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;
  14 use ast;
  15 use ast::{RegionTyParamBound, TraitTyParamBound, TraitBoundModifier};
  16 use ast_util;
  17 use attr;
  18 use owned_slice::OwnedSlice;
  19 use attr::{AttrMetaMethods, AttributeMethods};
  20 use codemap::{self, CodeMap, BytePos};
  21 use diagnostic;
  22 use parse::token::{self, BinOpToken, Token, InternedString};
  23 use parse::lexer::comments;
  24 use parse;
  25 use print::pp::{self, break_offset, word, space, zerobreak, hardbreak};
  26 use print::pp::{Breaks, eof};
  27 use print::pp::Breaks::{Consistent, Inconsistent};
  28 use ptr::P;
  29 use std_inject;
  30
  31 use std::ascii;
  32 use std::io::{self, Write, Read};
  33 use std::iter;
  34
  35 pub enum AnnNode<'a> {
  36     NodeIdent(&'a ast::Ident),
  37     NodeName(&'a ast::Name),
  38     NodeBlock(&'a ast::Block),
  39     NodeItem(&'a ast::Item),
  40     NodeSubItem(ast::NodeId),
  41     NodeExpr(&'a ast::Expr),
  42     NodePat(&'a ast::Pat),
  43 }
  44
  45 pub trait PpAnn {
  46     fn pre(&self, _state: &mut State, _node: AnnNode) -> io::Result<()> { Ok(()) }
  47     fn post(&self, _state: &mut State, _node: AnnNode) -> io::Result<()> { Ok(()) }
  48 }
  49
  50 #[derive(Copy, Clone)]
  51 pub struct NoAnn;
  52
  53 impl PpAnn for NoAnn {}
  54
  55 #[derive(Copy, Clone)]
  56 pub struct CurrentCommentAndLiteral {
  57     pub cur_cmnt: usize,
  58     pub cur_lit: usize,
  59 }
  60
  61 pub struct State<'a> {
  62     pub s: pp::Printer<'a>,
  63     cm: Option<&'a CodeMap>,
  64     comments: Option<Vec<comments::Comment> >,
  65     literals: Option<Vec<comments::Literal> >,
  66     cur_cmnt_and_lit: CurrentCommentAndLiteral,
  67     boxes: Vec<pp::Breaks>,
  68     ann: &'a (PpAnn+'a),
  69 }
  70
  71 pub fn rust_printer<'a>(writer: Box<Write+'a>) -> State<'a> {
  72     static NO_ANN: NoAnn = NoAnn;
  73     rust_printer_annotated(writer, &NO_ANN)
  74 }
  75
  76 pub fn rust_printer_annotated<'a>(writer: Box<Write+'a>,
  77                                   ann: &'a PpAnn) -> State<'a> {
  78     State {
  79         s: pp::mk_printer(writer, default_columns),
  80         cm: None,
  81         comments: None,
  82         literals: None,
  83         cur_cmnt_and_lit: CurrentCommentAndLiteral {
  84             cur_cmnt: 0,
  85             cur_lit: 0
  86         },
  87         boxes: Vec::new(),
  88         ann: ann,
  89     }
  90 }
  91
  92 #[allow(non_upper_case_globals)]
  93 pub const indent_unit: usize = 4;
  94
  95 #[allow(non_upper_case_globals)]
  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: &diagnostic::SpanHandler,
 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         let no_std_meta = attr::mk_word_item(InternedString::new("no_std"));
 123         let prelude_import_meta = attr::mk_word_item(InternedString::new("prelude_import"));
 124
 125         // #![feature(no_std)]
 126         let fake_attr = attr::mk_attr_inner(attr::mk_attr_id(),
 127                                             attr::mk_list_item(InternedString::new("feature"),
 128                                                                vec![no_std_meta.clone(),
 129                                                                     prelude_import_meta]));
 130         try!(s.print_attribute(&fake_attr));
 131
 132         // #![no_std]
 133         let fake_attr = attr::mk_attr_inner(attr::mk_attr_id(), no_std_meta);
 134         try!(s.print_attribute(&fake_attr));
 135     }
 136
 137     try!(s.print_mod(&krate.module, &krate.attrs));
 138     try!(s.print_remaining_comments());
 139     eof(&mut s.s)
 140 }
 141
 142 impl<'a> State<'a> {
 143     pub fn new_from_input(cm: &'a CodeMap,
 144                           span_diagnostic: &diagnostic::SpanHandler,
 145                           filename: String,
 146                           input: &mut Read,
 147                           out: Box<Write+'a>,
 148                           ann: &'a PpAnn,
 149                           is_expanded: bool) -> State<'a> {
 150         let (cmnts, lits) = comments::gather_comments_and_literals(
 151             span_diagnostic,
 152             filename,
 153             input);
 154
 155         State::new(
 156             cm,
 157             out,
 158             ann,
 159             Some(cmnts),
 160             // If the code is post expansion, don't use the table of
 161             // literals, since it doesn't correspond with the literals
 162             // in the AST anymore.
 163             if is_expanded { None } else { Some(lits) })
 164     }
 165
 166     pub fn new(cm: &'a CodeMap,
 167                out: Box<Write+'a>,
 168                ann: &'a PpAnn,
 169                comments: Option<Vec<comments::Comment>>,
 170                literals: Option<Vec<comments::Literal>>) -> State<'a> {
 171         State {
 172             s: pp::mk_printer(out, default_columns),
 173             cm: Some(cm),
 174             comments: comments,
 175             literals: literals,
 176             cur_cmnt_and_lit: CurrentCommentAndLiteral {
 177                 cur_cmnt: 0,
 178                 cur_lit: 0
 179             },
 180             boxes: Vec::new(),
 181             ann: ann,
 182         }
 183     }
 184 }
 185
 186 pub fn to_string<F>(f: F) -> String where
 187     F: FnOnce(&mut State) -> io::Result<()>,
 188 {
 189     let mut wr = Vec::new();
 190     {
 191         let mut printer = rust_printer(Box::new(&mut wr));
 192         f(&mut printer).unwrap();
 193         eof(&mut printer.s).unwrap();
 194     }
 195     String::from_utf8(wr).unwrap()
 196 }
 197
 198 pub fn binop_to_string(op: BinOpToken) -> &'static str {
 199     match op {
 200         token::Plus     => "+",
 201         token::Minus    => "-",
 202         token::Star     => "*",
 203         token::Slash    => "/",
 204         token::Percent  => "%",
 205         token::Caret    => "^",
 206         token::And      => "&",
 207         token::Or       => "|",
 208         token::Shl      => "<<",
 209         token::Shr      => ">>",
 210     }
 211 }
 212
 213 pub fn token_to_string(tok: &Token) -> String {
 214     match *tok {
 215         token::Eq                   => "=".to_string(),
 216         token::Lt                   => "<".to_string(),
 217         token::Le                   => "<=".to_string(),
 218         token::EqEq                 => "==".to_string(),
 219         token::Ne                   => "!=".to_string(),
 220         token::Ge                   => ">=".to_string(),
 221         token::Gt                   => ">".to_string(),
 222         token::Not                  => "!".to_string(),
 223         token::Tilde                => "~".to_string(),
 224         token::OrOr                 => "||".to_string(),
 225         token::AndAnd               => "&&".to_string(),
 226         token::BinOp(op)            => binop_to_string(op).to_string(),
 227         token::BinOpEq(op)          => format!("{}=", binop_to_string(op)),
 228
 229         /* Structural symbols */
 230         token::At                   => "@".to_string(),
 231         token::Dot                  => ".".to_string(),
 232         token::DotDot               => "..".to_string(),
 233         token::DotDotDot            => "...".to_string(),
 234         token::Comma                => ",".to_string(),
 235         token::Semi                 => ";".to_string(),
 236         token::Colon                => ":".to_string(),
 237         token::ModSep               => "::".to_string(),
 238         token::RArrow               => "->".to_string(),
 239         token::LArrow               => "<-".to_string(),
 240         token::FatArrow             => "=>".to_string(),
 241         token::OpenDelim(token::Paren) => "(".to_string(),
 242         token::CloseDelim(token::Paren) => ")".to_string(),
 243         token::OpenDelim(token::Bracket) => "[".to_string(),
 244         token::CloseDelim(token::Bracket) => "]".to_string(),
 245         token::OpenDelim(token::Brace) => "{".to_string(),
 246         token::CloseDelim(token::Brace) => "}".to_string(),
 247         token::Pound                => "#".to_string(),
 248         token::Dollar               => "$".to_string(),
 249         token::Question             => "?".to_string(),
 250
 251         /* Literals */
 252         token::Literal(lit, suf) => {
 253             let mut out = match lit {
 254                 token::Byte(b)           => format!("b'{}'", b),
 255                 token::Char(c)           => format!("'{}'", c),
 256                 token::Float(c)          => c.to_string(),
 257                 token::Integer(c)        => c.to_string(),
 258                 token::Str_(s)           => format!("\"{}\"", s),
 259                 token::StrRaw(s, n)      => format!("r{delim}\"{string}\"{delim}",
 260                                                     delim=repeat("#", n),
 261                                                     string=s),
 262                 token::ByteStr(v)         => format!("b\"{}\"", v),
 263                 token::ByteStrRaw(s, n)   => format!("br{delim}\"{string}\"{delim}",
 264                                                     delim=repeat("#", n),
 265                                                     string=s),
 266             };
 267
 268             if let Some(s) = suf {
 269                 out.push_str(&s.as_str())
 270             }
 271
 272             out
 273         }
 274
 275         /* Name components */
 276         token::Ident(s, _)          => s.to_string(),
 277         token::Lifetime(s)          => s.to_string(),
 278         token::Underscore           => "_".to_string(),
 279
 280         /* Other */
 281         token::DocComment(s)        => s.to_string(),
 282         token::SubstNt(s, _)        => format!("${}", s),
 283         token::MatchNt(s, t, _, _)  => format!("${}:{}", s, t),
 284         token::Eof                  => "<eof>".to_string(),
 285         token::Whitespace           => " ".to_string(),
 286         token::Comment              => "/* */".to_string(),
 287         token::Shebang(s)           => format!("/* shebang: {}*/", s),
 288
 289         token::SpecialVarNt(var)    => format!("${}", var.as_str()),
 290
 291         token::Interpolated(ref nt) => match *nt {
 292             token::NtExpr(ref e)        => expr_to_string(&**e),
 293             token::NtMeta(ref e)        => meta_item_to_string(&**e),
 294             token::NtTy(ref e)          => ty_to_string(&**e),
 295             token::NtPath(ref e)        => path_to_string(&**e),
 296             token::NtItem(ref e)        => item_to_string(&**e),
 297             token::NtBlock(ref e)       => block_to_string(&**e),
 298             token::NtStmt(ref e)        => stmt_to_string(&**e),
 299             token::NtPat(ref e)         => pat_to_string(&**e),
 300             token::NtIdent(ref e, _)    => ident_to_string(&**e),
 301             token::NtTT(ref e)          => tt_to_string(&**e),
 302             token::NtArm(ref e)         => arm_to_string(&*e),
 303             token::NtImplItem(ref e)    => impl_item_to_string(&**e),
 304             token::NtTraitItem(ref e)   => trait_item_to_string(&**e),
 305             token::NtGenerics(ref e)    => generics_to_string(&*e),
 306             token::NtWhereClause(ref e) => where_clause_to_string(&*e),
 307         }
 308     }
 309 }
 310
 311 pub fn ty_to_string(ty: &ast::Ty) -> String {
 312     to_string(|s| s.print_type(ty))
 313 }
 314
 315 pub fn bounds_to_string(bounds: &[ast::TyParamBound]) -> String {
 316     to_string(|s| s.print_bounds("", bounds))
 317 }
 318
 319 pub fn pat_to_string(pat: &ast::Pat) -> String {
 320     to_string(|s| s.print_pat(pat))
 321 }
 322
 323 pub fn arm_to_string(arm: &ast::Arm) -> String {
 324     to_string(|s| s.print_arm(arm))
 325 }
 326
 327 pub fn expr_to_string(e: &ast::Expr) -> String {
 328     to_string(|s| s.print_expr(e))
 329 }
 330
 331 pub fn lifetime_to_string(e: &ast::Lifetime) -> String {
 332     to_string(|s| s.print_lifetime(e))
 333 }
 334
 335 pub fn tt_to_string(tt: &ast::TokenTree) -> String {
 336     to_string(|s| s.print_tt(tt))
 337 }
 338
 339 pub fn tts_to_string(tts: &[ast::TokenTree]) -> String {
 340     to_string(|s| s.print_tts(tts))
 341 }
 342
 343 pub fn stmt_to_string(stmt: &ast::Stmt) -> String {
 344     to_string(|s| s.print_stmt(stmt))
 345 }
 346
 347 pub fn attr_to_string(attr: &ast::Attribute) -> String {
 348     to_string(|s| s.print_attribute(attr))
 349 }
 350
 351 pub fn item_to_string(i: &ast::Item) -> String {
 352     to_string(|s| s.print_item(i))
 353 }
 354
 355 pub fn impl_item_to_string(i: &ast::ImplItem) -> String {
 356     to_string(|s| s.print_impl_item(i))
 357 }
 358
 359 pub fn trait_item_to_string(i: &ast::TraitItem) -> String {
 360     to_string(|s| s.print_trait_item(i))
 361 }
 362
 363 pub fn generics_to_string(generics: &ast::Generics) -> String {
 364     to_string(|s| s.print_generics(generics))
 365 }
 366
 367 pub fn where_clause_to_string(i: &ast::WhereClause) -> String {
 368     to_string(|s| s.print_where_clause(i))
 369 }
 370
 371 pub fn fn_block_to_string(p: &ast::FnDecl) -> String {
 372     to_string(|s| s.print_fn_block_args(p))
 373 }
 374
 375 pub fn path_to_string(p: &ast::Path) -> String {
 376     to_string(|s| s.print_path(p, false, 0))
 377 }
 378
 379 pub fn ident_to_string(id: &ast::Ident) -> String {
 380     to_string(|s| s.print_ident(*id))
 381 }
 382
 383 pub fn fun_to_string(decl: &ast::FnDecl,
 384                      unsafety: ast::Unsafety,
 385                      constness: ast::Constness,
 386                      name: ast::Ident,
 387                      opt_explicit_self: Option<&ast::ExplicitSelf_>,
 388                      generics: &ast::Generics)
 389                      -> String {
 390     to_string(|s| {
 391         try!(s.head(""));
 392         try!(s.print_fn(decl, unsafety, constness, abi::Rust, Some(name),
 393                         generics, opt_explicit_self, ast::Inherited));
 394         try!(s.end()); // Close the head box
 395         s.end() // Close the outer box
 396     })
 397 }
 398
 399 pub fn block_to_string(blk: &ast::Block) -> String {
 400     to_string(|s| {
 401         // containing cbox, will be closed by print-block at }
 402         try!(s.cbox(indent_unit));
 403         // head-ibox, will be closed by print-block after {
 404         try!(s.ibox(0));
 405         s.print_block(blk)
 406     })
 407 }
 408
 409 pub fn meta_item_to_string(mi: &ast::MetaItem) -> String {
 410     to_string(|s| s.print_meta_item(mi))
 411 }
 412
 413 pub fn attribute_to_string(attr: &ast::Attribute) -> String {
 414     to_string(|s| s.print_attribute(attr))
 415 }
 416
 417 pub fn lit_to_string(l: &ast::Lit) -> String {
 418     to_string(|s| s.print_literal(l))
 419 }
 420
 421 pub fn explicit_self_to_string(explicit_self: &ast::ExplicitSelf_) -> String {
 422     to_string(|s| s.print_explicit_self(explicit_self, ast::MutImmutable).map(|_| {}))
 423 }
 424
 425 pub fn variant_to_string(var: &ast::Variant) -> String {
 426     to_string(|s| s.print_variant(var))
 427 }
 428
 429 pub fn arg_to_string(arg: &ast::Arg) -> String {
 430     to_string(|s| s.print_arg(arg))
 431 }
 432
 433 pub fn mac_to_string(arg: &ast::Mac) -> String {
 434     to_string(|s| s.print_mac(arg, ::parse::token::Paren))
 435 }
 436
 437 pub fn visibility_qualified(vis: ast::Visibility, s: &str) -> String {
 438     match vis {
 439         ast::Public => format!("pub {}", s),
 440         ast::Inherited => s.to_string()
 441     }
 442 }
 443
 444 fn needs_parentheses(expr: &ast::Expr) -> bool {
 445     match expr.node {
 446         ast::ExprAssign(..) | ast::ExprBinary(..) |
 447         ast::ExprClosure(..) |
 448         ast::ExprAssignOp(..) | ast::ExprCast(..) => true,
 449         _ => false,
 450     }
 451 }
 452
 453 pub trait PrintState<'a> {
 454     fn writer(&mut self) -> &mut pp::Printer<'a>;
 455     fn boxes(&mut self) -> &mut Vec<pp::Breaks>;
 456     fn comments(&mut self) -> &mut Option<Vec<comments::Comment>>;
 457     fn cur_cmnt_and_lit(&mut self) -> &mut CurrentCommentAndLiteral;
 458     fn literals(&self) -> &Option<Vec<comments::Literal>>;
 459
 460     fn word_space(&mut self, w: &str) -> io::Result<()> {
 461         try!(word(self.writer(), w));
 462         space(self.writer())
 463     }
 464
 465     fn popen(&mut self) -> io::Result<()> { word(self.writer(), "(") }
 466
 467     fn pclose(&mut self) -> io::Result<()> { word(self.writer(), ")") }
 468
 469     fn is_begin(&mut self) -> bool {
 470         match self.writer().last_token() {
 471             pp::Token::Begin(_) => true,
 472             _ => false,
 473         }
 474     }
 475
 476     fn is_end(&mut self) -> bool {
 477         match self.writer().last_token() {
 478             pp::Token::End => true,
 479             _ => false,
 480         }
 481     }
 482
 483     // is this the beginning of a line?
