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     /// List of 1-based line ranges which were annotated with skip
  75     /// Both bounds are inclusifs.
  76     pub skipped_range: Vec<(usize, usize)>,
  77     pub macro_rewrite_failure: bool,
  78     pub(crate) report: FormatReport,
  79 }
  80
  81 impl<'a> Drop for FmtVisitor<'a> {
  82     fn drop(&mut self) {
  83         if let Some(ctx) = self.parent_context {
  84             if self.macro_rewrite_failure {
  85                 ctx.macro_rewrite_failure.replace(true);
  86             }
  87         }
  88     }
  89 }
  90
  91 impl<'b, 'a: 'b> FmtVisitor<'a> {
  92     fn set_parent_context(&mut self, context: &'a RewriteContext) {
  93         self.parent_context = Some(context);
  94     }
  95
  96     pub fn shape(&self) -> Shape {
  97         Shape::indented(self.block_indent, self.config)
  98     }
  99
 100     fn visit_stmt(&mut self, stmt: &ast::Stmt) {
 101         debug!(
 102             "visit_stmt: {:?} {:?}",
 103             self.source_map.lookup_char_pos(stmt.span.lo()),
 104             self.source_map.lookup_char_pos(stmt.span.hi())
 105         );
 106
 107         match stmt.node {
 108             ast::StmtKind::Item(ref item) => {
 109                 self.visit_item(item);
 110                 // Handle potential `;` after the item.
 111                 self.format_missing(stmt.span.hi());
 112             }
 113             ast::StmtKind::Local(..) | ast::StmtKind::Expr(..) | ast::StmtKind::Semi(..) => {
 114                 let attrs = get_attrs_from_stmt(stmt);
 115                 if contains_skip(attrs) {
 116                     self.push_skipped_with_span(attrs, stmt.span());
 117                 } else {
 118                     let shape = self.shape();
 119                     let rewrite = self.with_context(|ctx| stmt.rewrite(&ctx, shape));
 120                     self.push_rewrite(stmt.span(), rewrite)
 121                 }
 122             }
 123             ast::StmtKind::Mac(ref mac) => {
 124                 let (ref mac, _macro_style, ref attrs) = **mac;
 125                 if self.visit_attrs(attrs, ast::AttrStyle::Outer) {
 126                     self.push_skipped_with_span(attrs, stmt.span());
 127                 } else {
 128                     self.visit_mac(mac, None, MacroPosition::Statement);
 129                 }
 130                 self.format_missing(stmt.span.hi());
 131             }
 132         }
 133     }
 134
 135     pub fn visit_block(
 136         &mut self,
 137         b: &ast::Block,
 138         inner_attrs: Option<&[ast::Attribute]>,
 139         has_braces: bool,
 140     ) {
 141         debug!(
 142             "visit_block: {:?} {:?}",
 143             self.source_map.lookup_char_pos(b.span.lo()),
 144             self.source_map.lookup_char_pos(b.span.hi())
 145         );
 146
 147         // Check if this block has braces.
 148         let brace_compensation = BytePos(if has_braces { 1 } else { 0 });
 149
 150         self.last_pos = self.last_pos + brace_compensation;
 151         self.block_indent = self.block_indent.block_indent(self.config);
 152         self.push_str("{");
 153
 154         if let Some(first_stmt) = b.stmts.first() {
 155             let attr_lo = inner_attrs
 156                 .and_then(|attrs| inner_attributes(attrs).first().map(|attr| attr.span.lo()))
 157                 .or_else(|| {
 158                     // Attributes for an item in a statement position
 159                     // do not belong to the statement. (rust-lang/rust#34459)
 160                     if let ast::StmtKind::Item(ref item) = first_stmt.node {
 161                         item.attrs.first()
 162                     } else {
 163                         first_stmt.attrs().first()
 164                     }
 165                     .and_then(|attr| {
 166                         // Some stmts can have embedded attributes.
