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::attr::HasAttrs;
  12 use syntax::codemap::{self, BytePos, CodeMap, Pos, Span};
  13 use syntax::parse::ParseSess;
  14 use syntax::{ast, visit};
  15
  16 use attr::*;
  17 use codemap::{LineRangeUtils, SpanUtils};
  18 use comment::{CodeCharKind, CommentCodeSlices, FindUncommented};
  19 use config::{BraceStyle, Config};
  20 use items::{
  21     format_impl, format_trait, format_trait_alias, is_mod_decl, is_use_item,
  22     rewrite_associated_impl_type, rewrite_associated_type, rewrite_extern_crate,
  23     rewrite_type_alias, FnSig, StaticParts, StructParts,
  24 };
  25 use macros::{rewrite_macro, rewrite_macro_def, MacroPosition};
  26 use rewrite::{Rewrite, RewriteContext};
  27 use shape::{Indent, Shape};
  28 use spanned::Spanned;
  29 use utils::{self, contains_skip, count_newlines, inner_attributes, mk_sp, ptr_vec_to_ref_vec};
  30
  31 use std::cell::RefCell;
  32
  33 /// Creates a string slice corresponding to the specified span.
  34 pub struct SnippetProvider<'a> {
  35     /// A pointer to the content of the file we are formatting.
  36     big_snippet: &'a str,
  37     /// A position of the start of `big_snippet`, used as an offset.
  38     start_pos: usize,
  39 }
  40
  41 impl<'a> SnippetProvider<'a> {
  42     pub fn span_to_snippet(&self, span: Span) -> Option<&str> {
  43         let start_index = span.lo().to_usize().checked_sub(self.start_pos)?;
  44         let end_index = span.hi().to_usize().checked_sub(self.start_pos)?;
  45         Some(&self.big_snippet[start_index..end_index])
  46     }
  47
  48     pub fn new(start_pos: BytePos, big_snippet: &'a str) -> Self {
  49         let start_pos = start_pos.to_usize();
  50         SnippetProvider {
  51             big_snippet,
  52             start_pos,
  53         }
  54     }
  55 }
  56
  57 pub struct FmtVisitor<'a> {
  58     pub parse_session: &'a ParseSess,
  59     pub codemap: &'a CodeMap,
  60     pub buffer: String,
  61     pub last_pos: BytePos,
  62     // FIXME: use an RAII util or closure for indenting
  63     pub block_indent: Indent,
  64     pub config: &'a Config,
  65     pub is_if_else_block: bool,
  66     pub snippet_provider: &'a SnippetProvider<'a>,
  67     pub line_number: usize,
  68     pub skipped_range: Vec<(usize, usize)>,
  69 }
  70
  71 impl<'b, 'a: 'b> FmtVisitor<'a> {
  72     pub fn shape(&self) -> Shape {
  73         Shape::indented(self.block_indent, self.config)
  74     }
  75
  76     fn visit_stmt(&mut self, stmt: &ast::Stmt) {
  77         debug!(
  78             "visit_stmt: {:?} {:?}",
  79             self.codemap.lookup_char_pos(stmt.span.lo()),
  80             self.codemap.lookup_char_pos(stmt.span.hi())
  81         );
  82
  83         match stmt.node {
  84             ast::StmtKind::Item(ref item) => {
  85                 self.visit_item(item);
  86             }
  87             ast::StmtKind::Local(..) | ast::StmtKind::Expr(..) | ast::StmtKind::Semi(..) => {
  88                 if contains_skip(get_attrs_from_stmt(stmt)) {
  89                     self.push_skipped_with_span(stmt.span());
  90                 } else {
  91                     let rewrite = stmt.rewrite(&self.get_context(), self.shape());
  92                     self.push_rewrite(stmt.span(), rewrite)
  93                 }
  94             }
  95             ast::StmtKind::Mac(ref mac) => {
  96                 let (ref mac, _macro_style, ref attrs) = **mac;
  97                 if self.visit_attrs(attrs, ast::AttrStyle::Outer) {
  98                     self.push_skipped_with_span(stmt.span());
  99                 } else {
 100                     self.visit_mac(mac, None, MacroPosition::Statement);
 101                 }
 102                 self.format_missing(stmt.span.hi());
 103             }
 104         }
 105     }
 106
 107     pub fn visit_block(
 108         &mut self,
 109         b: &ast::Block,
 110         inner_attrs: Option<&[ast::Attribute]>,
 111         has_braces: bool,
 112     ) {
 113         debug!(
 114             "visit_block: {:?} {:?}",
 115             self.codemap.lookup_char_pos(b.span.lo()),
 116             self.codemap.lookup_char_pos(b.span.hi())
 117         );
 118
 119         // Check if this block has braces.
