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::parse::ParseSess;
  13 use syntax::source_map::{self, BytePos, Pos, SourceMap, Span};
  14 use syntax::{ast, visit};
  15
  16 use attr::*;
  17 use comment::{CodeCharKind, CommentCodeSlices, FindUncommented};
  18 use config::{BraceStyle, Config};
  19 use items::{
  20     format_impl, format_trait, format_trait_alias, is_mod_decl, is_use_item,
  21     rewrite_associated_impl_type, rewrite_associated_type, rewrite_existential_impl_type,
  22     rewrite_existential_type, rewrite_extern_crate, rewrite_type_alias, FnSig, StaticParts,
  23     StructParts,
  24 };
  25 use macros::{rewrite_macro, rewrite_macro_def, MacroPosition};
  26 use rewrite::{Rewrite, RewriteContext};
  27 use shape::{Indent, Shape};
  28 use source_map::{LineRangeUtils, SpanUtils};
  29 use spanned::Spanned;
  30 use utils::{
  31     self, contains_skip, count_newlines, inner_attributes, mk_sp, ptr_vec_to_ref_vec,
  32     rewrite_ident, DEPR_SKIP_ANNOTATION,
  33 };
  34 use {ErrorKind, FormatReport, FormattingError};
  35
  36 use std::cell::RefCell;
  37
  38 /// Creates a string slice corresponding to the specified span.
  39 pub struct SnippetProvider<'a> {
  40     /// A pointer to the content of the file we are formatting.
  41     big_snippet: &'a str,
  42     /// A position of the start of `big_snippet`, used as an offset.
  43     start_pos: usize,
  44 }
  45
  46 impl<'a> SnippetProvider<'a> {
  47     pub fn span_to_snippet(&self, span: Span) -> Option<&str> {
  48         let start_index = span.lo().to_usize().checked_sub(self.start_pos)?;
  49         let end_index = span.hi().to_usize().checked_sub(self.start_pos)?;
  50         Some(&self.big_snippet[start_index..end_index])
  51     }
  52
  53     pub fn new(start_pos: BytePos, big_snippet: &'a str) -> Self {
  54         let start_pos = start_pos.to_usize();
  55         SnippetProvider {
  56             big_snippet,
  57             start_pos,
  58         }
  59     }
  60 }
  61
  62 pub struct FmtVisitor<'a> {
  63     parent_context: Option<&'a RewriteContext<'a>>,
  64     pub parse_session: &'a ParseSess,
  65     pub source_map: &'a SourceMap,
  66     pub buffer: String,
  67     pub last_pos: BytePos,
  68     // FIXME: use an RAII util or closure for indenting
  69     pub block_indent: Indent,
  70     pub config: &'a Config,
  71     pub is_if_else_block: bool,
  72     pub snippet_provider: &'a SnippetProvider<'a>,
  73     pub line_number: usize,
  74     pub skipped_range: Vec<(usize, usize)>,
  75     pub macro_rewrite_failure: bool,
  76     pub(crate) report: FormatReport,
  77 }
  78
  79 impl<'a> Drop for FmtVisitor<'a> {
  80     fn drop(&mut self) {
  81         if let Some(ctx) = self.parent_context {
  82             if self.macro_rewrite_failure {
  83                 ctx.macro_rewrite_failure.replace(true);
  84             }
  85         }
  86     }
  87 }
  88
  89 impl<'b, 'a: 'b> FmtVisitor<'a> {
  90     fn set_parent_context(&mut self, context: &'a RewriteContext) {
  91         self.parent_context = Some(context);
  92     }
  93
  94     pub fn shape(&self) -> Shape {
  95         Shape::indented(self.block_indent, self.config)
  96     }
  97
  98     fn visit_stmt(&mut self, stmt: &ast::Stmt) {
  99         debug!(
 100             "visit_stmt: {:?} {:?}",
 101             self.source_map.lookup_char_pos(stmt.span.lo()),
 102             self.source_map.lookup_char_pos(stmt.span.hi())
 103         );
 104
 105         match stmt.node {
 106             ast::StmtKind::Item(ref item) => {
 107                 self.visit_item(item);
 108                 // Handle potential `;` after the item.
