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.
13 use syntax::{ast, visit};
14 use syntax::attr::HasAttrs;
15 use syntax::codemap::{self, BytePos, CodeMap, Pos, Span};
16 use syntax::parse::ParseSess;
18 use codemap::{LineRangeUtils, SpanUtils};
19 use comment::{combine_strs_with_missing_comments, contains_comment, CodeCharKind,
20 CommentCodeSlices, FindUncommented};
21 use comment::rewrite_comment;
22 use config::{BraceStyle, Config};
23 use expr::rewrite_literal;
24 use items::{format_impl, format_trait, format_trait_alias, rewrite_associated_impl_type,
25 rewrite_associated_type, rewrite_type_alias, FnSig, StaticParts, StructParts};
26 use lists::{itemize_list, write_list, DefinitiveListTactic, ListFormatting, SeparatorPlace,
28 use macros::{rewrite_macro, rewrite_macro_def, MacroPosition};
30 use rewrite::{Rewrite, RewriteContext};
31 use shape::{Indent, Shape};
33 use utils::{self, contains_skip, count_newlines, inner_attributes, mk_sp, ptr_vec_to_ref_vec};
35 /// Returns attributes that are within `outer_span`.
36 pub fn filter_inline_attrs(attrs: &[ast::Attribute], outer_span: Span) -> Vec<ast::Attribute> {
39 .filter(|a| outer_span.lo() <= a.span.lo() && a.span.hi() <= outer_span.hi())
44 /// Returns true for `mod foo;`, false for `mod foo { .. }`.
45 fn is_mod_decl(item: &ast::Item) -> bool {
47 ast::ItemKind::Mod(ref m) => m.inner.hi() != item.span.hi(),
52 /// Returns true for `mod foo;` without any inline attributes.
53 /// We cannot reorder modules with attributes because doing so can break the code.
54 /// e.g. `#[macro_use]`.
55 fn is_mod_decl_without_attr(item: &ast::Item) -> bool {
56 is_mod_decl(item) && filter_inline_attrs(&item.attrs, item.span()).is_empty()
59 fn is_use_item(item: &ast::Item) -> bool {
61 ast::ItemKind::Use(_) => true,
66 fn is_extern_crate(item: &ast::Item) -> bool {
68 ast::ItemKind::ExternCrate(..) => true,
73 /// Creates a string slice corresponding to the specified span.
74 pub struct SnippetProvider<'a> {
75 /// A pointer to the content of the file we are formatting.
77 /// A position of the start of `big_snippet`, used as an offset.
81 impl<'a> SnippetProvider<'a> {
82 pub fn span_to_snippet(&self, span: Span) -> Option<&str> {
83 let start_index = span.lo().to_usize().checked_sub(self.start_pos)?;
84 let end_index = span.hi().to_usize().checked_sub(self.start_pos)?;
85 Some(&self.big_snippet[start_index..end_index])
88 pub fn new(start_pos: BytePos, big_snippet: &'a str) -> Self {
89 let start_pos = start_pos.to_usize();
97 pub struct FmtVisitor<'a> {
98 pub parse_session: &'a ParseSess,
99 pub codemap: &'a CodeMap,
101 pub last_pos: BytePos,
102 // FIXME: use an RAII util or closure for indenting
103 pub block_indent: Indent,
104 pub config: &'a Config,
105 pub is_if_else_block: bool,
106 pub snippet_provider: &'a SnippetProvider<'a>,
107 pub line_number: usize,
108 pub skipped_range: Vec<(usize, usize)>,
111 impl<'b, 'a: 'b> FmtVisitor<'a> {
112 pub fn shape(&self) -> Shape {
113 Shape::indented(self.block_indent, self.config)
116 fn visit_stmt(&mut self, stmt: &ast::Stmt) {
118 "visit_stmt: {:?} {:?}",
119 self.codemap.lookup_char_pos(stmt.span.lo()),
120 self.codemap.lookup_char_pos(stmt.span.hi())
124 ast::StmtKind::Item(ref item) => {
125 self.visit_item(item);
127 ast::StmtKind::Local(..) | ast::StmtKind::Expr(..) | ast::StmtKind::Semi(..) => {
128 if contains_skip(get_attrs_from_stmt(stmt)) {
129 self.push_skipped_with_span(stmt.span());
131 let rewrite = stmt.rewrite(&self.get_context(), self.shape());
132 self.push_rewrite(stmt.span(), rewrite)
135 ast::StmtKind::Mac(ref mac) => {
136 let (ref mac, _macro_style, ref attrs) = **mac;
137 if self.visit_attrs(attrs, ast::AttrStyle::Outer) {
138 self.push_skipped_with_span(stmt.span());
140 self.visit_mac(mac, None, MacroPosition::Statement);
142 self.format_missing(stmt.span.hi());
150 inner_attrs: Option<&[ast::Attribute]>,
154 "visit_block: {:?} {:?}",
155 self.codemap.lookup_char_pos(b.span.lo()),
156 self.codemap.lookup_char_pos(b.span.hi())
159 // Check if this block has braces.
