src/libsyntax/print/pprust.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 pub use self::AnnNode::*;
  12
  13 use abi::{self, Abi};
  14 use ast::{self, BlockCheckMode, PatKind, RangeEnd};
  15 use ast::{SelfKind, RegionTyParamBound, TraitTyParamBound, TraitBoundModifier};
  16 use ast::Attribute;
  17 use util::parser::AssocOp;
  18 use attr;
  19 use codemap::{self, CodeMap};
  20 use syntax_pos::{self, BytePos};
  21 use parse::token::{self, BinOpToken, Token};
  22 use parse::lexer::comments;
  23 use parse::{self, ParseSess};
  24 use print::pp::{self, break_offset, word, space, zerobreak, hardbreak};
  25 use print::pp::{Breaks, eof};
  26 use print::pp::Breaks::{Consistent, Inconsistent};
  27 use ptr::P;
  28 use std_inject;
  29 use symbol::{Symbol, keywords};
  30 use syntax_pos::DUMMY_SP;
  31 use tokenstream::{self, TokenTree};
  32
  33 use std::ascii;
  34 use std::io::{self, Write, Read};
  35 use std::iter;
  36
  37 pub enum AnnNode<'a> {
  38     NodeIdent(&'a ast::Ident),
  39     NodeName(&'a ast::Name),
  40     NodeBlock(&'a ast::Block),
  41     NodeItem(&'a ast::Item),
  42     NodeSubItem(ast::NodeId),
  43     NodeExpr(&'a ast::Expr),
  44     NodePat(&'a ast::Pat),
  45 }
  46
  47 pub trait PpAnn {
  48     fn pre(&self, _state: &mut State, _node: AnnNode) -> io::Result<()> { Ok(()) }
  49     fn post(&self, _state: &mut State, _node: AnnNode) -> io::Result<()> { Ok(()) }
  50 }
  51
  52 #[derive(Copy, Clone)]
  53 pub struct NoAnn;
  54
  55 impl PpAnn for NoAnn {}
  56
  57 #[derive(Copy, Clone)]
  58 pub struct CurrentCommentAndLiteral {
  59     pub cur_cmnt: usize,
  60     pub cur_lit: usize,
  61 }
  62
  63 pub struct State<'a> {
  64     pub s: pp::Printer<'a>,
  65     cm: Option<&'a CodeMap>,
  66     comments: Option<Vec<comments::Comment> >,
  67     literals: Option<Vec<comments::Literal> >,
  68     cur_cmnt_and_lit: CurrentCommentAndLiteral,
  69     boxes: Vec<pp::Breaks>,
  70     ann: &'a (PpAnn+'a),
  71 }
  72
  73 pub fn rust_printer<'a>(writer: Box<Write+'a>) -> State<'a> {
  74     static NO_ANN: NoAnn = NoAnn;
  75     rust_printer_annotated(writer, &NO_ANN)
  76 }
  77
  78 pub fn rust_printer_annotated<'a>(writer: Box<Write+'a>,
  79                                   ann: &'a PpAnn) -> State<'a> {
  80     State {
  81         s: pp::mk_printer(writer, DEFAULT_COLUMNS),
  82         cm: None,
  83         comments: None,
  84         literals: None,
  85         cur_cmnt_and_lit: CurrentCommentAndLiteral {
  86             cur_cmnt: 0,
  87             cur_lit: 0
  88         },
  89         boxes: Vec::new(),
  90         ann: ann,
  91     }
  92 }
  93
  94 pub const INDENT_UNIT: usize = 4;
  95
  96 pub const DEFAULT_COLUMNS: usize = 78;
  97
  98 /// Requires you to pass an input filename and reader so that
  99 /// it can scan the input text for comments and literals to
 100 /// copy forward.
 101 pub fn print_crate<'a>(cm: &'a CodeMap,
 102                        sess: &ParseSess,
 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, sess, filename, input, out, ann, is_expanded);
 110
 111     if is_expanded && !std_inject::injected_crate_name(krate).is_none() {
 112         // We need to print `#![no_std]` (and its feature gate) so that
 113         // compiling pretty-printed source won't inject libstd again.
 114         // However we don't want these attributes in the AST because
 115         // of the feature gate, so we fake them up here.
 116
 117         // #![feature(prelude_import)]
 118         let prelude_import_meta = attr::mk_list_word_item(Symbol::intern("prelude_import"));
 119         let list = attr::mk_list_item(Symbol::intern("feature"), vec![prelude_import_meta]);
 120         let fake_attr = attr::mk_attr_inner(DUMMY_SP, attr::mk_attr_id(), list);
 121         s.print_attribute(&fake_attr)?;
 122
 123         // #![no_std]
 124         let no_std_meta = attr::mk_word_item(Symbol::intern("no_std"));
 125         let fake_attr = attr::mk_attr_inner(DUMMY_SP, attr::mk_attr_id(), no_std_meta);
 126         s.print_attribute(&fake_attr)?;
 127     }
 128
 129     s.print_mod(&krate.module, &krate.attrs)?;
 130     s.print_remaining_comments()?;
 131     eof(&mut s.s)
 132 }
 133
 134 impl<'a> State<'a> {
 135     pub fn new_from_input(cm: &'a CodeMap,
 136                           sess: &ParseSess,
 137                           filename: String,
 138                           input: &mut Read,
 139                           out: Box<Write+'a>,
 140                           ann: &'a PpAnn,
 141                           is_expanded: bool) -> State<'a> {
 142         let (cmnts, lits) = comments::gather_comments_and_literals(sess, filename, input);
 143
 144         State::new(
 145             cm,
 146             out,
 147             ann,
 148             Some(cmnts),
 149             // If the code is post expansion, don't use the table of
 150             // literals, since it doesn't correspond with the literals
 151             // in the AST anymore.
 152             if is_expanded { None } else { Some(lits) })
 153     }
 154
 155     pub fn new(cm: &'a CodeMap,
 156                out: Box<Write+'a>,
 157                ann: &'a PpAnn,
 158                comments: Option<Vec<comments::Comment>>,
 159                literals: Option<Vec<comments::Literal>>) -> State<'a> {
 160         State {
 161             s: pp::mk_printer(out, DEFAULT_COLUMNS),
 162             cm: Some(cm),
 163             comments: comments,
 164             literals: literals,
 165             cur_cmnt_and_lit: CurrentCommentAndLiteral {
 166                 cur_cmnt: 0,
 167                 cur_lit: 0
 168             },
 169             boxes: Vec::new(),
 170             ann: ann,
 171         }
 172     }
 173 }
 174
 175 pub fn to_string<F>(f: F) -> String where
 176     F: FnOnce(&mut State) -> io::Result<()>,
 177 {
 178     let mut wr = Vec::new();
 179     {
 180         let mut printer = rust_printer(Box::new(&mut wr));
 181         f(&mut printer).unwrap();
 182         eof(&mut printer.s).unwrap();
 183     }
 184     String::from_utf8(wr).unwrap()
 185 }
 186
 187 pub fn binop_to_string(op: BinOpToken) -> &'static str {
 188     match op {
 189         token::Plus     => "+",
 190         token::Minus    => "-",
 191         token::Star     => "*",
 192         token::Slash    => "/",
 193         token::Percent  => "%",
 194         token::Caret    => "^",
 195         token::And      => "&",
 196         token::Or       => "|",
 197         token::Shl      => "<<",
 198         token::Shr      => ">>",
 199     }
 200 }
 201
 202 pub fn token_to_string(tok: &Token) -> String {
 203     match *tok {
 204         token::Eq                   => "=".to_string(),
 205         token::Lt                   => "<".to_string(),
 206         token::Le                   => "<=".to_string(),
 207         token::EqEq                 => "==".to_string(),
 208         token::Ne                   => "!=".to_string(),
 209         token::Ge                   => ">=".to_string(),
 210         token::Gt                   => ">".to_string(),
 211         token::Not                  => "!".to_string(),
 212         token::Tilde                => "~".to_string(),
 213         token::OrOr                 => "||".to_string(),
 214         token::AndAnd               => "&&".to_string(),
 215         token::BinOp(op)            => binop_to_string(op).to_string(),
 216         token::BinOpEq(op)          => format!("{}=", binop_to_string(op)),
 217
 218         /* Structural symbols */
 219         token::At                   => "@".to_string(),
 220         token::Dot                  => ".".to_string(),
 221         token::DotDot               => "..".to_string(),
 222         token::DotDotDot            => "...".to_string(),
 223         token::Comma                => ",".to_string(),
 224         token::Semi                 => ";".to_string(),
 225         token::Colon                => ":".to_string(),
 226         token::ModSep               => "::".to_string(),
 227         token::RArrow               => "->".to_string(),
 228         token::LArrow               => "<-".to_string(),
 229         token::FatArrow             => "=>".to_string(),
 230         token::OpenDelim(token::Paren) => "(".to_string(),
 231         token::CloseDelim(token::Paren) => ")".to_string(),
 232         token::OpenDelim(token::Bracket) => "[".to_string(),
 233         token::CloseDelim(token::Bracket) => "]".to_string(),
 234         token::OpenDelim(token::Brace) => "{".to_string(),
 235         token::CloseDelim(token::Brace) => "}".to_string(),
 236         token::OpenDelim(token::NoDelim) => " ".to_string(),
 237         token::CloseDelim(token::NoDelim) => " ".to_string(),
 238         token::Pound                => "#".to_string(),
 239         token::Dollar               => "$".to_string(),
 240         token::Question             => "?".to_string(),
 241
 242         /* Literals */
 243         token::Literal(lit, suf) => {
 244             let mut out = match lit {
 245                 token::Byte(b)           => format!("b'{}'", b),
 246                 token::Char(c)           => format!("'{}'", c),
 247                 token::Float(c)          => c.to_string(),
 248                 token::Integer(c)        => c.to_string(),
 249                 token::Str_(s)           => format!("\"{}\"", s),
 250                 token::StrRaw(s, n)      => format!("r{delim}\"{string}\"{delim}",
 251                                                     delim=repeat("#", n),
 252                                                     string=s),
 253                 token::ByteStr(v)         => format!("b\"{}\"", v),
 254                 token::ByteStrRaw(s, n)   => format!("br{delim}\"{string}\"{delim}",
 255                                                     delim=repeat("#", n),
 256                                                     string=s),
 257             };
 258
 259             if let Some(s) = suf {
 260                 out.push_str(&s.as_str())
 261             }
 262
 263             out
 264         }
 265
 266         /* Name components */
 267         token::Ident(s)             => s.to_string(),
 268         token::Lifetime(s)          => s.to_string(),
 269         token::Underscore           => "_".to_string(),
 270
 271         /* Other */
 272         token::DocComment(s)        => s.to_string(),
 273         token::SubstNt(s)           => format!("${}", s),
 274         token::Eof                  => "<eof>".to_string(),
 275         token::Whitespace           => " ".to_string(),
 276         token::Comment              => "/* */".to_string(),
 277         token::Shebang(s)           => format!("/* shebang: {}*/", s),
 278
 279         token::Interpolated(ref nt) => match **nt {
 280             token::NtExpr(ref e)        => expr_to_string(&e),
 281             token::NtMeta(ref e)        => meta_item_to_string(&e),
 282             token::NtTy(ref e)          => ty_to_string(&e),
 283             token::NtPath(ref e)        => path_to_string(&e),
 284             token::NtItem(ref e)        => item_to_string(&e),
 285             token::NtBlock(ref e)       => block_to_string(&e),
 286             token::NtStmt(ref e)        => stmt_to_string(&e),
 287             token::NtPat(ref e)         => pat_to_string(&e),
 288             token::NtIdent(ref e)       => ident_to_string(e.node),
 289             token::NtTT(ref tree)       => tt_to_string(tree.clone()),
 290             token::NtArm(ref e)         => arm_to_string(&e),
 291             token::NtImplItem(ref e)    => impl_item_to_string(&e),
 292             token::NtTraitItem(ref e)   => trait_item_to_string(&e),
 293             token::NtGenerics(ref e)    => generics_to_string(&e),
 294             token::NtWhereClause(ref e) => where_clause_to_string(&e),
 295             token::NtArg(ref e)         => arg_to_string(&e),
 296         }
 297     }
 298 }
 299
 300 pub fn ty_to_string(ty: &ast::Ty) -> String {
 301     to_string(|s| s.print_type(ty))
 302 }
 303
 304 pub fn bounds_to_string(bounds: &[ast::TyParamBound]) -> String {
 305     to_string(|s| s.print_bounds("", bounds))
 306 }
 307
 308 pub fn pat_to_string(pat: &ast::Pat) -> String {
 309     to_string(|s| s.print_pat(pat))
 310 }
 311
 312 pub fn arm_to_string(arm: &ast::Arm) -> String {
 313     to_string(|s| s.print_arm(arm))
 314 }
 315
 316 pub fn expr_to_string(e: &ast::Expr) -> String {
 317     to_string(|s| s.print_expr(e))
 318 }
 319
 320 pub fn lifetime_to_string(e: &ast::Lifetime) -> String {
 321     to_string(|s| s.print_lifetime(e))
 322 }
 323
 324 pub fn tt_to_string(tt: tokenstream::TokenTree) -> String {
 325     to_string(|s| s.print_tt(tt))
 326 }
 327
 328 pub fn tts_to_string(tts: &[tokenstream::TokenTree]) -> String {
 329     to_string(|s| s.print_tts(tts.iter().cloned().collect()))
 330 }
 331
 332 pub fn stmt_to_string(stmt: &ast::Stmt) -> String {
 333     to_string(|s| s.print_stmt(stmt))
 334 }
 335
 336 pub fn attr_to_string(attr: &ast::Attribute) -> String {
 337     to_string(|s| s.print_attribute(attr))
 338 }
 339
 340 pub fn item_to_string(i: &ast::Item) -> String {
 341     to_string(|s| s.print_item(i))
 342 }
 343
 344 pub fn impl_item_to_string(i: &ast::ImplItem) -> String {
 345     to_string(|s| s.print_impl_item(i))
 346 }
 347
 348 pub fn trait_item_to_string(i: &ast::TraitItem) -> String {
 349     to_string(|s| s.print_trait_item(i))
 350 }
 351
 352 pub fn generics_to_string(generics: &ast::Generics) -> String {
 353     to_string(|s| s.print_generics(generics))
 354 }
 355
 356 pub fn where_clause_to_string(i: &ast::WhereClause) -> String {
 357     to_string(|s| s.print_where_clause(i))
 358 }
 359
 360 pub fn fn_block_to_string(p: &ast::FnDecl) -> String {
 361     to_string(|s| s.print_fn_block_args(p))
 362 }
 363
 364 pub fn path_to_string(p: &ast::Path) -> String {
 365     to_string(|s| s.print_path(p, false, 0, false))
 366 }
 367
 368 pub fn ident_to_string(id: ast::Ident) -> String {
 369     to_string(|s| s.print_ident(id))
 370 }
 371
 372 pub fn fun_to_string(decl: &ast::FnDecl,
 373                      unsafety: ast::Unsafety,
 374                      constness: ast::Constness,
 375                      name: ast::Ident,
 376                      generics: &ast::Generics)
 377                      -> String {
 378     to_string(|s| {
 379         s.head("")?;
 380         s.print_fn(decl, unsafety, constness, Abi::Rust, Some(name),
 381                    generics, &ast::Visibility::Inherited)?;
 382         s.end()?; // Close the head box
 383         s.end() // Close the outer box
 384     })
 385 }
 386
 387 pub fn block_to_string(blk: &ast::Block) -> String {
 388     to_string(|s| {
 389         // containing cbox, will be closed by print-block at }
 390         s.cbox(INDENT_UNIT)?;
 391         // head-ibox, will be closed by print-block after {
 392         s.ibox(0)?;
 393         s.print_block(blk)
 394     })
 395 }
 396
 397 pub fn meta_list_item_to_string(li: &ast::NestedMetaItem) -> String {
 398     to_string(|s| s.print_meta_list_item(li))
 399 }
 400
 401 pub fn meta_item_to_string(mi: &ast::MetaItem) -> String {
 402     to_string(|s| s.print_meta_item(mi))
 403 }
 404
 405 pub fn attribute_to_string(attr: &ast::Attribute) -> String {
 406     to_string(|s| s.print_attribute(attr))
 407 }
 408
 409 pub fn lit_to_string(l: &ast::Lit) -> String {
 410     to_string(|s| s.print_literal(l))
 411 }
 412
 413 pub fn variant_to_string(var: &ast::Variant) -> String {
 414     to_string(|s| s.print_variant(var))
 415 }
 416
 417 pub fn arg_to_string(arg: &ast::Arg) -> String {
 418     to_string(|s| s.print_arg(arg, false))
 419 }
 420
 421 pub fn mac_to_string(arg: &ast::Mac) -> String {
 422     to_string(|s| s.print_mac(arg, ::parse::token::Paren))
 423 }
 424
 425 pub fn visibility_qualified(vis: &ast::Visibility, s: &str) -> String {
 426     match *vis {
 427         ast::Visibility::Public => format!("pub {}", s),
 428         ast::Visibility::Crate(_) => format!("pub(crate) {}", s),
 429         ast::Visibility::Restricted { ref path, .. } =>
 430             format!("pub({}) {}", to_string(|s| s.print_path(path, false, 0, true)), s),
 431         ast::Visibility::Inherited => s.to_string()
 432     }
 433 }
 434
 435 fn needs_parentheses(expr: &ast::Expr) -> bool {
 436     match expr.node {
 437         ast::ExprKind::Assign(..) | ast::ExprKind::Binary(..) |
 438         ast::ExprKind::Closure(..) |
 439         ast::ExprKind::AssignOp(..) | ast::ExprKind::Cast(..) |
 440         ast::ExprKind::InPlace(..) | ast::ExprKind::Type(..) => true,
 441         _ => false,
 442     }
 443 }
 444
 445 pub trait PrintState<'a> {
 446     fn writer(&mut self) -> &mut pp::Printer<'a>;
 447     fn boxes(&mut self) -> &mut Vec<pp::Breaks>;
 448     fn comments(&mut self) -> &mut Option<Vec<comments::Comment>>;
 449     fn cur_cmnt_and_lit(&mut self) -> &mut CurrentCommentAndLiteral;
 450     fn literals(&self) -> &Option<Vec<comments::Literal>>;
 451
 452     fn word_space(&mut self, w: &str) -> io::Result<()> {
 453         word(self.writer(), w)?;
 454         space(self.writer())
 455     }
 456
 457     fn popen(&mut self) -> io::Result<()> { word(self.writer(), "(") }
 458
 459     fn pclose(&mut self) -> io::Result<()> { word(self.writer(), ")") }
 460
 461     fn is_begin(&mut self) -> bool {
 462         match self.writer().last_token() {
 463             pp::Token::Begin(_) => true,
 464             _ => false,
 465         }
 466     }
 467
 468     fn is_end(&mut self) -> bool {
 469         match self.writer().last_token() {
 470             pp::Token::End => true,
 471             _ => false,
 472         }
 473     }
 474
 475     // is this the beginning of a line?
