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, CodeCharKind, CommentCodeSlices, FindUncommented};
  22 use comment::rewrite_comment;
  23 use config::{BraceStyle, Config};
  24 use expr::{format_expr, ExprType};
  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, SeparatorTactic};
  28 use macros::{rewrite_macro, MacroPosition};
  29 use regex::Regex;
  30 use rewrite::{Rewrite, RewriteContext};
  31 use utils::{self, contains_skip, mk_sp};
  32
  33 fn is_use_item(item: &ast::Item) -> bool {
  34     match item.node {
  35         ast::ItemKind::Use(_) => true,
  36         _ => false,
  37     }
  38 }
  39
  40 fn is_extern_crate(item: &ast::Item) -> bool {
  41     match item.node {
  42         ast::ItemKind::ExternCrate(..) => true,
  43         _ => false,
  44     }
  45 }
  46
  47 pub struct FmtVisitor<'a> {
  48     pub parse_session: &'a ParseSess,
  49     pub codemap: &'a CodeMap,
  50     pub buffer: StringBuffer,
  51     pub last_pos: BytePos,
  52     // FIXME: use an RAII util or closure for indenting
  53     pub block_indent: Indent,
  54     pub config: &'a Config,
  55     pub is_if_else_block: bool,
  56 }
  57
  58 impl<'a> FmtVisitor<'a> {
  59     fn visit_stmt(&mut self, stmt: &ast::Stmt) {
  60         debug!(
  61             "visit_stmt: {:?} {:?}",
  62             self.codemap.lookup_char_pos(stmt.span.lo),
  63             self.codemap.lookup_char_pos(stmt.span.hi)
  64         );
  65
  66         match stmt.node {
  67             ast::StmtKind::Item(ref item) => {
  68                 self.visit_item(item);
  69             }
  70             ast::StmtKind::Local(ref local) => {
  71                 let rewrite = if contains_skip(&local.attrs) {
  72                     None
  73                 } else {
  74                     stmt.rewrite(
  75                         &self.get_context(),
  76                         Shape::indented(self.block_indent, self.config),
  77                     )
  78                 };
  79                 self.push_rewrite(stmt.span, rewrite);
  80             }
  81             ast::StmtKind::Expr(ref expr) => {
  82                 let rewrite = format_expr(
  83                     expr,
  84                     ExprType::Statement,
  85                     &self.get_context(),
  86                     Shape::indented(self.block_indent, self.config),
  87                 );
  88                 let span = if expr.attrs.is_empty() {
  89                     stmt.span
  90                 } else {
  91                     mk_sp(expr.span().lo, stmt.span.hi)
  92                 };
  93                 self.push_rewrite(span, rewrite)
  94             }
  95             ast::StmtKind::Semi(ref expr) => {
  96                 let rewrite = stmt.rewrite(
  97                     &self.get_context(),
  98                     Shape::indented(self.block_indent, self.config),
  99                 );
 100                 let span = if expr.attrs.is_empty() {
 101                     stmt.span
 102                 } else {
 103                     mk_sp(expr.span().lo, stmt.span.hi)
 104                 };
 105                 self.push_rewrite(span, rewrite)
 106             }
 107             ast::StmtKind::Mac(ref mac) => {
 108                 let (ref mac, _macro_style, ref attrs) = **mac;
 109                 if contains_skip(attrs) {
 110                     self.push_rewrite(mac.span, None);
 111                 } else {
 112                     self.visit_mac(mac, None, MacroPosition::Statement);
 113                 }
 114                 self.format_missing(stmt.span.hi);
 115             }
 116         }
 117     }
 118
 119     pub fn visit_block(&mut self, b: &ast::Block, inner_attrs: Option<&[ast::Attribute]>) {
 120         debug!(
 121             "visit_block: {:?} {:?}",
 122             self.codemap.lookup_char_pos(b.span.lo),
 123             self.codemap.lookup_char_pos(b.span.hi)
 124         );
 125
 126         // Check if this block has braces.