 120         let brace_compensation = BytePos(if has_braces { 1 } else { 0 });
 121
 122         self.last_pos = self.last_pos + brace_compensation;
 123         self.block_indent = self.block_indent.block_indent(self.config);
 124         self.push_str("{");
 125
 126         if self.config.remove_blank_lines_at_start_or_end_of_block() {
 127             if let Some(first_stmt) = b.stmts.first() {
 128                 let attr_lo = inner_attrs
 129                     .and_then(|attrs| inner_attributes(attrs).first().map(|attr| attr.span.lo()))
 130                     .or_else(|| {
 131                         // Attributes for an item in a statement position
 132                         // do not belong to the statement. (rust-lang/rust#34459)
 133                         if let ast::StmtKind::Item(ref item) = first_stmt.node {
 134                             item.attrs.first()
 135                         } else {
 136                             first_stmt.attrs().first()
 137                         }.and_then(|attr| {
 138                             // Some stmts can have embedded attributes.
 139                             // e.g. `match { #![attr] ... }`
 140                             let attr_lo = attr.span.lo();
 141                             if attr_lo < first_stmt.span.lo() {
 142                                 Some(attr_lo)
 143                             } else {
 144                                 None
 145                             }
 146                         })
 147                     });
 148
 149                 let snippet = self.snippet(mk_sp(
 150                     self.last_pos,
 151                     attr_lo.unwrap_or_else(|| first_stmt.span.lo()),
 152                 ));
 153                 let len = CommentCodeSlices::new(snippet)
 154                     .nth(0)
 155                     .and_then(|(kind, _, s)| {
 156                         if kind == CodeCharKind::Normal {
 157                             s.rfind('\n')
 158                         } else {
 159                             None
 160                         }
 161                     });
 162                 if let Some(len) = len {
 163                     self.last_pos = self.last_pos + BytePos::from_usize(len);
 164                 }
 165             }
 166         }
 167
 168         // Format inner attributes if available.
 169         let skip_rewrite = if let Some(attrs) = inner_attrs {
 170             self.visit_attrs(attrs, ast::AttrStyle::Inner)
 171         } else {
 172             false
 173         };
 174
 175         if skip_rewrite {
 176             self.push_rewrite(b.span, None);
 177             self.close_block(false);
 178             self.last_pos = source!(self, b.span).hi();
 179             return;
 180         }
 181
 182         self.walk_block_stmts(b);
 183
 184         if !b.stmts.is_empty() {
 185             if let Some(expr) = utils::stmt_expr(&b.stmts[b.stmts.len() - 1]) {
 186                 if utils::semicolon_for_expr(&self.get_context(), expr) {
 187                     self.push_str(";");
 188                 }
 189             }
 190         }
 191
 192         let mut remove_len = BytePos(0);
 193         if self.config.remove_blank_lines_at_start_or_end_of_block() {
 194             if let Some(stmt) = b.stmts.last() {
 195                 let snippet = self.snippet(mk_sp(
 196                     stmt.span.hi(),
 197                     source!(self, b.span).hi() - brace_compensation,
 198                 ));
 199                 let len = CommentCodeSlices::new(snippet)
 200                     .last()
 201                     .and_then(|(kind, _, s)| {
 202                         if kind == CodeCharKind::Normal && s.trim().is_empty() {
 203                             Some(s.len())
 204                         } else {
 205                             None
 206                         }
 207                     });
 208                 if let Some(len) = len {
 209                     remove_len = BytePos::from_usize(len);
 210                 }
 211             }
