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, TokenStream, 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             token::NtVis(ref e)         => vis_to_string(&e),
 297         }
 298     }
 299 }
 300
 301 pub fn ty_to_string(ty: &ast::Ty) -> String {
 302     to_string(|s| s.print_type(ty))
 303 }
 304
 305 pub fn bounds_to_string(bounds: &[ast::TyParamBound]) -> String {
 306     to_string(|s| s.print_bounds("", bounds))
 307 }
 308
 309 pub fn pat_to_string(pat: &ast::Pat) -> String {
 310     to_string(|s| s.print_pat(pat))
 311 }
 312
 313 pub fn arm_to_string(arm: &ast::Arm) -> String {
 314     to_string(|s| s.print_arm(arm))
 315 }
 316
 317 pub fn expr_to_string(e: &ast::Expr) -> String {
 318     to_string(|s| s.print_expr(e))
 319 }
 320
 321 pub fn lifetime_to_string(e: &ast::Lifetime) -> String {
 322     to_string(|s| s.print_lifetime(e))
 323 }
 324
 325 pub fn tt_to_string(tt: tokenstream::TokenTree) -> String {
 326     to_string(|s| s.print_tt(tt))
 327 }
 328
 329 pub fn tts_to_string(tts: &[tokenstream::TokenTree]) -> String {
 330     to_string(|s| s.print_tts(tts.iter().cloned().collect()))
 331 }
 332
 333 pub fn tokens_to_string(tokens: TokenStream) -> String {
 334     to_string(|s| s.print_tts(tokens))
 335 }
 336
 337 pub fn stmt_to_string(stmt: &ast::Stmt) -> String {
 338     to_string(|s| s.print_stmt(stmt))
 339 }
 340
 341 pub fn attr_to_string(attr: &ast::Attribute) -> String {
 342     to_string(|s| s.print_attribute(attr))
 343 }
 344
 345 pub fn item_to_string(i: &ast::Item) -> String {
 346     to_string(|s| s.print_item(i))
 347 }
 348
 349 pub fn impl_item_to_string(i: &ast::ImplItem) -> String {
 350     to_string(|s| s.print_impl_item(i))
 351 }
 352
 353 pub fn trait_item_to_string(i: &ast::TraitItem) -> String {
 354     to_string(|s| s.print_trait_item(i))
 355 }
 356
 357 pub fn generics_to_string(generics: &ast::Generics) -> String {
 358     to_string(|s| s.print_generics(generics))
 359 }
 360
 361 pub fn where_clause_to_string(i: &ast::WhereClause) -> String {
 362     to_string(|s| s.print_where_clause(i))
 363 }
 364
 365 pub fn fn_block_to_string(p: &ast::FnDecl) -> String {
 366     to_string(|s| s.print_fn_block_args(p))
 367 }
 368
 369 pub fn path_to_string(p: &ast::Path) -> String {
 370     to_string(|s| s.print_path(p, false, 0, false))
 371 }
 372
 373 pub fn ident_to_string(id: ast::Ident) -> String {
 374     to_string(|s| s.print_ident(id))
 375 }
 376
 377 pub fn vis_to_string(v: &ast::Visibility) -> String {
 378     to_string(|s| s.print_visibility(v))
 379 }
 380
 381 pub fn fun_to_string(decl: &ast::FnDecl,
 382                      unsafety: ast::Unsafety,
 383                      constness: ast::Constness,
 384                      name: ast::Ident,
 385                      generics: &ast::Generics)
 386                      -> String {
 387     to_string(|s| {
 388         s.head("")?;
 389         s.print_fn(decl, unsafety, constness, Abi::Rust, Some(name),
 390                    generics, &ast::Visibility::Inherited)?;
 391         s.end()?; // Close the head box
 392         s.end() // Close the outer box
 393     })
 394 }
 395
 396 pub fn block_to_string(blk: &ast::Block) -> String {
 397     to_string(|s| {
 398         // containing cbox, will be closed by print-block at }
 399         s.cbox(INDENT_UNIT)?;
 400         // head-ibox, will be closed by print-block after {
 401         s.ibox(0)?;
 402         s.print_block(blk)
 403     })
 404 }
 405
 406 pub fn meta_list_item_to_string(li: &ast::NestedMetaItem) -> String {
 407     to_string(|s| s.print_meta_list_item(li))
 408 }
 409
 410 pub fn meta_item_to_string(mi: &ast::MetaItem) -> String {
 411     to_string(|s| s.print_meta_item(mi))
 412 }
 413
 414 pub fn attribute_to_string(attr: &ast::Attribute) -> String {
 415     to_string(|s| s.print_attribute(attr))
 416 }
 417
 418 pub fn lit_to_string(l: &ast::Lit) -> String {
 419     to_string(|s| s.print_literal(l))
 420 }
 421
 422 pub fn variant_to_string(var: &ast::Variant) -> String {
 423     to_string(|s| s.print_variant(var))
 424 }
 425
 426 pub fn arg_to_string(arg: &ast::Arg) -> String {
 427     to_string(|s| s.print_arg(arg, false))
 428 }
 429
 430 pub fn mac_to_string(arg: &ast::Mac) -> String {
 431     to_string(|s| s.print_mac(arg, ::parse::token::Paren))
 432 }
 433
 434 pub fn visibility_qualified(vis: &ast::Visibility, s: &str) -> String {
 435     format!("{}{}", to_string(|s| s.print_visibility(vis)), s)
 436 }
 437
 438 fn needs_parentheses(expr: &ast::Expr) -> bool {
 439     match expr.node {
 440         ast::ExprKind::Assign(..) | ast::ExprKind::Binary(..) |
 441         ast::ExprKind::Closure(..) |
 442         ast::ExprKind::AssignOp(..) | ast::ExprKind::Cast(..) |
 443         ast::ExprKind::InPlace(..) | ast::ExprKind::Type(..) => true,
 444         _ => false,
 445     }
 446 }
 447
 448 pub trait PrintState<'a> {
 449     fn writer(&mut self) -> &mut pp::Printer<'a>;
 450     fn boxes(&mut self) -> &mut Vec<pp::Breaks>;
 451     fn comments(&mut self) -> &mut Option<Vec<comments::Comment>>;
 452     fn cur_cmnt_and_lit(&mut self) -> &mut CurrentCommentAndLiteral;
 453     fn literals(&self) -> &Option<Vec<comments::Literal>>;
 454
 455     fn word_space(&mut self, w: &str) -> io::Result<()> {
 456         word(self.writer(), w)?;
 457         space(self.writer())
 458     }
 459
 460     fn popen(&mut self) -> io::Result<()> { word(self.writer(), "(") }
 461
 462     fn pclose(&mut self) -> io::Result<()> { word(self.writer(), ")") }
 463
 464     fn is_begin(&mut self) -> bool {
 465         match self.writer().last_token() {
 466             pp::Token::Begin(_) => true,
 467             _ => false,
 468         }
 469     }
 470
 471     fn is_end(&mut self) -> bool {
 472         match self.writer().last_token() {
 473             pp::Token::End => true,
 474             _ => false,
 475         }
 476     }
 477
 478     // is this the beginning of a line?
 479     fn is_bol(&mut self) -> bool {
 480         self.writer().last_token().is_eof() || self.writer().last_token().is_hardbreak_tok()
 481     }
 482
 483     fn hardbreak_if_not_bol(&mut self) -> io::Result<()> {
 484         if !self.is_bol() {
 485             hardbreak(self.writer())?
 486         }
 487         Ok(())
 488     }
 489
 490     // "raw box"
 491     fn rbox(&mut self, u: usize, b: pp::Breaks) -> io::Result<()> {
 492         self.boxes().push(b);
 493         pp::rbox(self.writer(), u, b)
 494     }
 495
 496     fn ibox(&mut self, u: usize) -> io::Result<()> {
 497         self.boxes().push(pp::Breaks::Inconsistent);
 498         pp::ibox(self.writer(), u)
 499     }
 500
 501     fn end(&mut self) -> io::Result<()> {
 502         self.boxes().pop().unwrap();
 503         pp::end(self.writer())
 504     }
 505
 506     fn commasep<T, F>(&mut self, b: Breaks, elts: &[T], mut op: F) -> io::Result<()>
 507         where F: FnMut(&mut Self, &T) -> io::Result<()>,
 508     {
 509         self.rbox(0, b)?;
 510         let mut first = true;
 511         for elt in elts {
 512             if first { first = false; } else { self.word_space(",")?; }
 513             op(self, elt)?;
 514         }
 515         self.end()
 516     }
 517
 518     fn next_lit(&mut self, pos: BytePos) -> Option<comments::Literal> {
 519         let mut cur_lit = self.cur_cmnt_and_lit().cur_lit;
 520
 521         let mut result = None;
 522
 523         if let &Some(ref lits) = self.literals()
 524         {
 525             while cur_lit < lits.len() {
 526                 let ltrl = (*lits)[cur_lit].clone();
 527                 if ltrl.pos > pos { break; }
 528                 cur_lit += 1;
 529                 if ltrl.pos == pos {
 530                     result = Some(ltrl);
 531                     break;
 532                 }
 533             }
 534         }
 535
 536         self.cur_cmnt_and_lit().cur_lit = cur_lit;
 537         result
 538     }
 539
 540     fn maybe_print_comment(&mut self, pos: BytePos) -> io::Result<()> {
 541         while let Some(ref cmnt) = self.next_comment() {
 542             if cmnt.pos < pos {
 543                 self.print_comment(cmnt)?;
 544                 self.cur_cmnt_and_lit().cur_cmnt += 1;
 545             } else {
 546                 break
 547             }
 548         }
 549         Ok(())
 550     }
 551
 552     fn print_comment(&mut self,
 553                      cmnt: &comments::Comment) -> io::Result<()> {
 554         match cmnt.style {
 555             comments::Mixed => {
 556                 assert_eq!(cmnt.lines.len(), 1);
 557                 zerobreak(self.writer())?;
 558                 word(self.writer(), &cmnt.lines[0])?;
 559                 zerobreak(self.writer())
 560             }
 561             comments::Isolated => {
 562                 self.hardbreak_if_not_bol()?;
 563                 for line in &cmnt.lines {
 564                     // Don't print empty lines because they will end up as trailing
 565                     // whitespace
 566                     if !line.is_empty() {
 567                         word(self.writer(), &line[..])?;
 568                     }
 569                     hardbreak(self.writer())?;
 570                 }
 571                 Ok(())
 572             }
 573             comments::Trailing => {
 574                 if !self.is_bol() {
 575                     word(self.writer(), " ")?;
 576                 }
 577                 if cmnt.lines.len() == 1 {
 578                     word(self.writer(), &cmnt.lines[0])?;
 579                     hardbreak(self.writer())
 580                 } else {
 581                     self.ibox(0)?;
 582                     for line in &cmnt.lines {
 583                         if !line.is_empty() {
 584                             word(self.writer(), &line[..])?;
 585                         }
 586                         hardbreak(self.writer())?;
 587                     }
 588                     self.end()
 589                 }
 590             }
 591             comments::BlankLine => {
 592                 // We need to do at least one, possibly two hardbreaks.
 593                 let is_semi = match self.writer().last_token() {
 594                     pp::Token::String(s, _) => ";" == s,
 595                     _ => false
 596                 };
 597                 if is_semi || self.is_begin() || self.is_end() {
 598                     hardbreak(self.writer())?;
 599                 }
 600                 hardbreak(self.writer())
 601             }
 602         }
 603     }
 604
 605     fn next_comment(&mut self) -> Option<comments::Comment> {
 606         let cur_cmnt = self.cur_cmnt_and_lit().cur_cmnt;
 607         match *self.comments() {
 608             Some(ref cmnts) => {
 609                 if cur_cmnt < cmnts.len() {
 610                     Some(cmnts[cur_cmnt].clone())
 611                 } else {
 612                     None
 613                 }
 614             }
 615             _ => None
 616         }
 617     }
 618
 619     fn print_literal(&mut self, lit: &ast::Lit) -> io::Result<()> {
 620         self.maybe_print_comment(lit.span.lo)?;
 621         match self.next_lit(lit.span.lo) {
 622             Some(ref ltrl) => {
 623                 return word(self.writer(), &(*ltrl).lit);
 624             }
 625             _ => ()
 626         }
 627         match lit.node {
 628             ast::LitKind::Str(st, style) => self.print_string(&st.as_str(), style),
 629             ast::LitKind::Byte(byte) => {
 630                 let mut res = String::from("b'");
 631                 res.extend(ascii::escape_default(byte).map(|c| c as char));
 632                 res.push('\'');
 633                 word(self.writer(), &res[..])
 634             }
 635             ast::LitKind::Char(ch) => {
 636                 let mut res = String::from("'");
 637                 res.extend(ch.escape_default());
 638                 res.push('\'');
 639                 word(self.writer(), &res[..])
 640             }
 641             ast::LitKind::Int(i, t) => {
 642                 match t {
 643                     ast::LitIntType::Signed(st) => {
 644                         word(self.writer(), &st.val_to_string(i as i128))
 645                     }
 646                     ast::LitIntType::Unsigned(ut) => {
 647                         word(self.writer(), &ut.val_to_string(i))
 648                     }
 649                     ast::LitIntType::Unsuffixed => {
 650                         word(self.writer(), &format!("{}", i))
 651                     }
 652                 }
 653             }
 654             ast::LitKind::Float(ref f, t) => {
 655                 word(self.writer(),
 656                      &format!(
 657                          "{}{}",
 658                          &f,
 659                          t.ty_to_string()))
 660             }
 661             ast::LitKind::FloatUnsuffixed(ref f) => word(self.writer(), &f.as_str()),
 662             ast::LitKind::Bool(val) => {
 663                 if val { word(self.writer(), "true") } else { word(self.writer(), "false") }
 664             }
 665             ast::LitKind::ByteStr(ref v) => {
 666                 let mut escaped: String = String::new();
 667                 for &ch in v.iter() {
 668                     escaped.extend(ascii::escape_default(ch)
 669                                          .map(|c| c as char));
 670                 }
 671                 word(self.writer(), &format!("b\"{}\"", escaped))
 672             }
 673         }
 674     }
 675
 676     fn print_string(&mut self, st: &str,
 677                     style: ast::StrStyle) -> io::Result<()> {
 678         let st = match style {
 679             ast::StrStyle::Cooked => {
 680                 (format!("\"{}\"", parse::escape_default(st)))
 681             }
 682             ast::StrStyle::Raw(n) => {
 683                 (format!("r{delim}\"{string}\"{delim}",
 684                          delim=repeat("#", n),
 685                          string=st))
 686             }
 687         };
 688         word(self.writer(), &st[..])
