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 abi::{self, Abi};
  14 use ast::{self, BlockCheckMode, PatKind};
  15 use ast::{SelfKind, RegionTyParamBound, TraitTyParamBound, TraitBoundModifier};
  16 use ast::Attribute;
  17 use util::parser::AssocOp;
  18 use attr;
  19 use attr::{AttrMetaMethods, AttributeMethods};
  20 use codemap::{self, CodeMap};
  21 use syntax_pos::{self, BytePos};
  22 use errors;
  23 use parse::token::{self, keywords, BinOpToken, Token, InternedString};
  24 use parse::lexer::comments;
  25 use parse;
  26 use print::pp::{self, break_offset, word, space, zerobreak, hardbreak};
  27 use print::pp::{Breaks, eof};
  28 use print::pp::Breaks::{Consistent, Inconsistent};
  29 use ptr::P;
  30 use std_inject;
  31 use tokenstream::{self, TokenTree};
  32
  33 use std::ascii;
  34 use std::io::{self, Write, Read};
  35 use std::iter;
  36
  37 pub enum AnnNode<'a> {
  38     NodeIdent(&'a ast::Ident),
  39     NodeName(&'a ast::Name),
  40     NodeBlock(&'a ast::Block),
  41     NodeItem(&'a ast::Item),
  42     NodeSubItem(ast::NodeId),
  43     NodeExpr(&'a ast::Expr),
  44     NodePat(&'a ast::Pat),
  45 }
  46
  47 pub trait PpAnn {
  48     fn pre(&self, _state: &mut State, _node: AnnNode) -> io::Result<()> { Ok(()) }
  49     fn post(&self, _state: &mut State, _node: AnnNode) -> io::Result<()> { Ok(()) }
  50 }
  51
  52 #[derive(Copy, Clone)]
  53 pub struct NoAnn;
  54
  55 impl PpAnn for NoAnn {}
  56
  57 #[derive(Copy, Clone)]
  58 pub struct CurrentCommentAndLiteral {
  59     pub cur_cmnt: usize,
  60     pub cur_lit: usize,
  61 }
  62
  63 pub struct State<'a> {
  64     pub s: pp::Printer<'a>,
  65     cm: Option<&'a CodeMap>,
  66     comments: Option<Vec<comments::Comment> >,
  67     literals: Option<Vec<comments::Literal> >,
  68     cur_cmnt_and_lit: CurrentCommentAndLiteral,
  69     boxes: Vec<pp::Breaks>,
  70     ann: &'a (PpAnn+'a),
  71 }
  72
  73 pub fn rust_printer<'a>(writer: Box<Write+'a>) -> State<'a> {
  74     static NO_ANN: NoAnn = NoAnn;
  75     rust_printer_annotated(writer, &NO_ANN)
  76 }
  77
  78 pub fn rust_printer_annotated<'a>(writer: Box<Write+'a>,
  79                                   ann: &'a PpAnn) -> State<'a> {
  80     State {
  81         s: pp::mk_printer(writer, DEFAULT_COLUMNS),
  82         cm: None,
  83         comments: None,
  84         literals: None,
  85         cur_cmnt_and_lit: CurrentCommentAndLiteral {
  86             cur_cmnt: 0,
  87             cur_lit: 0
  88         },
  89         boxes: Vec::new(),
  90         ann: ann,
  91     }
  92 }
  93
  94 pub const INDENT_UNIT: usize = 4;
  95
  96 pub const DEFAULT_COLUMNS: usize = 78;
  97
  98 /// Requires you to pass an input filename and reader so that
  99 /// it can scan the input text for comments and literals to
 100 /// copy forward.
 101 pub fn print_crate<'a>(cm: &'a CodeMap,
 102                        span_diagnostic: &errors::Handler,
 103                        krate: &ast::Crate,
 104                        filename: String,
 105                        input: &mut Read,
 106                        out: Box<Write+'a>,
 107                        ann: &'a PpAnn,
 108                        is_expanded: bool) -> io::Result<()> {
 109     let mut s = State::new_from_input(cm,
 110                                       span_diagnostic,
 111                                       filename,
 112                                       input,
 113                                       out,
 114                                       ann,
 115                                       is_expanded);
 116     if is_expanded && !std_inject::no_std(krate) {
 117         // We need to print `#![no_std]` (and its feature gate) so that
 118         // compiling pretty-printed source won't inject libstd again.
 119         // However we don't want these attributes in the AST because
 120         // of the feature gate, so we fake them up here.
 121
 122         // #![feature(prelude_import)]
 123         let prelude_import_meta = attr::mk_word_item(InternedString::new("prelude_import"));
 124         let list = attr::mk_list_item(InternedString::new("feature"),
 125                                       vec![prelude_import_meta]);
 126         let fake_attr = attr::mk_attr_inner(attr::mk_attr_id(), list);
 127         try!(s.print_attribute(&fake_attr));
 128
 129         // #![no_std]
 130         let no_std_meta = attr::mk_word_item(InternedString::new("no_std"));
 131         let fake_attr = attr::mk_attr_inner(attr::mk_attr_id(), no_std_meta);
 132         try!(s.print_attribute(&fake_attr));
 133     }
 134
 135     try!(s.print_mod(&krate.module, &krate.attrs));
 136     try!(s.print_remaining_comments());
 137     eof(&mut s.s)
 138 }
 139
 140 impl<'a> State<'a> {
 141     pub fn new_from_input(cm: &'a CodeMap,
 142                           span_diagnostic: &errors::Handler,
 143                           filename: String,
 144                           input: &mut Read,
 145                           out: Box<Write+'a>,
 146                           ann: &'a PpAnn,
 147                           is_expanded: bool) -> State<'a> {
 148         let (cmnts, lits) = comments::gather_comments_and_literals(
 149             span_diagnostic,
 150             filename,
 151             input);
 152
 153         State::new(
 154             cm,
 155             out,
 156             ann,
 157             Some(cmnts),
 158             // If the code is post expansion, don't use the table of
 159             // literals, since it doesn't correspond with the literals
 160             // in the AST anymore.
 161             if is_expanded { None } else { Some(lits) })
 162     }
 163
 164     pub fn new(cm: &'a CodeMap,
 165                out: Box<Write+'a>,
 166                ann: &'a PpAnn,
 167                comments: Option<Vec<comments::Comment>>,
 168                literals: Option<Vec<comments::Literal>>) -> State<'a> {
 169         State {
 170             s: pp::mk_printer(out, DEFAULT_COLUMNS),
 171             cm: Some(cm),
 172             comments: comments,
 173             literals: literals,
 174             cur_cmnt_and_lit: CurrentCommentAndLiteral {
 175                 cur_cmnt: 0,
 176                 cur_lit: 0
 177             },
 178             boxes: Vec::new(),
 179             ann: ann,
 180         }
 181     }
 182 }
 183
 184 pub fn to_string<F>(f: F) -> String where
 185     F: FnOnce(&mut State) -> io::Result<()>,
 186 {
 187     let mut wr = Vec::new();
 188     {
 189         let mut printer = rust_printer(Box::new(&mut wr));
 190         f(&mut printer).unwrap();
 191         eof(&mut printer.s).unwrap();
 192     }
 193     String::from_utf8(wr).unwrap()
 194 }
 195
 196 pub fn binop_to_string(op: BinOpToken) -> &'static str {
 197     match op {
 198         token::Plus     => "+",
 199         token::Minus    => "-",
 200         token::Star     => "*",
 201         token::Slash    => "/",
 202         token::Percent  => "%",
 203         token::Caret    => "^",
 204         token::And      => "&",
 205         token::Or       => "|",
 206         token::Shl      => "<<",
 207         token::Shr      => ">>",
 208     }
 209 }
 210
 211 pub fn token_to_string(tok: &Token) -> String {
 212     match *tok {
 213         token::Eq                   => "=".to_string(),
 214         token::Lt                   => "<".to_string(),
 215         token::Le                   => "<=".to_string(),
 216         token::EqEq                 => "==".to_string(),
 217         token::Ne                   => "!=".to_string(),
 218         token::Ge                   => ">=".to_string(),
 219         token::Gt                   => ">".to_string(),
 220         token::Not                  => "!".to_string(),
 221         token::Tilde                => "~".to_string(),
 222         token::OrOr                 => "||".to_string(),
 223         token::AndAnd               => "&&".to_string(),
 224         token::BinOp(op)            => binop_to_string(op).to_string(),
 225         token::BinOpEq(op)          => format!("{}=", binop_to_string(op)),
 226
 227         /* Structural symbols */
 228         token::At                   => "@".to_string(),
 229         token::Dot                  => ".".to_string(),
 230         token::DotDot               => "..".to_string(),
 231         token::DotDotDot            => "...".to_string(),
 232         token::Comma                => ",".to_string(),
 233         token::Semi                 => ";".to_string(),
 234         token::Colon                => ":".to_string(),
 235         token::ModSep               => "::".to_string(),
 236         token::RArrow               => "->".to_string(),
 237         token::LArrow               => "<-".to_string(),
 238         token::FatArrow             => "=>".to_string(),
 239         token::OpenDelim(token::Paren) => "(".to_string(),
 240         token::CloseDelim(token::Paren) => ")".to_string(),
 241         token::OpenDelim(token::Bracket) => "[".to_string(),
 242         token::CloseDelim(token::Bracket) => "]".to_string(),
 243         token::OpenDelim(token::Brace) => "{".to_string(),
 244         token::CloseDelim(token::Brace) => "}".to_string(),
 245         token::Pound                => "#".to_string(),
 246         token::Dollar               => "$".to_string(),
 247         token::Question             => "?".to_string(),
 248
 249         /* Literals */
 250         token::Literal(lit, suf) => {
 251             let mut out = match lit {
 252                 token::Byte(b)           => format!("b'{}'", b),
 253                 token::Char(c)           => format!("'{}'", c),
 254                 token::Float(c)          => c.to_string(),
 255                 token::Integer(c)        => c.to_string(),
 256                 token::Str_(s)           => format!("\"{}\"", s),
 257                 token::StrRaw(s, n)      => format!("r{delim}\"{string}\"{delim}",
 258                                                     delim=repeat("#", n),
 259                                                     string=s),
 260                 token::ByteStr(v)         => format!("b\"{}\"", v),
 261                 token::ByteStrRaw(s, n)   => format!("br{delim}\"{string}\"{delim}",
 262                                                     delim=repeat("#", n),
 263                                                     string=s),
 264             };
 265
 266             if let Some(s) = suf {
 267                 out.push_str(&s.as_str())
 268             }
 269
 270             out
 271         }
 272
 273         /* Name components */
 274         token::Ident(s)             => s.to_string(),
 275         token::Lifetime(s)          => s.to_string(),
 276         token::Underscore           => "_".to_string(),
 277
 278         /* Other */
 279         token::DocComment(s)        => s.to_string(),
 280         token::SubstNt(s)           => format!("${}", s),
 281         token::MatchNt(s, t)        => format!("${}:{}", s, t),
 282         token::Eof                  => "<eof>".to_string(),
 283         token::Whitespace           => " ".to_string(),
 284         token::Comment              => "/* */".to_string(),
 285         token::Shebang(s)           => format!("/* shebang: {}*/", s),
 286
 287         token::SpecialVarNt(var)    => format!("${}", var.as_str()),
 288
 289         token::Interpolated(ref nt) => match *nt {
 290             token::NtExpr(ref e)        => expr_to_string(&e),
 291             token::NtMeta(ref e)        => meta_item_to_string(&e),
 292             token::NtTy(ref e)          => ty_to_string(&e),
 293             token::NtPath(ref e)        => path_to_string(&e),
 294             token::NtItem(ref e)        => item_to_string(&e),
 295             token::NtBlock(ref e)       => block_to_string(&e),
 296             token::NtStmt(ref e)        => stmt_to_string(&e),
 297             token::NtPat(ref e)         => pat_to_string(&e),
 298             token::NtIdent(ref e)       => ident_to_string(e.node),
 299             token::NtTT(ref e)          => tt_to_string(&e),
 300             token::NtArm(ref e)         => arm_to_string(&e),
 301             token::NtImplItem(ref e)    => impl_item_to_string(&e),
 302             token::NtTraitItem(ref e)   => trait_item_to_string(&e),
 303             token::NtGenerics(ref e)    => generics_to_string(&e),
 304             token::NtWhereClause(ref e) => where_clause_to_string(&e),
 305             token::NtArg(ref e)         => arg_to_string(&e),
 306         }
 307     }
 308 }
 309
 310 pub fn ty_to_string(ty: &ast::Ty) -> String {
 311     to_string(|s| s.print_type(ty))
 312 }
 313
 314 pub fn bounds_to_string(bounds: &[ast::TyParamBound]) -> String {
 315     to_string(|s| s.print_bounds("", bounds))
 316 }
 317
 318 pub fn pat_to_string(pat: &ast::Pat) -> String {
 319     to_string(|s| s.print_pat(pat))
 320 }
 321
 322 pub fn arm_to_string(arm: &ast::Arm) -> String {
 323     to_string(|s| s.print_arm(arm))
 324 }
 325
 326 pub fn expr_to_string(e: &ast::Expr) -> String {
 327     to_string(|s| s.print_expr(e))
 328 }
 329
 330 pub fn lifetime_to_string(e: &ast::Lifetime) -> String {
 331     to_string(|s| s.print_lifetime(e))
 332 }
 333
 334 pub fn tt_to_string(tt: &tokenstream::TokenTree) -> String {
 335     to_string(|s| s.print_tt(tt))
 336 }
 337
 338 pub fn tts_to_string(tts: &[tokenstream::TokenTree]) -> String {
 339     to_string(|s| s.print_tts(tts))
 340 }
 341
 342 pub fn stmt_to_string(stmt: &ast::Stmt) -> String {
 343     to_string(|s| s.print_stmt(stmt))
 344 }
 345
 346 pub fn attr_to_string(attr: &ast::Attribute) -> String {
 347     to_string(|s| s.print_attribute(attr))
 348 }
 349
 350 pub fn item_to_string(i: &ast::Item) -> String {
 351     to_string(|s| s.print_item(i))
 352 }
 353
 354 pub fn impl_item_to_string(i: &ast::ImplItem) -> String {
 355     to_string(|s| s.print_impl_item(i))
 356 }
 357
 358 pub fn trait_item_to_string(i: &ast::TraitItem) -> String {
 359     to_string(|s| s.print_trait_item(i))
 360 }
 361
 362 pub fn generics_to_string(generics: &ast::Generics) -> String {
 363     to_string(|s| s.print_generics(generics))
 364 }
 365
 366 pub fn where_clause_to_string(i: &ast::WhereClause) -> String {
 367     to_string(|s| s.print_where_clause(i))
 368 }
 369
 370 pub fn fn_block_to_string(p: &ast::FnDecl) -> String {
 371     to_string(|s| s.print_fn_block_args(p))
 372 }
 373
 374 pub fn path_to_string(p: &ast::Path) -> String {
 375     to_string(|s| s.print_path(p, false, 0))
 376 }
 377
 378 pub fn ident_to_string(id: ast::Ident) -> String {
 379     to_string(|s| s.print_ident(id))
 380 }
 381
 382 pub fn fun_to_string(decl: &ast::FnDecl,
 383                      unsafety: ast::Unsafety,
 384                      constness: ast::Constness,
 385                      name: ast::Ident,
 386                      generics: &ast::Generics)
 387                      -> String {
 388     to_string(|s| {
 389         try!(s.head(""));
 390         try!(s.print_fn(decl, unsafety, constness, Abi::Rust, Some(name),
 391                    generics, &ast::Visibility::Inherited));
 392         try!(s.end()); // Close the head box
 393         s.end() // Close the outer box
 394     })
 395 }
 396
 397 pub fn block_to_string(blk: &ast::Block) -> String {
 398     to_string(|s| {
 399         // containing cbox, will be closed by print-block at }
 400         try!(s.cbox(INDENT_UNIT));
 401         // head-ibox, will be closed by print-block after {
 402         try!(s.ibox(0));
 403         s.print_block(blk)
 404     })
 405 }
 406
 407 pub fn meta_item_to_string(mi: &ast::MetaItem) -> String {
 408     to_string(|s| s.print_meta_item(mi))
 409 }
 410
 411 pub fn attribute_to_string(attr: &ast::Attribute) -> String {
 412     to_string(|s| s.print_attribute(attr))
 413 }
 414
 415 pub fn lit_to_string(l: &ast::Lit) -> String {
 416     to_string(|s| s.print_literal(l))
 417 }
 418
 419 pub fn variant_to_string(var: &ast::Variant) -> String {
 420     to_string(|s| s.print_variant(var))
 421 }
 422
 423 pub fn arg_to_string(arg: &ast::Arg) -> String {
 424     to_string(|s| s.print_arg(arg, false))
 425 }
 426
 427 pub fn mac_to_string(arg: &ast::Mac) -> String {
 428     to_string(|s| s.print_mac(arg, ::parse::token::Paren))
 429 }
 430
 431 pub fn visibility_qualified(vis: &ast::Visibility, s: &str) -> String {
 432     match *vis {
 433         ast::Visibility::Public => format!("pub {}", s),
 434         ast::Visibility::Crate(_) => format!("pub(crate) {}", s),
 435         ast::Visibility::Restricted { ref path, .. } => format!("pub({}) {}", path, s),
 436         ast::Visibility::Inherited => s.to_string()
 437     }
 438 }
 439
 440 fn needs_parentheses(expr: &ast::Expr) -> bool {
 441     match expr.node {
 442         ast::ExprKind::Assign(..) | ast::ExprKind::Binary(..) |
 443         ast::ExprKind::Closure(..) |
 444         ast::ExprKind::AssignOp(..) | ast::ExprKind::Cast(..) |
 445         ast::ExprKind::InPlace(..) | ast::ExprKind::Type(..) => true,
 446         _ => false,
 447     }
 448 }
 449
 450 pub trait PrintState<'a> {
 451     fn writer(&mut self) -> &mut pp::Printer<'a>;
 452     fn boxes(&mut self) -> &mut Vec<pp::Breaks>;
 453     fn comments(&mut self) -> &mut Option<Vec<comments::Comment>>;
 454     fn cur_cmnt_and_lit(&mut self) -> &mut CurrentCommentAndLiteral;
 455     fn literals(&self) -> &Option<Vec<comments::Literal>>;
 456
 457     fn word_space(&mut self, w: &str) -> io::Result<()> {
 458         try!(word(self.writer(), w));
 459         space(self.writer())
 460     }
 461
 462     fn popen(&mut self) -> io::Result<()> { word(self.writer(), "(") }
 463
 464     fn pclose(&mut self) -> io::Result<()> { word(self.writer(), ")") }
 465
 466     fn is_begin(&mut self) -> bool {
 467         match self.writer().last_token() {
 468             pp::Token::Begin(_) => true,
 469             _ => false,
 470         }
 471     }
 472
 473     fn is_end(&mut self) -> bool {
 474         match self.writer().last_token() {
 475             pp::Token::End => true,
 476             _ => false,
 477         }
 478     }
 479
 480     // is this the beginning of a line?
