src/libsyntax/print/pprust.rs

   1 // Copyright 2012-2014 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 pub use self::AnnNode::*;
  12
  13 use rustc_target::spec::abi::{self, Abi};
  14 use ast::{self, BlockCheckMode, PatKind, RangeEnd, RangeSyntax};
  15 use ast::{SelfKind, GenericBound, TraitBoundModifier};
  16 use ast::{Attribute, MacDelimiter, GenericArg};
  17 use util::parser::{self, AssocOp, Fixity};
  18 use attr;
  19 use source_map::{self, SourceMap, Spanned};
  20 use syntax_pos::{self, BytePos};
  21 use syntax_pos::hygiene::{Mark, SyntaxContext};
  22 use parse::token::{self, BinOpToken, Token};
  23 use parse::lexer::comments;
  24 use parse::{self, ParseSess};
  25 use print::pp::{self, Breaks};
  26 use print::pp::Breaks::{Consistent, Inconsistent};
  27 use ptr::P;
  28 use std_inject;
  29 use symbol::keywords;
  30 use syntax_pos::{DUMMY_SP, FileName};
  31 use tokenstream::{self, TokenStream, TokenTree};
  32
  33 use std::ascii;
  34 use std::io::{self, Write, Read};
  35 use std::iter::Peekable;
  36 use std::vec;
  37
  38 pub enum AnnNode<'a> {
  39     NodeIdent(&'a ast::Ident),
  40     NodeName(&'a ast::Name),
  41     NodeBlock(&'a ast::Block),
  42     NodeItem(&'a ast::Item),
  43     NodeSubItem(ast::NodeId),
  44     NodeExpr(&'a ast::Expr),
  45     NodePat(&'a ast::Pat),
  46 }
  47
  48 pub trait PpAnn {
  49     fn pre(&self, _state: &mut State, _node: AnnNode) -> io::Result<()> { Ok(()) }
  50     fn post(&self, _state: &mut State, _node: AnnNode) -> io::Result<()> { Ok(()) }
  51 }
  52
  53 #[derive(Copy, Clone)]
  54 pub struct NoAnn;
  55
  56 impl PpAnn for NoAnn {}
  57
  58 pub struct State<'a> {
  59     pub s: pp::Printer<'a>,
  60     cm: Option<&'a SourceMap>,
  61     comments: Option<Vec<comments::Comment> >,
  62     literals: Peekable<vec::IntoIter<comments::Literal>>,
  63     cur_cmnt: usize,
  64     boxes: Vec<pp::Breaks>,
  65     ann: &'a (dyn PpAnn+'a),
  66 }
  67
  68 fn rust_printer<'a>(writer: Box<dyn Write+'a>, ann: &'a dyn PpAnn) -> State<'a> {
  69     State {
  70         s: pp::mk_printer(writer, DEFAULT_COLUMNS),
  71         cm: None,
  72         comments: None,
  73         literals: vec![].into_iter().peekable(),
  74         cur_cmnt: 0,
  75         boxes: Vec::new(),
  76         ann,
  77     }
  78 }
  79
  80 pub const INDENT_UNIT: usize = 4;
  81
  82 pub const DEFAULT_COLUMNS: usize = 78;
  83
  84 /// Requires you to pass an input filename and reader so that
  85 /// it can scan the input text for comments and literals to
  86 /// copy forward.
  87 pub fn print_crate<'a>(cm: &'a SourceMap,
  88                        sess: &ParseSess,
  89                        krate: &ast::Crate,
  90                        filename: FileName,
  91                        input: &mut dyn Read,
  92                        out: Box<dyn Write+'a>,
  93                        ann: &'a dyn PpAnn,
  94                        is_expanded: bool) -> io::Result<()> {
  95     let mut s = State::new_from_input(cm, sess, filename, input, out, ann, is_expanded);
  96
  97     if is_expanded && std_inject::injected_crate_name().is_some() {
  98         // We need to print `#![no_std]` (and its feature gate) so that
  99         // compiling pretty-printed source won't inject libstd again.
 100         // However we don't want these attributes in the AST because
 101         // of the feature gate, so we fake them up here.
 102
 103         // #![feature(prelude_import)]
 104         let pi_nested = attr::mk_nested_word_item(ast::Ident::from_str("prelude_import"));
 105         let list = attr::mk_list_item(DUMMY_SP, ast::Ident::from_str("feature"), vec![pi_nested]);
 106         let fake_attr = attr::mk_attr_inner(DUMMY_SP, attr::mk_attr_id(), list);
 107         s.print_attribute(&fake_attr)?;
 108
 109         // #![no_std]
 110         let no_std_meta = attr::mk_word_item(ast::Ident::from_str("no_std"));
 111         let fake_attr = attr::mk_attr_inner(DUMMY_SP, attr::mk_attr_id(), no_std_meta);
 112         s.print_attribute(&fake_attr)?;
 113     }
 114
 115     s.print_mod(&krate.module, &krate.attrs)?;
 116     s.print_remaining_comments()?;
 117     s.s.eof()
 118 }
 119
 120 impl<'a> State<'a> {
 121     pub fn new_from_input(cm: &'a SourceMap,
 122                           sess: &ParseSess,
 123                           filename: FileName,
 124                           input: &mut dyn Read,
 125                           out: Box<dyn Write+'a>,
 126                           ann: &'a dyn PpAnn,
 127                           is_expanded: bool) -> State<'a> {
 128         let (cmnts, lits) = comments::gather_comments_and_literals(sess, filename, input);
 129
 130         State::new(
 131             cm,
 132             out,
 133             ann,
 134             Some(cmnts),
 135             // If the code is post expansion, don't use the table of
 136             // literals, since it doesn't correspond with the literals
 137             // in the AST anymore.
 138             if is_expanded { None } else { Some(lits) })
 139     }
 140
 141     pub fn new(cm: &'a SourceMap,
 142                out: Box<dyn Write+'a>,
 143                ann: &'a dyn PpAnn,
 144                comments: Option<Vec<comments::Comment>>,
 145                literals: Option<Vec<comments::Literal>>) -> State<'a> {
 146         State {
 147             s: pp::mk_printer(out, DEFAULT_COLUMNS),
 148             cm: Some(cm),
 149             comments,
 150             literals: literals.unwrap_or_default().into_iter().peekable(),
 151             cur_cmnt: 0,
 152             boxes: Vec::new(),
 153             ann,
 154         }
 155     }
 156 }
 157
 158 pub fn to_string<F>(f: F) -> String where
 159     F: FnOnce(&mut State) -> io::Result<()>,
 160 {
 161     let mut wr = Vec::new();
 162     {
 163         let ann = NoAnn;
 164         let mut printer = rust_printer(Box::new(&mut wr), &ann);
 165         f(&mut printer).unwrap();
 166         printer.s.eof().unwrap();
 167     }
 168     String::from_utf8(wr).unwrap()
 169 }
 170
 171 fn binop_to_string(op: BinOpToken) -> &'static str {
 172     match op {
 173         token::Plus     => "+",
 174         token::Minus    => "-",
 175         token::Star     => "*",
 176         token::Slash    => "/",
 177         token::Percent  => "%",
 178         token::Caret    => "^",
 179         token::And      => "&",
 180         token::Or       => "|",
 181         token::Shl      => "<<",
 182         token::Shr      => ">>",
 183     }
 184 }
 185
 186 pub fn token_to_string(tok: &Token) -> String {
 187     match *tok {
 188         token::Eq                   => "=".to_string(),
 189         token::Lt                   => "<".to_string(),
 190         token::Le                   => "<=".to_string(),
 191         token::EqEq                 => "==".to_string(),
 192         token::Ne                   => "!=".to_string(),
 193         token::Ge                   => ">=".to_string(),
 194         token::Gt                   => ">".to_string(),
 195         token::Not                  => "!".to_string(),
 196         token::Tilde                => "~".to_string(),
 197         token::OrOr                 => "||".to_string(),
 198         token::AndAnd               => "&&".to_string(),
 199         token::BinOp(op)            => binop_to_string(op).to_string(),
 200         token::BinOpEq(op)          => format!("{}=", binop_to_string(op)),
 201
 202         /* Structural symbols */
 203         token::At                   => "@".to_string(),
 204         token::Dot                  => ".".to_string(),
 205         token::DotDot               => "..".to_string(),
 206         token::DotDotDot            => "...".to_string(),
 207         token::DotDotEq             => "..=".to_string(),
 208         token::DotEq                => ".=".to_string(),
 209         token::Comma                => ",".to_string(),
 210         token::Semi                 => ";".to_string(),
 211         token::Colon                => ":".to_string(),
 212         token::ModSep               => "::".to_string(),
 213         token::RArrow               => "->".to_string(),
 214         token::LArrow               => "<-".to_string(),
 215         token::FatArrow             => "=>".to_string(),
 216         token::OpenDelim(token::Paren) => "(".to_string(),
 217         token::CloseDelim(token::Paren) => ")".to_string(),
 218         token::OpenDelim(token::Bracket) => "[".to_string(),
 219         token::CloseDelim(token::Bracket) => "]".to_string(),
 220         token::OpenDelim(token::Brace) => "{".to_string(),
 221         token::CloseDelim(token::Brace) => "}".to_string(),
 222         token::OpenDelim(token::NoDelim) |
 223         token::CloseDelim(token::NoDelim) => " ".to_string(),
 224         token::Pound                => "#".to_string(),
 225         token::Dollar               => "$".to_string(),
 226         token::Question             => "?".to_string(),
 227         token::SingleQuote          => "'".to_string(),
 228
 229         /* Literals */
 230         token::Literal(lit, suf) => {
 231             let mut out = match lit {
 232                 token::Byte(b)           => format!("b'{}'", b),
 233                 token::Char(c)           => format!("'{}'", c),
 234                 token::Float(c)          |
 235                 token::Integer(c)        => c.to_string(),
 236                 token::Str_(s)           => format!("\"{}\"", s),
 237                 token::StrRaw(s, n)      => format!("r{delim}\"{string}\"{delim}",
 238                                                     delim="#".repeat(n as usize),
 239                                                     string=s),
 240                 token::ByteStr(v)         => format!("b\"{}\"", v),
 241                 token::ByteStrRaw(s, n)   => format!("br{delim}\"{string}\"{delim}",
 242                                                     delim="#".repeat(n as usize),
 243                                                     string=s),
 244             };
 245
 246             if let Some(s) = suf {
 247                 out.push_str(&s.as_str())
 248             }
 249
 250             out
 251         }
 252
 253         /* Name components */
 254         token::Ident(s, false)      => s.to_string(),
 255         token::Ident(s, true)       => format!("r#{}", s),
 256         token::Lifetime(s)          => s.to_string(),
 257
 258         /* Other */
 259         token::DocComment(s)        => s.to_string(),
 260         token::Eof                  => "<eof>".to_string(),
 261         token::Whitespace           => " ".to_string(),
 262         token::Comment              => "/* */".to_string(),
 263         token::Shebang(s)           => format!("/* shebang: {}*/", s),
 264
 265         token::Interpolated(ref nt) => match nt.0 {
 266             token::NtExpr(ref e)        => expr_to_string(e),
 267             token::NtMeta(ref e)        => meta_item_to_string(e),
 268             token::NtTy(ref e)          => ty_to_string(e),
 269             token::NtPath(ref e)        => path_to_string(e),
 270             token::NtItem(ref e)        => item_to_string(e),
 271             token::NtBlock(ref e)       => block_to_string(e),
 272             token::NtStmt(ref e)        => stmt_to_string(e),
 273             token::NtPat(ref e)         => pat_to_string(e),
 274             token::NtIdent(e, false)    => ident_to_string(e),
 275             token::NtIdent(e, true)     => format!("r#{}", ident_to_string(e)),
 276             token::NtLifetime(e)        => ident_to_string(e),
 277             token::NtLiteral(ref e)     => expr_to_string(e),
 278             token::NtTT(ref tree)       => tt_to_string(tree.clone()),
 279             token::NtArm(ref e)         => arm_to_string(e),
 280             token::NtImplItem(ref e)    => impl_item_to_string(e),
 281             token::NtTraitItem(ref e)   => trait_item_to_string(e),
 282             token::NtGenerics(ref e)    => generic_params_to_string(&e.params),
 283             token::NtWhereClause(ref e) => where_clause_to_string(e),
 284             token::NtArg(ref e)         => arg_to_string(e),
 285             token::NtVis(ref e)         => vis_to_string(e),
 286             token::NtForeignItem(ref e) => foreign_item_to_string(e),
 287         }
 288     }
 289 }
 290
 291 pub fn ty_to_string(ty: &ast::Ty) -> String {
 292     to_string(|s| s.print_type(ty))
 293 }
 294
 295 pub fn bounds_to_string(bounds: &[ast::GenericBound]) -> String {
 296     to_string(|s| s.print_type_bounds("", bounds))
 297 }
 298
 299 pub fn pat_to_string(pat: &ast::Pat) -> String {
 300     to_string(|s| s.print_pat(pat))
 301 }
 302
 303 pub fn arm_to_string(arm: &ast::Arm) -> String {
 304     to_string(|s| s.print_arm(arm))
 305 }
 306
 307 pub fn expr_to_string(e: &ast::Expr) -> String {
 308     to_string(|s| s.print_expr(e))
 309 }
 310
 311 pub fn lifetime_to_string(lt: &ast::Lifetime) -> String {
 312     to_string(|s| s.print_lifetime(*lt))
 313 }
 314
 315 pub fn tt_to_string(tt: tokenstream::TokenTree) -> String {
 316     to_string(|s| s.print_tt(tt))
 317 }
 318
 319 pub fn tts_to_string(tts: &[tokenstream::TokenTree]) -> String {
 320     to_string(|s| s.print_tts(tts.iter().cloned().collect()))
 321 }
 322
 323 pub fn tokens_to_string(tokens: TokenStream) -> String {
 324     to_string(|s| s.print_tts(tokens))
 325 }
 326
 327 pub fn stmt_to_string(stmt: &ast::Stmt) -> String {
 328     to_string(|s| s.print_stmt(stmt))
 329 }
 330
 331 pub fn attr_to_string(attr: &ast::Attribute) -> String {
 332     to_string(|s| s.print_attribute(attr))
 333 }
 334
 335 pub fn item_to_string(i: &ast::Item) -> String {
 336     to_string(|s| s.print_item(i))
 337 }
 338
 339 pub fn impl_item_to_string(i: &ast::ImplItem) -> String {
 340     to_string(|s| s.print_impl_item(i))
 341 }
 342
 343 pub fn trait_item_to_string(i: &ast::TraitItem) -> String {
 344     to_string(|s| s.print_trait_item(i))
 345 }
 346
 347 pub fn generic_params_to_string(generic_params: &[ast::GenericParam]) -> String {
 348     to_string(|s| s.print_generic_params(generic_params))
 349 }
 350
 351 pub fn where_clause_to_string(i: &ast::WhereClause) -> String {
 352     to_string(|s| s.print_where_clause(i))
 353 }
 354
 355 pub fn fn_block_to_string(p: &ast::FnDecl) -> String {
 356     to_string(|s| s.print_fn_block_args(p))
 357 }
 358
 359 pub fn path_to_string(p: &ast::Path) -> String {
 360     to_string(|s| s.print_path(p, false, 0))
 361 }
 362
 363 pub fn path_segment_to_string(p: &ast::PathSegment) -> String {
 364     to_string(|s| s.print_path_segment(p, false))
 365 }
 366
 367 pub fn ident_to_string(id: ast::Ident) -> String {
 368     to_string(|s| s.print_ident(id))
 369 }
 370
 371 pub fn vis_to_string(v: &ast::Visibility) -> String {
 372     to_string(|s| s.print_visibility(v))
 373 }
 374
 375 pub fn fun_to_string(decl: &ast::FnDecl,
 376                      header: ast::FnHeader,
 377                      name: ast::Ident,
 378                      generics: &ast::Generics)
 379                      -> String {
 380     to_string(|s| {
 381         s.head("")?;
 382         s.print_fn(decl, header, Some(name),
 383                    generics, &source_map::dummy_spanned(ast::VisibilityKind::Inherited))?;
 384         s.end()?; // Close the head box
 385         s.end() // Close the outer box
 386     })
 387 }
 388
 389 pub fn block_to_string(blk: &ast::Block) -> String {
 390     to_string(|s| {
 391         // containing cbox, will be closed by print-block at }
 392         s.cbox(INDENT_UNIT)?;
 393         // head-ibox, will be closed by print-block after {
 394         s.ibox(0)?;
 395         s.print_block(blk)
 396     })
 397 }
 398
 399 pub fn meta_list_item_to_string(li: &ast::NestedMetaItem) -> String {
 400     to_string(|s| s.print_meta_list_item(li))
 401 }
 402
 403 pub fn meta_item_to_string(mi: &ast::MetaItem) -> String {
 404     to_string(|s| s.print_meta_item(mi))
 405 }
 406
 407 pub fn attribute_to_string(attr: &ast::Attribute) -> String {
 408     to_string(|s| s.print_attribute(attr))
 409 }
 410
 411 pub fn lit_to_string(l: &ast::Lit) -> String {
 412     to_string(|s| s.print_literal(l))
 413 }
 414
 415 pub fn variant_to_string(var: &ast::Variant) -> String {
 416     to_string(|s| s.print_variant(var))
 417 }
 418
 419 pub fn arg_to_string(arg: &ast::Arg) -> String {
 420     to_string(|s| s.print_arg(arg, false))
 421 }
 422
 423 pub fn mac_to_string(arg: &ast::Mac) -> String {
 424     to_string(|s| s.print_mac(arg))
 425 }
 426
 427 pub fn foreign_item_to_string(arg: &ast::ForeignItem) -> String {
 428     to_string(|s| s.print_foreign_item(arg))
 429 }
 430
 431 pub fn visibility_qualified(vis: &ast::Visibility, s: &str) -> String {
 432     format!("{}{}", to_string(|s| s.print_visibility(vis)), s)
 433 }
 434
 435 pub trait PrintState<'a> {
 436     fn writer(&mut self) -> &mut pp::Printer<'a>;
 437     fn boxes(&mut self) -> &mut Vec<pp::Breaks>;
 438     fn comments(&mut self) -> &mut Option<Vec<comments::Comment>>;
 439     fn cur_cmnt(&mut self) -> &mut usize;
 440     fn cur_lit(&mut self) -> Option<&comments::Literal>;
 441     fn bump_lit(&mut self) -> Option<comments::Literal>;
 442
 443     fn word_space(&mut self, w: &str) -> io::Result<()> {
 444         self.writer().word(w)?;
 445         self.writer().space()
 446     }
 447
 448     fn popen(&mut self) -> io::Result<()> { self.writer().word("(") }
 449
 450     fn pclose(&mut self) -> io::Result<()> { self.writer().word(")") }
 451
 452     fn is_begin(&mut self) -> bool {
 453         match self.writer().last_token() {
 454             pp::Token::Begin(_) => true,
 455             _ => false,
 456         }
 457     }
 458
 459     fn is_end(&mut self) -> bool {
 460         match self.writer().last_token() {
 461             pp::Token::End => true,
 462             _ => false,
 463         }
 464     }
 465
 466     // is this the beginning of a line?