 167                         // e.g. `match { #![attr] ... }`
 168                         let attr_lo = attr.span.lo();
 169                         if attr_lo < first_stmt.span.lo() {
 170                             Some(attr_lo)
 171                         } else {
 172                             None
 173                         }
 174                     })
 175                 });
 176
 177             let snippet = self.snippet(mk_sp(
 178                 self.last_pos,
 179                 attr_lo.unwrap_or_else(|| first_stmt.span.lo()),
 180             ));
 181             let len = CommentCodeSlices::new(snippet)
 182                 .nth(0)
 183                 .and_then(|(kind, _, s)| {
 184                     if kind == CodeCharKind::Normal {
 185                         s.rfind('\n')
 186                     } else {
 187                         None
 188                     }
 189                 });
 190             if let Some(len) = len {
 191                 self.last_pos = self.last_pos + BytePos::from_usize(len);
 192             }
 193         }
 194
 195         // Format inner attributes if available.
 196         let skip_rewrite = if let Some(attrs) = inner_attrs {
 197             self.visit_attrs(attrs, ast::AttrStyle::Inner)
 198         } else {
 199             false
 200         };
 201
 202         if skip_rewrite {
 203             self.push_rewrite(b.span, None);
 204             self.close_block(false);
 205             self.last_pos = source!(self, b.span).hi();
 206             return;
 207         }
 208
 209         self.walk_block_stmts(b);
 210
 211         if !b.stmts.is_empty() {
 212             if let Some(expr) = utils::stmt_expr(&b.stmts[b.stmts.len() - 1]) {
 213                 if utils::semicolon_for_expr(&self.get_context(), expr) {
 214                     self.push_str(";");
 215                 }
 216             }
 217         }
 218
 219         let mut remove_len = BytePos(0);
 220         if let Some(stmt) = b.stmts.last() {
 221             let snippet = self.snippet(mk_sp(
 222                 stmt.span.hi(),
 223                 source!(self, b.span).hi() - brace_compensation,
 224             ));
 225             let len = CommentCodeSlices::new(snippet)
 226                 .last()
 227                 .and_then(|(kind, _, s)| {
 228                     if kind == CodeCharKind::Normal && s.trim().is_empty() {
 229                         Some(s.len())
 230                     } else {
 231                         None
 232                     }
 233                 });
 234             if let Some(len) = len {
 235                 remove_len = BytePos::from_usize(len);
 236             }
 237         }
 238
 239         let unindent_comment = (self.is_if_else_block && !b.stmts.is_empty()) && {
 240             let end_pos = source!(self, b.span).hi() - brace_compensation - remove_len;
 241             let snippet = self.snippet(mk_sp(self.last_pos, end_pos));
 242             snippet.contains("//") || snippet.contains("/*")
 243         };
 244         // FIXME: we should compress any newlines here to just one
 245         if unindent_comment {
 246             self.block_indent = self.block_indent.block_unindent(self.config);
 247         }
 248         self.format_missing_with_indent(
 249             source!(self, b.span).hi() - brace_compensation - remove_len,
 250         );
 251         if unindent_comment {
 252             self.block_indent = self.block_indent.block_indent(self.config);
 253         }
 254         self.close_block(unindent_comment);
 255         self.last_pos = source!(self, b.span).hi();
 256     }
 257
 258     // FIXME: this is a terrible hack to indent the comments between the last
 259     // item in the block and the closing brace to the block's level.
 260     // The closing brace itself, however, should be indented at a shallower
 261     // level.
 262     fn close_block(&mut self, unindent_comment: bool) {
 263         let total_len = self.buffer.len();
 264         let chars_too_many = if unindent_comment {
 265             0
 266         } else if self.config.hard_tabs() {
 267             1
 268         } else {
 269             self.config.tab_spaces()
 270         };
 271         self.buffer.truncate(total_len - chars_too_many);
 272         self.push_str("}");
 273         self.block_indent = self.block_indent.block_unindent(self.config);
 274     }
 275
 276     // Note that this only gets called for function definitions. Required methods
 277     // on traits do not get handled here.