 481     fn is_bol(&mut self) -> bool {
 482         self.writer().last_token().is_eof() || self.writer().last_token().is_hardbreak_tok()
 483     }
 484
 485     fn hardbreak_if_not_bol(&mut self) -> io::Result<()> {
 486         if !self.is_bol() {
 487             try!(hardbreak(self.writer()))
 488         }
 489         Ok(())
 490     }
 491
 492     // "raw box"
 493     fn rbox(&mut self, u: usize, b: pp::Breaks) -> io::Result<()> {
 494         self.boxes().push(b);
 495         pp::rbox(self.writer(), u, b)
 496     }
 497
 498     fn ibox(&mut self, u: usize) -> io::Result<()> {
 499         self.boxes().push(pp::Breaks::Inconsistent);
 500         pp::ibox(self.writer(), u)
 501     }
 502
 503     fn end(&mut self) -> io::Result<()> {
 504         self.boxes().pop().unwrap();
 505         pp::end(self.writer())
 506     }
 507
 508     fn commasep<T, F>(&mut self, b: Breaks, elts: &[T], mut op: F) -> io::Result<()>
 509         where F: FnMut(&mut Self, &T) -> io::Result<()>,
 510     {
 511         try!(self.rbox(0, b));
 512         let mut first = true;
 513         for elt in elts {
 514             if first { first = false; } else { try!(self.word_space(",")); }
 515             try!(op(self, elt));
 516         }
 517         self.end()
 518     }
 519
 520     fn next_lit(&mut self, pos: BytePos) -> Option<comments::Literal> {
 521         let mut cur_lit = self.cur_cmnt_and_lit().cur_lit;
 522
 523         let mut result = None;
 524
 525         if let &Some(ref lits) = self.literals()
 526         {
 527             while cur_lit < lits.len() {
 528                 let ltrl = (*lits)[cur_lit].clone();
 529                 if ltrl.pos > pos { break; }
 530                 cur_lit += 1;
 531                 if ltrl.pos == pos {
 532                     result = Some(ltrl);
 533                     break;
 534                 }
 535             }
 536         }
 537
 538         self.cur_cmnt_and_lit().cur_lit = cur_lit;
 539         result
 540     }
 541
 542     fn maybe_print_comment(&mut self, pos: BytePos) -> io::Result<()> {
 543         loop {
 544             match self.next_comment() {
 545                 Some(ref cmnt) => {
 546                     if (*cmnt).pos < pos {
 547                         try!(self.print_comment(cmnt));
 548                         self.cur_cmnt_and_lit().cur_cmnt += 1;
 549                     } else { break; }
 550                 }
 551                 _ => break
 552             }
 553         }
 554         Ok(())
 555     }
 556
 557     fn print_comment(&mut self,
 558                      cmnt: &comments::Comment) -> io::Result<()> {
 559         match cmnt.style {
 560             comments::Mixed => {
 561                 assert_eq!(cmnt.lines.len(), 1);
 562                 try!(zerobreak(self.writer()));
 563                 try!(word(self.writer(), &cmnt.lines[0]));
 564                 zerobreak(self.writer())
 565             }
 566             comments::Isolated => {
 567                 try!(self.hardbreak_if_not_bol());
 568                 for line in &cmnt.lines {
 569                     // Don't print empty lines because they will end up as trailing
 570                     // whitespace
 571                     if !line.is_empty() {
 572                         try!(word(self.writer(), &line[..]));
 573                     }
 574                     try!(hardbreak(self.writer()));
 575                 }
 576                 Ok(())
 577             }
 578             comments::Trailing => {
 579                 try!(word(self.writer(), " "));
 580                 if cmnt.lines.len() == 1 {
 581                     try!(word(self.writer(), &cmnt.lines[0]));
 582                     hardbreak(self.writer())
 583                 } else {
 584                     try!(self.ibox(0));
 585                     for line in &cmnt.lines {
 586                         if !line.is_empty() {
 587                             try!(word(self.writer(), &line[..]));
 588                         }
 589                         try!(hardbreak(self.writer()));
 590                     }
 591                     self.end()
 592                 }
 593             }
 594             comments::BlankLine => {
 595                 // We need to do at least one, possibly two hardbreaks.
 596                 let is_semi = match self.writer().last_token() {
 597                     pp::Token::String(s, _) => ";" == s,
 598                     _ => false
 599                 };
 600                 if is_semi || self.is_begin() || self.is_end() {
 601                     try!(hardbreak(self.writer()));
 602                 }
 603                 hardbreak(self.writer())
 604             }
 605         }
 606     }
 607
 608     fn next_comment(&mut self) -> Option<comments::Comment> {
 609         let cur_cmnt = self.cur_cmnt_and_lit().cur_cmnt;
 610         match *self.comments() {
 611             Some(ref cmnts) => {
 612                 if cur_cmnt < cmnts.len() {
 613                     Some(cmnts[cur_cmnt].clone())
 614                 } else {
 615                     None
 616                 }
 617             }
 618             _ => None
 619         }
 620     }
 621
 622     fn print_literal(&mut self, lit: &ast::Lit) -> io::Result<()> {
 623         try!(self.maybe_print_comment(lit.span.lo));
 624         match self.next_lit(lit.span.lo) {
 625             Some(ref ltrl) => {
 626                 return word(self.writer(), &(*ltrl).lit);
 627             }
 628             _ => ()
 629         }
 630         match lit.node {
 631             ast::LitKind::Str(ref st, style) => self.print_string(&st, style),
 632             ast::LitKind::Byte(byte) => {
 633                 let mut res = String::from("b'");
 634                 res.extend(ascii::escape_default(byte).map(|c| c as char));
 635                 res.push('\'');
 636                 word(self.writer(), &res[..])
 637             }
 638             ast::LitKind::Char(ch) => {
 639                 let mut res = String::from("'");
 640                 res.extend(ch.escape_default());
 641                 res.push('\'');
 642                 word(self.writer(), &res[..])
 643             }
 644             ast::LitKind::Int(i, t) => {
 645                 match t {
 646                     ast::LitIntType::Signed(st) => {
 647                         word(self.writer(),
 648                              &st.val_to_string(i as i64))
 649                     }
 650                     ast::LitIntType::Unsigned(ut) => {
 651                         word(self.writer(), &ut.val_to_string(i))
 652                     }
 653                     ast::LitIntType::Unsuffixed => {
 654                         word(self.writer(), &format!("{}", i))
 655                     }
 656                 }
 657             }
 658             ast::LitKind::Float(ref f, t) => {
 659                 word(self.writer(),
 660                      &format!(
 661                          "{}{}",
 662                          &f,
 663                          t.ty_to_string()))
 664             }
 665             ast::LitKind::FloatUnsuffixed(ref f) => word(self.writer(), &f[..]),
 666             ast::LitKind::Bool(val) => {
 667                 if val { word(self.writer(), "true") } else { word(self.writer(), "false") }
 668             }
 669             ast::LitKind::ByteStr(ref v) => {
 670                 let mut escaped: String = String::new();
 671                 for &ch in v.iter() {
 672                     escaped.extend(ascii::escape_default(ch)
 673                                          .map(|c| c as char));
 674                 }
 675                 word(self.writer(), &format!("b\"{}\"", escaped))
 676             }
 677         }
 678     }
 679
 680     fn print_string(&mut self, st: &str,
 681                     style: ast::StrStyle) -> io::Result<()> {
 682         let st = match style {
 683             ast::StrStyle::Cooked => {
 684                 (format!("\"{}\"", st.escape_default()))
 685             }
 686             ast::StrStyle::Raw(n) => {
 687                 (format!("r{delim}\"{string}\"{delim}",
 688                          delim=repeat("#", n),
 689                          string=st))
 690             }
 691         };
 692         word(self.writer(), &st[..])
 693     }
 694
 695     fn print_inner_attributes(&mut self,
 696                               attrs: &[ast::Attribute]) -> io::Result<()> {
 697         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, true)
 698     }
 699
 700     fn print_inner_attributes_no_trailing_hardbreak(&mut self,
 701                                                    attrs: &[ast::Attribute])
 702                                                    -> io::Result<()> {
 703         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, false)
 704     }
 705
 706     fn print_outer_attributes(&mut self,
 707                               attrs: &[ast::Attribute]) -> io::Result<()> {
 708         self.print_either_attributes(attrs, ast::AttrStyle::Outer, false, true)
 709     }
 710
 711     fn print_inner_attributes_inline(&mut self,
 712                                      attrs: &[ast::Attribute]) -> io::Result<()> {
 713         self.print_either_attributes(attrs, ast::AttrStyle::Inner, true, true)
 714     }
 715
 716     fn print_outer_attributes_inline(&mut self,
 717                                      attrs: &[ast::Attribute]) -> io::Result<()> {
 718         self.print_either_attributes(attrs, ast::AttrStyle::Outer, true, true)
 719     }
 720
 721     fn print_either_attributes(&mut self,
 722                               attrs: &[ast::Attribute],
 723                               kind: ast::AttrStyle,
 724                               is_inline: bool,
 725                               trailing_hardbreak: bool) -> io::Result<()> {
 726         let mut count = 0;
 727         for attr in attrs {
 728             if attr.node.style == kind {
 729                 try!(self.print_attribute_inline(attr, is_inline));
 730                 if is_inline {
 731                     try!(self.nbsp());
 732                 }
 733                 count += 1;
 734             }
 735         }
 736         if count > 0 && trailing_hardbreak && !is_inline {
 737             try!(self.hardbreak_if_not_bol());
 738         }
 739         Ok(())
 740     }
 741
 742     fn print_attribute(&mut self, attr: &ast::Attribute) -> io::Result<()> {
 743         self.print_attribute_inline(attr, false)
 744     }
 745
 746     fn print_attribute_inline(&mut self, attr: &ast::Attribute,
 747                               is_inline: bool) -> io::Result<()> {
 748         if !is_inline {
 749             try!(self.hardbreak_if_not_bol());
 750         }
 751         try!(self.maybe_print_comment(attr.span.lo));
 752         if attr.node.is_sugared_doc {
 753             try!(word(self.writer(), &attr.value_str().unwrap()));
 754             hardbreak(self.writer())
 755         } else {
 756             match attr.node.style {
 757                 ast::AttrStyle::Inner => try!(word(self.writer(), "#![")),
 758                 ast::AttrStyle::Outer => try!(word(self.writer(), "#[")),
 759             }
 760             try!(self.print_meta_item(&attr.meta()));
 761             word(self.writer(), "]")
 762         }
 763     }
 764
 765     fn print_meta_item(&mut self, item: &ast::MetaItem) -> io::Result<()> {
 766         try!(self.ibox(INDENT_UNIT));
 767         match item.node {
 768             ast::MetaItemKind::Word(ref name) => {
 769                 try!(word(self.writer(), &name));
 770             }
 771             ast::MetaItemKind::NameValue(ref name, ref value) => {
 772                 try!(self.word_space(&name[..]));
 773                 try!(self.word_space("="));
 774                 try!(self.print_literal(value));
 775             }
 776             ast::MetaItemKind::List(ref name, ref items) => {
 777                 try!(word(self.writer(), &name));
 778                 try!(self.popen());
 779                 try!(self.commasep(Consistent,
 780                               &items[..],
 781                               |s, i| s.print_meta_item(&i)));
 782                 try!(self.pclose());
 783             }
 784         }
 785         self.end()
 786     }
 787
 788     fn space_if_not_bol(&mut self) -> io::Result<()> {
 789         if !self.is_bol() { try!(space(self.writer())); }
 790         Ok(())
 791     }
 792
 793     fn nbsp(&mut self) -> io::Result<()> { word(self.writer(), " ") }
 794 }
 795
 796 impl<'a> PrintState<'a> for State<'a> {
 797     fn writer(&mut self) -> &mut pp::Printer<'a> {
 798         &mut self.s
 799     }
 800
 801     fn boxes(&mut self) -> &mut Vec<pp::Breaks> {
 802         &mut self.boxes
 803     }
 804
 805     fn comments(&mut self) -> &mut Option<Vec<comments::Comment>> {
 806         &mut self.comments
 807     }
 808
 809     fn cur_cmnt_and_lit(&mut self) -> &mut CurrentCommentAndLiteral {
 810         &mut self.cur_cmnt_and_lit
 811     }
 812
 813     fn literals(&self) -> &Option<Vec<comments::Literal>> {
 814         &self.literals
 815     }
 816 }
 817
 818 impl<'a> State<'a> {
 819     pub fn cbox(&mut self, u: usize) -> io::Result<()> {
 820         self.boxes.push(pp::Breaks::Consistent);
 821         pp::cbox(&mut self.s, u)
 822     }
 823
 824     pub fn word_nbsp(&mut self, w: &str) -> io::Result<()> {
 825         try!(word(&mut self.s, w));
 826         self.nbsp()
 827     }
 828
 829     pub fn head(&mut self, w: &str) -> io::Result<()> {
 830         // outer-box is consistent
 831         try!(self.cbox(INDENT_UNIT));
 832         // head-box is inconsistent
 833         try!(self.ibox(w.len() + 1));
 834         // keyword that starts the head
 835         if !w.is_empty() {
 836             try!(self.word_nbsp(w));
 837         }
 838         Ok(())
 839     }
 840
 841     pub fn bopen(&mut self) -> io::Result<()> {
 842         try!(word(&mut self.s, "{"));
 843         self.end() // close the head-box
 844     }
 845
 846     pub fn bclose_(&mut self, span: syntax_pos::Span,
 847                    indented: usize) -> io::Result<()> {
 848         self.bclose_maybe_open(span, indented, true)
 849     }
 850     pub fn bclose_maybe_open(&mut self, span: syntax_pos::Span,
 851                              indented: usize, close_box: bool) -> io::Result<()> {
 852         try!(self.maybe_print_comment(span.hi));
 853         try!(self.break_offset_if_not_bol(1, -(indented as isize)));
 854         try!(word(&mut self.s, "}"));
 855         if close_box {
 856             try!(self.end()); // close the outer-box
 857         }
 858         Ok(())
 859     }
 860     pub fn bclose(&mut self, span: syntax_pos::Span) -> io::Result<()> {
 861         self.bclose_(span, INDENT_UNIT)
 862     }
 863
 864     pub fn in_cbox(&self) -> bool {
 865         match self.boxes.last() {
 866             Some(&last_box) => last_box == pp::Breaks::Consistent,
 867             None => false
 868         }
 869     }
 870
 871     pub fn break_offset_if_not_bol(&mut self, n: usize,
 872                                    off: isize) -> io::Result<()> {
 873         if !self.is_bol() {
 874             break_offset(&mut self.s, n, off)
 875         } else {
 876             if off != 0 && self.s.last_token().is_hardbreak_tok() {
 877                 // We do something pretty sketchy here: tuck the nonzero
 878                 // offset-adjustment we were going to deposit along with the
 879                 // break into the previous hardbreak.