 476     fn is_bol(&mut self) -> bool {
 477         self.writer().last_token().is_eof() || self.writer().last_token().is_hardbreak_tok()
 478     }
 479
 480     fn hardbreak_if_not_bol(&mut self) -> io::Result<()> {
 481         if !self.is_bol() {
 482             hardbreak(self.writer())?
 483         }
 484         Ok(())
 485     }
 486
 487     // "raw box"
 488     fn rbox(&mut self, u: usize, b: pp::Breaks) -> io::Result<()> {
 489         self.boxes().push(b);
 490         pp::rbox(self.writer(), u, b)
 491     }
 492
 493     fn ibox(&mut self, u: usize) -> io::Result<()> {
 494         self.boxes().push(pp::Breaks::Inconsistent);
 495         pp::ibox(self.writer(), u)
 496     }
 497
 498     fn end(&mut self) -> io::Result<()> {
 499         self.boxes().pop().unwrap();
 500         pp::end(self.writer())
 501     }
 502
 503     fn commasep<T, F>(&mut self, b: Breaks, elts: &[T], mut op: F) -> io::Result<()>
 504         where F: FnMut(&mut Self, &T) -> io::Result<()>,
 505     {
 506         self.rbox(0, b)?;
 507         let mut first = true;
 508         for elt in elts {
 509             if first { first = false; } else { self.word_space(",")?; }
 510             op(self, elt)?;
 511         }
 512         self.end()
 513     }
 514
 515     fn next_lit(&mut self, pos: BytePos) -> Option<comments::Literal> {
 516         let mut cur_lit = self.cur_cmnt_and_lit().cur_lit;
 517
 518         let mut result = None;
 519
 520         if let &Some(ref lits) = self.literals()
 521         {
 522             while cur_lit < lits.len() {
 523                 let ltrl = (*lits)[cur_lit].clone();
 524                 if ltrl.pos > pos { break; }
 525                 cur_lit += 1;
 526                 if ltrl.pos == pos {
 527                     result = Some(ltrl);
 528                     break;
 529                 }
 530             }
 531         }
 532
 533         self.cur_cmnt_and_lit().cur_lit = cur_lit;
 534         result
 535     }
 536
 537     fn maybe_print_comment(&mut self, pos: BytePos) -> io::Result<()> {
 538         while let Some(ref cmnt) = self.next_comment() {
 539             if cmnt.pos < pos {
 540                 self.print_comment(cmnt)?;
 541                 self.cur_cmnt_and_lit().cur_cmnt += 1;
 542             } else {
 543                 break
 544             }
 545         }
 546         Ok(())
 547     }
 548
 549     fn print_comment(&mut self,
 550                      cmnt: &comments::Comment) -> io::Result<()> {
 551         match cmnt.style {
 552             comments::Mixed => {
 553                 assert_eq!(cmnt.lines.len(), 1);
 554                 zerobreak(self.writer())?;
 555                 word(self.writer(), &cmnt.lines[0])?;
 556                 zerobreak(self.writer())
 557             }
 558             comments::Isolated => {
 559                 self.hardbreak_if_not_bol()?;
 560                 for line in &cmnt.lines {
 561                     // Don't print empty lines because they will end up as trailing
 562                     // whitespace
 563                     if !line.is_empty() {
 564                         word(self.writer(), &line[..])?;
 565                     }
 566                     hardbreak(self.writer())?;
 567                 }
 568                 Ok(())
 569             }
 570             comments::Trailing => {
 571                 if !self.is_bol() {
 572                     word(self.writer(), " ")?;
 573                 }
 574                 if cmnt.lines.len() == 1 {
 575                     word(self.writer(), &cmnt.lines[0])?;
 576                     hardbreak(self.writer())
 577                 } else {
 578                     self.ibox(0)?;
 579                     for line in &cmnt.lines {
 580                         if !line.is_empty() {
 581                             word(self.writer(), &line[..])?;
 582                         }
 583                         hardbreak(self.writer())?;
 584                     }
 585                     self.end()
 586                 }
 587             }
 588             comments::BlankLine => {
 589                 // We need to do at least one, possibly two hardbreaks.
 590                 let is_semi = match self.writer().last_token() {
 591                     pp::Token::String(s, _) => ";" == s,
 592                     _ => false
 593                 };
 594                 if is_semi || self.is_begin() || self.is_end() {
 595                     hardbreak(self.writer())?;
 596                 }
 597                 hardbreak(self.writer())
 598             }
 599         }
 600     }
 601
 602     fn next_comment(&mut self) -> Option<comments::Comment> {
 603         let cur_cmnt = self.cur_cmnt_and_lit().cur_cmnt;
 604         match *self.comments() {
 605             Some(ref cmnts) => {
 606                 if cur_cmnt < cmnts.len() {
 607                     Some(cmnts[cur_cmnt].clone())
 608                 } else {
 609                     None
 610                 }
 611             }
 612             _ => None
 613         }
 614     }
 615
 616     fn print_literal(&mut self, lit: &ast::Lit) -> io::Result<()> {
 617         self.maybe_print_comment(lit.span.lo)?;
 618         match self.next_lit(lit.span.lo) {
 619             Some(ref ltrl) => {
 620                 return word(self.writer(), &(*ltrl).lit);
 621             }
 622             _ => ()
 623         }
 624         match lit.node {
 625             ast::LitKind::Str(st, style) => self.print_string(&st.as_str(), style),
 626             ast::LitKind::Byte(byte) => {
 627                 let mut res = String::from("b'");
 628                 res.extend(ascii::escape_default(byte).map(|c| c as char));
 629                 res.push('\'');
 630                 word(self.writer(), &res[..])
 631             }
 632             ast::LitKind::Char(ch) => {
 633                 let mut res = String::from("'");
 634                 res.extend(ch.escape_default());
 635                 res.push('\'');
 636                 word(self.writer(), &res[..])
 637             }
 638             ast::LitKind::Int(i, t) => {
 639                 match t {
 640                     ast::LitIntType::Signed(st) => {
 641                         word(self.writer(), &st.val_to_string(i as i128))
 642                     }
 643                     ast::LitIntType::Unsigned(ut) => {
 644                         word(self.writer(), &ut.val_to_string(i))
 645                     }
 646                     ast::LitIntType::Unsuffixed => {
 647                         word(self.writer(), &format!("{}", i))
 648                     }
 649                 }
 650             }
 651             ast::LitKind::Float(ref f, t) => {
 652                 word(self.writer(),
 653                      &format!(
 654                          "{}{}",
 655                          &f,
 656                          t.ty_to_string()))
 657             }
 658             ast::LitKind::FloatUnsuffixed(ref f) => word(self.writer(), &f.as_str()),
 659             ast::LitKind::Bool(val) => {
 660                 if val { word(self.writer(), "true") } else { word(self.writer(), "false") }
 661             }
 662             ast::LitKind::ByteStr(ref v) => {
 663                 let mut escaped: String = String::new();
 664                 for &ch in v.iter() {
 665                     escaped.extend(ascii::escape_default(ch)
 666                                          .map(|c| c as char));
 667                 }
 668                 word(self.writer(), &format!("b\"{}\"", escaped))
 669             }
 670         }
 671     }
 672
 673     fn print_string(&mut self, st: &str,
 674                     style: ast::StrStyle) -> io::Result<()> {
 675         let st = match style {
 676             ast::StrStyle::Cooked => {
 677                 (format!("\"{}\"", st.escape_default()))
 678             }
 679             ast::StrStyle::Raw(n) => {
 680                 (format!("r{delim}\"{string}\"{delim}",
 681                          delim=repeat("#", n),
 682                          string=st))
 683             }
 684         };
 685         word(self.writer(), &st[..])