 212         }
 213
 214         let unindent_comment = (self.is_if_else_block && !b.stmts.is_empty()) && {
 215             let end_pos = source!(self, b.span).hi() - brace_compensation - remove_len;
 216             let snippet = self.snippet(mk_sp(self.last_pos, end_pos));
 217             snippet.contains("//") || snippet.contains("/*")
 218         };
 219         // FIXME: we should compress any newlines here to just one
 220         if unindent_comment {
 221             self.block_indent = self.block_indent.block_unindent(self.config);
 222         }
 223         self.format_missing_with_indent(
 224             source!(self, b.span).hi() - brace_compensation - remove_len,
 225         );
 226         if unindent_comment {
 227             self.block_indent = self.block_indent.block_indent(self.config);
 228         }
 229         self.close_block(unindent_comment);
 230         self.last_pos = source!(self, b.span).hi();
 231     }
 232
 233     // FIXME: this is a terrible hack to indent the comments between the last
 234     // item in the block and the closing brace to the block's level.
 235     // The closing brace itself, however, should be indented at a shallower
 236     // level.
 237     fn close_block(&mut self, unindent_comment: bool) {
 238         let total_len = self.buffer.len();
 239         let chars_too_many = if unindent_comment {
 240             0
 241         } else if self.config.hard_tabs() {
 242             1
 243         } else {
 244             self.config.tab_spaces()
 245         };
 246         self.buffer.truncate(total_len - chars_too_many);
 247         self.push_str("}");
 248         self.block_indent = self.block_indent.block_unindent(self.config);
 249     }
 250
 251     // Note that this only gets called for function definitions. Required methods
 252     // on traits do not get handled here.
 253     fn visit_fn(
 254         &mut self,
 255         fk: visit::FnKind,
 256         generics: &ast::Generics,
 257         fd: &ast::FnDecl,
 258         s: Span,
 259         defaultness: ast::Defaultness,
 260         inner_attrs: Option<&[ast::Attribute]>,
 261     ) {
 262         let indent = self.block_indent;
 263         let block;
 264         let rewrite = match fk {
 265             visit::FnKind::ItemFn(ident, _, _, _, _, b) | visit::FnKind::Method(ident, _, _, b) => {
 266                 block = b;
 267                 self.rewrite_fn(
 268                     indent,
 269                     ident,
 270                     &FnSig::from_fn_kind(&fk, generics, fd, defaultness),
 271                     mk_sp(s.lo(), b.span.lo()),
 272                     b,
 273                     inner_attrs,
 274                 )
 275             }
 276             visit::FnKind::Closure(_) => unreachable!(),
 277         };
 278
 279         if let Some(fn_str) = rewrite {
 280             self.format_missing_with_indent(source!(self, s).lo());
 281             self.push_str(&fn_str);
 282             if let Some(c) = fn_str.chars().last() {
 283                 if c == '}' {
 284                     self.last_pos = source!(self, block.span).hi();
 285                     return;
 286                 }
 287             }
 288         } else {
 289             self.format_missing(source!(self, block.span).lo());
 290         }
 291
 292         self.last_pos = source!(self, block.span).lo();
 293         self.visit_block(block, inner_attrs, true)
 294     }
 295
 296     pub fn visit_item(&mut self, item: &ast::Item) {
 297         skip_out_of_file_lines_range_visitor!(self, item.span);
 298
 299         // This is where we bail out if there is a skip attribute. This is only
 300         // complex in the module case. It is complex because the module could be
 301         // in a separate file and there might be attributes in both files, but
 302         // the AST lumps them all together.
 303         let filtered_attrs;
 304         let mut attrs = &item.attrs;
 305         match item.node {
 306             // For use items, skip rewriting attributes. Just check for a skip attribute.