 127         let snippet = self.snippet(b.span);
 128         let has_braces = snippet.starts_with('{') || snippet.starts_with("unsafe");
 129         let brace_compensation = if has_braces { BytePos(1) } else { BytePos(0) };
 130
 131         self.last_pos = self.last_pos + brace_compensation;
 132         self.block_indent = self.block_indent.block_indent(self.config);
 133         self.buffer.push_str("{");
 134
 135         if self.config.remove_blank_lines_at_start_or_end_of_block() {
 136             if let Some(first_stmt) = b.stmts.first() {
 137                 let attr_lo = inner_attrs
 138                     .and_then(|attrs| {
 139                         utils::inner_attributes(attrs)
 140                             .first()
 141                             .map(|attr| attr.span.lo)
 142                     })
 143                     .or_else(|| {
 144                         // Attributes for an item in a statement position
 145                         // do not belong to the statement. (rust-lang/rust#34459)
 146                         if let ast::StmtKind::Item(ref item) = first_stmt.node {
 147                             item.attrs.first()
 148                         } else {
 149                             first_stmt.attrs().first()
 150                         }.and_then(|attr| {
 151                             // Some stmts can have embedded attributes.
 152                             // e.g. `match { #![attr] ... }`
 153                             let attr_lo = attr.span.lo;
 154                             if attr_lo < first_stmt.span.lo {
 155                                 Some(attr_lo)
 156                             } else {
 157                                 None
 158                             }
 159                         })
 160                     });
 161
 162                 let snippet =
 163                     self.snippet(mk_sp(self.last_pos, attr_lo.unwrap_or(first_stmt.span.lo)));
 164                 let len = CommentCodeSlices::new(&snippet).nth(0).and_then(
 165                     |(kind, _, s)| if kind == CodeCharKind::Normal {
 166                         s.rfind('\n')
 167                     } else {
 168                         None
 169                     },
 170                 );
 171                 if let Some(len) = len {
 172                     self.last_pos = self.last_pos + BytePos::from_usize(len);
 173                 }
 174             }
 175         }
 176
 177         // Format inner attributes if available.
 178         if let Some(attrs) = inner_attrs {
 179             self.visit_attrs(attrs, ast::AttrStyle::Inner);
 180         }
 181
 182         for stmt in &b.stmts {
 183             self.visit_stmt(stmt)
 184         }
 185
 186         if !b.stmts.is_empty() {
 187             if let Some(expr) = utils::stmt_expr(&b.stmts[b.stmts.len() - 1]) {
 188                 if utils::semicolon_for_expr(&self.get_context(), expr) {
 189                     self.buffer.push_str(";");
 190                 }
 191             }
 192         }
 193
 194         let mut remove_len = BytePos(0);
 195         if self.config.remove_blank_lines_at_start_or_end_of_block() {
 196             if let Some(stmt) = b.stmts.last() {
 197                 let snippet = self.snippet(mk_sp(
 198                     stmt.span.hi,
 199                     source!(self, b.span).hi - brace_compensation,
 200                 ));
 201                 let len = CommentCodeSlices::new(&snippet)
 202                     .last()
 203                     .and_then(|(kind, _, s)| {
 204                         if kind == CodeCharKind::Normal && s.trim().is_empty() {
 205                             Some(s.len())
 206                         } else {
 207                             None
 208                         }
 209                     });
 210                 if let Some(len) = len {
 211                     remove_len = BytePos::from_usize(len);
 212                 }
 213             }
 214         }
 215
 216         let mut unindent_comment = self.is_if_else_block && !b.stmts.is_empty();
 217         if unindent_comment {
 218             let end_pos = source!(self, b.span).hi - brace_compensation - remove_len;
 219             let snippet = self.get_context().snippet(mk_sp(self.last_pos, end_pos));
 220             unindent_comment = snippet.contains("//") || snippet.contains("/*");
 221         }
 222         // FIXME: we should compress any newlines here to just one
 223         if unindent_comment {
 224             self.block_indent = self.block_indent.block_unindent(self.config);
 225         }
 226         self.format_missing_with_indent(source!(self, b.span).hi - brace_compensation - remove_len);
 227         if unindent_comment {
 228             self.block_indent = self.block_indent.block_indent(self.config);
 229         }
 230         self.close_block(unindent_comment);
 231         self.last_pos = source!(self, b.span).hi;
 232     }
 233
 234     // FIXME: this is a terrible hack to indent the comments between the last
 235     // item in the block and the closing brace to the block's level.
 236     // The closing brace itself, however, should be indented at a shallower
 237     // level.