 689     }
 690
 691     fn print_inner_attributes(&mut self,
 692                               attrs: &[ast::Attribute]) -> io::Result<()> {
 693         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, true)
 694     }
 695
 696     fn print_inner_attributes_no_trailing_hardbreak(&mut self,
 697                                                    attrs: &[ast::Attribute])
 698                                                    -> io::Result<()> {
 699         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, false)
 700     }
 701
 702     fn print_outer_attributes(&mut self,
 703                               attrs: &[ast::Attribute]) -> io::Result<()> {
 704         self.print_either_attributes(attrs, ast::AttrStyle::Outer, false, true)
 705     }
 706
 707     fn print_inner_attributes_inline(&mut self,
 708                                      attrs: &[ast::Attribute]) -> io::Result<()> {
 709         self.print_either_attributes(attrs, ast::AttrStyle::Inner, true, true)
 710     }
 711
 712     fn print_outer_attributes_inline(&mut self,
 713                                      attrs: &[ast::Attribute]) -> io::Result<()> {
 714         self.print_either_attributes(attrs, ast::AttrStyle::Outer, true, true)
 715     }
 716
 717     fn print_either_attributes(&mut self,
 718                               attrs: &[ast::Attribute],
 719                               kind: ast::AttrStyle,
 720                               is_inline: bool,
 721                               trailing_hardbreak: bool) -> io::Result<()> {
 722         let mut count = 0;
 723         for attr in attrs {
 724             if attr.style == kind {
 725                 self.print_attribute_inline(attr, is_inline)?;
 726                 if is_inline {
 727                     self.nbsp()?;
 728                 }
 729                 count += 1;
 730             }
 731         }
 732         if count > 0 && trailing_hardbreak && !is_inline {
 733             self.hardbreak_if_not_bol()?;
 734         }
 735         Ok(())
 736     }
 737
 738     fn print_attribute(&mut self, attr: &ast::Attribute) -> io::Result<()> {
 739         self.print_attribute_inline(attr, false)
 740     }
 741
 742     fn print_attribute_inline(&mut self, attr: &ast::Attribute,
 743                               is_inline: bool) -> io::Result<()> {
 744         if !is_inline {
 745             self.hardbreak_if_not_bol()?;
 746         }
 747         self.maybe_print_comment(attr.span.lo)?;
 748         if attr.is_sugared_doc {
 749             word(self.writer(), &attr.value_str().unwrap().as_str())?;
 750             hardbreak(self.writer())
 751         } else {
 752             match attr.style {
 753                 ast::AttrStyle::Inner => word(self.writer(), "#![")?,
 754                 ast::AttrStyle::Outer => word(self.writer(), "#[")?,
 755             }
 756             if let Some(mi) = attr.meta() {
 757                 self.print_meta_item(&mi)?
 758             } else {
 759                 for (i, segment) in attr.path.segments.iter().enumerate() {
 760                     if i > 0 {
 761                         word(self.writer(), "::")?
 762                     }
 763                     if segment.identifier.name != keywords::CrateRoot.name() &&
 764                        segment.identifier.name != "$crate" {
 765                         word(self.writer(), &segment.identifier.name.as_str())?;
 766                     }
 767                 }
 768                 space(self.writer())?;
 769                 self.print_tts(attr.tokens.clone())?;
 770             }
 771             word(self.writer(), "]")
 772         }
 773     }
 774
 775     fn print_meta_list_item(&mut self, item: &ast::NestedMetaItem) -> io::Result<()> {
 776         match item.node {
 777             ast::NestedMetaItemKind::MetaItem(ref mi) => {
 778                 self.print_meta_item(mi)
 779             },
 780             ast::NestedMetaItemKind::Literal(ref lit) => {
 781                 self.print_literal(lit)
 782             }
 783         }
 784     }
 785
 786     fn print_meta_item(&mut self, item: &ast::MetaItem) -> io::Result<()> {
 787         self.ibox(INDENT_UNIT)?;
 788         match item.node {
 789             ast::MetaItemKind::Word => {
 790                 word(self.writer(), &item.name.as_str())?;
 791             }
 792             ast::MetaItemKind::NameValue(ref value) => {
 793                 self.word_space(&item.name.as_str())?;
 794                 self.word_space("=")?;
 795                 self.print_literal(value)?;
 796             }
 797             ast::MetaItemKind::List(ref items) => {
 798                 word(self.writer(), &item.name.as_str())?;
 799                 self.popen()?;
 800                 self.commasep(Consistent,
 801                               &items[..],
 802                               |s, i| s.print_meta_list_item(&i))?;
 803                 self.pclose()?;
 804             }
 805         }
 806         self.end()
 807     }
 808
 809     /// This doesn't deserve to be called "pretty" printing, but it should be
 810     /// meaning-preserving. A quick hack that might help would be to look at the
 811     /// spans embedded in the TTs to decide where to put spaces and newlines.
 812     /// But it'd be better to parse these according to the grammar of the
 813     /// appropriate macro, transcribe back into the grammar we just parsed from,
 814     /// and then pretty-print the resulting AST nodes (so, e.g., we print
 815     /// expression arguments as expressions). It can be done! I think.
 816     fn print_tt(&mut self, tt: tokenstream::TokenTree) -> io::Result<()> {
 817         match tt {
 818             TokenTree::Token(_, ref tk) => {
 819                 word(self.writer(), &token_to_string(tk))?;
 820                 match *tk {
 821                     parse::token::DocComment(..) => {
 822                         hardbreak(self.writer())
 823                     }
 824                     _ => Ok(())
 825                 }
 826             }
 827             TokenTree::Delimited(_, ref delimed) => {
 828                 word(self.writer(), &token_to_string(&delimed.open_token()))?;
 829                 space(self.writer())?;
 830                 self.print_tts(delimed.stream())?;
 831                 space(self.writer())?;
 832                 word(self.writer(), &token_to_string(&delimed.close_token()))
 833             },
 834         }
 835     }
 836
 837     fn print_tts(&mut self, tts: tokenstream::TokenStream) -> io::Result<()> {
 838         self.ibox(0)?;
 839         for (i, tt) in tts.into_trees().enumerate() {
 840             if i != 0 {
 841                 space(self.writer())?;
 842             }
 843             self.print_tt(tt)?;
 844         }
 845         self.end()
 846     }
 847
 848     fn space_if_not_bol(&mut self) -> io::Result<()> {
 849         if !self.is_bol() { space(self.writer())?; }
 850         Ok(())
 851     }
 852
 853     fn nbsp(&mut self) -> io::Result<()> { word(self.writer(), " ") }
 854 }
 855
 856 impl<'a> PrintState<'a> for State<'a> {
 857     fn writer(&mut self) -> &mut pp::Printer<'a> {
 858         &mut self.s
 859     }
 860
 861     fn boxes(&mut self) -> &mut Vec<pp::Breaks> {
 862         &mut self.boxes
 863     }
 864
 865     fn comments(&mut self) -> &mut Option<Vec<comments::Comment>> {
 866         &mut self.comments
 867     }
 868
 869     fn cur_cmnt_and_lit(&mut self) -> &mut CurrentCommentAndLiteral {
 870         &mut self.cur_cmnt_and_lit
 871     }
 872
 873     fn literals(&self) -> &Option<Vec<comments::Literal>> {
 874         &self.literals
 875     }
 876 }
 877
 878 impl<'a> State<'a> {
 879     pub fn cbox(&mut self, u: usize) -> io::Result<()> {
 880         self.boxes.push(pp::Breaks::Consistent);
 881         pp::cbox(&mut self.s, u)
 882     }
 883
 884     pub fn word_nbsp(&mut self, w: &str) -> io::Result<()> {
 885         word(&mut self.s, w)?;
 886         self.nbsp()
 887     }
 888
 889     pub fn head(&mut self, w: &str) -> io::Result<()> {
 890         // outer-box is consistent
 891         self.cbox(INDENT_UNIT)?;
 892         // head-box is inconsistent
 893         self.ibox(w.len() + 1)?;
 894         // keyword that starts the head
 895         if !w.is_empty() {
 896             self.word_nbsp(w)?;
 897         }
 898         Ok(())
 899     }
 900
 901     pub fn bopen(&mut self) -> io::Result<()> {
 902         word(&mut self.s, "{")?;
 903         self.end() // close the head-box
 904     }
 905
 906     pub fn bclose_(&mut self, span: syntax_pos::Span,
 907                    indented: usize) -> io::Result<()> {
 908         self.bclose_maybe_open(span, indented, true)
 909     }
 910     pub fn bclose_maybe_open(&mut self, span: syntax_pos::Span,
 911                              indented: usize, close_box: bool) -> io::Result<()> {
 912         self.maybe_print_comment(span.hi)?;
 913         self.break_offset_if_not_bol(1, -(indented as isize))?;
 914         word(&mut self.s, "}")?;
 915         if close_box {
 916             self.end()?; // close the outer-box
 917         }
 918         Ok(())
 919     }
 920     pub fn bclose(&mut self, span: syntax_pos::Span) -> io::Result<()> {
 921         self.bclose_(span, INDENT_UNIT)
 922     }
 923
 924     pub fn in_cbox(&self) -> bool {
 925         match self.boxes.last() {
 926             Some(&last_box) => last_box == pp::Breaks::Consistent,
 927             None => false
 928         }
 929     }
 930
 931     pub fn break_offset_if_not_bol(&mut self, n: usize,
 932                                    off: isize) -> io::Result<()> {
 933         if !self.is_bol() {
 934             break_offset(&mut self.s, n, off)
 935         } else {
 936             if off != 0 && self.s.last_token().is_hardbreak_tok() {
 937                 // We do something pretty sketchy here: tuck the nonzero
 938                 // offset-adjustment we were going to deposit along with the
 939                 // break into the previous hardbreak.
 940                 self.s.replace_last_token(pp::hardbreak_tok_offset(off));
 941             }
 942             Ok(())
 943         }
 944     }
 945
 946     // Synthesizes a comment that was not textually present in the original source
 947     // file.
 948     pub fn synth_comment(&mut self, text: String) -> io::Result<()> {
 949         word(&mut self.s, "/*")?;
 950         space(&mut self.s)?;
 951         word(&mut self.s, &text[..])?;
 952         space(&mut self.s)?;
 953         word(&mut self.s, "*/")
 954     }
 955
 956
 957
 958     pub fn commasep_cmnt<T, F, G>(&mut self,
 959                                   b: Breaks,
 960                                   elts: &[T],
 961                                   mut op: F,
 962                                   mut get_span: G) -> io::Result<()> where
 963         F: FnMut(&mut State, &T) -> io::Result<()>,
 964         G: FnMut(&T) -> syntax_pos::Span,
 965     {
 966         self.rbox(0, b)?;
 967         let len = elts.len();
 968         let mut i = 0;
 969         for elt in elts {
 970             self.maybe_print_comment(get_span(elt).hi)?;
 971             op(self, elt)?;
 972             i += 1;
 973             if i < len {
 974                 word(&mut self.s, ",")?;
 975                 self.maybe_print_trailing_comment(get_span(elt),
 976                                                   Some(get_span(&elts[i]).hi))?;
 977                 self.space_if_not_bol()?;
 978             }
 979         }
 980         self.end()
 981     }
 982
 983     pub fn commasep_exprs(&mut self, b: Breaks,
 984                           exprs: &[P<ast::Expr>]) -> io::Result<()> {
 985         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(&e), |e| e.span)
 986     }
 987
 988     pub fn print_mod(&mut self, _mod: &ast::Mod,
 989                      attrs: &[ast::Attribute]) -> io::Result<()> {
 990         self.print_inner_attributes(attrs)?;
 991         for item in &_mod.items {
 992             self.print_item(&item)?;
 993         }
 994         Ok(())
 995     }
 996
 997     pub fn print_foreign_mod(&mut self, nmod: &ast::ForeignMod,
 998                              attrs: &[ast::Attribute]) -> io::Result<()> {
 999         self.print_inner_attributes(attrs)?;
1000         for item in &nmod.items {
1001             self.print_foreign_item(item)?;
1002         }
1003         Ok(())
1004     }
1005
1006     pub fn print_opt_lifetime(&mut self,
1007                               lifetime: &Option<ast::Lifetime>) -> io::Result<()> {
1008         if let Some(l) = *lifetime {
1009             self.print_lifetime(&l)?;
1010             self.nbsp()?;
1011         }
1012         Ok(())
1013     }
1014
1015     pub fn print_type(&mut self, ty: &ast::Ty) -> io::Result<()> {
1016         self.maybe_print_comment(ty.span.lo)?;
1017         self.ibox(0)?;
1018         match ty.node {
1019             ast::TyKind::Slice(ref ty) => {
1020                 word(&mut self.s, "[")?;
1021                 self.print_type(&ty)?;
1022                 word(&mut self.s, "]")?;
1023             }
1024             ast::TyKind::Ptr(ref mt) => {
1025                 word(&mut self.s, "*")?;
1026                 match mt.mutbl {
1027                     ast::Mutability::Mutable => self.word_nbsp("mut")?,
1028                     ast::Mutability::Immutable => self.word_nbsp("const")?,
1029                 }
1030                 self.print_type(&mt.ty)?;
1031             }
1032             ast::TyKind::Rptr(ref lifetime, ref mt) => {
1033                 word(&mut self.s, "&")?;
1034                 self.print_opt_lifetime(lifetime)?;
1035                 self.print_mt(mt)?;
1036             }
1037             ast::TyKind::Never => {
1038                 word(&mut self.s, "!")?;
1039             },
1040             ast::TyKind::Tup(ref elts) => {
1041                 self.popen()?;
1042                 self.commasep(Inconsistent, &elts[..],
1043                               |s, ty| s.print_type(&ty))?;
1044                 if elts.len() == 1 {
1045                     word(&mut self.s, ",")?;
1046                 }
1047                 self.pclose()?;
1048             }
1049             ast::TyKind::Paren(ref typ) => {
1050                 self.popen()?;
1051                 self.print_type(&typ)?;
1052                 self.pclose()?;
1053             }
1054             ast::TyKind::BareFn(ref f) => {
1055                 let generics = ast::Generics {
1056                     lifetimes: f.lifetimes.clone(),
1057                     ty_params: Vec::new(),
1058                     where_clause: ast::WhereClause {
1059                         id: ast::DUMMY_NODE_ID,
1060                         predicates: Vec::new(),
1061                     },
1062                     span: syntax_pos::DUMMY_SP,
1063                 };
1064                 self.print_ty_fn(f.abi,
1065                                  f.unsafety,
1066                                  &f.decl,
1067                                  None,
1068                                  &generics)?;
1069             }
1070             ast::TyKind::Path(None, ref path) => {
1071                 self.print_path(path, false, 0, false)?;
1072             }
1073             ast::TyKind::Path(Some(ref qself), ref path) => {
1074                 self.print_qpath(path, qself, false)?