 880                 self.s.replace_last_token(pp::hardbreak_tok_offset(off));
 881             }
 882             Ok(())
 883         }
 884     }
 885
 886     // Synthesizes a comment that was not textually present in the original source
 887     // file.
 888     pub fn synth_comment(&mut self, text: String) -> io::Result<()> {
 889         try!(word(&mut self.s, "/*"));
 890         try!(space(&mut self.s));
 891         try!(word(&mut self.s, &text[..]));
 892         try!(space(&mut self.s));
 893         word(&mut self.s, "*/")
 894     }
 895
 896
 897
 898     pub fn commasep_cmnt<T, F, G>(&mut self,
 899                                   b: Breaks,
 900                                   elts: &[T],
 901                                   mut op: F,
 902                                   mut get_span: G) -> io::Result<()> where
 903         F: FnMut(&mut State, &T) -> io::Result<()>,
 904         G: FnMut(&T) -> syntax_pos::Span,
 905     {
 906         try!(self.rbox(0, b));
 907         let len = elts.len();
 908         let mut i = 0;
 909         for elt in elts {
 910             try!(self.maybe_print_comment(get_span(elt).hi));
 911             try!(op(self, elt));
 912             i += 1;
 913             if i < len {
 914                 try!(word(&mut self.s, ","));
 915                 try!(self.maybe_print_trailing_comment(get_span(elt),
 916                                                   Some(get_span(&elts[i]).hi)));
 917                 try!(self.space_if_not_bol());
 918             }
 919         }
 920         self.end()
 921     }
 922
 923     pub fn commasep_exprs(&mut self, b: Breaks,
 924                           exprs: &[P<ast::Expr>]) -> io::Result<()> {
 925         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(&e), |e| e.span)
 926     }
 927
 928     pub fn print_mod(&mut self, _mod: &ast::Mod,
 929                      attrs: &[ast::Attribute]) -> io::Result<()> {
 930         try!(self.print_inner_attributes(attrs));
 931         for item in &_mod.items {
 932             try!(self.print_item(&item));
 933         }
 934         Ok(())
 935     }
 936
 937     pub fn print_foreign_mod(&mut self, nmod: &ast::ForeignMod,
 938                              attrs: &[ast::Attribute]) -> io::Result<()> {
 939         try!(self.print_inner_attributes(attrs));
 940         for item in &nmod.items {
 941             try!(self.print_foreign_item(item));
 942         }
 943         Ok(())
 944     }
 945
 946     pub fn print_opt_lifetime(&mut self,
 947                               lifetime: &Option<ast::Lifetime>) -> io::Result<()> {
 948         if let Some(l) = *lifetime {
 949             try!(self.print_lifetime(&l));
 950             try!(self.nbsp());
 951         }
 952         Ok(())
 953     }
 954
 955     pub fn print_type(&mut self, ty: &ast::Ty) -> io::Result<()> {
 956         try!(self.maybe_print_comment(ty.span.lo));
 957         try!(self.ibox(0));
 958         match ty.node {
 959             ast::TyKind::Vec(ref ty) => {
 960                 try!(word(&mut self.s, "["));
 961                 try!(self.print_type(&ty));
 962                 try!(word(&mut self.s, "]"));
 963             }
 964             ast::TyKind::Ptr(ref mt) => {
 965                 try!(word(&mut self.s, "*"));
 966                 match mt.mutbl {
 967                     ast::Mutability::Mutable => try!(self.word_nbsp("mut")),
 968                     ast::Mutability::Immutable => try!(self.word_nbsp("const")),
 969                 }
 970                 try!(self.print_type(&mt.ty));
 971             }
 972             ast::TyKind::Rptr(ref lifetime, ref mt) => {
 973                 try!(word(&mut self.s, "&"));
 974                 try!(self.print_opt_lifetime(lifetime));
 975                 try!(self.print_mt(mt));
 976             }
 977             ast::TyKind::Tup(ref elts) => {
 978                 try!(self.popen());
 979                 try!(self.commasep(Inconsistent, &elts[..],
 980                               |s, ty| s.print_type(&ty)));
 981                 if elts.len() == 1 {
 982                     try!(word(&mut self.s, ","));
 983                 }
 984                 try!(self.pclose());
 985             }
 986             ast::TyKind::Paren(ref typ) => {
 987                 try!(self.popen());
 988                 try!(self.print_type(&typ));
 989                 try!(self.pclose());
 990             }
 991             ast::TyKind::BareFn(ref f) => {
 992                 let generics = ast::Generics {
 993                     lifetimes: f.lifetimes.clone(),
 994                     ty_params: P::new(),
 995                     where_clause: ast::WhereClause {
 996                         id: ast::DUMMY_NODE_ID,
 997                         predicates: Vec::new(),
 998                     },
 999                 };
1000                 try!(self.print_ty_fn(f.abi,
1001                                  f.unsafety,
1002                                  &f.decl,
1003                                  None,
1004                                  &generics));
1005             }
1006             ast::TyKind::Path(None, ref path) => {
1007                 try!(self.print_path(path, false, 0));
1008             }
1009             ast::TyKind::Path(Some(ref qself), ref path) => {
1010                 try!(self.print_qpath(path, qself, false))
1011             }
1012             ast::TyKind::ObjectSum(ref ty, ref bounds) => {
1013                 try!(self.print_type(&ty));
1014                 try!(self.print_bounds("+", &bounds[..]));
1015             }
1016             ast::TyKind::PolyTraitRef(ref bounds) => {
1017                 try!(self.print_bounds("", &bounds[..]));
1018             }
1019             ast::TyKind::FixedLengthVec(ref ty, ref v) => {
1020                 try!(word(&mut self.s, "["));
1021                 try!(self.print_type(&ty));
1022                 try!(word(&mut self.s, "; "));
1023                 try!(self.print_expr(&v));
1024                 try!(word(&mut self.s, "]"));
1025             }
1026             ast::TyKind::Typeof(ref e) => {
1027                 try!(word(&mut self.s, "typeof("));
1028                 try!(self.print_expr(&e));
1029                 try!(word(&mut self.s, ")"));
1030             }
1031             ast::TyKind::Infer => {
1032                 try!(word(&mut self.s, "_"));
1033             }
1034             ast::TyKind::ImplicitSelf => {
1035                 try!(word(&mut self.s, "Self"));
1036             }
1037             ast::TyKind::Mac(ref m) => {
1038                 try!(self.print_mac(m, token::Paren));
1039             }
1040         }
1041         self.end()
1042     }
1043
1044     pub fn print_foreign_item(&mut self,
1045                               item: &ast::ForeignItem) -> io::Result<()> {
1046         try!(self.hardbreak_if_not_bol());
1047         try!(self.maybe_print_comment(item.span.lo));
1048         try!(self.print_outer_attributes(&item.attrs));
1049         match item.node {
1050             ast::ForeignItemKind::Fn(ref decl, ref generics) => {
1051                 try!(self.head(""));
1052                 try!(self.print_fn(decl, ast::Unsafety::Normal,
1053                               ast::Constness::NotConst,
1054                               Abi::Rust, Some(item.ident),
1055                               generics, &item.vis));
1056                 try!(self.end()); // end head-ibox
1057                 try!(word(&mut self.s, ";"));
1058                 self.end() // end the outer fn box
1059             }
1060             ast::ForeignItemKind::Static(ref t, m) => {
1061                 try!(self.head(&visibility_qualified(&item.vis, "static")));
1062                 if m {
1063                     try!(self.word_space("mut"));
1064                 }
1065                 try!(self.print_ident(item.ident));
1066                 try!(self.word_space(":"));
1067                 try!(self.print_type(&t));
1068                 try!(word(&mut self.s, ";"));
1069                 try!(self.end()); // end the head-ibox
1070                 self.end() // end the outer cbox
1071             }
1072         }
1073     }
1074
1075     fn print_associated_const(&mut self,
1076                               ident: ast::Ident,
1077                               ty: &ast::Ty,
1078                               default: Option<&ast::Expr>,
1079                               vis: &ast::Visibility)
1080                               -> io::Result<()>
1081     {
1082         try!(word(&mut self.s, &visibility_qualified(vis, "")));
1083         try!(self.word_space("const"));
1084         try!(self.print_ident(ident));
1085         try!(self.word_space(":"));
1086         try!(self.print_type(ty));
1087         if let Some(expr) = default {
1088             try!(space(&mut self.s));
1089             try!(self.word_space("="));
1090             try!(self.print_expr(expr));
1091         }
1092         word(&mut self.s, ";")
1093     }
1094
1095     fn print_associated_type(&mut self,
1096                              ident: ast::Ident,
1097                              bounds: Option<&ast::TyParamBounds>,
1098                              ty: Option<&ast::Ty>)
1099                              -> io::Result<()> {
1100         try!(self.word_space("type"));
1101         try!(self.print_ident(ident));
1102         if let Some(bounds) = bounds {
1103             try!(self.print_bounds(":", bounds));
1104         }
1105         if let Some(ty) = ty {
1106             try!(space(&mut self.s));
1107             try!(self.word_space("="));
1108             try!(self.print_type(ty));
1109         }
1110         word(&mut self.s, ";")
1111     }
1112
1113     /// Pretty-print an item
1114     pub fn print_item(&mut self, item: &ast::Item) -> io::Result<()> {
1115         try!(self.hardbreak_if_not_bol());
1116         try!(self.maybe_print_comment(item.span.lo));
1117         try!(self.print_outer_attributes(&item.attrs));
1118         try!(self.ann.pre(self, NodeItem(item)));
1119         match item.node {
1120             ast::ItemKind::ExternCrate(ref optional_path) => {
1121                 try!(self.head(&visibility_qualified(&item.vis, "extern crate")));
1122                 if let Some(p) = *optional_path {
1123                     let val = p.as_str();
1124                     if val.contains("-") {
1125                         try!(self.print_string(&val, ast::StrStyle::Cooked));
1126                     } else {
1127                         try!(self.print_name(p));
1128                     }
1129                     try!(space(&mut self.s));
1130                     try!(word(&mut self.s, "as"));
1131                     try!(space(&mut self.s));
1132                 }
1133                 try!(self.print_ident(item.ident));
1134                 try!(word(&mut self.s, ";"));
1135                 try!(self.end()); // end inner head-block
1136                 try!(self.end()); // end outer head-block
1137             }
1138             ast::ItemKind::Use(ref vp) => {
1139                 try!(self.head(&visibility_qualified(&item.vis, "use")));
1140                 try!(self.print_view_path(&vp));
1141                 try!(word(&mut self.s, ";"));
1142                 try!(self.end()); // end inner head-block
1143                 try!(self.end()); // end outer head-block
1144             }
1145             ast::ItemKind::Static(ref ty, m, ref expr) => {
1146                 try!(self.head(&visibility_qualified(&item.vis, "static")));
1147                 if m == ast::Mutability::Mutable {
1148                     try!(self.word_space("mut"));
1149                 }
1150                 try!(self.print_ident(item.ident));
1151                 try!(self.word_space(":"));
1152                 try!(self.print_type(&ty));
1153                 try!(space(&mut self.s));
1154                 try!(self.end()); // end the head-ibox
1155
1156                 try!(self.word_space("="));
1157                 try!(self.print_expr(&expr));
1158                 try!(word(&mut self.s, ";"));
1159                 try!(self.end()); // end the outer cbox
1160             }
1161             ast::ItemKind::Const(ref ty, ref expr) => {
1162                 try!(self.head(&visibility_qualified(&item.vis, "const")));
1163                 try!(self.print_ident(item.ident));
1164                 try!(self.word_space(":"));
1165                 try!(self.print_type(&ty));
1166                 try!(space(&mut self.s));
1167                 try!(self.end()); // end the head-ibox
1168
1169                 try!(self.word_space("="));
1170                 try!(self.print_expr(&expr));
1171                 try!(word(&mut self.s, ";"));
1172                 try!(self.end()); // end the outer cbox
1173             }
1174             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref typarams, ref body) => {
1175                 try!(self.head(""));
1176                 try!(self.print_fn(
1177                     decl,
1178                     unsafety,
1179                     constness,
1180                     abi,
1181                     Some(item.ident),
1182                     typarams,
1183                     &item.vis
1184                 ));
1185                 try!(word(&mut self.s, " "));
1186                 try!(self.print_block_with_attrs(&body, &item.attrs));
1187             }
1188             ast::ItemKind::Mod(ref _mod) => {
1189                 try!(self.head(&visibility_qualified(&item.vis, "mod")));
1190                 try!(self.print_ident(item.ident));
1191                 try!(self.nbsp());
1192                 try!(self.bopen());
1193                 try!(self.print_mod(_mod, &item.attrs));
1194                 try!(self.bclose(item.span));
1195             }
1196             ast::ItemKind::ForeignMod(ref nmod) => {
1197                 try!(self.head("extern"));
1198                 try!(self.word_nbsp(&nmod.abi.to_string()));
1199                 try!(self.bopen());
1200                 try!(self.print_foreign_mod(nmod, &item.attrs));
1201                 try!(self.bclose(item.span));
1202             }
1203             ast::ItemKind::Ty(ref ty, ref params) => {
1204                 try!(self.ibox(INDENT_UNIT));
1205                 try!(self.ibox(0));
1206                 try!(self.word_nbsp(&visibility_qualified(&item.vis, "type")));
1207                 try!(self.print_ident(item.ident));
1208                 try!(self.print_generics(params));
1209                 try!(self.end()); // end the inner ibox
1210
1211                 try!(self.print_where_clause(&params.where_clause));
1212                 try!(space(&mut self.s));
1213                 try!(self.word_space("="));
1214                 try!(self.print_type(&ty));
1215                 try!(word(&mut self.s, ";"));
1216                 try!(self.end()); // end the outer ibox
1217             }
1218             ast::ItemKind::Enum(ref enum_definition, ref params) => {
1219                 try!(self.print_enum_def(
1220                     enum_definition,
1221                     params,
1222                     item.ident,
1223                     item.span,
1224                     &item.vis
1225                 ));
1226             }
