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 std::cmp;
  12
  13 use strings::string_buffer::StringBuffer;
  14 use syntax::{ast, ptr, visit};
  15 use syntax::attr::HasAttrs;
  16 use syntax::codemap::{self, BytePos, CodeMap, Pos, Span};
  17 use syntax::parse::ParseSess;
  18
  19 use {Indent, Shape, Spanned};
  20 use codemap::{LineRangeUtils, SpanUtils};
  21 use comment::{contains_comment, recover_missing_comment_in_span, CodeCharKind, CommentCodeSlices,
  22               FindUncommented};
  23 use comment::rewrite_comment;
  24 use config::{BraceStyle, Config};
  25 use items::{format_impl, format_trait, rewrite_associated_impl_type, rewrite_associated_type,
  26             rewrite_static, rewrite_type_alias};
  27 use lists::{itemize_list, write_list, DefinitiveListTactic, ListFormatting, SeparatorPlace,
  28             SeparatorTactic};
  29 use macros::{rewrite_macro, MacroPosition};
  30 use regex::Regex;
  31 use rewrite::{Rewrite, RewriteContext};
  32 use utils::{self, contains_skip, inner_attributes, mk_sp};
  33
  34 fn is_use_item(item: &ast::Item) -> bool {
  35     match item.node {
  36         ast::ItemKind::Use(_) => true,
  37         _ => false,
  38     }
  39 }
  40
  41 fn is_extern_crate(item: &ast::Item) -> bool {
  42     match item.node {
  43         ast::ItemKind::ExternCrate(..) => true,
  44         _ => false,
  45     }
  46 }
  47
  48 pub struct FmtVisitor<'a> {
  49     pub parse_session: &'a ParseSess,
  50     pub codemap: &'a CodeMap,
  51     pub buffer: StringBuffer,
  52     pub last_pos: BytePos,
  53     // FIXME: use an RAII util or closure for indenting
  54     pub block_indent: Indent,
  55     pub config: &'a Config,
  56     pub is_if_else_block: bool,
  57 }
  58
  59 impl<'a> FmtVisitor<'a> {
  60     pub fn shape(&self) -> Shape {
  61         Shape::indented(self.block_indent, self.config)
  62     }
  63
  64     fn visit_stmt(&mut self, stmt: &ast::Stmt) {
  65         debug!(
  66             "visit_stmt: {:?} {:?}",
  67             self.codemap.lookup_char_pos(stmt.span.lo()),
  68             self.codemap.lookup_char_pos(stmt.span.hi())
  69         );
  70
  71         match stmt.node {
  72             ast::StmtKind::Item(ref item) => {
  73                 self.visit_item(item);
  74             }
  75             ast::StmtKind::Local(..) => {
  76                 let rewrite = stmt.rewrite(&self.get_context(), self.shape());
  77                 self.push_rewrite(stmt.span(), rewrite);
  78             }
  79             ast::StmtKind::Expr(..) | ast::StmtKind::Semi(..) => {
  80                 let rewrite = stmt.rewrite(&self.get_context(), self.shape());
  81                 self.push_rewrite(stmt.span(), rewrite)
  82             }
  83             ast::StmtKind::Mac(ref mac) => {
  84                 let (ref mac, _macro_style, ref attrs) = **mac;
  85                 if self.visit_attrs(attrs, ast::AttrStyle::Outer) {
  86                     self.push_rewrite(stmt.span(), None);
  87                 } else {
  88                     self.visit_mac(mac, None, MacroPosition::Statement);
  89                 }
  90                 self.format_missing(stmt.span.hi());
  91             }
  92         }
  93     }
  94
  95     pub fn visit_block(&mut self, b: &ast::Block, inner_attrs: Option<&[ast::Attribute]>) {
  96         debug!(
  97             "visit_block: {:?} {:?}",
  98             self.codemap.lookup_char_pos(b.span.lo()),
  99             self.codemap.lookup_char_pos(b.span.hi())
 100         );
 101
 102         // Check if this block has braces.
 103         let snippet = self.snippet(b.span);
 104         let has_braces = snippet.starts_with('{') || snippet.starts_with("unsafe");
 105         let brace_compensation = if has_braces { BytePos(1) } else { BytePos(0) };
 106
 107         self.last_pos = self.last_pos + brace_compensation;
 108         self.block_indent = self.block_indent.block_indent(self.config);
 109         self.buffer.push_str("{");
 110
 111         if self.config.remove_blank_lines_at_start_or_end_of_block() {
 112             if let Some(first_stmt) = b.stmts.first() {
 113                 let attr_lo = inner_attrs
 114                     .and_then(|attrs| {
 115                         inner_attributes(attrs).first().map(|attr| attr.span.lo())
 116                     })
 117                     .or_else(|| {
 118                         // Attributes for an item in a statement position
 119                         // do not belong to the statement. (rust-lang/rust#34459)
 120                         if let ast::StmtKind::Item(ref item) = first_stmt.node {
 121                             item.attrs.first()
 122                         } else {
 123                             first_stmt.attrs().first()
 124                         }.and_then(|attr| {
 125                             // Some stmts can have embedded attributes.