1075             }
1076             ast::TyKind::TraitObject(ref bounds) => {
1077                 self.print_bounds("", &bounds[..])?;
1078             }
1079             ast::TyKind::ImplTrait(ref bounds) => {
1080                 self.print_bounds("impl ", &bounds[..])?;
1081             }
1082             ast::TyKind::Array(ref ty, ref v) => {
1083                 word(&mut self.s, "[")?;
1084                 self.print_type(&ty)?;
1085                 word(&mut self.s, "; ")?;
1086                 self.print_expr(&v)?;
1087                 word(&mut self.s, "]")?;
1088             }
1089             ast::TyKind::Typeof(ref e) => {
1090                 word(&mut self.s, "typeof(")?;
1091                 self.print_expr(&e)?;
1092                 word(&mut self.s, ")")?;
1093             }
1094             ast::TyKind::Infer => {
1095                 word(&mut self.s, "_")?;
1096             }
1097             ast::TyKind::Err => {
1098                 word(&mut self.s, "?")?;
1099             }
1100             ast::TyKind::ImplicitSelf => {
1101                 word(&mut self.s, "Self")?;
1102             }
1103             ast::TyKind::Mac(ref m) => {
1104                 self.print_mac(m, token::Paren)?;
1105             }
1106         }
1107         self.end()
1108     }
1109
1110     pub fn print_foreign_item(&mut self,
1111                               item: &ast::ForeignItem) -> io::Result<()> {
1112         self.hardbreak_if_not_bol()?;
1113         self.maybe_print_comment(item.span.lo)?;
1114         self.print_outer_attributes(&item.attrs)?;
1115         match item.node {
1116             ast::ForeignItemKind::Fn(ref decl, ref generics) => {
1117                 self.head("")?;
1118                 self.print_fn(decl, ast::Unsafety::Normal,
1119                               ast::Constness::NotConst,
1120                               Abi::Rust, Some(item.ident),
1121                               generics, &item.vis)?;
1122                 self.end()?; // end head-ibox
1123                 word(&mut self.s, ";")?;
1124                 self.end() // end the outer fn box
1125             }
1126             ast::ForeignItemKind::Static(ref t, m) => {
1127                 self.head(&visibility_qualified(&item.vis, "static"))?;
1128                 if m {
1129                     self.word_space("mut")?;
1130                 }
1131                 self.print_ident(item.ident)?;
1132                 self.word_space(":")?;
1133                 self.print_type(&t)?;
1134                 word(&mut self.s, ";")?;
1135                 self.end()?; // end the head-ibox
1136                 self.end() // end the outer cbox
1137             }
1138         }
1139     }
1140
1141     fn print_associated_const(&mut self,
1142                               ident: ast::Ident,
1143                               ty: &ast::Ty,
1144                               default: Option<&ast::Expr>,
1145                               vis: &ast::Visibility)
1146                               -> io::Result<()>
1147     {
1148         word(&mut self.s, &visibility_qualified(vis, ""))?;
1149         self.word_space("const")?;
1150         self.print_ident(ident)?;
1151         self.word_space(":")?;
1152         self.print_type(ty)?;
1153         if let Some(expr) = default {
1154             space(&mut self.s)?;
1155             self.word_space("=")?;
1156             self.print_expr(expr)?;
1157         }
1158         word(&mut self.s, ";")
1159     }
1160
1161     fn print_associated_type(&mut self,
1162                              ident: ast::Ident,
1163                              bounds: Option<&ast::TyParamBounds>,
1164                              ty: Option<&ast::Ty>)
1165                              -> io::Result<()> {
1166         self.word_space("type")?;
1167         self.print_ident(ident)?;
1168         if let Some(bounds) = bounds {
1169             self.print_bounds(":", bounds)?;
1170         }
1171         if let Some(ty) = ty {
1172             space(&mut self.s)?;
1173             self.word_space("=")?;
1174             self.print_type(ty)?;
1175         }
1176         word(&mut self.s, ";")
1177     }
1178
1179     /// Pretty-print an item
1180     pub fn print_item(&mut self, item: &ast::Item) -> io::Result<()> {
1181         self.hardbreak_if_not_bol()?;
1182         self.maybe_print_comment(item.span.lo)?;
1183         self.print_outer_attributes(&item.attrs)?;
1184         self.ann.pre(self, NodeItem(item))?;
1185         match item.node {
1186             ast::ItemKind::ExternCrate(ref optional_path) => {
1187                 self.head(&visibility_qualified(&item.vis, "extern crate"))?;
1188                 if let Some(p) = *optional_path {
1189                     let val = p.as_str();
1190                     if val.contains("-") {
1191                         self.print_string(&val, ast::StrStyle::Cooked)?;
1192                     } else {
1193                         self.print_name(p)?;
1194                     }
1195                     space(&mut self.s)?;
1196                     word(&mut self.s, "as")?;
1197                     space(&mut self.s)?;
1198                 }
1199                 self.print_ident(item.ident)?;
1200                 word(&mut self.s, ";")?;
1201                 self.end()?; // end inner head-block
1202                 self.end()?; // end outer head-block
1203             }
1204             ast::ItemKind::Use(ref vp) => {
1205                 self.head(&visibility_qualified(&item.vis, "use"))?;
1206                 self.print_view_path(&vp)?;
1207                 word(&mut self.s, ";")?;
1208                 self.end()?; // end inner head-block
1209                 self.end()?; // end outer head-block
1210             }
1211             ast::ItemKind::Static(ref ty, m, ref expr) => {
1212                 self.head(&visibility_qualified(&item.vis, "static"))?;
1213                 if m == ast::Mutability::Mutable {
1214                     self.word_space("mut")?;
1215                 }
1216                 self.print_ident(item.ident)?;
1217                 self.word_space(":")?;
1218                 self.print_type(&ty)?;
1219                 space(&mut self.s)?;
1220                 self.end()?; // end the head-ibox
1221
1222                 self.word_space("=")?;
1223                 self.print_expr(&expr)?;
1224                 word(&mut self.s, ";")?;
1225                 self.end()?; // end the outer cbox
1226             }
1227             ast::ItemKind::Const(ref ty, ref expr) => {
1228                 self.head(&visibility_qualified(&item.vis, "const"))?;
1229                 self.print_ident(item.ident)?;
1230                 self.word_space(":")?;
1231                 self.print_type(&ty)?;
1232                 space(&mut self.s)?;
1233                 self.end()?; // end the head-ibox
1234
1235                 self.word_space("=")?;
1236                 self.print_expr(&expr)?;
1237                 word(&mut self.s, ";")?;
1238                 self.end()?; // end the outer cbox
1239             }
1240             ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref typarams, ref body) => {
1241                 self.head("")?;
1242                 self.print_fn(
1243                     decl,
1244                     unsafety,
1245                     constness.node,
1246                     abi,
1247                     Some(item.ident),
1248                     typarams,
1249                     &item.vis
1250                 )?;
1251                 word(&mut self.s, " ")?;
1252                 self.print_block_with_attrs(&body, &item.attrs)?;
1253             }
1254             ast::ItemKind::Mod(ref _mod) => {
1255                 self.head(&visibility_qualified(&item.vis, "mod"))?;
1256                 self.print_ident(item.ident)?;
1257                 self.nbsp()?;
1258                 self.bopen()?;
1259                 self.print_mod(_mod, &item.attrs)?;
1260                 self.bclose(item.span)?;
1261             }
1262             ast::ItemKind::ForeignMod(ref nmod) => {
1263                 self.head("extern")?;
1264                 self.word_nbsp(&nmod.abi.to_string())?;
1265                 self.bopen()?;
1266                 self.print_foreign_mod(nmod, &item.attrs)?;
1267                 self.bclose(item.span)?;
1268             }
1269             ast::ItemKind::GlobalAsm(ref ga) => {
1270                 self.head(&visibility_qualified(&item.vis, "global_asm!"))?;
1271                 word(&mut self.s, &ga.asm.as_str())?;
1272                 self.end()?;
1273             }
1274             ast::ItemKind::Ty(ref ty, ref params) => {
1275                 self.ibox(INDENT_UNIT)?;
1276                 self.ibox(0)?;
1277                 self.word_nbsp(&visibility_qualified(&item.vis, "type"))?;
1278                 self.print_ident(item.ident)?;
1279                 self.print_generics(params)?;
1280                 self.end()?; // end the inner ibox
1281
1282                 self.print_where_clause(&params.where_clause)?;
1283                 space(&mut self.s)?;
1284                 self.word_space("=")?;
1285                 self.print_type(&ty)?;
1286                 word(&mut self.s, ";")?;
1287                 self.end()?; // end the outer ibox
1288             }
1289             ast::ItemKind::Enum(ref enum_definition, ref params) => {
1290                 self.print_enum_def(
1291                     enum_definition,
1292                     params,
1293                     item.ident,
1294                     item.span,
1295                     &item.vis
1296                 )?;
1297             }
1298             ast::ItemKind::Struct(ref struct_def, ref generics) => {
1299                 self.head(&visibility_qualified(&item.vis, "struct"))?;
1300                 self.print_struct(&struct_def, generics, item.ident, item.span, true)?;
1301             }
1302             ast::ItemKind::Union(ref struct_def, ref generics) => {
1303                 self.head(&visibility_qualified(&item.vis, "union"))?;
1304                 self.print_struct(&struct_def, generics, item.ident, item.span, true)?;
1305             }
1306             ast::ItemKind::DefaultImpl(unsafety, ref trait_ref) => {
1307                 self.head("")?;
1308                 self.print_visibility(&item.vis)?;
1309                 self.print_unsafety(unsafety)?;
1310                 self.word_nbsp("impl")?;
1311                 self.print_trait_ref(trait_ref)?;
1312                 space(&mut self.s)?;
1313                 self.word_space("for")?;
1314                 self.word_space("..")?;
1315                 self.bopen()?;
1316                 self.bclose(item.span)?;
1317             }
1318             ast::ItemKind::Impl(unsafety,
1319                           polarity,
1320                           defaultness,
1321                           ref generics,
1322                           ref opt_trait,
1323                           ref ty,
1324                           ref impl_items) => {
1325                 self.head("")?;
1326                 self.print_visibility(&item.vis)?;
1327                 self.print_defaultness(defaultness)?;
1328                 self.print_unsafety(unsafety)?;
1329                 self.word_nbsp("impl")?;
1330
1331                 if generics.is_parameterized() {
1332                     self.print_generics(generics)?;
1333                     space(&mut self.s)?;
1334                 }
1335
1336                 match polarity {
1337                     ast::ImplPolarity::Negative => {
1338                         word(&mut self.s, "!")?;
1339                     },
1340                     _ => {}
1341                 }
1342
1343                 if let Some(ref t) = *opt_trait {
1344                     self.print_trait_ref(t)?;
1345                     space(&mut self.s)?;
1346                     self.word_space("for")?;
1347                 }
1348
1349                 self.print_type(&ty)?;
1350                 self.print_where_clause(&generics.where_clause)?;
1351
1352                 space(&mut self.s)?;
1353                 self.bopen()?;
1354                 self.print_inner_attributes(&item.attrs)?;
1355                 for impl_item in impl_items {
1356                     self.print_impl_item(impl_item)?;
1357                 }
1358                 self.bclose(item.span)?;
1359             }
1360             ast::ItemKind::Trait(unsafety, ref generics, ref bounds, ref trait_items) => {
1361                 self.head("")?;
1362                 self.print_visibility(&item.vis)?;
1363                 self.print_unsafety(unsafety)?;
1364                 self.word_nbsp("trait")?;
1365                 self.print_ident(item.ident)?;
1366                 self.print_generics(generics)?;
1367                 let mut real_bounds = Vec::with_capacity(bounds.len());
1368                 for b in bounds.iter() {
1369                     if let TraitTyParamBound(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
1370                         space(&mut self.s)?;
1371                         self.word_space("for ?")?;
1372                         self.print_trait_ref(&ptr.trait_ref)?;
1373                     } else {
1374                         real_bounds.push(b.clone());
1375                     }
1376                 }
1377                 self.print_bounds(":", &real_bounds[..])?;
1378                 self.print_where_clause(&generics.where_clause)?;
1379                 word(&mut self.s, " ")?;
1380                 self.bopen()?;
1381                 for trait_item in trait_items {
1382                     self.print_trait_item(trait_item)?;
1383                 }
1384                 self.bclose(item.span)?;
1385             }
1386             ast::ItemKind::Mac(codemap::Spanned { ref node, .. }) => {
1387                 self.print_path(&node.path, false, 0, false)?;
1388                 word(&mut self.s, "! ")?;
1389                 self.print_ident(item.ident)?;
1390                 self.cbox(INDENT_UNIT)?;
1391                 self.popen()?;
1392                 self.print_tts(node.stream())?;
1393                 self.pclose()?;
1394                 word(&mut self.s, ";")?;
1395                 self.end()?;
1396             }
1397             ast::ItemKind::MacroDef(ref tts) => {
1398                 word(&mut self.s, "macro_rules! ")?;
1399                 self.print_ident(item.ident)?;
1400                 self.cbox(INDENT_UNIT)?;
1401                 self.popen()?;
1402                 self.print_tts(tts.clone().into())?;
1403                 self.pclose()?;
1404                 word(&mut self.s, ";")?;
1405                 self.end()?;
1406             }
1407         }
1408         self.ann.post(self, NodeItem(item))
1409     }
1410
1411     fn print_trait_ref(&mut self, t: &ast::TraitRef) -> io::Result<()> {
1412         self.print_path(&t.path, false, 0, false)
1413     }
1414
1415     fn print_formal_lifetime_list(&mut self, lifetimes: &[ast::LifetimeDef]) -> io::Result<()> {
1416         if !lifetimes.is_empty() {
1417             word(&mut self.s, "for<")?;
1418             let mut comma = false;
1419             for lifetime_def in lifetimes {
1420                 if comma {
1421                     self.word_space(",")?