 278     fn visit_fn(
 279         &mut self,
 280         fk: visit::FnKind,
 281         generics: &ast::Generics,
 282         fd: &ast::FnDecl,
 283         s: Span,
 284         defaultness: ast::Defaultness,
 285         inner_attrs: Option<&[ast::Attribute]>,
 286     ) {
 287         let indent = self.block_indent;
 288         let block;
 289         let rewrite = match fk {
 290             visit::FnKind::ItemFn(ident, _, _, b) | visit::FnKind::Method(ident, _, _, b) => {
 291                 block = b;
 292                 self.rewrite_fn(
 293                     indent,
 294                     ident,
 295                     &FnSig::from_fn_kind(&fk, generics, fd, defaultness),
 296                     mk_sp(s.lo(), b.span.lo()),
 297                     b,
 298                     inner_attrs,
 299                 )
 300             }
 301             visit::FnKind::Closure(_) => unreachable!(),
 302         };
 303
 304         if let Some(fn_str) = rewrite {
 305             self.format_missing_with_indent(source!(self, s).lo());
 306             self.push_str(&fn_str);
 307             if let Some(c) = fn_str.chars().last() {
 308                 if c == '}' {
 309                     self.last_pos = source!(self, block.span).hi();
 310                     return;
 311                 }
 312             }
 313         } else {
 314             self.format_missing(source!(self, block.span).lo());
 315         }
 316
 317         self.last_pos = source!(self, block.span).lo();
 318         self.visit_block(block, inner_attrs, true)
 319     }
 320
 321     pub fn visit_item(&mut self, item: &ast::Item) {
 322         skip_out_of_file_lines_range_visitor!(self, item.span);
 323
 324         // This is where we bail out if there is a skip attribute. This is only
 325         // complex in the module case. It is complex because the module could be
 326         // in a separate file and there might be attributes in both files, but
 327         // the AST lumps them all together.
 328         let filtered_attrs;
 329         let mut attrs = &item.attrs;
 330         match item.node {
 331             // For use items, skip rewriting attributes. Just check for a skip attribute.
 332             ast::ItemKind::Use(..) => {
 333                 if contains_skip(attrs) {
 334                     self.push_skipped_with_span(attrs.as_slice(), item.span());
 335                     return;
 336                 }
 337             }
 338             // Module is inline, in this case we treat it like any other item.
 339             _ if !is_mod_decl(item) => {
 340                 if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
 341                     self.push_skipped_with_span(item.attrs.as_slice(), item.span());
 342                     return;
 343                 }
 344             }
 345             // Module is not inline, but should be skipped.
 346             ast::ItemKind::Mod(..) if contains_skip(&item.attrs) => {
 347                 return;
 348             }
 349             // Module is not inline and should not be skipped. We want
 350             // to process only the attributes in the current file.
 351             ast::ItemKind::Mod(..) => {
 352                 filtered_attrs = filter_inline_attrs(&item.attrs, item.span());
 353                 // Assert because if we should skip it should be caught by
 354                 // the above case.
 355                 assert!(!self.visit_attrs(&filtered_attrs, ast::AttrStyle::Outer));
 356                 attrs = &filtered_attrs;
 357             }
 358             _ => {
 359                 if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
 360                     self.push_skipped_with_span(item.attrs.as_slice(), item.span());
 361                     return;
 362                 }
 363             }
 364         }
 365
 366         match item.node {
 367             ast::ItemKind::Use(ref tree) => self.format_import(item, tree),
 368             ast::ItemKind::Impl(..) => {
 369                 let snippet = self.snippet(item.span);
 370                 let where_span_end = snippet
 371                     .find_uncommented("{")
 372                     .map(|x| BytePos(x as u32) + source!(self, item.span).lo());
 373                 let block_indent = self.block_indent;
 374                 let rw =
 375                     self.with_context(|ctx| format_impl(&ctx, item, block_indent, where_span_end));
 376                 self.push_rewrite(item.span, rw);
 377             }
 378             ast::ItemKind::Trait(..) => {
 379                 let block_indent = self.block_indent;
 380                 let rw = self.with_context(|ctx| format_trait(&ctx, item, block_indent));