 686     }
 687
 688     fn print_inner_attributes(&mut self,
 689                               attrs: &[ast::Attribute]) -> io::Result<()> {
 690         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, true)
 691     }
 692
 693     fn print_inner_attributes_no_trailing_hardbreak(&mut self,
 694                                                    attrs: &[ast::Attribute])
 695                                                    -> io::Result<()> {
 696         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, false)
 697     }
 698
 699     fn print_outer_attributes(&mut self,
 700                               attrs: &[ast::Attribute]) -> io::Result<()> {
 701         self.print_either_attributes(attrs, ast::AttrStyle::Outer, false, true)
 702     }
 703
 704     fn print_inner_attributes_inline(&mut self,
 705                                      attrs: &[ast::Attribute]) -> io::Result<()> {
 706         self.print_either_attributes(attrs, ast::AttrStyle::Inner, true, true)
 707     }
 708
 709     fn print_outer_attributes_inline(&mut self,
 710                                      attrs: &[ast::Attribute]) -> io::Result<()> {
 711         self.print_either_attributes(attrs, ast::AttrStyle::Outer, true, true)
 712     }
 713
 714     fn print_either_attributes(&mut self,
 715                               attrs: &[ast::Attribute],
 716                               kind: ast::AttrStyle,
 717                               is_inline: bool,
 718                               trailing_hardbreak: bool) -> io::Result<()> {
 719         let mut count = 0;
 720         for attr in attrs {
 721             if attr.style == kind {
 722                 self.print_attribute_inline(attr, is_inline)?;
 723                 if is_inline {
 724                     self.nbsp()?;
 725                 }
 726                 count += 1;
 727             }
 728         }
 729         if count > 0 && trailing_hardbreak && !is_inline {
 730             self.hardbreak_if_not_bol()?;
 731         }
 732         Ok(())
 733     }
 734
 735     fn print_attribute(&mut self, attr: &ast::Attribute) -> io::Result<()> {
 736         self.print_attribute_inline(attr, false)
 737     }
 738
 739     fn print_attribute_inline(&mut self, attr: &ast::Attribute,
 740                               is_inline: bool) -> io::Result<()> {
 741         if !is_inline {
 742             self.hardbreak_if_not_bol()?;
 743         }
 744         self.maybe_print_comment(attr.span.lo)?;
 745         if attr.is_sugared_doc {
 746             word(self.writer(), &attr.value_str().unwrap().as_str())?;
 747             hardbreak(self.writer())
 748         } else {
 749             match attr.style {
 750                 ast::AttrStyle::Inner => word(self.writer(), "#![")?,
 751                 ast::AttrStyle::Outer => word(self.writer(), "#[")?,
 752             }
 753             self.print_meta_item(&attr.meta())?;
 754             word(self.writer(), "]")
 755         }
 756     }
 757
 758     fn print_meta_list_item(&mut self, item: &ast::NestedMetaItem) -> io::Result<()> {
 759         match item.node {
 760             ast::NestedMetaItemKind::MetaItem(ref mi) => {
 761                 self.print_meta_item(mi)
 762             },
 763             ast::NestedMetaItemKind::Literal(ref lit) => {
 764                 self.print_literal(lit)
 765             }
 766         }
 767     }
 768
 769     fn print_meta_item(&mut self, item: &ast::MetaItem) -> io::Result<()> {
 770         self.ibox(INDENT_UNIT)?;
 771         match item.node {
 772             ast::MetaItemKind::Word => {
 773                 word(self.writer(), &item.name.as_str())?;
 774             }
 775             ast::MetaItemKind::NameValue(ref value) => {
 776                 self.word_space(&item.name.as_str())?;
 777                 self.word_space("=")?;
 778                 self.print_literal(value)?;
 779             }
 780             ast::MetaItemKind::List(ref items) => {
 781                 word(self.writer(), &item.name.as_str())?;
 782                 self.popen()?;
 783                 self.commasep(Consistent,
 784                               &items[..],
 785                               |s, i| s.print_meta_list_item(&i))?;
 786                 self.pclose()?;
 787             }
 788         }
 789         self.end()
 790     }
 791
 792     fn space_if_not_bol(&mut self) -> io::Result<()> {
 793         if !self.is_bol() { space(self.writer())?; }
 794         Ok(())
 795     }
 796
 797     fn nbsp(&mut self) -> io::Result<()> { word(self.writer(), " ") }
 798 }
 799
 800 impl<'a> PrintState<'a> for State<'a> {
 801     fn writer(&mut self) -> &mut pp::Printer<'a> {
 802         &mut self.s
 803     }
 804
 805     fn boxes(&mut self) -> &mut Vec<pp::Breaks> {
 806         &mut self.boxes
 807     }
 808
 809     fn comments(&mut self) -> &mut Option<Vec<comments::Comment>> {
 810         &mut self.comments
 811     }
 812
 813     fn cur_cmnt_and_lit(&mut self) -> &mut CurrentCommentAndLiteral {
 814         &mut self.cur_cmnt_and_lit
 815     }
 816
 817     fn literals(&self) -> &Option<Vec<comments::Literal>> {
 818         &self.literals
 819     }
 820 }
 821
 822 impl<'a> State<'a> {
 823     pub fn cbox(&mut self, u: usize) -> io::Result<()> {
 824         self.boxes.push(pp::Breaks::Consistent);
 825         pp::cbox(&mut self.s, u)
 826     }
 827
 828     pub fn word_nbsp(&mut self, w: &str) -> io::Result<()> {
 829         word(&mut self.s, w)?;
 830         self.nbsp()
 831     }
 832
 833     pub fn head(&mut self, w: &str) -> io::Result<()> {
 834         // outer-box is consistent
 835         self.cbox(INDENT_UNIT)?;
 836         // head-box is inconsistent
 837         self.ibox(w.len() + 1)?;
 838         // keyword that starts the head
 839         if !w.is_empty() {
 840             self.word_nbsp(w)?;
 841         }
 842         Ok(())
 843     }
 844
 845     pub fn bopen(&mut self) -> io::Result<()> {
 846         word(&mut self.s, "{")?;
 847         self.end() // close the head-box
 848     }
 849
 850     pub fn bclose_(&mut self, span: syntax_pos::Span,
 851                    indented: usize) -> io::Result<()> {
 852         self.bclose_maybe_open(span, indented, true)
 853     }
 854     pub fn bclose_maybe_open(&mut self, span: syntax_pos::Span,
 855                              indented: usize, close_box: bool) -> io::Result<()> {
 856         self.maybe_print_comment(span.hi)?;
 857         self.break_offset_if_not_bol(1, -(indented as isize))?;
 858         word(&mut self.s, "}")?;
 859         if close_box {
 860             self.end()?; // close the outer-box
 861         }
 862         Ok(())
 863     }
 864     pub fn bclose(&mut self, span: syntax_pos::Span) -> io::Result<()> {
 865         self.bclose_(span, INDENT_UNIT)
 866     }
 867
 868     pub fn in_cbox(&self) -> bool {
 869         match self.boxes.last() {
 870             Some(&last_box) => last_box == pp::Breaks::Consistent,
 871             None => false
 872         }
 873     }
 874
 875     pub fn break_offset_if_not_bol(&mut self, n: usize,
 876                                    off: isize) -> io::Result<()> {
 877         if !self.is_bol() {
 878             break_offset(&mut self.s, n, off)
 879         } else {
 880             if off != 0 && self.s.last_token().is_hardbreak_tok() {
 881                 // We do something pretty sketchy here: tuck the nonzero
 882                 // offset-adjustment we were going to deposit along with the
 883                 // break into the previous hardbreak.
 884                 self.s.replace_last_token(pp::hardbreak_tok_offset(off));
 885             }
 886             Ok(())
 887         }
 888     }
 889
 890     // Synthesizes a comment that was not textually present in the original source
 891     // file.
 892     pub fn synth_comment(&mut self, text: String) -> io::Result<()> {
 893         word(&mut self.s, "/*")?;
 894         space(&mut self.s)?;
 895         word(&mut self.s, &text[..])?;
 896         space(&mut self.s)?;
 897         word(&mut self.s, "*/")
 898     }
 899
 900
 901
 902     pub fn commasep_cmnt<T, F, G>(&mut self,
 903                                   b: Breaks,
 904                                   elts: &[T],
 905                                   mut op: F,
 906                                   mut get_span: G) -> io::Result<()> where
 907         F: FnMut(&mut State, &T) -> io::Result<()>,
 908         G: FnMut(&T) -> syntax_pos::Span,
 909     {
 910         self.rbox(0, b)?;
 911         let len = elts.len();
 912         let mut i = 0;
 913         for elt in elts {
 914             self.maybe_print_comment(get_span(elt).hi)?;
 915             op(self, elt)?;
 916             i += 1;
 917             if i < len {
 918                 word(&mut self.s, ",")?;
 919                 self.maybe_print_trailing_comment(get_span(elt),
 920                                                   Some(get_span(&elts[i]).hi))?;
 921                 self.space_if_not_bol()?;
 922             }
 923         }
 924         self.end()
 925     }
 926
 927     pub fn commasep_exprs(&mut self, b: Breaks,
 928                           exprs: &[P<ast::Expr>]) -> io::Result<()> {
 929         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(&e), |e| e.span)
 930     }
 931
 932     pub fn print_mod(&mut self, _mod: &ast::Mod,
 933                      attrs: &[ast::Attribute]) -> io::Result<()> {
 934         self.print_inner_attributes(attrs)?;
 935         for item in &_mod.items {
 936             self.print_item(&item)?;
 937         }
 938         Ok(())
 939     }
 940
 941     pub fn print_foreign_mod(&mut self, nmod: &ast::ForeignMod,
 942                              attrs: &[ast::Attribute]) -> io::Result<()> {
 943         self.print_inner_attributes(attrs)?;
 944         for item in &nmod.items {
 945             self.print_foreign_item(item)?;
 946         }
 947         Ok(())
 948     }
 949
 950     pub fn print_opt_lifetime(&mut self,
 951                               lifetime: &Option<ast::Lifetime>) -> io::Result<()> {
 952         if let Some(l) = *lifetime {
 953             self.print_lifetime(&l)?;
 954             self.nbsp()?;
 955         }
 956         Ok(())
 957     }
 958
 959     pub fn print_type(&mut self, ty: &ast::Ty) -> io::Result<()> {
 960         self.maybe_print_comment(ty.span.lo)?;
 961         self.ibox(0)?;
 962         match ty.node {
 963             ast::TyKind::Slice(ref ty) => {
 964                 word(&mut self.s, "[")?;
 965                 self.print_type(&ty)?;
 966                 word(&mut self.s, "]")?;
 967             }
 968             ast::TyKind::Ptr(ref mt) => {
 969                 word(&mut self.s, "*")?;
 970                 match mt.mutbl {
 971                     ast::Mutability::Mutable => self.word_nbsp("mut")?,
 972                     ast::Mutability::Immutable => self.word_nbsp("const")?,
 973                 }
 974                 self.print_type(&mt.ty)?;
 975             }
 976             ast::TyKind::Rptr(ref lifetime, ref mt) => {
 977                 word(&mut self.s, "&")?;
 978                 self.print_opt_lifetime(lifetime)?;
 979                 self.print_mt(mt)?;
 980             }
 981             ast::TyKind::Never => {
 982                 word(&mut self.s, "!")?;
 983             },
 984             ast::TyKind::Tup(ref elts) => {
 985                 self.popen()?;
 986                 self.commasep(Inconsistent, &elts[..],
 987                               |s, ty| s.print_type(&ty))?;
 988                 if elts.len() == 1 {
 989                     word(&mut self.s, ",")?;
 990                 }
 991                 self.pclose()?;
 992             }
 993             ast::TyKind::Paren(ref typ) => {
 994                 self.popen()?;
 995                 self.print_type(&typ)?;
 996                 self.pclose()?;
 997             }
 998             ast::TyKind::BareFn(ref f) => {
 999                 let generics = ast::Generics {
1000                     lifetimes: f.lifetimes.clone(),
1001                     ty_params: Vec::new(),
1002                     where_clause: ast::WhereClause {
1003                         id: ast::DUMMY_NODE_ID,
1004                         predicates: Vec::new(),
1005                     },
1006                     span: syntax_pos::DUMMY_SP,
1007                 };
1008                 self.print_ty_fn(f.abi,
1009                                  f.unsafety,
1010                                  &f.decl,
1011                                  None,
1012                                  &generics)?;
1013             }
1014             ast::TyKind::Path(None, ref path) => {
1015                 self.print_path(path, false, 0, false)?;
1016             }
1017             ast::TyKind::Path(Some(ref qself), ref path) => {
1018                 self.print_qpath(path, qself, false)?
1019             }
1020             ast::TyKind::TraitObject(ref bounds) => {
1021                 self.print_bounds("", &bounds[..])?;
1022             }
1023             ast::TyKind::ImplTrait(ref bounds) => {
1024                 self.print_bounds("impl ", &bounds[..])?;
1025             }
1026             ast::TyKind::Array(ref ty, ref v) => {
1027                 word(&mut self.s, "[")?;
1028                 self.print_type(&ty)?;
1029                 word(&mut self.s, "; ")?;
1030                 self.print_expr(&v)?;
1031                 word(&mut self.s, "]")?;
1032             }
1033             ast::TyKind::Typeof(ref e) => {
1034                 word(&mut self.s, "typeof(")?;
1035                 self.print_expr(&e)?;
1036                 word(&mut self.s, ")")?;
1037             }
1038             ast::TyKind::Infer => {
1039                 word(&mut self.s, "_")?;
1040             }
1041             ast::TyKind::ImplicitSelf => {
1042                 word(&mut self.s, "Self")?;
1043             }
1044             ast::TyKind::Mac(ref m) => {
1045                 self.print_mac(m, token::Paren)?;
1046             }
1047         }
1048         self.end()
1049     }
1050
1051     pub fn print_foreign_item(&mut self,
1052                               item: &ast::ForeignItem) -> io::Result<()> {
1053         self.hardbreak_if_not_bol()?;
1054         self.maybe_print_comment(item.span.lo)?;
1055         self.print_outer_attributes(&item.attrs)?;
1056         match item.node {
1057             ast::ForeignItemKind::Fn(ref decl, ref generics) => {
1058                 self.head("")?;
1059                 self.print_fn(decl, ast::Unsafety::Normal,
1060                               ast::Constness::NotConst,
1061                               Abi::Rust, Some(item.ident),
1062                               generics, &item.vis)?;
1063                 self.end()?; // end head-ibox
1064                 word(&mut self.s, ";")?;
1065                 self.end() // end the outer fn box
1066             }
1067             ast::ForeignItemKind::Static(ref t, m) => {
1068                 self.head(&visibility_qualified(&item.vis, "static"))?;
1069                 if m {
1070                     self.word_space("mut")?;
1071                 }
1072                 self.print_ident(item.ident)?;
1073                 self.word_space(":")?;
1074                 self.print_type(&t)?;
1075                 word(&mut self.s, ";")?;
1076                 self.end()?; // end the head-ibox
1077                 self.end() // end the outer cbox
1078             }
1079         }
1080     }
1081
1082     fn print_associated_const(&mut self,
1083                               ident: ast::Ident,
1084                               ty: &ast::Ty,
1085                               default: Option<&ast::Expr>,
1086                               vis: &ast::Visibility)
1087                               -> io::Result<()>
1088     {
1089         word(&mut self.s, &visibility_qualified(vis, ""))?;
1090         self.word_space("const")?;
1091         self.print_ident(ident)?;
1092         self.word_space(":")?;
1093         self.print_type(ty)?;
1094         if let Some(expr) = default {
1095             space(&mut self.s)?;
1096             self.word_space("=")?;
1097             self.print_expr(expr)?;
1098         }
1099         word(&mut self.s, ";")
1100     }
1101
1102     fn print_associated_type(&mut self,
1103                              ident: ast::Ident,
1104                              bounds: Option<&ast::TyParamBounds>,
1105                              ty: Option<&ast::Ty>)
1106                              -> io::Result<()> {
1107         self.word_space("type")?;
1108         self.print_ident(ident)?;
1109         if let Some(bounds) = bounds {
1110             self.print_bounds(":", bounds)?;
1111         }
1112         if let Some(ty) = ty {
1113             space(&mut self.s)?;
1114             self.word_space("=")?;
1115             self.print_type(ty)?;
1116         }
1117         word(&mut self.s, ";")
1118     }
1119
1120     /// Pretty-print an item
1121     pub fn print_item(&mut self, item: &ast::Item) -> io::Result<()> {
1122         self.hardbreak_if_not_bol()?;
1123         self.maybe_print_comment(item.span.lo)?;
1124         self.print_outer_attributes(&item.attrs)?;
1125         self.ann.pre(self, NodeItem(item))?;
1126         match item.node {
1127             ast::ItemKind::ExternCrate(ref optional_path) => {
1128                 self.head(&visibility_qualified(&item.vis, "extern crate"))?;
1129                 if let Some(p) = *optional_path {
1130                     let val = p.as_str();
1131                     if val.contains("-") {
1132                         self.print_string(&val, ast::StrStyle::Cooked)?;
1133                     } else {
1134                         self.print_name(p)?;
1135                     }
1136                     space(&mut self.s)?;
1137                     word(&mut self.s, "as")?;
1138                     space(&mut self.s)?;
1139                 }
1140                 self.print_ident(item.ident)?;
1141                 word(&mut self.s, ";")?;
1142                 self.end()?; // end inner head-block
1143                 self.end()?; // end outer head-block
1144             }
1145             ast::ItemKind::Use(ref vp) => {
1146                 self.head(&visibility_qualified(&item.vis, "use"))?;