 467     fn is_bol(&mut self) -> bool {
 468         self.writer().last_token().is_eof() || self.writer().last_token().is_hardbreak_tok()
 469     }
 470
 471     fn hardbreak_if_not_bol(&mut self) -> io::Result<()> {
 472         if !self.is_bol() {
 473             self.writer().hardbreak()?
 474         }
 475         Ok(())
 476     }
 477
 478     // "raw box"
 479     fn rbox(&mut self, u: usize, b: pp::Breaks) -> io::Result<()> {
 480         self.boxes().push(b);
 481         self.writer().rbox(u, b)
 482     }
 483
 484     fn ibox(&mut self, u: usize) -> io::Result<()> {
 485         self.boxes().push(pp::Breaks::Inconsistent);
 486         self.writer().ibox(u)
 487     }
 488
 489     fn end(&mut self) -> io::Result<()> {
 490         self.boxes().pop().unwrap();
 491         self.writer().end()
 492     }
 493
 494     fn commasep<T, F>(&mut self, b: Breaks, elts: &[T], mut op: F) -> io::Result<()>
 495         where F: FnMut(&mut Self, &T) -> io::Result<()>,
 496     {
 497         self.rbox(0, b)?;
 498         let mut first = true;
 499         for elt in elts {
 500             if first { first = false; } else { self.word_space(",")?; }
 501             op(self, elt)?;
 502         }
 503         self.end()
 504     }
 505
 506     fn next_lit(&mut self, pos: BytePos) -> Option<comments::Literal> {
 507         while let Some(ltrl) = self.cur_lit().cloned() {
 508             if ltrl.pos > pos { break; }
 509
 510             // we don't need the value here since we're forced to clone cur_lit
 511             // due to lack of NLL.
 512             self.bump_lit();
 513             if ltrl.pos == pos {
 514                 return Some(ltrl);
 515             }
 516         }
 517
 518         None
 519     }
 520
 521     fn maybe_print_comment(&mut self, pos: BytePos) -> io::Result<()> {
 522         while let Some(ref cmnt) = self.next_comment() {
 523             if cmnt.pos < pos {
 524                 self.print_comment(cmnt)?;
 525             } else {
 526                 break
 527             }
 528         }
 529         Ok(())
 530     }
 531
 532     fn print_comment(&mut self,
 533                      cmnt: &comments::Comment) -> io::Result<()> {
 534         let r = match cmnt.style {
 535             comments::Mixed => {
 536                 assert_eq!(cmnt.lines.len(), 1);
 537                 self.writer().zerobreak()?;
 538                 self.writer().word(&cmnt.lines[0])?;
 539                 self.writer().zerobreak()
 540             }
 541             comments::Isolated => {
 542                 self.hardbreak_if_not_bol()?;
 543                 for line in &cmnt.lines {
 544                     // Don't print empty lines because they will end up as trailing
 545                     // whitespace
 546                     if !line.is_empty() {
 547                         self.writer().word(&line[..])?;
 548                     }
 549                     self.writer().hardbreak()?;
 550                 }
 551                 Ok(())
 552             }
 553             comments::Trailing => {
 554                 if !self.is_bol() {
 555                     self.writer().word(" ")?;
 556                 }
 557                 if cmnt.lines.len() == 1 {
 558                     self.writer().word(&cmnt.lines[0])?;
 559                     self.writer().hardbreak()
 560                 } else {
 561                     self.ibox(0)?;
 562                     for line in &cmnt.lines {
 563                         if !line.is_empty() {
 564                             self.writer().word(&line[..])?;
 565                         }
 566                         self.writer().hardbreak()?;
 567                     }
 568                     self.end()
 569                 }
 570             }
 571             comments::BlankLine => {
 572                 // We need to do at least one, possibly two hardbreaks.
 573                 let is_semi = match self.writer().last_token() {
 574                     pp::Token::String(s, _) => ";" == s,
 575                     _ => false
 576                 };
 577                 if is_semi || self.is_begin() || self.is_end() {
 578                     self.writer().hardbreak()?;
 579                 }
 580                 self.writer().hardbreak()
 581             }
 582         };
 583         match r {
 584             Ok(()) => {
 585                 *self.cur_cmnt() = *self.cur_cmnt() + 1;
 586                 Ok(())
 587             }
 588             Err(e) => Err(e),
 589         }
 590     }
 591
 592     fn next_comment(&mut self) -> Option<comments::Comment> {
 593         let cur_cmnt = *self.cur_cmnt();
 594         match *self.comments() {
 595             Some(ref cmnts) => {
 596                 if cur_cmnt < cmnts.len() {
 597                     Some(cmnts[cur_cmnt].clone())
 598                 } else {
 599                     None
 600                 }
 601             }
 602             _ => None
 603         }
 604     }
 605
 606     fn print_literal(&mut self, lit: &ast::Lit) -> io::Result<()> {
 607         self.maybe_print_comment(lit.span.lo())?;
 608         if let Some(ltrl) = self.next_lit(lit.span.lo()) {
 609             return self.writer().word(&ltrl.lit);
 610         }
 611         match lit.node {
 612             ast::LitKind::Str(st, style) => self.print_string(&st.as_str(), style),
 613             ast::LitKind::Byte(byte) => {
 614                 let mut res = String::from("b'");
 615                 res.extend(ascii::escape_default(byte).map(|c| c as char));
 616                 res.push('\'');
 617                 self.writer().word(&res[..])
 618             }
 619             ast::LitKind::Char(ch) => {
 620                 let mut res = String::from("'");
 621                 res.extend(ch.escape_default());
 622                 res.push('\'');
 623                 self.writer().word(&res[..])
 624             }
 625             ast::LitKind::Int(i, t) => {
 626                 match t {
 627                     ast::LitIntType::Signed(st) => {
 628                         self.writer().word(&st.val_to_string(i as i128))
 629                     }
 630                     ast::LitIntType::Unsigned(ut) => {
 631                         self.writer().word(&ut.val_to_string(i))
 632                     }
 633                     ast::LitIntType::Unsuffixed => {
 634                         self.writer().word(&i.to_string())
 635                     }
 636                 }
 637             }
 638             ast::LitKind::Float(ref f, t) => {
 639                 self.writer().word(&format!("{}{}", &f, t.ty_to_string()))
 640             }
 641             ast::LitKind::FloatUnsuffixed(ref f) => self.writer().word(&f.as_str()),
 642             ast::LitKind::Bool(val) => {
 643                 if val { self.writer().word("true") } else { self.writer().word("false") }
 644             }
 645             ast::LitKind::ByteStr(ref v) => {
 646                 let mut escaped: String = String::new();
 647                 for &ch in v.iter() {
 648                     escaped.extend(ascii::escape_default(ch)
 649                                          .map(|c| c as char));
 650                 }
 651                 self.writer().word(&format!("b\"{}\"", escaped))
 652             }
 653         }
 654     }
 655
 656     fn print_string(&mut self, st: &str,
 657                     style: ast::StrStyle) -> io::Result<()> {
 658         let st = match style {
 659             ast::StrStyle::Cooked => {
 660                 (format!("\"{}\"", st.escape_debug()))
 661             }
 662             ast::StrStyle::Raw(n) => {
 663                 (format!("r{delim}\"{string}\"{delim}",
 664                          delim="#".repeat(n as usize),
 665                          string=st))
 666             }
 667         };
 668         self.writer().word(&st[..])
 669     }
 670
 671     fn print_inner_attributes(&mut self,
 672                               attrs: &[ast::Attribute]) -> io::Result<()> {
 673         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, true)
 674     }
 675
 676     fn print_inner_attributes_no_trailing_hardbreak(&mut self,
 677                                                    attrs: &[ast::Attribute])
 678                                                    -> io::Result<()> {
 679         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, false)
 680     }
 681
 682     fn print_outer_attributes(&mut self,
 683                               attrs: &[ast::Attribute]) -> io::Result<()> {
 684         self.print_either_attributes(attrs, ast::AttrStyle::Outer, false, true)
 685     }
 686
 687     fn print_inner_attributes_inline(&mut self,
 688                                      attrs: &[ast::Attribute]) -> io::Result<()> {
 689         self.print_either_attributes(attrs, ast::AttrStyle::Inner, true, true)
 690     }
 691
 692     fn print_outer_attributes_inline(&mut self,
 693                                      attrs: &[ast::Attribute]) -> io::Result<()> {
 694         self.print_either_attributes(attrs, ast::AttrStyle::Outer, true, true)
 695     }
 696
 697     fn print_either_attributes(&mut self,
 698                               attrs: &[ast::Attribute],
 699                               kind: ast::AttrStyle,
 700                               is_inline: bool,
 701                               trailing_hardbreak: bool) -> io::Result<()> {
 702         let mut count = 0;
 703         for attr in attrs {
 704             if attr.style == kind {
 705                 self.print_attribute_inline(attr, is_inline)?;
 706                 if is_inline {
 707                     self.nbsp()?;
 708                 }
 709                 count += 1;
 710             }
 711         }
 712         if count > 0 && trailing_hardbreak && !is_inline {
 713             self.hardbreak_if_not_bol()?;
 714         }
 715         Ok(())
 716     }
 717
 718     fn print_attribute_path(&mut self, path: &ast::Path) -> io::Result<()> {
 719         for (i, segment) in path.segments.iter().enumerate() {
 720             if i > 0 {
 721                 self.writer().word("::")?
 722             }
 723             if segment.ident.name != keywords::CrateRoot.name() &&
 724                segment.ident.name != keywords::DollarCrate.name()
 725             {
 726                 self.writer().word(&segment.ident.as_str())?;
 727             } else if segment.ident.name == keywords::DollarCrate.name() {
 728                 self.print_dollar_crate(segment.ident.span.ctxt())?;
 729             }
 730         }
 731         Ok(())
 732     }
 733
 734     fn print_attribute(&mut self, attr: &ast::Attribute) -> io::Result<()> {
 735         self.print_attribute_inline(attr, false)
 736     }
 737
 738     fn print_attribute_inline(&mut self, attr: &ast::Attribute,
 739                               is_inline: bool) -> io::Result<()> {
 740         if !is_inline {
 741             self.hardbreak_if_not_bol()?;
 742         }
 743         self.maybe_print_comment(attr.span.lo())?;
 744         if attr.is_sugared_doc {
 745             self.writer().word(&attr.value_str().unwrap().as_str())?;
 746             self.writer().hardbreak()
 747         } else {
 748             match attr.style {
 749                 ast::AttrStyle::Inner => self.writer().word("#![")?,
 750                 ast::AttrStyle::Outer => self.writer().word("#[")?,
 751             }
 752             if let Some(mi) = attr.meta() {
 753                 self.print_meta_item(&mi)?
 754             } else {
 755                 self.print_attribute_path(&attr.path)?;
 756                 self.writer().space()?;
 757                 self.print_tts(attr.tokens.clone())?;
 758             }
 759             self.writer().word("]")
 760         }
 761     }
 762
 763     fn print_meta_list_item(&mut self, item: &ast::NestedMetaItem) -> io::Result<()> {
 764         match item.node {
 765             ast::NestedMetaItemKind::MetaItem(ref mi) => {
 766                 self.print_meta_item(mi)
 767             },
 768             ast::NestedMetaItemKind::Literal(ref lit) => {
 769                 self.print_literal(lit)
 770             }
 771         }
 772     }
 773
 774     fn print_meta_item(&mut self, item: &ast::MetaItem) -> io::Result<()> {
 775         self.ibox(INDENT_UNIT)?;
 776         match item.node {
 777             ast::MetaItemKind::Word => self.print_attribute_path(&item.ident)?,
 778             ast::MetaItemKind::NameValue(ref value) => {
 779                 self.print_attribute_path(&item.ident)?;
 780                 self.writer().space()?;
 781                 self.word_space("=")?;
 782                 self.print_literal(value)?;
 783             }
 784             ast::MetaItemKind::List(ref items) => {
 785                 self.print_attribute_path(&item.ident)?;
 786                 self.popen()?;
 787                 self.commasep(Consistent,
 788                               &items[..],
 789                               |s, i| s.print_meta_list_item(i))?;
 790                 self.pclose()?;
 791             }
 792         }
 793         self.end()
 794     }
 795
 796     /// This doesn't deserve to be called "pretty" printing, but it should be
 797     /// meaning-preserving. A quick hack that might help would be to look at the
 798     /// spans embedded in the TTs to decide where to put spaces and newlines.