 381                 self.push_rewrite(item.span, rw);
 382             }
 383             ast::ItemKind::TraitAlias(ref generics, ref generic_bounds) => {
 384                 let shape = Shape::indented(self.block_indent, self.config);
 385                 let rw = format_trait_alias(
 386                     &self.get_context(),
 387                     item.ident,
 388                     generics,
 389                     generic_bounds,
 390                     shape,
 391                 );
 392                 self.push_rewrite(item.span, rw);
 393             }
 394             ast::ItemKind::ExternCrate(_) => {
 395                 let rw = rewrite_extern_crate(&self.get_context(), item);
 396                 self.push_rewrite(item.span, rw);
 397             }
 398             ast::ItemKind::Struct(..) | ast::ItemKind::Union(..) => {
 399                 self.visit_struct(&StructParts::from_item(item));
 400             }
 401             ast::ItemKind::Enum(ref def, ref generics) => {
 402                 self.format_missing_with_indent(source!(self, item.span).lo());
 403                 self.visit_enum(item.ident, &item.vis, def, generics, item.span);
 404                 self.last_pos = source!(self, item.span).hi();
 405             }
 406             ast::ItemKind::Mod(ref module) => {
 407                 let is_inline = !is_mod_decl(item);
 408                 self.format_missing_with_indent(source!(self, item.span).lo());
 409                 self.format_mod(module, &item.vis, item.span, item.ident, attrs, is_inline);
 410             }
 411             ast::ItemKind::Mac(ref mac) => {
 412                 self.visit_mac(mac, Some(item.ident), MacroPosition::Item);
 413             }
 414             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 415                 self.format_missing_with_indent(source!(self, item.span).lo());
 416                 self.format_foreign_mod(foreign_mod, item.span);
 417             }
 418             ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => {
 419                 self.visit_static(&StaticParts::from_item(item));
 420             }
 421             ast::ItemKind::Fn(ref decl, fn_header, ref generics, ref body) => {
 422                 let inner_attrs = inner_attributes(&item.attrs);
 423                 self.visit_fn(
 424                     visit::FnKind::ItemFn(item.ident, fn_header, &item.vis, body),
 425                     generics,
 426                     decl,
 427                     item.span,
 428                     ast::Defaultness::Final,
 429                     Some(&inner_attrs),
 430                 )
 431             }
 432             ast::ItemKind::Ty(ref ty, ref generics) => {
 433                 let rewrite = rewrite_type_alias(
 434                     &self.get_context(),
 435                     self.block_indent,
 436                     item.ident,
 437                     ty,
 438                     generics,
 439                     &item.vis,
 440                 );
 441                 self.push_rewrite(item.span, rewrite);
 442             }
 443             ast::ItemKind::Existential(ref generic_bounds, ref generics) => {
 444                 let rewrite = rewrite_existential_type(
 445                     &self.get_context(),
 446                     self.block_indent,
 447                     item.ident,
 448                     generic_bounds,
 449                     generics,
 450                     &item.vis,
 451                 );
 452                 self.push_rewrite(item.span, rewrite);
 453             }
 454             ast::ItemKind::GlobalAsm(..) => {
 455                 let snippet = Some(self.snippet(item.span).to_owned());
 456                 self.push_rewrite(item.span, snippet);
 457             }
 458             ast::ItemKind::MacroDef(ref def) => {
 459                 let rewrite = rewrite_macro_def(
 460                     &self.get_context(),
 461                     self.shape(),
 462                     self.block_indent,
 463                     def,
 464                     item.ident,
 465                     &item.vis,
 466                     item.span,
 467                 );
 468                 self.push_rewrite(item.span, rewrite);
 469             }
 470         }
 471     }
 472
 473     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 474         skip_out_of_file_lines_range_visitor!(self, ti.span);
 475
 476         if self.visit_attrs(&ti.attrs, ast::AttrStyle::Outer) {
 477             self.push_skipped_with_span(ti.attrs.as_slice(), ti.span());
 478             return;
 479         }
 480
 481         match ti.node {