 484     fn is_bol(&mut self) -> bool {
 485         self.writer().last_token().is_eof() || self.writer().last_token().is_hardbreak_tok()
 486     }
 487
 488     fn hardbreak_if_not_bol(&mut self) -> io::Result<()> {
 489         if !self.is_bol() {
 490             try!(hardbreak(self.writer()))
 491         }
 492         Ok(())
 493     }
 494
 495     // "raw box"
 496     fn rbox(&mut self, u: usize, b: pp::Breaks) -> io::Result<()> {
 497         self.boxes().push(b);
 498         pp::rbox(self.writer(), u, b)
 499     }
 500
 501     fn ibox(&mut self, u: usize) -> io::Result<()> {
 502         self.boxes().push(pp::Breaks::Inconsistent);
 503         pp::ibox(self.writer(), u)
 504     }
 505
 506     fn end(&mut self) -> io::Result<()> {
 507         self.boxes().pop().unwrap();
 508         pp::end(self.writer())
 509     }
 510
 511     fn commasep<T, F>(&mut self, b: Breaks, elts: &[T], mut op: F) -> io::Result<()>
 512         where F: FnMut(&mut Self, &T) -> io::Result<()>,
 513     {
 514         try!(self.rbox(0, b));
 515         let mut first = true;
 516         for elt in elts {
 517             if first { first = false; } else { try!(self.word_space(",")); }
 518             try!(op(self, elt));
 519         }
 520         self.end()
 521     }
 522
 523
 524     fn next_lit(&mut self, pos: BytePos) -> Option<comments::Literal> {
 525         let mut cur_lit = self.cur_cmnt_and_lit().cur_lit;
 526
 527         let mut result = None;
 528
 529         if let &Some(ref lits) = self.literals()
 530         {
 531             while cur_lit < lits.len() {
 532                 let ltrl = (*lits)[cur_lit].clone();
 533                 if ltrl.pos > pos { break; }
 534                 cur_lit += 1;
 535                 if ltrl.pos == pos {
 536                     result = Some(ltrl);
 537                     break;
 538                 }
 539             }
 540         }
 541
 542         self.cur_cmnt_and_lit().cur_lit = cur_lit;
 543         result
 544     }
 545
 546     fn maybe_print_comment(&mut self, pos: BytePos) -> io::Result<()> {
 547         loop {
 548             match self.next_comment() {
 549                 Some(ref cmnt) => {
 550                     if (*cmnt).pos < pos {
 551                         try!(self.print_comment(cmnt));
 552                         self.cur_cmnt_and_lit().cur_cmnt += 1;
 553                     } else { break; }
 554                 }
 555                 _ => break
 556             }
 557         }
 558         Ok(())
 559     }
 560
 561     fn print_comment(&mut self,
 562                      cmnt: &comments::Comment) -> io::Result<()> {
 563         match cmnt.style {
 564             comments::Mixed => {
 565                 assert_eq!(cmnt.lines.len(), 1);
 566                 try!(zerobreak(self.writer()));
 567                 try!(word(self.writer(), &cmnt.lines[0]));
 568                 zerobreak(self.writer())
 569             }
 570             comments::Isolated => {
 571                 try!(self.hardbreak_if_not_bol());
 572                 for line in &cmnt.lines {
 573                     // Don't print empty lines because they will end up as trailing
 574                     // whitespace
 575                     if !line.is_empty() {
 576                         try!(word(self.writer(), &line[..]));
 577                     }
 578                     try!(hardbreak(self.writer()));
 579                 }
 580                 Ok(())
 581             }
 582             comments::Trailing => {
 583                 try!(word(self.writer(), " "));
 584                 if cmnt.lines.len() == 1 {
 585                     try!(word(self.writer(), &cmnt.lines[0]));
 586                     hardbreak(self.writer())
 587                 } else {
 588                     try!(self.ibox(0));
 589                     for line in &cmnt.lines {
 590                         if !line.is_empty() {
 591                             try!(word(self.writer(), &line[..]));
 592                         }
 593                         try!(hardbreak(self.writer()));
 594                     }
 595                     self.end()
 596                 }
 597             }
 598             comments::BlankLine => {
 599                 // We need to do at least one, possibly two hardbreaks.
 600                 let is_semi = match self.writer().last_token() {
 601                     pp::Token::String(s, _) => ";" == s,
 602                     _ => false
 603                 };
 604                 if is_semi || self.is_begin() || self.is_end() {
 605                     try!(hardbreak(self.writer()));
 606                 }
 607                 hardbreak(self.writer())
 608             }
 609         }
 610     }
 611
 612     fn next_comment(&mut self) -> Option<comments::Comment> {
 613         let cur_cmnt = self.cur_cmnt_and_lit().cur_cmnt;
 614         match *self.comments() {
 615             Some(ref cmnts) => {
 616                 if cur_cmnt < cmnts.len() {
 617                     Some(cmnts[cur_cmnt].clone())
 618                 } else {
 619                     None
 620                 }
 621             }
 622             _ => None
 623         }
 624     }
 625
 626     fn print_literal(&mut self, lit: &ast::Lit) -> io::Result<()> {
 627         try!(self.maybe_print_comment(lit.span.lo));
 628         match self.next_lit(lit.span.lo) {
 629             Some(ref ltrl) => {
 630                 return word(self.writer(), &(*ltrl).lit);
 631             }
 632             _ => ()
 633         }
 634         match lit.node {
 635             ast::LitStr(ref st, style) => self.print_string(&st, style),
 636             ast::LitByte(byte) => {
 637                 let mut res = String::from("b'");
 638                 res.extend(ascii::escape_default(byte).map(|c| c as char));
 639                 res.push('\'');
 640                 word(self.writer(), &res[..])
 641             }
 642             ast::LitChar(ch) => {
 643                 let mut res = String::from("'");
 644                 res.extend(ch.escape_default());
 645                 res.push('\'');
 646                 word(self.writer(), &res[..])
 647             }
 648             ast::LitInt(i, t) => {
 649                 match t {
 650                     ast::SignedIntLit(st, ast::Plus) => {
 651                         word(self.writer(),
 652                              &ast_util::int_ty_to_string(st, Some(i as i64)))
 653                     }
 654                     ast::SignedIntLit(st, ast::Minus) => {
 655                         let istr = ast_util::int_ty_to_string(st, Some(-(i as i64)));
 656                         word(self.writer(),
 657                              &format!("-{}", istr))
 658                     }
 659                     ast::UnsignedIntLit(ut) => {
 660                         word(self.writer(), &ast_util::uint_ty_to_string(ut, Some(i)))
 661                     }
 662                     ast::UnsuffixedIntLit(ast::Plus) => {
 663                         word(self.writer(), &format!("{}", i))
 664                     }
 665                     ast::UnsuffixedIntLit(ast::Minus) => {
 666                         word(self.writer(), &format!("-{}", i))
 667                     }
 668                 }
 669             }
 670             ast::LitFloat(ref f, t) => {
 671                 word(self.writer(),
 672                      &format!(
 673                          "{}{}",
 674                          &f,
 675                          &ast_util::float_ty_to_string(t)))
 676             }
 677             ast::LitFloatUnsuffixed(ref f) => word(self.writer(), &f[..]),
 678             ast::LitBool(val) => {
 679                 if val { word(self.writer(), "true") } else { word(self.writer(), "false") }
 680             }
 681             ast::LitByteStr(ref v) => {
 682                 let mut escaped: String = String::new();
 683                 for &ch in v.iter() {
 684                     escaped.extend(ascii::escape_default(ch)
 685                                          .map(|c| c as char));
 686                 }
 687                 word(self.writer(), &format!("b\"{}\"", escaped))
 688             }
 689         }
 690     }
 691
 692     fn print_string(&mut self, st: &str,
 693                     style: ast::StrStyle) -> io::Result<()> {
 694         let st = match style {
 695             ast::CookedStr => {
 696                 (format!("\"{}\"", st.escape_default()))
 697             }
 698             ast::RawStr(n) => {
 699                 (format!("r{delim}\"{string}\"{delim}",
 700                          delim=repeat("#", n),
 701                          string=st))
 702             }
 703         };
 704         word(self.writer(), &st[..])