 307             ast::ItemKind::Use(..) => {
 308                 if contains_skip(attrs) {
 309                     self.push_skipped_with_span(item.span());
 310                     return;
 311                 }
 312             }
 313             // Module is inline, in this case we treat it like any other item.
 314             _ if !is_mod_decl(item) => {
 315                 if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
 316                     self.push_skipped_with_span(item.span());
 317                     return;
 318                 }
 319             }
 320             // Module is not inline, but should be skipped.
 321             ast::ItemKind::Mod(..) if contains_skip(&item.attrs) => {
 322                 return;
 323             }
 324             // Module is not inline and should not be skipped. We want
 325             // to process only the attributes in the current file.
 326             ast::ItemKind::Mod(..) => {
 327                 filtered_attrs = filter_inline_attrs(&item.attrs, item.span());
 328                 // Assert because if we should skip it should be caught by
 329                 // the above case.
 330                 assert!(!self.visit_attrs(&filtered_attrs, ast::AttrStyle::Outer));
 331                 attrs = &filtered_attrs;
 332             }
 333             _ => {
 334                 if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
 335                     self.push_skipped_with_span(item.span());
 336                     return;
 337                 }
 338             }
 339         }
 340
 341         match item.node {
 342             ast::ItemKind::Use(ref tree) => self.format_import(item, tree),
 343             ast::ItemKind::Impl(..) => {
 344                 let snippet = self.snippet(item.span);
 345                 let where_span_end = snippet
 346                     .find_uncommented("{")
 347                     .map(|x| BytePos(x as u32) + source!(self, item.span).lo());
 348                 let rw = format_impl(&self.get_context(), item, self.block_indent, where_span_end);
 349                 self.push_rewrite(item.span, rw);
 350             }
 351             ast::ItemKind::Trait(..) => {
 352                 let rw = format_trait(&self.get_context(), item, self.block_indent);
 353                 self.push_rewrite(item.span, rw);
 354             }
 355             ast::ItemKind::TraitAlias(ref generics, ref ty_param_bounds) => {
 356                 let shape = Shape::indented(self.block_indent, self.config);
 357                 let rw = format_trait_alias(
 358                     &self.get_context(),
 359                     item.ident,
 360                     generics,
 361                     ty_param_bounds,
 362                     shape,
 363                 );
 364                 self.push_rewrite(item.span, rw);
 365             }
 366             ast::ItemKind::ExternCrate(_) => {
 367                 let rw = rewrite_extern_crate(&self.get_context(), item);
 368                 self.push_rewrite(item.span, rw);
 369             }
 370             ast::ItemKind::Struct(..) | ast::ItemKind::Union(..) => {
 371                 self.visit_struct(&StructParts::from_item(item));
 372             }
 373             ast::ItemKind::Enum(ref def, ref generics) => {
 374                 self.format_missing_with_indent(source!(self, item.span).lo());
 375                 self.visit_enum(item.ident, &item.vis, def, generics, item.span);
 376                 self.last_pos = source!(self, item.span).hi();
 377             }
 378             ast::ItemKind::Mod(ref module) => {
 379                 let is_inline = !is_mod_decl(item);
 380                 self.format_missing_with_indent(source!(self, item.span).lo());
 381                 self.format_mod(module, &item.vis, item.span, item.ident, attrs, is_inline);
 382             }
 383             ast::ItemKind::Mac(ref mac) => {
 384                 self.visit_mac(mac, Some(item.ident), MacroPosition::Item);
 385             }
 386             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 387                 self.format_missing_with_indent(source!(self, item.span).lo());
 388                 self.format_foreign_mod(foreign_mod, item.span);
 389             }
 390             ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => {
 391                 self.visit_static(&StaticParts::from_item(item));
 392             }
 393             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