160 let brace_compensation = BytePos(if has_braces { 1 } else { 0 });
162 self.last_pos = self.last_pos + brace_compensation;
163 self.block_indent = self.block_indent.block_indent(self.config);
166 if self.config.remove_blank_lines_at_start_or_end_of_block() {
167 if let Some(first_stmt) = b.stmts.first() {
168 let attr_lo = inner_attrs
169 .and_then(|attrs| inner_attributes(attrs).first().map(|attr| attr.span.lo()))
171 // Attributes for an item in a statement position
172 // do not belong to the statement. (rust-lang/rust#34459)
173 if let ast::StmtKind::Item(ref item) = first_stmt.node {
176 first_stmt.attrs().first()
178 // Some stmts can have embedded attributes.
179 // e.g. `match { #![attr] ... }`
180 let attr_lo = attr.span.lo();
181 if attr_lo < first_stmt.span.lo() {
189 let snippet = self.snippet(mk_sp(
191 attr_lo.unwrap_or(first_stmt.span.lo()),
193 let len = CommentCodeSlices::new(snippet)
195 .and_then(|(kind, _, s)| {
196 if kind == CodeCharKind::Normal {
202 if let Some(len) = len {
203 self.last_pos = self.last_pos + BytePos::from_usize(len);
208 // Format inner attributes if available.
209 let skip_rewrite = if let Some(attrs) = inner_attrs {
210 self.visit_attrs(attrs, ast::AttrStyle::Inner)
216 self.push_rewrite(b.span, None);
217 self.close_block(false);
218 self.last_pos = source!(self, b.span).hi();
222 self.walk_block_stmts(b);
224 if !b.stmts.is_empty() {
225 if let Some(expr) = utils::stmt_expr(&b.stmts[b.stmts.len() - 1]) {
226 if utils::semicolon_for_expr(&self.get_context(), expr) {
232 let mut remove_len = BytePos(0);
233 if self.config.remove_blank_lines_at_start_or_end_of_block() {
234 if let Some(stmt) = b.stmts.last() {
235 let snippet = self.snippet(mk_sp(
237 source!(self, b.span).hi() - brace_compensation,
239 let len = CommentCodeSlices::new(snippet)
241 .and_then(|(kind, _, s)| {
242 if kind == CodeCharKind::Normal && s.trim().is_empty() {
248 if let Some(len) = len {
249 remove_len = BytePos::from_usize(len);
254 let unindent_comment = (self.is_if_else_block && !b.stmts.is_empty()) && {
255 let end_pos = source!(self, b.span).hi() - brace_compensation - remove_len;
256 let snippet = self.snippet(mk_sp(self.last_pos, end_pos));
257 snippet.contains("//") || snippet.contains("/*")
259 // FIXME: we should compress any newlines here to just one
260 if unindent_comment {
261 self.block_indent = self.block_indent.block_unindent(self.config);
263 self.format_missing_with_indent(
264 source!(self, b.span).hi() - brace_compensation - remove_len,
266 if unindent_comment {
267 self.block_indent = self.block_indent.block_indent(self.config);
269 self.close_block(unindent_comment);
270 self.last_pos = source!(self, b.span).hi();
273 // FIXME: this is a terrible hack to indent the comments between the last
274 // item in the block and the closing brace to the block's level.