 705     }
 706
 707     fn print_inner_attributes(&mut self,
 708                                   attrs: &[ast::Attribute]) -> io::Result<()> {
 709         let mut count = 0;
 710         for attr in attrs {
 711             match attr.node.style {
 712                 ast::AttrInner => {
 713                     try!(self.print_attribute(attr));
 714                     count += 1;
 715                 }
 716                 _ => {/* fallthrough */ }
 717             }
 718         }
 719         if count > 0 {
 720             try!(self.hardbreak_if_not_bol());
 721         }
 722         Ok(())
 723     }
 724
 725     fn print_outer_attributes(&mut self,
 726                               attrs: &[ast::Attribute]) -> io::Result<()> {
 727         let mut count = 0;
 728         for attr in attrs {
 729             match attr.node.style {
 730                 ast::AttrOuter => {
 731                     try!(self.print_attribute(attr));
 732                     count += 1;
 733                 }
 734                 _ => {/* fallthrough */ }
 735             }
 736         }
 737         if count > 0 {
 738             try!(self.hardbreak_if_not_bol());
 739         }
 740         Ok(())
 741     }
 742
 743     fn print_attribute(&mut self, attr: &ast::Attribute) -> io::Result<()> {
 744         try!(self.hardbreak_if_not_bol());
 745         try!(self.maybe_print_comment(attr.span.lo));
 746         if attr.node.is_sugared_doc {
 747             word(self.writer(), &attr.value_str().unwrap())
 748         } else {
 749             match attr.node.style {
 750                 ast::AttrInner => try!(word(self.writer(), "#![")),
 751                 ast::AttrOuter => try!(word(self.writer(), "#[")),
 752             }
 753             try!(self.print_meta_item(&*attr.meta()));
 754             word(self.writer(), "]")
 755         }
 756     }
 757
 758     fn print_meta_item(&mut self, item: &ast::MetaItem) -> io::Result<()> {
 759         try!(self.ibox(indent_unit));
 760         match item.node {
 761             ast::MetaWord(ref name) => {
 762                 try!(word(self.writer(), &name));
 763             }
 764             ast::MetaNameValue(ref name, ref value) => {
 765                 try!(self.word_space(&name[..]));
 766                 try!(self.word_space("="));
 767                 try!(self.print_literal(value));
 768             }
 769             ast::MetaList(ref name, ref items) => {
 770                 try!(word(self.writer(), &name));
 771                 try!(self.popen());
 772                 try!(self.commasep(Consistent,
 773                                    &items[..],
 774                                    |s, i| s.print_meta_item(&**i)));
 775                 try!(self.pclose());
 776             }
 777         }
 778         self.end()
 779     }
 780 }
 781
 782 impl<'a> PrintState<'a> for State<'a> {
 783     fn writer(&mut self) -> &mut pp::Printer<'a> {
 784         &mut self.s
 785     }
 786
 787     fn boxes(&mut self) -> &mut Vec<pp::Breaks> {
 788         &mut self.boxes
 789     }
 790
 791     fn comments(&mut self) -> &mut Option<Vec<comments::Comment>> {
 792         &mut self.comments
 793     }
 794
 795     fn cur_cmnt_and_lit(&mut self) -> &mut CurrentCommentAndLiteral {
 796         &mut self.cur_cmnt_and_lit
 797     }
 798
 799     fn literals(&self) -> &Option<Vec<comments::Literal>> {
 800         &self.literals
 801     }
 802 }
 803
 804 impl<'a> State<'a> {
 805     pub fn cbox(&mut self, u: usize) -> io::Result<()> {
 806         self.boxes.push(pp::Breaks::Consistent);
 807         pp::cbox(&mut self.s, u)
 808     }
 809
 810     pub fn nbsp(&mut self) -> io::Result<()> { word(&mut self.s, " ") }
 811
 812     pub fn word_nbsp(&mut self, w: &str) -> io::Result<()> {
 813         try!(word(&mut self.s, w));
 814         self.nbsp()
 815     }
 816
 817     pub fn head(&mut self, w: &str) -> io::Result<()> {
 818         // outer-box is consistent
 819         try!(self.cbox(indent_unit));
 820         // head-box is inconsistent
 821         try!(self.ibox(w.len() + 1));
 822         // keyword that starts the head
 823         if !w.is_empty() {
 824             try!(self.word_nbsp(w));
 825         }
 826         Ok(())
 827     }
 828
 829     pub fn bopen(&mut self) -> io::Result<()> {
 830         try!(word(&mut self.s, "{"));
 831         self.end() // close the head-box
 832     }
 833
 834     pub fn bclose_(&mut self, span: codemap::Span,
 835                    indented: usize) -> io::Result<()> {
 836         self.bclose_maybe_open(span, indented, true)
 837     }
 838     pub fn bclose_maybe_open (&mut self, span: codemap::Span,
 839                               indented: usize, close_box: bool) -> io::Result<()> {
 840         try!(self.maybe_print_comment(span.hi));
 841         try!(self.break_offset_if_not_bol(1, -(indented as isize)));
 842         try!(word(&mut self.s, "}"));
 843         if close_box {
 844             try!(self.end()); // close the outer-box
 845         }
 846         Ok(())
 847     }
 848     pub fn bclose(&mut self, span: codemap::Span) -> io::Result<()> {
 849         self.bclose_(span, indent_unit)
 850     }
 851
 852     pub fn in_cbox(&self) -> bool {
 853         match self.boxes.last() {
 854             Some(&last_box) => last_box == pp::Breaks::Consistent,
 855             None => false
 856         }
 857     }
 858
 859     pub fn space_if_not_bol(&mut self) -> io::Result<()> {
 860         if !self.is_bol() { try!(space(&mut self.s)); }
 861         Ok(())
 862     }
 863     pub fn break_offset_if_not_bol(&mut self, n: usize,
 864                                    off: isize) -> io::Result<()> {
 865         if !self.is_bol() {
 866             break_offset(&mut self.s, n, off)
 867         } else {
 868             if off != 0 && self.s.last_token().is_hardbreak_tok() {
 869                 // We do something pretty sketchy here: tuck the nonzero
 870                 // offset-adjustment we were going to deposit along with the
 871                 // break into the previous hardbreak.
 872                 self.s.replace_last_token(pp::hardbreak_tok_offset(off));
 873             }
 874             Ok(())
 875         }
 876     }
 877
 878     // Synthesizes a comment that was not textually present in the original source
 879     // file.
 880     pub fn synth_comment(&mut self, text: String) -> io::Result<()> {
 881         try!(word(&mut self.s, "/*"));
 882         try!(space(&mut self.s));
 883         try!(word(&mut self.s, &text[..]));
 884         try!(space(&mut self.s));
 885         word(&mut self.s, "*/")
 886     }
 887
 888
 889
 890     pub fn commasep_cmnt<T, F, G>(&mut self,
 891                                   b: Breaks,
 892                                   elts: &[T],
 893                                   mut op: F,
 894                                   mut get_span: G) -> io::Result<()> where
 895         F: FnMut(&mut State, &T) -> io::Result<()>,
 896         G: FnMut(&T) -> codemap::Span,
 897     {
 898         try!(self.rbox(0, b));
 899         let len = elts.len();
 900         let mut i = 0;
 901         for elt in elts {
 902             try!(self.maybe_print_comment(get_span(elt).hi));
 903             try!(op(self, elt));
 904             i += 1;
 905             if i < len {
 906                 try!(word(&mut self.s, ","));
 907                 try!(self.maybe_print_trailing_comment(get_span(elt),
 908                                                     Some(get_span(&elts[i]).hi)));
 909                 try!(self.space_if_not_bol());
 910             }
 911         }
 912         self.end()
 913     }
 914
 915     pub fn commasep_exprs(&mut self, b: Breaks,
 916                           exprs: &[P<ast::Expr>]) -> io::Result<()> {
 917         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(&**e), |e| e.span)
 918     }
 919
 920     pub fn print_mod(&mut self, _mod: &ast::Mod,
 921                      attrs: &[ast::Attribute]) -> io::Result<()> {
 922         try!(self.print_inner_attributes(attrs));
 923         for item in &_mod.items {
 924             try!(self.print_item(&**item));
 925         }
 926         Ok(())
 927     }
 928
 929     pub fn print_foreign_mod(&mut self, nmod: &ast::ForeignMod,
 930                              attrs: &[ast::Attribute]) -> io::Result<()> {
 931         try!(self.print_inner_attributes(attrs));
 932         for item in &nmod.items {
 933             try!(self.print_foreign_item(&**item));
 934         }
 935         Ok(())
 936     }
 937
 938     pub fn print_opt_lifetime(&mut self,
 939                               lifetime: &Option<ast::Lifetime>) -> io::Result<()> {
 940         if let Some(l) = *lifetime {
 941             try!(self.print_lifetime(&l));
 942             try!(self.nbsp());
 943         }
 944         Ok(())
 945     }
 946
 947     pub fn print_type(&mut self, ty: &ast::Ty) -> io::Result<()> {
 948         try!(self.maybe_print_comment(ty.span.lo));
 949         try!(self.ibox(0));
 950         match ty.node {
 951             ast::TyVec(ref ty) => {
 952                 try!(word(&mut self.s, "["));
 953                 try!(self.print_type(&**ty));
 954                 try!(word(&mut self.s, "]"));
 955             }
 956             ast::TyPtr(ref mt) => {
 957                 try!(word(&mut self.s, "*"));
 958                 match mt.mutbl {
 959                     ast::MutMutable => try!(self.word_nbsp("mut")),
 960                     ast::MutImmutable => try!(self.word_nbsp("const")),
 961                 }
 962                 try!(self.print_type(&*mt.ty));
 963             }
 964             ast::TyRptr(ref lifetime, ref mt) => {
 965                 try!(word(&mut self.s, "&"));
 966                 try!(self.print_opt_lifetime(lifetime));
 967                 try!(self.print_mt(mt));
 968             }
 969             ast::TyTup(ref elts) => {
 970                 try!(self.popen());
 971                 try!(self.commasep(Inconsistent, &elts[..],
 972                                    |s, ty| s.print_type(&**ty)));
 973                 if elts.len() == 1 {
 974                     try!(word(&mut self.s, ","));
 975                 }
 976                 try!(self.pclose());
 977             }
 978             ast::TyParen(ref typ) => {
 979                 try!(self.popen());
 980                 try!(self.print_type(&**typ));
 981                 try!(self.pclose());
 982             }
 983             ast::TyBareFn(ref f) => {
 984                 let generics = ast::Generics {
 985                     lifetimes: f.lifetimes.clone(),
 986                     ty_params: OwnedSlice::empty(),
 987                     where_clause: ast::WhereClause {
 988                         id: ast::DUMMY_NODE_ID,
 989                         predicates: Vec::new(),
 990                     },
 991                 };
 992                 try!(self.print_ty_fn(f.abi,
 993                                       f.unsafety,
 994                                       &*f.decl,
 995                                       None,
 996                                       &generics,
 997                                       None));
 998             }
 999             ast::TyPath(None, ref path) => {
1000                 try!(self.print_path(path, false, 0));
1001             }
1002             ast::TyPath(Some(ref qself), ref path) => {
1003                 try!(self.print_qpath(path, qself, false))
1004             }
1005             ast::TyObjectSum(ref ty, ref bounds) => {
1006                 try!(self.print_type(&**ty));
1007                 try!(self.print_bounds("+", &bounds[..]));
1008             }
1009             ast::TyPolyTraitRef(ref bounds) => {
1010                 try!(self.print_bounds("", &bounds[..]));
1011             }
1012             ast::TyFixedLengthVec(ref ty, ref v) => {
1013                 try!(word(&mut self.s, "["));
1014                 try!(self.print_type(&**ty));
1015                 try!(word(&mut self.s, "; "));
1016                 try!(self.print_expr(&**v));
1017                 try!(word(&mut self.s, "]"));
1018             }
1019             ast::TyTypeof(ref e) => {
1020                 try!(word(&mut self.s, "typeof("));
1021                 try!(self.print_expr(&**e));
1022                 try!(word(&mut self.s, ")"));
1023             }
1024             ast::TyInfer => {
1025                 try!(word(&mut self.s, "_"));
1026             }
1027             ast::TyMac(ref m) => {
1028                 try!(self.print_mac(m, token::Paren));
1029             }
1030         }
1031         self.end()
1032     }
1033
1034     pub fn print_foreign_item(&mut self,
1035                               item: &ast::ForeignItem) -> io::Result<()> {
1036         try!(self.hardbreak_if_not_bol());
1037         try!(self.maybe_print_comment(item.span.lo));
1038         try!(self.print_outer_attributes(&item.attrs));
1039         match item.node {
1040             ast::ForeignItemFn(ref decl, ref generics) => {
1041                 try!(self.head(""));
1042                 try!(self.print_fn(decl, ast::Unsafety::Normal,
1043                                    ast::Constness::NotConst,
1044                                    abi::Rust, Some(item.ident),
1045                                    generics, None, item.vis));
1046                 try!(self.end()); // end head-ibox
1047                 try!(word(&mut self.s, ";"));
1048                 self.end() // end the outer fn box
1049             }
1050             ast::ForeignItemStatic(ref t, m) => {
1051                 try!(self.head(&visibility_qualified(item.vis,
1052                                                     "static")));
1053                 if m {
1054                     try!(self.word_space("mut"));
1055                 }
1056                 try!(self.print_ident(item.ident));
1057                 try!(self.word_space(":"));
1058                 try!(self.print_type(&**t));
1059                 try!(word(&mut self.s, ";"));
1060                 try!(self.end()); // end the head-ibox
1061                 self.end() // end the outer cbox
1062             }
1063         }
1064     }
1065
1066     fn print_associated_const(&mut self,
1067                               ident: ast::Ident,
1068                               ty: &ast::Ty,
1069                               default: Option<&ast::Expr>,
1070                               vis: ast::Visibility)
1071                               -> io::Result<()>
1072     {
1073         try!(word(&mut self.s, &visibility_qualified(vis, "")));
1074         try!(self.word_space("const"));
1075         try!(self.print_ident(ident));
1076         try!(self.word_space(":"));
1077         try!(self.print_type(ty));
1078         if let Some(expr) = default {
1079             try!(space(&mut self.s));
1080             try!(self.word_space("="));
1081             try!(self.print_expr(expr));
1082         }
1083         word(&mut self.s, ";")
1084     }
1085
1086     fn print_associated_type(&mut self,
1087                              ident: ast::Ident,
1088                              bounds: Option<&ast::TyParamBounds>,
1089                              ty: Option<&ast::Ty>)
1090                              -> io::Result<()> {
1091         try!(self.word_space("type"));
1092         try!(self.print_ident(ident));
1093         if let Some(bounds) = bounds {
1094             try!(self.print_bounds(":", bounds));
1095         }
1096         if let Some(ty) = ty {
1097             try!(space(&mut self.s));
1098             try!(self.word_space("="));
1099             try!(self.print_type(ty));
1100         }
1101         word(&mut self.s, ";")
1102     }
1103
1104     /// Pretty-print an item
