src/visitor.rs

   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.
   4 //
   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.
  10
  11 use syntax::{ast, visit};
  12 use syntax::attr::HasAttrs;
  13 use syntax::codemap::{self, BytePos, CodeMap, Pos, Span};
  14 use syntax::parse::ParseSess;
  15
  16 use attr::*;
  17 use codemap::{LineRangeUtils, SpanUtils};
  18 use comment::{CodeCharKind, CommentCodeSlices, FindUncommented};
  19 use config::{BraceStyle, Config};
  20 use items::{format_impl, format_trait, format_trait_alias, is_mod_decl, is_use_item,
  21             rewrite_associated_impl_type, rewrite_associated_type, rewrite_extern_crate,
  22             rewrite_type_alias, FnSig, StaticParts, StructParts};
  23 use macros::{rewrite_macro, rewrite_macro_def, MacroPosition};
  24 use rewrite::{Rewrite, RewriteContext};
  25 use shape::{Indent, Shape};
  26 use spanned::Spanned;
  27 use utils::{self, contains_skip, count_newlines, inner_attributes, mk_sp, ptr_vec_to_ref_vec};
  28
  29 /// Creates a string slice corresponding to the specified span.
  30 pub struct SnippetProvider<'a> {
  31     /// A pointer to the content of the file we are formatting.
  32     big_snippet: &'a str,
  33     /// A position of the start of `big_snippet`, used as an offset.
  34     start_pos: usize,
  35 }
  36
  37 impl<'a> SnippetProvider<'a> {
  38     pub fn span_to_snippet(&self, span: Span) -> Option<&str> {
  39         let start_index = span.lo().to_usize().checked_sub(self.start_pos)?;
  40         let end_index = span.hi().to_usize().checked_sub(self.start_pos)?;
  41         Some(&self.big_snippet[start_index..end_index])
  42     }
  43
  44     pub fn new(start_pos: BytePos, big_snippet: &'a str) -> Self {
  45         let start_pos = start_pos.to_usize();
  46         SnippetProvider {
  47             big_snippet,
  48             start_pos,
  49         }
  50     }
  51 }
  52
  53 pub struct FmtVisitor<'a> {
  54     pub parse_session: &'a ParseSess,
  55     pub codemap: &'a CodeMap,
  56     pub buffer: String,
  57     pub last_pos: BytePos,
  58     // FIXME: use an RAII util or closure for indenting
  59     pub block_indent: Indent,
  60     pub config: &'a Config,
  61     pub is_if_else_block: bool,
  62     pub snippet_provider: &'a SnippetProvider<'a>,
  63     pub line_number: usize,
  64     pub skipped_range: Vec<(usize, usize)>,
  65 }
  66
  67 impl<'b, 'a: 'b> FmtVisitor<'a> {
  68     pub fn shape(&self) -> Shape {
  69         Shape::indented(self.block_indent, self.config)
  70     }
  71
  72     fn visit_stmt(&mut self, stmt: &ast::Stmt) {
  73         debug!(
  74             "visit_stmt: {:?} {:?}",
  75             self.codemap.lookup_char_pos(stmt.span.lo()),
  76             self.codemap.lookup_char_pos(stmt.span.hi())
  77         );
  78
  79         match stmt.node {
  80             ast::StmtKind::Item(ref item) => {
  81                 self.visit_item(item);
  82             }
  83             ast::StmtKind::Local(..) | ast::StmtKind::Expr(..) | ast::StmtKind::Semi(..) => {
  84                 if contains_skip(get_attrs_from_stmt(stmt)) {
  85                     self.push_skipped_with_span(stmt.span());
  86                 } else {
  87                     let rewrite = stmt.rewrite(&self.get_context(), self.shape());
  88                     self.push_rewrite(stmt.span(), rewrite)
  89                 }
  90             }
  91             ast::StmtKind::Mac(ref mac) => {
  92                 let (ref mac, _macro_style, ref attrs) = **mac;
  93                 if self.visit_attrs(attrs, ast::AttrStyle::Outer) {
  94                     self.push_skipped_with_span(stmt.span());
  95                 } else {
  96                     self.visit_mac(mac, None, MacroPosition::Statement);
  97                 }
  98                 self.format_missing(stmt.span.hi());
  99             }
 100         }
 101     }
 102
 103     pub fn visit_block(
 104         &mut self,
 105         b: &ast::Block,
 106         inner_attrs: Option<&[ast::Attribute]>,
 107         has_braces: bool,
 108     ) {
 109         debug!(
 110             "visit_block: {:?} {:?}",
 111             self.codemap.lookup_char_pos(b.span.lo()),
 112             self.codemap.lookup_char_pos(b.span.hi())
 113         );
 114
 115         // Check if this block has braces.