 126                             // e.g. `match { #![attr] ... }`
 127                             let attr_lo = attr.span.lo();
 128                             if attr_lo < first_stmt.span.lo() {
 129                                 Some(attr_lo)
 130                             } else {
 131                                 None
 132                             }
 133                         })
 134                     });
 135
 136                 let snippet = self.snippet(mk_sp(
 137                     self.last_pos,
 138                     attr_lo.unwrap_or(first_stmt.span.lo()),
 139                 ));
 140                 let len = CommentCodeSlices::new(&snippet).nth(0).and_then(
 141                     |(kind, _, s)| if kind == CodeCharKind::Normal {
 142                         s.rfind('\n')
 143                     } else {
 144                         None
 145                     },
 146                 );
 147                 if let Some(len) = len {
 148                     self.last_pos = self.last_pos + BytePos::from_usize(len);
 149                 }
 150             }
 151         }
 152
 153         // Format inner attributes if available.
 154         if let Some(attrs) = inner_attrs {
 155             self.visit_attrs(attrs, ast::AttrStyle::Inner);
 156         }
 157
 158         for stmt in &b.stmts {
 159             self.visit_stmt(stmt)
 160         }
 161
 162         if !b.stmts.is_empty() {
 163             if let Some(expr) = utils::stmt_expr(&b.stmts[b.stmts.len() - 1]) {
 164                 if utils::semicolon_for_expr(&self.get_context(), expr) {
 165                     self.buffer.push_str(";");
 166                 }
 167             }
 168         }
 169
 170         let mut remove_len = BytePos(0);
 171         if self.config.remove_blank_lines_at_start_or_end_of_block() {
 172             if let Some(stmt) = b.stmts.last() {
 173                 let snippet = self.snippet(mk_sp(
 174                     stmt.span.hi(),
 175                     source!(self, b.span).hi() - brace_compensation,
 176                 ));
 177                 let len = CommentCodeSlices::new(&snippet)
 178                     .last()
 179                     .and_then(|(kind, _, s)| {
 180                         if kind == CodeCharKind::Normal && s.trim().is_empty() {
 181                             Some(s.len())
 182                         } else {
 183                             None
 184                         }
 185                     });
 186                 if let Some(len) = len {
 187                     remove_len = BytePos::from_usize(len);
 188                 }
 189             }
 190         }
 191
 192         let mut unindent_comment = self.is_if_else_block && !b.stmts.is_empty();
 193         if unindent_comment {
 194             let end_pos = source!(self, b.span).hi() - brace_compensation - remove_len;
 195             let snippet = self.snippet(mk_sp(self.last_pos, end_pos));
 196             unindent_comment = snippet.contains("//") || snippet.contains("/*");
 197         }
 198         // FIXME: we should compress any newlines here to just one
 199         if unindent_comment {
 200             self.block_indent = self.block_indent.block_unindent(self.config);
 201         }
 202         self.format_missing_with_indent(
 203             source!(self, b.span).hi() - brace_compensation - remove_len,
 204         );
 205         if unindent_comment {
 206             self.block_indent = self.block_indent.block_indent(self.config);
 207         }
 208         self.close_block(unindent_comment);
 209         self.last_pos = source!(self, b.span).hi();
 210     }
 211
 212     // FIXME: this is a terrible hack to indent the comments between the last
 213     // item in the block and the closing brace to the block's level.
 214     // The closing brace itself, however, should be indented at a shallower
 215     // level.
 216     fn close_block(&mut self, unindent_comment: bool) {
 217         let total_len = self.buffer.len;
 218         let chars_too_many = if unindent_comment {
 219             0
 220         } else if self.config.hard_tabs() {
 221             1
 222         } else {
 223             self.config.tab_spaces()
 224         };
 225         self.buffer.truncate(total_len - chars_too_many);
 226         self.buffer.push_str("}");
 227         self.block_indent = self.block_indent.block_unindent(self.config);
 228     }
 229
 230     // Note that this only gets called for function definitions. Required methods
 231     // on traits do not get handled here.