 238     fn close_block(&mut self, unindent_comment: bool) {
 239         let total_len = self.buffer.len;
 240         let chars_too_many = if unindent_comment {
 241             0
 242         } else if self.config.hard_tabs() {
 243             1
 244         } else {
 245             self.config.tab_spaces()
 246         };
 247         self.buffer.truncate(total_len - chars_too_many);
 248         self.buffer.push_str("}");
 249         self.block_indent = self.block_indent.block_unindent(self.config);
 250     }
 251
 252     // Note that this only gets called for function definitions. Required methods
 253     // on traits do not get handled here.
 254     fn visit_fn(
 255         &mut self,
 256         fk: visit::FnKind,
 257         fd: &ast::FnDecl,
 258         s: Span,
 259         _: ast::NodeId,
 260         defaultness: ast::Defaultness,
 261         inner_attrs: Option<&[ast::Attribute]>,
 262     ) {
 263         let indent = self.block_indent;
 264         let block;
 265         let rewrite = match fk {
 266             visit::FnKind::ItemFn(ident, generics, unsafety, constness, abi, vis, b) => {
 267                 block = b;
 268                 self.rewrite_fn(
 269                     indent,
 270                     ident,
 271                     fd,
 272                     generics,
 273                     unsafety,
 274                     constness.node,
 275                     defaultness,
 276                     abi,
 277                     vis,
 278                     mk_sp(s.lo, b.span.lo),
 279                     &b,
 280                 )
 281             }
 282             visit::FnKind::Method(ident, sig, vis, b) => {
 283                 block = b;
 284                 self.rewrite_fn(
 285                     indent,
 286                     ident,
 287                     fd,
 288                     &sig.generics,
 289                     sig.unsafety,
 290                     sig.constness.node,
 291                     defaultness,
 292                     sig.abi,
 293                     vis.unwrap_or(&ast::Visibility::Inherited),
 294                     mk_sp(s.lo, b.span.lo),
 295                     &b,
 296                 )
 297             }
 298             visit::FnKind::Closure(_) => unreachable!(),
 299         };
 300
 301         if let Some(fn_str) = rewrite {
 302             self.format_missing_with_indent(source!(self, s).lo);
 303             self.buffer.push_str(&fn_str);
 304             if let Some(c) = fn_str.chars().last() {
 305                 if c == '}' {
 306                     self.last_pos = source!(self, block.span).hi;
 307                     return;
 308                 }
 309             }
 310         } else {
 311             self.format_missing(source!(self, block.span).lo);
 312         }
 313
 314         self.last_pos = source!(self, block.span).lo;
 315         self.visit_block(block, inner_attrs)
 316     }
 317
 318     pub fn visit_item(&mut self, item: &ast::Item) {
 319         skip_out_of_file_lines_range_visitor!(self, item.span);
 320
 321         // This is where we bail out if there is a skip attribute. This is only
 322         // complex in the module case. It is complex because the module could be
 323         // in a separate file and there might be attributes in both files, but
 324         // the AST lumps them all together.
 325         let mut attrs = item.attrs.clone();
 326         match item.node {
 327             ast::ItemKind::Mod(ref m) => {
 328                 let outer_file = self.codemap.lookup_char_pos(item.span.lo).file;
 329                 let inner_file = self.codemap.lookup_char_pos(m.inner.lo).file;
 330                 if outer_file.name == inner_file.name {
 331                     // Module is inline, in this case we treat modules like any
 332                     // other item.
 333                     if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
 334                         self.push_rewrite(item.span, None);
 335                         return;
 336                     }
 337                 } else if utils::contains_skip(&item.attrs) {
 338                     // Module is not inline, but should be skipped.
 339                     return;
 340                 } else {
 341                     // Module is not inline and should not be skipped. We want
 342                     // to process only the attributes in the current file.
 343                     let filterd_attrs = item.attrs
 344                         .iter()
 345                         .filter_map(|a| {
 346                             let attr_file = self.codemap.lookup_char_pos(a.span.lo).file;
 347                             if attr_file.name == outer_file.name {
 348                                 Some(a.clone())
 349                             } else {
 350                                 None
 351                             }
 352                         })
 353                         .collect::<Vec<_>>();
 354                     // Assert because if we should skip it should be caught by
 355                     // the above case.