 116         let brace_compensation = BytePos(if has_braces { 1 } else { 0 });
 117
 118         self.last_pos = self.last_pos + brace_compensation;
 119         self.block_indent = self.block_indent.block_indent(self.config);
 120         self.push_str("{");
 121
 122         if self.config.remove_blank_lines_at_start_or_end_of_block() {
 123             if let Some(first_stmt) = b.stmts.first() {
 124                 let attr_lo = inner_attrs
 125                     .and_then(|attrs| inner_attributes(attrs).first().map(|attr| attr.span.lo()))
 126                     .or_else(|| {
 127                         // Attributes for an item in a statement position
 128                         // do not belong to the statement. (rust-lang/rust#34459)
 129                         if let ast::StmtKind::Item(ref item) = first_stmt.node {
 130                             item.attrs.first()
 131                         } else {
 132                             first_stmt.attrs().first()
 133                         }.and_then(|attr| {
 134                             // Some stmts can have embedded attributes.
 135                             // e.g. `match { #![attr] ... }`
 136                             let attr_lo = attr.span.lo();
 137                             if attr_lo < first_stmt.span.lo() {
 138                                 Some(attr_lo)
 139                             } else {
 140                                 None
 141                             }
 142                         })
 143                     });
 144
 145                 let snippet = self.snippet(mk_sp(
 146                     self.last_pos,
 147                     attr_lo.unwrap_or_else(|| first_stmt.span.lo()),
 148                 ));
 149                 let len = CommentCodeSlices::new(snippet)
 150                     .nth(0)
 151                     .and_then(|(kind, _, s)| {
 152                         if kind == CodeCharKind::Normal {
 153                             s.rfind('\n')
 154                         } else {
 155                             None
 156                         }
 157                     });
 158                 if let Some(len) = len {
 159                     self.last_pos = self.last_pos + BytePos::from_usize(len);
 160                 }
 161             }
 162         }
 163
 164         // Format inner attributes if available.