 799     /// But it'd be better to parse these according to the grammar of the
 800     /// appropriate macro, transcribe back into the grammar we just parsed from,
 801     /// and then pretty-print the resulting AST nodes (so, e.g., we print
 802     /// expression arguments as expressions). It can be done! I think.
 803     fn print_tt(&mut self, tt: tokenstream::TokenTree) -> io::Result<()> {
 804         match tt {
 805             TokenTree::Token(_, ref tk) => {
 806                 self.writer().word(&token_to_string(tk))?;
 807                 match *tk {
 808                     parse::token::DocComment(..) => {
 809                         self.writer().hardbreak()
 810                     }
 811                     _ => Ok(())
 812                 }
 813             }
 814             TokenTree::Delimited(_, ref delimed) => {
 815                 self.writer().word(&token_to_string(&delimed.open_token()))?;
 816                 self.writer().space()?;
 817                 self.print_tts(delimed.stream())?;
 818                 self.writer().space()?;
 819                 self.writer().word(&token_to_string(&delimed.close_token()))
 820             },
 821         }
 822     }
 823
 824     fn print_tts(&mut self, tts: tokenstream::TokenStream) -> io::Result<()> {
 825         self.ibox(0)?;
 826         for (i, tt) in tts.into_trees().enumerate() {
 827             if i != 0 {
 828                 self.writer().space()?;
 829             }
 830             self.print_tt(tt)?;
 831         }
 832         self.end()
 833     }
 834
 835     fn space_if_not_bol(&mut self) -> io::Result<()> {
 836         if !self.is_bol() { self.writer().space()?; }
 837         Ok(())
 838     }
 839
 840     fn nbsp(&mut self) -> io::Result<()> { self.writer().word(" ") }
 841
 842     fn print_dollar_crate(&mut self, mut ctxt: SyntaxContext) -> io::Result<()> {
 843         if let Some(mark) = ctxt.adjust(Mark::root()) {
 844             // Make a best effort to print something that complies
 845             if mark.is_builtin() {
 846                 if let Some(name) = std_inject::injected_crate_name() {
 847                     self.writer().word("::")?;
 848                     self.writer().word(name)?;
 849                 }
 850             }
 851         }
 852         Ok(())
 853     }
 854 }
 855
 856 impl<'a> PrintState<'a> for State<'a> {
 857     fn writer(&mut self) -> &mut pp::Printer<'a> {
 858         &mut self.s
 859     }
 860
 861     fn boxes(&mut self) -> &mut Vec<pp::Breaks> {
 862         &mut self.boxes
 863     }
 864
 865     fn comments(&mut self) -> &mut Option<Vec<comments::Comment>> {
 866         &mut self.comments
 867     }
 868
 869     fn cur_cmnt(&mut self) -> &mut usize {
 870         &mut self.cur_cmnt
 871     }
 872
 873     fn cur_lit(&mut self) -> Option<&comments::Literal> {
 874         self.literals.peek()
 875     }
 876
 877     fn bump_lit(&mut self) -> Option<comments::Literal> {
 878         self.literals.next()
 879     }
 880 }
 881
 882 impl<'a> State<'a> {
 883     pub fn cbox(&mut self, u: usize) -> io::Result<()> {
 884         self.boxes.push(pp::Breaks::Consistent);
 885         self.s.cbox(u)
 886     }
 887
 888     pub fn word_nbsp(&mut self, w: &str) -> io::Result<()> {
 889         self.s.word(w)?;
 890         self.nbsp()
 891     }
 892
 893     pub fn head(&mut self, w: &str) -> io::Result<()> {
 894         // outer-box is consistent
 895         self.cbox(INDENT_UNIT)?;
 896         // head-box is inconsistent
 897         self.ibox(w.len() + 1)?;
 898         // keyword that starts the head
 899         if !w.is_empty() {
 900             self.word_nbsp(w)?;
 901         }
 902         Ok(())
 903     }
 904
 905     pub fn bopen(&mut self) -> io::Result<()> {
 906         self.s.word("{")?;
 907         self.end() // close the head-box
 908     }
 909
 910     pub fn bclose_(&mut self, span: syntax_pos::Span,
 911                    indented: usize) -> io::Result<()> {
 912         self.bclose_maybe_open(span, indented, true)
 913     }
 914     pub fn bclose_maybe_open(&mut self, span: syntax_pos::Span,
 915                              indented: usize, close_box: bool) -> io::Result<()> {
 916         self.maybe_print_comment(span.hi())?;
 917         self.break_offset_if_not_bol(1, -(indented as isize))?;
 918         self.s.word("}")?;
 919         if close_box {
 920             self.end()?; // close the outer-box
 921         }
 922         Ok(())
 923     }
 924     pub fn bclose(&mut self, span: syntax_pos::Span) -> io::Result<()> {
 925         self.bclose_(span, INDENT_UNIT)
 926     }
 927
 928     pub fn in_cbox(&self) -> bool {
 929         match self.boxes.last() {
 930             Some(&last_box) => last_box == pp::Breaks::Consistent,
 931             None => false
 932         }
 933     }
 934
 935     pub fn break_offset_if_not_bol(&mut self, n: usize,
 936                                    off: isize) -> io::Result<()> {
 937         if !self.is_bol() {
 938             self.s.break_offset(n, off)
 939         } else {
 940             if off != 0 && self.s.last_token().is_hardbreak_tok() {
 941                 // We do something pretty sketchy here: tuck the nonzero
 942                 // offset-adjustment we were going to deposit along with the
 943                 // break into the previous hardbreak.
 944                 self.s.replace_last_token(pp::Printer::hardbreak_tok_offset(off));
 945             }
 946             Ok(())
 947         }
 948     }
 949
 950     // Synthesizes a comment that was not textually present in the original source
 951     // file.
 952     pub fn synth_comment(&mut self, text: String) -> io::Result<()> {
 953         self.s.word("/*")?;
 954         self.s.space()?;
 955         self.s.word(&text[..])?;
 956         self.s.space()?;
 957         self.s.word("*/")
 958     }
 959
 960
 961
 962     pub fn commasep_cmnt<T, F, G>(&mut self,
 963                                   b: Breaks,
 964                                   elts: &[T],
 965                                   mut op: F,
 966                                   mut get_span: G) -> io::Result<()> where
 967         F: FnMut(&mut State, &T) -> io::Result<()>,
 968         G: FnMut(&T) -> syntax_pos::Span,
 969     {
 970         self.rbox(0, b)?;
 971         let len = elts.len();
 972         let mut i = 0;
 973         for elt in elts {
 974             self.maybe_print_comment(get_span(elt).hi())?;
 975             op(self, elt)?;
 976             i += 1;
 977             if i < len {
 978                 self.s.word(",")?;
 979                 self.maybe_print_trailing_comment(get_span(elt),
 980                                                   Some(get_span(&elts[i]).hi()))?;
 981                 self.space_if_not_bol()?;
 982             }
 983         }
 984         self.end()
 985     }
 986
 987     pub fn commasep_exprs(&mut self, b: Breaks,
 988                           exprs: &[P<ast::Expr>]) -> io::Result<()> {
 989         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(e), |e| e.span)
 990     }
 991
 992     pub fn print_mod(&mut self, _mod: &ast::Mod,
 993                      attrs: &[ast::Attribute]) -> io::Result<()> {
 994         self.print_inner_attributes(attrs)?;
 995         for item in &_mod.items {
 996             self.print_item(item)?;
 997         }
 998         Ok(())
 999     }
1000
1001     pub fn print_foreign_mod(&mut self, nmod: &ast::ForeignMod,
1002                              attrs: &[ast::Attribute]) -> io::Result<()> {
1003         self.print_inner_attributes(attrs)?;
1004         for item in &nmod.items {
1005             self.print_foreign_item(item)?;
1006         }
1007         Ok(())
1008     }
1009
1010     pub fn print_opt_lifetime(&mut self, lifetime: &Option<ast::Lifetime>) -> io::Result<()> {
1011         if let Some(lt) = *lifetime {
1012             self.print_lifetime(lt)?;
1013             self.nbsp()?;
1014         }
1015         Ok(())
1016     }
1017
1018     pub fn print_generic_arg(&mut self, generic_arg: &GenericArg) -> io::Result<()> {
1019         match generic_arg {
1020             GenericArg::Lifetime(lt) => self.print_lifetime(*lt),
1021             GenericArg::Type(ty) => self.print_type(ty),
1022         }
1023     }
1024
1025     pub fn print_type(&mut self, ty: &ast::Ty) -> io::Result<()> {
1026         self.maybe_print_comment(ty.span.lo())?;
1027         self.ibox(0)?;
1028         match ty.node {
1029             ast::TyKind::Slice(ref ty) => {
1030                 self.s.word("[")?;
1031                 self.print_type(ty)?;
1032                 self.s.word("]")?;
1033             }
1034             ast::TyKind::Ptr(ref mt) => {
1035                 self.s.word("*")?;
1036                 match mt.mutbl {
1037                     ast::Mutability::Mutable => self.word_nbsp("mut")?,
1038                     ast::Mutability::Immutable => self.word_nbsp("const")?,
1039                 }
1040                 self.print_type(&mt.ty)?;
1041             }
1042             ast::TyKind::Rptr(ref lifetime, ref mt) => {
1043                 self.s.word("&")?;
1044                 self.print_opt_lifetime(lifetime)?;
1045                 self.print_mt(mt)?;
1046             }
1047             ast::TyKind::Never => {
1048                 self.s.word("!")?;
1049             },
1050             ast::TyKind::Tup(ref elts) => {
1051                 self.popen()?;
1052                 self.commasep(Inconsistent, &elts[..],
1053                               |s, ty| s.print_type(ty))?;
1054                 if elts.len() == 1 {
1055                     self.s.word(",")?;
1056                 }
1057                 self.pclose()?;
1058             }
1059             ast::TyKind::Paren(ref typ) => {
1060                 self.popen()?;
1061                 self.print_type(typ)?;
1062                 self.pclose()?;
1063             }
1064             ast::TyKind::BareFn(ref f) => {
1065                 self.print_ty_fn(f.abi,
1066                                  f.unsafety,
1067                                  &f.decl,
1068                                  None,
1069                                  &f.generic_params)?;
1070             }
1071             ast::TyKind::Path(None, ref path) => {
1072                 self.print_path(path, false, 0)?;
1073             }
1074             ast::TyKind::Path(Some(ref qself), ref path) => {
1075                 self.print_qpath(path, qself, false)?
1076             }
1077             ast::TyKind::TraitObject(ref bounds, syntax) => {
1078                 let prefix = if syntax == ast::TraitObjectSyntax::Dyn { "dyn" } else { "" };
1079                 self.print_type_bounds(prefix, &bounds[..])?;
1080             }
1081             ast::TyKind::ImplTrait(_, ref bounds) => {
1082                 self.print_type_bounds("impl", &bounds[..])?;
1083             }
1084             ast::TyKind::Array(ref ty, ref length) => {
1085                 self.s.word("[")?;
1086                 self.print_type(ty)?;
1087                 self.s.word("; ")?;
1088                 self.print_expr(&length.value)?;
1089                 self.s.word("]")?;
1090             }
1091             ast::TyKind::Typeof(ref e) => {
1092                 self.s.word("typeof(")?;
1093                 self.print_expr(&e.value)?;
1094                 self.s.word(")")?;
1095             }
1096             ast::TyKind::Infer => {
1097                 self.s.word("_")?;
1098             }
1099             ast::TyKind::Err => {
1100                 self.s.word("?")?;
1101             }
1102             ast::TyKind::ImplicitSelf => {
1103                 self.s.word("Self")?;
1104             }
1105             ast::TyKind::Mac(ref m) => {
1106                 self.print_mac(m)?;
1107             }
1108         }
1109         self.end()
1110     }
1111
1112     pub fn print_foreign_item(&mut self,
1113                               item: &ast::ForeignItem) -> io::Result<()> {
1114         self.hardbreak_if_not_bol()?;
1115         self.maybe_print_comment(item.span.lo())?;
1116         self.print_outer_attributes(&item.attrs)?;
1117         match item.node {
1118             ast::ForeignItemKind::Fn(ref decl, ref generics) => {
1119                 self.head("")?;
1120                 self.print_fn(decl, ast::FnHeader::default(),
1121                               Some(item.ident),
1122                               generics, &item.vis)?;
1123                 self.end()?; // end head-ibox
1124                 self.s.word(";")?;
1125                 self.end() // end the outer fn box
1126             }
1127             ast::ForeignItemKind::Static(ref t, m) => {
1128                 self.head(&visibility_qualified(&item.vis, "static"))?;
1129                 if m {
1130                     self.word_space("mut")?;
1131                 }
1132                 self.print_ident(item.ident)?;
1133                 self.word_space(":")?;
1134                 self.print_type(t)?;
1135                 self.s.word(";")?;
1136                 self.end()?; // end the head-ibox
1137                 self.end() // end the outer cbox
1138             }
1139             ast::ForeignItemKind::Ty => {
1140                 self.head(&visibility_qualified(&item.vis, "type"))?;
1141                 self.print_ident(item.ident)?;
1142                 self.s.word(";")?;
1143                 self.end()?; // end the head-ibox
1144                 self.end() // end the outer cbox
1145             }
1146             ast::ForeignItemKind::Macro(ref m) => {
1147                 self.print_mac(m)?;
1148                 match m.node.delim {
1149                     MacDelimiter::Brace => Ok(()),
1150                     _ => self.s.word(";")
1151                 }
1152             }
1153         }
1154     }
1155
1156     fn print_associated_const(&mut self,
1157                               ident: ast::Ident,
1158                               ty: &ast::Ty,
1159                               default: Option<&ast::Expr>,
1160                               vis: &ast::Visibility)
1161                               -> io::Result<()>
1162     {
1163         self.s.word(&visibility_qualified(vis, ""))?;
1164         self.word_space("const")?;
1165         self.print_ident(ident)?;
1166         self.word_space(":")?;
1167         self.print_type(ty)?;
1168         if let Some(expr) = default {
1169             self.s.space()?;
1170             self.word_space("=")?;
1171             self.print_expr(expr)?;
1172         }
1173         self.s.word(";")
1174     }
1175
1176     fn print_associated_type(&mut self,
1177                              ident: ast::Ident,
1178                              bounds: Option<&ast::GenericBounds>,
1179                              ty: Option<&ast::Ty>)
1180                              -> io::Result<()> {
1181         self.word_space("type")?;
1182         self.print_ident(ident)?;
1183         if let Some(bounds) = bounds {
1184             self.print_type_bounds(":", bounds)?;
1185         }
1186         if let Some(ty) = ty {
1187             self.s.space()?;
1188             self.word_space("=")?;
1189             self.print_type(ty)?;
1190         }
1191         self.s.word(";")
1192     }
1193
1194     /// Pretty-print an item
1195     pub fn print_item(&mut self, item: &ast::Item) -> io::Result<()> {
1196         self.hardbreak_if_not_bol()?;
1197         self.maybe_print_comment(item.span.lo())?;
1198         self.print_outer_attributes(&item.attrs)?;
1199         self.ann.pre(self, NodeItem(item))?;
1200         match item.node {
1201             ast::ItemKind::ExternCrate(orig_name) => {
1202                 self.head(&visibility_qualified(&item.vis, "extern crate"))?;
1203                 if let Some(orig_name) = orig_name {
1204                     self.print_name(orig_name)?;
1205                     self.s.space()?;
1206                     self.s.word("as")?;
1207                     self.s.space()?;
1208                 }
1209                 self.print_ident(item.ident)?;
1210                 self.s.word(";")?;
1211                 self.end()?; // end inner head-block
1212                 self.end()?; // end outer head-block
1213             }
1214             ast::ItemKind::Use(ref tree) => {