 109                 self.format_missing(stmt.span.hi());
 110             }
 111             ast::StmtKind::Local(..) | ast::StmtKind::Expr(..) | ast::StmtKind::Semi(..) => {
 112                 if contains_skip(get_attrs_from_stmt(stmt)) {
 113                     self.push_skipped_with_span(stmt.span());
 114                 } else {
 115                     let shape = self.shape().clone();
 116                     let rewrite = self.with_context(|ctx| stmt.rewrite(&ctx, shape));
 117                     self.push_rewrite(stmt.span(), rewrite)
 118                 }
 119             }
 120             ast::StmtKind::Mac(ref mac) => {
 121                 let (ref mac, _macro_style, ref attrs) = **mac;
 122                 if self.visit_attrs(attrs, ast::AttrStyle::Outer) {
 123                     self.push_skipped_with_span(stmt.span());
 124                 } else {
 125                     self.visit_mac(mac, None, MacroPosition::Statement);
 126                 }
 127                 self.format_missing(stmt.span.hi());
 128             }
 129         }
 130     }
 131
 132     pub fn visit_block(
 133         &mut self,
 134         b: &ast::Block,
 135         inner_attrs: Option<&[ast::Attribute]>,
 136         has_braces: bool,
 137     ) {
 138         debug!(
 139             "visit_block: {:?} {:?}",
 140             self.source_map.lookup_char_pos(b.span.lo()),
 141             self.source_map.lookup_char_pos(b.span.hi())
 142         );
 143
 144         // Check if this block has braces.
 145         let brace_compensation = BytePos(if has_braces { 1 } else { 0 });
 146
 147         self.last_pos = self.last_pos + brace_compensation;
 148         self.block_indent = self.block_indent.block_indent(self.config);
 149         self.push_str("{");
 150
 151         if let Some(first_stmt) = b.stmts.first() {
 152             let attr_lo = inner_attrs
 153                 .and_then(|attrs| inner_attributes(attrs).first().map(|attr| attr.span.lo()))
 154                 .or_else(|| {
 155                     // Attributes for an item in a statement position
 156                     // do not belong to the statement. (rust-lang/rust#34459)
 157                     if let ast::StmtKind::Item(ref item) = first_stmt.node {
 158                         item.attrs.first()
 159                     } else {
 160                         first_stmt.attrs().first()
 161                     }.and_then(|attr| {
 162                         // Some stmts can have embedded attributes.
 163                         // e.g. `match { #![attr] ... }`
 164                         let attr_lo = attr.span.lo();
 165                         if attr_lo < first_stmt.span.lo() {
 166                             Some(attr_lo)
 167                         } else {
 168                             None
 169                         }
 170                     })
 171                 });
 172
 173             let snippet = self.snippet(mk_sp(
 174                 self.last_pos,
 175                 attr_lo.unwrap_or_else(|| first_stmt.span.lo()),
 176             ));
 177             let len = CommentCodeSlices::new(snippet)
 178                 .nth(0)
 179                 .and_then(|(kind, _, s)| {
 180                     if kind == CodeCharKind::Normal {
 181                         s.rfind('\n')
 182                     } else {
 183                         None
 184                     }
 185                 });
 186             if let Some(len) = len {
 187                 self.last_pos = self.last_pos + BytePos::from_usize(len);
 188             }
 189         }
 190
 191         // Format inner attributes if available.