 356                     assert!(!self.visit_attrs(&filterd_attrs, ast::AttrStyle::Outer));
 357                     attrs = filterd_attrs;
 358                 }
 359             }
 360             _ => if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
 361                 self.push_rewrite(item.span, None);
 362                 return;
 363             },
 364         }
 365
 366         match item.node {
 367             ast::ItemKind::Use(ref vp) => {
 368                 self.format_import(&item.vis, vp, item.span, &item.attrs);
 369             }
 370             ast::ItemKind::Impl(..) => {
 371                 self.format_missing_with_indent(source!(self, item.span).lo);
 372                 let snippet = self.get_context().snippet(item.span);
 373                 let where_span_end = snippet
 374                     .find_uncommented("{")
 375                     .map(|x| (BytePos(x as u32)) + source!(self, item.span).lo);
 376                 if let Some(impl_str) =
 377                     format_impl(&self.get_context(), item, self.block_indent, where_span_end)
 378                 {
 379                     self.buffer.push_str(&impl_str);
 380                     self.last_pos = source!(self, item.span).hi;
 381                 }
 382             }
 383             ast::ItemKind::Trait(..) => {
 384                 self.format_missing_with_indent(item.span.lo);
 385                 if let Some(trait_str) = format_trait(&self.get_context(), item, self.block_indent)
 386                 {
 387                     self.buffer.push_str(&trait_str);
 388                     self.last_pos = source!(self, item.span).hi;
 389                 }
 390             }
 391             ast::ItemKind::ExternCrate(_) => {
 392                 self.format_missing_with_indent(source!(self, item.span).lo);
 393                 let new_str = self.snippet(item.span);
 394                 if contains_comment(&new_str) {
 395                     self.buffer.push_str(&new_str)
 396                 } else {
 397                     let no_whitespace =
 398                         &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
 399                     self.buffer
 400                         .push_str(&Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"));
 401                 }
 402                 self.last_pos = source!(self, item.span).hi;
 403             }
 404             ast::ItemKind::Struct(ref def, ref generics) => {
 405                 let rewrite = {
 406                     let indent = self.block_indent;
 407                     let context = self.get_context();
 408                     ::items::format_struct(
 409                         &context,
 410                         "struct ",
 411                         item.ident,
 412                         &item.vis,
 413                         def,
 414                         Some(generics),
 415                         item.span,
 416                         indent,
 417                         None,
 418                     ).map(|s| match *def {
 419                         ast::VariantData::Tuple(..) => s + ";",
 420                         _ => s,
 421                     })
 422                 };
 423                 self.push_rewrite(item.span, rewrite);
 424             }
 425             ast::ItemKind::Enum(ref def, ref generics) => {
 426                 self.format_missing_with_indent(source!(self, item.span).lo);
 427                 self.visit_enum(item.ident, &item.vis, def, generics, item.span);
 428                 self.last_pos = source!(self, item.span).hi;
 429             }
 430             ast::ItemKind::Mod(ref module) => {
 431                 self.format_missing_with_indent(source!(self, item.span).lo);
 432                 self.format_mod(module, &item.vis, item.span, item.ident, &attrs);
 433             }
 434             ast::ItemKind::Mac(ref mac) => {
 435                 self.visit_mac(mac, Some(item.ident), MacroPosition::Item);
 436             }
 437             ast::ItemKind::ForeignMod(ref foreign_mod) => {
 438                 self.format_missing_with_indent(source!(self, item.span).lo);
 439                 self.format_foreign_mod(foreign_mod, item.span);
 440             }
 441             ast::ItemKind::Static(ref ty, mutability, ref expr) => {
 442                 let rewrite = rewrite_static(
 443                     "static",
 444                     &item.vis,
 445                     item.ident,
 446                     ty,
 447                     mutability,
 448                     Some(expr),
 449                     self.block_indent,
 450                     item.span,
 451                     &self.get_context(),
 452                 );
 453                 self.push_rewrite(item.span, rewrite);
 454             }
 455             ast::ItemKind::Const(ref ty, ref expr) => {
 456                 let rewrite = rewrite_static(
 457                     "const",
 458                     &item.vis,
 459                     item.ident,
 460                     ty,
 461                     ast::Mutability::Immutable,
 462                     Some(expr),
 463                     self.block_indent,
 464                     item.span,
 465                     &self.get_context(),
 466                 );
 467                 self.push_rewrite(item.span, rewrite);
 468             }
 469             ast::ItemKind::DefaultImpl(..) => {
 470                 // FIXME(#78): format impl definitions.