1215                 self.head(&visibility_qualified(&item.vis, "use"))?;
1216                 self.print_use_tree(tree)?;
1217                 self.s.word(";")?;
1218                 self.end()?; // end inner head-block
1219                 self.end()?; // end outer head-block
1220             }
1221             ast::ItemKind::Static(ref ty, m, ref expr) => {
1222                 self.head(&visibility_qualified(&item.vis, "static"))?;
1223                 if m == ast::Mutability::Mutable {
1224                     self.word_space("mut")?;
1225                 }
1226                 self.print_ident(item.ident)?;
1227                 self.word_space(":")?;
1228                 self.print_type(ty)?;
1229                 self.s.space()?;
1230                 self.end()?; // end the head-ibox
1231
1232                 self.word_space("=")?;
1233                 self.print_expr(expr)?;
1234                 self.s.word(";")?;
1235                 self.end()?; // end the outer cbox
1236             }
1237             ast::ItemKind::Const(ref ty, ref expr) => {
1238                 self.head(&visibility_qualified(&item.vis, "const"))?;
1239                 self.print_ident(item.ident)?;
1240                 self.word_space(":")?;
1241                 self.print_type(ty)?;
1242                 self.s.space()?;
1243                 self.end()?; // end the head-ibox
1244
1245                 self.word_space("=")?;
1246                 self.print_expr(expr)?;
1247                 self.s.word(";")?;
1248                 self.end()?; // end the outer cbox
1249             }
1250             ast::ItemKind::Fn(ref decl, header, ref typarams, ref body) => {
1251                 self.head("")?;
1252                 self.print_fn(
1253                     decl,
1254                     header,
1255                     Some(item.ident),
1256                     typarams,
1257                     &item.vis
1258                 )?;
1259                 self.s.word(" ")?;
1260                 self.print_block_with_attrs(body, &item.attrs)?;
1261             }
1262             ast::ItemKind::Mod(ref _mod) => {
1263                 self.head(&visibility_qualified(&item.vis, "mod"))?;
1264                 self.print_ident(item.ident)?;
1265                 self.nbsp()?;
1266                 self.bopen()?;
1267                 self.print_mod(_mod, &item.attrs)?;
1268                 self.bclose(item.span)?;
1269             }
1270             ast::ItemKind::ForeignMod(ref nmod) => {
1271                 self.head("extern")?;
1272                 self.word_nbsp(&nmod.abi.to_string())?;
1273                 self.bopen()?;
1274                 self.print_foreign_mod(nmod, &item.attrs)?;
1275                 self.bclose(item.span)?;
1276             }
1277             ast::ItemKind::GlobalAsm(ref ga) => {
1278                 self.head(&visibility_qualified(&item.vis, "global_asm!"))?;
1279                 self.s.word(&ga.asm.as_str())?;
1280                 self.end()?;
1281             }
1282             ast::ItemKind::Ty(ref ty, ref generics) => {
1283                 self.head(&visibility_qualified(&item.vis, "type"))?;
1284                 self.print_ident(item.ident)?;
1285                 self.print_generic_params(&generics.params)?;
1286                 self.end()?; // end the inner ibox
1287
1288                 self.print_where_clause(&generics.where_clause)?;
1289                 self.s.space()?;
1290                 self.word_space("=")?;
1291                 self.print_type(ty)?;
1292                 self.s.word(";")?;
1293                 self.end()?; // end the outer ibox
1294             }
1295             ast::ItemKind::Existential(ref bounds, ref generics) => {
1296                 self.head(&visibility_qualified(&item.vis, "existential type"))?;
1297                 self.print_ident(item.ident)?;
1298                 self.print_generic_params(&generics.params)?;
1299                 self.end()?; // end the inner ibox
1300
1301                 self.print_where_clause(&generics.where_clause)?;
1302                 self.s.space()?;
1303                 self.print_type_bounds(":", bounds)?;
1304                 self.s.word(";")?;
1305                 self.end()?; // end the outer ibox
1306             }
1307             ast::ItemKind::Enum(ref enum_definition, ref params) => {
1308                 self.print_enum_def(
1309                     enum_definition,
1310                     params,
1311                     item.ident,
1312                     item.span,
1313                     &item.vis
1314                 )?;
1315             }
1316             ast::ItemKind::Struct(ref struct_def, ref generics) => {
1317                 self.head(&visibility_qualified(&item.vis, "struct"))?;
1318                 self.print_struct(struct_def, generics, item.ident, item.span, true)?;
1319             }
1320             ast::ItemKind::Union(ref struct_def, ref generics) => {
1321                 self.head(&visibility_qualified(&item.vis, "union"))?;
1322                 self.print_struct(struct_def, generics, item.ident, item.span, true)?;
1323             }
1324             ast::ItemKind::Impl(unsafety,
1325                           polarity,
1326                           defaultness,
1327                           ref generics,
1328                           ref opt_trait,
1329                           ref ty,
1330                           ref impl_items) => {
1331                 self.head("")?;
1332                 self.print_visibility(&item.vis)?;
1333                 self.print_defaultness(defaultness)?;
1334                 self.print_unsafety(unsafety)?;
1335                 self.word_nbsp("impl")?;
1336
1337                 if !generics.params.is_empty() {
1338                     self.print_generic_params(&generics.params)?;
1339                     self.s.space()?;
1340                 }
1341
1342                 if polarity == ast::ImplPolarity::Negative {
1343                     self.s.word("!")?;
1344                 }
1345
1346                 if let Some(ref t) = *opt_trait {
1347                     self.print_trait_ref(t)?;
1348                     self.s.space()?;
1349                     self.word_space("for")?;
1350                 }
1351
1352                 self.print_type(ty)?;
1353                 self.print_where_clause(&generics.where_clause)?;
1354
1355                 self.s.space()?;
1356                 self.bopen()?;
1357                 self.print_inner_attributes(&item.attrs)?;
1358                 for impl_item in impl_items {
1359                     self.print_impl_item(impl_item)?;
1360                 }
1361                 self.bclose(item.span)?;
1362             }
1363             ast::ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref trait_items) => {
1364                 self.head("")?;
1365                 self.print_visibility(&item.vis)?;
1366                 self.print_unsafety(unsafety)?;
1367                 self.print_is_auto(is_auto)?;
1368                 self.word_nbsp("trait")?;
1369                 self.print_ident(item.ident)?;
1370                 self.print_generic_params(&generics.params)?;
1371                 let mut real_bounds = Vec::with_capacity(bounds.len());
1372                 for b in bounds.iter() {
1373                     if let GenericBound::Trait(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
1374                         self.s.space()?;
1375                         self.word_space("for ?")?;
1376                         self.print_trait_ref(&ptr.trait_ref)?;
1377                     } else {
1378                         real_bounds.push(b.clone());
1379                     }
1380                 }
1381                 self.print_type_bounds(":", &real_bounds[..])?;
1382                 self.print_where_clause(&generics.where_clause)?;
1383                 self.s.word(" ")?;
1384                 self.bopen()?;
1385                 for trait_item in trait_items {
1386                     self.print_trait_item(trait_item)?;
1387                 }
1388                 self.bclose(item.span)?;
1389             }
1390             ast::ItemKind::TraitAlias(ref generics, ref bounds) => {
1391                 self.head("")?;
1392                 self.print_visibility(&item.vis)?;
1393                 self.word_nbsp("trait")?;
1394                 self.print_ident(item.ident)?;
1395                 self.print_generic_params(&generics.params)?;
1396                 let mut real_bounds = Vec::with_capacity(bounds.len());
1397                 // FIXME(durka) this seems to be some quite outdated syntax
1398                 for b in bounds.iter() {
1399                     if let GenericBound::Trait(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
1400                         self.s.space()?;
1401                         self.word_space("for ?")?;
1402                         self.print_trait_ref(&ptr.trait_ref)?;
1403                     } else {
1404                         real_bounds.push(b.clone());
1405                     }
1406                 }
1407                 self.nbsp()?;
1408                 self.print_type_bounds("=", &real_bounds[..])?;
1409                 self.print_where_clause(&generics.where_clause)?;
1410                 self.s.word(";")?;
1411             }
1412             ast::ItemKind::Mac(ref mac) => {
1413                 if item.ident.name == keywords::Invalid.name() {
1414                     self.print_mac(mac)?;
1415                     match mac.node.delim {
1416                         MacDelimiter::Brace => {}
1417                         _ => self.s.word(";")?,
1418                     }
1419                 } else {
1420                     self.print_path(&mac.node.path, false, 0)?;
1421                     self.s.word("! ")?;
1422                     self.print_ident(item.ident)?;
1423                     self.cbox(INDENT_UNIT)?;
1424                     self.popen()?;
1425                     self.print_tts(mac.node.stream())?;
1426                     self.pclose()?;
1427                     self.s.word(";")?;
1428                     self.end()?;
1429                 }
1430             }
1431             ast::ItemKind::MacroDef(ref tts) => {
1432                 self.s.word("macro_rules! ")?;
1433                 self.print_ident(item.ident)?;
1434                 self.cbox(INDENT_UNIT)?;
1435                 self.popen()?;
1436                 self.print_tts(tts.stream())?;
1437                 self.pclose()?;
1438                 self.s.word(";")?;
1439                 self.end()?;
1440             }
1441         }
1442         self.ann.post(self, NodeItem(item))
1443     }
1444
1445     fn print_trait_ref(&mut self, t: &ast::TraitRef) -> io::Result<()> {
1446         self.print_path(&t.path, false, 0)
1447     }
1448
1449     fn print_formal_generic_params(
1450         &mut self,
1451         generic_params: &[ast::GenericParam]
1452     ) -> io::Result<()> {
1453         if !generic_params.is_empty() {
1454             self.s.word("for")?;
1455             self.print_generic_params(generic_params)?;
1456             self.nbsp()?;
1457         }
1458         Ok(())
1459     }
1460
1461     fn print_poly_trait_ref(&mut self, t: &ast::PolyTraitRef) -> io::Result<()> {
1462         self.print_formal_generic_params(&t.bound_generic_params)?;
1463         self.print_trait_ref(&t.trait_ref)
1464     }
1465
1466     pub fn print_enum_def(&mut self, enum_definition: &ast::EnumDef,
1467                           generics: &ast::Generics, ident: ast::Ident,
1468                           span: syntax_pos::Span,
1469                           visibility: &ast::Visibility) -> io::Result<()> {
1470         self.head(&visibility_qualified(visibility, "enum"))?;
1471         self.print_ident(ident)?;
1472         self.print_generic_params(&generics.params)?;
1473         self.print_where_clause(&generics.where_clause)?;
1474         self.s.space()?;
1475         self.print_variants(&enum_definition.variants, span)
1476     }
1477
1478     pub fn print_variants(&mut self,
1479                           variants: &[ast::Variant],
1480                           span: syntax_pos::Span) -> io::Result<()> {
1481         self.bopen()?;
1482         for v in variants {
1483             self.space_if_not_bol()?;
1484             self.maybe_print_comment(v.span.lo())?;
1485             self.print_outer_attributes(&v.node.attrs)?;
1486             self.ibox(INDENT_UNIT)?;
1487             self.print_variant(v)?;
1488             self.s.word(",")?;
1489             self.end()?;
1490             self.maybe_print_trailing_comment(v.span, None)?;
1491         }
1492         self.bclose(span)
1493     }
1494
1495     pub fn print_visibility(&mut self, vis: &ast::Visibility) -> io::Result<()> {
1496         match vis.node {
1497             ast::VisibilityKind::Public => self.word_nbsp("pub"),
1498             ast::VisibilityKind::Crate(sugar) => match sugar {
1499                 ast::CrateSugar::PubCrate => self.word_nbsp("pub(crate)"),
1500                 ast::CrateSugar::JustCrate => self.word_nbsp("crate")
1501             }
1502             ast::VisibilityKind::Restricted { ref path, .. } => {
1503                 let path = to_string(|s| s.print_path(path, false, 0));
1504                 if path == "self" || path == "super" {
1505                     self.word_nbsp(&format!("pub({})", path))
1506                 } else {
1507                     self.word_nbsp(&format!("pub(in {})", path))
1508                 }
1509             }
1510             ast::VisibilityKind::Inherited => Ok(())
1511         }
1512     }
1513
1514     pub fn print_defaultness(&mut self, defaultness: ast::Defaultness) -> io::Result<()> {
1515         if let ast::Defaultness::Default = defaultness {
1516             try!(self.word_nbsp("default"));
1517         }
1518         Ok(())
1519     }
1520
1521     pub fn print_struct(&mut self,
1522                         struct_def: &ast::VariantData,
1523                         generics: &ast::Generics,
1524                         ident: ast::Ident,
1525                         span: syntax_pos::Span,
1526                         print_finalizer: bool) -> io::Result<()> {
1527         self.print_ident(ident)?;
1528         self.print_generic_params(&generics.params)?;
1529         if !struct_def.is_struct() {
1530             if struct_def.is_tuple() {
1531                 self.popen()?;
1532                 self.commasep(
1533                     Inconsistent, struct_def.fields(),
1534                     |s, field| {
1535                         s.maybe_print_comment(field.span.lo())?;
1536                         s.print_outer_attributes(&field.attrs)?;
1537                         s.print_visibility(&field.vis)?;
1538                         s.print_type(&field.ty)
1539                     }
1540                 )?;
1541                 self.pclose()?;
1542             }
1543             self.print_where_clause(&generics.where_clause)?;
1544             if print_finalizer {
1545                 self.s.word(";")?;
1546             }
1547             self.end()?;
1548             self.end() // close the outer-box
1549         } else {
1550             self.print_where_clause(&generics.where_clause)?;
1551             self.nbsp()?;
1552             self.bopen()?;
1553             self.hardbreak_if_not_bol()?;
1554
1555             for field in struct_def.fields() {
1556                 self.hardbreak_if_not_bol()?;
1557                 self.maybe_print_comment(field.span.lo())?;
1558                 self.print_outer_attributes(&field.attrs)?;
1559                 self.print_visibility(&field.vis)?;
1560                 self.print_ident(field.ident.unwrap())?;
1561                 self.word_nbsp(":")?;
1562                 self.print_type(&field.ty)?;
1563                 self.s.word(",")?;
1564             }
1565
1566             self.bclose(span)
1567         }
1568     }
1569
1570     pub fn print_variant(&mut self, v: &ast::Variant) -> io::Result<()> {
1571         self.head("")?;
1572         let generics = ast::Generics::default();
1573         self.print_struct(&v.node.data, &generics, v.node.ident, v.span, false)?;
1574         match v.node.disr_expr {
1575             Some(ref d) => {