 482             ast::TraitItemKind::Const(..) => self.visit_static(&StaticParts::from_trait_item(ti)),
 483             ast::TraitItemKind::Method(ref sig, None) => {
 484                 let indent = self.block_indent;
 485                 let rewrite =
 486                     self.rewrite_required_fn(indent, ti.ident, sig, &ti.generics, ti.span);
 487                 self.push_rewrite(ti.span, rewrite);
 488             }
 489             ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
 490                 let inner_attrs = inner_attributes(&ti.attrs);
 491                 self.visit_fn(
 492                     visit::FnKind::Method(ti.ident, sig, None, body),
 493                     &ti.generics,
 494                     &sig.decl,
 495                     ti.span,
 496                     ast::Defaultness::Final,
 497                     Some(&inner_attrs),
 498                 );
 499             }
 500             ast::TraitItemKind::Type(ref generic_bounds, ref type_default) => {
 501                 let rewrite = rewrite_associated_type(
 502                     ti.ident,
 503                     type_default.as_ref(),
 504                     &ti.generics,
 505                     Some(generic_bounds),
 506                     &self.get_context(),
 507                     self.block_indent,
 508                 );
 509                 self.push_rewrite(ti.span, rewrite);
 510             }
 511             ast::TraitItemKind::Macro(ref mac) => {
 512                 self.visit_mac(mac, Some(ti.ident), MacroPosition::Item);
 513             }
 514         }
 515     }
 516
 517     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 518         skip_out_of_file_lines_range_visitor!(self, ii.span);
 519
 520         if self.visit_attrs(&ii.attrs, ast::AttrStyle::Outer) {
 521             self.push_skipped_with_span(ii.attrs.as_slice(), ii.span());
 522             return;
 523         }
 524
 525         match ii.node {
 526             ast::ImplItemKind::Method(ref sig, ref body) => {
 527                 let inner_attrs = inner_attributes(&ii.attrs);
 528                 self.visit_fn(
 529                     visit::FnKind::Method(ii.ident, sig, Some(&ii.vis), body),
 530                     &ii.generics,
 531                     &sig.decl,
 532                     ii.span,
 533                     ii.defaultness,
 534                     Some(&inner_attrs),
 535                 );
 536             }
 537             ast::ImplItemKind::Const(..) => self.visit_static(&StaticParts::from_impl_item(ii)),
 538             ast::ImplItemKind::Type(ref ty) => {
 539                 let rewrite = rewrite_associated_impl_type(
 540                     ii.ident,
 541                     ii.defaultness,
 542                     Some(ty),
 543                     &ii.generics,
 544                     &self.get_context(),
 545                     self.block_indent,
 546                 );
 547                 self.push_rewrite(ii.span, rewrite);
 548             }
 549             ast::ImplItemKind::Existential(ref generic_bounds) => {
 550                 let rewrite = rewrite_existential_impl_type(
 551                     &self.get_context(),
 552                     ii.ident,
 553                     &ii.generics,
 554                     generic_bounds,
 555                     self.block_indent,
 556                 );
 557                 self.push_rewrite(ii.span, rewrite);
 558             }
 559             ast::ImplItemKind::Macro(ref mac) => {
 560                 self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
 561             }
 562         }
 563     }
 564
 565     fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>, pos: MacroPosition) {
 566         skip_out_of_file_lines_range_visitor!(self, mac.span);
 567
 568         // 1 = ;
 569         let shape = self.shape().sub_width(1).unwrap();
 570         let rewrite = self.with_context(|ctx| rewrite_macro(mac, ident, ctx, shape, pos));
 571         self.push_rewrite(mac.span, rewrite);
 572     }
 573
 574     pub fn push_str(&mut self, s: &str) {
 575         self.line_number += count_newlines(s);
 576         self.buffer.push_str(s);
 577     }
 578
 579     #[allow(clippy::needless_pass_by_value)]
 580     fn push_rewrite_inner(&mut self, span: Span, rewrite: Option<String>) {
 581         if let Some(ref s) = rewrite {
 582             self.push_str(s);
 583         } else {
 584             let snippet = self.snippet(span);
 585             self.push_str(snippet);
 586         }
 587         self.last_pos = source!(self, span).hi();
 588     }
 589
 590     pub fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 591         self.format_missing_with_indent(source!(self, span).lo());