 394                 let inner_attrs = inner_attributes(&item.attrs);
 395                 self.visit_fn(
 396                     visit::FnKind::ItemFn(item.ident, unsafety, constness, abi, &item.vis, body),
 397                     generics,
 398                     decl,
 399                     item.span,
 400                     ast::Defaultness::Final,
 401                     Some(&inner_attrs),
 402                 )
 403             }
 404             ast::ItemKind::Ty(ref ty, ref generics) => {
 405                 let rewrite = rewrite_type_alias(
 406                     &self.get_context(),
 407                     self.block_indent,
 408                     item.ident,
 409                     ty,
 410                     generics,
 411                     &item.vis,
 412                     item.span,
 413                 );
 414                 self.push_rewrite(item.span, rewrite);
 415             }
 416             ast::ItemKind::GlobalAsm(..) => {
 417                 let snippet = Some(self.snippet(item.span).to_owned());
 418                 self.push_rewrite(item.span, snippet);
 419             }
 420             ast::ItemKind::MacroDef(ref def) => {
 421                 let rewrite = rewrite_macro_def(
 422                     &self.get_context(),
 423                     self.shape(),
 424                     self.block_indent,
 425                     def,
 426                     item.ident,
 427                     &item.vis,
 428                     item.span,
 429                 );
 430                 self.push_rewrite(item.span, rewrite);
 431             }
 432         }
 433     }
 434
 435     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 436         skip_out_of_file_lines_range_visitor!(self, ti.span);
 437
 438         if self.visit_attrs(&ti.attrs, ast::AttrStyle::Outer) {
 439             self.push_skipped_with_span(ti.span());
 440             return;
 441         }
 442
 443         match ti.node {
 444             ast::TraitItemKind::Const(..) => self.visit_static(&StaticParts::from_trait_item(ti)),
 445             ast::TraitItemKind::Method(ref sig, None) => {
 446                 let indent = self.block_indent;
 447                 let rewrite =
 448                     self.rewrite_required_fn(indent, ti.ident, sig, &ti.generics, ti.span);
 449                 self.push_rewrite(ti.span, rewrite);
 450             }
 451             ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
 452                 let inner_attrs = inner_attributes(&ti.attrs);
 453                 self.visit_fn(
 454                     visit::FnKind::Method(ti.ident, sig, None, body),
 455                     &ti.generics,
 456                     &sig.decl,
 457                     ti.span,
 458                     ast::Defaultness::Final,
 459                     Some(&inner_attrs),
 460                 );
 461             }
 462             ast::TraitItemKind::Type(ref type_param_bounds, ref type_default) => {
 463                 let rewrite = rewrite_associated_type(
 464                     ti.ident,
 465                     type_default.as_ref(),
 466                     Some(type_param_bounds),
 467                     &self.get_context(),
 468                     self.block_indent,
 469                 );
 470                 self.push_rewrite(ti.span, rewrite);
 471             }
 472             ast::TraitItemKind::Macro(ref mac) => {
 473                 self.visit_mac(mac, Some(ti.ident), MacroPosition::Item);
 474             }
 475         }
 476     }
 477
 478     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 479         skip_out_of_file_lines_range_visitor!(self, ii.span);
 480
 481         if self.visit_attrs(&ii.attrs, ast::AttrStyle::Outer) {
 482             self.push_skipped_with_span(ii.span());
 483             return;
 484         }
 485
 486         match ii.node {
 487             ast::ImplItemKind::Method(ref sig, ref body) => {
 488                 let inner_attrs = inner_attributes(&ii.attrs);
 489                 self.visit_fn(
 490                     visit::FnKind::Method(ii.ident, sig, Some(&ii.vis), body),
 491                     &ii.generics,
 492                     &sig.decl,
 493                     ii.span,
 494                     ii.defaultness,
 495                     Some(&inner_attrs),
 496                 );
 497             }
 498             ast::ImplItemKind::Const(..) => self.visit_static(&StaticParts::from_impl_item(ii)),
 499             ast::ImplItemKind::Type(ref ty) => {