1576                 self.s.space()?;
1577                 self.word_space("=")?;
1578                 self.print_expr(&d.value)
1579             }
1580             _ => Ok(())
1581         }
1582     }
1583
1584     pub fn print_method_sig(&mut self,
1585                             ident: ast::Ident,
1586                             generics: &ast::Generics,
1587                             m: &ast::MethodSig,
1588                             vis: &ast::Visibility)
1589                             -> io::Result<()> {
1590         self.print_fn(&m.decl,
1591                       m.header,
1592                       Some(ident),
1593                       &generics,
1594                       vis)
1595     }
1596
1597     pub fn print_trait_item(&mut self, ti: &ast::TraitItem)
1598                             -> io::Result<()> {
1599         self.ann.pre(self, NodeSubItem(ti.id))?;
1600         self.hardbreak_if_not_bol()?;
1601         self.maybe_print_comment(ti.span.lo())?;
1602         self.print_outer_attributes(&ti.attrs)?;
1603         match ti.node {
1604             ast::TraitItemKind::Const(ref ty, ref default) => {
1605                 self.print_associated_const(
1606                     ti.ident,
1607                     ty,
1608                     default.as_ref().map(|expr| &**expr),
1609                     &source_map::respan(ti.span.shrink_to_lo(), ast::VisibilityKind::Inherited),
1610                 )?;
1611             }
1612             ast::TraitItemKind::Method(ref sig, ref body) => {
1613                 if body.is_some() {
1614                     self.head("")?;
1615                 }
1616                 self.print_method_sig(
1617                     ti.ident,
1618                     &ti.generics,
1619                     sig,
1620                     &source_map::respan(ti.span.shrink_to_lo(), ast::VisibilityKind::Inherited),
1621                 )?;
1622                 if let Some(ref body) = *body {
1623                     self.nbsp()?;
1624                     self.print_block_with_attrs(body, &ti.attrs)?;
1625                 } else {
1626                     self.s.word(";")?;
1627                 }
1628             }
1629             ast::TraitItemKind::Type(ref bounds, ref default) => {
1630                 self.print_associated_type(ti.ident, Some(bounds),
1631                                            default.as_ref().map(|ty| &**ty))?;
1632             }
1633             ast::TraitItemKind::Macro(ref mac) => {
1634                 self.print_mac(mac)?;
1635                 match mac.node.delim {
1636                     MacDelimiter::Brace => {}
1637                     _ => self.s.word(";")?,
1638                 }
1639             }
1640         }
1641         self.ann.post(self, NodeSubItem(ti.id))
1642     }
1643
1644     pub fn print_impl_item(&mut self, ii: &ast::ImplItem) -> io::Result<()> {
1645         self.ann.pre(self, NodeSubItem(ii.id))?;
1646         self.hardbreak_if_not_bol()?;
1647         self.maybe_print_comment(ii.span.lo())?;
1648         self.print_outer_attributes(&ii.attrs)?;
1649         self.print_defaultness(ii.defaultness)?;
1650         match ii.node {
1651             ast::ImplItemKind::Const(ref ty, ref expr) => {
1652                 self.print_associated_const(ii.ident, ty, Some(expr), &ii.vis)?;
1653             }
1654             ast::ImplItemKind::Method(ref sig, ref body) => {
1655                 self.head("")?;
1656                 self.print_method_sig(ii.ident, &ii.generics, sig, &ii.vis)?;
1657                 self.nbsp()?;
1658                 self.print_block_with_attrs(body, &ii.attrs)?;
1659             }
1660             ast::ImplItemKind::Type(ref ty) => {
1661                 self.print_associated_type(ii.ident, None, Some(ty))?;
1662             }
1663             ast::ImplItemKind::Existential(ref bounds) => {
1664                 self.word_space("existential")?;
1665                 self.print_associated_type(ii.ident, Some(bounds), None)?;
1666             }
1667             ast::ImplItemKind::Macro(ref mac) => {
1668                 self.print_mac(mac)?;
1669                 match mac.node.delim {
1670                     MacDelimiter::Brace => {}
1671                     _ => self.s.word(";")?,
1672                 }
1673             }
1674         }
1675         self.ann.post(self, NodeSubItem(ii.id))
1676     }
1677
1678     pub fn print_stmt(&mut self, st: &ast::Stmt) -> io::Result<()> {
1679         self.maybe_print_comment(st.span.lo())?;
1680         match st.node {
1681             ast::StmtKind::Local(ref loc) => {
1682                 self.print_outer_attributes(&loc.attrs)?;
1683                 self.space_if_not_bol()?;
1684                 self.ibox(INDENT_UNIT)?;
1685                 self.word_nbsp("let")?;
1686
1687                 self.ibox(INDENT_UNIT)?;
1688                 self.print_local_decl(loc)?;
1689                 self.end()?;
1690                 if let Some(ref init) = loc.init {
1691                     self.nbsp()?;
1692                     self.word_space("=")?;
1693                     self.print_expr(init)?;
1694                 }
1695                 self.s.word(";")?;
1696                 self.end()?;
1697             }
1698             ast::StmtKind::Item(ref item) => self.print_item(item)?,
1699             ast::StmtKind::Expr(ref expr) => {
1700                 self.space_if_not_bol()?;
1701                 self.print_expr_outer_attr_style(expr, false)?;
1702                 if parse::classify::expr_requires_semi_to_be_stmt(expr) {
1703                     self.s.word(";")?;
1704                 }
1705             }
1706             ast::StmtKind::Semi(ref expr) => {
1707                 self.space_if_not_bol()?;
1708                 self.print_expr_outer_attr_style(expr, false)?;
1709                 self.s.word(";")?;
1710             }
1711             ast::StmtKind::Mac(ref mac) => {
1712                 let (ref mac, style, ref attrs) = **mac;
1713                 self.space_if_not_bol()?;
1714                 self.print_outer_attributes(attrs)?;
1715                 self.print_mac(mac)?;
1716                 if style == ast::MacStmtStyle::Semicolon {
1717                     self.s.word(";")?;
1718                 }
1719             }
1720         }
1721         self.maybe_print_trailing_comment(st.span, None)
1722     }
1723
1724     pub fn print_block(&mut self, blk: &ast::Block) -> io::Result<()> {
1725         self.print_block_with_attrs(blk, &[])
1726     }
1727
1728     pub fn print_block_unclosed(&mut self, blk: &ast::Block) -> io::Result<()> {
1729         self.print_block_unclosed_indent(blk, INDENT_UNIT)
1730     }
1731
1732     pub fn print_block_unclosed_with_attrs(&mut self, blk: &ast::Block,
1733                                             attrs: &[ast::Attribute])
1734                                            -> io::Result<()> {
1735         self.print_block_maybe_unclosed(blk, INDENT_UNIT, attrs, false)
1736     }
1737
1738     pub fn print_block_unclosed_indent(&mut self, blk: &ast::Block,
1739                                        indented: usize) -> io::Result<()> {
1740         self.print_block_maybe_unclosed(blk, indented, &[], false)
1741     }
1742
1743     pub fn print_block_with_attrs(&mut self,
1744                                   blk: &ast::Block,
1745                                   attrs: &[ast::Attribute]) -> io::Result<()> {
1746         self.print_block_maybe_unclosed(blk, INDENT_UNIT, attrs, true)
1747     }
1748
1749     pub fn print_block_maybe_unclosed(&mut self,
1750                                       blk: &ast::Block,
1751                                       indented: usize,
1752                                       attrs: &[ast::Attribute],
1753                                       close_box: bool) -> io::Result<()> {
1754         match blk.rules {
1755             BlockCheckMode::Unsafe(..) => self.word_space("unsafe")?,
1756             BlockCheckMode::Default => ()
1757         }
1758         self.maybe_print_comment(blk.span.lo())?;
1759         self.ann.pre(self, NodeBlock(blk))?;
1760         self.bopen()?;
1761
1762         self.print_inner_attributes(attrs)?;
1763
1764         for (i, st) in blk.stmts.iter().enumerate() {
1765             match st.node {
1766                 ast::StmtKind::Expr(ref expr) if i == blk.stmts.len() - 1 => {
1767                     self.maybe_print_comment(st.span.lo())?;
1768                     self.space_if_not_bol()?;
1769                     self.print_expr_outer_attr_style(expr, false)?;
1770                     self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi()))?;
1771                 }
1772                 _ => self.print_stmt(st)?,
1773             }
1774         }
1775
1776         self.bclose_maybe_open(blk.span, indented, close_box)?;
1777         self.ann.post(self, NodeBlock(blk))
1778     }
1779
1780     fn print_else(&mut self, els: Option<&ast::Expr>) -> io::Result<()> {
1781         match els {
1782             Some(_else) => {
1783                 match _else.node {
1784                     // "another else-if"
1785                     ast::ExprKind::If(ref i, ref then, ref e) => {
1786                         self.cbox(INDENT_UNIT - 1)?;
1787                         self.ibox(0)?;
1788                         self.s.word(" else if ")?;
1789                         self.print_expr_as_cond(i)?;
1790                         self.s.space()?;
1791                         self.print_block(then)?;
1792                         self.print_else(e.as_ref().map(|e| &**e))
1793                     }
1794                     // "another else-if-let"
1795                     ast::ExprKind::IfLet(ref pats, ref expr, ref then, ref e) => {
1796                         self.cbox(INDENT_UNIT - 1)?;
1797                         self.ibox(0)?;
1798                         self.s.word(" else if let ")?;
1799                         self.print_pats(pats)?;
1800                         self.s.space()?;
1801                         self.word_space("=")?;
1802                         self.print_expr_as_cond(expr)?;
1803                         self.s.space()?;
1804                         self.print_block(then)?;
1805                         self.print_else(e.as_ref().map(|e| &**e))
1806                     }
1807                     // "final else"
1808                     ast::ExprKind::Block(ref b, _) => {
1809                         self.cbox(INDENT_UNIT - 1)?;
1810                         self.ibox(0)?;
1811                         self.s.word(" else ")?;
1812                         self.print_block(b)
1813                     }
1814                     // BLEAH, constraints would be great here
1815                     _ => {
1816                         panic!("print_if saw if with weird alternative");
1817                     }
1818                 }
1819             }
1820             _ => Ok(())
1821         }
1822     }
1823
1824     pub fn print_if(&mut self, test: &ast::Expr, blk: &ast::Block,
1825                     elseopt: Option<&ast::Expr>) -> io::Result<()> {
1826         self.head("if")?;
1827         self.print_expr_as_cond(test)?;
1828         self.s.space()?;
1829         self.print_block(blk)?;
1830         self.print_else(elseopt)
1831     }
1832
1833     pub fn print_if_let(&mut self, pats: &[P<ast::Pat>], expr: &ast::Expr, blk: &ast::Block,
1834                         elseopt: Option<&ast::Expr>) -> io::Result<()> {
1835         self.head("if let")?;
1836         self.print_pats(pats)?;
1837         self.s.space()?;
1838         self.word_space("=")?;
1839         self.print_expr_as_cond(expr)?;
1840         self.s.space()?;
1841         self.print_block(blk)?;
1842         self.print_else(elseopt)
1843     }
1844
1845     pub fn print_mac(&mut self, m: &ast::Mac) -> io::Result<()> {
1846         self.print_path(&m.node.path, false, 0)?;
1847         self.s.word("!")?;
1848         match m.node.delim {
1849             MacDelimiter::Parenthesis => self.popen()?,
1850             MacDelimiter::Bracket => self.s.word("[")?,
1851             MacDelimiter::Brace => {
1852                 self.head("")?;
1853                 self.bopen()?;
1854             }
1855         }
1856         self.print_tts(m.node.stream())?;
1857         match m.node.delim {
1858             MacDelimiter::Parenthesis => self.pclose(),
1859             MacDelimiter::Bracket => self.s.word("]"),
1860             MacDelimiter::Brace => self.bclose(m.span),
1861         }
1862     }
1863
1864
1865     fn print_call_post(&mut self, args: &[P<ast::Expr>]) -> io::Result<()> {
1866         self.popen()?;
1867         self.commasep_exprs(Inconsistent, args)?;
1868         self.pclose()
1869     }
1870
1871     pub fn print_expr_maybe_paren(&mut self, expr: &ast::Expr, prec: i8) -> io::Result<()> {
1872         let needs_par = expr.precedence().order() < prec;
1873         if needs_par {
1874             self.popen()?;
1875         }
1876         self.print_expr(expr)?;
1877         if needs_par {
1878             self.pclose()?;
1879         }
1880         Ok(())
1881     }
1882
1883     /// Print an expr using syntax that's acceptable in a condition position, such as the `cond` in
1884     /// `if cond { ... }`.
1885     pub fn print_expr_as_cond(&mut self, expr: &ast::Expr) -> io::Result<()> {
1886         let needs_par = match expr.node {
1887             // These cases need parens due to the parse error observed in #26461: `if return {}`
1888             // parses as the erroneous construct `if (return {})`, not `if (return) {}`.
1889             ast::ExprKind::Closure(..) |
1890             ast::ExprKind::Ret(..) |
1891             ast::ExprKind::Break(..) => true,
1892
1893             _ => parser::contains_exterior_struct_lit(expr),
1894         };
1895
1896         if needs_par {
1897             self.popen()?;
1898         }
1899         self.print_expr(expr)?;
1900         if needs_par {
1901             self.pclose()?;
1902         }
1903         Ok(())
1904     }
1905
1906     fn print_expr_vec(&mut self, exprs: &[P<ast::Expr>],
1907                       attrs: &[Attribute]) -> io::Result<()> {
1908         self.ibox(INDENT_UNIT)?;
1909         self.s.word("[")?;
1910         self.print_inner_attributes_inline(attrs)?;
1911         self.commasep_exprs(Inconsistent, &exprs[..])?;
1912         self.s.word("]")?;
1913         self.end()
1914     }
1915
1916     fn print_expr_repeat(&mut self,
1917                          element: &ast::Expr,
1918                          count: &ast::AnonConst,
1919                          attrs: &[Attribute]) -> io::Result<()> {
1920         self.ibox(INDENT_UNIT)?;
1921         self.s.word("[")?;
1922         self.print_inner_attributes_inline(attrs)?;
1923         self.print_expr(element)?;
1924         self.word_space(";")?;
1925         self.print_expr(&count.value)?;
1926         self.s.word("]")?;
1927         self.end()
1928     }
1929
1930     fn print_expr_struct(&mut self,
1931                          path: &ast::Path,
1932                          fields: &[ast::Field],
1933                          wth: &Option<P<ast::Expr>>,
1934                          attrs: &[Attribute]) -> io::Result<()> {
1935         self.print_path(path, true, 0)?;
1936         self.s.word("{")?;
1937         self.print_inner_attributes_inline(attrs)?;
1938         self.commasep_cmnt(
1939             Consistent,
1940             &fields[..],
1941             |s, field| {
1942                 s.ibox(INDENT_UNIT)?;
1943                 if !field.is_shorthand {
1944                     s.print_ident(field.ident)?;
1945                     s.word_space(":")?;
1946                 }
1947                 s.print_expr(&field.expr)?;
1948                 s.end()
1949             },
1950             |f| f.span)?;
1951         match *wth {
1952             Some(ref expr) => {
1953                 self.ibox(INDENT_UNIT)?;
1954                 if !fields.is_empty() {
1955                     self.s.word(",")?;
1956                     self.s.space()?;
1957                 }
1958                 self.s.word("..")?;
1959                 self.print_expr(expr)?;
1960                 self.end()?;
1961             }
1962             _ => if !fields.is_empty() {
1963                 self.s.word(",")?