 165         let skip_rewrite = if let Some(attrs) = inner_attrs {
 166             self.visit_attrs(attrs, ast::AttrStyle::Inner)
 167         } else {
 168             false
 169         };
 170
 171         if skip_rewrite {
 172             self.push_rewrite(b.span, None);
 173             self.close_block(false);
 174             self.last_pos = source!(self, b.span).hi();
 175             return;
 176         }
 177
 178         self.walk_block_stmts(b);
 179
 180         if !b.stmts.is_empty() {
 181             if let Some(expr) = utils::stmt_expr(&b.stmts[b.stmts.len() - 1]) {
 182                 if utils::semicolon_for_expr(&self.get_context(), expr) {
 183                     self.push_str(";");
 184                 }
 185             }
 186         }
 187
 188         let mut remove_len = BytePos(0);
 189         if self.config.remove_blank_lines_at_start_or_end_of_block() {
 190             if let Some(stmt) = b.stmts.last() {
 191                 let snippet = self.snippet(mk_sp(
 192                     stmt.span.hi(),
 193                     source!(self, b.span).hi() - brace_compensation,
 194                 ));
 195                 let len = CommentCodeSlices::new(snippet)
 196                     .last()
 197                     .and_then(|(kind, _, s)| {
 198                         if kind == CodeCharKind::Normal && s.trim().is_empty() {
 199                             Some(s.len())
 200                         } else {
 201                             None
 202                         }
 203                     });
 204                 if let Some(len) = len {
 205                     remove_len = BytePos::from_usize(len);
 206                 }
 207             }
 208         }
 209
 210         let unindent_comment = (self.is_if_else_block && !b.stmts.is_empty()) && {
 211             let end_pos = source!(self, b.span).hi() - brace_compensation - remove_len;
 212             let snippet = self.snippet(mk_sp(self.last_pos, end_pos));
 213             snippet.contains("//") || snippet.contains("/*")
 214         };
 215         // FIXME: we should compress any newlines here to just one
 216         if unindent_comment {
 217             self.block_indent = self.block_indent.block_unindent(self.config);
 218         }
 219         self.format_missing_with_indent(
 220             source!(self, b.span).hi() - brace_compensation - remove_len,
 221         );
 222         if unindent_comment {
 223             self.block_indent = self.block_indent.block_indent(self.config);
 224         }
 225         self.close_block(unindent_comment);
 226         self.last_pos = source!(self, b.span).hi();
 227     }
 228
 229     // FIXME: this is a terrible hack to indent the comments between the last
 230     // item in the block and the closing brace to the block's level.
 231     // The closing brace itself, however, should be indented at a shallower
 232     // level.
 233     fn close_block(&mut self, unindent_comment: bool) {
 234         let total_len = self.buffer.len();
 235         let chars_too_many = if unindent_comment {
 236             0
 237         } else if self.config.hard_tabs() {
 238             1
 239         } else {
 240             self.config.tab_spaces()
 241         };
 242         self.buffer.truncate(total_len - chars_too_many);
 243         self.push_str("}");
 244         self.block_indent = self.block_indent.block_unindent(self.config);
 245     }
 246
 247     // Note that this only gets called for function definitions. Required methods
 248     // on traits do not get handled here.
 249     fn visit_fn(
 250         &mut self,
 251         fk: visit::FnKind,
 252         generics: &ast::Generics,
 253         fd: &ast::FnDecl,
 254         s: Span,
 255         defaultness: ast::Defaultness,
 256         inner_attrs: Option<&[ast::Attribute]>,
 257     ) {
 258         let indent = self.block_indent;
 259         let block;
 260         let rewrite = match fk {
 261             visit::FnKind::ItemFn(ident, _, _, _, _, b) | visit::FnKind::Method(ident, _, _, b) => {
 262                 block = b;
 263                 self.rewrite_fn(
 264                     indent,
 265                     ident,
 266                     &FnSig::from_fn_kind(&fk, generics, fd, defaultness),
 267                     mk_sp(s.lo(), b.span.lo()),
 268                     b,
 269                 )
 270             }
 271             visit::FnKind::Closure(_) => unreachable!(),
 272         };
 273
 274         if let Some(fn_str) = rewrite {
 275             self.format_missing_with_indent(source!(self, s).lo());
 276             self.push_str(&fn_str);
 277             if let Some(c) = fn_str.chars().last() {
 278                 if c == '}' {
 279                     self.last_pos = source!(self, block.span).hi();
 280                     return;
 281                 }
 282             }
 283         } else {
 284             self.format_missing(source!(self, block.span).lo());
 285         }
 286
 287         self.last_pos = source!(self, block.span).lo();
 288         self.visit_block(block, inner_attrs, true)
 289     }
 290
 291     pub fn visit_item(&mut self, item: &ast::Item) {
 292         skip_out_of_file_lines_range_visitor!(self, item.span);
 293
 294         // This is where we bail out if there is a skip attribute. This is only
 295         // complex in the module case. It is complex because the module could be
 296         // in a separate file and there might be attributes in both files, but
 297         // the AST lumps them all together.