1147                 self.print_view_path(&vp)?;
1148                 word(&mut self.s, ";")?;
1149                 self.end()?; // end inner head-block
1150                 self.end()?; // end outer head-block
1151             }
1152             ast::ItemKind::Static(ref ty, m, ref expr) => {
1153                 self.head(&visibility_qualified(&item.vis, "static"))?;
1154                 if m == ast::Mutability::Mutable {
1155                     self.word_space("mut")?;
1156                 }
1157                 self.print_ident(item.ident)?;
1158                 self.word_space(":")?;
1159                 self.print_type(&ty)?;
1160                 space(&mut self.s)?;
1161                 self.end()?; // end the head-ibox
1162
1163                 self.word_space("=")?;
1164                 self.print_expr(&expr)?;
1165                 word(&mut self.s, ";")?;
1166                 self.end()?; // end the outer cbox
1167             }
1168             ast::ItemKind::Const(ref ty, ref expr) => {
1169                 self.head(&visibility_qualified(&item.vis, "const"))?;
1170                 self.print_ident(item.ident)?;
1171                 self.word_space(":")?;
1172                 self.print_type(&ty)?;
1173                 space(&mut self.s)?;
1174                 self.end()?; // end the head-ibox
1175
1176                 self.word_space("=")?;
1177                 self.print_expr(&expr)?;
1178                 word(&mut self.s, ";")?;
1179                 self.end()?; // end the outer cbox
1180             }
1181             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref typarams, ref body) => {
1182                 self.head("")?;
1183                 self.print_fn(
1184                     decl,
1185                     unsafety,
1186                     constness.node,
1187                     abi,
1188                     Some(item.ident),
1189                     typarams,
1190                     &item.vis
1191                 )?;
1192                 word(&mut self.s, " ")?;
1193                 self.print_block_with_attrs(&body, &item.attrs)?;
1194             }
1195             ast::ItemKind::Mod(ref _mod) => {
1196                 self.head(&visibility_qualified(&item.vis, "mod"))?;
1197                 self.print_ident(item.ident)?;
1198                 self.nbsp()?;
1199                 self.bopen()?;
1200                 self.print_mod(_mod, &item.attrs)?;
1201                 self.bclose(item.span)?;
1202             }
1203             ast::ItemKind::ForeignMod(ref nmod) => {
1204                 self.head("extern")?;
1205                 self.word_nbsp(&nmod.abi.to_string())?;
1206                 self.bopen()?;
1207                 self.print_foreign_mod(nmod, &item.attrs)?;
1208                 self.bclose(item.span)?;
1209             }
1210             ast::ItemKind::Ty(ref ty, ref params) => {
1211                 self.ibox(INDENT_UNIT)?;
1212                 self.ibox(0)?;
1213                 self.word_nbsp(&visibility_qualified(&item.vis, "type"))?;
1214                 self.print_ident(item.ident)?;
1215                 self.print_generics(params)?;
1216                 self.end()?; // end the inner ibox
1217
1218                 self.print_where_clause(&params.where_clause)?;
1219                 space(&mut self.s)?;
1220                 self.word_space("=")?;
1221                 self.print_type(&ty)?;
1222                 word(&mut self.s, ";")?;
1223                 self.end()?; // end the outer ibox
1224             }
1225             ast::ItemKind::Enum(ref enum_definition, ref params) => {
1226                 self.print_enum_def(
1227                     enum_definition,
1228                     params,
1229                     item.ident,
1230                     item.span,
1231                     &item.vis
1232                 )?;
1233             }
1234             ast::ItemKind::Struct(ref struct_def, ref generics) => {
1235                 self.head(&visibility_qualified(&item.vis, "struct"))?;
1236                 self.print_struct(&struct_def, generics, item.ident, item.span, true)?;
1237             }
1238             ast::ItemKind::Union(ref struct_def, ref generics) => {
1239                 self.head(&visibility_qualified(&item.vis, "union"))?;
1240                 self.print_struct(&struct_def, generics, item.ident, item.span, true)?;
1241             }
1242             ast::ItemKind::DefaultImpl(unsafety, ref trait_ref) => {
1243                 self.head("")?;
1244                 self.print_visibility(&item.vis)?;
1245                 self.print_unsafety(unsafety)?;
1246                 self.word_nbsp("impl")?;
1247                 self.print_trait_ref(trait_ref)?;
1248                 space(&mut self.s)?;
1249                 self.word_space("for")?;
1250                 self.word_space("..")?;
1251                 self.bopen()?;
1252                 self.bclose(item.span)?;
1253             }
1254             ast::ItemKind::Impl(unsafety,
1255                           polarity,
1256                           ref generics,
1257                           ref opt_trait,
1258                           ref ty,
1259                           ref impl_items) => {
1260                 self.head("")?;
1261                 self.print_visibility(&item.vis)?;
1262                 self.print_unsafety(unsafety)?;
1263                 self.word_nbsp("impl")?;
1264
1265                 if generics.is_parameterized() {
1266                     self.print_generics(generics)?;
1267                     space(&mut self.s)?;
1268                 }
1269
1270                 match polarity {
1271                     ast::ImplPolarity::Negative => {
1272                         word(&mut self.s, "!")?;
1273                     },
1274                     _ => {}
1275                 }
1276
1277                 if let Some(ref t) = *opt_trait {
1278                     self.print_trait_ref(t)?;
1279                     space(&mut self.s)?;
1280                     self.word_space("for")?;
1281                 }
1282
1283                 self.print_type(&ty)?;
1284                 self.print_where_clause(&generics.where_clause)?;
1285
1286                 space(&mut self.s)?;
1287                 self.bopen()?;
1288                 self.print_inner_attributes(&item.attrs)?;
1289                 for impl_item in impl_items {
1290                     self.print_impl_item(impl_item)?;
1291                 }
1292                 self.bclose(item.span)?;
1293             }
1294             ast::ItemKind::Trait(unsafety, ref generics, ref bounds, ref trait_items) => {
1295                 self.head("")?;
1296                 self.print_visibility(&item.vis)?;
1297                 self.print_unsafety(unsafety)?;
1298                 self.word_nbsp("trait")?;
1299                 self.print_ident(item.ident)?;
1300                 self.print_generics(generics)?;
1301                 let mut real_bounds = Vec::with_capacity(bounds.len());
1302                 for b in bounds.iter() {
1303                     if let TraitTyParamBound(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
1304                         space(&mut self.s)?;
1305                         self.word_space("for ?")?;
1306                         self.print_trait_ref(&ptr.trait_ref)?;
1307                     } else {
1308                         real_bounds.push(b.clone());
1309                     }
1310                 }
1311                 self.print_bounds(":", &real_bounds[..])?;
1312                 self.print_where_clause(&generics.where_clause)?;
1313                 word(&mut self.s, " ")?;
1314                 self.bopen()?;
1315                 for trait_item in trait_items {
1316                     self.print_trait_item(trait_item)?;
1317                 }
1318                 self.bclose(item.span)?;
1319             }
1320             ast::ItemKind::Mac(codemap::Spanned { ref node, .. }) => {
1321                 self.print_visibility(&item.vis)?;
1322                 self.print_path(&node.path, false, 0, false)?;
1323                 word(&mut self.s, "! ")?;
1324                 self.print_ident(item.ident)?;
1325                 self.cbox(INDENT_UNIT)?;
1326                 self.popen()?;
1327                 self.print_tts(node.stream())?;
1328                 self.pclose()?;
1329                 word(&mut self.s, ";")?;
1330                 self.end()?;
1331             }
1332         }
1333         self.ann.post(self, NodeItem(item))
1334     }
1335
1336     fn print_trait_ref(&mut self, t: &ast::TraitRef) -> io::Result<()> {
1337         self.print_path(&t.path, false, 0, false)
1338     }
1339
1340     fn print_formal_lifetime_list(&mut self, lifetimes: &[ast::LifetimeDef]) -> io::Result<()> {
1341         if !lifetimes.is_empty() {
1342             word(&mut self.s, "for<")?;
1343             let mut comma = false;
1344             for lifetime_def in lifetimes {
1345                 if comma {
1346                     self.word_space(",")?
1347                 }
1348                 self.print_outer_attributes_inline(&lifetime_def.attrs)?;
1349                 self.print_lifetime_bounds(&lifetime_def.lifetime, &lifetime_def.bounds)?;
1350                 comma = true;
1351             }
1352             word(&mut self.s, ">")?;
1353         }
1354         Ok(())
1355     }
1356
1357     fn print_poly_trait_ref(&mut self, t: &ast::PolyTraitRef) -> io::Result<()> {
1358         self.print_formal_lifetime_list(&t.bound_lifetimes)?;
1359         self.print_trait_ref(&t.trait_ref)
1360     }
1361
1362     pub fn print_enum_def(&mut self, enum_definition: &ast::EnumDef,
1363                           generics: &ast::Generics, ident: ast::Ident,
1364                           span: syntax_pos::Span,
1365                           visibility: &ast::Visibility) -> io::Result<()> {
1366         self.head(&visibility_qualified(visibility, "enum"))?;
1367         self.print_ident(ident)?;
1368         self.print_generics(generics)?;
1369         self.print_where_clause(&generics.where_clause)?;
1370         space(&mut self.s)?;
1371         self.print_variants(&enum_definition.variants, span)
1372     }
1373
1374     pub fn print_variants(&mut self,
1375                           variants: &[ast::Variant],
1376                           span: syntax_pos::Span) -> io::Result<()> {
1377         self.bopen()?;
1378         for v in variants {
1379             self.space_if_not_bol()?;
1380             self.maybe_print_comment(v.span.lo)?;
1381             self.print_outer_attributes(&v.node.attrs)?;
1382             self.ibox(INDENT_UNIT)?;
1383             self.print_variant(v)?;
1384             word(&mut self.s, ",")?;
1385             self.end()?;
1386             self.maybe_print_trailing_comment(v.span, None)?;
1387         }
1388         self.bclose(span)
1389     }
1390
1391     pub fn print_visibility(&mut self, vis: &ast::Visibility) -> io::Result<()> {
1392         match *vis {
1393             ast::Visibility::Public => self.word_nbsp("pub"),
1394             ast::Visibility::Crate(_) => self.word_nbsp("pub(crate)"),
1395             ast::Visibility::Restricted { ref path, .. } => {
1396                 let path = to_string(|s| s.print_path(path, false, 0, true));
1397                 self.word_nbsp(&format!("pub({})", path))
1398             }
1399             ast::Visibility::Inherited => Ok(())
1400         }
1401     }
1402
1403     pub fn print_struct(&mut self,
1404                         struct_def: &ast::VariantData,
1405                         generics: &ast::Generics,
1406                         ident: ast::Ident,
1407                         span: syntax_pos::Span,
1408                         print_finalizer: bool) -> io::Result<()> {
1409         self.print_ident(ident)?;
1410         self.print_generics(generics)?;
1411         if !struct_def.is_struct() {
1412             if struct_def.is_tuple() {
1413                 self.popen()?;
1414                 self.commasep(
1415                     Inconsistent, struct_def.fields(),
1416                     |s, field| {
1417                         s.maybe_print_comment(field.span.lo)?;
1418                         s.print_outer_attributes(&field.attrs)?;
1419                         s.print_visibility(&field.vis)?;
1420                         s.print_type(&field.ty)
1421                     }
1422                 )?;
1423                 self.pclose()?;
1424             }
1425             self.print_where_clause(&generics.where_clause)?;
1426             if print_finalizer {
1427                 word(&mut self.s, ";")?;
1428             }
1429             self.end()?;
1430             self.end() // close the outer-box
1431         } else {
1432             self.print_where_clause(&generics.where_clause)?;
1433             self.nbsp()?;
1434             self.bopen()?;
1435             self.hardbreak_if_not_bol()?;
1436
1437             for field in struct_def.fields() {
1438                 self.hardbreak_if_not_bol()?;
1439                 self.maybe_print_comment(field.span.lo)?;
1440                 self.print_outer_attributes(&field.attrs)?;
1441                 self.print_visibility(&field.vis)?;
1442                 self.print_ident(field.ident.unwrap())?;
1443                 self.word_nbsp(":")?;
1444                 self.print_type(&field.ty)?;
1445                 word(&mut self.s, ",")?;
1446             }
1447
1448             self.bclose(span)
1449         }
1450     }
1451
1452     /// This doesn't deserve to be called "pretty" printing, but it should be
1453     /// meaning-preserving. A quick hack that might help would be to look at the
1454     /// spans embedded in the TTs to decide where to put spaces and newlines.
1455     /// But it'd be better to parse these according to the grammar of the
1456     /// appropriate macro, transcribe back into the grammar we just parsed from,
1457     /// and then pretty-print the resulting AST nodes (so, e.g., we print
1458     /// expression arguments as expressions). It can be done! I think.
1459     pub fn print_tt(&mut self, tt: tokenstream::TokenTree) -> io::Result<()> {
1460         match tt {
1461             TokenTree::Token(_, ref tk) => {
1462                 word(&mut self.s, &token_to_string(tk))?;
1463                 match *tk {
1464                     parse::token::DocComment(..) => {
1465                         hardbreak(&mut self.s)
1466                     }
1467                     _ => Ok(())
1468                 }
1469             }
1470             TokenTree::Delimited(_, ref delimed) => {
1471                 word(&mut self.s, &token_to_string(&delimed.open_token()))?;
1472                 space(&mut self.s)?;
1473                 self.print_tts(delimed.stream())?;
1474                 space(&mut self.s)?;
1475                 word(&mut self.s, &token_to_string(&delimed.close_token()))
1476             },
1477         }
1478     }
1479
1480     pub fn print_tts(&mut self, tts: tokenstream::TokenStream) -> io::Result<()> {
1481         self.ibox(0)?;
1482         for (i, tt) in tts.into_trees().enumerate() {
1483             if i != 0 {
1484                 space(&mut self.s)?;
1485             }
1486             self.print_tt(tt)?;
1487         }
1488         self.end()
1489     }
1490
1491     pub fn print_variant(&mut self, v: &ast::Variant) -> io::Result<()> {
1492         self.head("")?;
1493         let generics = ast::Generics::default();
1494         self.print_struct(&v.node.data, &generics, v.node.name, v.span, false)?;
1495         match v.node.disr_expr {
1496             Some(ref d) => {
1497                 space(&mut self.s)?;
1498                 self.word_space("=")?;
1499                 self.print_expr(&d)
1500             }
1501             _ => Ok(())
1502         }
1503     }
1504
1505     pub fn print_method_sig(&mut self,
1506                             ident: ast::Ident,
1507                             m: &ast::MethodSig,
1508                             vis: &ast::Visibility)
1509                             -> io::Result<()> {
1510         self.print_fn(&m.decl,
1511                       m.unsafety,
1512                       m.constness.node,
1513                       m.abi,
1514                       Some(ident),
1515                       &m.generics,
1516                       vis)
1517     }
1518
1519     pub fn print_trait_item(&mut self, ti: &ast::TraitItem)
1520                             -> io::Result<()> {
1521         self.ann.pre(self, NodeSubItem(ti.id))?;
1522         self.hardbreak_if_not_bol()?;
1523         self.maybe_print_comment(ti.span.lo)?;
1524         self.print_outer_attributes(&ti.attrs)?;
1525         match ti.node {
1526             ast::TraitItemKind::Const(ref ty, ref default) => {
1527                 self.print_associated_const(ti.ident, &ty,
1528                                             default.as_ref().map(|expr| &**expr),
1529                                             &ast::Visibility::Inherited)?;
1530             }
1531             ast::TraitItemKind::Method(ref sig, ref body) => {
1532                 if body.is_some() {
1533                     self.head("")?;
1534                 }
1535                 self.print_method_sig(ti.ident, sig, &ast::Visibility::Inherited)?;
1536                 if let Some(ref body) = *body {
1537                     self.nbsp()?;
1538                     self.print_block_with_attrs(body, &ti.attrs)?;
1539                 } else {
1540                     word(&mut self.s, ";")?;
1541                 }
1542             }
1543             ast::TraitItemKind::Type(ref bounds, ref default) => {
1544                 self.print_associated_type(ti.ident, Some(bounds),
1545                                            default.as_ref().map(|ty| &**ty))?;
1546             }
1547             ast::TraitItemKind::Macro(codemap::Spanned { ref node, .. }) => {
1548                 // code copied from ItemKind::Mac:
1549                 self.print_path(&node.path, false, 0, false)?;
1550                 word(&mut self.s, "! ")?;
1551                 self.cbox(INDENT_UNIT)?;
1552                 self.popen()?;
1553                 self.print_tts(node.stream())?;
1554                 self.pclose()?;
1555                 word(&mut self.s, ";")?;
1556                 self.end()?