275 // The closing brace itself, however, should be indented at a shallower
277 fn close_block(&mut self, unindent_comment: bool) {
278 let total_len = self.buffer.len();
279 let chars_too_many = if unindent_comment {
281 } else if self.config.hard_tabs() {
284 self.config.tab_spaces()
286 self.buffer.truncate(total_len - chars_too_many);
288 self.block_indent = self.block_indent.block_unindent(self.config);
291 // Note that this only gets called for function definitions. Required methods
292 // on traits do not get handled here.
296 generics: &ast::Generics,
299 defaultness: ast::Defaultness,
300 inner_attrs: Option<&[ast::Attribute]>,
302 let indent = self.block_indent;
304 let rewrite = match fk {
305 visit::FnKind::ItemFn(ident, _, _, _, _, b) | visit::FnKind::Method(ident, _, _, b) => {
310 &FnSig::from_fn_kind(&fk, generics, fd, defaultness),
311 mk_sp(s.lo(), b.span.lo()),
315 visit::FnKind::Closure(_) => unreachable!(),
318 if let Some(fn_str) = rewrite {
319 self.format_missing_with_indent(source!(self, s).lo());
320 self.push_str(&fn_str);
321 if let Some(c) = fn_str.chars().last() {
323 self.last_pos = source!(self, block.span).hi();
328 self.format_missing(source!(self, block.span).lo());
331 self.last_pos = source!(self, block.span).lo();
332 self.visit_block(block, inner_attrs, true)
335 pub fn visit_item(&mut self, item: &ast::Item) {
336 skip_out_of_file_lines_range_visitor!(self, item.span);
338 // This is where we bail out if there is a skip attribute. This is only
339 // complex in the module case. It is complex because the module could be
340 // in a separate file and there might be attributes in both files, but
341 // the AST lumps them all together.
343 let mut attrs = &item.attrs;
345 // Module is inline, in this case we treat it like any other item.
346 _ if !is_mod_decl(item) => {
347 if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
348 self.push_skipped_with_span(item.span());
352 // Module is not inline, but should be skipped.
353 ast::ItemKind::Mod(..) if contains_skip(&item.attrs) => {
356 // Module is not inline and should not be skipped. We want
357 // to process only the attributes in the current file.
358 ast::ItemKind::Mod(..) => {
359 filtered_attrs = filter_inline_attrs(&item.attrs, item.span());
360 // Assert because if we should skip it should be caught by
362 assert!(!self.visit_attrs(&filtered_attrs, ast::AttrStyle::Outer));
363 attrs = &filtered_attrs;
366 if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
367 self.push_skipped_with_span(item.span());
374 ast::ItemKind::Use(ref tree) => self.format_import(item, tree),
375 ast::ItemKind::Impl(..) => {
376 let snippet = self.snippet(item.span);
377 let where_span_end = snippet
378 .find_uncommented("{")
379 .map(|x| (BytePos(x as u32)) + source!(self, item.span).lo());
380 let rw = format_impl(&self.get_context(), item, self.block_indent, where_span_end);
381 self.push_rewrite(item.span, rw);
383 ast::ItemKind::Trait(..) => {
384 let rw = format_trait(&self.get_context(), item, self.block_indent);
385 self.push_rewrite(item.span, rw);
387 ast::ItemKind::TraitAlias(ref generics, ref ty_param_bounds) => {
388 let shape = Shape::indented(self.block_indent, self.config);
389 let rw = format_trait_alias(
396 self.push_rewrite(item.span, rw);
398 ast::ItemKind::ExternCrate(_) => {
399 let rw = rewrite_extern_crate(&self.get_context(), item);