1105     pub fn print_item(&mut self, item: &ast::Item) -> io::Result<()> {
1106         try!(self.hardbreak_if_not_bol());
1107         try!(self.maybe_print_comment(item.span.lo));
1108         try!(self.print_outer_attributes(&item.attrs));
1109         try!(self.ann.pre(self, NodeItem(item)));
1110         match item.node {
1111             ast::ItemExternCrate(ref optional_path) => {
1112                 try!(self.head(&visibility_qualified(item.vis,
1113                                                      "extern crate")));
1114                 if let Some(p) = *optional_path {
1115                     let val = p.as_str();
1116                     if val.contains("-") {
1117                         try!(self.print_string(&val, ast::CookedStr));
1118                     } else {
1119                         try!(self.print_name(p));
1120                     }
1121                     try!(space(&mut self.s));
1122                     try!(word(&mut self.s, "as"));
1123                     try!(space(&mut self.s));
1124                 }
1125                 try!(self.print_ident(item.ident));
1126                 try!(word(&mut self.s, ";"));
1127                 try!(self.end()); // end inner head-block
1128                 try!(self.end()); // end outer head-block
1129             }
1130             ast::ItemUse(ref vp) => {
1131                 try!(self.head(&visibility_qualified(item.vis,
1132                                                      "use")));
1133                 try!(self.print_view_path(&**vp));
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::ItemStatic(ref ty, m, ref expr) => {
1139                 try!(self.head(&visibility_qualified(item.vis,
1140                                                     "static")));
1141                 if m == ast::MutMutable {
1142                     try!(self.word_space("mut"));
1143                 }
1144                 try!(self.print_ident(item.ident));
1145                 try!(self.word_space(":"));
1146                 try!(self.print_type(&**ty));
1147                 try!(space(&mut self.s));
1148                 try!(self.end()); // end the head-ibox
1149
1150                 try!(self.word_space("="));
1151                 try!(self.print_expr(&**expr));
1152                 try!(word(&mut self.s, ";"));
1153                 try!(self.end()); // end the outer cbox
1154             }
1155             ast::ItemConst(ref ty, ref expr) => {
1156                 try!(self.head(&visibility_qualified(item.vis,
1157                                                     "const")));
1158                 try!(self.print_ident(item.ident));
1159                 try!(self.word_space(":"));
1160                 try!(self.print_type(&**ty));
1161                 try!(space(&mut self.s));
1162                 try!(self.end()); // end the head-ibox
1163
1164                 try!(self.word_space("="));
1165                 try!(self.print_expr(&**expr));
1166                 try!(word(&mut self.s, ";"));
1167                 try!(self.end()); // end the outer cbox
1168             }
1169             ast::ItemFn(ref decl, unsafety, constness, abi, ref typarams, ref body) => {
1170                 try!(self.head(""));
1171                 try!(self.print_fn(
1172                     decl,
1173                     unsafety,
1174                     constness,
1175                     abi,
1176                     Some(item.ident),
1177                     typarams,
1178                     None,
1179                     item.vis
1180                 ));
1181                 try!(word(&mut self.s, " "));
1182                 try!(self.print_block_with_attrs(&**body, &item.attrs));
1183             }
1184             ast::ItemMod(ref _mod) => {
1185                 try!(self.head(&visibility_qualified(item.vis,
1186                                                     "mod")));
1187                 try!(self.print_ident(item.ident));
1188                 try!(self.nbsp());
1189                 try!(self.bopen());
1190                 try!(self.print_mod(_mod, &item.attrs));
1191                 try!(self.bclose(item.span));
1192             }
1193             ast::ItemForeignMod(ref nmod) => {
1194                 try!(self.head("extern"));
1195                 try!(self.word_nbsp(&nmod.abi.to_string()));
1196                 try!(self.bopen());
1197                 try!(self.print_foreign_mod(nmod, &item.attrs));
1198                 try!(self.bclose(item.span));
1199             }
1200             ast::ItemTy(ref ty, ref params) => {
1201                 try!(self.ibox(indent_unit));
1202                 try!(self.ibox(0));
1203                 try!(self.word_nbsp(&visibility_qualified(item.vis, "type")));
1204                 try!(self.print_ident(item.ident));
1205                 try!(self.print_generics(params));
1206                 try!(self.end()); // end the inner ibox
1207
1208                 try!(self.print_where_clause(&params.where_clause));
1209                 try!(space(&mut self.s));
1210                 try!(self.word_space("="));
1211                 try!(self.print_type(&**ty));
1212                 try!(word(&mut self.s, ";"));
1213                 try!(self.end()); // end the outer ibox
1214             }
1215             ast::ItemEnum(ref enum_definition, ref params) => {
1216                 try!(self.print_enum_def(
1217                     enum_definition,
1218                     params,
1219                     item.ident,
1220                     item.span,
1221                     item.vis
1222                 ));
1223             }
1224             ast::ItemStruct(ref struct_def, ref generics) => {
1225                 try!(self.head(&visibility_qualified(item.vis,"struct")));
1226                 try!(self.print_struct(&**struct_def, generics, item.ident, item.span));
1227             }
1228
1229             ast::ItemDefaultImpl(unsafety, ref trait_ref) => {
1230                 try!(self.head(""));
1231                 try!(self.print_visibility(item.vis));
1232                 try!(self.print_unsafety(unsafety));
1233                 try!(self.word_nbsp("impl"));
1234                 try!(self.print_trait_ref(trait_ref));
1235                 try!(space(&mut self.s));
1236                 try!(self.word_space("for"));
1237                 try!(self.word_space(".."));
1238                 try!(self.bopen());
1239                 try!(self.bclose(item.span));
1240             }
1241             ast::ItemImpl(unsafety,
1242                           polarity,
1243                           ref generics,
1244                           ref opt_trait,
1245                           ref ty,
1246                           ref impl_items) => {
1247                 try!(self.head(""));
1248                 try!(self.print_visibility(item.vis));
1249                 try!(self.print_unsafety(unsafety));
1250                 try!(self.word_nbsp("impl"));
1251
1252                 if generics.is_parameterized() {
1253                     try!(self.print_generics(generics));
1254                     try!(space(&mut self.s));
1255                 }
1256
1257                 match polarity {
1258                     ast::ImplPolarity::Negative => {
1259                         try!(word(&mut self.s, "!"));
1260                     },
1261                     _ => {}
1262                 }
1263
1264                 match opt_trait {
1265                     &Some(ref t) => {
1266                         try!(self.print_trait_ref(t));
1267                         try!(space(&mut self.s));
1268                         try!(self.word_space("for"));
1269                     }
1270                     &None => {}
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::ItemTrait(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::ItemMac(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_def(lifetime_def));
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: codemap::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: &[P<ast::Variant>],
1365                           span: codemap::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::Public => self.word_nbsp("pub"),
1383             ast::Inherited => Ok(())
1384         }
1385     }
1386
1387     pub fn print_struct(&mut self,
1388                         struct_def: &ast::StructDef,
1389                         generics: &ast::Generics,
1390                         ident: ast::Ident,
1391                         span: codemap::Span) -> io::Result<()> {
1392         try!(self.print_ident(ident));
1393         try!(self.print_generics(generics));
1394         if ast_util::struct_def_is_tuple_like(struct_def) {
1395             if !struct_def.fields.is_empty() {
1396                 try!(self.popen());
1397                 try!(self.commasep(
1398                     Inconsistent, &struct_def.fields,
1399                     |s, field| {
1400                         match field.node.kind {
1401                             ast::NamedField(..) => panic!("unexpected named field"),
1402                             ast::UnnamedField(vis) => {
1403                                 try!(s.print_visibility(vis));
1404                                 try!(s.maybe_print_comment(field.span.lo));
1405                                 s.print_type(&*field.node.ty)
1406                             }
1407                         }
1408                     }
1409                 ));
1410                 try!(self.pclose());
1411             }
1412             try!(self.print_where_clause(&generics.where_clause));
1413             try!(word(&mut self.s, ";"));
1414             try!(self.end());
1415             self.end() // close the outer-box
1416         } else {
1417             try!(self.print_where_clause(&generics.where_clause));
1418             try!(self.nbsp());
1419             try!(self.bopen());
1420             try!(self.hardbreak_if_not_bol());
1421
1422             for field in &struct_def.fields {
1423                 match field.node.kind {
1424                     ast::UnnamedField(..) => panic!("unexpected unnamed field"),
1425                     ast::NamedField(ident, visibility) => {
1426                         try!(self.hardbreak_if_not_bol());
1427                         try!(self.maybe_print_comment(field.span.lo));
1428                         try!(self.print_outer_attributes(&field.node.attrs));
1429                         try!(self.print_visibility(visibility));
1430                         try!(self.print_ident(ident));
1431                         try!(self.word_nbsp(":"));
1432                         try!(self.print_type(&*field.node.ty));
1433                         try!(word(&mut self.s, ","));
1434                     }
1435                 }
1436             }
1437
1438             self.bclose(span)
1439         }
1440     }
1441
1442     /// This doesn't deserve to be called "pretty" printing, but it should be
1443     /// meaning-preserving. A quick hack that might help would be to look at the
1444     /// spans embedded in the TTs to decide where to put spaces and newlines.
1445     /// But it'd be better to parse these according to the grammar of the
1446     /// appropriate macro, transcribe back into the grammar we just parsed from,
1447     /// and then pretty-print the resulting AST nodes (so, e.g., we print
1448     /// expression arguments as expressions). It can be done! I think.
1449     pub fn print_tt(&mut self, tt: &ast::TokenTree) -> io::Result<()> {
1450         match *tt {
1451             ast::TtToken(_, ref tk) => {
1452                 try!(word(&mut self.s, &token_to_string(tk)));
1453                 match *tk {
1454                     parse::token::DocComment(..) => {
1455                         hardbreak(&mut self.s)
1456                     }
1457                     _ => Ok(())
1458                 }
1459             }
1460             ast::TtDelimited(_, ref delimed) => {
1461                 try!(word(&mut self.s, &token_to_string(&delimed.open_token())));
1462                 try!(space(&mut self.s));
1463                 try!(self.print_tts(&delimed.tts));
1464                 try!(space(&mut self.s));
1465                 word(&mut self.s, &token_to_string(&delimed.close_token()))
1466             },
1467             ast::TtSequence(_, ref seq) => {
1468                 try!(word(&mut self.s, "$("));
1469                 for tt_elt in &seq.tts {
1470                     try!(self.print_tt(tt_elt));
1471                 }
1472                 try!(word(&mut self.s, ")"));
1473                 match seq.separator {
1474                     Some(ref tk) => {
1475                         try!(word(&mut self.s, &token_to_string(tk)));
1476                     }
1477                     None => {},
1478                 }
1479                 match seq.op {
1480                     ast::ZeroOrMore => word(&mut self.s, "*"),
1481                     ast::OneOrMore => word(&mut self.s, "+"),
1482                 }
1483             }
1484         }
1485     }
1486
1487     pub fn print_tts(&mut self, tts: &[ast::TokenTree]) -> io::Result<()> {
1488         try!(self.ibox(0));
1489         let mut suppress_space = false;
1490         for (i, tt) in tts.iter().enumerate() {
1491             if i != 0 && !suppress_space {
1492                 try!(space(&mut self.s));
1493             }
1494             try!(self.print_tt(tt));
1495             // There should be no space between the module name and the following `::` in paths,
1496             // otherwise imported macros get re-parsed from crate metadata incorrectly (#20701)
1497             suppress_space = match tt {
1498                 &ast::TtToken(_, token::Ident(_, token::ModName)) |
1499                 &ast::TtToken(_, token::MatchNt(_, _, _, token::ModName)) |
1500                 &ast::TtToken(_, token::SubstNt(_, token::ModName)) => true,
1501                 _ => false
1502             }
1503         }
1504         self.end()
1505     }
1506
1507     pub fn print_variant(&mut self, v: &ast::Variant) -> io::Result<()> {
1508         match v.node.kind {
1509             ast::TupleVariantKind(ref args) => {
1510                 try!(self.print_ident(v.node.name));
1511                 if !args.is_empty() {
1512                     try!(self.popen());
1513                     try!(self.commasep(Consistent,
1514                                        &args[..],
1515                                        |s, arg| s.print_type(&*arg.ty)));
1516                     try!(self.pclose());
1517                 }
1518             }
1519             ast::StructVariantKind(ref struct_def) => {
1520                 try!(self.head(""));
1521                 let generics = ast_util::empty_generics();
1522                 try!(self.print_struct(&**struct_def, &generics, v.node.name, v.span));
1523             }
1524         }
1525         match v.node.disr_expr {
1526             Some(ref d) => {
1527                 try!(space(&mut self.s));
1528                 try!(self.word_space("="));
1529                 self.print_expr(&**d)
1530             }
1531             _ => Ok(())
1532         }
1533     }
1534
1535     pub fn print_method_sig(&mut self,
1536                             ident: ast::Ident,
1537                             m: &ast::MethodSig,
1538                             vis: ast::Visibility)
1539                             -> io::Result<()> {
1540         self.print_fn(&m.decl,
1541                       m.unsafety,
1542                       m.constness,
1543                       m.abi,
1544                       Some(ident),
1545                       &m.generics,
1546                       Some(&m.explicit_self.node),
1547                       vis)
1548     }
1549
1550     pub fn print_trait_item(&mut self, ti: &ast::TraitItem)