 192         let skip_rewrite = if let Some(attrs) = inner_attrs {
 193             self.visit_attrs(attrs, ast::AttrStyle::Inner)
 194         } else {
 195             false
 196         };
 197
 198         if skip_rewrite {
 199             self.push_rewrite(b.span, None);
 200             self.close_block(false);
 201             self.last_pos = source!(self, b.span).hi();
 202             return;
 203         }
 204
 205         self.walk_block_stmts(b);
 206
 207         if !b.stmts.is_empty() {
 208             if let Some(expr) = utils::stmt_expr(&b.stmts[b.stmts.len() - 1]) {
 209                 if utils::semicolon_for_expr(&self.get_context(), expr) {
 210                     self.push_str(";");
 211                 }
 212             }
 213         }
 214
 215         let mut remove_len = BytePos(0);
 216         if let Some(stmt) = b.stmts.last() {
 217             let snippet = self.snippet(mk_sp(
 218                 stmt.span.hi(),
 219                 source!(self, b.span).hi() - brace_compensation,
 220             ));
 221             let len = CommentCodeSlices::new(snippet)
 222                 .last()
 223                 .and_then(|(kind, _, s)| {
 224                     if kind == CodeCharKind::Normal && s.trim().is_empty() {
 225                         Some(s.len())
 226                     } else {
 227                         None
 228                     }
 229                 });
 230             if let Some(len) = len {
 231                 remove_len = BytePos::from_usize(len);
 232             }
 233         }
 234
 235         let unindent_comment = (self.is_if_else_block && !b.stmts.is_empty()) && {
 236             let end_pos = source!(self, b.span).hi() - brace_compensation - remove_len;
 237             let snippet = self.snippet(mk_sp(self.last_pos, end_pos));
 238             snippet.contains("//") || snippet.contains("/*")
 239         };
 240         // FIXME: we should compress any newlines here to just one
 241         if unindent_comment {
 242             self.block_indent = self.block_indent.block_unindent(self.config);
 243         }
 244         self.format_missing_with_indent(
 245             source!(self, b.span).hi() - brace_compensation - remove_len,
 246         );
 247         if unindent_comment {
 248             self.block_indent = self.block_indent.block_indent(self.config);
 249         }
 250         self.close_block(unindent_comment);
 251         self.last_pos = source!(self, b.span).hi();
 252     }
 253
 254     // FIXME: this is a terrible hack to indent the comments between the last
 255     // item in the block and the closing brace to the block's level.
 256     // The closing brace itself, however, should be indented at a shallower
 257     // level.
 258     fn close_block(&mut self, unindent_comment: bool) {
 259         let total_len = self.buffer.len();
 260         let chars_too_many = if unindent_comment {
 261             0
 262         } else if self.config.hard_tabs() {
 263             1
 264         } else {
 265             self.config.tab_spaces()
 266         };
 267         self.buffer.truncate(total_len - chars_too_many);
 268         self.push_str("}");
 269         self.block_indent = self.block_indent.block_unindent(self.config);
 270     }
 271
 272     // Note that this only gets called for function definitions. Required methods
 273     // on traits do not get handled here.
 274     fn visit_fn(
 275         &mut self,
 276         fk: visit::FnKind,
 277         generics: &ast::Generics,
 278         fd: &ast::FnDecl,
 279         s: Span,
 280         defaultness: ast::Defaultness,
 281         inner_attrs: Option<&[ast::Attribute]>,
 282     ) {
 283         let indent = self.block_indent;
 284         let block;
 285         let rewrite = match fk {
 286             visit::FnKind::ItemFn(ident, _, _, b) | visit::FnKind::Method(ident, _, _, b) => {
 287                 block = b;
 288                 self.rewrite_fn(
 289                     indent,
 290                     ident,
 291                     &FnSig::from_fn_kind(&fk, generics, fd, defaultness),
 292                     mk_sp(s.lo(), b.span.lo()),
 293                     b,
 294                     inner_attrs,
 295                 )
 296             }
 297             visit::FnKind::Closure(_) => unreachable!(),
 298         };
 299
 300         if let Some(fn_str) = rewrite {
 301             self.format_missing_with_indent(source!(self, s).lo());
 302             self.push_str(&fn_str);
 303             if let Some(c) = fn_str.chars().last() {
 304                 if c == '}' {
 305                     self.last_pos = source!(self, block.span).hi();
 306                     return;
 307                 }
 308             }
 309         } else {
 310             self.format_missing(source!(self, block.span).lo());
 311         }
 312
 313         self.last_pos = source!(self, block.span).lo();
 314         self.visit_block(block, inner_attrs, true)
 315     }
 316
 317     pub fn visit_item(&mut self, item: &ast::Item) {
 318         skip_out_of_file_lines_range_visitor!(self, item.span);
 319
 320         // This is where we bail out if there is a skip attribute. This is only
 321         // complex in the module case. It is complex because the module could be
 322         // in a separate file and there might be attributes in both files, but
 323         // the AST lumps them all together.