1557             }
1558         }
1559         self.ann.post(self, NodeSubItem(ti.id))
1560     }
1561
1562     pub fn print_impl_item(&mut self, ii: &ast::ImplItem) -> io::Result<()> {
1563         self.ann.pre(self, NodeSubItem(ii.id))?;
1564         self.hardbreak_if_not_bol()?;
1565         self.maybe_print_comment(ii.span.lo)?;
1566         self.print_outer_attributes(&ii.attrs)?;
1567         if let ast::Defaultness::Default = ii.defaultness {
1568             self.word_nbsp("default")?;
1569         }
1570         match ii.node {
1571             ast::ImplItemKind::Const(ref ty, ref expr) => {
1572                 self.print_associated_const(ii.ident, &ty, Some(&expr), &ii.vis)?;
1573             }
1574             ast::ImplItemKind::Method(ref sig, ref body) => {
1575                 self.head("")?;
1576                 self.print_method_sig(ii.ident, sig, &ii.vis)?;
1577                 self.nbsp()?;
1578                 self.print_block_with_attrs(body, &ii.attrs)?;
1579             }
1580             ast::ImplItemKind::Type(ref ty) => {
1581                 self.print_associated_type(ii.ident, None, Some(ty))?;
1582             }
1583             ast::ImplItemKind::Macro(codemap::Spanned { ref node, .. }) => {
1584                 // code copied from ItemKind::Mac:
1585                 self.print_path(&node.path, false, 0, false)?;
1586                 word(&mut self.s, "! ")?;
1587                 self.cbox(INDENT_UNIT)?;
1588                 self.popen()?;
1589                 self.print_tts(node.stream())?;
1590                 self.pclose()?;
1591                 word(&mut self.s, ";")?;
1592                 self.end()?
1593             }
1594         }
1595         self.ann.post(self, NodeSubItem(ii.id))
1596     }
1597
1598     pub fn print_stmt(&mut self, st: &ast::Stmt) -> io::Result<()> {
1599         self.maybe_print_comment(st.span.lo)?;
1600         match st.node {
1601             ast::StmtKind::Local(ref loc) => {
1602                 self.print_outer_attributes(&loc.attrs)?;
1603                 self.space_if_not_bol()?;
1604                 self.ibox(INDENT_UNIT)?;
1605                 self.word_nbsp("let")?;
1606
1607                 self.ibox(INDENT_UNIT)?;
1608                 self.print_local_decl(&loc)?;
1609                 self.end()?;
1610                 if let Some(ref init) = loc.init {
1611                     self.nbsp()?;
1612                     self.word_space("=")?;
1613                     self.print_expr(&init)?;
1614                 }
1615                 word(&mut self.s, ";")?;
1616                 self.end()?;
1617             }
1618             ast::StmtKind::Item(ref item) => self.print_item(&item)?,
1619             ast::StmtKind::Expr(ref expr) => {
1620                 self.space_if_not_bol()?;
1621                 self.print_expr_outer_attr_style(&expr, false)?;
1622                 if parse::classify::expr_requires_semi_to_be_stmt(expr) {
1623                     word(&mut self.s, ";")?;
1624                 }
1625             }
1626             ast::StmtKind::Semi(ref expr) => {
1627                 self.space_if_not_bol()?;
1628                 self.print_expr_outer_attr_style(&expr, false)?;
1629                 word(&mut self.s, ";")?;
1630             }
1631             ast::StmtKind::Mac(ref mac) => {
1632                 let (ref mac, style, ref attrs) = **mac;
1633                 self.space_if_not_bol()?;
1634                 self.print_outer_attributes(&attrs)?;
1635                 let delim = match style {
1636                     ast::MacStmtStyle::Braces => token::Brace,
1637                     _ => token::Paren
1638                 };
1639                 self.print_mac(&mac, delim)?;
1640                 if style == ast::MacStmtStyle::Semicolon {
1641                     word(&mut self.s, ";")?;
1642                 }
1643             }
1644         }
1645         self.maybe_print_trailing_comment(st.span, None)
1646     }
1647
1648     pub fn print_block(&mut self, blk: &ast::Block) -> io::Result<()> {
1649         self.print_block_with_attrs(blk, &[])
1650     }
1651
1652     pub fn print_block_unclosed(&mut self, blk: &ast::Block) -> io::Result<()> {
1653         self.print_block_unclosed_indent(blk, INDENT_UNIT)
1654     }
1655
1656     pub fn print_block_unclosed_with_attrs(&mut self, blk: &ast::Block,
1657                                             attrs: &[ast::Attribute])
1658                                            -> io::Result<()> {
1659         self.print_block_maybe_unclosed(blk, INDENT_UNIT, attrs, false)
1660     }
1661
1662     pub fn print_block_unclosed_indent(&mut self, blk: &ast::Block,
1663                                        indented: usize) -> io::Result<()> {
1664         self.print_block_maybe_unclosed(blk, indented, &[], false)
1665     }
1666
1667     pub fn print_block_with_attrs(&mut self,
1668                                   blk: &ast::Block,
1669                                   attrs: &[ast::Attribute]) -> io::Result<()> {
1670         self.print_block_maybe_unclosed(blk, INDENT_UNIT, attrs, true)
1671     }
1672
1673     pub fn print_block_maybe_unclosed(&mut self,
1674                                       blk: &ast::Block,
1675                                       indented: usize,
1676                                       attrs: &[ast::Attribute],
1677                                       close_box: bool) -> io::Result<()> {
1678         match blk.rules {
1679             BlockCheckMode::Unsafe(..) => self.word_space("unsafe")?,
1680             BlockCheckMode::Default => ()
1681         }
1682         self.maybe_print_comment(blk.span.lo)?;
1683         self.ann.pre(self, NodeBlock(blk))?;
1684         self.bopen()?;
1685
1686         self.print_inner_attributes(attrs)?;
1687
1688         for (i, st) in blk.stmts.iter().enumerate() {
1689             match st.node {
1690                 ast::StmtKind::Expr(ref expr) if i == blk.stmts.len() - 1 => {
1691                     self.maybe_print_comment(st.span.lo)?;
1692                     self.space_if_not_bol()?;
1693                     self.print_expr_outer_attr_style(&expr, false)?;
1694                     self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi))?;
1695                 }
1696                 _ => self.print_stmt(st)?,
1697             }
1698         }
1699
1700         self.bclose_maybe_open(blk.span, indented, close_box)?;
1701         self.ann.post(self, NodeBlock(blk))
1702     }
1703
1704     fn print_else(&mut self, els: Option<&ast::Expr>) -> io::Result<()> {
1705         match els {
1706             Some(_else) => {
1707                 match _else.node {
1708                     // "another else-if"
1709                     ast::ExprKind::If(ref i, ref then, ref e) => {
1710                         self.cbox(INDENT_UNIT - 1)?;
1711                         self.ibox(0)?;
1712                         word(&mut self.s, " else if ")?;
1713                         self.print_expr(&i)?;
1714                         space(&mut self.s)?;
1715                         self.print_block(&then)?;
1716                         self.print_else(e.as_ref().map(|e| &**e))
1717                     }
1718                     // "another else-if-let"
1719                     ast::ExprKind::IfLet(ref pat, ref expr, ref then, ref e) => {
1720                         self.cbox(INDENT_UNIT - 1)?;
1721                         self.ibox(0)?;
1722                         word(&mut self.s, " else if let ")?;
1723                         self.print_pat(&pat)?;
1724                         space(&mut self.s)?;
1725                         self.word_space("=")?;
1726                         self.print_expr(&expr)?;
1727                         space(&mut self.s)?;
1728                         self.print_block(&then)?;
1729                         self.print_else(e.as_ref().map(|e| &**e))
1730                     }
1731                     // "final else"
1732                     ast::ExprKind::Block(ref b) => {
1733                         self.cbox(INDENT_UNIT - 1)?;
1734                         self.ibox(0)?;
1735                         word(&mut self.s, " else ")?;
1736                         self.print_block(&b)
1737                     }
1738                     // BLEAH, constraints would be great here
1739                     _ => {
1740                         panic!("print_if saw if with weird alternative");
1741                     }
1742                 }
1743             }
1744             _ => Ok(())
1745         }
1746     }
1747
1748     pub fn print_if(&mut self, test: &ast::Expr, blk: &ast::Block,
1749                     elseopt: Option<&ast::Expr>) -> io::Result<()> {
1750         self.head("if")?;
1751         self.print_expr(test)?;
1752         space(&mut self.s)?;
1753         self.print_block(blk)?;
1754         self.print_else(elseopt)
1755     }
1756
1757     pub fn print_if_let(&mut self, pat: &ast::Pat, expr: &ast::Expr, blk: &ast::Block,
1758                         elseopt: Option<&ast::Expr>) -> io::Result<()> {
1759         self.head("if let")?;
1760         self.print_pat(pat)?;
1761         space(&mut self.s)?;
1762         self.word_space("=")?;
1763         self.print_expr(expr)?;
1764         space(&mut self.s)?;
1765         self.print_block(blk)?;
1766         self.print_else(elseopt)
1767     }
1768
1769     pub fn print_mac(&mut self, m: &ast::Mac, delim: token::DelimToken)
1770                      -> io::Result<()> {
1771         self.print_path(&m.node.path, false, 0, false)?;
1772         word(&mut self.s, "!")?;
1773         match delim {
1774             token::Paren => self.popen()?,
1775             token::Bracket => word(&mut self.s, "[")?,
1776             token::Brace => {
1777                 self.head("")?;
1778                 self.bopen()?;
1779             }
1780             token::NoDelim => {}
1781         }
1782         self.print_tts(m.node.stream())?;
1783         match delim {
1784             token::Paren => self.pclose(),
1785             token::Bracket => word(&mut self.s, "]"),
1786             token::Brace => self.bclose(m.span),
1787             token::NoDelim => Ok(()),
1788         }
1789     }
1790
1791
1792     fn print_call_post(&mut self, args: &[P<ast::Expr>]) -> io::Result<()> {
1793         self.popen()?;
1794         self.commasep_exprs(Inconsistent, args)?;
1795         self.pclose()
1796     }
1797
1798     pub fn check_expr_bin_needs_paren(&mut self, sub_expr: &ast::Expr,
1799                                       binop: ast::BinOp) -> bool {
1800         match sub_expr.node {
1801             ast::ExprKind::Binary(ref sub_op, _, _) => {
1802                 if AssocOp::from_ast_binop(sub_op.node).precedence() <
1803                     AssocOp::from_ast_binop(binop.node).precedence() {
1804                     true
1805                 } else {
1806                     false
1807                 }
1808             }
1809             _ => true
1810         }
1811     }
1812
1813     pub fn print_expr_maybe_paren(&mut self, expr: &ast::Expr) -> io::Result<()> {
1814         let needs_par = needs_parentheses(expr);
1815         if needs_par {
1816             self.popen()?;
1817         }
1818         self.print_expr(expr)?;
1819         if needs_par {
1820             self.pclose()?;
1821         }
1822         Ok(())
1823     }
1824
1825     fn print_expr_in_place(&mut self,
1826                            place: &ast::Expr,
1827                            expr: &ast::Expr) -> io::Result<()> {
1828         self.print_expr_maybe_paren(place)?;
1829         space(&mut self.s)?;
1830         self.word_space("<-")?;
1831         self.print_expr_maybe_paren(expr)
1832     }
1833
1834     fn print_expr_vec(&mut self, exprs: &[P<ast::Expr>],
1835                       attrs: &[Attribute]) -> io::Result<()> {
1836         self.ibox(INDENT_UNIT)?;
1837         word(&mut self.s, "[")?;
1838         self.print_inner_attributes_inline(attrs)?;
1839         self.commasep_exprs(Inconsistent, &exprs[..])?;
1840         word(&mut self.s, "]")?;
1841         self.end()
1842     }
1843
1844     fn print_expr_repeat(&mut self,
1845                          element: &ast::Expr,
1846                          count: &ast::Expr,
1847                          attrs: &[Attribute]) -> io::Result<()> {
1848         self.ibox(INDENT_UNIT)?;
1849         word(&mut self.s, "[")?;
1850         self.print_inner_attributes_inline(attrs)?;
1851         self.print_expr(element)?;
1852         self.word_space(";")?;
1853         self.print_expr(count)?;
1854         word(&mut self.s, "]")?;
1855         self.end()
1856     }
1857
1858     fn print_expr_struct(&mut self,
1859                          path: &ast::Path,
1860                          fields: &[ast::Field],
1861                          wth: &Option<P<ast::Expr>>,
1862                          attrs: &[Attribute]) -> io::Result<()> {
1863         self.print_path(path, true, 0, false)?;
1864         word(&mut self.s, "{")?;
1865         self.print_inner_attributes_inline(attrs)?;
1866         self.commasep_cmnt(
1867             Consistent,
1868             &fields[..],
1869             |s, field| {
1870                 s.ibox(INDENT_UNIT)?;
1871                 if !field.is_shorthand {
1872                     s.print_ident(field.ident.node)?;
1873                     s.word_space(":")?;
1874                 }
1875                 s.print_expr(&field.expr)?;
1876                 s.end()
1877             },
1878             |f| f.span)?;
1879         match *wth {
1880             Some(ref expr) => {
1881                 self.ibox(INDENT_UNIT)?;
1882                 if !fields.is_empty() {
1883                     word(&mut self.s, ",")?;
1884                     space(&mut self.s)?;
1885                 }
1886                 word(&mut self.s, "..")?;
1887                 self.print_expr(&expr)?;
1888                 self.end()?;
1889             }
1890             _ => if !fields.is_empty() {
1891                 word(&mut self.s, ",")?