1551                             -> io::Result<()> {
1552         try!(self.ann.pre(self, NodeSubItem(ti.id)));
1553         try!(self.hardbreak_if_not_bol());
1554         try!(self.maybe_print_comment(ti.span.lo));
1555         try!(self.print_outer_attributes(&ti.attrs));
1556         match ti.node {
1557             ast::ConstTraitItem(ref ty, ref default) => {
1558                 try!(self.print_associated_const(ti.ident, &ty,
1559                                                  default.as_ref().map(|expr| &**expr),
1560                                                  ast::Inherited));
1561             }
1562             ast::MethodTraitItem(ref sig, ref body) => {
1563                 if body.is_some() {
1564                     try!(self.head(""));
1565                 }
1566                 try!(self.print_method_sig(ti.ident, sig, ast::Inherited));
1567                 if let Some(ref body) = *body {
1568                     try!(self.nbsp());
1569                     try!(self.print_block_with_attrs(body, &ti.attrs));
1570                 } else {
1571                     try!(word(&mut self.s, ";"));
1572                 }
1573             }
1574             ast::TypeTraitItem(ref bounds, ref default) => {
1575                 try!(self.print_associated_type(ti.ident, Some(bounds),
1576                                                 default.as_ref().map(|ty| &**ty)));
1577             }
1578         }
1579         self.ann.post(self, NodeSubItem(ti.id))
1580     }
1581
1582     pub fn print_impl_item(&mut self, ii: &ast::ImplItem) -> io::Result<()> {
1583         try!(self.ann.pre(self, NodeSubItem(ii.id)));
1584         try!(self.hardbreak_if_not_bol());
1585         try!(self.maybe_print_comment(ii.span.lo));
1586         try!(self.print_outer_attributes(&ii.attrs));
1587         match ii.node {
1588             ast::ConstImplItem(ref ty, ref expr) => {
1589                 try!(self.print_associated_const(ii.ident, &ty, Some(&expr), ii.vis));
1590             }
1591             ast::MethodImplItem(ref sig, ref body) => {
1592                 try!(self.head(""));
1593                 try!(self.print_method_sig(ii.ident, sig, ii.vis));
1594                 try!(self.nbsp());
1595                 try!(self.print_block_with_attrs(body, &ii.attrs));
1596             }
1597             ast::TypeImplItem(ref ty) => {
1598                 try!(self.print_associated_type(ii.ident, None, Some(ty)));
1599             }
1600             ast::MacImplItem(codemap::Spanned { ref node, .. }) => {
1601                 // code copied from ItemMac:
1602                 try!(self.print_path(&node.path, false, 0));
1603                 try!(word(&mut self.s, "! "));
1604                 try!(self.cbox(indent_unit));
1605                 try!(self.popen());
1606                 try!(self.print_tts(&node.tts[..]));
1607                 try!(self.pclose());
1608                 try!(word(&mut self.s, ";"));
1609                 try!(self.end())
1610             }
1611         }
1612         self.ann.post(self, NodeSubItem(ii.id))
1613     }
1614
1615     pub fn print_stmt(&mut self, st: &ast::Stmt) -> io::Result<()> {
1616         try!(self.maybe_print_comment(st.span.lo));
1617         match st.node {
1618             ast::StmtDecl(ref decl, _) => {
1619                 try!(self.print_decl(&**decl));
1620             }
1621             ast::StmtExpr(ref expr, _) => {
1622                 try!(self.space_if_not_bol());
1623                 try!(self.print_expr(&**expr));
1624             }
1625             ast::StmtSemi(ref expr, _) => {
1626                 try!(self.space_if_not_bol());
1627                 try!(self.print_expr(&**expr));
1628                 try!(word(&mut self.s, ";"));
1629             }
1630             ast::StmtMac(ref mac, style) => {
1631                 try!(self.space_if_not_bol());
1632                 let delim = match style {
1633                     ast::MacStmtWithBraces => token::Brace,
1634                     _ => token::Paren
1635                 };
1636                 try!(self.print_mac(&**mac, delim));
1637                 match style {
1638                     ast::MacStmtWithBraces => {}
1639                     _ => try!(word(&mut self.s, ";")),
1640                 }
1641             }
1642         }
1643         if parse::classify::stmt_ends_with_semi(&st.node) {
1644             try!(word(&mut self.s, ";"));
1645         }
1646         self.maybe_print_trailing_comment(st.span, None)
1647     }
1648
1649     pub fn print_block(&mut self, blk: &ast::Block) -> io::Result<()> {
1650         self.print_block_with_attrs(blk, &[])
1651     }
1652
1653     pub fn print_block_unclosed(&mut self, blk: &ast::Block) -> io::Result<()> {
1654         self.print_block_unclosed_indent(blk, indent_unit)
1655     }
1656
1657     pub fn print_block_unclosed_indent(&mut self, blk: &ast::Block,
1658                                        indented: usize) -> io::Result<()> {
1659         self.print_block_maybe_unclosed(blk, indented, &[], false)
1660     }
1661
1662     pub fn print_block_with_attrs(&mut self,
1663                                   blk: &ast::Block,
1664                                   attrs: &[ast::Attribute]) -> io::Result<()> {
1665         self.print_block_maybe_unclosed(blk, indent_unit, attrs, true)
1666     }
1667
1668     pub fn print_block_maybe_unclosed(&mut self,
1669                                       blk: &ast::Block,
1670                                       indented: usize,
1671                                       attrs: &[ast::Attribute],
1672                                       close_box: bool) -> io::Result<()> {
1673         match blk.rules {
1674             ast::UnsafeBlock(..) | ast::PushUnsafeBlock(..) => try!(self.word_space("unsafe")),
1675             ast::DefaultBlock    | ast::PopUnsafeBlock(..) => ()
1676         }
1677         try!(self.maybe_print_comment(blk.span.lo));
1678         try!(self.ann.pre(self, NodeBlock(blk)));
1679         try!(self.bopen());
1680
1681         try!(self.print_inner_attributes(attrs));
1682
1683         for st in &blk.stmts {
1684             try!(self.print_stmt(&**st));
1685         }
1686         match blk.expr {
1687             Some(ref expr) => {
1688                 try!(self.space_if_not_bol());
1689                 try!(self.print_expr(&**expr));
1690                 try!(self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi)));
1691             }
1692             _ => ()
1693         }
1694         try!(self.bclose_maybe_open(blk.span, indented, close_box));
1695         self.ann.post(self, NodeBlock(blk))
1696     }
1697
1698     fn print_else(&mut self, els: Option<&ast::Expr>) -> io::Result<()> {
1699         match els {
1700             Some(_else) => {
1701                 match _else.node {
1702                     // "another else-if"
1703                     ast::ExprIf(ref i, ref then, ref e) => {
1704                         try!(self.cbox(indent_unit - 1));
1705                         try!(self.ibox(0));
1706                         try!(word(&mut self.s, " else if "));
1707                         try!(self.print_expr(&**i));
1708                         try!(space(&mut self.s));
1709                         try!(self.print_block(&**then));
1710                         self.print_else(e.as_ref().map(|e| &**e))
1711                     }
1712                     // "another else-if-let"
1713                     ast::ExprIfLet(ref pat, ref expr, ref then, ref e) => {
1714                         try!(self.cbox(indent_unit - 1));
1715                         try!(self.ibox(0));
1716                         try!(word(&mut self.s, " else if let "));
1717                         try!(self.print_pat(&**pat));
1718                         try!(space(&mut self.s));
1719                         try!(self.word_space("="));
1720                         try!(self.print_expr(&**expr));
1721                         try!(space(&mut self.s));
1722                         try!(self.print_block(&**then));
1723                         self.print_else(e.as_ref().map(|e| &**e))
1724                     }
1725                     // "final else"
1726                     ast::ExprBlock(ref b) => {
1727                         try!(self.cbox(indent_unit - 1));
1728                         try!(self.ibox(0));
1729                         try!(word(&mut self.s, " else "));
1730                         self.print_block(&**b)
1731                     }
1732                     // BLEAH, constraints would be great here
1733                     _ => {
1734                         panic!("print_if saw if with weird alternative");
1735                     }
1736                 }
1737             }
1738             _ => Ok(())
1739         }
1740     }
1741
1742     pub fn print_if(&mut self, test: &ast::Expr, blk: &ast::Block,
1743                     elseopt: Option<&ast::Expr>) -> io::Result<()> {
1744         try!(self.head("if"));
1745         try!(self.print_expr(test));
1746         try!(space(&mut self.s));
1747         try!(self.print_block(blk));
1748         self.print_else(elseopt)
1749     }
1750
1751     pub fn print_if_let(&mut self, pat: &ast::Pat, expr: &ast::Expr, blk: &ast::Block,
1752                         elseopt: Option<&ast::Expr>) -> io::Result<()> {
1753         try!(self.head("if let"));
1754         try!(self.print_pat(pat));
1755         try!(space(&mut self.s));
1756         try!(self.word_space("="));
1757         try!(self.print_expr(expr));
1758         try!(space(&mut self.s));
1759         try!(self.print_block(blk));
1760         self.print_else(elseopt)
1761     }
1762
1763     pub fn print_mac(&mut self, m: &ast::Mac, delim: token::DelimToken)
1764                      -> io::Result<()> {
1765         try!(self.print_path(&m.node.path, false, 0));
1766         try!(word(&mut self.s, "!"));
1767         match delim {
1768             token::Paren => try!(self.popen()),
1769             token::Bracket => try!(word(&mut self.s, "[")),
1770             token::Brace => try!(self.bopen()),
1771         }
1772         try!(self.print_tts(&m.node.tts));
1773         match delim {
1774             token::Paren => self.pclose(),
1775             token::Bracket => word(&mut self.s, "]"),
1776             token::Brace => self.bclose(m.span),
1777         }
1778     }
1779
1780
1781     fn print_call_post(&mut self, args: &[P<ast::Expr>]) -> io::Result<()> {
1782         try!(self.popen());
1783         try!(self.commasep_exprs(Inconsistent, args));
1784         self.pclose()
1785     }
1786
1787     pub fn check_expr_bin_needs_paren(&mut self, sub_expr: &ast::Expr,
1788                                       binop: ast::BinOp) -> bool {
1789         match sub_expr.node {
1790             ast::ExprBinary(ref sub_op, _, _) => {
1791                 if ast_util::operator_prec(sub_op.node) <
1792                     ast_util::operator_prec(binop.node) {
1793                     true
1794                 } else {
1795                     false
1796                 }
1797             }
1798             _ => true
1799         }
1800     }
1801
1802     pub fn print_expr_maybe_paren(&mut self, expr: &ast::Expr) -> io::Result<()> {
1803         let needs_par = needs_parentheses(expr);
1804         if needs_par {
1805             try!(self.popen());
1806         }
1807         try!(self.print_expr(expr));
1808         if needs_par {
1809             try!(self.pclose());
1810         }
1811         Ok(())
1812     }
1813
1814     fn print_expr_in_place(&mut self,
1815                            place: &ast::Expr,
1816                            expr: &ast::Expr) -> io::Result<()> {
1817         try!(self.word_space("in"));
1818         try!(self.print_expr(place));
1819         try!(space(&mut self.s));
1820         self.print_expr(expr)
1821     }
1822
1823     fn print_expr_vec(&mut self, exprs: &[P<ast::Expr>]) -> io::Result<()> {
1824         try!(self.ibox(indent_unit));
1825         try!(word(&mut self.s, "["));
1826         try!(self.commasep_exprs(Inconsistent, &exprs[..]));
1827         try!(word(&mut self.s, "]"));
1828         self.end()
1829     }
1830
1831     fn print_expr_repeat(&mut self,
1832                          element: &ast::Expr,
1833                          count: &ast::Expr) -> io::Result<()> {
1834         try!(self.ibox(indent_unit));
1835         try!(word(&mut self.s, "["));
1836         try!(self.print_expr(element));
1837         try!(self.word_space(";"));
1838         try!(self.print_expr(count));
1839         try!(word(&mut self.s, "]"));
1840         self.end()
1841     }
1842
1843     fn print_expr_struct(&mut self,
1844                          path: &ast::Path,
1845                          fields: &[ast::Field],
1846                          wth: &Option<P<ast::Expr>>) -> io::Result<()> {
1847         try!(self.print_path(path, true, 0));
1848         try!(word(&mut self.s, "{"));
1849         try!(self.commasep_cmnt(
1850             Consistent,
1851             &fields[..],
1852             |s, field| {
1853                 try!(s.ibox(indent_unit));
1854                 try!(s.print_ident(field.ident.node));
1855                 try!(s.word_space(":"));
1856                 try!(s.print_expr(&*field.expr));
1857                 s.end()
1858             },
1859             |f| f.span));
1860         match *wth {
1861             Some(ref expr) => {
1862                 try!(self.ibox(indent_unit));
1863                 if !fields.is_empty() {
1864                     try!(word(&mut self.s, ","));
1865                     try!(space(&mut self.s));
1866                 }
1867                 try!(word(&mut self.s, ".."));
1868                 try!(self.print_expr(&**expr));
1869                 try!(self.end());
1870             }
1871             _ => if !fields.is_empty() {
1872                 try!(word(&mut self.s, ","))
1873             }
1874         }
1875         try!(word(&mut self.s, "}"));
1876         Ok(())
1877     }
1878
1879     fn print_expr_tup(&mut self, exprs: &[P<ast::Expr>]) -> io::Result<()> {
1880         try!(self.popen());
1881         try!(self.commasep_exprs(Inconsistent, &exprs[..]));
1882         if exprs.len() == 1 {
1883             try!(word(&mut self.s, ","));
1884         }
1885         self.pclose()
1886     }
1887
1888     fn print_expr_call(&mut self,
1889                        func: &ast::Expr,
1890                        args: &[P<ast::Expr>]) -> io::Result<()> {
1891         try!(self.print_expr_maybe_paren(func));
1892         self.print_call_post(args)
1893     }
1894
1895     fn print_expr_method_call(&mut self,
1896                               ident: ast::SpannedIdent,
1897                               tys: &[P<ast::Ty>],
1898                               args: &[P<ast::Expr>]) -> io::Result<()> {
1899         let base_args = &args[1..];
1900         try!(self.print_expr(&*args[0]));
1901         try!(word(&mut self.s, "."));
1902         try!(self.print_ident(ident.node));
1903         if !tys.is_empty() {
1904             try!(word(&mut self.s, "::<"));
1905             try!(self.commasep(Inconsistent, tys,
1906                                |s, ty| s.print_type(&**ty)));
1907             try!(word(&mut self.s, ">"));
1908         }
1909         self.print_call_post(base_args)
1910     }
1911
1912     fn print_expr_binary(&mut self,
1913                          op: ast::BinOp,
1914                          lhs: &ast::Expr,
1915                          rhs: &ast::Expr) -> io::Result<()> {
1916         if self.check_expr_bin_needs_paren(lhs, op) {
1917             try!(self.print_expr_maybe_paren(lhs));
1918         } else {
1919             try!(self.print_expr(lhs));
1920         }
1921         try!(space(&mut self.s));