 592         self.push_rewrite_inner(span, rewrite);
 593     }
 594
 595     pub fn push_skipped_with_span(&mut self, attrs: &[ast::Attribute], item_span: Span) {
 596         self.format_missing_with_indent(source!(self, item_span).lo());
 597         // do not take into account the lines with attributes as part of the skipped range
 598         let attrs_end = attrs
 599             .iter()
 600             .map(|attr| self.source_map.lookup_char_pos(attr.span().hi()).line)
 601             .max()
 602             .unwrap_or(1);
 603         // Add 1 to get the line past the last attribute
 604         let lo = attrs_end + 1;
 605         self.push_rewrite_inner(item_span, None);
 606         let hi = self.line_number + 1;
 607         self.skipped_range.push((lo, hi));
 608     }
 609
 610     pub fn from_context(ctx: &'a RewriteContext) -> FmtVisitor<'a> {
 611         let mut visitor = FmtVisitor::from_source_map(
 612             ctx.parse_session,
 613             ctx.config,
 614             ctx.snippet_provider,
 615             ctx.report.clone(),
 616         );
 617         visitor.set_parent_context(ctx);
 618         visitor
 619     }
 620
 621     pub(crate) fn from_source_map(
 622         parse_session: &'a ParseSess,
 623         config: &'a Config,
 624         snippet_provider: &'a SnippetProvider,
 625         report: FormatReport,
 626     ) -> FmtVisitor<'a> {
 627         FmtVisitor {
 628             parent_context: None,
 629             parse_session,
 630             source_map: parse_session.source_map(),
 631             buffer: String::with_capacity(snippet_provider.big_snippet.len() * 2),
 632             last_pos: BytePos(0),
 633             block_indent: Indent::empty(),
 634             config,
 635             is_if_else_block: false,
 636             snippet_provider,
 637             line_number: 0,
 638             skipped_range: vec![],
 639             macro_rewrite_failure: false,
 640             report,
 641         }
 642     }
 643
 644     pub fn opt_snippet(&'b self, span: Span) -> Option<&'a str> {
 645         self.snippet_provider.span_to_snippet(span)
 646     }
 647
 648     pub fn snippet(&'b self, span: Span) -> &'a str {
 649         self.opt_snippet(span).unwrap()
 650     }
 651
 652     // Returns true if we should skip the following item.
 653     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute], style: ast::AttrStyle) -> bool {
 654         for attr in attrs {
 655             if attr.name() == DEPR_SKIP_ANNOTATION {
 656                 let file_name = self.source_map.span_to_filename(attr.span).into();
 657                 self.report.append(
 658                     file_name,
 659                     vec![FormattingError::from_span(
 660                         attr.span,
 661                         &self.source_map,
 662                         ErrorKind::DeprecatedAttr,
 663                     )],
 664                 );
 665             } else if attr.path.segments[0].ident.to_string() == "rustfmt"
 666                 && (attr.path.segments.len() == 1
 667                     || attr.path.segments[1].ident.to_string() != "skip")
 668             {
 669                 let file_name = self.source_map.span_to_filename(attr.span).into();
 670                 self.report.append(
 671                     file_name,
 672                     vec![FormattingError::from_span(
 673                         attr.span,
 674                         &self.source_map,
 675                         ErrorKind::BadAttr,
 676                     )],
 677                 );
 678             }
 679         }
 680         if contains_skip(attrs) {
 681             return true;
 682         }
 683
 684         let attrs: Vec<_> = attrs.iter().filter(|a| a.style == style).cloned().collect();
 685         if attrs.is_empty() {
 686             return false;
 687         }
 688
 689         let rewrite = attrs.rewrite(&self.get_context(), self.shape());
 690         let span = mk_sp(attrs[0].span.lo(), attrs[attrs.len() - 1].span.hi());
 691         self.push_rewrite(span, rewrite);
 692
 693         false
 694     }
 695
 696     fn walk_mod_items(&mut self, m: &ast::Mod) {
 697         self.visit_items_with_reordering(&ptr_vec_to_ref_vec(&m.items));
 698     }
 699
 700     fn walk_stmts(&mut self, stmts: &[ast::Stmt]) {
 701         fn to_stmt_item(stmt: &ast::Stmt) -> Option<&ast::Item> {
 702             match stmt.node {
 703                 ast::StmtKind::Item(ref item) => Some(&**item),
 704                 _ => None,
 705             }
 706         }
 707
 708         if stmts.is_empty() {
 709             return;
 710         }
 711
 712         // Extract leading `use ...;`.