1892             }
1893         }
1894         word(&mut self.s, "}")?;
1895         Ok(())
1896     }
1897
1898     fn print_expr_tup(&mut self, exprs: &[P<ast::Expr>],
1899                       attrs: &[Attribute]) -> io::Result<()> {
1900         self.popen()?;
1901         self.print_inner_attributes_inline(attrs)?;
1902         self.commasep_exprs(Inconsistent, &exprs[..])?;
1903         if exprs.len() == 1 {
1904             word(&mut self.s, ",")?;
1905         }
1906         self.pclose()
1907     }
1908
1909     fn print_expr_call(&mut self,
1910                        func: &ast::Expr,
1911                        args: &[P<ast::Expr>]) -> io::Result<()> {
1912         self.print_expr_maybe_paren(func)?;
1913         self.print_call_post(args)
1914     }
1915
1916     fn print_expr_method_call(&mut self,
1917                               ident: ast::SpannedIdent,
1918                               tys: &[P<ast::Ty>],
1919                               args: &[P<ast::Expr>]) -> io::Result<()> {
1920         let base_args = &args[1..];
1921         self.print_expr(&args[0])?;
1922         word(&mut self.s, ".")?;
1923         self.print_ident(ident.node)?;
1924         if !tys.is_empty() {
1925             word(&mut self.s, "::<")?;
1926             self.commasep(Inconsistent, tys,
1927                           |s, ty| s.print_type(&ty))?;
1928             word(&mut self.s, ">")?;
1929         }
1930         self.print_call_post(base_args)
1931     }
1932
1933     fn print_expr_binary(&mut self,
1934                          op: ast::BinOp,
1935                          lhs: &ast::Expr,
1936                          rhs: &ast::Expr) -> io::Result<()> {
1937         if self.check_expr_bin_needs_paren(lhs, op) {
1938             self.print_expr_maybe_paren(lhs)?;
1939         } else {
1940             self.print_expr(lhs)?;
1941         }
1942         space(&mut self.s)?;
1943         self.word_space(op.node.to_string())?;
1944         if self.check_expr_bin_needs_paren(rhs, op) {
1945             self.print_expr_maybe_paren(rhs)
1946         } else {
1947             self.print_expr(rhs)
1948         }
1949     }
1950
1951     fn print_expr_unary(&mut self,
1952                         op: ast::UnOp,
1953                         expr: &ast::Expr) -> io::Result<()> {
1954         word(&mut self.s, ast::UnOp::to_string(op))?;
1955         self.print_expr_maybe_paren(expr)
1956     }
1957
1958     fn print_expr_addr_of(&mut self,
1959                           mutability: ast::Mutability,
1960                           expr: &ast::Expr) -> io::Result<()> {
1961         word(&mut self.s, "&")?;
1962         self.print_mutability(mutability)?;
1963         self.print_expr_maybe_paren(expr)
1964     }
1965
1966     pub fn print_expr(&mut self, expr: &ast::Expr) -> io::Result<()> {
1967         self.print_expr_outer_attr_style(expr, true)
1968     }
1969
1970     fn print_expr_outer_attr_style(&mut self,
1971                                   expr: &ast::Expr,
1972                                   is_inline: bool) -> io::Result<()> {
1973         self.maybe_print_comment(expr.span.lo)?;
1974
1975         let attrs = &expr.attrs;
1976         if is_inline {
1977             self.print_outer_attributes_inline(attrs)?;
1978         } else {
1979             self.print_outer_attributes(attrs)?;
1980         }
1981
1982         self.ibox(INDENT_UNIT)?;
1983         self.ann.pre(self, NodeExpr(expr))?;
1984         match expr.node {
1985             ast::ExprKind::Box(ref expr) => {
1986                 self.word_space("box")?;
1987                 self.print_expr(expr)?;
1988             }
1989             ast::ExprKind::InPlace(ref place, ref expr) => {
1990                 self.print_expr_in_place(place, expr)?;
1991             }
1992             ast::ExprKind::Array(ref exprs) => {
1993                 self.print_expr_vec(&exprs[..], attrs)?;
1994             }
1995             ast::ExprKind::Repeat(ref element, ref count) => {
1996                 self.print_expr_repeat(&element, &count, attrs)?;
1997             }
1998             ast::ExprKind::Struct(ref path, ref fields, ref wth) => {
1999                 self.print_expr_struct(path, &fields[..], wth, attrs)?;
2000             }
2001             ast::ExprKind::Tup(ref exprs) => {
2002                 self.print_expr_tup(&exprs[..], attrs)?;
2003             }
2004             ast::ExprKind::Call(ref func, ref args) => {
2005                 self.print_expr_call(&func, &args[..])?;
2006             }
2007             ast::ExprKind::MethodCall(ident, ref tys, ref args) => {
2008                 self.print_expr_method_call(ident, &tys[..], &args[..])?;
2009             }
2010             ast::ExprKind::Binary(op, ref lhs, ref rhs) => {
2011                 self.print_expr_binary(op, &lhs, &rhs)?;
2012             }
2013             ast::ExprKind::Unary(op, ref expr) => {
2014                 self.print_expr_unary(op, &expr)?;
2015             }
2016             ast::ExprKind::AddrOf(m, ref expr) => {
2017                 self.print_expr_addr_of(m, &expr)?;
2018             }
2019             ast::ExprKind::Lit(ref lit) => {
2020                 self.print_literal(&lit)?;
2021             }
2022             ast::ExprKind::Cast(ref expr, ref ty) => {
2023                 if let ast::ExprKind::Cast(..) = expr.node {
2024                     self.print_expr(&expr)?;
2025                 } else {
2026                     self.print_expr_maybe_paren(&expr)?;
2027                 }
2028                 space(&mut self.s)?;
2029                 self.word_space("as")?;
2030                 self.print_type(&ty)?;
2031             }
2032             ast::ExprKind::Type(ref expr, ref ty) => {
2033                 self.print_expr(&expr)?;
2034                 self.word_space(":")?;
2035                 self.print_type(&ty)?;
2036             }
2037             ast::ExprKind::If(ref test, ref blk, ref elseopt) => {
2038                 self.print_if(&test, &blk, elseopt.as_ref().map(|e| &**e))?;
2039             }
2040             ast::ExprKind::IfLet(ref pat, ref expr, ref blk, ref elseopt) => {
2041                 self.print_if_let(&pat, &expr, &blk, elseopt.as_ref().map(|e| &**e))?;
2042             }
2043             ast::ExprKind::While(ref test, ref blk, opt_ident) => {
2044                 if let Some(ident) = opt_ident {
2045                     self.print_ident(ident.node)?;
2046                     self.word_space(":")?;
2047                 }
2048                 self.head("while")?;
2049                 self.print_expr(&test)?;
2050                 space(&mut self.s)?;
2051                 self.print_block_with_attrs(&blk, attrs)?;
2052             }
2053             ast::ExprKind::WhileLet(ref pat, ref expr, ref blk, opt_ident) => {
2054                 if let Some(ident) = opt_ident {
2055                     self.print_ident(ident.node)?;
2056                     self.word_space(":")?;
2057                 }
2058                 self.head("while let")?;
2059                 self.print_pat(&pat)?;
2060                 space(&mut self.s)?;
2061                 self.word_space("=")?;
2062                 self.print_expr(&expr)?;
2063                 space(&mut self.s)?;
2064                 self.print_block_with_attrs(&blk, attrs)?;
2065             }
2066             ast::ExprKind::ForLoop(ref pat, ref iter, ref blk, opt_ident) => {
2067                 if let Some(ident) = opt_ident {
2068                     self.print_ident(ident.node)?;
2069                     self.word_space(":")?;
2070                 }
2071                 self.head("for")?;
2072                 self.print_pat(&pat)?;
2073                 space(&mut self.s)?;
2074                 self.word_space("in")?;
2075                 self.print_expr(&iter)?;
2076                 space(&mut self.s)?;
2077                 self.print_block_with_attrs(&blk, attrs)?;
2078             }
2079             ast::ExprKind::Loop(ref blk, opt_ident) => {
2080                 if let Some(ident) = opt_ident {
2081                     self.print_ident(ident.node)?;
2082                     self.word_space(":")?;
2083                 }
2084                 self.head("loop")?;
2085                 space(&mut self.s)?;
2086                 self.print_block_with_attrs(&blk, attrs)?;
2087             }
2088             ast::ExprKind::Match(ref expr, ref arms) => {
2089                 self.cbox(INDENT_UNIT)?;
2090                 self.ibox(4)?;
2091                 self.word_nbsp("match")?;
2092                 self.print_expr(&expr)?;
2093                 space(&mut self.s)?;
2094                 self.bopen()?;
2095                 self.print_inner_attributes_no_trailing_hardbreak(attrs)?;
2096                 for arm in arms {
2097                     self.print_arm(arm)?;
2098                 }
2099                 self.bclose_(expr.span, INDENT_UNIT)?;
2100             }
2101             ast::ExprKind::Closure(capture_clause, ref decl, ref body, _) => {
2102                 self.print_capture_clause(capture_clause)?;
2103
2104                 self.print_fn_block_args(&decl)?;
2105                 space(&mut self.s)?;
2106                 self.print_expr(body)?;
2107                 self.end()?; // need to close a box
2108
2109                 // a box will be closed by print_expr, but we didn't want an overall
2110                 // wrapper so we closed the corresponding opening. so create an
2111                 // empty box to satisfy the close.
2112                 self.ibox(0)?;
2113             }
2114             ast::ExprKind::Block(ref blk) => {
2115                 // containing cbox, will be closed by print-block at }
2116                 self.cbox(INDENT_UNIT)?;
2117                 // head-box, will be closed by print-block after {
2118                 self.ibox(0)?;
2119                 self.print_block_with_attrs(&blk, attrs)?;
2120             }
2121             ast::ExprKind::Assign(ref lhs, ref rhs) => {
2122                 self.print_expr(&lhs)?;
2123                 space(&mut self.s)?;
2124                 self.word_space("=")?;
2125                 self.print_expr(&rhs)?;
2126             }
2127             ast::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
2128                 self.print_expr(&lhs)?;
2129                 space(&mut self.s)?;
2130                 word(&mut self.s, op.node.to_string())?;
2131                 self.word_space("=")?;
2132                 self.print_expr(&rhs)?;
2133             }
2134             ast::ExprKind::Field(ref expr, id) => {
2135                 self.print_expr(&expr)?;
2136                 word(&mut self.s, ".")?;
2137                 self.print_ident(id.node)?;
2138             }
2139             ast::ExprKind::TupField(ref expr, id) => {
2140                 self.print_expr(&expr)?;
2141                 word(&mut self.s, ".")?;
2142                 self.print_usize(id.node)?;
2143             }
2144             ast::ExprKind::Index(ref expr, ref index) => {
2145                 self.print_expr(&expr)?;
2146                 word(&mut self.s, "[")?;
2147                 self.print_expr(&index)?;
2148                 word(&mut self.s, "]")?;
2149             }
2150             ast::ExprKind::Range(ref start, ref end, limits) => {
2151                 if let &Some(ref e) = start {
2152                     self.print_expr(&e)?;
2153                 }
2154                 if limits == ast::RangeLimits::HalfOpen {
2155                     word(&mut self.s, "..")?;
2156                 } else {
2157                     word(&mut self.s, "...")?;
2158                 }
2159                 if let &Some(ref e) = end {
2160                     self.print_expr(&e)?;
2161                 }
2162             }
2163             ast::ExprKind::Path(None, ref path) => {
2164                 self.print_path(path, true, 0, false)?
2165             }
2166             ast::ExprKind::Path(Some(ref qself), ref path) => {
2167                 self.print_qpath(path, qself, true)?
2168             }
2169             ast::ExprKind::Break(opt_ident, ref opt_expr) => {
2170                 word(&mut self.s, "break")?;
2171                 space(&mut self.s)?;
2172                 if let Some(ident) = opt_ident {
2173                     self.print_ident(ident.node)?;
2174                     space(&mut self.s)?;
2175                 }
2176                 if let Some(ref expr) = *opt_expr {
2177                     self.print_expr(expr)?;
2178                     space(&mut self.s)?;
2179                 }
2180             }
2181             ast::ExprKind::Continue(opt_ident) => {
2182                 word(&mut self.s, "continue")?;
2183                 space(&mut self.s)?;
2184                 if let Some(ident) = opt_ident {
2185                     self.print_ident(ident.node)?;
2186                     space(&mut self.s)?
2187                 }
2188             }
2189             ast::ExprKind::Ret(ref result) => {
2190                 word(&mut self.s, "return")?;
2191                 match *result {
2192                     Some(ref expr) => {
2193                         word(&mut self.s, " ")?;
2194                         self.print_expr(&expr)?;
2195                     }
2196                     _ => ()
2197                 }
2198             }
2199             ast::ExprKind::InlineAsm(ref a) => {
2200                 word(&mut self.s, "asm!")?;
2201                 self.popen()?;
2202                 self.print_string(&a.asm.as_str(), a.asm_str_style)?;
2203                 self.word_space(":")?;
2204
2205                 self.commasep(Inconsistent, &a.outputs, |s, out| {
2206                     let constraint = out.constraint.as_str();
2207                     let mut ch = constraint.chars();
2208                     match ch.next() {
2209                         Some('=') if out.is_rw => {
2210                             s.print_string(&format!("+{}", ch.as_str()),
2211                                            ast::StrStyle::Cooked)?
2212                         }
2213                         _ => s.print_string(&constraint, ast::StrStyle::Cooked)?
2214                     }
2215                     s.popen()?;
2216                     s.print_expr(&out.expr)?;
2217                     s.pclose()?;
2218                     Ok(())
2219                 })?;
2220                 space(&mut self.s)?;
2221                 self.word_space(":")?;
2222
2223                 self.commasep(Inconsistent, &a.inputs, |s, &(co, ref o)| {
2224                     s.print_string(&co.as_str(), ast::StrStyle::Cooked)?;
2225                     s.popen()?;
2226                     s.print_expr(&o)?;
2227                     s.pclose()?;
2228                     Ok(())
2229                 })?;
2230                 space(&mut self.s)?;
2231                 self.word_space(":")?;
2232
2233                 self.commasep(Inconsistent, &a.clobbers,
2234                                    |s, co| {
2235                     s.print_string(&co.as_str(), ast::StrStyle::Cooked)?;
2236                     Ok(())
2237                 })?;
2238
2239                 let mut options = vec![];
2240                 if a.volatile {
2241                     options.push("volatile");
2242                 }
2243                 if a.alignstack {
2244                     options.push("alignstack");
2245                 }
2246                 if a.dialect == ast::AsmDialect::Intel {
2247                     options.push("intel");
2248                 }
2249
2250                 if !options.is_empty() {
2251                     space(&mut self.s)?;
2252                     self.word_space(":")?;
2253                     self.commasep(Inconsistent, &options,
2254                                   |s, &co| {
2255                                       s.print_string(co, ast::StrStyle::Cooked)?;
2256                                       Ok(())
2257                                   })?;
2258                 }
2259
2260                 self.pclose()?;
2261             }
2262             ast::ExprKind::Mac(ref m) => self.print_mac(m, token::Paren)?,
2263             ast::ExprKind::Paren(ref e) => {
2264                 self.popen()?;
2265                 self.print_inner_attributes_inline(attrs)?;
2266                 self.print_expr(&e)?;
2267                 self.pclose()?;
2268             },
2269             ast::ExprKind::Try(ref e) => {
2270                 self.print_expr(e)?;
2271                 word(&mut self.s, "?")?