1227             ast::ItemKind::Struct(ref struct_def, ref generics) => {
1228                 try!(self.head(&visibility_qualified(&item.vis, "struct")));
1229                 try!(self.print_struct(&struct_def, generics, item.ident, item.span, true));
1230             }
1231
1232             ast::ItemKind::DefaultImpl(unsafety, ref trait_ref) => {
1233                 try!(self.head(""));
1234                 try!(self.print_visibility(&item.vis));
1235                 try!(self.print_unsafety(unsafety));
1236                 try!(self.word_nbsp("impl"));
1237                 try!(self.print_trait_ref(trait_ref));
1238                 try!(space(&mut self.s));
1239                 try!(self.word_space("for"));
1240                 try!(self.word_space(".."));
1241                 try!(self.bopen());
1242                 try!(self.bclose(item.span));
1243             }
1244             ast::ItemKind::Impl(unsafety,
1245                           polarity,
1246                           ref generics,
1247                           ref opt_trait,
1248                           ref ty,
1249                           ref impl_items) => {
1250                 try!(self.head(""));
1251                 try!(self.print_visibility(&item.vis));
1252                 try!(self.print_unsafety(unsafety));
1253                 try!(self.word_nbsp("impl"));
1254
1255                 if generics.is_parameterized() {
1256                     try!(self.print_generics(generics));
1257                     try!(space(&mut self.s));
1258                 }
1259
1260                 match polarity {
1261                     ast::ImplPolarity::Negative => {
1262                         try!(word(&mut self.s, "!"));
1263                     },
1264                     _ => {}
1265                 }
1266
1267                 if let Some(ref t) = *opt_trait {
1268                     try!(self.print_trait_ref(t));
1269                     try!(space(&mut self.s));
1270                     try!(self.word_space("for"));
1271                 }
1272
1273                 try!(self.print_type(&ty));
1274                 try!(self.print_where_clause(&generics.where_clause));
1275
1276                 try!(space(&mut self.s));
1277                 try!(self.bopen());
1278                 try!(self.print_inner_attributes(&item.attrs));
1279                 for impl_item in impl_items {
1280                     try!(self.print_impl_item(impl_item));
1281                 }
1282                 try!(self.bclose(item.span));
1283             }
1284             ast::ItemKind::Trait(unsafety, ref generics, ref bounds, ref trait_items) => {
1285                 try!(self.head(""));
1286                 try!(self.print_visibility(&item.vis));
1287                 try!(self.print_unsafety(unsafety));
1288                 try!(self.word_nbsp("trait"));
1289                 try!(self.print_ident(item.ident));
1290                 try!(self.print_generics(generics));
1291                 let mut real_bounds = Vec::with_capacity(bounds.len());
1292                 for b in bounds.iter() {
1293                     if let TraitTyParamBound(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
1294                         try!(space(&mut self.s));
1295                         try!(self.word_space("for ?"));
1296                         try!(self.print_trait_ref(&ptr.trait_ref));
1297                     } else {
1298                         real_bounds.push(b.clone());
1299                     }
1300                 }
1301                 try!(self.print_bounds(":", &real_bounds[..]));
1302                 try!(self.print_where_clause(&generics.where_clause));
1303                 try!(word(&mut self.s, " "));
1304                 try!(self.bopen());
1305                 for trait_item in trait_items {
1306                     try!(self.print_trait_item(trait_item));
1307                 }
1308                 try!(self.bclose(item.span));
1309             }
1310             ast::ItemKind::Mac(codemap::Spanned { ref node, .. }) => {
1311                 try!(self.print_visibility(&item.vis));
1312                 try!(self.print_path(&node.path, false, 0));
1313                 try!(word(&mut self.s, "! "));
1314                 try!(self.print_ident(item.ident));
1315                 try!(self.cbox(INDENT_UNIT));
1316                 try!(self.popen());
1317                 try!(self.print_tts(&node.tts[..]));
1318                 try!(self.pclose());
1319                 try!(word(&mut self.s, ";"));
1320                 try!(self.end());
1321             }
1322         }
1323         self.ann.post(self, NodeItem(item))
1324     }
1325
1326     fn print_trait_ref(&mut self, t: &ast::TraitRef) -> io::Result<()> {
1327         self.print_path(&t.path, false, 0)
1328     }
1329
1330     fn print_formal_lifetime_list(&mut self, lifetimes: &[ast::LifetimeDef]) -> io::Result<()> {
1331         if !lifetimes.is_empty() {
1332             try!(word(&mut self.s, "for<"));
1333             let mut comma = false;
1334             for lifetime_def in lifetimes {
1335                 if comma {
1336                     try!(self.word_space(","))
1337                 }
1338                 try!(self.print_lifetime_bounds(&lifetime_def.lifetime, &lifetime_def.bounds));
1339                 comma = true;
1340             }
1341             try!(word(&mut self.s, ">"));
1342         }
1343         Ok(())
1344     }
1345
1346     fn print_poly_trait_ref(&mut self, t: &ast::PolyTraitRef) -> io::Result<()> {
1347         try!(self.print_formal_lifetime_list(&t.bound_lifetimes));
1348         self.print_trait_ref(&t.trait_ref)
1349     }
1350
1351     pub fn print_enum_def(&mut self, enum_definition: &ast::EnumDef,
1352                           generics: &ast::Generics, ident: ast::Ident,
1353                           span: syntax_pos::Span,
1354                           visibility: &ast::Visibility) -> io::Result<()> {
1355         try!(self.head(&visibility_qualified(visibility, "enum")));
1356         try!(self.print_ident(ident));
1357         try!(self.print_generics(generics));
1358         try!(self.print_where_clause(&generics.where_clause));
1359         try!(space(&mut self.s));
1360         self.print_variants(&enum_definition.variants, span)
1361     }
1362
1363     pub fn print_variants(&mut self,
1364                           variants: &[ast::Variant],
1365                           span: syntax_pos::Span) -> io::Result<()> {
1366         try!(self.bopen());
1367         for v in variants {
1368             try!(self.space_if_not_bol());
1369             try!(self.maybe_print_comment(v.span.lo));
1370             try!(self.print_outer_attributes(&v.node.attrs));
1371             try!(self.ibox(INDENT_UNIT));
1372             try!(self.print_variant(v));
1373             try!(word(&mut self.s, ","));
1374             try!(self.end());
1375             try!(self.maybe_print_trailing_comment(v.span, None));
1376         }
1377         self.bclose(span)
1378     }
1379
1380     pub fn print_visibility(&mut self, vis: &ast::Visibility) -> io::Result<()> {
1381         match *vis {
1382             ast::Visibility::Public => self.word_nbsp("pub"),
1383             ast::Visibility::Crate(_) => self.word_nbsp("pub(crate)"),
1384             ast::Visibility::Restricted { ref path, .. } =>
1385                 self.word_nbsp(&format!("pub({})", path)),
1386             ast::Visibility::Inherited => Ok(())
1387         }
1388     }
1389
1390     pub fn print_struct(&mut self,
1391                         struct_def: &ast::VariantData,
1392                         generics: &ast::Generics,
1393                         ident: ast::Ident,
1394                         span: syntax_pos::Span,
1395                         print_finalizer: bool) -> io::Result<()> {
1396         try!(self.print_ident(ident));
1397         try!(self.print_generics(generics));
1398         if !struct_def.is_struct() {
1399             if struct_def.is_tuple() {
1400                 try!(self.popen());
1401                 try!(self.commasep(
1402                     Inconsistent, struct_def.fields(),
1403                     |s, field| {
1404                         try!(s.maybe_print_comment(field.span.lo));
1405                         try!(s.print_outer_attributes(&field.attrs));
1406                         try!(s.print_visibility(&field.vis));
1407                         s.print_type(&field.ty)
1408                     }
1409                 ));
1410                 try!(self.pclose());
1411             }
1412             try!(self.print_where_clause(&generics.where_clause));
1413             if print_finalizer {
1414                 try!(word(&mut self.s, ";"));
1415             }
1416             try!(self.end());
1417             self.end() // close the outer-box
1418         } else {
1419             try!(self.print_where_clause(&generics.where_clause));
1420             try!(self.nbsp());
1421             try!(self.bopen());
1422             try!(self.hardbreak_if_not_bol());
1423
1424             for field in struct_def.fields() {
1425                 try!(self.hardbreak_if_not_bol());
1426                 try!(self.maybe_print_comment(field.span.lo));
1427                 try!(self.print_outer_attributes(&field.attrs));
1428                 try!(self.print_visibility(&field.vis));
1429                 try!(self.print_ident(field.ident.unwrap()));
1430                 try!(self.word_nbsp(":"));
1431                 try!(self.print_type(&field.ty));
1432                 try!(word(&mut self.s, ","));
1433             }
1434
1435             self.bclose(span)
1436         }
1437     }
1438
1439     /// This doesn't deserve to be called "pretty" printing, but it should be
1440     /// meaning-preserving. A quick hack that might help would be to look at the
1441     /// spans embedded in the TTs to decide where to put spaces and newlines.
1442     /// But it'd be better to parse these according to the grammar of the
1443     /// appropriate macro, transcribe back into the grammar we just parsed from,
1444     /// and then pretty-print the resulting AST nodes (so, e.g., we print
1445     /// expression arguments as expressions). It can be done! I think.
1446     pub fn print_tt(&mut self, tt: &tokenstream::TokenTree) -> io::Result<()> {
1447         match *tt {
1448             TokenTree::Token(_, ref tk) => {
1449                 try!(word(&mut self.s, &token_to_string(tk)));
1450                 match *tk {
1451                     parse::token::DocComment(..) => {
1452                         hardbreak(&mut self.s)
1453                     }
1454                     _ => Ok(())
1455                 }
1456             }
1457             TokenTree::Delimited(_, ref delimed) => {
1458                 try!(word(&mut self.s, &token_to_string(&delimed.open_token())));
1459                 try!(space(&mut self.s));
1460                 try!(self.print_tts(&delimed.tts));
1461                 try!(space(&mut self.s));
1462                 word(&mut self.s, &token_to_string(&delimed.close_token()))
1463             },
1464             TokenTree::Sequence(_, ref seq) => {
1465                 try!(word(&mut self.s, "$("));
1466                 for tt_elt in &seq.tts {
1467                     try!(self.print_tt(tt_elt));
1468                 }
1469                 try!(word(&mut self.s, ")"));
1470                 if let Some(ref tk) = seq.separator {
1471                     try!(word(&mut self.s, &token_to_string(tk)));
1472                 }
1473                 match seq.op {
1474                     tokenstream::KleeneOp::ZeroOrMore => word(&mut self.s, "*"),
1475                     tokenstream::KleeneOp::OneOrMore => word(&mut self.s, "+"),
1476                 }
1477             }
1478         }
1479     }
1480
1481     pub fn print_tts(&mut self, tts: &[tokenstream::TokenTree]) -> io::Result<()> {
1482         try!(self.ibox(0));
1483         for (i, tt) in tts.iter().enumerate() {
1484             if i != 0 {
1485                 try!(space(&mut self.s));
1486             }
1487             try!(self.print_tt(tt));
1488         }
1489         self.end()
1490     }
1491
1492     pub fn print_variant(&mut self, v: &ast::Variant) -> io::Result<()> {
1493         try!(self.head(""));
1494         let generics = ast::Generics::default();
1495         try!(self.print_struct(&v.node.data, &generics, v.node.name, v.span, false));
1496         match v.node.disr_expr {
1497             Some(ref d) => {
1498                 try!(space(&mut self.s));
1499                 try!(self.word_space("="));
1500                 self.print_expr(&d)
1501             }
1502             _ => Ok(())
1503         }
1504     }
1505
1506     pub fn print_method_sig(&mut self,
1507                             ident: ast::Ident,
1508                             m: &ast::MethodSig,
1509                             vis: &ast::Visibility)
1510                             -> io::Result<()> {
1511         self.print_fn(&m.decl,
1512                       m.unsafety,
1513                       m.constness,
1514                       m.abi,
1515                       Some(ident),
1516                       &m.generics,
1517                       vis)
1518     }
1519
1520     pub fn print_trait_item(&mut self, ti: &ast::TraitItem)
1521                             -> io::Result<()> {
1522         try!(self.ann.pre(self, NodeSubItem(ti.id)));
1523         try!(self.hardbreak_if_not_bol());
1524         try!(self.maybe_print_comment(ti.span.lo));
1525         try!(self.print_outer_attributes(&ti.attrs));
1526         match ti.node {
1527             ast::TraitItemKind::Const(ref ty, ref default) => {
1528                 try!(self.print_associated_const(ti.ident, &ty,
1529                                             default.as_ref().map(|expr| &**expr),
1530                                             &ast::Visibility::Inherited));
1531             }
1532             ast::TraitItemKind::Method(ref sig, ref body) => {
1533                 if body.is_some() {
1534                     try!(self.head(""));
1535                 }
1536                 try!(self.print_method_sig(ti.ident, sig, &ast::Visibility::Inherited));
1537                 if let Some(ref body) = *body {
1538                     try!(self.nbsp());
1539                     try!(self.print_block_with_attrs(body, &ti.attrs));
1540                 } else {
1541                     try!(word(&mut self.s, ";"));
1542                 }
1543             }
1544             ast::TraitItemKind::Type(ref bounds, ref default) => {
1545                 try!(self.print_associated_type(ti.ident, Some(bounds),
1546                                            default.as_ref().map(|ty| &**ty)));
1547             }
1548             ast::TraitItemKind::Macro(codemap::Spanned { ref node, .. }) => {
1549                 // code copied from ItemKind::Mac:
1550                 self.print_path(&node.path, false, 0)?;
1551                 word(&mut self.s, "! ")?;
1552                 self.cbox(INDENT_UNIT)?;
1553                 self.popen()?;
1554                 self.print_tts(&node.tts[..])?;
1555                 self.pclose()?;
1556                 word(&mut self.s, ";")?;
1557                 self.end()?