 298         let filtered_attrs;
 299         let mut attrs = &item.attrs;
 300         match item.node {
 301             // Module is inline, in this case we treat it like any other item.
 302             _ if !is_mod_decl(item) => {
 303                 if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
 304                     self.push_skipped_with_span(item.span());
 305                     return;
 306                 }
 307             }
 308             // Module is not inline, but should be skipped.
 309             ast::ItemKind::Mod(..) if contains_skip(&item.attrs) => {
 310                 return;
 311             }
 312             // Module is not inline and should not be skipped. We want
 313             // to process only the attributes in the current file.
 314             ast::ItemKind::Mod(..) => {
 315                 filtered_attrs = filter_inline_attrs(&item.attrs, item.span());
 316                 // Assert because if we should skip it should be caught by
 317                 // the above case.
 318                 assert!(!self.visit_attrs(&filtered_attrs, ast::AttrStyle::Outer));
 319                 attrs = &filtered_attrs;
 320             }
 321             _ => {
 322                 if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
 323                     self.push_skipped_with_span(item.span());
 324                     return;
 325                 }
 326             }
 327         }
 328
 329         match item.node {
 330             ast::ItemKind::Use(ref tree) => self.format_import(item, tree),
 331             ast::ItemKind::Impl(..) => {
 332                 let snippet = self.snippet(item.span);
 333                 let where_span_end = snippet
 334                     .find_uncommented("{")
 335                     .map(|x| (BytePos(x as u32)) + source!(self, item.span).lo());
 336                 let rw = format_impl(&self.get_context(), item, self.block_indent, where_span_end);
 337                 self.push_rewrite(item.span, rw);
 338             }
 339             ast::ItemKind::Trait(..) => {
 340                 let rw = format_trait(&self.get_context(), item, self.block_indent);
 341                 self.push_rewrite(item.span, rw);
 342             }
 343             ast::ItemKind::TraitAlias(ref generics, ref ty_param_bounds) => {
 344                 let shape = Shape::indented(self.block_indent, self.config);
 345                 let rw = format_trait_alias(
 346                     &self.get_context(),
 347                     item.ident,
 348                     generics,
 349                     ty_param_bounds,
 350                     shape,
 351                 );
 352                 self.push_rewrite(item.span, rw);
 353             }
 354             ast::ItemKind::ExternCrate(_) => {
 355                 let rw = rewrite_extern_crate(&self.get_context(), item);
 356                 self.push_rewrite(item.span, rw);
 357             }
 358             ast::ItemKind::Struct(..) | ast::ItemKind::Union(..) => {
 359                 self.visit_struct(&StructParts::from_item(item));
 360             }
 361             ast::ItemKind::Enum(ref def, ref generics) => {
 362                 self.format_missing_with_indent(source!(self, item.span).lo());
 363                 self.visit_enum(item.ident, &item.vis, def, generics, item.span);
 364                 self.last_pos = source!(self, item.span).hi();
 365             }
 366             ast::ItemKind::Mod(ref module) => {
 367                 let is_inline = !is_mod_decl(item);
 368                 self.format_missing_with_indent(source!(self, item.span).lo());
 369                 self.format_mod(module, &item.vis, item.span, item.ident, attrs, is_inline);
 370             }
 371             ast::ItemKind::Mac(ref mac) => {
 372                 self.visit_mac(mac, Some(item.ident), MacroPosition::Item);
 373             }
 374             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 375                 self.format_missing_with_indent(source!(self, item.span).lo());
 376                 self.format_foreign_mod(foreign_mod, item.span);
 377             }
 378             ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => {
 379                 self.visit_static(&StaticParts::from_item(item));
 380             }
 381             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