2272             }
2273         }
2274         self.ann.post(self, NodeExpr(expr))?;
2275         self.end()
2276     }
2277
2278     pub fn print_local_decl(&mut self, loc: &ast::Local) -> io::Result<()> {
2279         self.print_pat(&loc.pat)?;
2280         if let Some(ref ty) = loc.ty {
2281             self.word_space(":")?;
2282             self.print_type(&ty)?;
2283         }
2284         Ok(())
2285     }
2286
2287     pub fn print_ident(&mut self, ident: ast::Ident) -> io::Result<()> {
2288         word(&mut self.s, &ident.name.as_str())?;
2289         self.ann.post(self, NodeIdent(&ident))
2290     }
2291
2292     pub fn print_usize(&mut self, i: usize) -> io::Result<()> {
2293         word(&mut self.s, &i.to_string())
2294     }
2295
2296     pub fn print_name(&mut self, name: ast::Name) -> io::Result<()> {
2297         word(&mut self.s, &name.as_str())?;
2298         self.ann.post(self, NodeName(&name))
2299     }
2300
2301     pub fn print_for_decl(&mut self, loc: &ast::Local,
2302                           coll: &ast::Expr) -> io::Result<()> {
2303         self.print_local_decl(loc)?;
2304         space(&mut self.s)?;
2305         self.word_space("in")?;
2306         self.print_expr(coll)
2307     }
2308
2309     fn print_path(&mut self,
2310                   path: &ast::Path,
2311                   colons_before_params: bool,
2312                   depth: usize,
2313                   defaults_to_global: bool)
2314                   -> io::Result<()>
2315     {
2316         self.maybe_print_comment(path.span.lo)?;
2317
2318         let mut segments = path.segments[..path.segments.len()-depth].iter();
2319         if defaults_to_global && path.is_global() {
2320             segments.next();
2321         }
2322         for (i, segment) in segments.enumerate() {
2323             if i > 0 {
2324                 word(&mut self.s, "::")?
2325             }
2326             if segment.identifier.name != keywords::CrateRoot.name() &&
2327                segment.identifier.name != "$crate" {
2328                 self.print_ident(segment.identifier)?;
2329                 if let Some(ref parameters) = segment.parameters {
2330                     self.print_path_parameters(parameters, colons_before_params)?;
2331                 }
2332             }
2333         }
2334
2335         Ok(())
2336     }
2337
2338     fn print_qpath(&mut self,
2339                    path: &ast::Path,
2340                    qself: &ast::QSelf,
2341                    colons_before_params: bool)
2342                    -> io::Result<()>
2343     {
2344         word(&mut self.s, "<")?;
2345         self.print_type(&qself.ty)?;
2346         if qself.position > 0 {
2347             space(&mut self.s)?;
2348             self.word_space("as")?;
2349             let depth = path.segments.len() - qself.position;
2350             self.print_path(&path, false, depth, false)?;
2351         }
2352         word(&mut self.s, ">")?;
2353         word(&mut self.s, "::")?;
2354         let item_segment = path.segments.last().unwrap();
2355         self.print_ident(item_segment.identifier)?;
2356         match item_segment.parameters {
2357             Some(ref parameters) => self.print_path_parameters(parameters, colons_before_params),
2358             None => Ok(()),
2359         }
2360     }
2361
2362     fn print_path_parameters(&mut self,
2363                              parameters: &ast::PathParameters,
2364                              colons_before_params: bool)
2365                              -> io::Result<()>
2366     {
2367         if colons_before_params {
2368             word(&mut self.s, "::")?
2369         }
2370
2371         match *parameters {
2372             ast::PathParameters::AngleBracketed(ref data) => {
2373                 word(&mut self.s, "<")?;
2374
2375                 let mut comma = false;
2376                 for lifetime in &data.lifetimes {
2377                     if comma {
2378                         self.word_space(",")?
2379                     }
2380                     self.print_lifetime(lifetime)?;
2381                     comma = true;
2382                 }
2383
2384                 if !data.types.is_empty() {
2385                     if comma {
2386                         self.word_space(",")?
2387                     }
2388                     self.commasep(
2389                         Inconsistent,
2390                         &data.types,
2391                         |s, ty| s.print_type(&ty))?;
2392                         comma = true;
2393                 }
2394
2395                 for binding in data.bindings.iter() {
2396                     if comma {
2397                         self.word_space(",")?
2398                     }
2399                     self.print_ident(binding.ident)?;
2400                     space(&mut self.s)?;
2401                     self.word_space("=")?;
2402                     self.print_type(&binding.ty)?;
2403                     comma = true;
2404                 }
2405
2406                 word(&mut self.s, ">")?
2407             }
2408
2409             ast::PathParameters::Parenthesized(ref data) => {
2410                 word(&mut self.s, "(")?;
2411                 self.commasep(
2412                     Inconsistent,
2413                     &data.inputs,
2414                     |s, ty| s.print_type(&ty))?;
2415                 word(&mut self.s, ")")?;
2416
2417                 if let Some(ref ty) = data.output {
2418                     self.space_if_not_bol()?;
2419                     self.word_space("->")?;
2420                     self.print_type(&ty)?;
2421                 }
2422             }
2423         }
2424
2425         Ok(())
2426     }
2427
2428     pub fn print_pat(&mut self, pat: &ast::Pat) -> io::Result<()> {
2429         self.maybe_print_comment(pat.span.lo)?;
2430         self.ann.pre(self, NodePat(pat))?;
2431         /* Pat isn't normalized, but the beauty of it
2432          is that it doesn't matter */
2433         match pat.node {
2434             PatKind::Wild => word(&mut self.s, "_")?,
2435             PatKind::Ident(binding_mode, ref path1, ref sub) => {
2436                 match binding_mode {
2437                     ast::BindingMode::ByRef(mutbl) => {
2438                         self.word_nbsp("ref")?;
2439                         self.print_mutability(mutbl)?;
2440                     }
2441                     ast::BindingMode::ByValue(ast::Mutability::Immutable) => {}
2442                     ast::BindingMode::ByValue(ast::Mutability::Mutable) => {
2443                         self.word_nbsp("mut")?;
2444                     }
2445                 }
2446                 self.print_ident(path1.node)?;
2447                 if let Some(ref p) = *sub {
2448                     word(&mut self.s, "@")?;
2449                     self.print_pat(&p)?;
2450                 }
2451             }
2452             PatKind::TupleStruct(ref path, ref elts, ddpos) => {
2453                 self.print_path(path, true, 0, false)?;
2454                 self.popen()?;
2455                 if let Some(ddpos) = ddpos {
2456                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p))?;
2457                     if ddpos != 0 {
2458                         self.word_space(",")?;
2459                     }
2460                     word(&mut self.s, "..")?;
2461                     if ddpos != elts.len() {
2462                         word(&mut self.s, ",")?;
2463                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p))?;
2464                     }
2465                 } else {
2466                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p))?;
2467                 }
2468                 self.pclose()?;
2469             }
2470             PatKind::Path(None, ref path) => {
2471                 self.print_path(path, true, 0, false)?;
2472             }
2473             PatKind::Path(Some(ref qself), ref path) => {
2474                 self.print_qpath(path, qself, false)?;
2475             }
2476             PatKind::Struct(ref path, ref fields, etc) => {
2477                 self.print_path(path, true, 0, false)?;
2478                 self.nbsp()?;
2479                 self.word_space("{")?;
2480                 self.commasep_cmnt(
2481                     Consistent, &fields[..],
2482                     |s, f| {
2483                         s.cbox(INDENT_UNIT)?;
2484                         if !f.node.is_shorthand {
2485                             s.print_ident(f.node.ident)?;
2486                             s.word_nbsp(":")?;
2487                         }
2488                         s.print_pat(&f.node.pat)?;
2489                         s.end()
2490                     },
2491                     |f| f.node.pat.span)?;
2492                 if etc {
2493                     if !fields.is_empty() { self.word_space(",")?; }
2494                     word(&mut self.s, "..")?;
2495                 }
2496                 space(&mut self.s)?;
2497                 word(&mut self.s, "}")?;
2498             }
2499             PatKind::Tuple(ref elts, ddpos) => {
2500                 self.popen()?;
2501                 if let Some(ddpos) = ddpos {
2502                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p))?;
2503                     if ddpos != 0 {
2504                         self.word_space(",")?;
2505                     }
2506                     word(&mut self.s, "..")?;
2507                     if ddpos != elts.len() {
2508                         word(&mut self.s, ",")?;
2509                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p))?;
2510                     }
2511                 } else {
2512                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p))?;
2513                     if elts.len() == 1 {
2514                         word(&mut self.s, ",")?;
2515                     }
2516                 }
2517                 self.pclose()?;
2518             }
2519             PatKind::Box(ref inner) => {
2520                 word(&mut self.s, "box ")?;
2521                 self.print_pat(&inner)?;
2522             }
2523             PatKind::Ref(ref inner, mutbl) => {
2524                 word(&mut self.s, "&")?;
2525                 if mutbl == ast::Mutability::Mutable {
2526                     word(&mut self.s, "mut ")?;
2527                 }
2528                 self.print_pat(&inner)?;
2529             }
2530             PatKind::Lit(ref e) => self.print_expr(&**e)?,
2531             PatKind::Range(ref begin, ref end, ref end_kind) => {
2532                 self.print_expr(&begin)?;
2533                 space(&mut self.s)?;
2534                 match *end_kind {
2535                     RangeEnd::Included => word(&mut self.s, "...")?,
2536                     RangeEnd::Excluded => word(&mut self.s, "..")?,
2537                 }
2538                 self.print_expr(&end)?;
2539             }
2540             PatKind::Slice(ref before, ref slice, ref after) => {
2541                 word(&mut self.s, "[")?;
2542                 self.commasep(Inconsistent,
2543                                    &before[..],
2544                                    |s, p| s.print_pat(&p))?;
2545                 if let Some(ref p) = *slice {
2546                     if !before.is_empty() { self.word_space(",")?; }
2547                     if p.node != PatKind::Wild {
2548                         self.print_pat(&p)?;
2549                     }
2550                     word(&mut self.s, "..")?;
2551                     if !after.is_empty() { self.word_space(",")?; }
2552                 }
2553                 self.commasep(Inconsistent,
2554                                    &after[..],
2555                                    |s, p| s.print_pat(&p))?;
2556                 word(&mut self.s, "]")?;
2557             }
2558             PatKind::Mac(ref m) => self.print_mac(m, token::Paren)?,
2559         }
2560         self.ann.post(self, NodePat(pat))
2561     }
2562
2563     fn print_arm(&mut self, arm: &ast::Arm) -> io::Result<()> {
2564         // I have no idea why this check is necessary, but here it
2565         // is :(
2566         if arm.attrs.is_empty() {
2567             space(&mut self.s)?;
2568         }
2569         self.cbox(INDENT_UNIT)?;
2570         self.ibox(0)?;
2571         self.maybe_print_comment(arm.pats[0].span.lo)?;
2572         self.print_outer_attributes(&arm.attrs)?;
2573         let mut first = true;
2574         for p in &arm.pats {
2575             if first {
2576                 first = false;
2577             } else {
2578                 space(&mut self.s)?;
2579                 self.word_space("|")?;
2580             }
2581             self.print_pat(&p)?;
2582         }
2583         space(&mut self.s)?;
2584         if let Some(ref e) = arm.guard {
2585             self.word_space("if")?;
2586             self.print_expr(&e)?;
2587             space(&mut self.s)?;
2588         }
2589         self.word_space("=>")?;
2590
2591         match arm.body.node {
2592             ast::ExprKind::Block(ref blk) => {
2593                 // the block will close the pattern's ibox
2594                 self.print_block_unclosed_indent(&blk, INDENT_UNIT)?;
2595
2596                 // If it is a user-provided unsafe block, print a comma after it
2597                 if let BlockCheckMode::Unsafe(ast::UserProvided) = blk.rules {
2598                     word(&mut self.s, ",")?;
2599                 }
2600             }
2601             _ => {
2602                 self.end()?; // close the ibox for the pattern
2603                 self.print_expr(&arm.body)?;
2604                 word(&mut self.s, ",")?;
2605             }
2606         }
2607         self.end() // close enclosing cbox
2608     }
2609
2610     fn print_explicit_self(&mut self, explicit_self: &ast::ExplicitSelf) -> io::Result<()> {
2611         match explicit_self.node {
2612             SelfKind::Value(m) => {
2613                 self.print_mutability(m)?;
2614                 word(&mut self.s, "self")
2615             }
2616             SelfKind::Region(ref lt, m) => {
2617                 word(&mut self.s, "&")?;
2618                 self.print_opt_lifetime(lt)?;
2619                 self.print_mutability(m)?;
2620                 word(&mut self.s, "self")
2621             }
2622             SelfKind::Explicit(ref typ, m) => {
2623                 self.print_mutability(m)?;
2624                 word(&mut self.s, "self")?;
2625                 self.word_space(":")?;
2626                 self.print_type(&typ)
2627             }
2628         }
2629     }
2630
2631     pub fn print_fn(&mut self,
2632                     decl: &ast::FnDecl,
2633                     unsafety: ast::Unsafety,
2634                     constness: ast::Constness,
2635                     abi: abi::Abi,
2636                     name: Option<ast::Ident>,
2637                     generics: &ast::Generics,
2638                     vis: &ast::Visibility) -> io::Result<()> {
2639         self.print_fn_header_info(unsafety, constness, abi, vis)?;
2640
2641         if let Some(name) = name {
2642             self.nbsp()?;
2643             self.print_ident(name)?;
2644         }
2645         self.print_generics(generics)?;
2646         self.print_fn_args_and_ret(decl)?;
2647         self.print_where_clause(&generics.where_clause)
2648     }
2649
2650     pub fn print_fn_args_and_ret(&mut self, decl: &ast::FnDecl)
2651         -> io::Result<()> {
2652         self.popen()?;
2653         self.commasep(Inconsistent, &decl.inputs, |s, arg| s.print_arg(arg, false))?;
2654         if decl.variadic {
2655             word(&mut self.s, ", ...")?;
2656         }
2657         self.pclose()?;
2658
2659         self.print_fn_output(decl)
2660     }
2661
2662     pub fn print_fn_block_args(
2663             &mut self,
2664             decl: &ast::FnDecl)
2665             -> io::Result<()> {
2666         word(&mut self.s, "|")?;
2667         self.commasep(Inconsistent, &decl.inputs, |s, arg| s.print_arg(arg, true))?;
2668         word(&mut self.s, "|")?;
2669
2670         if let ast::FunctionRetTy::Default(..) = decl.output {
2671             return Ok(());
2672         }
2673
2674         self.space_if_not_bol()?;
2675         self.word_space("->")?;
2676         match decl.output {
2677             ast::FunctionRetTy::Ty(ref ty) => {
2678                 self.print_type(&ty)?;
2679                 self.maybe_print_comment(ty.span.lo)
2680             }
2681             ast::FunctionRetTy::Default(..) => unreachable!(),
2682         }
2683     }
2684
2685     pub fn print_capture_clause(&mut self, capture_clause: ast::CaptureBy)
2686                                 -> io::Result<()> {
2687         match capture_clause {
2688             ast::CaptureBy::Value => self.word_space("move"),
2689             ast::CaptureBy::Ref => Ok(()),
2690         }
2691     }
2692
2693     pub fn print_bounds(&mut self,
2694                         prefix: &str,
2695                         bounds: &[ast::TyParamBound])
2696                         -> io::Result<()> {
2697         if !bounds.is_empty() {
2698             word(&mut self.s, prefix)?;
2699             let mut first = true;
2700             for bound in bounds {
2701                 self.nbsp()?;
2702                 if first {
2703                     first = false;
2704                 } else {
2705                     self.word_space("+")?;
2706                 }
2707
2708                 (match *bound {
2709                     TraitTyParamBound(ref tref, TraitBoundModifier::None) => {
2710                         self.print_poly_trait_ref(tref)
2711                     }
2712                     TraitTyParamBound(ref tref, TraitBoundModifier::Maybe) => {
2713                         word(&mut self.s, "?")?;
2714                         self.print_poly_trait_ref(tref)
2715                     }
2716                     RegionTyParamBound(ref lt) => {
2717                         self.print_lifetime(lt)
2718                     }
2719                 })?