 471             }
 472             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
 473                 self.visit_fn(
 474                     visit::FnKind::ItemFn(
 475                         item.ident,
 476                         generics,
 477                         unsafety,
 478                         constness,
 479                         abi,
 480                         &item.vis,
 481                         body,
 482                     ),
 483                     decl,
 484                     item.span,
 485                     item.id,
 486                     ast::Defaultness::Final,
 487                     Some(&item.attrs),
 488                 )
 489             }
 490             ast::ItemKind::Ty(ref ty, ref generics) => {
 491                 let rewrite = rewrite_type_alias(
 492                     &self.get_context(),
 493                     self.block_indent,
 494                     item.ident,
 495                     ty,
 496                     generics,
 497                     &item.vis,
 498                     item.span,
 499                 );
 500                 self.push_rewrite(item.span, rewrite);
 501             }
 502             ast::ItemKind::Union(ref def, ref generics) => {
 503                 let rewrite = ::items::format_struct_struct(
 504                     &self.get_context(),
 505                     "union ",
 506                     item.ident,
 507                     &item.vis,
 508                     def.fields(),
 509                     Some(generics),
 510                     item.span,
 511                     self.block_indent,
 512                     None,
 513                 );
 514                 self.push_rewrite(item.span, rewrite);
 515             }
 516             ast::ItemKind::GlobalAsm(..) => {
 517                 let snippet = Some(self.snippet(item.span));
 518                 self.push_rewrite(item.span, snippet);
 519             }
 520             ast::ItemKind::MacroDef(..) => {
 521                 // FIXME(#1539): macros 2.0
 522                 let snippet = Some(self.snippet(item.span));
 523                 self.push_rewrite(item.span, snippet);
 524             }
 525         }
 526     }
 527
 528     pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
 529         skip_out_of_file_lines_range_visitor!(self, ti.span);
 530
 531         if self.visit_attrs(&ti.attrs, ast::AttrStyle::Outer) {
 532             self.push_rewrite(ti.span, None);
 533             return;
 534         }
 535
 536         match ti.node {
 537             ast::TraitItemKind::Const(ref ty, ref expr_opt) => {
 538                 let rewrite = rewrite_static(
 539                     "const",
 540                     &ast::Visibility::Inherited,
 541                     ti.ident,
 542                     ty,
 543                     ast::Mutability::Immutable,
 544                     expr_opt.as_ref(),
 545                     self.block_indent,
 546                     ti.span,
 547                     &self.get_context(),
 548                 );
 549                 self.push_rewrite(ti.span, rewrite);
 550             }
 551             ast::TraitItemKind::Method(ref sig, None) => {
 552                 let indent = self.block_indent;
 553                 let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, ti.span);
 554                 self.push_rewrite(ti.span, rewrite);
 555             }
 556             ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
 557                 self.visit_fn(
 558                     visit::FnKind::Method(ti.ident, sig, None, body),
 559                     &sig.decl,
 560                     ti.span,
 561                     ti.id,
 562                     ast::Defaultness::Final,
 563                     Some(&ti.attrs),
 564                 );
 565             }
 566             ast::TraitItemKind::Type(ref type_param_bounds, ref type_default) => {
 567                 let rewrite = rewrite_associated_type(
 568                     ti.ident,
 569                     type_default.as_ref(),
 570                     Some(type_param_bounds),
 571                     &self.get_context(),
 572                     self.block_indent,
 573                 );
 574                 self.push_rewrite(ti.span, rewrite);
 575             }
 576             ast::TraitItemKind::Macro(ref mac) => {
 577                 self.visit_mac(mac, Some(ti.ident), MacroPosition::Item);
 578             }
 579         }
 580     }
 581
 582     pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
 583         skip_out_of_file_lines_range_visitor!(self, ii.span);
 584
 585         if self.visit_attrs(&ii.attrs, ast::AttrStyle::Outer) {
 586             self.push_rewrite(ii.span, None);
 587             return;
 588         }
 589
 590         match ii.node {
 591             ast::ImplItemKind::Method(ref sig, ref body) => {
 592                 self.visit_fn(
 593                     visit::FnKind::Method(ii.ident, sig, Some(&ii.vis), body),
 594                     &sig.decl,
 595                     ii.span,
 596                     ii.id,
 597                     ii.defaultness,
 598                     Some(&ii.attrs),
 599                 );
 600             }
 601             ast::ImplItemKind::Const(ref ty, ref expr) => {