1422                 }
1423                 self.print_outer_attributes_inline(&lifetime_def.attrs)?;
1424                 self.print_lifetime_bounds(&lifetime_def.lifetime, &lifetime_def.bounds)?;
1425                 comma = true;
1426             }
1427             word(&mut self.s, ">")?;
1428         }
1429         Ok(())
1430     }
1431
1432     fn print_poly_trait_ref(&mut self, t: &ast::PolyTraitRef) -> io::Result<()> {
1433         self.print_formal_lifetime_list(&t.bound_lifetimes)?;
1434         self.print_trait_ref(&t.trait_ref)
1435     }
1436
1437     pub fn print_enum_def(&mut self, enum_definition: &ast::EnumDef,
1438                           generics: &ast::Generics, ident: ast::Ident,
1439                           span: syntax_pos::Span,
1440                           visibility: &ast::Visibility) -> io::Result<()> {
1441         self.head(&visibility_qualified(visibility, "enum"))?;
1442         self.print_ident(ident)?;
1443         self.print_generics(generics)?;
1444         self.print_where_clause(&generics.where_clause)?;
1445         space(&mut self.s)?;
1446         self.print_variants(&enum_definition.variants, span)
1447     }
1448
1449     pub fn print_variants(&mut self,
1450                           variants: &[ast::Variant],
1451                           span: syntax_pos::Span) -> io::Result<()> {
1452         self.bopen()?;
1453         for v in variants {
1454             self.space_if_not_bol()?;
1455             self.maybe_print_comment(v.span.lo)?;
1456             self.print_outer_attributes(&v.node.attrs)?;
1457             self.ibox(INDENT_UNIT)?;
1458             self.print_variant(v)?;
1459             word(&mut self.s, ",")?;
1460             self.end()?;
1461             self.maybe_print_trailing_comment(v.span, None)?;
1462         }
1463         self.bclose(span)
1464     }
1465
1466     pub fn print_visibility(&mut self, vis: &ast::Visibility) -> io::Result<()> {
1467         match *vis {
1468             ast::Visibility::Public => self.word_nbsp("pub"),
1469             ast::Visibility::Crate(_) => self.word_nbsp("pub(crate)"),
1470             ast::Visibility::Restricted { ref path, .. } => {
1471                 let path = to_string(|s| s.print_path(path, false, 0, true));
1472                 if path == "self" || path == "super" {
1473                     self.word_nbsp(&format!("pub({})", path))
1474                 } else {
1475                     self.word_nbsp(&format!("pub(in {})", path))
1476                 }
1477             }
1478             ast::Visibility::Inherited => Ok(())
1479         }
1480     }
1481
1482     pub fn print_defaultness(&mut self, defatulness: ast::Defaultness) -> io::Result<()> {
1483         if let ast::Defaultness::Default = defatulness {
1484             try!(self.word_nbsp("default"));
1485         }
1486         Ok(())
1487     }
1488
1489     pub fn print_struct(&mut self,
1490                         struct_def: &ast::VariantData,
1491                         generics: &ast::Generics,
1492                         ident: ast::Ident,
1493                         span: syntax_pos::Span,
1494                         print_finalizer: bool) -> io::Result<()> {
1495         self.print_ident(ident)?;
1496         self.print_generics(generics)?;
1497         if !struct_def.is_struct() {
1498             if struct_def.is_tuple() {
1499                 self.popen()?;
1500                 self.commasep(
1501                     Inconsistent, struct_def.fields(),
1502                     |s, field| {
1503                         s.maybe_print_comment(field.span.lo)?;
1504                         s.print_outer_attributes(&field.attrs)?;
1505                         s.print_visibility(&field.vis)?;
1506                         s.print_type(&field.ty)
1507                     }
1508                 )?;
1509                 self.pclose()?;
1510             }
1511             self.print_where_clause(&generics.where_clause)?;
1512             if print_finalizer {
1513                 word(&mut self.s, ";")?;
1514             }
1515             self.end()?;
1516             self.end() // close the outer-box
1517         } else {
1518             self.print_where_clause(&generics.where_clause)?;
1519             self.nbsp()?;
1520             self.bopen()?;
1521             self.hardbreak_if_not_bol()?;
1522
1523             for field in struct_def.fields() {
1524                 self.hardbreak_if_not_bol()?;
1525                 self.maybe_print_comment(field.span.lo)?;
1526                 self.print_outer_attributes(&field.attrs)?;
1527                 self.print_visibility(&field.vis)?;
1528                 self.print_ident(field.ident.unwrap())?;
1529                 self.word_nbsp(":")?;
1530                 self.print_type(&field.ty)?;
1531                 word(&mut self.s, ",")?;
1532             }
1533
1534             self.bclose(span)
1535         }
1536     }
1537
1538     pub fn print_variant(&mut self, v: &ast::Variant) -> io::Result<()> {
1539         self.head("")?;
1540         let generics = ast::Generics::default();
1541         self.print_struct(&v.node.data, &generics, v.node.name, v.span, false)?;
1542         match v.node.disr_expr {
1543             Some(ref d) => {
1544                 space(&mut self.s)?;
1545                 self.word_space("=")?;
1546                 self.print_expr(&d)
1547             }
1548             _ => Ok(())
1549         }
1550     }
1551
1552     pub fn print_method_sig(&mut self,
1553                             ident: ast::Ident,
1554                             m: &ast::MethodSig,
1555                             vis: &ast::Visibility)
1556                             -> io::Result<()> {
1557         self.print_fn(&m.decl,
1558                       m.unsafety,
1559                       m.constness.node,
1560                       m.abi,
1561                       Some(ident),
1562                       &m.generics,
1563                       vis)
1564     }
1565
1566     pub fn print_trait_item(&mut self, ti: &ast::TraitItem)
1567                             -> io::Result<()> {
1568         self.ann.pre(self, NodeSubItem(ti.id))?;
1569         self.hardbreak_if_not_bol()?;
1570         self.maybe_print_comment(ti.span.lo)?;
1571         self.print_outer_attributes(&ti.attrs)?;
1572         match ti.node {
1573             ast::TraitItemKind::Const(ref ty, ref default) => {
1574                 self.print_associated_const(ti.ident, &ty,
1575                                             default.as_ref().map(|expr| &**expr),
1576                                             &ast::Visibility::Inherited)?;
1577             }
1578             ast::TraitItemKind::Method(ref sig, ref body) => {
1579                 if body.is_some() {
1580                     self.head("")?;
1581                 }
1582                 self.print_method_sig(ti.ident, sig, &ast::Visibility::Inherited)?;
1583                 if let Some(ref body) = *body {
1584                     self.nbsp()?;
1585                     self.print_block_with_attrs(body, &ti.attrs)?;
1586                 } else {
1587                     word(&mut self.s, ";")?;
1588                 }
1589             }
1590             ast::TraitItemKind::Type(ref bounds, ref default) => {
1591                 self.print_associated_type(ti.ident, Some(bounds),
1592                                            default.as_ref().map(|ty| &**ty))?;
1593             }
1594             ast::TraitItemKind::Macro(codemap::Spanned { ref node, .. }) => {
1595                 // code copied from ItemKind::Mac:
1596                 self.print_path(&node.path, false, 0, false)?;
1597                 word(&mut self.s, "! ")?;
1598                 self.cbox(INDENT_UNIT)?;
1599                 self.popen()?;
1600                 self.print_tts(node.stream())?;
1601                 self.pclose()?;
1602                 word(&mut self.s, ";")?;
1603                 self.end()?
1604             }
1605         }
1606         self.ann.post(self, NodeSubItem(ti.id))
1607     }
1608
1609     pub fn print_impl_item(&mut self, ii: &ast::ImplItem) -> io::Result<()> {
1610         self.ann.pre(self, NodeSubItem(ii.id))?;
1611         self.hardbreak_if_not_bol()?;
1612         self.maybe_print_comment(ii.span.lo)?;
1613         self.print_outer_attributes(&ii.attrs)?;
1614         self.print_defaultness(ii.defaultness)?;
1615         match ii.node {
1616             ast::ImplItemKind::Const(ref ty, ref expr) => {
1617                 self.print_associated_const(ii.ident, &ty, Some(&expr), &ii.vis)?;
1618             }
1619             ast::ImplItemKind::Method(ref sig, ref body) => {
1620                 self.head("")?;
1621                 self.print_method_sig(ii.ident, sig, &ii.vis)?;
1622                 self.nbsp()?;
1623                 self.print_block_with_attrs(body, &ii.attrs)?;
1624             }
1625             ast::ImplItemKind::Type(ref ty) => {
1626                 self.print_associated_type(ii.ident, None, Some(ty))?;
1627             }
1628             ast::ImplItemKind::Macro(codemap::Spanned { ref node, .. }) => {
1629                 // code copied from ItemKind::Mac:
1630                 self.print_path(&node.path, false, 0, false)?;
1631                 word(&mut self.s, "! ")?;
1632                 self.cbox(INDENT_UNIT)?;
1633                 self.popen()?;
1634                 self.print_tts(node.stream())?;
1635                 self.pclose()?;
1636                 word(&mut self.s, ";")?;
1637                 self.end()?