400 self.push_rewrite(item.span, rw);
402 ast::ItemKind::Struct(..) | ast::ItemKind::Union(..) => {
403 self.visit_struct(&StructParts::from_item(item));
405 ast::ItemKind::Enum(ref def, ref generics) => {
406 self.format_missing_with_indent(source!(self, item.span).lo());
407 self.visit_enum(item.ident, &item.vis, def, generics, item.span);
408 self.last_pos = source!(self, item.span).hi();
410 ast::ItemKind::Mod(ref module) => {
411 let is_inline = !is_mod_decl(item);
412 self.format_missing_with_indent(source!(self, item.span).lo());
413 self.format_mod(module, &item.vis, item.span, item.ident, attrs, is_inline);
415 ast::ItemKind::Mac(ref mac) => {
416 self.visit_mac(mac, Some(item.ident), MacroPosition::Item);
418 ast::ItemKind::ForeignMod(ref foreign_mod) => {
419 self.format_missing_with_indent(source!(self, item.span).lo());
420 self.format_foreign_mod(foreign_mod, item.span);
422 ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => {
423 self.visit_static(&StaticParts::from_item(item));
425 ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
427 visit::FnKind::ItemFn(item.ident, unsafety, constness, abi, &item.vis, body),
431 ast::Defaultness::Final,
435 ast::ItemKind::Ty(ref ty, ref generics) => {
436 let rewrite = rewrite_type_alias(
445 self.push_rewrite(item.span, rewrite);
447 ast::ItemKind::GlobalAsm(..) => {
448 let snippet = Some(self.snippet(item.span).to_owned());
449 self.push_rewrite(item.span, snippet);
451 ast::ItemKind::MacroDef(ref def) => {
452 let rewrite = rewrite_macro_def(
460 self.push_rewrite(item.span, rewrite);
465 pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
466 skip_out_of_file_lines_range_visitor!(self, ti.span);
468 if self.visit_attrs(&ti.attrs, ast::AttrStyle::Outer) {
469 self.push_skipped_with_span(ti.span());
474 ast::TraitItemKind::Const(..) => self.visit_static(&StaticParts::from_trait_item(ti)),
475 ast::TraitItemKind::Method(ref sig, None) => {
476 let indent = self.block_indent;
478 self.rewrite_required_fn(indent, ti.ident, sig, &ti.generics, ti.span);
479 self.push_rewrite(ti.span, rewrite);
481 ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
483 visit::FnKind::Method(ti.ident, sig, None, body),
487 ast::Defaultness::Final,
491 ast::TraitItemKind::Type(ref type_param_bounds, ref type_default) => {
492 let rewrite = rewrite_associated_type(
494 type_default.as_ref(),
495 Some(type_param_bounds),
499 self.push_rewrite(ti.span, rewrite);
501 ast::TraitItemKind::Macro(ref mac) => {
502 self.visit_mac(mac, Some(ti.ident), MacroPosition::Item);
507 pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
508 skip_out_of_file_lines_range_visitor!(self, ii.span);
510 if self.visit_attrs(&ii.attrs, ast::AttrStyle::Outer) {
511 self.push_skipped_with_span(ii.span());
516 ast::ImplItemKind::Method(ref sig, ref body) => {
518 visit::FnKind::Method(ii.ident, sig, Some(&ii.vis), body),
526 ast::ImplItemKind::Const(..) => self.visit_static(&StaticParts::from_impl_item(ii)),
527 ast::ImplItemKind::Type(ref ty) => {
528 let rewrite = rewrite_associated_impl_type(
536 self.push_rewrite(ii.span, rewrite);
538 ast::ImplItemKind::Macro(ref mac) => {
539 self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
544 fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>, pos: MacroPosition) {
545 skip_out_of_file_lines_range_visitor!(self, mac.span);