1558             }
1559         }
1560         self.ann.post(self, NodeSubItem(ti.id))
1561     }
1562
1563     pub fn print_impl_item(&mut self, ii: &ast::ImplItem) -> io::Result<()> {
1564         try!(self.ann.pre(self, NodeSubItem(ii.id)));
1565         try!(self.hardbreak_if_not_bol());
1566         try!(self.maybe_print_comment(ii.span.lo));
1567         try!(self.print_outer_attributes(&ii.attrs));
1568         if let ast::Defaultness::Default = ii.defaultness {
1569             try!(self.word_nbsp("default"));
1570         }
1571         match ii.node {
1572             ast::ImplItemKind::Const(ref ty, ref expr) => {
1573                 try!(self.print_associated_const(ii.ident, &ty, Some(&expr), &ii.vis));
1574             }
1575             ast::ImplItemKind::Method(ref sig, ref body) => {
1576                 try!(self.head(""));
1577                 try!(self.print_method_sig(ii.ident, sig, &ii.vis));
1578                 try!(self.nbsp());
1579                 try!(self.print_block_with_attrs(body, &ii.attrs));
1580             }
1581             ast::ImplItemKind::Type(ref ty) => {
1582                 try!(self.print_associated_type(ii.ident, None, Some(ty)));
1583             }
1584             ast::ImplItemKind::Macro(codemap::Spanned { ref node, .. }) => {
1585                 // code copied from ItemKind::Mac:
1586                 try!(self.print_path(&node.path, false, 0));
1587                 try!(word(&mut self.s, "! "));
1588                 try!(self.cbox(INDENT_UNIT));
1589                 try!(self.popen());
1590                 try!(self.print_tts(&node.tts[..]));
1591                 try!(self.pclose());
1592                 try!(word(&mut self.s, ";"));
1593                 try!(self.end())
1594             }
1595         }
1596         self.ann.post(self, NodeSubItem(ii.id))
1597     }
1598
1599     pub fn print_stmt(&mut self, st: &ast::Stmt) -> io::Result<()> {
1600         try!(self.maybe_print_comment(st.span.lo));
1601         match st.node {
1602             ast::StmtKind::Local(ref loc) => {
1603                 try!(self.print_outer_attributes(&loc.attrs));
1604                 try!(self.space_if_not_bol());
1605                 try!(self.ibox(INDENT_UNIT));
1606                 try!(self.word_nbsp("let"));
1607
1608                 try!(self.ibox(INDENT_UNIT));
1609                 try!(self.print_local_decl(&loc));
1610                 try!(self.end());
1611                 if let Some(ref init) = loc.init {
1612                     try!(self.nbsp());
1613                     try!(self.word_space("="));
1614                     try!(self.print_expr(&init));
1615                 }
1616                 try!(word(&mut self.s, ";"));
1617                 self.end()?;
1618             }
1619             ast::StmtKind::Item(ref item) => self.print_item(&item)?,
1620             ast::StmtKind::Expr(ref expr) => {
1621                 try!(self.space_if_not_bol());
1622                 try!(self.print_expr_outer_attr_style(&expr, false));
1623                 if parse::classify::expr_requires_semi_to_be_stmt(expr) {
1624                     try!(word(&mut self.s, ";"));
1625                 }
1626             }
1627             ast::StmtKind::Semi(ref expr) => {
1628                 try!(self.space_if_not_bol());
1629                 try!(self.print_expr_outer_attr_style(&expr, false));
1630                 try!(word(&mut self.s, ";"));
1631             }
1632             ast::StmtKind::Mac(ref mac) => {
1633                 let (ref mac, style, ref attrs) = **mac;
1634                 try!(self.space_if_not_bol());
1635                 try!(self.print_outer_attributes(&attrs));
1636                 let delim = match style {
1637                     ast::MacStmtStyle::Braces => token::Brace,
1638                     _ => token::Paren
1639                 };
1640                 try!(self.print_mac(&mac, delim));
1641                 match style {
1642                     ast::MacStmtStyle::Braces => {}
1643                     _ => try!(word(&mut self.s, ";")),
1644                 }
1645             }
1646         }
1647         self.maybe_print_trailing_comment(st.span, None)
1648     }
1649
1650     pub fn print_block(&mut self, blk: &ast::Block) -> io::Result<()> {
1651         self.print_block_with_attrs(blk, &[])
1652     }
1653
1654     pub fn print_block_unclosed(&mut self, blk: &ast::Block) -> io::Result<()> {
1655         self.print_block_unclosed_indent(blk, INDENT_UNIT)
1656     }
1657
1658     pub fn print_block_unclosed_with_attrs(&mut self, blk: &ast::Block,
1659                                             attrs: &[ast::Attribute])
1660                                            -> io::Result<()> {
1661         self.print_block_maybe_unclosed(blk, INDENT_UNIT, attrs, false)
1662     }
1663
1664     pub fn print_block_unclosed_indent(&mut self, blk: &ast::Block,
1665                                        indented: usize) -> io::Result<()> {
1666         self.print_block_maybe_unclosed(blk, indented, &[], false)
1667     }
1668
1669     pub fn print_block_with_attrs(&mut self,
1670                                   blk: &ast::Block,
1671                                   attrs: &[ast::Attribute]) -> io::Result<()> {
1672         self.print_block_maybe_unclosed(blk, INDENT_UNIT, attrs, true)
1673     }
1674
1675     pub fn print_block_maybe_unclosed(&mut self,
1676                                       blk: &ast::Block,
1677                                       indented: usize,
1678                                       attrs: &[ast::Attribute],
1679                                       close_box: bool) -> io::Result<()> {
1680         match blk.rules {
1681             BlockCheckMode::Unsafe(..) => try!(self.word_space("unsafe")),
1682             BlockCheckMode::Default => ()
1683         }
1684         try!(self.maybe_print_comment(blk.span.lo));
1685         try!(self.ann.pre(self, NodeBlock(blk)));
1686         try!(self.bopen());
1687
1688         try!(self.print_inner_attributes(attrs));
1689
1690         for (i, st) in blk.stmts.iter().enumerate() {
1691             match st.node {
1692                 ast::StmtKind::Expr(ref expr) if i == blk.stmts.len() - 1 => {
1693                     try!(self.space_if_not_bol());
1694                     try!(self.print_expr_outer_attr_style(&expr, false));
1695                     try!(self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi)));
1696                 }
1697                 _ => try!(self.print_stmt(st)),
1698             }
1699         }
1700
1701         try!(self.bclose_maybe_open(blk.span, indented, close_box));
1702         self.ann.post(self, NodeBlock(blk))
1703     }
1704
1705     fn print_else(&mut self, els: Option<&ast::Expr>) -> io::Result<()> {
1706         match els {
1707             Some(_else) => {
1708                 match _else.node {
1709                     // "another else-if"
1710                     ast::ExprKind::If(ref i, ref then, ref e) => {
1711                         try!(self.cbox(INDENT_UNIT - 1));
1712                         try!(self.ibox(0));
1713                         try!(word(&mut self.s, " else if "));
1714                         try!(self.print_expr(&i));
1715                         try!(space(&mut self.s));
1716                         try!(self.print_block(&then));
1717                         self.print_else(e.as_ref().map(|e| &**e))
1718                     }
1719                     // "another else-if-let"
1720                     ast::ExprKind::IfLet(ref pat, ref expr, ref then, ref e) => {
1721                         try!(self.cbox(INDENT_UNIT - 1));
1722                         try!(self.ibox(0));
1723                         try!(word(&mut self.s, " else if let "));
1724                         try!(self.print_pat(&pat));
1725                         try!(space(&mut self.s));
1726                         try!(self.word_space("="));
1727                         try!(self.print_expr(&expr));
1728                         try!(space(&mut self.s));
1729                         try!(self.print_block(&then));
1730                         self.print_else(e.as_ref().map(|e| &**e))
1731                     }
1732                     // "final else"
1733                     ast::ExprKind::Block(ref b) => {
1734                         try!(self.cbox(INDENT_UNIT - 1));
1735                         try!(self.ibox(0));
1736                         try!(word(&mut self.s, " else "));
1737                         self.print_block(&b)
1738                     }
1739                     // BLEAH, constraints would be great here
1740                     _ => {
1741                         panic!("print_if saw if with weird alternative");
1742                     }
1743                 }
1744             }
1745             _ => Ok(())
1746         }
1747     }
1748
1749     pub fn print_if(&mut self, test: &ast::Expr, blk: &ast::Block,
1750                     elseopt: Option<&ast::Expr>) -> io::Result<()> {
1751         try!(self.head("if"));
1752         try!(self.print_expr(test));
1753         try!(space(&mut self.s));
1754         try!(self.print_block(blk));
1755         self.print_else(elseopt)
1756     }
1757
1758     pub fn print_if_let(&mut self, pat: &ast::Pat, expr: &ast::Expr, blk: &ast::Block,
1759                         elseopt: Option<&ast::Expr>) -> io::Result<()> {
1760         try!(self.head("if let"));
1761         try!(self.print_pat(pat));
1762         try!(space(&mut self.s));
1763         try!(self.word_space("="));
1764         try!(self.print_expr(expr));
1765         try!(space(&mut self.s));
1766         try!(self.print_block(blk));
1767         self.print_else(elseopt)
1768     }
1769
1770     pub fn print_mac(&mut self, m: &ast::Mac, delim: token::DelimToken)
1771                      -> io::Result<()> {
1772         try!(self.print_path(&m.node.path, false, 0));
1773         try!(word(&mut self.s, "!"));
1774         match delim {
1775             token::Paren => try!(self.popen()),
1776             token::Bracket => try!(word(&mut self.s, "[")),
1777             token::Brace => {
1778                 try!(self.head(""));
1779                 try!(self.bopen());
1780             }
1781         }
1782         try!(self.print_tts(&m.node.tts));
1783         match delim {
1784             token::Paren => self.pclose(),
1785             token::Bracket => word(&mut self.s, "]"),
1786             token::Brace => self.bclose(m.span),
1787         }
1788     }
1789
1790
1791     fn print_call_post(&mut self, args: &[P<ast::Expr>]) -> io::Result<()> {
1792         try!(self.popen());
1793         try!(self.commasep_exprs(Inconsistent, args));
1794         self.pclose()
1795     }
1796
1797     pub fn check_expr_bin_needs_paren(&mut self, sub_expr: &ast::Expr,
1798                                       binop: ast::BinOp) -> bool {
1799         match sub_expr.node {
1800             ast::ExprKind::Binary(ref sub_op, _, _) => {
1801                 if AssocOp::from_ast_binop(sub_op.node).precedence() <
1802                     AssocOp::from_ast_binop(binop.node).precedence() {
1803                     true
1804                 } else {
1805                     false
1806                 }
1807             }
1808             _ => true
1809         }
1810     }
1811
1812     pub fn print_expr_maybe_paren(&mut self, expr: &ast::Expr) -> io::Result<()> {
1813         let needs_par = needs_parentheses(expr);
1814         if needs_par {
1815             try!(self.popen());
1816         }
1817         try!(self.print_expr(expr));
1818         if needs_par {
1819             try!(self.pclose());
1820         }
1821         Ok(())
1822     }
1823
1824     fn print_expr_in_place(&mut self,
1825                            place: &ast::Expr,
1826                            expr: &ast::Expr) -> io::Result<()> {
1827         try!(self.print_expr_maybe_paren(place));
1828         try!(space(&mut self.s));
1829         try!(self.word_space("<-"));
1830         self.print_expr_maybe_paren(expr)
1831     }
1832
1833     fn print_expr_vec(&mut self, exprs: &[P<ast::Expr>],
1834                       attrs: &[Attribute]) -> io::Result<()> {
1835         try!(self.ibox(INDENT_UNIT));
1836         try!(word(&mut self.s, "["));
1837         try!(self.print_inner_attributes_inline(attrs));
1838         try!(self.commasep_exprs(Inconsistent, &exprs[..]));
1839         try!(word(&mut self.s, "]"));
1840         self.end()
1841     }
1842
1843     fn print_expr_repeat(&mut self,
1844                          element: &ast::Expr,
1845                          count: &ast::Expr,
1846                          attrs: &[Attribute]) -> io::Result<()> {
1847         try!(self.ibox(INDENT_UNIT));
1848         try!(word(&mut self.s, "["));
1849         try!(self.print_inner_attributes_inline(attrs));
1850         try!(self.print_expr(element));
1851         try!(self.word_space(";"));
1852         try!(self.print_expr(count));
1853         try!(word(&mut self.s, "]"));
1854         self.end()
1855     }
1856
1857     fn print_expr_struct(&mut self,
1858                          path: &ast::Path,
1859                          fields: &[ast::Field],
1860                          wth: &Option<P<ast::Expr>>,
1861                          attrs: &[Attribute]) -> io::Result<()> {
1862         try!(self.print_path(path, true, 0));
1863         try!(word(&mut self.s, "{"));
1864         try!(self.print_inner_attributes_inline(attrs));
1865         try!(self.commasep_cmnt(
1866             Consistent,
1867             &fields[..],
1868             |s, field| {
1869                 try!(s.ibox(INDENT_UNIT));
1870                 try!(s.print_ident(field.ident.node));
1871                 try!(s.word_space(":"));
1872                 try!(s.print_expr(&field.expr));
1873                 s.end()
1874             },
1875             |f| f.span));
1876         match *wth {
1877             Some(ref expr) => {
1878                 try!(self.ibox(INDENT_UNIT));
1879                 if !fields.is_empty() {
1880                     try!(word(&mut self.s, ","));
1881                     try!(space(&mut self.s));
1882                 }
1883                 try!(word(&mut self.s, ".."));
1884                 try!(self.print_expr(&expr));
1885                 try!(self.end());
1886             }
1887             _ => if !fields.is_empty() {
1888                 try!(word(&mut self.s, ","))
1889             }
1890         }
1891         try!(word(&mut self.s, "}"));
1892         Ok(())
1893     }
1894
1895     fn print_expr_tup(&mut self, exprs: &[P<ast::Expr>],
1896                       attrs: &[Attribute]) -> io::Result<()> {
1897         try!(self.popen());
1898         try!(self.print_inner_attributes_inline(attrs));
1899         try!(self.commasep_exprs(Inconsistent, &exprs[..]));
1900         if exprs.len() == 1 {
1901             try!(word(&mut self.s, ","));
1902         }
1903         self.pclose()
1904     }
1905
1906     fn print_expr_call(&mut self,
1907                        func: &ast::Expr,
1908                        args: &[P<ast::Expr>]) -> io::Result<()> {
1909         try!(self.print_expr_maybe_paren(func));
1910         self.print_call_post(args)
1911     }
1912
1913     fn print_expr_method_call(&mut self,
1914                               ident: ast::SpannedIdent,
1915                               tys: &[P<ast::Ty>],
1916                               args: &[P<ast::Expr>]) -> io::Result<()> {
1917         let base_args = &args[1..];
1918         try!(self.print_expr(&args[0]));
1919         try!(word(&mut self.s, "."));
1920         try!(self.print_ident(ident.node));
1921         if !tys.is_empty() {
1922             try!(word(&mut self.s, "::<"));
1923             try!(self.commasep(Inconsistent, tys,
1924                           |s, ty| s.print_type(&ty)));
1925             try!(word(&mut self.s, ">"));
1926         }
1927         self.print_call_post(base_args)
1928     }
1929
1930     fn print_expr_binary(&mut self,
1931                          op: ast::BinOp,
1932                          lhs: &ast::Expr,
1933                          rhs: &ast::Expr) -> io::Result<()> {
1934         if self.check_expr_bin_needs_paren(lhs, op) {
1935             try!(self.print_expr_maybe_paren(lhs));