 602                 let rewrite = rewrite_static(
 603                     "const",
 604                     &ii.vis,
 605                     ii.ident,
 606                     ty,
 607                     ast::Mutability::Immutable,
 608                     Some(expr),
 609                     self.block_indent,
 610                     ii.span,
 611                     &self.get_context(),
 612                 );
 613                 self.push_rewrite(ii.span, rewrite);
 614             }
 615             ast::ImplItemKind::Type(ref ty) => {
 616                 let rewrite = rewrite_associated_impl_type(
 617                     ii.ident,
 618                     ii.defaultness,
 619                     Some(ty),
 620                     None,
 621                     &self.get_context(),
 622                     self.block_indent,
 623                 );
 624                 self.push_rewrite(ii.span, rewrite);
 625             }
 626             ast::ImplItemKind::Macro(ref mac) => {
 627                 self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
 628             }
 629         }
 630     }
 631
 632     fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>, pos: MacroPosition) {
 633         skip_out_of_file_lines_range_visitor!(self, mac.span);
 634
 635         // 1 = ;
 636         let shape = Shape::indented(self.block_indent, self.config)
 637             .sub_width(1)
 638             .unwrap();
 639         let rewrite = rewrite_macro(mac, ident, &self.get_context(), shape, pos);
 640         self.push_rewrite(mac.span, rewrite);
 641     }
 642
 643     fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 644         self.format_missing_with_indent(source!(self, span).lo);
 645         let result = rewrite.unwrap_or_else(|| self.snippet(span));
 646         self.buffer.push_str(&result);
 647         self.last_pos = source!(self, span).hi;
 648     }
 649
 650     pub fn from_codemap(parse_session: &'a ParseSess, config: &'a Config) -> FmtVisitor<'a> {
 651         FmtVisitor {
 652             parse_session: parse_session,
 653             codemap: parse_session.codemap(),
 654             buffer: StringBuffer::new(),
 655             last_pos: BytePos(0),
 656             block_indent: Indent::empty(),
 657             config: config,
 658             is_if_else_block: false,
 659         }
 660     }
 661
 662     pub fn snippet(&self, span: Span) -> String {
 663         match self.codemap.span_to_snippet(span) {
 664             Ok(s) => s,
 665             Err(_) => {
 666                 println!(
 667                     "Couldn't make snippet for span {:?}->{:?}",
 668                     self.codemap.lookup_char_pos(span.lo),
 669                     self.codemap.lookup_char_pos(span.hi)
 670                 );
 671                 "".to_owned()
 672             }
 673         }
 674     }
 675
 676     // Returns true if we should skip the following item.
 677     pub fn visit_attrs(&mut self, attrs: &[ast::Attribute], style: ast::AttrStyle) -> bool {
 678         if utils::contains_skip(attrs) {
 679             return true;
 680         }
 681
 682         let attrs: Vec<_> = attrs.iter().filter(|a| a.style == style).cloned().collect();
 683         if attrs.is_empty() {
 684             return false;
 685         }
 686
 687         let rewrite = attrs.rewrite(
 688             &self.get_context(),
 689             Shape::indented(self.block_indent, self.config),
 690         );
 691         let span = mk_sp(attrs[0].span.lo, attrs[attrs.len() - 1].span.hi);
 692         self.push_rewrite(span, rewrite);
 693
 694         false
 695     }
 696
 697     fn reorder_items<F>(
 698         &mut self,
 699         items_left: &[ptr::P<ast::Item>],
 700         is_item: &F,
 701         in_group: bool,
 702     ) -> usize
 703     where
 704         F: Fn(&ast::Item) -> bool,
 705     {
 706         let mut last = self.codemap.lookup_line_range(items_left[0].span());
 707         let item_length = items_left
 708             .iter()
 709             .take_while(|ppi| {
 710                 is_item(&***ppi) && (!in_group || {
 711                     let current = self.codemap.lookup_line_range(ppi.span());
 712                     let in_same_group = current.lo < last.hi + 2;
 713                     last = current;
 714                     in_same_group
 715                 })
 716             })
 717             .count();
 718         let items = &items_left[..item_length];
 719
 720         let at_least_one_in_file_lines = items
 721             .iter()
 722             .any(|item| !out_of_file_lines_range!(self, item.span));
 723
 724         if at_least_one_in_file_lines {
 725             self.format_imports(items);
 726         } else {
 727             for item in items {
 728                 self.push_rewrite(item.span, None);
 729             }
 730         }
 731
 732         item_length
 733     }
 734
 735     fn walk_mod_items(&mut self, m: &ast::Mod) {
 736         let mut items_left: &[ptr::P<ast::Item>] = &m.items;
 737         while !items_left.is_empty() {
 738             // If the next item is a `use` declaration, then extract it and any subsequent `use`s
 739             // to be potentially reordered within `format_imports`. Otherwise, just format the
 740             // next item for output.