 382                 self.visit_fn(
 383                     visit::FnKind::ItemFn(item.ident, unsafety, constness, abi, &item.vis, body),
 384                     generics,
 385                     decl,
 386                     item.span,
 387                     ast::Defaultness::Final,
 388                     Some(&item.attrs),
 389                 )
 390             }
 391             ast::ItemKind::Ty(ref ty, ref generics) => {
 392                 let rewrite = rewrite_type_alias(
 393                     &self.get_context(),
 394                     self.block_indent,
 395                     item.ident,
 396                     ty,
 397                     generics,
 398                     &item.vis,
 399                     item.span,
 400                 );
 401                 self.push_rewrite(item.span, rewrite);
 402             }
 403             ast::ItemKind::GlobalAsm(..) => {
 404                 let snippet = Some(self.snippet(item.span).to_owned());
 405                 self.push_rewrite(item.span, snippet);
 406             }
 407             ast::ItemKind::MacroDef(ref def) => {
 408                 let rewrite = rewrite_macro_def(
 409                     &self.get_context(),
 410                     self.shape(),
 411                     self.block_indent,
 412                     def,
 413                     item.ident,
 414                     &item.vis,
 415                     item.span,
 416                 );
 417                 self.push_rewrite(item.span, rewrite);
 418             }
 419         }
 420     }
 421
 422     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 423         skip_out_of_file_lines_range_visitor!(self, ti.span);
 424
 425         if self.visit_attrs(&ti.attrs, ast::AttrStyle::Outer) {
 426             self.push_skipped_with_span(ti.span());
 427             return;
 428         }
 429
 430         match ti.node {
 431             ast::TraitItemKind::Const(..) => self.visit_static(&StaticParts::from_trait_item(ti)),
 432             ast::TraitItemKind::Method(ref sig, None) => {
 433                 let indent = self.block_indent;
 434                 let rewrite =
 435                     self.rewrite_required_fn(indent, ti.ident, sig, &ti.generics, ti.span);
 436                 self.push_rewrite(ti.span, rewrite);
 437             }
 438             ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
 439                 self.visit_fn(
 440                     visit::FnKind::Method(ti.ident, sig, None, body),
 441                     &ti.generics,
 442                     &sig.decl,
 443                     ti.span,
 444                     ast::Defaultness::Final,
 445                     Some(&ti.attrs),
 446                 );
 447             }
 448             ast::TraitItemKind::Type(ref type_param_bounds, ref type_default) => {
 449                 let rewrite = rewrite_associated_type(
 450                     ti.ident,
 451                     type_default.as_ref(),
 452                     Some(type_param_bounds),
 453                     &self.get_context(),
 454                     self.block_indent,
 455                 );
 456                 self.push_rewrite(ti.span, rewrite);
 457             }
 458             ast::TraitItemKind::Macro(ref mac) => {
 459                 self.visit_mac(mac, Some(ti.ident), MacroPosition::Item);
 460             }
 461         }
 462     }
 463
 464     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 465         skip_out_of_file_lines_range_visitor!(self, ii.span);
 466
 467         if self.visit_attrs(&ii.attrs, ast::AttrStyle::Outer) {
 468             self.push_skipped_with_span(ii.span());
 469             return;
 470         }
 471
 472         match ii.node {
 473             ast::ImplItemKind::Method(ref sig, ref body) => {
 474                 self.visit_fn(
 475                     visit::FnKind::Method(ii.ident, sig, Some(&ii.vis), body),
 476                     &ii.generics,
 477                     &sig.decl,
 478                     ii.span,
 479                     ii.defaultness,
 480                     Some(&ii.attrs),
 481                 );
 482             }
 483             ast::ImplItemKind::Const(..) => self.visit_static(&StaticParts::from_impl_item(ii)),
 484             ast::ImplItemKind::Type(ref ty) => {
 485                 let rewrite = rewrite_associated_impl_type(
 486                     ii.ident,
