definitive_tactic(&item_vec, ListTactic::HorizontalVertical, one_line_budget),
2456 trailing_separator: if context.config.generics_indent() == IndentStyle::Visual {
2457 SeparatorTactic::Never
2459 context.config.trailing_comma()
2462 ends_with_newline: false,
2463 config: context.config,
2466 let list_str = try_opt!(write_list(&item_vec, &fmt));
2468 Some(wrap_generics_with_angle_brackets(
2475 pub fn wrap_generics_with_angle_brackets(
2476 context: &RewriteContext,
2478 list_offset: Indent,
2480 if context.config.generics_indent() == IndentStyle::Block &&
2481 (list_str.contains('\n') || list_str.ends_with(','))
2485 list_offset.to_string(context.config),
2488 .block_unindent(context.config)
2489 .to_string(context.config)
2491 } else if context.config.spaces_within_angle_brackets() {
2492 format!("< {} >", list_str)
2494 format!("<{}>", list_str)
2498 fn rewrite_trait_bounds(
2499 context: &RewriteContext,
2500 type_param_bounds: &ast::TyParamBounds,
2502 ) -> Option<String> {
2503 let bounds: &[_] = type_param_bounds;
2505 if bounds.is_empty() {
2506 return Some(String::new());
2508 let bound_str = try_opt!(
2511 .map(|ty_bound| ty_bound.rewrite(&context, shape))
2512 .collect::<Option<Vec<_>>>()
2514 Some(format!(": {}", join_bounds(context, shape, &bound_str)))
2517 fn rewrite_where_clause_rfc_style(
2518 context: &RewriteContext,
2519 where_clause: &ast::WhereClause,
2522 suppress_comma: bool,
2523 // where clause can be kept on the current line.
2525 span_end: Option<BytePos>,
2526 ) -> Option<String> {
2527 let block_shape = shape.block().with_max_width(context.config);
2529 let starting_newline = if snuggle {
2532 "\n".to_owned() + &block_shape.indent.to_string(context.config)
2535 let clause_shape = block_shape.block_indent(context.config.tab_spaces());
2536 // each clause on one line, trailing comma (except if suppress_comma)
2537 let span_start = span_for_where_pred(&where_clause.predicates[0]).lo;
2538 // If we don't have the start of the next span, then use the end of the
2539 // predicates, but that means we miss comments.
2540 let len = where_clause.predicates.len();
2541 let end_of_preds = span_for_where_pred(&where_clause.predicates[len - 1]).hi;
2542 let span_end = span_end.unwrap_or(end_of_preds);
2543 let items = itemize_list(
2545 where_clause.predicates.iter(),
2547 |pred| span_for_where_pred(pred).lo,
2548 |pred| span_for_where_pred(pred).hi,
2549 |pred| pred.rewrite(context, block_shape),
2553 let comma_tactic = if suppress_comma {
2554 SeparatorTactic::Never
2556 context.config.trailing_comma()
2559 let fmt = ListFormatting {
2560 tactic: DefinitiveListTactic::Vertical,
2562 trailing_separator: comma_tactic,
2563 shape: clause_shape,
2564 ends_with_newline: true,
2565 config: context.config,
2567 let preds_str = try_opt!(write_list(items, &fmt));
2572 clause_shape.indent.to_string(context.config),
2577 fn rewrite_where_clause(
2578 context: &RewriteContext,
2579 where_clause: &ast::WhereClause,
2580 brace_style: BraceStyle,
2584 suppress_comma: bool,
2586 span_end: Option<BytePos>,
2587 ) -> Option<String> {
2588 if where_clause.predicates.is_empty() {
2589 return Some(String::new());
2592 if context.config.where_style() == Style::Rfc {
2593 return rewrite_where_clause_rfc_style(
2604 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2606 let offset = match context.config.where_pred_indent() {
2607 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2608 // 6 = "where ".len()
2609 IndentStyle::Visual => shape.indent + extra_indent + 6,
2611 // FIXME: if where_pred_indent != Visual, then the budgets below might
2612 // be out by a char or two.
2614 let budget = context.config.max_width() - offset.width();
2615 let span_start = span_for_where_pred(&where_clause.predicates[0]).lo;
2616 // If we don't have the start of the next span, then use the end of the
2617 // predicates, but that means we miss comments.
2618 let len = where_clause.predicates.len();
2619 let end_of_preds = span_for_where_pred(&where_clause.predicates[len - 1]).hi;
2620 let span_end = span_end.unwrap_or(end_of_preds);
2621 let items = itemize_list(
2623 where_clause.predicates.iter(),
2625 |pred| span_for_where_pred(pred).lo,
2626 |pred| span_for_where_pred(pred).hi,
2627 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2631 let item_vec = items.collect::<Vec<_>>();
2632 // FIXME: we don't need to collect here if the where_layout isn't
2633 // HorizontalVertical.
2634 let tactic = definitive_tactic(&item_vec, context.config.where_layout(), budget);
2636 let mut comma_tactic = context.config.trailing_comma();
2637 // Kind of a hack because we don't usually have trailing commas in where clauses.
2638 if comma_tactic == SeparatorTactic::Vertical || suppress_comma {
2639 comma_tactic = SeparatorTactic::Never;
2642 let fmt = ListFormatting {
2645 trailing_separator: comma_tactic,
2646 shape: Shape::legacy(budget, offset),
2647 ends_with_newline: true,
2648 config: context.config,
2650 let preds_str = try_opt!(write_list(&item_vec, &fmt));
2652 let end_length = if terminator == "{" {
2653 // If the brace is on the next line we don't need to count it otherwise it needs two
2656 BraceStyle::AlwaysNextLine |
2657 BraceStyle::SameLineWhere => 0,
2658 BraceStyle::PreferSameLine => 2,
2660 } else if terminator == "=" {
2665 if density == Density::Tall || preds_str.contains('\n') ||
2666 shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2670 (shape.indent + extra_indent).to_string(context.config),
2674 Some(format!(" where {}", preds_str))
2678 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2679 format!("{}{}{}", format_visibility(vis), item_name, ident)
2683 context: &RewriteContext,
2684 generics: &ast::Generics,
2687 brace_style: BraceStyle,
2688 force_same_line_brace: bool,
2691 ) -> Option<String> {
2692 let shape = Shape::indented(offset, context.config);
2693 let mut result = try_opt!(rewrite_generics(context, generics, shape, span));
2695 if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2696 let budget = try_opt!(
2700 .checked_sub(last_line_width(&result))
2702 let where_clause_str = try_opt!(rewrite_where_clause(
2704 &generics.where_clause,
2706 Shape::legacy(budget, offset.block_only()),
2710 trimmed_last_line_width(&result) == 1,
2713 result.push_str(&where_clause_str);
2714 let same_line_brace = force_same_line_brace ||
2715 (generics.where_clause.predicates.is_empty() && trimmed_last_line_width(&result) == 1);
2716 if !same_line_brace &&
2717 (brace_style == BraceStyle::SameLineWhere ||
2718 brace_style == BraceStyle::AlwaysNextLine)
2721 result.push_str(&offset.block_only().to_string(context.config));
2725 result.push_str(opener);
2727 if force_same_line_brace || trimmed_last_line_width(&result) == 1 ||
2728 brace_style != BraceStyle::AlwaysNextLine
2733 result.push_str(&offset.block_only().to_string(context.config));
2735 result.push_str(opener);