2720             }
2721             Ok(())
2722         } else {
2723             Ok(())
2724         }
2725     }
2726
2727     pub fn print_lifetime(&mut self,
2728                           lifetime: &ast::Lifetime)
2729                           -> io::Result<()>
2730     {
2731         self.print_name(lifetime.name)
2732     }
2733
2734     pub fn print_lifetime_bounds(&mut self,
2735                                  lifetime: &ast::Lifetime,
2736                                  bounds: &[ast::Lifetime])
2737                                  -> io::Result<()>
2738     {
2739         self.print_lifetime(lifetime)?;
2740         if !bounds.is_empty() {
2741             word(&mut self.s, ": ")?;
2742             for (i, bound) in bounds.iter().enumerate() {
2743                 if i != 0 {
2744                     word(&mut self.s, " + ")?;
2745                 }
2746                 self.print_lifetime(bound)?;
2747             }
2748         }
2749         Ok(())
2750     }
2751
2752     pub fn print_generics(&mut self,
2753                           generics: &ast::Generics)
2754                           -> io::Result<()>
2755     {
2756         let total = generics.lifetimes.len() + generics.ty_params.len();
2757         if total == 0 {
2758             return Ok(());
2759         }
2760
2761         word(&mut self.s, "<")?;
2762
2763         let mut ints = Vec::new();
2764         for i in 0..total {
2765             ints.push(i);
2766         }
2767
2768         self.commasep(Inconsistent, &ints[..], |s, &idx| {
2769             if idx < generics.lifetimes.len() {
2770                 let lifetime_def = &generics.lifetimes[idx];
2771                 s.print_outer_attributes_inline(&lifetime_def.attrs)?;
2772                 s.print_lifetime_bounds(&lifetime_def.lifetime, &lifetime_def.bounds)
2773             } else {
2774                 let idx = idx - generics.lifetimes.len();
2775                 let param = &generics.ty_params[idx];
2776                 s.print_ty_param(param)
2777             }
2778         })?;
2779
2780         word(&mut self.s, ">")?;
2781         Ok(())
2782     }
2783
2784     pub fn print_ty_param(&mut self, param: &ast::TyParam) -> io::Result<()> {
2785         self.print_outer_attributes_inline(&param.attrs)?;
2786         self.print_ident(param.ident)?;
2787         self.print_bounds(":", &param.bounds)?;
2788         match param.default {
2789             Some(ref default) => {
2790                 space(&mut self.s)?;
2791                 self.word_space("=")?;
2792                 self.print_type(&default)
2793             }
2794             _ => Ok(())
2795         }
2796     }
2797
2798     pub fn print_where_clause(&mut self, where_clause: &ast::WhereClause)
2799                               -> io::Result<()> {
2800         if where_clause.predicates.is_empty() {
2801             return Ok(())
2802         }
2803
2804         space(&mut self.s)?;
2805         self.word_space("where")?;
2806
2807         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2808             if i != 0 {
2809                 self.word_space(",")?;
2810             }
2811
2812             match *predicate {
2813                 ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate{ref bound_lifetimes,
2814                                                                              ref bounded_ty,
2815                                                                              ref bounds,
2816                                                                              ..}) => {
2817                     self.print_formal_lifetime_list(bound_lifetimes)?;
2818                     self.print_type(&bounded_ty)?;
2819                     self.print_bounds(":", bounds)?;
2820                 }
2821                 ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate{ref lifetime,
2822                                                                                ref bounds,
2823                                                                                ..}) => {
2824                     self.print_lifetime_bounds(lifetime, bounds)?;
2825                 }
2826                 ast::WherePredicate::EqPredicate(ast::WhereEqPredicate{ref lhs_ty,
2827                                                                        ref rhs_ty,
2828                                                                        ..}) => {
2829                     self.print_type(lhs_ty)?;
2830                     space(&mut self.s)?;
2831                     self.word_space("=")?;
2832                     self.print_type(rhs_ty)?;
2833                 }
2834             }
2835         }
2836
2837         Ok(())
2838     }
2839
2840     pub fn print_view_path(&mut self, vp: &ast::ViewPath) -> io::Result<()> {
2841         match vp.node {
2842             ast::ViewPathSimple(ident, ref path) => {
2843                 self.print_path(path, false, 0, true)?;
2844
2845                 if path.segments.last().unwrap().identifier.name !=
2846                         ident.name {
2847                     space(&mut self.s)?;
2848                     self.word_space("as")?;
2849                     self.print_ident(ident)?;
2850                 }
2851
2852                 Ok(())
2853             }
2854
2855             ast::ViewPathGlob(ref path) => {
2856                 self.print_path(path, false, 0, true)?;
2857                 word(&mut self.s, "::*")
2858             }
2859
2860             ast::ViewPathList(ref path, ref idents) => {
2861                 if path.segments.is_empty() {
2862                     word(&mut self.s, "{")?;
2863                 } else {
2864                     self.print_path(path, false, 0, true)?;
2865                     word(&mut self.s, "::{")?;
2866                 }
2867                 self.commasep(Inconsistent, &idents[..], |s, w| {
2868                     s.print_ident(w.node.name)?;
2869                     if let Some(ident) = w.node.rename {
2870                         space(&mut s.s)?;
2871                         s.word_space("as")?;
2872                         s.print_ident(ident)?;
2873                     }
2874                     Ok(())
2875                 })?;
2876                 word(&mut self.s, "}")
2877             }
2878         }
2879     }
2880
2881     pub fn print_mutability(&mut self,
2882                             mutbl: ast::Mutability) -> io::Result<()> {
2883         match mutbl {
2884             ast::Mutability::Mutable => self.word_nbsp("mut"),
2885             ast::Mutability::Immutable => Ok(()),
2886         }
2887     }
2888
2889     pub fn print_mt(&mut self, mt: &ast::MutTy) -> io::Result<()> {
2890         self.print_mutability(mt.mutbl)?;
2891         self.print_type(&mt.ty)
2892     }
2893
2894     pub fn print_arg(&mut self, input: &ast::Arg, is_closure: bool) -> io::Result<()> {
2895         self.ibox(INDENT_UNIT)?;
2896         match input.ty.node {
2897             ast::TyKind::Infer if is_closure => self.print_pat(&input.pat)?,
2898             _ => {
2899                 if let Some(eself) = input.to_self() {
2900                     self.print_explicit_self(&eself)?;
2901                 } else {
2902                     let invalid = if let PatKind::Ident(_, ident, _) = input.pat.node {
2903                         ident.node.name == keywords::Invalid.name()
2904                     } else {
2905                         false
2906                     };
2907                     if !invalid {
2908                         self.print_pat(&input.pat)?;
2909                         word(&mut self.s, ":")?;
2910                         space(&mut self.s)?;
2911                     }
2912                     self.print_type(&input.ty)?;
2913                 }
2914             }
2915         }
2916         self.end()
2917     }
2918
2919     pub fn print_fn_output(&mut self, decl: &ast::FnDecl) -> io::Result<()> {
2920         if let ast::FunctionRetTy::Default(..) = decl.output {
2921             return Ok(());
2922         }
2923
2924         self.space_if_not_bol()?;
2925         self.ibox(INDENT_UNIT)?;
2926         self.word_space("->")?;
2927         match decl.output {
2928             ast::FunctionRetTy::Default(..) => unreachable!(),
2929             ast::FunctionRetTy::Ty(ref ty) =>
2930                 self.print_type(&ty)?
2931         }
2932         self.end()?;
2933
2934         match decl.output {
2935             ast::FunctionRetTy::Ty(ref output) => self.maybe_print_comment(output.span.lo),
2936             _ => Ok(())
2937         }
2938     }
2939
2940     pub fn print_ty_fn(&mut self,
2941                        abi: abi::Abi,
2942                        unsafety: ast::Unsafety,
2943                        decl: &ast::FnDecl,
2944                        name: Option<ast::Ident>,
2945                        generics: &ast::Generics)
2946                        -> io::Result<()> {
2947         self.ibox(INDENT_UNIT)?;
2948         if !generics.lifetimes.is_empty() || !generics.ty_params.is_empty() {
2949             word(&mut self.s, "for")?;
2950             self.print_generics(generics)?;
2951         }
2952         let generics = ast::Generics {
2953             lifetimes: Vec::new(),
2954             ty_params: Vec::new(),
2955             where_clause: ast::WhereClause {
2956                 id: ast::DUMMY_NODE_ID,
2957                 predicates: Vec::new(),
2958             },
2959             span: syntax_pos::DUMMY_SP,
2960         };
2961         self.print_fn(decl,
2962                       unsafety,
2963                       ast::Constness::NotConst,
2964                       abi,
2965                       name,
2966                       &generics,
2967                       &ast::Visibility::Inherited)?;
2968         self.end()
2969     }
2970
2971     pub fn maybe_print_trailing_comment(&mut self, span: syntax_pos::Span,
2972                                         next_pos: Option<BytePos>)
2973         -> io::Result<()> {
2974         let cm = match self.cm {
2975             Some(cm) => cm,
2976             _ => return Ok(())
2977         };
2978         if let Some(ref cmnt) = self.next_comment() {
2979             if cmnt.style != comments::Trailing { return Ok(()) }
2980             let span_line = cm.lookup_char_pos(span.hi);
2981             let comment_line = cm.lookup_char_pos(cmnt.pos);
2982             let next = next_pos.unwrap_or(cmnt.pos + BytePos(1));
2983             if span.hi < cmnt.pos && cmnt.pos < next && span_line.line == comment_line.line {
2984                 self.print_comment(cmnt)?;
2985                 self.cur_cmnt_and_lit.cur_cmnt += 1;
2986             }
2987         }
2988         Ok(())
2989     }
2990
2991     pub fn print_remaining_comments(&mut self) -> io::Result<()> {
2992         // If there aren't any remaining comments, then we need to manually
2993         // make sure there is a line break at the end.
2994         if self.next_comment().is_none() {
2995             hardbreak(&mut self.s)?;
2996         }
2997         loop {
2998             match self.next_comment() {
2999                 Some(ref cmnt) => {
3000                     self.print_comment(cmnt)?;
3001                     self.cur_cmnt_and_lit.cur_cmnt += 1;
3002                 }
3003                 _ => break
3004             }
3005         }
3006         Ok(())
3007     }
3008
3009     pub fn print_opt_abi_and_extern_if_nondefault(&mut self,
3010                                                   opt_abi: Option<Abi>)
3011         -> io::Result<()> {
3012         match opt_abi {
3013             Some(Abi::Rust) => Ok(()),
3014             Some(abi) => {
3015                 self.word_nbsp("extern")?;
3016                 self.word_nbsp(&abi.to_string())
3017             }
3018             None => Ok(())
3019         }
3020     }
3021
3022     pub fn print_extern_opt_abi(&mut self,
3023                                 opt_abi: Option<Abi>) -> io::Result<()> {
3024         match opt_abi {
3025             Some(abi) => {
3026                 self.word_nbsp("extern")?;
3027                 self.word_nbsp(&abi.to_string())
3028             }
3029             None => Ok(())
3030         }
3031     }
3032
3033     pub fn print_fn_header_info(&mut self,
3034                                 unsafety: ast::Unsafety,
3035                                 constness: ast::Constness,
3036                                 abi: Abi,
3037                                 vis: &ast::Visibility) -> io::Result<()> {
3038         word(&mut self.s, &visibility_qualified(vis, ""))?;
3039
3040         match constness {
3041             ast::Constness::NotConst => {}
3042             ast::Constness::Const => self.word_nbsp("const")?
3043         }
3044
3045         self.print_unsafety(unsafety)?;
3046
3047         if abi != Abi::Rust {
3048             self.word_nbsp("extern")?;
3049             self.word_nbsp(&abi.to_string())?;
3050         }
3051
3052         word(&mut self.s, "fn")
3053     }
3054
3055     pub fn print_unsafety(&mut self, s: ast::Unsafety) -> io::Result<()> {
3056         match s {
3057             ast::Unsafety::Normal => Ok(()),
3058             ast::Unsafety::Unsafe => self.word_nbsp("unsafe"),
3059         }
3060     }
3061 }
3062
3063 fn repeat(s: &str, n: usize) -> String { iter::repeat(s).take(n).collect() }
3064
3065 #[cfg(test)]
3066 mod tests {
3067     use super::*;
3068
3069     use ast;
3070     use codemap;
3071     use syntax_pos;
3072
3073     #[test]
3074     fn test_fun_to_string() {
3075         let abba_ident = ast::Ident::from_str("abba");
3076
3077         let decl = ast::FnDecl {
3078             inputs: Vec::new(),
3079             output: ast::FunctionRetTy::Default(syntax_pos::DUMMY_SP),
3080             variadic: false
3081         };
3082         let generics = ast::Generics::default();
3083         assert_eq!(fun_to_string(&decl, ast::Unsafety::Normal,
3084                                  ast::Constness::NotConst,
3085                                  abba_ident, &generics),
3086                    "fn abba()");
3087     }
3088
3089     #[test]
3090     fn test_variant_to_string() {
3091         let ident = ast::Ident::from_str("principal_skinner");
3092
3093         let var = codemap::respan(syntax_pos::DUMMY_SP, ast::Variant_ {
3094             name: ident,
3095             attrs: Vec::new(),
3096             // making this up as I go.... ?
3097             data: ast::VariantData::Unit(ast::DUMMY_NODE_ID),
3098             disr_expr: None,
3099         });
3100
3101         let varstr = variant_to_string(&var);
3102         assert_eq!(varstr, "principal_skinner");
3103     }
3104 }