 324         let filtered_attrs;
 325         let mut attrs = &item.attrs;
 326         match item.node {
 327             // For use items, skip rewriting attributes. Just check for a skip attribute.
 328             ast::ItemKind::Use(..) => {
 329                 if contains_skip(attrs) {
 330                     self.push_skipped_with_span(item.span());
 331                     return;
 332                 }
 333             }
 334             // Module is inline, in this case we treat it like any other item.
 335             _ if !is_mod_decl(item) => {
 336                 if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
 337                     self.push_skipped_with_span(item.span());
 338                     return;
 339                 }
 340             }
 341             // Module is not inline, but should be skipped.
 342             ast::ItemKind::Mod(..) if contains_skip(&item.attrs) => {
 343                 return;
 344             }
 345             // Module is not inline and should not be skipped. We want
 346             // to process only the attributes in the current file.
 347             ast::ItemKind::Mod(..) => {
 348                 filtered_attrs = filter_inline_attrs(&item.attrs, item.span());
 349                 // Assert because if we should skip it should be caught by
 350                 // the above case.
 351                 assert!(!self.visit_attrs(&filtered_attrs, ast::AttrStyle::Outer));
 352                 attrs = &filtered_attrs;
 353             }
 354             _ => {
 355                 if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
 356                     self.push_skipped_with_span(item.span());
 357                     return;
 358                 }
 359             }
 360         }
 361
 362         match item.node {
 363             ast::ItemKind::Use(ref tree) => self.format_import(item, tree),
 364             ast::ItemKind::Impl(..) => {
 365                 let snippet = self.snippet(item.span);
 366                 let where_span_end = snippet
 367                     .find_uncommented("{")
 368                     .map(|x| BytePos(x as u32) + source!(self, item.span).lo());
 369                 let block_indent = self.block_indent.clone();
 370                 let rw =
 371                     self.with_context(|ctx| format_impl(&ctx, item, block_indent, where_span_end));
 372                 self.push_rewrite(item.span, rw);
 373             }
 374             ast::ItemKind::Trait(..) => {
 375                 let block_indent = self.block_indent.clone();
 376                 let rw = self.with_context(|ctx| format_trait(&ctx, item, block_indent));
 377                 self.push_rewrite(item.span, rw);
 378             }
 379             ast::ItemKind::TraitAlias(ref generics, ref generic_bounds) => {
 380                 let shape = Shape::indented(self.block_indent, self.config);
 381                 let rw = format_trait_alias(
 382                     &self.get_context(),
 383                     item.ident,
 384                     generics,
 385                     generic_bounds,
 386                     shape,
 387                 );
 388                 self.push_rewrite(item.span, rw);
 389             }
 390             ast::ItemKind::ExternCrate(_) => {
 391                 let rw = rewrite_extern_crate(&self.get_context(), item);
 392                 self.push_rewrite(item.span, rw);
 393             }
 394             ast::ItemKind::Struct(..) | ast::ItemKind::Union(..) => {
 395                 self.visit_struct(&StructParts::from_item(item));
 396             }
 397             ast::ItemKind::Enum(ref def, ref generics) => {
 398                 self.format_missing_with_indent(source!(self, item.span).lo());
 399                 self.visit_enum(item.ident, &item.vis, def, generics, item.span);
 400                 self.last_pos = source!(self, item.span).hi();
 401             }
 402             ast::ItemKind::Mod(ref module) => {
 403                 let is_inline = !is_mod_decl(item);
 404                 self.format_missing_with_indent(source!(self, item.span).lo());
 405                 self.format_mod(module, &item.vis, item.span, item.ident, attrs, is_inline);
 406             }
 407             ast::ItemKind::Mac(ref mac) => {
 408                 self.visit_mac(mac, Some(item.ident), MacroPosition::Item);
 409             }
 410             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 411                 self.format_missing_with_indent(source!(self, item.span).lo());
 412                 self.format_foreign_mod(foreign_mod, item.span);
 413             }