1936         } else {
1937             try!(self.print_expr(lhs));
1938         }
1939         try!(space(&mut self.s));
1940         try!(self.word_space(op.node.to_string()));
1941         if self.check_expr_bin_needs_paren(rhs, op) {
1942             self.print_expr_maybe_paren(rhs)
1943         } else {
1944             self.print_expr(rhs)
1945         }
1946     }
1947
1948     fn print_expr_unary(&mut self,
1949                         op: ast::UnOp,
1950                         expr: &ast::Expr) -> io::Result<()> {
1951         try!(word(&mut self.s, ast::UnOp::to_string(op)));
1952         self.print_expr_maybe_paren(expr)
1953     }
1954
1955     fn print_expr_addr_of(&mut self,
1956                           mutability: ast::Mutability,
1957                           expr: &ast::Expr) -> io::Result<()> {
1958         try!(word(&mut self.s, "&"));
1959         try!(self.print_mutability(mutability));
1960         self.print_expr_maybe_paren(expr)
1961     }
1962
1963     pub fn print_expr(&mut self, expr: &ast::Expr) -> io::Result<()> {
1964         self.print_expr_outer_attr_style(expr, true)
1965     }
1966
1967     fn print_expr_outer_attr_style(&mut self,
1968                                   expr: &ast::Expr,
1969                                   is_inline: bool) -> io::Result<()> {
1970         try!(self.maybe_print_comment(expr.span.lo));
1971
1972         let attrs = &expr.attrs;
1973         if is_inline {
1974             try!(self.print_outer_attributes_inline(attrs));
1975         } else {
1976             try!(self.print_outer_attributes(attrs));
1977         }
1978
1979         try!(self.ibox(INDENT_UNIT));
1980         try!(self.ann.pre(self, NodeExpr(expr)));
1981         match expr.node {
1982             ast::ExprKind::Box(ref expr) => {
1983                 try!(self.word_space("box"));
1984                 try!(self.print_expr(expr));
1985             }
1986             ast::ExprKind::InPlace(ref place, ref expr) => {
1987                 try!(self.print_expr_in_place(place, expr));
1988             }
1989             ast::ExprKind::Vec(ref exprs) => {
1990                 try!(self.print_expr_vec(&exprs[..], attrs));
1991             }
1992             ast::ExprKind::Repeat(ref element, ref count) => {
1993                 try!(self.print_expr_repeat(&element, &count, attrs));
1994             }
1995             ast::ExprKind::Struct(ref path, ref fields, ref wth) => {
1996                 try!(self.print_expr_struct(path, &fields[..], wth, attrs));
1997             }
1998             ast::ExprKind::Tup(ref exprs) => {
1999                 try!(self.print_expr_tup(&exprs[..], attrs));
2000             }
2001             ast::ExprKind::Call(ref func, ref args) => {
2002                 try!(self.print_expr_call(&func, &args[..]));
2003             }
2004             ast::ExprKind::MethodCall(ident, ref tys, ref args) => {
2005                 try!(self.print_expr_method_call(ident, &tys[..], &args[..]));
2006             }
2007             ast::ExprKind::Binary(op, ref lhs, ref rhs) => {
2008                 try!(self.print_expr_binary(op, &lhs, &rhs));
2009             }
2010             ast::ExprKind::Unary(op, ref expr) => {
2011                 try!(self.print_expr_unary(op, &expr));
2012             }
2013             ast::ExprKind::AddrOf(m, ref expr) => {
2014                 try!(self.print_expr_addr_of(m, &expr));
2015             }
2016             ast::ExprKind::Lit(ref lit) => {
2017                 try!(self.print_literal(&lit));
2018             }
2019             ast::ExprKind::Cast(ref expr, ref ty) => {
2020                 if let ast::ExprKind::Cast(..) = expr.node {
2021                     try!(self.print_expr(&expr));
2022                 } else {
2023                     try!(self.print_expr_maybe_paren(&expr));
2024                 }
2025                 try!(space(&mut self.s));
2026                 try!(self.word_space("as"));
2027                 try!(self.print_type(&ty));
2028             }
2029             ast::ExprKind::Type(ref expr, ref ty) => {
2030                 try!(self.print_expr(&expr));
2031                 try!(self.word_space(":"));
2032                 try!(self.print_type(&ty));
2033             }
2034             ast::ExprKind::If(ref test, ref blk, ref elseopt) => {
2035                 try!(self.print_if(&test, &blk, elseopt.as_ref().map(|e| &**e)));
2036             }
2037             ast::ExprKind::IfLet(ref pat, ref expr, ref blk, ref elseopt) => {
2038                 try!(self.print_if_let(&pat, &expr, &blk, elseopt.as_ref().map(|e| &**e)));
2039             }
2040             ast::ExprKind::While(ref test, ref blk, opt_ident) => {
2041                 if let Some(ident) = opt_ident {
2042                     try!(self.print_ident(ident.node));
2043                     try!(self.word_space(":"));
2044                 }
2045                 try!(self.head("while"));
2046                 try!(self.print_expr(&test));
2047                 try!(space(&mut self.s));
2048                 try!(self.print_block_with_attrs(&blk, attrs));
2049             }
2050             ast::ExprKind::WhileLet(ref pat, ref expr, ref blk, opt_ident) => {
2051                 if let Some(ident) = opt_ident {
2052                     try!(self.print_ident(ident.node));
2053                     try!(self.word_space(":"));
2054                 }
2055                 try!(self.head("while let"));
2056                 try!(self.print_pat(&pat));
2057                 try!(space(&mut self.s));
2058                 try!(self.word_space("="));
2059                 try!(self.print_expr(&expr));
2060                 try!(space(&mut self.s));
2061                 try!(self.print_block_with_attrs(&blk, attrs));
2062             }
2063             ast::ExprKind::ForLoop(ref pat, ref iter, ref blk, opt_ident) => {
2064                 if let Some(ident) = opt_ident {
2065                     try!(self.print_ident(ident.node));
2066                     try!(self.word_space(":"));
2067                 }
2068                 try!(self.head("for"));
2069                 try!(self.print_pat(&pat));
2070                 try!(space(&mut self.s));
2071                 try!(self.word_space("in"));
2072                 try!(self.print_expr(&iter));
2073                 try!(space(&mut self.s));
2074                 try!(self.print_block_with_attrs(&blk, attrs));
2075             }
2076             ast::ExprKind::Loop(ref blk, opt_ident) => {
2077                 if let Some(ident) = opt_ident {
2078                     try!(self.print_ident(ident.node));
2079                     try!(self.word_space(":"));
2080                 }
2081                 try!(self.head("loop"));
2082                 try!(space(&mut self.s));
2083                 try!(self.print_block_with_attrs(&blk, attrs));
2084             }
2085             ast::ExprKind::Match(ref expr, ref arms) => {
2086                 try!(self.cbox(INDENT_UNIT));
2087                 try!(self.ibox(4));
2088                 try!(self.word_nbsp("match"));
2089                 try!(self.print_expr(&expr));
2090                 try!(space(&mut self.s));
2091                 try!(self.bopen());
2092                 try!(self.print_inner_attributes_no_trailing_hardbreak(attrs));
2093                 for arm in arms {
2094                     try!(self.print_arm(arm));
2095                 }
2096                 try!(self.bclose_(expr.span, INDENT_UNIT));
2097             }
2098             ast::ExprKind::Closure(capture_clause, ref decl, ref body, _) => {
2099                 try!(self.print_capture_clause(capture_clause));
2100
2101                 try!(self.print_fn_block_args(&decl));
2102                 try!(space(&mut self.s));
2103
2104                 let default_return = match decl.output {
2105                     ast::FunctionRetTy::Default(..) => true,
2106                     _ => false
2107                 };
2108
2109                 match body.stmts.last().map(|stmt| &stmt.node) {
2110                     Some(&ast::StmtKind::Expr(ref i_expr)) if default_return &&
2111                                                               body.stmts.len() == 1 => {
2112                         // we extract the block, so as not to create another set of boxes
2113                         if let ast::ExprKind::Block(ref blk) = i_expr.node {
2114                             try!(self.print_block_unclosed_with_attrs(&blk, &i_expr.attrs));
2115                         } else {
2116                             // this is a bare expression
2117                             try!(self.print_expr(&i_expr));
2118                             try!(self.end()); // need to close a box
2119                         }
2120                     }
2121                     _ => try!(self.print_block_unclosed(&body)),
2122                 }
2123
2124                 // a box will be closed by print_expr, but we didn't want an overall
2125                 // wrapper so we closed the corresponding opening. so create an
2126                 // empty box to satisfy the close.
2127                 try!(self.ibox(0));
2128             }
2129             ast::ExprKind::Block(ref blk) => {
2130                 // containing cbox, will be closed by print-block at }
2131                 try!(self.cbox(INDENT_UNIT));
2132                 // head-box, will be closed by print-block after {
2133                 try!(self.ibox(0));
2134                 try!(self.print_block_with_attrs(&blk, attrs));
2135             }
2136             ast::ExprKind::Assign(ref lhs, ref rhs) => {
2137                 try!(self.print_expr(&lhs));
2138                 try!(space(&mut self.s));
2139                 try!(self.word_space("="));
2140                 try!(self.print_expr(&rhs));
2141             }
2142             ast::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
2143                 try!(self.print_expr(&lhs));
2144                 try!(space(&mut self.s));
2145                 try!(word(&mut self.s, op.node.to_string()));
2146                 try!(self.word_space("="));
2147                 try!(self.print_expr(&rhs));
2148             }
2149             ast::ExprKind::Field(ref expr, id) => {
2150                 try!(self.print_expr(&expr));
2151                 try!(word(&mut self.s, "."));
2152                 try!(self.print_ident(id.node));
2153             }
2154             ast::ExprKind::TupField(ref expr, id) => {
2155                 try!(self.print_expr(&expr));
2156                 try!(word(&mut self.s, "."));
2157                 try!(self.print_usize(id.node));
2158             }
2159             ast::ExprKind::Index(ref expr, ref index) => {
2160                 try!(self.print_expr(&expr));
2161                 try!(word(&mut self.s, "["));
2162                 try!(self.print_expr(&index));
2163                 try!(word(&mut self.s, "]"));
2164             }
2165             ast::ExprKind::Range(ref start, ref end, limits) => {
2166                 if let &Some(ref e) = start {
2167                     try!(self.print_expr(&e));
2168                 }
2169                 if limits == ast::RangeLimits::HalfOpen {
2170                     try!(word(&mut self.s, ".."));
2171                 } else {
2172                     try!(word(&mut self.s, "..."));
2173                 }
2174                 if let &Some(ref e) = end {
2175                     try!(self.print_expr(&e));
2176                 }
2177             }
2178             ast::ExprKind::Path(None, ref path) => {
2179                 try!(self.print_path(path, true, 0))
2180             }
2181             ast::ExprKind::Path(Some(ref qself), ref path) => {
2182                 try!(self.print_qpath(path, qself, true))
2183             }
2184             ast::ExprKind::Break(opt_ident) => {
2185                 try!(word(&mut self.s, "break"));
2186                 try!(space(&mut self.s));
2187                 if let Some(ident) = opt_ident {
2188                     try!(self.print_ident(ident.node));
2189                     try!(space(&mut self.s));
2190                 }
2191             }
2192             ast::ExprKind::Continue(opt_ident) => {
2193                 try!(word(&mut self.s, "continue"));
2194                 try!(space(&mut self.s));
2195                 if let Some(ident) = opt_ident {
2196                     try!(self.print_ident(ident.node));
2197                     try!(space(&mut self.s))
2198                 }
2199             }
2200             ast::ExprKind::Ret(ref result) => {
2201                 try!(word(&mut self.s, "return"));
2202                 match *result {
2203                     Some(ref expr) => {
2204                         try!(word(&mut self.s, " "));
2205                         try!(self.print_expr(&expr));
2206                     }
2207                     _ => ()
2208                 }
2209             }
2210             ast::ExprKind::InlineAsm(ref a) => {
2211                 try!(word(&mut self.s, "asm!"));
2212                 try!(self.popen());
2213                 try!(self.print_string(&a.asm, a.asm_str_style));
2214                 try!(self.word_space(":"));
2215
2216                 try!(self.commasep(Inconsistent, &a.outputs,
2217                                    |s, out| {
2218                     let mut ch = out.constraint.chars();
2219                     match ch.next() {
2220                         Some('=') if out.is_rw => {
2221                             try!(s.print_string(&format!("+{}", ch.as_str()),
2222                                            ast::StrStyle::Cooked))
2223                         }
2224                         _ => try!(s.print_string(&out.constraint,
2225                                             ast::StrStyle::Cooked))
2226                     }
2227                     try!(s.popen());
2228                     try!(s.print_expr(&out.expr));
2229                     try!(s.pclose());
2230                     Ok(())
2231                 }));
2232                 try!(space(&mut self.s));
2233                 try!(self.word_space(":"));
2234
2235                 try!(self.commasep(Inconsistent, &a.inputs,
2236                                    |s, &(ref co, ref o)| {
2237                     try!(s.print_string(&co, ast::StrStyle::Cooked));
2238                     try!(s.popen());
2239                     try!(s.print_expr(&o));
2240                     try!(s.pclose());
2241                     Ok(())
2242                 }));
2243                 try!(space(&mut self.s));
2244                 try!(self.word_space(":"));
2245
2246                 try!(self.commasep(Inconsistent, &a.clobbers,
2247                                    |s, co| {
2248                     try!(s.print_string(&co, ast::StrStyle::Cooked));
2249                     Ok(())
2250                 }));
2251
2252                 let mut options = vec!();
2253                 if a.volatile {
2254                     options.push("volatile");
2255                 }
2256                 if a.alignstack {
2257                     options.push("alignstack");
2258                 }
2259                 if a.dialect == ast::AsmDialect::Intel {
2260                     options.push("intel");
2261                 }
2262
2263                 if !options.is_empty() {
2264                     try!(space(&mut self.s));
2265                     try!(self.word_space(":"));
2266                     try!(self.commasep(Inconsistent, &options,
2267                                   |s, &co| {
2268                                       try!(s.print_string(co, ast::StrStyle::Cooked));
2269                                       Ok(())
2270                                   }));
2271                 }
2272
2273                 try!(self.pclose());
2274             }
2275             ast::ExprKind::Mac(ref m) => try!(self.print_mac(m, token::Paren)),
2276             ast::ExprKind::Paren(ref e) => {
2277                 try!(self.popen());
2278                 try!(self.print_inner_attributes_inline(attrs));
2279                 try!(self.print_expr(&e));
2280                 try!(self.pclose());
2281             },
2282             ast::ExprKind::Try(ref e) => {
2283                 try!(self.print_expr(e));
2284                 try!(word(&mut self.s, "?"))