548 let shape = self.shape().sub_width(1).unwrap();
549 let rewrite = rewrite_macro(mac, ident, &self.get_context(), shape, pos);
550 self.push_rewrite(mac.span, rewrite);
553 pub fn push_str(&mut self, s: &str) {
554 self.line_number += count_newlines(s);
555 self.buffer.push_str(s);
558 fn push_rewrite_inner(&mut self, span: Span, rewrite: Option<String>) {
559 if let Some(ref s) = rewrite {
562 let snippet = self.snippet(span);
563 self.push_str(snippet);
565 self.last_pos = source!(self, span).hi();
568 pub fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
569 self.format_missing_with_indent(source!(self, span).lo());
570 self.push_rewrite_inner(span, rewrite);
573 pub fn push_skipped_with_span(&mut self, span: Span) {
574 self.format_missing_with_indent(source!(self, span).lo());
575 let lo = self.line_number + 1;
576 self.push_rewrite_inner(span, None);
577 let hi = self.line_number + 1;
578 self.skipped_range.push((lo, hi));
581 pub fn from_context(ctx: &'a RewriteContext) -> FmtVisitor<'a> {
582 FmtVisitor::from_codemap(ctx.parse_session, ctx.config, ctx.snippet_provider)
586 parse_session: &'a ParseSess,
588 snippet_provider: &'a SnippetProvider,
589 ) -> FmtVisitor<'a> {
592 codemap: parse_session.codemap(),
593 buffer: String::with_capacity(snippet_provider.big_snippet.len() * 2),
594 last_pos: BytePos(0),
595 block_indent: Indent::empty(),
597 is_if_else_block: false,
600 skipped_range: vec![],
604 pub fn opt_snippet(&'b self, span: Span) -> Option<&'a str> {
605 self.snippet_provider.span_to_snippet(span)
608 pub fn snippet(&'b self, span: Span) -> &'a str {
609 self.opt_snippet(span).unwrap()
612 // Returns true if we should skip the following item.
613 pub fn visit_attrs(&mut self, attrs: &[ast::Attribute], style: ast::AttrStyle) -> bool {
614 if contains_skip(attrs) {
618 let attrs: Vec<_> = attrs.iter().filter(|a| a.style == style).cloned().collect();
619 if attrs.is_empty() {
623 let rewrite = attrs.rewrite(&self.get_context(), self.shape());
624 let span = mk_sp(attrs[0].span.lo(), attrs[attrs.len() - 1].span.hi());
625 self.push_rewrite(span, rewrite);
630 fn reorder_items<F>(&mut self, items_left: &[&ast::Item], is_item: &F, in_group: bool) -> usize
632 F: Fn(&ast::Item) -> bool,
634 let mut last = self.codemap.lookup_line_range(items_left[0].span());
635 let item_length = items_left
638 is_item(&***ppi) && (!in_group || {
639 let current = self.codemap.lookup_line_range(ppi.span());
640 let in_same_group = current.lo < last.hi + 2;
646 let items = &items_left[..item_length];
648 let at_least_one_in_file_lines = items
650 .any(|item| !out_of_file_lines_range!(self, item.span));
652 if at_least_one_in_file_lines {
653 self.format_imports(items);
656 self.push_rewrite(item.span, None);
663 fn walk_items(&mut self, mut items_left: &[&ast::Item]) {
664 macro try_reorder_items_with($reorder: ident, $in_group: ident, $pred: ident) {
665 if self.config.$reorder() && $pred(&*items_left[0]) {
667 self.reorder_items(items_left, &$pred, self.config.$in_group());
668 let (_, rest) = items_left.split_at(used_items_len);
674 while !items_left.is_empty() {
675 // If the next item is a `use`, `extern crate` or `mod`, then extract it and any
676 // subsequent items that have the same item kind to be reordered within
677 // `format_imports`. Otherwise, just format the next item for output.