1922         try!(self.word_space(ast_util::binop_to_string(op.node)));
1923         if self.check_expr_bin_needs_paren(rhs, op) {
1924             self.print_expr_maybe_paren(rhs)
1925         } else {
1926             self.print_expr(rhs)
1927         }
1928     }
1929
1930     fn print_expr_unary(&mut self,
1931                         op: ast::UnOp,
1932                         expr: &ast::Expr) -> io::Result<()> {
1933         try!(word(&mut self.s, ast_util::unop_to_string(op)));
1934         self.print_expr_maybe_paren(expr)
1935     }
1936
1937     fn print_expr_addr_of(&mut self,
1938                           mutability: ast::Mutability,
1939                           expr: &ast::Expr) -> io::Result<()> {
1940         try!(word(&mut self.s, "&"));
1941         try!(self.print_mutability(mutability));
1942         self.print_expr_maybe_paren(expr)
1943     }
1944
1945     pub fn print_expr(&mut self, expr: &ast::Expr) -> io::Result<()> {
1946         try!(self.maybe_print_comment(expr.span.lo));
1947         try!(self.ibox(indent_unit));
1948         try!(self.ann.pre(self, NodeExpr(expr)));
1949         match expr.node {
1950             ast::ExprBox(ref expr) => {
1951                 try!(self.word_space("box"));
1952                 try!(self.print_expr(expr));
1953             }
1954             ast::ExprInPlace(ref place, ref expr) => {
1955                 try!(self.print_expr_in_place(place, expr));
1956             }
1957             ast::ExprVec(ref exprs) => {
1958                 try!(self.print_expr_vec(&exprs[..]));
1959             }
1960             ast::ExprRepeat(ref element, ref count) => {
1961                 try!(self.print_expr_repeat(&**element, &**count));
1962             }
1963             ast::ExprStruct(ref path, ref fields, ref wth) => {
1964                 try!(self.print_expr_struct(path, &fields[..], wth));
1965             }
1966             ast::ExprTup(ref exprs) => {
1967                 try!(self.print_expr_tup(&exprs[..]));
1968             }
1969             ast::ExprCall(ref func, ref args) => {
1970                 try!(self.print_expr_call(&**func, &args[..]));
1971             }
1972             ast::ExprMethodCall(ident, ref tys, ref args) => {
1973                 try!(self.print_expr_method_call(ident, &tys[..], &args[..]));
1974             }
1975             ast::ExprBinary(op, ref lhs, ref rhs) => {
1976                 try!(self.print_expr_binary(op, &**lhs, &**rhs));
1977             }
1978             ast::ExprUnary(op, ref expr) => {
1979                 try!(self.print_expr_unary(op, &**expr));
1980             }
1981             ast::ExprAddrOf(m, ref expr) => {
1982                 try!(self.print_expr_addr_of(m, &**expr));
1983             }
1984             ast::ExprLit(ref lit) => {
1985                 try!(self.print_literal(&**lit));
1986             }
1987             ast::ExprCast(ref expr, ref ty) => {
1988                 if let ast::ExprCast(..) = expr.node {
1989                     try!(self.print_expr(&**expr));
1990                 } else {
1991                     try!(self.print_expr_maybe_paren(&**expr));
1992                 }
1993                 try!(space(&mut self.s));
1994                 try!(self.word_space("as"));
1995                 try!(self.print_type(&**ty));
1996             }
1997             ast::ExprIf(ref test, ref blk, ref elseopt) => {
1998                 try!(self.print_if(&**test, &**blk, elseopt.as_ref().map(|e| &**e)));
1999             }
2000             ast::ExprIfLet(ref pat, ref expr, ref blk, ref elseopt) => {
2001                 try!(self.print_if_let(&**pat, &**expr, &** blk, elseopt.as_ref().map(|e| &**e)));
2002             }
2003             ast::ExprWhile(ref test, ref blk, opt_ident) => {
2004                 if let Some(ident) = opt_ident {
2005                     try!(self.print_ident(ident));
2006                     try!(self.word_space(":"));
2007                 }
2008                 try!(self.head("while"));
2009                 try!(self.print_expr(&**test));
2010                 try!(space(&mut self.s));
2011                 try!(self.print_block(&**blk));
2012             }
2013             ast::ExprWhileLet(ref pat, ref expr, ref blk, opt_ident) => {
2014                 if let Some(ident) = opt_ident {
2015                     try!(self.print_ident(ident));
2016                     try!(self.word_space(":"));
2017                 }
2018                 try!(self.head("while let"));
2019                 try!(self.print_pat(&**pat));
2020                 try!(space(&mut self.s));
2021                 try!(self.word_space("="));
2022                 try!(self.print_expr(&**expr));
2023                 try!(space(&mut self.s));
2024                 try!(self.print_block(&**blk));
2025             }
2026             ast::ExprForLoop(ref pat, ref iter, ref blk, opt_ident) => {
2027                 if let Some(ident) = opt_ident {
2028                     try!(self.print_ident(ident));
2029                     try!(self.word_space(":"));
2030                 }
2031                 try!(self.head("for"));
2032                 try!(self.print_pat(&**pat));
2033                 try!(space(&mut self.s));
2034                 try!(self.word_space("in"));
2035                 try!(self.print_expr(&**iter));
2036                 try!(space(&mut self.s));
2037                 try!(self.print_block(&**blk));
2038             }
2039             ast::ExprLoop(ref blk, opt_ident) => {
2040                 if let Some(ident) = opt_ident {
2041                     try!(self.print_ident(ident));
2042                     try!(self.word_space(":"));
2043                 }
2044                 try!(self.head("loop"));
2045                 try!(space(&mut self.s));
2046                 try!(self.print_block(&**blk));
2047             }
2048             ast::ExprMatch(ref expr, ref arms, _) => {
2049                 try!(self.cbox(indent_unit));
2050                 try!(self.ibox(4));
2051                 try!(self.word_nbsp("match"));
2052                 try!(self.print_expr(&**expr));
2053                 try!(space(&mut self.s));
2054                 try!(self.bopen());
2055                 for arm in arms {
2056                     try!(self.print_arm(arm));
2057                 }
2058                 try!(self.bclose_(expr.span, indent_unit));
2059             }
2060             ast::ExprClosure(capture_clause, ref decl, ref body) => {
2061                 try!(self.print_capture_clause(capture_clause));
2062
2063                 try!(self.print_fn_block_args(&**decl));
2064                 try!(space(&mut self.s));
2065
2066                 let default_return = match decl.output {
2067                     ast::DefaultReturn(..) => true,
2068                     _ => false
2069                 };
2070
2071                 if !default_return || !body.stmts.is_empty() || body.expr.is_none() {
2072                     try!(self.print_block_unclosed(&**body));
2073                 } else {
2074                     // we extract the block, so as not to create another set of boxes
2075                     match body.expr.as_ref().unwrap().node {
2076                         ast::ExprBlock(ref blk) => {
2077                             try!(self.print_block_unclosed(&**blk));
2078                         }
2079                         _ => {
2080                             // this is a bare expression
2081                             try!(self.print_expr(body.expr.as_ref().map(|e| &**e).unwrap()));
2082                             try!(self.end()); // need to close a box
2083                         }
2084                     }
2085                 }
2086                 // a box will be closed by print_expr, but we didn't want an overall
2087                 // wrapper so we closed the corresponding opening. so create an
2088                 // empty box to satisfy the close.
2089                 try!(self.ibox(0));
2090             }
2091             ast::ExprBlock(ref blk) => {
2092                 // containing cbox, will be closed by print-block at }
2093                 try!(self.cbox(indent_unit));
2094                 // head-box, will be closed by print-block after {
2095                 try!(self.ibox(0));
2096                 try!(self.print_block(&**blk));
2097             }
2098             ast::ExprAssign(ref lhs, ref rhs) => {
2099                 try!(self.print_expr(&**lhs));
2100                 try!(space(&mut self.s));
2101                 try!(self.word_space("="));
2102                 try!(self.print_expr(&**rhs));
2103             }
2104             ast::ExprAssignOp(op, ref lhs, ref rhs) => {
2105                 try!(self.print_expr(&**lhs));
2106                 try!(space(&mut self.s));
2107                 try!(word(&mut self.s, ast_util::binop_to_string(op.node)));
2108                 try!(self.word_space("="));
2109                 try!(self.print_expr(&**rhs));
2110             }
2111             ast::ExprField(ref expr, id) => {
2112                 try!(self.print_expr(&**expr));
2113                 try!(word(&mut self.s, "."));
2114                 try!(self.print_ident(id.node));
2115             }
2116             ast::ExprTupField(ref expr, id) => {
2117                 try!(self.print_expr(&**expr));
2118                 try!(word(&mut self.s, "."));
2119                 try!(self.print_usize(id.node));
2120             }
2121             ast::ExprIndex(ref expr, ref index) => {
2122                 try!(self.print_expr(&**expr));
2123                 try!(word(&mut self.s, "["));
2124                 try!(self.print_expr(&**index));
2125                 try!(word(&mut self.s, "]"));
2126             }
2127             ast::ExprRange(ref start, ref end) => {
2128                 if let &Some(ref e) = start {
2129                     try!(self.print_expr(&**e));
2130                 }
2131                 try!(word(&mut self.s, ".."));
2132                 if let &Some(ref e) = end {
2133                     try!(self.print_expr(&**e));
2134                 }
2135             }
2136             ast::ExprPath(None, ref path) => {
2137                 try!(self.print_path(path, true, 0))
2138             }
2139             ast::ExprPath(Some(ref qself), ref path) => {
2140                 try!(self.print_qpath(path, qself, true))
2141             }
2142             ast::ExprBreak(opt_ident) => {
2143                 try!(word(&mut self.s, "break"));
2144                 try!(space(&mut self.s));
2145                 if let Some(ident) = opt_ident {
2146                     try!(self.print_ident(ident.node));
2147                     try!(space(&mut self.s));
2148                 }
2149             }
2150             ast::ExprAgain(opt_ident) => {
2151                 try!(word(&mut self.s, "continue"));
2152                 try!(space(&mut self.s));
2153                 if let Some(ident) = opt_ident {
2154                     try!(self.print_ident(ident.node));
2155                     try!(space(&mut self.s))
2156                 }
2157             }
2158             ast::ExprRet(ref result) => {
2159                 try!(word(&mut self.s, "return"));
2160                 match *result {
2161                     Some(ref expr) => {
2162                         try!(word(&mut self.s, " "));
2163                         try!(self.print_expr(&**expr));
2164                     }
2165                     _ => ()
2166                 }
2167             }
2168             ast::ExprInlineAsm(ref a) => {
2169                 try!(word(&mut self.s, "asm!"));
2170                 try!(self.popen());
2171                 try!(self.print_string(&a.asm, a.asm_str_style));
2172                 try!(self.word_space(":"));
2173
2174                 try!(self.commasep(Inconsistent, &a.outputs,
2175                                    |s, &(ref co, ref o, is_rw)| {
2176                     match co.slice_shift_char() {
2177                         Some(('=', operand)) if is_rw => {
2178                             try!(s.print_string(&format!("+{}", operand),
2179                                                 ast::CookedStr))
2180                         }
2181                         _ => try!(s.print_string(&co, ast::CookedStr))
2182                     }
2183                     try!(s.popen());
2184                     try!(s.print_expr(&**o));
2185                     try!(s.pclose());
2186                     Ok(())
2187                 }));
2188                 try!(space(&mut self.s));
2189                 try!(self.word_space(":"));
2190
2191                 try!(self.commasep(Inconsistent, &a.inputs,
2192                                    |s, &(ref co, ref o)| {
2193                     try!(s.print_string(&co, ast::CookedStr));
2194                     try!(s.popen());
2195                     try!(s.print_expr(&**o));
2196                     try!(s.pclose());
2197                     Ok(())
2198                 }));
2199                 try!(space(&mut self.s));
2200                 try!(self.word_space(":"));
2201
2202                 try!(self.commasep(Inconsistent, &a.clobbers,
2203                                    |s, co| {
2204                     try!(s.print_string(&co, ast::CookedStr));
2205                     Ok(())
2206                 }));
2207
2208                 let mut options = vec!();
2209                 if a.volatile {
2210                     options.push("volatile");
2211                 }
2212                 if a.alignstack {
2213                     options.push("alignstack");
2214                 }
2215                 if a.dialect == ast::AsmDialect::Intel {
2216                     options.push("intel");
2217                 }
2218
2219                 if !options.is_empty() {
2220                     try!(space(&mut self.s));
2221                     try!(self.word_space(":"));
2222                     try!(self.commasep(Inconsistent, &*options,
2223                                        |s, &co| {
2224                         try!(s.print_string(co, ast::CookedStr));
2225                         Ok(())
2226                     }));
2227                 }
2228
2229                 try!(self.pclose());
2230             }
2231             ast::ExprMac(ref m) => try!(self.print_mac(m, token::Paren)),
2232             ast::ExprParen(ref e) => {
2233                 try!(self.popen());
2234                 try!(self.print_expr(&**e));
2235                 try!(self.pclose());
2236             }
2237         }
2238         try!(self.ann.post(self, NodeExpr(expr)));
2239         self.end()
2240     }
2241
2242     pub fn print_local_decl(&mut self, loc: &ast::Local) -> io::Result<()> {
2243         try!(self.print_pat(&*loc.pat));
2244         if let Some(ref ty) = loc.ty {
2245             try!(self.word_space(":"));
2246             try!(self.print_type(&**ty));
2247         }
2248         Ok(())
2249     }
2250
2251     pub fn print_decl(&mut self, decl: &ast::Decl) -> io::Result<()> {
2252         try!(self.maybe_print_comment(decl.span.lo));
2253         match decl.node {
2254             ast::DeclLocal(ref loc) => {
2255                 try!(self.space_if_not_bol());
2256                 try!(self.ibox(indent_unit));
2257                 try!(self.word_nbsp("let"));
2258
2259                 try!(self.ibox(indent_unit));
2260                 try!(self.print_local_decl(&**loc));
2261                 try!(self.end());
2262                 if let Some(ref init) = loc.init {
2263                     try!(self.nbsp());
2264                     try!(self.word_space("="));
2265                     try!(self.print_expr(&**init));
2266                 }
2267                 self.end()
2268             }
2269             ast::DeclItem(ref item) => self.print_item(&**item)
2270         }
2271     }
2272