1964             }
1965         }
1966         self.s.word("}")?;
1967         Ok(())
1968     }
1969
1970     fn print_expr_tup(&mut self, exprs: &[P<ast::Expr>],
1971                       attrs: &[Attribute]) -> io::Result<()> {
1972         self.popen()?;
1973         self.print_inner_attributes_inline(attrs)?;
1974         self.commasep_exprs(Inconsistent, &exprs[..])?;
1975         if exprs.len() == 1 {
1976             self.s.word(",")?;
1977         }
1978         self.pclose()
1979     }
1980
1981     fn print_expr_call(&mut self,
1982                        func: &ast::Expr,
1983                        args: &[P<ast::Expr>]) -> io::Result<()> {
1984         let prec =
1985             match func.node {
1986                 ast::ExprKind::Field(..) => parser::PREC_FORCE_PAREN,
1987                 _ => parser::PREC_POSTFIX,
1988             };
1989
1990         self.print_expr_maybe_paren(func, prec)?;
1991         self.print_call_post(args)
1992     }
1993
1994     fn print_expr_method_call(&mut self,
1995                               segment: &ast::PathSegment,
1996                               args: &[P<ast::Expr>]) -> io::Result<()> {
1997         let base_args = &args[1..];
1998         self.print_expr_maybe_paren(&args[0], parser::PREC_POSTFIX)?;
1999         self.s.word(".")?;
2000         self.print_ident(segment.ident)?;
2001         if let Some(ref args) = segment.args {
2002             self.print_generic_args(args, true)?;
2003         }
2004         self.print_call_post(base_args)
2005     }
2006
2007     fn print_expr_binary(&mut self,
2008                          op: ast::BinOp,
2009                          lhs: &ast::Expr,
2010                          rhs: &ast::Expr) -> io::Result<()> {
2011         let assoc_op = AssocOp::from_ast_binop(op.node);
2012         let prec = assoc_op.precedence() as i8;
2013         let fixity = assoc_op.fixity();
2014
2015         let (left_prec, right_prec) = match fixity {
2016             Fixity::Left => (prec, prec + 1),
2017             Fixity::Right => (prec + 1, prec),
2018             Fixity::None => (prec + 1, prec + 1),
2019         };
2020
2021         let left_prec = match (&lhs.node, op.node) {
2022             // These cases need parens: `x as i32 < y` has the parser thinking that `i32 < y` is
2023             // the beginning of a path type. It starts trying to parse `x as (i32 < y ...` instead
2024             // of `(x as i32) < ...`. We need to convince it _not_ to do that.
2025             (&ast::ExprKind::Cast { .. }, ast::BinOpKind::Lt) |
2026             (&ast::ExprKind::Cast { .. }, ast::BinOpKind::Shl) => parser::PREC_FORCE_PAREN,
2027             _ => left_prec,
2028         };
2029
2030         self.print_expr_maybe_paren(lhs, left_prec)?;
2031         self.s.space()?;
2032         self.word_space(op.node.to_string())?;
2033         self.print_expr_maybe_paren(rhs, right_prec)
2034     }
2035
2036     fn print_expr_unary(&mut self,
2037                         op: ast::UnOp,
2038                         expr: &ast::Expr) -> io::Result<()> {
2039         self.s.word(ast::UnOp::to_string(op))?;
2040         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
2041     }
2042
2043     fn print_expr_addr_of(&mut self,
2044                           mutability: ast::Mutability,
2045                           expr: &ast::Expr) -> io::Result<()> {
2046         self.s.word("&")?;
2047         self.print_mutability(mutability)?;
2048         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
2049     }
2050
2051     pub fn print_expr(&mut self, expr: &ast::Expr) -> io::Result<()> {
2052         self.print_expr_outer_attr_style(expr, true)
2053     }
2054
2055     fn print_expr_outer_attr_style(&mut self,
2056                                   expr: &ast::Expr,
2057                                   is_inline: bool) -> io::Result<()> {
2058         self.maybe_print_comment(expr.span.lo())?;
2059
2060         let attrs = &expr.attrs;
2061         if is_inline {
2062             self.print_outer_attributes_inline(attrs)?;
2063         } else {
2064             self.print_outer_attributes(attrs)?;
2065         }
2066
2067         self.ibox(INDENT_UNIT)?;
2068         self.ann.pre(self, NodeExpr(expr))?;
2069         match expr.node {
2070             ast::ExprKind::Box(ref expr) => {
2071                 self.word_space("box")?;
2072                 self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)?;
2073             }
2074             ast::ExprKind::ObsoleteInPlace(ref place, ref expr) => {
2075                 let prec = AssocOp::ObsoleteInPlace.precedence() as i8;
2076                 self.print_expr_maybe_paren(place, prec + 1)?;
2077                 self.s.space()?;
2078                 self.word_space("<-")?;
2079                 self.print_expr_maybe_paren(expr, prec)?;
2080             }
2081             ast::ExprKind::Array(ref exprs) => {
2082                 self.print_expr_vec(&exprs[..], attrs)?;
2083             }
2084             ast::ExprKind::Repeat(ref element, ref count) => {
2085                 self.print_expr_repeat(element, count, attrs)?;
2086             }
2087             ast::ExprKind::Struct(ref path, ref fields, ref wth) => {
2088                 self.print_expr_struct(path, &fields[..], wth, attrs)?;
2089             }
2090             ast::ExprKind::Tup(ref exprs) => {
2091                 self.print_expr_tup(&exprs[..], attrs)?;
2092             }
2093             ast::ExprKind::Call(ref func, ref args) => {
2094                 self.print_expr_call(func, &args[..])?;
2095             }
2096             ast::ExprKind::MethodCall(ref segment, ref args) => {
2097                 self.print_expr_method_call(segment, &args[..])?;
2098             }
2099             ast::ExprKind::Binary(op, ref lhs, ref rhs) => {
2100                 self.print_expr_binary(op, lhs, rhs)?;
2101             }
2102             ast::ExprKind::Unary(op, ref expr) => {
2103                 self.print_expr_unary(op, expr)?;
2104             }
2105             ast::ExprKind::AddrOf(m, ref expr) => {
2106                 self.print_expr_addr_of(m, expr)?;
2107             }
2108             ast::ExprKind::Lit(ref lit) => {
2109                 self.print_literal(lit)?;
2110             }
2111             ast::ExprKind::Cast(ref expr, ref ty) => {
2112                 let prec = AssocOp::As.precedence() as i8;
2113                 self.print_expr_maybe_paren(expr, prec)?;
2114                 self.s.space()?;
2115                 self.word_space("as")?;
2116                 self.print_type(ty)?;
2117             }
2118             ast::ExprKind::Type(ref expr, ref ty) => {
2119                 let prec = AssocOp::Colon.precedence() as i8;
2120                 self.print_expr_maybe_paren(expr, prec)?;
2121                 self.word_space(":")?;
2122                 self.print_type(ty)?;
2123             }
2124             ast::ExprKind::If(ref test, ref blk, ref elseopt) => {
2125                 self.print_if(test, blk, elseopt.as_ref().map(|e| &**e))?;
2126             }
2127             ast::ExprKind::IfLet(ref pats, ref expr, ref blk, ref elseopt) => {
2128                 self.print_if_let(pats, expr, blk, elseopt.as_ref().map(|e| &**e))?;
2129             }
2130             ast::ExprKind::While(ref test, ref blk, opt_label) => {
2131                 if let Some(label) = opt_label {
2132                     self.print_ident(label.ident)?;
2133                     self.word_space(":")?;
2134                 }
2135                 self.head("while")?;
2136                 self.print_expr_as_cond(test)?;
2137                 self.s.space()?;
2138                 self.print_block_with_attrs(blk, attrs)?;
2139             }
2140             ast::ExprKind::WhileLet(ref pats, ref expr, ref blk, opt_label) => {
2141                 if let Some(label) = opt_label {
2142                     self.print_ident(label.ident)?;
2143                     self.word_space(":")?;
2144                 }
2145                 self.head("while let")?;
2146                 self.print_pats(pats)?;
2147                 self.s.space()?;
2148                 self.word_space("=")?;
2149                 self.print_expr_as_cond(expr)?;
2150                 self.s.space()?;
2151                 self.print_block_with_attrs(blk, attrs)?;
2152             }
2153             ast::ExprKind::ForLoop(ref pat, ref iter, ref blk, opt_label) => {
2154                 if let Some(label) = opt_label {
2155                     self.print_ident(label.ident)?;
2156                     self.word_space(":")?;
2157                 }
2158                 self.head("for")?;
2159                 self.print_pat(pat)?;
2160                 self.s.space()?;
2161                 self.word_space("in")?;
2162                 self.print_expr_as_cond(iter)?;
2163                 self.s.space()?;
2164                 self.print_block_with_attrs(blk, attrs)?;
2165             }
2166             ast::ExprKind::Loop(ref blk, opt_label) => {
2167                 if let Some(label) = opt_label {
2168                     self.print_ident(label.ident)?;
2169                     self.word_space(":")?;
2170                 }
2171                 self.head("loop")?;
2172                 self.s.space()?;
2173                 self.print_block_with_attrs(blk, attrs)?;
2174             }
2175             ast::ExprKind::Match(ref expr, ref arms) => {
2176                 self.cbox(INDENT_UNIT)?;
2177                 self.ibox(4)?;
2178                 self.word_nbsp("match")?;
2179                 self.print_expr_as_cond(expr)?;
2180                 self.s.space()?;
2181                 self.bopen()?;
2182                 self.print_inner_attributes_no_trailing_hardbreak(attrs)?;
2183                 for arm in arms {
2184                     self.print_arm(arm)?;
2185                 }
2186                 self.bclose_(expr.span, INDENT_UNIT)?;
2187             }
2188             ast::ExprKind::Closure(
2189                 capture_clause, asyncness, movability, ref decl, ref body, _) => {
2190                 self.print_movability(movability)?;
2191                 self.print_asyncness(asyncness)?;
2192                 self.print_capture_clause(capture_clause)?;
2193
2194                 self.print_fn_block_args(decl)?;
2195                 self.s.space()?;
2196                 self.print_expr(body)?;
2197                 self.end()?; // need to close a box
2198
2199                 // a box will be closed by print_expr, but we didn't want an overall
2200                 // wrapper so we closed the corresponding opening. so create an
2201                 // empty box to satisfy the close.
2202                 self.ibox(0)?;
2203             }
2204             ast::ExprKind::Block(ref blk, opt_label) => {
2205                 if let Some(label) = opt_label {
2206                     self.print_ident(label.ident)?;
2207                     self.word_space(":")?;
2208                 }
2209                 // containing cbox, will be closed by print-block at }
2210                 self.cbox(INDENT_UNIT)?;
2211                 // head-box, will be closed by print-block after {
2212                 self.ibox(0)?;
2213                 self.print_block_with_attrs(blk, attrs)?;
2214             }
2215             ast::ExprKind::Async(capture_clause, _, ref blk) => {
2216                 self.word_nbsp("async")?;
2217                 self.print_capture_clause(capture_clause)?;
2218                 self.s.space()?;
2219                 self.print_block_with_attrs(blk, attrs)?;
2220             }
2221             ast::ExprKind::Assign(ref lhs, ref rhs) => {
2222                 let prec = AssocOp::Assign.precedence() as i8;
2223                 self.print_expr_maybe_paren(lhs, prec + 1)?;
2224                 self.s.space()?;
2225                 self.word_space("=")?;
2226                 self.print_expr_maybe_paren(rhs, prec)?;
2227             }
2228             ast::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
2229                 let prec = AssocOp::Assign.precedence() as i8;
2230                 self.print_expr_maybe_paren(lhs, prec + 1)?;
2231                 self.s.space()?;
2232                 self.s.word(op.node.to_string())?;
2233                 self.word_space("=")?;
2234                 self.print_expr_maybe_paren(rhs, prec)?;
2235             }
2236             ast::ExprKind::Field(ref expr, ident) => {
2237                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX)?;
2238                 self.s.word(".")?;
2239                 self.print_ident(ident)?;
2240             }
2241             ast::ExprKind::Index(ref expr, ref index) => {
2242                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX)?;
2243                 self.s.word("[")?;
2244                 self.print_expr(index)?;
2245                 self.s.word("]")?;
2246             }
2247             ast::ExprKind::Range(ref start, ref end, limits) => {
2248                 // Special case for `Range`.  `AssocOp` claims that `Range` has higher precedence
2249                 // than `Assign`, but `x .. x = x` gives a parse error instead of `x .. (x = x)`.
2250                 // Here we use a fake precedence value so that any child with lower precedence than
2251                 // a "normal" binop gets parenthesized.  (`LOr` is the lowest-precedence binop.)
2252                 let fake_prec = AssocOp::LOr.precedence() as i8;
2253                 if let Some(ref e) = *start {
2254                     self.print_expr_maybe_paren(e, fake_prec)?;
2255                 }
2256                 if limits == ast::RangeLimits::HalfOpen {
2257                     self.s.word("..")?;
2258                 } else {
2259                     self.s.word("..=")?;
2260                 }
2261                 if let Some(ref e) = *end {
2262                     self.print_expr_maybe_paren(e, fake_prec)?;
2263                 }
2264             }
2265             ast::ExprKind::Path(None, ref path) => {
2266                 self.print_path(path, true, 0)?
2267             }
2268             ast::ExprKind::Path(Some(ref qself), ref path) => {
2269                 self.print_qpath(path, qself, true)?
2270             }
2271             ast::ExprKind::Break(opt_label, ref opt_expr) => {
2272                 self.s.word("break")?;
2273                 self.s.space()?;
2274                 if let Some(label) = opt_label {
2275                     self.print_ident(label.ident)?;
2276                     self.s.space()?;
2277                 }
2278                 if let Some(ref expr) = *opt_expr {
2279                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP)?;
2280                     self.s.space()?;
2281                 }
2282             }
2283             ast::ExprKind::Continue(opt_label) => {
2284                 self.s.word("continue")?;
2285                 self.s.space()?;
2286                 if let Some(label) = opt_label {
2287                     self.print_ident(label.ident)?;
2288                     self.s.space()?
2289                 }
2290             }
2291             ast::ExprKind::Ret(ref result) => {
2292                 self.s.word("return")?;
2293                 if let Some(ref expr) = *result {
2294                     self.s.word(" ")?;
2295                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP)?;
2296                 }
2297             }
2298             ast::ExprKind::InlineAsm(ref a) => {
2299                 self.s.word("asm!")?;
2300                 self.popen()?;
2301                 self.print_string(&a.asm.as_str(), a.asm_str_style)?;
2302                 self.word_space(":")?;
2303
2304                 self.commasep(Inconsistent, &a.outputs, |s, out| {
2305                     let constraint = out.constraint.as_str();
2306                     let mut ch = constraint.chars();
2307                     match ch.next() {
2308                         Some('=') if out.is_rw => {
2309                             s.print_string(&format!("+{}", ch.as_str()),
2310                                            ast::StrStyle::Cooked)?
2311                         }
2312                         _ => s.print_string(&constraint, ast::StrStyle::Cooked)?
2313                     }
2314                     s.popen()?;
2315                     s.print_expr(&out.expr)?;
2316                     s.pclose()?;
2317                     Ok(())
2318                 })?;
2319                 self.s.space()?;
2320                 self.word_space(":")?;
2321
2322                 self.commasep(Inconsistent, &a.inputs, |s, &(co, ref o)| {
2323                     s.print_string(&co.as_str(), ast::StrStyle::Cooked)?;
2324                     s.popen()?;
2325                     s.print_expr(o)?;
2326                     s.pclose()?;
2327                     Ok(())
2328                 })?;
2329                 self.s.space()?;
2330                 self.word_space(":")?;
2331
2332                 self.commasep(Inconsistent, &a.clobbers,
2333                                    |s, co| {
2334                     s.print_string(&co.as_str(), ast::StrStyle::Cooked)?;
2335                     Ok(())
2336                 })?;
2337
2338                 let mut options = vec![];
2339                 if a.volatile {
2340                     options.push("volatile");
2341                 }
2342                 if a.alignstack {
2343                     options.push("alignstack");
2344                 }
2345                 if a.dialect == ast::AsmDialect::Intel {
2346                     options.push("intel");
2347                 }
2348
2349                 if !options.is_empty() {
2350                     self.s.space()?;
2351                     self.word_space(":")?;
2352                     self.commasep(Inconsistent, &options,
2353                                   |s, &co| {
2354                                       s.print_string(co, ast::StrStyle::Cooked)?;
2355                                       Ok(())
2356                                   })?;
2357                 }
2358
2359                 self.pclose()?;
2360             }
2361             ast::ExprKind::Mac(ref m) => self.print_mac(m)?,
2362             ast::ExprKind::Paren(ref e) => {
2363                 self.popen()?;
2364                 self.print_inner_attributes_inline(attrs)?;
2365                 self.print_expr(e)?;
2366                 self.pclose()?;
2367             },
2368             ast::ExprKind::Yield(ref e) => {
2369                 self.s.word("yield")?;
2370                 match *e {
2371                     Some(ref expr) => {
2372                         self.s.space()?;
2373                         self.print_expr_maybe_paren(expr, parser::PREC_JUMP)?;
2374                     }
2375                     _ => ()
2376                 }
2377             }
2378             ast::ExprKind::Try(ref e) => {
2379                 self.print_expr_maybe_paren(e, parser::PREC_POSTFIX)?;
2380                 self.s.word("?")?