 741             if self.config.reorder_imports() && is_use_item(&*items_left[0]) {
 742                 let used_items_len = self.reorder_items(
 743                     &items_left,
 744                     &is_use_item,
 745                     self.config.reorder_imports_in_group(),
 746                 );
 747                 let (_, rest) = items_left.split_at(used_items_len);
 748                 items_left = rest;
 749             } else if self.config.reorder_extern_crates() && is_extern_crate(&*items_left[0]) {
 750                 let used_items_len = self.reorder_items(
 751                     &items_left,
 752                     &is_extern_crate,
 753                     self.config.reorder_extern_crates_in_group(),
 754                 );
 755                 let (_, rest) = items_left.split_at(used_items_len);
 756                 items_left = rest;
 757             } else {
 758                 // `unwrap()` is safe here because we know `items_left`
 759                 // has elements from the loop condition
 760                 let (item, rest) = items_left.split_first().unwrap();
 761                 self.visit_item(item);
 762                 items_left = rest;
 763             }
 764         }
 765     }
 766
 767     fn format_mod(
 768         &mut self,
 769         m: &ast::Mod,
 770         vis: &ast::Visibility,
 771         s: Span,
 772         ident: ast::Ident,
 773         attrs: &[ast::Attribute],
 774     ) {
 775         // Decide whether this is an inline mod or an external mod.
 776         let local_file_name = self.codemap.span_to_filename(s);
 777         let inner_span = source!(self, m.inner);
 778         let is_internal = !(inner_span.lo.0 == 0 && inner_span.hi.0 == 0) &&
 779             local_file_name == self.codemap.span_to_filename(inner_span);
 780
 781         self.buffer.push_str(&*utils::format_visibility(vis));
 782         self.buffer.push_str("mod ");
 783         self.buffer.push_str(&ident.to_string());
 784
 785         if is_internal {
 786             match self.config.item_brace_style() {
 787                 BraceStyle::AlwaysNextLine => self.buffer
 788                     .push_str(&format!("\n{}{{", self.block_indent.to_string(self.config))),
 789                 _ => self.buffer.push_str(" {"),
 790             }
 791             // Hackery to account for the closing }.
 792             let mod_lo = self.codemap.span_after(source!(self, s), "{");
 793             let body_snippet = self.snippet(mk_sp(mod_lo, source!(self, m.inner).hi - BytePos(1)));
 794             let body_snippet = body_snippet.trim();
 795             if body_snippet.is_empty() {
 796                 self.buffer.push_str("}");
 797             } else {
 798                 self.last_pos = mod_lo;
 799                 self.block_indent = self.block_indent.block_indent(self.config);
 800                 self.visit_attrs(attrs, ast::AttrStyle::Inner);
 801                 self.walk_mod_items(m);
 802                 self.format_missing_with_indent(source!(self, m.inner).hi - BytePos(1));
 803                 self.close_block(false);
 804             }
 805             self.last_pos = source!(self, m.inner).hi;
 806         } else {
 807             self.buffer.push_str(";");
 808             self.last_pos = source!(self, s).hi;
 809         }
 810     }
 811
 812     pub fn format_separate_mod(&mut self, m: &ast::Mod, filemap: &codemap::FileMap) {
 813         self.block_indent = Indent::empty();
 814         self.walk_mod_items(m);
 815         self.format_missing_with_indent(filemap.end_pos);
 816     }
 817
 818     pub fn get_context(&self) -> RewriteContext {
 819         RewriteContext {
 820             parse_session: self.parse_session,
 821             codemap: self.codemap,
 822             config: self.config,
 823             inside_macro: false,
 824             use_block: false,
 825             is_if_else_block: false,
 826             force_one_line_chain: false,
 827         }
 828     }
 829 }
 830
 831 impl Rewrite for ast::NestedMetaItem {
 832     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 833         match self.node {
 834             ast::NestedMetaItemKind::MetaItem(ref meta_item) => meta_item.rewrite(context, shape),
 835             ast::NestedMetaItemKind::Literal(..) => Some(context.snippet(self.span)),
 836         }
 837     }
 838 }
 839
 840 impl Rewrite for ast::MetaItem {
 841     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 842         Some(match self.node {
 843             ast::MetaItemKind::Word => String::from(&*self.name.as_str()),
 844             ast::MetaItemKind::List(ref list) => {
 845                 let name = self.name.as_str();
 846                 // 3 = `#[` and `(`, 2 = `]` and `)`
 847                 let item_shape = try_opt!(
 848                     shape
 849                         .shrink_left(name.len() + 3)