2273     pub fn print_ident(&mut self, ident: ast::Ident) -> io::Result<()> {
2274         try!(word(&mut self.s, &ident.name.as_str()));
2275         self.ann.post(self, NodeIdent(&ident))
2276     }
2277
2278     pub fn print_usize(&mut self, i: usize) -> io::Result<()> {
2279         word(&mut self.s, &i.to_string())
2280     }
2281
2282     pub fn print_name(&mut self, name: ast::Name) -> io::Result<()> {
2283         try!(word(&mut self.s, &name.as_str()));
2284         self.ann.post(self, NodeName(&name))
2285     }
2286
2287     pub fn print_for_decl(&mut self, loc: &ast::Local,
2288                           coll: &ast::Expr) -> io::Result<()> {
2289         try!(self.print_local_decl(loc));
2290         try!(space(&mut self.s));
2291         try!(self.word_space("in"));
2292         self.print_expr(coll)
2293     }
2294
2295     fn print_path(&mut self,
2296                   path: &ast::Path,
2297                   colons_before_params: bool,
2298                   depth: usize)
2299                   -> io::Result<()>
2300     {
2301         try!(self.maybe_print_comment(path.span.lo));
2302
2303         let mut first = !path.global;
2304         for segment in &path.segments[..path.segments.len()-depth] {
2305             if first {
2306                 first = false
2307             } else {
2308                 try!(word(&mut self.s, "::"))
2309             }
2310
2311             try!(self.print_ident(segment.identifier));
2312
2313             try!(self.print_path_parameters(&segment.parameters, colons_before_params));
2314         }
2315
2316         Ok(())
2317     }
2318
2319     fn print_qpath(&mut self,
2320                    path: &ast::Path,
2321                    qself: &ast::QSelf,
2322                    colons_before_params: bool)
2323                    -> io::Result<()>
2324     {
2325         try!(word(&mut self.s, "<"));
2326         try!(self.print_type(&qself.ty));
2327         if qself.position > 0 {
2328             try!(space(&mut self.s));
2329             try!(self.word_space("as"));
2330             let depth = path.segments.len() - qself.position;
2331             try!(self.print_path(&path, false, depth));
2332         }
2333         try!(word(&mut self.s, ">"));
2334         try!(word(&mut self.s, "::"));
2335         let item_segment = path.segments.last().unwrap();
2336         try!(self.print_ident(item_segment.identifier));
2337         self.print_path_parameters(&item_segment.parameters, colons_before_params)
2338     }
2339
2340     fn print_path_parameters(&mut self,
2341                              parameters: &ast::PathParameters,
2342                              colons_before_params: bool)
2343                              -> io::Result<()>
2344     {
2345         if parameters.is_empty() {
2346             return Ok(());
2347         }
2348
2349         if colons_before_params {
2350             try!(word(&mut self.s, "::"))
2351         }
2352
2353         match *parameters {
2354             ast::AngleBracketedParameters(ref data) => {
2355                 try!(word(&mut self.s, "<"));
2356
2357                 let mut comma = false;
2358                 for lifetime in &data.lifetimes {
2359                     if comma {
2360                         try!(self.word_space(","))
2361                     }
2362                     try!(self.print_lifetime(lifetime));
2363                     comma = true;
2364                 }
2365
2366                 if !data.types.is_empty() {
2367                     if comma {
2368                         try!(self.word_space(","))
2369                     }
2370                     try!(self.commasep(
2371                         Inconsistent,
2372                         &data.types,
2373                         |s, ty| s.print_type(&**ty)));
2374                         comma = true;
2375                 }
2376
2377                 for binding in data.bindings.iter() {
2378                     if comma {
2379                         try!(self.word_space(","))
2380                     }
2381                     try!(self.print_ident(binding.ident));
2382                     try!(space(&mut self.s));
2383                     try!(self.word_space("="));
2384                     try!(self.print_type(&*binding.ty));
2385                     comma = true;
2386                 }
2387
2388                 try!(word(&mut self.s, ">"))
2389             }
2390
2391             ast::ParenthesizedParameters(ref data) => {
2392                 try!(word(&mut self.s, "("));
2393                 try!(self.commasep(
2394                     Inconsistent,
2395                     &data.inputs,
2396                     |s, ty| s.print_type(&**ty)));
2397                 try!(word(&mut self.s, ")"));
2398
2399                 match data.output {
2400                     None => { }
2401                     Some(ref ty) => {
2402                         try!(self.space_if_not_bol());
2403                         try!(self.word_space("->"));
2404                         try!(self.print_type(&**ty));
2405                     }
2406                 }
2407             }
2408         }
2409
2410         Ok(())
2411     }
2412
2413     pub fn print_pat(&mut self, pat: &ast::Pat) -> io::Result<()> {
2414         try!(self.maybe_print_comment(pat.span.lo));
2415         try!(self.ann.pre(self, NodePat(pat)));
2416         /* Pat isn't normalized, but the beauty of it
2417          is that it doesn't matter */
2418         match pat.node {
2419             ast::PatWild(ast::PatWildSingle) => try!(word(&mut self.s, "_")),
2420             ast::PatWild(ast::PatWildMulti) => try!(word(&mut self.s, "..")),
2421             ast::PatIdent(binding_mode, ref path1, ref sub) => {
2422                 match binding_mode {
2423                     ast::BindByRef(mutbl) => {
2424                         try!(self.word_nbsp("ref"));
2425                         try!(self.print_mutability(mutbl));
2426                     }
2427                     ast::BindByValue(ast::MutImmutable) => {}
2428                     ast::BindByValue(ast::MutMutable) => {
2429                         try!(self.word_nbsp("mut"));
2430                     }
2431                 }
2432                 try!(self.print_ident(path1.node));
2433                 match *sub {
2434                     Some(ref p) => {
2435                         try!(word(&mut self.s, "@"));
2436                         try!(self.print_pat(&**p));
2437                     }
2438                     None => ()
2439                 }
2440             }
2441             ast::PatEnum(ref path, ref args_) => {
2442                 try!(self.print_path(path, true, 0));
2443                 match *args_ {
2444                     None => try!(word(&mut self.s, "(..)")),
2445                     Some(ref args) => {
2446                         if !args.is_empty() {
2447                             try!(self.popen());
2448                             try!(self.commasep(Inconsistent, &args[..],
2449                                               |s, p| s.print_pat(&**p)));
2450                             try!(self.pclose());
2451                         }
2452                     }
2453                 }
2454             }
2455             ast::PatQPath(ref qself, ref path) => {
2456                 try!(self.print_qpath(path, qself, false));
2457             }
2458             ast::PatStruct(ref path, ref fields, etc) => {
2459                 try!(self.print_path(path, true, 0));
2460                 try!(self.nbsp());
2461                 try!(self.word_space("{"));
2462                 try!(self.commasep_cmnt(
2463                     Consistent, &fields[..],
2464                     |s, f| {
2465                         try!(s.cbox(indent_unit));
2466                         if !f.node.is_shorthand {
2467                             try!(s.print_ident(f.node.ident));
2468                             try!(s.word_nbsp(":"));
2469                         }
2470                         try!(s.print_pat(&*f.node.pat));
2471                         s.end()
2472                     },
2473                     |f| f.node.pat.span));
2474                 if etc {
2475                     if !fields.is_empty() { try!(self.word_space(",")); }
2476                     try!(word(&mut self.s, ".."));
2477                 }
2478                 try!(space(&mut self.s));
2479                 try!(word(&mut self.s, "}"));
2480             }
2481             ast::PatTup(ref elts) => {
2482                 try!(self.popen());
2483                 try!(self.commasep(Inconsistent,
2484                                    &elts[..],
2485                                    |s, p| s.print_pat(&**p)));
2486                 if elts.len() == 1 {
2487                     try!(word(&mut self.s, ","));
2488                 }
2489                 try!(self.pclose());
2490             }
2491             ast::PatBox(ref inner) => {
2492                 try!(word(&mut self.s, "box "));
2493                 try!(self.print_pat(&**inner));
2494             }
2495             ast::PatRegion(ref inner, mutbl) => {
2496                 try!(word(&mut self.s, "&"));
2497                 if mutbl == ast::MutMutable {
2498                     try!(word(&mut self.s, "mut "));
2499                 }
2500                 try!(self.print_pat(&**inner));
2501             }
2502             ast::PatLit(ref e) => try!(self.print_expr(&**e)),
2503             ast::PatRange(ref begin, ref end) => {
2504                 try!(self.print_expr(&**begin));
2505                 try!(space(&mut self.s));
2506                 try!(word(&mut self.s, "..."));
2507                 try!(self.print_expr(&**end));
2508             }
2509             ast::PatVec(ref before, ref slice, ref after) => {
2510                 try!(word(&mut self.s, "["));
2511                 try!(self.commasep(Inconsistent,
2512                                    &before[..],
2513                                    |s, p| s.print_pat(&**p)));
2514                 if let Some(ref p) = *slice {
2515                     if !before.is_empty() { try!(self.word_space(",")); }
2516                     try!(self.print_pat(&**p));
2517                     match **p {
2518                         ast::Pat { node: ast::PatWild(ast::PatWildMulti), .. } => {
2519                             // this case is handled by print_pat
2520                         }
2521                         _ => try!(word(&mut self.s, "..")),
2522                     }
2523                     if !after.is_empty() { try!(self.word_space(",")); }
2524                 }
2525                 try!(self.commasep(Inconsistent,
2526                                    &after[..],
2527                                    |s, p| s.print_pat(&**p)));
2528                 try!(word(&mut self.s, "]"));
2529             }
2530             ast::PatMac(ref m) => try!(self.print_mac(m, token::Paren)),
2531         }
2532         self.ann.post(self, NodePat(pat))
2533     }
2534
2535     fn print_arm(&mut self, arm: &ast::Arm) -> io::Result<()> {
2536         // I have no idea why this check is necessary, but here it
2537         // is :(
2538         if arm.attrs.is_empty() {
2539             try!(space(&mut self.s));
2540         }
2541         try!(self.cbox(indent_unit));
2542         try!(self.ibox(0));
2543         try!(self.print_outer_attributes(&arm.attrs));
2544         let mut first = true;
2545         for p in &arm.pats {
2546             if first {
2547                 first = false;
2548             } else {
2549                 try!(space(&mut self.s));
2550                 try!(self.word_space("|"));
2551             }
2552             try!(self.print_pat(&**p));
2553         }
2554         try!(space(&mut self.s));
2555         if let Some(ref e) = arm.guard {
2556             try!(self.word_space("if"));
2557             try!(self.print_expr(&**e));
2558             try!(space(&mut self.s));
2559         }
2560         try!(self.word_space("=>"));
2561
2562         match arm.body.node {
2563             ast::ExprBlock(ref blk) => {
2564                 // the block will close the pattern's ibox
2565                 try!(self.print_block_unclosed_indent(&**blk, indent_unit));
2566
2567                 // If it is a user-provided unsafe block, print a comma after it
2568                 if let ast::UnsafeBlock(ast::UserProvided) = blk.rules {
2569                     try!(word(&mut self.s, ","));
2570                 }
2571             }
2572             _ => {
2573                 try!(self.end()); // close the ibox for the pattern
2574                 try!(self.print_expr(&*arm.body));
2575                 try!(word(&mut self.s, ","));
2576             }
2577         }
2578         self.end() // close enclosing cbox
2579     }
2580
2581     // Returns whether it printed anything
2582     fn print_explicit_self(&mut self,
2583                            explicit_self: &ast::ExplicitSelf_,
2584                            mutbl: ast::Mutability) -> io::Result<bool> {
2585         try!(self.print_mutability(mutbl));
2586         match *explicit_self {
2587             ast::SelfStatic => { return Ok(false); }
2588             ast::SelfValue(_) => {
2589                 try!(word(&mut self.s, "self"));
2590             }
2591             ast::SelfRegion(ref lt, m, _) => {
2592                 try!(word(&mut self.s, "&"));
2593                 try!(self.print_opt_lifetime(lt));
2594                 try!(self.print_mutability(m));
2595                 try!(word(&mut self.s, "self"));
2596             }
2597             ast::SelfExplicit(ref typ, _) => {
2598                 try!(word(&mut self.s, "self"));
2599                 try!(self.word_space(":"));
2600                 try!(self.print_type(&**typ));
2601             }
2602         }
2603         return Ok(true);
2604     }
2605
2606     pub fn print_fn(&mut self,
2607                     decl: &ast::FnDecl,
2608                     unsafety: ast::Unsafety,
2609                     constness: ast::Constness,
2610                     abi: abi::Abi,
2611                     name: Option<ast::Ident>,
2612                     generics: &ast::Generics,
2613                     opt_explicit_self: Option<&ast::ExplicitSelf_>,
2614                     vis: ast::Visibility) -> io::Result<()> {
2615         try!(self.print_fn_header_info(unsafety, constness, abi, vis));
2616
2617         if let Some(name) = name {
2618             try!(self.nbsp());
2619             try!(self.print_ident(name));
2620         }
2621         try!(self.print_generics(generics));
2622         try!(self.print_fn_args_and_ret(decl, opt_explicit_self));
2623         self.print_where_clause(&generics.where_clause)
2624     }
2625
2626     pub fn print_fn_args(&mut self, decl: &ast::FnDecl,
2627                          opt_explicit_self: Option<&ast::ExplicitSelf_>)
2628         -> io::Result<()> {
2629         // It is unfortunate to duplicate the commasep logic, but we want the
2630         // self type and the args all in the same box.
2631         try!(self.rbox(0, Inconsistent));
2632         let mut first = true;
2633         if let Some(explicit_self) = opt_explicit_self {
2634             let m = match explicit_self {
2635                 &ast::SelfStatic => ast::MutImmutable,
2636                 _ => match decl.inputs[0].pat.node {
2637                     ast::PatIdent(ast::BindByValue(m), _, _) => m,
2638                     _ => ast::MutImmutable
2639                 }
2640             };
2641             first = !try!(self.print_explicit_self(explicit_self, m));
2642         }
2643
2644         // HACK(eddyb) ignore the separately printed self argument.
2645         let args = if first {
2646             &decl.inputs[..]
2647         } else {
2648             &decl.inputs[1..]