 232     fn visit_fn(
 233         &mut self,
 234         fk: visit::FnKind,
 235         fd: &ast::FnDecl,
 236         s: Span,
 237         _: ast::NodeId,
 238         defaultness: ast::Defaultness,
 239         inner_attrs: Option<&[ast::Attribute]>,
 240     ) {
 241         let indent = self.block_indent;
 242         let block;
 243         let rewrite = match fk {
 244             visit::FnKind::ItemFn(ident, generics, unsafety, constness, abi, vis, b) => {
 245                 block = b;
 246                 self.rewrite_fn(
 247                     indent,
 248                     ident,
 249                     fd,
 250                     generics,
 251                     unsafety,
 252                     constness.node,
 253                     defaultness,
 254                     abi,
 255                     vis,
 256                     mk_sp(s.lo(), b.span.lo()),
 257                     b,
 258                 )
 259             }
 260             visit::FnKind::Method(ident, sig, vis, b) => {
 261                 block = b;
 262                 self.rewrite_fn(
 263                     indent,
 264                     ident,
 265                     fd,
 266                     &sig.generics,
 267                     sig.unsafety,
 268                     sig.constness.node,
 269                     defaultness,
 270                     sig.abi,
 271                     vis.unwrap_or(&ast::Visibility::Inherited),
 272                     mk_sp(s.lo(), b.span.lo()),
 273                     b,
 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.buffer.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)
 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 mut attrs = item.attrs.clone();
 304         match item.node {
 305             ast::ItemKind::Mod(ref m) => {
 306                 let outer_file = self.codemap.lookup_char_pos(item.span.lo()).file;
 307                 let inner_file = self.codemap.lookup_char_pos(m.inner.lo()).file;
 308                 if outer_file.name == inner_file.name {
 309                     // Module is inline, in this case we treat modules like any
 310                     // other item.
 311                     if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
 312                         self.push_rewrite(item.span, None);
 313                         return;
 314                     }
 315                 } else if contains_skip(&item.attrs) {
 316                     // Module is not inline, but should be skipped.
 317                     return;
 318                 } else {
 319                     // Module is not inline and should not be skipped. We want
 320                     // to process only the attributes in the current file.
 321                     let filterd_attrs = item.attrs
 322                         .iter()
 323                         .filter_map(|a| {
 324                             let attr_file = self.codemap.lookup_char_pos(a.span.lo()).file;
 325                             if attr_file.name == outer_file.name {
 326                                 Some(a.clone())
 327                             } else {
 328                                 None
 329                             }
 330                         })
 331                         .collect::<Vec<_>>();
 332                     // Assert because if we should skip it should be caught by
 333                     // the above case.
 334                     assert!(!self.visit_attrs(&filterd_attrs, ast::AttrStyle::Outer));
 335                     attrs = filterd_attrs;
 336                 }
 337             }
 338             _ => if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
 339                 self.push_rewrite(item.span, None);
 340                 return;
 341             },
 342         }
 343
 344         match item.node {
 345             ast::ItemKind::Use(ref vp) => {
 346                 self.format_import(&item.vis, vp, item.span, &item.attrs);
 347             }
 348             ast::ItemKind::Impl(..) => {
 349                 self.format_missing_with_indent(source!(self, item.span).lo());
 350                 let snippet = self.snippet(item.span);
 351                 let where_span_end = snippet
 352                     .find_uncommented("{")
 353                     .map(|x| (BytePos(x as u32)) + source!(self, item.span).lo());
 354                 if let Some(impl_str) =
 355                     format_impl(&self.get_context(), item, self.block_indent, where_span_end)
 356                 {
 357                     self.buffer.push_str(&impl_str);
 358                     self.last_pos = source!(self, item.span).hi();
 359                 }
 360             }
 361             ast::ItemKind::Trait(..) => {
 362                 self.format_missing_with_indent(item.span.lo());
 363                 if let Some(trait_str) = format_trait(&self.get_context(), item, self.block_indent)
 364                 {
 365                     self.buffer.push_str(&trait_str);
 366                     self.last_pos = source!(self, item.span).hi();
 367                 }
 368             }
 369             ast::ItemKind::ExternCrate(_) => {
 370                 let rw = rewrite_extern_crate(&self.get_context(), item);
 371                 self.push_rewrite(item.span, rw);
 372             }
 373             ast::ItemKind::Struct(ref def, ref generics) => {
 374                 let rewrite = {
 375                     let indent = self.block_indent;
 376                     let context = self.get_context();