2285             }
2286         }
2287         try!(self.ann.post(self, NodeExpr(expr)));
2288         self.end()
2289     }
2290
2291     pub fn print_local_decl(&mut self, loc: &ast::Local) -> io::Result<()> {
2292         try!(self.print_pat(&loc.pat));
2293         if let Some(ref ty) = loc.ty {
2294             try!(self.word_space(":"));
2295             try!(self.print_type(&ty));
2296         }
2297         Ok(())
2298     }
2299
2300     pub fn print_ident(&mut self, ident: ast::Ident) -> io::Result<()> {
2301         try!(word(&mut self.s, &ident.name.as_str()));
2302         self.ann.post(self, NodeIdent(&ident))
2303     }
2304
2305     pub fn print_usize(&mut self, i: usize) -> io::Result<()> {
2306         word(&mut self.s, &i.to_string())
2307     }
2308
2309     pub fn print_name(&mut self, name: ast::Name) -> io::Result<()> {
2310         try!(word(&mut self.s, &name.as_str()));
2311         self.ann.post(self, NodeName(&name))
2312     }
2313
2314     pub fn print_for_decl(&mut self, loc: &ast::Local,
2315                           coll: &ast::Expr) -> io::Result<()> {
2316         try!(self.print_local_decl(loc));
2317         try!(space(&mut self.s));
2318         try!(self.word_space("in"));
2319         self.print_expr(coll)
2320     }
2321
2322     fn print_path(&mut self,
2323                   path: &ast::Path,
2324                   colons_before_params: bool,
2325                   depth: usize)
2326                   -> io::Result<()>
2327     {
2328         try!(self.maybe_print_comment(path.span.lo));
2329
2330         let mut first = !path.global;
2331         for segment in &path.segments[..path.segments.len()-depth] {
2332             if first {
2333                 first = false
2334             } else {
2335                 try!(word(&mut self.s, "::"))
2336             }
2337
2338             try!(self.print_ident(segment.identifier));
2339
2340             try!(self.print_path_parameters(&segment.parameters, colons_before_params));
2341         }
2342
2343         Ok(())
2344     }
2345
2346     fn print_qpath(&mut self,
2347                    path: &ast::Path,
2348                    qself: &ast::QSelf,
2349                    colons_before_params: bool)
2350                    -> io::Result<()>
2351     {
2352         try!(word(&mut self.s, "<"));
2353         try!(self.print_type(&qself.ty));
2354         if qself.position > 0 {
2355             try!(space(&mut self.s));
2356             try!(self.word_space("as"));
2357             let depth = path.segments.len() - qself.position;
2358             try!(self.print_path(&path, false, depth));
2359         }
2360         try!(word(&mut self.s, ">"));
2361         try!(word(&mut self.s, "::"));
2362         let item_segment = path.segments.last().unwrap();
2363         try!(self.print_ident(item_segment.identifier));
2364         self.print_path_parameters(&item_segment.parameters, colons_before_params)
2365     }
2366
2367     fn print_path_parameters(&mut self,
2368                              parameters: &ast::PathParameters,
2369                              colons_before_params: bool)
2370                              -> io::Result<()>
2371     {
2372         if parameters.is_empty() {
2373             return Ok(());
2374         }
2375
2376         if colons_before_params {
2377             try!(word(&mut self.s, "::"))
2378         }
2379
2380         match *parameters {
2381             ast::PathParameters::AngleBracketed(ref data) => {
2382                 try!(word(&mut self.s, "<"));
2383
2384                 let mut comma = false;
2385                 for lifetime in &data.lifetimes {
2386                     if comma {
2387                         try!(self.word_space(","))
2388                     }
2389                     try!(self.print_lifetime(lifetime));
2390                     comma = true;
2391                 }
2392
2393                 if !data.types.is_empty() {
2394                     if comma {
2395                         try!(self.word_space(","))
2396                     }
2397                     try!(self.commasep(
2398                         Inconsistent,
2399                         &data.types,
2400                         |s, ty| s.print_type(&ty)));
2401                         comma = true;
2402                 }
2403
2404                 for binding in data.bindings.iter() {
2405                     if comma {
2406                         try!(self.word_space(","))
2407                     }
2408                     try!(self.print_ident(binding.ident));
2409                     try!(space(&mut self.s));
2410                     try!(self.word_space("="));
2411                     try!(self.print_type(&binding.ty));
2412                     comma = true;
2413                 }
2414
2415                 try!(word(&mut self.s, ">"))
2416             }
2417
2418             ast::PathParameters::Parenthesized(ref data) => {
2419                 try!(word(&mut self.s, "("));
2420                 try!(self.commasep(
2421                     Inconsistent,
2422                     &data.inputs,
2423                     |s, ty| s.print_type(&ty)));
2424                 try!(word(&mut self.s, ")"));
2425
2426                 match data.output {
2427                     None => { }
2428                     Some(ref ty) => {
2429                         try!(self.space_if_not_bol());
2430                         try!(self.word_space("->"));
2431                         try!(self.print_type(&ty));
2432                     }
2433                 }
2434             }
2435         }
2436
2437         Ok(())
2438     }
2439
2440     pub fn print_pat(&mut self, pat: &ast::Pat) -> io::Result<()> {
2441         try!(self.maybe_print_comment(pat.span.lo));
2442         try!(self.ann.pre(self, NodePat(pat)));
2443         /* Pat isn't normalized, but the beauty of it
2444          is that it doesn't matter */
2445         match pat.node {
2446             PatKind::Wild => try!(word(&mut self.s, "_")),
2447             PatKind::Ident(binding_mode, ref path1, ref sub) => {
2448                 match binding_mode {
2449                     ast::BindingMode::ByRef(mutbl) => {
2450                         try!(self.word_nbsp("ref"));
2451                         try!(self.print_mutability(mutbl));
2452                     }
2453                     ast::BindingMode::ByValue(ast::Mutability::Immutable) => {}
2454                     ast::BindingMode::ByValue(ast::Mutability::Mutable) => {
2455                         try!(self.word_nbsp("mut"));
2456                     }
2457                 }
2458                 try!(self.print_ident(path1.node));
2459                 if let Some(ref p) = *sub {
2460                     try!(word(&mut self.s, "@"));
2461                     try!(self.print_pat(&p));
2462                 }
2463             }
2464             PatKind::TupleStruct(ref path, ref elts, ddpos) => {
2465                 try!(self.print_path(path, true, 0));
2466                 try!(self.popen());
2467                 if let Some(ddpos) = ddpos {
2468                     try!(self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p)));
2469                     if ddpos != 0 {
2470                         try!(self.word_space(","));
2471                     }
2472                     try!(word(&mut self.s, ".."));
2473                     if ddpos != elts.len() {
2474                         try!(word(&mut self.s, ","));
2475                         try!(self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p)));
2476                     }
2477                 } else {
2478                     try!(self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p)));
2479                 }
2480                 try!(self.pclose());
2481             }
2482             PatKind::Path(None, ref path) => {
2483                 try!(self.print_path(path, true, 0));
2484             }
2485             PatKind::Path(Some(ref qself), ref path) => {
2486                 try!(self.print_qpath(path, qself, false));
2487             }
2488             PatKind::Struct(ref path, ref fields, etc) => {
2489                 try!(self.print_path(path, true, 0));
2490                 try!(self.nbsp());
2491                 try!(self.word_space("{"));
2492                 try!(self.commasep_cmnt(
2493                     Consistent, &fields[..],
2494                     |s, f| {
2495                         try!(s.cbox(INDENT_UNIT));
2496                         if !f.node.is_shorthand {
2497                             try!(s.print_ident(f.node.ident));
2498                             try!(s.word_nbsp(":"));
2499                         }
2500                         try!(s.print_pat(&f.node.pat));
2501                         s.end()
2502                     },
2503                     |f| f.node.pat.span));
2504                 if etc {
2505                     if !fields.is_empty() { try!(self.word_space(",")); }
2506                     try!(word(&mut self.s, ".."));
2507                 }
2508                 try!(space(&mut self.s));
2509                 try!(word(&mut self.s, "}"));
2510             }
2511             PatKind::Tuple(ref elts, ddpos) => {
2512                 try!(self.popen());
2513                 if let Some(ddpos) = ddpos {
2514                     try!(self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p)));
2515                     if ddpos != 0 {
2516                         try!(self.word_space(","));
2517                     }
2518                     try!(word(&mut self.s, ".."));
2519                     if ddpos != elts.len() {
2520                         try!(word(&mut self.s, ","));
2521                         try!(self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p)));
2522                     }
2523                 } else {
2524                     try!(self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p)));
2525                     if elts.len() == 1 {
2526                         try!(word(&mut self.s, ","));
2527                     }
2528                 }
2529                 try!(self.pclose());
2530             }
2531             PatKind::Box(ref inner) => {
2532                 try!(word(&mut self.s, "box "));
2533                 try!(self.print_pat(&inner));
2534             }
2535             PatKind::Ref(ref inner, mutbl) => {
2536                 try!(word(&mut self.s, "&"));
2537                 if mutbl == ast::Mutability::Mutable {
2538                     try!(word(&mut self.s, "mut "));
2539                 }
2540                 try!(self.print_pat(&inner));
2541             }
2542             PatKind::Lit(ref e) => try!(self.print_expr(&**e)),
2543             PatKind::Range(ref begin, ref end) => {
2544                 try!(self.print_expr(&begin));
2545                 try!(space(&mut self.s));
2546                 try!(word(&mut self.s, "..."));
2547                 try!(self.print_expr(&end));
2548             }
2549             PatKind::Vec(ref before, ref slice, ref after) => {
2550                 try!(word(&mut self.s, "["));
2551                 try!(self.commasep(Inconsistent,
2552                                    &before[..],
2553                                    |s, p| s.print_pat(&p)));
2554                 if let Some(ref p) = *slice {
2555                     if !before.is_empty() { try!(self.word_space(",")); }
2556                     if p.node != PatKind::Wild {
2557                         try!(self.print_pat(&p));
2558                     }
2559                     try!(word(&mut self.s, ".."));
2560                     if !after.is_empty() { try!(self.word_space(",")); }
2561                 }
2562                 try!(self.commasep(Inconsistent,
2563                                    &after[..],
2564                                    |s, p| s.print_pat(&p)));
2565                 try!(word(&mut self.s, "]"));
2566             }
2567             PatKind::Mac(ref m) => try!(self.print_mac(m, token::Paren)),
2568         }
2569         self.ann.post(self, NodePat(pat))
2570     }
2571
2572     fn print_arm(&mut self, arm: &ast::Arm) -> io::Result<()> {
2573         // I have no idea why this check is necessary, but here it
2574         // is :(
2575         if arm.attrs.is_empty() {
2576             try!(space(&mut self.s));
2577         }
2578         try!(self.cbox(INDENT_UNIT));
2579         try!(self.ibox(0));
2580         try!(self.print_outer_attributes(&arm.attrs));
2581         let mut first = true;
2582         for p in &arm.pats {
2583             if first {
2584                 first = false;
2585             } else {
2586                 try!(space(&mut self.s));
2587                 try!(self.word_space("|"));
2588             }
2589             try!(self.print_pat(&p));
2590         }
2591         try!(space(&mut self.s));
2592         if let Some(ref e) = arm.guard {
2593             try!(self.word_space("if"));
2594             try!(self.print_expr(&e));
2595             try!(space(&mut self.s));
2596         }
2597         try!(self.word_space("=>"));
2598
2599         match arm.body.node {
2600             ast::ExprKind::Block(ref blk) => {
2601                 // the block will close the pattern's ibox
2602                 try!(self.print_block_unclosed_indent(&blk, INDENT_UNIT));
2603
2604                 // If it is a user-provided unsafe block, print a comma after it
2605                 if let BlockCheckMode::Unsafe(ast::UserProvided) = blk.rules {
2606                     try!(word(&mut self.s, ","));
2607                 }
2608             }
2609             _ => {
2610                 try!(self.end()); // close the ibox for the pattern
2611                 try!(self.print_expr(&arm.body));
2612                 try!(word(&mut self.s, ","));
2613             }
2614         }
2615         self.end() // close enclosing cbox
2616     }
2617
2618     fn print_explicit_self(&mut self, explicit_self: &ast::ExplicitSelf) -> io::Result<()> {
2619         match explicit_self.node {
2620             SelfKind::Value(m) => {
2621                 try!(self.print_mutability(m));
2622                 word(&mut self.s, "self")
2623             }
2624             SelfKind::Region(ref lt, m) => {
2625                 try!(word(&mut self.s, "&"));
2626                 try!(self.print_opt_lifetime(lt));
2627                 try!(self.print_mutability(m));
2628                 word(&mut self.s, "self")
2629             }
2630             SelfKind::Explicit(ref typ, m) => {
2631                 try!(self.print_mutability(m));
2632                 try!(word(&mut self.s, "self"));
2633                 try!(self.word_space(":"));
2634                 self.print_type(&typ)
2635             }
2636         }
2637     }
2638
2639     pub fn print_fn(&mut self,
2640                     decl: &ast::FnDecl,
2641                     unsafety: ast::Unsafety,
2642                     constness: ast::Constness,
2643                     abi: abi::Abi,
2644                     name: Option<ast::Ident>,
2645                     generics: &ast::Generics,
2646                     vis: &ast::Visibility) -> io::Result<()> {
2647         try!(self.print_fn_header_info(unsafety, constness, abi, vis));
2648
2649         if let Some(name) = name {
2650             try!(self.nbsp());
2651             try!(self.print_ident(name));
2652         }
2653         try!(self.print_generics(generics));
2654         try!(self.print_fn_args_and_ret(decl));
2655         self.print_where_clause(&generics.where_clause)
2656     }
2657
2658     pub fn print_fn_args_and_ret(&mut self, decl: &ast::FnDecl)
2659         -> io::Result<()> {
2660         try!(self.popen());
2661         try!(self.commasep(Inconsistent, &decl.inputs, |s, arg| s.print_arg(arg, false)));
2662         if decl.variadic {
2663             try!(word(&mut self.s, ", ..."));
2664         }
2665         try!(self.pclose());
2666
2667         self.print_fn_output(decl)
2668     }
2669
2670     pub fn print_fn_block_args(
2671             &mut self,
2672             decl: &ast::FnDecl)
2673             -> io::Result<()> {
2674         try!(word(&mut self.s, "|"));
2675         try!(self.commasep(Inconsistent, &decl.inputs, |s, arg| s.print_arg(arg, true)));
2676         try!(word(&mut self.s, "|"));
2677
2678         if let ast::FunctionRetTy::Default(..) = decl.output {
2679             return Ok(());
2680         }
2681
2682         try!(self.space_if_not_bol());
2683         try!(self.word_space("->"));
2684         match decl.output {
2685             ast::FunctionRetTy::Ty(ref ty) => {
2686                 try!(self.print_type(&ty));
2687                 self.maybe_print_comment(ty.span.lo)
2688             }
2689             ast::FunctionRetTy::Default(..) => unreachable!(),
2690             ast::FunctionRetTy::None(span) => {
2691                 try!(self.word_nbsp("!"));
2692                 self.maybe_print_comment(span.lo)
2693             }
2694         }
2695     }
2696
2697     pub fn print_capture_clause(&mut self, capture_clause: ast::CaptureBy)