 414             ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => {
 415                 self.visit_static(&StaticParts::from_item(item));
 416             }
 417             ast::ItemKind::Fn(ref decl, fn_header, ref generics, ref body) => {
 418                 let inner_attrs = inner_attributes(&item.attrs);
 419                 self.visit_fn(
 420                     visit::FnKind::ItemFn(item.ident, fn_header, &item.vis, body),
 421                     generics,
 422                     decl,
 423                     item.span,
 424                     ast::Defaultness::Final,
 425                     Some(&inner_attrs),
 426                 )
 427             }
 428             ast::ItemKind::Ty(ref ty, ref generics) => {
 429                 let rewrite = rewrite_type_alias(
 430                     &self.get_context(),
 431                     self.block_indent,
 432                     item.ident,
 433                     ty,
 434                     generics,
 435                     &item.vis,
 436                 );
 437                 self.push_rewrite(item.span, rewrite);
 438             }
 439             ast::ItemKind::Existential(ref generic_bounds, ref generics) => {
 440                 let rewrite = rewrite_existential_type(
 441                     &self.get_context(),
 442                     self.block_indent,
 443                     item.ident,
 444                     generic_bounds,
 445                     generics,
 446                     &item.vis,
 447                 );
 448                 self.push_rewrite(item.span, rewrite);
 449             }
 450             ast::ItemKind::GlobalAsm(..) => {
 451                 let snippet = Some(self.snippet(item.span).to_owned());
 452                 self.push_rewrite(item.span, snippet);
 453             }
 454             ast::ItemKind::MacroDef(ref def) => {
 455                 let rewrite = rewrite_macro_def(
 456                     &self.get_context(),
 457                     self.shape(),
 458                     self.block_indent,
 459                     def,
 460                     item.ident,
 461                     &item.vis,
 462                     item.span,
 463                 );
 464                 self.push_rewrite(item.span, rewrite);
 465             }
 466         }
 467     }
 468
 469     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 470         skip_out_of_file_lines_range_visitor!(self, ti.span);
 471
 472         if self.visit_attrs(&ti.attrs, ast::AttrStyle::Outer) {
 473             self.push_skipped_with_span(ti.span());
 474             return;
 475         }
 476
 477         match ti.node {
 478             ast::TraitItemKind::Const(..) => self.visit_static(&StaticParts::from_trait_item(ti)),
 479             ast::TraitItemKind::Method(ref sig, None) => {
 480                 let indent = self.block_indent;
 481                 let rewrite =
 482                     self.rewrite_required_fn(indent, ti.ident, sig, &ti.generics, ti.span);
 483                 self.push_rewrite(ti.span, rewrite);
 484             }
 485             ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
 486                 let inner_attrs = inner_attributes(&ti.attrs);
 487                 self.visit_fn(
 488                     visit::FnKind::Method(ti.ident, sig, None, body),
 489                     &ti.generics,
 490                     &sig.decl,
 491                     ti.span,
 492                     ast::Defaultness::Final,
 493                     Some(&inner_attrs),
 494                 );
 495             }
 496             ast::TraitItemKind::Type(ref generic_bounds, ref type_default) => {
 497                 let rewrite = rewrite_associated_type(
 498                     ti.ident,
 499                     type_default.as_ref(),
 500                     Some(generic_bounds),
 501                     &self.get_context(),
 502                     self.block_indent,
 503                 );
 504                 self.push_rewrite(ti.span, rewrite);
 505             }
 506             ast::TraitItemKind::Macro(ref mac) => {
 507                 self.visit_mac(mac, Some(ti.ident), MacroPosition::Item);
 508             }
 509         }
 510     }
 511
 512     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 513         skip_out_of_file_lines_range_visitor!(self, ii.span);
 514
 515         if self.visit_attrs(&ii.attrs, ast::AttrStyle::Outer) {
 516             self.push_skipped_with_span(ii.span());
 517             return;
 518         }
 519
 520         match ii.node {
 521             ast::ImplItemKind::Method(ref sig, ref body) => {