 500                 let rewrite = rewrite_associated_impl_type(
 501                     ii.ident,
 502                     ii.defaultness,
 503                     Some(ty),
 504                     None,
 505                     &self.get_context(),
 506                     self.block_indent,
 507                 );
 508                 self.push_rewrite(ii.span, rewrite);
 509             }
 510             ast::ImplItemKind::Macro(ref mac) => {
 511                 self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
 512             }
 513         }
 514     }
 515
 516     fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>, pos: MacroPosition) {
 517         skip_out_of_file_lines_range_visitor!(self, mac.span);
 518
 519         // 1 = ;
 520         let shape = self.shape().sub_width(1).unwrap();
 521         let rewrite = rewrite_macro(mac, ident, &self.get_context(), shape, pos);
 522         self.push_rewrite(mac.span, rewrite);
 523     }
 524
 525     pub fn push_str(&mut self, s: &str) {
 526         self.line_number += count_newlines(s);
 527         self.buffer.push_str(s);
 528     }
 529
 530     #[cfg_attr(feature = "cargo-clippy", allow(needless_pass_by_value))]
 531     fn push_rewrite_inner(&mut self, span: Span, rewrite: Option<String>) {
 532         if let Some(ref s) = rewrite {
 533             self.push_str(s);
 534         } else {
 535             let snippet = self.snippet(span);
 536             self.push_str(snippet);
 537         }
 538         self.last_pos = source!(self, span).hi();
 539     }
 540
 541     pub fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 542         self.format_missing_with_indent(source!(self, span).lo());
 543         self.push_rewrite_inner(span, rewrite);
 544     }
 545
 546     pub fn push_skipped_with_span(&mut self, span: Span) {
 547         self.format_missing_with_indent(source!(self, span).lo());
 548         let lo = self.line_number + 1;
 549         self.push_rewrite_inner(span, None);
 550         let hi = self.line_number + 1;
 551         self.skipped_range.push((lo, hi));
 552     }
 553
 554     pub fn from_context(ctx: &'a RewriteContext) -> FmtVisitor<'a> {
 555         FmtVisitor::from_codemap(ctx.parse_session, ctx.config, ctx.snippet_provider)
 556     }
 557
 558     pub fn from_codemap(
 559         parse_session: &'a ParseSess,
 560         config: &'a Config,
 561         snippet_provider: &'a SnippetProvider,
 562     ) -> FmtVisitor<'a> {
 563         FmtVisitor {
 564             parse_session,
 565             codemap: parse_session.codemap(),
 566             buffer: String::with_capacity(snippet_provider.big_snippet.len() * 2),
 567             last_pos: BytePos(0),
 568             block_indent: Indent::empty(),
 569             config,
 570             is_if_else_block: false,
 571             snippet_provider,
 572             line_number: 0,
 573             skipped_range: vec![],
 574         }
 575     }
 576
 577     pub fn opt_snippet(&'b self, span: Span) -> Option<&'a str> {
 578         self.snippet_provider.span_to_snippet(span)
 579     }
 580
 581     pub fn snippet(&'b self, span: Span) -> &'a str {
 582         self.opt_snippet(span).unwrap()
 583     }
 584
 585     // Returns true if we should skip the following item.
 586     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute], style: ast::AttrStyle) -> bool {
 587         if contains_skip(attrs) {
 588             return true;
 589         }
 590
 591         let attrs: Vec<_> = attrs.iter().filter(|a| a.style == style).cloned().collect();
 592         if attrs.is_empty() {
 593             return false;
 594         }
 595
 596         let rewrite = attrs.rewrite(&self.get_context(), self.shape());
 597         let span = mk_sp(attrs[0].span.lo(), attrs[attrs.len() - 1].span.hi());
 598         self.push_rewrite(span, rewrite);
 599
 600         false
 601     }
 602
 603     fn walk_mod_items(&mut self, m: &ast::Mod) {
 604         self.visit_items_with_reordering(&ptr_vec_to_ref_vec(&m.items));
 605     }
 606
 607     fn walk_stmts(&mut self, stmts: &[ast::Stmt]) {
 608         fn to_stmt_item(stmt: &ast::Stmt) -> Option<&ast::Item> {
 609             match stmt.node {
 610                 ast::StmtKind::Item(ref item) => Some(&**item),
 611                 _ => None,
 612             }
 613         }
 614
 615         if stmts.is_empty() {
 616             return;
 617         }
 618
 619         // Extract leading `use ...;`.