679 try_reorder_items_with!(reorder_imports, reorder_imports_in_group, is_use_item);
680 try_reorder_items_with!(
681 reorder_extern_crates,
682 reorder_extern_crates_in_group,
685 try_reorder_items_with!(reorder_modules, reorder_modules, is_mod_decl_without_attr);
687 // Reaching here means items were not reordered. There must be at least
688 // one item left in `items_left`, so calling `unwrap()` here is safe.
689 let (item, rest) = items_left.split_first().unwrap();
690 self.visit_item(item);
695 fn walk_mod_items(&mut self, m: &ast::Mod) {
696 self.walk_items(&ptr_vec_to_ref_vec(&m.items));
699 fn walk_stmts(&mut self, stmts: &[ast::Stmt]) {
700 fn to_stmt_item(stmt: &ast::Stmt) -> Option<&ast::Item> {
702 ast::StmtKind::Item(ref item) => Some(&**item),
707 if stmts.is_empty() {
711 // Extract leading `use ...;`.
712 let items: Vec<_> = stmts
714 .take_while(|stmt| to_stmt_item(stmt).map_or(false, is_use_item))
715 .filter_map(|stmt| to_stmt_item(stmt))
718 if items.is_empty() {
719 self.visit_stmt(&stmts[0]);
720 self.walk_stmts(&stmts[1..]);
722 self.walk_items(&items);
723 self.walk_stmts(&stmts[items.len()..]);
727 fn walk_block_stmts(&mut self, b: &ast::Block) {
728 self.walk_stmts(&b.stmts)
734 vis: &ast::Visibility,
737 attrs: &[ast::Attribute],
740 self.push_str(&*utils::format_visibility(vis));
741 self.push_str("mod ");
742 self.push_str(&ident.to_string());
745 match self.config.brace_style() {
746 BraceStyle::AlwaysNextLine => {
747 let sep_str = format!("\n{}{{", self.block_indent.to_string(self.config));
748 self.push_str(&sep_str);
750 _ => self.push_str(" {"),
752 // Hackery to account for the closing }.
753 let mod_lo = self.codemap.span_after(source!(self, s), "{");
755 self.snippet(mk_sp(mod_lo, source!(self, m.inner).hi() - BytePos(1)));
756 let body_snippet = body_snippet.trim();
757 if body_snippet.is_empty() {
760 self.last_pos = mod_lo;
761 self.block_indent = self.block_indent.block_indent(self.config);
762 self.visit_attrs(attrs, ast::AttrStyle::Inner);
763 self.walk_mod_items(m);
764 self.format_missing_with_indent(source!(self, m.inner).hi() - BytePos(1));
765 self.close_block(false);
767 self.last_pos = source!(self, m.inner).hi();
770 self.last_pos = source!(self, s).hi();
774 pub fn format_separate_mod(&mut self, m: &ast::Mod, filemap: &codemap::FileMap) {
775 self.block_indent = Indent::empty();
776 self.walk_mod_items(m);
777 self.format_missing_with_indent(filemap.end_pos);
780 pub fn skip_empty_lines(&mut self, end_pos: BytePos) {
781 while let Some(pos) = self.codemap
782 .opt_span_after(mk_sp(self.last_pos, end_pos), "\n")
784 if let Some(snippet) = self.opt_snippet(mk_sp(self.last_pos, pos)) {
785 if snippet.trim().is_empty() {
794 pub fn get_context(&self) -> RewriteContext {
796 parse_session: self.parse_session,
797 codemap: self.codemap,
801 is_if_else_block: false,
802 force_one_line_chain: false,
803 snippet_provider: self.snippet_provider,
808 impl Rewrite for ast::NestedMetaItem {
809 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
811 ast::NestedMetaItemKind::MetaItem(ref meta_item) => meta_item.rewrite(context, shape),
812 ast::NestedMetaItemKind::Literal(ref l) => rewrite_literal(context, l, shape),
817 impl Rewrite for ast::MetaItem {
818 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
819 Some(match self.node {
820 ast::MetaItemKind::Word => String::from(&*self.name.as_str()),
821 ast::MetaItemKind::List(ref list) => {
822 let name = self.name.as_str();
823 // 1 = `(`, 2 = `]` and `)`
824 let item_shape = shape
826 .shrink_left(name.len() + 1)
827 .and_then(|s| s.sub_width(2))?;
828 let items = itemize_list(
833 |nested_meta_item| nested_meta_item.span.lo(),
834 |nested_meta_item| nested_meta_item.span.hi(),
835 |nested_meta_item| nested_meta_item.rewrite(context, item_shape),
840 let item_vec = items.collect::<Vec<_>>();
841 let fmt = ListFormatting {
842 tactic: DefinitiveListTactic::Mixed,
844 trailing_separator: SeparatorTactic::Never,
845 separator_place: SeparatorPlace::Back,
847 ends_with_newline: false,
848 preserve_newline: false,
849 config: context.config,
851 format!("{}({})", name, write_list(&item_vec, &fmt)?)