 522                 let inner_attrs = inner_attributes(&ii.attrs);
 523                 self.visit_fn(
 524                     visit::FnKind::Method(ii.ident, sig, Some(&ii.vis), body),
 525                     &ii.generics,
 526                     &sig.decl,
 527                     ii.span,
 528                     ii.defaultness,
 529                     Some(&inner_attrs),
 530                 );
 531             }
 532             ast::ImplItemKind::Const(..) => self.visit_static(&StaticParts::from_impl_item(ii)),
 533             ast::ImplItemKind::Type(ref ty) => {
 534                 let rewrite = rewrite_associated_impl_type(
 535                     ii.ident,
 536                     ii.defaultness,
 537                     Some(ty),
 538                     &self.get_context(),
 539                     self.block_indent,
 540                 );
 541                 self.push_rewrite(ii.span, rewrite);
 542             }
 543             ast::ImplItemKind::Existential(ref generic_bounds) => {
 544                 let rewrite = rewrite_existential_impl_type(
 545                     &self.get_context(),
 546                     ii.ident,
 547                     generic_bounds,
 548                     self.block_indent,
 549                 );
 550                 self.push_rewrite(ii.span, rewrite);
 551             }
 552             ast::ImplItemKind::Macro(ref mac) => {
 553                 self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
 554             }
 555         }
 556     }
 557
 558     fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>, pos: MacroPosition) {
 559         skip_out_of_file_lines_range_visitor!(self, mac.span);
 560
 561         // 1 = ;
 562         let shape = self.shape().sub_width(1).unwrap();
 563         let rewrite = self.with_context(|ctx| rewrite_macro(mac, ident, ctx, shape, pos));
 564         self.push_rewrite(mac.span, rewrite);
 565     }
 566
 567     pub fn push_str(&mut self, s: &str) {
 568         self.line_number += count_newlines(s);
 569         self.buffer.push_str(s);
 570     }
 571
 572     #[cfg_attr(feature = "cargo-clippy", allow(needless_pass_by_value))]
 573     fn push_rewrite_inner(&mut self, span: Span, rewrite: Option<String>) {
 574         if let Some(ref s) = rewrite {
 575             self.push_str(s);
 576         } else {
 577             let snippet = self.snippet(span);
 578             self.push_str(snippet);
 579         }
 580         self.last_pos = source!(self, span).hi();
 581     }
 582
 583     pub fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 584         self.format_missing_with_indent(source!(self, span).lo());
 585         self.push_rewrite_inner(span, rewrite);
 586     }
 587
 588     pub fn push_skipped_with_span(&mut self, span: Span) {
 589         self.format_missing_with_indent(source!(self, span).lo());
 590         let lo = self.line_number + 1;
 591         self.push_rewrite_inner(span, None);
 592         let hi = self.line_number + 1;
 593         self.skipped_range.push((lo, hi));
 594     }
 595
 596     pub fn from_context(ctx: &'a RewriteContext) -> FmtVisitor<'a> {
 597         let mut visitor = FmtVisitor::from_source_map(
 598             ctx.parse_session,
 599             ctx.config,
 600             ctx.snippet_provider,
 601             ctx.report.clone(),
 602         );
 603         visitor.set_parent_context(ctx);
 604         visitor
 605     }
 606
 607     pub(crate) fn from_source_map(
 608         parse_session: &'a ParseSess,
 609         config: &'a Config,
 610         snippet_provider: &'a SnippetProvider,
 611         report: FormatReport,
 612     ) -> FmtVisitor<'a> {
 613         FmtVisitor {
 614             parent_context: None,
 615             parse_session,
 616             source_map: parse_session.source_map(),
 617             buffer: String::with_capacity(snippet_provider.big_snippet.len() * 2),
 618             last_pos: BytePos(0),
 619             block_indent: Indent::empty(),
 620             config,
 621             is_if_else_block: false,
 622             snippet_provider,
 623             line_number: 0,
 624             skipped_range: vec![],
 625             macro_rewrite_failure: false,
 626             report,
 627         }
 628     }
 629
 630     pub fn opt_snippet(&'b self, span: Span) -> Option<&'a str> {
 631         self.snippet_provider.span_to_snippet(span)
 632     }
 633
 634     pub fn snippet(&'b self, span: Span) -> &'a str {
 635         self.opt_snippet(span).unwrap()
 636     }
 637
 638     // Returns true if we should skip the following item.