 377                     ::items::format_struct(
 378                         &context,
 379                         "struct ",
 380                         item.ident,
 381                         &item.vis,
 382                         def,
 383                         Some(generics),
 384                         item.span,
 385                         indent,
 386                         None,
 387                     ).map(|s| match *def {
 388                         ast::VariantData::Tuple(..) => s + ";",
 389                         _ => s,
 390                     })
 391                 };
 392                 self.push_rewrite(item.span, rewrite);
 393             }
 394             ast::ItemKind::Enum(ref def, ref generics) => {
 395                 self.format_missing_with_indent(source!(self, item.span).lo());
 396                 self.visit_enum(item.ident, &item.vis, def, generics, item.span);
 397                 self.last_pos = source!(self, item.span).hi();
 398             }
 399             ast::ItemKind::Mod(ref module) => {
 400                 self.format_missing_with_indent(source!(self, item.span).lo());
 401                 self.format_mod(module, &item.vis, item.span, item.ident, &attrs);
 402             }
 403             ast::ItemKind::Mac(ref mac) => {
 404                 self.visit_mac(mac, Some(item.ident), MacroPosition::Item);
 405             }
 406             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 407                 self.format_missing_with_indent(source!(self, item.span).lo());
 408                 self.format_foreign_mod(foreign_mod, item.span);
 409             }
 410             ast::ItemKind::Static(ref ty, mutability, ref expr) => {
 411                 let rewrite = rewrite_static(
 412                     "static",
 413                     &item.vis,
 414                     item.ident,
 415                     ty,
 416                     mutability,
 417                     Some(expr),
 418                     self.block_indent,
 419                     item.span,
 420                     &self.get_context(),
 421                 );
 422                 self.push_rewrite(item.span, rewrite);
 423             }
 424             ast::ItemKind::Const(ref ty, ref expr) => {
 425                 let rewrite = rewrite_static(
 426                     "const",
 427                     &item.vis,
 428                     item.ident,
 429                     ty,
 430                     ast::Mutability::Immutable,
 431                     Some(expr),
 432                     self.block_indent,
 433                     item.span,
 434                     &self.get_context(),
 435                 );
 436                 self.push_rewrite(item.span, rewrite);
 437             }
 438             ast::ItemKind::DefaultImpl(..) => {
 439                 // FIXME(#78): format impl definitions.
 440             }
 441             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
 442                 self.visit_fn(
 443                     visit::FnKind::ItemFn(
 444                         item.ident,
 445                         generics,
 446                         unsafety,
 447                         constness,
 448                         abi,
 449                         &item.vis,
 450                         body,
 451                     ),
 452                     decl,
 453                     item.span,
 454                     item.id,
 455                     ast::Defaultness::Final,
 456                     Some(&item.attrs),
 457                 )
 458             }
 459             ast::ItemKind::Ty(ref ty, ref generics) => {
 460                 let rewrite = rewrite_type_alias(
 461                     &self.get_context(),
 462                     self.block_indent,
 463                     item.ident,
 464                     ty,
 465                     generics,
 466                     &item.vis,
 467                     item.span,
 468                 );
 469                 self.push_rewrite(item.span, rewrite);
 470             }
 471             ast::ItemKind::Union(ref def, ref generics) => {
 472                 let rewrite = ::items::format_struct_struct(
 473                     &self.get_context(),
 474                     "union ",
 475                     item.ident,
 476                     &item.vis,
 477                     def.fields(),
 478                     Some(generics),
 479                     item.span,
 480                     self.block_indent,
 481                     None,
 482                 );
 483                 self.push_rewrite(item.span, rewrite);
 484             }
 485             ast::ItemKind::GlobalAsm(..) => {
 486                 let snippet = Some(self.snippet(item.span));
 487                 self.push_rewrite(item.span, snippet);
 488             }
 489             ast::ItemKind::MacroDef(..) => {
 490                 // FIXME(#1539): macros 2.0
 491                 let mac_snippet = Some(self.snippet(item.span));
 492                 self.push_rewrite(item.span, mac_snippet);
 493             }
 494         }
 495     }
 496
 497     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 498         skip_out_of_file_lines_range_visitor!(self, ti.span);
 499
 500         if self.visit_attrs(&ti.attrs, ast::AttrStyle::Outer) {
 501             self.push_rewrite(ti.span, None);
 502             return;
 503         }
 504
 505         match ti.node {
 506             ast::TraitItemKind::Const(ref ty, ref expr_opt) => {