1638             }
1639         }
1640         self.ann.post(self, NodeSubItem(ii.id))
1641     }
1642
1643     pub fn print_stmt(&mut self, st: &ast::Stmt) -> io::Result<()> {
1644         self.maybe_print_comment(st.span.lo)?;
1645         match st.node {
1646             ast::StmtKind::Local(ref loc) => {
1647                 self.print_outer_attributes(&loc.attrs)?;
1648                 self.space_if_not_bol()?;
1649                 self.ibox(INDENT_UNIT)?;
1650                 self.word_nbsp("let")?;
1651
1652                 self.ibox(INDENT_UNIT)?;
1653                 self.print_local_decl(&loc)?;
1654                 self.end()?;
1655                 if let Some(ref init) = loc.init {
1656                     self.nbsp()?;
1657                     self.word_space("=")?;
1658                     self.print_expr(&init)?;
1659                 }
1660                 word(&mut self.s, ";")?;
1661                 self.end()?;
1662             }
1663             ast::StmtKind::Item(ref item) => self.print_item(&item)?,
1664             ast::StmtKind::Expr(ref expr) => {
1665                 self.space_if_not_bol()?;
1666                 self.print_expr_outer_attr_style(&expr, false)?;
1667                 if parse::classify::expr_requires_semi_to_be_stmt(expr) {
1668                     word(&mut self.s, ";")?;
1669                 }
1670             }
1671             ast::StmtKind::Semi(ref expr) => {
1672                 self.space_if_not_bol()?;
1673                 self.print_expr_outer_attr_style(&expr, false)?;
1674                 word(&mut self.s, ";")?;
1675             }
1676             ast::StmtKind::Mac(ref mac) => {
1677                 let (ref mac, style, ref attrs) = **mac;
1678                 self.space_if_not_bol()?;
1679                 self.print_outer_attributes(&attrs)?;
1680                 let delim = match style {
1681                     ast::MacStmtStyle::Braces => token::Brace,
1682                     _ => token::Paren
1683                 };
1684                 self.print_mac(&mac, delim)?;
1685                 if style == ast::MacStmtStyle::Semicolon {
1686                     word(&mut self.s, ";")?;
1687                 }
1688             }
1689         }
1690         self.maybe_print_trailing_comment(st.span, None)
1691     }
1692
1693     pub fn print_block(&mut self, blk: &ast::Block) -> io::Result<()> {
1694         self.print_block_with_attrs(blk, &[])
1695     }
1696
1697     pub fn print_block_unclosed(&mut self, blk: &ast::Block) -> io::Result<()> {
1698         self.print_block_unclosed_indent(blk, INDENT_UNIT)
1699     }
1700
1701     pub fn print_block_unclosed_with_attrs(&mut self, blk: &ast::Block,
1702                                             attrs: &[ast::Attribute])
1703                                            -> io::Result<()> {
1704         self.print_block_maybe_unclosed(blk, INDENT_UNIT, attrs, false)
1705     }
1706
1707     pub fn print_block_unclosed_indent(&mut self, blk: &ast::Block,
1708                                        indented: usize) -> io::Result<()> {
1709         self.print_block_maybe_unclosed(blk, indented, &[], false)
1710     }
1711
1712     pub fn print_block_with_attrs(&mut self,
1713                                   blk: &ast::Block,
1714                                   attrs: &[ast::Attribute]) -> io::Result<()> {
1715         self.print_block_maybe_unclosed(blk, INDENT_UNIT, attrs, true)
1716     }
1717
1718     pub fn print_block_maybe_unclosed(&mut self,
1719                                       blk: &ast::Block,
1720                                       indented: usize,
1721                                       attrs: &[ast::Attribute],
1722                                       close_box: bool) -> io::Result<()> {
1723         match blk.rules {
1724             BlockCheckMode::Unsafe(..) => self.word_space("unsafe")?,
1725             BlockCheckMode::Default => ()
1726         }
1727         self.maybe_print_comment(blk.span.lo)?;
1728         self.ann.pre(self, NodeBlock(blk))?;
1729         self.bopen()?;
1730
1731         self.print_inner_attributes(attrs)?;
1732
1733         for (i, st) in blk.stmts.iter().enumerate() {
1734             match st.node {
1735                 ast::StmtKind::Expr(ref expr) if i == blk.stmts.len() - 1 => {
1736                     self.maybe_print_comment(st.span.lo)?;
1737                     self.space_if_not_bol()?;
1738                     self.print_expr_outer_attr_style(&expr, false)?;
1739                     self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi))?;
1740                 }
1741                 _ => self.print_stmt(st)?,
1742             }
1743         }
1744
1745         self.bclose_maybe_open(blk.span, indented, close_box)?;
1746         self.ann.post(self, NodeBlock(blk))
1747     }
1748
1749     fn print_else(&mut self, els: Option<&ast::Expr>) -> io::Result<()> {
1750         match els {
1751             Some(_else) => {
1752                 match _else.node {
1753                     // "another else-if"
1754                     ast::ExprKind::If(ref i, ref then, ref e) => {
1755                         self.cbox(INDENT_UNIT - 1)?;
1756                         self.ibox(0)?;
1757                         word(&mut self.s, " else if ")?;
1758                         self.print_expr(&i)?;
1759                         space(&mut self.s)?;
1760                         self.print_block(&then)?;
1761                         self.print_else(e.as_ref().map(|e| &**e))
1762                     }
1763                     // "another else-if-let"
1764                     ast::ExprKind::IfLet(ref pat, ref expr, ref then, ref e) => {
1765                         self.cbox(INDENT_UNIT - 1)?;
1766                         self.ibox(0)?;
1767                         word(&mut self.s, " else if let ")?;
1768                         self.print_pat(&pat)?;
1769                         space(&mut self.s)?;
1770                         self.word_space("=")?;
1771                         self.print_expr(&expr)?;
1772                         space(&mut self.s)?;
1773                         self.print_block(&then)?;
1774                         self.print_else(e.as_ref().map(|e| &**e))
1775                     }
1776                     // "final else"
1777                     ast::ExprKind::Block(ref b) => {
1778                         self.cbox(INDENT_UNIT - 1)?;
1779                         self.ibox(0)?;
1780                         word(&mut self.s, " else ")?;
1781                         self.print_block(&b)
1782                     }
1783                     // BLEAH, constraints would be great here
1784                     _ => {
1785                         panic!("print_if saw if with weird alternative");
1786                     }
1787                 }
1788             }
1789             _ => Ok(())
1790         }
1791     }
1792
1793     pub fn print_if(&mut self, test: &ast::Expr, blk: &ast::Block,
1794                     elseopt: Option<&ast::Expr>) -> io::Result<()> {
1795         self.head("if")?;
1796         self.print_expr(test)?;
1797         space(&mut self.s)?;
1798         self.print_block(blk)?;
1799         self.print_else(elseopt)
1800     }
1801
1802     pub fn print_if_let(&mut self, pat: &ast::Pat, expr: &ast::Expr, blk: &ast::Block,
1803                         elseopt: Option<&ast::Expr>) -> io::Result<()> {
1804         self.head("if let")?;
1805         self.print_pat(pat)?;
1806         space(&mut self.s)?;
1807         self.word_space("=")?;
1808         self.print_expr(expr)?;
1809         space(&mut self.s)?;
1810         self.print_block(blk)?;
1811         self.print_else(elseopt)
1812     }
1813
1814     pub fn print_mac(&mut self, m: &ast::Mac, delim: token::DelimToken)
1815                      -> io::Result<()> {
1816         self.print_path(&m.node.path, false, 0, false)?;
1817         word(&mut self.s, "!")?;
1818         match delim {
1819             token::Paren => self.popen()?,
1820             token::Bracket => word(&mut self.s, "[")?,
1821             token::Brace => {
1822                 self.head("")?;
1823                 self.bopen()?;
1824             }
1825             token::NoDelim => {}
1826         }
1827         self.print_tts(m.node.stream())?;
1828         match delim {
1829             token::Paren => self.pclose(),
1830             token::Bracket => word(&mut self.s, "]"),
1831             token::Brace => self.bclose(m.span),
1832             token::NoDelim => Ok(()),
1833         }
1834     }
1835
1836
1837     fn print_call_post(&mut self, args: &[P<ast::Expr>]) -> io::Result<()> {
1838         self.popen()?;
1839         self.commasep_exprs(Inconsistent, args)?;
1840         self.pclose()
1841     }
1842
1843     pub fn check_expr_bin_needs_paren(&mut self, sub_expr: &ast::Expr,
1844                                       binop: ast::BinOp) -> bool {
1845         match sub_expr.node {
1846             ast::ExprKind::Binary(ref sub_op, _, _) => {
1847                 if AssocOp::from_ast_binop(sub_op.node).precedence() <
1848                     AssocOp::from_ast_binop(binop.node).precedence() {
1849                     true
1850                 } else {
1851                     false
1852                 }
1853             }
1854             _ => true
1855         }
1856     }
1857
1858     pub fn print_expr_maybe_paren(&mut self, expr: &ast::Expr) -> io::Result<()> {
1859         let needs_par = needs_parentheses(expr);
1860         if needs_par {
1861             self.popen()?;
1862         }
1863         self.print_expr(expr)?;
1864         if needs_par {
1865             self.pclose()?;
1866         }
1867         Ok(())
1868     }
1869
1870     fn print_expr_in_place(&mut self,
1871                            place: &ast::Expr,
1872                            expr: &ast::Expr) -> io::Result<()> {
1873         self.print_expr_maybe_paren(place)?;
1874         space(&mut self.s)?;
1875         self.word_space("<-")?;
1876         self.print_expr_maybe_paren(expr)
1877     }
1878
1879     fn print_expr_vec(&mut self, exprs: &[P<ast::Expr>],
1880                       attrs: &[Attribute]) -> io::Result<()> {
1881         self.ibox(INDENT_UNIT)?;
1882         word(&mut self.s, "[")?;
1883         self.print_inner_attributes_inline(attrs)?;
1884         self.commasep_exprs(Inconsistent, &exprs[..])?;
1885         word(&mut self.s, "]")?;
1886         self.end()
1887     }
1888
1889     fn print_expr_repeat(&mut self,
1890                          element: &ast::Expr,
1891                          count: &ast::Expr,
1892                          attrs: &[Attribute]) -> io::Result<()> {
1893         self.ibox(INDENT_UNIT)?;
1894         word(&mut self.s, "[")?;
1895         self.print_inner_attributes_inline(attrs)?;
1896         self.print_expr(element)?;
1897         self.word_space(";")?;
1898         self.print_expr(count)?;
1899         word(&mut self.s, "]")?;
1900         self.end()
1901     }
1902
1903     fn print_expr_struct(&mut self,
1904                          path: &ast::Path,
1905                          fields: &[ast::Field],
1906                          wth: &Option<P<ast::Expr>>,
1907                          attrs: &[Attribute]) -> io::Result<()> {
1908         self.print_path(path, true, 0, false)?;
1909         word(&mut self.s, "{")?;
1910         self.print_inner_attributes_inline(attrs)?;
1911         self.commasep_cmnt(
1912             Consistent,
1913             &fields[..],
1914             |s, field| {
1915                 s.ibox(INDENT_UNIT)?;
1916                 if !field.is_shorthand {
1917                     s.print_ident(field.ident.node)?;
1918                     s.word_space(":")?;
1919                 }
1920                 s.print_expr(&field.expr)?;
1921                 s.end()
1922             },
1923             |f| f.span)?;
1924         match *wth {
1925             Some(ref expr) => {
1926                 self.ibox(INDENT_UNIT)?;
1927                 if !fields.is_empty() {
1928                     word(&mut self.s, ",")?;
1929                     space(&mut self.s)?;
1930                 }
1931                 word(&mut self.s, "..")?;
1932                 self.print_expr(&expr)?;
1933                 self.end()?;
1934             }
1935             _ => if !fields.is_empty() {
1936                 word(&mut self.s, ",")?
1937             }
1938         }
1939         word(&mut self.s, "}")?;
1940         Ok(())
1941     }
1942
1943     fn print_expr_tup(&mut self, exprs: &[P<ast::Expr>],
1944                       attrs: &[Attribute]) -> io::Result<()> {
1945         self.popen()?;
1946         self.print_inner_attributes_inline(attrs)?;
1947         self.commasep_exprs(Inconsistent, &exprs[..])?;
1948         if exprs.len() == 1 {
1949             word(&mut self.s, ",")?;
1950         }
1951         self.pclose()
1952     }
1953
1954     fn print_expr_call(&mut self,
1955                        func: &ast::Expr,
1956                        args: &[P<ast::Expr>]) -> io::Result<()> {
1957         self.print_expr_maybe_paren(func)?;
1958         self.print_call_post(args)
1959     }
1960
1961     fn print_expr_method_call(&mut self,
1962                               ident: ast::SpannedIdent,
1963                               tys: &[P<ast::Ty>],
1964                               args: &[P<ast::Expr>]) -> io::Result<()> {
1965         let base_args = &args[1..];
1966         self.print_expr(&args[0])?;
1967         word(&mut self.s, ".")?;
1968         self.print_ident(ident.node)?;
1969         if !tys.is_empty() {
1970             word(&mut self.s, "::<")?;
1971             self.commasep(Inconsistent, tys,
1972                           |s, ty| s.print_type(&ty))?;
1973             word(&mut self.s, ">")?;
1974         }
1975         self.print_call_post(base_args)
1976     }
1977
1978     fn print_expr_binary(&mut self,
1979                          op: ast::BinOp,
1980                          lhs: &ast::Expr,
1981                          rhs: &ast::Expr) -> io::Result<()> {
1982         if self.check_expr_bin_needs_paren(lhs, op) {
1983             self.print_expr_maybe_paren(lhs)?;
1984         } else {
1985             self.print_expr(lhs)?;
1986         }
1987         space(&mut self.s)?;
1988         self.word_space(op.node.to_string())?;
1989         if self.check_expr_bin_needs_paren(rhs, op) {
1990             self.print_expr_maybe_paren(rhs)
1991         } else {
1992             self.print_expr(rhs)
1993         }
1994     }
1995
1996     fn print_expr_unary(&mut self,
1997                         op: ast::UnOp,
1998                         expr: &ast::Expr) -> io::Result<()> {
1999         word(&mut self.s, ast::UnOp::to_string(op))?;
2000         self.print_expr_maybe_paren(expr)
2001     }
2002
2003     fn print_expr_addr_of(&mut self,
2004                           mutability: ast::Mutability,
2005                           expr: &ast::Expr) -> io::Result<()> {
2006         word(&mut self.s, "&")?;
2007         self.print_mutability(mutability)?;
2008         self.print_expr_maybe_paren(expr)
2009     }
2010
2011     pub fn print_expr(&mut self, expr: &ast::Expr) -> io::Result<()> {
2012         self.print_expr_outer_attr_style(expr, true)
2013     }
2014
2015     fn print_expr_outer_attr_style(&mut self,
2016                                   expr: &ast::Expr,
2017                                   is_inline: bool) -> io::Result<()> {
2018         self.maybe_print_comment(expr.span.lo)?;