 487                     ii.defaultness,
 488                     Some(ty),
 489                     None,
 490                     &self.get_context(),
 491                     self.block_indent,
 492                 );
 493                 self.push_rewrite(ii.span, rewrite);
 494             }
 495             ast::ImplItemKind::Macro(ref mac) => {
 496                 self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
 497             }
 498         }
 499     }
 500
 501     fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>, pos: MacroPosition) {
 502         skip_out_of_file_lines_range_visitor!(self, mac.span);
 503
 504         // 1 = ;
 505         let shape = self.shape().sub_width(1).unwrap();
 506         let rewrite = rewrite_macro(mac, ident, &self.get_context(), shape, pos);
 507         self.push_rewrite(mac.span, rewrite);
 508     }
 509
 510     pub fn push_str(&mut self, s: &str) {
 511         self.line_number += count_newlines(s);
 512         self.buffer.push_str(s);
 513     }
 514
 515     #[cfg_attr(feature = "cargo-clippy", allow(needless_pass_by_value))]
 516     fn push_rewrite_inner(&mut self, span: Span, rewrite: Option<String>) {
 517         if let Some(ref s) = rewrite {
 518             self.push_str(s);
 519         } else {
 520             let snippet = self.snippet(span);
 521             self.push_str(snippet);
 522         }
 523         self.last_pos = source!(self, span).hi();
 524     }
 525
 526     pub fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 527         self.format_missing_with_indent(source!(self, span).lo());
 528         self.push_rewrite_inner(span, rewrite);
 529     }
 530
 531     pub fn push_skipped_with_span(&mut self, span: Span) {
 532         self.format_missing_with_indent(source!(self, span).lo());
 533         let lo = self.line_number + 1;
 534         self.push_rewrite_inner(span, None);
 535         let hi = self.line_number + 1;
 536         self.skipped_range.push((lo, hi));
 537     }
 538
 539     pub fn from_context(ctx: &'a RewriteContext) -> FmtVisitor<'a> {
 540         FmtVisitor::from_codemap(ctx.parse_session, ctx.config, ctx.snippet_provider)
 541     }
 542
 543     pub fn from_codemap(
 544         parse_session: &'a ParseSess,
 545         config: &'a Config,
 546         snippet_provider: &'a SnippetProvider,
 547     ) -> FmtVisitor<'a> {
 548         FmtVisitor {
 549             parse_session,
 550             codemap: parse_session.codemap(),
 551             buffer: String::with_capacity(snippet_provider.big_snippet.len() * 2),
 552             last_pos: BytePos(0),
 553             block_indent: Indent::empty(),
 554             config,
 555             is_if_else_block: false,
 556             snippet_provider,
 557             line_number: 0,
 558             skipped_range: vec![],
 559         }
 560     }
 561
 562     pub fn opt_snippet(&'b self, span: Span) -> Option<&'a str> {
 563         self.snippet_provider.span_to_snippet(span)
 564     }
 565
 566     pub fn snippet(&'b self, span: Span) -> &'a str {
 567         self.opt_snippet(span).unwrap()
 568     }
 569
 570     // Returns true if we should skip the following item.
 571     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute], style: ast::AttrStyle) -> bool {
 572         if contains_skip(attrs) {
 573             return true;
 574         }
 575
 576         let attrs: Vec<_> = attrs.iter().filter(|a| a.style == style).cloned().collect();
 577         if attrs.is_empty() {
 578             return false;
 579         }
 580
 581         let rewrite = attrs.rewrite(&self.get_context(), self.shape());
 582         let span = mk_sp(attrs[0].span.lo(), attrs[attrs.len() - 1].span.hi());
 583         self.push_rewrite(span, rewrite);
 584
 585         false
 586     }
 587
 588     fn walk_mod_items(&mut self, m: &ast::Mod) {
 589         self.visit_items_with_reordering(&ptr_vec_to_ref_vec(&m.items));
 590     }
 591
 592     fn walk_stmts(&mut self, stmts: &[ast::Stmt]) {
 593         fn to_stmt_item(stmt: &ast::Stmt) -> Option<&ast::Item> {
 594             match stmt.node {
 595                 ast::StmtKind::Item(ref item) => Some(&**item),
 596                 _ => None,
 597             }
 598         }
 599
 600         if stmts.is_empty() {
 601             return;
 602         }
 603
 604         // Extract leading `use ...;`.