2698                                 -> io::Result<()> {
2699         match capture_clause {
2700             ast::CaptureBy::Value => self.word_space("move"),
2701             ast::CaptureBy::Ref => Ok(()),
2702         }
2703     }
2704
2705     pub fn print_bounds(&mut self,
2706                         prefix: &str,
2707                         bounds: &[ast::TyParamBound])
2708                         -> io::Result<()> {
2709         if !bounds.is_empty() {
2710             try!(word(&mut self.s, prefix));
2711             let mut first = true;
2712             for bound in bounds {
2713                 try!(self.nbsp());
2714                 if first {
2715                     first = false;
2716                 } else {
2717                     try!(self.word_space("+"));
2718                 }
2719
2720                 try!(match *bound {
2721                     TraitTyParamBound(ref tref, TraitBoundModifier::None) => {
2722                         self.print_poly_trait_ref(tref)
2723                     }
2724                     TraitTyParamBound(ref tref, TraitBoundModifier::Maybe) => {
2725                         try!(word(&mut self.s, "?"));
2726                         self.print_poly_trait_ref(tref)
2727                     }
2728                     RegionTyParamBound(ref lt) => {
2729                         self.print_lifetime(lt)
2730                     }
2731                 })
2732             }
2733             Ok(())
2734         } else {
2735             Ok(())
2736         }
2737     }
2738
2739     pub fn print_lifetime(&mut self,
2740                           lifetime: &ast::Lifetime)
2741                           -> io::Result<()>
2742     {
2743         self.print_name(lifetime.name)
2744     }
2745
2746     pub fn print_lifetime_bounds(&mut self,
2747                                  lifetime: &ast::Lifetime,
2748                                  bounds: &[ast::Lifetime])
2749                                  -> io::Result<()>
2750     {
2751         try!(self.print_lifetime(lifetime));
2752         if !bounds.is_empty() {
2753             try!(word(&mut self.s, ": "));
2754             for (i, bound) in bounds.iter().enumerate() {
2755                 if i != 0 {
2756                     try!(word(&mut self.s, " + "));
2757                 }
2758                 try!(self.print_lifetime(bound));
2759             }
2760         }
2761         Ok(())
2762     }
2763
2764     pub fn print_generics(&mut self,
2765                           generics: &ast::Generics)
2766                           -> io::Result<()>
2767     {
2768         let total = generics.lifetimes.len() + generics.ty_params.len();
2769         if total == 0 {
2770             return Ok(());
2771         }
2772
2773         try!(word(&mut self.s, "<"));
2774
2775         let mut ints = Vec::new();
2776         for i in 0..total {
2777             ints.push(i);
2778         }
2779
2780         try!(self.commasep(Inconsistent, &ints[..], |s, &idx| {
2781             if idx < generics.lifetimes.len() {
2782                 let lifetime_def = &generics.lifetimes[idx];
2783                 s.print_lifetime_bounds(&lifetime_def.lifetime, &lifetime_def.bounds)
2784             } else {
2785                 let idx = idx - generics.lifetimes.len();
2786                 let param = &generics.ty_params[idx];
2787                 s.print_ty_param(param)
2788             }
2789         }));
2790
2791         try!(word(&mut self.s, ">"));
2792         Ok(())
2793     }
2794
2795     pub fn print_ty_param(&mut self, param: &ast::TyParam) -> io::Result<()> {
2796         try!(self.print_ident(param.ident));
2797         try!(self.print_bounds(":", &param.bounds));
2798         match param.default {
2799             Some(ref default) => {
2800                 try!(space(&mut self.s));
2801                 try!(self.word_space("="));
2802                 self.print_type(&default)
2803             }
2804             _ => Ok(())
2805         }
2806     }
2807
2808     pub fn print_where_clause(&mut self, where_clause: &ast::WhereClause)
2809                               -> io::Result<()> {
2810         if where_clause.predicates.is_empty() {
2811             return Ok(())
2812         }
2813
2814         try!(space(&mut self.s));
2815         try!(self.word_space("where"));
2816
2817         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2818             if i != 0 {
2819                 try!(self.word_space(","));
2820             }
2821
2822             match *predicate {
2823                 ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate{ref bound_lifetimes,
2824                                                                              ref bounded_ty,
2825                                                                              ref bounds,
2826                                                                              ..}) => {
2827                     try!(self.print_formal_lifetime_list(bound_lifetimes));
2828                     try!(self.print_type(&bounded_ty));
2829                     try!(self.print_bounds(":", bounds));
2830                 }
2831                 ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate{ref lifetime,
2832                                                                                ref bounds,
2833                                                                                ..}) => {
2834                     try!(self.print_lifetime_bounds(lifetime, bounds));
2835                 }
2836                 ast::WherePredicate::EqPredicate(ast::WhereEqPredicate{ref path, ref ty, ..}) => {
2837                     try!(self.print_path(path, false, 0));
2838                     try!(space(&mut self.s));
2839                     try!(self.word_space("="));
2840                     try!(self.print_type(&ty));
2841                 }
2842             }
2843         }
2844
2845         Ok(())
2846     }
2847
2848     pub fn print_view_path(&mut self, vp: &ast::ViewPath) -> io::Result<()> {
2849         match vp.node {
2850             ast::ViewPathSimple(ident, ref path) => {
2851                 try!(self.print_path(path, false, 0));
2852
2853                 if path.segments.last().unwrap().identifier.name !=
2854                         ident.name {
2855                     try!(space(&mut self.s));
2856                     try!(self.word_space("as"));
2857                     try!(self.print_ident(ident));
2858                 }
2859
2860                 Ok(())
2861             }
2862
2863             ast::ViewPathGlob(ref path) => {
2864                 try!(self.print_path(path, false, 0));
2865                 word(&mut self.s, "::*")
2866             }
2867
2868             ast::ViewPathList(ref path, ref idents) => {
2869                 if path.segments.is_empty() {
2870                     try!(word(&mut self.s, "{"));
2871                 } else {
2872                     try!(self.print_path(path, false, 0));
2873                     try!(word(&mut self.s, "::{"));
2874                 }
2875                 try!(self.commasep(Inconsistent, &idents[..], |s, w| {
2876                     match w.node {
2877                         ast::PathListItemKind::Ident { name, rename, .. } => {
2878                             try!(s.print_ident(name));
2879                             if let Some(ident) = rename {
2880                                 try!(space(&mut s.s));
2881                                 try!(s.word_space("as"));
2882                                 try!(s.print_ident(ident));
2883                             }
2884                             Ok(())
2885                         },
2886                         ast::PathListItemKind::Mod { rename, .. } => {
2887                             try!(word(&mut s.s, "self"));
2888                             if let Some(ident) = rename {
2889                                 try!(space(&mut s.s));
2890                                 try!(s.word_space("as"));
2891                                 try!(s.print_ident(ident));
2892                             }
2893                             Ok(())
2894                         }
2895                     }
2896                 }));
2897                 word(&mut self.s, "}")
2898             }
2899         }
2900     }
2901
2902     pub fn print_mutability(&mut self,
2903                             mutbl: ast::Mutability) -> io::Result<()> {
2904         match mutbl {
2905             ast::Mutability::Mutable => self.word_nbsp("mut"),
2906             ast::Mutability::Immutable => Ok(()),
2907         }
2908     }
2909
2910     pub fn print_mt(&mut self, mt: &ast::MutTy) -> io::Result<()> {
2911         try!(self.print_mutability(mt.mutbl));
2912         self.print_type(&mt.ty)
2913     }
2914
2915     pub fn print_arg(&mut self, input: &ast::Arg, is_closure: bool) -> io::Result<()> {
2916         try!(self.ibox(INDENT_UNIT));
2917         match input.ty.node {
2918             ast::TyKind::Infer if is_closure => try!(self.print_pat(&input.pat)),
2919             _ => {
2920                 if let Some(eself) = input.to_self() {
2921                     try!(self.print_explicit_self(&eself));
2922                 } else {
2923                     let invalid = if let PatKind::Ident(_, ident, _) = input.pat.node {
2924                         ident.node.name == keywords::Invalid.name()
2925                     } else {
2926                         false
2927                     };
2928                     if !invalid {
2929                         try!(self.print_pat(&input.pat));
2930                         try!(word(&mut self.s, ":"));
2931                         try!(space(&mut self.s));
2932                     }
2933                     try!(self.print_type(&input.ty));
2934                 }
2935             }
2936         }
2937         self.end()
2938     }
2939
2940     pub fn print_fn_output(&mut self, decl: &ast::FnDecl) -> io::Result<()> {
2941         if let ast::FunctionRetTy::Default(..) = decl.output {
2942             return Ok(());
2943         }
2944
2945         try!(self.space_if_not_bol());
2946         try!(self.ibox(INDENT_UNIT));
2947         try!(self.word_space("->"));
2948         match decl.output {
2949             ast::FunctionRetTy::None(_) =>
2950                 try!(self.word_nbsp("!")),
2951             ast::FunctionRetTy::Default(..) => unreachable!(),
2952             ast::FunctionRetTy::Ty(ref ty) =>
2953                 try!(self.print_type(&ty))
2954         }
2955         try!(self.end());
2956
2957         match decl.output {
2958             ast::FunctionRetTy::Ty(ref output) => self.maybe_print_comment(output.span.lo),
2959             _ => Ok(())
2960         }
2961     }
2962
2963     pub fn print_ty_fn(&mut self,
2964                        abi: abi::Abi,
2965                        unsafety: ast::Unsafety,
2966                        decl: &ast::FnDecl,
2967                        name: Option<ast::Ident>,
2968                        generics: &ast::Generics)
2969                        -> io::Result<()> {
2970         try!(self.ibox(INDENT_UNIT));
2971         if !generics.lifetimes.is_empty() || !generics.ty_params.is_empty() {
2972             try!(word(&mut self.s, "for"));
2973             try!(self.print_generics(generics));
2974         }
2975         let generics = ast::Generics {
2976             lifetimes: Vec::new(),
2977             ty_params: P::new(),
2978             where_clause: ast::WhereClause {
2979                 id: ast::DUMMY_NODE_ID,
2980                 predicates: Vec::new(),
2981             },
2982         };
2983         try!(self.print_fn(decl,
2984                       unsafety,
2985                       ast::Constness::NotConst,
2986                       abi,
2987                       name,
2988                       &generics,
2989                       &ast::Visibility::Inherited));
2990         self.end()
2991     }
2992
2993     pub fn maybe_print_trailing_comment(&mut self, span: syntax_pos::Span,
2994                                         next_pos: Option<BytePos>)
2995         -> io::Result<()> {
2996         let cm = match self.cm {
2997             Some(cm) => cm,
2998             _ => return Ok(())
2999         };
3000         if let Some(ref cmnt) = self.next_comment() {
3001             if (*cmnt).style != comments::Trailing { return Ok(()) }
3002             let span_line = cm.lookup_char_pos(span.hi);
3003             let comment_line = cm.lookup_char_pos((*cmnt).pos);
3004             let mut next = (*cmnt).pos + BytePos(1);
3005             if let Some(p) = next_pos {
3006                 next = p;
3007             }
3008             if span.hi < (*cmnt).pos && (*cmnt).pos < next &&
3009                span_line.line == comment_line.line {
3010                 self.print_comment(cmnt)?;
3011                 self.cur_cmnt_and_lit.cur_cmnt += 1;
3012             }
3013         }
3014         Ok(())
3015     }
3016
3017     pub fn print_remaining_comments(&mut self) -> io::Result<()> {
3018         // If there aren't any remaining comments, then we need to manually
3019         // make sure there is a line break at the end.
3020         if self.next_comment().is_none() {
3021             try!(hardbreak(&mut self.s));
3022         }
3023         loop {
3024             match self.next_comment() {
3025                 Some(ref cmnt) => {
3026                     try!(self.print_comment(cmnt));
3027                     self.cur_cmnt_and_lit.cur_cmnt += 1;
3028                 }
3029                 _ => break
3030             }
3031         }
3032         Ok(())
3033     }
3034
3035     pub fn print_opt_abi_and_extern_if_nondefault(&mut self,
3036                                                   opt_abi: Option<Abi>)
3037         -> io::Result<()> {
3038         match opt_abi {
3039             Some(Abi::Rust) => Ok(()),
3040             Some(abi) => {
3041                 try!(self.word_nbsp("extern"));
3042                 self.word_nbsp(&abi.to_string())
3043             }
3044             None => Ok(())
3045         }
3046     }
3047
3048     pub fn print_extern_opt_abi(&mut self,
3049                                 opt_abi: Option<Abi>) -> io::Result<()> {
3050         match opt_abi {
3051             Some(abi) => {
3052                 try!(self.word_nbsp("extern"));
3053                 self.word_nbsp(&abi.to_string())
3054             }
3055             None => Ok(())
3056         }
3057     }
3058
3059     pub fn print_fn_header_info(&mut self,
3060                                 unsafety: ast::Unsafety,
3061                                 constness: ast::Constness,
3062                                 abi: Abi,
3063                                 vis: &ast::Visibility) -> io::Result<()> {
3064         try!(word(&mut self.s, &visibility_qualified(vis, "")));
3065
3066         match constness {
3067             ast::Constness::NotConst => {}
3068             ast::Constness::Const => try!(self.word_nbsp("const"))
3069         }
3070
3071         try!(self.print_unsafety(unsafety));
3072
3073         if abi != Abi::Rust {
3074             try!(self.word_nbsp("extern"));
3075             try!(self.word_nbsp(&abi.to_string()));
3076         }
3077
3078         word(&mut self.s, "fn")
3079     }
3080
3081     pub fn print_unsafety(&mut self, s: ast::Unsafety) -> io::Result<()> {
3082         match s {
3083             ast::Unsafety::Normal => Ok(()),
3084             ast::Unsafety::Unsafe => self.word_nbsp("unsafe"),
3085         }
3086     }
3087 }
3088
3089 fn repeat(s: &str, n: usize) -> String { iter::repeat(s).take(n).collect() }
3090
3091 #[cfg(test)]
3092 mod tests {
3093     use super::*;
3094
3095     use ast;
3096     use codemap;
3097     use parse::token;
3098     use syntax_pos;
3099
3100     #[test]
3101     fn test_fun_to_string() {
3102         let abba_ident = token::str_to_ident("abba");
3103
3104         let decl = ast::FnDecl {
3105             inputs: Vec::new(),
3106             output: ast::FunctionRetTy::Default(syntax_pos::DUMMY_SP),
3107             variadic: false
3108         };
3109         let generics = ast::Generics::default();
3110         assert_eq!(fun_to_string(&decl, ast::Unsafety::Normal,
3111                                  ast::Constness::NotConst,
3112                                  abba_ident, &generics),
3113                    "fn abba()");
3114     }
3115
3116     #[test]
3117     fn test_variant_to_string() {
3118         let ident = token::str_to_ident("principal_skinner");
3119
3120         let var = codemap::respan(syntax_pos::DUMMY_SP, ast::Variant_ {
3121             name: ident,
3122             attrs: Vec::new(),
3123             // making this up as I go.... ?
3124             data: ast::VariantData::Unit(ast::DUMMY_NODE_ID),
3125             disr_expr: None,
3126         });
3127
3128         let varstr = variant_to_string(&var);
3129         assert_eq!(varstr, "principal_skinner");
3130     }
3131 }