2019
2020         let attrs = &expr.attrs;
2021         if is_inline {
2022             self.print_outer_attributes_inline(attrs)?;
2023         } else {
2024             self.print_outer_attributes(attrs)?;
2025         }
2026
2027         self.ibox(INDENT_UNIT)?;
2028         self.ann.pre(self, NodeExpr(expr))?;
2029         match expr.node {
2030             ast::ExprKind::Box(ref expr) => {
2031                 self.word_space("box")?;
2032                 self.print_expr(expr)?;
2033             }
2034             ast::ExprKind::InPlace(ref place, ref expr) => {
2035                 self.print_expr_in_place(place, expr)?;
2036             }
2037             ast::ExprKind::Array(ref exprs) => {
2038                 self.print_expr_vec(&exprs[..], attrs)?;
2039             }
2040             ast::ExprKind::Repeat(ref element, ref count) => {
2041                 self.print_expr_repeat(&element, &count, attrs)?;
2042             }
2043             ast::ExprKind::Struct(ref path, ref fields, ref wth) => {
2044                 self.print_expr_struct(path, &fields[..], wth, attrs)?;
2045             }
2046             ast::ExprKind::Tup(ref exprs) => {
2047                 self.print_expr_tup(&exprs[..], attrs)?;
2048             }
2049             ast::ExprKind::Call(ref func, ref args) => {
2050                 self.print_expr_call(&func, &args[..])?;
2051             }
2052             ast::ExprKind::MethodCall(ident, ref tys, ref args) => {
2053                 self.print_expr_method_call(ident, &tys[..], &args[..])?;
2054             }
2055             ast::ExprKind::Binary(op, ref lhs, ref rhs) => {
2056                 self.print_expr_binary(op, &lhs, &rhs)?;
2057             }
2058             ast::ExprKind::Unary(op, ref expr) => {
2059                 self.print_expr_unary(op, &expr)?;
2060             }
2061             ast::ExprKind::AddrOf(m, ref expr) => {
2062                 self.print_expr_addr_of(m, &expr)?;
2063             }
2064             ast::ExprKind::Lit(ref lit) => {
2065                 self.print_literal(&lit)?;
2066             }
2067             ast::ExprKind::Cast(ref expr, ref ty) => {
2068                 if let ast::ExprKind::Cast(..) = expr.node {
2069                     self.print_expr(&expr)?;
2070                 } else {
2071                     self.print_expr_maybe_paren(&expr)?;
2072                 }
2073                 space(&mut self.s)?;
2074                 self.word_space("as")?;
2075                 self.print_type(&ty)?;
2076             }
2077             ast::ExprKind::Type(ref expr, ref ty) => {
2078                 self.print_expr(&expr)?;
2079                 self.word_space(":")?;
2080                 self.print_type(&ty)?;
2081             }
2082             ast::ExprKind::If(ref test, ref blk, ref elseopt) => {
2083                 self.print_if(&test, &blk, elseopt.as_ref().map(|e| &**e))?;
2084             }
2085             ast::ExprKind::IfLet(ref pat, ref expr, ref blk, ref elseopt) => {
2086                 self.print_if_let(&pat, &expr, &blk, elseopt.as_ref().map(|e| &**e))?;
2087             }
2088             ast::ExprKind::While(ref test, ref blk, opt_ident) => {
2089                 if let Some(ident) = opt_ident {
2090                     self.print_ident(ident.node)?;
2091                     self.word_space(":")?;
2092                 }
2093                 self.head("while")?;
2094                 self.print_expr(&test)?;
2095                 space(&mut self.s)?;
2096                 self.print_block_with_attrs(&blk, attrs)?;
2097             }
2098             ast::ExprKind::WhileLet(ref pat, ref expr, ref blk, opt_ident) => {
2099                 if let Some(ident) = opt_ident {
2100                     self.print_ident(ident.node)?;
2101                     self.word_space(":")?;
2102                 }
2103                 self.head("while let")?;
2104                 self.print_pat(&pat)?;
2105                 space(&mut self.s)?;
2106                 self.word_space("=")?;
2107                 self.print_expr(&expr)?;
2108                 space(&mut self.s)?;
2109                 self.print_block_with_attrs(&blk, attrs)?;
2110             }
2111             ast::ExprKind::ForLoop(ref pat, ref iter, ref blk, opt_ident) => {
2112                 if let Some(ident) = opt_ident {
2113                     self.print_ident(ident.node)?;
2114                     self.word_space(":")?;
2115                 }
2116                 self.head("for")?;
2117                 self.print_pat(&pat)?;
2118                 space(&mut self.s)?;
2119                 self.word_space("in")?;
2120                 self.print_expr(&iter)?;
2121                 space(&mut self.s)?;
2122                 self.print_block_with_attrs(&blk, attrs)?;
2123             }
2124             ast::ExprKind::Loop(ref blk, opt_ident) => {
2125                 if let Some(ident) = opt_ident {
2126                     self.print_ident(ident.node)?;
2127                     self.word_space(":")?;
2128                 }
2129                 self.head("loop")?;
2130                 space(&mut self.s)?;
2131                 self.print_block_with_attrs(&blk, attrs)?;
2132             }
2133             ast::ExprKind::Match(ref expr, ref arms) => {
2134                 self.cbox(INDENT_UNIT)?;
2135                 self.ibox(4)?;
2136                 self.word_nbsp("match")?;
2137                 self.print_expr(&expr)?;
2138                 space(&mut self.s)?;
2139                 self.bopen()?;
2140                 self.print_inner_attributes_no_trailing_hardbreak(attrs)?;
2141                 for arm in arms {
2142                     self.print_arm(arm)?;
2143                 }
2144                 self.bclose_(expr.span, INDENT_UNIT)?;
2145             }
2146             ast::ExprKind::Closure(capture_clause, ref decl, ref body, _) => {
2147                 self.print_capture_clause(capture_clause)?;
2148
2149                 self.print_fn_block_args(&decl)?;
2150                 space(&mut self.s)?;
2151                 self.print_expr(body)?;
2152                 self.end()?; // need to close a box
2153
2154                 // a box will be closed by print_expr, but we didn't want an overall
2155                 // wrapper so we closed the corresponding opening. so create an
2156                 // empty box to satisfy the close.
2157                 self.ibox(0)?;
2158             }
2159             ast::ExprKind::Block(ref blk) => {
2160                 // containing cbox, will be closed by print-block at }
2161                 self.cbox(INDENT_UNIT)?;
2162                 // head-box, will be closed by print-block after {
2163                 self.ibox(0)?;
2164                 self.print_block_with_attrs(&blk, attrs)?;
2165             }
2166             ast::ExprKind::Assign(ref lhs, ref rhs) => {
2167                 self.print_expr(&lhs)?;
2168                 space(&mut self.s)?;
2169                 self.word_space("=")?;
2170                 self.print_expr(&rhs)?;
2171             }
2172             ast::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
2173                 self.print_expr(&lhs)?;
2174                 space(&mut self.s)?;
2175                 word(&mut self.s, op.node.to_string())?;
2176                 self.word_space("=")?;
2177                 self.print_expr(&rhs)?;
2178             }
2179             ast::ExprKind::Field(ref expr, id) => {
2180                 self.print_expr(&expr)?;
2181                 word(&mut self.s, ".")?;
2182                 self.print_ident(id.node)?;
2183             }
2184             ast::ExprKind::TupField(ref expr, id) => {
2185                 self.print_expr(&expr)?;
2186                 word(&mut self.s, ".")?;
2187                 self.print_usize(id.node)?;
2188             }
2189             ast::ExprKind::Index(ref expr, ref index) => {
2190                 self.print_expr(&expr)?;
2191                 word(&mut self.s, "[")?;
2192                 self.print_expr(&index)?;
2193                 word(&mut self.s, "]")?;
2194             }
2195             ast::ExprKind::Range(ref start, ref end, limits) => {
2196                 if let &Some(ref e) = start {
2197                     self.print_expr(&e)?;
2198                 }
2199                 if limits == ast::RangeLimits::HalfOpen {
2200                     word(&mut self.s, "..")?;
2201                 } else {
2202                     word(&mut self.s, "...")?;
2203                 }
2204                 if let &Some(ref e) = end {
2205                     self.print_expr(&e)?;
2206                 }
2207             }
2208             ast::ExprKind::Path(None, ref path) => {
2209                 self.print_path(path, true, 0, false)?
2210             }
2211             ast::ExprKind::Path(Some(ref qself), ref path) => {
2212                 self.print_qpath(path, qself, true)?
2213             }
2214             ast::ExprKind::Break(opt_ident, ref opt_expr) => {
2215                 word(&mut self.s, "break")?;
2216                 space(&mut self.s)?;
2217                 if let Some(ident) = opt_ident {
2218                     self.print_ident(ident.node)?;
2219                     space(&mut self.s)?;
2220                 }
2221                 if let Some(ref expr) = *opt_expr {
2222                     self.print_expr(expr)?;
2223                     space(&mut self.s)?;
2224                 }
2225             }
2226             ast::ExprKind::Continue(opt_ident) => {
2227                 word(&mut self.s, "continue")?;
2228                 space(&mut self.s)?;
2229                 if let Some(ident) = opt_ident {
2230                     self.print_ident(ident.node)?;
2231                     space(&mut self.s)?
2232                 }
2233             }
2234             ast::ExprKind::Ret(ref result) => {
2235                 word(&mut self.s, "return")?;
2236                 match *result {
2237                     Some(ref expr) => {
2238                         word(&mut self.s, " ")?;
2239                         self.print_expr(&expr)?;
2240                     }
2241                     _ => ()
2242                 }
2243             }
2244             ast::ExprKind::InlineAsm(ref a) => {
2245                 word(&mut self.s, "asm!")?;
2246                 self.popen()?;
2247                 self.print_string(&a.asm.as_str(), a.asm_str_style)?;
2248                 self.word_space(":")?;
2249
2250                 self.commasep(Inconsistent, &a.outputs, |s, out| {
2251                     let constraint = out.constraint.as_str();
2252                     let mut ch = constraint.chars();
2253                     match ch.next() {
2254                         Some('=') if out.is_rw => {
2255                             s.print_string(&format!("+{}", ch.as_str()),
2256                                            ast::StrStyle::Cooked)?
2257                         }
2258                         _ => s.print_string(&constraint, ast::StrStyle::Cooked)?
2259                     }
2260                     s.popen()?;
2261                     s.print_expr(&out.expr)?;
2262                     s.pclose()?;
2263                     Ok(())
2264                 })?;
2265                 space(&mut self.s)?;
2266                 self.word_space(":")?;
2267
2268                 self.commasep(Inconsistent, &a.inputs, |s, &(co, ref o)| {
2269                     s.print_string(&co.as_str(), ast::StrStyle::Cooked)?;
2270                     s.popen()?;
2271                     s.print_expr(&o)?;
2272                     s.pclose()?;
2273                     Ok(())
2274                 })?;
2275                 space(&mut self.s)?;
2276                 self.word_space(":")?;
2277
2278                 self.commasep(Inconsistent, &a.clobbers,
2279                                    |s, co| {
2280                     s.print_string(&co.as_str(), ast::StrStyle::Cooked)?;
2281                     Ok(())
2282                 })?;
2283
2284                 let mut options = vec![];
2285                 if a.volatile {
2286                     options.push("volatile");
2287                 }
2288                 if a.alignstack {
2289                     options.push("alignstack");
2290                 }
2291                 if a.dialect == ast::AsmDialect::Intel {
2292                     options.push("intel");
2293                 }
2294
2295                 if !options.is_empty() {
2296                     space(&mut self.s)?;
2297                     self.word_space(":")?;
2298                     self.commasep(Inconsistent, &options,
2299                                   |s, &co| {
2300                                       s.print_string(co, ast::StrStyle::Cooked)?;
2301                                       Ok(())
2302                                   })?;
2303                 }
2304
2305                 self.pclose()?;
2306             }
2307             ast::ExprKind::Mac(ref m) => self.print_mac(m, token::Paren)?,
2308             ast::ExprKind::Paren(ref e) => {
2309                 self.popen()?;
2310                 self.print_inner_attributes_inline(attrs)?;
2311                 self.print_expr(&e)?;
2312                 self.pclose()?;
2313             },
2314             ast::ExprKind::Try(ref e) => {
2315                 self.print_expr(e)?;
2316                 word(&mut self.s, "?")?
2317             }
2318             ast::ExprKind::Catch(ref blk) => {
2319                 self.head("do catch")?;
2320                 space(&mut self.s)?;
2321                 self.print_block_with_attrs(&blk, attrs)?
2322             }
2323         }
2324         self.ann.post(self, NodeExpr(expr))?;
2325         self.end()
2326     }
2327
2328     pub fn print_local_decl(&mut self, loc: &ast::Local) -> io::Result<()> {
2329         self.print_pat(&loc.pat)?;
2330         if let Some(ref ty) = loc.ty {
2331             self.word_space(":")?;
2332             self.print_type(&ty)?;
2333         }
2334         Ok(())
2335     }
2336
2337     pub fn print_ident(&mut self, ident: ast::Ident) -> io::Result<()> {
2338         word(&mut self.s, &ident.name.as_str())?;
2339         self.ann.post(self, NodeIdent(&ident))
2340     }
2341
2342     pub fn print_usize(&mut self, i: usize) -> io::Result<()> {
2343         word(&mut self.s, &i.to_string())
2344     }
2345
2346     pub fn print_name(&mut self, name: ast::Name) -> io::Result<()> {
2347         word(&mut self.s, &name.as_str())?;
2348         self.ann.post(self, NodeName(&name))
2349     }
2350
2351     pub fn print_for_decl(&mut self, loc: &ast::Local,
2352                           coll: &ast::Expr) -> io::Result<()> {
2353         self.print_local_decl(loc)?;
2354         space(&mut self.s)?;
2355         self.word_space("in")?;
2356         self.print_expr(coll)
2357     }
2358
2359     fn print_path(&mut self,
2360                   path: &ast::Path,
2361                   colons_before_params: bool,
2362                   depth: usize,
2363                   defaults_to_global: bool)
2364                   -> io::Result<()>
2365     {
2366         self.maybe_print_comment(path.span.lo)?;
2367
2368         let mut segments = path.segments[..path.segments.len()-depth].iter();
2369         if defaults_to_global && path.is_global() {
2370             segments.next();
2371         }
2372         for (i, segment) in segments.enumerate() {
2373             if i > 0 {
2374                 word(&mut self.s, "::")?