 605         let items: Vec<_> = stmts
 606             .iter()
 607             .take_while(|stmt| to_stmt_item(stmt).map_or(false, is_use_item))
 608             .filter_map(|stmt| to_stmt_item(stmt))
 609             .collect();
 610
 611         if items.is_empty() {
 612             self.visit_stmt(&stmts[0]);
 613             self.walk_stmts(&stmts[1..]);
 614         } else {
 615             self.visit_items_with_reordering(&items);
 616             self.walk_stmts(&stmts[items.len()..]);
 617         }
 618     }
 619
 620     fn walk_block_stmts(&mut self, b: &ast::Block) {
 621         self.walk_stmts(&b.stmts)
 622     }
 623
 624     fn format_mod(
 625         &mut self,
 626         m: &ast::Mod,
 627         vis: &ast::Visibility,
 628         s: Span,
 629         ident: ast::Ident,
 630         attrs: &[ast::Attribute],
 631         is_internal: bool,
 632     ) {
 633         self.push_str(&*utils::format_visibility(vis));
 634         self.push_str("mod ");
 635         self.push_str(&ident.to_string());
 636
 637         if is_internal {
 638             match self.config.brace_style() {
 639                 BraceStyle::AlwaysNextLine => {
 640                     let indent_str = self.block_indent.to_string_with_newline(self.config);
 641                     self.push_str(&indent_str);
 642                     self.push_str("{");
 643                 }
 644                 _ => self.push_str(" {"),
 645             }
 646             // Hackery to account for the closing }.
 647             let mod_lo = self.snippet_provider.span_after(source!(self, s), "{");
 648             let body_snippet =
 649                 self.snippet(mk_sp(mod_lo, source!(self, m.inner).hi() - BytePos(1)));
 650             let body_snippet = body_snippet.trim();
 651             if body_snippet.is_empty() {
 652                 self.push_str("}");
 653             } else {
 654                 self.last_pos = mod_lo;
 655                 self.block_indent = self.block_indent.block_indent(self.config);
 656                 self.visit_attrs(attrs, ast::AttrStyle::Inner);
 657                 self.walk_mod_items(m);
 658                 self.format_missing_with_indent(source!(self, m.inner).hi() - BytePos(1));
 659                 self.close_block(false);
 660             }
 661             self.last_pos = source!(self, m.inner).hi();
 662         } else {
 663             self.push_str(";");
 664             self.last_pos = source!(self, s).hi();
 665         }
 666     }
 667
 668     pub fn format_separate_mod(&mut self, m: &ast::Mod, filemap: &codemap::FileMap) {
 669         self.block_indent = Indent::empty();
 670         self.walk_mod_items(m);
 671         self.format_missing_with_indent(filemap.end_pos);
 672     }
 673
 674     pub fn skip_empty_lines(&mut self, end_pos: BytePos) {
 675         while let Some(pos) = self.snippet_provider
 676             .opt_span_after(mk_sp(self.last_pos, end_pos), "\n")
 677         {
 678             if let Some(snippet) = self.opt_snippet(mk_sp(self.last_pos, pos)) {
 679                 if snippet.trim().is_empty() {
 680                     self.last_pos = pos;
 681                 } else {
 682                     return;
 683                 }
 684             }
 685         }
 686     }
 687
 688     pub fn get_context(&self) -> RewriteContext {
 689         RewriteContext {
 690             parse_session: self.parse_session,
 691             codemap: self.codemap,
 692             config: self.config,
 693             inside_macro: false,
 694             use_block: false,
 695             is_if_else_block: false,
 696             force_one_line_chain: false,
 697             snippet_provider: self.snippet_provider,
 698         }
 699     }
 700 }