853 ast::MetaItemKind::NameValue(ref literal) => {
854 let name = self.name.as_str();
856 let lit_shape = shape.shrink_left(name.len() + 3)?;
857 let value = rewrite_literal(context, literal, lit_shape)?;
858 format!("{} = {}", name, value)
864 impl Rewrite for ast::Attribute {
865 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
866 let prefix = match self.style {
867 ast::AttrStyle::Inner => "#!",
868 ast::AttrStyle::Outer => "#",
870 let snippet = context.snippet(self.span);
871 if self.is_sugared_doc {
872 let doc_shape = Shape {
873 width: cmp::min(shape.width, context.config.comment_width())
874 .checked_sub(shape.indent.width())
878 rewrite_comment(snippet, false, doc_shape, context.config)
880 if contains_comment(snippet) {
881 return Some(snippet.to_owned());
884 let shape = shape.offset_left(prefix.len() + 1)?;
886 .rewrite(context, shape)
887 .map(|rw| format!("{}[{}]", prefix, rw))
892 /// Returns the first group of attributes that fills the given predicate.
893 /// We consider two doc comments are in different group if they are separated by normal comments.
894 fn take_while_with_pred<'a, P>(
895 context: &RewriteContext,
896 attrs: &'a [ast::Attribute],
898 ) -> &'a [ast::Attribute]
900 P: Fn(&ast::Attribute) -> bool,
902 let mut last_index = 0;
903 let mut iter = attrs.iter().enumerate().peekable();
904 while let Some((i, attr)) = iter.next() {
908 if let Some(&(_, next_attr)) = iter.peek() {
909 // Extract comments between two attributes.
910 let span_between_attr = mk_sp(attr.span.hi(), next_attr.span.lo());
911 let snippet = context.snippet(span_between_attr);
912 if count_newlines(snippet) >= 2 || snippet.contains('/') {
921 &attrs[..last_index + 1]
925 fn rewrite_first_group_attrs(
926 context: &RewriteContext,
927 attrs: &[ast::Attribute],
929 ) -> Option<(usize, String)> {
930 if attrs.is_empty() {
931 return Some((0, String::new()));
933 // Rewrite doc comments
934 let sugared_docs = take_while_with_pred(context, attrs, |a| a.is_sugared_doc);
935 if !sugared_docs.is_empty() {
936 let snippet = sugared_docs
938 .map(|a| context.snippet(a.span))
943 rewrite_comment(&snippet, false, shape, context.config)?,
946 // Rewrite `#[derive(..)]`s.
947 if context.config.merge_derives() {
948 let derives = take_while_with_pred(context, attrs, is_derive);
949 if !derives.is_empty() {
950 let mut derive_args = vec![];
951 for derive in derives {
952 derive_args.append(&mut get_derive_args(context, derive)?);
954 return Some((derives.len(), format_derive(context, &derive_args, shape)?));
957 // Rewrite the first attribute.