 639     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute], style: ast::AttrStyle) -> bool {
 640         for attr in attrs {
 641             if attr.name() == DEPR_SKIP_ANNOTATION {
 642                 let file_name = self.source_map.span_to_filename(attr.span).into();
 643                 self.report.append(
 644                     file_name,
 645                     vec![FormattingError::from_span(
 646                         attr.span,
 647                         &self.source_map,
 648                         ErrorKind::DeprecatedAttr,
 649                     )],
 650                 );
 651             } else if attr.path.segments[0].ident.to_string() == "rustfmt" {
 652                 if attr.path.segments.len() == 1
 653                     || attr.path.segments[1].ident.to_string() != "skip"
 654                 {
 655                     let file_name = self.source_map.span_to_filename(attr.span).into();
 656                     self.report.append(
 657                         file_name,
 658                         vec![FormattingError::from_span(
 659                             attr.span,
 660                             &self.source_map,
 661                             ErrorKind::BadAttr,
 662                         )],
 663                     );
 664                 }
 665             }
 666         }
 667         if contains_skip(attrs) {
 668             return true;
 669         }
 670
 671         let attrs: Vec<_> = attrs.iter().filter(|a| a.style == style).cloned().collect();
 672         if attrs.is_empty() {
 673             return false;
 674         }
 675
 676         let rewrite = attrs.rewrite(&self.get_context(), self.shape());
 677         let span = mk_sp(attrs[0].span.lo(), attrs[attrs.len() - 1].span.hi());
 678         self.push_rewrite(span, rewrite);
 679
 680         false
 681     }
 682
 683     fn walk_mod_items(&mut self, m: &ast::Mod) {
 684         self.visit_items_with_reordering(&ptr_vec_to_ref_vec(&m.items));
 685     }
 686
 687     fn walk_stmts(&mut self, stmts: &[ast::Stmt]) {
 688         fn to_stmt_item(stmt: &ast::Stmt) -> Option<&ast::Item> {
 689             match stmt.node {
 690                 ast::StmtKind::Item(ref item) => Some(&**item),
 691                 _ => None,
 692             }
 693         }
 694
 695         if stmts.is_empty() {
 696             return;
 697         }
 698
 699         // Extract leading `use ...;`.