 507                 let rewrite = rewrite_static(
 508                     "const",
 509                     &ast::Visibility::Inherited,
 510                     ti.ident,
 511                     ty,
 512                     ast::Mutability::Immutable,
 513                     expr_opt.as_ref(),
 514                     self.block_indent,
 515                     ti.span,
 516                     &self.get_context(),
 517                 );
 518                 self.push_rewrite(ti.span, rewrite);
 519             }
 520             ast::TraitItemKind::Method(ref sig, None) => {
 521                 let indent = self.block_indent;
 522                 let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, ti.span);
 523                 self.push_rewrite(ti.span, rewrite);
 524             }
 525             ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
 526                 self.visit_fn(
 527                     visit::FnKind::Method(ti.ident, sig, None, body),
 528                     &sig.decl,
 529                     ti.span,
 530                     ti.id,
 531                     ast::Defaultness::Final,
 532                     Some(&ti.attrs),
 533                 );
 534             }
 535             ast::TraitItemKind::Type(ref type_param_bounds, ref type_default) => {
 536                 let rewrite = rewrite_associated_type(
 537                     ti.ident,
 538                     type_default.as_ref(),
 539                     Some(type_param_bounds),
 540                     &self.get_context(),
 541                     self.block_indent,
 542                 );
 543                 self.push_rewrite(ti.span, rewrite);
 544             }
 545             ast::TraitItemKind::Macro(ref mac) => {
 546                 self.visit_mac(mac, Some(ti.ident), MacroPosition::Item);
 547             }
 548         }
 549     }
 550
 551     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 552         skip_out_of_file_lines_range_visitor!(self, ii.span);
 553
 554         if self.visit_attrs(&ii.attrs, ast::AttrStyle::Outer) {
 555             self.push_rewrite(ii.span, None);
 556             return;
 557         }
 558
 559         match ii.node {
 560             ast::ImplItemKind::Method(ref sig, ref body) => {
 561                 self.visit_fn(
 562                     visit::FnKind::Method(ii.ident, sig, Some(&ii.vis), body),
 563                     &sig.decl,
 564                     ii.span,
 565                     ii.id,
 566                     ii.defaultness,
 567                     Some(&ii.attrs),
 568                 );
 569             }
 570             ast::ImplItemKind::Const(ref ty, ref expr) => {
 571                 let rewrite = rewrite_static(
 572                     "const",
 573                     &ii.vis,
 574                     ii.ident,
 575                     ty,
 576                     ast::Mutability::Immutable,
 577                     Some(expr),
 578                     self.block_indent,
 579                     ii.span,
 580                     &self.get_context(),
 581                 );
 582                 self.push_rewrite(ii.span, rewrite);
 583             }
 584             ast::ImplItemKind::Type(ref ty) => {
 585                 let rewrite = rewrite_associated_impl_type(
 586                     ii.ident,
 587                     ii.defaultness,
 588                     Some(ty),
 589                     None,
 590                     &self.get_context(),
 591                     self.block_indent,
 592                 );
 593                 self.push_rewrite(ii.span, rewrite);
 594             }
 595             ast::ImplItemKind::Macro(ref mac) => {
 596                 self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
 597             }
 598         }
 599     }
 600
 601     fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>, pos: MacroPosition) {
 602         skip_out_of_file_lines_range_visitor!(self, mac.span);
 603
 604         // 1 = ;
 605         let shape = self.shape().sub_width(1).unwrap();
 606         let rewrite = rewrite_macro(mac, ident, &self.get_context(), shape, pos);
 607         self.push_rewrite(mac.span, rewrite);
 608     }
 609
 610     pub fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 611         self.format_missing_with_indent(source!(self, span).lo());
 612         let result = rewrite.unwrap_or_else(|| self.snippet(span));
 613         self.buffer.push_str(&result);
 614         self.last_pos = source!(self, span).hi();
 615     }
 616
 617     pub fn from_codemap(parse_session: &'a ParseSess, config: &'a Config) -> FmtVisitor<'a> {
 618         FmtVisitor {
 619             parse_session: parse_session,
 620             codemap: parse_session.codemap(),
 621             buffer: StringBuffer::new(),
 622             last_pos: BytePos(0),
 623             block_indent: Indent::empty(),
 624             config: config,
 625             is_if_else_block: false,
 626         }
 627     }
 628
 629     pub fn snippet(&self, span: Span) -> String {
 630         match self.codemap.span_to_snippet(span) {
 631             Ok(s) => s,
 632             Err(_) => {
 633                 println!(
 634                     "Couldn't make snippet for span {:?}->{:?}",
 635                     self.codemap.lookup_char_pos(span.lo()),
 636                     self.codemap.lookup_char_pos(span.hi())
 637                 );
 638                 "".to_owned()
 639             }
 640         }
 641     }
 642
 643     // Returns true if we should skip the following item.