 713         let items: Vec<_> = stmts
 714             .iter()
 715             .take_while(|stmt| to_stmt_item(stmt).map_or(false, is_use_item))
 716             .filter_map(|stmt| to_stmt_item(stmt))
 717             .collect();
 718
 719         if items.is_empty() {
 720             self.visit_stmt(&stmts[0]);
 721             self.walk_stmts(&stmts[1..]);
 722         } else {
 723             self.visit_items_with_reordering(&items);
 724             self.walk_stmts(&stmts[items.len()..]);
 725         }
 726     }
 727
 728     fn walk_block_stmts(&mut self, b: &ast::Block) {
 729         self.walk_stmts(&b.stmts)
 730     }
 731
 732     fn format_mod(
 733         &mut self,
 734         m: &ast::Mod,
 735         vis: &ast::Visibility,
 736         s: Span,
 737         ident: ast::Ident,
 738         attrs: &[ast::Attribute],
 739         is_internal: bool,
 740     ) {
 741         let vis_str = utils::format_visibility(&self.get_context(), vis);
 742         self.push_str(&*vis_str);
 743         self.push_str("mod ");
 744         // Calling `to_owned()` to work around borrow checker.
 745         let ident_str = rewrite_ident(&self.get_context(), ident).to_owned();
 746         self.push_str(&ident_str);
 747
 748         if is_internal {
 749             match self.config.brace_style() {
 750                 BraceStyle::AlwaysNextLine => {
 751                     let indent_str = self.block_indent.to_string_with_newline(self.config);
 752                     self.push_str(&indent_str);
 753                     self.push_str("{");
 754                 }
 755                 _ => self.push_str(" {"),
 756             }
 757             // Hackery to account for the closing }.
 758             let mod_lo = self.snippet_provider.span_after(source!(self, s), "{");
 759             let body_snippet =
 760                 self.snippet(mk_sp(mod_lo, source!(self, m.inner).hi() - BytePos(1)));
 761             let body_snippet = body_snippet.trim();
 762             if body_snippet.is_empty() {
 763                 self.push_str("}");
 764             } else {
 765                 self.last_pos = mod_lo;
 766                 self.block_indent = self.block_indent.block_indent(self.config);
 767                 self.visit_attrs(attrs, ast::AttrStyle::Inner);
 768                 self.walk_mod_items(m);
 769                 self.format_missing_with_indent(source!(self, m.inner).hi() - BytePos(1));
 770                 self.close_block(false);
 771             }
 772             self.last_pos = source!(self, m.inner).hi();
 773         } else {
 774             self.push_str(";");
 775             self.last_pos = source!(self, s).hi();
 776         }
 777     }
 778
 779     pub fn format_separate_mod(&mut self, m: &ast::Mod, source_file: &source_map::SourceFile) {
 780         self.block_indent = Indent::empty();
 781         self.walk_mod_items(m);
 782         self.format_missing_with_indent(source_file.end_pos);
 783     }
 784
 785     pub fn skip_empty_lines(&mut self, end_pos: BytePos) {
 786         while let Some(pos) = self
 787             .snippet_provider
 788             .opt_span_after(mk_sp(self.last_pos, end_pos), "\n")
 789         {
 790             if let Some(snippet) = self.opt_snippet(mk_sp(self.last_pos, pos)) {
 791                 if snippet.trim().is_empty() {
 792                     self.last_pos = pos;
 793                 } else {
 794                     return;
 795                 }
 796             }
 797         }
 798     }
 799
 800     pub fn with_context<F>(&mut self, f: F) -> Option<String>
 801     where
 802         F: Fn(&RewriteContext) -> Option<String>,
 803     {
 804         // FIXME borrow checker fighting - can be simplified a lot with NLL.
 805         let (result, mrf) = {
 806             let context = self.get_context();
 807             let result = f(&context);
 808             let mrf = &context.macro_rewrite_failure.borrow();
 809             (result, *std::ops::Deref::deref(mrf))
 810         };
 811
 812         self.macro_rewrite_failure |= mrf;
 813         result
 814     }
 815
 816     pub fn get_context(&self) -> RewriteContext {
 817         RewriteContext {
 818             parse_session: self.parse_session,
 819             source_map: self.source_map,
 820             config: self.config,
 821             inside_macro: RefCell::new(false),
 822             use_block: RefCell::new(false),
 823             is_if_else_block: RefCell::new(false),
 824             force_one_line_chain: RefCell::new(false),
 825             snippet_provider: self.snippet_provider,
 826             macro_rewrite_failure: RefCell::new(false),
 827             report: self.report.clone(),
 828         }
 829     }
 830 }