 700         let items: Vec<_> = stmts
 701             .iter()
 702             .take_while(|stmt| to_stmt_item(stmt).map_or(false, is_use_item))
 703             .filter_map(|stmt| to_stmt_item(stmt))
 704             .collect();
 705
 706         if items.is_empty() {
 707             self.visit_stmt(&stmts[0]);
 708             self.walk_stmts(&stmts[1..]);
 709         } else {
 710             self.visit_items_with_reordering(&items);
 711             self.walk_stmts(&stmts[items.len()..]);
 712         }
 713     }
 714
 715     fn walk_block_stmts(&mut self, b: &ast::Block) {
 716         self.walk_stmts(&b.stmts)
 717     }
 718
 719     fn format_mod(
 720         &mut self,
 721         m: &ast::Mod,
 722         vis: &ast::Visibility,
 723         s: Span,
 724         ident: ast::Ident,
 725         attrs: &[ast::Attribute],
 726         is_internal: bool,
 727     ) {
 728         let vis_str = utils::format_visibility(&self.get_context(), vis);
 729         self.push_str(&*vis_str);
 730         self.push_str("mod ");
 731         // Calling `to_owned()` to work around borrow checker.
 732         let ident_str = rewrite_ident(&self.get_context(), ident).to_owned();
 733         self.push_str(&ident_str);
 734
 735         if is_internal {
 736             match self.config.brace_style() {
 737                 BraceStyle::AlwaysNextLine => {
 738                     let indent_str = self.block_indent.to_string_with_newline(self.config);
 739                     self.push_str(&indent_str);
 740                     self.push_str("{");
 741                 }
 742                 _ => self.push_str(" {"),
 743             }
 744             // Hackery to account for the closing }.
 745             let mod_lo = self.snippet_provider.span_after(source!(self, s), "{");
 746             let body_snippet =
 747                 self.snippet(mk_sp(mod_lo, source!(self, m.inner).hi() - BytePos(1)));
 748             let body_snippet = body_snippet.trim();
 749             if body_snippet.is_empty() {
 750                 self.push_str("}");
 751             } else {
 752                 self.last_pos = mod_lo;
 753                 self.block_indent = self.block_indent.block_indent(self.config);
 754                 self.visit_attrs(attrs, ast::AttrStyle::Inner);
 755                 self.walk_mod_items(m);
 756                 self.format_missing_with_indent(source!(self, m.inner).hi() - BytePos(1));
 757                 self.close_block(false);
 758             }
 759             self.last_pos = source!(self, m.inner).hi();
 760         } else {
 761             self.push_str(";");
 762             self.last_pos = source!(self, s).hi();
 763         }
 764     }
 765
 766     pub fn format_separate_mod(&mut self, m: &ast::Mod, source_file: &source_map::SourceFile) {
 767         self.block_indent = Indent::empty();
 768         self.walk_mod_items(m);
 769         self.format_missing_with_indent(source_file.end_pos);
 770     }
 771
 772     pub fn skip_empty_lines(&mut self, end_pos: BytePos) {
 773         while let Some(pos) = self
 774             .snippet_provider
 775             .opt_span_after(mk_sp(self.last_pos, end_pos), "\n")
 776         {
 777             if let Some(snippet) = self.opt_snippet(mk_sp(self.last_pos, pos)) {
 778                 if snippet.trim().is_empty() {
 779                     self.last_pos = pos;
 780                 } else {
 781                     return;
 782                 }
 783             }
 784         }
 785     }
 786
 787     pub fn with_context<F>(&mut self, f: F) -> Option<String>
 788     where
 789         F: Fn(&RewriteContext) -> Option<String>,
 790     {
 791         let result;
 792         let macro_rewrite_failure = {
 793             let context = self.get_context();
 794             result = f(&context);
 795             unsafe { *context.macro_rewrite_failure.as_ptr() }
 796         };
 797         self.macro_rewrite_failure |= macro_rewrite_failure;
 798         result
 799     }
 800
 801     pub fn get_context(&self) -> RewriteContext {
 802         RewriteContext {
 803             parse_session: self.parse_session,
 804             source_map: self.source_map,
 805             config: self.config,
 806             inside_macro: RefCell::new(false),
 807             use_block: RefCell::new(false),
 808             is_if_else_block: RefCell::new(false),
 809             force_one_line_chain: RefCell::new(false),
 810             snippet_provider: self.snippet_provider,
 811             macro_rewrite_failure: RefCell::new(false),
 812             report: self.report.clone(),
 813         }
 814     }
 815 }