 620         let items: Vec<_> = stmts
 621             .iter()
 622             .take_while(|stmt| to_stmt_item(stmt).map_or(false, is_use_item))
 623             .filter_map(|stmt| to_stmt_item(stmt))
 624             .collect();
 625
 626         if items.is_empty() {
 627             self.visit_stmt(&stmts[0]);
 628             self.walk_stmts(&stmts[1..]);
 629         } else {
 630             self.visit_items_with_reordering(&items);
 631             self.walk_stmts(&stmts[items.len()..]);
 632         }
 633     }
 634
 635     fn walk_block_stmts(&mut self, b: &ast::Block) {
 636         self.walk_stmts(&b.stmts)
 637     }
 638
 639     fn format_mod(
 640         &mut self,
 641         m: &ast::Mod,
 642         vis: &ast::Visibility,
 643         s: Span,
 644         ident: ast::Ident,
 645         attrs: &[ast::Attribute],
 646         is_internal: bool,
 647     ) {
 648         self.push_str(&*utils::format_visibility(vis));
 649         self.push_str("mod ");
 650         self.push_str(&ident.to_string());
 651
 652         if is_internal {
 653             match self.config.brace_style() {
 654                 BraceStyle::AlwaysNextLine => {
 655                     let indent_str = self.block_indent.to_string_with_newline(self.config);
 656                     self.push_str(&indent_str);
 657                     self.push_str("{");
 658                 }
 659                 _ => self.push_str(" {"),
 660             }
 661             // Hackery to account for the closing }.
 662             let mod_lo = self.snippet_provider.span_after(source!(self, s), "{");
 663             let body_snippet =
 664                 self.snippet(mk_sp(mod_lo, source!(self, m.inner).hi() - BytePos(1)));
 665             let body_snippet = body_snippet.trim();
 666             if body_snippet.is_empty() {
 667                 self.push_str("}");
 668             } else {
 669                 self.last_pos = mod_lo;
 670                 self.block_indent = self.block_indent.block_indent(self.config);
 671                 self.visit_attrs(attrs, ast::AttrStyle::Inner);
 672                 self.walk_mod_items(m);
 673                 self.format_missing_with_indent(source!(self, m.inner).hi() - BytePos(1));
 674                 self.close_block(false);
 675             }
 676             self.last_pos = source!(self, m.inner).hi();
 677         } else {
 678             self.push_str(";");
 679             self.last_pos = source!(self, s).hi();
 680         }
 681     }
 682
 683     pub fn format_separate_mod(&mut self, m: &ast::Mod, filemap: &codemap::FileMap) {
 684         self.block_indent = Indent::empty();
 685         self.walk_mod_items(m);
 686         self.format_missing_with_indent(filemap.end_pos);
 687     }
 688
 689     pub fn skip_empty_lines(&mut self, end_pos: BytePos) {
 690         while let Some(pos) = self
 691             .snippet_provider
 692             .opt_span_after(mk_sp(self.last_pos, end_pos), "\n")
 693         {
 694             if let Some(snippet) = self.opt_snippet(mk_sp(self.last_pos, pos)) {
 695                 if snippet.trim().is_empty() {
 696                     self.last_pos = pos;
 697                 } else {
 698                     return;
 699                 }
 700             }
 701         }
 702     }
 703
 704     pub fn get_context(&self) -> RewriteContext {
 705         RewriteContext {
 706             parse_session: self.parse_session,
 707             codemap: self.codemap,
 708             config: self.config,
 709             inside_macro: RefCell::new(false),
 710             use_block: RefCell::new(false),
 711             is_if_else_block: RefCell::new(false),
 712             force_one_line_chain: RefCell::new(false),
 713             snippet_provider: self.snippet_provider,
 714         }
 715     }
 716 }