2375             }
2376             if segment.identifier.name != keywords::CrateRoot.name() &&
2377                segment.identifier.name != "$crate" {
2378                 self.print_ident(segment.identifier)?;
2379                 if let Some(ref parameters) = segment.parameters {
2380                     self.print_path_parameters(parameters, colons_before_params)?;
2381                 }
2382             }
2383         }
2384
2385         Ok(())
2386     }
2387
2388     fn print_qpath(&mut self,
2389                    path: &ast::Path,
2390                    qself: &ast::QSelf,
2391                    colons_before_params: bool)
2392                    -> io::Result<()>
2393     {
2394         word(&mut self.s, "<")?;
2395         self.print_type(&qself.ty)?;
2396         if qself.position > 0 {
2397             space(&mut self.s)?;
2398             self.word_space("as")?;
2399             let depth = path.segments.len() - qself.position;
2400             self.print_path(&path, false, depth, false)?;
2401         }
2402         word(&mut self.s, ">")?;
2403         word(&mut self.s, "::")?;
2404         let item_segment = path.segments.last().unwrap();
2405         self.print_ident(item_segment.identifier)?;
2406         match item_segment.parameters {
2407             Some(ref parameters) => self.print_path_parameters(parameters, colons_before_params),
2408             None => Ok(()),
2409         }
2410     }
2411
2412     fn print_path_parameters(&mut self,
2413                              parameters: &ast::PathParameters,
2414                              colons_before_params: bool)
2415                              -> io::Result<()>
2416     {
2417         if colons_before_params {
2418             word(&mut self.s, "::")?
2419         }
2420
2421         match *parameters {
2422             ast::PathParameters::AngleBracketed(ref data) => {
2423                 word(&mut self.s, "<")?;
2424
2425                 let mut comma = false;
2426                 for lifetime in &data.lifetimes {
2427                     if comma {
2428                         self.word_space(",")?
2429                     }
2430                     self.print_lifetime(lifetime)?;
2431                     comma = true;
2432                 }
2433
2434                 if !data.types.is_empty() {
2435                     if comma {
2436                         self.word_space(",")?
2437                     }
2438                     self.commasep(
2439                         Inconsistent,
2440                         &data.types,
2441                         |s, ty| s.print_type(&ty))?;
2442                         comma = true;
2443                 }
2444
2445                 for binding in data.bindings.iter() {
2446                     if comma {
2447                         self.word_space(",")?
2448                     }
2449                     self.print_ident(binding.ident)?;
2450                     space(&mut self.s)?;
2451                     self.word_space("=")?;
2452                     self.print_type(&binding.ty)?;
2453                     comma = true;
2454                 }
2455
2456                 word(&mut self.s, ">")?
2457             }
2458
2459             ast::PathParameters::Parenthesized(ref data) => {
2460                 word(&mut self.s, "(")?;
2461                 self.commasep(
2462                     Inconsistent,
2463                     &data.inputs,
2464                     |s, ty| s.print_type(&ty))?;
2465                 word(&mut self.s, ")")?;
2466
2467                 if let Some(ref ty) = data.output {
2468                     self.space_if_not_bol()?;
2469                     self.word_space("->")?;
2470                     self.print_type(&ty)?;
2471                 }
2472             }
2473         }
2474
2475         Ok(())
2476     }
2477
2478     pub fn print_pat(&mut self, pat: &ast::Pat) -> io::Result<()> {
2479         self.maybe_print_comment(pat.span.lo)?;
2480         self.ann.pre(self, NodePat(pat))?;
2481         /* Pat isn't normalized, but the beauty of it
2482          is that it doesn't matter */
2483         match pat.node {
2484             PatKind::Wild => word(&mut self.s, "_")?,
2485             PatKind::Ident(binding_mode, ref path1, ref sub) => {
2486                 match binding_mode {
2487                     ast::BindingMode::ByRef(mutbl) => {
2488                         self.word_nbsp("ref")?;
2489                         self.print_mutability(mutbl)?;
2490                     }
2491                     ast::BindingMode::ByValue(ast::Mutability::Immutable) => {}
2492                     ast::BindingMode::ByValue(ast::Mutability::Mutable) => {
2493                         self.word_nbsp("mut")?;
2494                     }
2495                 }
2496                 self.print_ident(path1.node)?;
2497                 if let Some(ref p) = *sub {
2498                     word(&mut self.s, "@")?;
2499                     self.print_pat(&p)?;
2500                 }
2501             }
2502             PatKind::TupleStruct(ref path, ref elts, ddpos) => {
2503                 self.print_path(path, true, 0, false)?;
2504                 self.popen()?;
2505                 if let Some(ddpos) = ddpos {
2506                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p))?;
2507                     if ddpos != 0 {
2508                         self.word_space(",")?;
2509                     }
2510                     word(&mut self.s, "..")?;
2511                     if ddpos != elts.len() {
2512                         word(&mut self.s, ",")?;
2513                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p))?;
2514                     }
2515                 } else {
2516                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p))?;
2517                 }
2518                 self.pclose()?;
2519             }
2520             PatKind::Path(None, ref path) => {
2521                 self.print_path(path, true, 0, false)?;
2522             }
2523             PatKind::Path(Some(ref qself), ref path) => {
2524                 self.print_qpath(path, qself, false)?;
2525             }
2526             PatKind::Struct(ref path, ref fields, etc) => {
2527                 self.print_path(path, true, 0, false)?;
2528                 self.nbsp()?;
2529                 self.word_space("{")?;
2530                 self.commasep_cmnt(
2531                     Consistent, &fields[..],
2532                     |s, f| {
2533                         s.cbox(INDENT_UNIT)?;
2534                         if !f.node.is_shorthand {
2535                             s.print_ident(f.node.ident)?;
2536                             s.word_nbsp(":")?;
2537                         }
2538                         s.print_pat(&f.node.pat)?;
2539                         s.end()
2540                     },
2541                     |f| f.node.pat.span)?;
2542                 if etc {
2543                     if !fields.is_empty() { self.word_space(",")?; }
2544                     word(&mut self.s, "..")?;
2545                 }
2546                 space(&mut self.s)?;
2547                 word(&mut self.s, "}")?;
2548             }
2549             PatKind::Tuple(ref elts, ddpos) => {
2550                 self.popen()?;
2551                 if let Some(ddpos) = ddpos {
2552                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p))?;
2553                     if ddpos != 0 {
2554                         self.word_space(",")?;
2555                     }
2556                     word(&mut self.s, "..")?;
2557                     if ddpos != elts.len() {
2558                         word(&mut self.s, ",")?;
2559                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p))?;
2560                     }
2561                 } else {
2562                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p))?;
2563                     if elts.len() == 1 {
2564                         word(&mut self.s, ",")?;
2565                     }
2566                 }
2567                 self.pclose()?;
2568             }
2569             PatKind::Box(ref inner) => {
2570                 word(&mut self.s, "box ")?;
2571                 self.print_pat(&inner)?;
2572             }
2573             PatKind::Ref(ref inner, mutbl) => {
2574                 word(&mut self.s, "&")?;
2575                 if mutbl == ast::Mutability::Mutable {
2576                     word(&mut self.s, "mut ")?;
2577                 }
2578                 self.print_pat(&inner)?;
2579             }
2580             PatKind::Lit(ref e) => self.print_expr(&**e)?,
2581             PatKind::Range(ref begin, ref end, ref end_kind) => {
2582                 self.print_expr(&begin)?;
2583                 space(&mut self.s)?;
2584                 match *end_kind {
2585                     RangeEnd::Included => word(&mut self.s, "...")?,
2586                     RangeEnd::Excluded => word(&mut self.s, "..")?,
2587                 }
2588                 self.print_expr(&end)?;
2589             }
2590             PatKind::Slice(ref before, ref slice, ref after) => {
2591                 word(&mut self.s, "[")?;
2592                 self.commasep(Inconsistent,
2593                                    &before[..],
2594                                    |s, p| s.print_pat(&p))?;
2595                 if let Some(ref p) = *slice {
2596                     if !before.is_empty() { self.word_space(",")?; }
2597                     if p.node != PatKind::Wild {
2598                         self.print_pat(&p)?;
2599                     }
2600                     word(&mut self.s, "..")?;
2601                     if !after.is_empty() { self.word_space(",")?; }
2602                 }
2603                 self.commasep(Inconsistent,
2604                                    &after[..],
2605                                    |s, p| s.print_pat(&p))?;
2606                 word(&mut self.s, "]")?;
2607             }
2608             PatKind::Mac(ref m) => self.print_mac(m, token::Paren)?,
2609         }
2610         self.ann.post(self, NodePat(pat))
2611     }
2612
2613     fn print_arm(&mut self, arm: &ast::Arm) -> io::Result<()> {
2614         // I have no idea why this check is necessary, but here it
2615         // is :(
2616         if arm.attrs.is_empty() {
2617             space(&mut self.s)?;
2618         }
2619         self.cbox(INDENT_UNIT)?;
2620         self.ibox(0)?;
2621         self.maybe_print_comment(arm.pats[0].span.lo)?;
2622         self.print_outer_attributes(&arm.attrs)?;
2623         let mut first = true;
2624         for p in &arm.pats {
2625             if first {
2626                 first = false;
2627             } else {
2628                 space(&mut self.s)?;
2629                 self.word_space("|")?;
2630             }
2631             self.print_pat(&p)?;
2632         }
2633         space(&mut self.s)?;
2634         if let Some(ref e) = arm.guard {
2635             self.word_space("if")?;
2636             self.print_expr(&e)?;
2637             space(&mut self.s)?;
2638         }
2639         self.word_space("=>")?;
2640
2641         match arm.body.node {
2642             ast::ExprKind::Block(ref blk) => {
2643                 // the block will close the pattern's ibox
2644                 self.print_block_unclosed_indent(&blk, INDENT_UNIT)?;
2645
2646                 // If it is a user-provided unsafe block, print a comma after it
2647                 if let BlockCheckMode::Unsafe(ast::UserProvided) = blk.rules {
2648                     word(&mut self.s, ",")?;
2649                 }
2650             }
2651             _ => {
2652                 self.end()?; // close the ibox for the pattern
2653                 self.print_expr(&arm.body)?;
2654                 word(&mut self.s, ",")?;
2655             }
2656         }
2657         self.end() // close enclosing cbox
2658     }
2659
2660     fn print_explicit_self(&mut self, explicit_self: &ast::ExplicitSelf) -> io::Result<()> {
2661         match explicit_self.node {
2662             SelfKind::Value(m) => {
2663                 self.print_mutability(m)?;
2664                 word(&mut self.s, "self")
2665             }
2666             SelfKind::Region(ref lt, m) => {
2667                 word(&mut self.s, "&")?;
2668                 self.print_opt_lifetime(lt)?;
2669                 self.print_mutability(m)?;
2670                 word(&mut self.s, "self")
2671             }
2672             SelfKind::Explicit(ref typ, m) => {
2673                 self.print_mutability(m)?;
2674                 word(&mut self.s, "self")?;
2675                 self.word_space(":")?;
2676                 self.print_type(&typ)
2677             }
2678         }
2679     }
2680
2681     pub fn print_fn(&mut self,
2682                     decl: &ast::FnDecl,
2683                     unsafety: ast::Unsafety,
2684                     constness: ast::Constness,
2685                     abi: abi::Abi,
2686                     name: Option<ast::Ident>,
2687                     generics: &ast::Generics,
2688                     vis: &ast::Visibility) -> io::Result<()> {
2689         self.print_fn_header_info(unsafety, constness, abi, vis)?;
2690
2691         if let Some(name) = name {
2692             self.nbsp()?;
2693             self.print_ident(name)?;
2694         }
2695         self.print_generics(generics)?;
2696         self.print_fn_args_and_ret(decl)?;
2697         self.print_where_clause(&generics.where_clause)
2698     }
2699
2700     pub fn print_fn_args_and_ret(&mut self, decl: &ast::FnDecl)
2701         -> io::Result<()> {
2702         self.popen()?;
2703         self.commasep(Inconsistent, &decl.inputs, |s, arg| s.print_arg(arg, false))?;
2704         if decl.variadic {
2705             word(&mut self.s, ", ...")?;
2706         }
2707         self.pclose()?;
2708
2709         self.print_fn_output(decl)
2710     }
2711
2712     pub fn print_fn_block_args(
2713             &mut self,
2714             decl: &ast::FnDecl)
2715             -> io::Result<()> {
2716         word(&mut self.s, "|")?;
2717         self.commasep(Inconsistent, &decl.inputs, |s, arg| s.print_arg(arg, true))?;
2718         word(&mut self.s, "|")?;
2719
2720         if let ast::FunctionRetTy::Default(..) = decl.output {
2721             return Ok(());
2722         }
2723
2724         self.space_if_not_bol()?;
2725         self.word_space("->")?;
2726         match decl.output {
2727             ast::FunctionRetTy::Ty(ref ty) => {
2728                 self.print_type(&ty)?;
2729                 self.maybe_print_comment(ty.span.lo)
2730             }
2731             ast::FunctionRetTy::Default(..) => unreachable!(),
2732         }
2733     }
2734
2735     pub fn print_capture_clause(&mut self, capture_clause: ast::CaptureBy)
2736                                 -> io::Result<()> {
2737         match capture_clause {
2738             ast::CaptureBy::Value => self.word_space("move"),
2739             ast::CaptureBy::Ref => Ok(()),
2740         }
2741     }
2742
2743     pub fn print_bounds(&mut self,
2744                         prefix: &str,
2745                         bounds: &[ast::TyParamBound])
2746                         -> io::Result<()> {
2747         if !bounds.is_empty() {
2748             word(&mut self.s, prefix)?;
2749             let mut first = true;
2750             for bound in bounds {
2751                 self.nbsp()?;
2752                 if first {
2753                     first = false;
2754                 } else {
2755                     self.word_space("+")?;
2756                 }
2757
2758                 (match *bound {
2759                     TraitTyParamBound(ref tref, TraitBoundModifier::None) => {
2760                         self.print_poly_trait_ref(tref)
2761                     }
2762                     TraitTyParamBound(ref tref, TraitBoundModifier::Maybe) => {
2763                         word(&mut self.s, "?")?;
2764                         self.print_poly_trait_ref(tref)
2765                     }
2766                     RegionTyParamBound(ref lt) => {
2767                         self.print_lifetime(lt)
2768                     }
2769                 })?