 644     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute], style: ast::AttrStyle) -> bool {
 645         if contains_skip(attrs) {
 646             return true;
 647         }
 648
 649         let attrs: Vec<_> = attrs.iter().filter(|a| a.style == style).cloned().collect();
 650         if attrs.is_empty() {
 651             return false;
 652         }
 653
 654         let rewrite = attrs.rewrite(&self.get_context(), self.shape());
 655         let span = mk_sp(attrs[0].span.lo(), attrs[attrs.len() - 1].span.hi());
 656         self.push_rewrite(span, rewrite);
 657
 658         false
 659     }
 660
 661     fn reorder_items<F>(
 662         &mut self,
 663         items_left: &[ptr::P<ast::Item>],
 664         is_item: &F,
 665         in_group: bool,
 666     ) -> usize
 667     where
 668         F: Fn(&ast::Item) -> bool,
 669     {
 670         let mut last = self.codemap.lookup_line_range(items_left[0].span());
 671         let item_length = items_left
 672             .iter()
 673             .take_while(|ppi| {
 674                 is_item(&***ppi) && (!in_group || {
 675                     let current = self.codemap.lookup_line_range(ppi.span());
 676                     let in_same_group = current.lo < last.hi + 2;
 677                     last = current;
 678                     in_same_group
 679                 })
 680             })
 681             .count();
 682         let items = &items_left[..item_length];
 683
 684         let at_least_one_in_file_lines = items
 685             .iter()
 686             .any(|item| !out_of_file_lines_range!(self, item.span));
 687
 688         if at_least_one_in_file_lines {
 689             self.format_imports(items);
 690         } else {
 691             for item in items {
 692                 self.push_rewrite(item.span, None);
 693             }
 694         }
 695
 696         item_length
 697     }
 698
 699     fn walk_mod_items(&mut self, m: &ast::Mod) {
 700         let mut items_left: &[ptr::P<ast::Item>] = &m.items;
 701         while !items_left.is_empty() {
 702             // If the next item is a `use` declaration, then extract it and any subsequent `use`s
 703             // to be potentially reordered within `format_imports`. Otherwise, just format the
 704             // next item for output.
 705             if self.config.reorder_imports() && is_use_item(&*items_left[0]) {
 706                 let used_items_len = self.reorder_items(
 707                     items_left,
 708                     &is_use_item,
 709                     self.config.reorder_imports_in_group(),
 710                 );
 711                 let (_, rest) = items_left.split_at(used_items_len);
 712                 items_left = rest;
 713             } else if self.config.reorder_extern_crates() && is_extern_crate(&*items_left[0]) {
 714                 let used_items_len = self.reorder_items(
 715                     items_left,
 716                     &is_extern_crate,
 717                     self.config.reorder_extern_crates_in_group(),
 718                 );
 719                 let (_, rest) = items_left.split_at(used_items_len);
 720                 items_left = rest;
 721             } else {
 722                 // `unwrap()` is safe here because we know `items_left`
 723                 // has elements from the loop condition
 724                 let (item, rest) = items_left.split_first().unwrap();
 725                 self.visit_item(item);
 726                 items_left = rest;
 727             }
 728         }
 729     }
 730
 731     fn format_mod(
 732         &mut self,
 733         m: &ast::Mod,
 734         vis: &ast::Visibility,
 735         s: Span,
 736         ident: ast::Ident,
 737         attrs: &[ast::Attribute],
 738     ) {
 739         // Decide whether this is an inline mod or an external mod.
 740         let local_file_name = self.codemap.span_to_filename(s);
 741         let inner_span = source!(self, m.inner);
 742         let is_internal = !(inner_span.lo().0 == 0 && inner_span.hi().0 == 0) &&
 743             local_file_name == self.codemap.span_to_filename(inner_span);
 744
 745         self.buffer.push_str(&*utils::format_visibility(vis));
 746         self.buffer.push_str("mod ");
 747         self.buffer.push_str(&ident.to_string());
 748
 749         if is_internal {
 750             match self.config.item_brace_style() {
 751                 BraceStyle::AlwaysNextLine => self.buffer
 752                     .push_str(&format!("\n{}{{", self.block_indent.to_string(self.config))),
 753                 _ => self.buffer.push_str(" {"),
 754             }
 755             // Hackery to account for the closing }.
 756             let mod_lo = self.codemap.span_after(source!(self, s), "{");
 757             let body_snippet =
 758                 self.snippet(mk_sp(mod_lo, source!(self, m.inner).hi() - BytePos(1)));
 759             let body_snippet = body_snippet.trim();
 760             if body_snippet.is_empty() {
 761                 self.buffer.push_str("}");
 762             } else {
 763                 self.last_pos = mod_lo;
 764                 self.block_indent = self.block_indent.block_indent(self.config);
 765                 self.visit_attrs(attrs, ast::AttrStyle::Inner);
 766                 self.walk_mod_items(m);
 767                 self.format_missing_with_indent(source!(self, m.inner).hi() - BytePos(1));
 768                 self.close_block(false);
 769             }
 770             self.last_pos = source!(self, m.inner).hi();
 771         } else {
 772             self.buffer.push_str(";");
 773             self.last_pos = source!(self, s).hi();
 774         }
 775     }
 776
 777     pub fn format_separate_mod(&mut self, m: &ast::Mod, filemap: &codemap::FileMap) {