958 Some((1, attrs[0].rewrite(context, shape)?))
961 fn has_newlines_before_after_comment(comment: &str) -> (&str, &str) {
962 // Look at before and after comment and see if there are any empty lines.
963 let comment_begin = comment.chars().position(|c| c == '/');
964 let len = comment_begin.unwrap_or_else(|| comment.len());
965 let mlb = count_newlines(&comment[..len]) > 1;
966 let mla = if comment_begin.is_none() {
969 let comment_end = comment.chars().rev().position(|c| !c.is_whitespace());
970 let len = comment_end.unwrap();
975 .filter(|c| *c == '\n')
978 (if mlb { "\n" } else { "" }, if mla { "\n" } else { "" })
981 impl<'a> Rewrite for [ast::Attribute] {
982 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
984 return Some(String::new());
986 let (first_group_len, first_group_str) = rewrite_first_group_attrs(context, self, shape)?;
987 if self.len() == 1 || first_group_len == self.len() {
988 Some(first_group_str)
990 let rest_str = self[first_group_len..].rewrite(context, shape)?;
991 let missing_span = mk_sp(
992 self[first_group_len - 1].span.hi(),
993 self[first_group_len].span.lo(),
995 // Preserve an empty line before/after doc comments.
996 if self[0].is_sugared_doc || self[first_group_len].is_sugared_doc {
997 let snippet = context.snippet(missing_span);
998 let (mla, mlb) = has_newlines_before_after_comment(snippet);
999 let comment = ::comment::recover_missing_comment_in_span(
1001 shape.with_max_width(context.config),
1005 let comment = if comment.is_empty() {
1006 format!("\n{}", mlb)
1008 format!("{}{}\n{}", mla, comment, mlb)
1014 shape.indent.to_string(context.config),
1018 combine_strs_with_missing_comments(
1031 // Format `#[derive(..)]`, using visual indent & mixed style when we need to go multiline.
1032 fn format_derive(context: &RewriteContext, derive_args: &[&str], shape: Shape) -> Option<String> {
1033 let mut result = String::with_capacity(128);
1034 result.push_str("#[derive(");
1035 // 11 = `#[derive()]`
1036 let initial_budget = shape.width.checked_sub(11)?;
1037 let mut budget = initial_budget;
1038 let num = derive_args.len();
1039 for (i, a) in derive_args.iter().enumerate() {
1041 let width = a.len() + 2;
1044 // Remove trailing whitespace.
1049 result.push_str(&(shape.indent + 9).to_string(context.config));
1050 budget = initial_budget;
1052 budget = budget.checked_sub(width).unwrap_or(0);
1056 result.push_str(", ")
1059 result.push_str(")]");
1063 fn is_derive(attr: &ast::Attribute) -> bool {
1064 attr.check_name("derive")
1067 /// Returns the arguments of `#[derive(...)]`.
1068 fn get_derive_args<'a>(context: &'a RewriteContext, attr: &ast::Attribute) -> Option<Vec<&'a str>> {
1069 attr.meta_item_list().map(|meta_item_list| {
1072 .map(|nested_meta_item| context.snippet(nested_meta_item.span))
1077 // Rewrite `extern crate foo;` WITHOUT attributes.
1078 pub fn rewrite_extern_crate(context: &RewriteContext, item: &ast::Item) -> Option<String> {
1079 assert!(is_extern_crate(item));
1080 let new_str = context.snippet(item.span);
1081 Some(if contains_comment(new_str) {
1084 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
1085 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
1089 fn get_attrs_from_stmt(stmt: &ast::Stmt) -> &[ast::Attribute] {
1091 ast::StmtKind::Local(ref local) => &local.attrs,
1092 ast::StmtKind::Item(ref item) => &item.attrs,
1093 ast::StmtKind::Expr(ref expr) | ast::StmtKind::Semi(ref expr) => &expr.attrs,
1094 ast::StmtKind::Mac(ref mac) => &mac.2,