 850                         .and_then(|s| s.sub_width(2))
 851                 );
 852                 let items = itemize_list(
 853                     context.codemap,
 854                     list.iter(),
 855                     ")",
 856                     |nested_meta_item| nested_meta_item.span.lo,
 857                     |nested_meta_item| nested_meta_item.span.hi,
 858                     |nested_meta_item| nested_meta_item.rewrite(context, item_shape),
 859                     self.span.lo,
 860                     self.span.hi,
 861                     false,
 862                 );
 863                 let item_vec = items.collect::<Vec<_>>();
 864                 let fmt = ListFormatting {
 865                     tactic: DefinitiveListTactic::Mixed,
 866                     separator: ",",
 867                     trailing_separator: SeparatorTactic::Never,
 868                     shape: item_shape,
 869                     ends_with_newline: false,
 870                     preserve_newline: false,
 871                     config: context.config,
 872                 };
 873                 format!("{}({})", name, try_opt!(write_list(&item_vec, &fmt)))
 874             }
 875             ast::MetaItemKind::NameValue(ref literal) => {
 876                 let name = self.name.as_str();
 877                 let value = context.snippet(literal.span);
 878                 if &*name == "doc" && contains_comment(&value) {
 879                     let doc_shape = Shape {
 880                         width: cmp::min(shape.width, context.config.comment_width())
 881                             .checked_sub(shape.indent.width())
 882                             .unwrap_or(0),
 883                         ..shape
 884                     };
 885                     format!(
 886                         "{}",
 887                         try_opt!(rewrite_comment(&value, false, doc_shape, context.config))
 888                     )
 889                 } else {
 890                     format!("{} = {}", name, value)
 891                 }
 892             }
 893         })
 894     }
 895 }
 896
 897 impl Rewrite for ast::Attribute {
 898     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 899         try_opt!(self.meta())
 900             .rewrite(context, shape)
 901             .map(|rw| if self.is_sugared_doc {
 902                 rw
 903             } else {
 904                 let original = context.snippet(self.span);
 905                 let prefix = match self.style {
 906                     ast::AttrStyle::Inner => "#!",
 907                     ast::AttrStyle::Outer => "#",
 908                 };
 909                 if contains_comment(&original) {
 910                     original
 911                 } else {
 912                     format!("{}[{}]", prefix, rw)
 913                 }
 914             })
 915     }
 916 }
 917
 918 impl<'a> Rewrite for [ast::Attribute] {
 919     fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
 920         let mut result = String::new();
 921         if self.is_empty() {
 922             return Some(result);
 923         }
 924         let indent = shape.indent.to_string(context.config);
 925
 926         for (i, a) in self.iter().enumerate() {
 927             let a_str = try_opt!(a.rewrite(context, shape));
 928
 929             // Write comments and blank lines between attributes.
 930             if i > 0 {
 931                 let comment = context.snippet(mk_sp(self[i - 1].span.hi, a.span.lo));
 932                 // This particular horror show is to preserve line breaks in between doc
 933                 // comments. An alternative would be to force such line breaks to start
 934                 // with the usual doc comment token.
 935                 let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
 936                 let comment = comment.trim();
 937                 if !comment.is_empty() {
 938                     let comment = try_opt!(rewrite_comment(
 939                         comment,
 940                         false,
 941                         Shape::legacy(
 942                             context.config.comment_width() - shape.indent.width(),
 943                             shape.indent,
 944                         ),
 945                         context.config,
 946                     ));
 947                     result.push_str(&indent);
 948                     result.push_str(&comment);
 949                     result.push('\n');
 950                 } else if multi_line {
 951                     result.push('\n');
 952                 }
 953                 result.push_str(&indent);
 954             }
 955
 956             // Write the attribute itself.
 957             result.push_str(&a_str);
 958
 959             if i < self.len() - 1 {
 960                 result.push('\n');
 961             }
 962         }
 963
 964         Some(result)
 965     }
 966 }