 778         self.block_indent = Indent::empty();
 779         self.walk_mod_items(m);
 780         self.format_missing_with_indent(filemap.end_pos);
 781     }
 782
 783     pub fn get_context(&self) -> RewriteContext {
 784         RewriteContext {
 785             parse_session: self.parse_session,
 786             codemap: self.codemap,
 787             config: self.config,
 788             inside_macro: false,
 789             use_block: false,
 790             is_if_else_block: false,
 791             force_one_line_chain: false,
 792         }
 793     }
 794 }
 795
 796 impl Rewrite for ast::NestedMetaItem {
 797     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 798         match self.node {
 799             ast::NestedMetaItemKind::MetaItem(ref meta_item) => meta_item.rewrite(context, shape),
 800             ast::NestedMetaItemKind::Literal(..) => Some(context.snippet(self.span)),
 801         }
 802     }
 803 }
 804
 805 impl Rewrite for ast::MetaItem {
 806     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 807         Some(match self.node {
 808             ast::MetaItemKind::Word => String::from(&*self.name.as_str()),
 809             ast::MetaItemKind::List(ref list) => {
 810                 let name = self.name.as_str();
 811                 // 3 = `#[` and `(`, 2 = `]` and `)`
 812                 let item_shape = try_opt!(
 813                     shape
 814                         .shrink_left(name.len() + 3)
 815                         .and_then(|s| s.sub_width(2))
 816                 );
 817                 let items = itemize_list(
 818                     context.codemap,
 819                     list.iter(),
 820                     ")",
 821                     |nested_meta_item| nested_meta_item.span.lo(),
 822                     |nested_meta_item| nested_meta_item.span.hi(),
 823                     |nested_meta_item| nested_meta_item.rewrite(context, item_shape),
 824                     self.span.lo(),
 825                     self.span.hi(),
 826                     false,
 827                 );
 828                 let item_vec = items.collect::<Vec<_>>();
 829                 let fmt = ListFormatting {
 830                     tactic: DefinitiveListTactic::Mixed,
 831                     separator: ",",
 832                     trailing_separator: SeparatorTactic::Never,
 833                     separator_place: SeparatorPlace::Back,
 834                     shape: item_shape,
 835                     ends_with_newline: false,
 836                     preserve_newline: false,
 837                     config: context.config,
 838                 };
 839                 format!("{}({})", name, try_opt!(write_list(&item_vec, &fmt)))
 840             }
 841             ast::MetaItemKind::NameValue(ref literal) => {
 842                 let name = self.name.as_str();
 843                 let value = context.snippet(literal.span);
 844                 if &*name == "doc" && contains_comment(&value) {
 845                     let doc_shape = Shape {
 846                         width: cmp::min(shape.width, context.config.comment_width())
 847                             .checked_sub(shape.indent.width())
 848                             .unwrap_or(0),
 849                         ..shape
 850                     };
 851                     try_opt!(rewrite_comment(&value, false, doc_shape, context.config))
 852                 } else {
 853                     format!("{} = {}", name, value)
 854                 }
 855             }
 856         })
 857     }
 858 }
 859
 860 impl Rewrite for ast::Attribute {
 861     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 862         try_opt!(self.meta())
 863             .rewrite(context, shape)
 864             .map(|rw| if self.is_sugared_doc {
 865                 rw
 866             } else {
 867                 let original = context.snippet(self.span);
 868                 let prefix = match self.style {
 869                     ast::AttrStyle::Inner => "#!",
 870                     ast::AttrStyle::Outer => "#",
 871                 };
 872                 if contains_comment(&original) {
 873                     original
 874                 } else {
 875                     format!("{}[{}]", prefix, rw)
 876                 }
 877             })
 878     }
 879 }
 880
 881 impl<'a> Rewrite for [ast::Attribute] {
 882     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 883         if self.is_empty() {
 884             return Some(String::new());
 885         }
 886         let mut result = String::with_capacity(128);
 887         let indent = shape.indent.to_string(context.config);
 888
 889         let mut derive_args = Vec::new();
 890
 891         let mut iter = self.iter().enumerate().peekable();
 892         let mut insert_new_line = true;
 893         let mut is_prev_sugared_doc = false;
 894         while let Some((i, a)) = iter.next() {
 895             let a_str = try_opt!(a.rewrite(context, shape));
 896
 897             // Write comments and blank lines between attributes.
 898             if i > 0 {
 899                 let comment = context.snippet(mk_sp(self[i - 1].span.hi(), a.span.lo()));
 900                 // This particular horror show is to preserve line breaks in between doc
 901                 // comments. An alternative would be to force such line breaks to start
 902                 // with the usual doc comment token.
 903                 let (multi_line_before, multi_line_after) = if a.is_sugared_doc ||
 904                     is_prev_sugared_doc
 905                 {
 906                     // Look at before and after comment and see if there are any empty lines.