2381             }
2382             ast::ExprKind::TryBlock(ref blk) => {
2383                 self.head("try")?;
2384                 self.s.space()?;
2385                 self.print_block_with_attrs(blk, attrs)?
2386             }
2387         }
2388         self.ann.post(self, NodeExpr(expr))?;
2389         self.end()
2390     }
2391
2392     pub fn print_local_decl(&mut self, loc: &ast::Local) -> io::Result<()> {
2393         self.print_pat(&loc.pat)?;
2394         if let Some(ref ty) = loc.ty {
2395             self.word_space(":")?;
2396             self.print_type(ty)?;
2397         }
2398         Ok(())
2399     }
2400
2401     pub fn print_ident(&mut self, ident: ast::Ident) -> io::Result<()> {
2402         if ident.is_raw_guess() {
2403             self.s.word(&format!("r#{}", ident))?;
2404         } else {
2405             self.s.word(&ident.as_str())?;
2406         }
2407         self.ann.post(self, NodeIdent(&ident))
2408     }
2409
2410     pub fn print_usize(&mut self, i: usize) -> io::Result<()> {
2411         self.s.word(&i.to_string())
2412     }
2413
2414     pub fn print_name(&mut self, name: ast::Name) -> io::Result<()> {
2415         self.s.word(&name.as_str())?;
2416         self.ann.post(self, NodeName(&name))
2417     }
2418
2419     pub fn print_for_decl(&mut self, loc: &ast::Local,
2420                           coll: &ast::Expr) -> io::Result<()> {
2421         self.print_local_decl(loc)?;
2422         self.s.space()?;
2423         self.word_space("in")?;
2424         self.print_expr(coll)
2425     }
2426
2427     fn print_path(&mut self,
2428                   path: &ast::Path,
2429                   colons_before_params: bool,
2430                   depth: usize)
2431                   -> io::Result<()>
2432     {
2433         self.maybe_print_comment(path.span.lo())?;
2434
2435         for (i, segment) in path.segments[..path.segments.len() - depth].iter().enumerate() {
2436             if i > 0 {
2437                 self.s.word("::")?
2438             }
2439             self.print_path_segment(segment, colons_before_params)?;
2440         }
2441
2442         Ok(())
2443     }
2444
2445     fn print_path_segment(&mut self,
2446                           segment: &ast::PathSegment,
2447                           colons_before_params: bool)
2448                           -> io::Result<()>
2449     {
2450         if segment.ident.name != keywords::CrateRoot.name() &&
2451            segment.ident.name != keywords::DollarCrate.name() {
2452             self.print_ident(segment.ident)?;
2453             if let Some(ref args) = segment.args {
2454                 self.print_generic_args(args, colons_before_params)?;
2455             }
2456         } else if segment.ident.name == keywords::DollarCrate.name() {
2457             self.print_dollar_crate(segment.ident.span.ctxt())?;
2458         }
2459         Ok(())
2460     }
2461
2462     fn print_qpath(&mut self,
2463                    path: &ast::Path,
2464                    qself: &ast::QSelf,
2465                    colons_before_params: bool)
2466                    -> io::Result<()>
2467     {
2468         self.s.word("<")?;
2469         self.print_type(&qself.ty)?;
2470         if qself.position > 0 {
2471             self.s.space()?;
2472             self.word_space("as")?;
2473             let depth = path.segments.len() - qself.position;
2474             self.print_path(path, false, depth)?;
2475         }
2476         self.s.word(">")?;
2477         self.s.word("::")?;
2478         let item_segment = path.segments.last().unwrap();
2479         self.print_ident(item_segment.ident)?;
2480         match item_segment.args {
2481             Some(ref args) => self.print_generic_args(args, colons_before_params),
2482             None => Ok(()),
2483         }
2484     }
2485
2486     fn print_generic_args(&mut self,
2487                           args: &ast::GenericArgs,
2488                           colons_before_params: bool)
2489                           -> io::Result<()>
2490     {
2491         if colons_before_params {
2492             self.s.word("::")?
2493         }
2494
2495         match *args {
2496             ast::GenericArgs::AngleBracketed(ref data) => {
2497                 self.s.word("<")?;
2498
2499                 self.commasep(Inconsistent, &data.args, |s, generic_arg| {
2500                     s.print_generic_arg(generic_arg)
2501                 })?;
2502
2503                 let mut comma = data.args.len() != 0;
2504
2505                 for binding in data.bindings.iter() {
2506                     if comma {
2507                         self.word_space(",")?
2508                     }
2509                     self.print_ident(binding.ident)?;
2510                     self.s.space()?;
2511                     self.word_space("=")?;
2512                     self.print_type(&binding.ty)?;
2513                     comma = true;
2514                 }
2515
2516                 self.s.word(">")?
2517             }
2518
2519             ast::GenericArgs::Parenthesized(ref data) => {
2520                 self.s.word("(")?;
2521                 self.commasep(
2522                     Inconsistent,
2523                     &data.inputs,
2524                     |s, ty| s.print_type(ty))?;
2525                 self.s.word(")")?;
2526
2527                 if let Some(ref ty) = data.output {
2528                     self.space_if_not_bol()?;
2529                     self.word_space("->")?;
2530                     self.print_type(ty)?;
2531                 }
2532             }
2533         }
2534
2535         Ok(())
2536     }
2537
2538     pub fn print_pat(&mut self, pat: &ast::Pat) -> io::Result<()> {
2539         self.maybe_print_comment(pat.span.lo())?;
2540         self.ann.pre(self, NodePat(pat))?;
2541         /* Pat isn't normalized, but the beauty of it
2542          is that it doesn't matter */
2543         match pat.node {
2544             PatKind::Wild => self.s.word("_")?,
2545             PatKind::Ident(binding_mode, ident, ref sub) => {
2546                 match binding_mode {
2547                     ast::BindingMode::ByRef(mutbl) => {
2548                         self.word_nbsp("ref")?;
2549                         self.print_mutability(mutbl)?;
2550                     }
2551                     ast::BindingMode::ByValue(ast::Mutability::Immutable) => {}
2552                     ast::BindingMode::ByValue(ast::Mutability::Mutable) => {
2553                         self.word_nbsp("mut")?;
2554                     }
2555                 }
2556                 self.print_ident(ident)?;
2557                 if let Some(ref p) = *sub {
2558                     self.s.word("@")?;
2559                     self.print_pat(p)?;
2560                 }
2561             }
2562             PatKind::TupleStruct(ref path, ref elts, ddpos) => {
2563                 self.print_path(path, true, 0)?;
2564                 self.popen()?;
2565                 if let Some(ddpos) = ddpos {
2566                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(p))?;
2567                     if ddpos != 0 {
2568                         self.word_space(",")?;
2569                     }
2570                     self.s.word("..")?;
2571                     if ddpos != elts.len() {
2572                         self.s.word(",")?;
2573                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(p))?;
2574                     }
2575                 } else {
2576                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(p))?;
2577                 }
2578                 self.pclose()?;
2579             }
2580             PatKind::Path(None, ref path) => {
2581                 self.print_path(path, true, 0)?;
2582             }
2583             PatKind::Path(Some(ref qself), ref path) => {
2584                 self.print_qpath(path, qself, false)?;
2585             }
2586             PatKind::Struct(ref path, ref fields, etc) => {
2587                 self.print_path(path, true, 0)?;
2588                 self.nbsp()?;
2589                 self.word_space("{")?;
2590                 self.commasep_cmnt(
2591                     Consistent, &fields[..],
2592                     |s, f| {
2593                         s.cbox(INDENT_UNIT)?;
2594                         if !f.node.is_shorthand {
2595                             s.print_ident(f.node.ident)?;
2596                             s.word_nbsp(":")?;
2597                         }
2598                         s.print_pat(&f.node.pat)?;
2599                         s.end()
2600                     },
2601                     |f| f.node.pat.span)?;
2602                 if etc {
2603                     if !fields.is_empty() { self.word_space(",")?; }
2604                     self.s.word("..")?;
2605                 }
2606                 self.s.space()?;
2607                 self.s.word("}")?;
2608             }
2609             PatKind::Tuple(ref elts, ddpos) => {
2610                 self.popen()?;
2611                 if let Some(ddpos) = ddpos {
2612                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(p))?;
2613                     if ddpos != 0 {
2614                         self.word_space(",")?;
2615                     }
2616                     self.s.word("..")?;
2617                     if ddpos != elts.len() {
2618                         self.s.word(",")?;
2619                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(p))?;
2620                     }
2621                 } else {
2622                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(p))?;
2623                     if elts.len() == 1 {
2624                         self.s.word(",")?;
2625                     }
2626                 }
2627                 self.pclose()?;
2628             }
2629             PatKind::Box(ref inner) => {
2630                 self.s.word("box ")?;
2631                 self.print_pat(inner)?;
2632             }
2633             PatKind::Ref(ref inner, mutbl) => {
2634                 self.s.word("&")?;
2635                 if mutbl == ast::Mutability::Mutable {
2636                     self.s.word("mut ")?;
2637                 }
2638                 self.print_pat(inner)?;
2639             }
2640             PatKind::Lit(ref e) => self.print_expr(&**e)?,
2641             PatKind::Range(ref begin, ref end, Spanned { node: ref end_kind, .. }) => {
2642                 self.print_expr(begin)?;
2643                 self.s.space()?;
2644                 match *end_kind {
2645                     RangeEnd::Included(RangeSyntax::DotDotDot) => self.s.word("...")?,
2646                     RangeEnd::Included(RangeSyntax::DotDotEq) => self.s.word("..=")?,
2647                     RangeEnd::Excluded => self.s.word("..")?,
2648                 }
2649                 self.print_expr(end)?;
2650             }
2651             PatKind::Slice(ref before, ref slice, ref after) => {
2652                 self.s.word("[")?;
2653                 self.commasep(Inconsistent,
2654                                    &before[..],
2655                                    |s, p| s.print_pat(p))?;
2656                 if let Some(ref p) = *slice {
2657                     if !before.is_empty() { self.word_space(",")?; }
2658                     if let PatKind::Wild = p.node {
2659                         // Print nothing
2660                     } else {
2661                         self.print_pat(p)?;
2662                     }
2663                     self.s.word("..")?;
2664                     if !after.is_empty() { self.word_space(",")?; }
2665                 }
2666                 self.commasep(Inconsistent,
2667                                    &after[..],
2668                                    |s, p| s.print_pat(p))?;
2669                 self.s.word("]")?;
2670             }
2671             PatKind::Paren(ref inner) => {
2672                 self.popen()?;
2673                 self.print_pat(inner)?;
2674                 self.pclose()?;
2675             }
2676             PatKind::Mac(ref m) => self.print_mac(m)?,
2677         }
2678         self.ann.post(self, NodePat(pat))
2679     }
2680
2681     fn print_pats(&mut self, pats: &[P<ast::Pat>]) -> io::Result<()> {
2682         let mut first = true;
2683         for p in pats {
2684             if first {
2685                 first = false;
2686             } else {
2687                 self.s.space()?;
2688                 self.word_space("|")?;
2689             }
2690             self.print_pat(p)?;
2691         }
2692         Ok(())
2693     }
2694
2695     fn print_arm(&mut self, arm: &ast::Arm) -> io::Result<()> {
2696         // I have no idea why this check is necessary, but here it
2697         // is :(
2698         if arm.attrs.is_empty() {
2699             self.s.space()?;
2700         }
2701         self.cbox(INDENT_UNIT)?;
2702         self.ibox(0)?;
2703         self.maybe_print_comment(arm.pats[0].span.lo())?;
2704         self.print_outer_attributes(&arm.attrs)?;
2705         self.print_pats(&arm.pats)?;
2706         self.s.space()?;
2707         if let Some(ref e) = arm.guard {
2708             self.word_space("if")?;
2709             self.print_expr(e)?;
2710             self.s.space()?;
2711         }
2712         self.word_space("=>")?;
2713
2714         match arm.body.node {
2715             ast::ExprKind::Block(ref blk, opt_label) => {
2716                 if let Some(label) = opt_label {
2717                     self.print_ident(label.ident)?;
2718                     self.word_space(":")?;
2719                 }
2720
2721                 // the block will close the pattern's ibox
2722                 self.print_block_unclosed_indent(blk, INDENT_UNIT)?;
2723
2724                 // If it is a user-provided unsafe block, print a comma after it
2725                 if let BlockCheckMode::Unsafe(ast::UserProvided) = blk.rules {
2726                     self.s.word(",")?;
2727                 }
2728             }
2729             _ => {
2730                 self.end()?; // close the ibox for the pattern
2731                 self.print_expr(&arm.body)?;
2732                 self.s.word(",")?;
2733             }
2734         }
2735         self.end() // close enclosing cbox
2736     }
2737
2738     fn print_explicit_self(&mut self, explicit_self: &ast::ExplicitSelf) -> io::Result<()> {
2739         match explicit_self.node {
2740             SelfKind::Value(m) => {
2741                 self.print_mutability(m)?;
2742                 self.s.word("self")
2743             }
2744             SelfKind::Region(ref lt, m) => {
2745                 self.s.word("&")?;
2746                 self.print_opt_lifetime(lt)?;
2747                 self.print_mutability(m)?;
2748                 self.s.word("self")
2749             }
2750             SelfKind::Explicit(ref typ, m) => {
2751                 self.print_mutability(m)?;
2752                 self.s.word("self")?;
2753                 self.word_space(":")?;
2754                 self.print_type(typ)
2755             }
2756         }
2757     }
2758
2759     pub fn print_fn(&mut self,
2760                     decl: &ast::FnDecl,
2761                     header: ast::FnHeader,
2762                     name: Option<ast::Ident>,
2763                     generics: &ast::Generics,
2764                     vis: &ast::Visibility) -> io::Result<()> {
2765         self.print_fn_header_info(header, vis)?;
2766
2767         if let Some(name) = name {
2768             self.nbsp()?;
2769             self.print_ident(name)?;
2770         }
2771         self.print_generic_params(&generics.params)?;
2772         self.print_fn_args_and_ret(decl)?;
2773         self.print_where_clause(&generics.where_clause)
2774     }
2775
2776     pub fn print_fn_args_and_ret(&mut self, decl: &ast::FnDecl)
2777         -> io::Result<()> {
2778         self.popen()?;
2779         self.commasep(Inconsistent, &decl.inputs, |s, arg| s.print_arg(arg, false))?;
2780         if decl.variadic {
2781             self.s.word(", ...")?;
2782         }
2783         self.pclose()?;
2784
2785         self.print_fn_output(decl)
2786     }
2787
2788     pub fn print_fn_block_args(
2789             &mut self,
2790             decl: &ast::FnDecl)
2791             -> io::Result<()> {
2792         self.s.word("|")?;
2793         self.commasep(Inconsistent, &decl.inputs, |s, arg| s.print_arg(arg, true))?;
2794         self.s.word("|")?;
2795
2796         if let ast::FunctionRetTy::Default(..) = decl.output {
2797             return Ok(());
2798         }
2799
2800         self.space_if_not_bol()?;
2801         self.word_space("->")?;