2770             }
2771             Ok(())
2772         } else {
2773             Ok(())
2774         }
2775     }
2776
2777     pub fn print_lifetime(&mut self,
2778                           lifetime: &ast::Lifetime)
2779                           -> io::Result<()>
2780     {
2781         self.print_name(lifetime.name)
2782     }
2783
2784     pub fn print_lifetime_bounds(&mut self,
2785                                  lifetime: &ast::Lifetime,
2786                                  bounds: &[ast::Lifetime])
2787                                  -> io::Result<()>
2788     {
2789         self.print_lifetime(lifetime)?;
2790         if !bounds.is_empty() {
2791             word(&mut self.s, ": ")?;
2792             for (i, bound) in bounds.iter().enumerate() {
2793                 if i != 0 {
2794                     word(&mut self.s, " + ")?;
2795                 }
2796                 self.print_lifetime(bound)?;
2797             }
2798         }
2799         Ok(())
2800     }
2801
2802     pub fn print_generics(&mut self,
2803                           generics: &ast::Generics)
2804                           -> io::Result<()>
2805     {
2806         let total = generics.lifetimes.len() + generics.ty_params.len();
2807         if total == 0 {
2808             return Ok(());
2809         }
2810
2811         word(&mut self.s, "<")?;
2812
2813         let mut ints = Vec::new();
2814         for i in 0..total {
2815             ints.push(i);
2816         }
2817
2818         self.commasep(Inconsistent, &ints[..], |s, &idx| {
2819             if idx < generics.lifetimes.len() {
2820                 let lifetime_def = &generics.lifetimes[idx];
2821                 s.print_outer_attributes_inline(&lifetime_def.attrs)?;
2822                 s.print_lifetime_bounds(&lifetime_def.lifetime, &lifetime_def.bounds)
2823             } else {
2824                 let idx = idx - generics.lifetimes.len();
2825                 let param = &generics.ty_params[idx];
2826                 s.print_ty_param(param)
2827             }
2828         })?;
2829
2830         word(&mut self.s, ">")?;
2831         Ok(())
2832     }
2833
2834     pub fn print_ty_param(&mut self, param: &ast::TyParam) -> io::Result<()> {
2835         self.print_outer_attributes_inline(&param.attrs)?;
2836         self.print_ident(param.ident)?;
2837         self.print_bounds(":", &param.bounds)?;
2838         match param.default {
2839             Some(ref default) => {
2840                 space(&mut self.s)?;
2841                 self.word_space("=")?;
2842                 self.print_type(&default)
2843             }
2844             _ => Ok(())
2845         }
2846     }
2847
2848     pub fn print_where_clause(&mut self, where_clause: &ast::WhereClause)
2849                               -> io::Result<()> {
2850         if where_clause.predicates.is_empty() {
2851             return Ok(())
2852         }
2853
2854         space(&mut self.s)?;
2855         self.word_space("where")?;
2856
2857         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2858             if i != 0 {
2859                 self.word_space(",")?;
2860             }
2861
2862             match *predicate {
2863                 ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate{ref bound_lifetimes,
2864                                                                              ref bounded_ty,
2865                                                                              ref bounds,
2866                                                                              ..}) => {
2867                     self.print_formal_lifetime_list(bound_lifetimes)?;
2868                     self.print_type(&bounded_ty)?;
2869                     self.print_bounds(":", bounds)?;
2870                 }
2871                 ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate{ref lifetime,
2872                                                                                ref bounds,
2873                                                                                ..}) => {
2874                     self.print_lifetime_bounds(lifetime, bounds)?;
2875                 }
2876                 ast::WherePredicate::EqPredicate(ast::WhereEqPredicate{ref lhs_ty,
2877                                                                        ref rhs_ty,
2878                                                                        ..}) => {
2879                     self.print_type(lhs_ty)?;
2880                     space(&mut self.s)?;
2881                     self.word_space("=")?;
2882                     self.print_type(rhs_ty)?;
2883                 }
2884             }
2885         }
2886
2887         Ok(())
2888     }
2889
2890     pub fn print_view_path(&mut self, vp: &ast::ViewPath) -> io::Result<()> {
2891         match vp.node {
2892             ast::ViewPathSimple(ident, ref path) => {
2893                 self.print_path(path, false, 0, true)?;
2894
2895                 if path.segments.last().unwrap().identifier.name !=
2896                         ident.name {
2897                     space(&mut self.s)?;
2898                     self.word_space("as")?;
2899                     self.print_ident(ident)?;
2900                 }
2901
2902                 Ok(())
2903             }
2904
2905             ast::ViewPathGlob(ref path) => {
2906                 self.print_path(path, false, 0, true)?;
2907                 word(&mut self.s, "::*")
2908             }
2909
2910             ast::ViewPathList(ref path, ref idents) => {
2911                 if path.segments.is_empty() {
2912                     word(&mut self.s, "{")?;
2913                 } else {
2914                     self.print_path(path, false, 0, true)?;
2915                     word(&mut self.s, "::{")?;
2916                 }
2917                 self.commasep(Inconsistent, &idents[..], |s, w| {
2918                     s.print_ident(w.node.name)?;
2919                     if let Some(ident) = w.node.rename {
2920                         space(&mut s.s)?;
2921                         s.word_space("as")?;
2922                         s.print_ident(ident)?;
2923                     }
2924                     Ok(())
2925                 })?;
2926                 word(&mut self.s, "}")
2927             }
2928         }
2929     }
2930
2931     pub fn print_mutability(&mut self,
2932                             mutbl: ast::Mutability) -> io::Result<()> {
2933         match mutbl {
2934             ast::Mutability::Mutable => self.word_nbsp("mut"),
2935             ast::Mutability::Immutable => Ok(()),
2936         }
2937     }
2938
2939     pub fn print_mt(&mut self, mt: &ast::MutTy) -> io::Result<()> {
2940         self.print_mutability(mt.mutbl)?;
2941         self.print_type(&mt.ty)
2942     }
2943
2944     pub fn print_arg(&mut self, input: &ast::Arg, is_closure: bool) -> io::Result<()> {
2945         self.ibox(INDENT_UNIT)?;
2946         match input.ty.node {
2947             ast::TyKind::Infer if is_closure => self.print_pat(&input.pat)?,
2948             _ => {
2949                 if let Some(eself) = input.to_self() {
2950                     self.print_explicit_self(&eself)?;
2951                 } else {
2952                     let invalid = if let PatKind::Ident(_, ident, _) = input.pat.node {
2953                         ident.node.name == keywords::Invalid.name()
2954                     } else {
2955                         false
2956                     };
2957                     if !invalid {
2958                         self.print_pat(&input.pat)?;
2959                         word(&mut self.s, ":")?;
2960                         space(&mut self.s)?;
2961                     }
2962                     self.print_type(&input.ty)?;
2963                 }
2964             }
2965         }
2966         self.end()
2967     }
2968
2969     pub fn print_fn_output(&mut self, decl: &ast::FnDecl) -> io::Result<()> {
2970         if let ast::FunctionRetTy::Default(..) = decl.output {
2971             return Ok(());
2972         }
2973
2974         self.space_if_not_bol()?;
2975         self.ibox(INDENT_UNIT)?;
2976         self.word_space("->")?;
2977         match decl.output {
2978             ast::FunctionRetTy::Default(..) => unreachable!(),
2979             ast::FunctionRetTy::Ty(ref ty) =>
2980                 self.print_type(&ty)?
2981         }
2982         self.end()?;
2983
2984         match decl.output {
2985             ast::FunctionRetTy::Ty(ref output) => self.maybe_print_comment(output.span.lo),
2986             _ => Ok(())
2987         }
2988     }
2989
2990     pub fn print_ty_fn(&mut self,
2991                        abi: abi::Abi,
2992                        unsafety: ast::Unsafety,
2993                        decl: &ast::FnDecl,
2994                        name: Option<ast::Ident>,
2995                        generics: &ast::Generics)
2996                        -> io::Result<()> {
2997         self.ibox(INDENT_UNIT)?;
2998         if !generics.lifetimes.is_empty() || !generics.ty_params.is_empty() {
2999             word(&mut self.s, "for")?;
3000             self.print_generics(generics)?;
3001         }
3002         let generics = ast::Generics {
3003             lifetimes: Vec::new(),
3004             ty_params: Vec::new(),
3005             where_clause: ast::WhereClause {
3006                 id: ast::DUMMY_NODE_ID,
3007                 predicates: Vec::new(),
3008             },
3009             span: syntax_pos::DUMMY_SP,
3010         };
3011         self.print_fn(decl,
3012                       unsafety,
3013                       ast::Constness::NotConst,
3014                       abi,
3015                       name,
3016                       &generics,
3017                       &ast::Visibility::Inherited)?;
3018         self.end()
3019     }
3020
3021     pub fn maybe_print_trailing_comment(&mut self, span: syntax_pos::Span,
3022                                         next_pos: Option<BytePos>)
3023         -> io::Result<()> {
3024         let cm = match self.cm {
3025             Some(cm) => cm,
3026             _ => return Ok(())
3027         };
3028         if let Some(ref cmnt) = self.next_comment() {
3029             if cmnt.style != comments::Trailing { return Ok(()) }
3030             let span_line = cm.lookup_char_pos(span.hi);
3031             let comment_line = cm.lookup_char_pos(cmnt.pos);
3032             let next = next_pos.unwrap_or(cmnt.pos + BytePos(1));
3033             if span.hi < cmnt.pos && cmnt.pos < next && span_line.line == comment_line.line {
3034                 self.print_comment(cmnt)?;
3035                 self.cur_cmnt_and_lit.cur_cmnt += 1;
3036             }
3037         }
3038         Ok(())
3039     }
3040
3041     pub fn print_remaining_comments(&mut self) -> io::Result<()> {
3042         // If there aren't any remaining comments, then we need to manually
3043         // make sure there is a line break at the end.
3044         if self.next_comment().is_none() {
3045             hardbreak(&mut self.s)?;
3046         }
3047         loop {
3048             match self.next_comment() {
3049                 Some(ref cmnt) => {
3050                     self.print_comment(cmnt)?;
3051                     self.cur_cmnt_and_lit.cur_cmnt += 1;
3052                 }
3053                 _ => break
3054             }
3055         }
3056         Ok(())
3057     }
3058
3059     pub fn print_opt_abi_and_extern_if_nondefault(&mut self,
3060                                                   opt_abi: Option<Abi>)
3061         -> io::Result<()> {
3062         match opt_abi {
3063             Some(Abi::Rust) => Ok(()),
3064             Some(abi) => {
3065                 self.word_nbsp("extern")?;
3066                 self.word_nbsp(&abi.to_string())
3067             }
3068             None => Ok(())
3069         }
3070     }
3071
3072     pub fn print_extern_opt_abi(&mut self,
3073                                 opt_abi: Option<Abi>) -> io::Result<()> {
3074         match opt_abi {
3075             Some(abi) => {
3076                 self.word_nbsp("extern")?;
3077                 self.word_nbsp(&abi.to_string())
3078             }
3079             None => Ok(())
3080         }
3081     }
3082
3083     pub fn print_fn_header_info(&mut self,
3084                                 unsafety: ast::Unsafety,
3085                                 constness: ast::Constness,
3086                                 abi: Abi,
3087                                 vis: &ast::Visibility) -> io::Result<()> {
3088         word(&mut self.s, &visibility_qualified(vis, ""))?;
3089
3090         match constness {
3091             ast::Constness::NotConst => {}
3092             ast::Constness::Const => self.word_nbsp("const")?
3093         }
3094
3095         self.print_unsafety(unsafety)?;
3096
3097         if abi != Abi::Rust {
3098             self.word_nbsp("extern")?;
3099             self.word_nbsp(&abi.to_string())?;
3100         }
3101
3102         word(&mut self.s, "fn")
3103     }
3104
3105     pub fn print_unsafety(&mut self, s: ast::Unsafety) -> io::Result<()> {
3106         match s {
3107             ast::Unsafety::Normal => Ok(()),
3108             ast::Unsafety::Unsafe => self.word_nbsp("unsafe"),
3109         }
3110     }
3111 }
3112
3113 fn repeat(s: &str, n: usize) -> String { iter::repeat(s).take(n).collect() }
3114
3115 #[cfg(test)]
3116 mod tests {
3117     use super::*;
3118
3119     use ast;
3120     use codemap;
3121     use syntax_pos;
3122
3123     #[test]
3124     fn test_fun_to_string() {
3125         let abba_ident = ast::Ident::from_str("abba");
3126
3127         let decl = ast::FnDecl {
3128             inputs: Vec::new(),
3129             output: ast::FunctionRetTy::Default(syntax_pos::DUMMY_SP),
3130             variadic: false
3131         };
3132         let generics = ast::Generics::default();
3133         assert_eq!(fun_to_string(&decl, ast::Unsafety::Normal,
3134                                  ast::Constness::NotConst,
3135                                  abba_ident, &generics),
3136                    "fn abba()");
3137     }
3138
3139     #[test]
3140     fn test_variant_to_string() {
3141         let ident = ast::Ident::from_str("principal_skinner");
3142
3143         let var = codemap::respan(syntax_pos::DUMMY_SP, ast::Variant_ {
3144             name: ident,
3145             attrs: Vec::new(),
3146             // making this up as I go.... ?
3147             data: ast::VariantData::Unit(ast::DUMMY_NODE_ID),
3148             disr_expr: None,
3149         });
3150
3151         let varstr = variant_to_string(&var);
3152         assert_eq!(varstr, "principal_skinner");
3153     }
3154 }