 907                     let comment_begin = comment.chars().position(|c| c == '/');
 908                     let len = comment_begin.unwrap_or_else(|| comment.len());
 909                     let mlb = comment.chars().take(len).filter(|c| *c == '\n').count() > 1;
 910                     let mla = if comment_begin.is_none() {
 911                         mlb
 912                     } else {
 913                         let comment_end = comment.chars().rev().position(|c| !c.is_whitespace());
 914                         let len = comment_end.unwrap();
 915                         comment
 916                             .chars()
 917                             .rev()
 918                             .take(len)
 919                             .filter(|c| *c == '\n')
 920                             .count() > 1
 921                     };
 922                     (mlb, mla)
 923                 } else {
 924                     (false, false)
 925                 };
 926
 927                 let comment = try_opt!(recover_missing_comment_in_span(
 928                     mk_sp(self[i - 1].span.hi(), a.span.lo()),
 929                     shape.with_max_width(context.config),
 930                     context,
 931                     0,
 932                 ));
 933
 934                 if !comment.is_empty() {
 935                     if multi_line_before {
 936                         result.push('\n');
 937                     }
 938                     result.push_str(&comment);
 939                     result.push('\n');
 940                     if multi_line_after {
 941                         result.push('\n')
 942                     }
 943                 } else if insert_new_line {
 944                     result.push('\n');
 945                     if multi_line_after {
 946                         result.push('\n')
 947                     }
 948                 }
 949
 950                 if derive_args.is_empty() {
 951                     result.push_str(&indent);
 952                 }
 953
 954                 insert_new_line = true;
 955             }
 956
 957             // Write the attribute itself.
 958             if context.config.merge_derives() {
 959                 // If the attribute is `#[derive(...)]`, take the arguments.
 960                 if let Some(mut args) = get_derive_args(context, a) {
 961                     derive_args.append(&mut args);
 962                     match iter.peek() {
 963                         // If the next attribute is `#[derive(...)]` as well, skip rewriting.
 964                         Some(&(_, next_attr)) if is_derive(next_attr) => insert_new_line = false,
 965                         // If not, rewrite the merged derives.
 966                         _ => {
 967                             result.push_str(&try_opt!(format_derive(context, &derive_args, shape)));
 968                             derive_args.clear();
 969                         }
 970                     }
 971                 } else {
 972                     result.push_str(&a_str);
 973                 }
 974             } else {
 975                 result.push_str(&a_str);
 976             }
 977
 978             is_prev_sugared_doc = a.is_sugared_doc;
 979         }
 980         Some(result)
 981     }
 982 }
 983
 984 // Format `#[derive(..)]`, using visual indent & mixed style when we need to go multiline.
 985 fn format_derive(context: &RewriteContext, derive_args: &[String], shape: Shape) -> Option<String> {
 986     let mut result = String::with_capacity(128);
 987     result.push_str("#[derive(");
 988     // 11 = `#[derive()]`
 989     let initial_budget = try_opt!(shape.width.checked_sub(11));
 990     let mut budget = initial_budget;
 991     let num = derive_args.len();
 992     for (i, a) in derive_args.iter().enumerate() {
 993         // 2 = `, ` or `)]`
 994         let width = a.len() + 2;
 995         if width > budget {
 996             if i > 0 {
 997                 // Remove trailing whitespace.
 998                 result.pop();
 999             }
1000             result.push('\n');
1001             // 9 = `#[derive(`
1002             result.push_str(&(shape.indent + 9).to_string(context.config));
1003             budget = initial_budget;
1004         } else {
1005             budget = budget.checked_sub(width).unwrap_or(0);
1006         }
1007         result.push_str(a);
1008         if i != num - 1 {
1009             result.push_str(", ")
1010         }
1011     }
1012     result.push_str(")]");
1013     Some(result)
1014 }
1015
1016 fn is_derive(attr: &ast::Attribute) -> bool {
1017     match attr.meta() {
1018         Some(meta_item) => match meta_item.node {
1019             ast::MetaItemKind::List(..) => meta_item.name.as_str() == "derive",
1020             _ => false,
1021         },
1022         _ => false,
1023     }
1024 }
1025
1026 /// Returns the arguments of `#[derive(...)]`.
1027 fn get_derive_args(context: &RewriteContext, attr: &ast::Attribute) -> Option<Vec<String>> {
1028     attr.meta().and_then(|meta_item| match meta_item.node {
1029         ast::MetaItemKind::List(ref args) if meta_item.name.as_str() == "derive" => {
1030             // Every argument of `derive` should be `NestedMetaItemKind::Literal`.
1031             Some(
1032                 args.iter()
1033                     .map(|a| context.snippet(a.span))
1034                     .collect::<Vec<_>>(),
1035             )
1036         }
1037         _ => None,
1038     })
1039 }
1040
1041 // Rewrite `extern crate foo;` WITHOUT attributes.
1042 pub fn rewrite_extern_crate(context: &RewriteContext, item: &ast::Item) -> Option<String> {
1043     assert!(is_extern_crate(item));
1044     let new_str = context.snippet(item.span);
1045     Some(if contains_comment(&new_str) {
1046         new_str
1047     } else {
1048         let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
1049         String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
1050     })
1051 }