2649         };
2650
2651         for arg in args {
2652             if first { first = false; } else { try!(self.word_space(",")); }
2653             try!(self.print_arg(arg));
2654         }
2655
2656         self.end()
2657     }
2658
2659     pub fn print_fn_args_and_ret(&mut self, decl: &ast::FnDecl,
2660                                  opt_explicit_self: Option<&ast::ExplicitSelf_>)
2661         -> io::Result<()> {
2662         try!(self.popen());
2663         try!(self.print_fn_args(decl, opt_explicit_self));
2664         if decl.variadic {
2665             try!(word(&mut self.s, ", ..."));
2666         }
2667         try!(self.pclose());
2668
2669         self.print_fn_output(decl)
2670     }
2671
2672     pub fn print_fn_block_args(
2673             &mut self,
2674             decl: &ast::FnDecl)
2675             -> io::Result<()> {
2676         try!(word(&mut self.s, "|"));
2677         try!(self.print_fn_args(decl, None));
2678         try!(word(&mut self.s, "|"));
2679
2680         if let ast::DefaultReturn(..) = decl.output {
2681             return Ok(());
2682         }
2683
2684         try!(self.space_if_not_bol());
2685         try!(self.word_space("->"));
2686         match decl.output {
2687             ast::Return(ref ty) => {
2688                 try!(self.print_type(&**ty));
2689                 self.maybe_print_comment(ty.span.lo)
2690             }
2691             ast::DefaultReturn(..) => unreachable!(),
2692             ast::NoReturn(span) => {
2693                 try!(self.word_nbsp("!"));
2694                 self.maybe_print_comment(span.lo)
2695             }
2696         }
2697     }
2698
2699     pub fn print_capture_clause(&mut self, capture_clause: ast::CaptureClause)
2700                                 -> io::Result<()> {
2701         match capture_clause {
2702             ast::CaptureByValue => self.word_space("move"),
2703             ast::CaptureByRef => Ok(()),
2704         }
2705     }
2706
2707     pub fn print_bounds(&mut self,
2708                         prefix: &str,
2709                         bounds: &[ast::TyParamBound])
2710                         -> io::Result<()> {
2711         if !bounds.is_empty() {
2712             try!(word(&mut self.s, prefix));
2713             let mut first = true;
2714             for bound in bounds {
2715                 try!(self.nbsp());
2716                 if first {
2717                     first = false;
2718                 } else {
2719                     try!(self.word_space("+"));
2720                 }
2721
2722                 try!(match *bound {
2723                     TraitTyParamBound(ref tref, TraitBoundModifier::None) => {
2724                         self.print_poly_trait_ref(tref)
2725                     }
2726                     TraitTyParamBound(ref tref, TraitBoundModifier::Maybe) => {
2727                         try!(word(&mut self.s, "?"));
2728                         self.print_poly_trait_ref(tref)
2729                     }
2730                     RegionTyParamBound(ref lt) => {
2731                         self.print_lifetime(lt)
2732                     }
2733                 })
2734             }
2735             Ok(())
2736         } else {
2737             Ok(())
2738         }
2739     }
2740
2741     pub fn print_lifetime(&mut self,
2742                           lifetime: &ast::Lifetime)
2743                           -> io::Result<()>
2744     {
2745         self.print_name(lifetime.name)
2746     }
2747
2748     pub fn print_lifetime_def(&mut self,
2749                               lifetime: &ast::LifetimeDef)
2750                               -> io::Result<()>
2751     {
2752         try!(self.print_lifetime(&lifetime.lifetime));
2753         let mut sep = ":";
2754         for v in &lifetime.bounds {
2755             try!(word(&mut self.s, sep));
2756             try!(self.print_lifetime(v));
2757             sep = "+";
2758         }
2759         Ok(())
2760     }
2761
2762     pub fn print_generics(&mut self,
2763                           generics: &ast::Generics)
2764                           -> io::Result<()>
2765     {
2766         let total = generics.lifetimes.len() + generics.ty_params.len();
2767         if total == 0 {
2768             return Ok(());
2769         }
2770
2771         try!(word(&mut self.s, "<"));
2772
2773         let mut ints = Vec::new();
2774         for i in 0..total {
2775             ints.push(i);
2776         }
2777
2778         try!(self.commasep(Inconsistent, &ints[..], |s, &idx| {
2779             if idx < generics.lifetimes.len() {
2780                 let lifetime = &generics.lifetimes[idx];
2781                 s.print_lifetime_def(lifetime)
2782             } else {
2783                 let idx = idx - generics.lifetimes.len();
2784                 let param = &generics.ty_params[idx];
2785                 s.print_ty_param(param)
2786             }
2787         }));
2788
2789         try!(word(&mut self.s, ">"));
2790         Ok(())
2791     }
2792
2793     pub fn print_ty_param(&mut self, param: &ast::TyParam) -> io::Result<()> {
2794         try!(self.print_ident(param.ident));
2795         try!(self.print_bounds(":", &param.bounds));
2796         match param.default {
2797             Some(ref default) => {
2798                 try!(space(&mut self.s));
2799                 try!(self.word_space("="));
2800                 self.print_type(&**default)
2801             }
2802             _ => Ok(())
2803         }
2804     }
2805
2806     pub fn print_where_clause(&mut self, where_clause: &ast::WhereClause)
2807                               -> io::Result<()> {
2808         if where_clause.predicates.is_empty() {
2809             return Ok(())
2810         }
2811
2812         try!(space(&mut self.s));
2813         try!(self.word_space("where"));
2814
2815         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2816             if i != 0 {
2817                 try!(self.word_space(","));
2818             }
2819
2820             match predicate {
2821                 &ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate{ref bound_lifetimes,
2822                                                                               ref bounded_ty,
2823                                                                               ref bounds,
2824                                                                               ..}) => {
2825                     try!(self.print_formal_lifetime_list(bound_lifetimes));
2826                     try!(self.print_type(&**bounded_ty));
2827                     try!(self.print_bounds(":", bounds));
2828                 }
2829                 &ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate{ref lifetime,
2830                                                                                 ref bounds,
2831                                                                                 ..}) => {
2832                     try!(self.print_lifetime(lifetime));
2833                     try!(word(&mut self.s, ":"));
2834
2835                     for (i, bound) in bounds.iter().enumerate() {
2836                         try!(self.print_lifetime(bound));
2837
2838                         if i != 0 {
2839                             try!(word(&mut self.s, ":"));
2840                         }
2841                     }
2842                 }
2843                 &ast::WherePredicate::EqPredicate(ast::WhereEqPredicate{ref path, ref ty, ..}) => {
2844                     try!(self.print_path(path, false, 0));
2845                     try!(space(&mut self.s));
2846                     try!(self.word_space("="));
2847                     try!(self.print_type(&**ty));
2848                 }
2849             }
2850         }
2851
2852         Ok(())
2853     }
2854
2855     pub fn print_view_path(&mut self, vp: &ast::ViewPath) -> io::Result<()> {
2856         match vp.node {
2857             ast::ViewPathSimple(ident, ref path) => {
2858                 try!(self.print_path(path, false, 0));
2859
2860                 // FIXME(#6993) can't compare identifiers directly here
2861                 if path.segments.last().unwrap().identifier.name !=
2862                         ident.name {
2863                     try!(space(&mut self.s));
2864                     try!(self.word_space("as"));
2865                     try!(self.print_ident(ident));
2866                 }
2867
2868                 Ok(())
2869             }
2870
2871             ast::ViewPathGlob(ref path) => {
2872                 try!(self.print_path(path, false, 0));
2873                 word(&mut self.s, "::*")
2874             }
2875
2876             ast::ViewPathList(ref path, ref idents) => {
2877                 if path.segments.is_empty() {
2878                     try!(word(&mut self.s, "{"));
2879                 } else {
2880                     try!(self.print_path(path, false, 0));
2881                     try!(word(&mut self.s, "::{"));
2882                 }
2883                 try!(self.commasep(Inconsistent, &idents[..], |s, w| {
2884                     match w.node {
2885                         ast::PathListIdent { name, rename, .. } => {
2886                             try!(s.print_ident(name));
2887                             if let Some(ident) = rename {
2888                                 try!(space(&mut s.s));
2889                                 try!(s.word_space("as"));
2890                                 try!(s.print_ident(ident));
2891                             }
2892                             Ok(())
2893                         },
2894                         ast::PathListMod { rename, .. } => {
2895                             try!(word(&mut s.s, "self"));
2896                             if let Some(ident) = rename {
2897                                 try!(space(&mut s.s));
2898                                 try!(s.word_space("as"));
2899                                 try!(s.print_ident(ident));
2900                             }
2901                             Ok(())
2902                         }
2903                     }
2904                 }));
2905                 word(&mut self.s, "}")
2906             }
2907         }
2908     }
2909
2910     pub fn print_mutability(&mut self,
2911                             mutbl: ast::Mutability) -> io::Result<()> {
2912         match mutbl {
2913             ast::MutMutable => self.word_nbsp("mut"),
2914             ast::MutImmutable => Ok(()),
2915         }
2916     }
2917
2918     pub fn print_mt(&mut self, mt: &ast::MutTy) -> io::Result<()> {
2919         try!(self.print_mutability(mt.mutbl));
2920         self.print_type(&*mt.ty)
2921     }
2922
2923     pub fn print_arg(&mut self, input: &ast::Arg) -> io::Result<()> {
2924         try!(self.ibox(indent_unit));
2925         match input.ty.node {
2926             ast::TyInfer => try!(self.print_pat(&*input.pat)),
2927             _ => {
2928                 match input.pat.node {
2929                     ast::PatIdent(_, ref path1, _) if
2930                         path1.node.name ==
2931                             parse::token::special_idents::invalid.name => {
2932                         // Do nothing.
2933                     }
2934                     _ => {
2935                         try!(self.print_pat(&*input.pat));
2936                         try!(word(&mut self.s, ":"));
2937                         try!(space(&mut self.s));
2938                     }
2939                 }
2940                 try!(self.print_type(&*input.ty));
2941             }
2942         }
2943         self.end()
2944     }
2945
2946     pub fn print_fn_output(&mut self, decl: &ast::FnDecl) -> io::Result<()> {
2947         if let ast::DefaultReturn(..) = decl.output {
2948             return Ok(());
2949         }
2950
2951         try!(self.space_if_not_bol());
2952         try!(self.ibox(indent_unit));
2953         try!(self.word_space("->"));
2954         match decl.output {
2955             ast::NoReturn(_) =>
2956                 try!(self.word_nbsp("!")),
2957             ast::DefaultReturn(..) => unreachable!(),
2958             ast::Return(ref ty) =>
2959                 try!(self.print_type(&**ty))
2960         }
2961         try!(self.end());
2962
2963         match decl.output {
2964             ast::Return(ref output) => self.maybe_print_comment(output.span.lo),
2965             _ => Ok(())
2966         }
2967     }
2968
2969     pub fn print_ty_fn(&mut self,
2970                        abi: abi::Abi,
2971                        unsafety: ast::Unsafety,
2972                        decl: &ast::FnDecl,
2973                        name: Option<ast::Ident>,
2974                        generics: &ast::Generics,
2975                        opt_explicit_self: Option<&ast::ExplicitSelf_>)
2976                        -> io::Result<()> {
2977         try!(self.ibox(indent_unit));
2978         if !generics.lifetimes.is_empty() || !generics.ty_params.is_empty() {
2979             try!(word(&mut self.s, "for"));
2980             try!(self.print_generics(generics));
2981         }
2982         let generics = ast::Generics {
2983             lifetimes: Vec::new(),
2984             ty_params: OwnedSlice::empty(),
2985             where_clause: ast::WhereClause {
2986                 id: ast::DUMMY_NODE_ID,
2987                 predicates: Vec::new(),
2988             },
2989         };
2990         try!(self.print_fn(decl,
2991                            unsafety,
2992                            ast::Constness::NotConst,
2993                            abi,
2994                            name,
2995                            &generics,
2996                            opt_explicit_self,
2997                            ast::Inherited));
2998         self.end()
2999     }
3000
3001     pub fn maybe_print_trailing_comment(&mut self, span: codemap::Span,
3002                                         next_pos: Option<BytePos>)
3003         -> io::Result<()> {
3004         let cm = match self.cm {
3005             Some(cm) => cm,
3006             _ => return Ok(())
3007         };
3008         match self.next_comment() {
3009             Some(ref cmnt) => {
3010                 if (*cmnt).style != comments::Trailing { return Ok(()) }
3011                 let span_line = cm.lookup_char_pos(span.hi);
3012                 let comment_line = cm.lookup_char_pos((*cmnt).pos);
3013                 let mut next = (*cmnt).pos + BytePos(1);
3014                 match next_pos { None => (), Some(p) => next = p }
3015                 if span.hi < (*cmnt).pos && (*cmnt).pos < next &&
3016                     span_line.line == comment_line.line {
3017                         try!(self.print_comment(cmnt));
3018                         self.cur_cmnt_and_lit.cur_cmnt += 1;
3019                     }
3020             }
3021             _ => ()
3022         }
3023         Ok(())
3024     }
3025
3026     pub fn print_remaining_comments(&mut self) -> io::Result<()> {
3027         // If there aren't any remaining comments, then we need to manually
3028         // make sure there is a line break at the end.
3029         if self.next_comment().is_none() {
3030             try!(hardbreak(&mut self.s));
3031         }
3032         loop {
3033             match self.next_comment() {
3034                 Some(ref cmnt) => {
3035                     try!(self.print_comment(cmnt));
3036                     self.cur_cmnt_and_lit.cur_cmnt += 1;
3037                 }
3038                 _ => break
3039             }
3040         }
3041         Ok(())
3042     }
3043
3044     pub fn print_opt_abi_and_extern_if_nondefault(&mut self,
3045                                                   opt_abi: Option<abi::Abi>)
3046         -> io::Result<()> {
3047         match opt_abi {
3048             Some(abi::Rust) => Ok(()),
3049             Some(abi) => {
3050                 try!(self.word_nbsp("extern"));
3051                 self.word_nbsp(&abi.to_string())
3052             }
3053             None => Ok(())
3054         }
3055     }
3056
3057     pub fn print_extern_opt_abi(&mut self,
3058                                 opt_abi: Option<abi::Abi>) -> io::Result<()> {
3059         match opt_abi {
3060             Some(abi) => {
3061                 try!(self.word_nbsp("extern"));
3062                 self.word_nbsp(&abi.to_string())
3063             }
3064             None => Ok(())
3065         }
3066     }
3067
3068     pub fn print_fn_header_info(&mut self,
3069                                 unsafety: ast::Unsafety,
3070                                 constness: ast::Constness,
3071                                 abi: abi::Abi,
3072                                 vis: ast::Visibility) -> io::Result<()> {
3073         try!(word(&mut self.s, &visibility_qualified(vis, "")));
3074         try!(self.print_unsafety(unsafety));
3075
3076         match constness {
3077             ast::Constness::NotConst => {}
3078             ast::Constness::Const => try!(self.word_nbsp("const"))
3079         }
3080
3081         if abi != abi::Rust {
3082             try!(self.word_nbsp("extern"));
3083             try!(self.word_nbsp(&abi.to_string()));
3084         }
3085
3086         word(&mut self.s, "fn")
3087     }
3088
3089     pub fn print_unsafety(&mut self, s: ast::Unsafety) -> io::Result<()> {
3090         match s {
3091             ast::Unsafety::Normal => Ok(()),
3092             ast::Unsafety::Unsafe => self.word_nbsp("unsafe"),
3093         }
3094     }
3095 }
3096
3097 fn repeat(s: &str, n: usize) -> String { iter::repeat(s).take(n).collect() }
3098
3099 #[cfg(test)]
3100 mod tests {
3101     use super::*;
3102
3103     use ast;
3104     use ast_util;
3105     use codemap;
3106     use parse::token;
3107
3108     #[test]
3109     fn test_fun_to_string() {
3110         let abba_ident = token::str_to_ident("abba");
3111
3112         let decl = ast::FnDecl {
3113             inputs: Vec::new(),
3114             output: ast::DefaultReturn(codemap::DUMMY_SP),
3115             variadic: false
3116         };
3117         let generics = ast_util::empty_generics();
3118         assert_eq!(fun_to_string(&decl, ast::Unsafety::Normal,
3119                                  ast::Constness::NotConst,
3120                                  abba_ident,
3121                                  None, &generics),
3122                    "fn abba()");
3123     }
3124
3125     #[test]
3126     fn test_variant_to_string() {
3127         let ident = token::str_to_ident("principal_skinner");
3128
3129         let var = codemap::respan(codemap::DUMMY_SP, ast::Variant_ {
3130             name: ident,
3131             attrs: Vec::new(),
3132             // making this up as I go.... ?
3133             kind: ast::TupleVariantKind(Vec::new()),
3134             id: 0,
3135             disr_expr: None,
3136         });
3137
3138         let varstr = variant_to_string(&var);
3139         assert_eq!(varstr, "principal_skinner");
3140     }
3141
3142     #[test]
3143     fn test_signed_int_to_string() {
3144         let pos_int = ast::LitInt(42, ast::SignedIntLit(ast::TyI32, ast::Plus));
3145         let neg_int = ast::LitInt((!42 + 1) as u64, ast::SignedIntLit(ast::TyI32, ast::Minus));
3146         assert_eq!(format!("-{}", lit_to_string(&codemap::dummy_spanned(pos_int))),
3147                    lit_to_string(&codemap::dummy_spanned(neg_int)));
3148     }
3149 }