2802         match decl.output {
2803             ast::FunctionRetTy::Ty(ref ty) => {
2804                 self.print_type(ty)?;
2805                 self.maybe_print_comment(ty.span.lo())
2806             }
2807             ast::FunctionRetTy::Default(..) => unreachable!(),
2808         }
2809     }
2810
2811     pub fn print_movability(&mut self, movability: ast::Movability)
2812                                 -> io::Result<()> {
2813         match movability {
2814             ast::Movability::Static => self.word_space("static"),
2815             ast::Movability::Movable => Ok(()),
2816         }
2817     }
2818
2819     pub fn print_asyncness(&mut self, asyncness: ast::IsAsync)
2820                                 -> io::Result<()> {
2821         if asyncness.is_async() {
2822             self.word_nbsp("async")?;
2823         }
2824         Ok(())
2825     }
2826
2827     pub fn print_capture_clause(&mut self, capture_clause: ast::CaptureBy)
2828                                 -> io::Result<()> {
2829         match capture_clause {
2830             ast::CaptureBy::Value => self.word_space("move"),
2831             ast::CaptureBy::Ref => Ok(()),
2832         }
2833     }
2834
2835     pub fn print_type_bounds(&mut self,
2836                         prefix: &str,
2837                         bounds: &[ast::GenericBound])
2838                         -> io::Result<()> {
2839         if !bounds.is_empty() {
2840             self.s.word(prefix)?;
2841             let mut first = true;
2842             for bound in bounds {
2843                 if !(first && prefix.is_empty()) {
2844                     self.nbsp()?;
2845                 }
2846                 if first {
2847                     first = false;
2848                 } else {
2849                     self.word_space("+")?;
2850                 }
2851
2852                 match bound {
2853                     GenericBound::Trait(tref, modifier) => {
2854                         if modifier == &TraitBoundModifier::Maybe {
2855                             self.s.word("?")?;
2856                         }
2857                         self.print_poly_trait_ref(tref)?;
2858                     }
2859                     GenericBound::Outlives(lt) => self.print_lifetime(*lt)?,
2860                 }
2861             }
2862         }
2863         Ok(())
2864     }
2865
2866     pub fn print_lifetime(&mut self, lifetime: ast::Lifetime) -> io::Result<()> {
2867         self.print_name(lifetime.ident.name)
2868     }
2869
2870     pub fn print_lifetime_bounds(&mut self, lifetime: ast::Lifetime, bounds: &ast::GenericBounds)
2871         -> io::Result<()>
2872     {
2873         self.print_lifetime(lifetime)?;
2874         if !bounds.is_empty() {
2875             self.s.word(": ")?;
2876             for (i, bound) in bounds.iter().enumerate() {
2877                 if i != 0 {
2878                     self.s.word(" + ")?;
2879                 }
2880                 match bound {
2881                     ast::GenericBound::Outlives(lt) => self.print_lifetime(*lt)?,
2882                     _ => panic!(),
2883                 }
2884             }
2885         }
2886         Ok(())
2887     }
2888
2889     pub fn print_generic_params(
2890         &mut self,
2891         generic_params: &[ast::GenericParam]
2892     ) -> io::Result<()> {
2893         if generic_params.is_empty() {
2894             return Ok(());
2895         }
2896
2897         self.s.word("<")?;
2898
2899         self.commasep(Inconsistent, &generic_params, |s, param| {
2900             match param.kind {
2901                 ast::GenericParamKind::Lifetime => {
2902                     s.print_outer_attributes_inline(&param.attrs)?;
2903                     let lt = ast::Lifetime { id: param.id, ident: param.ident };
2904                     s.print_lifetime_bounds(lt, &param.bounds)
2905                 },
2906                 ast::GenericParamKind::Type { ref default } => {
2907                     s.print_outer_attributes_inline(&param.attrs)?;
2908                     s.print_ident(param.ident)?;
2909                     s.print_type_bounds(":", &param.bounds)?;
2910                     match default {
2911                         Some(ref default) => {
2912                             s.s.space()?;
2913                             s.word_space("=")?;
2914                             s.print_type(default)
2915                         }
2916                         _ => Ok(())
2917                     }
2918                 }
2919             }
2920         })?;
2921
2922         self.s.word(">")?;
2923         Ok(())
2924     }
2925
2926     pub fn print_where_clause(&mut self, where_clause: &ast::WhereClause)
2927                               -> io::Result<()> {
2928         if where_clause.predicates.is_empty() {
2929             return Ok(())
2930         }
2931
2932         self.s.space()?;
2933         self.word_space("where")?;
2934
2935         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2936             if i != 0 {
2937                 self.word_space(",")?;
2938             }
2939
2940             match *predicate {
2941                 ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
2942                     ref bound_generic_params,
2943                     ref bounded_ty,
2944                     ref bounds,
2945                     ..
2946                 }) => {
2947                     self.print_formal_generic_params(bound_generic_params)?;
2948                     self.print_type(bounded_ty)?;
2949                     self.print_type_bounds(":", bounds)?;
2950                 }
2951                 ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate{ref lifetime,
2952                                                                                ref bounds,
2953                                                                                ..}) => {
2954                     self.print_lifetime_bounds(*lifetime, bounds)?;
2955                 }
2956                 ast::WherePredicate::EqPredicate(ast::WhereEqPredicate{ref lhs_ty,
2957                                                                        ref rhs_ty,
2958                                                                        ..}) => {
2959                     self.print_type(lhs_ty)?;
2960                     self.s.space()?;
2961                     self.word_space("=")?;
2962                     self.print_type(rhs_ty)?;
2963                 }
2964             }
2965         }
2966
2967         Ok(())
2968     }
2969
2970     pub fn print_use_tree(&mut self, tree: &ast::UseTree) -> io::Result<()> {
2971         match tree.kind {
2972             ast::UseTreeKind::Simple(rename, ..) => {
2973                 self.print_path(&tree.prefix, false, 0)?;
2974                 if let Some(rename) = rename {
2975                     self.s.space()?;
2976                     self.word_space("as")?;
2977                     self.print_ident(rename)?;
2978                 }
2979             }
2980             ast::UseTreeKind::Glob => {
2981                 if !tree.prefix.segments.is_empty() {
2982                     self.print_path(&tree.prefix, false, 0)?;
2983                     self.s.word("::")?;
2984                 }
2985                 self.s.word("*")?;
2986             }
2987             ast::UseTreeKind::Nested(ref items) => {
2988                 if tree.prefix.segments.is_empty() {
2989                     self.s.word("{")?;
2990                 } else {
2991                     self.print_path(&tree.prefix, false, 0)?;
2992                     self.s.word("::{")?;
2993                 }
2994                 self.commasep(Inconsistent, &items[..], |this, &(ref tree, _)| {
2995                     this.print_use_tree(tree)
2996                 })?;
2997                 self.s.word("}")?;
2998             }
2999         }
3000
3001         Ok(())
3002     }
3003
3004     pub fn print_mutability(&mut self,
3005                             mutbl: ast::Mutability) -> io::Result<()> {
3006         match mutbl {
3007             ast::Mutability::Mutable => self.word_nbsp("mut"),
3008             ast::Mutability::Immutable => Ok(()),
3009         }
3010     }
3011
3012     pub fn print_mt(&mut self, mt: &ast::MutTy) -> io::Result<()> {
3013         self.print_mutability(mt.mutbl)?;
3014         self.print_type(&mt.ty)
3015     }
3016
3017     pub fn print_arg(&mut self, input: &ast::Arg, is_closure: bool) -> io::Result<()> {
3018         self.ibox(INDENT_UNIT)?;
3019         match input.ty.node {
3020             ast::TyKind::Infer if is_closure => self.print_pat(&input.pat)?,
3021             _ => {
3022                 if let Some(eself) = input.to_self() {
3023                     self.print_explicit_self(&eself)?;
3024                 } else {
3025                     let invalid = if let PatKind::Ident(_, ident, _) = input.pat.node {
3026                         ident.name == keywords::Invalid.name()
3027                     } else {
3028                         false
3029                     };
3030                     if !invalid {
3031                         self.print_pat(&input.pat)?;
3032                         self.s.word(":")?;
3033                         self.s.space()?;
3034                     }
3035                     self.print_type(&input.ty)?;
3036                 }
3037             }
3038         }
3039         self.end()
3040     }
3041
3042     pub fn print_fn_output(&mut self, decl: &ast::FnDecl) -> io::Result<()> {
3043         if let ast::FunctionRetTy::Default(..) = decl.output {
3044             return Ok(());
3045         }
3046
3047         self.space_if_not_bol()?;
3048         self.ibox(INDENT_UNIT)?;
3049         self.word_space("->")?;
3050         match decl.output {
3051             ast::FunctionRetTy::Default(..) => unreachable!(),
3052             ast::FunctionRetTy::Ty(ref ty) =>
3053                 self.print_type(ty)?
3054         }
3055         self.end()?;
3056
3057         match decl.output {
3058             ast::FunctionRetTy::Ty(ref output) => self.maybe_print_comment(output.span.lo()),
3059             _ => Ok(())
3060         }
3061     }
3062
3063     pub fn print_ty_fn(&mut self,
3064                        abi: abi::Abi,
3065                        unsafety: ast::Unsafety,
3066                        decl: &ast::FnDecl,
3067                        name: Option<ast::Ident>,
3068                        generic_params: &[ast::GenericParam])
3069                        -> io::Result<()> {
3070         self.ibox(INDENT_UNIT)?;
3071         if !generic_params.is_empty() {
3072             self.s.word("for")?;
3073             self.print_generic_params(generic_params)?;
3074         }
3075         let generics = ast::Generics {
3076             params: Vec::new(),
3077             where_clause: ast::WhereClause {
3078                 id: ast::DUMMY_NODE_ID,
3079                 predicates: Vec::new(),
3080                 span: syntax_pos::DUMMY_SP,
3081             },
3082             span: syntax_pos::DUMMY_SP,
3083         };
3084         self.print_fn(decl,
3085                       ast::FnHeader { unsafety, abi, ..ast::FnHeader::default() },
3086                       name,
3087                       &generics,
3088                       &source_map::dummy_spanned(ast::VisibilityKind::Inherited))?;
3089         self.end()
3090     }
3091
3092     pub fn maybe_print_trailing_comment(&mut self, span: syntax_pos::Span,
3093                                         next_pos: Option<BytePos>)
3094         -> io::Result<()> {
3095         let cm = match self.cm {
3096             Some(cm) => cm,
3097             _ => return Ok(())
3098         };
3099         if let Some(ref cmnt) = self.next_comment() {
3100             if cmnt.style != comments::Trailing { return Ok(()) }
3101             let span_line = cm.lookup_char_pos(span.hi());
3102             let comment_line = cm.lookup_char_pos(cmnt.pos);
3103             let next = next_pos.unwrap_or(cmnt.pos + BytePos(1));
3104             if span.hi() < cmnt.pos && cmnt.pos < next && span_line.line == comment_line.line {
3105                 self.print_comment(cmnt)?;
3106             }
3107         }
3108         Ok(())
3109     }
3110
3111     pub fn print_remaining_comments(&mut self) -> io::Result<()> {
3112         // If there aren't any remaining comments, then we need to manually
3113         // make sure there is a line break at the end.
3114         if self.next_comment().is_none() {
3115             self.s.hardbreak()?;
3116         }
3117         while let Some(ref cmnt) = self.next_comment() {
3118             self.print_comment(cmnt)?;
3119         }
3120         Ok(())
3121     }
3122
3123     pub fn print_opt_abi_and_extern_if_nondefault(&mut self,
3124                                                   opt_abi: Option<Abi>)
3125         -> io::Result<()> {
3126         match opt_abi {
3127             Some(Abi::Rust) => Ok(()),
3128             Some(abi) => {
3129                 self.word_nbsp("extern")?;
3130                 self.word_nbsp(&abi.to_string())
3131             }
3132             None => Ok(())
3133         }
3134     }
3135
3136     pub fn print_extern_opt_abi(&mut self,
3137                                 opt_abi: Option<Abi>) -> io::Result<()> {
3138         match opt_abi {
3139             Some(abi) => {
3140                 self.word_nbsp("extern")?;
3141                 self.word_nbsp(&abi.to_string())
3142             }
3143             None => Ok(())
3144         }
3145     }
3146
3147     pub fn print_fn_header_info(&mut self,
3148                                 header: ast::FnHeader,
3149                                 vis: &ast::Visibility) -> io::Result<()> {
3150         self.s.word(&visibility_qualified(vis, ""))?;
3151
3152         match header.constness.node {
3153             ast::Constness::NotConst => {}
3154             ast::Constness::Const => self.word_nbsp("const")?
3155         }
3156
3157         self.print_asyncness(header.asyncness)?;
3158         self.print_unsafety(header.unsafety)?;
3159
3160         if header.abi != Abi::Rust {
3161             self.word_nbsp("extern")?;
3162             self.word_nbsp(&header.abi.to_string())?;
3163         }
3164
3165         self.s.word("fn")
3166     }
3167
3168     pub fn print_unsafety(&mut self, s: ast::Unsafety) -> io::Result<()> {
3169         match s {
3170             ast::Unsafety::Normal => Ok(()),
3171             ast::Unsafety::Unsafe => self.word_nbsp("unsafe"),
3172         }
3173     }
3174
3175     pub fn print_is_auto(&mut self, s: ast::IsAuto) -> io::Result<()> {
3176         match s {
3177             ast::IsAuto::Yes => self.word_nbsp("auto"),
3178             ast::IsAuto::No => Ok(()),
3179         }
3180     }
3181 }
3182
3183 #[cfg(test)]
3184 mod tests {
3185     use super::*;
3186
3187     use ast;
3188     use source_map;
3189     use syntax_pos;
3190     use with_globals;
3191
3192     #[test]
3193     fn test_fun_to_string() {
3194         with_globals(|| {
3195             let abba_ident = ast::Ident::from_str("abba");
3196
3197             let decl = ast::FnDecl {
3198                 inputs: Vec::new(),
3199                 output: ast::FunctionRetTy::Default(syntax_pos::DUMMY_SP),
3200                 variadic: false
3201             };
3202             let generics = ast::Generics::default();
3203             assert_eq!(
3204                 fun_to_string(
3205                     &decl,
3206                     ast::FnHeader {
3207                         unsafety: ast::Unsafety::Normal,
3208                         constness: source_map::dummy_spanned(ast::Constness::NotConst),
3209                         asyncness: ast::IsAsync::NotAsync,
3210                         abi: Abi::Rust,
3211                     },
3212                     abba_ident,
3213                     &generics
3214                 ),
3215                 "fn abba()"
3216             );
3217         })
3218     }
3219
3220     #[test]
3221     fn test_variant_to_string() {
3222         with_globals(|| {
3223             let ident = ast::Ident::from_str("principal_skinner");
3224
3225             let var = source_map::respan(syntax_pos::DUMMY_SP, ast::Variant_ {
3226                 ident,
3227                 attrs: Vec::new(),
3228                 // making this up as I go.... ?
3229                 data: ast::VariantData::Unit(ast::DUMMY_NODE_ID),
3230                 disr_expr: None,
3231             });
3232
3233             let varstr = variant_to_string(&var);
3234             assert_eq!(varstr, "principal_skinner");
3235         })
3236     }
3237 }